Streptococcus pneumoniae Sheds Syndecan-1 Ectodomains through ZmpC, a Metalloproteinase Virulence Factor

Abstract

Several microbial pathogens stimulate the ectodomain shedding of host cell surface proteins to promote their pathogenesis. We reported previously that Pseudomonas aeruginosa and Staphylococcus aureus activate the ectodomain shedding of syndecan-1 and that syndecan-1 shedding promotes P. aeruginosa pathogenesis in mouse models of lung and burned skin infections. However, it remains to be determined whether activation of syndecan-1 shedding is a virulence mechanism broadly used by pathogens. Here we show that Streptococcus pneumoniae stimulates syndecan-1 shedding in cell culture-based assays. S. pneumoniae-induced syndecan-1 shedding was repressed by peptide hydroxamate inhibitors of metalloproteinases but not by inhibitors of intracellular signaling pathways previously found to be essential for syndecan-1 shedding caused by P. aeruginosa, S. aureus, or other shedding agonists. A 170-kDa protein fraction with a peptide hydroxamate-sensitive shedding activity was purified by ammonium sulfate precipitation, DEAE chromatography, and size exclusion chromatography. Mass spectrometry analyses revealed that the 170-kDa fraction is composed of ZmpB and ZmpC, two metalloproteinase virulence factors of S. pneumoniae. Both the purified 170-kDa ZmpB/ ZmpC fraction and unfractionated S. pneumoniae culture supernatant generated syndecan-1 ectodomains that are smaller than those released by endogenous shedding. Further, a mutant S. pneumoniae strain deficient in zmpC, but not zmpB, lost its capacity to stimulate syndecan-1 shedding. These data demonstrate that S. pneumoniae directly sheds syndecan-1 ectodomains through the action of ZmpC.

LL-37 Complexation with Glycosaminoglycans in Cystic Fibrosis Lungs Inhibits Antimicrobial Activity, Which Can Be Restored by Hypertonic Saline

“…Previous studies have shown that long linear negatively charged chains of sulfated and nonsulfated disaccharides designated GAGs are increased in CF (44 -46) and lung epithelial shedding of GAG proteoglycans can be stimulated by pathogenic virulence factors (47)(48)(49). In the present study, we hypothesized that LL-37 interacts with GAGs within the CF lung milieu.…”

Immunization with a ZmpB-Based Protein Vaccine Could Protect against Pneumococcal Diseases in Mice

“…The best characterized of them is IgA1 protease, which is involved in pneumococcal adherence and colonization, and it could elicit significant protection against fatal pneumococcal pneumonia in mice (2,37). ZmpC has the capacity to cleave human matrix metalloproteinase-9 (MMP-9) and to stimulate syndecan-1 shedding (12,30), while the role of ZmpD in pneumococcal infection still is unknown. Unlike ZmpC and ZmpD in some pneumococcal strains, ZmpB is ubiquitous in all strains of S. pneumoniae and contributes to the virulence of this pathogen (13).…”

Syndecan-1 shedding facilitates the resolution of neutrophilic inflammation by removing sequestered CXC chemokines

“…Syndecan-1 is shed by metalloproteinases 16,[32][33][34][35] and, to block its release, WT mice were injected intraperitoneally with GM6001, a broad-acting metalloproteinase inhibitor, or vehicle at 24 hours after LPS. GM6001 was administered in a delayed manner because pretreatment or early administration of GM6001 has been shown to be protective in mouse models of endotoxemia, in part, by inhibiting TACE (ADAM17)-mediated release of TNF␣.…”