*2.6. Astaxanthin Exhibited Inhibitive Effects on Cytokine Production in LPS-Induced DCs and LPS-Challenged Mice*

To investigate whether astaxanthin modulated the production of cytokines in LPSinduced DCs, the levels of interleukin-1β (IL-1β), interleukin-17 (IL-17), and transforming growth factor-beta (TGF-β) in supernatants of DCs were measured by an enzyme-linked immunosorbent assay (ELISA). After being exposed to LPS (100 ng/mL) for 24 h, the secretion of IL-1β, IL-17, and TGF-β cytokines was upregulated, whereas it was significantly inhibited by the treatment of astaxanthin in a dose-dependent manner (Figure 7A–C). LPSinduced sepsis is associated with overloaded cytokines [29]; therefore, serum samples were collected from mice. As shown in Figure 7D–F, LPS administration markedly increased the levels of IL-1β, IL-17, and TGF-β in mice. As expected, astaxanthin treatment significantly decreased the expression of these cytokines in a dose-dependent manner. These results suggested that astaxanthin strongly inhibited cytokine production in LPS-induced DCs and LPS-challenged mice.

**Figure 7.** Astaxanthin efficiently impaired the secretion of cytokines in LPS-induced DCs and LPSchallenged mice. (**A**–**C**) DCs were incubated with the indicated concentrations of astaxanthin and LPS (100 ng/mL) for 24 h. (**D**–**F**) C57BL/6 mice were orally given astaxanthin before LPS injection, and then serum was sampled at 4 h after LPS injection. Levels of IL-1β, IL-17, and TGF-β in DC supernatants or serum were measured by ELISA. Results are from one representative experiment of three performed. Data are presented as means ± SD. The comparisons were performed with analysis of variance (ANOVA) (multiple groups). Different lowercase letters indicate significant differences between groups (*p* < 0.05).
