Phosphoglycerate Kinase-A Novel Streptococcal Factor Involved in Neutrophil Activation and Degranulation.
BACKGROUND
Neutrophils have been proposed as important contributors to the hyperinflammatory responses that are associated with severe invasive Streptococcus pyogenes infections. In particular, streptococcal surface proteins have been implicated as potent neutrophil activators. Here we explore the impact of streptococcus-secreted factors on neutrophil activation and degranulation.


METHODS
Primary human neutrophils were exposed to supernatants prepared from cultures of invasive S. pyogenes strains of varying serotypes in the stationary growth phase. Neutrophil activation was assessed by measurement of secreted resistin, an azurophilic granule marker, and by determination of the secretome profile, using mass spectrometry.


RESULTS
Marked variation in resistin release and the neutrophil secretome profile were observed following exposure to different strains. A high resistin response was triggered exclusively by SpeB-negative strains, suggesting that at least 1 stimulatory factor is susceptible to SpeB proteolytic degradation. Further analysis, including proteomics and stimulation analyses, identified phosphoglycerate kinase as a stimulatory factor for neutrophils.


CONCLUSIONS
Taken together, results of this study reveal a novel secreted streptococcal factor that, in the absence of SpeB, can trigger neutrophil activation and degranulation. This finding is of interest in light of reports of hypervirulent SpeB-negative S. pyogenes variants present during invasive infections.
Center for Infectious Medicine.
Julia
J
Uhlmann
Center for Infectious Medicine.
Nikolai
N
Siemens
Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.
Ylva
Y
Kai-Larsen
University Medicine, Institute of Medical Microbiology, Virology and Hygiene, Rostock University, Germany.
Tomas
T
Fiedler
Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.
Peter
P
Bergman
Center for Infectious Medicine.
Linda
L
Johansson
Center for Infectious Medicine.
Anna
A
Norrby-Teglund
D015550:Cell Degranulation; D002478:Cells, Cultured; D064368:Healthy Volunteers; D006801:Humans; D013058:Mass Spectrometry; D018375:Neutrophil Activation; D009504:Neutrophils / Q000187:drug effects* / Q000276:immunology*; D010735:Phosphoglycerate Kinase / Q000378:metabolism*; D052243:Resistin / Q000032:analysis; D013297:Streptococcus pyogenes / Q000201:enzymology* / Q000276:immunology*
D052243:Resistin; D010735:Phosphoglycerate Kinase
PGK; Streptococcus pyogenes; degranulation; neutrophil; phosphoglycerate kinase