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Abstract
The amoeba parasite Entamoeba histolytica is the causative agent of human amebiasis, an enteropathic disease affecting millions of people worldwide. This ancient protozoan is an elementary example of how parasites evolve with humans, e.g. taking advantage of multiple mechanisms to evade immune responses, interacting with microbiota for nutritional and protective needs, utilizing host resources for growth, division, and encystation. These skills of E. histolytica perpetuate the species and incidence of infection. However, in 10% of infected cases, the parasite turns into a pathogen; the host-parasite equilibrium is then disorganized, and the simple lifecycle based on two cell forms, trophozoites and cysts, becomes unbalanced. Trophozoites acquire a virulent phenotype which, when non-controlled, leads to intestinal invasion with the onset of amoebiasis symptoms. Virulent E. histolytica must cross mucus, epithelium, connective tissue and possibly blood. This highly mobile parasite faces various stresses and a powerful host immune response, with oxidative stress being a challenge for its survival. New emerging research avenues and omics technologies target gene regulation to determine human or parasitic factors activated upon infection, their role in virulence activation, and in pathogenesis; this research bears in mind that E. histolytica is a resident of the complex intestinal ecosystem. The goal is to eradicate amoebiasis from the planet, but the parasitic life of E. histolytica is ancient and complex and will likely continue to evolve with humans. Advances in these topics are summarized here.
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Affiliation(s)
- Nancy Guillén
- Cell Biology and Infection Department, Institut Pasteur and Centre National de la Recherche Scientifique CNRS-ERM9195, Paris, France
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2
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Tunali V, Korkmaz M. Emerging and Re-Emerging Parasitic Infections of the Central Nervous System (CNS) in Europe. Infect Dis Rep 2023; 15:679-699. [PMID: 37987400 PMCID: PMC10660548 DOI: 10.3390/idr15060062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 10/12/2023] [Accepted: 10/20/2023] [Indexed: 11/22/2023] Open
Abstract
In a rapidly evolving global landscape characterized by increased international travel, migration, and ecological shifts, this study sheds light on the emergence of protozoal and helminthic infections targeting the central nervous system (CNS) within Europe. Despite being traditionally associated with tropical regions, these infections are progressively becoming more prevalent in non-endemic areas. By scrutinizing the inherent risks, potential outcomes, and attendant challenges, this study underscores the intricate interplay between diagnostic limitations, susceptibility of specific population subsets, and the profound influence of climate fluctuations. The contemporary interconnectedness of societies serves as a conduit for introducing and establishing these infections, warranting comprehensive assessment. This study emphasizes the pivotal role of heightened clinician vigilance, judicious public health interventions, and synergistic research collaborations to mitigate the potential consequences of these infections. Though rare, their profound impact on morbidity and mortality underscores the collective urgency required to safeguard the neurological well-being of the European populace. Through this multifaceted approach, Europe can effectively navigate the complex terrain posed with these emergent infections.
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Affiliation(s)
- Varol Tunali
- Department of Parasitology, Faculty of Medicine, Manisa Celal Bayar University, 45030 Manisa, Turkey
- Department of Emergency Medicine, Izmir Metropolitan Municipality Eşrefpaşa Hospital, 35170 Izmir, Turkey
| | - Metin Korkmaz
- Department of Parasitology, Faculty of Medicine, Ege University, 35100 Izmir, Turkey;
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Chadha A, Chadee K. The NF-κB Pathway: Modulation by Entamoeba histolytica and Other Protozoan Parasites. Front Cell Infect Microbiol 2021; 11:748404. [PMID: 34595137 PMCID: PMC8476871 DOI: 10.3389/fcimb.2021.748404] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 08/27/2021] [Indexed: 12/15/2022] Open
Abstract
Protozoan parasites have led to worldwide devastation because of their ability to cause infectious diseases. They have evolved as successful pathogens in part because of their remarkable and sophisticated ways to evade innate host defenses. This holds true for both intracellular and extracellular parasites that deploy multiple strategies to circumvent innate host defenses for their survival. The different strategies protozoan parasites use include hijacking the host cellular signaling pathways and transcription factors. In particular, the nuclear factor-κB (NF-κB) pathway seems to be an attractive target for different pathogens owing to their central role in regulating prompt innate immune responses in host defense. NF-κB is a ubiquitous transcription factor that plays an indispensable role not only in regulating immediate immune responses against invading pathogens but is also a critical regulator of cell proliferation and survival. The major immunomodulatory components include parasite surface and secreted proteins/enzymes and stimulation of host cells intracellular pathways and inflammatory caspases that directly or indirectly interfere with the NF-κB pathway to thwart immune responses that are directed for containment and/or elimination of the pathogen. To showcase how protozoan parasites exploits the NF-κB signaling pathway, this review highlights recent advances from Entamoeba histolytica and other protozoan parasites in contact with host cells that induce outside-in and inside-out signaling to modulate NF-κB in disease pathogenesis and survival in the host.
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Affiliation(s)
- Attinder Chadha
- Departments of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - Kris Chadee
- Departments of Microbiology, Immunology, and Infectious Diseases, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
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Chadha A, Moreau F, Wang S, Dufour A, Chadee K. Entamoeba histolytica activation of caspase-1 degrades cullin that attenuates NF-κB dependent signaling from macrophages. PLoS Pathog 2021; 17:e1009936. [PMID: 34499701 PMCID: PMC8454965 DOI: 10.1371/journal.ppat.1009936] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 09/21/2021] [Accepted: 09/01/2021] [Indexed: 12/18/2022] Open
Abstract
While Entamoeba histolytica (Eh)-induced pro-inflammatory responses are critical in disease pathogenesis, the downstream signaling pathways that subsequently dampens inflammation and the immune response remains unclear. Eh in contact with macrophages suppresses NF-κB signaling while favoring NLRP3-dependent pro-inflammatory cytokine production by an unknown mechanism. Cullin-1 and cullin-5 (cullin-1/5) assembled into a multi-subunit RING E3 ubiquitin ligase complex are substrates for neddylation that regulates the ubiquitination pathway important in NF-κB activity and pro-inflammatory cytokine production. In this study, we showed that upon live Eh contact with human macrophages, cullin-1/4A/4B/5 but not cullin-2/3, were degraded within 10 minutes. Similar degradation of cullin-1/5 were observed from colonic epithelial cells and proximal colonic loops tissues of mice inoculated with live Eh. Degradation of cullin-1/5 was dependent on Eh-induced activation of caspase-1 via the NLRP3 inflammasome. Unlike cullin-4B, the degradation of cullin-4A was partially dependent on caspase-1 and was inhibited with a pan caspase inhibitor. Cullin-1/5 degradation was dependent on Eh cysteine proteinases EhCP-A1 and EhCP-A4, but not EhCP-A5, based on pharmacological inhibition of the cysteine proteinases and EhCP-A5 deficient parasites. siRNA silencing of cullin-1/5 decreased the phosphorylation of pIκ-Bα in response to Eh and LPS stimulation and downregulated NF-κB-dependent TNF-α mRNA expression and TNF-α and MCP-1 pro-inflammatory cytokine production. These results unravel a unique outside-in strategy employed by Eh to attenuate NF-κB-dependent pro-inflammatory responses via NLRP3 activation of caspase-1 that degraded cullin-1/5 from macrophages. The protozoan parasite Entamoeba histolytica (Eh) is the etiologic agent for the disease amebiasis. It is a potent pathogen that deploys an arsenal of virulence factors to trigger and subvert host immune defenses. One of the hallmark features of the disease is amebic colitis and in extreme cases, it can lead to abscesses of the liver and brain. For unknown reasons, the parasite breaches colonic mucosal barriers and invade underlying tissues. The host immune system plays a decisive role in determining the outcome of the disease. At the molecular level, the interaction of Eh with macrophage is a turning point in shaping pro-inflammatory responses. Understanding host-pathogen intricacies at the molecular level is key in determining the complexity of the disease. In the context of amebiasis, the underlying molecular events that occur at the Eh-macrophage intercellular junction are partly unravelled. Here we sought to interrogate the mechanisms by which NF-κB signaling is aborted following Eh-macrophage contact and found two regulatory scaffold proteins, cullin-1 and -5 (cullin-1/5) of the multiple E3 ligase complex, are degraded leading to dampening of NF-κB signaling. During Eh-macrophage contact, cullin-1/4A/4B/5 were rapidly degraded whereas cullin-2/3 were not. The degradation of cullin-1/5 was highly dependent on Eh-induced caspase-1 activation via the NLRP3 inflammasome. In contrast, the degradation of cullin-4A but not cullin-4B, was partially dependent on caspase-1 and was inhibited with a cell-permeable pan caspase inhibitor. Intriguingly, we found that Eh virulence factor EhCP-A1 and EhCP-A4, but not EhCP-A5, played an important role in mediating the degradation of these proteins. Silencing cullin-1/5 decreased the phosphorylation of Iκ-Bα in response to Eh and LPS stimulation that markedly downregulated NF-κB-dependent TNF-α mRNA expression and TNF-α and MCP-1 pro-inflammatory cytokine production. This study unravelled a novel role for Eh-induced NLRP3 inflammasome activation of caspase-1 that intersected with the NF-κB pathway leading to the degradation of the novel substrates cullin-1/5 that regulates NF-κB-dependent pro-inflammatory cytokine production.
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Affiliation(s)
- Attinder Chadha
- Departments of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - France Moreau
- Departments of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Shanshan Wang
- Departments of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Antoine Dufour
- Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada
- Biochemistry and Molecular Biology, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada
| | - Kris Chadee
- Departments of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
- * E-mail:
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Wesel J, Shuman J, Bastuzel I, Dickerson J, Ingram-Smith C. Encystation of Entamoeba histolytica in Axenic Culture. Microorganisms 2021; 9:873. [PMID: 33919506 PMCID: PMC8074197 DOI: 10.3390/microorganisms9040873] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 04/15/2021] [Accepted: 04/16/2021] [Indexed: 12/16/2022] Open
Abstract
Entamoeba histolytica is a parasitic protozoan that causes amoebic dysentery, which affects approximately 90 million people each year worldwide. E. histolytica is transmitted through ingestion of food and water contaminated with the cyst form, which undergoes excystation in the small intestine to the trophozoite form that colonizes the large intestine. The reptile pathogen Entamoeba invadens has served as a model for studying stage conversion between the trophozoite and cyst form due to lack of reproducible encystation of E. histolytica in the laboratory. Although much has been learned about encystation and excystation using E. invadens, the findings do not fully translate to E. histolytica due to the extensive genetic and host differences between these species. Here, we present the first reproducible encystation of E. histolytica in vitro. The cysts produced were viable and displayed the four characteristic hallmarks: round shape, chitinous cell wall, tetranucleation, and detergent resistance. Using flow cytometry analysis, glucose limitation and high cell density were key for encystation, as for E. invadens. Entry into encystation was enhanced by the short-chain fatty acids acetate and propionate, unlike for E. invadens. This new model will now allow the further study of E. histolytica stage conversion, transmission, and treatment.
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Affiliation(s)
- Jordan Wesel
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA; (J.W.); (J.S.); (I.B.); (J.D.)
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, SC 29634, USA
| | - Jennifer Shuman
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA; (J.W.); (J.S.); (I.B.); (J.D.)
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, SC 29634, USA
| | - Irem Bastuzel
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA; (J.W.); (J.S.); (I.B.); (J.D.)
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, SC 29634, USA
| | - Julie Dickerson
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA; (J.W.); (J.S.); (I.B.); (J.D.)
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, SC 29634, USA
| | - Cheryl Ingram-Smith
- Department of Genetics and Biochemistry, Clemson University, Clemson, SC 29634, USA; (J.W.); (J.S.); (I.B.); (J.D.)
- Eukaryotic Pathogens Innovation Center, Clemson University, Clemson, SC 29634, USA
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Sauvey C, Ehrenkaufer G, Shi D, Debnath A, Abagyan R. Antineoplastic kinase inhibitors: A new class of potent anti-amoebic compounds. PLoS Negl Trop Dis 2021; 15:e0008425. [PMID: 33556060 PMCID: PMC7895358 DOI: 10.1371/journal.pntd.0008425] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 02/19/2021] [Accepted: 12/21/2020] [Indexed: 12/17/2022] Open
Abstract
Entamoeba histolytica is a protozoan parasite which infects approximately 50 million people worldwide, resulting in an estimated 70,000 deaths every year. Since the 1960s E. histolytica infection has been successfully treated with metronidazole. However, drawbacks to metronidazole therapy exist, including adverse effects, a long treatment course, and the need for an additional drug to prevent cyst-mediated transmission. E. histolytica possesses a kinome with approximately 300–400 members, some of which have been previously studied as potential targets for the development of amoebicidal drug candidates. However, while these efforts have uncovered novel potent inhibitors of E. histolytica kinases, none have resulted in approved drugs. In this study we took the alternative approach of testing a set of twelve previously FDA-approved antineoplastic kinase inhibitors against E. histolytica trophozoites in vitro. This resulted in the identification of dasatinib, bosutinib, and ibrutinib as amoebicidal agents at low-micromolar concentrations. Next, we utilized a recently developed computational tool to identify twelve additional drugs with human protein target profiles similar to the three initial hits. Testing of these additional twelve drugs led to the identification of ponatinib, neratinib, and olmutinib were identified as highly potent, with EC50 values in the sub-micromolar range. All of these six drugs were found to kill E. histolytica trophozoites as rapidly as metronidazole. Furthermore, ibrutinib was found to kill the transmissible cyst stage of the model organism E. invadens. Ibrutinib thus possesses both amoebicidal and cysticidal properties, in contrast to all drugs used in the current therapeutic strategy. These findings together reveal antineoplastic kinase inhibitors as a highly promising class of potent drugs against this widespread and devastating disease. Every year, nearly a hundred thousand people worldwide die from infection by the intestinal parasite Entamoeba histolytica, despite the widespread availability of metronidazole as a treatment. Here we report that six anticancer drugs of the kinase inhibitor class possess potent anti-amoebic properties, with one of them killing both actively dividing parasite and its transmissible cysts. These anticancer kinase inhibitors, including the dual-purpose drug with both amoebicidal and cysticidal activities may be used to treat amoebiasis, especially in cancer patients or in life-threatening brain- and liver-infecting forms of the disease.
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Affiliation(s)
- Conall Sauvey
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School for Pharmacy and Pharmaceutical Sciences, University of California—San Diego, La Jolla, California, United States of America
- * E-mail: (CS); (RA)
| | - Gretchen Ehrenkaufer
- Division of Infectious Diseases, Department of Internal Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Da Shi
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School for Pharmacy and Pharmaceutical Sciences, University of California—San Diego, La Jolla, California, United States of America
| | - Anjan Debnath
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School for Pharmacy and Pharmaceutical Sciences, University of California—San Diego, La Jolla, California, United States of America
| | - Ruben Abagyan
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School for Pharmacy and Pharmaceutical Sciences, University of California—San Diego, La Jolla, California, United States of America
- * E-mail: (CS); (RA)
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Single-Cell RNA Sequencing Reveals that the Switching of the Transcriptional Profiles of Cysteine-Related Genes Alters the Virulence of Entamoeba histolytica. mSystems 2020; 5:5/6/e01095-20. [PMID: 33361325 PMCID: PMC7762796 DOI: 10.1128/msystems.01095-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Studies on the trophozoite of Entamoeba histolytica suggested this organism could accumulate polyploid cells in its proliferative phase and differentiate its cell cycle from that of other eukaryotes. Therefore, a single-cell sequencing technique was used to study the switching of the RNA transcription profiles of single amoebic trophozoites. Entamoeba histolytica is an intestinal protozoan that causes human amoebic colitis and extraintestinal abscesses. Virulence variation is observed in the pathogenicity of E. histolytica trophozoites, but the detailed mechanism remains unclear. Here, a single trophozoite was cultured alone, and the progeny of the trophozoites of each generation were subjected to single-cell RNA sequencing (scRNA-seq) to study the transcriptional profiles of trophozoites. The scRNA-seq analysis indicated the importance of sulfur metabolism and the proteasome pathway in pathogenicity, whereas the isobaric tags for relative and absolute quantitation (iTRAQ) proteomic analysis did not identify the bulk trophozoites. The trophozoite improved the synthesis of cysteine under cysteine-deficient conditions but downregulated the expression of the intermediate subunit of the lectin of E. histolytica trophozoites and retained the expression of the heavy subunit of lectin, resulting in decreased amoebic phagocytosis and cytotoxicity. The variation in the transmembrane kinase gene family might be critical in regulating the proteasome pathway. Thus, the scRNA-seq technique provided an improved understanding of the biological characteristics and the mechanism of virulence variation of amoebic trophozoites. IMPORTANCE Studies on the trophozoite of Entamoeba histolytica suggested this organism could accumulate polyploid cells in its proliferative phase and differentiate its cell cycle from that of other eukaryotes. Therefore, a single-cell sequencing technique was used to study the switching of the RNA transcription profiles of single amoebic trophozoites. We separated individual trophozoites from axenic cultured trophozoites, CHO cell-incubated trophozoites, and in vivo trophozoites. We found important changes in the sulfur and cysteine metabolism in pathogenicity. The trophozoites strategically regulated the expression of the cysteine-rich protein-encoding genes under cysteine-deficient conditions, thereby decreasing amoebic phagocytosis and cytotoxicity. The single-cell sequencing technique shows evident advantages in comparison with the isobaric tags for relative and absolute quantitation (iTRAQ) proteomic technology (bulk trophozoite level) and reveals the regulation strategy of trophozoites in the absence of exogenous cysteine. This regulation strategy may be the mechanism of virulence variation of amoebic trophozoites.
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Shahi P, Moreau F, Chadee K. Entamoeba histolytica Cyclooxygenase-Like Protein Regulates Cysteine Protease Expression and Virulence. Front Cell Infect Microbiol 2019; 8:447. [PMID: 30687644 PMCID: PMC6333869 DOI: 10.3389/fcimb.2018.00447] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 12/17/2018] [Indexed: 12/19/2022] Open
Abstract
The intestinal protozoan parasite Entamoeba histolytica (Eh) causes amebiasis associated with severe diarrhea and/or liver abscess. Eh pathogenesis is multifactorial requiring both parasite virulent molecules and host-induced innate immune responses. Eh-induced host pro-inflammatory responses plays a critical role in disease pathogenesis by causing damage to tissues allowing parasites access to systemic sites. Eh cyclooxygenase (EhCox) derived prostaglandin E2 stimulates the chemokine IL-8 from mucosal epithelial cells that recruits neutrophils to the site of infection to exacerbate disease. At present, it is not known how EhCox is regulated or whether it affects the expression of other proteins in Eh. In this study, we found that gene silencing of EhCox (EhCoxgs) markedly increased endogenous cysteine protease (CP) protein expression and virulence without altering CP gene transcripts. Live virulent Eh pretreated with arachidonic acid substrate to enhance PGE2 production or aspirin to inhibit EhCox enzyme activity or addition of exogenous PGE2 to Eh had no effect on EhCP activity. Increased CP enzyme activity in EhCoxgs was stable and significantly enhanced erythrophagocytosis, cytopathic effects on colonic epithelial cells and elicited pro-inflammatory cytokines in mice colonic loops. Acute infection with EhCoxgs in colonic loops increased inflammation associated with high levels of myeloperoxidase activity. This study has identified EhCox protein as one of the important endogenous regulators of cysteine protease activity. Alterations of CP activity in response to Cox gene silencing may be a negative feedback mechanism in Eh to limit proteolytic activity during colonization that can inadvertently trigger inflammation in the gut.
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Affiliation(s)
| | | | - Kris Chadee
- Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
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9
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Abstract
BACKGROUND Infection with the protozoan Entamoeba histolytica is common in low- and middle-income countries, and up to 100,000 people with severe disease die every year. Adequate therapy for amoebic colitis is necessary to reduce illness, prevent development of complicated disease and extraintestinal spread, and decrease transmission. OBJECTIVES To evaluate antiamoebic drugs for treating amoebic colitis. SEARCH METHODS We searched the available literature up to 22 March 2018. We searched the Cochrane Infectious Diseases Group Specialised Register, CENTRAL, MEDLINE, Embase, LILACS, mRCT, and conference proceedings. We contacted individual researchers, organizations, and pharmaceutical companies, and we checked reference lists. SELECTION CRITERIA Randomized controlled trials of antiamoebic drugs given alone or in combination, compared with placebo or another antiamoebic drug, for treating adults and children with a diagnosis of amoebic colitis. DATA COLLECTION AND ANALYSIS Two review authors independently assessed the eligibility and methodological quality of trials and extracted and analysed the data. We calculated clinical and parasitological failure rates and rates of relapse and adverse events as risk ratios (RRs) with 95% confidence intervals (CIs), using a random-effects model. We determined statistical heterogeneity and explored possible sources of heterogeneity using subgroup analyses. We carried out sensitivity analysis by using trial quality to assess the robustness of reported results. MAIN RESULTS In total, 41 trials (4999 participants) met the inclusion criteria of this review. In this update, we added four trials to the 37 trials included in the first published review version. Thirty trials were published over 20 years ago. Only one trial used adequate methods of randomization and allocation concealment, was blinded, and analysed all randomized participants. Only one trial used an E histolytica stool antigen test, and two trials used amoebic culture.Tinidazole may be more effective than metronidazole for reducing clinical failure (RR 0.28, 95% CI 0.15 to 0.51; 477 participants, eight trials; low-certainty evidence) and is probably associated with fewer adverse events (RR 0.65, 95% CI 0.46 to 0.92; 477 participants, 8 trials; moderate-certainty evidence). Compared with metronidazole, combination therapy may result in fewer parasitological failures (RR 0.36, 95% CI 0.15 to 0.86; 720 participants, 3 trials; low-certainty evidence), but we are uncertain which combination is more effective than another. Evidence is insufficient to allow conclusions regarding the efficacy of other antiamoebic drugs. AUTHORS' CONCLUSIONS Compared with metronidazole, tinidazole may be more effective in reducing clinical failure and may be associated with fewer adverse events. Combination drug therapy may be more effective for reducing parasitological failure compared with metronidazole alone. However, these results are based mostly on small trials conducted over 20 years ago with a variety of poorly defined outcomes. Tests that detect E histolytica more accurately are needed, particularly in countries where concomitant infection with other bacteria and parasites is common.
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Affiliation(s)
- Maria Liza M Gonzales
- University of the Philippines Manila College of Medicine‐Philippine General HospitalDepartment of PediatricsTaft AvenueManilaNational Capital RegionPhilippines1000
| | - Leonila F Dans
- University of the Philippines Manila College of Medicine‐Philippine General HospitalDepartment of PediatricsTaft AvenueManilaNational Capital RegionPhilippines1000
| | - Juliet Sio‐Aguilar
- University of the Philippines Manila College of Medicine‐Philippine General HospitalDepartment of PediatricsTaft AvenueManilaNational Capital RegionPhilippines1000
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Fonseca Z, Díaz-Godínez C, Mora N, Alemán OR, Uribe-Querol E, Carrero JC, Rosales C. Entamoeba histolytica Induce Signaling via Raf/MEK/ERK for Neutrophil Extracellular Trap (NET) Formation. Front Cell Infect Microbiol 2018; 8:226. [PMID: 30023352 PMCID: PMC6039748 DOI: 10.3389/fcimb.2018.00226] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 06/15/2018] [Indexed: 12/25/2022] Open
Abstract
Amoebiasis, the disease caused by Entamoeba histolytica is the third leading cause of human deaths among parasite infections. E. histolytica was reported associated with around 100 million cases of amoebic dysentery, colitis and amoebic liver abscess that lead to almost 50,000 fatalities worldwide in 2010. E. histolytica infection is associated with the induction of inflammation characterized by a large number of infiltrating neutrophils. These neutrophils have been implicated in defense against this parasite, by mechanisms not completely described. The neutrophil antimicrobial mechanisms include phagocytosis, degranulation, and formation of neutrophil extracellular traps (NETs). Recently, our group reported that NETs are also produced in response to E. histolytica trophozoites. But, the mechanism for NETs induction remains unknown. In this report we explored the possibility that E. histolytica leads to NETs formation via a signaling pathway similar to the pathways activated by PMA or the Fc receptor FcγRIIIb. Neutrophils were stimulated by E. histolytica trophozoites and the effect of various pharmacological inhibitors on amoeba-induced NETs formation was assessed. Selective inhibitors of Raf, MEK, and NF-κB prevented E. histolytica-induced NET formation. In contrast, inhibitors of PKC, TAK1, and NADPH-oxidase did not block E. histolytica-induced NETs formation. E. histolytica induced phosphorylation of ERK in a Raf and MEK dependent manner. These data show that E. histolytica activates a signaling pathway to induce NETs formation, that involves Raf/MEK/ERK, but it is independent of PKC, TAK1, and reactive oxygen species (ROS). Thus, amoebas activate neutrophils via a different pathway from the pathways activated by PMA or the IgG receptor FcγRIIIb.
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Affiliation(s)
- Zayda Fonseca
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - César Díaz-Godínez
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Nancy Mora
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Omar R Alemán
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Eileen Uribe-Querol
- División de Estudios de Posgrado e Investigación, Facultad de Odontología, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Julio C Carrero
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos Rosales
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Nakada-Tsukui K, Sekizuka T, Sato-Ebine E, Escueta-de Cadiz A, Ji DD, Tomii K, Kuroda M, Nozaki T. AIG1 affects in vitro and in vivo virulence in clinical isolates of Entamoeba histolytica. PLoS Pathog 2018; 14:e1006882. [PMID: 29554130 PMCID: PMC5884625 DOI: 10.1371/journal.ppat.1006882] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 04/04/2018] [Accepted: 01/17/2018] [Indexed: 11/17/2022] Open
Abstract
The disease state of amebiasis, caused by Entamoeba histolytica, varies from asymptomatic to severe manifestations that include dysentery and extraintestinal abscesses. The virulence factors of the pathogen, and host defense mechanisms, contribute to the outcomes of infection; however, the underlying genetic factors, which affect clinical outcomes, remain to be fully elucidated. To identify these genetic factors in E. histolytica, we used Illumina next-generation sequencing to conduct a comparative genomic analysis of two clinical isolates obtained from diarrheal and asymptomatic patients (strains KU50 and KU27, respectively). By mapping KU50 and KU27 reads to the genome of a reference HM-1:IMSS strain, we identified two genes (EHI_089440 and EHI_176590) that were absent in strain KU27. In KU27, a single AIG1 (avrRpt2-induced gene 1) family gene (EHI_176590) was found to be deleted, from a tandem array of three AIG1 genes, by homologous recombination between the two flanking genes. Overexpression of the EHI_176590 gene, in strain HM-1:IMSS cl6, resulted in increased formation of cell-surface protrusions and enhanced adhesion to human erythrocytes. The EHI_176590 gene was detected by PCR in 56% of stool samples from symptomatic patients infected with E. histolytica, but only in 15% of stool samples from asymptomatic individuals. This suggests that the presence of the EHI_176590 gene is correlated with the outcomes of infection. Taken together, these data strongly indicate that the AIG1 family protein plays a pivotal role in E. histolytica virulence via regulation of host cell adhesion. Our in-vivo experiments, using a hamster liver abscess model, showed that overexpression or gene silencing of EHI_176590 reduced and increased liver abscess formation, respectively. This suggests that the AIG1 genes may have contrasting roles in virulence depending on the genetic background of the parasite and host environment.
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Affiliation(s)
- Kumiko Nakada-Tsukui
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tsuyoshi Sekizuka
- Laboratory of Bacterial Genomics, Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Emi Sato-Ebine
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
| | | | - Dar-der Ji
- Center for Research and Diagnostics, Centers for Disease Control, Taipei, Taiwan
| | - Kentaro Tomii
- Artificial Intelligence Research Center (AIRC) and Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Industrial Science and Technology (AIST), Tokyo, Japan
| | - Makoto Kuroda
- Laboratory of Bacterial Genomics, Pathogen Genomics Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tomoyoshi Nozaki
- Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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12
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Herman E, Siegesmund MA, Bottery MJ, van Aerle R, Shather MM, Caler E, Dacks JB, van der Giezen M. Membrane Trafficking Modulation during Entamoeba Encystation. Sci Rep 2017; 7:12854. [PMID: 28993644 PMCID: PMC5634486 DOI: 10.1038/s41598-017-12875-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 09/11/2017] [Indexed: 12/15/2022] Open
Abstract
Entamoeba histolytica is an intestinal parasite that infects 50-100 million people and causes up to 55,000 deaths annually. The transmissive form of E. histolytica is the cyst, with a single infected individual passing up to 45 million cysts per day, making cyst production an attractive target for infection control. Lectins and chitin are secreted to form the cyst wall, although little is known about the underlying membrane trafficking processes supporting encystation. As E. histolytica does not readily form cysts in vitro, we assessed membrane trafficking gene expression during encystation in the closely related model Entamoeba invadens. Genes involved in secretion are up-regulated during cyst formation, as are some trans-Golgi network-to-endosome trafficking genes. Furthermore, endocytic and general trafficking genes are up-regulated in the mature cyst, potentially preserved as mRNA in preparation for excystation. Two divergent dynamin-related proteins found in Entamoeba are predominantly expressed during cyst formation. Phylogenetic analyses indicate that they are paralogous to, but quite distinct from, classical dynamins found in human, suggesting that they may be potential drug targets to block encystation. The membrane-trafficking machinery is clearly regulated during encystation, providing an additional facet to understanding this crucial parasitic process.
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Affiliation(s)
- Emily Herman
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, T6G 2H7, Edmonton, Alberta, Canada
| | | | - Michael J Bottery
- Department of Biology, University of York, Heslington, York, YO10 5DD, UK
| | - Ronny van Aerle
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Centre for Environment, Fisheries, and Aquaculture Science (Cefas), Barrack Road, The Nothe, Weymouth, Dorset, DT4 8UB, UK
| | | | - Elisabet Caler
- J. Craig Venter Institute, 9714 Medical Center Drive, Rockville, MD, 20850, USA
- National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), 6701, Rockledge Drive, Room 9144, Bethesda, MD, 20892-7950, USA
| | - Joel B Dacks
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, T6G 2H7, Edmonton, Alberta, Canada.
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Inam A, Mittal S, Rajala MS, Avecilla F, Azam A. Synthesis and biological evaluation of 4-(2-(dimethylamino)ethoxy)benzohydrazide derivatives as inhibitors of Entamoeba histolyica. Eur J Med Chem 2016; 124:445-455. [DOI: 10.1016/j.ejmech.2016.08.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 07/20/2016] [Accepted: 08/11/2016] [Indexed: 12/20/2022]
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14
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Gurung P, Kanneganti TD. Immune responses against protozoan parasites: a focus on the emerging role of Nod-like receptors. Cell Mol Life Sci 2016; 73:3035-51. [PMID: 27032699 PMCID: PMC4956549 DOI: 10.1007/s00018-016-2212-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 03/11/2016] [Accepted: 03/24/2016] [Indexed: 02/07/2023]
Abstract
Nod-like receptors (NLRs) have gained attention in recent years because of the ability of some family members to assemble into a multimeric protein complex known as the inflammasome. The role of NLRs and the inflammasome in regulating innate immunity against bacterial pathogens has been well studied. However, recent studies show that NLRs and inflammasomes also play a role during infections caused by protozoan parasites, which pose a significant global health burden. Herein, we review the diseases caused by the most common protozoan parasites in the world and discuss the roles of NLRs and inflammasomes in host immunity against these parasites.
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Affiliation(s)
- Prajwal Gurung
- Department of Immunology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105-2794, USA
| | - Thirumala-Devi Kanneganti
- Department of Immunology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN, 38105-2794, USA.
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15
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Ávila EE, Salaiza N, Pulido J, Rodríguez MC, Díaz-Godínez C, Laclette JP, Becker I, Carrero JC. Entamoeba histolytica Trophozoites and Lipopeptidophosphoglycan Trigger Human Neutrophil Extracellular Traps. PLoS One 2016; 11:e0158979. [PMID: 27415627 PMCID: PMC4944907 DOI: 10.1371/journal.pone.0158979] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 06/24/2016] [Indexed: 12/17/2022] Open
Abstract
Neutrophil defense mechanisms include phagocytosis, degranulation and the formation of extracellular traps (NET). These networks of DNA are triggered by several immune and microbial factors, representing a defense strategy to prevent microbial spread by trapping/killing pathogens. This may be important against Entamoeba histolytica, since its large size hinders its phagocytosis. The aim of this study was to determine whether E. histolytica and their lipopeptidophosphoglycan (EhLPPG) induce the formation of NETs and the outcome of their interaction with the parasite. Our data show that live amoebae and EhLPPG, but not fixed trophozoites, induced NET formation in a time and dose dependent manner, starting at 5 min of co-incubation. Although immunofluorescence studies showed that the NETs contain cathelicidin LL-37 in close proximity to amoebae, the trophozoite growth was only affected when ethylene glycol tetra-acetic acid (EGTA) was present during contact with NETs, suggesting that the activity of enzymes requiring calcium, such as DNases, may be important for amoeba survival. In conclusion, E. histolytica trophozoites and EhLPPG induce in vitro formation of human NETs, which did not affect the parasite growth unless a chelating agent was present. These results suggest that NETs may be an important factor of the innate immune response during infection with E. histolytica.
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Affiliation(s)
- Eva E. Ávila
- Department of Biology, Division of Exact and Natural Sciences, Universidad de Guanajuato, 36050, Guanajuato, México
| | - Norma Salaiza
- Department of Experimental Medicine, Medical Faculty, Universidad Nacional Autónoma de México, 04510, México D.F., México
| | - Julieta Pulido
- Department of Biology, Division of Exact and Natural Sciences, Universidad de Guanajuato, 36050, Guanajuato, México
| | - Mayra C. Rodríguez
- Department of Biology, Division of Exact and Natural Sciences, Universidad de Guanajuato, 36050, Guanajuato, México
| | - César Díaz-Godínez
- Department of Immunology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510, México D.F., México
| | - Juan P. Laclette
- Department of Immunology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510, México D.F., México
| | - Ingeborg Becker
- Department of Experimental Medicine, Medical Faculty, Universidad Nacional Autónoma de México, 04510, México D.F., México
- * E-mail: (JCC); (IB)
| | - Julio C. Carrero
- Department of Immunology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, 04510, México D.F., México
- * E-mail: (JCC); (IB)
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Abstract
Entamoeba histolytica, the etiological agent of amebiasis, is a significant cause of pediatric diarrhea in South Asia and sub-Saharan Africa. The clinical outcome of an E. histolytica exposure varies enormously and can present as diarrhea, dysentery, or amebic liver abscess. Host and parasite factors likely contribute to the outcome of infection with the parasite, but do not explain the wide variation in presentation of disease. This suggests that other environmental factors affect disease. An emerging body of work suggests that the host intestinal bacterial microbiome may have a significant influence on the development and outcome of amebiasis.
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Affiliation(s)
- Stacey L. Burgess
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia Health System, Charlottesville, VA USA
| | - William A. Petri
- Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia Health System, Charlottesville, VA USA
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Marie C, Verkerke HP, Theodorescu D, Petri WA. A whole-genome RNAi screen uncovers a novel role for human potassium channels in cell killing by the parasite Entamoeba histolytica. Sci Rep 2015; 5:13613. [PMID: 26346926 PMCID: PMC4561901 DOI: 10.1038/srep13613] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 07/30/2015] [Indexed: 01/29/2023] Open
Abstract
The parasite Entamoeba histolytica kills human cells resulting in ulceration, inflammation and invasion of the colonic epithelium. We used the cytotoxic properties of ameba to select a genome-wide RNAi library to reveal novel host factors that control susceptibility to amebic killing. We identified 281 candidate susceptibility genes and bioinformatics analyses revealed that ion transporters were significantly enriched among susceptibility genes. Potassium (K+) channels were the most common transporter identified. Their importance was further supported by colon biopsy of humans with amebiasis that demonstrated suppressed K+ channel expression. Inhibition of human K+ channels by genetic silencing, pharmacologic inhibitors and with excess K+ protected diverse cell types from E. histolytica-induced death. Contact with E. histolytica parasites triggered K+ channel activation and K+ efflux by intestinal epithelial cells, which preceded cell killing. Specific inhibition of Ca2+-dependent K+ channels was highly effective in preventing amebic cytotoxicity in intestinal epithelial cells and macrophages. Blockade of K+ efflux also inhibited caspase-1 activation, IL-1β secretion and pyroptotic death in THP-1 macrophages. We concluded that K+ channels are host mediators of amebic cytotoxicity in multiple cells types and of inflammasome activation in macrophages.
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Affiliation(s)
- Chelsea Marie
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA
| | - Hans P Verkerke
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA
| | - Dan Theodorescu
- Department of Surgery, Department of Pharmacology, University of Colorado Comprehensive Cancer Center, University of Colorado, Denver, CO, USA
| | - William A Petri
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA
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Bone marrow dendritic cells from mice with an altered microbiota provide interleukin 17A-dependent protection against Entamoeba histolytica colitis. mBio 2014; 5:e01817. [PMID: 25370489 PMCID: PMC4222101 DOI: 10.1128/mbio.01817-14] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
There is an emerging paradigm that the human microbiome is central to many aspects of health and may have a role in preventing enteric infection. Entamoeba histolytica is a major cause of amebic diarrhea in developing countries. It colonizes the colon lumen in close proximity to the gut microbiota. Interestingly, not all individuals are equally susceptible to E. histolytica infection. Therefore, as the microbiota is highly variable within individuals, we sought to determine if a component of the microbiota could regulate susceptibility to infection. In studies utilizing a murine model, we demonstrated that colonization of the gut with the commensal Clostridia-related bacteria known as segmented filamentous bacteria (SFB) is protective during E. histolytica infection. SFB colonization in this model was associated with elevated cecal levels of interleukin 17A (IL-17A), dendritic cells, and neutrophils. Bone marrow-derived dendritic cells (BMDCs) from SFB-colonized mice had higher levels of IL-23 production in response to stimulation with trophozoites. Adoptive transfer of BMDCs from an SFB+ to an SFB− mouse was sufficient to provide protection against E. histolytica. IL-17A induction during BMDC transfer was necessary for this protection. This work demonstrates that intestinal colonization with a specific commensal bacterium can provide protection during amebiasis in a murine model. Most importantly, this work demonstrates that the microbiome can mediate protection against an enteric infection via extraintestinal effects on bone marrow-derived dendritic cells. Entamoeba histolytica is the causative agent of amebiasis, an infectious disease that contributes significantly to morbidity and mortality due to diarrhea in the developing world. We showed in a murine model that colonization with the commensal members of the Clostridia known as SFB provides protection against E. histolytica and that dendritic cells from SFB-colonized mice alone can recapitulate protection. Understanding interactions between enteropathogens, commensal intestinal bacteria, and the mucosal immune response, including dendritic cells, will help in the development of effective treatments for this disease and other infectious and inflammatory diseases. The demonstration of immune-mediated protection due to communication from the microbiome to the bone marrow represents an emerging field of study that will yield unique approaches to the development of these treatments.
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Diro E, Lynen L, Gebregziabiher B, Assefa A, Lakew W, Belew Z, Hailu A, Boelaert M, van Griensven J. Clinical aspects of paediatric visceral leishmaniasis in North-west Ethiopia. Trop Med Int Health 2014; 20:8-16. [PMID: 25329449 DOI: 10.1111/tmi.12407] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Visceral leishmaniasis (VL) in north-west Ethiopia is causing an overwhelming case load among adult migrant workers that masked the disease burden in children. This study describes the clinical profile and explores comorbidities in paediatric VL patients. METHODS A prospective study at two hospitals in this region (Gondar and Humera) was conducted in a year period, 2011-2012. The clinical manifestations and comorbidities such as malnutrition, intestinal parasitosis and vitamin D deficiency and HIV infection were assessed, and treatment outcomes noted. RESULTS A total of 122 children with VL were detected during the study period with median age of 8.5 years (IQR 5-12 years); 23% were under 5 years. Eighty-five (69.7%) cases were male. The clinical manifestations were similar to the adult patients. High rates of malnutrition, intestinal parasitosis (47.5%) and hypovitaminosis D (56.4%) were detected. The proportion of stunting and wasting was 63% and 22.2% in children aged under five years, and 50.5% and 75.9% in 5-year and older children, respectively, using WHO standard growth curves. Only one child had HIV infection. In 95% of the cases, sodium stibogluconate (20 mg/kg/day for 30 days) was used for treatment. The treatment success rate at end of therapy was 98.3%, but the definitive outcome at 6 months could not be determined because of a high loss to follow-up (80.2%). CONCLUSION While HIV co-infection was rare, malnutrition, intestinal parasitosis and vitamin D deficiency were frequent indicating the need for further research on their role in the pathophysiology. Meanwhile, systematic assessment and management of malnutrition and intestinal parasitosis in VL programmes is recommended.
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Affiliation(s)
- Ermias Diro
- University of Gondar, Gondar, Ethiopia; Institute of Tropical Medicine, Antwerp, Belgium
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The trend in distribution of Q223R mutation of leptin receptor gene in amoebic liver abscess patients from North India: a prospective study. BIOMED RESEARCH INTERNATIONAL 2014; 2014:847132. [PMID: 25114924 PMCID: PMC4121093 DOI: 10.1155/2014/847132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 05/06/2014] [Indexed: 02/06/2023]
Abstract
Host genetic susceptibility is an important risk factor in infectious diseases. We explored the distribution of Q223R mutation in leptin receptor gene of amoebic liver abscess (ALA) patients of North India. A total of 55 ALA samples along with 102 controls were subjected to PCR-RFLP analysis. The frequency of allele “G” (coding for arginine) was in general high in Indian population irrespective of the disease. Our results of Fisher exact test shows that heterozygous mutant (QQ versus QR, P = 0.049) and homozygous mutant (QQ versus RR, P = 0.004) were significantly associated with amoebic liver abscess when compared with homozygous wild (QQ).
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Abstract
Entamoeba histolytica is the third-leading cause of parasitic mortality globally. E. histolytica infection generally does not cause symptoms, but the parasite has potent pathogenic potential. The origins, benefits, and triggers of amoebic virulence are complex. Amoebic pathogenesis entails depletion of the host mucosal barrier, adherence to the colonic lumen, cytotoxicity, and invasion of the colonic epithelium. Parasite damage results in colitis and, in some cases, disseminated disease. Both host and parasite genotypes influence the development of disease, as do the regulatory responses they govern at the host-pathogen interface. Host environmental factors determine parasite transmission and shape the colonic microenvironment E. histolytica infects. Here we highlight research that illuminates novel links between host, parasite, and environmental factors in the regulation of E. histolytica virulence.
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Affiliation(s)
- Chelsea Marie
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia 22908; ,
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Kaput J, van Ommen B, Kremer B, Priami C, Monteiro JP, Morine M, Pepping F, Diaz Z, Fenech M, He Y, Albers R, Drevon CA, Evelo CT, Hancock REW, Ijsselmuiden C, Lumey LH, Minihane AM, Muller M, Murgia C, Radonjic M, Sobral B, West KP. Consensus statement understanding health and malnutrition through a systems approach: the ENOUGH program for early life. GENES & NUTRITION 2014; 9:378. [PMID: 24363221 PMCID: PMC3896628 DOI: 10.1007/s12263-013-0378-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 12/02/2013] [Indexed: 12/20/2022]
Abstract
Nutrition research, like most biomedical disciplines, adopted and often uses experimental approaches based on Beadle and Tatum's one gene-one polypeptide hypothesis, thereby reducing biological processes to single reactions or pathways. Systems thinking is needed to understand the complexity of health and disease processes requiring measurements of physiological processes, as well as environmental and social factors, which may alter the expression of genetic information. Analysis of physiological processes with omics technologies to assess systems' responses has only become available over the past decade and remains costly. Studies of environmental and social conditions known to alter health are often not connected to biomedical research. While these facts are widely accepted, developing and conducting comprehensive research programs for health are often beyond financial and human resources of single research groups. We propose a new research program on essential nutrients for optimal underpinning of growth and health (ENOUGH) that will use systems approaches with more comprehensive measurements and biostatistical analysis of the many biological and environmental factors that influence undernutrition. Creating a knowledge base for nutrition and health is a necessary first step toward developing solutions targeted to different populations in diverse social and physical environments for the two billion undernourished people in developed and developing economies.
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Affiliation(s)
- Jim Kaput
- Clinical Translation Unit, Nestle Institute of Health Sciences, Lausanne, Switzerland,
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Abstract
The parasite Entamoeba histolytica causes amebic colitis and systemic amebiasis. Among the known amebic factors contributing to pathogenesis are signaling pathways involving heterotrimeric and Ras superfamily G proteins. Here, we review the current knowledge of the roles of heterotrimeric G protein subunits, Ras, Rho and Rab GTPase families in E. histolytica pathogenesis, as well as of their downstream signaling effectors and nucleotide cycle regulators. Heterotrimeric G protein signaling likely modulates amebic motility and attachment to and killing of host cells, in part through activation of an RGS-RhoGEF (regulator of G protein signaling-Rho guanine nucleotide exchange factor) effector. Rho family GTPases, as well as RhoGEFs and Rho effectors (formins and p21-activated kinases) regulate the dynamic actin cytoskeleton of E. histolytica and associated pathogenesis-related cellular processes, such as migration, invasion, phagocytosis and evasion of the host immune response by surface receptor capping. A remarkably large family of 91 Rab GTPases has multiple roles in a complex amebic vesicular trafficking system required for phagocytosis and pinocytosis and secretion of known virulence factors, such as amebapores and cysteine proteases. Although much remains to be discovered, recent studies of G protein signaling in E. histolytica have enhanced our understanding of parasitic pathogenesis and have also highlighted possible targets for pharmacological manipulation.
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