Nitric oxide mediates cytokine-induced inhibition of insulin secretion by human islets of Langerhans.

Abstract

Cytokines have been implicated s immunological effector molecules that mediate beta cell destruction asciated with insulin-dependent diabetes mellitus. In this report we demonstrate that the cytokine combination of human recombinant interieukin lp (IL-1*), tumor necrosis factor a (TNF-a), and interferon y (IFN-y) induces the formation of nitric oxide by human islets. This combination of cytokines stimulates both the formation of the nitric oxide derivative, nitrite, and the accumulation of cGMP by human iWets. The nitric oide synthase inhibitor NG.monomethyl-L-argIne prevents formation of both cGMP and nitrite. IL-1,B and IFN-y are sufcient to induce nitric oide formation by human islets, whereas TNF-a potentiates nitrite production. This combination of cytokines (IL-1f3, TNF-a, and IFN-y) also influences insulin secretion by human idets. Pretreatment of human iWets with low concentrations of this cytokne combination (IL-lp at 15 units/ml, 0.7 nM TNF-a, and IFN-y at 150 units/ml) appears to slightly stimulate insulin secretion. Higher concentrations (IL-l1 at 75 units/nl, 3.5 nM TNF-a, and IFN-yat 750 units/ml) inhibit inlin secretion from human islets, and the inhibitory effect is prevented by NG-monomethyl-L-argine. This higher concentration of cytokines also induces the formation of an electron paramagnetic resonance-detectable g = 2.04 axial feature by human islets that is characteristic of the formation of an iron-diho-dinitrosyl complex. The formation of this complex is prevented by NG-monomethyl-L-arginine, thus confirming that this cytokine combination induces the formation of nitric oxide by human islets. These results indicate that nitric oxide mediates the inhibitory effects of cytoldnes on glucosestimulated insulin secretion by human Wets and suggest that nitric oidde may participate in beta-cell dysfunction associated with insulin-dependent diabetes mellitus.Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease characterized by specific destruction of the pancreatic islet beta cell (1). The destruction of beta cells is believed to be mediated by infiltrating lymphocytes. The ability of T cells to adoptively transfer diabetes in diabetesprone BB rats (2) and in the NOD mouse indicates that T cells participate in beta-cell destruction (3). Cytokines, released by infiltrating lymphocytes, have also been implicated as possible mediators of beta-cell destruction. Pretreatment of isolated rat islets with the cytokine human recombinant interleukin 1,B (IL-1*8) results in a concentration-and timedependent inhibition of glucose-stimulated insulin secretion that is followed by islet destruction after prolonged exposures to this cytokine (4, 5).The free-radical nitric oxide has been implicated as the cellular effector molecule that mediates the inhibitory and cytotoxic effects of IL-1,3 on rat islets (6). Pretreatment of rat islets for 18-24 hr with IL-1lB results in nearly complete inhibition of glucose-stimulated insulin secretion that is prevented by the nitric oxide synthase inhibitor...

Cytokines activate genes of the endocytotic pathway in insulin-producing RINm5F cells

“…1 and Table 2). This more pronounced change of the gene expression pattern in response to a combination of cytokines is a well-known characteristic of insulin-producing cells [6,26,27]. These results were confirmed and extended by a quantification of the gene expression using quantitative real time RT-PCR measurements.…”

Infection of intact human islets by a lentiviral vector

“…4,5,34,38 IL-1␤ promotes nitric oxide formation and Fas expression in ␤-cells and blockade of IL-1␤ in vivo with continuous IL-Ra infusion prevented diabetes in a genetically susceptible animal model. [6][7][8]39 The stably integrating nature of the lentiviral vector and the absence of immunogenicity in rat in vivo experiments compels us to pursue the lentiviral-IL-1Ra strategy in vivo.…”

Sensitivity of human pancreatic islets to peroxynitrite‐induced cell dysfunction and death

“…However, the present data showing similar susceptibility of human and rodent islets to peroxynitrite suggest that higher amounts of these 'defence' proteins are not sufficient to protect human islets against this reactive species. Peroxynitrite is formed by the interaction of nitric oxide with superoxide [7], and there is data suggesting that human pancreatic islets exposed in vitro to cytokines generate both these radicals [26,9,27]. Considering the high activity of SOD in human islets [23], it can be argued that the enzyme will remove superoxide and prevent peroxynitrite formation.…”