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Intracranial Subarachnoidal Route of Infection for Investigating Roles of Streptococcus suis Biofilms in Meningitis in a Mouse Infection Model
Published on: July 1, 2018
Interactions of Streptococcus suis serotype 2 with human meningeal cells and astrocytes
Jean-Philippe Auger1, Myron Christodoulides2, Mariela Segura3
1Faculty 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.
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.
Insights
Streptococcus suis serotype 2 adheres to and invades human meningeal cells and astrocytes. Virulence factors influence invasion, but the pathogen causes minimal inflammation, suggesting it may not directly drive meningitis symptoms.
Area of Science:
- Microbiology
- Neuroscience
- Pathogen-Host Interactions
Background:
- Streptococcus suis serotype 2 is a significant swine pathogen and emerging zoonotic agent causing meningitis.
- Human meningeal cells and astrocytes are key components of the central nervous system's protective layers.
- The interaction of S. suis serotype 2 with these human cells and the role of its virulence factors were previously unknown.
Purpose of the Study:
- To investigate the interaction of Streptococcus suis serotype 2 with human meningeal cells and astrocytes.
- To determine the role of S. suis serotype 2 virulence factors (capsular polysaccharide, suilysin, cell wall) in these interactions.
- To understand the cellular basis of S. suis serotype 2 meningitis in humans.
Main Methods:
- In vitro assays evaluating adhesion and invasion of human meningeal cells and astrocytes by S. suis serotype 2.
- Analysis of different S. suis serotype 2 sequence types.
- Assessment of the impact of specific virulence factors on cellular interactions.
- Evaluation of inflammatory responses induced by S. suis serotype 2 in these cell types.
Main Results:
- Streptococcus suis serotype 2 demonstrated adhesion to both human meningeal cells and astrocytes.
- Invasion was infrequent in meningeal cells but more common in astrocytes, with no sequence type-specific differences.
- Capsular polysaccharide modulated adhesion and invasion; suilysin and cell wall modifications affected only astrocyte invasion.
- S. suis serotype 2 induced minimal to no inflammatory response from either cell type, independent of cell death.
Conclusions:
- Streptococcus suis serotype 2 interacts with human meningeal cells and astrocytes, but these interactions are strain-specific.
- The pathogen's adhesion and invasion capabilities are inherent characteristics of the bacterial strain.
- Neither meningeal cells nor astrocytes appear to be directly involved in the inflammatory response characteristic of human meningitis caused by S. suis serotype 2.
