The role of invariant natural killer T cells and associated immunoregulatory factors in triptolide-induced cholestatic liver injury

Abstract: Proinflammatory cytokines are potent inhibitors of bile acid nuclear receptors and transporters. Triptolide (TP), an active ingredient of Tripterygium wilfordii Hook.f., exhibits unique efficacy for autoimmune diseases and tumors. While its clinical application is greatly constrained by hepatotoxicity. Therefore, we explored the mechanism of iNKT cells and associated immunoregulators in TP-induced cholestatic liver injury. TP was administered to both female C57BL/6 mice and Jα18-/- mice. INKT cells released significantly increased Th2 cytokine IL-4 in C57BL/6 mice after TP administration. Blood biochemistry, histopathology and immunohistochemistry demonstrated that TP-induced cholestasis liver injury. In Jα18-/- mice, cholestatic liver damage was alleviated due to the upregulation of type 2 NKT cells, nuclear receptor FXR, transporter OATP1B2 and CYP450, but also the downregulation of Cxcl10, ICAM-1 and Egr-1. Above results suggested that Th2 cytokines produced by iNKT cells suppressed type 2 NKT cells and promoted the expression of immunoregulatory factors represented by CXCL10, ICAM-1 and Egr-1, which in turn affected cholestasis-related nuclear receptor, transporter and enzymes, thus aggravated cholestatic liver injury. Our research contributes to better understanding of the role of iNKT cells in TP-induced cholestatic liver injury, thereby providing potential therapeutic targets for clinical prevention and treatment.