The fucose containing polymer (FCP) rich fraction of Ascophyllum nodosum (L.) Le Jol. protects Caenorhabditis elegans against Pseudomonas aeruginosa by triggering innate immune signaling pathways and suppression of pathogen virulence factors

doi:2015.30.2.147

Algae > Volume 30(2); 2015 > Article

Algae 2015;30(2): 147-161. doi: https://doi.org/10.4490/algae.2015.30.2.147

Saveetha Kandasamy¹, Wajahatullah Khan², Garima Kulshreshtha¹, Franklin Evans³, Alan T. Critchley³, J. H. Fitton⁴, Damien N. Stringer⁴, Vicki-Anne Gardiner⁴ and Balakrishnan Prithiviraj^1,*

¹Department of Environmental Sciences, Faculty of Agriculture, Dalhousie University, P.O. Box 550, Truro, NS B2B 5E3 Canada
²Basic Sciences Department, College of Science and Health Professions (COSHP), King Saud Bin Abdul Aziz University for Health Sciences (KSAU-HS), P.O. Box 22490, Riyadh 11426, Saudi Arabia
³Acadian Seaplants Limited, 30 Brown Avenue, Dartmouth, NS B3B 1X8, Canada
⁴Marinova Pty Ltd., 249, Kennedy Drive, Cambridge, Tasmania 7170, Australia

*Corresponding Author

Email: bprithiviraj@dal.ca

ABSTRACT

Brown algal extracts have long been used as feed supplements to promote health of farm animals. Here, we show new molecular insights in to the mechanism of action of a fucose containing polymer (FCP) rich fraction from the brown seaweed Ascophyllum nodosum using the Caenorhabditis elegans-Pseudomonas aeruginosa PA14 infection model. FCP enhanced survival of C. elegans against pathogen stress, correlated with up-regulation of key immune response genes such as: lipases, lysozyme (lys-1), saponin-like protein (spp-1), thaumatin-like protein (tlp-1), matridin SK domain protein (msk-1), antibacterial protein (abf-1), and lectin family protein (lfp). Further, FCP caused down regulation of P. aeruginosa quorum sensing genes: (lasI, lasR, rhlI, and rhlR), secreted virulence factors (lipase, proteases, and elastases) and toxic metabolites (pyocyanin, hydrogen cyanide, and siderophore). Biofilm formation and motility of pathogenic bacteria were also greatly attenuated when the culture media were treated with FCP. Interestingly, FCP failed to mitigate the pathogen stress in skn-1, daf-2, and pmk-1 mutants of C. elegans. This indicated that, FCP treatment acted on the regulation of fundamental innate immune pathways, which are conserved across the majority of organisms including humans. This study suggests the possible use of FCP, a seaweed component, as a functional food source for healthy living.

Key words: Ascophyllum nodosum; Caenorhabditis elegans; innate immunity; Pseudomonas aeruginosa; quorum sensing; virulence factors