Origin and Function of Double Negative T cells in Lupus

总结。B细胞耐受性的丧失和浆细胞(PC)产生自身抗体(Ab)是主要原因 在系统性红斑狼疮(SLE)病理中的作用。尽管抗体依赖的致病机制可以部分地 在免疫抑制的控制下，抗体介导的疾病无法治愈。主要限制之一是 在制定旨在预防抗体依赖病理的治疗策略时，缺乏准确的 了解如何生成和维护自动反应PC。在这方面，T卵泡助手(TFH) 细胞是CD4T细胞的一个亚群，为B细胞提供帮助，在促进自身反应性PC方面发挥着关键作用。 因此，自身反应性TFH细胞的扩张与自身抗体的产生和疾病的严重程度相关 鼠狼疮和人类狼疮。与TFH细胞类似，双阴性(DN)T细胞是一种特殊的T细胞群 以缺乏CD4和CD8表达为特征的，在狼疮中也会扩大。重要的是， 糖尿病肾病T细胞也与疾病活动性和自身抗体的产生有关。因此，人们普遍认为，这些 细胞在自身免疫性疾病的发病机制中起着重要作用。尽管它们在疾病发展中起着推定的作用，但我们 不知道是什么信号控制了糖尿病肾病T细胞的形成，它们的确切来源和致病功能仍然存在 在很大程度上是难以捉摸的。此外，调节糖尿病肾病T细胞稳态的机制是完全未知的，并且 目前还没有在体内选择性地去除糖尿病肾病T细胞的治疗方法。这项提议的主要目标是 明确控制致病性糖尿病肾病T细胞发育和功能的细胞和分子机制。在……里面 在这方面，我们的初步数据表明，DNT细胞和TFH细胞具有共同的表型，转录， 和发展要求。因此，我们已经确定了一组Bcl6dN T细胞 表型与TFH细胞相似。将在该提案中检验的中心假设是TFH细胞是 Bcl6dN T细胞的前体细胞与Tfh细胞相似，是有效的B细胞辅助者。 重要的是，我们的初步数据还表明，Bcl6dN T细胞比Tfh细胞更具可塑性，这 使他们能够获得我们认为对支持自动反应PC至关重要的TFH/Th17混合签名 回应。在目标1中，我们将检验Tfh细胞是Bcl6dN T细胞的前体的假设，并检验 这些细胞帮助自身反应的B细胞的能力。在目标2.1中，我们将测试IL-1的假设 17糖尿病肾病T细胞的产生对于支持PC反应和抗体介导的病理是至关重要的。在AIM 2.2中，我们 将确定控制获得“混合”Tfh/Th17签名的分子机制。最后，在 目的3、我们将开发一种新的以IL-2为基础的协同免疫疗法，旨在选择性地靶向Tfh和 超低剂量rIL-2联合STAT3-2抑制IL-17 Bcl6-dN T细胞分化 信号封锁。我们相信，我们的研究将为研究糖尿病肾病T细胞的致病性提供一个新的范例 将揭示与自身免疫性疾病发病机制有关的新途径，并将对 设计新的治疗干预措施，以靶向TfH和DNT细胞，并防止抗体介导的病理。

SUMMARY. Loss of B cell tolerance and production of auto-antibodies (Ab) by plasma cells (PCs) play a major role in Systemic Lupus Erythematosus (SLE) pathology. Though Ab-dependent pathogenesis can be partially controlled with immunosuppression, there is no cure for Ab-mediated disorders. One of the main limitations when developing therapeutic strategies aimed to prevent Ab-dependent pathology is the lack of a precise understanding of how auto-reactive PCs are generated and maintained. In this regard, T follicular helper (Tfh) cells, a subset of CD4+ T cells that provides help to B cells, play a critical role in promoting auto-reactive PCs. As such, the expansion of self-reactive Tfh cells correlates with auto-Ab production and disease severity in murine and human lupus. Similar to Tfh cells, Double-negative (DN) T cells, a particular population of T cells that characteristically lack CD4 and CD8 expression, are also expanded in lupus. Importantly, the frequency of DN T cells also correlates with disease activity and auto-Ab production. Thus, it is generally believed that these cells play a role in autoimmune disease pathogenesis. Despite their putative role in disease development, we do not know what signals control DN T cell formation, and their exact origin and pathogenic function remain largely elusive. Furthermore, the mechanisms that regulate DN T cell homeostasis are entirely unknown, and there are currently no therapies to selectively deplete DN T cells in vivo. The main goal of this proposal is to define the cellular and molecular mechanisms that control pathogenic DN T cell development and function. In this regard, our preliminary data demonstrate that DN T cells and Tfh cells share phenotypic, transcriptional, and developmental requirements. As such, we have identified a population of Bcl6+ DN T cells that phenotypically resemble Tfh cells. The central hypothesis that will be tested in this proposal is that Tfh cells are the precursors of Bcl6+ DN T cells and that, similar to Tfh cells, these cells are efficient B cell helpers. Importantly, our preliminary data also suggest that Bcl6+ DN T cells are more plastic than Tfh cells, which allows them to acquire a “hybrid” Tfh/Th17 signature that we believe is critical for supporting auto-reactive PC responses. In Aim 1, we will test the hypothesis that Tfh cells are precursors of Bcl6+ DN T cells and examine the capacity of these cells to help self-reactive B cell responses. In Aim 2.1, we will test the hypothesis that IL- 17 production by DN T cells is critical for supporting PC responses and Ab-mediated pathology. In Aim 2.2, we will determine the molecular mechanisms controlling the acquisition of a “hybrid” Tfh/Th17 signature. Finally, in Aim 3, we will develop a new synergistic IL-2-based immunotherapy aimed to selectively target Tfh and prevent the differentiation of IL-17+Bcl6+DN T cells by combining “ultra-low” doses of rIL-2 with STAT3- signaling blockade. We believe that our studies will provide a new paradigm for how pathogenic DN T cells are generated, will reveal new pathways implicated in autoimmune disease pathogenesis, and will be crucial for designing new therapeutic interventions to target Tfh and DN T cells and prevent Ab-mediated pathology.