Effect of nano-sized horse oil-in-water emulsion on particulate matter-induced oxidative damage in human HaCaT keratinocytes

Horse oil contains up to 65% unsaturated fatty acids and protects human skin from environmental stressors. This study was performed to investigate the stability and protective effects of nano-sized horse oil-in-water (HO/W) emulsions, including emulsions enhanced with α-tocopherol (HO/W+α-T) or trolox (HO/W+T), against particulate matter (PM)-induced oxidative stress in HaCaT human keratinocytes. Mean particle diameters in these HO/W emulsions ranged from 154.5 to 169.2 nm, classifying them as nano-sized emulsions. The encapsulation efficiencies of HO/W and HO/W+α-T were 89.98-90.79%. The HO/W, HO/W+α-T, and HO/W+T emulsions sufficiently reduced lactate hydrogenase (LDH) release in HaCaT cells that has been exposed to 62.5 mg/mL of PM. The HO/W+α-T emulsion also significantly inhibited PM-induced lipid peroxidation. These results demonstrate that the horse oil O/W emulsion exhibits cytoprotective effects by inhibiting lipid peroxidation and increasing the viability of PM-exposed HaCaT cells, suggesting its potential as a novel strategy for preventing skin damage caused by environmental pollutants.