Immunobiology of EAU Recovery Through the Melanocortin-Adenosinergic Pathway

摘要 自身免疫性葡萄膜炎是一种使人虚弱并可能致盲的炎症性疾病，在 每年有10万美国人。目前的治疗策略是通过以下方式控制炎症 免疫抑制药物，包括类固醇，类固醇反过来会产生严重的副作用，例如 白内障、青光眼、消化性溃疡、骨骼脱钙和全身感染易感性。一只老鼠 人自身免疫性葡萄膜炎的模型，实验性自身免疫性葡萄膜炎(EAU)已经被用来更好地 了解这种疾病。与慢性人类葡萄膜炎不同，EAU在没有干预的情况下就会消失，而小鼠 抗葡萄膜炎复发，因为在脾中发现了调节免疫力。这一监管规定 免疫需要EAU后Treg细胞被EAU后抗原提呈细胞(APC)激活。我们有 研究表明，黑素皮质素5受体(MC5r)是调节APC在脑缺血后出现所必需的。 EAU脾，这种调节性APC是腺苷的来源，通过 腺苷2A受体(A2Ar)。这是一个有趣的发现，因为这两条路径 显示了单独调节免疫力，但我们的观察是第一次将这两个途径联系起来。其结果是 刺激黑素皮质素-腺苷能途径的是一种自身抗原特异性的Treg细胞，它可以抑制EAU。 我们观察到依赖A2Ar的Treg在EAU开始时出现在眼睛中，持续到分辨率， 并在EAU再免疫后以A2Ar依赖的方式扩张。因此，这些A2Ar- 依赖眼部驻留Tregs预防复发和A2Ar依赖的机制将被解答 (目标1)。我们已经鉴定出不同的A2Ar依赖的T细胞免疫球蛋白和ITIM(TIGIT)TIGIT+和PD-1+ Eau-Treg后脾内的亚群。这些不同的Treg子集是如何被诱导的，它们是如何抑制EAU的， 如果每个子集在葡萄膜炎中有不同的激活要求，将对患者进行调查(目标2)。这个 EAU后Treg细胞表达CCR7和CCR6，CCR7是次级淋巴组织的家园，CCR6是EAU后Treg细胞的家园 眼睛，当重新激活时，在两个组织部位都发现了这些Tregs，并诱导了CCR6和CCR7的表达 通过刺激葡萄膜炎患者PBMC上的腺苷能-黑素皮质素途径， 与健康对照组相比减少。腺苷能黑素皮质素在哪里以及如何诱导EAU后 将研究在家抑制葡萄膜炎的Treg细胞(目标3)。我们的假设是黑素皮质素- 腺苷能途径诱导有效和长期的调节性免疫，从而提供对 自身免疫性葡萄膜炎。我们建议将小鼠研究与翻译研究相结合，以回答重要的 关于眼自身抗原特异性Treg细胞的机制问题，长期目标是将其 将研究结果引入临床，开发出一种治疗葡萄膜炎的方法，提供持久的缓解。

Abstract Autoimmune uveitis is a debilitating and potentially blinding inflammatory disease that affects 93 in 100,000 Americans annually. The current treatment strategy is to control the inflammation with immunosuppressive medication that include steroids, which in turn have serious side effects, such as cataracts, glaucoma, peptic ulcers, bone decalcification, and systemic susceptibility to infection. A mouse model of human autoimmune uveitis, experimental autoimmune uveitis (EAU) has been used to better understand this disease. In contrast to chronic human uveitis, EAU resolves without intervention and mice are resistant to recrudescence of uveitis because of regulatory immunity found in the spleen. This regulatory immunity requires post-EAU Treg cells to be activated by post-EAU antigen presenting cells (APC). We have shown that the melanocortin 5 receptor (MC5r) is required for the emergence of a regulatory APC in the post- EAU spleen, and this regulatory APC is a source of adenosine that activates the post-EAU Treg cell through the adenosine 2A receptor (A2Ar). This is an interesting finding, because these two pathways have been shown to individually regulate immunity, but our observation is the first to link the two pathways. The result of stimulating this melanocortin-adenosinergic pathway is an autoantigen specific Treg cell that suppresses EAU. We have observed A2Ar-dependent Tregs emerge in the eye at the onset of EAU, persist through resolution, and expand in an A2Ar-dependent manner following EAU-reimmunization. Therefore, how these A2Ar- dependent ocular resident Tregs prevent relapse and the mechanism of A2Ar dependency will be answered (Aim 1). We have identified distinct A2Ar-dependent T cell Immunoglobulin and ITIM (TIGIT) TIGIT+ and PD-1+ post-EAU Treg subsets in the spleen. How these distinct Treg subsets are induced, how they suppress EAU, and if each subset has a different activation requirement in uveitis patients will be investigated (Aim 2). The post-EAU Treg cells express CCR7 that homes to secondary lymphoid tissue and CCR6 that homes to the eye, these Tregs are found in both tissue sites when reactivated, and expression of CCR6 and CCR7 induced through stimulation of the adenosinergic-melanocortin pathway on PBMC from uveitis patients is significantly reduced compared to healthy controls. Where and how the adenosinergic-melanocortin induced post-EAU Treg cells home to suppress uveitis will be investigated (Aim 3). Our hypothesis is that the melanocortin- adenosinergic pathway induces effective and long-term regulatory immunity that provides resistance to autoimmune uveitis. We propose to combine murine studies with translational studies to answer important mechanistic questions about ocular autoantigen specific Treg cells with the long-term goal of bringing these findings into the clinic to develop a uveitis treatment that provides lasting remission.