Apoptotic cell clearance by bronchial epithelial cells critically influences airway inflammation

Nature. 2013 Jan 24;493(7433):547-51. doi: 10.1038/nature11714. Epub 2012 Dec 12.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allergens / immunology
  • Animals
  • Apoptosis*
  • Bronchi / cytology*
  • Bronchi / immunology
  • Bronchi / pathology
  • Bronchoalveolar Lavage Fluid / chemistry
  • Bronchoalveolar Lavage Fluid / immunology
  • Dust / immunology
  • Epithelial Cells / immunology
  • Epithelial Cells / physiology*
  • Immunity, Innate / immunology
  • Inflammation / immunology
  • Inflammation / pathology*
  • Interleukin-10 / biosynthesis
  • Interleukin-10 / immunology
  • Interleukin-33
  • Interleukins / biosynthesis
  • Interleukins / immunology
  • Lung / immunology
  • Lung / pathology*
  • Mice
  • Ovalbumin / immunology
  • Phagocytosis*
  • Pyroglyphidae / immunology
  • Respiratory Hypersensitivity / immunology
  • Respiratory Hypersensitivity / pathology*
  • Th2 Cells / immunology
  • Th2 Cells / metabolism
  • Up-Regulation
  • rac1 GTP-Binding Protein / deficiency
  • rac1 GTP-Binding Protein / genetics
  • rac1 GTP-Binding Protein / metabolism

Substances

  • Allergens
  • Dust
  • Il33 protein, mouse
  • Interleukin-33
  • Interleukins
  • Interleukin-10
  • Ovalbumin
  • rac1 GTP-Binding Protein