Endocrine Abstracts

Cardiovascular diseases account for more deaths in the Western world than from any other cause. Atherosclerosis has a chronic inflammatory component involving Th1 pro-inflammatory cytokines such as IFN-γ, which is known to induce endothelial cell inflammatory responses. CNP, acting via its receptors to elevate intracellular cGMP, is produced by endothelium and endocardium and is upregulated in atherosclerosis. It is believed to be protective yet its role in vascular inflammation is poorly understood. The aim of this study was to investigate effects of CNP on human endothelial cell inflammatory responses following IFN-γ stimulation. HUVECs were treated with either IFN-γ (10 ng/ml) or CNP (100 nm), or both in combination, followed by analysis by flow cytometry for expression of MHC class 1 and ICAM-1. In experiments, CNP was substituted by the cGMP donor 8-Bromoguanosine 3′, 5′-cyclic monophosphate. To determine whether CNP also modulates the anti-microbial effects of IFN-γ in HUVEC, expression of indolamine deoxygenase (IDO) was measured by RT-PCR. To determine whether CNP directly affects the signalling pathways activated by IFN-γ the phosphorylation of STAT-1b was analysed by western blotting and immunodetection. IFN-γ significantly increased expression of both MHC class 1 and ICAM-1, which was significantly inhibited by CNP or 8-Br-cGMP. CNP also reduced IFN-γ mediated phosphorylation of STAT-1b and total levels of STAT-1b and enhanced IFN-γ mediated expression of mRNA for IDO. CNP downmodulated IFN-γ induced pro-inflammatory gene expression in human endothelial cells via a cGMP-mediated pathway, as well as upregulating IFN-γ mediated expression of anti-microbial genes, which are considered to be protective in a chronic inflammatory response. Thus, CNP has a protective role in vascular inflammation and novel therapeutic strategies for CVD based on upregulation of endothelial CNP expression could reduce chronic EC inflammation.