Ultraviolet B (UVB) radiation is a major environmental causative factor of skin oxidative damage and photoaging. Lacticaseibacillus paracasei is a well-known probiotic strain that can regulate skin health. The present study investigated the effects of heat-killed Lacticaseibacillus paracasei (PL) on UVB linked oxidative damage and photoaging in skin cells (Normal human dermal fibroblast (NHDF) cells and B16F10 murine melanoma cells). Results demonstrated that: (1) PL prevented UVB-induced cytotoxicity relating to decreased DNA damage in NHDF and B16F10 cells; (2) PL alleviated UVB-induced oxidative damage through increasing GSH content, as well as antioxidant enzyme activities and mRNA levels (except MnSOD activity and mRNA levels as well as CAT mRNA level) relating to the activation of Sirt1/PGC-1α/Nrf2 signaling in NHDF cells; (3) PL attenuated UVB-induced photoaging was noticed with a decrease in the percentage of SA-β-gal positive cells in NHDF cells model. Moreover, PL attenuated UVB-induced photoaging through exerting an anti-wrinkling effect by enhancing the type I collagen level relating to the inhibition (JNK, p38)/(c-Fos, c-Jun) of signaling in NHDF cells, and exerting an anti-melanogenic effect by suppressing tyrosinase and TYRP-1 activity and/or expressions relating to the inhibition of PKA/CREB/MITF signaling in B16F10 cells. In conclusion, PL could ameliorate UVB-induced oxidative damage and photoaging. Therefore, PL may be a potential antioxidant and anti-photoaging active ingredient for the cosmetic industry.

中文翻译：

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热灭活副干酪乳酸杆菌改善 UVB 诱导的氧化损伤和光老化及其潜在机制

紫外线 B (UVB) 辐射是皮肤氧化损伤和光老化的主要环境致病因素。副干酪乳酸杆菌是一种众所周知的益生菌菌株，可以调节皮肤健康。本研究调查了热灭活的副干酪乳酸杆菌的影响。(PL) 关于 UVB 与皮肤细胞（正常人​​真皮成纤维细胞 (NHDF) 细胞和 B16F10 鼠黑色素瘤细胞）中的氧化损伤和光老化有关。结果表明：(1) PL 可防止 UVB 诱导的与 NHDF 和 B16F10 细胞中 DNA 损伤减少相关的细胞毒性；(2) PL通过增加GSH含量以及与Sirt1/PGC-1α/Nrf2激活相关的抗氧化酶活性和mRNA水平(MnSOD活性和mRNA水平以及CAT mRNA水平除外)来减轻UVB诱导的氧化损伤NHDF 细胞中的信号传导；(3) PL减弱了UVB诱导的光老化，在NHDF细胞模型中SA-β-gal阳性细胞的百分比降低。此外，PL 通过增强与抑制相关的 I 型胶原蛋白水平 (JNK, p38)/(c-Fos, c-Jun) 在 NHDF 细胞中的信号传导，并通过抑制 B16F10 细胞中的酪氨酸酶和 TYRP-1 活性和/或与抑制 PKA/CREB/MITF 信号传导相关的表达来发挥抗黑色素生成作用。总之，PL可以改善UVB诱导的氧化损伤和光老化。因此，PL可能是化妆品行业潜在的抗氧化和抗光老化活性成分。