Characterization of a live Cutibacterium acnes subspecies defendens strain XYCM42 and clinical assessment as a topical regimen for general skin health and cosmesis

Background When formulating topical products to treat skin diseases and addressing general skin health and cosmesis, most of the focus has traditionally been placed on how any given ingredient may impact the structure, function, and health of human skin elements. However, recent research is beginning to highlight the importance of the skin microbiome in relation to certain skin conditions and general cosmesis. Cutibacterium acnes is one of the most prolific skin‐specific bacterial species. Research has shown that the species is divided into subspecies, some of which are thought to be beneficial to the skin. This paper aims to determine the efficacy of strainXYCM42, a C. acnes subspecies defendens derived strain designed to improve the health and appearance of the skin. Methods In vitro studies were performed on human keratinocyte and fibroblast monolayers, human peripheral blood mononuclear cells (PBMC), and skin explants to elucidate the effects of live XYCM42 cells and their ferment on human skin cells and tissues. Subsequently, clinical studies were performed using XYCM42‐based topical regimens designed to deliver and support the engraftment of live XYCM42 cells onto subjects' skin. Two studies were performed, a 3‐week pilot study (n = 10) and a 8‐week pivotal study (n = 121). In the latter, 32 subjects were enrolled for an in‐clinic portion for efficacy evaluation, with clinic visits occurring at Baseline, Week 1, Week 4, and Week 8. Results In vitro data suggest that XYCM42 and its ferment filtrate have potential to provide benefits to the skin via antioxidant, anti‐inflammatory, and select antimicrobial activities. Clinical observation demonstrated that a XYCM42‐containing regimen supports a healthy skin environment, promotes increased skin hydration, decreases erythema, calms the skin, and regulates sebum production. Conclusion These studies provide further evidence that specific strains of C. acnes, such as XYCM42, have a more beneficial function regarding skin health and appearance than was previously thought. Appropriate use of formulations derived from symbiotic strains within the skin microbiome can support the development of novel, beneficial topicals.