IL9 and autoimmune hepatitis: Moreover, after IL-9 was inhibited, liver fibrosis and the levels of proinflammatory Th1 and Th17 cells were decreased in mice.169 This study may reveal a partial role for Th9 cells in AIH, as liver fibrosis and cirrhosis are also later features of AIH.2 However, more relevant studies are still needed to confirm the specific role of Th9 cells in AIH.