Pancreatic deletion of the interleukin-1 receptor disrupts whole body glucose homeostasis and promotes islet β-cell de-differentiation

• Main Authors: Susan J. Burke, Heidi M. Batdorf, David H. Burk, Thomas M. Martin, Tamra Mendoza, Krisztian Stadler, Wateen Alami, Michael D. Karlstad, Matthew J. Robson, Randy D. Blakely, Randall L. Mynatt, J. Jason Collier
• Format: Article
• Language: English
• Published: Elsevier 2018-08-01
• Series: Molecular Metabolism
• Online Access: http://www.sciencedirect.com/science/article/pii/S2212877818303041

Objective: Pancreatic tissue, and islets in particular, are enriched in expression of the interleukin-1 receptor type I (IL-1R). Because of this enrichment, islet β-cells are exquisitely sensitive to the IL-1R ligands IL-1α and IL-1β, suggesting that signaling through this pathway regulates health and function of islet β-cells. Methods: Herein, we report a targeted deletion of IL-1R in pancreatic tissue (IL-1RPdx1−/−) in C57BL/6J mice and in db/db mice on the C57 genetic background. Islet morphology, β-cell transcription factor abundance, and expression of the de-differentiation marker Aldh1a3 were analyzed by immunofluorescent staining. Glucose and insulin tolerance tests were used to examine metabolic status of these genetic manipulations. Glucose-stimulated insulin secretion was evaluated in vivo and in isolated islets ex vivo by perifusion. Results: Pancreatic deletion of IL-1R leads to impaired glucose tolerance, a phenotype that is exacerbated by age. Crossing the IL-1RPdx1−/− with db/db mice worsened glucose tolerance without altering body weight. There were no detectable alterations in insulin tolerance between IL-1RPdx1−/− mice and littermate controls. However, glucose-stimulated insulin secretion was reduced in islets isolated from IL-1RPdx1−/− relative to control islets. Insulin output in vivo after a glucose challenge was also markedly reduced in IL-1RPdx1−/− mice when compared with littermate controls. Pancreatic islets from IL-1RPdx1−/− mice displayed elevations in Aldh1a3, a marker of de-differentiation, and reduction in nuclear abundance of the β-cell transcription factor MafA. Nkx6.1 abundance was unaltered. Conclusions: There is an important physiological role for pancreatic IL-1R to promote glucose homeostasis by suppressing expression of Aldh1a3, sustaining MafA abundance, and supporting glucose-stimulated insulin secretion in vivo. Keywords: Cytokine, Glucose homeostasis, Inflammation, Insulin, Islet