Background and aims: Increasing evidence in recent years has suggested that microRNA-7 (miR-7) is an important gene implicated in the development of various diseases including HCC. However, the role of miR-7 in autoimmune hepatitis (AIH) is unknown.
Approach and results: Herein, we showed that miR-7 deficiency led to exacerbated pathology in Concanavalin-A-induced murine acute autoimmune liver injury (ALI) model, accompanied by hyperactivation state of CD4+ T cells. Depletion of CD4+ T cells reduced the effect of miR-7 deficiency on the pathology of ALI. Interestingly, miR-7 deficiency elevated CD4+ T-cell activation, proliferation, and cytokine production in vitro. Adoptive cell transfer experiments showed that miR-7def CD4+ T cells could exacerbate the pathology of ALI. Further analysis showed that miR-7 expression was up-regulated in activated CD4+ T cells. Importantly, the transcription of pre-miR-7b, a major resource of mature miR-7 in CD4+ T cells, was dominantly dependent on transcription factor CCAAT enhancer binding protein alpha (C/EBPα), which binds to the core promoter region of the miR-7b gene. Global gene analysis showed that mitogen-activated protein kinase 4 (MAPK4) is a target of miR-7 in CD4+ T cells. Finally, the loss of MAPK4 could ameliorate the activation state of CD4+ T cells with or without miR-7 deficiency. Our studies document the important role of miR-7 in the setting of AIH induced by Concanavalin-A. Specifically, we provide evidence that the C/EBPα/miR-7 axis negatively controls CD4+ T-cell activation and function through MAPK4, thereby orchestrating experimental AIH in mice.
Conclusions: This study expands on the important role of miR-7 in liver-related diseases and reveals the value of the C/EBPα/miR-7 axis in CD4+ T-cell biological function for the pathogenesis of immune-mediated liver diseases.
© 2020 by the American Association for the Study of Liver Diseases.