Hepatocytes paradoxically affect intrahepatic IFN-γ production in autoimmune hepatitis due to Gal-9 expression and TLR2/4 ligand release.

Hepatocytes are the targets in autoimmune hepatitis (AIH) that results in T cell-dependent liver injury. However, hepatocytes may also affect the hepatic T cells in AIH, but the underlying mechanisms are not fully understood. Here we report that hepatocytes could secrete galectin-9 (Gal-9) to suppress the intrahepatic production of Th1 cytokine IFN-γ and restrict AIH development, but hepatocyte damage resulted in opposite effects due to release of TLR2/4 ligands that promoted the intrahepatic production of IL-1β, IL-6, and IL-12.

TLR2/4 ligand-amplified liver inflammation promotes initiation of autoimmune hepatitis due to sustained IL-6/IL-12/IL-4/IL-25 expression.

Autoimmune hepatitis (AIH), a serious autoimmune liver disease, can be a lifelong illness, leading to fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). So far the mechanisms for disease initiation are largely unknown. Here we report that the amplified non-AIH liver inflammation could promote the initiation of AIH due to the sustained increase of IL-6, IL-12, IL-4, and IL-25 in the liver.