Rapamycin Alleviates Age-Related Senescence in Human Facial Dermal Fibroblasts by Modulating Autophagy

Introduction : Intrinsic skin aging is associated with reduced autophagic activity and dermal fibroblast senescence. Although rapamycin has shown anti-aging effects in stress-induced senescence models, its effects on naturally aged human skin fibroblasts and their age dependence remain unclear. Objective : This study investigated the effects and underlying mechanisms of low-dose rapamycin on senescence-associated phenotypes and autophagy signaling in human facial skin fibroblasts (HSFs) from women of different ages. Methods : An age-stratified model of physiological skin aging was established using primary HSFs isolated from discarded facial skin tissues of healthy female donors aged 20–29 years (Group 1), 30–39 years (Group 2), and 40–49 years (Group 3). After optimization, exponentially growing HSFs were treated with 0.1 nmol/L rapamycin for 48 h. Cellular senescence was assessed by SA-β-gal staining, and cell-cycle distribution was analyzed by flow cytometry. Immunofluorescence, quantitative real-time PCR, and Western blotting were used to assess mTOR and the autophagy-related markers Beclin-1 and LC3B at the mRNA and protein levels. Results : Basal expression of autophagy-related markers progressively declined with increasing donor age. Treatment with 0.1 nmol/L rapamycin significantly reduced the proportion of SA-β-gal-positive cells across all age groups and increased the proportion of cells in the G0/G1 phase, accompanied by a reduction in the proportion of cells in the S phase. At the molecular level, rapamycin suppressed mTOR expression and increased the mRNA and protein expression of Beclin-1 and LC3B, indicating activation of autophagy-related signaling. Notably, the response to rapamycin varied among the age groups. HSFs derived from women aged 40–49 years exhibited the greatest increases in autophagy-related markers and the most pronounced improvement in senescence-associated phenotypes. Conclusions: Low-dose rapamycin may alleviate age-related senescence in human facial skin fibroblasts by inhibiting mTOR signaling and enhancing autophagy-related activity. Among the age groups examined, fibroblasts derived from women aged 40–49 years showed the greatest responsiveness to rapamycin. These findings provide an in vitro basis for the future development of age-stratified and locally targeted interventions for facial skin aging.