Circulating Extracellular Vesicles in the Pathogenesis of Type 1 Diabetes

摘要：循环细胞外囊泡在1型糖尿病发病机制中的作用

SUMMARY: Circulating Extracellular Vesicles in the Pathogenesis of Type 1 Diabetes Type 1 diabetes (T1D) is an autoimmune disease, characterized by death, dedifferentiation or dysfunction of functional beta cells. However, precise molecular events that initiate beta cell loss and dysfunction or mediate autoimmunity is a major gap in knowledge that remains unaddressed. Emerging evidence suggests that circulating extracellular vesicles (EVs), known mediators of intercellular microcommunication, may play important roles in the pathogenesis of T1D. However, their precise function and molecular contents, especially in the initiation of beta cell loss and dysfunction in humans are largely undefined. Here, we hypothesize that circulating EVs in T1D, through their distinct molecular characteristics, are cytotoxic to beta cell health, thus contributing to the pathogenesis of T1D, with the potential to serve as biomarkers for early disease diagnosis. Our preliminary data suggests that EVs, but not EV-depleted fraction in the humoral factors in T1D are cytotoxic, particularly to human beta cells, but not to alpha cells. Specifically, EVs from T1D subjects, but not from control subjects, induce human beta cell death suggesting that circulating T1D-EVs are key components contributing to humoral cytotoxicity. Therefore, characterizing T1D EVs at various stages of the disease and control could identify important biomarkers for early detection of the disease that correlate with beta cell loss and dysfunction. Our research plan has the following Specific Aims: AIM 1: To determine the functional effects of circulating EVs from pre-disease to late stage T1D subjects on human beta and alpha cell health. We will characterize circulating EVs from the plasma of T1D subjects at i) early (1-5 years), ii) late (>10 year) and iii) pediatric (<18 year) stages and compare them with i) autoantibody positive non-T1D, ii) T2D (control for secondary effects such as hyperglycemia) and iii) appropriate age, ethnicity, and sex-matched healthy control non-diabetic subjects for their effect on human beta and alpha cell health. AIM 2: To establish the functional role of circulating EVs in the pathogenesis of T1D in vivo using a rodent model. To provide proof-of-concept, we will administer circulating EVs from diabetic female NOD mice to non- diabetic controls and test T1D disease progression in the recipient (Aim2A); we will inhibit EV secretion in young pre-T1D female NOD mice and test T1D disease progression and quantify beta cell death and function (Aim2B). AIM 3: Investigate the molecular mechanisms, cargo composition and cargo function of human T1D- EVs. We will address the differential function of T1D EVs in beta cell cytotoxicity by investigating their uptake mechanisms, (Aim3A); compare EV cargo in T1D and control subjects (Aim3B); examine the function of differentially expressed EV-RNAs (Aim3C). Our proposed research is clinically relevant and will profoundly change our understanding of the progression of T1D. If successful, our study has the potential to identify new biomarkers and therapeutics for T1D.