is the leading reason behind bacterial meningitis. et al., 2010b; Mook-Kanamori et al., 2011; Barichello et al., 2015). Neuronal damage is due to the joint actions of the immediate toxicity of bacterial parts and the solid inflammatory sponsor response (Nau and Brck, 2002; Koedel et al., 2010a,b; Barichello et al., 2012). Mouse models of meningitis are used both to dissect the molecular pathogenesis of the pneumococcal infection of the brain, and to investigate novel therapeutic approaches (Chiavolini et al., 2004, 2008; Hirst et al., 2004, 2008; Banerjee et al., 2010; Woehrl et al., 2011; Mook-Kanamori et al., 2012; Tan et al., 2015). Experimental studies, aimed to develop new adjunctive therapies to be combined with antimicrobial treatment, have recently identified inhibition of cytokines as a promising target. During pneumococcal meningitis, bacterial components stimulate the release of inflammatory cytokines such as TNF-, IL-1, and IFN- (Wellmer et al., 2001; Zwijnenburg et al., 2003). Although the role of IFN- was extensively studied in viral infections, its role in acute bacterial infection is not completely comprehended and needs to be further investigated. IFN- is mainly secreted by natural killer (NK) but also by natural killer T (NKT) cells and monocytes as part of the innate immune response, and by CD4 and CD8 T lymphocytes as effector mechanism once antigen-specific immunity develops (Schoenborn and Wilson, 2007; Mildner et al., 2008). IFN- is an important mediator of multiple immune pathways during inflammation (Schroder et al., 2004) and SB 203580 pontent inhibitor was found in the cerebrospinal fluid (CSF) of patients with pneumococcal meningitis, in concentrations significantly SB 203580 pontent inhibitor higher than in patients with meningococcal or haemophilus meningitis (Glim?ker et al., 1994; Kornelisse et al., 1997; Coutinho et al., 2013; Grandgirard et al., 2013). The first evidence for a key role of IFN- in the pathogenesis of pneumococcal meningitis was obtained using a type 3 strain of in a mouse model of meningitis (Mitchell Rabbit Polyclonal to PPP4R1L et al., 2012). To determine whether the observed role of IFN- is usually specific for type 3 strains or it is a general trait of pneumococcal meningitis, we used type 4 strain TIGR4, which is considered a prototype of all strains (Tettelin et al., 2001). In fact, type 3 differs significantly from other pneumococci in important biological traits including major virulence factors such as the polysaccharide capsule and the surface protein PspC (S?rensen et al., 1990; Janulczyk et al., 2000; Iannelli et al., SB 203580 pontent inhibitor 2002; Bentley et al., 2006). In this work, type 4 strain TIGR4 was used to induce meningitis in the murine model, to investigate IFN- gene expression, leukocyte recruitment in the brain, IFN- producing cells, and antibody-mediated neutralization of IFN- activity. Materials and methods Mice Seven-weeks old female C57BL/6J, purchased from Charles River (Lecco, Italy), were maintained under specific pathogen-free conditions in the animal facilities at the University of Siena, and treated according to national guidelines (Decreto Legislativo 26/2014). All animal studies were approved by the Ethics Committee Comitato Etico Locale dell’Azienda Ospedaliera Universitaria Senese and the Italian Ministry of Health (authorization of the 20th September, 2011). Bacterial strains, media, and growth conditions TIGR4 (type 4) was grown in Tryptic Soy Broth (TSB, Becton Dickinson, Italy) and stored at ?80C with 10% glycerol. Solid media were prepared by addition of 1 1.5% agar and 3% defibrinated horse blood (Liofilchem, Italy) to TSB. Counts of colony forming units (CFU) had been performed on blood-agar plates at.