Paeonol Attenuates UVB-Induced Premature Senescence in Human Dermal Fibroblasts to Promote Skin Longevity

Skin photoaging is largely driven by ultraviolet (UV) irradiation, which contributes to chronic inflammation and extracellular matrix (ECM) degradation. This study investigated the protective effects of paeonol against UVB-induced cellular senescence in human dermal fibroblasts (HDFn). Repeated UVB irradiation was used to induce premature senescence. Paeonol treatment reduced the senescence-associated β-galactosidase (SA-β-gal) positive cells and intracellular reactive oxygen species (ROS) accumulation. Paeonol also reduced the expression of senescence-associated cell cycle regulators, including p21 and p16 at the mRNA level and the protein level. In addition, paeonol suppressed matrix metalloproteinase-1 (MMP-1) production but did not significantly restore type I procollagen secretion. Paeonol also attenuated the expression and secretion of the senescence-associated secretory phenotype (SASP) factors inter-leukin-6 (IL-6) and interleukin-8 (IL-8). These effects were accompanied by reduced phosphorylation of JNK and c-Jun. Furthermore, activation of JNK signaling with anisomycin partially reversed the paeonol-mediated suppression of MMP-1 mRNA expression, supporting the involvement of JNK signaling in the regulation of MMP-1. Collectively, these findings suggest that paeonol attenuates multiple features of UVB-induced cellular senescence in HDFn cells, with JNK signaling potentially contributing to its inhibitory effect on MMP-1 expression. Further studies are needed to clarify the mechanisms underlying these effects and establish their physiological relevance in UVA-based and in vivo models.