The growth and differentiation of normal cells are controlled by protein-tyrosine kinases, which serve as receptors for a wide variety of external signals. Small protein modules called Src homology 2 (SH2) and SH3 domains mediate protein-protein interactions in signaling pathways that are triggered by protein tyrosine kinases. The SH2 domain, a protein module of around 100 amino acids, is present in tyrosine kinase targets within the cell. SH2 domains are recruited to activated and autophosphorylated growth factor receptors by directly recognizing tyrosine phosphorylation sites. Growth factor receptors and other phosphoproteins have short phosphotyrosine (pTyr)-containing sequences that are bound by SH2 domains. The SH3 domain, a distinct element of approximately 50 residues that recognizes proline-rich and hydrophobic-amino-acid-containing regions, is frequently found in SH2-containing proteins. Tyrosine kinases can be coupled to downstream targets with SH3-binding sites by proteins with SH2 and SH3 domains acting as adaptors. These intricate and precise biochemical signaling pathways result in the regulation of gene expression, cytoskeletal architecture, and cell metabolism. The role of SH2/SH3 proteins in T cell signaling will be discussed. A special focus will be on the role of the hematopoietic signal transducer with SH2/SH3 domains, Vav1, in health and cancer.

Linker for activation of T cells (LAT) is a central adaptor protein in proximal T cell activation. A key element of its adaptor function is the efficiency with which LAT interacts with its binding partners. Such efficiency is controlled by the local concentration of LAT as well as the vicinity to up- and downstream interaction partners, i.e. LAT localization. Several factors control LAT localization. LAT is a palmitoylated transmembrane protein and traffics between vesicular compartments and the plasma membrane. Membrane heterogeneity and protein-protein interactions can drive LAT clustering, at scales from a few to hundreds if not more molecules. LAT vesicular trafficking through the small, crowded cytoplasm of a T cell and the commonly nm scale clusters are difficult to access experimentally, in particular in the physiological interaction of T cells binding to antigen presenting cells (APCs) with a highly undulating interface. Only in recent years have technological advances begun to provide better access. Based on such advances, three elements of LAT localization are discussed in conjunction: vesicular trafficking as it regulates LAT transport towards, insertion into, and removal from the plasma membrane; LAT clustering as it increases local LAT concentrations; LAT-anchored supramolecular signaling complexes as they embed LAT in a dense network of interaction partners. Consistent with the important role of LAT localization for its function, each of these processes regulates LAT activity and the efficiency of T cell activation.

Surgery, chemotherapy, radiation therapy, and immunotherapy are potential therapeutic choices for many malignant and metastatic cancers. Despite adverse side effects and pain, surgery and chemotherapy continue to be the most common cancer treatments. However, patients treated with immunotherapy had better cancer control than those who got other treatments. There are two methods to activate immunological pathways: systemically and locally. To modify the tumor microenvironment (TME), the former uses systemic cytokine/chemokine (CK) delivery, whilst the latter uses immunological checkpoints or small molecule inhibitors. Organic and inorganic nanomaterials (NMs) enhanced the efficacy of cancer immunotherapy. NMs can transmit drugs, peptides, antigens, antibodies, whole cell membranes, etc. Surface-modified NMs precisely target and enter the tissues. The inner core of surface-modified NMs is composed of chemicals with limited bioavailability and biocompatibility, resulting in prolonged blood retention and decreased renal clearance. These platforms hinder or prevent many immune cell activities and modify the TME, enhancing the efficiency of cancer immunotherapy. By inhibiting CK/CK receptor signaling, cell migration and other immune responses could be controlled. Developing CK-targeted nanoparticles (NPs) that inhibit CK signaling or take advantage of the ligand-receptor connection is possible. Surface chemical modification of NMs with CKs or specific peptides has several medicinal applications, including tissue-specific drug delivery and limited cell migration in cancer-afflicted conditions. This review covers current developments in the role of different groups of CK-loaded NP in tumor therapy targeting immune cells and cancer. It also covers the role of NP targeting CK signaling which aids in immunogenic cell death (ICD) and induction of antitumor immunity. In addition, CK gene silencing and its capacity to prevent cancer metastasis as well as inhibition of immune cell migration to modulate the TME are discussed.

Mesenchymal stem/stromal cells (MSCs) are known as multipotent cells due to their ability to differentiate into various cell lineages of mesoderm origin. Recent developments in stem cell biology have provided a new ray of hope for the treatment of diseases and disorders that are yet to be treated. These cells have been widely used in animals and clinical trials in humans. To date, there are more than 920 clinical trials on humans related to MSCs as cell-based therapy in various conditions. The purpose of this review is to provide a summary of the characteristics of MSCs, evaluate their immunological properties, activation of MSCs that dictate their soluble factors, possible pathway, and mechanisms involved by MSCs and immune cell interaction, and various application of MSCs in different diseases.

In the last years, multiple efforts have been made to accurately predict neoantigens derived from somatic mutations in cancer patients, either to develop personalized therapeutic vaccines or to study immune responses after cancer immunotherapy. In this context, the increasing accessibility of paired whole-exome sequencing (WES) of tumor biopsies and matched normal tissue as well as RNA sequencing (RNA-Seq) has provided a basis for the development of bioinformatics tools that predict and prioritize neoantigen candidates. Most pipelines rely on the binding prediction of candidate peptides to the patient’s major histocompatibility complex (MHC), but these methods return a high number of false positives since they lack information related to other features that influence T cell responses to neoantigens. This review explores available computational methods that incorporate information on T cell preferences to predict their activation after encountering a peptide-MHC complex. Specifically, methods that predict i) biological features that may increase the availability of a neopeptide to be exposed to the immune system, ii) metrics of self-similarity representing the chances of a neoantigen to break immune tolerance, iii) pathogen immunogenicity, and iv) tumor immunogenicity. Also, this review describes the characteristics of these tools and addresses their performance in the context of a novel benchmark dataset of experimentally validated neoantigens from patients treated with a melanoma vaccine (VACCIMEL) in a phase II clinical study. The overall results of the evaluation indicate that current tools have a limited ability to predict the activation of a cytotoxic response against neoantigens. Based on this result, the limitations that make this problem an unsolved challenge in immunoinformatics are discussed.

Lung cancer is the leading cause of cancer-related deaths worldwide. The main risk factor for lung cancer is exposure to chemicals present in cigarettes and atmospheric pollutants, which, among other mechanisms, can increase the risk of cancer by inducing pulmonary inflammation. Among the complex features of inflammatory processes, the role of inflammasomes has attracted increasing attention due to their role in different stages of carcinogenesis. Inflammasomes are intracellular multiprotein complexes that when activated promote the maturation of interleukin-1beta (IL-1β) and IL-18, pro-inflammatory cytokines involved in the promotion, progression, epithelial-mesenchymal transition, metastasis, and resistance to therapy of lung cancer. In this way, this review summarizes the recent findings of inflammasome research in different stages of lung cancer, with a focus on non-small cell lung carcinoma (NSCLC), and highlights these multiprotein complexes as promising targets for cancer therapy.

The infection of COVID-19 is directly linked to the destruction of lung epithelial cells, and the cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) system has been implicated in the pathology of respiratory infections. This study aimed to systematize the relationship between the pathophysiology of COVID-19 and the cGAS-STING system’s activation in the lungs. Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is an RNA virus that belongs to the Coronaviridae family whose genetic material is produced by a single positive RNA molecule (RNA+). The cGAS-STING signaling pathway has emerged as a key mediator of injury caused by infection and cellular or tissue stress. The cGAS-STING cyclic pathway is part of innate immunity and is activated from cytosolic DNA responses present in newly formed syncytia, by cell-to-cell fusion, in target of angiotensin-converting enzyme 2 (ACE2) expression and SARS-CoV-2 Spike protein. Although this pathway is canonically understood to be responsive to both pathogen-derived and host-derived DNA, it has been demonstrated to cross-communicate with the retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs). cGAS-STING activation is significant to interferon production, mainly type-I interferons (IFN-I), in a SARS-CoV-2 infection scenario, indicating a major antiviral role of the cGAS-STING pathway. It was identified that in SARS-CoV-2 the cGAS-STING axis is activated, but the inflammatory response could be specific for nuclear factor-κB (NF-κB) in infected cells, and that this axis is potentiated by a cytokine storm produced by the immune system’s cells.

Tumor necrosis factor receptor (TNFR)-associated factors (TRAFs) are a family of intracellular signaling adaptors that associate with the cytoplasmic tails of a diverse range of lymphocyte receptors, including members of the TNFR superfamily, the Toll-like receptor (TLR)/interleukin-1 (IL-1) receptor superfamily, and the IL-6 receptor family that are major targets for therapeutic intervention for inflammatory diseases. TRAF5 is one of the seven family members of the TRAF family and is highly expressed by B- and T-lymphocytes. As compared to other family members, the biological and pathophysiological functions of TRAF5 have remained ambiguous since its discovery. TRAF5 promotes lymphocyte signaling for the TNFR family molecules such as glucocorticoid-induced TNFR family-related protein (GITR), CD27, and CD40. In contrast, TRAF5 limits the activity of the common signaling receptor subunit glycoprotein 130 kDa (gp130) in CD4⁺ T cells that requires signaling by IL-6 and IL-27. TRAF5 also restrains TLR signaling in B cells. Thus, TRAF5 regulates lymphocyte signaling in both positive and negative ways. This review will summarize the findings of recent studies of TRAF5 in terms of how TRAF5 regulates signaling in lymphocytes and other cell types and how TRAF5 expression contributes to inflammatory and autoimmune diseases in mice and humans.

Coronavirus disease caused by the recently emerged severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represents a major public health that has submerged the world into a crisis unprecedented in the modern era. A better understanding of the innate immune response could help to fight this pandemic and be better prepared for potential future outbreaks. Interestingly, innate immune cells can develop a non-specific memory termed trained immunity. This review details recent evidence concerning the interaction of SARS-CoV-2 with innate immune cells, in particular those in which the trained immunity activity has been demonstrated.

Human cytomegalovirus (HCMV), whose genome is around 235 kb, is a ubiquitous human herpesvirus that infects between 40% and 95% of the population. Though HCMV infection is commonly asymptomatic and leads to subtle clinical symptoms, it can promote robust immune responses and establish lifelong latency. In addition, in immunocompromised hosts, including individuals with acquired immunodeficiency syndrome (AIDS), transplant recipients, and developing fetuses it can lead to severe diseases. Immunosenescence, well-defined as the alterations in the immune system, is linked mainly to aging and has been recently gathering considerable attention. Senescence was characterized by an elevated inflammation and hence considered a powerful contributor to “inflammaging” that is measured mainly by tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and C-reactive protein (CRP) levels as well as latent viral infections, for instance, cytomegalovirus (CMV). Inflammaging resulted in a senescence-associated secretory phenotype (SASP). HCMV is markedly associated with accelerated aging of the immune system as well as several age-associated diseases that accumulate and subsequently deteriorate the immune responses, thus have been linked to mortality, declined vaccine efficacy, serious diseases, and tumors in the elderly. HCMV triggers or exacerbates immunosenescence; on the other hand, the weakened immune responses and inflammaging favor viral reactivation and highlight the role of HCMV in aging as well as viral-associated tumors. HCMV reactivation resulting in sequential lytic and latent viral cycles could contribute to HCMV genomic variability. Besides the oncomodulatory role and transforming capacities of HCMV, the immune-privileged tumor microenvironment has been considered the main element in tumor progression and aggressiveness. Therefore, the interplay between HCMV, immunosenescence, and cancer will aid in discovering new therapeutic approaches that target HCMV and act as immune response boosters mainly to fight cancers of poor prognosis, particularly in the elderly population.

Immunoinformatics is an emerging area focused on development and applications of methods used to facilitate vaccine development. There is a growing interest in the field of vaccinology centered on the new omic science named ‘vaccinomics’. However, this approach has not succeeded to provide a solution against major infections affecting both animals and humans, since tick vaccines are still being developed based on conventional biochemical or immunological methods to dissect the molecular structure of the pathogen, looking for a candidate antigen. The availability of complete genomes and the novel advanced technologies, such as data mining, bioinformatics, microarrays, and proteomics, have revolutionized the approach to vaccine development and provided a new impulse to tick research. The aim of this review is to explore how modern vaccinology will contribute to the discovery of new candidate antigens and to understand the research process to improve existing vaccines. Under this concept, the omic age of ticks will make it possible to design vaccines starting from a prediction based on the in silico analysis of gene sequences obtained by data mining using computer algorithms, without the need to keep the pathogen growing in vitro. This new genome-based approach has been named “reverse vaccinology 3.0” or “vaccinomics 1.0” and can be applied to ticks.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in the human host can lead to various clinical manifestations, from symptomless carriers to mild to moderate to severe/critical illness. Therefore, the clinical classification of SARS-CoV-2 disease, based on severity, is a reliable way to predict disease states in SARS-CoV-2 infection. Recent studies on genomics, transcriptomics, epigenomics, and immunogenomics, along with spatial analysis of immune cells have delineated and defined the categorization of these disease groups using these high throughout technologies. These technologies hold the promise of providing not only a detailed but a holistic view of SARS-CoV-2-led pathogenesis. The main genomic, cellular, and immunologic features of each disease category, and what separates them spatially and molecularly are discussed in this brief review to provide a foundational spatial understanding of SARS-CoV-2 immunopathogenesis.

Immune responses are orchestrated by controlling the initiation, magnitude, and duration of various signaling pathways. Adaptor proteins act as positive or negative regulators by targeting critical molecules of signaling cascades. Signal-transducing adaptor protein-2 (STAP-2) contains typical features of adaptor proteins, like a pleckstrin homology (PH) domain in the N-terminal region and a Src homology 2 (SH2) domain in the central region. STAP-2 binds to a variety of signaling or transcriptional molecules to control multiple steps of inflammatory/immune responses. STAP-2 enhances T-cell receptor (TCR)-mediated signaling via the association with TCR-proximal CD3ζ immunoreceptor tyrosine-based activation motifs (ITAMs) and lymphocyte-specific protein tyrosine kinase (Lck). STAP-2 decreases adherence of T-cells to fibronectin (FN) through an association with focal adhesion kinase (Fak) and Casitas B-lineage Lymphoma (c-Cbl), and increases chemotaxis of T-cells toward stromal cell-derived factor-1α (SDF-1α) through interactions with Vav1 and Ras-related C3 botulinum toxin substrate 1 (Rac1). STAP-2 positively regulates activation-induced cell deathrough the association with Fas and caspase-8. This review describes the current knowledge of the roles of STAP-2 in T-cell-dependent immune responses and the possible clinical utility of STAP-2-targeting therapies.

Psoriasis is a skin disease characterized by scaly erythema, parakeratosis, and epidermal hyperplasia. Application of imiquimod (IMQ), a ligand for Toll-like receptor 7, produces a mouse model for psoriasis. IMQ application induces scaling, erythema, and thickness in skin lesions, and the symptoms are milder in interleukin-23 p19 (Il23p19)-deficient and Il17a-deficient mice than in wild-type mice; this suggests that the interleukin-23 (IL-23)/T helper 17 (Th17) axis and Th17 cell-secreting cytokines play essential roles in the IMQ-induced psoriasis model. It is notable that a genome-wide association study identified the human tyrosine kinase 2 (TYK2) gene within the psoriasis susceptibility locus. After IMQ application, mice lacking Tyk2, a mouse homologue of the human TYK2 gene, exhibited significantly lower symptom scores of psoriasis and diminished inflammatory cell infiltration in the skin lesions. Tyk2-deficient mice also failed to increase CD4⁺IL-17⁺ or CD4⁺ interferon-γ⁺ (IFN-γ⁺) T cells in the draining lymph nodes or to produce Th17 cell-related cytokines after IMQ application. Furthermore, Tyk2 deficiency led to diminished skin inflammation induced by IL-23 and IL-22 injections. These results indicate that Tyk2-mediated signals in mice contribute to multiple steps of immune and inflammatory responses during the development of psoriasis; therefore, TYK2 targeting may be a promising strategy to treat patients with psoriasis. Recent clinical trials have shown that TYK2 inhibitors have a high overall response rate with good tolerability in the management of psoriasis. This review describes the fundamental mechanisms of Tyk2 inhibition in immune/inflammatory diseases.

The absence of advancement in finding efficient vaccines for several human viruses, such as hepatitis C virus (HCV), human immunodeficiency virus type 1 (HIV-1), and herpes simplex viruses (HSVs) despite 30, 40, and even 60 years of research, respectively, is unnerving. Among objective reasons for such failure are the highly glycosylated nature of proteins used as primary vaccine targets against these viruses and the presence of neotopes and cryptotopes, as well as high mutation rates of the RNA viruses HCV and HIV-1 and the capability to establish latency by HSVs. However, the lack of success in utilization of the structure-based reverse vaccinology for these viruses is likely to be related to the presence of highly flexible and intrinsically disordered regions in human antibodies (Abs) and the major immunogens of HIV-1, HCV, and HSVs, their surface glycoproteins. This clearly calls for moving from the rational structure-based vaccinology to the unstructural vaccinology based on the utilization of tools designed for the analysis of disordered and flexible proteins, while looking at intrinsically disordered viral antigens and their interactions with intrinsically disordered/flexible Abs.

Microbiome research has enormous potential in cancer research and the use of formalin-fixed paraffin-embedded (FFPE) tissues could offer many advantages. The tumor microenvironment represents a suitable niche for specific microbes and evidence proves the presence of an endogenous tumor microbiota, here referred to as oncobiota. Awareness of the oncobiota role in tumorigenesis could have a large influence on cancer care, in terms of diagnosis, prevention, and treatment. Moreover, understanding the microbial-related tumor microenvironment, and its influence on tumor immune response and cancer cells will help define important pathogenetic mechanisms in cancer starting or progression. Routine collection of histopathological FFPE samples provides a large availability of specimens essential for affordable and impactful retrospective analyses and for getting robust statistical results. The FFPE tissues are common in the analysis of tumor biopsies including the tumor microbiota characterization which has an important role in the modulation of our immune system and consequently of tumor cells. However, the microbiota analysis starting from FFPE tissues presents methodological pitfalls and limits that may negatively affect the oncobiota research. After examining the methodological and analytical difficulties of this approach, this work seeks to offer workable solutions to promote that research area.

Natural killer (NK) cells have a dual role in human reproduction for maternal-fetal tolerance and protection from infection. During the ovarian cycle and pregnancy, peripheral NK (pNK) and uterine NK (uNK) cells dynamically change their proportions and cytotoxicities to prepare and accommodate invading trophoblast and maintain pregnancy. However, dysregulated pNK and uNK cell proportions and cytotoxic activities have been associated with aberrant spiral artery remodeling and trophoblast invasion, leading to implantation failures and recurrent pregnancy losses (RPLs). This review will focus on the role of NK cells in RPLs reviewing the ontogeny of NK cells, changes in pNK and uNK cell levels, and activities during the ovarian cycle, normal pregnancy, and RPL. In addition, the immunopathological role of NK cells in endometrial/decidual vascular development and killer immunoglobin-like receptor (KIR) and human leukocyte antigen (HLA)-C interactions are discussed.

Menopause signals the end of the reproductive period in women. However, fertility and fecundity decrease with increasing age prior to menopause demonstrating that changes in the premenopausal female reproductive tract (FRT) are already occurring that negatively impact reproductive success. The effects of age on the endometrium are poorly understood, in contrast to the ovary where changes occur with increasing age that negatively affect successful reproduction. The endometrial immune system is essential for generating a receptive endometrium, but the link between the immune and reproductive systems in the endometrium in the years prior to menopause has not been well-defined. Since the endometrial immune system is tightly regulated to maximize reproductive success and pathogen protection, changes in immune function with increasing premenopausal age have the potential to impact reproduction.

Sepsis was defined in 1991 by the systemic inflammatory response syndrome (SIRS) criteria which consisted mostly of physiologic responses to infection or inflammation (fever, tachycardia, tachypnea, and leukocytosis). These criteria were initially proposed to identify patients with gram-negative bloodstream infection (BSI). However, most patients with BSI are not critically ill at initial presentation using objective clinical scores for acute severity of illness, such as the Pitt bacteremia score (PBS). Lack of specificity and low positive predictive value (PPV) are other pitfalls of the SIRS criteria. Moreover, the implementation of sepsis interventions based on this outdated definition failed to improve patients’ outcomes and in some settings was associated with increased use of broad-spectrum antibiotics and Clostridioides difficile (C. difficile) infection. In 2016, sepsis was redefined as a dysregulatory host response to life-threatening infections using quick sequential organ failure assessment (qSOFA) score. The presence of two of three bedside clinical variables (hypotension, respiratory distress, and altered mental status) that have consistently predicted mortality in patients with infections now constitutes sepsis. The scientific debate continues in the medical literature regarding the performance of the new criteria. Some medical professionals and quality organizations consider these changes to the sepsis definition too revolutionary and are resistant to altering existing medical practice. This narrative review presents infection as a continuum from localized to systemic infection (pre-sepsis) with the potential progression into sepsis and septic shock if appropriate antibiotic therapy and source control are delayed. The review assesses host and microbial factors that may influence the rate of progression through the sepsis cascade and proposes diagnostic considerations and management decisions at each step of the way. It emphasizes the need to utilize precision medicine concepts in selecting empirical antibiotic therapy based on patient-specific risk factors for infections due to resistant bacteria and potential benefits from appropriate therapy across the sepsis spectrum.

Coronavirus disease 2019 (COVID-19) is currently a major public health concern causing devastating sociological, economic, and psychological damage to livelihood all over the world. The most intense severity of COVID-19 is not only acute respiratory distress syndrome (ARDS), it also causes multi-organ failure, the post-infection secondary effect as well as death. The fast-mutating ability and high transmissibility rate of the virus cause emergence of the new variants and also the occurrence of breakthrough infections. Evidence suggests that vaccination against COVID-19 has been effective at preventing the severity of illness, hospitalization, and death. The efficacy of vaccines depends on multiple factors including the host’s ability to mount a robust and sustainable immune response, the virus’s ability to mutate its genome, and programmatic factors such as vaccine dose, storage, dosing schedules, etc. In this article, an overview of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, its pathogenesis, host immune responses to infection, and different type of COVID-19 vaccines, including vaccine efficacy and adverse effects are described.

Chemokines are homeostatic or inflammatory small proteins regulating immune cell migration and are structurally characterized by cysteine disulfide bridges. Around 50 human chemokines binding almost 20 seven-transmembrane G-protein coupled receptors have been discovered. The finding that two of them were the main human immunodeficiency virus (HIV) co-receptors intensified the research on the binding mechanism to block the viral entrance. Blockade of chemokine/chemokine receptor signaling ultimately modulates cell migration, then immune responses. Particular nanotechnologies can be designed to interfere with chemokine signaling or to exploit the ligand-receptor interaction. Surface chemical modification of nanomaterials with chemokines or specific peptides can find several applications in bio-medicine, from tissue-specific drug delivery to reduced cell migration in pathological conditions. Recent highlights on peculiar chemokine-nanoparticle design and their potential to modulate immune responses will be discussed.

Complement component 1q (C1q) is the recognition molecule of the classical pathway of the complement system that can bind to an array of closely spaced antigen-bound immunoglobulin G (IgG) and IgM antibodies. In addition to its involvement in defence against a range of pathogens and clearance of apoptotic and necrotic cells, C1q has also been implicated in immune and non-immune homeostasis. C1q is locally produced by immune cells such as monocytes, macrophages, and dendritic cells. C1q is also synthesized by decidual endothelial cells, thus acting as a link between decidual cells and trophoblasts, as well as contributing to the remodelling of spiral arteries. Furthermore, C1q is produced by the extravillous trophoblasts (EVTs) invading the decidua. As a pro-angiogenic molecule, C1q is also important for normal placentation processes as it favors the active angiogenesis in the developing decidua. These observations have been validated by C1q gene knock-out mice which showed pre-eclampsia (PE)-like symptoms, characterized by hypertension, proteinuria, glomerular endotheliosis, and increased soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) ratio, and increased oxidative stress. The role of C1q in normal and adverse human pregnancy is being studied extensively due to its absence or low level as a likely precipitating factor for the development of PE.

In ultrarare cases, patients vaccinated with DNA adenovirus vector vaccine against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), develop a vaccine-induced immune thrombotic thrombocytopenia (VITT), with a high incidence of fatal cases. The causative agent is the development of platelet factor 4 (PF4)-dependent antibodies that resemble heparin-induced thrombocytopenia (HIT) complication, although many differences can be noticed in clinical presentation, antibody reactivity, involved epitopes on the PF4 protein, and pathological mechanisms. From the literature review, and the experience of HIT and testing a few plasmas from patients with VITT, this review analyzes the possible mechanisms, which show the strong immunoglobulin G (IgG) antibody reactivity to PF4 alone, in the absence of heparin, and to a lesser extend to stoichiometric complexes of PF4 and heparin (H-PF4). In addition, much lower heparin concentrations are required for inhibiting antibody binding to PF4. These concentrations are much lower than those required for disrupting the stoichiometric H-PF4 complexes. This confirms that IgG antibodies responsible for HIT bind preferentially to PF4, to epitopes that are readily masked by low concentrations of heparin. These antibodies are at a much higher concentration than the current ones observed for HIT, keeping a strong reactivity even for plasma dilutions as high as 1/500 to 1/5,000, whilst the current dilution for testing heparin-dependent antibodies in HIT is 1/100. Although VITT anti-PF4 antibodies can be detected with the current anti-H-PF4 enzyme-linked immunosorbent assays (ELISAs) designed for HIT, some assays have low sensitivity or are unreactive, like lateral immunofiltration methods or chemiluminescent automated assays. The preferred method should concern the use of capture assays using PF4 coated solid surfaces. This report proposes that the immune response is only targeted to the binding domain of PF4 with the hexons present on the adenovirus vector, through an epitope spreading mechanism, without any exposure of neo-epitopes on PF4 protein.

Sepsis is a life-threatening condition caused by dysregulated host immune response to infection, leading to persistent inflammation followed by immunosuppression. Sepsis represents a substantial global health problem owing to protracted inflammation, immune suppression, and susceptibility to nosocomial infections. Despite continuing progress in the development of antibiotics, fluid resuscitation, and other supportive care therapies, no specific immunomodulatory drugs or immunotherapeutic adjuncts for the treatment of sepsis are available to date. The advances in tertiary care facilities and patient care have improved the survival of sepsis patients in the initial hyper-inflammatory phase of sepsis. However, the majority of sepsis patients succumb later due to prolong immunosuppression. The sepsis-induced immune dysregulation and its long-term effects on mortality are under meticulous investigations that are still poorly defined. Sepsis leads to the impaired functions of the innate and adaptive immune systems. The exhaustion of T cells, reduced expression of human leukocytes antigen (HLA)-DR on monocytes, and induced uncontrolled apoptosis of immune cells have been reported as hallmark features of sepsis. Sepsis-induced immune cell apoptosis of immune cells is a primary contributing factor to the immunosuppression in sepsis. Preclinical studies have identified several new therapeutic targets for therapy in sepsis, including monoclonal antibodies (Abs) and anti-apoptotic agents to reduce T cells exhaustion, immune cells apoptosis, and restoring immune cells functions. Recent studies have centered on immune-modulatory therapy. The review article will focus solely on sepsis’ effects on innate and adaptive cells functions that contribute to immunosuppression. Finally, it is discussed how immune cells responsible for immunosuppression might be directly targeted to provide potential therapeutic benefits in treating sepsis and improving long-term survival.

The human microbiome has emerged as an intriguing field of scientific research. Its role in human physiology impacts both health and disease, contributing to the enhancement or impairment of metabolic and immune functions. Sometimes referred to as our body’s “second genome”, the alteration of the microbiome’s bacterial ecology (dysbiosis), is linked to increasing numbers of illnesses, including cancer. The tumor microenvironment (TME) is the environment in which tumors grow and modulate the tumorigenic process depending on a myriad of distinct factors, including cell types, vascular system, and cytokines. Given the emerging relationship between the microbiome and the TME, this perspective aims to distill some of the key factors regulating the crosstalk between the microbiome and the TME. It also outlines why manipulating the microbiome may be a feasible strategy for anti-cancer therapy.

The immune system, whose nature lies in being a complex network of interactions, lends itself well to being represented and studied using graph theory. However, it should be noted that although the formalization of models of the immune system is relatively recent, the medical use of its signaling network structure has been carried out empirically for centuries in vaccinology, immunopathology, and clinical immunology, as evidenced by the development of effective vaccines, the management of transplant rejection, the management of allergies, and the treatment of certain types of cancer and autoimmune diseases. A network optimization analogy is proposed through the employment of the system dynamic formalism of causal loop diagrams (CLDs), where current network operations (also known as NetOps) in information technology (IT), are interpreted as immune NetOps in coronavirus disease 2019 (COVID-19) treatment. Traffic shaping corresponds to signaling pathway modulation by immunosuppressors. Data caching corresponds to the activation of innate immunity by application of Bacillus Calmette-Guerin (BCG) and other vaccines. Data compression corresponds with the activation of adaptative immune response by vaccination with the actual approved COVID-19 vaccines. Buffer tuning corresponds with concurrent activation of innate and adaptative or specialized immune cells and antibodies that attack and destroy foreign invaders by trained immunity-based vaccines to develop. The present study delineates some experimental extensions and future developments. Given the complex communication architecture of signal transduction in the immune system, it is apparent that multiple parallel pathways influencing and regulating each other are not the exception but the norm. Thus, the transition from empirical immune NetOps to analytical immune NetOps is a goal for the near future in biomedicine.

Infertility affects millions of people of reproductive age. The failure of a blastocyst to implant is a leading cause of psychological distress. It became increasingly evident that an effective immune dialogue occurs at each step in the fluids surrounding the oocyte, the spermatozoa, the embryo, or the endometrium. Exploring and deciphering this dialogue could potentially help understand why 50% of healthy euploid blastocysts fail to implant. Introducing immunology into reproductive medicine requires a change of mindset to bring immune hypothesis to clinical applications. Implantation of an embryo requires a prepared uterus in order to dialogue with the embryo, which is able to express and repair itself. Exploring the uterine immune profile of patients with previous implantation failures (IF) or recurrent miscarriages (RM) has already been developed and is under evaluation as a precision tool to equilibrate the uterine environment before implantation to increase the subsequent live birth rate after the embryo transfer. Immunology may also be fundamental in the future to identify through non-invasive procedure the competence of oocytes or embryos through reliable immune biomarkers quantified in follicular fluids or embryo supernatants during the in vitro fertilization (IVF) process. Non-invasive biomarkers would allow physicians to identify competent oocytes or embryos based on their ability to communicate with the mother and their energetic potential for all the self-repair processes that should occur during the preimplantation and the implantation period. This area of research is only beginning.

Human γδ T cells are unconventional lymphocytes that function in innate and adaptive immune responses and immunosurveillance. These cells show potent cytotoxicity against tumor cells in a major histocompatibility complex unrestricted manner and have recently gained considerable attention as a sparkling star for clinical immunotherapy. Clinical immunotherapy trials with activated γδ T cells are tolerated well. However, clinical benefits are still unsatisfactory. Therefore, anti-tumor effects need to further increase the cytotoxicity of γδ T cells via several mechanisms, including the novel nitrogen-containing bisphosphonate products, adjuvant use with a bispecific antibody and chimeric antigen receptor, co-immunotherapy with γδ T cells plus immune checkpoint inhibitors, and adoptive immunotherapy with Vδ1 T cells and T cells engineered to express a defined γδ T cell receptor. Here, this article describes the crucial role of γδ T cells in anti-tumor immunity, concludes transduction strategies and summarizes the different development of novel approaches for clinical applications and cancer immunotherapy, which may be effective in overcoming current therapeutic limitations.

Uterine natural killer (uNK) cells, a specific type of natural killer (NK) cells, are important cells at the foeto-maternal interface in humans as well as in mice. uNK cells are part of the innate lymphoid cells group 1. Especially in the mouse, but also in the rat, many in vivo studies have been performed to evaluate the role of uNK cells in placental development. These studies have shown that uNK cells are not indispensable to pregnancy, but that they play an important role in optimal decidual angiogenesis in early pregnancy, trophoblast invasion and spiral artery remodelling in the mouse placenta. Based on the mouse studies, various in vitro studies, as well as immunohistological studies of the human placenta from elective abortions, have shown that uNK cells have similar functions in the human placenta. In the present narrative review, the role of the uNK cells in the development of the mouse and rat placenta will be discussed first. Thereafter, studies on the role of human uNK cells in the human placenta will be reviewed and these studies will be discussed in the light of the knowledge on mouse uNK cells.

Antiphospholipid syndrome (APS) is defined by recurrent pregnancy morbidity and/or vascular thrombosis associated with the persistent presence of antibodies against anionic phospholipid-binding proteins. Beta 2 glycoprotein I (β2GPI) and prothrombin (PT) are the major antigens for antiphospholipid antibodies (aPL) detectable by functional coagulation [lupus anticoagulant (LA)] or solid-phase assays [anti-β2GPI-dependent cardiolipin (aCL) and anti-β2GPI]. β2GPI-dependent aPL are responsible for the positivity of the three classification laboratory criteria. While medium/high titers of antibodies against β2GPI are risk factors for both the vascular and the obstetric manifestations of APS, persistent low titers are also associated with pregnancy complications. There is evidence from animal models of aPL-dependent fetal loss and from in vitro systems that β2GPI-dependent aPL can be pathogenic. β2GPI is physiologically found in large quantities at the placental level being available for the specific antibodies circulating in the maternal blood. Once bound to the protein, the antibodies trigger a local inflammation via the activation of the complement cascade and affect trophoblast and decidual function. The final result is represented by defective placentation, while thrombotic events are apparently less important. β2GPI is a pleiotropic molecule with scavenging properties towards several molecules including apoptotic material and displays anti-oxidant activity. These functions may explain the β2GPI placental localization in an area of intensive tissue remodeling and low oxygen tension. Since β2GPI interacts also with the complement and the coagulation cascade, its binding with specific antibodies may affect the physiology of placentation in several ways.

Sepsis and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and its severe form coronavirus disease 2019 (COVID-19), represent the major medical challenges of the modern era. Therapeutic options are limited, mostly symptomatic, partially relying on antibodies and corticosteroids and, in the case of SARS-CoV-2 infection, supplemented by the antiviral drug remdesivir, and more recently by molnupiravir, nirmatrelvir/ritonavir, and the Janus kinase (JAK) inhibitors tofacitinib and baricitinib. Sepsis and severe SARS-CoV-2 infection/COVID-19 share many features at the level of pathophysiology and pro-inflammatory mediators, thus enabling a common disease management strategy. New ideas in successfully targeting the prognostic severity and mortality marker pentraxin 3 (PTX3) in sepsis and severe SARS-CoV-2 infection/COVID-19; the complement (C3/C3a/C3aR and C5/C5a/C5aR axis); tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 expression; IL-6-triggered expression of C5aR receptor in vascular endothelial cells; and release of anti-inflammatory IL-10 are still missing. Small molecules with lysosomotropic characteristics such as the approved drugs amitriptyline, desloratadine, fluvoxamine, azelastine, and ambroxol have demonstrated their clinical benefits in rodent models of sepsis or clinical trials in COVID-19; however, their exact mode of action remains to be fully elucidated. Addressing disease-relevant targets such as viral infection of host cells, shedding of toll-like receptors (TLRs), expression of pro-inflammatory mediators such as TNF-α, IL-1β, IL-6, PTX3, and the complement receptor C5aR, highlight the advantages of this multi-target approach in comparison to current standards. Rational drug repurposing of approved drugs or screening for active compounds with virtually exclusively lysosomotropic pharmacologic effects is a major opportunity to improve prophylaxis and treatment of sepsis and/or SARS-CoV-2 infection, and its severe form COVID-19.

Endometriosis (EMS) is an inflammatory, gynaecologic disease characterized by the growth of endometrial tissues outside the uterus. With no satisfactory therapies or non-invasive diagnostics available, a shift in perspectives on EMS pathophysiology is overdue. The implication of immune dysregulation in EMS pathogenesis and disease progression has been an evolving area of research, with numerous immune and inflammatory pathways identified. Traditional theories regarding the establishment of endometriotic lesions have lacked mechanistic explanations for their proliferation and survival until recent research unearthed the involvement of mesenchymal stem cell (MSC) and myeloid-derived suppressor cells (MDSCs) in a complex network of immune-endocrine signaling. The unique immunology of EMS is likely owing to estrogen dominance, as endocrine imbalance reliably cultivates immune dysregulation. Many of the phenomena observed in EMS parallel immune biology seen in various cancers, including accelerated somatic mutations in endometrial epithelial cells. Here, the high mutational load leads to EMS neoantigen development which potentially contributes to the lesion immune microenvironment. As well, EMS manifests comorbidity with several chronic inflammatory diseases that share common dysregulation of the interleukin-23 (IL-23)/IL-17 pathway (as seen in inflammatory bowel disease, psoriasis, and rheumatoid arthritis). EMS is especially relevant to the study of chronic pelvic pain (CPP) as 60% of EMS patients experience this symptom and chronic inflammation is believed to be central to the process of pain sensitization. Since the onset of the disease usually occurs in adolescence, and diagnosis only occurs years later once moderate to severe symptoms have developed, it is vital to innovate non-invasive diagnostic tools for earlier detection. Several potential biomarkers are being studied, including some cytokines, gene signatures, and extracellular vesicle (EV) signatures. By incorporating the immune perspectives of EMS into our research, approaches to diagnosis, and treatment solutions, the field has more promising avenues to clearly define EMS and offer patients relief.

This review pretends to shed light on the immune processes occurring in the coronavirus disease 2019 (COVID-19) from a perspective based on the antigens size, lower or larger than 70 kDa. This cutoff size point explains the host type of immune response against the antigenic proteins of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which may lead to the development of the memory B cells or, conversely, the immune suppression, apoptosis, viral escape, and sepsis. Here, based on previous experimental work and the review of related literature, the following is proposed: antigens < 70 kDa can access the germinal center through the follicular conduits, where the activated B cells can present the processed antigen to specific naive CD4⁺ T cells that, in interaction with the major histocompatibility complex class II (MHC-II), trigger the immune response T helper type 2 (Th2). Conversely, antigens > 70 kDa cannot circulate through the narrow follicular conduits network and might be captured within the subcapsular sinus by the macrophages and dendritic follicular cells. Then, these cognate antigens are presented, via complement receptors, to the B cells that acquire and present them through the MHC-II to the specific naive CD4⁺ T cells, triggering the immune response Th1. The sustained infected cells lysis can overfeed high levels of unassembled viral proteins < 70 kDa, which can lead to a strong and persistent B cell receptor (BCR) activation, enhancing the Th2 immune response, releasing interleukin-10 (IL-10) and transforming growth factor-beta (TGF-β) that may lead to the immune paralysis, apoptosis, sepsis, and death. Finally, it is suggested that the polymerization of the viral antigens < 70 kDa into an antigenic polymer > 70 kDa could shift the immune response type from Th2 to Th1, developing the memory B cells and immunoglobulin G2 (IgG2) production, and avoiding the sepsis.

Immunity is usually classified into two categories: innate immunity and adaptive immunity, distinguished by the process and characteristics of the immunological impact. It was widely assumed that only adaptive immunity possessed memory features; however, current research has revealed that innate immunity, like adaptive immunity, possesses memory properties as well. “Trained immunity”, also known as “innate immune memory”, is a phenomenon that occurs when the immune system’s innate cells are stimulated and then undergo epigenetic reprogramming and metabolic alterations. When it comes to innate immunity, macrophages are essential since they have immunological memory capabilities and play a significant role in the body’s immunity. The concept of innate immune memory expands the definition of immunological memory and offers a broader view of immune response research. This article reviews the properties, mechanism, and significance of macrophage innate immune memory in disease.

“There is many a slip twist the cup and the lip” is a proverb that dates back to the 3rd century. This proverb comes to mind while writing a review on pregnancy loss; so many complications can occur between fertilization and development of the embryo through the long period of gestation until successful delivery of the baby. These include failure of implantation of the embryo, spontaneous miscarriage in the first trimester, pre-eclampsia in the second trimester, premature rupture of fetal membranes, pre-term labour, and pre-term delivery. The maternal immune system which does a phenomenal job of protecting the host from a daunting variety of infections, sometimes also mounts adverse reactions that complicate pregnancy and endanger the fetus. Maternal immune reactions that can adversely affect pregnancy have been shown to be mediated by lymphocytes, macrophages and natural killer cells, and by cytokines secreted by these cellular effectors. This review summarizes the deleterious effects of cytokines leading to recurrent spontaneous miscarriage, pre-eclampsia and pre-term delivery, which are the major complications of pregnancy. It then goes on to discuss the potential use of progesterone and dydrogesterone, an orally-administered progestogen, as immunomodulatory molecules that can be considered for the prevention and/or treatment of these complications.

Polycystic ovary syndrome (PCOS) is one of the most frequently observed endocrinopathies among women of reproductive age that redound to subfertility. The specific etiology of this heterogenic syndrome remains ambiguous. Metabolic complications, hormonal imbalance, deregulation in the immune system and their interrelationship make PCOS more complex. Hyperandrogenism and chronic low-grade inflammation modulate each other and enhance the self-perpetuation of PCOS. Even though there are many literature studies on PCOS and immune deregulation, this review focuses on the endocrine-immune nexus and how the altered endocrine system is embroiled in the immunopathology of PCOS.

Conventional immunohistochemistry methods though once fundamental for the individual staining of cell markers, have now been superseded by multispectral immunohistochemistry (mIHC). mIHC enables simultaneous detection of multiple cell markers in situ using single formalin-fixed paraffin-embedded (FFPE) tissue sections. In addition to conserving patient tissue specimens, the ability to visualise more than one marker on individual cells allows for further refining of cell phenotypes, and provides insight into cell-to-cell interactions and spatial arrangements across single tissue sections. Here, a comprehensive protocol is described for the in situ interrogation of γδ T cells and phosphoantigen-presenting butyrophilin (BTN) molecules (BTN2A1 and BTN3A1) in human FFPE tissue using Opal™ tyramide signal amplification (TSA)-based mIHC. It is demonstrated that an effectively optimised Opal™-TSA 7-marker [CD3, Pan-γδ T cell receptor (TCR), granzyme B, BTN2A1, BTN3A1, tumour marker, 4’,6-diamidino-2-phenylindole (DAPI)] mIHC panel can be used to define the presence, localisation, and activation status of γδ T cells and the BTN2A1 and BTN3A1 ligands.

Among decidual immune cells, regulatory T cells (Tregs) have been unanimously recognized as central contributors to tolerance and maintenance of healthy pregnancy. Numerical and functional downregulation of Tregs or disturbed interaction of Tregs with trophoblasts and other immune cells have been linked to early pregnancy loss such as idiopathic infertility and miscarriage and later-onset adverse pregnancy outcomes including preeclampsia. This review focuses on the mechanisms for regulating the generation, expansion, and function of Tregs, the roles of Tregs in maintaining maternal immune tolerance through crosstalk with trophoblasts and other decidual regulatory immune cells, and how Tregs may play foes to pregnancy and contribute to the programming of pregnancy-related complications. Therapeutic options for implantation failure and adverse pregnancy outcomes are now part of the emerging significance of Tregs in pregnancy tolerance and maintenance.

Humans are afflicted by a wide spectrum of autoimmune disorders, ranging from those affecting just one or a few organs to those associated with more systemic effects. In most instances, the etiology of such disorders remains unknown; a consequence of this lack of knowledge is a lack of specific treatment options. Systemic lupus erythematosus (SLE) is the prototypic systemic autoimmune disorder; pathology is believed to be antibody-mediated, and multiple organs are targeted. Periods of disease “flares” are often followed by long periods of remission. The fact that SLE is more commonly observed in females, and also that it more particularly manifests in females in the reproductive age group, has quite naturally drawn attention to the potential roles that hormones play in disease onset and progression. This review attempts to shed light on the influences that key hormones might have on disease indicators and pathology. Databases (Google Scholar, PubMed) were searched for the following keywords (sometimes in certain combinations), in conjunction with the term “lupus” or “SLE”: autoantibodies, recurrent abortion, polycystic ovarian syndrome (PCOS), preeclampsia, pre-term delivery, estrogens, progesterone, androgens, prolactin, leptin, human chorionic gonadotropin (hCG). Cited publications included both research articles and reviews.

Cancer immunotherapy, especially T-cell driven targeting, has significantly evolved and improved over the past decade, paving the way to treat previously refractory cancers. Hematologic malignancies, given their direct tumor accessibility and less immunosuppressive microenvironment compared to solid tumors, are better suited to be targeted by cellular immunotherapies. Gamma delta (γδ) T cells, with their unique attributes spanning the entirety of the immune system, make a tantalizing therapeutic platform for cancer immunotherapy. Their inherent anti-tumor properties, ability to act like antigen-presenting cells, and the advantage of having no major histocompatibility complex (MHC) restrictions, allow for greater flexibility in their utility to target tumors, compared to their αβ T cell counterpart. Their MHC-independent anti-tumor activity, coupled with their ability to be easily expanded from peripheral blood, enhance their potential to be used as an allogeneic product. In this review, the potential of utilizing γδ T cells to target hematologic malignancies is described, with a specific focus on their applicability as an allogeneic adoptive cellular therapy product.

Obesity has become a worldwide scourge, affecting more than 10% of adults worldwide. While widely recognized to be associated with increased incidence of medical conditions such as diabetes mellitus and atherosclerosis, obesity also accounts for 9% of the cancer burden in some populations. This is due in part to perturbation of protective immune mechanisms involving natural killer cells, macrophages, and neutrophils. Recent studies indicate that γδ T cells play a prominent protective role against cancer, but in some circumstances are detrimental and pro tumorogenic. In this review, the current scientific literature was explored to determine whether and how obesity affects the anti- and pro-tumoral functions of γδ T cells. Considerable perturbations of γδ T cells by obesity were revealed, suggesting that the “obesity-γδ T cell axis” may profoundly impact the increased incidence of cancer in obese individuals and is worthy of further study.

Lower respiratory tract infections caused over 4 million deaths per year worldwide, especially in low-income countries. Viral respiratory infections often occur as rapidly spreading seasonal endemic or epidemic, and sometimes due to new respiratory viruses including corona viruses. The first level of host defense against viral infection is based on the innate immune system and intracellular killing mechanisms. The latter is activated by the release of viral DNA or RNA into the cytosol of the infected cells during the initial phase of virus replication. Viral DNA and RNA are recognized by the cyclic guanosine monophosphate (cGMP)-adenosine monophosphate (AMP) synthase (cGAS)–stimulator of interferon (IFN) genes (STING) sensing pathway, leading to the activation of type-I and -III IFN synthesis, with the aim to limit viral replication. However, the efficacy of the cGAS-STING sensing mechanism seems to vary with different viruses, and therefore, so is the efficacy of the host defense mechanism. Viral DNA can be sensed by different proteins including DNA-dependent activator of IFN regulating factor (DAI), cGAS, and toll-like receptor-9 (TLR-9). Viral RNA is recognized by retinoid acid-inducible gene 1 (RIG-1), TLR-7 and TLR-8. The question if cGAS also recognizes viral RNA remains unclear. The activation of IFN synthesis by cGAS is initiated by the recognition of purines and pyrimidines and their enzymatic conversion into cGMP and cyclic AMP (cAMP), followed by the activation of STING. In addition, it is indicated that several viruses can evade the cGAS-STING signaling and escape the host defense. This review aims to summarize the role of cGAS-STING as a host defense mechanism against viral respiratory tract infections.

Treatment of sepsis currently relies on eliminating the causal pathogen and supportive care, whereas almost no approaches to interfere with the defining event of a “dysregulated host response” are available. This review points to the striking correlation of two phenotypes of sepsis etiopathology with the concept of bipartite response patterns of higher organisms to microbial attacks. According to this concept, the phenotypes of sepsis can be interpreted as either resistance or tolerance responses to infection that got out of hand. This concept might allow focusing sepsis research and related patient studies on key conundrums of current sepsis research: how do resistance responses result in immunopathology and how can tolerance lead to systemic immunosuppression or even immunoparalysis? The heuristic vigor of these questions might inspire experimental efforts and clinical studies and ultimately advance the therapeutic armamentarium for sepsis care.

Self-replicating RNA viruses have been commonly used for preventive and therapeutic interventions in the fields of infectious diseases and cancers. Both RNA viruses with single-stranded RNA genomes of positive and negative polarity have been utilized. Expression of viral surface proteins from self-replicating RNA virus vectors has elicited strong immune responses and provided protection against challenges with lethal doses of pathogens in various animal models using recombinant viral particles, RNA replicons, or plasmid-based replicon vectors. Similarly, immunization with self-replicating RNA virus vectors expressing tumor antigens has induced tumor-specific antibody (Ab) responses, inhibited tumor growth, eradicated tumors, and protected immunized animals against tumor challenges. Clinical trials have demonstrated good safety and tolerance of self-replicating RNA viruses. Although the number of clinical trials is low, robust immune responses and protection against challenges with pathogens and tumor cells have been achieved. The Ervebo vaccine against Ebola virus disease has been approved by both the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA).

The crown-like shaped viruses known as coronaviruses which were first reported in the 1960’s have caused three epidemics in the past two decades namely, coronavirus disease-19 (COVID-19), severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS). SARS coronavirus 2 (SARS-CoV-2) was first reported in the latter half of December in Wuhan, a city of China, with people affected by deadly pneumonia with unknown etiology. Since then, the world has experienced two phases of virus spread with different symptoms and disease severity. This review embarks on the journey to investigate candidate molecules of this virus which can and are being investigated for various vaccine formulations and to discuss immunity developed against this virus.

Alzheimer’s disease (AD) is a common neurological disease in the elderly, and the major manifestations are cognitive dysfunction, neuronal loss, and neuropathic lesions in the brain. In the process of AD pathogenesis, the inflammatory response plays an indispensable role. The nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) inflammasome containing NOD, leucine-rich repeat (LRR), and pyran domains is a multi-molecular complex that can detect dangerous signals related to neurological diseases. The assembly of NLRP3 inflammasome promotes the maturation of interleukin-1beta (IL-1β) and IL-18 mediated by caspase-1 in microglia, which leads to neuroinflammation and finally contributes to the occurrence and development of AD. This review aimed to clarify the structure and activating mechanism of NLRP3 inflammasome and its key role in the pathogenesis of AD, summarize the latest findings on the suppression of NLRP3 inflammasome activation for the treatment of AD, as well as indicate that targeting regulation of NLRP3 inflammasome assembly may be a potential strategy for the treatment of AD, providing a theoretical basis for the research of AD.

Recent anti-cancer strategies are based on the stimulation of anti-tumor immune reaction, exploiting distinct lymphocyte subsets. Among them, γδ T cells represent optimal anti-cancer candidates, especially in those tissues where they are highly localized, such as the respiratory or gastrointestinal tract. One important challenge has been the identification of stimulating drugs able to induce and maintain γδ T cell-mediated anti-cancer immune response. Amino-bisphosphonates (N-BPs) have been largely employed in anti-cancer clinical trials due to their ability to upregulate the accumulation of pyrophosphates that promote the activation of Vγ9Vδ2 T cells. This activation depends on the butyrophilin A family, which is crucial in contributing to Vγ9Vδ2 T cells stimulation but is not equally expressed in all cancer tissues. Thus, the clinical outcome of such treatments is still a challenge. In this viewpoint, a critical picture of γδ T cells as effective anti-cancer effectors is designed, with a specific focus on the best immune-stimulating therapeutic schemes involving this lymphocyte subset and the tools available to measure their efficacy and presence in tumor tissues. Some pre-clinical models, useful to measure γδ T cell anti-cancer potential and their response to stimulating drugs, therapeutic monoclonal antibodies, or bispecific antibodies are described. Computerized imaging and digital pathology are also proposed as a help in the identification of co-stimulatory molecules and localization of γδ T cell effectors. Finally, two types of novel drug preparation are proposed: nanoparticles loaded with N-BPs and pro-drug formulations that enhance the effectiveness of γδ T lymphocyte stimulation.

Until now, despite 30 years of intensive work, the RV144 human immunodeficiency virus (HIV) vaccine trial initiated in 2003 remains so far the most protective vaccine prototype of all those tested (32% reduction in the infection rate three years after the vaccination) and the HIV epidemic is still spreading worldwide. In addition, antiretroviral therapy (ART) for people living with HIV is given for life as no other pharmacological intervention has allowed to maintain an undetectable viral load after ART withdrawal. Pr Andrieu and colleagues discovered tolerogenic CD8+T-cells that suppress simian immunodeficiency virus (SIV) specific activation, ensuing SIV reverse transcription suppression and viral replication-defective in Chinese macaques vaccinated by intragastric route with inactivated SIV particles + Lactobacillus rhamnosus. Moreover, in HIV-infected elite controllers with specific genetic features (HLA-1-Bw4-80i and KIR3DL1 genes), Pr Andrieu found out that similar tolerogenic CD8+T-cells suppress in the same manner HIV-specific activation, HIV reverse transcription, and HIV replication. These data justify the development of a tolerogenic vaccine composed of inactivated HIV particles + Lactobacillus rhamnosus that could be used as a preventive or therapeutic vaccine.

Although a large number of preventative human immunodeficiency virus (HIV) vaccine trials have been carried out during the last 30 years, it is remarkable that an effective HIV vaccine has not yet been developed. Research paradigms correspond to theoretical assumptions and particular strategies that scientists use when they try to solve a particular problem. Many paradigms used successfully in vaccinology were ineffective with HIV. For instance: 1) The structure-based reverse vaccinology approach failed because investigators tried to generate a vaccine starting with the antigenic structure of HIV-envelope (Env) epitopes bound to neutralizing monoclonal antibodies (mAbs) derived from HIV-infected individuals. They assumed that this antigenic structure would also possess the immunogenic capacity of inducing in vaccinees a polyclonal antibody (Ab) response with the same neutralizing capacity as the mAb. 2) The structures observed in epitope-paratope crystallographic complexes result from mutually induced fit between the two partners and do not correspond to the structures present in the free molecules before they had interacted. 3) The affinity-matured neutralizing mAbs obtained from chronically infected individuals did not recognize the germline predecessors of these Abs present in vaccinees. 4) The HIV p17 matrix protein that lines the inner surface of the viral membrane is one of the most disordered proteins identified on our planet and this prevents the induced Abs from binding to the glycosylated HIV gp120 protein. 5) Vaccinologists need to solve so-called inverse problems, for instance, guessing what are the multiple causes that produced an earlier wanted beneficial effect such as the absence of deleterious HIV infection in elite controllers. Since the immune system consists of numerous subsystems that have not yet been elucidated, it is impossible to solve the inverse problems posed by each subsystem. 6) Vaccinology is an empirical science that only sometimes succeeds because we do not understand the complex mechanisms that lead to protective immune responses.

Gamma delta lymphocytes (γδ T) sit at the interface between innate and adaptive immunity. They have the capacity to recognize cancer cells by interaction of their surface receptors with an array of cancer cell surface target antigens. Interactions include the binding of γδ T cell receptors, the ligands for which are diverse and do not involve classical major histocompatibility complex (MHC) molecules. Moreover, a variety of natural killer-like and fragment crystallizable gamma (Fcγ) receptors confer additional cancer reactivity. Given this innate capacity to recognize and kill cancer cells, there appears less rationale for redirecting specific to cancer cell surface antigens through chimeric antigen receptor (CAR) expression. Several groups have however reported research findings that expression of CARs in γδ T cells can confer additional specificity or functionality. Though limited in number, these studies collectively identify the potential of CAR-T engineering to augment and fine tune anti-cancer responses. Together with the lack of graft versus host disease induced by allogeneic γδ T cells, these insights should encourage researchers to explore additional γδ T-CAR refinements for the development of off-the-shelf anti-cancer cell therapies.

Allogeneic stem cell transplantation is currently the only curative approach for a variety of malignant and non-malignant diseases. In the early transplant era, the intent of this treatment was to apply an intensive myeloablative regimen to eliminate residual malignant cells followed by the hematopoietic rescue of the patients with donor hematopoietic stem cells. However, the focus has shifted over time and allogeneic transplantation is nowadays seen as a cellular therapy in which the donor-derived immune system mounts an anti-infectious and especially an anti-tumor effect in the posttransplant phase. In order to further augment the anti-tumor effect, various approaches have been developed, including the manipulation of the donor-derived immune system in vivo or the adoptive transfer of ex vivo-expanded donor-derived effector cells. Based on their lack of alloreactivity, γδ⁺ T cells are shifting into the spotlight of research in the context of allogeneic transplantation. Their exploitation with regard to their anti-infectious and anti-tumor properties and their in vivo and ex vivo manipulation will lead to new therapeutic approaches to improve the outcome of patients after allogeneic stem cell transplantation. In this review, the important role of γδ⁺ T cells in allogeneic matched and mismatched transplantation is summarized and an outlook is discussed on how to best make use of this unique cell population.

Avidity of immunoglobulin G (IgG) is defined as its binding strength to its target antigen. As a consequence of affinity maturation of the IgG response, avidity is maturing as well. Therefore, acute infections are characterized by low-avidity IgG, whereas past infections are usually associated with high-avidity IgG. Avidity maturation is also observed as a consequence of optimal vaccination. Avidity has been shown to play a significant role in protective humoral immunity in many microbial systems. After severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the situation is different compared to other viral infections, as the moderate degree of avidity reached in most cases of infection is similar to that reached after only one vaccination step. In contrast, two vaccination steps lead to a much higher avidity of IgG directed towards viral spike protein S1 (S1) in the majority of vaccinated individuals. Therefore, it seems that two vaccination steps allow for a more extended affinity/avidity maturation than natural infection. The degree of avidity maturation after two vaccination steps is heterogeneous. It can be further enhanced by a third vaccination step. Complete avidity maturation seems to depend on sustained availability of antigen during the maturation process. Variants of concern seem to increase the affinity of their receptor-binding domain (RBD) to angiotensin-converting enzyme-2 (ACE2) and/or to decrease the susceptibility for neutralizing antibodies. Classical neutralization tests do not necessarily reflect the avidity of neutralizing IgG, as they operationally dissect the binding reaction between S1 and IgG from the binding of the S1 to ACE2. This approach fades out critical competition reactions between IgG and ACE for RBD of the S1. Quantitative avidity determination might be an essential tool to define individuals that only possess suboptimal protective immunity after vaccination and therefore might benefit from an additional booster immunization.

γδ T cells express unique T cell receptor (TCR) γ and TCR δ chains, with structural and functional heterogeneity. Taking advantage of the diverse γδ TCR repertoire or other ligand-receptor interactions, γδ T cells can recognize a broad spectrum of tumor-associated antigens (TAAs) in a major histocompatibility complex (MHC)—independent manner, thereby activating downstream pleiotropic effects. γδ T cells recruited into the tumor microenvironment can act as effector cells to mediate cancer immune surveillance. Their advantage lies in the ability to perceive tumors with a low mutation load, thus establishing the first line of defense against pathogens. Activated γδ T cells exhibit strong cytotoxic activity and cytokine secretion functions and are effective antitumor lymphocytes with simple and direct recognition modes and rapid responses. However, the clinical application of tumor—infiltrating γδ T cells has certain limitations. First, γδ T cells exposed to complicated cytokine networks are potentially affected by multiple inhibitory mechanisms. Additionally, these cells show highly flexible and dynamic plasticity and are extremely easily polarized into regulatory phenotypes. This review further emphasizes the diversified cross-talk between γδ T cells and other immune cells. Effective immunity of the body is often manifested by counterbalance under mutual restriction. Therefore, an in-depth understanding of γδ T cells that play conflicting roles in the tumor microenvironment is necessary. These cells may be a key factor ultimately mediating the deviation of the antagonistic response between tumor inhibition and tumor promotion. Finally, it retrospectively analyze the activation strategies and clinical relevance of existing γδ T cell adoptive immunotherapies. According to current challenges, there is a need to explore innovative immunotherapies, maximize the tumor-killing efficacy of γδ T cells, and attenuate or eliminate tumor immunosuppression. It is hoped that the host immune status can be accurately predicted and gradually advance γδ T cell precise individualized medicine.

Antitumor immunity relies on the ability of T cells to recognize and kill tumor targets. γδ T cells are a specialized subset of T cells that predominantly localizes to non-lymphoid tissue such as the skin, gut, and lung where they are actively involved in tumor immunosurveillance. γδ T cells respond to self-stress ligands that are increased on many tumor cells, and these interactions provide costimulatory signals that promote their activation and cytotoxicity. This review will cover costimulatory molecules that are known to be critical for the function of γδ T cells with a specific focus on mouse dendritic epidermal T cells (DETC). DETC are a prototypic tissue-resident γδ T cell population with known roles in antitumor immunity and are therefore useful for identifying mechanisms that may control activation of other γδ T cell subsets within non-lymphoid tissues. This review concludes with a brief discussion on how γδ T cell costimulatory molecules can be targeted for improved cancer immunotherapy.

In recent years, immunologists have been working to utilize the functional mechanism of the immune system to research new tumor treatment methods and achieved a major breakthrough in 2013, which was listed as one of the top 10 scientific breakthroughs of 2013 by Science magazine (see “Cancer immunotherapy”. Science. 2013;342:1417. doi: 10.1126/science.1249481). Currently, two main methods are used in clinical tumor immunotherapy: immune checkpoint inhibitors and chimeric antigen receptor (CAR) T cells. Clinical responses to checkpoint inhibitors rely on blockade of the target neoantigens expressed on the surfaces of tumor cells, which can inhibit T cell activity and prevent the T cell immune response; therefore, the therapeutic effect is limited by the tumor antigen expression level. While CAR-T cell therapy can partly enhance neoantigen recognition of T cells, problems remain in the current treatment for solid tumors, such as restricted transport of adoptively transferred cells to the tumor site and off-targets. Immunologists have therefore turned their attention to γδ T cells, which are not restricted by the major histocompatibility complex (MHC) for neoantigen recognition and are able to initiate a rapid immune response at an early stage. However, due to the lack of an understanding of the antigens that γδ T cells recognize, the role of γδ T cells in tumorigenesis and tumor development is not clearly understood. In the past few years, extensive data identifying antigen ligands recognized by γδ T cells have been obtained, mainly focusing on bisphosphonates and small-molecule polypeptides, but few studies have focused on protein ligands recognized by γδ T cells. In this paper, we reviewed and analyzed the tumor-associated protein ligands of γδ T cells that have been discovered thus far, hoping to provide new ideas for the comprehensive application of γδ T cells in tumor immunotherapy.

γδ T cells are one of the immune cell types that express antigen receptors. γδ T cells are able to recognize pathogens or cancer cells independently of human leukocyte antigen restriction, which is an important feature of αβ T cells. Therefore, γδ T cells are considered the bridge between innate and adaptive immunity. These cells exhibit important roles in immune surveillance, exert immune defense against tumors and have become promising effector cells for cancer immunotherapy. However, in particular circumstances, the tumor microenvironment seems to render γδ T cells immunosuppressive and even tumor-promoting, emphasizing the importance of regulating γδ T functions in realizing their translation into practical cancer immunotherapy. In recent years, increasing evidence has demonstrated that the intratumoral and peritumoral microbiota can have complex effects on tumor immunology. Thus, understanding the role of microbiota in the crosstalk between γδ T cells and tumors will provide insights for developing adjuvant immunotherapy with precise regulation of tumor-related microbiota. In the present review, the effects of microbiota on γδ T cell receptor repertoire and the roles of microbiota in some common tumors will be discussed, with implications for future cancer therapy.

In recent decades, abundant methods for targeted tumor cell immunotherapy have been developed. It was recently discovered that excellent curative effects observed in hematological tumors cannot be achieved in solid tumors, as serious side effects will occur. These are all derived from engineered adaptive immune cells, the use of which will bring limitations. γδT cells have a unique ability to respond to a variety of tumor cells while linking innate immunity and adaptive immunity, and thus, they are an ideal source of therapeutic allogeneic cells. This review introduces strategies that can optimize the clinical application of γδT cells to provide novel ideas for adoptive immunotherapy in the future.

Endometriosis is an inflammatory oestrogen-dependent chronic disease and is mainly expressed by pain and increased infertility. Several studies showed an increased prevalence of autoimmune systemic diseases and various autoantibodies in endometriosis. The association of these autoimmune markers and diseases could raise the fact that endometriosis is an authentic autoimmune or inflammatory disease and thus could argue for the use of immunomodulatory therapies. Usually, it is considered that the autoantibodies did not directly act in endometrium implants growth, and could be rather implicated in endometriosis-related infertility. The use of immunomodulatory strategies could be an important alternative or additional strategy to the use of hormones and surgery but need prospective well-designed trials.

A few pieces of research exist about the protective titer against severe acute respiratory syndrome (SARS) coronavirus 2 (CoV-2; SARS-CoV-2) in monkeys and humans in which the protection could be shown as dose-dependent. Early studies supposed that higher levels of pre-existing neutralizing antibodies (Nabs) against SARS-CoV-2 can potentially correlate with the protection to consequent infection. The data so far showed that cellular immunity is as essential as the humoral one. If needed, its presence can be beneficial if the titer of immunoglobulins is not optimal. It is also known that the immune response to the vaccine is similar to the one after natural infection with a production of very high naturalization titers antibodies. However, medical community is still unaware of the immunoglobulin titer needed for protection against the virus. The answers to the questions regarding correlates of protection are yet to be discovered. Still, no studies indicate a specific virus-Nab titer, so one can assume a patient is protected from being infected in the future. The evoked immunological response is indeed encouraging, but a future investigation is needed. Nonetheless, it remains a mystery how long the immunity lasts and whether it will be enough to shield the patients in the long run. Therefore, identifying immune protection correlations, including neutralization titer of antibodies and T cell immune response against SARS-CoV-2, could give a clue. Unfortunately, recent studies in the field have been more controversial than concise, and the data available is far from consensus.

One of the most troubling developments of 2021 has been the number of fertile-age women who have been led to believe that mRNA vaccines against severe acute respiratory syndrome coronavirus-2 [SARS-CoV-2, coronavirus disease 2019 (COVID-19)] can cause infertility via cross-reactivity of immune response. Specifically, cross-reactivity of developed antibodies to syncytin-1, a protein found in human cell fusion, placentation and recently identified in the envelope gene of a human endogenous defective retrovirus, HERV-W (see “Syncytin is a captive retroviral envelope protein involved in human placental morphogenesis”. Nature. 2000;403:785–9. doi: 10.1038/35001608). The mechanism, evidence, and evaluation of the claim is presented concluding in a rejection due to lack of evidence.

It is well recognized that immune tolerance is important to prevent semiallografted fetuses from rejection by maternal immunocompetent cells; however, immune activation also plays an important role in placental development and fetal growth. Basic and clinical studies have shown that an imbalance between immune activation and regulation can lead to implantation failure, miscarriage, and preeclampsia. Here, the balance between immunostimulation and immunoregulation in reproduction will be reviewed.

The coronavirus disease 2019 (COVID-19) results from the infection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and primarily affects the respiratory tissue. Since first reported from Wuhan, China in December 2019, the virus has resulted in an unprecedented pandemic. Vaccination against SARS-CoV-2 can control the further spread of the ongoing pandemic by making people immunised to SARS-CoV-2. Several vaccines have been approved for use in clinics, a lot many are in different stages of development. Diligent interpretations from the preclinical evaluation are crucial to identify the most effective and safest vaccine candidates. Multiple vaccine candidates/variants have been tested in small animal models with relative ease and further in non-human primate models before being taken into clinical development. Here, we review the state-of-the-art strategies employed for a thorough preclinical evaluation of COVID-19 vaccine candidates. We summarise the methods in place to identify indicators which make the vaccine candidate effective in controlling SARS-CoV-2 infection and/or COVID-19 and are safe for administration as inferred by their (1) biophysical/functional attributes (antigen expression, organization, functionality, and stability); (2) immunogenicity in animal models and protective correlates [SARS-CoV-2 specific binding/neutralising immunoglobulin titer, B/T-cell profiling, balanced T-helper type-1 (T_h1) or type-2 (T_h2) response (T_h1:T_h2), and anamnestic response]; (3) protective correlates as interpreted by controlled pathology of the respiratory tissue (pulmonary clinical and immunopathology); and finally, (4) strategies to monitor adverse effects of the vaccine candidates.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a highly pathogenic β-coronavirus, is the etiologic agent of coronavirus disease 2019 (COVID-19), which gave rise to a difficult to control pandemic, especially in Brazil. Approximately 4,000 mutations have been identified in SARS-CoV-2, with the majority being redundant without having any biological effect on the virus. The aim of the present study was to objectively understand how new SARS-CoV-2 variants can affect vaccine response, in addition to highlighting the current situation in Brazil in the face of the pandemic and considering epidemiological and immunological aspects of COVID-19. The main protective correlate investigated in most vaccines is the neutralizing antibody titer induced by immunizing agents, observed in the pre-clinical phase in animals, whose action is to block the binding of the spike protein to the angiotensin-converting enzyme 2 (ACE2) receptor, preventing infection. Up to the second half of 2021, the variants that are of greatest concern worldwide and require molecular surveillance are Alpha variant (or B.1.1.7 lineage), Beta (or B.1.351 lineage), Gamma (or P1 lineage) and Delta (or B.1.617.2 lineage). Brazil finds itself in a highly unfavorable scenario, with the circulation of variants of concern, mainly Gamma and Delta, with high fatality rates for COVID-19 and low vaccination rate. Given the still latent situation of the COVID-19 pandemic in Brazil, the lack of global planning for action strategies for non-pharmacological prevention measures, there is an imminent risk of the emergence of new variants due to the finding of susceptible hosts and the high proliferative rate of SARS-CoV-2. It is urgent to increase the genotyping of positive samples isolated from infected individuals, the speed of vaccination of the entire population and the unification of non-pharmacological preventive measures throughout the country.

Cutaneous homeostasis is maintained by dynamic cellular communications between different cell types in the skin through interactions with various mediators, including cytokines, chemokines and antimicrobial peptides/proteins (AMPs). Keratinocytes, as the major cell type of the epidermis, not only form a passive physical barrier, but also actively participate in the pathogenesis of many, if not all, inflammatory skin diseases. Keratinocytes highly interact with immune cells to shape, amplify or regulate inflammatory responses, thus triggering and/or sustaining these inflammatory skin diseases. In this review, crosstalk between keratinocytes and immune cells is summarized, and its contributions to two major inflammatory skin disorders including psoriasis and atopic dermatitis are highlighted.

The foetus expressing paternal antigens ought to be “rejected” by the maternal immune system. However, the immunological relationship of the mother and the foetus does not follow the rules of transplantation immunology. Maternal immune functions are re-adjusted during pregnancy, to create a tolerant environment for the developing foetus. Progesterone and its downstream mediator; the progesterone induced blocking factor (PIBF) are important in this process. The mRNA transcribed from the PIBF1 gene contains 18 exons, and codes for a 90 kDa protein. The 90 kDa form is associated with the centrosome and plays a role in cell cycle regulation, while smaller isoforms produced by alternative spicing are secreted, and bind to the glycosylphosphatidylinositol (GPI) anchored PIBF receptor. Upon ligation, the former forms a heterodimer with the alpha chain of the interleukin-4 (IL-4) receptor and activates the Janus kinase/signal transducers and activators of transcription (Jak/STAT) pathway, via which, PIBF induces increased production of T helper2 (Th2) cytokines. PIBF regulates natural killer (NK) cytotoxicity, by inhibiting perforin release from the cytoplasmic granules of NK cells. During normal human pregnancy, the serum concentrations of PIBF increase with gestational age, and lower than normal serum levels predict spontaneous pregnancy termination. Depletion of PIBF during the peri-implantation period in mice, results in lower implantation and increased resorption rates, together with increased decidual and peripheral NK activity, downregulation of the genes implicated in T cell activation in CD4⁺ cells, and Th1 differentiation of the T cells. PIBF is expressed in rapidly proliferating immature cells as well as several tumours, and regulates invasion. The PIBF gene has been identified in the chromosomal region 13q21-q22—which is a common site for somatic deletions in a variety of malignant tumours. These data suggest that PIBF might be involved in tumorigenesis.

This article is a tribute and homage to Gerard Chaouat who invited me to contribute this article. My years in France have remained very memorable to me. Reviewed briefly is the vaccine that was made against human chorionic gonadotropin (hCG) to prevent unwanted pregnancy in sexually active women. It has now been developed as a genetically engineered recombinant vaccine and passed onto industry for its production under good manufacturing practices (GMP) conditions for confirmatory trials. The trials have received the approval of the Drugs Controller General of India. The trials have started but have been interrupted by the coronavirus disease 2019 (COVID-19) pandemic. This vaccine is likely to have another highly beneficial application in the treatment of cancers expressing ectopically hCG.

Coronavirus disease 2019 (COVID-19) emerges as an expeditiously growing pandemic, in the human population caused by the highly transmissible RNA virus severe acute respiratory syndrome of coronavirus 2 (SARS-CoV-2). Prognosis of SARS-CoV-2 infection predominantly occurs at the angiotensin-converting enzyme 2 receptor and transmembrane protease serine type 2 positive (ACE2 + TMPRSS2)⁺ epithelial cells of the mucosal surface like nasal, oral mucosae, and/or the conjunctival surface of the eye where it has interacted along with the immune system. The primary host response towards the pathogen starts from an immune microenvironment of nasopharynx-associated lymphoid tissue (NALT) and mucosa-associated lymphoid tissue (MALT). The presence of exhausted lymphocytes, lymphopenia, pneumonia and cytokine storm is the hallmark of COVID-19. The multifaceted nature of co-morbidity factors like obesity and type 2 diabetes and its effects on immunity can alter the pathogenesis of SARS-CoV-2 infection. Adipose tissue is a crucial endocrine organ that secretes a plethora of factors like adipokines, cytokines, and chemokines that have a profound impact on metabolism and augments the expression of mucosal pro-inflammatory cytokines, like tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), and the interleukin-12 (IL-12)/IL-23. Mucosal immunization could be a superior approach to activate mucosal and systemic immune responses against pathogenic invasion at mucosal surface entry ports. Mucosal vaccines are also able to generate strong systemic humoral immunity—required to neutralize any virus particle that dodges the primary immune response. To develop an efficient vaccine against mucosal pathogens, considering the designing of the delivery route, immunomodulatory features, and adjuvants are very important. In this article, we further provide evidence to understand the significant role of mucosal immunity, along with secretory and circulating immunoglobulin A (IgA) antibodies in generating a novel mucosal vaccine against COVID-19. Moreover, along with mucosal vaccines, we should look for combination treatment strategies with plant bioactive molecules. Glycan-binding lectins against viral proteins for targeted activation of mucosal immune response are one of such examples. This might play a promising role to halt this emerging virus.

Vaccination against coronavirus disease 2019 (COVID-19) is one of the most effective tools to curb the pandemic. Multiple vaccine candidates based on different platforms are available for emergency use presently. However, in common all the vaccines target spike protein, which is a dominant immunogen of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2). Adequate immunogenicity and efficacy are demonstrated by many of the vaccines in clinical phase III trials. The emergence of the new variant of concern is believed to be associated with less susceptibility to the post-infection or post-vaccination mounted immunity. It is a global concern currently threatening the progression of the vaccination drive. Nevertheless, the results of the presently available phase III clinical trials promote COVID-19 vaccination to prevent disease severity and COVID-19 related deaths. Cross-immunity towards the new variants of concern especially against the South African variant is yet to be explored and managed adequately.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; βCoV), the causative agent of coronavirus disease 2019 (COVID-19), causes severe lower respiratory tract infections and acute respiratory failure syndrome (ARDS). Deaths due to the ongoing COVID-19 pandemic for more than a year are still seen worldwide. Therefore, vaccine trials have gained importance. The discovery of the genome and protein structure of SARS-CoV-2 in a short time allowed the development of nucleic acid-based vaccines (mRNA and DNA vaccines), vector vaccines, inactivated virus vaccines, protein-based vaccines, virus-like particle vaccines, and live attenuated virus vaccines. Many companies, universities, and institutes around the world continue to develop effective vaccines against SARS-CoV-2. In this review, the structural features, classification, genome, and intracellular entry of SARS-CoV-2 coronaviruses, stimulation of the immune system and immunity, COVID-19 vaccine types, and the latest status of clinical trials of these vaccines have been reviewed.

The maternal syndrome preeclampsia is triggered by syncytiotrophoblast (STB) stress; the heterogeneity of the syndrome is caused by the different pathways leading to this STB stress. Inflammation plays a pivotal role in the pathogenesis of preeclampsia. While, the immune system at large is therefore intimately involved in the causation of this heterogeneous syndrome, the role of the adaptive immune system is more controversial. The classic paradigm placed preeclampsia as the disease of the nulliparous pregnant women. Up to the later part of the 20th century, human reproduction, particularly in Western societies, was characterised by a low rate of pre-marital sex, and the great majority of children being born within one stable sexual relationship. More prolonged periods of regular sexual intercourse within a stable relationship have been demonstrated to reduce the risk of preeclampsia and fetal growth restriction. Primarily animal studies have indeed shown that repetitive sperm exposure leads to partner specific mucosal tolerance. Societal changes made partner change over the reproductive period of individual women extremely common. For the adaptive immune system of multiparous women, being pregnant in a new sexual relationship (primipaternity) would represent being faced with a new “hemi-allograft”. In these pregnancies, potential couple-specific immune “maladaptation” could lead to the superficial cytotrophoblast invasion of the spiral arteries, known to be associated with early-onset preeclampsia. Having a new pregnancy in a different relationship does indeed increase the risk for this type of preeclampsia. Large epidemiologic population studies identified prolonged birth interval but not “primipaternity” as a risk factor for preeclampsia in multiparous women. This apparent contradiction is explained by the fact that the great majority of preeclampsia cases in these population studies involve term preeclampsia. In late-onset preeclampsia, the far more common phenotype of the syndrome, STB stress is not caused by lack of proper spiral artery modification, but involves maternal genetic predisposition to cardiovascular and metabolic disease, with in particular obesity/metabolic syndrome representing major players. Partner or couple specific issues are not detectable in this disease phenotype.

The testis is designated as one of the immune previleged sites in the body and harbours a unique immunoregulatory environment, which is important for preventing an immune response against sperm antigens which otherwise are recognized as “foreign” by the immune system. The blood-testis barrier along with the unique immune cells repertoire and various immunoregulatory & immunosuppressive factors secreted by the Leydig cells, Sertoli cells and peritubular cells act in concert to maintain the tolerogenic environment in the testis. Abberations in immunotolerant mechanisms in the testis can lead to generation of anti-sperm antibodies that have an association with male infertility. It can also lead to inflammatory conditions of the male reproductive tract manifested as epididymitis and orchitis, generally due to bacterial or viral infections. In addition, non-infectious epididymitis and orchitis, having autoimmune origin have also been reported in males. While the immune privilege status of human testis protects the germ cells from an immune attack, it can also make the testis a succeptible reservoir for viruses such as human immunodeficiency virus-1, Zika virus and severe acute respiratory syndrome coronavirus-2, all of which have adverse consequences on male reproduction.

Viral vectors have been frequently applied for vaccine development. It has also been the case for vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to tackle the coronavirus disease 2019 (COVID-19) pandemic. A multitude of different viral vectors have been mainly targeting the SARS-CoV-2 spike (S) protein as antigen. Intramuscular injection has been most commonly used, but also intranasal administration has been tested. Adenovirus vector-based vaccines are the most advanced with several vaccines receiving Emergency Use Authorization (EUA). The simian ChAdOx1 nCoV-19 vaccine applied as a prime-boost regimen has provided 62.1–90% vaccine efficacy in clinical trials. The Ad26.COV2.S vaccine requires only one immunization to provide protection against SARS-CoV-2. The rAd26-S/rAd5-S vaccine utilizes the Ad26 serotype for the prime immunization followed by a boost with the Ad5 serotype resulting in 91.2% vaccine efficacy. All adenovirus-based vaccines are used for mass vaccinations. Moreover, vaccine candidates based on vaccinia virus and lentivirus vectors have been subjected to clinical evaluation. Among self-replicating RNA viruses, vaccine vectors based on measles virus, rhabdoviruses, and alphaviruses have been engineered and tested in clinical trials. In addition to the intramuscular route of administration vaccine candidates based on influenza viruses and adenoviruses have been subjected to intranasal delivery showing antibody responses and protection against SARS-CoV-2 challenges in animal models. The detection of novel more transmissible and pathogenic SARS-CoV-2 variants added concerns about the vaccine efficacy and needs to be monitored. Moreover, the cause of recently documented rare cases of vaccine-induced immune thrombotic thrombocytopenia (VITT) must be investigated.

Both innate and adaptive immune cells exist in the skin, predominantly in the dermis layer. Recent studies have focused on how and which circadian rhythms contribute to maintain good health. Over recent years, we have gained a better understanding of the molecular mechanisms that control biological clocks and circadian rhythms. Circadian rhythms maintain homeostasis by providing day and night information to various physiological functions of our body. However, excessively high immune system activity can lead to a risk of developing autoimmune or allergic diseases. Recently, increasing numbers of studies with human and mouse models have been conducted to investigate the mechanisms underlying circadian regulation of the skin homeostasis. In this review, circadian regulation in the skin will be discussed from different points of view. Skin is referred as the largest organ of the body and is directly exposed to the external environment, including large changes in diurnal temperature, light, and pathogens. Immune cells as well as skin cells are the ones protecting us from these stimulants. Associations of the circadian system and these cells have been revealed in many ways, however, the specific roles of the peripheral clocks in these cells remain unknown. Circadian regulation in the skin diseases is discussed specifically in atopic dermatitis and other skin allergic symptoms as well as psoriasis.

There have been significant developments in the design of nanostructured scaffolds for eliciting robust immune responses named vaccine. The technique is to produce strong immune responses is to manipulate the appearance of a pathogen. Subsequently pathogens such as viruses and bacteria often demonstrate of multiple copies of ligands on their surfaces, the immune system is predominantly sensitive towards multivalent presentations of antigens. Consequently, when designing a vaccine, it is beneficial to garnish a nanostructured surface with multiple copies of an antigen so it can effectively act as an immune booster. Different methods are there for the development of the vaccine, from them most of the techniques are well developed and reported and some of in the developing state. This review focuses primarily on cellular and non-cellular vaccines, the whole cells or cellular proteins either as the source of antigens or the platform in which to deliver the antigens. Purpose of this review, understand and discussion on the various vaccine platforms which will contribute noteworthy information to vaccine research and development (R and D).

There are various types of skin immune responses including inflammatory skin diseases and skin malignancy. Macrophages and fibroblasts are skin resident cells that had been overlooked in terms of immunological research targets. In this review, cross talk among macrophages, fibroblasts, and migratory immune cells in skin diseases such as atopic dermatitis (AD), contact hypersensitivity, psoriasis, systemic sclerosis, melanoma, and cutaneous T-cell lymphoma is described. Macrophages are important in AD by antigen-presenting phagocytosis, production of inflammatory cytokines, removal of apoptotic cells, and mediating clusters between dendritic cells (DCs) and T cells. They are also increased in lesional skin of psoriasis, especially in stable plaques, and an increased ratio of M1/M2 macrophages and tumor necrosis factor-α production by macrophages are essential for development of psoriasis. The progression of skin malignancy is mediated by macrophages through promotion of tumor survival pathways via expression of cytokines and growth factors, interaction with regulatory T cells (Tregs) and myeloid-derived suppressor cells, and suppression of function of tumor-infiltrating T cells by immunosuppressive cytokines and programmed death-ligand (PD-L)1. Fibroblasts play important roles in development and maintenance of AD lesions through expression of CC chemokine ligand (CCL)17, CCL11, CCL26, C-X-C motif chemokine ligand (CXCL)12, CCL19, and periostin, interacting with T helper (Th)2 cells, natural killer T (NKT) cells, DCs, and keratinocytes. They also play important roles in psoriasis, expressing interleukin (IL)-8 and vascular endothelial growth factor, production of fibronectin, and changes in the proteomic profiles. Fibroblasts have a critical role in the progression skin malignancy via expression of cytokines, suppression natural killer (NK) functions, and establishment of Th2-dominant microenvironment. Thus, cross talk among macrophages, fibroblasts, and migratory immune cells including T cells, DCs, and NK cells in skin diseases is important and those skin-resident cells are attracting therapeutic targets in the near future.

Understanding the interactions of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) with humans is deeply grounded in immunology, from the diagnosis to pathogenesis, from the clinical presentations to the epidemiology, prevention, and treatment. However, the difficulty of capturing the complex and changeable array of immunological concepts and incorporating them into the strategies of control of the SARS-CoV-2 pandemic poses significant hindrances to establish optimal public health policies. The contribution of immunology to the control of the pandemic is to shed light on the features and mechanisms of the protective immunity elicited by SARS-CoV-2 infection and vaccines. Do they induce effective protective immunity? How? For how long? What is the effect of vaccination on individuals who were previously infected? To appropriately answer these questions, it is necessary to get rid of the outdated notion of a naïve, static, and closed immune system, which leads to misconceptions about susceptibility, specificity, immunological memory, and protective immunity. The present essay discusses these issues based on current immunological concepts.

Head and neck squamous cell carcinoma (HNSCC) is a relatively widespread cancer with high mortality rates. Many patients with locally advanced disease are treated with combinations of surgery, radiation, and chemotherapy, while others are considered incurable and develop recurrent/metastatic (R/M) disease. Despite these treatment modalities, the 5-year survival rate of HNSCC has remained at 50% due to limited treatment options in patients with recurrent disease. Immunotherapy has been shown to induce durable responses in R/M patients, but only a minority of patients currently respond. A major hurdle in tumor immunotherapy is identifying the non-responders and markers to predict resistance in patients who at first responded to the therapy. In HNSCC patients, the tumor microenvironment (TME) assumes a vital role to either diminish or augment immune responses. There is an urgent need for extensive studies to be undertaken to better understand how tumor cells escape immune surveillance and resist immune attack. In this review, the impact of TME on the efficiency of immunotherapy, addressing the factors that mediate therapy resistance are highlighted. The composition of the TME encompassing the immunosuppressive cells including myeloid-derived suppressor cell (MDSC), regulatory T cells (Treg), mesenchymal stem cell (MSC), cancer-associated fibroblast (CAF), and tumor-associated macrophages (TAMs) and intrinsic factors like hypoxia, reactive oxygen species (ROS), extracellular matrix (ECM), angiogenesis, and epithelial-mesenchymal transition (EMT), how this debilitates immunosurveillance, and also discuss existing and potential strategies aimed at targeting these cellular and molecular TME components are reviewed. Understanding the interactions between the TME and immunotherapy is not only important in dissevering the mechanisms of action of immunosuppression but also offers scope for developing newer strategies to improve the competence of current immunotherapies.

Coronavirus disease-2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus (SARS-CoV)-2 spread globally and creates an alarming situation. Following the SARS-CoV-2 paradigm, therapeutic efficacy is achieved via repurposing several antiviral, antibacterial, and antimalarial drugs. Innate and adaptive immune cells work close to combat infection through the intricate production of antibodies (Abs) and inflammatory cytokines. As an essential component of the immune system, Abs play an important role in eliminating viruses and maintaining homeostasis. B lymphocytes (B cells) are effector cells, stringent to produce neutralizing Abs to combat infection. After recognizing SARS-CoV-2 antigens by a surface receptor called B cell receptors (BCRs) on the plasma membrane, the BCRs transmembrane signal transduction and immune activation results in Ab production and development of immune memory. Thus, it ensures that plasma B cells can quickly start an intricate immune response to generate efficient protective Abs to clear the pathogen. Nevertheless, considering therapeutic challenges in the context of the new coronavirus pandemic, this review addresses the molecular mechanism of the immune activation and function of novel SARS-CoV-2 specific B cells in the production of SARS-CoV-2 specific Abs. Additionally, these studies highlighted the Ab-mediated pathogenesis, the intriguing role of nano-scale signaling subunits, non-structural proteins during COVID-19 infection, and structural insights of SARS-CoV-2 specific Abs.

Mesenchymal stromal cells (MSCs) are a mesodermal stem cell population, with known self-renewal and multilineage differentiation properties. In the last century, MSCs have been widely used in regenerative medicine and tissue engineering approaches. MSCs initially were isolated from bone marrow aspirates, but currently have been identified in a great number of tissues of the human body. Besides their utilization in regenerative medicine, MSCs possess significant immunoregulatory/immunosuppressive properties, through interaction with the cells of innate and adaptive immunity. MSCs can exert their immunomodulatory properties with either cell-cell contact or via paracrine secretion of molecules, such as cytokines, growth factors and chemokines. Of particular importance, the MSCs’ immunomodulatory properties are explored as promising therapeutic strategies in immune-related disorders, such as autoimmune diseases, graft versus host disease, cancer. MSCs may also have an additional impact on coronavirus disease-19 (COVID-19), by attenuating the severe symptoms of this disorder. Nowadays, a great number of clinical trials, of MSC-mediated therapies are evaluated for their therapeutic potential. In this review, the current knowledge on cellular and molecular mechanisms involved in MSC-mediated immunomodulation were highlighted. Also, the most important aspects, regarding their potential application in immune-related diseases, will be highlighted. The broad application of MSCs has emerged their role as key immunomodulatory players, therefore their utilization in many disease situations is full of possibilities for future clinical treatment.

Skin is the largest organ of the body having multifunctional activities. It has a dynamic cellular network with unique immunologic properties to maintain defensive actions, photoprotection, immune response, inflammation, tolerogenic capacity, wound healing, etc. The immune cells of the skin exhibit distinct properties. They can synthesize active vitamin D [1,24(OH)₂D₃] and express vitamin D receptors. Any difficulties in the cutaneous immune system cause skin diseases (psoriasis, vitiligo, atopic dermatitis, skin carcinoma, and others). Vitamin D is an essential factor, exhibits immunomodulatory effects by regulating dendritic cells’ maturation, lymphocytes’ functions, and cytokine production. More specifically, vitamin D acts as an immune balancing agent, inhibits the exaggeration of immunostimulation. This vitamin suppresses T-helper 1 and T-helper 17 cell formation decreases inflammatory cytokines release and promotes the maturation of regulatory T cells and interleukin 10 secretion. The deficiency of this vitamin promotes the occurrence of immunoreactive disorders. Administration of vitamin D or its analogs is the therapeutic choice for the treatment of several skin diseases.

Arginase-1 (Arg1) and the inducible nitric oxide synthase 2 (NOS2) compete for the common substrate L-arginine, semi-essential amino acid, and central intestinal metabolite. Both enzymes exhibit various, sometimes opposing effects on immune responses, tissue regeneration, or microbial growth and replication. In sub-mucosal tissues of patients suffering from inflammatory bowel disease (IBD), similar as in experimental colitis, the expression and activity of both enzymes, Arg1 and NOS2 are more prominent than in respective controls. Accordingly, the metabolism of L-arginine is altered in IBD patients. Thus, L-arginine represents a promising medical target for clinical intervention in these devastating diseases. Previous studies primarily focused on the host side of L-arginine metabolism. Initial reports using Arg1 inhibitors generated conflicting results in murine colitis models. Subsequently, only the generation of conditional Arg1 knockout mice allowed reliable functional analyses of Arg1 and the L-arginine metabolism in the immune system. Utilizing cell-specific conditional Arg1 knockouts, we have recently reported that Arg1, surprisingly, hampered the resolution of experimental colitis due to the restriction of the intraluminal availability of L-arginine. Reduced levels of L-arginine restrained the compositional diversity of the intestinal microbiota and subsequently the mutual metabolism between the microbiota and the host. Thus, the intraluminal microbiota represents a potential therapeutic target for L-arginine metabolism aside from host-dependent L-arginine consumption.

As the severe acute respiratory syndrome coronavirus (SARS-CoV)-2 is a new virus, the current knowledge on the immunopathogenesis of this newly emerged SARS-CoV-2 is beginning to unravel with intensive ongoing global research efforts. Although a plethora of new studies have been published in a short space of time describing how the virus causes disease and incurs insults on the host immune system and the underlying immunopathogenic mechanisms remain to be elucidated. Thus, the discussion in this review is based on the most current knowledge on the immunopathogenesis of SARS-CoV-2 that has emerged in the past 12 months. The main objective is to shed light on the most current concepts in immunopathological aspects of the lung, bloodstream, and brain caused by the SARS-CoV-2, which has led to the current pandemic resulting in > 100 million infections and > 2 million deaths, and ongoing.

Immunity is continuously evolving by evolutionary mechanisms shaped by pathogenic stimuli of different kinds. Man-made nanomaterials (NMs) have been developed in the last decades and represent a novel challenge for our immune system, especially when applied to medical science. Toxicological studies of such nanoparticles (NPs) revealed that size, shape, and surface chemistry are key parameters to understand their noxious effects on cellular mechanisms. Less is known on the immune reactions to NMs since prolonged exposure data are not so detailed as the results for acute administration. The importance of immunity to biocompatible NPs is underlined by their increasing use as drug or gene delivery carriers in common pharmaceutical preparations and vaccines. In the latter case, the immunomodulatory properties of NMs allow their use also as efficient adjuvants to enhance the innate immune response. In the current manuscript, the authors discuss the main concepts in this fast-growing field by restricting our view to NMs with consolidated application in biomedicine.

Interleukin (IL)-22 is produced from immune cells such as T helper (Th)22 cells, Th17/22 cells, and group 3 innate lymphoid cells. IL-22 signals via the IL-22 receptor 1 (IL-22R1) and the IL-10 receptor 2 (IL-10R2). As the IL-22R1/IL-10R2 heterodimer is preferentially expressed on border tissue between the host and the environment, IL-22 is believed to be involved in border defense. Epidermal keratinocytes are the first-line skin barrier and express IL-22R1/IL-10R2. IL-22 increases keratinocyte proliferation but inhibits differentiation. Aryl hydrocarbon receptor (AHR) is a chemical sensor and an essential transcription factor for IL-22 production. In addition, AHR also upregulates the production of barrier-related proteins such as filaggrin in keratinocytes, suggesting a pivotal role for the AHR-IL-22 axis in regulating the physiological skin barrier. Although IL-22 signatures are elevated in atopic dermatitis and psoriasis, their pathogenic and/or protective implications are not fully understood.

Atopic dermatitis (AD) is characterized by skin barrier disruption, type 2 immune dysregulation, chronic pruritus, and abnormal colonization by Staphylococcus aureus (S. aureus). Tapinarof, an aryl hydrocarbon receptor modulator, has been demonstrated to attenuate the development of AD in clinical studies. Recently, we found that tapinarof upregulated the expression of filaggrin and loricrin, which are essential proteins in skin barrier functions. Paradoxically, tapinarof induced interleukin (IL)-24 secretion by normal human keratinocytes. IL-24 is produced by T helper 2 lymphocytes and keratinocytes following stimulation by type 2 cytokines, and IL-24 is upregulated in the skin of patients with AD. Furthermore, IL-24 contributes to skin barrier disruption and hyperplasia in AD, and it may exacerbate skin inflammatory responses, itch, and S. aureus infection. In this review, we summarized the current findings regarding the detrimental role of IL-24 in AD, thereby suggesting that co-treatment of tapinarof with therapeutics that block IL-24 signaling may represent a promising strategy for managing AD.