L'activité antibactérienne et immunomodulatrice d'un extrait d'algue verte riche en polysaccharides sulfatés

Session Santé AnimaleAntibiotics have been used for a long time in pig production to protect animals against pathogens. However, EU policy has been adopted to implement a sustainable production without adding antibiotics as growth promoters. Marine algae contain in their cell wall water-soluble sulfated polysaccharides with potential biological activities such as anticoagulant, antiviral, antibacterial and immunomodulating activities that are being explored to be used as an effective alternative to antibiotics. A crude extract containing sulfated polysaccharides was prepared from the green algae Ulva armoricana harvested in Brittany region (France) and tested for its antibacterial activity against five strains of bacterial pathogens: Salmonella Typhimurium, Staphylococcus aureus, Listeria monocytogenes, E. coli O78 and E. coli K88. The obtained results showed that this extract was more effective in inhibiting the growth of S. aureus than those of L. monocytogenes, E. coli K88 and E. coli O78. Furthermore, the ability of the extract to stimulate the expression of the immune response mediators was evaluated using an in vitro system of porcine differentiated intestinal epithelial cells IPEC-1. Analysis by RT-qPCR showed increased expression of several cytokines including TNF, IL-1, IL-6, IL-8 and CCL20. This stimulation of immune response factor expression involved the activation of TLR4 receptor. These results suggest that this extract could be used as a new prophylactic strategy to stimulate the immune response of animals and to protect mucosal tissues against pathogens