Effect of fuzapladib sodium hydrate on adhesion molecule expression in canine endothelial cells and neutrophils

Neutrophil recruitment to inflamed tissue is mediated by adhesion molecules and chemokine signaling. Fuzapladib sodium hydrate (FZP) has been reported to reduce neutrophil infiltration, but its broader effect on adhesion molecules in dogs remains unclear. This study investigated the influence of FZP on canine aortic endothelial cells (CnAOEC) and primary neutrophils under cytokine stimulation. CnAOEC were treated with recombinant canine tumor necrosis factor alpha (rh-cTNFα) or lipopolysaccharide together with FZP, while neutrophils isolated from healthy dogs were preincubated with FZP before rh-cTNFα stimulation for gene and protein expression analyses. Expression of endothelial E-selectin, P-selectin, and intercellular adhesion molecule-1 (ICAM-1) was quantified by qPCR. Neutrophil C-X-C motif chemokine receptor 2, P-selectin glycoprotein ligand-1 (PSGL-1), and L-selectin were also analyzed using qPCR. In addition, C-X-C motif chemokine ligand 1 and leukocyte function-associated antigen-1 (LFA-1) were determined using ELISA and flow cytometry, respectively. Neutrophil adhesion to FZP-treated endothelial monolayers was evaluated under static conditions. FZP significantly downregulated endothelial P-selectin at the highest dose, whereas ICAM-1 was upregulated. In neutrophils, FZP decreased L-selectin and PSGL-1 expression at the highest concentration. These findings suggest that FZP selectively modulates early adhesion through suppression of P-selectin, L-selectin, and PSGL-1, which may weaken rolling and tethering interactions between cells. Although functional adhesion effects were limited, these molecular responses provide further insight into the anti-inflammatory effect of FZP.