title: Immune-responsiveness of CD4+T cells during Streptococcus suis serotype 2 infection.
abstract: The pathogenesis of Streptococcus suis infection, a major swine and human pathogen, is only partially understood and knowledge on the host adaptive immune response is critically scarce. Yet, S. suis virulence factors, particularly its capsular polysaccharide (CPS), enable this bacterium to modulate dendritic cell (DC) functions and potentially impair the immune response. This study aimed to evaluate modulation of T cell activation during S. suis infection and the role of DCs in this response. S. suis-stimulated total mouse splenocytes readily produced TNF-α, IL-6, IFN-γ, CCL3, CXCL9, and IL-10. Ex vivo and in vivo analyses revealed the involvement of CD4+T cells and a Th1 response. Nevertheless, during S. suis infection, levels of the Th1-derived cytokines TNF-α and IFN-γ were very low. A transient splenic depletion of CD4+T cells and a poor memory response were also observed. Moreover, CD4+T cells secreted IL-10 and failed to up-regulate optimal levels of CD40L and CD69 in coculture with DCs. The CPS hampered release of several T cell-derived cytokines in vitro. Finally, a correlation was established between severe clinical signs of S. suis disease and impaired antibody responses. Altogether, these results suggest S. suis interferes with the adaptive immune response.
authors.affiliation: Laboratory of Immunology, Faculty of veterinary medicine, University of Montreal, St-Hyacinthe, Quebec, Canada.|Laboratory of Streptococcus suis, Faculty of veterinary medicine, University of Montreal, St-Hyacinthe, Quebec, Canada.
authors.forename: Marie-Pier
authors.initials: MP
authors.lastname: Lecours
authors.affiliation: Laboratory of Immunology, Faculty of veterinary medicine, University of Montreal, St-Hyacinthe, Quebec, Canada.
authors.forename: Corinne
authors.initials: C
authors.lastname: Letendre
authors.affiliation: Laboratory of Immunology, Faculty of veterinary medicine, University of Montreal, St-Hyacinthe, Quebec, Canada.
authors.forename: Damian
authors.initials: D
authors.lastname: Clarke
authors.affiliation: Laboratory of Immunology, Faculty of veterinary medicine, University of Montreal, St-Hyacinthe, Quebec, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Lemire
authors.affiliation: Laboratory of Molecular Immunology, Department of Microbiology, Infectiology and Immunology, University of Montreal, Montreal, Quebec, Canada.
authors.forename: Tristan
authors.initials: T
authors.lastname: Galbas
authors.affiliation: Pathology Division, University of Montreal, 3200 rue Sicotte, St-Hyacinthe, J2S 2M2 Canada.
authors.forename: Marie-Odile
authors.initials: MO
authors.lastname: Benoit-Biancamano
authors.affiliation: Laboratory of Molecular Immunology, Department of Microbiology, Infectiology and Immunology, University of Montreal, Montreal, Quebec, Canada.
authors.forename: Jacques
authors.initials: J
authors.lastname: Thibodeau
authors.affiliation: Laboratory of Streptococcus suis, Faculty of veterinary medicine, University of Montreal, St-Hyacinthe, Quebec, Canada.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Gottschalk
authors.affiliation: Laboratory of Immunology, Faculty of veterinary medicine, University of Montreal, St-Hyacinthe, Quebec, Canada.
authors.forename: Mariela
authors.initials: M
authors.lastname: Segura
mesh_terms: D000818:Animals; D016667:Bacterial Capsules / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology*; D004195:Disease Models, Animal; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D051379:Mice; D013290:Streptococcal Infections / Q000276:immunology / Q000382:microbiology*; D017011:Streptococcus suis / Q000276:immunology*; D013552:Swine; D018417:Th1 Cells / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D037521:Virulence Factors
chemical_list: C000611649:IFNG protein, mouse; D014409:Tumor Necrosis Factor-alpha; D037521:Virulence Factors; C028096:capsular polysaccharide, Streptococcus suis type 2; D007371:Interferon-gamma