title: Cigarette smoke decreases inducible nitric oxide synthase in lung epithelial cells.
abstract: Cigarette smoking has been associated with decreased exhaled nitric oxide (NO). To investigate the mechanism of this decrease, the effects of a cigarette smoke extract were evaluated a murine lung epithelial cell line (LA-4), a human lung epithelial cell line (A549), and primary cultures of human lung epithelial cells induced to produce NO by cytokines. NO production was evaluated by measuring nitrite, a stable end product of NO, in cell culture supernatant fluids. Cigarette smoke extract caused a reduction in the cytokine-induced nitrite concentrations in the culture supernatant fluids from all 3 cell types (P < .01, all comparisons). To further investigate these observations, immunohistochemistry demonstrated a decrease in cytokine-induced inducible NO synthase (iNOS) protein expression and iNOS mRNA after cigarette smoke extract exposure in LA-4 cells. However, iNOS mRNA half-life was not altered by the smoke extract, suggesting that the smoke extract decreased NO by decreasing iNOS mRNA transcription. These findings demonstrate that cigarette smoke extract decreases iNOS expression and NO production from lung epithelial cells.
authors.affiliation: Research Service, Southern Arizona VA Health Care System, Building 52, 3601 South 6th Avenue, Tucson, AZ 85723, USA.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Hoyt
authors.forename: Richard A
authors.initials: RA
authors.lastname: Robbins
authors.forename: Michael
authors.initials: M
authors.lastname: Habib
authors.forename: David R
authors.initials: DR
authors.lastname: Springall
authors.forename: Lee D K
authors.initials: LD
authors.lastname: Buttery
authors.forename: Julia M
authors.initials: JM
authors.lastname: Polak
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Barnes
mesh_terms: D000818:Animals; D002460:Cell Line; D016207:Cytokines / Q000494:pharmacology; D004847:Epithelial Cells / Q000201:enzymology* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008168:Lung / Q000166:cytology* / Q000201:enzymology; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D020871:RNA Stability; D012333:RNA, Messenger / Q000032:analysis; D012906:Smoke / Q000009:adverse effects*; D014026:Nicotiana; D014158:Transcription, Genetic
chemical_list: D016207:Cytokines; D012333:RNA, Messenger; D012906:Smoke; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II