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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
Porcine brain microvascular endothelial cell-derived interleukin-8 is first induced and then degraded by
Ghyslaine Vanier1, Mariela Segura, Marie-Pier Lecours
1Groupe de Recherche sur les Maladies Infectieuses du Porc (GREMIP), Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC J2S2M2, Canada.
Abstract:
Streptococcus suis is a major pathogen of swine, causing mainly meningitis, and it also represents an emerging zoonotic agent. We investigated its ability to induce the release of pro-inflammatory cytokines and chemokines by porcine brain microvascular endothelial cells (PBMEC). We demonstrated that live S. suis induced a strong release of interleukin (IL)-6 and IL-8 by PBMEC. We showed that the suilysin (hemolysin) was largely responsible for such stimulation, although cell wall components also contribute to cell stimulation but to a considerably lower extent. Interestingly, IL-8 production by PBMEC became undetectable by increasing either the incubation time or bacterial concentration of certain live S. suis strains. We further demonstrated that this decrease of IL-8 levels was probably linked to the production of a serine protease by S. suis. Our results suggest that S. suis can induce an exacerbated release of inflammatory mediators by swine endothelial cells that could cause a massive recruitment of leukocytes and subsequent blood-brain barrier breakdown facilitating the pathogenesis of S. suis-induced meningitis. In addition, S. suis could modulate this response by degrading IL-8 which might delay recruitment of S. suis killer-neutrophils to the site of inflammation, allowing this pathogen to survive upon its arrival to central nervous system.
Insights
Streptococcus suis infection triggers inflammatory responses in swine brain cells, primarily via suilysin. The bacteria may also degrade IL-8, potentially aiding survival in the central nervous system.
Area of Science:
- Veterinary Microbiology
- Immunology
- Neuroscience
Background:
- Streptococcus suis is a significant swine pathogen causing meningitis and an emerging zoonotic agent.
- Understanding S. suis interactions with the blood-brain barrier is crucial for disease pathogenesis.
Purpose of the Study:
- To investigate the induction of pro-inflammatory cytokines and chemokines by S. suis in porcine brain microvascular endothelial cells (PBMEC).
- To identify the bacterial factors responsible for stimulating these responses and explore potential immune evasion mechanisms.
Main Methods:
- Co-incubation of live S. suis strains with PBMEC.
- Measurement of cytokine (IL-6) and chemokine (IL-8) release using ELISA.
- Analysis of bacterial components (suilysin, cell wall) and bacterial products (serine protease) effects.
Main Results:
- Live S. suis induced significant release of IL-6 and IL-8 from PBMEC.
- Suilysin was the primary bacterial factor responsible for cytokine/chemokine stimulation.
- Certain S. suis strains reduced IL-8 levels, linked to a serine protease, potentially via IL-8 degradation.
Conclusions:
- S. suis exacerbates inflammatory mediator release in swine endothelial cells, potentially leading to blood-brain barrier breakdown and meningitis.
- Bacterial degradation of IL-8 may represent a mechanism for S. suis to evade neutrophil clearance and survive in the central nervous system.
