Apoptotic cell clearance by bronchial epithelial cells critically influences airway inflammation.
Nature 2012;
493:547-51. [PMID:
23235830 DOI:
10.1038/nature11714]
[Citation(s) in RCA: 223] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 10/25/2012] [Indexed: 01/07/2023]
Abstract
Lung epithelial cells can influence immune responses to airway allergens. Airway epithelial cells also undergo apoptosis after encountering environmental allergens; yet, relatively little is known about how these are cleared, and their effect on airway inflammation. Here we show that airway epithelial cells efficiently engulf apoptotic epithelial cells and secrete anti-inflammatory cytokines, dependent upon intracellular signalling by the small GTPase Rac1. Inducible deletion of Rac1 expression specifically in airway epithelial cells in a mouse model resulted in defective engulfment by epithelial cells and aberrant anti-inflammatory cytokine production. Intranasal priming and challenge of these mice with house dust mite extract or ovalbumin as allergens led to exacerbated inflammation, augmented Th2 cytokines and airway hyper-responsiveness, with decreased interleukin (IL)-10 in bronchial lavages. Rac1-deficient epithelial cells produced much higher IL-33 upon allergen or apoptotic cell encounter, with increased numbers of nuocyte-like cells. Administration of exogenous IL-10 'rescued' the airway inflammation phenotype in Rac1-deficient mice, with decreased IL-33. Collectively, these genetic and functional studies suggest a new role for Rac1-dependent engulfment by airway epithelial cells and in establishing the anti-inflammatory environment, and that defects in cell clearance in the airways could contribute to inflammatory responses towards common allergens.
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