The thermolysin-like metalloproteinase and virulence factor LasB from pathogenic Pseudomonas aeruginosa induces anoikis of human vascular cells
Article first published online: 25 MAY 2011
© 2011 Blackwell Publishing Ltd
Volume 13, Issue 8, pages 1149–1167, August 2011
How to Cite
Beaufort, N., Corvazier, E., Hervieu, A., Choqueux, C., Dussiot, M., Louedec, L., Cady, A., de Bentzmann, S., Michel, J.-B. and Pidard, D. (2011), The thermolysin-like metalloproteinase and virulence factor LasB from pathogenic Pseudomonas aeruginosa induces anoikis of human vascular cells. Cellular Microbiology, 13: 1149–1167. doi: 10.1111/j.1462-5822.2011.01606.x
- Issue published online: 18 JUL 2011
- Article first published online: 25 MAY 2011
- Accepted manuscript online: 18 APR 2011 06:53AM EST
- Received 30 November, 2010; revised 7 April, 2011; accepted 8 April, 2011.
Disruption of cell/ECM interactions resulting from uncontrolled pericellular proteolysis leads to detachment-induced cell apoptosis (anoikis), contributing to the morbid evolution of inflammatory vascular diseases. During cardiovascular infections, bacterial proteinases might induce vascular cells to enter a similar pathway. We focused on LasB, the predominant metalloproteinase secreted by the haematotropic pathogen Pseudomonas aeruginosa. While the exosecretome of the LasB-deficient pseudomonal strain PAO1lasBΔ had limited impact on human vascular cell adherence and viability, secretomes from the LasB-expressing reference strain, PAO1, or clinical isolates from patients with cardiac infection all induced anoikis, as did purified LasB. Immunofluorescence and/or immunoblotting analysis of heart valve myofibroblast cultures or whole tissue revealed an extensive, LasB-dependent degradation of ECM-associated fibronectin and vitronectin, that preceded cell de-adherence, whereas type I collagen showed limited degradation. Moreover, LasB produced a rapid endoproteolysis of the cell-associated urokinase receptor/uPAR, leaving a truncated receptor that is unable to support cell adherence and survival via interactions with vitronectin and integrins. Conversely, major myofibroblast integrins showed no or only minor alterations. Thus, among P. aeruginosa-secreted metalloproteinases, LasB can induce vascular cell anoikis through simultaneous proteolysis of ECM components and cell receptors, suggesting the uPAR-vitronectin axis as a major target in this process.