Faculty Collaboration Database

LPS-mediated endothelial activation in pulmonary endothelial cells: role of Nox2-dependent IKK-β phosphorylation. Am J Physiol Lung Cell Mol Physiol 2013 Mar 15;304(6):L445-55

Date

01/22/2013

Pubmed ID

23333803

Pubmed Central ID

PMC3602745

DOI

10.1152/ajplung.00261.2012

Scopus ID

2-s2.0-84877105539 (requires institutional sign-in at Scopus site)   55 Citations

Abstract

Lipopolysaccharide (LPS)-mediated endothelial activation contributes to lung inflammation and alveolar remodeling seen in premature infants with bronchopulmonary dysplasia (BPD). The mechanisms underlying LPS-mediated oxidative stress and proinflammatory signaling in human pulmonary microvascular endothelial cells (HPMEC) remain unclear. We hypothesized that NADPH oxidase (Nox) mediates LPS-induced endothelial activation in HPMEC by regulating phosphorylation of Toll-like receptor (TLR) pathway proteins. LPS-induced expression of intercellular adhesion molecule 1 (ICAM-1) was associated with increased 2-OH-E(+) (marker for superoxide formation) levels and was attenuated by apocynin and the Nox inhibitor, VAS2870. LPS triggered membrane translocation of p67phox, suggesting activation of Nox2. Silencing Nox2, but not Nox4, suppressed LPS-induced ICAM-1 expression in HPMEC. Immunoprecipitation studies showed that inhibitor of κ-B kinase-β (IKK-β) serine phosphorylation induced by LPS was inhibited by Nox2 silencing. We examined whether Nox2-dependent, LPS-mediated IKK-β phosphorylation was regulated by protein phosphatase 2A (PP2A) or TGF-β associated kinase-1 (TAK1) in HPMEC. LPS increased PP2A activity in HPMEC, and inhibition of PP2A did not alter LPS-mediated ICAM-1 expression but attenuated IKK-β phosphorylation. TAK1 inhibition decreased LPS-induced ICAM-1 expression in HPMEC, and Nox2 silencing attenuated LPS-mediated TAK1 phosphorylation (Thr184/187). We demonstrate that Nox2 regulates LPS-mediated endothelial activation in pulmonary endothelial cells by modulating phosphorylation of key kinases in the TLR signaling cascade. Our data support a novel mechanism by which Nox-dependent signaling regulates proinflammatory signaling in pulmonary endothelial cells. Inhibition of vascular Nox may potentially limit lung injury and alveolar remodeling caused by infections in BPD.

Author List

Menden H, Tate E, Hogg N, Sampath V

Author

Neil Hogg PhD Associate Dean, Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Cells, Cultured
Endothelial Cells
Gene Expression
Gene Knockdown Techniques
Humans
I-kappa B Kinase
Intercellular Adhesion Molecule-1
Isoenzymes
Lipopolysaccharides
Lung
MAP Kinase Kinase Kinases
Membrane Glycoproteins
Microvessels
NADPH Oxidase 2
NADPH Oxidase 4
NADPH Oxidases
Phosphoproteins
Phosphorylation
Protein Phosphatase 2
Protein Processing, Post-Translational
Protein Transport
RNA, Small Interfering
Superoxides