Abstract
Background: The lipoxin A4 receptor, LXA4R/FPRL-1, is a G protein-coupled receptor. LXA4R with high affinity binds anti-inflammatory lipoxin LXA4 and with low affinity - N-formylated proinflammatory peptides. The aim of our study was to evaluate FPRL-1 expression in nonsmokers, asymptomatic smokers and in patients with COPD.
Patients and methods: 6 nonsmokers, 7 asymptomatic smokers and 5 moderate COPD patients undergoing lung resection for a solitary peripheral non-small cell carcinoma were enrolled in the study. Immunohistochemical methods were used to evaluate FPRL expression in airways and alveolar walls.
Results: FPRL-1 expression was observed in airways epithelial cells, macrophages, lymphocytes and neutrophils. Obtained results showed that asymptomatic smokers had increased numbers of FPRL-1 positive cells in alveolar walls compared to nonsmokers (157±59 vs 38±13 cells/mm2, p= 0.002). At contrast, COPD patients had decreased numbers of FPRL-1 positive cells compared to asymptomatic smokers (23±7 vs 157±59 cells/mm2, p= 0.002). In addition, COPD patients had a tendency of decreased FPRL-1 expression compared to nonsmokers. When all smokers were analyzed together, a significant positive correlation was found between the number of FPRL positive cells and airflow obstruction, FEV1% (Rho=+0.66, p=0.02).
Conclusion: Downregulated FPRL-1 in COPD patients may explain persistence of inflammatory process in alveolar area in COPD, whereas upregulation in asymptomatic smokers could serve as adaptive mechanism limiting inflammatory process.
- © 2011 ERS