title: Phage-Derived Protein Induces Increased Platelet Activation and Is Associated with Mortality in Patients with Invasive Pneumococcal Disease.
abstract: To improve our understanding about the severity of invasive pneumococcal disease (IPD), we investigated the association between the genotype of Streptococcus pneumoniae and disease outcomes for 349 bacteremic patients. A pneumococcal genome-wide association study (GWAS) demonstrated a strong correlation between 30-day mortality and the presence of the phage-derived gene pblB, encoding a platelet-binding protein whose effects on platelet activation were previously unknown. Platelets are increasingly recognized as key players of the innate immune system, and in sepsis, excessive platelet activation contributes to microvascular obstruction, tissue hypoperfusion, and finally multiorgan failure, leading to mortality. Our in vitro studies revealed that pblB expression was induced by fluoroquinolones but not by the beta-lactam antibiotic penicillin G. Subsequently, we determined pblB induction and platelet activation by incubating whole blood with the wild type or a pblB knockout mutant in the presence or absence of antibiotics commonly administered to our patient cohort. pblB-dependent enhancement of platelet activation, as measured by increased expression of the α-granule protein P-selectin, the binding of fibrinogen to the activated αIIbβ3 receptor, and the formation of platelet-monocyte complex occurred irrespective of antibiotic exposure. In conclusion, the presence of pblB on the pneumococcal chromosome potentially leads to increased mortality in patients with an invasive S. pneumoniae infection, which may be explained by enhanced platelet activation. This study highlights the clinical utility of a bacterial GWAS, followed by functional characterization, to identify bacterial factors involved in disease severity.
  
  
  
  The exact mechanisms causing mortality in invasive pneumococcal disease (IPD) patients are not completely understood. We examined 349 patients with IPD and found in a bacterial genome-wide association study (GWAS) that the presence of the phage-derived gene pblB was associated with mortality in the first 30 days after hospitalization. Although pblB has been extensively studied in Streptococcus mitis, its consequence for the interaction between platelets and Streptococcus pneumoniae is largely unknown. Platelets are important in immunity and inflammation, and excessive platelet activation contributes to microvascular obstruction and multiorgan failure, leading to mortality. We therefore developed this study to assess whether the expression of pblB might increase the risk of death for IPD patients through its effect on enhanced platelet activation. This study also shows the value of integrating extensive bacterial genomics and clinical data in predicting and understanding pathogen virulence, which in turn will help to improve prognosis and therapy.
authors.affiliation: Department of Internal Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.|Center for Tropical and Infectious Diseases (CENTRID), Faculty of Medicine, Diponegoro University, and Dr. Kariadi Hospital, Semarang, Indonesia.
authors.forename: Rahajeng N
authors.identifier: 0000-0001-6168-4758
authors.initials: RN
authors.lastname: Tunjungputri
authors.affiliation: Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Fredrick M
authors.identifier: 0000-0003-0554-9919
authors.initials: FM
authors.lastname: Mobegi
authors.affiliation: Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.|Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands.
authors.forename: Amelieke J
authors.initials: AJ
authors.lastname: Cremers
authors.affiliation: Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Christa E
authors.initials: CE
authors.lastname: van der Gaast-de Jongh
authors.affiliation: Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Gerben
authors.initials: G
authors.lastname: Ferwerda
authors.affiliation: Department of Medical Microbiology and Infectious Diseases, Canisius-Wilhelmina Hospital, Nijmegen, The Netherlands.|Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Jacques F
authors.initials: JF
authors.lastname: Meis
authors.affiliation: Department for Health Evidence, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.|Department of Pediatrics, Radboudumc Amalia Children's Hospital, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Nel
authors.initials: N
authors.lastname: Roeleveld
authors.affiliation: Wellcome Trust Sanger Institute, Pathogen Genomics Group, Hinxton, Cambridgeshire, United Kingdom.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Bentley
authors.affiliation: Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Pastura
authors.affiliation: Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Sacha A F T
authors.initials: SA
authors.lastname: van Hijum
authors.affiliation: Department of Internal Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Andre J
authors.initials: AJ
authors.lastname: van der Ven
authors.affiliation: Department of Internal Medicine, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Quirijn
authors.initials: Q
authors.lastname: de Mast
authors.affiliation: Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.|Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Aldert
authors.initials: A
authors.lastname: Zomer
authors.affiliation: Laboratory of Pediatric Infectious Diseases, Department of Pediatrics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands marien.dejonge@radboudumc.nl.
authors.forename: Marien I
authors.initials: MI
authors.lastname: de Jonge
mesh_terms: D016470:Bacteremia / Q000401:mortality* / Q000473:pathology; D003718:Denmark; D006801:Humans; D015539:Platelet Activation; D011008:Pneumococcal Infections / Q000401:mortality* / Q000473:pathology; D013296:Streptococcus pneumoniae / Q000472:pathogenicity* / Q000821:virology*; D016019:Survival Analysis; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D014764:Viral Proteins