Hepatitis D virus (HDV), a satellite virus requiring hepatitis B surface antigen (HBsAg) for propagation, is a hepatotropic virus implicated in acute and chronic viral hepatitis, with an accentuated risk of cirrhosis and hepatocellular carcinoma. The epidemiology of HDV infection is underestimated owing to underdiagnosis and low screening rates. Being inherently defective, HDV depends on HBsAg, the envelope protein of the hepatitis B virus (HBV), for hepatocyte entry and exit. However, viral replication is then HBV-independent but dependent on the host cell RNA polymerases. Infection can either be a coinfection with HBV or superinfection in individuals with pre-existing HBV, with the latter exhibiting a higher propensity for progression to chronicity. Clinical manifestations could range from acute hepatitis to acute flares in chronic hepatitis to rapidly progressive chronic liver disease. For decades, the treatment of HDV infection relied heavily on conventional and pegylated interferons (PEG-IFNs), which, despite limited efficacy and high relapse rates, continue to be a therapeutic option in patients with compensated liver disease. The past decade witnessed an advanced understanding of HDV virology and pathogenesis, which led to the development of multiple specific and targeted therapeutic agents, most notably the HDV viral entry inhibitor, bulevirtide, and the prenylation inhibitor, lonafarnib. In 2020, bulevirtide became the first drug approved in the European Union to treat chronic HDV with compensated liver disease. The emergence of lambda interferons, nucleic acid polymers, RNA silencers, and immune modulators further expands the therapeutic landscape. Combination regimens leveraging complementary mechanisms are promising but require further validation to optimize dosing and treatment durations. While novel therapies provide hope, significant unmet needs remain, especially for patients with decompensated cirrhosis. Future research must prioritize comprehensive strategies to enhance treatment efficacy and accessibility, offering a brighter prognosis for those affected by this devastating virus.

Pancreatic cystic lesions are frequently found incidentally on cross-sectional imaging and are broadly classified into mucinous and non-mucinous cysts. While some exhibit benign behavior, others have a malignant potential and are considered noninvasive precursors of pancreatic ductal adenocarcinoma. Guidelines from various societies propose risk stratification based on morphologic features and cyst fluid analysis. Fluid analysis through EUS-guided fine needle aspiration contributes to improved classification and recently, targeted DNA or RNA-based next generation sequencing is emerging as a critical investigation tool for diagnostic confirmation and risk stratification of pancreatic cysts. Each of these modalities has specific strengths and limitations, highlighting the need for a multi-modal approach for comprehensive assessment to guide clinical decision making. In this perspective, we aim to provide a thorough clinicopathologic framework for diagnosing and risk stratifying pancreatic cysts encompassing imaging findings, cyst fluid analyses, and next generation sequencing.

Diverticular disease of the colon is a very important digestive disease and its management depends on the characteristics of the disease and the patient and the resources available. There are benefits and harms of open and laparoscopic Hartmann’s procedure, laparoscopic peritoneal lavage, sigmoidectomy, and primary anastomosis. There are many gaps to be eliminated in the future, such as real risks, benefits, and cost-effectiveness in the application of each one. The decision to be made for each case of complicated diverticulitis often depends on the interaction and competence of the multidisciplinary team in charge.

Acetaminophen (APAP)-induced liver injury and acute liver failure is a significant clinical problem worldwide; in addition, APAP overdoses in animals or in cell culture are used as popular models to study drug-induced liver injury mechanisms and test therapeutic interventions. Early assumptions that APAP toxicity is caused by a single mechanism resulting in a defined mode of cell death in hepatocytes had to be questioned when over the years many different mechanisms and modes of cell death were reported. Although many of the contradictory results and conclusions reported over the years can be attributed to lack of understanding of established mechanisms, methodological problems, and misinterpretation of data, it is increasingly recognized that some of the reported differences in signaling mechanisms and even a switch in the mode of cell death can be caused by variations in the experimental conditions. In this review, examples will be discussed how experimental conditions (dose, solvent, etc.), the experimental system (species, strain, and substrain in vivo, cell type, and in vitro conditions), and also adaptive responses and off-target effects of genetic manipulations and chemical interventions, can impact the mechanisms of cell death. Given that the conditions will determine the results, it is therefore of critical importance to keep in mind the translational aspect of the experiments, i.e., the conditions relevant to the human pathophysiology. Only the full appreciation of these issues will lead to reproducible and clinically relevant results that advance our understanding of all facets of the human pathophysiology and identify clinically relevant therapeutic targets.

The epidemic of metabolic dysfunction-associated steatotic liver disease (MASLD) is increasingly growing worldwide. Thus, there is an urgent need for novel, non-invasive, and reliable biomarkers to replace liver biopsy for the diagnosis and prognosis of MASLD. Circulating peripheral blood mononuclear cells (PBMCs) are highly responsive to various stimuli and physiological changes. Beyond their immunomodulatory role, PBMC may act as metabolic sensors in several cardiometabolic disorders, including MASLD, with their metabolic programs shifting accordingly. Recent evidence suggests a link between impaired mitochondrial bioenergetics in PBMC and MASLD. Additionally, impaired mitochondrial respiration is intricately linked to the intracellular depletion of the oxidized form of nicotinamide adenine dinucleotide (NAD⁺) in various cell types. Accumulating preclinical and clinical data show that NAD⁺-increasing strategies may protect against MASLD by restoring intracellular NAD⁺ pools and improving mitochondrial performance. This review will focus on [i] the relevance of mitochondrial dysfunction, including impaired bioenergetics, in PBMC as a marker for the diagnosis and prognosis of MASLD, and [ii] the potential benefits of NAD⁺ precursors in MAFLD and their relationship with improved mitochondrial respiration in blood immune cells.

Hepatitis B virus (HBV) infection is a major risk factor of cirrhosis and hepatocellular carcinoma (HCC) worldwide. Pathogenesis of HBV-induced cirrhosis and HCC involves viral factors and virus-triggered local inflammatory and immune responses, the latter leading to progressive fibrosis, cirrhosis and carcinogenesis. Antiviral therapeutics suppress HBV replication and reduce the risks of cirrhosis and HCC. We discuss the current knowledge on the pathogenesis of HBV-induced cirrhosis and HCC, focusing on mechanisms of current and emerging antiviral therapeutics.

Microsatellite unstable (MSI) colorectal cancer (CRC) tumors have a high mutational load (particularly frame-shift mutations) that creates numerous neoantigens that are presented to major histocompatibility complex molecules and recognized by T cells. Consequently, MSI tumors have a higher presence of tumor-infiltrating lymphocytes than mismatch repair-proficient tumors. Colorectal cancer patients with MSI constitute a rare group of immune checkpoint inhibitor (ICI)-responsive patients. Nonetheless, complete radiological responders comprise between 3% and 16% of MSI advanced CRC patients, which compares poorly with the 45% to 87% rate of pathological complete response in early MSI CRC patients treated with ICIs. In this review, we address the efficacy of current ICIs and the biological differences between early and advanced MSI CRC to potentially increase the efficacy of ICIs in both settings.

Liver inflammation, injury, and hepatic cell death are caused by external agents (viruses, bacteria, drugs, alcohol, etc.) along with the genetic susceptibility of an individual. Persistent activation of the fibrogenic response in cells leads to liver fibrosis which in turn progresses to cirrhosis and cancer. The dysregulation of the immune system generates reactive oxygen species which in turn induce necrosis of hepatocytes. This process activates hepatic stellate cells and myofibroblasts to produce a huge quantity of collagens, alpha-smooth muscle actin, and extracellular matrix deposition in liver parenchyma. Due to the multifactorial nature of this disease, conventional therapies increasingly attempted combinatorial therapy or polytherapy to target multiple mechanistic sites in order to prevent entry into further complicated irreversible stages. Despite advancements in conventional therapy, several cases aggravate fibrosis (grade 3 to 4) and cirrhosis. The inconsistency in treatment outcomes and limited organ donors for liver transplantation have led to an ever-increasing and challenging demand for alternative therapies. In this review, we analyze the mechanism and causative factors of liver diseases, conventional mode, and alternative therapeutic options. The central to liver diseases are immune dysregulation, hence bioactive agents with immunomodulatory properties should be searched and exploited to meet therapeutic needs. Mesenchymal stem cells (MSCs) with their specialized anti-inflammatory and immunomodulatory properties could be utilized as an effective alternative therapeutic candidate in treating inflammatory liver diseases. MSC-derived exosome further provides an additional immunomodulatory option that could work in tandem with MSC in a synergistic form. In this series, we have reviewed preconditioned and genetically edited MSCs to augment homing, proliferation, and differentiation. Importantly, all the clinical challenges should be noted and addressed before stem cell cytotherapy should be considered safe and effective for patients with liver diseases. Published literature indicated that MSC therapy has the potential to substitute conventional options in the treatment of high-grade fibrosis and cirrhosis.

Mitochondria are essential organelles responsible for intracellular energy production and play crucial roles in cellular metabolism, inflammation, and apoptosis. Reactive oxygen species (ROS) are primarily produced in the mitochondria and endoplasmic reticulum of hepatocytes due to the activity of cytochrome P450 enzymes. Under ideal conditions, cells have specific molecular mechanisms that manage oxidative stress levels, thus ensuring a balance between oxidants and antioxidants. The interplay between ROS-induced mitochondrial dysfunction and the activation of the NLRP3 (nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3) inflammasome in the context of liver diseases has been extensively studied. However, the exact mechanisms by which mitochondria promote the activation of the NLRP3 inflammasome and contribute to the onset of liver disease remain unclear. This review aims to elucidate the recently discovered mitochondrial regulation of the NLRP3 inflammasome in liver disorders, including alcohol-related liver disease (ALD), metabolic-associated steatotic liver disease (MASLD), and hepatocellular carcinoma (HCC). Finally, it summarizes various natural and pharmaceutical agents that can mitigate liver damage by modulating the activation of the NLRP3 inflammasome through mitochondrial pathways. This work serves as an important resource for identifying new therapeutic approaches and provides further support for advancing the understanding of liver diseases.

Steatotic liver disease (SLD) has been known for a long time, but our understanding of this disease has remained poor until the past decade. Despite extensive research, our ability to comprehend the etiopathogenesis and natural course of SLD is far from the desired level of comprehension. This is required to develop a universally effective novel therapeutic agent. This review aims to concisely elaborate the conceptual approach and advancement in the understanding of global disease burden and etiopathogenic process, identifying the gaps and the pathophysiologic mechanism behind developing novel therapeutic agents. We searched two major databases, PubMed and Google Scholar, to identify publications related to the abovementioned topics. All publications, including original papers, reviews, and commentaries, were reviewed. Findings: Metabolic dysfunction-associated steatotic liver disease (MASLD) is not limited to obese individuals, rather, it may develop in any individual independent of weight. Visceral adiposity is strongly associated with MASLD and subsequent risks of cirrhosis, hepatocellular carcinoma, and cardiovascular disease. MASLD is associated with diabetes mellitus independent of underlying pathogenic mechanisms, and there is a bidirectional connection between MASLD and diabetes mellitus, making the situation quite challenging. Not all patients with MASLD exhibit atherogenic dyslipidemia and thus do not have a higher risk of cardiovascular disease. The overlap of these metabolic risk factors is not straightforward. There is a differential contribution of these risk factors based on age, gender, race, ethnicity, alcohol consumption, and microbiota composition. Poor dietary habits and lifestyle directly affect the microbiota, modulators, and mediators, thereby affecting the final biochemical processes leading to steatosis, steatohepatitis, fibrosis, and oncogenesis. In conclusion, MASLD is a complex and pathogenically heterogeneous disease with significant interpatient variation in the natural course and outcome. Understanding the precise mechanism of variability is the key gap and a limiting factor in the development of a novel therapeutic agent.

Hepatitis B virus (HBV) infection affects 262 million people worldwide, leading to over 820,000 deaths annually. The reason HBV has been a persistent issue for decades is that it is a non-cytopathic, liver-specific virus with the ability for persistent infection, which cannot be completely eliminated by drugs, eventually progressing to cirrhosis and hepatocellular carcinoma (HCC). Although HBV seems to induce little innate immune activation, adaptive immune responses can mediate viral clearance and liver disease. Here, we review the epidemiology, natural history, lifecycle, and modes of transmission of HBV. We also pay particular attention to the adaptive and innate immune responses to HBV and the research progress on therapeutic vaccines, which may provide new insights for targeted HBV treatment.

Lipids are intricate biomolecules responsible for the building up of biological membranes. Besides this structural function, they also display crucial roles in signaling, acting as second messengers that activate specific pathways. Mitochondria are fundamental for cells as they participate in several pivotal functions, such as ATP synthesis, cell survival, metabolic pathways, and calcium homeostasis. Thus, the lipid composition of mitochondrial membranes can affect specific proteins and impact vital functions of mitochondria, such as oxidative phosphorylation and dynamics. The liver possesses a critical function in lipid homeostasis, involving the generation, oxidation, and trafficking of free fatty acids (FFA), triglycerides (TG), cholesterol, and bile acids (BAs). Mitochondria play a key role in lipid storage regulation in hepatocytes, which can control liver function. Their diverse tasks are affected by the lipid composition of mitochondrial membranes, characterized by low cholesterol content and enrichment of specific lipids such as cardiolipin. As mitochondria determine the bioenergetic status of cells and are key regulators of cell viability, alterations of mitochondrial lipid composition can contribute to the induction and progression of chronic diseases, including alcohol-related liver disease (ARLD) and metabolic dysfunction-associated steatotic liver disease (MASLD), two of the most common forms of liver diseases characterized by steatosis, necroinflammation, and fibrosis, which can progress to hepatocellular carcinoma (HCC). Thus, the disruption of lipid metabolism and membrane composition of mitochondria are characteristic features of cancer cells, and altered mitochondrial lipid composition may be a critical player in the progression of chronic liver diseases toward HCC. This review will address the mechanisms whereby alterations of mitochondrial lipid composition lead to the onset and progression of chronic liver diseases. Thus, a better characterization of the alterations of lipid composition in mitochondria may be a crucial step to design strategies and novel therapeutic opportunities for the treatment of MASLD and ARLD.

The formation of metabolic changes is based on many factors. In particular, the infectious theory of the development of metabolic “breakdowns” has not lost its relevance. In this regard, many scientists are investigating the role of various microorganisms in the pathogenesis of metabolic syndrome. The review provides the results of current research on the role of Helicobacter pylori (as one of the most well-known and widespread bacterial pathogens) in the pathogenesis of metabolic syndrome. However, the results of scientific work are sometimes contradictory, which dictates the need for novel further research to clarify the characteristics of the influence Helicobacter pylori on the formation of various components of the metabolic syndrome.

Metabolic-associated steatotic liver disease (MASLD) and its pathological version, metabolic dysfunction-associated steatohepatitis (MASH), are becoming the main leading causes of chronic liver disease almost worldwide and are the fastest growing aetiology of hepatocellular carcinoma (HCC), especially in the Western countries. The combination of high incidence and morbidity with limited treatment options for both MASH and HCC highlights an urgent need for the discovery of novel therapeutic candidates to inform drug development. The importance of lysosomes and cathepsins, their most abundant hydrolases, has been overlooked for decades. They were considered organelles only involved in the recycling of macromolecules, with cathepsins simply being their effectors. Contrary to this traditional view, recent findings have shed new light on the lysosome and its enzymes as drivers of essential cellular processes, such as apoptosis and autophagy. Bringing lysosomal activity and the regulation of cathepsins into the spotlight of MASH and HCC research can open new avenues for the development of novel drugs based on targeting cathepsin-driven lysosomal activity and its associated pathological processes. This review comprehensively summarises the current knowledge on the role and contribution of lysosomal cathepsins to MASLD/MASH and HCC progression.

Ascites is a frequent complication in patients with cirrhosis, associated with a bad prognosis. Ascites is associated with severe complications, such as spontaneous bacterial peritonitis and kidney dysfunction, which must be diagnosed and managed rapidly. First-line management is based on diuretics use. Beta-blockers role remains debated but an early administration could probably decrease complications associated with portal hypertension. Albumin infusion is validated in large volume paracenteses, spontaneous bacterial peritonitis, or kidney dysfunction, but is debated in other situations. Technical progresses allow the worldwide use of TIPS (transjugular intrahepatic portosystemic shunt), but patient selection must be rigorous because of potential severe complications. An alternative treatment, automated low-flow ascites pump, can be offered in patients without TIPS possibility: It is a recent technique, whose patients’ selection and installation conditions were improved, with interesting results. Liver transplantation remains the gold standard, but the lack of grafts, and specific side effects, lead to prefer other methods. In case of acute kidney injury due to hepatorenal syndrome, terlipressin remains the standard of care; continuous infusion is associated with fewer side effects.

One of the primary complications of cirrhosis and portal hypertension is the occurrence of hepatocellular carcinoma (HCC), which is among the most common malignancies worldwide. There is limited availability of predictive non-invasive markers for primary HCC development in compensated advanced chronic liver disease (cACLD) patients. The reference standard method of assessing prognosis for cACLD patients, beyond liver fibrosis assessed by histology, is the measurement of the hepatic venous pressure gradient (HVPG). HVPG ≥ 10 mmHg is associated with an increased risk of HCC in these patients. However, these methods are expensive and invasive and are available only at referral centers. In the last decade, several studies have focused on the evaluation of several, simple, non-invasive tests (NITs) as predictors of HCC development. Among these methods, attention has particularly been paid to the elastographic techniques for the assessment of liver and spleen stiffness. We have reviewed the current literature about vibration-controlled transient elastography (VCTE), magnetic resonance elastography (MRE), and other ultrasound-based elastographic techniques (e.g., SWE) in predicting primary HCC occurrence and recurrence. Despite promising results, the overall heterogeneity resulting from the variability in the populations analyzed, the differences in the elastographic techniques used, the design and methodological quality of the available studies, prevented us from drawing definite conclusions on the liver and spleen stiffness role for predicting HCC occurrence and recurrence in chronic liver disease patients.

Chronic hepatitis B (CHB) disease caused by persistent infection with hepatitis B virus (HBV) is a global health problem affecting almost 300 million people worldwide, resulting in up to 1 million deaths each year. The factors contributing to HBV mediated liver disease are yet to be fully resolved, however, multiple studies have suggested that HBV splice variants may be a contributing factor. Recent studies have indicated that novel fusion proteins encoded by splice variants, or the splice-derived RNA itself, may impact replication of wild-type HBV, although the direct mechanisms for these interactions are largely unknown. This review explores the latest knowledge regarding the contribution of splice variants to liver disease and their impact on HBV replication.

Patients with advanced chronic liver disease can develop specific pulmonary complications related or unrelated to pre-existing lung disease. The three major pulmonary complications in this patient population include hepatopulmonary syndrome (HPS), portopulmonary hypertension (PoPH), and hepatic hydrothorax (HH). These entities are most often revealed by increasing dyspnea together with signs of portal hypertension. The prevalence of these complications remains underestimated due to the lack of routine screening of the cirrhotic population. The pathophysiology of HH is better understood than that of HPS and PoPH. The clinical features, diagnosis, and therapeutic options of these pulmonary complications are extensively discussed in this chapter. Liver transplantation may offer a curative therapy in highly-selected cases and MELD exception points allow priority access to liver transplantation, thus avoiding potential deterioration while awaiting transplant and providing a better post liver transplant survival. The complexity of managing these pulmonary complications requires a multidisciplinary team approach, especially when liver transplantation is indicated.

Acute decompensation is defined as the development of ascites, bleeding due to portal hypertension, jaundice, or hepatic encephalopathy in the presence of known or unknown chronic liver disease. Acute-on-chronic liver disease is defined as a clinical entity reflecting acute worsening in liver function along with extrahepatic organ failure with significantly higher 28-day mortality. In the common pathogenesis, severe systemic inflammation and portal hypertension and varying degrees of reaction to these conditions play a major role. Triggering factors act as accelerators in the development of acute decompensation and acute-on-chronic liver failure. The extrahepatic organ failure in acute-on-chronic liver failure is mainly due to tissue hypoxia due to decreased perfusion and cellular edema. The number of organ failure in acute-on-chronic liver failure is considered to be the most important prognostic indicator. Liver transplantation remains the most appropriate treatment option for selected patients, even though supportive therapies based on the severity of the disease and the clinical findings that have developed are at the forefront.

With the rising prevalence of chronic liver disease worldwide, the incidence and prevalence of acute-on-chronic liver failure (ACLF) are increasing and attribute to higher morbidity, mortality, and healthcare costs. Many of such patients die without being considered for the lifesaving treatment option of liver transplantation. The underutilization of liver transplantation as a therapeutic option in the setting of ACLF, is due to multiple reasons; with the heterogeneity of ACLF and the lack of universal definition being the key players. Liver transplantation listing and allocation are based on MELD score. As of now, we do not know where MELD score stands in regard to defining ACLF and the prognostication of such patients. This insight is very important for the efficient identification of potential liver transplantation candidates in the setting of ACLF. This review paper investigates the role of liver transplantation in the setting of ACLF. In light of recent evidence, MELD score is not the perfect model in the setting of ACLF either. The safety of liver transplantation, either deceased donor or living donor, among ACLF patients has been debated. The short-term mortality rate of ACLF patients has created a need for a standard liver transplant selection criterion for these patients. Based on published literature, we find that three commonly used ACLF definitions may be used in combination to define the sensitivity, specificity, and futility of ACLF and we propose an algorithm to best identify patients for urgent liver transplantation in the setting of ACLF. Moreover, we discuss the data on the safety of liver transplantation in the setting of ACLF. Future validation of this multifaceted approach could bridge the gap between ACLF patients and appropriately guided medical intervention.

Transabdominal ultrasound is a valuable diagnostic approach for evaluating the gastrointestinal tract and related disorders. This dynamic examination provides real-time visualization of the digestive tube and surrounding structures, assessment of peristaltic movements, estimation of compressibility of intestinal loops, and recognition of painful spots requiring specific attention. Since ultrasound imaging is non-invasive, painless, reproducible, inexpensive and requires no special preparation, it is used as a major diagnostic tool in emergency settings and in outpatient follow-up of several disorders. Costs, encompassing both accessibility and actual procedural expenses, are lower than those associated with other diagnostic techniques. However, the incorporation of gastro-intestinal ultrasound (GIUS) in clinical practice has not been widely used on a global scale. The purpose of this paper is to provide an overview of the execution techniques as well as the main areas of application for GIUS. Through illustrative iconographic representation, emphasis was placed on its potential within the diagnostic and therapeutic pathway of various acute and chronic gastrointestinal disorders.

Hepatitis C viral infections present a significant global health challenge, carrying substantial economic implications. These infections manifest in various clinical forms, including acute and chronic hepatitis, liver cirrhosis, hepatic failure, and hepatocellular carcinoma (HCC). Liver cirrhosis and HCC emerge as the primary contributors to mortality in hepatitis virus-induced liver diseases. To alleviate the public health impact of this disease, it is imperative to enhance the diagnosis and treatment rates among hepatitis C virus-infected individuals. The advent of direct-acting antivirals (DAAs), especially pan-genotypic regimens such as a combination of sofosbuvir and velpatasvir, has shown remarkable progress in achieving hepatitis C cure. However, potential obstacles, such as drug adverse effects and resistance-associated substitutions (RASs), warrant attention. Managing chronic hepatitis C (CHC) requires tailored treatment plans, vigilant monitoring, and judicious re-treatment strategies.

Hepatocellular carcinoma (HCC) is the most common type of liver cancer and its death rate is rising faster than that of any other cancer, while we still lack effective treatments. The increasing incidence of liver cancer in western countries is closely associated with the growing prevalence of metabolic dysfunction-associated steatohepatitis (MASH) linked to metabolic diseases. While the contribution of lipids in the progression of MASH pathogenesis and its progression to HCC is well recognized, the specific contribution of cholesterol is subject to controversy. The liver plays a central role in cholesterol metabolism, where the majority of its biosynthesis, storage, excretion, recycling, and conversion into bile acids occur. Moreover, cholesterol is implicated in numerous hepatocyte cellular processes, encompassing endoplasmic reticulum function, formation of lipid microdomains in the plasma membrane, metabolism of lipoproteins, and mitochondrial function and performance. Therefore, it is not surprising that cholesterol plays key roles in initiation, promotion, and survival of HCC cells and there are several lines of evidence pointing to that cancer cells are subverting cholesterol metabolism to foster their proliferation and survival through various mechanisms. This narrative review provides a concise overview of the physiological and pathological roles of cholesterol in the transition from healthy hepatocytes to HCC, in the context of MASH. Gaining further understanding of how hepatic cancer cells disrupt cholesterol homeostasis and how these perturbations impact cancer progression will facilitate the identification of novel and more effective cancer treatment strategies in this complex and devastating disease.

The most common type of liver cancer is hepatocellular carcinoma (HCC) causes a lower survival rate even after systemic treatment. Previous studies have shown evidence that various molecular and epigenetic mechanisms are involved in the transition of HCC from normal liver cells. Epigenetics plays an important role in maintaining genomic stability in normal liver cells. Apart from the mutation of genes, epigenetic factors are involved in HCC progression. miRNA tends to be a major epigenetic factor involved in regulating major cell cycle pathways. miRNA regulates the HCC progression by inhibiting the major apoptotic pathways and favors angiogenesis and tumor microenvironment. Apart from regulating major pathways, miRNA appears to regulate tight junction integrity. Tight junction proteins appear to be strong barrier proteins involved in cell adhesion and integrity. Disturbance in cell adhesion and integrity leads to the major dysregulation of cell cycle resulting in cancer progression. Moreover, dysregulation of tight junction integrity was observed in the pathogenesis of HCC. The regulation of tight junction proteins via miRNA were studied in various diseases. Here, we discussed the regulation of tight junction proteins via miRNA in HCC progression. This review may focus on the significance of miRNA in cellular function and its role in regulating tight junction proteins that impact in HCC progression which opens a new approach to develop a new diagnostic marker for an early detection of HCC and novel therapeutic approach against HCC.

Hepatitis B surface antigen (HBsAg) seroclearance is considered the functional cure and the optimal treatment endpoint for chronic hepatitis B (CHB). Patients with CHB who cleared HBsAg generally have a favorable clinical course with minimal risk of developing hepatocellular carcinoma (HCC) or cirrhotic complications. Nevertheless, a minority of patients still develop HCC despite HBsAg seroclearance. While patients with liver cirrhosis are still recommended for HCC surveillance, whether other non-cirrhotic patients who achieved HBsAg seroclearance should remain on HCC surveillance remains unclear. This review provides an overview of the incidence of HBsAg seroclearance, the factors associated with the occurrence of HBsAg seroclearance, the durability of HBsAg seroclearance, the risk of developing HCC after HBsAg seroclearance, the risk factors associated with HCC development after HBsAg seroclearance, the role of HCC risk scores, and the implications on HCC surveillance. Existing HCC risk scores have a reasonably good performance in patients after HBsAg seroclearance. In the era of artificial intelligence, future HCC risk prediction models based on artificial intelligence and longitudinal clinical data may further improve the prediction accuracy to establish a foundation of a risk score-based HCC surveillance strategy. As different novel hepatitis B virus (HBV) antiviral agents aiming at HBsAg seroclearance are under active development, new knowledge is anticipated on the natural history and HCC risk prediction of patients treated with new HBV drugs.

It is generally accepted that eradication of Helicobacter pylori (H. pylori) infection may reduce the risk of the development of gastric cancer. Recommendations for global generalized tests and treat all individuals detected positive for H. pylori infection are currently proposed. However, the bacterium is commensal and harmless for the vast majority of the infected population. Moreover, eradication may have detrimental consequences in several groups of patients. In the present review, the current epidemiological data and recommendations for eradication in connection with the possible beneficial effects of the colonization with H. pylori in diseases such as asthma and allergies or chronic gastro-intestinal disorders such as inflammatory bowel disease and Barrett’ esophagus are presented the problems with increasing antibiotic resistance were also examined. Specific groups of patients where eradication of H. pylori may be necessary and endoscopic surveillance is advised were identified. Finally, based on the paradox of high H. pylori prevalence and low gastric risk as reported for areas of Africa, Asia, South America, and Greece, alternatives that may replace the widespread eradication of H. pylori with equal if not better results and more prudent use of the available financial resources are proposed. Mediterranean diets and alcohol and smoking reduction are among the well documented alternatives.

Autoimmune hepatitis (AIH) is a chronic liver disease of unknown aetiology that can lead to end stage liver disease if left without treatment. Corticosteroids with or without azathioprine (AZA) are considered the recommended standard first-line treatment option for the induction and maintenance of remission. The aim of treatment is to achieve complete biochemical response (CBR), defined by normal transaminases and immunoglobulin G (IgG) within 6–12 months after treatment initiation. However, response rates to standard treatment vary widely as approximately 10–25% of cases develop intolerance, insufficient response, or rarely non-response to AZA. Mycophenolate mofetil (MMF) is an effective and safe alternative first-line treatment in AIH, based on its high rates of CBR among treatment-naive patients, but can also be considered as second-line drug in patients with poor response or intolerance to AZA. However, even after the administration of second line treatment there is a small proportion of patients with refractory disease that bear the highest probability of developing decompensated cirrhosis and hepatocellular carcinoma. For this difficult to treat subgroup of patients third-line treatments are warranted. Therefore, the aim of this review is to summarize the current evidence on second- and third-line therapies for AIH, as well as, to set the background for future perspectives on safer and more efficient treatment strategies.

This is a case of remarkable alpha-fetoprotein in a female patient with known cryptogenic liver cirrhosis. Both ultrasound and triphasic computed tomography (CT) abdomen cannot diagnose or exclude hepatocellular carcinoma (HCC). It turns out to be a case of portal vein thrombosis and hepatic pseudo-infarction. It is better to postpone the therapeutic intervention, whether surgical or chemotherapeutic, in cases not confirmed to be HCC for at least 3 months to avoid misdiagnosis of hepatic pseudo-infarction.

The liver, characterized by a unique metabolic and immunosuppressive environment, is also the organ to which invasive malignant cells of many different cancer types most frequently metastasize. The reasons for this organ-specific metastatic process have been investigated for decades. This review first provides an overview of recent breakthroughs in this field, introducing intercellular communication between circulating tumor cells and the heterogeneous cell populations of the liver, and modifications to the extracellular matrix (ECM). Subsequently, to improve the understanding of the molecular mechanisms involved in the metastasis of colorectal cancer to the liver, the second leading cause of cancer-related mortality, the recent literature on this question was analyzed. Among the various parameters involved, the mechanisms behind the activation of hepatic stellate cells, proteins inducing ECM remodeling, specific genomic features of liver metastases, metabolic rewiring, and characteristics of stromal-enriched microenvironments were discussed. To provide more insights into the molecular determinants of liver metastatic colonization, important findings reported on a set of mitochondrial proteins were addressed, the relative abundance of which changed in the liver during the progression stage of an aggressive experimental model of peritoneal malignant mesothelioma in immunocompetent rats. Based on previous studies cross-comparing the liver proteomes from curcumin-treated tumor-bearing rats/untreated tumor-bearing rats/normal rats, data from the literature were reviewed for 25 mitochondrial proteins of interest. Their role in lipid metabolism, heme biosynthesis, the electron transport chain, small molecule transport, mitochondrial dynamics, the tricarboxylic acid cycle, and protection against oxidative stress were analyzed in the context of both cancer and non-malignant liver diseases.

Mitochondria are present in all mammalian cells except matured red blood cells. Mitochondria consist of several metabolic pathways for glucose, fatty acids, amino acids, and bioenergetic pathways for ATP synthesis, membrane potential, and reactive oxygen production. In the liver, hepatic mitochondria play a key role in hepatic steatosis because mitochondrial metabolism produces acetyl-CoA which is the building block for synthesis of lipids and cholesterol. Mitochondria inner membrane is impermeable of metabolites, reducing equivalents, and small molecules such as phosphate, and sulfate. Thus, mitochondrial shuttles and carriers function as the routes of influx and efflux of these metabolites and molecules across the inner membrane. The signal regulation of these shuttles and mitochondrial enzymes could play a key role in coordinating the mitochondrial metabolism to adapt the cytosolic part of metabolic pathways in liver metabolic stress. Intriguingly, the interaction of mitochondria protein SH3 domain-binding protein 5 (SAB/SH3BP5) and c-Jun N-terminal kinase (JNK) was found as a pivotal role in sustained activation of JNK and phosphorylated-JNK (P-JNK) mediated activation of lipogenic pathway in nutritional excess. Knockout or knockdown of SAB prevented or reversed the hepatic steatosis, inflammation, and fibrosis, and improved metabolic intolerance and energy expenditure. Moreover, blocking the SAB peptide prevents palmitic acid-induced P-JNK interaction with SAB and inhibition of mitochondrial bioenergetics, implying the P-JNK effect on mitochondrial metabolism. This review focuses on the flow of mitochondrial metabolites in metabolic stress conditions and the contribution of mitochondria and mitochondrial stress signals in hepatic steatosis.

Chronic liver diseases (CLDs), which are typically characterized by fibrogenic progression towards liver cirrhosis and related complications eventually leading to organ failure and can also lead to the development of primary liver cancers, represent a major burden for human health on a worldwide basis. Although the present knowledge on the pathogenesis of CLDs progression and primary liver cancers development has remarkably increased in the last decades, critical molecular mediators remain incompletely understood, and approved antifibrotic therapies to efficiently counteract CLDs progression and liver cancer are lacking. In the present review, this study will specifically analyse the putative contribution of SERPINB3, a member of the superfamily of serine-protease inhibitors (SERPINs), which has been shown to exert significant pro-inflammatory and pro-fibrogenic roles in progressive CLDs as well as to be involved in the development of primary liver cancers, including hepatocellular carcinoma (HCC), cholangiocarcinoma, and hepatoblastoma.

Hunting for tumoral material in body fluids, traditionally in blood, the so-called liquid biopsy is set to revolutionize the diagnosis and management of oncological patients. However, other biofluids can also be considered as alternative sources of biomarkers to provide clinically valuable information for multiple diseases. This is the case of bile, a fluid produced in the liver, stored in the gallbladder, and excreted to the duodenum, which complex composition is known to change in different pathological conditions. Remarkably, different works have demonstrated that the identification of mutations in bile cell-free DNA (cfDNA) can outperform blood analysis for the early diagnosis of biliopancreatic tumors causing biliary strictures. Here, the literature in which bile has been tested as a liquid biopsy matrix where lipids, metabolites, proteins, and cfDNA among other analytes were measured is reviewed. Moreover, the clinical situations and procedures where bile can be available, discussing the possible applications and limitations of bile analysis are summarized. The scientific relevance and clinical potential of bile harvesting, biobanking, and analysis are put forward. All this evidence supports the value of bile as a liquid biopsy matrix for the management of patients beyond cancer, and perhaps also beyond “blood, sweat, and tears”.

Drug-induced liver injury (DILI) poses a complex and heterogeneous clinical challenge, which often resembles non-drug related acute or chronic liver diseases, such as metabolic dysfunction-associated steatotic liver disease (MASLD). Furthermore, certain drugs can induce hepatic steatosis, which is considered a rare variant of hepatotoxicity. Additionally, the detection and diagnosis of DILI in patients with non-alcoholic liver disease present additional challenges that require attention. The importance of achieving an accurate diagnosis is highlighted by the different therapeutic approaches needed for each of these diseases. Nonetheless, as definitive diagnostic tests and distinct biomarkers often remain elusive, the differential diagnosis must rely on a combination of clinical, biochemical, histological, and immunophenotypic profiling. The diagnosis of hepatotoxicity is predicated upon the temporal nexus between the administration of a potentially hepatotoxic drug and the onset of hepatic injury, concomitantly excluding alternative hepatic pathologies. More frequently, this condition presents an acute course, with a more pronounced elevation of cytolytic and cholestatic parameters as compared to fatty liver disease. Advances in elucidating the underlying mechanisms hold promise for bolstering the diagnosis and management of these conditions. This article aims to thoroughly examine and emphasize the currently available scientific evidence to provide valuable insights into the diagnostic strategies for DILI, metabolic-associated liver disease, and drug-induced steatosis (DIS).

Metabolic dysfunction-associated steatotic liver disease (MASLD) is one of the most common chronic liver diseases. Over time, there has been a significant increase in the prevalence of MASLD. It has become one of the leading causes of hepatocellular carcinoma (HCC) in the United States, France, and the United Kingdom. Globally, the incidence of HCC related to MASLD may further increase with the growing prevalence of obesity. Non-alcoholic steatohepatitis (NASH) is an important stage of MASLD, which is more likely to cause cirrhosis and even HCC. And patients with NASH cirrhosis have a much higher incidence of hepatocellular cancer than patients with non-cirrhotic MASLD. As a result, it is critical to investigate the targets of MASLD therapy in HCC. This article reviews therapeutic targets of MASLD, such as farnesoid X receptor (FXR), peroxisome proliferator activated receptor (PPAR), fibroblast growth factor-21 (FGF-21), etc., and introduces the drugs related to these targets and their mechanisms of action in HCC. In addition, the developmental process and pathogenesis of MASLD, as well as risk factors for HCC development, are discussed. These are of great significance for the prevention and treatment of HCC.

Non-alcoholic fatty liver disease (NAFLD) is the leading chronic liver disease worldwide, with a progressive form of non-alcoholic steatohepatitis (NASH). It may progress to advanced liver diseases, including liver fibrosis, cirrhosis, and hepatocellular carcinoma. NAFLD/NASH is a comorbidity of many metabolic disorders such as obesity, insulin resistance, type 2 diabetes, cardiovascular disease, and chronic kidney disease. These metabolic diseases are often accompanied by systemic or extrahepatic inflammation, which plays an important role in the pathogenesis and treatment of NAFLD or NASH. Metabolites, such as short-chain fatty acids, impact the function, inflammation, and death of hepatocytes, the primary parenchymal cells in the liver tissue. Cholangiocytes, the epithelial cells that line the bile ducts, can differentiate into proliferative hepatocytes in chronic liver injury. In addition, hepatic non-parenchymal cells, including liver sinusoidal endothelial cells, hepatic stellate cells, and innate and adaptive immune cells, are involved in liver inflammation. Proteins such as fibroblast growth factors, acetyl-coenzyme A carboxylases, and nuclear factor erythroid 2-related factor 2 are involved in liver metabolism and inflammation, which are potential targets for NASH treatment. This review focuses on the effects of metabolic disease-induced extrahepatic inflammation, liver inflammation, and the cellular and molecular mechanisms of liver metabolism on the development and progression of NAFLD and NASH, as well as the associated treatments.

The pathogenesis of primary biliary cholangitis (PBC) is particularly complicated as both intrinsic and extrinsic factors are implicated. Several forms of cellular death, both programmable and non-programmable, operate leading biliary epithelial cells (BECs) to elimination. The precise role of critical pathways like autophagy, apoptosis, senescence, and their interplay has not been fully clarified. Therefore, in this review, data on these important mechanisms are presented and their implication in PBC is discussed. The interplay of the three mechanisms is examined and the factors that drive them are analyzed. Moreover, the upstream drivers of autophagy, apoptosis, and senescence are presented. They include the loss of the protective bicarbonate umbrella in BECs due to the reduction of activity of the anion exchanger 2 (AE2) with the resultant activation of the intracellular soluble adenylyl cyclase (sAC). The role of toxic bile acids is also presented. A sequence of events is proposed including involvement of the gut-liver axis and the possible role of ferroptosis. Finally, a brief account of the initial trigger of the disease is given.

Drug-induced liver injury (DILI) is an adverse reaction to drugs and other xenobiotics that can have serious consequences and jeopardise progress in pharmacological therapy. While DILI is predominantly hepatocellular, a non-negligible percentage of patients who present with cholestatic damage. Mixed damage is typically lumped together with cholestatic damage in the literature. Drug-induced cholestasis is often caused by the use of some non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics (i.e., amoxicillin-clavulanic acid), statins, and anabolic agents, among others. Drug-associated cholestasis tends to have a more chronic course and mostly affects older population. There is also a genetic predisposition to toxic cholestasis caused by some drugs (amoxicillin-clavulanic acid, statins, etc.). Recently, anatomical alterations of the biliary tract induced by drugs (especially immunotherapy drugs) have been described. Bile duct injury is one of the histopathological findings that have prognostic significance in DILI. A correct differential diagnosis with other causes of cholestasis is mandatory to reach an accurate diagnosis. Ursodexycholic acid, corticosteroids, and replacement therapies have been used as a therapeutic arsenal, although more evidence is needed to establish them as a routine therapeutic management in clinical practice. The breakthrough and validation of biomarkers of cholestasis and bile duct injury is an urgent need for drug development and post-marketing phase.

Nonalcoholic fatty liver disease (NAFLD) is an umbrella definition that describes the ectopic deposition of fat within the liver that occurs in the absence of inciting factors other than the metabolic syndrome and its individual features. NAFLD has a multi-factorial pathogenesis which determines heterogeneous clinical phenotypes and variable natural course spanning from liver-related (steatohepatitis, fibrosis, cirrhosis, hepatocellular carcinoma) to extrahepatic outcomes (cardio-metabolic and cancer). This narrative review article leverages the key aspects of disease natural history as the background information to discuss studies that may inform strategies to risk-stratify NAFLD patients. Evaluation of hepatic fibrosis with non-invasive tools, including blood-based biomarkers and imaging-based elastometry techniques, seemingly retains the core information useful to predict the heterogeneous outcomes listed above. Additionally, genetic testing and metabolomic profiles may also be utilized to this end. In conclusion, a comprehensive understanding of the variable hepatic, cardio-metabolic and cancer outcomes of NAFLD may enable physicians and researchers to risk-stratify and accurately identify the multilayered prognosis of NAFLD individuals while also defining homogeneous patient subsets to enroll in clinical trials.

Primary biliary cholangitis (PBC), previously known as primary biliary cirrhosis, is a rare chronic autoimmune cholestatic liver disease, affecting mostly females. With PBС develops chronic cholangiopathy, this is accompanied by the development of gradually progressive liver fibrosis, which leads to intrahepatic cholestasis. Defects in autoimmune tolerance are critical factors in the emergence of the disease. Biochemical signs in PBС appear already in the asymptomatic stage of the disease and they are associated with a disturbance of the secretion of bile acids. Understanding the pathophysiological mechanisms of these signs is essential to both the early diagnosis and treatment of PBC. Early diagnosis of the disease contributes to its more effective treatment. There are many scientifically based modern data on the pathophysiology of clinical and laboratory signs developing in PBС. The purpose of this review is to summarize the data available in the literature and those obtained by the authors on the mechanisms for the development of biochemical criteria for PBC and their diagnostic significance. The opportunity to present the pathophysiological mechanisms of the development of biochemical signs in patients with PBC is associated with the success in the development of modern research methods in biochemistry, molecular biology, and genetics.

A high consumption of ultra-processed food (UPF) is a hallmark of Western diets that has been related to increased risk of non-communicable diseases. As an underlying mechanism, UPF may promote non-alcoholic fatty liver disease (NAFLD) which is a key driver of metabolic impairment with extra-hepatic manifestations like type 2 diabetes, cardiovascular disease, chronic kidney disease, and osteoporosis among others. The present review provides an overview of UPF properties that may promote NAFLD and are thus potential targets for reformulation of UPF. Such approaches should address improvements in the quality of carbohydrates and fat, changes in food texture that lower eating rate as well as ingredients that prevent excess caloric intake or avoid dysbiosis and leaky gut syndrome. Promising strategies are enrichment with fiber, prebiotics, phytochemicals, and protein with a concurrent reduction in glycemic load, energy density, saturated fatty acids (FA; SFA), emulsifiers, fructose, and non-caloric sweeteners. Future studies are needed to examine the interactive and protective effects of such modifications in the composition of UPF on prevention and treatment of NAFLD.

Excessive alcohol intake is still among the leading causes of chronic liver diseases. Epidemiological studies suggest that per capita consumption of alcohol from various alcohol beverages e.g., beer, wine, or spirits, differs markedly between different areas of the world. Studies further suggest that different alcoholic beverages may impact the development of alcohol-related liver diseases (ALD) differentially. Specifically, results of several more recent epidemiological studies suggest that consumption of wine and herein especially of red wine may be less harmful in relation to the development of liver diseases than the intake of hard spirits. Results of studies evaluating the effects of beer on the development of ALD in humans are rather contradictory. Here, results of studies assessing the impact of wine, beer, and spirits on the development of ALD as well as possible underlying mechanisms are summarized and discussed.

The pathogenesis of drug-induced liver injury (DILI) is still in an early stage of research. However, investigators have shown that both oxidative stress and endoplasmic reticulum (ER) stress play a significant role in the pathological mechanism. However, there is little in-depth literature about these two mechanisms. In order to prevent and improve the clinical symptoms of DILI, it is particularly important to study its pathogenesis. In this review article, the role of ER and oxidative stress in DILI is thoroughly discussed.

The word “Kampo medicine” means the traditional Japanese herbal medicine. Even “natural herb” can cause drug-induced liver injury (DILI). In this review, the characteristics of Kampo medicine-induced liver injury (KMILI) are reported. The main causative herb involved in Kampo medicine is Scutellariae Radix. KMILI is based on certain hypersensitivity reactions. A small amount of Kampo medicine can cause liver injury, and KMILI can develop after a short latency period. The incidence of liver injury related to Scutellariae Radix is about 1%. KMILI is usually mild and not fatal. The latency period usually lasts 4 weeks to 24 weeks. Fatigue and loss of appetite are sometimes observed. Eosinophilia is not frequently observed. All three types of liver injuries are observed in KMILI: cholestatic, hepatocellular, and mixed types. In Japan, lymphocyte transformation test (LTT) has been generally used for the diagnosis of DILI; however, LTT is likely to yield false-positive result for Kampo medicines, and thus often leads to misdiagnosis in many cases. Recently, researchers reported that a specific human leukocyte antigen (HLA) genotype is possibly associated with KMILI. This hypothesis needs to be examined further. Although Kampo medicine is based on rich knowledge and experience that occurred over a period of thousands of years, much is still unknown about KMILI.

Zebrafish as a preclinical drug induced liver injury (DILI) model provides multiple advantages ranging from ease of breeding and maintenance, availability of different strains and transgenic fish amenable to study liver function, and highly conserved liver structure and function with the human liver. In this review, the authors have aimed to provide an account of the metabolic enzymes that take roles in drug detoxification in both human and zebrafish in a comparative manner and exemplify several recent models in studying liver functionality. Moreover, the authors emphasize the difficulties associated with studying idiosyncratic DILI in preclinical models and propose that zebrafish could be an important complement to mice in testing functions of genes that are associated with DILI with respect to different drugs in human genome-wide association studies (GWAS) Catalog. Finally, this review highlights the state-of-the-art in the development of novel transgenic reporter strains that can be used to study degree and molecular mechanisms of hepatotoxicity caused by drugs in zebrafish. All of these will help researchers to use effectively the available resources in the zebrafish DILI models, while advocating potential leads that can be taken to provide advancements in a better understanding and treatment of DILI.

The late event onset of a fraction of idiosyncratic drug-induced liver injury (DILI) cases and the link observed by genome-wide association studies (GWASs) of certain human leucocyte antigen (HLA) alleles with DILI due to specific drugs support the crucial role of the immune system (both innate and adaptive) in the pathogenesis of DILI. Recent advances in both flow and mass cytometry have allowed the profiling of all major immune cell types in a given sample. Therefore, determining the lymphocyte populations in samples from patients with DILI would facilitate the development of specific biomarkers for DILI diagnosis and prognosis. To date, a few studies have explored the immune landscape in DILI. In a recent study of leukocyte immunophenotyping using flow cytometry from the Spanish DILI Registry, an important role of adaptive immune response in DILI is suggested. DILI patients had significantly higher levels of T helper 1 (Th1) cells and activated helper and cytotoxic T cells than healthy controls. Furthermore, the increased expression of negative immune checkpoints and ligands in DILI patients could reflect a restoration of the immune homeostasis. Differences in the profile of cytokines in DILI patients from the Drug-Induced Liver Injury Network (DILIN) also suggest an involvement of both innate and adaptive immune systems in DILI development and prognosis. Moreover, several studies based on immunophenotyping of liver infiltrates showed a distinctive pattern of cellular infiltrates in patients with immune checkpoint inhibitors (ICIs)-DILI, with lower levels of plasma cells, CD20⁺ B cells and CD4⁺ T cells than in autoimmune hepatitis (AIH) patients. These pioneering studies highlight the importance of immunophenotyping for the mechanistic understanding of DILI. In this review, available data on immunophenotyping in DILI are gathered, and the potential clinical applications of cutting-edge, novel immunophenotyping techniques are discussed.

Hereditary cholestasis comprises a broad spectrum of clinical phenotypes of varying severity. Severe forms such as progressive familial intrahepatic cholestasis (PFIC) mostly affect children with disease onset within their first years. Nevertheless, late-onset PFIC forms are increasingly diagnosed. Most adults present with less severe forms of hereditary cholestasis, often suffering from pruritus, gallstone disease, jaundice, or elevated liver enzymes. To identify the underlying genetic background and to rule out potential differential diagnoses, a broad genetic analysis like whole exome sequencing (WES) is recommended. Knowledge of the affected gene may have an impact not only on patient surveillance due to risk for disease progression or tumor development but also on potential therapeutic strategies. This case of the adult patient illustrates the importance of broad genetic analysis, which brought up the potentially relevant rare multidrug resistance protein 3 (MDR3) missense variant p.(Asn489Tyr) underlying the patient’s clinical phenotype of low phospholipid-associated cholelithiasis (LPAC). Patients with MDR3 disease may have an increased risk for cholangiocarcinoma (CCA) development and therefore need an individualized surveillance strategy. Most MDR3-affected patients benefit from life-long therapy with ursodeoxycholic acid (UDCA), which is well tolerated. Bezafibrate treatment can reduce pruritus, one of the main symptoms affecting the quality of life. Whether the administration of ileal bile acid transporter (IBAT) inhibitors is beneficial in adult patients with MDR3 disease is so far unknown.

Evaluation of the hepatobiliary function is critical for the clinicians, not only for the diagnosis of a large variety of liver diseases but also in the follow-up and management of some patients, for instance, those with different degrees of cholestasis suffering from a drug-induced liver injury (DILI) or scheduled for liver resection. Currently, the determination of global liver function mainly relies on laboratory tests, clinical scores, and data from images obtained with ultrasonography, computed tomography (CT), or magnetic resonance. Nuclear medicine scanning, displaying either planar or three-dimensional spatial distribution of liver function, is enhanced when using hepatotropic tracers based on classical radioisotopes such as technetium-99m (^99mTc) and with higher resolution using metabolized probes such as those based on monosaccharide derivatives labeled with ¹⁸F. Other cholephilic compounds, and hence selectively secreted into bile, have been proposed to visualize the correct function of the liver parenchyma and the associated secretory machinery. This review aims to summarize the state-of-the-art regarding the techniques and chemical probes available to monitor liver and gallbladder function, in some cases based on imaging techniques reflecting the dynamic of labeled cholephilic compounds.

Lysosomal hydrolases were once considered effectors of the waste disposal system of the cell, the endo-lysosomal system. However, they are now recognized as highly selective enzymes, which can modulate the function of several substrates, contributing to essential homeostatic and pathological cellular processes. There are more than 50 different lysosomal hydrolases that display optimal activity in the pH present in the acidic cellular compartment but can also be found in other cellular locations. They can work alone or in cooperation with other proteases building signaling pathways or amplification cascades. In the context of liver fibrosis lysosomal hydrolases, especially cysteine cathepsins have been described to participate in several fundamental cellular events contributing to the development, progression, perpetuation, and resolution of liver fibrosis. This paper comprehensively reviews the current knowledge on the contribution of lysosomal hydrolases to liver fibrosis.

During liver injury and cholestasis, the mechanisms allowing the organ to protect itself with the aim of maintaining biliary homeostasis are not completely understood. Central to their biological roles, bile acids (BAs) and their receptors constitute a signaling network with multiple molecular and cellular impacts on both liver repair and protection from BA overload. BA signal through nuclear [mainly farnesoid X receptor (FXR)] and membrane [mainly G protein-coupled BA receptor 1 (GPBAR-1), aka Takeda G protein-coupled receptor 5 (TGR5)] receptors, in which activation elicits a wide array of biological responses. So far, most of the studies have been focused on FXR signaling as hepato-protective, TGR5 being less explored to this regard. While the liver faces massive and potentially harmful BA overload during cholestasis, it is crucial to understand that BAs induce also protective responses contributing not only to reduce the inflammatory burden, but also to spare liver cells and their repair capacities. Based on the available literature, the TGR5 BA receptor protects the liver in the cholestatic context and counteracts BA overload with the aim of restoring biliary homeostasis mainly through the control of inflammatory processes, biliary epithelial barrier permeability, and BA pool composition. Mouse experimental models of cholestasis reveal that the lack of TGR5 was associated with exacerbated inflammation and necrosis, leaky biliary epithelium, and excessive BA pool hydrophobicity, resulting in biliary cell and parenchymal insult, and compromising optimal restoration of biliary homeostasis and liver repair. There are thus widely opened translational perspectives with the aim of targeting TGR5-related signaling or biological responses to trigger protection of the cholestatic liver.

Metabolic zonation in the liver carries out the maintenance of organ and body homeostasis. Hypoxia is an inherent physiological feature of the liver and contributes to the zonal properties of the hepatic parenchyma. As a master regulator of hypoxia, the transcription factor hypoxia-inducing factor (HIF) is stabilized primarily by oxygen availability, and it is thought to contribute to steatohepatitis due to alcohol-related (ASH) and non-alcohol-related liver disease (NASH). Cholesterol has emerged as an important player in both diseases, and hypoxia increases hepatic cholesterol levels. Steroidogenic acute regulatory protein 1 (STARD1) is a mitochondrial outer membrane protein that transfers cholesterol to mitochondrial inner membrane for metabolic processing and acts as the rate-limiting step in the alternative pathway of bile acid synthesis in hepatocytes. STARD1 expression increases in ASH and NASH and determines the accumulation of cholesterol in mitochondria, which impacts the physico-chemical mitochondrial membranes properties and as a consequence impairs the activity of specific mitochondrial solute carriers, such as the 2-oxoglutarate carrier (2-OGC), limiting the exchange between cytosolic glutathione and mitochondrial 2-oxoglutarate (2-OG). Although HIF-1 is stabilized in hypoxia largely due to the requirement of prolylhydroxylases (PHDs) for oxygen to signal HIF degradation, PHDs are also dependent on 2-OG, and therefore it is conceivable that impairment of 2-OGC by STARD1-mediated cholesterol accumulation may contribute to HIF-1 stabilization due in part to decreased availability of cytosolic 2-OG. In this perspective, this review explores the interplay between HIF-1 stabilization and STARD1 induction and the potential contribution of this functional relationship to ASH and NASH.

Several metabolic pathways are involved in the biotransformation of C27 neutral cholesterol to C24 primary bile acids (BAs), mainly cholic acid (CA) and chenodeoxycholic acid (CDCA), which are then conjugated with glycine or taurine. This process can start with the modification of the steroid ring or the shortening of the side chain and involves enzymes present in different subcellular compartments. Inborn errors affecting the biogenesis of organelles, such as peroxisomes, or the expression or function of specific enzymes of these convergent routes result in: i) the lack of mature C24-BAs, with the subsequent impairment in digestion and absorption of dietary fat and liposoluble vitamins, such as vitamin K, which may account for a deficient hepatic synthesis of several coagulation factors; ii) the accumulation of intermediate metabolites, which may affect hepatocyte physiology, causing cholestasis as a commonly shared alteration besides other deleterious hepatic events; and iii) extrahepatic clinical manifestations due to accumulation of toxic metabolites in other territories, such as the nervous system, causing neurological disorders. In general, diseases whose primary alteration is a genetic defect in BA synthesis are diagnosed in children or young individuals with a very low incidence. The symptomatology can markedly vary among individuals, ranging from mild to severe conditions. Oral therapy, based on the enrichment of the BA pool with natural C24-BAs, such as CA, CDCA, glyco-CA, or ursodeoxycholic acid (UDCA), depending on the exact deficiency causing the disease, may be beneficial in preventing life-threatening situations. In contrast, in other cases, a liver transplant is the only option for these patients. This review describes the updated information on the genetic and molecular bases of these diseases and the current approaches to achieve a selective diagnosis and specific treatment.

Caspases are key factors in the regulation of the apoptotic and/or inflammatory responses, both crucial in the pathogenesis of diverse diseases. Caspase-2 is the most evolutionary conserved albeit functionally poorly defined member of the caspase family. The precise role of caspase-2 as an initiator or effector caspase is still unknown, but it has been involved in a wide variety of functions, from apoptosis to genomic stability, oxidative stress, metabolism, and cancer. However, many conflicting results render the exact function of this protease still unresolved. Although caspase-2 has several hundred substrates, the activation, processing, and activity on specific substrates remain poorly described. Recent evidence indicates that caspase-2 has a role in metabolic homeostasis and is required for lipotoxicity-induced apoptosis in hepatocytes, contributing to non-alcoholic steatohepatitis (NASH) progression towards hepatocellular carcinoma (HCC). Caspase-2 protein expression strongly localizes to injured/ballooned hepatocytes, correlating with NASH severity. Also, mice lacking caspase-2 showed protection from western diet-induced obesity, dyslipidemia, and insulin resistance. Although there are no effective therapies for NASH and HCC, the evaluation of a pan-caspase inhibitor has reached a phase I/II in clinical trials for advanced liver disease. Nevertheless, a better understanding of caspase functions with the identification of specific proteolytic substrates is essential for future therapeutic developments. Bearing in mind the pressing need to identify new targets for NASH-HCC and its metabolic-related comorbidities, and the favorable effect of caspase-2 genetic inhibition in animal models, pharmacological caspase-2 inhibition arises as a promising strategy that should be further investigated.

Normal hepatobiliary function depends on an adequate bile flow from the liver through the biliary tree to the gallbladder, where bile is stored and concentrated, and from the gallbladder to the duodenum when it is required for the digestive process. Interruption of this secretory function results in partial or complete cholestasis, which is accompanied by important repercussions due to the lack of bile acids in the intestine and their regurgitation from hepatocytes to blood together with potentially toxic compounds that are normally eliminated in bile. The presence of active and selective transporter proteins located at both poles of the plasma membrane of hepatocytes, cholangiocytes, and epithelial cells of the ileal mucosa, together with the ability of hepatocytes to synthesize bile acids from cholesterol, enables the so-called bile acid enterohepatic circulation, which is essential in liver and gastrointestinal tract physiology. The presence in the ducts of the biliary tree of agents reducing their luminal diameter by external compression or space-occupying obstacles, either in the duct wall or its lumen, can result in total or partial obstructive cholestasis. The clinical impact and management of cholestasis are different depending on the intrahepatic or extrahepatic location of the obstacle. Thus, surgical interventions can often be helpful in removing extrahepatic obstructions and restoring normal bile flow to the duodenum. In contrast, hepatocyte or cholangiocyte damage, either global, restricted to subcellular compartments, or more specifically affecting the elements of the canalicular secretory machinery, may result in hepatocellular cholestasis or cholangiopathies. In these cases, bile flow interruption is usually partial and, except for extremely severe cases when liver transplantation is required, these patients often treated with pharmacological agents, such as ursodeoxycholic acid (UDCA) and rifampicin. The present review gathers updated information on the etiopathogenesis and pathophysiological aspects of different types of cholestasis.

The surface of intestinal epithelial cells is covered by the brush border, which consists of densely packed cellular extrusions called microvilli. Until recently, microvilli have not been known to be interconnected. In 2014, a protein complex, called the intermicrovillar adhesion complex (IMAC) which is located at the tips of the microvilli and responsible for the regular spatial organization of the brush border, was identified. Deletion of IMAC components such as cadherin-related family member-2 (CDHR2) in mice resulted in microvillus disorganization and fanning, a structural aberration that is also found in the brush border of patients with inflammatory bowel disease. The etiology of inflammatory bowel disease has been primarily associated with dysfunctional mucosal immunity, but the discovery of the IMAC may encourage theories of an epithelial origin. Here, possible effects of the brush border on the gut barrier function and intestinal inflammation are discussed proposing that the IMAC protects against inflammation through its microvillus cross-linking function.

Worldwide the number of individuals being overweight or obese has dramatically increased during the last decades, which is also associated with a similar dramatic increase of individuals afflicted with metabolic disorders like dyslipidemia, hypertension, and non-alcoholic fatty liver disease (NAFLD). Genetic predisposition may account for some of the increases in body weight and the development of metabolic disorders; however, much is probably also related to the changes in physical activity and dietary pattern. Indeed, results of epidemiological studies suggest that a ‘western-type dietary pattern’ composed of highly processed foods, sweetened foods, and beverages, all adding to a low fiber but high sugar and saturated fat intake, may increase the odd of developing overweight and metabolic disorders. Consumption of sugar, and especially, fructose has repeatedly been discussed to be a key contributor to the development of health disturbances including hypertension, dyslipidemia, insulin resistance as well as NAFLD. However, despite intense research effort, the question if and how (high) dietary fructose intake interferes with human health has not yet been fully answered also as findings are sometimes contradictory. In the present narrative review, results of recent studies assessing the effect of fructose consumption on the development of metabolic disorders including hypertension, dyslipidemia, cardiovascular diseases (CVDs), hyperinsulinemia, and NAFLD as well as underlying molecular mechanisms are reviewed, thereby, aiming to further address the question if (high) fructose intake is a trigger of metabolic diseases.

Hepatocellular carcinoma (HCC) is considered one of the most aggressive tumors worldwide. The consumption of lipid-enriched diets, mainly high cholesterol, induces oxidative stress and chronic inflammation, leading to HCC progression. Moreover, fatty acids and cholesterol could display differential responses on immune cells inside the tumor immune microenvironment (TIME). Tumor-associated macrophages (TAMs) represent one of the most critical leukocytes in the tumor microenvironment (TME) displaying pro-tumoral responses and one of the mainly cholesterol donors to cancer cells. Immunotherapy or cholesterol regulators, alone or combined, would represent an effective strategy for HCC treatment. Nonetheless, steatotic etiology from non-alcoholic fatty liver disease (NAFLD)-HCC tumors has been unexpectedly resulting in highly aggressive behavior.

The prevalence of metabolic dysfunction-associated fatty liver disease (MAFLD) is increasing rapidly worldwide due to the obesity epidemic. Advanced stages of the MAFLD, such as non-alcoholic steatohepatitis (NASH) with advanced fibrosis or cirrhosis are affecting global health. Extracellular vesicles (EVs) are released by all cell types and are important in cell-to-cell communication and maintaining homeostasis, but they also play a role in the pathogenesis of various diseases. EVs contain biological information such as lipids, proteins, messenger RNAs (mRNAs), small RNAs, and DNA, and they act on (distant) target cells. The cargo of EVs is dependent on the type and the state of the releasing cell. EVs have been proposed as biomarkers, prognostic, and even therapeutic agents, also in the context of liver diseases. This review aims to give an overview of the current knowledge on EVs in MAFLD, including the role and interaction of EVs with different cell types in the liver. Several aspects of EVs, including their origin, characteristics, cargo, and functions are reviewed. Moreover, the potential of EVs as targets for the treatment of MAFLD is discussed.