DKI 1,3 -glucan

-Glucans represent a powerful, valuable and well-documented immunostimulant for improving immune status and increasing disease resistance in farmed fish. The diatom Phaeodactylum tricornutum is characterized by its high content of bioactive molecules, such as the omega-3 fatty acid EPA, the carotenoid pigment fucoxanthin, and chrysolaminarin, a water-soluble polysaccharide made up of glucose monomers joined by a -(1, 3) with limited -(1,6) branching.

Among the known immunostimulatory effects of fish diets enriched in P. tricornutum, it is worth highlighting:

i) increased hemolytic activity of complement.

ii) the stimulation of the phagocytic activity and the respiratory activity of the leukocytes of the cephalic kidney

iii) increased serum levels of IgM, the main adaptive humoral response and commonly the only class of immunoglobulin described in fish.

iv) increased expression of IL-8, a proinflammatory cytokine that contributes (acting together with IL-1 and TNF) to host defense mechanisms in response to bacterial invasion or colonization.

In addition, extracts enriched with chrysolaminarin have demonstrated their ability to: i) stimulate the expression of the chaperone hsp90aa and the antimicrobial peptide hamp1, thus modulating the NF-B pathway and the production of proinflammatory cytokines in macrophages, ii) modulating immune genes key factors, such as glucan receptor c-type lectin (clec), interferon-related factors irf3 and irf7, TNF, the chemokine cxc10, g-type lysozyme, cd4, and IL-1, supporting a immunomodulatory and anti-inflammatory effect and iii) modulate the intestinal microbiome, reducing bacteria of the Vibrio genus.