Interactions of Streptococcus suis serotype 2 with human meningeal cells and astrocytes.
BACKGROUND
Streptococcus suis serotype 2 is an important porcine pathogen and emerging zoonotic agent responsible for meningitis, of which different sequence types predominate worldwide. Though bacterial meningitis is defined as an exacerbated inflammation of the meninges, the underlying astrocytes of the glia limitans superficialis may also be implicated. However, the interactions between this pathogen and human meningeal cells or astrocytes remain unknown. Furthermore, the roles of well-described virulence factors (capsular polysaccharide, suilysin and cell wall modifications) in these interactions have yet to be studied. Consequently, the interactions between S. suis serotype 2 and human meningeal cells or astrocytes were evaluated for the first time in order to better understand their involvement during meningitis in humans.


RESULTS
Streptococcus suis serotype 2 adhered to human meningeal cells and astrocytes; invasion of meningeal cells was rare however, whereas invasion of astrocytes was generally more frequent. Regardless of the interaction or cell type, differences were not observed between sequence types. Though the capsular polysaccharide modulated the adhesion to and invasion of meningeal cells and astrocytes, the suilysin and cell wall modifications only influenced astrocyte invasion. Surprising, S. suis serotype 2 induced little or no inflammatory response from both cell types, but this absence of inflammatory response was probably not due to S. suis-induced cell death.


CONCLUSIONS
Though S. suis serotype 2 interacted with human meningeal cells and astrocytes, there was no correlation between sequence type and interaction. Consequently, the adhesion to and invasion of human meningeal cells and astrocytes are strain-specific characteristics. As such, the meningeal cells of the leptomeninges and the astrocytes of the glia limitans superficialis may not be directly implicated in the inflammatory response observed during meningitis in humans.
Faculty of Veterinary Medicine, Research Group on Infectious Diseases of Swine (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), University of Montreal, 3200 Sicotte Street, Saint-Hyacinthe, QC, J2S 2M2, Canada. jean-philippe.auger.1@umontreal.ca.
Jean-Philippe
JP
Auger
Neisseria Research Group, Molecular Microbiology, Clinical and Experimental Sciences, University of Southampton Faculty of Medicine, Southampton, UK. mc4@soton.ac.uk.
Myron
M
Christodoulides
Faculty of Veterinary Medicine, Research Group on Infectious Diseases of Swine (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), University of Montreal, 3200 Sicotte Street, Saint-Hyacinthe, QC, J2S 2M2, Canada. mariela.segura@umontreal.ca.
Mariela
M
Segura
Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China. xujianguo@icdc.cn.
Jianguo
J
Xu
Faculty of Veterinary Medicine, Research Group on Infectious Diseases of Swine (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), University of Montreal, 3200 Sicotte Street, Saint-Hyacinthe, QC, J2S 2M2, Canada. marcelo.gottschalk@umontreal.ca.
Marcelo
M
Gottschalk
D001253:Astrocytes / Q000382:microbiology*; D001422:Bacterial Adhesion; D002478:Cells, Cultured; D006801:Humans; D008578:Meninges / Q000166:cytology / Q000382:microbiology*; D017011:Streptococcus suis / Q000502:physiology*