Fucoxanthin in association with vitamin C acts as modulators of human neutrophil function

Neutrophils provide the first line of defense of the innate immune system by phagocytosing, killing and digesting bacteria and fungi. During this process, neutrophils produce reactive oxygen species (ROS), which in excess, can damage the cells themselves and surrounding tissues. The carotenoid fucoxanthin (Fc) has been studied concerning its antioxidant and anti-inflammatory actions. Vitamin c (Vc) also demonstrates potent antioxidant action. This study aimed to evaluate the effect of Fc (2 μM) in association with Vc (100 μM) on functional parameters of human neutrophils in vitro.

We evaluated the migration and phagocytic capacity, intracellular calcium mobilization, ROS production (O₂(·)⁻, H₂O₂, HOCl), myeloperoxidase activity, profile of antioxidant enzymes, phosphorylation of p38 MAPK and p65 NFκB subunit, GSH/GSSG ratio and release of pro-inflammatory cytokines (TNF-α and IL-6) in neutrophils under different stimuli.

We verified an increase in phagocytic capacity for all treatments, together with an increase in intracellular calcium only in cells treated with Fc and Fc + Vc. ROS production was reduced by all treatments, although Vc was a better antioxidant than Fc. Phosphorylation of the p-65 subunit of NFκB was reduced in cells treated with Fc + Vc and release of TNF-α and IL-6 was reduced by all treatments. These findings indicate that the regulation of inflammatory cytokines by neutrophils is not exclusively under the control of the NFκB pathway. Fc reduced the activity of some antioxidant enzymes, whereas Vc increased GR activity and the GSH/GSSG ratio.

In conclusion, the results presented in this study clearly show an immunomodulatory effect of the carotenoid fc alone or in combination with Vc on the function of human neutrophils.