Lactobacilli as Emerging Microbiome-Based Therapeutics for Skin Health
The human skin microbiota acts as a key barrier against skin pathogens and plays an important role in modulating immune responses. Recent studies have identified lactobacilli as endogenous inhabitants of healthy skin, while inflammatory skin conditions are often associated with a disrupted skin microbiome. Consequently, lactobacilli-based probiotics are being explored as a novel treatment for inflammatory skin conditions through topical application to the skin.
Mechanisms Behind the Protective Role of Lactobacilli on the Skin
This review focuses on the potential beneficial role of lactobacilli (family Lactobacillaceae) in the skin microenvironment, where they can exert multifactorial local mechanisms of action against pathogens and inflammation. On the one hand, lactobacilli have been shown to directly compete with skin pathogens by inhibiting adhesion, producing antimicrobial metabolites, and influencing pathogen metabolism. The competitive anti-pathogenic action of lactobacilli has already been mechanistically characterized for various common skin pathogens, such as Staphylococcus aureus, Cutibacterium acnes, and Candida albicans. On the other hand, lactobacilli also possess an immunomodulatory capacity associated with a reduction in excessive skin inflammation. Their influence on the immune system is mediated by bacterial metabolites and cell wall-associated or excreted microbe-associated molecular patterns (MAMPs). In addition, lactobacilli can also enhance the skin barrier function, which is often disrupted as a result of infection or in inflammatory skin diseases. Some clinical trials have already translated these mechanistic insights into beneficial clinical outcomes, demonstrating that topically applied lactobacilli can temporarily colonize the skin and promote skin health; however, more and larger clinical trials are needed to generate in vivo mechanistic insights and conduct in-depth analysis of the skin microbiome.
Authors: Lize Delanghe, Irina Spacova, Joke Van Malderen, Eline Oerlemans, Ingmar Claes, Sarah Lebeer
