Abstract
Background: We have previously demonstrated that human bronchial epithelial cells engulf apoptotic eosinophils.
Objectives: To compare and contrast the phagocytic capabilities of monocyte-derived macrophage and primary airway epithelial cells for apoptotic granulocytes.
Results: Here we compared phagocytosis of human apoptotic eosinophils and neutrophils by small and large airway epithelial cells (SAEC and LAEC) and monocyte-derived macrophages. Confocal microscopy of F-actin staining and scanning and transmission electron microscopy revealed phagocytic cup formation around apoptotic eosinophils by airway epithelial cells (AEC) membranes with evidence of their digestion. Resting and cytokine-stimulated AEC did not recognize and ingest apoptotic neutrophils. The latter were phagocytosed by macrophages that exhibited greater ingestion of and higher capacity for, apoptotic eosinophils over apoptotic neutrophils. Cytochalasin D completely abolished uptake of apoptotic eosinophils by SAEC, LAEC or macrophage monolayers. Ligation of epithelial cell CD44 receptors for 24 h increased phagocytosis of apoptotic eosinophils by SAEC and LAEC with a potency comparable with that of IL-1. Phagocytosis was a specific receptor-mediated process involving integrin- (αvβ3, αvβ5, CD36), phosphatidylserine receptor- and lectin-dependent mechanisms. No significant differences were observed in avarice for apoptotic eosinophils by SAEC or LAEC either resting, CD44 monoclonal antibodies- or cytokine- stimulated, or in their usage and expression of recognition receptors.
Conclusion: These findings further suggest and define an important role for the bronchial epithelium in the selective removal of apoptotic eosinophils from the airways in asthma.
Objectives: To compare and contrast the phagocytic capabilities of monocyte-derived macrophage and primary airway epithelial cells for apoptotic granulocytes.
Results: Here we compared phagocytosis of human apoptotic eosinophils and neutrophils by small and large airway epithelial cells (SAEC and LAEC) and monocyte-derived macrophages. Confocal microscopy of F-actin staining and scanning and transmission electron microscopy revealed phagocytic cup formation around apoptotic eosinophils by airway epithelial cells (AEC) membranes with evidence of their digestion. Resting and cytokine-stimulated AEC did not recognize and ingest apoptotic neutrophils. The latter were phagocytosed by macrophages that exhibited greater ingestion of and higher capacity for, apoptotic eosinophils over apoptotic neutrophils. Cytochalasin D completely abolished uptake of apoptotic eosinophils by SAEC, LAEC or macrophage monolayers. Ligation of epithelial cell CD44 receptors for 24 h increased phagocytosis of apoptotic eosinophils by SAEC and LAEC with a potency comparable with that of IL-1. Phagocytosis was a specific receptor-mediated process involving integrin- (αvβ3, αvβ5, CD36), phosphatidylserine receptor- and lectin-dependent mechanisms. No significant differences were observed in avarice for apoptotic eosinophils by SAEC or LAEC either resting, CD44 monoclonal antibodies- or cytokine- stimulated, or in their usage and expression of recognition receptors.
Conclusion: These findings further suggest and define an important role for the bronchial epithelium in the selective removal of apoptotic eosinophils from the airways in asthma.
| Original language | English |
|---|---|
| Pages (from-to) | 1514-1524 |
| Number of pages | 11 |
| Journal | Clinical and Experimental Allergy |
| Volume | 34 |
| Issue number | 10 |
| Early online date | 10 Sep 2004 |
| DOIs | |
| Publication status | Published - Oct 2004 |