IBRI RESEARCH PUBLISHED: Pro-Inflammatory Cytokines Induce Insulin and Glucagon Double Positive Human Islet Cells That Are Resistant to Apoptosis

February 19, 2021

Source: Biomolecules

Abstract

The presence of islet cells double positive for insulin and glucagon (Ins⁺/Glu⁺) has been described in the pancreas from both type 2 (T2D) and type 1 (T1D) diabetic subjects.

We studied the role of pro-inflammatory cytokines on the occurrence, trajectory and characteristics of Ins⁺/Glu⁺ cells in human pancreatic islets. Pancreas samples, isolated islets and dispersed islet cells from 3 T1D and 11 non-diabetic (ND) multi-organ donors were studied by immunofluorescence, confocal microscopy and/or electron microscopy. ND islet cells were exposed to interleukin-1β and interferon-γ for up to 120 h.

In T1D islets, we confirmed an increased prevalence of Ins⁺/Glu⁺ cells. Cytokine-exposed islets showed a progressive increase of Ins⁺/Glu⁺ cells that represented around 50% of endocrine cells after 120h. Concomitantly, cells expressing insulin granules only decreased significantly over time, whereas those containing only glucagon granules remained stable. Interestingly, Ins⁺/Glu⁺ cells were less prone to cytokine-induced apoptosis than cells containing only insulin. Cytokine-exposed islets showed down-regulation of β-cell identity genes.

In conclusion, pro-inflammatory cytokines induce Ins⁺/Glu⁺ cells in human islets, possibly due to a switch from a β- to a β-/α-cell phenotype. These Ins⁺/Glu⁺ cells appear to be resistant to cytokine-induced apoptosis.

To read the complete research article, go to Biomolecules.