Physiological and Histological Characterization of Chemically Induced Nanoplastic Forced Skin Aging in Mice

Background: NPs and chemical aging, are well documented, but the interactions of these components physiologically on the skin's integrity are not yet well characterized. Objective: To elucidate the effects of polystyrene NP exposure and D-galactose mediated accelerated ageing of the mouse skin. Methodology: Forty male C57BL/6 mice were divided into four groups: Control, NP exposure, Chemical aging, and Combined exposure. The topical treatments were repeated over 4 weeks. Macroscopic observations, transepidermal water loss (TEWL), elasticity, hydration and molecular analysis were performed. Results: Combined exposure showed significant effect on accelerating aging of skin. The combined group had an increase in TEWL values of nearly threefold as compared to the control group, with a value of 15.3±2.1 g/m²/h for the combined group, marking a severe barrier impairment. Skin elasticity dropped to 0.48±0.09 U f and hydration levels to 38.9±7.1. On the molecular level, a significant increase in malondialdehyde (5.1±0.7 mmol/mg) and a dramatic decrease in SOD (55.3±7.5 U/mg) was noted in the combined group. In addition, the pro-inflammatory cytokines, TNF-α and IL-6, were markedly increased to reveal synergic induction of oxidative stress and chronic inflammation by the combination of the two, which was synergistic effects of individual treatments alone. Conclusions: Exposure to nanoplastic significantly increases the chemically induced skin aging through disrupted skin barrier, increased oxidative, and inflammatory responses. The results demonstrate the importance of the risk associated with nanoplastics on skin health.