The macrophage scavenger receptor SR-AI/II and lung defense against pneumococci and particles

Am J Respir Cell Mol Biol. 2006 Oct;35(4):474-8. doi: 10.1165/rcmb.2006-0128OC. Epub 2006 May 4.

Abstract

The class A macrophage scavenger receptor SR-AI/II is implicated as a pattern recognition receptor for innate immunity, but its functional role in lung defense has not been studied. We used mice genetically deficient in SR-AI/II and their wild-type C57BL/6 counterparts to investigate the contribution of this receptor to defense against pneumococcal infection and inhaled particles. SR-AI/II deficiency caused impaired phagocytosis of fluorescent bacteria in vivo, diminished clearance of live bacteria from the lungs, and substantially increased pneumonic inflammation. Survival studies also showed increased mortality in SR-AI/II-deficient mice with pneumococcal lung infection. Similarly, after challenge of the airways with TiO(2) particles, SR-AI/II-deficient mice showed increased proinflammatory cytokine levels in lung lavage fluid and a more pronounced neutrophilic inflammation. The data indicate that the lung macrophage class A scavenger receptor SR-AI/II contributes to innate defense against bacteria and inhaled particles.

Publication types

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

MeSH terms

  • Animals
  • Disease Susceptibility
  • Female
  • Immunity, Innate*
  • Lung / immunology*
  • Lung / metabolism
  • Lung / microbiology
  • Macrophages, Alveolar / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Phagocytosis
  • Pneumonia, Pneumococcal / immunology*
  • Pneumonia, Pneumococcal / mortality
  • Scavenger Receptors, Class A / genetics
  • Scavenger Receptors, Class A / physiology*
  • Titanium / pharmacology

Substances

  • Scavenger Receptors, Class A
  • titanium dioxide
  • Titanium