278 Role of specific probiotics in skin diseases: new insights from in vitro investigation

Abstract

The aim of this study is to deeply investigate probiotic strains efficacy in the containment of the opportunistic pathogen Staphylococcus aureus, involved in several diseases, such as non melanoma skin cancer (i.e. actinic keratosis and squamous cell carcinoma) and those inflammatory ones, such as psoriasis and atopic dermatitis. Indeed, during the onset and progression of these skin disorders, the dysbiosis of the microbiota leads to the reduction of protective commensal resident bacteria, favoring pathogenic/opportunistic species proliferation (including S. aureus), and to the variation in the expression of their virulence factors. To this purpose, Lactocaseibacillus rhamnosus GG and Lactobacillus johnsonii, two probiotic strains well described by the literature, were grown independently and as co-culture. Viable probiotics inhibitory efficacy on S. aureus was investigated by agar spot test. S. aureus was also cultured for 24, 48 and 72 hours with probiotics-free supernatants (PFSNs), that were characterized by proteomic analysis. Both pathogen planktonic and biofilm forms were analyzed through the viability alamarBlue test. After that, planktonic form was spotted onto agar plates and single colonies were isolated, while biofilm was visualized by crystal violet staining. Viable probiotic strains demonstrate to inhibit S. aureus growth; interestingly, PFSNs alone (both from single and co-cultured strains) act in reducing pathogen plankton viability and in inducing phenotypic changes. Biofilm form, characteristic virulence feature of the pathogen, was inhibited at all times tested. In conclusion, S. aureus over-colonization, crucial factor in the onset and progression of several skin diseases, could be reduced by both viable Lactobacilli and their PFSNs. The deeper investigation of the cross-talk among microbes will help in clarifying their role in several cutaneous disorders.