Aspirin and diabetes: inhibition of amylin aggregation by nonsteroidal anti-inflammatory drugs

Islet amyloid polypeptide (amylin), cosecreted with insulin by the pancreatic beta-cells, has an important role in the regulation of islet cell hormone homeoastasis. Deposition of beta-sheet polypeptide fibrils into amyloid deposits is considered to be central to the pathology of a number of amyloidogenic disorders, including type-2 diabetes. Amyloid deposits comprised of beta-sheet fibrillar amylin observed in type-2 diabetics are cytotoxic and may have a prominent role in causing beta-cell dysfunction. The amyloidogenic process may impair beta-cell function before cell death and replacement by amyloid. Preservation of beta-cell viability and insulin secretion is a major objective in diabetic care. Using circular dichroism and Congo red absorption techniques we found that clinically relevant doses of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDS) prevented and also reversed the beta-sheet conformation of human amylin. The specific COX-2 inhibitors were less effective. The anti-inflammatory steroid prednisolone or the analgesic acetaminophen had no effect on amylin fibrillogenesis. This action of NSAIDS was similar to their inhibition of beta-sheet conformation of the Alzheimer protein, amyloid-beta. Aspirin, currently recommended for the prevention of cardiovascular complications in diabetic patients, may also ameliorate the disease process in diabetes by preserving the beta-cell function.