IL-12和IL-23在衣原体致肾脏病变中的作用及其机制研究

Chlamydia trachomatis is the most common bacterial sexually transmitted infection pathogen, which potentially cause serious complications, such as tubal factor infertility, pelvic inflammatory disease and ectopic pregnancy, and it also can induce upper urinary tract diseases. However, the pathogenic mechanisms of C. trachomatis-induced diseases remain unknown, and there is still no licensed anti-C. trachomatis vaccine. CD4+ Th1 cell-mediated immunity has been identified as a major protective mechanism to control chlamydial infection. Interleukin-12 (IL-12) is an essential inflammatory cytokine for the development of Th1 T cell immunity, which consists of a p35 and p40 subunit. In the preliminary studies, we unexpectedly found that IL-12p35 KO (knockout) and IL-12p40 KO mice showed severe kidney pathology and more chlamydial organisms were detected in the kidney tissues after intravaginally infected with C.muridarum (Cm）, which indicate that IL-12 and IL-23 may play important roles in controlling chlamydia spreading to distal organs and inducing renal lesions. Based on these foundation, we plan to do the following studies: firstly, to make sure IL-12 or IL-23 is the sensitive factor in chlamydial kidney diseases by immunoblockade treatments with neutralized monoclone antibodies to corresponding cytokines and immunotherapy experiments with recombinant cytokines. Secondly, to reveal the way(s) through which intravaginal chlamydia spreads to kidney. Finally, to analyze the role of flora disequilibrium played in kidney lesion introduced by chlamydia. The expected results of this study may not only benefit for better realization of chlamydial pathogenesis and developing anti-Chlamydia vaccines, and bring new understandings of chlamydial pathogenicity, but also provide references for clinical judgement the susceptible population and the development of corresponding prevention and treatment measures of chlamydial kidney diseases.

Ct是全球细菌性性传播疾病最常见的病原体。抗Ct免疫以CD4+ Th1细胞免疫为主，IL-12是重要的Th1型细胞因子。本课题组前期研究发现IL-12p35 KO和IL-12p40 KO小鼠生殖道感染衣原体后导致严重的肾脏病变，表明IL-12和IL-23在衣原体致肾脏病变中具有重要作用，但具体机制不明。本课题拟用IL-12p35 KO、p40 KO和wt小鼠建立衣原体泌尿生殖道感染模型，通过免疫阻断和免疫治疗实验，明确IL-12和IL-23是否为衣原体致肾脏病变的关键因子；体内试验分析衣原体进入肾脏的途径；PCR-DGGE分析阴道微生物多样性，探讨泌尿生殖道微生态失衡在衣原体致肾脏病变中的作用。预期结果不仅有助于阐明衣原体致病机制，还有助于临床判断衣原体性肾病易感人群及制定相应的防治策略。

本课题组前期研究发现IL-12和IL-23可能在衣原体致肾脏病变中具有重要作用，为进一步论证IL-12和IL-23为衣原体致肾脏病变的关键细胞因子，并探究生殖道感染的衣原体如何进入肾脏致病，我们开展了一系列实验。首先用鼠衣原体（Chlamydia. muridarum，Cm）经阴道感染wt、IL-12p35 KO和IL-12p40 KO 小鼠，感染后45天，肺、肝、脾、心脏组织中均未检出活的衣原体；而在肾脏、尿道、膀胱组织中，wt小鼠三种组织中均未检出活的衣原体，但IL-12p35 KO和IL-12p40 KO 小鼠均有较高的检出率，一直持续到感染后100天；并且IL-12p35 KO和IL-12p40 KO小鼠肾脏、尿道、膀胱组织出现严重的病变，其病变程度与肾脏的病变程度成正相关。由此推断，衣原体经生殖道感染引起肾脏病变最可能的途径是经泌尿道上行感染。.为确定IL-12或IL-23是衣原体引起肾脏病变的关键细胞因子，进行了重组IL-12和IL-23治疗试验和IL-12和IL-23抗体阻断试验。注射重组IL-12的IL-12p35 KO小鼠，与未治疗小鼠相比，生殖道带菌数量虽有所下降，但差异无统计学意义，肾脏病变程度也没很大改善；而用IL-12和IL-23治疗的IL-12p40 KO小鼠，从感染后28天开始，生殖道带菌数量和肾脏病变程度均显著低于未治疗小鼠，且由抗体类型和脾细胞产生的IFN-γ水平可见，经重组IL-12和IL-23治疗后，IL-12p40 KO小鼠有Th2型为主的免疫应答转变为Th1型应答为主。感染衣原体的wt小鼠，注射抗IL-12和抗IL-23单克隆抗体后生殖道带菌时间明显延长，肾脏出现明显病变，且使Th2 型抗体IgG1滴度明显增高，也使脾细胞产生的IFN-γ减少。由此可见，IL-12和IL-23在衣原体引起肾脏病变过程中发挥重要的作用。