| First Author | Wongtrakool C | Year | 2014 |
| Journal | PLoS One | Volume | 9 |
| Issue | 10 | Pages | e109602 |
| PubMed ID | 25296021 | Mgi Jnum | J:223571 |
| Mgi Id | MGI:5649510 | Doi | 10.1371/journal.pone.0109602 |
| Citation | Wongtrakool C, et al. (2014) Nicotine stimulates nerve growth factor in lung fibroblasts through an NFkappaB-dependent mechanism. PLoS One 9(10):e109602 |
| abstractText | RATIONALE: Airway hyperresponsiveness (AHR) is classically found in asthma, and persistent AHR is associated with poor asthma control. Although airway smooth muscle (ASM) cells play a critical pathophysiologic role in AHR, the paracrine contributions of surrounding cells such as fibroblasts to the contractile phenotype of ASM cells have not been examined fully. This study addresses the hypothesis that nicotine promotes a contractile ASM cell phenotype by stimulating fibroblasts to increase nerve growth factor (NGF) secretion into the environment. METHODS: Primary lung fibroblasts isolated from wild type and alpha7 nicotinic acetylcholine receptor (alpha7 nAChR) deficient mice were treated with nicotine (50 microg/ml) in vitro for 72 hours. NGF levels were measured in culture media and in bronchoalveolar lavage (BAL) fluid from asthmatic, smoking and non-smoking subjects by ELISA. The role of the NFkappaB pathway in nicotine-induced NGF expression was investigated by measuring NFkappaB nuclear translocation, transcriptional activity, chromatin immunoprecipitation assays, and si-p65 NFkappaB knockdown. The ability of nicotine to stimulate a fibroblast-mediated, contractile ASM cell phenotype was confirmed by examining expression of contractile proteins in ASM cells cultured with fibroblast-conditioned media or BAL fluid. RESULTS: NGF levels were elevated in the bronchoalveolar lavage fluid of nicotine-exposed mice, current smokers, and asthmatic children. Nicotine increased NGF secretion in lung fibroblasts in vitro in a dose-dependent manner and stimulated NFkappaB nuclear translocation, p65 binding to the NGF promoter, and NFkappaB transcriptional activity. These responses were attenuated in alpha7 nAChR deficient fibroblasts and in wild type fibroblasts following NFkappaB inhibition. Nicotine-treated, fibroblast-conditioned media increased expression of contractile proteins in ASM cells. CONCLUSION: Nicotine stimulates NGF release by lung fibroblasts through alpha7 nAChR and NFkappaB dependent pathways. These novel findings suggest that the nicotine-alpha7 nAChR-NFkappaB- NGF axis may provide novel therapeutic targets to attenuate tobacco smoke-induced AHR. |
