Genetic and Environmental Risk Factors for Autoimmune Hepatitis

Hepatic and Extrahepatic Characteristics of Autoimmune Hepatitis: A 23-year Hospital-Based Cohort Study

BACKGROUND

The characteristics of autoimmune hepatitis (AIH) in Asia mostly remain elusive.

METHODS

A cohort study of liver biopsy-proven AIH patients was conducted in a tertiary care cancer of Taiwan.

RESULTS

From 1999 to 2022, of 13,766 patients who underwent liver biopsy, 150 patients with AIH were enrolled. The female-to-male ratio was 2.26. At baseline, the mean age was 51.09 years, mean alanine aminotransferase level was 494.11 U/L, and 17 (11.3%) had cirrhosis. All except one patient had AIH type 1. The females were older and had higher baseline cirrhosis rates than did the males. The 23-year cumulative incidences of cirrhosis, hepatocellular carcinoma (HCC), mortality/liver transplantation, autoimmune diseases and extrahepatic cancer were 64.2%, 13.3%, 23.4%, 30.7% and 21.2%, respectively. The 1-year, 2-year, 3-year, 5-year, 10-year and 20-year postimmunosuppressive therapy relapse rates were 60%, 78.2%, 81.8%, 89.1%, 94.5% and 100%, respectively. Baseline associations were as follows: alkaline phosphatase (Alk-p) levels with postimmunosuppressive therapy flare [hazard ratio (HR): 1.003; 95% CI HR: 1.000-1.005]; age with HCC (1.072; 1.010-1.138) and all-cause cancer (1.041;1.005-1.079); cirrhosis with mortality/liver transplantation (11.933;1.984-71.787); and antinuclear antibody (ANA) titers with mortality/liver transplantation (1.001;1.000-1.003), cirrhosis (1.001;1.000-1.002), and autoimmune diseases (1.001; 1.000-1.002).

CONCLUSION

In an Asian country endemic for viral hepatitis, the female-to-male and baseline cirrhosis rates of AIH patients were lower than expected, while over 60% of the patients eventually developed cirrhosis. The high posttherapy relapse rate warrants cautious monitoring, particularly for patients with high baseline Alk-p levels. Baseline age, cirrhosis status and ANA titers are crucial for outcomes.

Fecal microbiota transplantation in autoimmune diseases - An extensive paper on a pathogenetic therapy

The role of infections in the pathogenesis of autoimmune diseases has long been recognized and reported. In addition to infectious agents, the internal composition of the "friendly" living bacteria, (microbiome) and its correlation to immune balance and dysregulation have drawn the attention of researchers for decades. Nevertheless, only recently, scientific papers regarding the potential role of transferring microbiome from healthy donor subjects to patients with autoimmune diseases has been proposed. Fecal microbiota transplantation or FMT, carries the logic of transferring microorganisms responsible for immune balance from healthy donors to individuals with immune dysregulation or more accurately for our paper, autoimmune diseases. Viewing the microbiome as a pathogenetic player allows us to consider FMT as a pathogenetic-based treatment. Promising results alongside improved outcomes have been demonstrated in patients with different autoimmune diseases following FMT. Therefore, in our current extensive review, we aimed to highlight the implication of FMT in various autoimmune diseases, such as inflammatory bowel disease, autoimmune thyroid and liver diseases, systemic lupus erythematosus, and type 1 diabetes mellitus, among others. Presenting all the aspects of FMT in more than 12 autoimmune diseases in one paper, to the best of our knowledge, is the first time presented in medical literature. Viewing FMT as such could contribute to better understanding and newer application of the model in the therapy of autoimmune diseases, indeed.

Missing Causality and Heritability of Autoimmune Hepatitis

BACKGROUND

Autoimmune hepatitis has an unknown cause and genetic associations that are not disease-specific or always present. Clarification of its missing causality and heritability could improve prevention and management strategies.

AIMS

Describe the key epigenetic and genetic mechanisms that could account for missing causality and heritability in autoimmune hepatitis; indicate the prospects of these mechanisms as pivotal factors; and encourage investigations of their pathogenic role and therapeutic potential.

METHODS

English abstracts were identified in PubMed using multiple key search phases. Several hundred abstracts and 210 full-length articles were reviewed.

RESULTS

Environmental induction of epigenetic changes is the prime candidate for explaining the missing causality of autoimmune hepatitis. Environmental factors (diet, toxic exposures) can alter chromatin structure and the production of micro-ribonucleic acids that affect gene expression. Epistatic interaction between unsuspected genes is the prime candidate for explaining the missing heritability. The non-additive, interactive effects of multiple genes could enhance their impact on the propensity and phenotype of autoimmune hepatitis. Transgenerational inheritance of acquired epigenetic marks constitutes another mechanism of transmitting parental adaptations that could affect susceptibility. Management strategies could range from lifestyle adjustments and nutritional supplements to precision editing of the epigenetic landscape.

CONCLUSIONS

Autoimmune hepatitis has a missing causality that might be explained by epigenetic changes induced by environmental factors and a missing heritability that might reflect epistatic gene interactions or transgenerational transmission of acquired epigenetic marks. These unassessed or under-evaluated areas warrant investigation.

Trust Your Gut: The Association of Gut Microbiota and Liver Disease

The gut microbiota composition is important for nutrient metabolism, mucosal barrier function, immunomodulation, and defense against pathogens. Alterations in the gut microbiome can disturb the gut ecosystem. These changes may lead to the loss of beneficial bacteria or an increase in potentially pathogenic bacteria. Furthermore, these have been shown to contribute to the pathophysiology of gastrointestinal and extra-intestinal diseases. Pathologies of the liver, such as non-alcoholic liver disease, alcoholic liver disease, cirrhosis, hepatocellular carcinoma, autoimmune hepatitis, viral hepatitis, and primary sclerosing cholangitis have all been linked to changes in the gut microbiome composition. There is substantial evidence that links gut dysbiosis to the progression and complications of these pathologies. This review article aimed to describe the changes seen in the gut microbiome in liver diseases and the association between gut dysbiosis and liver disease, and finally, explore treatment options that may improve gut dysbiosis in patients with liver disease.

The intestinal and biliary microbiome in autoimmune liver disease-current evidence and concepts

Autoimmune liver diseases are a group of immune-mediated liver diseases with three distinct entities, including autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis. The interplay of genetic and environmental factors leads to the breakdown of self-tolerance, resulting in hyper-responsiveness, and auto-aggressive immune activation. Emerging evidence links autoimmune liver diseases with alterations of the commensal microbiome configuration and aberrant immune system activation by microbial signals, mainly via the gut-liver axis. Thus, the microbiome is a new frontier to deepen the pathogenetic understanding, uncover biomarkers, and inspire innovative treatments. Herein, we review the current evidence on the role of the microbiome in autoimmune liver diseases from both clinical and basic research. We highlight recent achievements and also bottlenecks and limitations. Moreover, we give an outlook on future developments and potential for clinical applications.

Selected transgenic murine models of human autoimmune liver diseases

Murine models of human diseases are of outmost importance for both studying molecular mechanisms driving their development and testing new treatment strategies. In this review, we first discuss the etiology and risk factors for autoimmune liver disease, including primary biliary cholangitis, autoimmune hepatitis and primary sclerosing cholangitis. Second, we highlight important features of murine transgenic models that make them useful for basic scientists, drug developers and clinical researchers. Next, a brief description of each disease is followed by the characterization of selected animal models.

Patients with Autoimmune Hepatitis Report Lower Lifetime Coffee Consumption

BACKGROUND

Coffee drinking has been associated with decreased risk of some autoimmune diseases as well liver disease and outcomes. Environmental factors, such as coffee consumption, are yet to be assessed among patients with autoimmune hepatitis (AIH).

AIM

We sought to investigate the relationship between coffee consumption and risk of AIH utilizing the Genetic Repository of Autoimmune Liver Disease and Contributing Exposures (GRACE) database.

METHODS

Lifetime coffee drinking was collected from 358 AIH patients (cases) and 564 volunteers (controls) from primary care visits. Groups were compared utilizing the Wilcoxon rank sum test for continuous variables and the Chi-square test for discrete variables. Logistic regression was used to analyze the effects of different coffee parameters (time, frequency, and cups) after adjusting for age, sex, education, smoking status, BMI, and daily activity.

RESULTS

24.6% of AIH patients never drank coffee compared to 15.7% of controls (p < 0.001), and only 65.6% were current drinkers compared with 77% of controls (p < 0.001). Among "ever" coffee drinkers, AIH patients consumed fewer lifetime cups of coffee per month (45 vs. 47 for controls, p < 0.001) and spent less percentage of life drinking coffee (62.5% vs. 69.1% for controls, p < 0.001). Concurrent inflammatory bowel disease was higher among AIH patients than controls (5.7% vs. 1.2%, p < 0.001), yet did not significantly contribute to "never" coffee drinking status. The relationship between lower coffee consumption and AIH persisted even after controlling for covariates.

CONCLUSIONS

Coffee consumption is lower among patients with AIH compared to controls.

Environmental exposure as a risk-modifying factor in liver diseases: Knowns and unknowns

Liver diseases are considered to predominantly possess an inherited or xenobiotic etiology. However, inheritance drives the ability to appropriately adapt to environmental stressors, and disease is the culmination of a maladaptive response. Thus “pure” genetic and “pure” xenobiotic liver diseases are modified by each other and other factors, identified or unknown. The purpose of this review is to highlight the knowledgebase of environmental exposure as a potential risk modifying agent for the development of liver disease by other causes. This exercise is not to argue that all liver diseases have an environmental component, but to challenge the assumption that the current state of our knowledge is sufficient in all cases to conclusively dismiss this as a possibility. This review also discusses key new tools and approaches that will likely be critical to address this question in the future. Taken together, identifying the key gaps in our understanding is critical for the field to move forward, or at the very least to “know what we don't know.”

Metabolic-associated fatty liver disease and autoimmune hepatitis: an overlooked interaction

INTRODUCTION

Metabolic-associated fatty liver disease (MAFLD) is the most common liver disease globally, and affects about a quarter of the general population. Autoimmune hepatitis (AIH) is a severe (sometimes fatal) liver disease that affects children and adults, with a rising prevalence. Thus, not surprisingly, both conditions can frequently coexist, with potential synergistic impact on the course of the disease and response to therapy of both entities.

AREAS COVERED

In this work, the authors aimed to provide a narrative updated review on this interaction, diagnosis, and management of MAFLD/AIH and the current challenges.

EXPERT OPINION

Clarifying the nature of the complex interaction between the two diseases was hampered by a myriad of factors, particularly the previous diagnosis of exclusion for fatty liver disease associated with metabolic dysfunction. The recent redefinition of fatty liver disease that led to the development of positive diagnostic criteria for MAFLD has the premise to help in circumventing some of these challenges.

A novel insight into the pathophysiology of autoimmune hepatitis: An immune activator mutation in the FLT3 receptor

Autoimmune hepatitis (AIH) is a chronic progressive autoimmune liver disease characterized by hypergammaglobulinemia, interface hepatitis, a female preponderance, and the presence of autoantibodies in most patients. The presence of HLA-DR3/DR4 and functional impairment in regulatory T cells are associated with AIH. However, AIH is a multifactorial complex disease. This report is a description of a case of seronegative AIH in a girl with chronic hepatitis, a high immunoglobulin E (IgE) level, perforating nodular dermatitis, and sheer eosinophilia. To re-evaluate the diagnosis, whole exon sequencing was performed. It was determined that the patient had ancestral haplotype A1-B8-DR3, which is associated with autoimmunity. Importantly, it was also noted that an undocumented point mutation (Ala627Thr) of the FMS-like tyrosine 3 kinase (FLT3) receptor was present. This FLT3 receptor gain-of-function mutation is associated with the activation of the mechanistic target of rapamycin (mTOR), and dendritic cell activation. In addition, a loss-of-function mutation in the melanocortin-3 receptor gene, which inhibits interleukin 4, was detected. The constellation of these immune deregulatory factors may have propagated auto-aggression of the liver, causing chronic hepatitis with AIH features. The findings of seronegativity with eosinophilia and a high IgE level led us to hypothesize that the pathognomonic mechanism in this case was unlike that of classic AIH pathophysiology. Since mTOR is constitutively activated, mTOR inhibitors may be a useful option to treat AIH and dermatitis.

Human Cytomegalovirus and Autoimmune Diseases: Where Are We?

Human cytomegalovirus (HCMV) is a ubiquitous double-stranded DNA virus belonging to the β-subgroup of the herpesvirus family. After the initial infection, the virus establishes latency in poorly differentiated myeloid precursors from where it can reactivate at later times to cause recurrences. In immunocompetent subjects, primary HCMV infection is usually asymptomatic, while in immunocompromised patients, HCMV infection can lead to severe, life-threatening diseases, whose clinical severity parallels the degree of immunosuppression. The existence of a strict interplay between HCMV and the immune system has led many to hypothesize that HCMV could also be involved in autoimmune diseases (ADs). Indeed, signs of active viral infection were later found in a variety of different ADs, such as rheumatological, neurological, enteric disorders, and metabolic diseases. In addition, HCMV infection has been frequently linked to increased production of autoantibodies, which play a driving role in AD progression, as observed in systemic lupus erythematosus (SLE) patients. Documented mechanisms of HCMV-associated autoimmunity include molecular mimicry, inflammation, and nonspecific B-cell activation. In this review, we summarize the available literature on the various ADs arising from or exacerbating upon HCMV infection, focusing on the potential role of HCMV-mediated immune activation at disease onset.

Hepatic steatosis is highly prevalent but is not correlated with stiffness in autoimmune hepatitis

The prevalence and impact of hepatic steatosis among patients with autoimmune hepatitis (AIH) is not well described.We conducted a cross-sectional study to determine the prevalence of hepatic steatosis in AIH patients and examined its relationship with hepatic fibrosis using vibration controlled transient elastography. Liver stiffness measurement (LSM), controlled attenuation parameter (CAP), gender, current age, and body mass index (BMI) were collected from 277 AIH patients. Hepatic steatosis was defined as CAP >263 db/m.The study participants were mostly female (82%) with an average age of 49 years and BMI 29.7 kg/m. Mean LSM was 12.5 (standard deviation 13.5) kPa and CAP was 244 (standard deviation 63) db/m. The prevalence of coexisting steatosis was 33.2%, and steatosis did not correlate with LSM (r = 0.05, P = .46). In this study, only gender (females with 31% lower LSM on average compared to males, P = .001) and BMI (each unit increase of BMI resulted in a 1.48% increase on average LSM, P = .01) correlated with LSM. Male gender had significant association with increased LSM, after controlling for age, BMI, and CAP (P = .001).This exploratory study using noninvasive vibration controlled transient elastography revealed hepatic steatosis is highly prevalent in patients with AIH but not associated with liver fibrosis.