Abstract: In this work, the ameliorative effect of fucoxanthin on visible light-induced phagocytic disturbance of differentiated retinal pigment epithelial (RPE) cells was investigated in a polyunsaturated fatty acids-rich environment and the non-antioxidant pathway involved was explored. The results showed that when exposed to visible light at 3 500 lx, the phagocytic capacity of RPE cells was significantly reduced, and the expression of phagocytic receptors (including Mer tyrosine kinase (MerTK), αV integrin protein, β5 integrin protein and CD36 receptor) on the cell membrane was inhibited to varying degrees. Pretreatment with different concentrations (10.0 and 20.0 μg/mL) of fucoxanthin significantly ameliorated the phagocytic capacity of RPE cells and effectively up-regulated the expression of the above four phagocytic receptors. Specific antibody testing further confirmed that fucoxanthin enhanced the phagocytic capacity of RPE cells mainly by regulating the expression of MerTK, αV integrin protein and β5 integrin protein receptors. In addition, the L-type Ca2+ channel was also shown to be an important pathway for fucoxanthin to improve the phagocytic capacity of RPE cells. These findings provide a theoretical basis for the development of vision-protective functional foods containing fucoxanthin.

Key words: fucoxanthin; retinal pigment epithelial cells; phagocytosis; phagocytic receptors; visible light