Measurement of IL-13-induced iNOS-derived gas phase nitric oxide in human bronchial epithelial cells.
Exhaled nitric oxide (NO) is altered in numerous diseases including asthma, and is thought broadly to be a noninvasive marker of inflammation. However, the precise source of exhaled NO has yet to be identified, and the interpretation is further hampered by significant inter-subject variation. Using fully differentiated normal human bronchial epithelial (NHBE) cells, we sought to determine (1) the rate of NO release (flux, pl.s(-1.)cm(-2)) into the gas; (2) the effect of IL-13, a prominent mediator of allergic inflammation, on NO release; and (3) inter-subject/donor variability in NO release. NHBE cells from three different donors were cultured at an air-liquid interface and stimulated with different concentrations of IL-13 (0, 1, and 10 ng/ml) for 48 h. Gas phase NO concentrations in the headspace over the cells were measured using a chemiluminescence analyzer. The basal NO flux from the three donors (0.05 +/- 0.03) is similar in magnitude to that estimated from exhaled NO concentrations, and was significantly increased by IL-13 in a donor-specific fashion. The increase in NO release was strongly correlated with inducible nitric oxide synthase (iNOS) gene and protein expression. There was a trend toward enhanced production of nitrate relative to nitrite as an end product of NO metabolism in IL-13-stimulated cells. NO release from airway epithelial cells can be directly measured. The rate of release in response to IL-13 is strongly dependent on the individual donor, but is primarily due to the expression of iNOS.
Suresh
Vinod
V
Department of Biomedical Engineering, 3120 Natural Sciences II, University of California-Irvine, Irvine, CA 92697-2715, USA.
Mih
Justin D
JD
George
Steven C
SC
D000388:Air; D001249:Asthma / Q000378:metabolism; D001980:Bronchi / Q000166:cytology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000166:cytology*; D006801:Humans; D006967:Hypersensitivity; D007249:Inflammation; D018793:Interleukin-13 / Q000378:metabolism*; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D013997:Time Factors
D018793:Interleukin-13; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II