Fucoidan from Fucus vesiculosus Inhibits Inflammatory Response, Both In Vitro and In Vivo

Abstract

Fucoidan has been reported to present diverse bioactivities, but each extract has specific features from which a particular biological activity, such as immunomodulation, must be confirmed. In this study a commercially available pharmaceutical-grade fucoidan extracted from Fucus vesiculosus, FE, was characterized and its anti-inflammatory potential was investigated. Fucose was the main monosaccharide (90 mol%) present in the studied FE, followed by uronic acids, galactose, and xylose that were present at similar values (3.8-2.4 mol%). FE showed a molecular weight of 70 kDa and a sulfate content of around 10%. The expression of cytokines by mouse bone-marrow-derived macrophages (BMDMs) revealed that the addition of FE upregulated the expression of CD206 and IL-10 by about 28 and 22 fold, respectively, in respect to control. This was corroborated in a stimulated pro-inflammatory situation, with the higher expression (60 fold) of iNOS being almost completely reversed by the addition of FE. FE was also capable of reverse LPS-caused inflammation in an in vivo mouse model, including by reducing macrophage activation by LPS from 41% of positive CD11C to 9% upon fucoidan injection. Taken together, the potential of FE as an anti-inflammatory agent was validated, both in vitro and in vivo.

Keywords: Fucus vesiculosus; anti-inflammatory; fucoidan; macrophage.

Figure 1

Assessment of polysaccharide cytotoxicity in RAW 264.7 murine macrophages. Cell viability was quantified with CCK-8 assay after incubation with FE for 48 h.

Figure 2

Gene expression of pro- (TNF-α and IL-12) and anti-inflammatory (CD-206 and IL-10) cytokines. Significance was set to a p-value < 0.05. Results are presented as the mean ± standard deviation; ** p < 0.01.

Figure 3

Expression of iNOS (A) and CD206 (B) determined via RT-qPCR, and the amount of IL-10 quantified by ELISA (C); all inflammatory molecules synthesized by BMDM, stimulated or not stimulated by LPS and IFN-γ for 12 h, and after FE incubation for 48 h. Significance was set to a p-value < 0.05. Results are presented as the mean ± standard deviation; * p < 0.05, ** p < 0.01.

Figure 4

Morphology of inner organ (lung and heart) stained by H&E. Red (lung) and black (heart) arrows highlight morphological changes in the tissues, more evident in the group treated with LPS but mostly reversed when FE was also injected.

Figure 5

Flow cytometry analysis of F4/80 and CD11C expressed by peritoneal macrophages. (A) Flow cytometry histograms. (B) Relative percentage of F4/80 and CD11C markers. (C) Statistic analysis of specifically marked cells; ns—difference not statistically significant, ** p < 0.01, *** p < 0.001.