The skin is the outer surface of the human body, is the place to commensal microbiota and also acts a physical barrier that protects from invasion of foreign pathogenic microorganisms. Most of the time, the microorganisms constituting the skin microbiome are in harmony with each other and perform their functions of protecting the skin. The disruption in the skin microbiome composition is termed dysbiosis. Functional dysbiosis affects the microbe-host interactions and results in skin disorders. The gut has its microbiome similar to the skin. Several research studies link inflammatory skin diseases with the imbalanced gut microbiome. In recent years, interest has significantly expanded beyond the gut microbiome to include the skin microbiome and its influence in several skin disorders. If there is dysbiosis in the gut microbiome, then the altered gut microflora may result in autoimmune and inflammatory conditions not only in the gut but also in distant organs such as the skin. The connection between the skin and gut seems to be mediated by the host immune system. The interaction between the microorganisms and the host immune system is important to maintain skin homeostasis. Therefore, balancing the skin microbiota may be a treatment for a variety of skin conditions. Probiotics play a vital role in restoring the microbiome and are an important therapeutic modality in the treatment of inflammatory skin diseases. With our growing knowledge about the role of the microbiome in various skin diseases, modulating the immune system by restoring the balance in the microbiome becomes a new avenue of treatment. The direct approach to this kind of treatment involves the use of probiotics in oral and topical form. Topical probiotics are currently considered a safe treatment modality without any side effects, especially if compared to conventional treatment options for skin disorders.

Studies have showed that probiotics improve skin health by blocking inflammatory pathway, which includes (1) Probiotic bacteria occupy a similar ecological niche to that of pathogen to avoid their colonization. (2) Probiotics improve immune tolerance, reduce inflammation, and also release important biochemicals such as bacteriocins, modulins, antimicrobial peptides and propionic acid that inhibit growth of harmful microbes. (3) Healthy skin and healthy commensal microbiota rebuilds, leading to restoration of skin barrier function.

Many clinical studies have demonstrated that topical use of probiotics can be beneficial for some skin disorders, such as Streptococcus thermophilus, Streptococcus salivarus and Enterococcus faecium for acne; Streptococcus thermophilus and Lactobacillus jensenii for Atopic Dermatitis; Lactobacillus paracasei for dandruff; Lactobacillus sakei, Bifidobacterium infantis and Lactobacillus pentosus for psoriasis; Bifidobacteria breve BR03 and Lactobacillus salivarus for Rosasea; Lactobacillus plantarum, Lactobacillus fermentum and Kefir for wound healing; Nitrosomonas eutropha and Lactobacillus buchneri for skin aging.

Due to there are several potential applications for probiotics in management of skin related disorders, but almost all of the probiotic-containing topical formulations have yet not gone beyond the personal care product category and are not pharmaceuticals. Therefore, regulations of topical probiotics formulations still need to focus on safety. While topical probiotics are a very innovative development and there is still a lack of scientifically validated clinical data on the efficacy and safety of topical probiotics and no specific guidelines for commercializing probiotics, makes the topical use of probiotics become a challenge in the treatment of skin disorders.

Reference:
  1. Mohammed Habeebuddin, Ranjith Kumar Karnati, Predeepkumar Narayanappa Shiroorkar, Sreeharsha Nagaraja, Syed Mohammed Basheeruddin Asdaq, Md. Khalid Anwe and Santosh Fattepur. Topical Probiotics: More Than a Skin Deep. Pharmaceutics 2022, 14, 557. https://doi.org/10.3390/pharmaceutics14030557
  2. Katlein Franc. Topical Probiotics in Dermatological Therapy and Skincare: A ConciseReview. DermatolTher (Heidelb) https://doi.org/10.1007/s13555-020-00476-7. Pulished Online:19 December 2020