Protective effects of Punica granatum (pomegranate) peel extract on concanavalin A-induced autoimmune hepatitis in mice

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease of an unknown etiology, glucocorticoid therapy is currently recognized as an effective treatment for AIH, but conventional application and patient compliance are both hindered by its side effects. The exploration of the AIH pathogenesis and the searching for the new candidate drugs that exert potential activity and low toxicity are urgently needed. Pomegranate peel extract (PoPx) is a natural extract of Punica granatum and has been reported to have anti-inflammatory and antioxidative properties. The present study aimed to clarify the effect of PoPx on the concanavalin A (ConA)induced autoimmune hepatitis in a mouse model that is well established at 12h after tail vein injection with a dose of 20 mg/kg of ConA. C57BL/6 female mice were pretreated with PoPx (250 mg/kg, once daily for 3 days) followed by a ConA challenge. Pretreatment with PoPx significantly alleviated ConA-induced liver injury by down-regulating the levels of plasma alanine transaminase (ALT), aspartate transaminase (AST) and cytokine, including TNF-alpha, interferon (IFN) -gamma and interleukin (IL)-6. Moreover, liver hematoxylin and eosin (H&E) staining displayed a lighter inflammatory infiltration around the portal area in the PoPx-pretreated mice. In addition, the flow cytometry (FCM) data showed that the immune response in the liver was died down in the PoPx-pretreated condition. Specially, pretreatment with PoPx reduced the infiltration of activated CD4(+) and CD8(+) T cells in the liver. Taken together, these findings contributed to a better understanding of the actions of PoPx against acute AIH and indicated that PoPx might be a potential compound in treating T cell-mediated autoimmune liver injury.