Particulate matter 2.5 damages skin cells by inducing oxidative stress, subcellular organelle dysfunction, and apoptosis

The skin is the largest organ of the human body and the one mostly exposed to outdoor contaminants. To evaluate the biological mechanisms underlying skin damage caused by fine particulate matter (PM(2.5)), we analyzed the effects of PM(2.5) on cultured human keratinocytes and the skin of experimental animals. PM(2.5) was applied to human HaCaT keratinocytes at 50 µg/mL for 24 h and to mouse skin at 100 µg/mL for 7 days. The results indicate that PM(2.5) induced oxidative stress by generating reactive oxygen species both in vitro and in vivo, which led to DNA damage, lipid peroxidation, and protein carbonylation. As a result, PM(2.5) induced endoplasmic reticulum stress, mitochondrial swelling, and autophagy, and caused apoptosis in HaCaT cells and mouse skin tissue. The PM(2.5)-induced cell damage was attenuated by antioxidant N-acetyl cysteine, confirming that PM(2.5) cellular toxicity was due to oxidative stress. These findings contribute to understanding of the pathophysiological mechanisms triggered in the skin by PM(2.5), among which oxidative stress may play a major role.