Dados do Trabalho

Título

Comparative Analysis of Initial Events Occurring During Macrophage Interaction with Leishmania braziliensis Isolates Causing Distinct Clinical Forms

Introdução

Cutaneous Leishmaniasis (CL) is caused by Leishmania braziliensis (Lb) and can manifest as localized cutaneous (LCL), mucosal (ML), or disseminated leishmaniasis (DL). The interaction between Leishmania parasites and macrophages, the primary host cells, plays a crucial role in determining the establishment and outcome of the disease. Although the involvement of phospholipase C (PLC) and Akt in phagocytosis has been extensively studied, their specific role in Lb phagocytosis remains unexplored.

Objetivo (s)

Characterize the initial events of Lb entry into macrophages using isolates obtained from patients with LCL or DL.

Material e Métodos

Genetically characterized Lb isolates from LCL or DL patients were utilized. Infection kinetics were determined by infecting THP-1 cells with Lb-LCL-18483 or Lb-DL-18221 isolates. The percentage of infected cells and the number of parasites per macrophage were analyzed at 30 min, 6 h, 12 h, or 24 h after infection using optical microscopy. Parasite intracellular viability was assessed at 12 h post-infection in THP-1 cells to examine potential differences in infectivity between Lb-LCL-19432 and Lb-DL-18211. The impact of PLCγ and Akt on infection outcomes was evaluated by treating THP-1 cells infected with Lb-LCL-19432 or Lb-DL18211 with specific inhibitors (U73122 and GSK 690693, respectively). Parasite viability was measured at 4 and 12 hours post-infection. To assess free radical production, THP-1 cells were labeled with the superoxide probe H2DCFDA, incubated with Lb-LCL-19432 or Lb-DL-18211, and analyzed under fluorescence microscopy.

Resultados e Conclusão

Lb-LCL-18483 and Lb-DL-18221 isolates exhibited similar infectivity in THP-1 cells. However, Lb-DL-18211 isolate showed lower viability compared to Lb-LCL-19432 after 4 and 12 hours of infection. Inhibition of PLCγ significantly reduced parasite viability in cells infected with Lb-DL-18211, while Akt inhibition did not affect the viability of any isolate tested. In addition, Lb-LCL-19432 promastigotes induced greater production of reactive oxygen species (ROS) compared to Lb-DL-18211. PLCγ appears to play a role in Lb phagocytosis for DL tested isolates. Further experiments are ongoing to compare the influence of initial events in the outcome of infection caused by LCL and DL isolates in THP-1 cells.

Palavras-chave

Leishmaniasis; Leishmania braziliensis; phagocytosis.

Agradecimentos

Postgraduate program in Biotechnology in Health and Investigative Medicine (PgBSMI); Postgraduate program in Pathology (PgPAT); INOVA Program – Fiocruz; FAPESB; CNPq.