Drug transporter and oxidative stress gene expression in human macrophages infected with benznidazole-sensitive and naturally benznidazole-resistant Trypanosoma cruzi parasites treated with benznidazole

New drug discovery strategies for the treatment of benznidazole-resistance in Trypanosoma cruzi, the causative agent of Chagas disease

INTRODUCTION

Benznidazole, the drug of choice for treating Chagas Disease (CD), has significant limitations, such as poor cure efficacy, mainly in the chronic phase of CD, association with side effects, and parasite resistance. Understanding parasite resistance to benznidazole is crucial for developing new drugs to treat CD.

AREAS COVERED

Here, the authors review the current understanding of the molecular basis of benznidazole resistance. Furthermore, they discuss the state-of-the-art methods and critical outcomes employed to evaluate the efficacy of potential drugs against T. cruzi, aiming to select better compounds likely to succeed in the clinic. Finally, the authors describe the different strategies employed to overcome resistance to benznidazole and find effective new treatments for CD.

EXPERT OPINION

Resistance to benznidazole is a complex phenomenon that occurs naturally among T. cruzi strains. The combination of compounds that inhibit different metabolic pathways of the parasite is an important strategy for developing a new chemotherapeutic protocol.

Transcriptomic Analysis of the Aged Nulliparous Mouse Ovary Suggests a Stress State That Promotes Pro-Inflammatory Lipid Signaling and Epithelial Cell Enrichment

Ovarian cancer (OC) incidence and mortality peaks at post-menopause while OC risk is either reduced by parity or increased by nulliparity during fertile life. The long-term effect of nulliparity on ovarian gene expression is largely unknown. In this study, we describe a bioinformatic/data-mining analysis of 112 coding genes upregulated in the aged nulliparous (NP) mouse ovary compared to the aged multiparous one as reference. Canonical gene ontology and pathway analyses indicated a pro-oxidant, xenobiotic-like state accompanied by increased metabolism of inflammatory lipid mediators. Up-regulation of typical epithelial cell markers in the aged NP ovary was consistent with synchronized overexpression of Cldn3, Ezr, Krt7, Krt8 and Krt18 during the pre-neoplastic phase of mOSE cell cultures in a former transcriptome study. In addition, 61/112 genes were upregulated in knockout mice for Fshr and for three other tumor suppressor genes (Pten, Cdh1 and Smad3) known to regulate follicular homeostasis in the mammalian ovary. We conclude that the aged NP ovary displays a multifaceted stress state resulting from oxidative imbalance and pro-inflammatory lipid signaling. The enriched epithelial cell content might be linked to follicle depletion and is consistent with abundant clefts and cysts observed in aged human and mouse ovaries. It also suggests a mesenchymal-to-epithelial transition in the mOSE of the aged NP ovary. Our analysis suggests that in the long term, nulliparity worsens a variety of deleterious effects of aging and senescence thereby increasing susceptibility to cancer initiation in the ovary.

Repurposing of rabeprazole as an anti-Trypanosoma cruzi drug that targets cellular triosephosphate isomerase

Trypanosoma cruzi is the causative agent of American trypanosomiasis, which mainly affects populations in Latin America. Benznidazole is used to control the disease, with severe effects in patients receiving this chemotherapy. Previous studies have demonstrated the inhibition of triosephosphate isomerase from T. cruzi, but cellular enzyme inhibition has yet to be established. This study demonstrates that rabeprazole inhibits both cell viability and triosephosphate isomerase activity in T. cruzi epimastigotes. Our results show that rabeprazole has an IC50 of 0.4 µM, which is 14.5 times more effective than benznidazole. Additionally, we observed increased levels of methyl-glyoxal and advanced glycation end products after the inhibition of cellular triosephosphate isomerase by rabeprazole. Finally, we demonstrate that the inactivation mechanisms of rabeprazole on triosephosphate isomerase of T. cruzi can be achieved through the derivatization of three of its four cysteine residues. These results indicate that rabeprazole is a promising candidate against American trypanosomiasis.

Effect of B-NIPOx in Experimental Trypanosoma cruzi Infection in Mice

Chagas disease is caused by Trypanosoma cruzi and represents a major public health problem, which is endemic in Latin America and emerging in the rest of the world. The two drugs that are currently available for its treatment, Benznidazole and Nifurtimox, are partially effective in the chronic phase of the disease. In this study, we designed and synthesized the benzyl ester of N-isopropyl oxamic acid (B-NIPOx), which is a non-polar molecule that crosses cell membranes. B-NIPOx is cleaved inside the parasite by carboxylesterases, releasing benzyl alcohol (a molecule with antimicrobial activity), and NIPOx, which is an inhibitor of α-hydroxy acid dehydrogenase isozyme II (HADH-II), a key enzyme in T. cruzi metabolism. We evaluated B-NIPOx cytotoxicity, its toxicity in mice, and its inhibitory activity on purified HADH-II and on T. cruzi homogenates. We then evaluated the trypanocidal activity of B-NIPOx in vitro and in vivo and its effect in the intestine of T. cruzi-infected mice. We found that B-NIPOx had higher trypanocidal activity on epimastigotes and trypomastigotes than Benznidazole and Nifurtimox, that it was more effective to reduce blood parasitemia and amastigote nests in infected mice, and that, in contrast to the reference drugs, it prevented the development of Chagasic enteropathy.

Prediction of potential cysteine synthase inhibitors of Leishmania braziliensis and Leishmania major parasites by computational screening

Leishmaniasis is a neglected tropical disease considered a public health problem that requires innovative strategies for its chemotherapeutic control. In the present investigation, a molecular docking approach was carried out using the protein cysteine synthase (CS) of Leishmania braziliensis (CSLb) and Leishmania major (CSLm) parasites to identify new compounds as potential candidates for the development of selective leishmaniasis therapy. CS protein sequence similarity, active site, structural modeling, molecular docking, and ADMET properties of compounds were analyzed using bioinformatics tools. Molecular docking analyses identified 1000 ligands with highly promising binding affinity scores for both CS proteins. A total of 182 compounds for CSLb and 173 for CSLm were selected for more detailed characterization based on the binding energy and frequency values and ADMET properties. Based on Principal Component Analysis (PCA) and K-means clusterization for both CS proteins, we classified compounds into 5 clusters for CSLb and 7 for CSLm, thus providing an excellent starting point for verification of enzyme inhibition in in vitro studies. We found the ZINC16524774 compound predicted to have a high affinity and stability for both CSLb and CSLm proteins, which was also evaluated through molecular dynamics simulations. Compounds within each of the five clusters also displayed pharmacological and structural properties that make them attractive drug candidates for the development of selective cutaneous leishmaniasis chemotherapy.

MDR1 protein (ABC-C1) Over Expression in Giardia Intestinalis Incubated with Albendazole and Nitazoxanide

BACKGROUND

Giardia intestinalis is a worldwide parasite. Drugs used for the treatment of giardiasis are metronidazole, albendazole and nitazoxanide. The development of drug resistance is an obstacle to the effective treatment. Resistance mechanisms in some parasites involve the participation of ATP-binding cassette (ABC) transporter superfamily.

PURPOSE

To find if the ATP-binding cassette genes are overexpressed in trophozoites treated with albendazole or nitazoxanide.

METHODS

A search for ATP-binding cassette genes in Giardia sequence database (GiardiaDB) was done and six genes were selected. Trophozoites treated with albendazole or nitazoxanide and the expression of these six ABC genes was quantitated by real-time RT-PCR. The ABC-C1 gene was selected, and a fragment cloned. The ABC-C1 protein was expressed, and polyclonal antibodies were elicited in mice to detect the protein in treated trophozoites, finally a docking analysis was performed for ABC-C1 and tizoxanide interaction.

RESULTS

Bioinformatics analysis showed that the ATP-binding cassette (ABC) topology is present in the six proteins. The qRT-PCR revealed that the ABC-C1 gene was overexpressed in cells incubated with nitazoxanide or albendazole. Confocal analysis showed that ABC-C1 protein levels increased in trophozoites with both treatments but was higher with nitazoxanide. The mark was detected heavily in the periphery of the cells. Using a docking analysis, it was found that the nitazoxanide metabolite, tizoxanide was docked close to the ATP-binding region as well as in the exit tunnel, located in the transmembrane region.

CONCLUSION

These findings in Giardia intestinalis, support the possible role of ABC-C1 in drug efflux.

Multidrug resistance protein structure of Trypanosoma evansi isolated from buffaloes in Ngawi District, Indonesia: A bioinformatics analysis

Background and Aim:

Trypanosomiasis, also known as surra, is an infectious disease with a wide host spectrum. In Indonesia, this disease is caused by Trypanosoma evansi. Various trypanocidal drugs have been used to treat this pathogen and subsequent disease. Yet, the long-term trypanocidal administration generates drug-resistant T. evansi. Some have identified genetic alterations in T. evansi transporter protein-coding genes that may be responsible for drug resistance. The Multidrug Resistance Protein E (MRPE) gene is a likely candidate gene responsible for the individual resistance. To date, no research has focused on T. evansi MRPE (TevMRPE) in this context. Hence, this research aimed at analyzing and characterizing the TevMRPE gene and protein using a bioinformatics approach.

Materials and Methods:

T. evansi was isolated from buffalo suffering from surra in Ngawi Regency, Indonesia. Isolated T. evansi was inoculated and cultured in male mice. The T. evansi genome was isolated from mouse blood with a parasitemia degree as high as 10⁵. A polymerase chain reaction procedure was conducted to amplify the putative MRPE coding gene. The amplicon was sequenced and analyzed using MEGA X, BLAST, and I-tasser softwares.

Results:

The putative TevMRPE coding gene showed sequence similarity as high as 99.79% against the MRPE gene from Trypanosoma brucei gambiense. The protein profile and characteristics depicted that the putative TevMRPE protein was related to a family of Adenosine Triphosphate-Binding Cassette (ABC) transporter proteins. This family of transporter proteins plays a crucial role in the resistance toward several medicines.

Conclusion:

The obtained gene sequence in this research was identified as the TevMRPE. This gene is homologous to the T. brucei gambiense MRPE gene and possesses ligand active sites for Adenylyl Imidodiphosphate. In addition, MRPE contains enzyme active sites similar to the cystic fibrosis transmembrane conductance regulator. These data suggest that ABC transport proteins, like MRPE, may be necessary to confer trypanocidal drug resistance in T. evansi.

Host-pathogen transcriptomics: Trypanosoma cruzi as a model for studying RNA contamination

Cellular infection assays constitute essential tools to understand host-pathogen interactions, particularly for intracellular microorganisms that are produced in cell lines are needed to propagate the microorganism. In this work, we demonstrate that RNA derived from Vero cells is an important contaminant to consider in order to avoid false positive results in transcriptomic experiments. We study the cross-contamination on a Trypanosoma cruzi cell infection model, the etiological agent of Chagas disease. We implemented the most frequently used trypanosome-purification protocols and, for all of them, we detected RNAs derived from Vero cells in trypomastigote extracts. For some of the protocols we also detected Vero RNAs in infected human cells. We also found this type of contamination in microarray experiments of human samples infected with T. cruzi. Concerning Illumina RNA-Seq data, we found that the contamination with Vero cells is probably introducing spurious results. Finally, we recommend a protocol to purify trypomastigotes, which showed a high percentage of trypomastigote recovery and the absence of Vero contamination in infected human samples. Avoiding this type of contamination should be an important factor to consider during experimental design, in order to minimize false positive results in transcriptomic studies as well as RNA contamination in vaccine production. SIGNIFICANCE: Transcriptomic studies are widely used to understand host-pathogen interactions. When the pathogen is an intracellular microorganism, an additional mammalian cell system can be needed to propagate it. In this work we demonstrate that pathogens purified from infected monolayers can carry RNAs from these mammalian cells, and that this ambient RNA contamination is probably producing false positive results in subsequent transcriptomic studies performed with qRT-PCR, microarrays or Next Generation Sequencing.