The mitigation mechanism of morin on PM _2.5 -induced apoptosis by inhibiting mitochondrial damage via the ROS/ERK signaling pathway in human HaCaT keratinocytes

Particulate matter 2.5 (PM_2.5) can penetrate the human skin, causing inflammatory disease, senescence, and carcinogenesis. This study assessed the effects of morin on PM_2.5-induced apoptosis of HaCaT human keratinocytes. According to our results, morin at concentrations up to 12 µg/mL did not exhibit any harmful effects on cells and effectively reduced the generation of reactive oxygen species induced by PM_2.5. Furthermore, morin significantly inhibited PM_2.5-induced macromolecular damage, mitochondrial damage, and expression of pro-apoptotic proteins. Moreover, the cytoprotective effects of morin correlated with the activation of the transcription factor nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 expression. The results of our experiments using a mitogen-activated protein kinase kinase inhibitor indicated that morin protected cells from apoptosis by the extracellular signal-regulated kinase pathway. Morin mitigated skin damage caused by PM_2.5 via attenuation of oxidative stress, mitochondrial dysfunction, and apoptosis.