Abstract
Although sex differences in asthma severity are recognized, the mechanisms by which sex steroids such as estrogen influence the airway are still under investigation. Airway tone, a key aspect of asthma, represents a balance between bronchoconstriction and dilation. Nitric oxide (NO) from the bronchial epithelium is an endogenous bronchodilator. We hypothesized that estrogens facilitate bronchodilation by generating NO in bronchial epithelium. In acutely dissociated human bronchial epithelial cells from female patients exposure to 17β-estradiol (E2; 10 pM–100 nM) resulted in rapid increase of diaminofluorescein fluorescence (NO indicator) within minutes, comparable with that induced by ATP (20 μM). Estrogen receptor (ER) isoform-specific agonists (R,R)-5,11-diethyl-5,6,11,12-tetrahydro-2,8-chrysenediol (THC) (ERα) and diaryl-propionitrile (DPN) (ERβ) stimulated NO production to comparable levels and at comparable rates, whereas the ER antagonist 7α,17β-[9-[(4,4,5,5,5-pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol (ICI 182,780) (1 μM) was inhibitory. Estrogen effects on NO were mediated via caveolin-1 (blocked using the caveolin-1 scaffolding domain peptide) and by increased intracellular calcium concentration [prevented by 20 μM 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetra(acetoxymethyl) ester but not by blocking Ca2+ influx using LaCl3]. Estrogen increased endothelial NO synthase activation (inhibited by 100 μM NG-nitro-l-arginine methyl ester) and phosphorylated Akt. In epithelium-intact human bronchial rings contracted with acetylcholine (1 μM), E2, THC, and DPN all produced acute bronchodilation in a dose-dependent fashion. Such bronchodilatory effects were substantially reduced by epithelial denudation. Overall, these data indicate that estrogens, acting via ERα or ERβ, can acutely produce NO in airway epithelium (akin to vascular endothelium). Estrogen-induced NO and its impairment may contribute to altered bronchodilation in women with asthma.
Footnotes
This work was supported by the National Institutes of Health National Heart, Lung and Blood Institute [Grants HL090595, HL088029]; and the Mayo Graduate School (Rochester, MN).
This article represents partial fulfillment for E.A.T.'s PhD thesis in Physiology and Biomedical Engineering.
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
doi:10.1124/jpet.111.184416.
↵
The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.
-
ABBREVIATIONS:
- [Ca2+]i
- intracellular calcium concentration
- ACh
- acetylcholine
- AM
- acetoxymethyl
- ASM
- airway smooth muscle
- BAPTA
- 1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetra(acetoxymethyl) ester
- BEC
- bronchial epithelial cell
- CSD
- caveolin-1 scaffolding domain
- DAF-2
- 4,5-diaminofluorescein
- DAF-4
- 4-aminofluorescein diacetate
- DA
- diacetate
- DEANO
- diethylamine-NONOate
- DPN
- diaryl-propionitrile
- E2
- 17β-estradiol
- ER
- estrogen receptor
- GAPDH
- glyceraldehyde-3-phosphate dehydrogenase
- GL
- gray level
- GPCR30
- G protein-coupled receptor 30
- ICI 182,780
- 7α,17β-[9-[(4,4,5,5,5-pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol
- IP3
- inositol trisphosphate
- l-NAME
- NG-nitro-l-arginine methyl ester
- MAHMA
- 6-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-hexanamine
- NO
- nitric oxide
- NOS
- NO synthase
- eNOS
- endothelial NOS
- p-ENOS
- phosphorylated ENOS
- iNOS
- inducible NOS
- p-Akt
- phosphorylated Akt
- THC
- (R,R)-5,11-diethyl-5,6,11,12-tetrahydro-2,8-chrysenediol
- XeC
- xestospongin C
- 1400W
- N-([3-(Aminomethyl)phenyl]methyl)ethanimidamide dihydrochloride
- GA-1000
- gentamicin/amphotericin B
- G-1
- (±)-1-[(3aR*, 4S*, 9bS*)-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinolin-8-yl]-ethanone.
- Received May 25, 2011.
- Accepted September 21, 2011.
- Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|