The role of immune cells associated with sporotrichosis caused by Sporothrix schenckii is not yet fully clarified. Macrophages through pattern recognition receptors (PRRs) can recognize pathogen-associated molecular patterns (PAMPs) of Sporothrix, engulf it, activate respiratory burst, and secrete pro-inflammatory or anti-inflammatory biological mediators to control infection. It is important to consider that the characteristics associated with S. schenckii and/or the host may influence macrophage polarization (M1/M2), cell recruitment, and the type of immune response (1, 2, and 17). Currently, with the use of new monocyte-macrophage cell lines, it is possible to evaluate different host–pathogen interaction processes, which allows for the proposal of new mechanisms in human sporotrichosis. Therefore, in order to contribute to the understanding of these host–pathogen interactions, the aim of this review is to summarize and discuss the immune responses induced by macrophage-S. schenckii interactions, as well as the PRRs and PAMPs involved during the recognition of S. schenckii that favor the immune evasion by the fungus.

Cell wall (CW) components of fungusSporothrix schenckiiare the major inductors antigens of immune responses. The immunodominant 60 kDa glycoprotein (gp60) has been shown to be associated with the virulence of this fungus but its role in experimental sporotrichosis is unknown. In this work, the immunological effects of CW-purified gp60 were investigated in a model of experimental subcutaneous sporotrichosis in normal and gp60-preimmunized C57BL/6 and BALB/c mice strains which were then infected withS. schenckiiconidia. Results showed that both mice strains use different cytokine profiles in order to fightS. schenckiiinfection; C57BL/6 mice seem to use a Th17 response while BALB/c mice tend to depend on a Th1 profile. Preimmunization with gp60 showed a downregulatory effect on the immune response since cytokines levels were diminished in both strains. There were no significant differences in the magnitude of dorsoplantar inflammation between gp60-preimmunized and nonimmunized mice of both strains. However, skin lesions due to the infection in gp60-preimmunized mice were more severe in BALB/c than in C57BL/6 mice, suggesting that the antigen exerts a higher downregulatory effect on the Th1 response.

Invasive Candidiasis (IC) presents a global mortality rate greater than 40%, occupying the fourth place worldwide as the most frequent opportunistic nosocomial disease. Although the genus Candida consists of around 200 species, only 20 are reported as etiological agents of IC, being Candida albicans the most frequent causal agent. Even when there is a broad range of antifungals drugs for Candida infections, azoles, polyenes, and echinocandins are considered among the most effective treatment. However, there is some incidence for antifungal resistance among some Candida strains, limiting treatment options. Several molecular mechanisms with antifungal agents have been reported for C. albicans where insertions, deletions, and point mutations in genes codifying target proteins are frequently related to the antifungal drug resistance. Furthermore, gene overexpression is also frequently associated to antifungal resistance as well as an increase in the activity of proteins that reduce oxidative damage. This chapter summarizes the main molecular mechanisms to C. albicans antifungal drug resistance, besides offering an overview of new antifungal agents and new antifungal targets to combat fungal infections.