Entamoeba histolytica: Response of the parasite to metronidazole challenge on the levels of mRNA and protein expression

Tazreiter, Margit; Leitsch, David; Hatzenbichler, Evelyn; Mair-Scorpio, Georg E.; Steinborn, Ralf; Schreiber, Martin; Duchêne, Michael

doi:10.1016/j.exppara.2008.09.011

Cited by 20 publications

(18 citation statements)

References 34 publications

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“…To avoid interactions between dissolved oxygen and the stressors used in this study (30,31), we generated anaerobic conditions prior to and during stress exposures. In similarity to previous studies of transcription in G. duodenalis and other microaerobic protozoa (28,56,57), the magnitude of change in transcript abundance for many genes was modest. However, concerted biological replication allowed the identification of many genes that were differentially transcribed at statistical significance (FDR, 0.01).…”

Section: Discussionsupporting

confidence: 61%

Divergent Transcriptional Responses to Physiological and Xenobiotic Stress in Giardia duodenalis

Ansell

McConville

Baker

et al. 2016

Antimicrob Agents Chemother

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dUnderstanding how parasites respond to stress can help to identify essential biological processes. Giardia duodenalis is a parasitic protist that infects the human gastrointestinal tract and causes 200 to 300 million cases of diarrhea annually. Metronidazole, a major antigiardial drug, is thought to cause oxidative damage within the infective trophozoite form. However, treatment efficacy is suboptimal, due partly to metronidazole-resistant infections. To elucidate conserved and stress-specific responses, we calibrated sublethal metronidazole, hydrogen peroxide, and thermal stresses to exert approximately equal pressure on trophozoite growth and compared transcriptional responses after 24 h of exposure. We identified 252 genes that were differentially transcribed in response to all three stressors, including glycolytic and DNA repair enzymes, a mitogen-activated protein (MAP) kinase, high-cysteine membrane proteins, flavin adenine dinucleotide (FAD) synthetase, and histone modification enzymes. Transcriptional responses appeared to diverge according to physiological or xenobiotic stress. Downregulation of the antioxidant system and ␣-giardins was observed only under metronidazole-induced stress, whereas upregulation of GARP-like transcription factors and their subordinate genes was observed in response to hydrogen peroxide and thermal stressors. Limited evidence was found in support of stress-specific response elements upstream of differentially transcribed genes; however, antisense derepression and differential regulation of RNA interference machinery suggest multiple epigenetic mechanisms of transcriptional control. Giardia duodenalis (synonyms, Giardia lamblia and Giardia intestinalis) is a parasitic protist of the vertebrate gastrointestinal tract and the most common parasite of humans (1). The vegetative life cycle stage (trophozoite) infects around 1 billion people and causes 200 to 300 million cases of diarrheal disease (giardiasis) each year (1). Infection with G. duodenalis is also associated with the development of chronic diseases such as irritable bowel syndrome, chronic fatigue, and diabetes (2). At present, only two major drug classes are available to treat giardiasis: nitroimidazoles, primarily metronidazole (Mtz), and benzimidazoles, such as albendazole (3,4). Resistance to Mtz is documented in treatment-resistant clinical isolates (5-8), and resistant lines can be generated in vitro (reviewed in reference 9).The mechanism of action of Mtz is relatively poorly understood. This compound is thought to diffuse into G. duodenalis trophozoites as an inactive prodrug, whereupon it is enzymatically reduced (activated), yielding reactive intermediates. Mtz intermediates are thought to kill trophozoites by oxidizing proteins, lipids, and DNA (10, 11); however, the relative importance of damage to different biomolecules for Mtz-induced cytotoxicity is contested (10, 12). Resistance to Mtz involves changes in enzyme expression which limit drug activation. Nitroreductase-1, thioredoxin reductase, and pyruvat...

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Section: Discussionsupporting

confidence: 61%

Divergent Transcriptional Responses to Physiological and Xenobiotic Stress in Giardia duodenalis

Ansell

McConville

Baker

et al. 2016

Antimicrob Agents Chemother

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“…EhPrx1a was found to be upregulated about twofold in trophozoites under oxygen stress conditions (3) or exposure to 50 mM Trichostatin A, a histone deacetylase inhibitor (104). Increased expression of EhPrx1a (along with SOD) is also associated with metronidazole resistance (246,259).…”

Section: Prxs In Other Selected Protozoan Parasites Of Humansmentioning

confidence: 96%

Peroxiredoxins in Parasites

Gretes

Poole²,

Karplus³

2012

Antioxidants & Redox Signaling

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“…In E. histolytica , Samarawickrema et al ( 1997 ) reported the increased expression of iron-containing superoxide dismutase (Fe-SOD) in a strain resistant to 10 μM MTZ, while Wassmann et al ( 1999 ) showed that in addition to Fe-SOD upregulation, resistance to 40 μM MTZ was associated with increased peroxiredoxin (Prx) expression and decreased expression of Fdx. On the contrary, Tazreiter et al ( 2008 ) showed no substantial increase in Fe-SOD expression and less than 3-fold upregulation of Fdx and Prx in cells exposed to 50 μM MTZ. In addition, all three studies did not find any significant changes in PFOR expression, indicating that its downregulation may not be mandatory for low to modest drug resistance in this parasite.…”

Section: Introductionmentioning

confidence: 92%

Phenotypic and transcriptional profiling in Entamoeba histolytica reveal costs to fitness and adaptive responses associated with metronidazole resistance

2015

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Antimicrobial chemotherapy is critical in the fight against infectious diseases caused by Entamoeba histolytica. Among the drugs available for the treatment of amebiasis, metronidazole (MTZ) is considered the drug of choice. Recently, in vitro studies have described MTZ resistance and the potential mechanisms involved. Costs to fitness and adaptive responses associated with resistance, however, have not been investigated. In this study we generated an HM-1 derived strain resistant to 12 μM MTZ (MTZR). We examined its phenotypic and transcriptional profile to determine the consequences and mRNA level changes associated with MTZ resistance. Our results indicated increased cell size and granularity, and decreased rates in cell division, adhesion, phagocytosis, cytopathogenicity, and glucose consumption. Transcriptome analysis revealed 142 differentially expressed genes in MTZR. In contrast to other MTZ resistant parasites, MTZR did not down-regulate pyruvate:ferredoxin oxidoreductase, but showed increased expression of genes for a hypothetical protein (HP1) and several iron-sulfur flavoproteins, and downregulation of genes for leucine-rich proteins. Fisher's exact test showed 24 significantly enriched GO terms in MTZR, and a 3-way comparison of modulated genes in MTZR against those of MTZR cultured without MTZ and HM-1 cultured with MTZ, showed that 88 genes were specific to MTZR. Overall, our findings suggested that MTZ resistance is associated with specific transcriptional changes and decreased parasite virulence.

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Entamoeba histolytica: Response of the parasite to metronidazole challenge on the levels of mRNA and protein expression

Cited by 20 publications

References 34 publications

Divergent Transcriptional Responses to Physiological and Xenobiotic Stress in Giardia duodenalis

Divergent Transcriptional Responses to Physiological and Xenobiotic Stress in Giardia duodenalis

Peroxiredoxins in Parasites

Phenotypic and transcriptional profiling in Entamoeba histolytica reveal costs to fitness and adaptive responses associated with metronidazole resistance

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