Characterization of protective extracellular membrane-derived vesicles produced by Streptococcus pneumoniae.
Extracellular vesicles are produced by many pathogenic microorganisms and have varied functions that include secretion and release of microbial factors, which contribute to virulence. Very little is known about vesicle production by Gram-positive bacteria, as well as their biogenesis and release mechanisms. In this work, we demonstrate the active production of vesicles by Streptococcus pneumoniae from the plasma membrane, rather than being a product from cell lysis. We biochemically characterized them by proteomics and fatty acid analysis, showing that these vesicles and the plasma membrane resemble in essential aspects, but have some differences: vesicles are more enriched in lipoproteins and short-chain fatty acids. We also demonstrate that these vesicles act as carriers of surface proteins and virulence factors. They are also highly immunoreactive against human sera and induce immune responses that protect against infection. Overall, this work provides insights into the biology of this important Gram-positive human pathogen and the role of extracellular vesicles in clinical applications.


CONCLUSIONS
Pneumococcus is one of the leading causes of bacterial pneumonia worldwide in children and the elderly, being responsible for high morbidity and mortality rates in developing countries. The augment of pneumococcal disease in developed countries has raised major public health concern, since the difficulties to treat these infections due to increasing antibiotic resistance. Vaccination is still the best way to combat pneumococcal infections. One of the mechanisms that bacterial pathogens use to combat the defense responses of invaded hosts is the production and release of extracellular vesicles derived from the outer surface. Little is known about this phenomenon in Gram-positives. We show that pneumococcus produces membrane-derived vesicles particularly enriched in lipoproteins. We also show the utility of pneumococcal vesicles as a new type of vaccine, as they induce protection in immunized mice against infection with a virulent strain. This work will contribute to understand the role of these structures in important biological processes such as host-pathogen interactions and prevention of human disease.
Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Campus de Excelencia Internacional CeiA3, Córdoba, Spain; Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
Alfonso
A
Olaya-Abril
Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA.
Rafael
R
Prados-Rosales
Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain; Unidad de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Instituto de Biomedicina de Sevilla/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.
Michael J
MJ
McConnell
Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain; Unidad de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Instituto de Biomedicina de Sevilla/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.
Reyes
R
Martín-Peña
Departamento de Biología Celular, Fisiología e Inmunología, Universidad de Córdoba, Campus de Excelencia Internacional CeiA3, Córdoba, Spain.
José Antonio
JA
González-Reyes
Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Campus de Excelencia Internacional CeiA3, Córdoba, Spain; Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
Irene
I
Jiménez-Munguía
Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Campus de Excelencia Internacional CeiA3, Córdoba, Spain; Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain.
Lidia
L
Gómez-Gascón
Departamento de Botánica, Ecología y Fisiología Vegetal, Universidad de Córdoba, Campus de Excelencia Internacional CeiA3, Córdoba, Spain.
Javier
J
Fernández
Departamento de Química Analítica, Universidad Complutense de Madrid, Madrid, Spain.
José L
JL
Luque-García
Departamento de Química Analítica, Universidad Complutense de Madrid, Madrid, Spain.
Carlos
C
García-Lidón
Departamento de Química Analítica, Universidad Complutense de Madrid, Madrid, Spain.
Héctor
H
Estévez
Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain; Unidad de Enfermedades Infecciosas, Microbiología y Medicina Preventiva, Instituto de Biomedicina de Sevilla/Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Sevilla, Spain.
Jerónimo
J
Pachón
Sección de Enfermedades Infecciosas Pediátricas e Inmunopatología, Hospital Universitario Infantil Virgen del Rocío, Sevilla, Spain.
Ignacio
I
Obando
Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA.
Arturo
A
Casadevall
Department of Medicine and Microbiology and Immunology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA.
Liise-Anne
LA
Pirofski
Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Campus de Excelencia Internacional CeiA3, Córdoba, Spain; Red Española de Investigación en Patología Infecciosa (REIPI), Instituto de Salud Carlos III, Madrid, Spain. Electronic address: mjrodriguez@uco.es.
Manuel J
MJ
Rodríguez-Ortega
D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism; D002675:Child, Preschool; D002845:Chromatography; D002853:Chromatography, Liquid; D019295:Computational Biology; D030562:Databases, Protein; D024881:Drug Resistance, Bacterial; D005227:Fatty Acids / Q000737:chemistry; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011008:Pneumococcal Infections / Q000097:blood* / Q000188:drug therapy; D040901:Proteomics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013296:Streptococcus pneumoniae / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
D000900:Anti-Bacterial Agents; D005227:Fatty Acids
Extracellular vesicles; Membrane vesicles; Pneumococcus; Proteomics; Surface proteins; Vaccine