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

Abstract

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-1R ^Pdx1−/− ) 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-1R ^Pdx1−/− with db/db mice worsened glucose tolerance without altering body weight. There were no detectable alterations in insulin tolerance between IL-1R ^Pdx1−/− mice and littermate controls. However, glucose-stimulated insulin secretion was reduced in islets isolated from IL-1R ^Pdx1−/− relative to control islets. Insulin output in vivo after a glucose challenge was also markedly reduced in IL-1R ^Pdx1−/− mice when compared with littermate controls. Pancreatic islets from IL-1R ^Pdx1−/− 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.

Highlights

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  Pancreatic deletion of IL-1R impairs glucose tolerance in young and old male mice.

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  Pancreatic deletion of IL-1R worsens glucose tolerance in obese db/db mice.

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  Deletion of IL-1R triggers expression of the de-differentiation marker Aldh1a3.

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  IL-1 signaling in pancreatic tissue influences islet health and function.