AIM2炎症小体在干眼免疫中的功能及机制研究

Dry eye disease (DED) is an immune-mediated ocular surface disorder. Although the pathogenesis of dry eye disease is not fully understood, it is recognized that inflammation has a prominent role in the development and propagation of this debilitating condition. However, the immune mechanism of DED is complex and remains unclear. Absent in melanoma 2 (AIM2), a member of interferon-gamma (IFN-γ) inducible Ifi-200 family, plays an important role in the innate immune system. AIM2 can be upregulated by IFN-γ. AIM2 forms an inflammasome with the ligand and ASC to activate the cytokines IL1β and IL18 via caspase-1. IFN-γ and IL-1β are important inflammatory cytokines in DED. We hypothesize IFN-γ activate IL-1β via upregulating AIM2. We will use AIM2-/- mice as animal model. The ocular surface integrity of WT and AIM2-/- will be analyzed in normal conditions. C57BL/6 WT and AIM2-/- mice will receive injections of scopolamine hydrobromide (SCOP), and integrity of ocular surface will be evaluated. The expression levels of inflammatory cytokines, such as IFN-γ and IL-1β, the immunohistochemistry of lacrimal gland and the immunophenotype of infiltrating immunocytes in each group will be evaluated. The lacrimal gland will be cultured in vitro to further confirm the upstream and downstream factor of AIM2. We will investigate and clarify the important role and mechanism of AIM2 in immunoregulation of dry eye, which may provide a new therapeutic target for DED.

干眼是免疫功能失调导致的眼表炎症性疾病，其免疫病理机制并未得到充分研究。AIM2是重要的炎症反应物，属于干扰素诱导的Ifi-200基因家族成员，能被IFN-γ激活，并通过激活ASC和caspase-1激活炎症因子IL-1β和IL-18。而IFN-γ和IL-1β是干眼炎症机制中重要的炎症因子。在干眼模型中，假设IFN-γ可通过上调AIM2进而激活IL-1β，我们选取Aim2-/-小鼠作为动物模型，分析正常环境下Aim2-/-小鼠角膜上皮健康情况，然后通过东莨菪碱诱导干眼模型，比较造模后野生型和Aim2-/-小鼠角膜上皮情况、眼表炎症因子IFN-γ、IL-1β等表达水平、泪腺组织学形态及免疫细胞在泪腺中的分布和数量差异，并通过泪腺体外培养进一步确定AIM2相关上下游关键分子，以探寻AIM2在干眼炎症中功能机制。这一原创性研究将阐明AIM2在干眼免疫中的作用和分子机理，为干眼提供新的治疗靶点。

干眼是免疫功能失调导致的眼表炎症性疾病，炎症反应在干眼中起到关键性作用，AIM2作为重要的炎症反应物，在本课题中，通过选取Aim2-/-小鼠作为动物模型对AIM2在干眼中的功能和作用进行研究。首先，通过分析正常环境下Aim2-/-小鼠角膜上皮健康情况，明确AIM2对正常角膜上皮微环境没有明显作用，然后通过东莨菪碱诱导干眼模型，比较造模后野生型和Aim2-/-小鼠角膜上皮情况，发现干眼模型下，Aim2-/-小鼠角膜干眼症状明显轻于野生型，角膜上皮凋亡率明显低于野生型组，干眼模型下Aim2-/-小鼠泪腺炎症因子IL-1β表达水平低于野生型，通过泪腺体外培养进一步确定Aim2-/-小鼠泪腺炎症因子IL-1β表达水平低于野生型是通过IFN-γ- Aim2-IL-1β调控。RNA-seq结果分析发现Aim2-/-小鼠和野生型泪腺中，Th1，Th2，Th17及B细胞相关基因发生改变，提示AIM2可能通过影响炎症细胞的基因从而改变干眼状态下泪腺中炎症细胞反应，进而影响干眼程度。这一原创性研究阐明AIM2在干眼免疫中的作用，为干眼提供新的治疗靶点。