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Hypoxia Response in Asthma: Differential Modulation on Inflammation and Epithelial Injury.
MedLine Citation:
PMID:  22312019     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Rationale: Oxygen sensing prolyl-hydroxylase-2 (PHD-2) negatively regulates hypoxia-inducible-factor 1-alpha (HIF-1α) and suppresses the hypoxic response. Hypoxia-signaling is thought to be pro-inflammatory, but also attenuates cellular injury and apoptosis. While increased hypoxic-response has been noted in asthma, its functional relevance is unknown.Objectives: To dissect the mechanisms and role of hypoxic-response in asthma pathophysiology. Methods: Experimental studies were conducted in mice, using acute and chronic allergic models of asthma. The hypoxic-response in allergically inflamed lungs was modulated by using either pharmacologic PHD inhibitors (ethyl-3-4-dihydroxybenzoic acid, DHB, 1-10mg/kg) or siRNA mediated genetic knockdowns. Results: Increased hypoxia-response led to exacerbation of the asthma phenotype, with HIF-1α knockdown being beneficial. Chronically inflamed lungs from mice treated with 10mg/kg DHB showed diffuse upregulation of the hypoxia-response, severe airway remodeling and inflammation. Fatal asphyxiation during methacholine challenge was noted. However, bronchial epithelium restricted upregulation of hypoxia-response seen with low dose DHB (1mg/kg) reduced epithelial injury and attenuated the asthmatic phenotype. Upregulation of hypoxia-response was associated with increased expression of CX3CR1, a lymphocyte survival factor, and increased inflammatory cell infiltrate. Conclusion: Exaggerated hypoxia-response may contribute to airway inflammation, remodeling, and development of asthma. However, the hypoxia-response may also be protective of epithelial apoptosis at lower levels, and the net effects of modulating the hypoxia-response may vary based on the context.Key words: Hypoxia, HIF-1α, PHD2, apoptosis.
Authors:
Tanveer Ahmad; Manish Kumar; Ulaganathan Mabalirajan; Bijay Pattnaik; Shilpi Aggarwal; Ranjana Singh; Suchita Singh; Mitali Mukerji; Balaram Ghosh; Anurag Agrawal
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-2-3
Journal Detail:
Title:  American journal of respiratory cell and molecular biology     Volume:  -     ISSN:  1535-4989     ISO Abbreviation:  -     Publication Date:  2012 Feb 
Date Detail:
Created Date:  2012-2-8     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8917225     Medline TA:  Am J Respir Cell Mol Biol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Centre of Excellence for Translational Research in Asthma and Lung Disease, CSIR-Institute of Genomics and Integrative Biology, Delhi, India.
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