TLRs和CLRs对烟曲霉刺激肺泡上皮细胞调节肺泡巨噬细胞极化的影响机制

Invasive pulmonary aspergillosis is caused by Aspergillus fumigatus invading people with low immunity. In recent years, its incidence has increased dramatically, becoming a common infectious disease in clinically second only to Candida albicans infection. The alveolar epithelial barrier plays a very important role in resisting Aspergillus fumigatus infection. The polarization of alveolar macrophages is closely related to the progression and outcome of infection, but whether its polarization is affected by infected alveolar epithelial cells is unknown. In the early stage, we detected the expression of IFN-γ in the alveolar lavage fluid of mice with invasive pulmonary aspergillosis, while the expression of IL-4 was low, and the cytokines TNF-α, IL-12 and iNOS were highly expressed. It is suggested that M1 macrophage polarization may exist in the alveoli of invasive pulmonary aspergillosis, and it is unclear whether this phenomenon is induced by alveolar epithelial cells endocytosed by Aspergillus fumigatus. Whether the immune response is regulated by TLRs and CLRs is also unclear. This experiment is intended to explore the mechanism of the immune response of alveolar epithelial cells endocytosed by Aspergillus fumigatus by molecular biology, and the effects of microenvironment changes on the polarization of alveolar macrophages, further reveal the regulation of TLRs and CLRs mechanism. To provide a new experimental basis for further exploration of the pathogenic mechanism of Aspergillus fumigatus.

侵袭性肺曲霉病由烟曲霉侵袭免疫力低下人群所致。近年来其发病率急剧增加，成为临床上仅次于白假丝酵母感染的常见感染性疾病。肺泡上皮屏障在抵御烟曲霉感染的过程中，起了非常重要的作用。其中肺泡巨噬细胞的极化与感染的进展和转归关系密切，但其极化是否受感染的肺泡上皮细胞影响尚属未知。我们前期通过检测侵袭性肺曲霉病小鼠肺泡灌洗液发现，IFN-γ表达量升高，而IL-4呈低表达，促炎因子TNF-α、IL-12及iNOS均呈高表达，提示侵袭性肺曲霉病肺泡内可能存在M1型巨噬细胞极化，而该现象是否由内吞了烟曲霉的肺泡上皮细胞诱导尚不清楚。其免疫应答是否是通过TLRs和CLRs蛋白家族调控也尚不清楚。本实验拟通过分子生物学手段，探讨内吞了烟曲霉的肺泡上皮细胞发生免疫应答的机制，及其导致的微环境变化对肺泡巨噬细胞极化的影响，进一步揭示TLRs和CLRs蛋白家族调控机制。为进一步探讨烟曲霉的致病机制提供新的实验依据。

侵袭性肺曲霉病(Invasive pulmonary aspergillosis, IPA）即由烟曲霉 (Aspergillus fumigatus, Af)孢子，通过呼吸系统侵入免疫受损人群，引发的严重且往往是致死性的肺部疾病。近年来，由于广谱抗生素、抗癌药物、免疫抑制剂的泛用，侵入性诊疗技术、器官移植的广泛开展，艾滋病患者的不断增多，人口老龄化等原因，IPA的发病率急剧增加，已成为临床上仅次于白假丝酵母(Candida albicans)感染的常见真菌感染性疾病，并且病程进展迅速，诊断困难、预后差，非治疗患者死亡率＞90%。烟曲霉作为一种空气中、无处不在的机会性致病真菌，其很少在免疫机制正常的个体中引起感染。功能完善的先天性免疫系统，在预防烟曲霉菌感染方面起着至关重要的作用。故开展机体抵御烟曲霉感染的免疫反应机制研究，探索预防和治疗烟曲霉感染的新措施，对于降低IPA发病率和病死率，具有十分重要的意义。肺泡上皮屏障是烟曲霉感染肺脏的初级屏障，本项目首次探讨了烟曲霉侵袭肺泡上皮细胞后，诱导肺泡巨噬细胞极化在侵袭性肺曲霉病发病中的作用，发现其可以诱导肺泡巨噬细胞M1极化。同时，将肺泡上皮细胞诱导肺泡巨噬细胞极化和机体免疫应答关联起来，发现其可以激发机体免疫应答。并且联系前期工作，进一步探讨TLRs和CLRs蛋白家族在肺泡上皮细胞诱导肺泡巨噬细胞极化中的作用机制。比较了预萌发孢子和静默孢子的侵袭性，并探讨了烟曲霉孢子通过气血屏障的机制，为研究侵袭性肺曲霉病的发病机制，开拓了新思路。