中文摘要：

目的 探讨白细胞介素17A（IL-17A）在肺炎链球菌急性中耳炎（AOM）黏膜免疫中的作用。方法6～8周无特定病原体（SPF）级BALB/c小鼠,在感染前24 h腹腔注射200μg IL-17A抗体中和体内的IL-17A,注射相同剂量的Ig2a抗体作为对照组（Ig2a）,经鼓膜途径注射肺炎链球菌,感染后第5天取中耳灌洗液,酶联免疫吸附测定法（ELISA）检测IL-17A、CXCL2和CXCL5的水平。取中耳听泡,乙二胺四乙酸（EDTA）脱钙,常规石蜡切片,苏木素-伊红（HE）染色,评估中耳炎的严重程度。新型肺炎链球菌Psa A蛋白疫苗经鼻腔途径免疫小鼠,末次免疫后2周取小鼠的脾脏,制成细胞悬液,Psa A抗原刺激72 h,ELISA检测培养上清液IL-17A的水平;末次免疫后2周经鼓膜途径注射肺炎链球菌,攻毒后5 d取中耳灌洗液,ELISA检测IL-17A、CXCL2和CXCL5的水平。中耳攻毒后5 d取中耳黏膜,抽提RNA,反转录c DNA,荧光定量聚合酶链反应（PCR）检测IL-6、防御素β2和CXCL2 mRNA的表达水平。结果 在固有免疫中,中和体内的IL-17A,感染肺炎链球菌后,中耳有更严重的炎症反应,且中耳IL-17A、CXCL2和CXCL5分泌减少;在适应性免疫中,新型肺炎链球菌Psa A蛋白疫苗在CTB黏膜佐剂作用下经鼻腔途径免疫后,脾上清液分泌了较高水平的IL-17A,中耳攻毒后中耳黏膜灌洗液中检测到较高水平IL-17A,相关细胞因子CXCL2、CXCL5水平增高,中耳黏膜IL-6、防御素β2、CXCL2 mRNA表达量明显增高。结论 IL-17A在肺炎链球菌AOM黏膜免疫中起重要的保护作用,为AOM的治疗和新一代疫苗的设计及免疫策略的选择提供了实验依据。

英文摘要：

Objective To explore the role of interleukin-17A （IL-17A） in mucosal immunity against pneumocoecal acute otitis media （AOM）. Methods Twenty-four hours before infection with Streptococcus pneumoniae （SP） 200 pLg anti-murine IL-17A was administered intraperitoneally in BALB/c mice. As a control, 200 μg isotype matched rat IgG2a was used. Then, AOM in BALB/e mice was induced by the tympanic route. The degree of the inflammation in the middle ear was evaluated by hematoxyiin-eosin （HE） staining. The levels of CXCLS, CXCL2 and IL-17A in the SP-infected mice middle ear lavages （MEL） were measured by enzyme-linked inanunosorbent assay （ELISA）. PsaA protein was prepared as a new generation pneumococcal vaccine. BALB/e mice were immunized intranasally with PsaA/CTB, PsaA and CTB twice a week for 3 consecutive weeks. IL-17A level in splenocytes two weeks following the last immunization was determined by ELISA. The levels of IL-17A and related cytokine CXCL2, CXCL5 in MEL were also detected after challenge with type 14 SP following immunization. The exprssions of IL-6, defensin β2, CXCL2 mRNA in middle ear mueosa were detected by real-time reverse transeriptase polymerase chain reaction （RT-PCR）. Results After infection, the anti-IL-17-treated mice demonstrated a more severe otitis media compared with the IgG2a-treated mice. Compared with the IgG2a-treated SP-infected mice, the levels of CXCLS, CXCL2 and IL- 17A in the anti-IL-17-treated SP-infected mice were significantly lower. IL-17A level in spleen lymphocytes of mice immunized with PsaA/CTB was higher than that with PsaA alone. The higher level of IL-17A and related cytokine CXCL2, CXCL5 in MEL were also detected after challenge with type 14 SP following PsaA/CTB immunization. The IL-6, dafensin β2, CXCL2 mRNA expression was also significantly higher in the middle ear mucosa. Conclusions IL-17A plays an important protective role in mueosal immunity of pneumoeoccal AOM and provides the experimental basis for the treatment of AOM and the de