CCR5第一、二胞外环特异性结合的拮抗短肽对TNBS诱导SD大鼠结肠炎的治疗作用

目的:研究C-C趋化因子受体5(CCR5)膜外第一、二胞外环(ECL1和ECL2)特异性结合的拮抗短肽对三硝基苯磺酸(TNBS)诱导的结肠炎模型大鼠的治疗作用与机制。方法:采用100 mg/kg TNBS诱导结肠炎SD大鼠模型;用不同剂量的2条拮抗短肽(ECL1:25、35和45 mg/kg;ECL2:15、25和35 mg/kg)分别作用于模型大鼠,观察其对大鼠疾病活动指数(DAI)、结肠大体损伤指数(CMDI)和组织病理学改变的影响,采用real-time PCR和Western blot法分别检测结肠组织TNF-α和COX-2的mRNA与蛋白表达水平。结果:与模型组相比,有效剂量的ECL2拮抗短肽HY治疗组大鼠疾病活动程度、肠道溃疡及病理组织学损伤均有明显减轻,各评分指数差异具有统计学意义(P0.05);TNF-α和COX-2的蛋白和mRNA表达水平均明显下降(P0.05)。ECL1拮抗短肽GH作用的大鼠结肠炎症状评分及TNF-α和COX-2炎症因子表达无明显改变。结论:ECL2拮抗短肽可能通过下调结肠黏膜TNF-α和COX-2的表达来缓解TNBS诱导的SD大鼠结肠炎,而ECL1拮抗短肽的作用不明显。

Effects of antagonistic peptides binding specifically with first and second extracellular loops of CCR5 on colitis rats induced by TNBS

AIM: To study the effects of antagonistic peptides binding specifically with the first and second extracellular loops (ECL1 and ECL2) of C-C chemokine receptor 5 (CCR5) on the colitis rats induced by trinitrobenzenesulfonic acid (TNBS) and the mechanisms.METHODS: The colitis model of SD rats was induced by TNBS (100 mg/kg). The effects of 2 antagonistic peptides at different doses (ECL1:25, 35 and 45 mg/kg; ECL2:15, 25 and 35 mg/kg) on the model rats including the changes of disease activity index (DAI), colon macroscopic damage index (CMDI) and histological grading were observed. The mRNA and protein expression levels of TNF-α and COX-2 in the colonic mucosa were detected by real-time PCR and Western blot, respectively.RESULTS: Compared with model group, the changes of DAI, CMDI and histopathological injury of the rats treated with ECL2 antagonistic peptide HY at an appropriate dose were significantly reduced (P<0.05), and the protein and mRNA expression levels of TNF-α and COX-2 were significantly decreased (P<0.05). However, the effects of ECL1 antagonistic peptide GH on all scores and the expression levels of TNF-α and COX-2 were not obvious.CONCLUSION: ECL2 antagonistic peptide HY relieves TNBS-induced colitis in SD rats via down-regulating the expressions of TNF-α and COX-2 in the colonic mucosa, while the effect of ECL1 antagonist peptide GH was not obvious.