Numerous epidemiological studies have reported that particulate matter 2.5 (PM2.5) causes skin aging and skin inflammation and impairs skin homeostasis. Hesperidin, a bioflavonoid that is abundant in citrus species, reportedly has anti-inflammatory properties. In this study, we evaluated the cytoprotective effect of hesperidin against PM2.5-mediated damage in a human skin cell line (HaCaT). Hesperidin reduced PM2.5-induced intracellular reactive oxygen species (ROS) generation and oxidative cellular/organelle damage. PM2.5 increased the proportion of acridine orange-positive cells, levels of autophagy-related proteins, beclin-1 and microtubule-associated protein light chain 3, and apoptosis-related proteins, B-cell lymphoma-2-associated X protein, cleaved caspase-3, and cleaved caspase-9. However, hesperidin ameliorated PM2.5-induced autophagy and apoptosis. PM2.5 promoted cellular apoptosis via mitogen-activated protein kinase (MAPK) activation by promoting the phosphorylation of extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38. The MAPK inhibitors U0126, SP600125, and SB203580 along with hesperidin exerted a protective effect against PM2.5-induced cellular apoptosis. Furthermore, hesperidin restored PM2.5-mediated reduction in cell viability via Akt activation; this was also confirmed using LY294002 (a phosphoinositide 3-kinase inhibitor). Overall, hesperidin shows therapeutic potential against PM2.5-induced skin damage by mitigating excessive ROS accumulation, autophagy, and apoptosis.
Keywords: apoptosis; autophagy; hesperidin; human keratinocyte; mitogen-activated protein kinase; particulate matter 2.5.