Investigation the Anti-inflammatory Effect of Astaxanthin on Inhibiting TLR4 and Some Inflammatory Cytokines in macrophages cell

Inflammation is a protective physiologic response against pathogens, trauma and injury (1, 2). Inflammation pathway are different in human body and some main pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α have key role in pathogenesis of inflammation (3). Current anti-inflammatory drugs including corticosteroids and non-steroid anti-inflammatory drugs have serious side effects (6), so, research on new compounds with anti-inflammatory property is necessary. Astaxanthin is a natural carotenoid with various pharmacological effects. Haematococcus Algae is one of the marine sources of astaxanthin. Anti-inflammatory and antioxidant effects of astaxanthin were reported in previous studies (8-10), but the molecular mechanism of the anti-inflammatory effect of astaxanthin on the peripheral cells of the immune system is not clear. The aim of this study was to evaluate anti-inflammatory effects of astaxanthin on TLR4 gene expression and secretion of key inflammatory cytokines including IL-1, IL-6, and TNFα in RAW264.7 macrophage cells.

Methods and Material: 

The RAW264.7 macrophage cells was used in this study. Astaxanthin was extracted from Haematococcus Algae, then different doses of 25, 50, 100 μM of astaxanthin were used to treat the cells. Cells divided to three groups: one group received LPS (1µg/ml), Treatment group received LPS (1µg/ml) in combination to different dose of astaxanthin (25, 50, 100 μM) and control group without LPS astaxanthin. After 24 hour incubation, cell viability was assay with MMT test.TLR4 gene expression was measured by RT-PCR at 24 and 48 hours after induction with LPS. β-actin was considered as housekeeping gene. The levels of IL-1β, IL-6, and TNFα cytokines were measured with a commercial sandwich ELISA kit. The optic absorbance was read at 45 nm. Descriptive statistics and one-way ANOVA test were used to analyze the data. To analysis the fold change of gene expression, formula 2 -ΔΔCT   was used.

None of different doses of astaxanthin (25, 50, 100 μM) and LPS (1µg/ml) had no toxicity effect on macrophages cell. (P>0.05). LPS increased TLR 4 gene expression at both 24 and 48 hours after induction, (P <0.001) in compare to control group.