ApoFasL: a Novel Immunotherapeutic for T1D

描述（由申请人提供）：1型糖尿病（T1D）是一种自身免疫性疾病，以破坏分泌胰岛素的胰腺β细胞为目标，是全球超过1%人口发病和死亡的主要原因。虽然胰岛素治疗和胰岛移植是目前最有效的治疗方法，但这两种方法都有很大的局限性，包括胰岛素治疗不能完全预防糖尿病相关并发症，人类胰岛移植的可用性有限，以及无论使用免疫抑制药物，同种异体胰岛移植都会产生排斥反应。因此，使用不同物种（如猪）的胰岛，并在不长期使用免疫抑制药物的情况下诱导耐受性，将是临床上有效治疗T1D所需的重要治疗进展。鉴于Fas/FasL系统在对自身抗原的免疫耐受、免疫特权和淋巴细胞稳态中发挥着重要作用，以及FasL在各种情况下广泛应用于诱导异体移植耐受，本研究的主要目的是建立一种新颖、安全、实用的方法，即ApoFasL诱导异体胰岛移植耐受作为治疗1型糖尿病的治疗干预措施。这项资助的主要研究者，Haval Shirwan博士，利用ApoImmune公司的ProtEx（tm）技术开发了一种新型的FasL，具有强大的凋亡活性。ProtEx（tm）包括产生带有核心链亲和素修饰形式的嵌合免疫配体，用生物素修饰细胞膜，并用嵌合蛋白修饰生物素化膜。初步数据表明，在异体移植模型中，使用ProtEx（tm）在胰岛上显示FasL （ApoFasL治疗）可预防移植排斥反应和治疗化学诱导的糖尿病。在这些数据的基础上，本提案的重点是开发一种有效的、临床适用的方法，在大鼠-小鼠模型中诱导对异种胰岛移植物的免疫耐受，以治疗糖尿病。FasL将在大鼠供体胰岛上显示，用于移植到化学诱导的糖尿病小鼠和自发性糖尿病非肥胖糖尿病（NOD）小鼠，这些小鼠表现出破坏性的自身免疫性胰腺胰岛素炎。移植将在雷帕霉素存在的情况下进行，雷帕霉素是临床用于预防移植排斥反应的药物。我们假设用FasL修饰的胰岛会通过细胞凋亡和扩增T调节细胞来消除异种反应性淋巴细胞，从而诱导耐受性。雷帕霉素有望通过消除T效应细胞和/或扩增T调节细胞来进一步增强这种反应，从而产生供体特异性免疫耐受，从而导致移植胰岛的存活。原理验证之后将进行II期STTR申请，通过测试其在猪-非人灵长类异种移植模型中的有效性，进一步将ApoFasL开发为先导产品。对异种胰岛的耐受性将是将这种新方法转化为临床治疗T1D的第一步。如果证明有效，ApoFasL可能会改善全球数百万人的生活质量，并产生数十亿美元的经济影响。异种胰岛移植是治疗1型糖尿病的一种替代方法，可以替代传统的同种异体胰岛移植和胰岛素治疗方法，并有望产生更明确的解决方案。ApoFasL方法如果成功，将为1型糖尿病的治疗提供一条途径。

DESCRIPTION (provided by applicant): Type 1 Diabetes (T1D) is an autoimmune disease that targets insulin secreting pancreatic beta cells for destruction and remains a major cause of morbidity and mortality in over 1% of the population worldwide. Although insulin therapy and islet transplantation are currently the most effective treatments, both of these approaches suffer from major limitations including the inability of insulin therapy to totally prevent diabetes- associated complications, the limited availability of human islets for transplantation, and the rejection of islet allografts irrespective of the use of immunosuppressive drugs. Therefore, the use of islets from a different species, such as pigs, and induction of tolerance without the chronic use of immunosuppressive drugs will be important therapeutic advancements required for the efficient treatment of T1D in the clinic. The main objective of this proposal is to establish proof-of-principle for a novel, safe, and practical approach designated as ApoFasL to induce transplantation tolerance to xenogeneic pancreatic islets as a therapeutic intervention for the treatment of Type 1 diabetes Given the important role played by Fas/FasL system in immune tolerance to self antigens, immune privilege, and lymphocyte homeostasis, and the extensive use of FasL to induce allograft tolerance in various settings, the Principle Investigator of this grant, Dr. Haval Shirwan, developed a novel form of FasL with potent apoptotic activity using ApoImmune's ProtEx(tm) technology. ProtEx(tm) involves the generation of chimeric immunological ligands with a modified form of core streptavidin, modification of a cell membrane with biotin, and decoration of biotinylated membrane with chimeric proteins. Preliminary data have demonstrated that the display of FasL on pancreatic islets (ApoFasL therapy) using ProtEx(tm) resulted in the prevention of graft rejection and treatment of chemically-induced diabetes in an allogeneic transplant model. Expanding on these data, the focus of this proposal is to develop proof-of-principle for an effective, clinically applicable approach to induce immune tolerance to xenogeneic islet grafts in a rat-to-mouse model for the treatment of diabetes. FasL will be displayed on rat donor islets for transplantation into both chemically-induced diabetic mice and spontaneously diabetic non-obese diabetic (NOD) mice, which exhibit destructive autoimmune pancreatic insulitis. Transplants will be done in the presence of rapamycin a pharmaceutical agent used in the clinic for the prevention of graft rejection. We hypothesize that islets decorated with FasL will induce tolerance by eliminating xenoreactive lymphocytes via apoptosis and expanding T regulatory cells. Rapamycin is expected to further augment this response by eliminating T effector cells and/or expanding T regulatory cells, thereby creating donor specific immune tolerance, leading to the survival of transplanted islets. Proof-of-principle will be followed by a Phase II STTR application to further develop ApoFasL into a lead product by testing its efficacy in a pig-to-nonhuman primate xenograft model. Tolerance to xenogeneic islets will serve as the first step towards the translation of this novel approach to the clinic for the treatment of T1D. If proven effective, ApoFasL may improve the quality of life of millions of individuals worldwide with an economic impact in billions of dollars. Xenograft islet transplantation represents an alternative therapeutic approach for Type 1 diabetes over classic allogeneic islet transplantation and insulin treatment therapies, and promises to yield a more definitive solution. The ApoFasL approach, when successful, will ensure a pathway to the treatment of Type 1 diabetes.