Effect of acute and chronic inflammatory stimuli on expression of protease-activated receptors 1 and 2 in alveolar macrophages

Nicolas Roche, Robert G. Stirling, Sam Lim, Brian G. Oliver, Tim Oates, Elen Jazrawi, Gaetano Caramori, K. Fan Chung

Research output: Contribution to journalArticleResearchpeer-review

24 Citations (Scopus)


Background: Protease-activated receptors 1 and 2 (PAR-1 and PAR-2) are 7-transmembrane G protein-coupled receptors activated by serine proteases in many cell types, including monocytes-macrophages, leading to the production of proinflammatory mediators, cytokines, and growth factors. Objective: We determined the influence of chronic smoking and asthma on the expression of PAR-1 and PAR-2 receptors on alveolar macrophages (AMs). Methods: We used RT-PCR and immunocytochemistry with confocal microscopy to determine mRNA and protein expression of PAR-1 and PAR-2 in AMs obtained from healthy smokers, asthmatic patients, and healthy subjects. In addition, we examined the effect of IL-1β and LPS. Results: PAR1 mRNA was decreased, whereas PAR2 mRNA was increased in 24-hour cultured AMs from smokers when compared with values in AMs from healthy subjects. Paradoxically, there was a higher degree of PAR-1 protein staining in AMs from smokers, whereas PAR-2 staining was similar in smokers and healthy subjects. PAR-1 and PAR-2 mRNA and protein expression were similar in asthmatic patients and control subjects. IL-1β and LPS had no effect on PAR1 and PAR2 gene expression by AMs. Conclusions: There is a dissociation between gene and protein expression of PAR-1 and PAR-2. PAR-1 protein overexpression in AMs from smokers might be important in the pathophysiology of chronic airways disease.

Original languageEnglish
Pages (from-to)367-373
Number of pages7
JournalThe Journal of Allergy and Clinical Immunology
Issue number2
Publication statusPublished - 1 Feb 2003
Externally publishedYes


  • Alveolar macrophages
  • Asthma
  • Chronic airways disease
  • Protease-activated receptors

Cite this