The role of CD44 in the acute and resolution phase of the host response during pneumococcal pneumonia

Lab Invest. 2011 Apr;91(4):588-97. doi: 10.1038/labinvest.2010.206. Epub 2011 Jan 17.

Abstract

Streptococcus pneumoniae is the most prevalent pathogen causing community-acquired pneumonia. CD44 is a transmembrane adhesion molecule, expressed by a wide variety of cell types, that has several functions in innate and adaptive immune responses. In this study, we tested the hypothesis that CD44 is involved in the host response during pneumococcal pneumonia. On intranasal infection with a lethal dose of S. pneumoniae CD44-knockout (KO) mice showed a prolonged survival when compared with wild-type mice, which was accompanied by a diminished pulmonary bacterial growth and reduced dissemination to distant body sites. Whereas, proinflammatory cytokine responses and lung pathology were not affected, CD44 deficiency resulted in increased early neutrophil influx into the lung. In separate experiments, we confirmed a detrimental role of CD44 in host defense against pneumococci during sublethal pneumonia, as demonstrated by an improved capacity of CD44 KO mice to clear a low infectious dose. In addition, CD44 appeared important for the resolution of lung inflammation during sublethal pneumonia, as shown by histopathology of lung tissue slides. In conclusion, we show here that CD44 facilitates bacterial outgrowth and dissemination during pneumococcal pneumonia, which in lethal infection results in a prolonged survival of CD44 KO mice. Moreover, during sublethal pneumonia CD44 contributes to the resolution of the inflammatory response.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Bronchoalveolar Lavage Fluid / chemistry
  • Cytokines / metabolism
  • Hyaluronan Receptors / genetics
  • Hyaluronan Receptors / metabolism*
  • Hyaluronic Acid / metabolism
  • Immunity, Innate*
  • Inflammation Mediators / metabolism
  • Lung / metabolism
  • Lung / pathology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neutrophil Infiltration
  • Pneumonia, Pneumococcal / immunology*
  • Pneumonia, Pneumococcal / microbiology
  • Pneumonia, Pneumococcal / mortality
  • Pneumonia, Pneumococcal / pathology*
  • Streptococcus pneumoniae / growth & development
  • Survival Rate
  • Time Factors

Substances

  • Cytokines
  • Hyaluronan Receptors
  • Inflammation Mediators
  • Hyaluronic Acid