Changes of intestinal macrophage subsets at different stages in mice of inflammatory bowel disease / 中华实用儿科临床杂志

ABSTRACT

Objective:To establish a mice model of inflammatory bowel disease (IBD) induced by dextran sulfate sodium (DSS), and to analyze the changes in intestinal inflammation and macrophage subsets at different stages, so as to find a new target for the treatment of IBD.Methods:Thirty male C57BL/6 mice of 6-8 weeks were randomly divided into control group, activation stage group and resolution stage group.The latter 2 groups were given 25 g/L DSS for 5 consecutive days to establish the IBD model.After 5 days, the mice were given filtered and sterilized water and sacrificed on the 10 th and 15 th day, respectively.Colon inflammation in mice was evaluated, including body weight, disease activity index (DAI) score, changes in colon length, histopathology and histopathological score.Then the expression levels of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β in colon tissues were detected by quantitative real-time PCR(qPCR). Finally, the changes of intestinal macrophage subsets were detected by flow cytometry. Results:The colon inflammation of mice in the activation stage group was significantly more severe than that in the control group, while the colon inflammation of mice in the resolution stage group was reduced.The colon length of mice in the activation stage group was (5.94±0.40) cm, which was significantly shorter than that in the control group [(7.25±0.29) cm], and the situation was slightly improved in the resolution stage with the colon length of [(6.87±0.95) cm], and the differences were statistically significant (all P<0.05). The mRNA expression levels of pro-inflammatory cytokines IL-1β, IL-6 and TNF-α in the activation stage were 53.40±6.58, 117.69±30.78 and 2.52±0.25, respectively, which were significantly higher than those in the control group (1.00±0.13, 1.00±0.39, 1.00±0.10); the mRNA expression levels of IL-1β, IL-6 and TNF-α in the resolution stage were 2.51±0.13, 5.43±0.51 and 1.73±0.14, respectively, which were significantly lower than those in the activation stages(all P<0.05). The expression level of anti-inflammatory cytokine TGF-β in the resolution stage was 2.41±0.17, which was significantly higher than that in the activation stage (0.94±0.12), and the diffe-rence was statistically significant ( P<0.05). During the progression of IBD, there were 3 groups of macrophages in the lamina propria of intestinal mucosa of mice, of which the number of F4/80 lowCD 64-MHCⅡ - macrophage subset with the lowest maturity increased significantly in the activation stage of IBD, accounting for (10.68±4.62)%, and it decreased and returned to the normal level in the resolution stage, accounting for (4.63±1.06)%, and the difference was statistically significant ( P<0.05). Conclusions:Macrophages play an important role in the progression of IBD, the hindrance of maturation and development may be the main cause of inflammatory injury in the activation stage of IBD, and the transformation of macrophage subsets may become a new target for the treatment of IBD.