Circulating levels of IL-1B+IL-6 cause ER stress and dysfunction in islets from prediabetic male mice.

Published

Journal Article

Elevated levels of circulating proinflammatory cytokines are associated with obesity and increased risk of type 2 diabetes, but the mechanism is unknown. We tested whether proinflammatory cytokines IL-1B+IL-6 at low picogram per milliliter concentrations (consistent with serum levels) could directly trigger pancreatic islet dysfunction. Overnight exposure to IL-1B+IL-6 in islets isolated from normal mice and humans disrupted glucose-stimulated intracellular calcium responses; cytokine-induced effects were more severe among islets from prediabetic db/db mice that otherwise showed no signs of dysfunction. IL-1B+IL-6 exposure reduced endoplasmic reticulum (ER) calcium storage, activated ER stress responses (Nos2, Bip, Atf4, and Ddit3 [CHOP]), impaired glucose-stimulated insulin secretion, and increased cell death only in islets from prediabetic db/db mice. Furthermore, we found increased serum levels of IL-1B and IL-6 in diabetes-prone mice at an age before hyperglycemia was exhibited, suggesting that low-grade systemic inflammation develops early in the disease process. In addition, we implanted normal outbred and inbred mice with subcutaneous osmotic mini-pumps containing IL-1B+IL-6 to mimic the serum increases found in prediabetic db/db mice. Both IL-1B and IL-6 were elevated in serum from cytokine-pump mice, but glucose tolerance and blood glucose levels did not differ from controls. However, when compared with controls, isolated islets from cytokine-pump mice showed deficiencies in calcium handling and insulin secretion that were similar to observations with islets exposed to cytokines in vitro. These findings provide proof of principle that low-grade systemic inflammation is present early in the development of type 2 diabetes and can trigger ER stress-mediated islet dysfunction that can lead to islet failure.

Full Text

Cited Authors

  • O'Neill, CM; Lu, C; Corbin, KL; Sharma, PR; Dula, SB; Carter, JD; Ramadan, JW; Xin, W; Lee, JK; Nunemaker, CS

Published Date

  • September 2013

Published In

Volume / Issue

  • 154 / 9

Start / End Page

  • 3077 - 3088

PubMed ID

  • 23836031

Pubmed Central ID

  • 23836031

Electronic International Standard Serial Number (EISSN)

  • 1945-7170

International Standard Serial Number (ISSN)

  • 0013-7227

Digital Object Identifier (DOI)

  • 10.1210/en.2012-2138

Language

  • eng