The use of sulfated polysaccharides from brown seaweed Fucus evanescens as adjuvants (native fucoidan in combination with polyphenols, fucoidan without polyphenols, a product of enzymatic hydrolysis of fucoidan) stimulated the formation of specific antibodies to the surface antigen of the hepatitis B virus (HBs-AG). Immunization of mice with vaccine compositions containing HBs-AG and fucoidan samples resulted in increasing the serum level of the pro-inflammatory (TNF-a, IFN-g, IL-2) cytokines. Increased production of these cytokines was detected in the culture of splenocytes additionally stimulated in vitro by fucoidans or phytohemagglutinin. The adjuvant effect of fucoidan and its structural modifications was comparable to that of the traditional licensed adjuvant aluminum hydroxide. The obtained results indicate a promising use of sulfated polysaccharides from F. evanescens as vaccine adjuvants.
The study presents the results of a comparative evaluation of the effect of structural modifications of fucoidans from the brown alga Fucus evanescens (native, highly purified product of fucoidan enzymatic hydrolysis, a new regular 1→3;1→4-α-L-fucan, sulphated mainly at C2 and acetylated at C4 of the fucose residue) on the effector functions of innate and adaptive immunity cells in vitro and in vivo. Using flow cytometry, we found that all examined fucoidans induce the maturation of dendritic cells, enhance the ability of neutrophils to migrate and adhere, activate monocytes and enhance their antigen-presenting functions, and increase the cytotoxic potential of natural killers. Fucoidans increase the production of hepatitis B virus (HBs) specific IgG and cytokine Th1 (IFN-γ, TNF-α) and Th2 (IL-4) profiles in vivo. The data obtained suggest that in vitro and in vivo adjuvant effects of the products of fucoidan enzymatic hydrolysis with regular structural characteristics are comparable to those of the native fucoidan. Based on these data, the products of fucoidan enzymatic hydrolysis can be considered as an effective and safe candidate adjuvant to improve the efficacy of prophylactic and therapeutic vaccines.
The thermolabile toxin of Yersinia pseudotuberculosis produces a selective dose-dependent stimulating effect on functional activity of innate immunity cells. Prolonged apoptosis-inducing action of the toxin was associated with activation of enzymes of the oxygen-dependent system (LDH and myeloperoxidase) at the early terms of observation (up to 3 h). In turn, increased number of macrophages with apoptotic changes was noted at the early stages of contact with the thermolabile toxin (5 h), and its further growth was observed against the background of activation of mitochondrial enzymes and production of NO metabolites.
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