Resumo

Pathogenic yeast, such as Cryptococcus neoformans and Candida albicans, are able to reside and escape from macrophages. This ability to persist in host immune cells is an important factor for pathogenesis. Macrophages are phagocytes cells that have a central role in the innate immune response of mammalian hosts and generally expose the intracellular pathogen to a toxic environment, which is characterized by acid pH, presence of reactive oxygen and nitrogen species, as well the presence of lytic enzymes and antimicrobial peptides. In addition, the activity of specific transporters can reduce the concentration of free iron and possibly others metals in the phagosomal compartment, which can result in a decrease of the microbial intracellular development. In this work, we aim to evaluate a modulation of copper homeostasis during interaction between macrophages and C. neoformans or C. albicans cells. As a first step, we performed the phagocytosis assay during 2 h with 1 µM of CuSO₄ or 1 µM of CuSO₄ and 2 µM of the copper chelator bathocuproinedisulfonic acid (BCS). The results showed that, in presence of copper, the number of fungal cells recuperated was increased in comparison with control conditions. However, no alteration in the phagocytosis index could be observed, suggesting that the addition of copper modulate de anti-fungal activity of macrophages. We also evaluated whether the pre-loading of fungal cells with copper would change its sensitivity to macrophages. No alterations in phagocytosis index could be detected, but fungal cells overloaded with copper showed differential sensitivity to macrophages. To evaluate whether macrophages modulate the copper availability to fungal cells, we analyzed the expression of two copper transporters by qRT-PCR. The expression of CTR1 and ATP7A were down-regulated after 6 h of interaction between macrophages and C. albicans and the expression of ATP7A were dramatically down-regulated after 24 h in macrophages infected with C. neoformans. These results suggest that macrophages restrict copper to hamper fungal growth. Further characterization of copper homeostasis in macrophages will be conducted to confirm this assumption.