Heparan Sulfate Mimicking Glycopolymer Prevents Pancreatic ß Cell Destruction and Suppresses Inflammatory Cytokine Expression in Islets under the Challenge of Upregulated Heparanase.

ABSTRACT

Diabetes is a chronic disease in which the levels of blood glucose are too high because the body does not effectively produce insulin to meet its needs or is resistant to insulin. ß Cells in human pancreatic islets produce insulin, which signals glucogen production by the liver and causes muscles and fat to uptake glucose. Progressive loss of insulin-producing ß cells is the main cause of both type 1 and type 2 diabetes. Heparan sulfate (HS) is a ubiquitous polysaccharide found at the cell surface and in the extracellular matrix (ECM) of a variety of tissues. HS binds to and assembles proteins in ECM, thus playing important roles in the integrity of ECM (particularly basement membrane), barrier function, and ECM-cell interactions. Islet HS is highly expressed by the pancreatic ß cells and critical for the survival of ß cells. Heparanase is an endoglycosidase and cleaves islet HS in the pancreas, resulting in ß-cell death and oxidative stress. Heparanase could also accelerate ß-cell death by promoting cytokine release from ECM and secretion by activated inflammatory and endothelial cells. We demonstrate that HS-mimicking glycopolymer, a potent heparanase inhibitor, improves the survival of cultured mouse pancreatic ß cells and protects HS contents under the challenge of heparanase in human pancreatic islets. Moreover, this HS-mimicking glycopolymer reduces the expression levels of cytokines (IL8, IL1ß, and TNFα) and the gene encoding Toll-like Receptor 2 (TLR2) in human pancreatic islets.