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J Autoimmun. 2003 Jun;20(4):303-12.

IL-1beta, IFN-gamma and TNF-alpha increase vulnerability of pancreatic beta cells to autoimmune destruction.

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  • 1Institute of Pathophysiology, Ernst-Moritz-Arndt-University of Greifswald, Greifswalder Strasse 11b, Karlsburg 17495, Germany. wachlin@uni-greifswald.de

Abstract

In the pathogenesis of type-1 diabetes insulin-producing beta-cells are destroyed by cellular autoimmune processes. The locality of beta-cell destruction is the inflamed pancreatic islet. During insulitis cytokines released from islet-infiltrating mononuclear cells affect beta-cells at several levels. We investigated whether cytokine-induced beta-cell destruction is associated with changes in the expression of the surface receptors intercellular adhesion molecule (ICAM)-1 and Fas. Islets from diabetes-prone and congenic diabetes-resistant BB rats were exposed to interleukin (IL)-1beta alone or in combination with interferon (IFN)-gamma plus tumour necrosis factor (TNF)-alpha. Cytokines decreased islet insulin content, suppressed glucose stimulated insulin secretion and generated enhanced amounts of nitric oxide and DNA-strand breaks. While no membrane alterations of IL-1beta treated islets cells were detectable, the cytokine combination caused damage of cell membranes. Independent of diabetes susceptibility IL-1beta treated islet beta-cells expressed a significantly increased amount of ICAM-1 on their surfaces which was not further increased by IFN-gamma+TNF-alpha. However, IL-1beta induced Fas expression was significantly enhanced only on beta-cells from diabetes-prone BB rats. From these results we suggest that IL-1beta mediates the major stimulus for ICAM-1 induction which is possibly a necessary but not sufficient step in the process of beta-cell destruction. Obviously, the additional enhancement of Fas expression on the surface of beta-cells is important for destruction. The combined action of all three cytokines induced the expression of Fas on the beta-cell surface independent of diabetes susceptibility, indicating that such a strong stimulus in vitro may induce processes different from the precise mechanisms of beta-cell destruction in vivo.

PMID:
12791316
[PubMed - indexed for MEDLINE]
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