Abstract
BackgroundMatrix metalloproteinases (MMPs) 2 and 9 are two gelatinase members which have been found elevated in exudative pleural effusions. In endothelial cells these MMPs increase paracellular permeability via the disruption of tight junction (TJ) proteins occludin and claudin. In the present study it was investigated if MMP2 and MMP9 alter permeability properties of the pleura tissue by degradation of TJ proteins in pleural mesothelium.ResultsIn the present study the transmesothelial resistance (RTM) of sheep pleura tissue was recorded in Ussing chambers after the addition of MMP2 or MMP9. Both enzymes reduced RTM of the pleura, implying an increase in pleural permeability. The localization and expression of TJ proteins, occludin and claudin-1, were assessed after incubation with MMPs by indirect immunofluorescence and western blot analysis. Our results revealed that incubation with MMPs did not alter neither proteins localization at cell periphery nor their expression.ConclusionsMMP2 and MMP9 increase the permeability of sheep pleura and this finding suggests a role for MMPs in pleural fluid formation. Tight junction proteins remain intact after incubation with MMPs, contrary to previous studies which have shown TJ degradation by MMPs. Probably MMP2 and MMP9 augment pleural permeability via other mechanisms.
Highlights
Matrix metalloproteinases (MMPs) 2 and 9 are two gelatinase members which have been found elevated in exudative pleural effusions
This study was designed in order to investigate if MMP2 and MMP9 increase the permeability of sheep pleura and contribute to the pathogenesis of pleural effusion formation
We treated parietal and visceral sheep pleura specimens with increasing doses of MMP2 and MMP9 (0.1, 1, 10 and 20 ng/ml) and the Transmesothelial resistance (RTM) was measured over a 40min period
Summary
Matrix metalloproteinases (MMPs) 2 and 9 are two gelatinase members which have been found elevated in exudative pleural effusions. In endothelial cells these MMPs increase paracellular permeability via the disruption of tight junction (TJ) proteins occludin and claudin. In the present study it was investigated if MMP2 and MMP9 alter permeability properties of the pleura tissue by degradation of TJ proteins in pleural mesothelium. Matrix metalloproteinases (MMPs) 2 and 9 are two gelatinase members which have been measured and found to be elevated in pleural exudates of different origin (parapneumonic, malignant, tuberculous). In in vitro studies of endothelial cells, MMPs increase paracellular permeability by disrupting tight junction barrier [5,7,8]. The two major constituent proteins of TJs are occludin and claudin and the disruption of these proteins in several culture systems has been correlated with increased water and solute flux [9]
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