FOXO transcription factors regulate innate immune mechanisms in respiratory epithelial cells

J Immunol. 2013 Feb 15;190(4):1603-13. doi: 10.4049/jimmunol.1200596. Epub 2013 Jan 11.

Abstract

Bacterial pathogens are a leading cause of lung infections and contribute to acute exacerbations in patients with chronic respiratory diseases. The innate immune system of the respiratory tract controls and prevents colonization of the lung with bacterial pathogens. Forkhead box transcription factor family O (FOXO) transcription factors are key regulators of cellular metabolism, proliferation, and stress resistance. In this study, our aim was to investigate the role of FOXO transcription factors in innate immune functions of respiratory epithelial cells. We show that bacterial pathogens potently activate FOXO transcription factors in cultured human respiratory epithelial cells in vitro. Infection of mice with bacterial pathogens resulted in the activation of FOXO transcription factors in alveolar and bronchial epithelial cells in vivo. Active FOXO was also detectable in human bronchial tissue obtained from subjects with different infection-related lung diseases. Small interfering RNA-mediated knockdown of FOXO in bronchial epithelial cells resulted in reduced expression of factors of the innate immune system such as antimicrobial peptides and proinflammatory cytokines, both under basal conditions and upon infection. FOXO deficiency further affected internalization of Haemophilus influenzae in bronchial epithelial cells. Finally, we show that TLR3 activates innate immune responses in a FOXO-dependent manner. In conclusion, FOXO transcription factors are involved in the cellular responses to bacterial stimuli and act as central regulators of innate immune functions in respiratory epithelial cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Chronic Disease
  • Disease Models, Animal
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors / physiology*
  • Humans
  • Immunity, Innate
  • Mice
  • Mice, Inbred C57BL
  • Myeloid Cells / immunology
  • Myeloid Cells / metabolism
  • Myeloid Cells / pathology
  • Pseudomonas Infections / immunology
  • Pseudomonas Infections / metabolism
  • Pseudomonas Infections / pathology
  • Respiratory Mucosa / immunology*
  • Respiratory Mucosa / metabolism*
  • Respiratory Mucosa / pathology
  • Signal Transduction / immunology
  • Tumor Cells, Cultured

Substances

  • FOXO3 protein, human
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors