, 2003) is increased by IFN-γ, suggesting a relevant role of these activated phagocytic cells in the control of the fungal infection. Chronic tissue inflammatory reactions to microbial infections also involve the participation of IFN-γ. In situ expression of IFN-γ in the granulomas has been correlated

with preferential Th1 immune response developed in fungal (Koga et al., 2002) and bacterial infections (Bergeron et al., 1997), whereas in parasitic infections, the predominant pattern of immune response is Th2 (Czaja et al., 1989; Henri et al., 2002). Granuloma formation and fibrosis are characterized by the presence of extracellular matrix (ECM) components, cytokines, chemokines, enzymes, and different cell populations. The production of ECM components are regulated by several cytokines and growth factors, including IFN-γ, interleukin (IL)-4, transforming growth factor (TGF)-β, tumor necrosis factor selleck (TNF)-α (Wynn, 2004), and their breakdown by proteolytic enzymes, such as matrix metalloproteinases (MMPs), is also associated to modulation by IFN-γ, TNF-α, IL-1β, and TGF-β (Zhang et al., 1998;

Feinberg et al., 2000). IFN-γ controls collagen expression by direct effects on synthesis and degradation of type I collagen (Ghosh, 2002; Wynn, 2004) and by indirect effects through the modulation of production of the profibrotic cytokines IL-4 and TGF-β1 (Wynn, 2004). In our experimental model Selleck MI-503 of P. brasiliensis infection, we could detect distinct patterns of ECM components using immunohistochemical reactions (Xidieh et al., 1999; Nishikaku & Burger, 2003a, b), the presence of some cytokines (Nishikaku & Burger, 2003a; Nishikaku et al., 2008) and of proteolytic enzymes (Nishikaku et al., 2009a) at the lesions of infected mouse strains. However, the contribution of IFN-γ in the paracoccidioidal granuloma formation is not fully understood. The aim of the present work was Ribonuclease T1 to evaluate the in situ immunolocalization of IFN-γ in the lesions of susceptible

(B10.A) and resistant (A/J) mice ip. infected with P. brasiliensis, and to assess the contribution of this cytokine to the development of granulomas and to host resistance against this fungal disease. Yeast forms of P. brasiliensis isolates, Pb18 and Pb265, respectively, highly and slightly virulent to mice (Kashino et al., 1985), were cultivated on semisolid Fava Netto’s culture medium, kept at 37 °C and used at the seventh day of culture, which corresponds to the exponential phase of growth (Kashino et al., 1987). For inoculum preparation, the yeast cells were washed in sterile phosphate-buffered saline (PBS, pH 7.2) and the fungal suspensions obtained were adjusted to 10 × 106 fungi mL−1 after counting in a haemocytometer. The viability of the fungal cells, determined by Janus Green vital staining (Kashino et al., 1987), was always higher than 75%. Groups of 5–10 female, 8–10 weeks old mice of B10.