Lactobacillus reuteri DSM 17938 : A comparative study on the effect of probiotics and lysates on human skin.

Human skin microbiota might play an important role in maintaining skin health and potentially prevent premature skin ageing. The use of probiotics in therapeutic skin applications is an attractive idea, as it could offer an alternative option for certain inflammatory skin disorders and dry or sensitive skin. Here, we investigated for the first time, a comparative study of live and the lysate products of probiotic strain Lactobacillus reuteri DSM 17938 in skin topical applications using ex vivo skin models focusing on anti-inflammatory and skin barrier function and in vitro assays for antimicrobial activity. Our results in ultraviolet B radiation (UVB-R)-induced inflammation model demonstrated that both live bacteria and the lysate of L. reuteri DSM 17938 reduced proinflammatory IL-6 and IL-8, illustrated in both reconstructed human epidermis (RHE) and native skin models. Live L reuteri DSM 17938 significantly increased aquaporin 3 (AQP3) gene expression, while the lysate enhanced laminin A/B levels in a healthy (unstimulated) state of RHE, suggesting a positive impact on skin barrier. In addition, live L. reuteri DSM 17938 had antimicrobial action against pathogenic skin bacteria (Staphylococcus aureus, Streptococcus pyogenes M1, Cutibacterium acnes AS12, Pseudomonas aeruginosa), whereas the lysate did not have such an effect. Therefore, it is hypothesized that L. reuteri DSM 17938 could be beneficial for general skin health, to avoid the UVB-R-mediated inflammatory cascade and/or prevent photoageing, improve barrier function or in the management of unhealthy skin prone to inflammatory conditions due to its antimicrobial, anti-inflammatory and skin barrier enhancing functions