胰高糖素受体单抗对胰岛α细胞增生及向β细胞转化的作用及机制研究

Strategy for promoting islet β cell regeneration is a potential treatment for diabetes. It has been shown that islet α cells can be trans-differentiated into β cells under several circumstances. Our previous study found that glucagon receptor (GCGR) monoclonal antibody not only decreased hyperglycemia in diabetic mice, but also induced α cell hyperplasia and up-regulated circulating glucagon-like peptide-1 (GLP-1) level. Besides, our preliminary results demonstrated GCGR monoclonal antibody, combined with GLP-1 analog, could further increased β cell mass. Thus, we speculate that GCGR monoclonal antibody, combined with other drugs, might induce α cells to trans-differentiate into β cells and recover islet β cell mass by promoting islet α cell hyperplasia. In this program, we intend to complete the following plans. First, to investigate the effects of GCGR monoclonal antibody on islet α cell hyperplasia and trans-differentiation of α cells into β cells in different types of diabetic mice models and in control mice. Second, to determine the action of GCGR monoclonal receptor combined with other drugs (such as GABA or GLP-1) on the trans-differentiation of α cells into β cells, and to detect the regeneration speed and degree of β cells. Third, to investigate the source of α cell hyperplasia and β cell regeneration by using different lineage-tracing technologies. Fourth, to clarify the factors in the circulation by using mass spectrum analysis and high throughput sequencing. Fifth, to analyze the regulatory roles between islet α cells and β cells by comparing the differences of purified α cells or β cells in different groups. Our project not only is helpful to understand the mechanism of islet β cell regeneration, but also provide a clinic-potential strategy for diabetes treatment.

促进胰岛β细胞再生是治疗糖尿病的潜在希望。业已证实在某些条件下胰岛α细胞可转化为β细胞。课题组成员既往研究发现胰高糖素受体（GCGR）单抗可降低糖尿病小鼠血糖，诱导α细胞增生，升高循环胰高糖素样肽1（GLP-1）水平。预实验结果显示，GCGR单抗与GLP-1联合治疗可增加β细胞总量。因此推测GCGR单抗联合其他药物可能通过促进α细胞增生，诱导α向β细胞转化，进而恢复β细胞总量。本项目拟在不同类型糖尿病和正常小鼠中明确GCGR单抗对α细胞增生和向β细胞转化的效应；确定GCGR单抗联合GABA、GLP-1等因子对α向β细胞转化和β细胞再生的影响；应用不同的谱系示踪技术明确α细胞增生和β细胞再生的细胞来源；应用质谱分析、高通量测序等方法筛选促进α细胞增生和向β细胞转化的诱导因子；分离并纯化不同干预组的α和β细胞，分析两者间的相互调控作用。本项目有助于阐明β细胞再生的机制，为糖尿病治疗提供新思路。

胰岛β细胞数量减少或功能障碍是糖尿病的重要发病机制之一 ，促进β细胞再生是治疗糖尿病的潜在希望。既往研究发现，阻断胰高糖素受体（GCGR）可降低血糖并诱导α细胞增生，而α细胞具备向β细胞转化的能力。基于前期工作，本项目开展了五部分研究工作：明确GCGR单抗对多种模型小鼠的胰岛结构和功能的影响；确定增生α细胞的来源及其特性；探讨单抗与其他药物联合对胰岛再生的促进作用；分析再生β细胞的来源及其特性；阐明促进β细胞再生的潜在机制。结果显示：在血糖正常小鼠、1型和2型糖尿病小鼠中，GCGR单抗均能降低血糖，升高胰高糖素、生长抑素和GLP-1水平，增加胰岛α和δ细胞数量；在糖尿病小鼠中，单抗还可升高胰岛素水平，增加β细胞数量。与单抗相比，利拉鲁肽联用对血糖、血浆胰岛素水平、β细胞面积影响相似，但两药联用降低血浆胰高糖素水平，并促进α细胞向β细胞转化。内分泌前体细胞谱系示踪等技术证实增生的α细胞和再生的β细胞可来源于前体细胞分化和原有细胞增殖。α细胞谱系示踪等技术证实单抗可诱导α和δ细胞向β细胞转化。在单抗干预的不同肠段、L细胞和原代肠上皮细胞中证实单抗可促进L细胞增殖和LK细胞分化，增加L细胞数量，促进GLP-1合成和分泌，从而增加循环GLP-1水平。在GLP-1受体全身敲除和胰腺特异性敲除小鼠证实GLP-1受体参与GCGR单抗诱导的血糖稳态和胰岛再生。在干细胞分化体系和β细胞特异性敲除FoxO1小鼠，证实FoxO1在血糖稳态调控和胰岛再生中的作用。本项目强调α细胞和胰高糖素在胰岛功能调控和再生中的重要地位，进一步完善糖尿病的发病机制，揭示再生β细胞的来源，阐明再生的分子机制，从而为β细胞体内再生和糖尿病治疗提供新方案。本项目共发表SCI论文13篇（负责人第一/通讯9篇），所有IF均>3，其中2篇>8；发表中文论文10篇（负责人第一/通讯5篇），培养研究生和博后7名（已毕业4名）。