LncRNA MIR22HG在甲醛所致气道炎症和气道高反应中的作用及机制研究

In our previous study, we found that exposure to formaldehyde (FA) could induce the development of airway inflammation and bronchial hyperresponsiveness in mice. However, the mechanism of FA-induced asthma-like response is still poorly understood and may be associated with lncRNA. High-throughput sequencing indicated differentially expressed lncRNA MIR22HG induced by FA exposure in human cultured airway smooth muscle cells. The mRNA- lncRNA-network indicated that lncRNA MIR22HG was significantly correlated with mRNA TGFBR3. Bioinformatics analysis predicted that there were three combing sites between lncRNA MIR22HG and miR186, and four combing sites between TGFBR3 and miR186. Thus, we hypothesized that FA exposure could increase the expression of lncRNA MIR22HG in airway smooth muscle cells, and lncRNA MIR22HG may regulate the expression of mRNA TGFBR3 through miR186, which could induce airway inflammation and bronchial hyperresponsiveness. Therefore, the objective of this research is to clarify the mechanism of lncRNA MIR22HG expression induced by FA exposure, and to explore the role of lncRNA MIR22HG in regulating mRNA TGFBR3 through miR186 and thus leading to airway inflammation and bronchial hyperresponsiveness based on experiments in vitro and in vivo.

我们前期研究发现，甲醛可诱导小鼠气道炎症和气道高反应的发生，但调控机制不明，可能与lncRNA有关。预实验通过高通量技术筛选出甲醛诱导气道平滑肌细胞差异表达的lncRNA MIR22HG，共表达分析显示lncRNA MIR22HG与mRNA TGFBR3 共表达程度高。生物学信息预测lncRNA MIR22HG与miR186存在3个结合位点，TGFBR3与miR186存在4个结合位点。因此，推测甲醛刺激气道平滑肌细胞高表达lncRNA MIR22HG, 而lncRNA MIR22HG通过“海绵”等作用调控miR186表达，进而调控其靶基因TGFBR3的表达，继而促进气道炎症和气道高反应性。鉴此，本项目从体外和动物两个层面，阐明甲醛诱导lncRNA MIR22HG表达的作用机制及lncRNA MIR22HG介导miR186调控气道平滑肌细胞TGFBR3表达并促进气道炎症和气道高反应性的作用。

哮喘是儿童期最常见的慢性呼吸道疾病。近年来，气道平滑肌细胞（airway smooth muscle cell, ASMC）和巨噬细胞作为重要的效应细胞，在哮喘的发病机制中的作用日益受到关注。多项流行病学研究提示甲醛（formaldehyde，FA）可能与儿童哮喘发病增加有关。而FA对ASMC和巨噬细胞功能的影响及机制极少有研究报道。我们以ASMC和巨噬细胞为研究对象，检测FA对ASMC迁移能力和分泌功能的影响，检测FA对巨噬细胞M1型极化标志物和活性氧水平的影响，并筛选可能发挥作用的通路。结果发现：（1）FA对ASMC迁移能力没有明显影响，但会显著增加ASMC分泌IL-6的水平；（2）FA不能直接促进巨噬细胞M1型极化，而是通过间接作用，加剧LPS诱导的巨噬细胞M1型极化；（3）LPS+FA组巨噬细胞的活性氧水平，与LPS组相比，明显升高；（4）LPS+FA组NF-κB通路各组分磷酸化蛋白水平均明显高于LPS组。接着我们用PDTC抑制NF-κB通路，结果发现FA对LPS诱导的巨噬细胞M1型极化的促进作用消失。结论：甲醛可促进ASMC分泌IL-6；甲醛可通过NF-κB信号通路促进LPS诱导的巨噬细胞M1型极化；甲醛可促进LPS诱导的巨噬细胞活性氧产生增加。该部分结果丰富了甲醛对哮喘的作用机制网络，为哮喘等炎症性疾病的防治提供新的靶点和思路。.哮喘是多种因素共同作用导致的复杂性疾病，具体病因尚未明确。因此，我们在人群层面，用国际标准化的ISAAC问卷进行横断面调查，全面评估上海市杨浦区学龄前儿童哮喘的患病率及危险因素。研究共纳入有效问卷6183份，曾有喘息、现有喘息、严重哮喘、运动诱发的喘息、夜间咳嗽、医生诊断哮喘的患病率分别为16.0%、11.2%、4.9%、5.1%、14.7%、5.3%。在多因素Logistic回归分析中，与现有喘息显著相关的影响因素有个人鼻炎史、个人湿疹史、个人食物过敏史、1岁以内抗生素使用、过去一年中使用退热药每月超过一次、母亲鼻炎史、母亲哮喘史、父亲鼻炎史、父亲哮喘史、所在社区、家中有潮湿霉菌、家中使用地暖系统。结论：遗传因素、环境因素、个人生活方式与儿童哮喘的发生均密切相关。该部分成果为儿童哮喘的防治提供了理论依据。