创伤弧菌溶细胞素融合蛋白对人Caeo-2细胞IL-8基因表达和IL-8分泌的影响

Study on transcription and expression of IL-8 in human Caco-2 cells induced by VvhA recombinant protein

目的研究创伤弧菌溶细胞素融合蛋白（rVvhA）对人肠上皮细胞（human intestinal epithelial cell，Caco-2）IL-8基因表达的影响。方法IPTG诱导、表达、纯化、复性及Western blot鉴定rVvhA表达和纯化情况；CCK-8法检测rVvhA对Caco-2的细胞毒性作用；RT—PCR检测rVvhA诱导Caco-2细胞IL-8基因的表达情况；ELISA检测Caco-2细胞培养上清IL-8的分泌情况。结果Ni^2＋-NTA亲和层析柱对rVvhA进行纯化后纯度可达95％以上；CCK-8结果显示rVvhA活性蛋白显著降低了Caco-2细胞的存活率，有效浓度为1．5HU／ml（P〈0．05）；RT—PCR结果显示，0．6HU／ml rVvhA 30 min即可诱导Caco-2细胞IL-8mRNA基因表达上调；ELISA结果显示，Caco-2细胞经rVvhA作用后，培养液上清中IL-8多肽的表达时相在4h。RT—PCR与ELISA结果皆显示，IL-8基因的转录及IL-8表达皆具有时间-剂量依赖性。结论rVvhA在转录水平上能诱导人Caco-2细胞IL-8 mRNA表达，促进IL-8的合成，在创伤弧菌引起的过度炎症反应和败血症的发生、发展中可能具有重要意义。

Objective To investigate the effect of VvhA recombinant protein to the expression of IL-8 in human intestinal epithelial Caco-2 cells. Methods The VvhA recombinant protein（rVvhA） was expressed by prokaryotic expression vector pET-28a （ ＋ ）-vvhA in E. coli BL21 （DE3） , purified by Ni^2＋- NTA affinity chromatography refolded by stepwise deliquation together with dialysis methods and identified by Western blot. The cytotoxic of rVvhA to human Caco-2 cells was measured by CCK-8. The transcription of IL-8 mRNA in human Caco-2 cells induced by rVvhA was determined by RT-PCR, and the expression of IL- 8 in human Caco-2 cells induced by rVvhA was determined by ELISA assay. Results rVvhA was purified with high purity up to 95%. The viability of human Caco-2 ceils treated with 1.5 HU/ml rVvhA was inhibited significantly （P 〈 0.05）. The rVvhA can induce human Caco-2 cells to increase the transcription and expression of IL-8 in dose- and time-dependent manner. The transcription of IL-8 gene in human Caco-2 cells treated with 0.6 HU/ml rVvhA in 30 rain can be up-regulated significantly, and the expression of IL-8 in human Caco-2 cells treated with rVvhA in 4 h can be increased significantly. Conclusion rVvhA has cytotoxic to human Caco-2 and can increase the expression of IL-8, it might play a major role in the inflammatory reaction of rVvhA-exposed cells.