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Neutrophil diapedesis: paracellular or transcellular?
1Vascular Biology Program at the Lawson Health Research Institute, London, ON N6A 4G5, Canada.
Summary
Neutrophil (PMN) transmigration across the endothelial barrier to inflammatory sites can occur via paracellular or transcellular routes. This study reconciles these pathways, presenting anatomic and functional evidence for both mechanisms.
Area of Science:
- Immunology
- Cell Biology
- Pathology
Background:
- Circulating neutrophils (PMN) are critical immune cells that must migrate to inflammatory sites.
- Endothelial barriers regulate the passage of immune cells from the bloodstream into tissues.
- The precise mechanism of PMN transmigration through the endothelial barrier remains debated.
Purpose of the Study:
- To investigate the pathways of neutrophil (PMN) transmigration across the endothelial barrier.
- To present evidence supporting both paracellular and transcellular routes of PMN emigration.
- To reconcile the controversy surrounding PMN endothelial transmigration.
Main Methods:
- Anatomic analysis of endothelial barriers and neutrophil interactions.
- Functional assays to assess PMN transmigration.
- Teleological arguments to explain the evolutionary advantages of different pathways.
Main Results:
- Evidence supports both paracellular (between cells) and transcellular (through cells) pathways for PMN emigration.
- Specific conditions or stimuli may favor one pathway over the other.
- Reconciliation of existing data suggests a dynamic and context-dependent transmigration process.
Conclusions:
- Neutrophil (PMN) transmigration is a complex process involving both paracellular and transcellular routes.
- Understanding these pathways is crucial for modulating inflammatory responses.
- Both anatomical and functional data support a unified view of PMN endothelial transmigration.