FPR1 and endothelial dysfunction: We hypothesized that FPR1/2/3 expressions of blood innate immune cells, including neutrophil, monocyte, and natural killer (NK) cell, and serum protein levels of five FPR ligands, including LXA4, RvD1, ANXA1, SAA, and LL-37, may be associated with disease severity, clinical phenotypes, or endothelial dysfunction of OSA syndrome.