Original article Effect of homocysteine on intestinal permeability in rats with experimental colitis, and its mechanism

detection of the activity of myeloperoxidase (MPO) and the contents of MDA, IL-1b, IL-6, TNF-a, MMP-2, and MMP-9. Intestinal epithelial permeability was assessed with Evans blue (EB) dye. The levels of Hcy in plasma and colon mucosa were measured by high-performance liquid chromatography-fluorescence detection (HPLC-FD). Results: Compared with the normal group, the DAI scoring and MPO activity, contents of MDA, IL-1b, IL-6, TNF-a, MMP-2, MMP-9 in the colon and EB in the small intestine were significantly increased in the TNBS group (P < 0.01). Compared with the TNBS model group, the DAI scoring, plasma and colonic mucosa Hcy levels, MPO activity and contents of MDA, IL-1b, IL-6, TNF-a, MMP-2, MMP-9 in colon and EB in small intestine were significantly increased in the TNBS-induced colitis rats with simultaneous Hcy injection (P < 0.01). Conclusion: Hcy can increase intestinal permeability and aggravate inflammatory damage in rats with TNBS-induced colitis, the underlying mechanisms of which may be attributed to its effects of promoting the expression of MMP-2 and MMP-9, leading to injury of the intestinal barrier.