Continuous nitric oxide synthesis by inducible nitric oxide synthase in normal human airway epithelium in vivo.

Abstract

Nitric oxide (NO) is an important mediator of inflammatory responses in the lung and a key regulator of bronchomotor tone. An airway NO synthase (NOS; EC 1.14.13.39) has been proposed as a source of endogenous NO in the lung but has not been clearly defined. Through molecular cloning, we conclusively demonstrate that NO synthesis in normal human airways is due to the continuous expression of the inducible NOS (iNOS) isoform in airway epithelial cells. Although iNOS mRNA expression is abundant in airway epithelial cells, expression is not detected in other pulmonary cell types, indicating that airway epithelial cells are unique in the continuous pattern of iNOS expression in the lung. In situ analysis reveals all airway epithelial cell types express iNOS. However, removal of epithelial cells from the in vivo airway environment leads to rapid loss of iNOS expression, which suggests expression is dependent upon conditions and/or factors present in the airway. Quantitation of NOS activity in epithelial cell lysates indicates nanomolar levels of NO synthesis occur in vivo. Remarkably, the high-level iNOS expression is constant in airway epithelium of normal individuals over time. However, expression is strikingly decreased by inhaled corticosteroids and j8-adrenergic agonists, medications commonly used in treatment of inflammatory airway diseases. Based upon these findings, we propose that respiratory epithelial cells are key inflammatory cells in the airway, functioning in host defense and potentially playing a role in airway inflammation.

Role of nitric oxide in pancreatic tumour growth: in vivo and in vitro studies

“…Moreover. the in vivo overexpression of the iNOS gene in nonnal human airway epithelium disappeared in primary culture (Guo et al 1996). In our data.…”

Central Role of Double-Stranded RNA-Activated Protein Kinase in Microbial Induction of Nitric Oxide Synthase

“…Human airway epithelial cells obtained by bronchial brushing were cultured in serum-free Lechner and LaVeck media (LHC8, Biofluids, Rockville, MD) on plates precoated with coating media containing 29 g/ml collagen (Vitrogen, Collagen Corp., Palo Alto, CA), 10 g/ml BSA (Biofluids), and 10 g/ml fibronectin (Calbiochem, La Jolla, CA) for 5 min (21). The cells were passaged at 60 -80% confluence by dissociation from plates with 0.02% trypsin (E-PET, Biofluids) which was neutralized with soybean trypsin inhibitor (Biofluids).…”

“…Bronchoscopic brush samplings of airway epithelial cells were taken from second and third order bronchi (21). For some experiments, airway epithelial cells were isolated from surgical specimen of tracheas and mainstem bronchi as previously described (22).…”

“…Total RNA was extracted and evaluated by Northern analysis as previously described using a 32 P-labeled 1.9-kb NOS2 cDNA probe (pCCF21) or, as a control, a 2-kb ␥-actin cDNA probe (pHF␥A-1) and a 1.5-kb 18S cDNA probe (HHCS65, American Type Culture Collection) (21,23) and then subjected to autoradiography. RNA from A549 cells stimulated with 100 U/ml IFN-␥, 10 ng/ml TNF-␣, and 10 U/ml IL-1␤ for 8 h was used as a positive control (23).…”

Medicina do sono

“…Então, especulam que ou o NO não reflete o tipo de inflamação encontrada na SASO, ou existiram fatores de confusão no estudo que modificaram os níveis do NO. Considerando que existe inflamação na SASO e que o NO é um marcador inespecífico de inflamação (1) e regulador do tônus broncomotor (2) , optamos pela possibilidade de fatores de confusão no referido estudo, uma vez que outros autores (3) encontraram níveis elevados de NO em pacientes portadores de SASO após o sono, quando comparados com níveis dos mesmos pacientes antes do sono, bem como com valores antes e após o sono de indivíduos normais. Portanto, nos parece razoável concluir que os ní-veis de NO encontram-se elevados em pacientes portadores de SASO apenas após o sono, momento em que a inflamação das vias aéreas superiores se encontra manifesta.…”