Nitric oxide detoxification mechanisms of Neisseria meningitidis enhance CGMP activity during infection of human macrophages

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• 作者：Risat ul Haque ; Jay Laver ; David Dockrell ; Rob Read
• 刊名：Nitric Oxide
• 出版年：2012
• 出版时间：15 July, 2012
• 年：2012
• 卷：27
• 期：supp_S
• 页码：S45-S46
• 全文大小：1K

文摘

Rationale and hypothesis

Increased bacterial load in meningococcal sepsis is positively correlated with severe disease and increased concentrations of circulating nitric oxide (NO) metabolites. As a vasorelaxant, NO binds to the soluble guanylyl cyclase (sGC), found in abundance in vascular smooth muscle and activates cGMP, a secondary messenger important for vasodilation, platelet inhibition etc. We previously showed that NO detoxification mechanisms of N. meningitidis reduce abundance of NO species in mammalian cells, so we tested the hypothesis that this activity alters cellular cGMP activity.

Objectives

To examine the effect of bacterial NO metabolism on cGMP produced by Human macrophages (MDM) and endothelial (HMEC-1) cells.

Methodology

Human MDMs and HMEC-1 cells were exposed to NO donor spermine NONOate, together with the phosphodiesterase inhibitor IBMX and a soluble guanyl cyclase sensitiser BAY412275. Cells were infected with wild type Neisseria meningitidis (serogroup B strain MC58), a mutant strain for putative Arginine Decarboxylase (¦¤NMB0468) and an isogenic mutant unable to detoxify NO (¦¤norB). After two hours, cells were lysed and cGMP was measured by ELISA.

Findings

In the presence of spermine NONOate, IBMX and BAY 412275, the level of cGMP was detected at 5.69 pmol/mg protein in human MDMs; without these agonists no cGMP was detected (p < 0.0001, n = 4). During infection of MDMs with wild type N. meningitidis the level of cGMP production was enhanced compared to ¦¤norB (p = 0.0693, n = 8) and compared with ¦¤NMB0468 (p = 0.5605, n = 7). These preliminary data suggest that NO metabolism by N. meningitidis dysregulates cGMP activity in human cells.