3.2 TBⅡ prevented DSS-induced disruption of colonic epithelial integrity and attenuated DSS-induced inflammation of colon tissue
One of the key features of DSS-induced colitis is the disruption of colonic epithelial integrity and intestinal barrier homeostasis, and thereby causing enhancing intestinal permeability and colonic and systemic inflammatory infiltration. Given the alleviative effect of TBⅡ in DSS-induced colitis, we then examine whether TBⅡ can ameliorate DSS-induced the damage of colonic epithelial integrity. We demonstrated a significant increase in intestinal permeability of FITC-dextran in DSS-induced colitis mice compared with control mice, an effect that is reduced by TBⅡ treatment (Figure 2A). Accordingly, the expression of genes (such as E-cadherin and Occludin ) involved in colonic tight junctions and adhesive junctions was increased after TBⅡ treatment (Figure 2B). Consistently, the protein expression levels of E-cadherin and Occludin determined by western blot, and immunofluorescence were also elevated (Figure 2C and D).
Importantly, TBⅡ treatment also substantially diminished colonic inflammatory infiltration, as revealed by reduced F4/80+ positive cell recruitment to the colon tissue and lower levels of MPO activity in plasma and colon tissue (Figure 2D and E), a marker of inflammatory infiltration into the inflamed colon tissue, and subsequently leading to abating colonic inflammation, as seen by a decrease of pro-inflammatory cytokine release (TNF-α, IL-1β, IL-6 and IL-10) (Figure 2F). Correspondingly, the expression of genes associated colonic inflammation including TNF-α, IL-1β, IL-6 andIL-10 were prominently reversed in TBⅡ-treated colitis mice than that of vehicle-treated DSS-induced colitis mice (Figure 2G). Collectively, our results demonstrated that TBⅡ can alleviate DSS-induced the disruption of colonic epithelial integrity via reducing intestinal permeability and inflammatory infiltration.