Lorcan P McGarvey1, Claire A Butler2, Susan Stokesberry2, Liam Polley2, Stephen McQuaid3, Hani'ah Abdullah2, Sadaf Ashraf4, Mary K McGahon4, Tim M Curtis4, Joe Arron5, David Choy5, Tim J Warke2, Peter Bradding6, Madeleine Ennis2, Alexander Zholos7, Richard W Costello8, Liam G Heaney2. 1. Centre for Infection and Immunity, Health Sciences Building, Queens University Belfast, Belfast, United Kingdom. Electronic address: l.mcgarvey@qub.ac.uk. 2. Centre for Infection and Immunity, Health Sciences Building, Queens University Belfast, Belfast, United Kingdom. 3. Tissue Pathology, Belfast Health and Social Care Trust, Belfast, United Kingdom. 4. Centre for Vision and Vascular Science, Queens University Belfast, Belfast, United Kingdom. 5. Genentech, South San Francisco, Calif. 6. Institute for Lung Health, Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom. 7. Centre for Vision and Vascular Science, Queens University Belfast, Belfast, United Kingdom; Institute of Biology, Taras Shevchenko Kiev National University, Kiev, Ukraine. 8. Department of Respiratory, Otolaryngology and Molecular Medicine, Education and Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland.
Abstract
BACKGROUND: The airway epithelium is exposed to a range of physical and chemical irritants in the environment that are known to trigger asthma. Transient receptor potential (TRP) cation channels play a central role in sensory responses to noxious physical and chemical stimuli. Recent genetic evidence suggests an involvement of transient receptor potential vanilloid 1 (TRPV1), one member of the vanilloid subfamily of TRP channels, in the pathophysiology of asthma. The functional expression of TRPV1 on airway epithelium has yet to be elucidated. OBJECTIVE: In this study we examined the molecular, functional, and immunohistochemical expression of TRPV1 in asthmatic and healthy airways. METHODS: Bronchial biopsy specimens and bronchial brushings were obtained from healthy volunteers (n = 18), patients with mild-to-moderate asthma (n = 24), and patients with refractory asthma (n = 22). Cultured primary bronchial epithelial cells from patients with mild asthma (n = 4), nonasthmatic coughers (n = 4), and healthy subjects (n = 4) were studied to investigate the functional role of TRPV1. RESULTS: Quantitative immunohistochemistry revealed significantly more TRPV1 expression in asthmatic patients compared with healthy subjects, with the greatest expression in patients with refractory asthma (P = .001). PCR and Western blotting analysis confirmed gene and protein expression of TRPV1 in cultured primary bronchial epithelial cells. Patch-clamp electrophysiology directly confirmed functional TRPV1 expression in all 3 groups. In functional assays the TRPV1 agonist capsaicin induced dose-dependent IL-8 release, which could be blocked by the antagonist capsazepine. Reduction of external pH from 7.4 to 6.4 activated a capsazepine-sensitive outwardly rectifying membrane current. CONCLUSIONS: Functional TRPV1 channels are present in the human airway epithelium and overexpressed in the airways of patients with refractory asthma. These channels might represent a novel therapeutic target for the treatment of uncontrolled asthma.
BACKGROUND: The airway epithelium is exposed to a range of physical and chemical irritants in the environment that are known to trigger asthma. Transient receptor potential (TRP) cation channels play a central role in sensory responses to noxious physical and chemical stimuli. Recent genetic evidence suggests an involvement of transient receptor potential vanilloid 1 (TRPV1), one member of the vanilloid subfamily of TRP channels, in the pathophysiology of asthma. The functional expression of TRPV1 on airway epithelium has yet to be elucidated. OBJECTIVE: In this study we examined the molecular, functional, and immunohistochemical expression of TRPV1 in asthmatic and healthy airways. METHODS: Bronchial biopsy specimens and bronchial brushings were obtained from healthy volunteers (n = 18), patients with mild-to-moderate asthma (n = 24), and patients with refractory asthma (n = 22). Cultured primary bronchial epithelial cells from patients with mild asthma (n = 4), nonasthmatic coughers (n = 4), and healthy subjects (n = 4) were studied to investigate the functional role of TRPV1. RESULTS: Quantitative immunohistochemistry revealed significantly more TRPV1 expression in asthmatic patients compared with healthy subjects, with the greatest expression in patients with refractory asthma (P = .001). PCR and Western blotting analysis confirmed gene and protein expression of TRPV1 in cultured primary bronchial epithelial cells. Patch-clamp electrophysiology directly confirmed functional TRPV1 expression in all 3 groups. In functional assays the TRPV1 agonist capsaicin induced dose-dependent IL-8 release, which could be blocked by the antagonist capsazepine. Reduction of external pH from 7.4 to 6.4 activated a capsazepine-sensitive outwardly rectifying membrane current. CONCLUSIONS: Functional TRPV1 channels are present in the human airway epithelium and overexpressed in the airways of patients with refractory asthma. These channels might represent a novel therapeutic target for the treatment of uncontrolled asthma.
Authors: Kent Miner; Katja Labitzke; Benxian Liu; Paul Wang; Kathryn Henckels; Kevin Gaida; Robin Elliott; Jian Jeffrey Chen; Longbin Liu; Anh Leith; Esther Trueblood; Kelly Hensley; Xing-Zhong Xia; Oliver Homann; Brian Bennett; Mike Fiorino; John Whoriskey; Gang Yu; Sabine Escobar; Min Wong; Teresa L Born; Alison Budelsky; Mike Comeau; Dirk Smith; Jonathan Phillips; James A Johnston; Joseph G McGivern; Kerstin Weikl; David Powers; Karl Kunzelmann; Deanna Mohn; Andreas Hochheimer; John K Sullivan Journal: Front Pharmacol Date: 2019-02-14 Impact factor: 5.810
Authors: Cassandra E Deering-Rice; Chris Stockmann; Erin G Romero; Zhenyu Lu; Darien Shapiro; Bryan L Stone; Bernhard Fassl; Flory Nkoy; Derek A Uchida; Robert M Ward; John M Veranth; Christopher A Reilly Journal: J Biol Chem Date: 2016-10-07 Impact factor: 5.157