Pediatric autoimmune liver diseases (AILDs), including autoimmune hepatitis (AIH) and overlap syndromes like sclerosing cholangitis, are among the most common chronic liver conditions in the pediatric population. Currently, the treatment for AIH often involves long-term use of immunosuppressive therapy, which carries risks of severe side effects both in the short and long term. Due to these potential adverse effects, there is a critical need to explore alternative therapies that can modulate autoimmunity and potentially reduce or eliminate the dependence on immunosuppressive drugs. Autoimmune diseases, including AIH, typically arise in genetically predisposed individuals after exposure to certain environmental factors, leading to a breakdown in self-tolerance.The gut microbiome plays a crucial role in modulating the immune system through both anti-inflammatory and pro-inflammatory pathways. In advanced liver diseases, factors such as intestinal dysmotility, small intestinal bacterial overgrowth (SIBO), and increased intestinal permeability contribute to enhanced bacterial translocation, consistent with the "leaky gut" hypothesis. This phenomenon allows the passage of toxins, antigens, and bacteria into the systemic circulation, potentially exacerbating autoimmune responses. Consequently, altering the gut microbiome through dietary changes, probiotics, prebiotics, or fecal microbiota transplantation presents a promising therapeutic approach for autoimmune diseases.This study aims to investigate the gut microbiome and its modification following dietary intervention (specifically, a plant-based vegan diet) in pediatric AIH. Additionally, we will explore the potential role of such interventions in managing intestinal dysfunction in patients with advanced liver disease. In Aim 1, we will compare the baseline gut microbiome profiles of treatment-naïve pediatric AIH patients with those of healthy, age- and sex-matched controls to provide foundational insights. In Aim 2, we will evaluate the proportion of patients achieving biochemical remission after 180 days of a vegan versus standard diet in AIH patients. We will also assess changes in stool metagenomics, metabolomics, cytokine profiles, gut epithelial barrier function, and liver disease severity scores between the two dietary groups.

This study aims to demonstrate the potential benefits of a vegan diet in managing autoimmune hepatitis. It seeks to provide evidence supporting dietary modifications as a complementary approach to standard medical treatments for a wide range of autoimmune or autoimmune-like disorders, potentially paving the way for future therapeutic strategies.