OR34-07 Circulating Extracellular Vesicles Contribute to Type 1 Diabetes Pathogenicity

Abstract Disclosure: N. Guthalu Kondegowda: None. Z. Cisneros: None. J. Do: None. J. Filipowska: None. R. Li: None. S. Zhang: None. S. Ogyaadu: None. C. Wasserfall: None. M. Atkinson: None. H. Reijonen: None. D. Roeth: None. M. Kalkum: None. C. Levy: None. F. Kandeel: None. S. Sahoo: None. S. Sahoo: None. R. Vasavada: None. Type 1 diabetes (T1D) results from diminished functional β-cell mass due to autoimmunity. Plasma-derived circulating extracellular vesicles (cEVs) contribute to multiple diseases. However, their impact on T1D remains unknown. Our finding that serum from T1D subjects is cytotoxic to human β-cells led to the hypothesis that cEVs mediate β-cell cytotoxicity through their distinct molecular cargo and thus contribute to T1D pathogenesis.cEVs isolated from T1D (<5 years since diagnosis), multiple autoantibody-positive (Aab+), age, sex, and ethnicity-matched non-diabetic healthy donor (HD), and T1D subjects pre- and post-islet transplantation, were characterized physically, and protein cargo identified. Human islet cells cultured with T1D or HD plasma (10% vol/vol) or cEVs (≥50 µg/ml) were examined for cell death by TUNEL staining. Glucose and β-cell homeostasis was assessed in NOD/ShiLtJj female mice, an autoimmune T1D mouse model, treated with GW4869, an EV secretion inhibitor. PBMC-derived EVs from T1D and HD subjects were evaluated for β-cell cytotoxicity. Plasma and cEVs from T1D but not HD subjects (n=10/group) significantly increased human β-cell but not α-cell death, mimicking disease pathology. Proteomic analysis (n=5/group) identified differential cargo in T1D vs HD cEVs. Proinflammatory cytokine, IFN-γ, was increased in T1D cEVs, mediating its β-cell cytotoxic effect (n=5/group). GW4869-treatment in NOD mice (n=8-9/group) reduced cEVs, improved glucose and β-cell homeostasis in vivo, and diminished β-cell cytotoxicity of serum ex vivo, supporting cEV contribution to T1D pathology. Of clinical relevance, serum and cEVs (n=7-8/group) from Aab+ subjects also induced human β-cell cytotoxicity, implying that humoral β-cell cytotoxicity precedes clinical disease-onset. cEVs from post-islet transplant T1D patients under immunosuppressive-regimen showed reduced β-cell cytotoxicity, suggesting that immune cells may be one source of cytotoxic cEVs in T1D. Supporting this, PBMC-derived EVs from T1D but not HD subjects (n=4/group), like cEVs, induced human β-cell cytotoxicity, which was reduced with in vitro immunosuppression.Our findings demonstrate a critical role of T1D-cEVs in disease pathology through their, selective cytotoxicity to human β-cells; distinctive proinflammatory protein cargo mediating the cytotoxicity; in vivo role in T1D pathogenesis; cytotoxic phenotype acquired prior to disease-onset; cytotoxicity modulated by immunosuppression; and potential source being PBMC. Presentation: Monday, July 14, 2025