Staphylococcus aureus directly activates eosinophils via platelet-activating factor receptor.

Area of Science:

• Immunology
• Dermatology
• Microbiology

Background:

• Atopic dermatitis (AD) is often exacerbated by Staphylococcus aureus (SA) colonization.
• Eosinophilic inflammation is a key feature of AD, but direct interactions between SA and eosinophils are poorly understood.
• The platelet-activating factor receptor (PAFR) is implicated in leukocyte phagocytosis of bacteria.

Purpose of the Study:

• To investigate if SA directly triggers eosinophil effector functions via PAFR.
• To explore the role of SA-eosinophil interactions in AD pathogenesis.

Main Methods:

• Eosinophils were cultured with heat-killed SA, measuring eosinophil-derived neurotoxin (EDN) release, superoxide generation, and adhesion.
• Cytokine release was quantified using multiplex bead immunoassays.
• Phagocytosis was visualized using FISH-labeled SA and confocal microscopy; PAFR-blocking agents were used to assess inhibitory effects.

Main Results:

• SA induced dose-dependent EDN release and superoxide generation by eosinophils.
• Interleukins (IL-5, IL-17A) enhanced SA-induced reactions; SA promoted eosinophil adhesion and cytokine secretion.
• SA was phagocytosed by eosinophils, and PAFR blockade completely inhibited SA-induced eosinophil activation.

Conclusions:

• Staphylococcus aureus directly activates eosinophils via the PAFR.
• This interaction contributes to the inflammatory processes in atopic dermatitis.
• PAFR blockade presents a potential therapeutic strategy for SA-colonized AD.