Bi-functional fusion proteins to regulate autoimmunity

目前的治疗方法是自身免疫性疾病是不够的，因为他们治疗症状，而不是潜在的 原因，并往往与严重的副作用，特别是在长期使用。调节性T细胞 （TcR）代表主动抑制自身反应性T细胞的主要机制，其存在于所有免疫缺陷中。 个体T细胞的破坏导致自身反应性T细胞的激活，这有助于发展 自身免疫性相应地，一种有吸引力的治疗方法是重新调节免疫系统， 增强TcB的数量和/或功能以限制自身反应性T细胞。我实验室的大量工作 确定IL-2对于Treg发育和外周稳态是必需的。此外，我们还展示了 关键的IL-2 R依赖性活性很容易得到Treg中低IL-2 R信号传导的支持，而不是T效应细胞中的低IL-2 R信号传导 （Teff）细胞。这些发现为使用低剂量重组IL-2（rIL-2）的概念提供了机制支持 作为自身免疫的Treg选择性疗法。最近几种自身免疫性疾病的临床试验显示， 低剂量rIL-2选择性地增强TcR，这通常伴随着临床改善。然而，尽管如此， rIL-2具有差的药代动力学和药效学，需要频繁给药。 此外，自身免疫相关症状未完全消退，且在停止低剂量治疗后， rIL-2，自身免疫攻击通常恢复。新的分子工程IL-2为基础的生物制剂已经 开发了与重组IL-2（rIL-2）相比具有改善的性质的IL-2。在这方面我们 开发了一种基于IL-2的蛋白，其中IL-2与CD 25连接。IL-2/CD 25融合蛋白选择性地表达IL-2， 在NOD小鼠中，IL-1和IL-2对TcR的作用比rIL-2更强，并且在扩大TcR和限制糖尿病方面比rIL-2有效得多。 然而，即使使用这种改进的基于IL-2的生物制剂来递送IL-2活性， 有时只是延迟。基于这些发现，我们假设， 这是提高低剂量IL-2疗效所必需的。我们希望研究的一种方法是增加 同时应用免疫调节剂增强免疫抑制， 活动为了实现这一目标，我们开发了一种双功能融合蛋白来提供这两种活性。 因此，本建议的主要目的是优化和评估这种融合蛋白在体内的活性 通过以下具体目标。1)为了评估这种双功能融合蛋白是否比 mIL-2/CD 25限制结肠炎和糖尿病临床前小鼠模型中的自身免疫。2)确定 这种双功能融合蛋白的细胞作用机制。这些研究测试了这种新的融合 这种蛋白直接限制Teff细胞并影响自身免疫攻击的组织部位中的其他免疫细胞。3)到 评价双功能融合蛋白对自身反应性T细胞的贡献。

Current therapies are for autoimmune diseases are inadequate as they treat symptoms, not the underlying cause, and are often associated with severe sides effects, especially upon prolonged use. Regulatory T cells (Tregs) represent a major mechanism to actively suppress self-reactive T cells, which are present in all individuals. A breakdown in Tregs leads to activation of self-reactive T cells that contribute to the development of autoimmunity. Correspondingly, an attractive therapeutic approach is to re-regulate the immune system to boost the numbers and/or function of Tregs to limit autoreactive T cells. Extensive work from my lab has established that IL-2 is essential for Treg development and peripheral homeostasis. Furthermore, we showed that key IL-2R-dependent activities were readily supported by low IL-2R signaling in Treg but not T effector (Teff) cells. These findings provide mechanistic support for the notion to use low-dose recombinant IL-2 (rIL-2) as a Treg-selective therapy for autoimmunity. Recent clinical trials across several autoimmune diseases show that low-dose rIL-2 selectively boost Tregs that is often accompanied by clinical improvement. Nevertheless, rIL-2 has poor pharmacokinetics and pharmacodynamics that necessitate frequent administration. Furthermore, autoimmune-related symptoms were not completely resolved, and upon cessation of low-dose rIL-2, the autoimmune-attack usually resumed. New molecularly engineered IL-2-based biologics have been developed that have improved properties when compared to recombinant IL-2 (rIL-2). In this regard, we developed an IL-2-based protein, where IL-2 is linked to CD25. The IL-2/CD25 fusion protein shows selectively toward Tregs and is much more effective than rIL-2 in expanding Tregs and limiting diabetes in NOD mice. However, even with this improved IL-2-based biologic to deliver IL-2 activity, diabetes development was sometimes only delayed. Based on these findings, we have hypothesized that combination strategies will be necessary to enhance the efficacy of low-dose IL-2. One approach that we wish to investigate is to increase Tregs through IL-2 while enhancing immunosuppress by simultaneously applying an immune regulating activity. To accomplish this goal, we have developed a bifunctional fusion protein to deliver these two activities. Thus, the main objective of this proposal is to optimize and evaluate the activities of this fusion protein in vivo through the following specific aims. 1) To assess whether this bifunctional fusion protein is more effective than mIL-2/CD25 to limit autoimmunity in pre-clinical mouse models of colitis and diabetes. 2) To determine the cellular mechanism of action of this bifunctional fusion protein. These studies test the extent this novel fusion protein directly limits Teff cells and affects other immune cells in the tissue site(s) of autoimmune attack. 3) To evaluate the contribution of the bifunctional fusion protein on autoreactive T cells.