Moraxella catarrhalis induces an immune response in the murine lung that is independent of human CEACAM5 expression and long-term smoke exposure

Am J Physiol Lung Cell Mol Physiol. 2015 Aug 1;309(3):L250-61. doi: 10.1152/ajplung.00265.2014. Epub 2015 Jun 5.


In patients with chronic obstructive pulmonary disease (COPD), Moraxella catarrhalis infection of the lower airways is associated with chronic colonization and inflammation during stable disease and acute exacerbations. Chronic smoke exposure induces chronic inflammation and impairs mucociliary clearance, thus contributing to bacterial colonization of the lower airways in COPD patients. The human-specific carcinoembryonic antigen-related cell adhesion molecule (CEACAM) 5, expressed in human airways, has been shown to contribute to epithelial colonization of CEACAM-binding pathogens. To investigate the impact of CEACAM5 expression on pulmonary M. catarrhalis colonization, we infected mice transgenic for human CEACAM5 (hCEACAM5) and wild type mice intratracheally with M. catarrhalis with or without preceding smoke exposure and analyzed bacterial colonization and local and systemic inflammation. Our results show that airway infection with M. catarrhalis accelerated acute local but not systemic inflammation, albeit independent of hCEACAM5 expression. Long-term smoke exposure alone or prior to M. catarrhalis infection did not contribute to increased local or systemic inflammation. No difference was found in pulmonary clearance of M. catarrhalis in hCEACAM5-transgenic mice compared with wild-type mice. Smoke exposure neither altered time nor extent of persistence of M. catarrhalis in the lungs of both genotypes. In conclusion, M. catarrhalis induced a local acute immune response in murine airways. Neither hCEACAM5 expression nor chronic smoke exposure nor a combination of both was sufficient as prerequisites for the establishment of chronic M. catarrhalis colonization. Our results demonstrate the difficulties in mirroring conditions of chronic airways colonization of M. catarrhalis in a murine model.

Keywords: CEACAM5; COPD; M. catarrhalis; chronic smoke exposure; mouse model.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carcinoembryonic Antigen / genetics
  • Carcinoembryonic Antigen / metabolism*
  • Female
  • GPI-Linked Proteins / genetics
  • GPI-Linked Proteins / metabolism
  • Gene Expression
  • Humans
  • Lung / immunology
  • Lung / metabolism*
  • Lung / microbiology
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Moraxella catarrhalis / immunology*
  • Moraxellaceae Infections / immunology*
  • Moraxellaceae Infections / metabolism
  • Moraxellaceae Infections / microbiology
  • Mucociliary Clearance
  • Pulmonary Disease, Chronic Obstructive / complications
  • Pulmonary Disease, Chronic Obstructive / immunology
  • Pulmonary Disease, Chronic Obstructive / metabolism*
  • Respiratory Mucosa / immunology
  • Respiratory Mucosa / metabolism
  • Respiratory Mucosa / pathology
  • Smoking / immunology
  • Smoking / metabolism


  • CEACAM5 protein, human
  • Carcinoembryonic Antigen
  • GPI-Linked Proteins