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Glutathione peroxidase-1 modulates lipopolysaccharide-induced adhesion molecule expression in endothelial cells by altering CD14 expression.

ABSTRACT: CD14 contributes to LPS signaling in leukocytes through formation of toll-like receptor 4/CD14 receptor complexes; however, a specific role for endogenous cell-surface CD14 in endothelial cells is unclear. We have found that suppression of glutathione peroxidase-1 (GPx-1) in human microvascular endothelial cells increases CD14 gene expression compared to untreated or siControl (siCtrl)-treated conditions. Following LPS treatment, GPx-1 deficiency augmented LPS-induced intracellular reactive oxygen species accumulation, CD14 expression, and intercellular adhesion molecule-1 (ICAM-1) mRNA and protein expression compared to LPS-treated control cells. GPx-1 deficiency also transiently augmented LPS-induced vascular cell adhesion molecule-1 (VCAM-1) expression. Adenoviral overexpression of GPx-1 significantly diminished LPS-mediated responses in adhesion molecule expression. Consistent with these findings, LPS responses were also greater in endothelial cells derived from GPx-1-knockout mice, whereas adhesion molecule expression was decreased in cells from GPx-1-overexpressing transgenic mice. Knockdown of CD14 attenuated LPS-mediated up-regulation of ICAM-1 and VCAM-1 mRNA and protein, and it mitigated the effects of GPx-1 deficiency on LPS-induced adhesion molecule expression. Taken together, these data suggest that GPx-1 modulates the endothelial cell response to LPS, in part, by altering CD14-mediated effects.

SUBMITTER: Lubos E

PROVIDER: S-EPMC2887263 | biostudies-literature | 2010 Jul

REPOSITORIES: biostudies-literature

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Glutathione peroxidase-1 modulates lipopolysaccharide-induced adhesion molecule expression in endothelial cells by altering CD14 expression.

Lubos Edith E Mahoney Christopher E CE Leopold Jane A JA Zhang Ying-Yi YY Loscalzo Joseph J Handy Diane E DE

FASEB journal : official publication of the Federation of American Societies for Experimental Biology 20100310 7

CD14 contributes to LPS signaling in leukocytes through formation of toll-like receptor 4/CD14 receptor complexes; however, a specific role for endogenous cell-surface CD14 in endothelial cells is unclear. We have found that suppression of glutathione peroxidase-1 (GPx-1) in human microvascular endothelial cells increases CD14 gene expression compared to untreated or siControl (siCtrl)-treated conditions. Following LPS treatment, GPx-1 deficiency augmented LPS-induced intracellular reactive oxyg ...[more]

PMID: 20219985

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Project description:Circulating triglyceride-rich lipoproteins (TGRL) from hypertriglyceridemic subjects exacerbate endothelial inflammation and promote monocyte infiltration into the arterial wall. We have recently reported that TGRL isolated from human blood after a high-fat meal can elicit a pro- or anti-atherogenic state in human aortic endothelial cells (HAEC), defined as up- or down-regulation of VCAM-1 expression in response to tumor necrosis factor alpha (TNF?) stimulation, respectively. A direct correlation was found between subjects categorized at higher risk for cardiovascular disease based upon serum triglycerides and postprandial production of TGRL particles that increased VCAM-1-dependent monocyte adhesion to inflamed endothelium. To establish how TGRL metabolism is linked to VCAM-1 regulation, we examined endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) pathways. Regardless of its atherogenicity, the rate and extent of TGRL internalization and lipid droplet formation by HAEC were uniform. However, pro-atherogenic TGRL exacerbated ER membrane expansion and stress following TNF? stimulation, whereas anti-atherogenic TGRL ameliorated such effects. Inhibition of ER stress with a chemical chaperone 4-phenylbutyric acid decreased TNF?-induced VCAM-1 expression and abrogated TGRL's atherogenic effect. Activation of ER stress sensors PKR-like ER-regulated kinase (PERK) and inositol requiring protein 1? (IRE1?), and downstream effectors including eukaryotic initiation factor-2? (eIF2?), spliced X-box-binding protein 1 (sXBP1) and C/EBP homologous protein (CHOP), directly correlated with the atherogenic activity of an individual's TGRL. Modulation of ER stress sensors also correlated with changes in expression of interferon regulatory factor 1 (IRF-1), a transcription factor of Vcam-1 responsible for regulation of its expression. Moreover, knockdown studies using siRNA defined a causal relationship between the PERK/eIF2?/CHOP pathway and IRF-1-mediated VCAM-1 expression. We conclude that ER stress and the UPR contribute to the regulation of Vcam-1 transcription as a function of the atherogenic nature of TGRL.

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Glutathione peroxidase-1 modulates lipopolysaccharide-induced adhesion molecule expression in endothelial cells by altering CD14 expression.

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Glutathione peroxidase-1 modulates lipopolysaccharide-induced adhesion molecule expression in endothelial cells by altering CD14 expression.

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