The role of lactobacilli in inhibiting skin pathogens

Abstract

The human skin microbiota forms a key barrier against skin pathogens and is important in modulating immune responses. Recent studies identify lactobacilli as endogenous inhabitants of healthy skin, while inflammatory skin conditions are often associated with a disturbed skin microbiome. Consequently, lactobacilli-based probiotics are explored as a novel treatment of inflammatory skin conditions through their topical skin application. This review focuses on the potential beneficial role of lactobacilli (family Lactobacillaceae) in the skin habitat, where they can exert multifactorial local mechanisms of action against pathogens and inflammation. On one hand, lactobacilli have been shown to directly compete with skin pathogens through adhesion inhibition, production of antimicrobial metabolites, and by influencing pathogen metabolism. The competitive anti-pathogenic action of lactobacilli has already been described mechanistically for common different skin pathogens, such as Staphylococcus aureus, Cutibacterium acnes, and Candida albicans. On the other hand, lactobacilli also have 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, showing that topically applied lactobacilli can temporarily colonize the skin and promote skin health, but more and larger clinical trials are required to generate in vivo mechanistic insights and in-depth skin microbiome analysis.

Selective targeting of skin pathobionts and inflammation with topically applied lactobacilli

“…4 Such strategies have not yet widely been considered for direct application on the skin, in a large part because of the technical challenges. 5 One of the most common skin diseases is acne vulgaris, a chronic inflammatory skin condition of the sebaceous follicles and glands. The pathogenesis of acne vulgaris is multifactorial, with increased sebum production, alteration in the quality of sebum lipids, dysregulation of the hormone environment, and follicular hyperkeratinization as contributing factors.…”

“… 4 Such strategies have not yet widely been considered for direct application on the skin, in a large part because of the technical challenges. 5 …”

Community Composition of Bacteria Isolated from Swiss Banknotes Varies Depending on Collection Environment

“…These are both diverse families that include species closely associated with humans, e.g. as part of the human skin, respiratory tract or gut microbiome (Cogen et al , 2008; Fierer et al , 2008; Murphy and Parameswaran, 2009; Kim et al , 2013; Fourquin-Gomez et al , 2014; Robert-Pillot et al , 2014; Rock and Donnenberg, 2014; Delanghe et al , 2021; Skowron et al , 2021), but have also been isolated from animal hosts and soil and aquatic environments (Cousin, 1999; Madhaiyan et al , 2020). Other families were detected in significant abundance, but only in subsets of samples, such as Vibrionaceae and Lactobacillaceae (in 21 and 30 samples out of 42 respectively).…”

“…1B) including families found before in humans and human-associated environments, e.g. the human skin, gut or respiratory tract microbiome, or human food production (Cogen et al , 2008; Fierer et al , 2008; Murphy and Parameswaran, 2009; Oren, 2011; Fourquin-Gomez et al , 2014; Delanghe et al , 2021; Skowron et al , 2021). The evidence from our data set that community composition varied depending on the shop type in which each banknote was collected is surprising: this suggests money has a microbiome reflecting its local environment, even though we assume banknotes are only transiently exposed to each habitat/shop type.…”

Targeted Screening of Lactic Acid Bacteria With Antibacterial Activity Toward Staphylococcus aureus Clonal Complex Type 1 Associated With Atopic Dermatitis

“…Another antimicrobial mechanism indicated by co-aggregation is competitive displacement of the pathogen with some LAB strains showing high affinity binding to epithelial cell receptors (Lukic et al, 2017;Spacova et al, 2020). Several studies demonstrate antimicrobial effects of LAB on S. aureus (Blanchet-Réthoré et al, 2017;Jayashree et al, 2018;Spacova et al, 2020;Delanghe et al, 2021;Musa et al, 2021) and recent findings indicate, that aggregation of lactobacilli to S. aureus is important for the ability of lactobacilli to prevent or reduce S. aureus adhesion to epithelial surfaces (Younes et al, 2016). Previous study has shown that topical application of LAB in a cream formulation can have beneficial effect on AD symptoms and S. aureus colonization on skin (Blanchet-Réthoré et al, 2017;Butler et al, 2020).…”