Regulation of Autoimmune Type 1 Diabetes by Serpins B1 and A1 (Alpha 1-Antitrypsin)

全球糖尿病患者人数预计将从2015年的4.15亿增加到2040年的6.42亿。治疗疾病的医疗保健费用占全球卫生支出的12%，并继续成为巨大的经济负担（IDF World Atlas 2015）。1型糖尿病（T1 DM）占疾病负担的10-15%。它是一种自身免疫性疾病，被认为是由儿童早期的遗传或环境因素触发的，其导致抗体介导的胰岛素产生胰腺β细胞的破坏，从而引起危及生命的高血糖症。相比之下，2型糖尿病（T2 DM）在生命后期发展，由靶组织中的胰岛素抵抗和炎症以及β细胞补偿不足引起。 有效治疗这两种形式的疾病的主要限制是防止β细胞功能和/或质量下降。最近，Kulkarni实验室将Serpin B1（一种细胞内丝氨酸蛋白酶抑制剂）鉴定为一种肝源性蛋白因子，通过抑制弹性蛋白酶促进代偿性β细胞反应，并通过激活生长/存活因子信号通路诱导多种物种的β细胞增殖。结构和功能相关的人血浆蛋白α 1-抗胰蛋白酶（AAT，serpin A1）在延迟T1 DM发作的后期临床试验中，大多数独立研究表明，它可以通过保留功能性β细胞，增强胰岛移植物存活和调节细胞免疫来恢复T1 DM动物模型中的正常功能。早期临床研究结果表明，AAT降低HbA 1c水平和抗胰岛细胞抗体滴度。 Serpin B1（sB 1）与AAT一样，是一种有效的抗炎弹性蛋白酶抑制剂，但与AAT不同的是，它还诱导β-细胞增殖，促进胰腺导管衬里上皮中的胰岛素+细胞，抑制NETosis（糖尿病中涉及的另一种促炎过程），并在体外调节Th 17细胞因子产生细胞的扩增。因此，我们提出sB 1也可以单独或与AAT联合在体内发挥作用，在T1 DM动物模型中提供上级治疗效果。我们将在NOD小鼠模型中检测sB 1-/+ AAT是否可以通过诱导功能性β细胞增殖、增强导管内衬细胞产生胰岛素和保护β细胞免受免疫应答影响，更有效地预防或治疗已建立的T1 DM。如果成功，我们将通过临床前和临床试验进一步开发这项技术，旨在改善T1 DM患者的长期结局。拟定的I期研究将侧重于（目的1）生产高度纯化的活性重组蛋白和（目的2）在T1 DM动物模型中提供原理验证。这些研究的结果将指导未来动物和人类有效性研究的设计。

The number of people with diabetes worldwide is predicted to increase from 415 million in 2015 to 642 million in 2040. The health care costs of treating the disease account for 12% of the global health expenditure and continue to be a huge economic burden (IDF World Atlas 2015). Type 1 diabetes mellitus (T1DM) constitutes 10-15% of the disease burden. It is an autoimmune disease, thought to be triggered by genetic or environmental factors in early childhood, which results in antibody- mediated destruction of insulin producing pancreatic β-cells causing life-threatening hyperglycemia. In contrast, type 2 diabetes mellitus (T2DM) develops later in life and results from insulin resistance in target tissues and inflammation coupled with an inadequate compensation by the β-cells. A major limitation in effectively treating both forms of the disease is preventing a decline in β- cell function and/or mass. Recently, the Kulkarni lab identified Serpin B1 (an intracellular SERine Proteinase Inhibitor) as a liver-derived protein factor that promotes a compensatory β-cell response by inhibiting elastase and inducing β-cell proliferation in multiple species by activating growth/survival factor signaling pathways. The structurally and functionally related human plasma protein alpha 1- antitrypsin (AAT, serpin A1) is in late stage clinical trials to delay the onset of T1DM after a majority of independent studies showed it could restore euglycemia in animal models of T1DM by preserving functional β-cells, enhancing islet allograft survival and modulating cellular immunity. Early stage clinical study results indicate that AAT reduces HbA1c levels and anti-islet cell antibody titers. Serpin B1 (sB1), like AAT, is an effective anti-inflammatory elastase inhibitor but unlike AAT, also induces β-cell proliferation, promotes insulin + cells in pancreatic ductal lining epithelia, inhibits NETosis (another pro-inflammatory process involved in diabetes) and regulates the expansion of Th17 cytokine producing cells in vitro. We therefore propose that sB1 may also work in vivo, either alone or in combination with AAT, to provide superior therapeutic effects in animal models of T1DM. We will test if sB1 -/+ AAT can more effectively prevent the onset of, or treat established, T1DM in the NOD mouse model by inducing proliferation of functional β-cells, enhancing production of insulin by ductal lining cells and protecting β-cells from the immune response. If successful, we will further develop this technology through preclinical and clinical testing with the intent to improve long-term outcome for patients with T1DM. The proposed research in phase I will focus on (Aim 1) producing highly purified active recombinant proteins and (Aim 2) providing proof-of-principle in animal models of T1DM. The outcome of these studies will guide the design of future efficacy studies in animals and humans.