Methicillin-resistant Staphylococcus aureus adaptation to human keratinocytes

Area of Science:

• Microbiology
• Immunology
• Dermatology

Background:

• Skin is a common site for Staphylococcus aureus infections.
• Keratinocytes play a role in skin defense against pathogens.
• Recurrent S. aureus infections, particularly in atopic dermatitis, suggest pathogen adaptation.

Purpose of the Study:

• To investigate how Staphylococcus aureus adapts within human keratinocytes.
• To understand the mechanisms by which S. aureus evades keratinocyte-mediated clearance.
• To identify bacterial factors contributing to persistence within skin cells.

Main Methods:

• Isolation of S. aureus from chronically infected patients.
• Use of human skin infection models.
• Analysis of agr mutant phenotypes.
• Assessment of autophagy markers (galectin-8, LC3) and inflammasome activation (caspase-1).
• In vitro experiments with methicillin-resistant S. aureus (MRSA) USA300 and keratinocytes.

Main Results:

• S. aureus can adapt within keratinocytes to avoid clearance.
• Toxin-deficient, agr mutants of MRSA persist by stimulating autophagy.
• Autophagy promotes degradation of inflammasome components, aiding bacterial survival.
• A significant survival advantage was observed for agr or RNAIII mutants within keratinocytes.

Conclusions:

• Staphylococcus aureus exploits autophagy to evade immune responses within keratinocytes.
• Selection of adapted S. aureus mutants contributes to recurrent skin infections.
• Understanding this interplay is crucial for managing chronic S. aureus skin infections.