Effects of a novel β–lapachone derivative on Trypanosoma cruzi : Parasite death involving apoptosis, autophagy and necrosis

Abstract

Natural products comprise valuable sources for new antiparasitic drugs. Here we tested the effects of a novel β–lapachone derivative on Trypanosoma cruzi parasite survival and proliferation and used microscopy and cytometry techniques to approach the mechanism(s) underlying parasite death. The selectivity index determination indicate that the compound trypanocidal activity was over ten-fold more cytotoxic to epimastigotes than to macrophages or splenocytes. Scanning electron microscopy analysis revealed that the R72 β–lapachone derivative affected the T. cruzi morphology and surface topography. General plasma membrane waving and blebbing particularly on the cytostome region were observed in the R72-treated parasites. Transmission electron microscopy observations confirmed the surface damage at the cytostome opening vicinity. We also observed ultrastructural evidence of the autophagic mechanism termed macroautophagy. Some of the autophagosomes involved large portions of the parasite cytoplasm and their fusion/confluence may lead to necrotic parasite death. The remarkably enhanced frequency of autophagy triggering was confirmed by quantitating monodansylcadaverine labeling. Some cells displayed evidence of chromatin pycnosis and nuclear fragmentation were detected. This latter phenomenon was also indicated by DAPI staining of R72-treated cells. The apoptotis induction was suggested to take place in circa one-third of the parasites assessed by annexin V labeling measured by flow cytometry. TUNEL staining corroborated the apoptosis induction. Propidium iodide labeling indicate that at least 10% of the R72-treated parasites suffered necrosis within 24 h. The present data indicate that the β–lapachone derivative R72 selectively triggers T. cruzi cell death, involving both apoptosis and autophagy-induced necrosis.

The regulation of autophagy differentially affects Trypanosoma cruzi metacyclogenesis

“…cruzi . On the other hand, many trypanocidal drugs trigger autophagy in the parasite [ 58 , 59 ]. In this context, a deep knowledge of the mechanisms that regulate autophagy in this pathogen will contribute to a better understanding of the mechanisms of action of these drugs and improve the strategies for the treatment of Chagas’ disease.…”

Autophagy: A necessary process during the Trypanosoma cruzi life-cycle

“…As eukaryotic organisms, protists possess a rudimentary autophagic pathway that functions at specific stages of their life-cycles mainly during the differentiation processes [2]. Autophagy is also activated when pathogenic protists are treated with anti-parasitic drugs, as a mechanism to overcome the stress caused by the toxic compounds before cell death [52][53][54][55]. In addition, a growing body of evidence shows that intracellular protists have the ability to manipulate host-cell autophagy in order to establish or maintain the infection within a host.…”

Redox Balance Keepers and Possible Cell Functions Managed by Redox Homeostasis in Trypanosoma cruzi

“…Trypanosomes exhibit several features of eukaryotic cell apoptosis, including loss of mitochondrial membrane potential, cytochrome c release, cell shrinkage, and DNA fragmentation, although the exact mechanisms involved in PCD of trypanosomatids and its biological relevance is still under debate (De Souza et al, 2010;Dos Anjos et al, 2016;Menna-Barreto, 2019). The classical caspases and Bcl-2 homologs were not found in trypanosomes, but meta-caspases (TcMCA3 and TcMCA5) were described in T. cruzi (Laverriere et al, 2012).…”