Effects of enzymatically depolymerised fucoidan on effector functions of innate and adaptive immunity cells

The use of sulfated polysaccharides (fucoidans) as active pharmaceutical ingredients or adjuvants poses the challenge of obtaining structurally characterised and homogeneous samples or their oligomeric fractions maintaining high biological activity. The authors obtained a highly purified enzymatic hydrolysate of fucoidan from the brown alga Fucus evanescens and compared its biological activity with that of a native sample. The aim of the study was to compare, in vitro and in vivo, the effects of depolymerised fucoidan from the brown alga F. evanescens and native fucoidan on the effector functions of innate and adaptive immunity cells loaded with ovalbumin (OVA). Materials and methods: the effects of the fucoidan samples (depolymerised and native) on the expression of the main immunophenotypic markers by innate and adaptive immunity cells (neutrophils, monocytes, natural killers, and lymphocytes) were studied in vitro using flow cytometry. The levels of serum OVA-specific antibodies (IgG, IgG1, IgG2а) and cytokines (IFN-γ, IL-2, IL-10, IL-12) were studied in vivo using BALB/c mice immunised with OVA. The statistical analysis of the data obtained was performed using the Statistica 10 software package. Results: in vitro, both fucoidan samples altered the expression of the main immunophenotypic markers by innate and adaptive immunity cells, indicating their activation. In vivo, mice treated with the fucoidan samples demonstrated an increase in the levels of OVA-specific antibodies (IgG, IgG1 and IgG2a) and in the production of cytokines (IFN-γ, IL-2, IL-10). Conclusions: the effects of enzymatically depolymerised fucoidan on functional activity of innate and adaptive immunity cells are comparable to those of native fucoidan. The findings indicate the possibility of using enzymatic hydrolysis products of fucoidan as adjuvants for a wide range of prophylactic and therapeutic vaccines.