Met-RANTES干预实验性小鼠溃疡性结肠炎对MIP-3α及其受体CCR6的影响

Met-RANTES down-regulates the expression of MIP-3α and CCR6 in the colon of mice with experimental ulcerative colitis

目的:探讨MIP-3α及其受体CCR6在实验性小鼠溃疡性结肠炎(UC)发病中的作用,并分析Met-RANTES疗效机制.方法:用葡聚糖硫酸钠(DSS)诱导建立结肠炎小鼠模型,观察Met-RANTES对小鼠结肠炎病活动指数(DAI)、大体形态评分(GMS)、结肠组织学病理评分(HPS)的影响;并通过RT-PCR检测其对小鼠结肠组织MIP-3α、CCR6mRNA的表达变化及Westernblot和免疫组织化学方法检测其小鼠结肠组织MIP-3α、CCR6的蛋白表达变化.结果:DAI、GMS和HPS在DSS模型组和生理盐水治疗组中高于空白对照组,MIP-3α和CCR6在小鼠溃疡性结肠炎中表达上调,在小鼠空白对照组中不表达或弱阳性表达,差异有统计学意义(P<0.01);与DSS模型组和生理盐水治疗组相比,Met-RANTES治疗组小鼠DAI、GMS和HPS降低,MIP-3α和CCR6表达下调(mRNA:0.21±0.08vs1.09±0.08,1.08±0.07;0.25±0.08vs1.11±0.07,1.05±0.08,P<0.01;蛋白:0.28±0.08vs0.98±0.07,1.05±0.06;0.25±0.07vs1.19±0.07,1.15±0.06,P<0.01);生理盐水治疗组小鼠DAI、GMS和HPS以及MIP-3α和CCR6表达与DSS模型组相比表达无明显差异(P>0.05).结论:MIP-3α与CCR6参与了小鼠UC的发生、发展;Met-RANTES能下调MIP-3α及CCR6的表达,并能减轻炎症损伤;针对MIP-3α或CCR6的靶向治疗可能是UC一种有效的治疗方法.

AIM： To investigate the role of macrophage inflammatory protein-3α （MIP-3α） and chemokine receptor 6 （CCR6） in the pathogenesis of ulcerative colitis （UC） and to explore the mechanism of therapeutic effect of Met-RANTES against UC. METHODS： Forty mice were randomly and equally divided into four groups： blank control group, model control group, normal saline group, and Met-RANTES treatment group. Ulcerative colitis was induced in mice by givingdextran sodium sulfate （DSS）. The impact of Met-RANTES on disease activity index （DAI）, gross morphological score （GMS） and histopathological score （HPS） in UC was then evaluated. The expression of MIP-3α and CCR6 mRNAs was measured by reverse transcription-polymerase chain reaction （RT-PCR）. The expression of MIP-3α and CCR6 proteins was examined by Western blot and immunohistochemistry. RESULTS： The DAI, GMS and HPS were higher in the model control group and the normal saline group than in the blank control group. The expression levels of MIP-3α and CCR6 mRNAs and proteins in UC were significantly higher in the model control group and the normal saline group than in the blank control group （all P 0.01）. The DAI, GMS and HPS as well as the expression levels of MIP-3α and CCR6 mRNAs and proteins in the Met-RANTES treatment group were significantly lower than those in the model control group and the normal saline group （mRNA： 0.21 ± 0.08 vs 1.09 ± 0.08 and 1.08 ± 0.07, and 0.25 ± 0.08 vs 1.11 ± 0.07 and 1.05 ± 0.08; protein： 0.28 ± 0.08 vs 0.98 ± 0.07 and 1.05 ± 0.06, and 0.25 ± 0.07 vs 1.19 ± 0.07 and 1.15 ± 0.06; all P 0.01）. In contrast, no statistical differences were noted in DAI, GMS and HPS as well as the expression levels of MIP-3α and CCR6 mRNAs and proteins between the model control group and the normal saline group （all P 0.05）. CONCLUSION： The expression of MIP-3α and its receptor CCR6 is up-regulated in UC, which is closely related with the development and progression of UC. Met-RANTES can down-regulate the expression of MIP-3α and CCR6 and ameliorate inflammatory damage in mice with UC. MIP-3α and CCR6 may represent novel pharmacological targets for treatment of UC.