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The skin microbiome consists of a diverse array of microorganisms, such as bacteria, fungi, viruses, and mites. These microorganisms play a vital role in maintaining skin health by protecting against pathogens and modulating immune responses. In recent years, our comprehension of the skin microbiome has significantly advanced due to the use of metagenomic sequencing. This technology allows for the reconstruction of microbial species, strains, and gene pathways within the microbiomes of various groups. As a result, numerous therapeutic targets have been identified, which has driven the development of therapeutic strategies aimed at utilizing these microorganisms to treat skin conditions and enhance skin health.
The skin microbiome is important for keeping our skin healthy and safe from harmful germs
It does this by keeping the skin's pH balanced, stopping bad bacteria, and helping skin cells work properly. The types of microbes on our skin can change based on our age, gender, ethnicity, lifestyle (), and things like what we eat and how much sun we get (). If the skin barrier is damaged, it can upset the balance of these microbes
Normally, the bacteria on our skin don't cause problems unless something changes in the environment. Most of the bacteria on our skin are Gram-positive, like Staphylococcus and Veillonella, which help with healing wounds. Some microbes, like *Cutibacterium acnes*, can turn harmful if the environment changes
Propionibacteria, which are common on the skin, can produce substances that cause inflammation but also help fight off harmful bacteria like methicillin-resistant *Staphylococcus aureus*
Recent studies have demonstrated that the skin microbiome plays a significant role in influencing the skin's response to UV radiation through various mechanisms. One way it does this is by fortifying the skin barrier, which helps to minimize DNA damage caused by UV radiation. Additionally, certain commensal bacteria produce molecules that neutralize reactive oxygen species (ROS) generated by UV exposure, thereby limiting oxidative stress, which is a major contributor to cancer. Furthermore, the microbiome has the ability to modulate local immune responses, which may help reduce chronic inflammation, a known risk factor for cancer development.
The skin, as the body's largest organ, hosts a diverse array of microorganisms. Most of these microorganisms are either harmless or beneficial. The specific types of microorganisms present on the skin vary depending on their location on the body, as well as internal and environmental factors. The skin's immune system can influence the types of microorganisms present. Conversely, these microorganisms play a crucial role in educating the immune system. They help maintain the skin's balance and enable it to cope with environmental challenges.
The microorganisms on the skin are also involved in the development and modulation of the immune system. This interaction can affect the risk of skin cancer and the efficacy of treatments. Maintaining a healthy balance of skin microorganisms is essential for overall skin health and resilience. If this balance is disrupted, it can trigger an immune response.
The skin has the most variable and least stable microbiome owing to constant exposure to various conditions, including humidity , salinity , and temperature
10^12 microbes make up the skin microbiota
Healthy skin maintains a diverse microbiome and a potent immune system to fight infections
Epithelial-cell-derived Defensins activate G-protein-coupled receptors (GPCRs) Mrgpra2a/b on neutrophils
This signaling axis was required for effective neutrophil-mediated skin immunity and microbiome homeostasis
Defensins and Mrgpra2 were critical for combating S. aureus infections and the formation of neutrophil abscesses, a hallmark of antibacterial immunity
Activation of Mrgpra2 by defensin triggered neutrophil release of IL-1 beta and CXCL2, which are vital for proper amplification and propagation of the antibacterial immune response
The microbiota is fundamental in regulating host immunity, but the initiation and regulatory processes are not yet well understood. The skin microbiota promotes the expression of specific Endogenous retroviruses (ERVs) Keratinocyte responses to ERVs rely on cGAS/STING signaling and promote commensal-specific T cells. Inhibition of ERV reverse transcription impairs immunity and tissue repair. A high-fat diet primes the skin for increased ERV expression and immune responses, leading to inflammation. It suggests the host uses its endogenous virome to communicate with the microbiota to control tissue homeostasis and inflammation
Recent advancements in molecular methods have revealed that the bacteria residing on the skin are highly diverse and subject to significant variation.
see also:
Bacteria & Skin Microbiota
Cancer Immunotherapy / Immuno-Oncology & Gut microbiota
Cutibacterium acnes (Propionibacterium acnes)
Diseases / Disorders & Skin Microbiota
Melanoma (cutaneous) & Skin microbiota
Skin Cancer
Skin microbiota & Skin Cancer