Association of an overlap syndrome of autoimmune hepatitis and primary biliary cirrhosis with cytomegalovirus infection

Pathogenesis of Autoimmune Hepatitis-Cellular and Molecular Mechanisms

Pediatric autoimmune liver disorders include autoimmune hepatitis (AIH), autoimmune sclerosing cholangitis (ASC), and de novo AIH after liver transplantation. AIH is an idiopathic disease characterized by immune-mediated hepatocyte injury associated with the destruction of liver cells, causing inflammation, liver failure, and fibrosis, typically associated with autoantibodies. The etiology of AIH is not entirely unraveled, but evidence supports an intricate interaction among genetic variants, environmental factors, and epigenetic modifications. The pathogenesis of AIH comprises the interaction between specific genetic traits and molecular mimicry for disease development, impaired immunoregulatory mechanisms, including CD4+ T cell population and Treg cells, alongside other contributory roles played by CD8+ cytotoxicity and autoantibody production by B cells. These findings delineate an intricate pathway that includes gene to gene and gene to environment interactions with various drugs, viral infections, and the complex microbiome. Epigenetics emphasizes gene expression through hereditary and reversible modifications of the chromatin architecture without interfering with the DNA sequence. These alterations comprise DNA methylation, histone transformations, and non-coding small (miRNA) and long (lncRNA) RNA transcriptions. The current first-line therapy comprises prednisolone plus azathioprine to induce clinical and biochemical remission. Further understanding of the cellular and molecular mechanisms encountered in AIH may depict their impact on clinical aspects, detect biomarkers, and guide toward novel, effective, and better-targeted therapies with fewer side effects.

Examining pathogenic concepts of autoimmune hepatitis for cues to future investigations and interventions

BACKGROUND

Multiple pathogenic mechanisms have been implicated in autoimmune hepatitis, but they have not fully explained susceptibility, triggering events, and maintenance or escalation of the disease. Furthermore, they have not identified a critical defect that can be targeted. The goals of this review are to examine the diverse pathogenic mechanisms that have been considered in autoimmune hepatitis, indicate investigational opportunities to validate their contribution, and suggest interventions that might evolve to modify their impact. English abstracts were identified in PubMed by multiple search terms. Full length articles were selected for review, and secondary and tertiary bibliographies were developed. Genetic and epigenetic factors can affect susceptibility by influencing the expression of immune regulatory genes. Thymic dysfunction, possibly related to deficient production of programmed cell death protein-1, can allow autoreactive T cells to escape deletion, and alterations in the intestinal microbiome may help overcome immune tolerance and affect gender bias. Environmental factors may trigger the disease or induce epigenetic changes in gene function. Molecular mimicry, epitope spread, bystander activation, neo-antigen production, lymphocytic polyspecificity, and disturbances in immune inhibitory mechanisms may maintain or escalate the disease. Interventions that modify epigenetic effects on gene expression, alter intestinal dysbiosis, eliminate deleterious environmental factors, and target critical pathogenic mechanisms are therapeutic possibilities that might reduce risk, individualize management, and improve outcome. In conclusion, diverse pathogenic mechanisms have been implicated in autoimmune hepatitis, and they may identify a critical factor or sequence that can be validated and used to direct future management and preventive strategies.

Pathogens and autoimmune hepatitis

Autoimmune hepatitis (AIH) is a severe form of hepatitis resulting in the autoimmune-mediated destruction of the liver parenchyma. Whereas many of the immunopathogenic events have been elucidated and some of the drivers of the disease have been identified, little is known about the aetiology of the disease. There are certain risk factors, such as particular human leucocyte antigen (HLA) haplotypes, that enhance the susceptibility for AIH or influence the severity of the disease. However, as for many other autoimmune diseases, the mere presence of such risk factors does not warrant the occurrence of the disease. Not all individuals carrying risk factors develop AIH, and not all patients with AIH are carriers of high-risk alleles. Thus, additional environmental factors need to be considered as triggers for AIH. Environmental factors include diet, sunlight exposure, stress, medication and hygiene, as well as pathogen infections and vaccinations. This review discusses if pathogens should be considered as triggers for the initiation and/or propagation of AIH.

Current progress in research of overlap syndrome of autoimmune liver diseases

Autoimmune liver diseases (AILDs) include autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). Overlap syndrome (OS) of AILDs is a relatively infrequent disease that has the combined clinical, biochemical, serological, histological and radiological features of AIH and PBC or PSC, mainly comprising AIH-PBC and AIH-PSC overlap syndromes. The AIH-PBC overlap syndrome is common in adults, while the AIH-PSC overlap syndrome is predominantly found in children. Overlap syndromes have a progressive course and may finally lead to liver cirrhosis and liver failure without treatment. High-dose ursodeoxycholic acid (UDCA) combined with immunosuppressive therapy with corticosteroids and/or azathioprine (AZA) is usually used in both AIH-PBC and AIH-PSC overlap syndromes. At present, liver transplantation is the only option with known therapeutic benefit for end-stage patients.

Advances in research of autoimmune hepatitis

Autoimmune hepatitis (AIH) is a chronic inflammatory disease of the liver triggered by an immune-mediated attack, characterized by the presence of hypergammaglobulinemia, serum autoantibodies, interface hepatitis on histological examination, and good response to immunosuppressive therapy. In this article, we will review the role of genetic susceptibility, inducing factors, molecular mimicry, liver injury, and immune regulation imbalance in the pathogenesis of AIH. In addition, this article systematically describes the advances in research of AIH in terms of clinical features, serological characteristics, histologic features, diagnosis and therapy.

Synthesis and anti-HCMV activity of 1-[ω-(phenoxy)alkyl]uracil derivatives and analogues thereof

HCMV infection represents a life-threatening condition for immunocompromised patients and newborn infants and novel anti-HCMV agents are clearly needed. In this regard, a series of 1-[ω-(phenoxy)alkyl]uracil derivatives were synthesized and examined for antiviral properties. Compounds 17, 20, 24 and 28 were found to exhibit highly specific and promising inhibitory activity against HCMV replication in HEL cell cultures with EC50 values within 5.5-12μM range. Further studies should be undertaken to elucidate the mechanism of action of these compounds and the structure-activity relationship for the linker region.