Immunization with streptozotocin-treated NOD mouse islets inhibits the onset of autoimmune diabetes in NOD mice Gina R. Rayat a , Ray V. Rajotte a,b , James G. Lyon a , Jannette M. Dufour a , Brad V. Hacquoil a , Gregory S. Korbutt a,b, * a Surgical-Medical Research Institute, University of Alberta, 1074 B Dentistry/Pharmacy Building, Edmonton, AB, Canada T6G 2N8 b Department of Surgery, University of Alberta, 1074 B Dentistry/Pharmacy Building, Edmonton, AB, Canada T6G 2N8 Received 18 December 2002; revised 8 April 2003; accepted 2 May 2003 Abstract In this study, we determined whether a single intraperitoneal injection of NOD islets exposed to streptozotocin (STZ; 5 mmol/l) in vitro could prevent onset of diabetes in female NOD mice. Pre-diabetic female NOD mice were injected with saline or islets exposed to either STZ or citrate buffer alone. Single injection of STZ-exposed islets significantly (P<0.03) decreased the incidence of diabetes in pre-diabetic NOD mice compared to control groups. At 40 weeks of age, the onset of diabetes in NOD mice injected with STZ-treated islets was 16% (3/19) compared to 88% (14/16) in mice that received islets exposed to citrate buffer and 84% (26/31) in those mice injected with saline. Histological examination of the pancreases from normoglycemic mice given STZ-treated islets revealed numerous intact islets devoid of mononuclear cell infiltration while pancreases from control groups contained few intact islets infiltrated with mononuclear cells. This study demonstrates that immunization of pre-diabetic female NOD mice with syngeneic islets exposed to STZ prevents insulitis and onset of autoimmune diabetes. Our data suggest that exposure of islets to STZ may possibly induce the release of soluble antigens and/or cause an antigenic change in pancreatic  cells that subsequently results in immunization of pre-diabetic NOD mice.  2003 Elsevier Ltd. All rights reserved. Keywords: NOD mice; Streptozotocin; Type 1 diabetes 1. Introduction Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease resulting from the destruction of insulin-producing  cells. Animal models of IDDM such as the nonobese diabetic (NOD) mouse and BioBreeding (BB) rat have been utilized to enhance our understand- ing of the pathogenesis of IDDM. The NOD mouse spontaneously develops diabetes due to progressive lym- phocytic infiltration of the islets starting at approxi- mately 5 weeks of age and subsequent destruction of the pancreatic  cells. Experimental diabetes can also be induced chemically using high doses (160 to 250 mg/kg) of Streptozotocin (STZ) in several animal models of islet transplantation due to its direct cytotoxic effect on pancreatic  cells. The selectivity of STZ for  cells has been shown to rely on its glucose moiety that allows it to enter the  cells via the low affinity glucose transporter (GLUT2) [1]. STZ causes DNA damage, thereby depleting NAD+ [2], which in turn inhibits insulin biosynthesis and secretion and leads to  cell death through energy depletion [3]. Studies by Morgan et al. [4] demonstrated that treat- ment of pancreatic  cells with STZ resulted in DNA damage and subsequent induction of apoptosis thereby suggesting that the diabetogenic action of STZ involves induction of apoptosis in pancreatic  cells. In contrast, multiple injections of subdiabetogenic doses (40 mg/kg) of STZ can also produce pancreatic insulitis, with progression to nearly complete  cell destruction and diabetes mellitus [5–10]. The timing and appearance of the inflammatory islet lesions suggest that multiple low dose administration of STZ acts by initiating a * Corresponding author. Tel.: +1-780-492-4657; fax: +1-780-492-1627. E-mail address: Korbutt@ualberta.ca (G.S. Korbutt). Journal of Autoimmunity 21 (2003) 11–15 www.elsevier.com/locate/issn/08968411 0896-8411/03/$ - see front matter  2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0896-8411(03)00080-5