Astaxanthin, a xanthophyll carotenoid, prevents development of dextran sulphate sodium-induced murine colitis

Abstract

Astaxanthin is a xanthophyll carotenoid, which possesses strong scavenging effect on reactive oxygen species. In this study, we examined the effect of astaxanthin on dextran sulfate sodium (DSS)-induced colitis in mice. Experimental colitis was induced by the oral administration of 4% w/v DSS in tap water in C57BL/6J mice. Astaxanthin was mixed with a normal rodent diet (0.02 or 0.04%). Astaxanthin significantly ameliorated DSS-induced body weight loss and reduced the disease activity index. The ameliorating effects was observed in a dose-dependent manner. Immunochemical analyses showed that astaxanthin markedly suppressed DSS-induced histological inflammatory changes (inflammatory cell infiltration, edematous changes and goblet cell depletion). Plasma levels of malondialdehyde and 8-hydroxy-2-deoxyguanosine were significantly reduced by the administration of 0.04% astaxanthin. Astaxanthin significantly suppressed the mucosal mRNA expression of IL-1β, IL-6, TNF-α, IL-36α and IL-36γ. Astaxanthin blocked the DSS-induced translocation of NF-κB p65 and AP-1 (c-Jun) into the nucleus of mucosal epithelial cells, and also suppressed DSS-induced mucosal activation of MAPKs (ERK1/2, p38 and JNK). In conclusion, astaxanthin prevented the development of DSS-induced colitis via the direct suppression of NF-κB, AP-1 and MAPK activation. These findings suggest that astaxanthin is a novel candidate as a therapeutic option for the treatment of inflammatory bowel disease.

Keywords: carotenoid; inflammatory bowel disease; reactive oxygen species.

Fig. 1

The effect of astaxanthin on the development of DSS colitis. Astaxanthin was mixed with a normal rodent diet (0.02 or 0.04%). (A) Body weight, (B) disease activity index and (C) colonic weight/length. All data are means ± SEM (n = 5/group). Values not sharing a letter denote significant differences (p<0.05). AX, astaxanthin.

Fig. 2

Histological evaluation of DSS-colitis. (A) Histological picture of the colonic tissue on day 10 (original magnification ×100). (B) Histological score. All data are means ± SEM (n = 5/group). Values not sharing a letter denote significant differences (p<0.05). AX, astaxanthin.

Fig. 3

The effect of astaxanthin on plasma index of lipid peroxidation (MDA) and oxidative DNA damage (8-OHdG). Astaxanthin significantly reduced the elevation of plasma MDA and 8-OHdG levels. All data are means ± SEM (n = 5/group). Values not sharing a letter denote significant differences (p<0.05). AX, astaxanthin.

Fig. 4

The effect of astaxanthin on NF-κB and AP-1 activation in DSS mice. Immunohistochemical staining was performed for detection of mucosal activation of NF-κB p65 and c-Jun (original magnification ×400). NF-κB p65 and P-c-Jun was detected in the nucleus of the colonic epithelial cells in DSS-mice, but this was markedly blocked in the DSS plus 0.04% astaxanthin group. AX, astaxanthin.

Fig. 5

Immunoblot analyses for evaluation of NF-κB, AP-1 and MAPKs activation in colonic epithelial cells isolated from DSS mice. (A) The nuclear protein was extracted from epithelial cells of DSS mice, and NF-κB and phosphorylated (P) c-Jun were evaluated by immunoblotting. (B) The cytoplasmic protein was extracted from epithelial cells of DSS mice, and total and phosphorylated ERK1/2, p38 and JNK1 were evaluated by immunoblotting. The picture is representative of three independent experiments. AX, astaxanthin.

Fig. 6

Immunoblot analyses for evaluation of NF-κB, AP-1 and MAPK activation in HT-29 colonic epithelial cells. HT-29 cells were stimulated with TNF-α (100 ng/ml) in the presence or absence of astaxanthin for 10 min. Then, the nuclear and cytoplasmic proteins were extracted. (A) Accumulation of NF-κB p65 and phosphorylated (P) c-Jun in the nucleus were evaluated by immunoblotting. (B) The cytoplasmic proteins were subjected to immunoblotting to evaluate phosphorylated ERK1/2, p38 and JNK1. The picture is representative of three independent experiments. AX, astaxanthin.

Fig. 7

The effect of astaxanthin on the mRNA expression of proinflammatory cytokines. Mucosal mRNA expression for TNF-α, IL-1β, IL-6, IL-36α and IL-36γ was evaluated by real time-PCR. The mRNA expressions of cytokines were converted to a value relative to β-actin mRNA expression and revealed as a relative increase to the results for control mice. All data are means ± SEM (n = 5/group). Values not sharing a letter denote significant differences (p<0.05). AX, astaxanthin.