IL-27差异调节高/低Th2哮喘表型的作用和机理研究

Severe asthma is involved with elements of both innate and adaptive immunity. IL-27 has been shown to potentiate a TH1 response as well as suppress a TH2 response. Although IL-27 is reported to be present in atopic disease, its biologic function in asthma is not clear.Our priliminary data demonstrated that IL-27, in association with a Type-2 (IL-13) gene signature would identify a more severe asthma phenotype than when either cytokine or its signature was present alone. We hypothesized that the mechanisms for this increased severity would include diversified regulation of epithelial expression of the Type 1 chemokine, CXCL9 by IL-13 (high/low dose) and IL-27, through alterations in activation of STAT1. To evaluate this, bronchoscopic samples from a range of asthmatic and healthy control (HC) participants were analyzed for the presence of a Type-2 signature (based on epithelial CCL26 expression), alone or in association with bronchoalveolar lavage (BAL) cell IL-27 expression and compared to asthma severity and CXCL9 experesion. To determine potential mechanisms for these effects, the impact of IL-27, alone and in combination with IL-13 on primary HBEC activation of STAT1 and STAT3 was evaluated to determine their role in the synergistic increase in CXCL9 expression.The results showed IL-27 in combination with low dose IL-13 reached the peak production of CXCL9, much higher than in combination with high dose IL-13. STAT1 signaling pathway also was augmented by IL-27 in combination with low dose IL-13. While STAT6 signaling was further activated by high dose IL-13 in combination with IL-27.Such intriguing results encourage us to further investigate the diversified regulation of IL-27 on T cells and alveolar macrophages and eventually testify the theory on different animal asthma models. We believe it is invaluable to continue research of the novel interaction of innate immune (IL-27) and Type-2 inflammation (IL-13), which would lead to better understanding the complex immune process, more specific phenotype and targeted therapy for asthmatic patients.

支气管哮喘在我国的发病率正逐年升高，而仍有相当一部分哮喘患者不能得到有效控制，针对哮喘临床表型和分子表型的研究是解析哮喘异质性、开发哮喘个体化治疗方案的突破口。IL-27是近年发现的免疫调节因子，有文献报道其介入变态反应调节，但其在哮喘中作用一直未明。本项目前期研究发现高IL-27伴高Th2炎症的哮喘患者，症状最重，气道通气功能最差，但如IL-27高表达在低Th2型哮喘患者，则症状减轻，通气功能最佳。前期机理研究还发现IL-27在IL-13高/低剂量背景下对气道上皮细胞发挥不同的调节作用，其细胞内STAT1/6的信号通路也出现相应变化。本项目拟继续深入研究IL-27对高/低Th2哮喘表型免疫T细胞的调控。阐明IL-27对高/低Th2哮喘表型的差异调节不仅具有重要的哮喘临床意义，而且极富创新，将为哮喘分子表型研究开启一个新的窗口。

支气管哮喘是全球范围内的常见病和多发病，在我国近年来的发病率亦逐年上升，极大危及人民身体健康，以哮喘临床表型和分子表型为指导的个体化治疗是控制哮喘症状和降低远期风险的有效策略。IL-27是近年发现的免疫调节因子，参与了多种炎症疾病的调节，但其在哮喘中作用和机理尚不明确。本项目主要研究了三个方面的内容：1）IL-27在血清及肺泡灌洗细胞中表达与哮喘临床控制和肺功能等指标的相关性；2）IL-27在高/低Th2背景下对哮喘气道上皮细胞调控的作用；3）IL-27对哮喘外周血CD4+ T细胞的调控作用及高Th2因子对之的干扰。主要结果显示：1）哮喘患者外周血IL-27表达水平与哮喘临床控制水平密切相关，在未控制患者中，外周血IL-27水平较控制／完全控制患者明显降低；哮喘患者临床控制水平ACT评分与外周血IL-27水平成正相关（r＝0.429，p＝0.005）；并且，哮喘患者肺功能指标亦与外周血IL-27水平成正相关（r＝0.418，p＝0.027）。针对哮喘患者气道灌洗样本肺泡巨噬细胞IL-27表达的分析发现低Th2型并高IL-27表达患者症状最轻，肺功能最佳，而高Th2型并高IL-27表达患者症状最重，肺功能最差。 2）体外实验发现低剂量IL-13协同IL-27最大程度诱导气道上皮细胞分泌CXCL9，而在高剂量IL-13背景下，IL-27的诱导Th1因子CXCL9的效应反而减弱。此效应是通过低剂量IL-13协同IL-27促进STAT1磷酸化的通路实现的，而在高剂量IL-13下，IL-27协同IL-13诱导STAT6磷酸化，对抗STAT1信号通路效应，导致CXCL9产生降低。3）本研究发现IL-4对T细胞表面IL-27受体的调控有差异性，结果显示IL-4不改变总CD4+ T细胞表面IL-27RA的表达；但高浓度IL-4提高CD4+GATA3+IL-27RA+细胞数量，却不提高CD4+GATA3+T细胞中IL-27RA+细胞比例。IL-27明显促进CD4+ T细胞产生Th1效应因子CXCL9/CXCL10/CXCL11；而高浓度IL-4明显抑制IL-27诱导CD4+ T细胞产生CXCL9/ CXCL10/CXCL11。本项目在哮喘患者IL-27表达分析的临床基础上，以IL-27差异调节高/低Th2哮喘表型为主导思路，研究了IL-27对不同表型哮喘上皮细胞及CD4+T免疫调控的