Mucosal and systemic T cell response in mice intragastrically infected with Neospora caninum tachyzoites

Abstract

The murine model has been widely used to study the host immune response to Neospora caninum. However, in most studies, the intraperitoneal route was preferentially used to establish infection. Here, C57BL/6 mice were infected with N. caninum tachyzoites by the intragastric route, as it more closely resembles the natural route of infection through the gastrointestinal tract. The elicited T-cell mediated immune response was evaluated in the intestinal epithelium and mesenteric lymph nodes (MLN). Early upon the parasitic challenge, IL-12 production by conventional and plasmacytoid dendritic cells was increased in MLN. Accordingly, increased proportions and numbers of TCRαβ+CD8+IFN-γ+ lymphocytes were detected, not only in the intestinal epithelium and MLN, but also in the spleen of the infected mice. In this organ, IFN-γ-producing TCRαβ+CD4+ T cells were also found to increase in the infected mice, however later than CD8+ T cells. Interestingly, splenic and MLN CD4+CD25+ T cells sorted from infected mice presented a suppressive activity on in vitro T cell proliferation and cytokine production above that of control counterparts. These results altogether indicate that, by producing IFN-γ, TCRαβ+CD8+ cells contribute for local and systemic host protection in the earliest days upon infection established through the gastrointestinal tract. Nevertheless, they also provide substantial evidence for a parasite-driven reinforcement of T regulatory cell function which may contribute for parasite persistence in the host and might represent an additional barrier to overcome towards effective vaccination.

Poly- N -Acetylglucosamine Production by Staphylococcus epidermidis Cells Increases Their In Vivo Proinflammatory Effect

“…The generation of Tregs with enhanced suppressive activity was also reported in studies related to other pathogens (22,46) and may thus be a general phenomenon associated with infectious conditions. Nevertheless, a previous study showed that extracellular products of S. epidermidis promoted the suppressive activity of human Tregs (47), further indicating that this cell population may be involved in counterinflammatory mechanisms operating during infections with this bacterium.…”

“…The following anti-mouse monoclonal antibodies (MAbs), along with the respective isotype controls, were used: F4/80 antigen (BM8), Foxp3 (FJK-16S) (both from eBioscience, San Diego, CA), CD4 (RM4-5), Ly-6G (1A8), Ly-6C (AL-21), CD25 (PC61), gamma interferon (IFN-␥) (XMG1.2), IL-4 (BVD4-11B11), IL-17A (TC11-18H10), and IL-10 (JES5-2A5) (all from BD Pharmingen, San Diego, CA, USA). For intracellular cytokine detection, cells were stimulated with phorbol myristate acetate and ionomycin in the presence of brefeldin A as previously described (22). Detection of surface cell markers and intracellular Foxp3 was performed also as previously described (22).…”

“…For intracellular cytokine detection, cells were stimulated with phorbol myristate acetate and ionomycin in the presence of brefeldin A as previously described (22). Detection of surface cell markers and intracellular Foxp3 was performed also as previously described (22). The collected data files were analyzed with FlowJo software version vX.0.7 (Tree Star Inc., Ashland, OR, USA).…”

“…In vitro suppression assays were performed according to a modification of previously described methods (22). Briefly, antigen-presenting cells (APC) were prepared from splenic cell suspensions of naive mice.…”

Protective effect of intranasal immunization with Neospora caninum membrane antigens against murine neosporosis established through the gastrointestinal tract

“…Only a limited number of reports specifically studied the mucosal immune response to this parasite and to the best of our knowledge no study had previously addressed the immune response in the intestinal mucosa and associated lymphoid tissue of mice immunized with N. caninum antigens. The widespread usage of intraperitoneal inoculation in experimental studies on neosporosis probably contributed to the overlooking of the mucosal layer of immune defence against this parasitosis.…”