Effect of sweet potato purple acid phosphatase on Pseudomonas aeruginosa flagellin-mediated inflammatory response in A549 cells

Objective: The study was conducted to investigate the dephosphorylation of Pseudomonas aeruginosa flagellin (PA FLA) by sweet potato purple Acid Phosphatase (PAP) and the effect of the Enzyme on the flagellin-mediated inflammatory response in the A549 lung epithelial cell line.

Methods: The activity of sweet potato PAP on PA FLA was assayed at different pH (4, 5.5, 7, and 7.5) and temperature (25°C, 37°C, and 55°C) conditions. The release of interleukin-8 (IL-8) and the activation of nuclear factor kappa- light-chain-enhancer of activated B cells (NF-κB) in A549 cells exposed to PA FLA treated with or without sweet potato PAP was measured using IL-8 and NF-κB ELISA kits, respectively. The activation of Toll-like Receptor 5 (TLR5) in TLR5-overexpressing HEK-293 cells exposed to PA FLA treated with or without sweet potato PAP was determined by the secreted alkaline phosphatase-based assay.

Results: The dephosphorylation of PA FLA by sweet potato PAP was favorable at pH 4 and 5.5 and highest at 55°C. PA-FLA treated with the Enzyme decreased IL-8 release from A549 cells to about 3.5-fold compared to intact PA FLA at 1,000 ng/mL of substrate. Moreover, PA-FLA dephosphorylated by the Enzyme repressed the activation of NF-κB in the cells compared to intact PA FLA. The activation of TLR5 by PA-FLA was highest in TLR-overexpressing HEK293 cells at a substrate concentration of 5,000 ng/mL, whereas PA FLA treated with the Enzyme strongly repressed the activation of TLR5.

Conclusion: Sweet potato PAP has the potential to be a new alternative agent against the increased Antibiotic resistance of P. aeruginosa and may be a new conceptual feed additive to control unwanted inflammatory responses caused by Bacterial infections in Animal Husbandry.

A549 Cell; Flagellin; Inflammatory Response; Pseudomonas aeruginosa; Sweet Potato Purple Acid Phosphatase.