RESUMO
We have previously demonstrated that exogenous nitric oxide (NO) inhibited anti-IgE-mediated histamine release from human cultured mast cells. In the current study, we further investigated if syntheses of eicosanoids and cytokines were also suppressed by NO donors and evaluated if activation of soluble guanylyl cyclase (sGC) was an underlying mechanism. The effects of the NO donor diethylamine NONOate (DEA/NO) on IgE-dependent syntheses of eicosanoids (prostaglandin D(2) and cysteinyl leukotrienes) and cytokines (tumor necrosis factor-alpha and interleukin-8) from buffy coat derived human cultured mast cells were examined. The effects of sGC related agents on human mast cell activation were studied by measuring histamine release. DEA/NO (10(-7)-10(-4)M) dose-dependently inhibited anti-IgE induced release of histamine, eicosanoids and cytokines. It could also significantly increase intracellular cyclic guanosine monophosphate (cGMP) but reduce anti-IgE induced activation of ERK1/2, JNK1/2 and NF-kappaB. The inhibition of anti-IgE induced histamine release by DEA/NO was reversed by the sGC inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10(-7)M) and the cGMP-dependent protein kinase (PKG) inhibitor, Rp-8-(4-Chlorophenylthio)-guanosine-3',5'-cyclic monophosphorothioate (Rp-8-pCPT-cGMPS, 10(-5)M). The current study confirmed the inhibitory action of exogenous NO on immunological activation of human mast cells. We also provided evidence for the first time that the activation of the sGC-cGMP-PKG pathways together with the suppression of phosphorylation of MAPKs and NF-kappaB contributed to the mast cell modulating action of NO in human.
