IL-10/IL-10R负调控嗜碱性粒细胞及其在过敏性气道炎症中的作用研究

Allergic asthma is an immunological disorders characterised by Th2 dominant immune response. Understanding immunological tolerance is an important step towards developing new therapies. Interaction between antigen presenting cell(APCs) and T cell is the first step to initiate a Th2 immune response. it's important to study the mechanisms how tolerant APCs is induced. It was reported that IL-10/1L-10R pathway are one of most important way to induce tolerance by inhibiting the antigen presenting function of dendritic cells(DCs) via upregulation of SHIP-1. DCs were regarded as initiator of Th2 immune response for a long time, however it's not capable of polarizing Th2 cells in vitro study without exogenous IL-4. Recent studies revealed that basophils can act as APCs and are able to induce Th2 cell differentiation without exogenous IL-4 both in vitro and in vivo which also proved by our previuos study.It was reported that SHIP-1 can negative regulate basophil function,thus it could be the new target to induce immunologic tolerance. By now, there is no report about IL-10/1L-10R pathway in regulation of basophil.Our primary data revealed that basophil express IL-10R,and in vitro treatment of IL-10 can inhibit basophil from uptaking OVA-FITC. Based on the above observations, We assume that IL-10/1L-10R pathway can negative regulate basophil which leading to the suppression of Th2 immune response. In order to support our postulation, we will study the possible role of IL-10/1L-10R pathway in regulation the function of basophil and the cellular signaling underneath by blocking or activating this pathway and It will further extend the knowledge of the immunologic mechanisms of asthma

过敏性哮喘是机体对变应原产生过度Th2免疫应答，由抗原递呈细胞（APC）与T细胞相互作用而启动，因此诱导APC耐受及其机制是研究热点。IL-10/IL-10R信号通路经上调SHIP-1抑制树突状细胞（DC）递呈抗原是产生免疫耐受的关键。以往认为DC是启动Th2免疫应答的重要细胞，但DC不能自分泌IL-4，且无外源性IL-4不能诱导Th2分化。近年发现嗜碱性粒细胞（Ba）具备APC功能，促进Th2分化，并受SHIP-1调控，是诱导免疫耐受的靶点。我们亦发现，Ba作为APC在启动过敏性气道炎症中起关键作用；进一步发现Ba表达IL-10R，且外源性IL-10可抑制Ba摄取OVA。因此，我们假设IL-10/1L-10R通过上调SHIP-1负向调控Ba参与Th2免疫应答，产生免疫耐受。本项目聚焦Ba，通过激活或阻断IL-10/IL-10R通路阐释其作用，对拓展支气管哮喘发生的免疫学机制具有重要意义。

过敏性哮喘是机体对变应原产生过度Th2 免疫应答。目前认为嗜碱性粒细胞（Ba）具备抗原递呈细胞功能启动Th2免疫应答，但有较多争议。本研究采用OVA诱导的小鼠过敏性气道炎症模型，探讨Ba在过敏性气道炎症中的作用及IL-10/IL-10R调控Ba机制。我们发现，OVA诱导可显著增加肺组织Ba数量并增强其活化，上调共刺激分子表达，增强对DQ-OVA抗原的摄取能力，而且肺组织Ba可分泌大量IL-4并可促进Th2定向分化，回输肺组织Ba则可诱导正常小鼠产生过敏性气道炎症。特异性抗体（MAR-1和Ba103）剔除Ba则显著抑制过敏性气道炎症。以上研究表明Ba可作为主要免疫细胞启动过敏性免疫应答。IL-10/1L-10R信号通路是负向调控过敏性气道炎症的重要机制。IL-10的抗炎作用靶点十分广泛，但是否可作用于Ba尚未清楚。我们研究发现Ba可表达IL-10R，提示Ba具备IL-10作用靶点。进一步研究发现内源性缺乏IL-10(IL-10KO)导致过敏性气道炎症较野生型小鼠严重，Th2免疫应答增强，而给予外源性给予IL-10后气道减轻，Th2免疫应答减弱。这表明IL-10/IL-10R通路对Th2免疫应答具有负向调节作用。同时发现，内源性缺乏IL-10导致Ba对DQ-OVA抗原摄取能力增强，表面共刺激分子表达增强；相反的，当外源性给予IL-10后上诉指标逆转。在体外，我们发现IL-10KO或IL-10RKO小鼠骨髓细胞培养后Ba表现出与体内研究一致的结果，而且在体外Th2细胞定向分化实验中，IL-10干预后Ba对Th2分化作用显著抑制，而加用IL-10中和抗体后这种作用被消除。SHIP-1是调控Th2免疫应答的重要细胞内信号通路。我们通过Westernblot 检测发现，IL-10干预后Ba内SHIP-1和磷酸化SHIP-1表达显著上调，表明IL-10/IL-10R可通过SHIP-1调控Ba的功能。结合体内外结果，我们认为IL-10/IL-10R通路可通过抑制Ba抗原递呈功能调控气道炎症。本研究进一步证实明Ba可作为主要免疫细胞启动Th2免疫应答作用，而IL-10/IL-10R对Ba具有负向调控作用。这一研究结果对进一步深入认识Ba和Th2免疫应答具有重要理论价值，既拓展了Ba研究，又深化了IL-10抗炎机制，为过敏性气道炎症的临床治疗提供新的靶点治疗方向。