Abstract Body: Introduction: Pancreatic islets are highly vascularized crucial for glucose and metabolic homeostasis, with endothelial cells (ECs) playing key roles in nutrient exchange and immune regulation. While diabetes-induced EC dysfunction is well-known, the active role of ECs in modulating islet function is unclear. We previously showed EC-specific AGO1 inhibition (an anchoring protein of the RNA-induced silencing complex) leads to an anti-obesity phenotype in mice, highlighting an important role of EC and adipocytes. Here, we studied the impact of inhibition of EC-AGO1 inhibition on islet function, vascular inflammation, β-cell regeneration, and diabetes outcomes in human cells and mouse models.
Methods: We generated an inducible EC-specific AGO1 knockout (iKO) mouse model, characterized the baseline phenotype and evaluated islet function after streptozotocin (STZ)-induced β-cell damage and hyperglycemia. We assessed body weight, glucose, and insulin levels, along with β-cell function (insulin), vascular density (CD31), and immune infiltration (F4/80) via immunofluorescence. Islet transplant experiments measured engraftment and glucose control in hyperglycemic mice. RNA-seq was performed on ECs from STZ-treated WT and iKO pancreases. Microvascular ECs treated with pro-inflammatory cytokines (TNF-α, IL-1β, IFN-γ) were used to study AGO1-KD effects on inflammatory functions using qPCR and Luminex assays.
Results: iKO mice showed no baseline metabolic differences but had attenuated STZ-induced hyperglycemia and body weight loss with improved β-cell mass, vascular integrity, and reduced immune infiltration. Pancreatic EC RNA-seq revealed lower pro-inflammatory expression (Cxcl2, Ccl5, Il1b) and higher EC functional genes (Pecam1, Nos3, Cdh5) in iKO mice. AGO1-KD ECs showed reduced IL-6 and IL-8 production. iKO islets demonstrated improved engraftment and glucose lowering effects compared to WT islets in hyperglycemic mice.
Conclusion: Our findings position EC-AGO1 as a key regulator of EC homeostasis essential for the pancreatic islet function. Inhibition of EC-AGO1 promotes EC fitness and protects against β-cell damage and promotes islet engraftment in the context of diabetes. Our study points toward the therapeutic potential of targeting EC-AGO1 as a novel target for vascular-based interventions in metabolic diseases.