Oral Administration of Mixed Probiotics Improves Photoaging by Modulating the Cecal Microbiome and MAPK Pathway in UVB-Irradiated Hairless Mice

Scope: Continuous ultraviolet (UV) exposure causes skin photoaging, wrinkle formation, and skin barrier damage. In this study, the protective effect of mixed probiotics (MP) against photoaging in UVB-irradiated Hs68 fibroblasts and SKH-1 hairless mice is investigated. Methods and results: The mice are irradiated with UVB for 8 weeks to induce photoaging, and MP (15 and 50 mg day⁻¹) is orally administered once a day. Skin parameters are measured in the dorsal skin and wrinkle formation factors are analyzed in skin replicas. To evaluate the mitogen-activated protein kinase (MAPK) signaling pathway, western blotting and qRT-PCR are performed. MP (50 mg day⁻¹) significantly improves skin moisture, transepidermal water loss, erythema, and skin thickness. MP also effectively suppresses wrinkle formation by regulating the transcriptional expression of matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs. MP also reduces inflammatory cytokine levels and phosphorylation of extracellular signaling regulatory kinase, Jun N-terminal kinase, and p38 protein. Furthermore, the intestinal microbiome of the MP groups is significantly different compared with that of the UVB group, and the relative abundance of Lactobacillus and Akkermansia is significantly increased. Conclusion: Collectively, these findings suggest that MP modulates the gut microbiome and ameliorates UVB-induced photoaging by downregulating the MAPK pathway.