ARS | Publication request: Effects of linear cationic x-helical antimicrobial peptides on immune-relevant genes in trout macrophages.

Submitted to: Developmental and Comparative Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 30, 2005
Publication Date: November 28, 2005
Citation: Chiou, P.P., Khoo, J., Bols, N.C., Douglas, S., Chen, T.T. 2005. Effects of linear cationic x-helical antimicrobial peptides on immune-relevant genes in trout macrophages. Developmental and Comparative Immunology. 30:797-806.

Interpretive Summary: Disease outbreaks in aquaculture facilities are major causes of financial losses. Currently available methods of preventing disease outbreaks in aquaculture are either ineffective or cause contamination to the aquatic environment. An effective and safe solution to prevent disease outbreak is highly desirable. Although naturally occurring antimicrobial peptides are known to control the propagation of pathogenic microorganisms, the relationships of these peptides to the immune system of the host are not fully understood. We examined the effects of antimicrobial peptides on the expression of immune relevant genes in rainbow trout macrophage cells (RTS11). Results of the studies showed that antimicrobial peptides stimulated the expression levels of 2 pro-inflammatory genes, intrleukin-1beta and cyclooxygenase-2 genes. These results suggest that, besides killing the microorganisms directly, antimicrobial peptides could potentially serve as an effective immune adjuvant for fish vaccination. These findings will help to increase the efficacy of fish vaccination by incorporating antimicrobial peptides in fish vaccines.

Technical Abstract: There is increasing evidence of the potential role of antimicrobial peptides in the regulation of immune responses in mammalian species. However, the effects of these peptides in fish have yet to be investigated. In this study, we examined the transcriptional expression profile of representative immune-relevant genes in a trout macrophage cell line, RTS11, in response to three linear cationic alpha-helical antimicrobial peptides (insect cecropin B, fish pleurocidin and a cecropin analogue CF17). The expression levels of two pro-inflammatory genes, interleukin-1beta (IL-1beta) and cyclo-oxygenase-2 (COX-2), increased in the peptide-treated RTS11 cells. The peptides did not appear to affect the expression levels of representative genes associated with antigen presentation, interferon response or JAK/STAT signal transduction. Furthermore, the induction of IL-1beta and COX-2 in RTS11 by lipopolysaccharide was not adversely affected by these three antimicrobial peptides. Overall, the data indicate a pro-inflammatory effect of the three cationic antimicrobial peptides in the inflammatory response of salmonid species, suggesting a potential application of these peptides as immune adjuvant for fish vaccination.