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Matrix fibronectin disruption in association with altered endothelial cell adhesion induced by activated
Abstract:
Sequestration of activated polymorphonuclear leukocytes (PMN) within the lung microcirculation may contribute to pulmonary vascular injury following trauma, sepsis, or disseminated intravascular coagulation. In this study cultured rat endothelial cells were utilized to evaluate the effect of PMN activation on endothelial cell attachment. The concept that disruption of the extracellular fibronectin matrix is associated with altered endothelial cell adhesion was also tested. Rat endothelial cells were grown in culture and identified by morphological techniques as well as immunofluorescent staining of Factor VIII R:Ag. Endothelial cells were labeled with 51Cr in order to establish a cell injury assay based on release of free 51Cr or cell-associated 51Cr. PMN activation was verified microscopically and by chemiluminescence activity following phorbol myristate acetate (PMA) or opsonized zymosan exposure. Following incubation with PMA, the leukocytes aggregated, chemiluminesced vigorously, and caused endothelial cell injury and detachment as determined by release of 51Cr-labeled endothelial cells. PMNs exposed to serum-treated zymosan exhibited a more modest chemiluminescence burst which was consistent with their decreased activity to injure the endothelial monolayer. With PMA activation the degree of endothelial detachment from the monolayer increased as a function of time with a plateau observed by 3 hr. Microscopic immunofluorescent analysis of extracellular fibronectin in endothelial cell cultures revealed disruption of the fibrillar matrix fibronectin after incubation with PMA-activated neutrophils in association with endothelial cell disadhesion. Thus, exposure of activated rat PMN to rat endothelial cells in culture induces endothelial damage and an associated disruption of the fibronectin matrix which may contribute to endothelial cell detachment.
Insights
Activated neutrophils (PMN) cause lung vascular injury by damaging endothelial cells and disrupting the fibronectin matrix. This study shows how PMN activation leads to endothelial cell detachment, a key factor in vascular damage.
Area of Science:
- Cellular Biology
- Immunology
- Vascular Biology
Background:
- Activated polymorphonuclear leukocytes (PMN) sequester in lung microcirculation, potentially causing pulmonary vascular injury.
- Endothelial cell attachment is crucial for maintaining vascular integrity.
Purpose of the Study:
- To investigate the effect of activated PMN on endothelial cell attachment in vitro.
- To determine if fibronectin matrix disruption is linked to altered endothelial cell adhesion.
Main Methods:
- Cultured rat endothelial cells were used, identified by morphology and Factor VIII R:Ag staining.
- Endothelial cells were labeled with 51Cr for a cell injury assay.
- PMN activation was induced by phorbol myristate acetate (PMA) or opsonized zymosan and verified by microscopy and chemiluminescence.
Main Results:
- PMA-activated PMN caused significant endothelial cell injury and detachment, evidenced by 51Cr release.
- PMN activation with serum-treated zymosan resulted in less endothelial injury.
- Activated PMN exposure led to disruption of the extracellular fibronectin matrix, correlating with endothelial cell detachment.
Conclusions:
- Activated rat PMN induce damage to cultured rat endothelial cells.
- Disruption of the fibronectin matrix by activated PMN is associated with endothelial cell detachment.
- These findings suggest a mechanism for PMN-induced pulmonary vascular injury.