Hesperidin Protects Human HaCaT Keratinocytes from Particulate Matter 2.5-Induced Apoptosis via the Inhibition of Oxidative Stress and Autophagy

Numerous epidemiological studies have reported that particulate matter 2.5 (PM(2.5)) 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 PM(2.5)-mediated damage in a human skin cell line (HaCaT). Hesperidin reduced PM(2.5)-induced intracellular reactive oxygen species (ROS) generation and oxidative cellular/organelle damage. PM(2.5) 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 PM(2.5)-induced autophagy and apoptosis. PM(2.5) 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 PM(2.5)-induced cellular apoptosis. Furthermore, hesperidin restored PM(2.5)-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 PM(2.5)-induced skin damage by mitigating excessive ROS accumulation, autophagy, and apoptosis.