白细胞介素-1受体相关激酶1蛋白过表达对细菌脂蛋白耐受的影响

The influence of over expression of interleukin-1 receptor-associated kinase 1 on bacterial lipoprotein-induced tolerance

目的探讨细菌脂蛋白（BLP）信号转导分子Toll样受体2（TLR2）和白细胞介素-1受体相关激酶1（IRAK-1）与BLP耐受发生的关系。方法在人胚肾293（HEK293）细胞中过表达TLR2以及IRAK-1蛋白，利用蛋白质免疫印迹法和双荧光素酶报告基因检测实验观察其对BLP耐受的影响。结果以BLP刺激稳定转染并表达TLR2的HEK293细胞可以剂量依赖性地诱导NF—xB活化，而且BLP预处理HEK—TLR2细胞可诱导BI，P耐受的发生。在HEK—TLR2细胞中过表达IRAK-1可以剂量依赖性地增加NF—KB的活化并逆转BLP耐受：转染前BLP活化组与耐受组的NF—κB活化程度分别为0．3294±0．010和0．168±0．010；转染0．02／μgIRAK-1质粒后活化组与耐受组的NF—κB活化程度分别为0．493±0．010和0．427±0．035，均比转染前明显升高，差异均有统计学意义（均P〈0．01）。结论HEK293细胞中过表达TLR2不能阻止BLP耐受的诱导，但是在HEK—TLR2细胞中过表达IRAK-1可部分逆转BLP耐受，提示IRAK-1蛋白表达水平的变化在BLP耐受发生中起关键作用；IRAK-1可作为细菌感染和脓毒症治疗的重要靶点。

Objective To investigate Toll-like receptor 2 （TLR2） and interleukin-1 receptor- associated kinase 1 （IRAK-1） in bacterial lipoprotein （BLP） tolerance. Methods Western blotting was used to confirm the over expression of TLR2 and IRAK-1 in human embryo kidney 293 （HEK293） cells. Plasmids for dual luciferase reporter gene with nuclear factor-κB promoter （pNF-κB-Luc） or CMV promoter （phRL-CMV internal control vector） were used to detect the NF-κB activation and the induction of BLP tolerance in HEK-TLR2 ceils. Results BLP stimulation resuhed in dose-dependent NF-κB activation in HEK293 cells stably expressing TLR2. And BLP pretreatment could reduce NF-κB activation and induce BLP tolerance in HEK-TLR2 cells. The NF-κB activation was 0. 329±0. 010 and 0. 168±0. 010 in BLP-activated and BLP-tolerant HEK-TLR2 cells, respectively. After transfection with 0.02 μg IRAK-1 plasmid, NF-κB activation in the two groups was 0. 493±0. 010 and 0. 427±0. 035, respectively （both P〈0.01）. So over expression of IRAK-1 could increase NF-κB activation in a dose-dependent manner. Conclusion These results demonstrated that over expression of IRAK-1 could reverse BLP tolerance, whereas over expression of TLR2 failed to prevent the induction of BLP tolerance. Therefore reduced IRAK-1 protein expression is an important mechanism in the development of BLP-induced tolerance, suggesting that it could be a potentially important target for future therapeutic strategies in bacterial infection and sepsis.