Protective effect of platycodin D on liver injury in alloxan-induced diabetic mice via regulation of Treg/Th17 balance.

Abstract

Platycodin D is a major pharmacological constituent of Platycodi Radix with immunomodulatory activity. The present study was designed to investigate how platycodin D (PLD) reveals liver injury in diabetic mice and its mechanism. Fifty mice were divided into five groups randomly: control group, model group, rosiglitazone (ROG, 10 mg/kg) group, PLD (50 mg/kg) group, and PLD (100 mg/kg) group. Diabetes was induced with the injection of alloxan monohydrate (150 mg/kg) subcutaneously, and animals with blood glucose level of ≥250 mg/dl were considered as diabetic mice. After the first day of diabetes induction, the treatments were performed for 8 weeks. Then the animals were anaesthetized, and blood and liver samples were also collected for further assay. PLD significantly decreased the serum levels of glucose, insulin, interleukin-6 (IL-6), interleukin-1β, tumor necrosis factor-α (TNF-α), and interleukin (IL)-17A and increased IL-10 level in serum. PLD effectively downregulated aspartate transaminase (AST), alanine aminotransferase (ALT), total cholesterol (TC), and triglycerides (TG) in liver. PLD also attenuated liver histological change. In addition, PLD significantly attenuated IL-17A and IL-10 levels in vitro, flow cytometry (FCM) studies also showed that PLD remarkably inhibited Th17 cells and significantly increased Treg cells in liver tissues and spleen cells. Western blot demonstrated PLD inhibited the phosphorylation of JAK and STAT-3 and the expression of RORγt and increased the expression of Foxp3. The findings showed that PLD exerts beneficial effects on alloxan-induced liver injury in mice.