7309 Moderate ER Stress, Facilitated by IL-1β, Initiates Protective Mechanisms in Pancreatic β-Cells Ameliorating Dysfunction and Diminishing Death Induced by Inflammatory Cytokines

Abstract Disclosure: C. Sétula: None. M.S. Orellano: None. M. Argañarás: None. A. Scelza-Figueredo: None. E. Spinedi: None. L. Andreone: None. M.J. Perone: None. Type 1 and type 2 diabetes share common features, encompassing islet inflammation, β-cell dysfunction and the eventual reduction in both the number and mass of β-cells. The organism's resilience against higher doses of a harmful substance can be bolstered through the induction of mild stress responses, achieved by exposing it to low concentrations of the said agent. Our objective was to evaluate whether physiological concentrations of IL-1β prompt adaptive mechanisms that protect β-cells from the distinctive inflammatory milieu associated with diabetes.We employed INS-1E insulinoma and isolated mouse islets and measured NO by Griess, cell viability (MTT) and death (Hoechst/PI, microscopic fluorescence and Annexin V-PE/7-AAD, flow cytometry), mRNA by RT-qPCR, NF-κB (immunofluorescence), insulin (ELISA) and proteins by Western blot (WB). GSIS (glucose-stimulated insulin secretion) index was calculated as the ratio of insulin released during 1h under stimuli of 20mM/2mM glucose. Results are presented as mean ± SD, n≥3 independent experiments. Comparison between groups was carried out using paired or unpaired Student's t-test or ANOVA followed by Bonferroni's multiple comparison test, as appropriate. Mild endoplasmic reticulum (ER) stress was induced in β-cells through a 72h incubation with 10 pg/ml IL-1β (IL-1βlow). Cytokine-induced damage was triggered by 100 pg/ml IL-1β + 5 ng/ml IFNγ for 16h (CYT). IL-1βlow protects INS-1E from the decrease in mitochondrial reduction potential triggered by CYT, diminishes cell death (p<0.05 vs CYT) and improves GSIS (p<0.05 vs CYT), the latter in pancreatic islets as well (p<0.05 vs CYT). IL-1βlow reduces NO production (p<0.001 vs CYT) through a decrease in iNOS mRNA (p<0.01 vs CYT) and its protein expression (p<0.01 vs CYT). IL-1βlow reduces CYT-triggered NF-κB nuclear translocation (p<0.05 vs CYT). IL-1βlow hampers the increase in CHOP expression (p<0.001 vs CYT; by WB), decreases the mRNA expression of DP5 (p<0.05 vs CYT), PUMA (p<0.05 vs CYT), Bax/Bcl-2 ratio (p<0.01 vs CYT) and cleaved caspase-3 (p<0.001 vs CYT; by WB). Our study demonstrates that β-cells possess the capability to activate an adaptive stress response mediated by IL-1β in response to inflammatory stimuli. Approaches aimed at bolstering this resilient response provide a novel therapeutic avenue to enhance the functionality and viability of β-cells, ultimately mitigating the adverse inflammatory conditions associated with diabetes.Supported by ANCYPT-FONCYT (PICT -2018-1577 / -2018-0719), and partially by FPREDM 2023. Presentation: 6/2/2024