Galangin Mitigates PM_2.5-Induced Endoplasmic Reticulum Stress and Senescence in HaCaT Keratinocytes

Exposure to particulate matter 2.5 (PM_2.5) can negatively impact human skin, leading to issues such as wrinkle formation, skin aging, atopic dermatitis, and pigment spots. Galangin, a flavonoid known for its antioxidant property, was investigated for its protective effects on human HaCaT keratinocytes against PM_2.5-induced endoplasmic reticulum (ER) stress and cellular senescence via the activation of the p38 mitogen-activated protein kinase (MAPK)-mediated signaling pathway. In this study, cells were pretreated with galangin before exposure to PM_2.5. Galangin mitigated the PM_2.5-induced increases in reactive oxygen species (ROS), intracellular calcium, and ER stress-associated proteins. Additionally, galangin counteracted PM_2.5-induced cell cycle arrest in the G₀/G₁ phase and restored the levels of cell cycle regulators, matrix metalloproteinases, and inflammatory cytokines. Moreover, the p38 MAPK inhibitor, along with galangin, reversed cell cycle arrest, reduced cell proliferation, and alleviated cellular senescence triggered by PM_2.5. Overall, galangin protected cells against PM_2.5-induced ER stress and senescence via the ROS-p38 MAPK pathway.