Staphylococcus aureus Induces Increased Serine Protease Activity in Keratinocytes

Area of Science:

• Microbiology
• Immunology
• Dermatology

Background:

• Skin bacteria influence the immune system, but mechanisms are unclear.
• Staphylococcus aureus (S. aureus) colonization is linked to atopic dermatitis severity.

Purpose of the Study:

• To investigate how S. aureus affects human keratinocytes and skin barrier function.
• To identify mechanisms by which S. aureus influences skin homeostasis.

Main Methods:

• Exposure of human keratinocytes to S. aureus.
• Measurement of endogenous protease activity and kallikrein (KLK) mRNA expression.
• Silencing of KLK genes using small interfering RNA (siRNA).
• Assessment of desmoglein-1 and filaggrin degradation.

Main Results:

• S. aureus increased keratinocyte protease activity, notably trypsin.
• KLK6, KLK13, and KLK14 mRNA expression significantly increased after S. aureus exposure.
• KLK silencing partially prevented S. aureus-induced degradation of desmoglein-1 and filaggrin.
• S. aureus exposure enhanced degradation of key skin barrier proteins.

Conclusions:

• S. aureus directly stimulates keratinocytes to increase protease activity.
• Induced KLKs contribute to S. aureus-mediated skin barrier disruption.
• This pathway represents a novel mechanism linking S. aureus to skin disease pathogenesis.