Functional Studies of the IL-7/IL-7R Pathway in Alopecia Areata

项目摘要 斑秃（AA）是一种最常见的自身免疫性疾病，导致毁容性脱发， 特别是在儿童和青少年中具有显著的心理社会发病率。由于没有FDA 批准的AA治疗，具有改善的安全性特征的靶向治疗的识别将是一个 实质性进展。我们最近发现CD 8 + NKG 2D + T细胞是AA中的关键致病细胞，这指导了我们的研究。 努力鉴定驱动其活化和功能的炎性细胞因子。我们的基因转录 分析数据显示，白细胞介素-7（IL-7）及其受体（IL-7 R α）在AA损伤中上调， 皮肤IL-7是淋巴细胞发育和存活所必需的细胞因子。虽然IL-7及其受体具有 IL-7与其它几种自身免疫性疾病有关，但其在AA发病机制中的作用尚不清楚。 我们的初步数据表明，IL-7在AA中起着关键作用，这一点通过治疗益处得到了强调。 IL-7阻断在AA的C3 H/HeJ小鼠模型中的作用。虽然IL-7的作用已经在临床上得到了很好的研究， T细胞的发育、稳态增殖和存活，IL-7/IL-7 R 信号通路影响AA中的疾病环境和致病性T细胞应答，特别是在体内， 没有得到充分解决。在本提案的具体目标1中，我们将评估IL-7与脱发之间的联系。 使用逆转录TCR系统在体内诱导野生型或IL-7敲除的自发AA的T细胞 背景虽然IL-7的表达在AA中上调，但关于其机制知之甚少， 调节AA中皮肤IL-7的产生。在具体目标1中，我们假设IFN-γ产生的反馈回路 通过毛囊浸润T效应细胞，这反过来又促进皮肤IL-7的产生和T细胞的存活， 淋巴细胞有趣的是，我们发现IL-7 R α阻断可增加免疫抑制因子的表达。 IL-7抑制T效应细胞上的受体PD-1的表达，而IL-7抑制T细胞上的PD-1的表达。PD-1扮演了一个核心角色， 在外周耐受性中的作用。PD-1在AA发病机制中的作用尚未研究。在 本提案的具体目标2，我们将首先通过PD-1通路阻断来解决PD-1在AA中的作用。最后， 考虑到IL-7阻断剂在治疗人AA中的治疗潜力，我们将确定IL-7的作用。 通过测定血清IL-7是否与疾病参数相关， 评估特异性目标3中IL-7诱导的细胞因子产生。最重要的是，我们将定义 患者中AA头皮转录组和IL-7基因签名，因为AA分子环境 是复杂的，具有看似相似的AA表现的患者对治疗具有异质性反应。 总体而言，拟议的研究与申请人成为独立研究员的目标非常一致。 皮肤自身免疫性疾病领域的研究者。这项研究的结果将促进我们的理解 AA的发病机制，评估IL-7在毛囊终末器官耐受性丧失中的作用， 并帮助我们评估针对AA中IL-7/IL-7 R通路的治疗干预。

Project Summary Alopecia areata (AA) is one of the most common autoimmune diseases resulting in disfiguring hair loss, and carries significant psychosocial morbidity especially in children and adolescents. Since there are no FDA approved treatments for AA, the identification of targeted therapies with an improved safety profile would be a substantial advance. We recently identified CD8+NKG2D+ T cells as the key pathogenic cells in AA guiding our efforts to identify inflammatory cytokines that drive their activation and function. Our gene transcriptional profiling data showed that interleukin-7 (IL-7) as well as its receptor (IL-7Rα) are upregulated in AA lesional skin. IL-7 is a cytokine essential for lymphocyte development and survival. Although IL-7 and its receptor have been implicated in several other autoimmune diseases, the role of IL-7 in the pathogenesis of AA is unknown. Our preliminary data show that IL-7 plays a critical role in AA which was underscored by the therapeutic benefit of IL-7 blockade in C3H/HeJ mouse model of AA. Although the role of IL-7 has been well studied in development, homeostatic proliferation, and survival of T cells, the mechanism by which the IL-7/IL-7R signaling pathway influences disease settings and pathogenic T cell responses in AA, particularly in vivo, has not been fully addressed. In Specific Aim 1 of this proposal, we will assess the link between IL-7 and alopecic T cells in vivo using a retrogenic TCR system to induce spontaneous AA in wild type or IL-7 knockout background. Although the expression of IL-7 is upregulated in AA, little is known about the mechanisms that regulate skin IL-7 production in AA. In Specific Aim 1, we postulate a feedback loop in which IFN-γ is produced by hair follicle infiltrating T effector cells, which in turn promotes skin IL-7 production and the survival of T lymphocytes. Interestingly, we have found that IL-7Rα blockade increases the expression of immune inhibitory receptor PD-1 on T effector cells, whereas IL-7 inhibits the expression of PD-1 on T cells. PD-1 plays a central role in peripheral tolerance. The role of PD-1 in the pathogenesis of AA has not been yet investigated. In Specific Aim 2 of this proposal, we will first address the role of PD-1 in AA by PD-1 pathway blockade. Lastly, given the therapeutic potential of IL-7 blockade in the treatment for human AA, we will determine the role of IL- 7 in pathogenesis of human AA by determining if serum IL-7 correlates with parameters of disease, by evaluating the IL-7-induced cytokine production in Specific Aim 3. Most importantly, we will define a subset of patients in which the AA scalp transcriptome and IL-7 gene signature because the AA molecular environment is complex and patients with seemingly similar AA presentations have heterogeneous responses to treatment. Overall, the proposed research is strongly aligned with the applicant’s goal of becoming an independent investigator in the field of skin autoimmune diseases. The results of this study will advance our understanding of the pathogenesis of AA, evaluate the role that IL-7 plays in the loss of tolerance in the hair follicle end-organ, and aid us in evaluating therapeutic interventions that target the IL-7/IL-7R pathway in AA.