Ferulic acid ameliorates TNBS-induced ulcerative colitis through modulation of cytokines, oxidative stress, iNOs, COX-2, and apoptosis in laboratory rats

Ulcerative colitis (UC) is a chronic immune-inflammatory disorder characterized by oxido-nitrosative stress, the release of pro-inflammatory cytokines and apoptosis. Ferulic acid (FA), a phenolic compound is considered to possess potent antioxidant, anti-apoptotic and anti-inflammatory activities. The aim is to evaluate possible mechanism of action of FA against trinitrobenzensulfonic acid (TNBS) induced ulcerative colitis (UC) in rats. UC was induced in Sprague-Dawley rats (150-200 g) by intrarectal administration of TNBS (100 mg/kg). FA was administered (10, 20 and 40 mg/kg, p.o.) for 14 days after colitis was induced. Various biochemical, molecular and histological changes were assessed in the colon. Intrarectal administration of TNBS caused significant induction of ulcer in the colon with an elevation of oxido-nitrosative stress, myeloperoxidase and hydroxyproline activity in the colon. Administration of FA (20 and 40 mg/kg) significantly decrease oxido-nitrosative stress, myeloperoxidase, and hydroxyproline activities. Up-regulated mRNA expression of TNF-α, IL-1β, IL-6, COX-2, and iNOs, as well as down-regulated IL-10 mRNA expressions after TNBS administration, were significantly inhibited by FA (20 and 40 mg/kg) treatment. Flow cytometric analysis revealed that intrarectal administration of TNBS-induced significantly enhanced the colonic apoptosis whereas administration of FA (20 and 40 mg/kg) significantly restored the elevated apoptosis. FA administration also significantly restored the histopathological aberration induced by TNBS. The findings of the present study demonstrated that FA ameliorates TNBS-induced colitis via inhibition of oxido-nitrosative stress, apoptosis, proinflammatory cytokines production, and down- regulation of COX-2 synthesis.Graphical Abstract: TNBS caused activation of T cells which interact with CD40 on antigen presenting cells i.e. dendritic cells (DC) that induce the key Interleukin 12 (IL-12)-mediated Th1 T cell immune inflammatory response. It releases interferon-γ (IFN-γ), which in turn induces macrophages (MAC) to produce TNF-α and other pro-inflammatory cytokines (e.g., IL-1β, IL-6). This inflammatory influx resulted in induction of ulcerative colitis (UC). Administration of FA may inhibit this IFN-γ induced inflammatory cascade via a decrease in the release of pro-inflammatory cytokines to ameliorate TNBS-induced colitis.