Estudo da interação de Acanthamoeba castellanii sobre o fungo Trichophyton rubrum.

Abstract

Dermatophytoses are fungal infections that affect humans and animals. Among the most prevalent etiological agents in these infections are the Trichophyton rubrum species. The amoebas of the genus Acanthamoeba present wide environmental distribution, feeding on bacteria, fungi, viruses present in the environment. Both microorganisms can live in the same environment, so the objective of this work was to evaluate the interaction of A. castellanii on T. rubrum in different conditions (PYG, NA and ND). The kinetics of A. castellanii in the presence and absence of T. rubrum were studied, as well as the phagocytosis assay to confirm the ameba-fungus interaction, to evaluate the influence of different nutritional conditions (PYG media, NEFF). The results show an amoeba encroachment of approximately 30% with presence of T. rubrum and 25% without the fungus, and the interaction was confirmed by phagocytosis, where in the NA condition (addition of NEFF prior to fungus infection) there is a greater internalization in addition, the addition or subtraction of Ca2+ and Mg2+ ions, addition of mannose and cytochalasin D in phagocytosis, fungicide activity and release of the fungus from the amoeba interior were performed. The ions proved to be important for the predation of the fungus by amoeba and cytochalasin D demonstrated the importance of actin in the conidial release process, since there was a decrease in the exocytosis of conidia. Mannose decreased phagocytosis in PYG in a concentration-dependent manner, not occurring even for NA. NA provided a greater recovery of the fungus inside the amoeba and also a lower release, concomitant to a reduced production of oxidative species, also having a greater number of hyphae in the interior. The production of oxidative species, the capacity of amoeba to inactivate the fungus and its ability to survive and be released from the amoeba, and the production of antioxidant enzymes by the fungus were also evaluated. The fungus recovered from amoeba was tested against itraconazole, ketoconazole and terbinafine in order to determine the minimum inhibitory concentration (MIC) of these antifungals. The presence of enzymes of the antioxidant complex was shown to be greater in the conditions with passages through the amoeba than the control, showing an adaptation for survival of the fungus. The MIC of itraconazole presented significant variation in PYG 1h and NA 24h and the other antifungal drugs did not show significant alterations. Thus, the amoeba internalizes the fungus, independent of the nutritional condition and this internalization decreases over time, and this predation can be increased in the presence of Ca2+ and Mg2+ ions. On the other hand, the amoeba internalizes T. rubrum by mannose-dependent mechanism in trophozites and not in cysts and A. castellanii produces ROS and PRN that influence its fungicidal activity, which is independent of mannose and the fungus produces enzymes of the antioxidant complex for survive within the amoeba.