Antiinflammatory activity of soluble guanylate cyclase: cGMP-dependent down-regulation of P-selectin expression and leukocyte recruitment

Abstract

Nitric oxide (NO) production by the vascular endothelium maintains an essential antiinflammatory, cytoprotective influence on the blood vessel wall. A key component of this activity is attributed to prevention of leukocyte-endothelial cell interactions, yet the underlying mechanisms remain unclear. The NO receptor, soluble guanylate cyclase (sGC), is expressed in endothelial cells but fulfils an unknown function. Therefore, we used intravital microscopy in mesenteric postcapillary venules from WT and endothelial nitric oxide synthase (eNOS) knockout (eNOS ؊/؊ ) mice, and an sGC activator (BAY 41-2272), to investigate a potential role for sGC in the regulation of adhesion molecule expression and leukocyte recruitment. Leukocyte rolling and adhesion was 6-fold greater in eNOS ؊/؊ than WT animals. BAY 41-2272 and the NO-donor, diethylamine-NONOate, reduced leukocyte rolling and adhesion in eNOS ؊/؊ mice to levels observed in WT animals. These effects were blocked by the sGC inhibitor ODQ [1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one], which itself caused a 6-fold increase in leukocyte rolling and adhesion in WT mice. Increased leukocyte rolling and adhesion in IL-1␤-treated mice was also inhibited by BAY 41-2272. Fluorescence-activated cell sorting analysis in vitro and a specific P-selectin neutralizing antibody in vivo revealed that selective down-regulation of P-selectin expression accounted for the antiadhesive effects of sGC activation. These data demonstrate that sGC plays a key antiinflammatory role by inhibiting P-selectin expression and leukocyte recruitment.endothelium ͉ intravital microscopy T he recruitment of immune cells to sites of tissue injury is an important facet of an inflammatory response and is thought to represent a multistage process involving leukocyte rolling, adhesion, and emigration. Each stage of this response is triggered by the expression of specific adhesion molecules on the surface of leukocytes, platelets, and the vascular endothelium (see ref. 1). The regulation of this process therefore plays a key role in the development of an inflammatory response; moreover, it is clear that the active suppression of leukocyte͞platelet activation under physiological conditions is paramount for maintenance of blood vessel integrity and patency. Nitric oxide (NO) production by the vascular endothelium exerts an important cytoprotective, antithrombotic influence on the blood vessel wall by preventing the activation and adherence of circulating cells and platelets (2-4). Loss of this inhibitory effect of NO, and other endothelium-derived mediators including prostacyclin (PGI 2 ), results in a change in the endothelial cell to a prothrombotic, proinflammatory phenotype. It is thought that such changes contribute to diseases such as sepsis and atherosclerosis, and restenosis after balloon angioplasty. Hence, therapeutic intervention to prevent leukocyte͞platelet activation may be beneficial in numerous inf lammatory cardiovascular pathologies.The mechanism underlying the antiplatelet activity of NO ha...

The impact of genome‐wide association studies on the pathophysiology and therapy of cardiovascular disease

“…Studies investigating the effect of sGC on plaque formation in mouse models are eagerly awaited. A protective role of sGC is thereby strongly suggested by studies showing that cGMP formation is reduced in neointimal lesions (Melichar et al , 2004) and that cGMP leads to down‐regulation of the expression of adhesion molecules for the recruitment of leucocytes into atherosclerotic plaques (Ahluwalia et al , 2004). The common variant associated with CAD (rs7692387) is located in an intron however, and the exact mechanism from genotype to phenotype at this locus thus far remains elusive.…”

C-type natriuretic peptide inhibits leukocyte recruitment and platelet-leukocyte interactions via suppression of P-selectin expression

“…Male WT and eNOS Ϫ/Ϫ mice (10-15 g; in-house colony) were anesthetized with diazepam (6 mg͞kg; s.c.) and Hypnorm (0.7 mg͞kg fentanyl citrate and 20 mg͞kg fluanisone; i.m.). Cautery incisions were made along the abdominal region, and the mesenteric vascular bed was exteriorized for intravital recording, as we have described (6). Mesenteries were superfused with bicarbonate buffer at 37°C (132 mM NaCl͞4.7 mM KCl͞1.2 mM MgSO 4 ͞17.9 mM NaHCO 3 ͞2.0 mM CaCl 2 , pH 7.4, gassed with 5% CO 2 ͞95% N 2 ) at a rate of 2 ml͞min.…”

Protective effect of arginine on oxidative stress in transgenic sickle mouse models

“…NO has important salutary physiological properties like vascular tone regulation, quenching reactive oxygen intermediates and inhibiting leukocyte recruitment in the microcirculation [2,15,17,22,27,29]. Depleted NO production in a transgenic-knockout (BERK) model is associated with increased tyrosine nitration [16], suggesting that hemolysis in this model may trigger the reported hemin-mediated nitrotyrosine formation in the presence of nitrite and hydrogen peroxide (H 2 O 2 ) [38].…”