54-OR: Nitric Oxide Attenuates Viral Replication in Pancreatic ß-Cells through an Inhibition of Mitochondrial Oxidative Metabolism

Abstract

Viral infection has been identified as an environmental factor that may play a role in initiating the destruction of pancreatic β-cells during the development of autoimmune diabetes. We have identified a pro-inflammatory response activated in pancreatic islets in response to infection with encephalomyocarditis virus (EMCV). In response to the local production of cytokines such as IL-1 by resident islet macrophages, β-cells produce nitric oxide, a free radical with known antiviral activity. Nitric oxide has been characterized both as a potent antiviral molecule and as a mediator of β-cell dysfunction and damage and so we investigated the role of nitric oxide in controlling β-cell viability in the context of EMCV infection. We find that nitric oxide, either supplied exogenously with donor compounds or produced endogenously in response to cytokine treatment, attenuates EMCV replication and protects β-cells against EMCV-mediated death. These protective actions of nitric oxide are restricted to conditions in which nitric oxide is produced at low micromolar levels (consistent with the levels of nitric oxide generated by iNOS) and are associated with the ability of nitric oxide to impair mitochondrial oxidation and decrease ATP levels in β-cells. Treatment with rotenone, an inhibitor of complex I of the electron transport chain, likewise attenuates EMCV replication in β-cells, which are reliant on oxidative metabolism for ATP generation, but not in fibroblasts, which can sustain ATP levels via glycolysis alone. These findings suggest a mechanism of protection restricted to β-cells where nitric oxide production attenuates viral replication by inhibiting oxidative metabolism and depleting cellular stores of ATP, supporting a protective role for nitric oxide in the response of β-cells to viral infection. Disclosure J. Stafford: None. J.A. Corbett: None. Funding American Heart Association (17PRE3253000); National Institutes of Health (DK052194, AI44458)