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衰弱并可能致盲的炎症性疾病， 每年10万美国人。目前的治疗策略是控制炎症， 免疫抑制药物，包括类固醇，这反过来又有严重的副作用，如 白内障、青光眼、消化性溃疡、骨脱钙和全身感染易感性。鼠标 在人类自身免疫性葡萄膜炎模型中，实验性自身免疫性葡萄膜炎（EAU）已用于更好地 了解这种疾病。与慢性人葡萄膜炎相反，EAU在没有干预的情况下消退，并且小鼠是 由于脾脏中存在调节性免疫，因此能够抵抗葡萄膜炎的复发。这一监管 免疫需要EAU后Treg细胞被EAU后抗原呈递细胞（APC）激活。我们有 表明黑皮质素5受体（MC 5 r）是在后淋巴结转移中出现调节性APC所必需的。 EAU脾脏，这种调节性APC是腺苷的来源，腺苷通过激活EAU后Treg细胞来激活EAU后Treg细胞。 腺苷2A受体（A2 Ar）。这是一个有趣的发现，因为这两种途径 这两种途径被证明可以单独调节免疫力，但我们的观察是第一次将这两种途径联系起来。的结果 抑制EAU的自身抗原特异性Treg细胞刺激这种黑皮质素-腺苷能途径。 我们已经观察到A2 Ar依赖性T细胞在EAU发作时出现在眼睛中，持续到消退， 并在EAU再免疫后以A2 Ar依赖性方式扩增。因此，这些A2 Ar- 依赖性眼滞留TdR预防复发的可能性及A_2Ar依赖性的机制有待进一步探讨 (Aim 1）。我们已经鉴定了不同的A2 Ar依赖性T细胞免疫球蛋白和ITIM（TIGIT）TIGIT+和PD-1+ EAU后脾脏中的Treg亚群。这些不同的Treg亚群是如何被诱导的，它们如何抑制EAU， 并且如果每个子集在葡萄膜炎患者中具有不同的激活要求，则将研究（目标2）。的 EAU后Treg细胞表达归巢于次级淋巴组织的CCR 7和归巢于次级淋巴组织的CCR 6。 在眼睛中，当重新激活时，在两个组织部位都发现这些TCRs，并且诱导CCR 6和CCR 7的表达 通过刺激葡萄膜炎患者PBMC上的腺苷能-黑皮质素途径， 与健康对照组相比有所下降。腺苷能黑皮质素在EAU后的作用部位和方式 将研究Treg细胞归巢以抑制葡萄膜炎（目标3）。我们的假设是黑皮质素- 腺苷能途径诱导有效和长期的调节性免疫， 自身免疫性葡萄膜炎我们建议将联合收割机小鼠研究与翻译研究相结合，以回答重要的 关于眼部自身抗原特异性Treg细胞的机制问题，其长期目标是将这些 将这些发现应用于临床，以开发一种可提供持久缓解的葡萄膜炎治疗方法。

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.