A significant reduction in flora diversity is a core feature: metagenomic analysis shows that the abundance of obligate anaerobic bacteria (such as Roseburia, Faecalibacterium prausnitzii) that produce SCFAs in the intestines of AIH patients is decreased, while potential pathogenic bacteria (such as Veillonella) are over-proliferated, and the abundance of Veillonella dispar is positively correlated with serum ALT levels and the degree of liver inflammation (23). Here, GPT is linked to autoimmune hepatitis.