Lactobacillus improves the effects of prednisone on autoimmune hepatitis via gut microbiota-mediated follicular helper T cells

BACKGROUND: Autoimmune hepatitis (AIH) is a chronic, immune-mediated liver dysfunction. The gut microbiota and T follicular helper (Tfh) cells play critical roles in the immunopathogenesis and progression of AIH. We aimed to investigate the effect of gut microbiota combined with prednisone therapy on Tfh cell response in AIH. METHODS: Samples from AIH patients and mouse model of experimental autoimmune hepatitis (EAH) were analyzed using real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, western blotting, flow cytometry, and hematoxylin–eosin staining to determine the role of gut microbiota on AIH. RESULTS: Lactobacillus significantly increased the levels of Bacteroides fragilis, Clostridium, Clostridium leptum, Bifidobacterium, and Lactobacillus and significantly enhanced the suppressive effects of prednisone on the levels of AIH clinical indexes in AIH patients. Lactobacillus exerts the same prptective effects as prednisone in EAH mice and enhanced the effects of prednisone. Lactobacillus also reinforced the inhibitory effects of prednisone on the levels of serum IL-21 and the proportions of Tfh cells in peripheral blood mononuclear cells. Mechanistically, prednisone and Lactobacillus regulated Tfh cell response in EAH mice in an MyD88/NF-κB pathway-dependent manner. CONCLUSION: Our results suggested a therapeutic potential of Lactobacillus in the prednisone-combined treatment of AIH. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12964-021-00819-7.