US EPA

2266186 

Journal Article 

Abstract 

Neurotrophins produce nitric oxide in human airway epithelium 

Meuchel, LW; Townsend, EA; Thompson, MA; Cassivi, SD; Prakash, YS 

2010 

Yes 

American Journal of Respiratory and Critical Care Medicine
ISSN: 1073-449X
EISSN: 1535-4970 

181 

A5550 

English 

10.1164/ajrccm-conference.2010.181.1_MeetingAbstracts.A5550 

WOS:000208771003627 

is part of a larger document 3452678 Proceedings of the American Thoracic Society 2010 International Conference, May 14-19, 2010, New Orleans

Rationale: Airway hyperreactivity is characteristic of diseases such as asthma. Airway tone is regulated by a balance of airway smooth muscle (ASM) contraction, mediated in part by intracellular calcium ([Ca2+]i), and relaxation, induced by factors such as epithelium-derived nitric oxide (NO). We have previously demonstrated that growth factors called neurotrophins (NTs; e.g. brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT3)) modulate [Ca2+]i in ASM. Studies in vasculature suggest that NTs can modulate endothelium-derived NO. Accordingly, we hypothesized that NTs produce NO in normal bronchial epithelial cells (BEC; akin to effects on the endothelium), thus contributing to bronchodilation.

Methods and Results: Human BECs were isolated from surgical lung and bronchial samples and grown in a liquid-liquid interface. Western analysis showed that BECs express both high affinity (TrkB, TrkC) and low affinity (p75 ) NT receptors. In BECs loaded with the NTR fluorescent NO indicator DAF-2 (5 mM; 45min.) exposure to ACh (1 mM) or ATP (50 mM) substantially increased fluorescence levels in 5-8 min. Both BDNF and NT3 (10 nM>1 nM) increased DAF2 fluorescence to levels comparable to that of ACh or ATP. Addition of the NO scavenger PTIO reversed these changes in fluorescence. Inhibition of Trk receptors with K252A (10 nM; 30 min) attenuated NO production by NTs, while a functional p75^NTR antibody had no effect. Inhibition of eNOS via L-NAME abrogated the observed NT effect on NO. Specificity of DAF2 for NO was tested using the short-acting NO donor MAHMA-NONOate, and the nitrous oxide donor Sulpho-NONOate, and lack of change in fluorescence of the NO-insensitive dye DAF4.

Conclusions: In combination with previous data showing NT modulation of [Ca2+]i in airway smooth muscle, these novel data showing NT-induced NO production in BECs suggest that NTs (potentially derived from sources including airway smooth muscle and nerves) alter the balance between smooth muscle contraction vs. relaxation. Accordingly, we propose that in diseases such as asthma, NTs could potentially alter this balance, and that modulating NT signaling may represent a potential therapeutic target. 

American Thoracic Society 2010 International Conference 

New Orleans, LA 

May 14-19, 2010