A Novel Approach of beta Cell Replacement to Reverse Type I Diabetes in NOD Mice

描述（由申请人提供）：1型糖尿病（T1D）是一种自身免疫性疾病，其特征是朗格汉斯胰岛中产生胰岛素的β细胞被破坏。为了给慢性糖尿病患者提供“治愈”的方法，被破坏的细胞群必须被替换。胰岛移植是临床上替代β细胞的一种方法。然而，这种策略受到胰岛移植受体持续免疫抑制的要求和缺乏供体胰岛可用性的限制。因此，仍然需要β细胞替代的替代策略。这项R21应用的目的是确定利用怀孕期间促进β细胞复制的事件是否是一种逆转慢性糖尿病的可行方法。众所周知，催乳素在人类和啮齿动物怀孕期间诱导显著的β细胞复制。直到最近才发现，催乳素的有丝分裂作用部分归因于β细胞诱导血清素合成，血清素以自分泌/旁分泌的方式驱动β细胞增殖。此外，β细胞的血清素受体Htr2的差异表达也被证明在怀孕期间调节β细胞复制中起关键作用。利用腺相关病毒载体介导的基因转移，在体外和体内进行实验，以验证β细胞异位表达Htr2b结合胰腺靶向催乳素表达诱导β复制足以逆转长期糖尿病NOD小鼠的临床糖尿病的假设。实验还将包括评估异位催乳素表达对胰腺炎症的影响。

DESCRIPTION (provided by applicant): Type 1 diabetes (T1D) is an autoimmune disease characterized by the destruction of the insulin producing beta cells residing in the islets of Langerhans. In order to provide a "cure" for chronic diabetic individuals the beta cell mass that has been destroyed must be replaced. Islet transplantation is one approach for beta cell replacement in the clinic. However, this strategy is limited by the requirement for continuous immunosuppression of islet graft recipients and by the lack of donor islet availability. Consequently, there continues to be a need for alternative strategies of beta cell replacement. The goal of this R21 application is to determine whether exploiting events that promote robust beta cell replication during pregnancy is a feasible approach to reverse chronic diabetes. It is known that prolactin induces significant beta cell replication during pregnancy in humans and rodents. Only recently has it been found that the mitogenic effect of prolactin is in part attributd to the induction of serotonin synthesis by beta cells, which in an autocrine/paracrine manner drives beta cell proliferation. In addition, differential expression of the serotonin receptor Htr2 by beta cells has also been shown to play a key role in regulating beta cell replication during pregnancy. Using adeno- associated virus vector-mediated gene transfer, in vitro- and in vivo-based experiments will be carried out to test the hypothesis that ectopic expression of Htr2b by beta cells combined with pancreas-targeted expression of prolactin induces beta replication sufficient to reverse clinical diabetes in long-standing diabetic NOD mice. Experiments will also be included to assess the effects of ectopic prolactin expression on inflammation in the pancreas. PUBLIC HEALTH RELEVANCE: The goal of this study is to establish a novel strategy of beta cell replacement for the purpose of reversing clinical type 1 diabetes. Importantly, if successful this approach will also be applicable for the treatment of type 2 diabetes, and islet transplantation.