Photoprotective effects of Bifidobacterium breve supplementation against skin damage induced by ultraviolet irradiation in hairless mice

Background: Probiotics have been considered to affect not only the gut but also the skin. This study aimed at examining whether oral administration of live Bifidobacterium breve strain Yakult (BBY), a typical probiotic, could exert photoprotective effects in hairless mouse skin. Methods: BBY cell suspensions and fermented milk containing BBY (BBYM) were orally administered to hairless mice for 9 and 14 days, respectively. Mice were irradiated with ultraviolet (UV) light daily for the last four consecutive days. Twenty-four hours after the final irradiation, skin elasticity, appearance, elastase activity and interleukin (IL)-1 beta levels were evaluated in the dorsal skin. Results: BBY and BBYM significantly prevented UV-induced deleterious changes in skin elasticity and appearance. BBY suppressed the increases in both elastase activity and IL-1 beta levels in the skin. There was a significant negative correlation between elastase activity and the ratio of elastic recovery to total deformation and a significant positive correlation between elastase activity and the area ratio of furrows, independent of UV irradiation or BBY administration. Conclusion: Our findings suggest that oral administration of probiotic BBY has the potential to prevent UV-induced skin damage, supporting the hypothesis that probiotics are beneficial not only to the intestine but also to the skin.