肺炎衣原体假定蛋白Cpn0423通过NOD2信号途径诱导炎症反应的作用机制

Objective To understand the biological activity of the hypothetical protein Cpn0423 of Chlamydia pneumoniae (Cpn) and the pathway by which it induces the inflammatory response of host cells. Methods The biological characteristics of Cpn0423 were preliminarily analyzed by bioinformatics software, and the subcellular localization of nucleotide - binding oligomerization domain - like receptor 2 (NOD2) in bone marrow - derived macrophages (BMDMs) was detected by laser confocal microscopy. The NOD2 - siRNA interference test was used to detect its inhibitory effect on the expression level of NOD2 in BMDMs cells. The macrophage inflammatory protein 2 (MIP - 2) and IL - 6 secreted by BMDMs cells induced by Cpn0423 were detected by ELISA, and the Cpn0423 DNA level in the bronchoalveolar lavage fluid (BALF) of Cpn - positive patients was detected by PCR. Results The homology between Cpn0423 and the effector proteins of the Chlamydia type III secretion system was 85% - 93%. NOD2 - siRNA could effectively inhibit the expression level of NOD2 mRNA in BMDMs cells. After NOD2 - siRNA interference, the levels of cytokines MIP - 2 [(920.5 ± 99.1) pg/ml vs (130.1 ± 11.5) pg/ml, P < 0.001] and IL - 6 [(266.2 ± 58.4) pg/ml vs (165.7 ± 21.5) pg/ml, P < 0.001] secreted by BMDMs cells induced by Cpn0423 were significantly decreased. The Cpn0423 DNA was positive in the BALF of 83.3% (10/12) of Cpn - positive patients, and no Cpn0423 DNA was detected in the control group. Conclusion Cpn0423 induces the host cell immune response through the NOD2 pathway and is closely related to the chronic inflammatory injury caused by Cpn in the body.

目的了解肺炎衣原体(Chlamydia pneumoniae,Cpn)假定蛋白Cpn0423的生物学活性及其诱导宿主细胞炎症反应的作用途径。方法生物信息学软件初步分析Cpn0423的生物学特性,激光共聚焦显微技术检测核苷酸结合寡聚化结构域样受体2(nucleotide-binding oligomerization domain- like receptor 2, NOD2)在骨髓源性的巨噬细胞(bone marrow-derived macrophages, BMDMs)中的亚细胞定位。采用NOD2-siRNA干扰试验检测其抑制BMDMs细胞中NOD2的表达水平,ELISA法检测Cpn0423诱导BMDMs细胞分泌的巨噬细胞炎性蛋白2(MIP-2)和IL-6,PCR法检测Cpn阳性患者支气管肺泡灌洗液(bronchoalveolar lavage fluid,BALF)中Cpn0423 DNA水平。结果Cpn0423与衣原体Ⅲ型分泌系统效应蛋白同源性为85% ~ 93%。NOD2-siRNA能有效抑制BMDMs细胞中NOD2 mRNA的表达水平。NOD2-siRNA干扰后,Cpn0423诱导BMDMs细胞分泌的细胞因子MIP-2 [(920.5 ±99.1) pg/ml vs (130.1±11.5) pg/ml,P<0.001]和IL-6 [(266.2±58.4) pg/ml vs (165.7±21.5) pg/ml,P<0.001]水平显著降低。83.3% (10/12)Cpn阳性患者BALF中Cpn0423 DNA为阳性,对照组未检出Cpn0423 DNA。结论Cpn0423通过NOD2途径诱导宿主细胞免疫应答,与Cpn引起机体慢性炎症损伤密切相关。