PACAP modulates the transcription of TLR-1/TLR-5/MyD88 pathway genes and boosts antimicrobial defenses in Clarias gariepinus

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a multifunctional neuropeptide that belongs to the secretin/glucagon/GHRH/VIP superfamily. Some of these molecules have antimicrobial activity and they are capable of stimulating the immune system. The present work studied the antibacterial and immunostimulatory activity of PACAP-38 from African catfish Clarias gariepinus against the Gram-negative bacterium Pseudomonas aeruginosa in an in vivo test. PACAP-38 improved antimicrobial activity of skin mucus molecules against P. aeruginosa. The peptide modulates the gene expression profile of TLR-1, TLR-5, MyD88, IL-1 beta, TNF-alpha, IL-8, pardaxin, hepcidin and G/C-type lysozymes in skin, spleen and head kidney. The influenced exerted depended on the time after infection and tissue analyzed. This study provides the first evidence of a link between PACAP and antimicrobial peptides hepcidin and pardaxin. Our results suggest further use of PACAP as antimicrobial agent that could potentially be used to control disease in aquaculture.

Automated summary

PACAP-38 from African catfish enhances antibacterial activity and modulates gene expression of immune-related molecules, suggesting its potential as an antimicrobial agent in aquaculture.