Fucoidan Extracts Ameliorate Acute Colitis

Abstract

Inflammatory bowel diseases (IBD), such as ulcerative colitis and Crohn's disease, are an important cause of morbidity and impact significantly on quality of life. Overall, current treatments do not sustain a long-term clinical remission and are associated with adverse effects, which highlight the need for new treatment options. Fucoidans are complex sulphated, fucose-rich polysaccharides, found in edible brown algae and are described as having multiple bioactivities including potent anti-inflammatory effects. Therefore, the therapeutic potential of two different fucoidan preparations, fucoidan-polyphenol complex (Maritech Synergy) and depyrogenated fucoidan (DPF) was evaluated in the dextran sulphate sodium (DSS) mouse model of acute colitis. Mice were treated once daily over 7 days with fucoidans via oral (Synergy or DPF) or intraperitoneal administration (DPF). Signs and severity of colitis were monitored daily before colons and spleens were collected for macroscopic evaluation, cytokine measurements and histology. Orally administered Synergy and DPF, but not intraperitoneal DPF treatment, significantly ameliorated symptoms of colitis based on retention of body weight, as well as reduced diarrhoea and faecal blood loss, compared to the untreated colitis group. Colon and spleen weight in mice treated with oral fucoidan was also significantly lower, indicating reduced inflammation and oedema. Histological examination of untreated colitis mice confirmed a massive loss of crypt architecture and goblet cells, infiltration of immune cells and oedema, while all aspects of this pathology were alleviated by oral fucoidan. Importantly, in this model, the macroscopic changes induced by oral fucoidan correlated significantly with substantially decreased production of at least 15 pro-inflammatory cytokines by the colon tissue. Overall, oral fucoidan preparations significantly reduce the inflammatory pathology associated with DSS-induced colitis and could therefore represent a novel nutraceutical option for the management of IBD.

Fig 1. Effect of fucoidan extracts during acute colitis.

(A) Daily changes of body weight during colitis induction in C57BL/6 mice with and without fucoidan extracts treatment versus healthy control. Body weight changes, expressed as percentage, were calculated by dividing body weight on each day with the initial body weight before the start of DSS treatment. Stool samples were scored for (B) consistency and (C) occult blood on a daily basis during experiment. Data represent percentage or mean ± SD of n = 6–10 animals. Significance is indicated by *p < 0.05 and **p < 0.01 using two-way ANOVA followed by Tukey’s post-test. Healthy control (HC); untreated colitis (DSS); intraperitoneal injection of depyrogenated fucoidan (IPDPF); oral treatment of depyrogenated fucoidan (ODPF); oral treatment of Maritech Synergy (OS).

Fig 2. Effect of fucoidan extracts on colon and spleen.

Colons were measured for their length (A) and weight. Spleens were also removed and weighed. The organ weights were then presented as a ratio of colon weight (B) or spleen weight (C) over body weight respectively. Data represent the mean ± SD of n = 6–10 animals. Significance is indicated by *p < 0.05 and **p < 0.01 using one-way ANOVA followed by Dunnett’s post-test. Healthy control (HC); untreated colitis (DSS); intraperitoneal injection of depyrogenated fucoidan (IPDPF); oral treatment of depyrogenated fucoidan (ODPF); oral treatment of Maritech Synergy (OS).

Fig 3. Effect of fucoidan extracts on colon histology.

Representative hematoxylin and eosin stained colon sections of healthy controls, untreated mice with colitis and colitic mice that received fucoidan extracts. Scale bars = 100 μm for 400× and 400 μm for 100× magnification. Healthy control (HC); untreated colitis (DSS); intraperitoneal injection of depyrogenated fucoidan (IPDPF); oral treatment of depyrogenated fucoidan (ODPF); oral treatment of Maritech Synergy (OS).

Fig 4. Effect of fucoidan extracts on colon tissue.

Cumulative histology damage scores for (A) proximal colon (PC) and (B) distal colon (DC). Data represent the mean ± SD of n = 6–10 animals. Significance is indicated by *p < 0.05 and **p < 0.01 using one-way ANOVA followed by Dunnett’s post-test. Healthy control (HC); untreated colitis (DSS); intraperitoneal injection of depyrogenated fucoidan (IPDPF); oral treatment of depyrogenated fucoidan (ODPF); oral treatment of Maritech Synergy (OS).

Fig 5. Effect of fucoidan extracts on colon-derived cytokine levels.

Distal colon tissue samples were cultured for 24 hours. The supernatants were assessed for cytokine levels using a Bio-Plex assay kit. Cytokine levels in the supernatant were normalized to tissue weight to obtain pg / ml of cytokines/ 10 mg of tissue. Data represent minimum, 25th percentile, median, mean, 75 percentile and maximum of cytokine levels of n = 5 animals. Significance is indicated by *p < 0.05 and **p < 0.01 using one-way ANOVA followed by Dunnett’s post-test. Interleukin (IL); tumor necrosis factor-α (TNF-α); granulocyte colony-stimulating factor (G-CSF); granulocyte-macrophage colony-stimulating factor (GM-CSF); macrophage inflammatory protein (MIP); regulated and normal T cells expressed and secreted (RANTES); interferon-γ (IFN-γ); healthy control (open circle); untreated colitis (closed circle); intraperitoneal injection of depyrogenated fucoidan (closed square); oral treatment of depyrogenated fucoidan (closed diamond); oral treatment of Maritech Synergy (closed triangle).

Fig 6. Correlation between colon-derived cytokine levels and treatment-induced changes to body weight.

Changes in cytokine levels by fucoidan extracts were correlated with the changes to body weight for individual mice. The value of Pearson correlation coefficient (r²) is reported and significance is indicated by p value. Interleukin (IL); tumor necrosis factor-α (TNF-α); granulocyte colony-stimulating factor (G-CSF); granulocyte-macrophage colony-stimulating factor (GM-CSF); macrophage inflammatory protein (MIP); regulated and normal T cells expressed and secreted (RANTES); interferon-γ (IFN-γ); healthy control (HC); untreated colitis (DSS); intraperitoneal injection of depyrogenated fucoidan (IPDPF); oral treatment of depyrogenated fucoidan (ODPF); oral treatment of Maritech Synergy (OS).