DNA damage and oxidative stress in human cells infected by Trypanosoma cruzi.

Pilar T V Florentino,Renato A Mortara,Davi J Martins,Francisca Nathalia L Vitorino,Davi Mendes,Julia P C Cunha,Carlos F M Menck,Richard Mcculloch

doi:10.1371/journal.ppat.1009502

Pilar T V Florentino, Renato A Mortara + Show 6 more

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https://doi.org/10.1371/journal.ppat.1009502

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Abstract

Trypanosoma cruzi is the etiologic agent of Chagas’ disease. Infected cells with T. cruzi activate several responses that promote unbalance of reactive oxygen species (ROS) that may cause DNA damage that activate cellular responses including DNA repair processes. In this work, HeLa cells and AC16 human cardiomyocyte cell line were infected with T. cruzi to investigate host cell responses at genome level during parasites intracellular life cycle. In fact, alkaline sensitive sites and oxidized DNA bases were detected in the host cell genetic material particularly in early stages of infection. These DNA lesions were accompanied by phosphorylation of the histone H2Ax, inducing γH2Ax, a marker of genotoxic stress. Moreover, Poly [ADP-ribose] polymerase-1 (PARP1) and 8-oxoguanine glycosylase (OGG1) are recruited to host cell nuclei, indicating activation of the DNA repair process. In infected cells, chromatin-associated proteins are carbonylated, as a possible consequence of oxidative stress and the nuclear factor erythroid 2–related factor 2 (NRF2) is induced early after infection, suggesting that the host cell antioxidant defenses are activated. However, at late stages of infection, NRF2 is downregulated. Interestingly, host cells treated with glutathione precursor, N-acetyl cysteine, NRF2 activator (Sulforaphane), and also Benznidonazol (BNZ) reduce parasite burst significantly, and DNA damage. These data indicate that the balance of oxidative stress and DNA damage induction in host cells may play a role during the process of infection itself, and interference in these processes may hamper T. cruzi infection, revealing potential target pathways for the therapy support.

Highlights

Chagas’ disease is caused by flagellated protozoan Trypanosoma cruzi and is endemic in 22 countries in Latin America
We propose that reactive oxygen species (ROS) mediated by T. cruzi infection could benefit parasite survival and cause DNA damage, interfere with host cell cycle affecting DNA metabolism and RNA transcription in early and late stages of in vitro infection, conducting host cell death
Higher tail moments were detected 1 h post-infection when Formamidopyrimidine DNA glycosylase (FPG) was added to the assay, indicating increased oxidized bases in the HeLa cells genome (Fig 1A)

Summary

Introduction

Chagas’ disease is caused by flagellated protozoan Trypanosoma cruzi and is endemic in 22 countries in Latin America. T. cruzi pathology in host mammal presents two characteristic phases. Chronic phase presents itself after 30–40 years later and about 30–40% of the infected individuals develop severe cardiac or digestive complications [3,4]. Benznidazole (BNZ; N-benzyl-2-nitroimidazole acetamide) and Nifurtimox (NFX) are the only drugs approved to treat Chagas disease. These drugs help to clear parasites in a significant number of chronic patients, without, necessarily, restoring complications of the infection. BNZ is the only drug available in most Latin American countries and is considered to be better tolerated by patients [5,6]. The effort to comprehend how this drug act on parasite’s physiology, there is still little understanding of the mechanism of action on host cells from patients. Recent work found that after 3 h of treatment, BNZ increases intracellular ROS, consenquently leading to an antioxidant response, mediated by nuclear factor erythroid 2-related factor 2 (NRF2), in HEPG2 cells [11]

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