Oral Administration of Piperine Ameliorates Experimental Autoimmune Uveitis.

Abstract

This study aimed to evaluate the impact of piperine on experimental autoimmune uveitis (EAU). EAU was induced by immunization with interphotoreceptor retinoid-binding protein emulsified in complete Freund adjuvant. Starting from day 8 post-induction, Lewis rats were given piperine (0, 20, 40, and 80 mg/kg-P.O.) or prednisolone (10 mg/kg-P.O.) for 18 consecutive days. The 80 mg/kg dose of piperine demonstrated superior regression of clinical symptoms, increased nitric oxide levels, and enhanced IDO activity in eye homogenates compared to other doses. The 40 and 80 mg/kg doses of piperine were more effective in promoting weight gain in EAU rats than the 20 mg/kg dose. EAU rats treated with 80 mg/kg piperine showed more favorable mRNA expression of IL-10 and TGF-β in their eyes than other treatment groups. The interventions led to a significant decrease in mRNA ratios of T-bet/GATA-3, RORγt/T-bet, RORγt/Foxp3, and RORγt/GATA-3 in the eyes of EAU rats compared to untreated EAU rats. Specifically, EAU rats treated with 80 mg/kg piperine exhibited a greater reduction in the mRNA ratio of RORγt/Foxp3 expression compared to other treatment groups. Overall, oral administration of piperine may offer potential for clinical application in uveitis.