Endothelial nitric oxide synthase is expressed in cultured human bronchiolar epithelium.

Abstract

IntroductionNitric oxide (NO) is an important mediator of physiologic and inflammatory processes in the lung. (2), and endothelium-derived NO relaxes tracheal smooth muscle in vitro (3). In addition, endogenous NO gas is present in the exhaled air of animals and humans (4), and endogenous nitrogen oxides and bronchodilator S-nitrosothiols have been demonstrated in human airways (5). Furthermore, air or helium embolization of the rabbit pulmonary artery does not alter exhaled NO concentrations, suggesting that the exhaled NO may be derived from the bronchial tree and not the pulmonary vasculature (4).There is indirect evidence that the epithelium may be a source of NO production in the airway. In the canine bronchial tree, the epithelium releases a relaxing factor which reduces contractile responses in larger airways and enhances relaxation responses in smaller airways (6). Immunohistochemical studies in the rat using NADPH diaphorase staining indicative of NOS activity and antisera which recognize neuronal and endothelial NOS localize NOS to the airway epithelium (7,8). In human lung, it has been reported that NADPH diaphorase staining is evident throughout the airway epithelium but staining for constitutive NOS isoforms is negative, whereas large airway epithelium stains positive for inducible NOS (7). There are preliminary reports of NOS expression and activity in cultured human airway epithelium (9, 10), but the isoform(s) constitutively expressed in those cells has not been fully characterized.The purpose of this investigation was to examine constitutive NOS gene expression and function in NCI-H441 human bronchiolar epithelial cells, which originated from a papillary adenocarcinoma (11,12). Experiments were performed to address the following questions: (a) Is NOS activity present in human bronchiolar epithelial cells?; (b) Which NOS isoform(s) is expressed?; and (c) Does NO have autocrine effects in bronchiolar epithelium?1. Abbreviations used in this paper: FMN, flavin mononucleotide; IBMX, isobutylmethylxanthine; L-NAME, nitro-L-arginine methyl ester; NO, nitric oxide; NOS, nitric oxide synthase; PAEC, pulmonary artery endothelial cells.Nitric Oxide Synthase in Airway Epithelium 2231 J. Clin. Invest.

Cell-Specific Nitric Oxide Synthase-Isoenzyme Expression and Regulation in Response to Endotoxin in Intact Rat Lungs

“…This was anticipated for the constitutive isoforms bNOS and eNOS (Asano et al, 1994;Kobzik et al, 1993;Shaul et al, 1994;Steudel et al, 1999), although an entire profile of cellular localization of both isoforms in lung tissue has so far not been shown. A recent study reported eNOS expression in epithelial cells, endothelial cells, and VSMC in normal rat lung tissue, which corresponds well with the data presented in this study.…”

“…Three isoenzymes of NOS have been described Moncada and Higgs, 1993): the neuronal isoform bNOS (NOS-1) and an endothelial isoform eNOS (NOS-3) as constitutive isoenzymes, and a mitogeninducible isoform iNOS (NOS-2). Cellular expression of bNOS and eNOS in different cell types of normal lung tissue and pulmonary cell cultures has been reported earlier (Kobzik et al, 1993;Shaul et al, 1994;Sherman et al, 1999). Cellular expression of iNOS in the lung parenchyma has so far only been observed after experimental endotoxin stimulation or in sections from patients suffering from inflammatory lung disease (Kobzik et al, 1993;Robbins et al, 1994;Tracey et al, 1994).…”

Toll-like Receptor 7 Rapidly Relaxes Human Airways

“…Our observation that TLR7's effects occurs within minutes in vitro and within seconds in vivo is consistent with neuronal nitric oxide synthase's kinetics. Although the nitric oxide synthase inhibitors used in these experiments were not specific for a particular nitric oxide synthase isozyme, endothelial nitric oxide synthase is located in airway epithelium (37), which is not involved in TLR7's effect, whereas inducible nitric oxide synthase is transcriptionally ; Figure 4. Toll-like receptor (TLR) 7 is expressed on a subpopulation of human and murine airway nerves but not airway smooth muscle.…”

Medidas de óxido nítrico no ar exalado de pacientes com história prévia de broncoespasmo no período intra-operatório

“…As três isoformas de NOS estão presentes em vias aéreas (Robbins et al,1994;Shaul, 1994;FloraFilho e Zilberstein, 2000).…”

“…O NO é expresso constitutivamente no epitélio bronquial (Shaul et al, 1994) e em células epiteliais alveolares do tipo II humanas (Pechkovsky et al, 2002) é encontrado também vasos sanguíneos pulmonares (Shaul et al, 2002) e em todos tipos de artérias, particularmente na artéria radial. (Gaudino et al, 2003).…”