Indução de apoptose em macrófagos de camundongos BALB/c pela infecção in vitro com leishmania (Leishmania) amazonensis

Abstract

Apoptosis has been associated with a fundamental role on the control or progression of several diseases, including parasitic. Thus, the aim of this work was to investigate the type of cell death of BALB/c mice macrophages infected in vitro with L. amazonensis. Our results demonstrate that infected macrophages present a DNA fragmentation in a ladder pattern, visualized in agarose gels, typical of programmed celldeath. This result was corroborated by the TUNEL method, which also demonstrates DNA fragmentation, and that this fragmentation seems to initiate as soon as 3 hours postinfection. Another landmark of apoptosis, the exposure of phosphatidylserine, was also demonstrated in BALB/c macrophages infected with L. amazonensis. This exposure showed to be dependent of time of infection and the number of parasites used. By thismethod we demonstrate a great percentage of cells entering apoptosis after infection. Furthermore, our data show the necessity of parasite integrity for inducing the programmed cell death, once the incubation of BALB/c macrophages with membrane or cytosol extracts did not lead to the typical DNA fragmentation in the ladder pattern. This typical DNAfragmentation was also observed in C57BL/6 mice macrophages infected with L. amazonensis, although not in BALB/c macrophages infected with L. major, nor L. guyanensis, suggesting that apoptosis induction is associated with the infecting Leishmania species. Apoptosis, induced by L. amazonensis, may be related with the species evasionmechanisms, as well as be involved in host susceptibility.