1750-P: Rescuing Human Beta-Cell Dysfunction Induced by Proinflammatory Cytokines and Glucotoxicity

Introduction & Objective: Residual insulin secretion (IS) from surviving beta cells (BC) can be hampered by a stressful T1D islet microenvironment (e.g. cytokines - Cyt, increased glucose - G). We evaluated the effects of Cyt and Cyt+G on isolated human islet (HI) IS, assessed if BC dysfunction is reversible, and explored the associated molecular mechanisms.

Methods: HI from five nondiabetic organ donors (age, 78±15 yrs; BMI, 24.4±3.8 kg/m2) were exposed to Cyt (50 U/ml IL-1β + 1000 U/ml IFN-γ) at 5.5 or 11.1 mM G for 24h, followed by 72h culture in normal medium (wash-out, WO). IS at 3.3 and 16.7 mM G was assessed, and HI transcriptome evaluated by RNA sequencing.

Results: Cyt increased IS by 2-fold at 3.3 and 16.7 mM G, with an insulin stimulation index (ISI) of 5.3±2.3 (similar to that of control HI: 5.0±2.7). After WO, no change in IS was observed. Combined Cyt+G decreased ISI by > 50% (2.1±0.6); it improved after WO (4.0±1.1), due to better IS at 16.7 mM glucose. Transcriptome of Cyt+G washed-out vs exposed HI showed 3,137 differentially expressed genes (padj<0.01, log2FC≥1, ≤-1, 1,443 up- and 1,694 down-regulated). By GSEA, 10 pathways were positively enriched (including Glycolysis/Gluconeogenesis, AMPK signaling and Metabolic pathways) and 65 negatively enriched (including Cytokine-cytokine receptor interaction, signaling by IL-17, TNF, JAK-STAT and NF-kB, Spliceosome, Protein processing in ER).

Conclusion: Short-term exposure to Cyt increased HI IS, which persisted after WO. Combined Cyt+G impaired BC function, which recovered after WO. The improvement was associated with transcriptomic changes in metabolic processes, inflammatory pathways and the innate immune system. These data suggest that human BC function can be rescued in a T1D-like environment by alleviating the insult and/or targeting underlying molecular mechanisms.