eDNA-Mediated Cutaneous Protection Against UVB Damage Conferred by Staphylococcal Epidermal Colonization

Area of Science:

• Microbiology
• Dermatology
• Biochemistry

Background:

• The human skin hosts diverse microorganisms, including Staphylococcus epidermidis and Staphylococcus aureus.
• These bacteria can form biofilms, enhancing adhesion and stability on the skin surface.
• Skin is exposed to oxidative stress, like UV radiation, necessitating antioxidant defense mechanisms such as the Nrf2-Keap1 pathway.

Purpose of the Study:

• To investigate the morphology and matrix composition of S. aureus and S. epidermidis biofilms on healthy human skin.
• To determine if these skin bacteria provide protection against UV-induced oxidative stress.

Main Methods:

• Exploration of bacterial morphology and extracellular matrix (ECM) composition on ex vivo human skin.
• Assessment of the protective effects of bacterial cultures and their isolated extracellular DNA (eDNA) against UVB-induced apoptosis.

Main Results:

• S. aureus and S. epidermidis exhibit biofilm-like morphology when adhering to healthy human skin.
• The bacterial ECM comprises extracellular polysaccharides (EPS) and extracellular DNA (eDNA).
• Both bacterial cultures and isolated S. aureus biofilm eDNA demonstrated protective effects against UVB-induced apoptosis.

Conclusions:

• Skin staphylococci form biofilms on human skin with a matrix of EPS and eDNA.
• These bacteria and their biofilm eDNA offer cutaneous protection against UVB-induced apoptosis.
• Skin microbiota play a role in maintaining cutaneous redox balance by activating the skin's antioxidant defense mechanisms.