Abstract
Natural marine polysaccharides have demonstrated immune stimulatory effects in both mice and humans. Our previous study compared the ability of ascophyllan and fucoidan to activate human and mouse dendritic cells (DCs). In this study, we further examined the effect of ascophyllan on the activation of mouse natural killer (NK) cells in vivo and in vitro and compared it to that of fucoidan, a well-studied natural marine polysaccharide. Specifically, administration of ascophyllan to C57BL/6 mice increased the number of NK cells in the spleen when compared to the number in PBS-treated mice. Moreover, the number of IFN-γ-producing NK cells and expression of CD69 were markedly upregulated by ascophyllan treatment. Ascophyllan treatment also induced IFN-γ production and CD69 upregulation in isolated NK cells, but did not promote cell proliferation. Finally, ascophyllan treatment increased the cytotoxicity of NK cells against Yac-1 cells. The effects of ascophyllan on NK cell activation were considerably stronger than those of fucoidan. These data demonstrated that ascophyllan promotes NK cell activation both in mice and in vitro, and its stimulatory effect on NK cells is stronger than that of fucoidan.
Highlights
Natural marine polysaccharides show various bioactivities, including anti-diabetic, anti-inflammatory, anti-bacterial, anti-viral, and immunostimulatory activities [1,2].plant metabolites are well conserved from algae to higher plants, indicating that these molecules are of great biological value to these organisms [3,4]
We evaluated the effect of ascophyllan on natural killer (NK) cell activation in mice and compared it with the effects of fucoidan
Treatment with ascophyllan increased the frequency of NK1.1+ CD3− cells in the spleen and blood compared to those in mice treated with PBS at 6 h after injection (Figure 1B)
Summary
Natural marine polysaccharides show various bioactivities, including anti-diabetic, anti-inflammatory, anti-bacterial, anti-viral, and immunostimulatory activities [1,2].plant metabolites are well conserved from algae to higher plants, indicating that these molecules are of great biological value to these organisms [3,4]. Natural marine polysaccharides show various bioactivities, including anti-diabetic, anti-inflammatory, anti-bacterial, anti-viral, and immunostimulatory activities [1,2]. Polysaccharide components from algae have immunomodulatory effects in humans and mice. Fucoidan, a well-studied marine polysaccharide, can activate dendritic cells (DCs), natural killer (NK) cells, neutrophils, and T cells [5,6,7,8]. We showed that ascophyllan purified from Ascophyllum nodosum (A. nodosum) had immune cell activation effects that were comparable to those of fucoidan [9,10,11]. Ascophyllan is a heterogeneous sulfated polysaccharide that is clearly distinguishable by its monosaccharide composition from fucoidan, which mainly contains fucose as its sugar component [12,13]
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