新生儿期共生菌暴露诱导自然杀伤T细胞耐受防治哮喘的作用及机制研究

Prevalence of asthma has become an increasing problem in the last few decades and asthma has become the most common chronic disease among children. The impairment of immune tolerance to the allergen exposure might be causally related to the development of asthma. Recent studies suggested that disruption of commensal microbiota during neonatal period may lead to the impairment of immune tolerance and play a potential role in the development of asthma. NKT cells probably play an important role in the pathogenesis of asthma. However, the specific mechanism is still unknown. In this study, we will 1) examine the relationship between disruption of neonatal airway microbiome and the prevalence or severity of clinical asthma during childhood; 2) explore the role and mechanism of commensal microbiota on the regulation of NKT cells and the protection of asthma through animal experiments: firstly, we investigate the effects of commensal microbial exposure on the NKT cells and CXCL16 in the lung and gut using antibiotics induced normal microbiota disruption models; then to evaluate the effects of airway commensal microbial exposure on the prevalence and severity of asthma after OVA; further, CXCL16-neutralizing Ab was given to evaluate its influence on NKT cells and the development of asthma. The study may provide theoretical basis and new strategies for the prevention of asthma among children.

哮喘的发病率逐年增高，已成为影响儿童健康最常见的慢性病，目前对其防治仍无有效手段。生命早期微生物暴露对哮喘的防治作用日益受到证实，最新的研究提示了自然杀伤T（NKT）细胞在哮喘发病中的重要作用，但具体机制仍不清楚。本研究拟通过临床研究，分析新生儿期呼吸道菌群与随后哮喘等变应性疾病发生的相关性；通过动物实验，建立不同部位菌群抑制模型，检测不同时点肺组织NKT细胞及CXCL16表达，证实生命早期呼吸道菌群暴露对NKT细胞的影响；进而予变应原卵白蛋白（OVA）暴露，研究共生菌群暴露对哮喘的防治作用；通过CXCL16阻断动物模型，分析肺组织NKT细胞变化及对哮喘发生的作用，阐明共生菌调节NKT细胞耐受的机制，为哮喘防治提供全新的思路和理论依据。

菌群紊乱在变应性疾病发生中的作用日益受到重视。本研究从临床和动物研究两个方面，探讨了生命早期呼吸道菌群对变应性疾病的作用及机制。研究发现，呼吸道感染婴儿上、下气道菌群存在紊乱，上、下气道菌群的组成相似，比例不同；上气道菌群随月龄增长菌群呈动态改变；喘息患儿外周血iNKT细胞有高于非喘息患儿的趋势，而血浆IL-4、IL-6、IL-8、IL-10、IL-17A、IFN-γ水平显著高于非喘息患儿，且外周血iNKT细胞水平与IL-4、IL-17A水平呈正相关。动物研究发现，呼吸道菌群紊乱可导致OVA诱导的哮喘模型病理改变明显加重；与对照组相比，抗生素诱导菌群紊乱的小鼠外周血基础iNKT水平升高、脾脏iNKT水平显著上升，而肺脏iNKT细胞无显著变化；接触变应原后，外周血iNKT水平与对照组无显著差异，而肺脏iNKT细胞显著上升，同时伴有IL-4水平的升高，而IL-13水平无显著差异。本研究首次对小年龄婴儿下呼吸道菌群进行了描述，探讨了呼吸道菌群与iNKT细胞与气道炎症的相关性，发现iNKT细胞参与气道炎症发生的可能机制，研究结果为生命早期肺部菌群研究提供了理论基础，也为气道高反应性疾病的防治提供了新的思路。