2124-P: The Tissue Plasminogen Activator (tPA)/Plasmin System Reduces Amyloid Formation by Cleaving Human Islet Amyloid Polypeptide (hIAPP)

Type 2 diabetes is characterized by islet amyloid deposition, which is associated with β-cell loss. hIAPP is the unique peptide component of these deposits. We previously found that expression of tPA, the initiator of fibrinolysis, is upregulated in islets by amyloid formation in vitro. As plasmin, the proteolytic product of tPA activity, cleaves Aβ and attenuates amyloid deposition in Alzheimer’s disease, we hypothesized that the increase in islet tPA by amyloid deposition serves a protective function by generating plasmin to limit further accumulation of hIAPP. We therefore sought to determine whether the tPA/plasmin system reduces amyloid formation by hIAPP and, if so, what islet cell type produces tPA. Using a thioflavin T assay, we found 4 µM plasmin abrogated 20 µM hIAPP fibril formation by 91.6±0.9% (n=5; p In summary, plasmin rapidly degrades hIAPP, curbing its aggregation into amyloid. As tPA is expressed in macrophages, enhancing its activity or its production by islet macrophages may represent a novel strategy to generate plasmin, cleave hIAPP and thus reduce islet amyloid formation and β-cell loss. Disclosure N. Esser: None. M.F. Hogan: None. A. Aplin: None. A.T. Templin: None. S. El-Osta: None. D. Raleigh: None. J.S. Edgar: None. S. Zraika: Research Support; Self; Novartis Pharmaceuticals Corporation. R.L. Hull: Research Support; Self; Boehringer Ingelheim Pharmaceuticals, Inc. S.E. Kahn: Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Intarcia Therapeutics, Inc., Janssen Pharmaceuticals, Inc., Merck & Co., Inc., Novo Nordisk A/S. Consultant; Self; Neurimmune. Other Relationship; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Merck & Co., Inc., Novo Nordisk A/S. Funding U.S. Department of Veterans Affairs (BX001060); National Institutes of Health (GM078114); Belgian American Educational Foundation; Société Francophone du Diabète