吲哚胺2,3双加氧酶在真菌性角膜炎真菌免疫耐受中的作用及机制研究

Immune tolerance induced by Indoleamine 2,3-dioxygenase (IDO), as an important immune evasion mechanism, may lead to the persistence of fungi in the body and chronic infection. As a local immunosuppressive factor in human corneal cells, IDO can be acted as an inflammatory response-related factor in corneal allograft rejection, which inhibited the inflammatory response and maintained immune privilege in the cornea. Previous studies in our laboratory showed that IDO expressions increased in the corneal epithelial cells during the pathological process of fungal keratitis. Inhibition of IDO may aggravate the infection and inflammatory response. However, no evidence for the role of IDO in the immune tolerance of fungal keratitis exists. By a combination of molecular biology, immunohistochemistry, flow cytometry and other techniques, we will investigate the role of IDO in the immune tolerance of fungal keratitis, as well as the underlying mechanisms in the present study. We hypothesize that IDO may induce a protective immune tolerance and inhibit the inflammatory response by the impact of fungal morphology, influence of Th1/Thl7/Treg cell balance and regulation of localized neutrophil infection in the pathogenesis of fungal keratitis. The function of IDO is also regulated by one of the pattern recognition receptors Dectin-1. This will provide new research results and strategies for the prevention and treatment of fungal keratitis.

吲哚胺2，3双加氧酶（IDO）诱导的真菌免疫耐受作为一种重要的免疫逃逸机制，导致真菌在宿主体内持续存在，感染慢性化。研究表明IDO作为局部免疫抑制因子，表达于角膜内皮和基质细胞；其被视为角膜移植免疫排斥的炎症反应相关因子，抑制炎症反应的加剧。本室前期研究证实，真菌性角膜炎发病过程中，角膜上皮细胞中IDO表达增高；抑制IDO可加重角膜感染和炎症反应，但机制尚不清楚。本项目拟在真菌性角膜炎患者角膜组织、细胞模型、真菌性角膜炎及Dectin-1基因敲除小鼠上，综合应用分子生物学、组织化学及流式等技术，探讨IDO参与真菌性角膜炎发病过程的具体机制。拟证实IDO可通过影响真菌形态、调控Th1/Thl7/Treg细胞平衡及调节感染局部中性粒细胞功能诱导免疫耐受，使炎症慢性化。此外，IDO功能又受到模式识别受体Dectin-1的调节。本研究对了解真菌性角膜炎发病机制及提出新的干预策略具有理论和实用意义。

吲哚胺2，3双加氧酶（IDO）诱导的真菌免疫耐受作为一种重要的免疫逃逸机制，导致真菌在宿主体内持续存在，感染慢性化。真菌性角膜炎中IDO是否诱导真菌的免疫耐受导致感染慢性化尚未证实。本研究在临床真菌性角膜炎患者病变角膜组织、体外培养的角膜上皮细胞、巨噬细胞真菌感染模型及小鼠角膜真菌感染的模型上，综合应用免疫荧光、流式细胞术、Western blot及激光扫描共聚焦显微成像、计数菌落形成单位（CFU）等多种技术方法，观察IDO介导的真菌免疫耐受在真菌性角膜炎中的作用和调控机制，研究发现抑制IDO可显著加重真菌性角膜炎的感染和炎症反应，在烟曲霉菌感染的真菌性角膜炎中，烟曲霉菌可以通过Dectin-1/IDO这一信号通路，诱导角膜上皮细胞中IDO及其相关信号分子IL-1β、IL-6等的表达，进而诱导Treg反应，抑制Th17反应，介导了烟曲霉菌的免疫耐受，促进了真菌性角膜炎炎症反应的慢性化。此外，IDO 可通过抑制巨噬细胞的募集和吞噬功能，并且通过 MAPK/ERK 依赖途径促进了烟曲霉菌性角膜炎中巨噬细胞向 M1 型的极化，发挥抗烟曲霉菌的保护性免疫耐受。本研究对了解真菌性角膜炎发病机制及提出新的干预策略具有理论和实用价值。