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Ultrastructural changes in platelet activating factor-induced epithelial damage in rabbit maxillary sinus mucosa
S Y Jeon1, P S Jeong, C K Rhee
1Department of Otolaryngology, GyeongSang National University, Chinju, Korea.
Abstract:
Platelet activating factor (PAF), a potent chemical mediator in inflammation and allergic reaction, has been thought to induce mucociliary inhibition and epithelial damage in the airway mucosa. However, several recent papers have reported that PAF may not readily damage the airway epithelium. The aim of this study was to elucidate the pathogenesis of PAF-induced epithelial damage in terms of ultrastructural changes. Sixteen micrograms of PAF (1 mL of 16 microg/mL) was administered into the maxillary sinuses of rabbits. The rabbits were divided into 2 groups according to time intervals, and the antral mucosa was taken 1 and 3 days after administration of PAF. The tissue was processed for routine transmission electron microscopy. No epithelial degeneration was observed other than platelet aggregation, red blood cell stasis, and swelling of the endothelial cells 1 day after administration of PAF. Migration of inflammatory cells into the perivascular connective tissue, infiltration of eosinophils into the subepithelial and intraepithelial spaces, and vacuolar degeneration of the epithelial cells with focal loss of cilia were seen 3 days after administration of PAF. In conclusion, PAF induced infiltration of eosinophils into the epithelium, and resulted in epithelial degeneration that varied according to the time interval. Our findings suggest that PAF may cause epithelial damage through a series of secondary events, probably due to cytotoxicity of eosinophils infiltrating the epithelium.
Insights
Platelet activating factor (PAF) causes airway epithelial damage indirectly, primarily through eosinophil infiltration. This study reveals PAF
Area of Science:
- Respiratory Medicine
- Inflammation Research
- Cell Biology
Background:
- Platelet activating factor (PAF) is implicated in inflammation and allergic reactions.
- Previous research suggests PAF may not directly damage airway epithelium.
- The precise mechanism of PAF-induced airway epithelial damage requires further elucidation.
Purpose of the Study:
- To investigate the ultrastructural pathogenesis of Platelet activating factor (PAF)-induced epithelial damage in the airway mucosa.
- To clarify the role of PAF in airway inflammation and epithelial integrity.
Main Methods:
- Administration of Platelet activating factor (PAF) into rabbit maxillary sinuses.
- Collection of antral mucosa samples at 1 and 3 days post-administration.
- Analysis of tissue samples using transmission electron microscopy for ultrastructural changes.
Main Results:
- One day post-PAF administration: observed platelet aggregation, red blood cell stasis, and endothelial cell swelling, but no epithelial degeneration.
- Three days post-PAF administration: noted inflammatory cell migration, eosinophil infiltration into subepithelial and intraepithelial spaces, epithelial cell vacuolar degeneration, and focal cilia loss.
- Ultrastructural analysis revealed a time-dependent progression of damage.
Conclusions:
- Platelet activating factor (PAF) induces airway epithelial damage through secondary mechanisms, not direct cytotoxicity.
- Eosinophil infiltration into the epithelium is a key event in PAF-induced epithelial degeneration.
- The findings suggest a delayed pathogenesis of PAF-induced airway mucosal injury, mediated by inflammatory cell infiltration.