Genetic factors affect the etiology, clinical characteristics and outcome of autoimmune hepatitis

A Closer Look into Autoimmune Liver Diseases

Autoimmune liver diseases involve a heterogeneous group of chronic inflammatory disorders, including autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis. Sometimes presented consistently as an overlapping syndrome, their pathogenesis is rather complex and has yet to be fully elucidated, despite extensive research efforts. This review article corroborates the molecular mechanisms of autoimmune liver diseases, as well as existing and potential therapeutic modalities.

Clinical, biochemical and histological features related to treatment response and prognosis in autoimmune hepatitis

INTRODUCTION AND OBJECTIVES

Autoimmune hepatitis (AIH) is a rare disease with a complex and not fully understood pathogenesis. Prognostic factors that might influence treatment response, relapse rates, and transplant-free survival are not well established. This study investigates clinical and biochemical markers associated with response to immunosuppression in patients with AIH.

MATERIALS AND METHODS

This retrospective cohort study included 102 patients with AIH treated with immunosuppressants and followed at the Federal University of Minas Gerais, Brazil, from 1990 to 2018. Pretreatment data such as clinical profiles, laboratory, and histological exams were analyzed regarding biochemical response at one year, histological remission, relapse, and death/transplantation rates.

RESULTS

Cirrhosis was present in 59 % of cases at diagnosis. One-year biochemical remission was observed in 55.7 % of the patients and was found to be a protective factor for liver transplant. Overall survival was 89 %. Patients with ascites at disease onset showed a higher aspartate aminotransferase (AST)/ alanine aminotransferase (ALT) ratio and elevated Model of end-stage liver disease (MELD) score. The presence of ascites was significantly associated with a 20-fold increase in mortality rate.

CONCLUSIONS

AIH has a severe clinical phenotype in Brazilians, with high rates of cirrhosis and low remission rates. Early diagnosis and treatment are essential for achieving remission and reducing complications. The presence of ascites is significantly associated with mortality, emphasizing the importance of monitoring and prompt intervention. This study also stresses the need for further research on AIH in Latin America.

Association of HLA DRB1 Allele Profile with Pediatric Autoimmune Liver Disease in India

Objectives

The aim of this study is to study the association of human leukocyte antigen (HLA) DRB1 alleles with treatment response in Indian children with autoimmune liver disease (AILD).

Methods

HLA DRB1 alleles of 71 Indian children with pediatric AILD (pAILD) were analyzed along with 25 genetically confirmed patients with Wilson disease as controls. After 1 year of therapy, all those who failed to normalize aspartate & alanine transferase (AST/ ALT) (below 1.5 times of upper limit of normal) and/or failed to normalize IgG levels, or who had >2 relapses (AST/ALT levels >1.5 times of upper limit of normal) while on treatment, were labeled as difficult to treat (DTT).

Results

HLA DRB1∗3 was found to be significantly associated with AIH type 1 (46.2% vs. 4% in controls; P corrected = 0.011). Majority of the patients [55 (77.5%)] had chronic liver disease at presentation, with 42 (59.2%) having portal hypertension and 17 (23.9%) having ascites. Out of the 71 with pAILD, 19 (26.8%) were DTT. HLA DRB1∗14 was found to be independently associated with DTT cases (36.8% vs. 9.6%, OR 5.87, 95% CI 1.07-32.09, P = 0.041). Other factors independently associated with DTT were presence of autoimmune sclerosing cholangitis (OR 8.57, P = 0.008) and high-risk varices (OR 7.55, P = 0.016), improving the correctness of classification of the model from 73.2% to 84.5%.

Conclusion

HLA DRB1∗14 is independently associated with treatment response in pAILD and HLA DRB1∗3 is associated with AIH type 1. HLA DRB1 alleles may thus provide supportive information for diagnosis and prognosis of AILD.

The Role of Gut Microbiota in Some Liver Diseases: From an Immunological Perspective

Gut microbiota is a microecosystem composed of various microorganisms. It plays an important role in human metabolism, and its metabolites affect different tissues and organs. Intestinal flora maintains the intestinal mucosal barrier and interacts with the immune system. The liver is closely linked to the intestine by the gut-liver axis. As the first organ that comes into contact with blood from the intestine, the liver will be deeply influenced by the gut microbiota and its metabolites, and the intestinal leakage and the imbalance of the flora are the trigger of the pathological reaction of the liver. In this paper, we discuss the role of gut microbiota and its metabolites in the pathogenesis and development of autoimmune liver diseases((including autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis), metabolic liver disease such as non-alcoholic fatty liver disease, cirrhosisits and its complications, and liver cancer from the perspective of immune mechanism. And the recent progress in the treatment of these diseases was reviewed from the perspective of gut microbiota.

Impact of genetic and environmental factors on autoimmune hepatitis

Autoimmune hepatitis (AIH) is a chronic non-resolving liver disease characterized by diffuse hypergammaglobulinemia, the presence of autoantibodies and characteristic histological findings. The disease can have catastrophic outcome with the development of end-stage liver disease if misdiagnosed/undiagnosed and left untreated. AIH pathogenesis remains obscure and the main hypothesis supports its development in genetically predisposed individuals after being exposed to certain environmental triggers. Genetic predisposition is linked to the presence of certain HLA alleles, mainly HLA-DR3 and HLA-DR4. However, a wide number of non-HLA epitopes have also been associated with the disease although data vary significantly among different ethnic groups. Therefore, it is likely that epigenetic alterations may also play a crucial role in disease's pathogenesis, although not yet extensively studied. The aim of this review was to summarize the genetic and environmental factors that have been associated with AIH, but also to open new insights towards the role of epigenetic modifications in the etiology of the disease.

Noninvasive indices for monitoring disease course in Chinese patients with autoimmune hepatitis

OBJECTIVE

Noninvasive and simple tests to forecast cirrhosis is in great need clinically. This study aimed to assess the clinical significance of several noninvasive indices in predicting cirrhosis in Chinese patients with autoimmune hepatitis (AIH).

MATERIALS AND METHODS

Liver function test and blood cell analysis were conducted in 76 AIH patients and 75 paired healthy subjects to calculate aspartate aminotransferase to alanine aminotransferase ratio(AAR), aspartate aminotransferase to platelet ratio index (APRI), fibrosis index based on the four factors (FIB-4), gamma-glutamyl transferase to platelet ratio (GPR), red blood cell distribution width (RDW), neutrophil to lymphocyte ratio (NLR), lymphocyte to monocyte ratio (LMR), and platelet to lymphocyte ratio (PLR). Binary logistic regression was performed to analysis the risk factors of liver cirrhosis and receiver operating characteristic (ROC) curve was conducted to evaluate the diagnostic value of each index and compare their diagnostic performance with serum biomarkers commonly used in the clinical setting for liver fibrosis assessing including hyaluronic acid (HA), laminin(LN), procollagen III N terminal peptide (PIIINP) and type IV collagen (ColIV).

RESULTS

AAR, APRI, FIB-4, GPR, NLR and RDW were elevated remarkably in AIH patients with cirrhosis; AAR, FIB-4 and RDW were identified to be independent risk factors of cirrhosis with OR (95%CI) of 3.517 (1.300-9.514), 1.247(1.032-1.506) and 1.414 (1.086-1.842) respectively; ROC analysis showed that the area under the ROC curve (AUC) of AAR, FIB-4 and RDW were 0.801,0.82 and 0.739, with moderate diagnostic value and better than HA, LN, PIIINP and ColIV in identifying those with cirrhosis from AIH patients.

CONCLUSION

AAR, FIB-4 and RDW were independent risk factors of AIH cirrhosis and can be served as reference indices to monitor disease course in AIH.

Intestinal microbiome and permeability in patients with autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe inflammatory liver disease. The underlying mechanisms remain unclear, but recent studies provided new perspectives on altered intestinal microbiome and permeability in AIH animal models and patients, highlighting gut-liver crosstalk in the pathogenesis of AIH. Transgenic AIH mice carrying HLA-DR3 showed reduced diversity and total load of gut microbiota. Germ-free mice are resistant to concanavalin A-induced liver injury, whereas enterogenouss antigens induce the activation of natural killer T cells participating in concanavalin A-induced liver injury, supporting the close relationship between microbiota and AIH. Moreover, 'molecular mimicry' provides a plausible interpretation of the immune reactions between microorganic antigens and liver autoantigens, for instance, cytochrome P4502D6, the target of cross-reactivity between virus and self. Nevertheless, direct evidence for the intestinal microbiome and permeability in AIH is still limited. The relationship between AIH susceptibilities and an intestinal microbiome shaped by drugs, diets or genes needs further study.

Genetics and epigenetics in the pathogenesis of primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic, slowly progressive cholestatic autoimmune liver disease predominantly afflicting women. PBC is characterized by the presence of disease-specific antimitochondrial antibodies and the histological destruction of intrahepatic bile ducts, which eventually lead to cirrhosis and hepatic failure. Fortunately, ursodeoxycholic acid therapy has improved the outcome of the vast majority of PBC cases. Although the etiology of PBC has not yet been elucidated, human leukocyte antigen (HLA) class II alleles have been consistently associated with disease onset for decades. PBC patients may also have genetically determined risk factors in non-HLA regions. Meanwhile, exposure to environmental factors, such as infectious diseases and harmful chemicals, can produce epigenetic alterations in some individuals and subsequent PBC onset. In this review, we describe the influence of HLA alleles and other gene polymorphisms on PBC along with the results of genome-wide association studies on this disease and its future prospects in terms of epigenetics.

Genetic Contribution to the Pathogenesis of Primary Biliary Cholangitis

Formerly termed primary biliary cirrhosis, primary biliary cholangitis (PBC) is a chronic and progressive cholestatic liver disease characterized by the presence of antimitochondrial antibodies. Ursodeoxycholic acid (UDCA) therapy is the most effective and approved treatment for PBC and leads to a favorable outcome in the vast majority of cases. Although the etiology of PBC has not yet been elucidated, human leukocyte antigen (HLA) class II alleles have been consistently associated with disease onset for decades. Individuals in different geographic regions of the world may have varying susceptibility alleles that reflect indigenous triggering antigens. In this review, we describe the influence of HLA alleles and other gene polymorphisms on PBC along with the results of genome-wide association studies (GWAS) on this disease.

Autoimmune hepatitis: current challenges and future prospects

Autoimmune hepatitis (AIH) is a chronic progressive liver disease characterized by high levels of aminotransferases and autoantibodies, hypergammaglobulinemia, and interface hepatitis. AIH affects all races and all ages worldwide, regardless of sex, although a preponderance of females is a constant finding. The etiology of AIH has not been completely elucidated, but immunogenetic background and environmental parameters may contribute to its development. The most important genetic factor is human leukocyte antigens (HLAs), especially HLA-DR, whereas the role of environmental factors is not completely understood. Immunologically, disruption of the immune tolerance to autologous liver antigens may be a trigger of AIH. The diagnosis of classical AIH is fairly easy, though not without pitfalls. In contrast, the diagnosis of atypical AIH poses great challenges. There is confusion as to the definition of the disease entity and its boundaries in the diagnosis of overlap syndrome, drug-induced autoimmune hepatitis, and AIH with concomitant nonalcoholic fatty liver disease (NAFLD) or chronic hepatitis C. Centrilobular zonal necrosis is now included in the histological spectrum of AIH. However, the definition and the significance of AIH presenting with centrilobular zonal necrosis have not been examined extensively. In ~20% of AIH patients who are treated for the first time with standard therapy, remission is not achieved. The development of more effective and better tolerated novel therapies is an urgent need. In this review, we discuss the current challenges and the future prospects in relation to the diagnosis and treatment of AIH, which have been attracting considerable recent attention.

Immunology of hepatic diseases during pregnancy

The mother's immune system has to adapt to pregnancy accepting the semi-allograft fetus and preventing harmful effects to the developing child. Aberrations in feto-maternal immune adaptation may result in disease of the mother, such as liver injury. Five pregnancy-associated liver disorders have been described so far, however, little is known concerning immune alterations promoting the respective disease. These liver disorders are pre-eclampsia, hemolysis, elevated liver enzymes, low platelet count (HELLP), acute fatty liver, hyperemesis gravidarum, and intrahepatic cholestasis of pregnancy. On the other hand, pre-existing autoimmune liver injury of the mother can be affected by pregnancy. This review intends to summarize current knowledge linking feto-maternal immunology and liver inflammation with a special emphasis on novel potential biomarkers.