Table 4.

Studies characterizing the composition of the gut microbiota in autoimmune hepatitis.

Author Reference	Country	Study Design	Participants	Changes in the Composition of Gut Microbiota in AIH	Key Findings
[107]	China	Case-control	24 AIH 8 healthy controls	↓ Bifidobacterium ↓ Lactobacillus Escherichia coli and Enterococcus were unchanged	↑ Intestinal permeability and gut dysbiosis ↑ Bacterial translocation, indicated by increased LPS, was correlated with AIH disease severity
[104]	Egypt	Case-control	5 AIH 10 healthy controls	↑ Faecalibacterium ↑ Blautia ↑ Streptococcus ↑ Veillonella ↑ Eubacterium ↑ Lachnospiraceae ↑ Butyricicoccus ↑ Haemophilus ↑ Bacteroides ↑ Clostridium ↑ Ruminococcaceae ↓ Prevotella ↓ Parabacteroides ↓ Dilaster	↓ Bacterial diversity in AIH ↑ Butyrate forming bacteria (e.g., Butyricicoccus and Ruminococcaceae)
[106]	Germany	Case-control	72 AIH 95 healthy controls 99 primary biliary cholangitis 81 ulcerative colitis	↑ Proteobacteria ↑ Veillonella ↑ Streptococcus ↑ Lactobacillus ↓ Firmicutes in all groups ↓ Faecalibacterium ↓ Bifidobacterium	↓ Bifidobacterium in AIH was associated with increased disease activity and failure to achieve remission ↓ α-diversity in AIH patients vs. healthy controls
[105]	China	Cross-sectional	119 steroid-naïve AIH 132 healthy controls	↑ Veillonella ↑ Streptococcus ↑ Klebsiella ↑ Lactobacillus ↓ Clostridiales ↓ Ruminococcaceae ↓ Rikenellaceae ↓ Oscillospira ↓ Parabacteroides ↓ Coprococcus	↑ LPS biosynthesis ↓ α-diversity Veillonella showed a strong association with AIH and was link with ↑ AST and progression of liver inflammation Veillonella, Lactobacillus, Oscillospira, and Clostridiales have high diagnostic value in AIH
[111]	China	Case-control	37 AIH 78 healthy controls	↑ Veillonella ↑ Faecalibacterium ↑ Akkermansia ↑ Klebsiella ↑ Enterobacteriaceae_unclassified ↑ Megasphaera ↓ Pseudobutyrivibrio ↓ Lachnospira ↓ Ruminococcaceae ↓ Blautia ↓ Erysipelotrichaceae_incertae_sedis ↓ Phascolarctobacterium	A combination of Bacteroides, Ruminococcaceae, Lachnospiraceae, Veillonella, Roseburia, and Ruminococcaceae could distinguish AIH patients from healthy controls
[108]	China	Case-control	32 AIH 20 NAFLD 20 healthy controls	↑ Escherichia coli ↓ Bifidobacterium ↓ Lactobacillus ↓ Bacteroides ↓ C. leptum	↑ Serum LPS in comparison to NAFLD and healthy controls

AIH, autoimmune hepatitis; LPS, lipopolysaccharide; NAFLD, nonalcoholic fatty liver disease; SCFAs, short-chain fatty acids; ↑, increase; and ↓, decrease.