Brusatol-enriched Brucea Javanica Oil Ameliorated Dextran Sulfate Sodium-induced Colitis in Mice: Involvement of NF-κB and RhoA/ROCK Signaling Pathways

Abstract

Background: Our previous study indicates that Brucea javanica oil (BJO) is beneficial for treatment of ulcerative colitis (UC), and that quassinoids in particular brusatol are bioactive components. However, it is still uncertain whether or not other components in BJO, such as oleic acid and fatty acids, have anti-UC effect.Purpose: The present study aimed to compare the anti-UC effects between brusatol-enriched BJO (BE-BJO) and brusatol-free BJO (BF-BJO), and to explore the effects and mechanisms of BE-BJO on colon inflammation and intestinal epithelial barrier function.Methods: Balb/C mice received 3% (wt/vol) DSS for one weeks to establish the UC model. Different doses of BE-BJO, BF-BJO or BJO were treated. Body weight and colon length were measured. Disease activity index (DAI) and histological analysis were evaluated. The levels of pro-inflammatory cytokines in the colon tissues were measured by enzyme linked immunosorbent assay (ELISA). The expressions of tight junction proteins were tested to investigate the intestinal epithelial barrier function. The effects of BE-BJO on NF-κB and RhoA/ROCK pathways were studied.Results: BE-BJO alleviated DSS-induced loss of body weight, increase of DAI and shortening of colon, whereas BF-BJO did not have these protective effects. BE-BJO treatment improved the morphology of colon tissue, inhibited the production and release of pro-inflammatory cytokines including TNF-α、 IFN-γ、 IL-6 and IL-1β in the colon tissue, as well as reversed the decreased expressions of ZO-1, Occludin, Claudin-1and E-cadherin induced by DSS, but augmented Claudin-2 expression. Mechanistically, BE-BJO repressed phosphorylation of NF-κB subunit p65, suppressed RhoA activation, downregulated ROCK, and prevented phosphorylation of myosin light chain (MLC) in DSS-treated mice.Conclusions: This work demonstrated that BE-BJO could ameliorate DSS-induced UC by preventing colon inflammation and enhancing intestinal epithelial barrier function, probably via suppression of NF-κB and RhoA/ROCK signaling pathways. These findings confirm that quassinoids are active compounds from BJO and suggest the therapeutic potential of quassinoids and BE-BJO in the treatment of UC.