Group B Streptococcus (GBS) disrupts by calpain activation the actin and microtubule cytoskeleton of macrophages
Article first published online: 18 MAR 2011
© 2011 Blackwell Publishing Ltd
Volume 13, Issue 6, pages 859–884, June 2011
How to Cite
Fettucciari, K., Quotadamo, F., Noce, R., Palumbo, C., Modesti, A., Rosati, E., Mannucci, R., Bartoli, A. and Marconi, P. (2011), Group B Streptococcus (GBS) disrupts by calpain activation the actin and microtubule cytoskeleton of macrophages. Cellular Microbiology, 13: 859–884. doi: 10.1111/j.1462-5822.2011.01584.x
- Issue published online: 16 MAY 2011
- Article first published online: 18 MAR 2011
- Accepted manuscript online: 8 FEB 2011 04:31AM EST
- Received 7 July, 2010; revised 28 January, 2011; accepted 31 January, 2011.
Group B Streptococcus (GBS) has evolved several strategies to avoid host defences where macrophages are one of main targets. Since pathogens frequently target the cytoskeleton to evade immune defences, we investigated if GBS manipulates macrophage cytoskeleton. GBS-III-COH31 in a time- and infection ratio-dependent manner induces great macrophage cytoskeleton alterations, causing degradation of several structural and regulatory cytoskeletal proteins. GBS β-haemolysin is involved in cytoskeleton alterations causing plasma membrane permeability defects which allow calcium influx and calpain activation. In fact, cytoskeleton alterations are not induced by GBS-III-COH31 in conditions that suppress β-haemolysin expression/activity and in presence of dipalmitoylphosphatidylcholine (β-haemolysin inhibitor). Calpains, particularly m-calpain, are responsible for GBS-III-COH31-induced cytoskeleton disruption. In fact, the calpain inhibitor PD150606, m-calpain small-interfering-RNA and EGTA which inhibit calpain activation prevented cytoskeleton degradation whereas µ-calpain and other protease inhibitors did not. Finally, calpain inhibition strongly increased the number of viable intracellular GBS-III-COH31, showing that cytoskeleton alterations reduced macrophage phagocytosis. Marked macrophage cytoskeleton alterations are also induced by GBS-III-NEM316 and GBS-V-10/84 through β-haemolysin-mediated plasma membrane permeability defects which allow calpain activation. This study suggests a new GBS strategy to evade macrophage antimicrobial responses based on cytoskeleton disruption by an unusual mechanism mediated by calcium influx and calpain activation.