眼表微生物组的改变参与过敏性结膜炎发病机制的研究

Microbial ecosystems interact with the human body and affect human health. Ocular microbiota plays a key role in maintaining the physiology of the ocular surface, and dysbiosis of local microbial community can lead to ocular surface diseases. Using direct metagenomic shotgun sequencing approach, we surveyed the composition and function of conjunctival microbiota in volunteers from three Chinese cities (Guangzhou, Wenzhou, and Beijing) and showed that the airborne particulate matter PM2.5 from Beijing modulated conjunctival microbiota and damaged ocular surface. So we hypothesize that the alteration of the ocular surface microbiome may be associated with allergic conjunctivitis. Allergic conjunctivitis is a common form of ocular allergy, as it affects nearly one-third of the world population. As an inflammation condition of the conjunctiva tissue, allergic conjunctivitis is triggered by IgE-mediated and/or non-IgE-mediated allergic responses to allergens interacting with toll-like receptor 2. The role of Staphylococcus aureus colonization in the pathophysiology of chronic allergic conjunctivitis has been suggested, and the products of S. aureus, such as staphylococcal enterotoxin (SE) and exfoliative toxin, are correlated with allergic diseases. However, due to the limitations of traditional culture-based research methods, whether and how the ocular surface microbiota changes in allergic conjunctivitis patients remain unknown. Therefore, we will survey the composition and function of the conjunctival microbiome on allergic conjunctivitis patients using the direct metagenomic shotgun sequencing approach.

人体的眼表定植着相对稳定的微生物群落，微生物组的改变与包括过敏性疾病在内的多种免疫介导疾病相关。我们前期的研究结果表明空气中PM2.5浓度的升高，可以通过调控眼表微生物组中痤疮丙酸杆菌和绿脓假单胞菌的相对丰度诱发炎症，从而导致眼表角结膜的损伤。由于眼表的健康与眼表微生物密切相关，因而我们提出过敏性结膜炎的病程可能与眼表微生物的改变有关这一假说。已有研究表明金黄色葡萄球菌可能与慢性过敏性结膜炎的病理生理机制有关，葡萄球菌肠毒素、剥脱性毒素等金黄色葡萄球菌的代谢产物也被证实与过敏性疾病相关。然而由于研究手段的局限性，目前的研究尚不能全面系统地对过敏性结膜炎患者眼表微生物组的改变进行揭示。因而本研究试图在前期研究结果的基础上，通过宏基因组测序手段，找到眼表微生物组中与过敏性结膜炎发病相关的微生物种类，最终达到以该微生物种群为靶点来调节眼表的免疫状态，为过敏性结膜炎新的治疗方式的探索提供依据。

过敏性结膜炎是最常见的眼表疾病之一，且近年来，由于空气污染的加重，其发病率进一步上升。虽然大多数过敏性眼表疾病的临床诊断率和治愈率较高，但病程易反复，病情迁延，最终可导致不可逆的视力损伤。近年来的研究表明微生物组的改变与多种眼部疾病有关。为阐明眼表的微生物组在过敏性结膜炎发病机制中的关键作用，本项目收集了39例过敏性结膜炎患者的结膜印迹细胞样本，通过宏基因组测序技术比较了过敏性结膜炎患者和健康受试者眼表微生物组的差异。我们的研究结果表明过敏性结膜炎患者与健康人群眼表的微生物组在物种水平的相对构成上存在着显著的差异，真菌Malassezia furfur和细菌Moraxella catarrhalis在过敏性结膜炎患者眼表微生物组中的相对丰度较高；核糖体蛋白、Pfam蛋白家族以及Enzyme Commission基因家族等在过敏性结膜炎患者眼表的微生物组中存在显著的富集现象。同时，我们也发现过敏性结膜炎患者眼表宏基因组中存在的抗生素抗性基因明显高于健康人群。不同类型过敏性结膜炎患者的眼表微生物组在物种水平的相对构成上也存在着显著的不同。与季节性过敏性结膜炎/常年性过敏性结膜炎相关的微生物种类包括Brevibacterium aurantiacum和Staphylococcus sciuri。而链球菌在春季角结膜炎患者眼表微生物组中的相对丰度明显升高。综合上述结果，本项目为过敏性结膜炎治疗手段的研发提供了新的方向。项目资助发表SCI论文2篇。