Mechanisms of Fas Ligand Control of Insulitis in Autoimmune Diabetes

描述(申请人提供)：尽管胰岛素的供应有所改善，但维持严格的血糖稳态仍然是一个挑战，导致许多1型糖尿病(T1D)患者出现严重的低血糖和高血糖以及严重的长期并发症。因此，开发一种针对这种疾病的免疫疗法仍然是一个主要目标。然而，要实现这一目标，需要深入了解糖尿病形成过程的方方面面--通常认为，糖尿病形成过程是由致病机制和调控机制之间的失衡引发的，这种失衡允许糖尿病致T细胞渗透到胰岛并破坏产生胰岛素的ss细胞。因此，识别和了解各种分子和细胞类型在易感个体和动物模型中的作用，对于开发有效的免疫治疗具有重要意义。本研究探讨了当肿瘤坏死因子家族的凋亡诱导成员Fas配体(FasL)基因失活或药物失活时，SS细胞特异性自身反应性T细胞的强大控制机制。此前，缺乏合适的模型和有效的FasL阻断mAb严重阻碍了这种调查。在这项应用中，我们将使用FasL单倍体缺乏的NOD小鼠(NOD-GLD/小鼠)和FasL中和单抗(MFL4克隆)来研究MFL4单抗阻断FasL的潜在机制和治疗意义。NOD-GLD/小鼠对T1D完全保护，具有免疫活性，并具有正常的免疫动态平衡。此外，MFL4单抗在不改变免疫稳态的情况下保护NOD-WT小鼠免受糖尿病的侵袭，更重要的是，我们的初步数据表明，它在逆转新发病例的高血糖方面具有良好的疗效。根据我们使用这些模型系统产生的初步数据，我们假设产生IL-10的调节性B细胞亚群抑制糖尿病原发的自身反应性T细胞，受到FasL的负调控。在NOD-WT小鼠中，FasL介导的凋亡消除了产生IL-10的调节性B细胞，从而消除了对自身反应性T细胞的刹车(测试目标1)。我们假设MFL4单抗可以用于逆转新发糖尿病(在AIM 2中进行了测试)。在NOD小鼠中，FasL单倍体不足(GLD/)或单抗阻断FasL可阻止产生IL-10的B细胞被消除，导致糖尿病T细胞的控制和胰岛素炎症的抑制(在AIM中进行了测试 3)。在这个修订的应用程序中，我们还将评估我们的临床前数据与人类的相关性 霍普金斯大学新诊断患者的样本和JDRF赞助的nPOD项目(目标3)提供的组织中的疾病。由于FasL在正常免疫反应和SS细胞死亡中的作用是可有可无的，了解FasL如何调节糖尿病的发生过程可以导致对疾病发病机制的新的机械性见解，这可能具有重要的治疗意义。

DESCRIPTION (provided by applicant): Despite improvement in insulin delivery, maintaining tight control of glucose homeostasis continues to be a challenge that results in bouts of severe hypo and hyperglycemia and serious long-term complications in many type 1 diabetes (T1D) patients. Therefore, developing an immunotherapy for the disease remains a major goal. Reaching this goal, however, requires deep knowledge of all facets of the diabetogenic process - which is generally believed to be initiated by an imbalance between pathogenic and regulatory mechanisms that allows diabetogenic T cells to infiltrate pancreatic islets and destroy insulin-producing ss-cells. Therefore, identifying and understanding roles of various molecules and cell types that tip the balance towards the immunopathogenic pathways in susceptible individuals and animal models is important for developing effective immunotherapy. This proposal investigates mechanisms that powerfully control ss-cell specific autoreactive T cells when Fas ligand (FasL), an apoptosis-inducing member of TNF family, is genetically or pharmacologically inactivated. Previously, the lack of appropriate models and efficacious FasL blocking mAb has severely hampered such investigation. In this application, we will use NOD mice that are haploinsufficient for FasL (NOD-gld/+ mouse) and a FasL- neutralizing mAb (MFL4 clone) to investigate the underlying mechanisms and therapeutic significance of FasL blockade using the MFL4 mAb. NOD-gld/+ mice are completely protected from T1D, immunocompetent, and have normal immune homeostasis. In addition, MFL4 mAb protects NOD-wt mice from diabetes without altering immune homeostasis and, more importantly, our preliminary data show it has promising efficacy in reversing hyperglycemia in new-onset cases. Based on our preliminary data generated using these model systems, we hypothesize that an IL-10-producing regulatory B cell subset that suppresses diabetogenic autoreactive T cells are negatively regulated by FasL. In NOD-wt mice, FasL-mediated apoptosis eliminates IL- 10-producing regulatory B cells thereby removing the brakes on autoreactive T-cells (tested Aim 1). We hypothesize that the MFL4 mAb can be used to reverse new-onset diabetes (tested in Aim 2). In NOD mice, haploinsufficiency for FasL (gld/+) or mAb blockade of FasL prevents IL-10-producing B cell elimination, leading to control of diabetogenic T cells and suppression of insulitis (tested in Aim 3). In this revised application, we will also assess relevance of our preclinical data to the human disease in samples from newly diagnosed patients at Hopkins and tissues provided by the JDRF sponsored nPOD project (Aim 3). Because the role of FasL in normal immune response and ss-cell death are dispensable, understanding how FasL modulates the diabetogenic process can lead to new mechanistic insights into the disease pathogenesis that could have important therapeutic implications.