PLoS One. 2013 Sep 19;8(9):e75708. doi: 10.1371/journal.pone.0075708. eCollection 2013.
Disruption of the endothelial barrier by proteases from the bacterial pathogen Pseudomonas aeruginosa: implication of matrilysis and receptor cleavage.
Abstract
Within the vasculature, uncontrolled pericellular proteolysis can lead to disruption of cell-to-cell and cell-to-matrix
interactions and subsequent detachment-induced cell apoptosis, or
anoikis, contributing to inflammatory vascular diseases, with the
endothelium as the major target. Most studies so far have focused on
endogenous proteinases. However, during bloodstream infections,
bacterial proteinases may also trigger endothelial anoikis. We thus
investigated the potential apoptotic activity of the proteinases
secreted by the haematotropic opportunistic pathogen, Pseudomonas
aeruginosa, and particularly its predominant metalloproteinase, LasB.
For this, we used the secretome of the LasB-expressing pseudomonal
strain, PAO1, and compared it with that from the isogenic,
LasB-deficient strain (PAO1∆lasB), as well as with purified LasB.
Secretomes were tested for apoptotic activity on cultured human
endothelial cells derived from the umbilical vein or from the cerebral
microvasculature. We found that the PAO1 secretome readily induced
endothelial cell anoikis, as did secretomes of LasB-positive clinical
pseudomonal isolates, while the PAO1∆lasB secretome had only a limited
impact on endothelial adherence and viability. Notably, purified LasB
reproduced most of the effects of the LasB-containing secretomes, and
these were drastically reduced in the presence of the LasB-selective
inhibitor, phosphoramidon. A precocious and extensive LasB-dependent
degradation of several proteins associated with the endothelial extracellular matrix,
fibronectin and von Willebrand factor, was observed by
immunofluorescence and/or immunoblotting analysis of cell cultures.
Moreover, the PAO1 secretome, but not that from PAO1∆lasB, specifically
induced rapid endoproteolysis of two major interendothelial junction
components, VE-cadherin and occludin, as well as of the anti-anoikis,
integrin-associated urokinase receptor, uPAR. Taken as a prototype for
exogenous haemorrhagic proteinases, pseudomonal LasB thus appears to
induce endothelial anoikis not only via matrilysis, as observed for many
pro-apoptotic proteinases, but also via cleavage of some essential
cell-to-cell and cell-to-matrix adhesion receptors implicated in the maintenance of the endothelial barrier.
- PMID:
- 24069438
- [PubMed - indexed for MEDLINE]
- PMCID:
- PMC3777978
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