Single-cell transcriptomics reveals a role for pancreatic duct cells as potential mediators of inflammation in diabetes mellitus

Inflammation of the pancreas contributes to the development of diabetes mellitus. Although it is well-accepted that local inflammation leads to a progressive loss of functional beta cell mass that eventually causes the onset of the disease, the development of islet inflammation remains unclear. Here, we used single-cell RNA sequencing to explore the cell type-specific molecular response of primary human pancreatic cells exposed to an inflammatory environment. We identified a duct subpopulation presenting a unique proinflammatory signature among all pancreatic cell types. Overall, the findings of this study point towards a role for duct cells in the propagation of islet inflammation, and in immune cell recruitment and activation, which are key steps in the pathophysiology of diabetes mellitus. Overall design: Islets from 3 diabetic donors and 1 Wolfram syndrome donor were cultured in CMRL 1066 medium with 5.5 mmol/L of glucose, 10% fetal calf serum, 20mg/mL ciprofloxacin, 50 mg/mL gentamycin, 2mmol/L L-glutamine, 10mmol/L HEPES and 1.2 mg/mL nicotinamide. Islets and islet-depleted tissue were cultured at 37°C in a 5% CO2- humidified atmosphere. Medium was refreshed upon receipt and every 2 days thereafter. The islet-depleted tissue was kept in its supplemented CMRL 1066 medium, then washed and stored overnight at 4°C in advanced DMEM/F12 with trypsin inhibitor (100ug/ml) before processing immediately in the morning.