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Attenuated expression of inducible nitric oxide synthase in lung microvascular endothelial cells is associated with an increase in ICAM-1 expression. J Pediatr Surg 2001 Aug;36(8):1136-42

Date

08/02/2001

Pubmed ID

11479842

DOI

10.1053/jpsu.2001.25731

Scopus ID

2-s2.0-0034894482   17 Citations

Abstract

BACKGROUND/PURPOSE: The molecular and cellular events that regulate inflammatory lung injury, a major cause of morbidity in surgical patients, remain unclear. The authors hypothesize that nitric oxide (NO) plays an important role in regulating polymorphonuclear cell (PMN)-induced acute lung injury, and further, that attenuated expression of inducible nitric oxide synthase (iNOS) and therefore decreased production of NO by lung microvascular endothelial cells (LMVEC), accelerates inflammation and injury.

METHODS: LMVEC and aortic EC (AEC) from rat and human were stimulated with lipopolysaccharide (LPS) and cytokines; changes in iNOS mRNA expression and iNOS activity were determined. The role of NO in mediating inflammatory responses was evaluated by determining PMN adherence to LMVEC and lung tissue slices in the presence and absence of NOS inhibitors and NO donors. Human LMVEC and AEC were assessed by FACS analysis for ICAM-1 expression, because this is thought to be a critical determinant of PMN adherence.

RESULTS: When stimulated with endotoxin and cytokines, rat AEC monolayers express nearly 3-fold more iNOS mRNA than rat LMVEC. The low levels of LMVEC iNOS expression are associated with a 4-fold lower nitrite and nitrate production. Similar trends are seen in human endothelial cells. When iNOS activity was blocked, PMN adherence to tumor necrosis factor alpha (TNFalpha)/LPS-stimulated LMVEC was markedly increased. In contrast, adding a nitric oxide donor to endotoxin/cytokine-stimulated LMVEC monolayers reduced PMN adherence to near background levels. Similar responses were observed in vivo. Human lung microvascular endothelial cells show a substantially increased level of ICAM-1 upregulation when compared with similarly stimulated human aortic macrovascular endothelial cells.

CONCLUSIONS: These data indicate that LMVEC express less iNOS and produce less NO than AEC. This lower expression and activity of iNOS in LMVEC may be linked to increased expression of ICAM-1. Because ICAM-1 has been shown to be essential for tight PMN adherence, these data suggest that relatively low iNOS expression in LMVEC may contribute to a propensity for the lung to be injured by activated PMNs.

Author List

Lo HP, Ackland-Berglund CE, Pritchard KA Jr, Guice KS, Oldham KT

Authors

Keith T. Oldham MD Professor in the Surgery department at Medical College of Wisconsin
Kirkwood A. Pritchard PhD Professor in the Surgery department at Medical College of Wisconsin




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

Animals
Blotting, Northern
Cells, Cultured
Cytokines
Disease Models, Animal
Endothelium, Vascular
Flow Cytometry
Humans
Intercellular Adhesion Molecule-1
Lipopolysaccharides
Lung
Male
Nitric Oxide Synthase
RNA, Messenger
Rats
Rats, Sprague-Dawley
Reference Values
Sensitivity and Specificity
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a