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Transcriptomic analysis of reduced sensitivity to praziquantel in Schistosoma mansoni

ABSTRACT: Schistosomiasis is a chronic neglected tropical disease caused by digenetic parasitic flatworms of the genus Schistosoma. The disease is estimated to affect over 206 million people, the majority of whom live in Africa where Schistosoma mansoni and Schistosoma japonicum are the major causative agents. While a number of drugs have been used to treat schistosomiasis, praziquantel (PZQ) is the only one that is widely available, relatively cheap, and easy to use. The reliance on a single drug for the treatment of such a prevalent disease is a cause for concern due to the potential for resistance to render PZQ ineffective. In this study we examine the transcriptome of three generations of a laboratory strain of S. mansoni (PR1) whose susceptibility to PZQ has been diminished across 9 passages through exposure to increasing sub-lethal doses of the drug. Miracidial susceptibility was significantly reduced after exposure to 2 x 50 mg/Kg PZQ during the first passage. Susceptibility of worms in vivo was first assessed during passage 5 when mice infected with PZQ-selected schistosomes were dosed with a lethal dose of 3 x 300 mg/Kg PZQ resulting in only a 10% reduction in worm number compared to control treatment. The emergence of reduced sensitivity was marked by a shift in sex ratio from a predominantly male to female population, a reduction in the length of females and ultimately the loss of the PZQ-selected line after passage 9, perhaps due to a selection induced fitness cost. Analysis of differentially regulated transcripts did not suggest that any particular gene product or pathway was associated with drug resistance suggesting either a loss of function mutation to a single gene or an epistatic interaction of multiple gene products.

ORGANISM(S): Schistosoma mansoni

PROVIDER: GSE120682 | GEO | 2019/02/26

REPOSITORIES: GEO

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Project description:Schistosoma mansoni is one of the most common etiological agents responsible for the disease schistosomiasis. More than 200 million people suffer from this disease making it the most severe tropical disease after malaria in terms of morbidity. Praziquantel (PZQ) is the treatment of choice for schistosomiasis and has been used almost exclusively to treat the disease since the 1970s. However, while the drug is lethal for sexually mature schistosomes, it is ineffective against juveniles. Thus, while morbidity can be eased, a cure is difficult to achieve. As a result there is an urgent need to develop a new generation of anti-schistosomal drugs, a task that will be made easier by understanding the mechanism of action of PZQ. As yet, neither the molecule to which PZQ binds nor the means by which it kills mature schistosomes is known. The overarching aim of this study was to understand the molecular basis of PZQ sensitivity in S. mansoni. We believe that juvenile worms survive PZQ treatment in vivo due to the induction of, as yet, unidentified protective molecular pathways. To address this hypothesis juvenile and adult PR1 S. mansoni were treated in vitro with sub-lethal concentrations of PZQ. mRNA was extracted from replicate samples, cRNA prepagreen and labeled with cyanine dyes for analysis using a 44K S. mansoni microarray. The data was then analyzed using Genespring. Our findings suggest that a number of genes associated with drug transport, iron homeostasis and apoptosis are induced in juvenile but not adult schistosomes and that this allows the juvenile worms to protect themselves against the lethal effects of PZQ long enough for the drug to be metabolized by the human host. 42 days post exposure (DPE) male schistosomes were exposed to 0 and 1 µg/mL praziquantel (PZQ) for 1 or 20 h and 10 µg/mL PZQ for 1 h. 42 DPE female schistosomes were exposed to 0, 1 and 10 µg/mL PZQ for 20 h. 28 DPE mixed-sex schistosomes were exposed to 0, 1 and 10 µg/mL PZQ for 1 and 20 h. All experiments were performed in biological triplicates. The 0 µg/mL PZQ exposures were used as controls to the appropriate groups and a universal reference was used in all experiments that was comprised of RNA derived from 100 mixed sex, unexposed 42 DPE schistosomes spiked with 0.5 % (v/v) RNA isolated from 42 DPE mixed sex worms exposed to 10 µg/mL PZQ, 0.5 % (v/v) RNA isolated from 28 DPE worms exposed to 10 µg/mL PZQ and 0.5 % (v/v) RNA isolated from 28 DPE worms unexposed to PZQ. Transcriptional response to praziquantel exposure by time and concentration

Project description:Background: Treatment and morbidity control of schistosomiasis relies on a single drug, praziquantel. Therefore, there is a pressing need to explore the effects of PZQ on the parasites at the molecular level and to pursue alternative and/or or synergistic drugs against schistosomiasis. Methodology: We used a custom-designed Schistosoma mansoni oligo-microarray to explore the effects of a sublethal dose of praziquantel on S. mansoni adult worms’ gene expression. We used functional analysis of gene interaction networks to identify differentially expressed genes that are known targets of other drugs already tested in humans for diverse disease conditions. Omeprazole, a proton pump inhibitor drug that is widely prescribed, was tested in combination with praziquantel. We comparatively assessed the efficacy of praziquantel or omeprazole alone and in combination against S. mansoni adult worms in vitro over a period of 120 hours. Principal Findings: We identified sets of genes that were affected by praziquantel on both paired and unpaired females, however with opposite gene expression patterns (up-regulated in paired and down-regulated in unpaired females), indicating that the transcriptomics changes induced by praziquantel are heavily influenced by the mating status. We also identified genes that were similarly affected by praziquantel in males and females. The use of sublethal doses of praziquantel together with omeprazole showed a significantly enhanced worm mortality in vitro compared to praziquantel alone, thus evidencing a synergic effect. Conclusions: Functional analysis of gene interaction networks is an important approach to identify genes whose expression is affected by one drug and that are at the same time known targets of other drugs already tested in humans for diverse disease conditions, thus pointing the latter as possible synergic drugs. Combined treatment with omeprazol increases the efficacy of praziquantel against S. mansoni adult worms in vitro, and additional in vivo studies are warranted. Two-condition experiment, PZQ-treated vs. untreated . Biological replicates: 2 with dye-swap

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Transcriptomic analysis of reduced sensitivity to praziquantel in Schistosoma mansoni

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