Nitric Oxide Is a Mediator of Antiproliferative Effects Induced by Proinflammatory Cytokines on Pancreatic Beta Cells

Laura Quintana-Lopez,Carmen Segundo,Manuel Aguilar-Diosdado,Alberto Cebada-Aleu,Alfonso Lechuga-Sancho,Manuel Blandino-Rosano,Gonzalo Perez-Arana

doi:10.1155/2013/905175

Laura Quintana-Lopez, Carmen Segundo + Show 5 more

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https://doi.org/10.1155/2013/905175

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Abstract

Nitric oxide (NO) is involved in several biological processes. In type 1 diabetes mellitus (T1DM), proinflammatory cytokines activate an inducible isoform of NOS (iNOS) in β cells, thus increasing NO levels and inducing apoptosis. The aim of the current study is to determine the role of NO (1) in the antiproliferative effect of proinflammatory cytokines IL-1β, IFN-γ, and TNF-α on cultured islet β cells and (2) during the insulitis stage prior to diabetes onset using the Biobreeding (BB) rat strain as T1DM model. Our results indicate that NO donors exert an antiproliferative effect on β cell obtained from cultured pancreatic islets, similar to that induced by proinflammatory cytokines. This cytokine-induced antiproliferative effect can be reversed by L-NMMA, a general NOS inhibitor, and is independent of guanylate cyclase pathway. Assays using NOS isoform specific inhibitors suggest that the NO implicated in the antiproliferative effect of proinflammatory cytokines is produced by inducible NOS, although not in an exclusive way. In BB rats, early treatment with L-NMMA improves the initial stage of insulitis. We conclude that NO is an important mediator of antiproliferative effect induced by proinflammatory cytokines on cultured β cell and is implicated in β-cell proliferation impairment observed early from initial stage of insulitis.

Highlights

Type 1 diabetes mellitus (T1DM) is characterized by a loss of beta cell mass due to an autoimmune process
To determine the role of Nitric oxide (NO) donors on βcell proliferation, pancreatic islets were treated with proinflammatory cytokines or different concentrations of NO donors SNAP and DETA, alone or in combination with the caspase-3 inhibitor z-VAD-fmk. β-cell proliferation measured by BrdU incorporation showed that the NO donors, diethylenetriamine/nitric oxide adduct (DETA-NO) (Figure 1(a)) and SNAP (Figure 1(b)) exert an antiproliferative action on β cells in a dose-dependent manner
To determine the contribution of NO to the antiproliferative effect of proinflammatory cytokines on pancreatic β cells, pancreatic islets were cultured over a 48 h period and treated with proinflammatory cytokines, alone or in the presence of L-NMMA

Summary

Introduction

Type 1 diabetes mellitus (T1DM) is characterized by a loss of beta cell mass due to an autoimmune process. In a phase prior to the onset, immune cells infiltrate the islets creating an inflammatory microenvironment responsible for the βcell-specific toxicity. Proinflammatory cytokines, such as interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNFα), and interferon gamma (IFN-γ), secreted by activated lymphocytes and macrophages during insulitis, induce NFkB mediated iNOS expression which has a key role in β-cell apoptosis in the early T1DM stage [1]. There are three different tissuespecific NOS isoforms: Ca2+/calmodulin-independent and inducible NOS (iNOS), neuronal NOS (nNOS), and endothelial NOS (eNOS) These last two isoforms exhibit constitutive expression and Ca2+/calmodulin-dependent activity

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