Functional roles of FPRs in the regulation of respiratory diseases.
a Smoking induces lung damage and structural changes, eliciting augmented bacterial colonization in the lower respiratory tract, with increased production of fMLP. b In COPD, inflammatory FPR2 ligands are produced at higher levels than anti-inflammatory FPR ligands. c Klebsiella pneumoniae infection stimulates BALF cells to produce LXA4, which induces an anti-inflammatory response leading to bacterial dissemination in the early phase of infection and is required for resolution and recovery in the late phase of infection. However, FPR2 is required for maintaining epithelial integrity against Streptococcus pneumoniae infection. d AnxA1 is incorporated into influenza A virus particles, stimulating FPR2-mediated signaling to block defense activity against virus infection.