AUTHOR=Chen Huizhen , Li Ying , Xie Xinqiang , Chen Moutong , Xue Liang , Wang Juan , Ye Qinghua , Wu Shi , Yang Runshi , Zhao Hui , Zhang Jumei , Ding Yu , Wu Qingping TITLE=Exploration of the Molecular Mechanisms Underlying the Anti-Photoaging Effect of Limosilactobacillus fermentum XJC60 JOURNAL=Frontiers in Cellular and Infection Microbiology VOLUME=12 YEAR=2022 URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.838060 DOI=10.3389/fcimb.2022.838060 ISSN=2235-2988 ABSTRACT=

Although lactic acid bacteria (LAB) were shown to be effective for preventing photoaging, the underlying molecular mechanisms have not been fully elucidated. Accordingly, we examined the anti-photoaging potential of 206 LAB isolates and discovered 32 strains with protective activities against UV-induced injury. All of these 32 LABs exhibited high levels of 2,2-diphenyl-picrylhydrazyl, as well as hydroxyl free radical scavenging ability (46.89–85.13% and 44.29–95.97%, respectively). Genome mining and metabonomic verification of the most effective strain, Limosilactobacillus fermentum XJC60, revealed that the anti-photoaging metabolite of LAB was nicotinamide (NAM; 18.50 mg/L in the cell-free serum of XJC60). Further analysis revealed that LAB-derived NAM could reduce reactive oxygen species levels by 70%, stabilize the mitochondrial membrane potential, and increase the NAD+/NADH ratio in UV-injured skin cells. Furthermore, LAB-derived NAM downregulated the transcript levels of matrix metalloproteinase (MMP)-1, MMP-3, interleukin (IL)-1β, IL-6, and IL-8 in skin cells. In vivo, XJC60 relieved imflammation and protected skin collagen fiber integrity in UV-injured Guinea pigs. Overall, our findings elucidate that LAB-derived NAM might protect skin from photoaging by stabilizing mitochondrial function, establishing a therotical foundation for the use of probiotics in the maintenance of skin health.