1
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Hasan MM, Mattice EB, Teixeira JE, Jumani RS, Stebbins EE, Klopfer CE, Franco SE, Love MS, McNamara CW, Huston CD. Cryptosporidium life cycle small molecule probing implicates translational repression and an Apetala 2 transcription factor in macrogamont differentiation. PLoS Pathog 2024; 20:e1011906. [PMID: 38669269 DOI: 10.1371/journal.ppat.1011906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 04/08/2024] [Indexed: 04/28/2024] Open
Abstract
The apicomplexan parasite Cryptosporidium is a leading cause of childhood diarrhea in developing countries. Current treatment options are inadequate and multiple preclinical compounds are being actively pursued as potential drugs for cryptosporidiosis. Unlike most apicomplexans, Cryptosporidium spp. sequentially replicate asexually and then sexually within a single host to complete their lifecycles. Anti-cryptosporidial compounds are generally identified or tested through in vitro phenotypic assays that only assess the asexual stages. Therefore, compounds that specifically target the sexual stages remain unexplored. In this study, we leveraged the ReFRAME drug repurposing library against a newly devised multi-readout imaging assay to identify small-molecule compounds that modulate macrogamont differentiation and maturation. RNA-seq studies confirmed selective modulation of macrogamont differentiation for 10 identified compounds (9 inhibitors and 1 accelerator). The collective transcriptomic profiles of these compounds indicates that translational repression accompanies Cryptosporidium sexual differentiation, which we validated experimentally. Additionally, cross comparison of the RNA-seq data with promoter sequence analysis for stage-specific genes converged on a key role for an Apetala 2 (AP2) transcription factor (cgd2_3490) in differentiation into macrogamonts. Finally, drug annotation for the ReFRAME hits indicates that an elevated supply of energy equivalence in the host cell is critical for macrogamont formation.
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Affiliation(s)
- Muhammad M Hasan
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
- Cell, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, United States of America
| | - Ethan B Mattice
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
- Cell, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, United States of America
| | - José E Teixeira
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Rajiv S Jumani
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
- Cell, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, United States of America
| | - Erin E Stebbins
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Connor E Klopfer
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Sebastian E Franco
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Melissa S Love
- Calibr at Scripps Research, San Diego, California, United States of America
| | - Case W McNamara
- Calibr at Scripps Research, San Diego, California, United States of America
| | - Christopher D Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
- Cell, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, United States of America
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2
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Korwin-Mihavics BR, Dews EA, di Genova BM, Huston CD. Organoid-based in vitro systems to model Cryptosporidium parvum infection in 2D and 3D. bioRxiv 2023:2023.09.29.560165. [PMID: 37808810 PMCID: PMC10557739 DOI: 10.1101/2023.09.29.560165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Typical cancer cell-based culture systems cannot support the full life cycle of Cryptosporidium parvum, despite its monoxenous life cycle which is completed in the small intestine of a single host. There is a block to fertilization and zygote formation in vitro. In this paper, we adapted a 2D organoid derived monolayer system and a 3D inverted enteroid system for use in C. parvum culture. 3D inverted enteroids were successfully infected by C. parvum without the need for microinjection and supported subculture of C. parvum. Using the 2D organoid derived monolayer (ODM) system, the infection can be maintained for at least 3 weeks with new oocyst production throughout. Fertilization was confirmed based on successful mating of two strains of C. parvum. We demonstrated that the apparent block to fertilization in typical cell culture is overcome using ODMs.
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Affiliation(s)
- Bethany R Korwin-Mihavics
- Department of Medicine, University of Vermont, Burlington, Vermont, USA
- Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
- Cellular, Molecular, and Biomedical Sciences, University of Vermont, Burlington, Vermont, USA
| | - Emmett A Dews
- Department of Medicine, University of Vermont, Burlington, Vermont, USA
- Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
| | - Bruno Martorelli di Genova
- Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
- Cellular, Molecular, and Biomedical Sciences, University of Vermont, Burlington, Vermont, USA
| | - Christopher D Huston
- Department of Medicine, University of Vermont, Burlington, Vermont, USA
- Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
- Cellular, Molecular, and Biomedical Sciences, University of Vermont, Burlington, Vermont, USA
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3
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Schubert TJ, Oboh E, Peek H, Philo E, Teixeira JE, Stebbins EE, Miller P, Oliva J, Sverdrup FM, Griggs DW, Huston CD, Meyers MJ. Structure-Activity Relationship Studies of the Aryl Acetamide Triazolopyridazines against Cryptosporidium Reveals Remarkable Role of Fluorine. J Med Chem 2023; 66:7834-7848. [PMID: 37267631 DOI: 10.1021/acs.jmedchem.3c00110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Our previous work identified compound 1 (SLU-2633) as a potent lead compound toward the identification of a novel treatment for cryptosporidiosis, caused by the parasite Cryptosporidium (EC50 = 0.17 μM). While this compound is potent and orally efficacious, the mechanism of action and biological target(s) of this series are currently unknown. In this study, we synthesized 70 compounds to develop phenotypic structure-activity relationships around the aryl "tail" group. In this process, we found that 2-substituted compounds are inactive, confirmed that electron withdrawing groups are preferred over electron donating groups, and that fluorine plays a remarkable role in the potency of these compounds. The most potent compound resulting from this work is SLU-10482 (52, EC50 = 0.07 μΜ), which was found to be orally efficacious with an ED90 < 5 mg/kg BID in a Cryptosporidium-infection mouse model, superior to SLU-2633.
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Affiliation(s)
- Tanner J Schubert
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
| | - Edmund Oboh
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
| | - Hannah Peek
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
| | - Emily Philo
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
| | - José E Teixeira
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont 05401, United States
| | - Erin E Stebbins
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont 05401, United States
| | - Peter Miller
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont 05401, United States
| | - Jonathan Oliva
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104, United States
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, St. Louis, Missouri 63103, United States
| | - Francis M Sverdrup
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104, United States
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, St. Louis, Missouri 63103, United States
| | - David W Griggs
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, St. Louis, Missouri 63103, United States
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104, United States
| | - Christopher D Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont 05401, United States
| | - Marvin J Meyers
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
- Institute for Drug and Biotherapeutic Innovation, Saint Louis University, St. Louis, Missouri 63103, United States
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4
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Oboh E, Teixeira JE, Schubert TJ, Maribona AS, Denman BN, Patel R, Huston CD, Meyers MJ. Structure-Activity relationships of replacements for the triazolopyridazine of Anti-Cryptosporidium lead SLU-2633. Bioorg Med Chem 2023; 86:117295. [PMID: 37148788 PMCID: PMC10201403 DOI: 10.1016/j.bmc.2023.117295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 04/18/2023] [Accepted: 04/21/2023] [Indexed: 05/08/2023]
Abstract
Cryptosporidiosis is a diarrheal disease particularly harmful to children and immunocompromised people. Infection is caused by the parasite Cryptosporidium and leads to dehydration, malnutrition, and death in severe cases. Nitazoxanide is the only FDA approved drug but is only modestly effective in children and ineffective in immunocompromised patients. To address this unmet medical need, we previously identified triazolopyridazine SLU-2633 as potent against Cryptosporidium parvum, with an EC50 of 0.17 µM. In the present study, we develop structure-activity relationships (SAR) for the replacement of the triazolopyridazine head group by exploring different heteroaryl groups with the aim of maintaining potency while reducing affinity for the hERG channel. 64 new analogs of SLU-2633 were synthesized and assayed for potency versus C. parvum. The most potent compound, 7,8-dihydro-[1,2,4]triazolo[4,3-b]pyridazine 17a, was found to have a Cp EC50 of 1.2 µM, 7-fold less potent than SLU-2633 but has an improved lipophilic efficiency (LipE) score. 17a was found to decrease inhibition in an hERG patch-clamp assay by about two-fold relative to SLU-2633 at 10 µM despite having similar inhibition in a [3H]-dofetilide competitive binding assay. While most other heterocycles were significantly less potent than the lead, some analogs such as azabenzothiazole 31b, have promising potency in the low micromolar range, similar to the drug nitazoxanide, and represent potential new leads for optimization. Overall, this work highlights the important role of the terminal heterocyclic head group and represents a significant extension of the understanding of the SAR for this class of anti-Cryptosporidium compounds.
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Affiliation(s)
- Edmund Oboh
- Department of Chemistry, School of Science and Engineering, Saint Louis University, Saint Louis, MO 63103, United States
| | - José E Teixeira
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT 05401, United States
| | - Tanner J Schubert
- Department of Chemistry, School of Science and Engineering, Saint Louis University, Saint Louis, MO 63103, United States
| | - Adriana S Maribona
- Department of Chemistry, School of Science and Engineering, Saint Louis University, Saint Louis, MO 63103, United States
| | - Brylon N Denman
- Department of Chemistry, School of Science and Engineering, Saint Louis University, Saint Louis, MO 63103, United States
| | - Radhika Patel
- Department of Chemistry, School of Science and Engineering, Saint Louis University, Saint Louis, MO 63103, United States
| | - Christopher D Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT 05401, United States.
| | - Marvin J Meyers
- Department of Chemistry, School of Science and Engineering, Saint Louis University, Saint Louis, MO 63103, United States; Institute for Drug and Biotherapeutic Innovation, Saint Louis University, St. Louis, MO 63103, United States.
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5
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Oboh E, Schubert TJ, Teixeira JE, Stebbins EE, Miller P, Philo E, Thakellapalli H, Campbell SD, Griggs DW, Huston CD, Meyers MJ. Optimization of the Urea Linker of Triazolopyridazine MMV665917 Results in a New Anticryptosporidial Lead with Improved Potency and Predicted hERG Safety Margin. J Med Chem 2021; 64:11729-11745. [PMID: 34342443 DOI: 10.1021/acs.jmedchem.1c01136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cryptosporidiosis is caused by infection of the small intestine by Cryptosporidium parasites, resulting in severe diarrhea, dehydration, malabsorption, and potentially death. The only FDA-approved therapeutic is only partially effective in young children and ineffective for immunocompromised patients. Triazolopyridazine MMV665917 is a previously reported anti-Cryptosporidium screening hit with in vivo efficacy but suffers from modest inhibition of the hERG ion channel, which could portend cardiotoxicity. Herein, we describe our initial development of structure-activity relationships of this novel lead series with a particular focus on optimization of the piperazine-urea linker. We have discovered that piperazine-acetamide is a superior linker resulting in identification of SLU-2633, which has an EC50 of 0.17 μM, an improved projected margin versus hERG, prolonged pharmacokinetic exposure in small intestine, and oral efficacy in vivo with minimal systemic exposure. SLU-2633 represents a significant advancement toward the identification of a new effective and safe treatment for cryptosporidiosis.
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Affiliation(s)
- Edmund Oboh
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
| | - Tanner J Schubert
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
| | - Jose E Teixeira
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont 05401, United States
| | - Erin E Stebbins
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont 05401, United States
| | - Peter Miller
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont 05401, United States
| | - Emily Philo
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
| | - Haresh Thakellapalli
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States
| | - Scott D Campbell
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104, United States
| | - David W Griggs
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, Saint Louis, Missouri 63104, United States.,Institute for Drug and Biotherapeutic Innovation, Saint Louis University, St. Louis, Missouri 63103, United States
| | - Christopher D Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont 05401, United States
| | - Marvin J Meyers
- Department of Chemistry, Saint Louis University, Saint Louis, Missouri 63103, United States.,Institute for Drug and Biotherapeutic Innovation, Saint Louis University, St. Louis, Missouri 63103, United States
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6
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Huston CD. The Clofazimine for Treatment of Cryptosporidiosis in HIV-Infected Adults (CRYPTOFAZ) and Lessons Learned for Anticryptosporidial Drug Development. Clin Infect Dis 2021; 73:192-194. [PMID: 32277815 PMCID: PMC8427724 DOI: 10.1093/cid/ciaa425] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Indexed: 11/12/2022] Open
Affiliation(s)
- Christopher D Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
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7
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Vinayak S, Jumani RS, Miller P, Hasan MM, McLeod BI, Tandel J, Stebbins EE, Teixeira JE, Borrel J, Gonse A, Zhang M, Yu X, Wernimont A, Walpole C, Eckley S, Love MS, McNamara CW, Sharma M, Sharma A, Scherer CA, Kato N, Schreiber SL, Melillo B, Striepen B, Huston CD, Comer E. Bicyclic azetidines kill the diarrheal pathogen Cryptosporidium in mice by inhibiting parasite phenylalanyl-tRNA synthetase. Sci Transl Med 2021; 12:12/563/eaba8412. [PMID: 32998973 DOI: 10.1126/scitranslmed.aba8412] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 09/11/2020] [Indexed: 12/21/2022]
Abstract
Cryptosporidium is a protozoan parasite and a leading cause of diarrheal disease and mortality in young children. Currently, there are no fully effective treatments available to cure infection with this diarrheal pathogen. In this study, we report a broad drug repositioning effort that led to the identification of bicyclic azetidines as a new anticryptosporidial series. Members of this series blocked growth in in vitro culture of three Cryptosporidium parvum isolates with EC50 's in 1% serum of <0.4 to 96 nM, had comparable potencies against Cryptosporidium hominis and C. parvum, and was effective in three of four highly susceptible immunosuppressed mice with once-daily dosing administered for 4 days beginning 2 weeks after infection. Comprehensive genetic, biochemical, and chemical studies demonstrated inhibition of C. parvum phenylalanyl-tRNA synthetase (CpPheRS) as the mode of action of this new lead series. Introduction of mutations directly into the C. parvum pheRS gene by CRISPR-Cas9 genome editing resulted in parasites showing high degrees of compound resistance. In vitro, bicyclic azetidines potently inhibited the aminoacylation activity of recombinant ChPheRS. Medicinal chemistry optimization led to the identification of an optimal pharmacokinetic/pharmacodynamic profile for this series. Collectively, these data demonstrate that bicyclic azetidines are a promising series for anticryptosporidial drug development and establish a broad framework to enable target-based drug discovery for this infectious disease.
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Affiliation(s)
- Sumiti Vinayak
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
| | - Rajiv S Jumani
- Cellular, Molecular and Biomedical Sciences Graduate Program, University of Vermont, Burlington, VT 05405, USA
| | - Peter Miller
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA
| | - Muhammad M Hasan
- Cellular, Molecular and Biomedical Sciences Graduate Program, University of Vermont, Burlington, VT 05405, USA
| | - Briana I McLeod
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jayesh Tandel
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erin E Stebbins
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA
| | - Jose E Teixeira
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA
| | - Julien Borrel
- Chemical Biology and Therapeutics Science Program, Broad Institute, Cambridge, MA 02142, USA
| | - Arthur Gonse
- Chemical Biology and Therapeutics Science Program, Broad Institute, Cambridge, MA 02142, USA
| | - Mingliang Zhang
- International Discovery Service Unit, WuXi AppTec (Tianjin) Co. Ltd., Tianjin 300457, P.R. China
| | - Xianshui Yu
- International Discovery Service Unit, WuXi AppTec (Tianjin) Co. Ltd., Tianjin 300457, P.R. China
| | - Amy Wernimont
- Structural Genomics Consortium, MaRS Building, South Tower, 101 College Street, Suite 700, Toronto, Ontario M5G 1L7, Canada
| | - Chris Walpole
- Structural Genomics Consortium, MaRS Building, South Tower, 101 College Street, Suite 700, Toronto, Ontario M5G 1L7, Canada
| | | | - Melissa S Love
- Calibr, a division of The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Case W McNamara
- Calibr, a division of The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Manmohan Sharma
- Structural Parasitology, Molecular Medicine Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Road, New Delhi 110070, India
| | - Amit Sharma
- Structural Parasitology, Molecular Medicine Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Road, New Delhi 110070, India
| | - Christina A Scherer
- Chemical Biology and Therapeutics Science Program, Broad Institute, Cambridge, MA 02142, USA
| | - Nobutaka Kato
- Chemical Biology and Therapeutics Science Program, Broad Institute, Cambridge, MA 02142, USA
| | - Stuart L Schreiber
- Chemical Biology and Therapeutics Science Program, Broad Institute, Cambridge, MA 02142, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Bruno Melillo
- Chemical Biology and Therapeutics Science Program, Broad Institute, Cambridge, MA 02142, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.,Department of Chemistry, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Boris Striepen
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Christopher D Huston
- Department of Medicine, Larner College of Medicine, University of Vermont, Burlington, VT 05405, USA.
| | - Eamon Comer
- Chemical Biology and Therapeutics Science Program, Broad Institute, Cambridge, MA 02142, USA.
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8
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Ghatage P, Pierce KK, Wojewoda C, Mendelson N, Wilcock J, Nesbit R, Huston CD, Whitman TJ. A Veterinarian From Vermont Presenting With a Painful Right Index Finger Following a Needlestick Injury That Occurred While Caring for a Dog. Clin Infect Dis 2021; 71:1577-1579. [PMID: 32918550 DOI: 10.1093/cid/ciaa086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Prateek Ghatage
- Division of Infectious Diseases, Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - Kristen K Pierce
- Division of Infectious Diseases, Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - Christina Wojewoda
- Department of Pathology and Laboratory Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - Nicole Mendelson
- Department of Pathology and Laboratory Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - Jonathan Wilcock
- Department of Pathology and Laboratory Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - Robert Nesbit
- Division of Plastic Surgery, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - Christopher D Huston
- Division of Infectious Diseases, Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - Timothy J Whitman
- Division of Infectious Diseases, Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
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9
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Whitman TJ, Noyes CD, Hale AJ, Singh D, DeVoe SG, Repp AB, Pierce KK, Polish LB, Kirkpatrick BD, Dejace J, Smith LM, Lahey T, Huston CD, Catoe LJ, Ghatage P, Bullis S, Alston WK. Impact and costs of a hepatitis C virus screening programme for adults hospitalised at an academic medical centre. BMJ Open Qual 2021; 10:bmjoq-2020-001248. [PMID: 33593729 PMCID: PMC7888362 DOI: 10.1136/bmjoq-2020-001248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/26/2021] [Accepted: 02/04/2021] [Indexed: 11/16/2022] Open
Affiliation(s)
- Timothy J Whitman
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Cindy D Noyes
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Andrew J Hale
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Devika Singh
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Stephen G DeVoe
- Department of Medicine Quality Program, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Allen B Repp
- Department of Medicine Quality Program, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Kristen K Pierce
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Louis B Polish
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Beth D Kirkpatrick
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Jean Dejace
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Lindsay M Smith
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Tim Lahey
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Christopher D Huston
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Laura J Catoe
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Prateek Ghatage
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - Sean Bullis
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
| | - W Kemper Alston
- Division of Infectious Diseases, Department of Medicine, The Robert Larner, MD College of Medicine at the University of Vermont, Burlington, Vermont, USA
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10
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Bruce EA, Huang ML, Perchetti GA, Tighe S, Laaguiby P, Hoffman JJ, Gerrard DL, Nalla AK, Wei Y, Greninger AL, Diehl SA, Shirley DJ, Leonard DGB, Huston CD, Kirkpatrick BD, Dragon JA, Crothers JW, Jerome KR, Botten JW. Direct RT-qPCR detection of SARS-CoV-2 RNA from patient nasopharyngeal swabs without an RNA extraction step. PLoS Biol 2020; 18:e3000896. [PMID: 33006983 PMCID: PMC7556528 DOI: 10.1371/journal.pbio.3000896] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/14/2020] [Accepted: 09/10/2020] [Indexed: 11/24/2022] Open
Abstract
The ongoing COVID-19 pandemic has created an unprecedented need for rapid diagnostic testing. The World Health Organization (WHO) recommends a standard assay that includes an RNA extraction step from a nasopharyngeal (NP) swab followed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to detect the purified SARS-CoV-2 RNA. The current global shortage of RNA extraction kits has caused a severe bottleneck to COVID-19 testing. The goal of this study was to determine whether SARS-CoV-2 RNA could be detected from NP samples via a direct RT-qPCR assay that omits the RNA extraction step altogether. The direct RT-qPCR approach correctly identified 92% of a reference set of blinded NP samples (n = 155) demonstrated to be positive for SARS-CoV-2 RNA by traditional clinical diagnostic RT-qPCR that included an RNA extraction. Importantly, the direct method had sufficient sensitivity to reliably detect those patients with viral loads that correlate with the presence of infectious virus. Thus, this strategy has the potential to ease supply choke points to substantially expand COVID-19 testing and screening capacity and should be applicable throughout the world.
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Affiliation(s)
- Emily A. Bruce
- Division of Immunobiology, Department of Medicine, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
| | - Meei-Li Huang
- Virology Division, Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Garrett A. Perchetti
- Virology Division, Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Scott Tighe
- Vermont Integrative Genomics Resource, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
| | - Pheobe Laaguiby
- Vermont Integrative Genomics Resource, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
| | - Jessica J. Hoffman
- Vermont Integrative Genomics Resource, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
| | - Diana L. Gerrard
- Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington, Vermont, United States of America
| | - Arun K. Nalla
- Virology Division, Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Yulun Wei
- Virology Division, Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Alexander L. Greninger
- Virology Division, Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Sean A. Diehl
- Department of Microbiology and Molecular Genetics, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
- Vaccine Testing Center, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
| | - David J. Shirley
- Data Science Division, IXIS, Burlington, Vermont, United States of America
| | - Debra G. B. Leonard
- Department of Pathology and Laboratory Medicine, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
- University of Vermont Health Network, Burlington, Vermont, United States of America
| | - Christopher D. Huston
- Department of Microbiology and Molecular Genetics, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
- Division of Infectious Disease, Department of Medicine, University of Vermont Medical Center, Burlington, Vermont, United States of America
| | - Beth D. Kirkpatrick
- Department of Microbiology and Molecular Genetics, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
- Vaccine Testing Center, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
- Division of Infectious Disease, Department of Medicine, University of Vermont Medical Center, Burlington, Vermont, United States of America
| | - Julie A. Dragon
- Vermont Integrative Genomics Resource, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
- Department of Microbiology and Molecular Genetics, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
| | - Jessica W. Crothers
- Department of Pathology and Laboratory Medicine, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
- University of Vermont Health Network, Burlington, Vermont, United States of America
| | - Keith R. Jerome
- Virology Division, Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Jason W. Botten
- Division of Immunobiology, Department of Medicine, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
- Department of Microbiology and Molecular Genetics, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
- Vaccine Testing Center, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, Vermont, United States of America
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11
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Hasan MM, Teixeira JE, Lam YW, Huston CD. Coactosin Phosphorylation Controls Entamoeba histolytica Cell Membrane Protrusions and Cell Motility. mBio 2020; 11:e00660-20. [PMID: 32753489 PMCID: PMC7407079 DOI: 10.1128/mbio.00660-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 06/30/2020] [Indexed: 12/12/2022] Open
Abstract
Invasion of the colon wall by Entamoeba histolytica during amoebic dysentery entails migration of trophozoites through tissue layers that are rich in extracellular matrix. Transcriptional silencing of the E. histolytica surface metalloprotease EhMSP-1 produces hyperadherent less-motile trophozoites that are deficient in forming invadosomes. Reversible protein phosphorylation is often implicated in regulation of cell motility and invadosome formation. To identify such intermediaries of the EhMSP-1-silenced phenotype, here we compared the phosphoproteomes of EhMSP-1-silenced and vector control trophozoites by using quantitative tandem mass spectrometry-based proteomics. Six proteins were found to be differentially phosphorylated in EhMSP-1-silenced and control cells, including EhCoactosin, a member of the ADF/cofilin family of actin-binding proteins, which was more frequently phosphorylated at serine 147. Regulated overexpression of wild-type, phosphomimetic, and nonphosphorylatable EhCoactosin variants was used to test if phosphorylation functions in control of E. histolytica actin dynamics. Each of the overexpressed proteins colocalized with F-actin during E. histolytica phagocytosis. Nonetheless, trophozoites overexpressing an EhCoactosin phosphomimetic mutant formed more and poorly coordinated cell membrane protrusions compared to those in control or cells expressing a nonphosphorylatable mutant, while trophozoites overexpressing nonphosphorylatable EhCoactosin were significantly more motile within a model of mammalian extracellular matrix. Therefore, although EhCoactosin's actin-binding ability appeared unaffected by phosphorylation, EhCoactosin phosphorylation helps to regulate amoebic motility. These data help to understand the mechanisms underlying altered adherence and motility in EhMSP-1-silenced trophozoites and lay the groundwork for identifying kinases and phosphatases critical for control of amoebic invasiveness.IMPORTANCE Invasive amoebiasis, caused by the intestinal parasite Entamoeba histolytica, causes life-threatening diarrhea and liver abscesses, but, for unknown reasons, only approximately 10% of E. histolytica infections become symptomatic. A key requirement of invasion is the ability of the parasite to migrate through tissue layers. Here, we systematically looked for differences in protein phosphorylation between control parasites and a previously identified hyperadherent E. histolytica cell line that has reduced motility. We identified EhCoactosin, an actin-binding protein not previously known to be phosphoregulated, as one of the differentially phosphorylated proteins in E. histolytica and demonstrated that EhCoactosin phosphorylation functions in control of cell membrane dynamics and amoebic motility. This and the additional differentially phosphorylated proteins reported lay the groundwork for identifying kinases and phosphatases that regulate tissue invasiveness.
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Affiliation(s)
- Muhammad M Hasan
- Department of Medicine, University of Vermont, Larner College of Medicine, Burlington, Vermont, USA
- Cellular, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, USA
| | - José E Teixeira
- Department of Medicine, University of Vermont, Larner College of Medicine, Burlington, Vermont, USA
| | - Ying-Wai Lam
- Proteomics Facility, Vermont Genetics Network, University of Vermont, Burlington, Vermont, USA
- Department of Biology, University of Vermont, Burlington, Vermont, USA
| | - Christopher D Huston
- Department of Medicine, University of Vermont, Larner College of Medicine, Burlington, Vermont, USA
- Cellular, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, USA
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12
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Affiliation(s)
| | - Christopher D. Huston
- University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
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13
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Bruce EA, Huang ML, Perchetti GA, Tighe S, Laaguiby P, Hoffman JJ, Gerrard DL, Nalla AK, Wei Y, Greninger AL, Diehl SA, Shirley DJ, Leonard DGB, Huston CD, Kirkpatrick BD, Dragon JA, Crothers JW, Jerome KR, Botten JW. DIRECT RT-qPCR DETECTION OF SARS-CoV-2 RNA FROM PATIENT NASOPHARYNGEAL SWABS WITHOUT AN RNA EXTRACTION STEP. bioRxiv 2020:2020.03.20.001008. [PMID: 32511328 PMCID: PMC7239058 DOI: 10.1101/2020.03.20.001008] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The ongoing COVID-19 pandemic has caused an unprecedented need for rapid diagnostic testing. The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) recommend a standard assay that includes an RNA extraction step from a nasopharyngeal (NP) swab followed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to detect the purified SARS-CoV-2 RNA. The current global shortage of RNA extraction kits has caused a severe bottleneck to COVID-19 testing. We hypothesized that SARS-CoV-2 RNA could be detected from NP samples via a direct RT-qPCR assay that omits the RNA extraction step altogether, and tested this hypothesis on a series of blinded clinical samples. The direct RT-qPCR approach correctly identified 92% of NP samples (n = 155) demonstrated to be positive for SARS-CoV-2 RNA by traditional clinical diagnostic RT-qPCR that included an RNA extraction. Thus, direct RT-qPCR could be a front-line approach to identify the substantial majority of COVID-19 patients, reserving a repeat test with RNA extraction for those individuals with high suspicion of infection but an initial negative result. This strategy would drastically ease supply chokepoints of COVID-19 testing and should be applicable throughout the world.
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Affiliation(s)
- Emily A. Bruce
- Department of Medicine, Division of Immunobiology, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
| | - Meei-Li Huang
- Virology Division, Department of Laboratory Medicine, University of Washington, Seattle WA 98195, USA
| | - Garrett A. Perchetti
- Virology Division, Department of Laboratory Medicine, University of Washington, Seattle WA 98195, USA
| | - Scott Tighe
- Vermont Integrative Genomics Resource, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
| | - Pheobe Laaguiby
- Vermont Integrative Genomics Resource, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
| | - Jessica J. Hoffman
- Vermont Integrative Genomics Resource, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
| | - Diana L. Gerrard
- Department of Pathology and Laboratory Medicine, University of Vermont Medical Center, Burlington VT, 05401, USA
| | - Arun K. Nalla
- Virology Division, Department of Laboratory Medicine, University of Washington, Seattle WA 98195, USA
| | - Yulun Wei
- Virology Division, Department of Laboratory Medicine, University of Washington, Seattle WA 98195, USA
| | - Alexander L. Greninger
- Virology Division, Department of Laboratory Medicine, University of Washington, Seattle WA 98195, USA
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle WA 98109, USA
| | - Sean A. Diehl
- Department of Microbiology and Molecular Genetics, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
- Vaccine Testing Center, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, VT, 05405 USA
| | | | - Debra G. B. Leonard
- Department of Pathology and Laboratory Medicine, Robert Larner, M.D. College of Medicine, University of Vermont and the University of Vermont Health Network, Burlington VT, 05405, USA
| | - Christopher D. Huston
- Department of Microbiology and Molecular Genetics, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
- Department of Medicine, Division of Infectious Disease, University of Vermont Medical Center, Burlington VT, 05401, USA
| | - Beth D. Kirkpatrick
- Department of Microbiology and Molecular Genetics, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
- Vaccine Testing Center, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, VT, 05405 USA
- Department of Medicine, Division of Infectious Disease, University of Vermont Medical Center, Burlington VT, 05401, USA
| | - Julie A. Dragon
- Vermont Integrative Genomics Resource, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
- Department of Microbiology and Molecular Genetics, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
| | - Jessica W. Crothers
- Department of Pathology and Laboratory Medicine, Robert Larner, M.D. College of Medicine, University of Vermont and the University of Vermont Health Network, Burlington VT, 05405, USA
| | - Keith R. Jerome
- Virology Division, Department of Laboratory Medicine, University of Washington, Seattle WA 98195, USA
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle WA 98109, USA
| | - Jason W. Botten
- Department of Medicine, Division of Immunobiology, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
- Department of Microbiology and Molecular Genetics, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington VT, 05405, USA
- Vaccine Testing Center, Robert Larner, M.D. College of Medicine, University of Vermont, Burlington, VT, 05405 USA
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14
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Ehrenkaufer G, Li P, Stebbins EE, Kangussu-Marcolino MM, Debnath A, White CV, Moser MS, DeRisi J, Gisselberg J, Yeh E, Wang SC, Company AH, Monti L, Caffrey CR, Huston CD, Wang B, Singh U. Identification of anisomycin, prodigiosin and obatoclax as compounds with broad-spectrum anti-parasitic activity. PLoS Negl Trop Dis 2020; 14:e0008150. [PMID: 32196500 PMCID: PMC7112225 DOI: 10.1371/journal.pntd.0008150] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/01/2020] [Accepted: 02/18/2020] [Indexed: 01/20/2023] Open
Abstract
Parasitic infections are a major source of human suffering, mortality, and economic loss, but drug development for these diseases has been stymied by the significant expense involved in bringing a drug though clinical trials and to market. Identification of single compounds active against multiple parasitic pathogens could improve the economic incentives for drug development as well as simplifying treatment regimens. We recently performed a screen of repurposed compounds against the protozoan parasite Entamoeba histolytica, causative agent of amebic dysentery, and identified four compounds (anisomycin, prodigiosin, obatoclax and nithiamide) with low micromolar potency and drug-like properties. Here, we extend our investigation of these drugs. We assayed the speed of killing of E. histolytica trophozoites and found that all four have more rapid action than the current drug of choice, metronidazole. We further established a multi-institute collaboration to determine whether these compounds may have efficacy against other parasites and opportunistic pathogens. We found that anisomycin, prodigiosin and obatoclax all have broad-spectrum antiparasitic activity in vitro, including activity against schistosomes, T. brucei, and apicomplexan parasites. In several cases, the drugs were found to have significant improvements over existing drugs. For instance, both obatoclax and prodigiosin were more efficacious at inhibiting the juvenile form of Schistosoma than the current standard of care, praziquantel. Additionally, low micromolar potencies were observed against pathogenic free-living amebae (Naegleria fowleri, Balamuthia mandrillaris and Acanthamoeba castellanii), which cause CNS infection and for which there are currently no reliable treatments. These results, combined with the previous human use of three of these drugs (obatoclax, anisomycin and nithiamide), support the idea that these compounds could serve as the basis for the development of broad-spectrum anti-parasitic drugs.
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Affiliation(s)
- Gretchen Ehrenkaufer
- Division of Infectious Diseases, Department of Internal Medicine, Stanford University, Stanford, CA, United States of America
| | - Pengyang Li
- Department of Bioengineering, Stanford University, Stanford, CA, United States of America
| | - Erin E. Stebbins
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Monica M. Kangussu-Marcolino
- Division of Infectious Diseases, Department of Internal Medicine, Stanford University, Stanford, CA, United States of America
| | - Anjan Debnath
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Corin V. White
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Matthew S. Moser
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Joseph DeRisi
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Jolyn Gisselberg
- Department of Biochemistry, Stanford Medical School, Stanford University, Stanford, CA, United States of America
| | - Ellen Yeh
- Department of Biochemistry, Stanford Medical School, Stanford University, Stanford, CA, United States of America
- Department of Microbiology and Immunology, Stanford University, Stanford, CA, United States of America
- Department of Pathology, Stanford University, Stanford, CA, United States of America
| | - Steven C. Wang
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Ana Hervella Company
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Ludovica Monti
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Conor R. Caffrey
- Center for Discovery and Innovation in Parasitic Diseases, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Christopher D. Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, United States of America
| | - Bo Wang
- Department of Bioengineering, Stanford University, Stanford, CA, United States of America
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, United States of America
| | - Upinder Singh
- Division of Infectious Diseases, Department of Internal Medicine, Stanford University, Stanford, CA, United States of America
- Department of Microbiology and Immunology, Stanford University, Stanford, CA, United States of America
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15
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Lee S, Ginese M, Girouard D, Beamer G, Huston CD, Osbourn D, Griggs DW, Tzipori S. Piperazine-Derivative MMV665917: An Effective Drug in the Diarrheic Piglet Model of Cryptosporidium hominis. J Infect Dis 2020; 220:285-293. [PMID: 30893435 DOI: 10.1093/infdis/jiz105] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 03/18/2019] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Cryptosporidiosis, an enteric protozoon, causes substantial morbidity and mortality associated with diarrhea in children <2 years old in low- to middle-income countries. There is no vaccine and treatments are inadequate. A piperazine-based compound, MMV665917, has in vitro and in vivo efficacy against Cryptosporidium parvum. In this study, we evaluated the efficacy of MMV665917 in gnotobiotic piglets experimentally infected with Cryptosporidium hominis, the species responsible for >75% of diarrhea reported in these children. METHODS Gnotobiotic piglets were orally challenged with C hominis oocysts, and oral treatment with MMV665917 was commenced 3 days after challenge. Oocyst excretion and diarrhea severity were observed daily, and mucosal colonization and lesions were recorded after necropsy. RESULTS MMV665917 significantly reduced fecal oocyst excretion, parasite colonization and damage to the intestinal mucosa, and peak diarrheal symptoms, compared with infected untreated controls. A dose of 20 mg/kg twice daily for 7 days was more effective than 10 mg/kg. There were no signs of organ toxicity at either dose, but 20 mg/kg was associated with slightly elevated blood cholesterol and monocytes at euthanasia. CONCLUSIONS These results demonstrate the effectiveness of this drug against C hominis. Piperazine-derivative MMV665917 may potentially be used to treat human cryptosporidiosis; however, further investigations are required.
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Affiliation(s)
- Sangun Lee
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts
| | - Melanie Ginese
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts
| | - Don Girouard
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts
| | - Gillian Beamer
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts
| | - Christopher D Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington
| | - Damon Osbourn
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, St. Louis, Missouri
| | - David W Griggs
- Department of Molecular Microbiology and Immunology, Saint Louis University School of Medicine, St. Louis, Missouri
| | - Saul Tzipori
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts
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16
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Lunde CS, Stebbins EE, Jumani RS, Hasan MM, Miller P, Barlow J, Freund YR, Berry P, Stefanakis R, Gut J, Rosenthal PJ, Love MS, McNamara CW, Easom E, Plattner JJ, Jacobs RT, Huston CD. Identification of a potent benzoxaborole drug candidate for treating cryptosporidiosis. Nat Commun 2019; 10:2816. [PMID: 31249291 PMCID: PMC6597546 DOI: 10.1038/s41467-019-10687-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 05/23/2019] [Indexed: 11/09/2022] Open
Abstract
Cryptosporidiosis is a leading cause of life-threatening diarrhea in young children and causes chronic diarrhea in AIDS patients, but the only approved treatment is ineffective in malnourished children and immunocompromised people. We here use a drug repositioning strategy and identify a promising anticryptosporidial drug candidate. Screening a library of benzoxaboroles comprised of analogs to four antiprotozoal chemical scaffolds under pre-clinical development for neglected tropical diseases for Cryptosporidium growth inhibitors identifies the 6-carboxamide benzoxaborole AN7973. AN7973 blocks intracellular parasite development, appears to be parasiticidal, and potently inhibits the two Cryptosporidium species most relevant to human health, C. parvum and C. hominis. It is efficacious in murine models of both acute and established infection, and in a neonatal dairy calf model of cryptosporidiosis. AN7973 also possesses favorable safety, stability, and PK parameters, and therefore, is an exciting drug candidate for treating cryptosporidiosis.
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Affiliation(s)
| | - Erin E Stebbins
- Department of Medicine, University of Vermont Robert R. Larner College of Medicine, Burlington, VT, 05405, USA
| | - Rajiv S Jumani
- Department of Medicine, University of Vermont Robert R. Larner College of Medicine, Burlington, VT, 05405, USA
- Department of Microbiology and Molecular Genetics, University of Vermont College of Agriculture and Life Sciences, Burlington, VT, 05405, USA
| | - Md Mahmudul Hasan
- Department of Medicine, University of Vermont Robert R. Larner College of Medicine, Burlington, VT, 05405, USA
- Department of Microbiology and Molecular Genetics, University of Vermont College of Agriculture and Life Sciences, Burlington, VT, 05405, USA
| | - Peter Miller
- Department of Medicine, University of Vermont Robert R. Larner College of Medicine, Burlington, VT, 05405, USA
| | - John Barlow
- Department of Animal and Veterinary Sciences, University of Vermont College of Agriculture and Life Sciences, Burlington, VT, 05405, USA
| | | | - Pamela Berry
- Anacor Pharmaceuticals, Palo Alto, CA, 4230, USA
| | | | - Jiri Gut
- Department of Medicine, University of California San Francisco, San Francisco, CA, 94143, USA
| | - Philip J Rosenthal
- Department of Medicine, University of California San Francisco, San Francisco, CA, 94143, USA
| | | | | | - Eric Easom
- Anacor Pharmaceuticals, Palo Alto, CA, 4230, USA
| | | | | | - Christopher D Huston
- Department of Medicine, University of Vermont Robert R. Larner College of Medicine, Burlington, VT, 05405, USA.
- Department of Microbiology and Molecular Genetics, University of Vermont College of Agriculture and Life Sciences, Burlington, VT, 05405, USA.
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17
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Jumani RS, Hasan MM, Stebbins EE, Donnelly L, Miller P, Klopfer C, Bessoff K, Teixeira JE, Love MS, McNamara CW, Huston CD. A suite of phenotypic assays to ensure pipeline diversity when prioritizing drug-like Cryptosporidium growth inhibitors. Nat Commun 2019; 10:1862. [PMID: 31015448 PMCID: PMC6478823 DOI: 10.1038/s41467-019-09880-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 04/01/2019] [Indexed: 01/07/2023] Open
Abstract
Cryptosporidiosis is a leading cause of life-threatening diarrhea in children, and the only currently approved drug is ineffective in malnourished children and immunocompromised people. Large-scale phenotypic screens are ongoing to identify anticryptosporidial compounds, but optimal approaches to prioritize inhibitors and establish a mechanistically diverse drug development pipeline are unknown. Here, we present a panel of medium-throughput mode of action assays that enable testing of compounds in several stages of the Cryptosporidium life cycle. Phenotypic profiles are given for thirty-nine anticryptosporidials. Using a clustering algorithm, the compounds sort by phenotypic profile into distinct groups of inhibitors that are either chemical analogs (i.e. same molecular mechanism of action (MMOA)) or known to have similar MMOA. Furthermore, compounds belonging to multiple phenotypic clusters are efficacious in a chronic mouse model of cryptosporidiosis. This suite of phenotypic assays should ensure a drug development pipeline with diverse MMOA without the need to identify underlying mechanisms.
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Affiliation(s)
- Rajiv S Jumani
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA.,Cellular, Molecular and Biomedical Sciences Graduate Program, University of Vermont, Burlington, VT, 05405, USA.,Novartis Institute for Tropical Diseases, Novartis Institutes for BioMedical Research, Emeryville, CA, 94608, USA
| | - Muhammad M Hasan
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA.,Cellular, Molecular and Biomedical Sciences Graduate Program, University of Vermont, Burlington, VT, 05405, USA
| | - Erin E Stebbins
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Liam Donnelly
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Peter Miller
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Connor Klopfer
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Kovi Bessoff
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA.,Department of Surgery, Stanford University School of Medicine, Palo Alto, CA, 94305-5101, USA
| | - Jose E Teixeira
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Melissa S Love
- Calibr at The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Case W McNamara
- Calibr at The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Christopher D Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA. .,Cellular, Molecular and Biomedical Sciences Graduate Program, University of Vermont, Burlington, VT, 05405, USA. .,Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA.
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18
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Buckner FS, Ranade RM, Gillespie JR, Shibata S, Hulverson MA, Zhang Z, Huang W, Choi R, Verlinde CLMJ, Hol WGJ, Ochida A, Akao Y, Choy RKM, Van Voorhis WC, Arnold SLM, Jumani RS, Huston CD, Fan E. Optimization of Methionyl tRNA-Synthetase Inhibitors for Treatment of Cryptosporidium Infection. Antimicrob Agents Chemother 2019; 63:e02061-18. [PMID: 30745384 PMCID: PMC6437504 DOI: 10.1128/aac.02061-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 02/01/2019] [Indexed: 02/07/2023] Open
Abstract
Cryptosporidiosis is one of the leading causes of moderate to severe diarrhea in children in low-resource settings. The therapeutic options for cryptosporidiosis are limited to one drug, nitazoxanide, which unfortunately has poor activity in the most needy populations of malnourished children and HIV-infected persons. We describe here the discovery and early optimization of a class of imidazopyridine-containing compounds with potential for treating Cryptosporidium infections. The compounds target the Cryptosporidium methionyl-tRNA synthetase (MetRS), an enzyme that is essential for protein synthesis. The most potent compounds inhibited the enzyme with Ki values in the low picomolar range. Cryptosporidium cells in culture were potently inhibited with 50% effective concentrations as low as 7 nM and >1,000-fold selectivity over mammalian cells. A parasite persistence assay indicates that the compounds act by a parasiticidal mechanism. Several compounds were demonstrated to control infection in two murine models of cryptosporidiosis without evidence of toxicity. Pharmacological and physicochemical characteristics of compounds were investigated to determine properties that were associated with higher efficacy. The results indicate that MetRS inhibitors are excellent candidates for development for anticryptosporidiosis therapy.
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Affiliation(s)
| | - Ranae M Ranade
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - J Robert Gillespie
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Sayaka Shibata
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | | | - Zhongsheng Zhang
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Wenlin Huang
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Ryan Choi
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | | | - Wim G J Hol
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | | | | | - Robert K M Choy
- Drug Development Program, PATH, San Francisco, California, USA
| | | | - Sam L M Arnold
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Rajiv S Jumani
- Department of Medicine, University of Vermont, Burlington, Vermont, USA
| | | | - Erkang Fan
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
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19
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Bartelt LA, Bolick DT, Kolling GL, Stebbins E, Huston CD, Guerrant RL, Hoffman PS. Amixicile Reduces Severity of Cryptosporidiosis but Does Not Have In Vitro Activity against Cryptosporidium. Antimicrob Agents Chemother 2018; 62:e00718-18. [PMID: 30297368 PMCID: PMC6256802 DOI: 10.1128/aac.00718-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 09/28/2018] [Indexed: 12/13/2022] Open
Abstract
Cryptosporidium species cause significant morbidity in malnourished children. Nitazoxanide (NTZ) is the only approved treatment for cryptosporidiosis, but NTZ has diminished effectiveness during malnutrition. Here, we show that amixicile, a highly selective water-soluble derivative of NTZ diminishes Cryptosporidium infection severity in a malnourished mouse model despite a lack of direct anticryptosporidial activity. We suggest that amixicile, by tamping down anaerobes associated with intestinal inflammation, reverses weight loss and indirectly mitigates infection-associated pathology.
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Affiliation(s)
- Luther A Bartelt
- Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Center for Gastrointestinal Biology and Disease, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - David T Bolick
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Glynis L Kolling
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Erin Stebbins
- Division of Infectious Diseases, Department of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Christopher D Huston
- Division of Infectious Diseases, Department of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Richard L Guerrant
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Paul S Hoffman
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
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20
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Jumani RS, Bessoff K, Love MS, Miller P, Stebbins EE, Teixeira JE, Campbell MA, Meyers MJ, Zambriski JA, Nunez V, Woods AK, McNamara CW, Huston CD. A Novel Piperazine-Based Drug Lead for Cryptosporidiosis from the Medicines for Malaria Venture Open-Access Malaria Box. Antimicrob Agents Chemother 2018; 62:e01505-17. [PMID: 29339392 PMCID: PMC5913971 DOI: 10.1128/aac.01505-17] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 01/05/2018] [Indexed: 12/21/2022] Open
Abstract
Cryptosporidiosis causes life-threatening diarrhea in children under the age of 5 years and prolonged diarrhea in immunodeficient people, especially AIDS patients. The standard of care, nitazoxanide, is modestly effective in children and ineffective in immunocompromised individuals. In addition to the need for new drugs, better knowledge of drug properties that drive in vivo efficacy is needed to facilitate drug development. We report the identification of a piperazine-based lead compound for Cryptosporidium drug development, MMV665917, and a new pharmacodynamic method used for its characterization. The identification of MMV665917 from the Medicines for Malaria Venture Malaria Box was followed by dose-response studies, in vitro toxicity studies, and structure-activity relationship studies using commercial analogues. The potency of this compound against Cryptosporidium parvum Iowa and field isolates was comparable to that against Cryptosporidium hominis Furthermore, unlike nitazoxanide, clofazimine, and paromomycin, MMV665917 appeared to be curative in a NOD SCID gamma mouse model of chronic cryptosporidiosis. MMV665917 was also efficacious in a gamma interferon knockout mouse model of acute cryptosporidiosis. To determine if efficacy in this mouse model of chronic infection might relate to whether compounds are parasiticidal or parasitistatic for C. parvum, we developed a novel in vitro parasite persistence assay. This assay suggested that MMV665917 was parasiticidal, unlike nitazoxanide, clofazimine, and paromomycin. The assay also enabled determination of the concentration of the compound required to maximize the rate of parasite elimination. This time-kill assay can be used to prioritize early-stage Cryptosporidium drug leads and may aid in planning in vivo efficacy experiments. Collectively, these results identify MMV665917 as a promising lead and establish a new method for characterizing potential anticryptosporidial agents.
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Affiliation(s)
- R S Jumani
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
- Cellular, Molecular and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, USA
| | - K Bessoff
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - M S Love
- California Institute for Biomedical Research, La Jolla, California, USA
| | - P Miller
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - E E Stebbins
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - J E Teixeira
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
| | - M A Campbell
- Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - M J Meyers
- Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - J A Zambriski
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
| | - V Nunez
- California Institute for Biomedical Research, La Jolla, California, USA
| | - A K Woods
- California Institute for Biomedical Research, La Jolla, California, USA
| | - C W McNamara
- California Institute for Biomedical Research, La Jolla, California, USA
| | - C D Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont, USA
- Cellular, Molecular and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, USA
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21
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Stebbins E, Jumani RS, Klopfer C, Barlow J, Miller P, Campbell MA, Meyers MJ, Griggs DW, Huston CD. Clinical and microbiologic efficacy of the piperazine-based drug lead MMV665917 in the dairy calf cryptosporidiosis model. PLoS Negl Trop Dis 2018; 12:e0006183. [PMID: 29309415 PMCID: PMC5774826 DOI: 10.1371/journal.pntd.0006183] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/19/2018] [Accepted: 12/20/2017] [Indexed: 02/08/2023] Open
Abstract
Cryptosporidiosis causes life-threatening diarrhea in infants, but the best available treatment is only modestly efficacious. Rodents infected with relevant Cryptosporidium species do not develop diarrhea, which complicates drug development. Cryptosporidium parvum infection of dairy calves, however, causes an illness like that seen in infants. Here, the clinical and microbiologic anti-Cryptosporidium efficacy of the piperazine-based compound MMV665917 was demonstrated in neonatal calves. Oral administration of MMV665917 (22 mg/kg once daily) was begun two days after the onset of severe diarrhea and continued for seven days. Treatment resulted in prompt resolution of diarrhea, and reduced total fecal oocyst shedding by ~94%. MMV665917 was useful for treatment, rather than just prophylaxis, since it was safe and effective when administered well after the onset of diarrhea. Furthermore, even though all animals received intensive supportive care, there was a strong trend towards improved secondary health outcomes, including general health, appetite, and dehydration measures amongst treated animals. These data establish MMV665917 as an outstanding lead compound for Cryptosporidium drug development.
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Affiliation(s)
- Erin Stebbins
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Rajiv S. Jumani
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont
- Cell, Molecular and Biomedical Sciences graduate program, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - Connor Klopfer
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont
| | - John Barlow
- Department of Animal and Veterinary Sciences, University of Vermont College of Agriculture and Life Sciences, Burlington, Vermont
| | - Peter Miller
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont
| | | | | | | | - Christopher D. Huston
- Department of Medicine, University of Vermont Larner College of Medicine, Burlington, Vermont
- Cell, Molecular and Biomedical Sciences graduate program, University of Vermont Larner College of Medicine, Burlington, Vermont
- Department of Microbiology and Molecular Genetics, University of Vermont Larner College of Medicine, Burlington, Vermont
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22
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Osman KT, Ye J, Shi Z, Toker C, Lovato D, Jumani RS, Zuercher W, Huston CD, Edwards AM, Lautens M, Santhakumar V, Hui R. Discovery and structure activity relationship of the first potent cryptosporidium FIKK kinase inhibitor. Bioorg Med Chem 2017; 25:1672-1680. [DOI: 10.1016/j.bmc.2017.01.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/13/2017] [Accepted: 01/19/2017] [Indexed: 12/29/2022]
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23
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Love MS, Beasley FC, Jumani RS, Wright TM, Chatterjee AK, Huston CD, Schultz PG, McNamara CW. A high-throughput phenotypic screen identifies clofazimine as a potential treatment for cryptosporidiosis. PLoS Negl Trop Dis 2017; 11:e0005373. [PMID: 28158186 PMCID: PMC5310922 DOI: 10.1371/journal.pntd.0005373] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 02/15/2017] [Accepted: 01/30/2017] [Indexed: 11/19/2022] Open
Abstract
Cryptosporidiosis has emerged as a leading cause of non-viral diarrhea in children under five years of age in the developing world, yet the current standard of care to treat Cryptosporidium infections, nitazoxanide, demonstrates limited and immune-dependent efficacy. Given the lack of treatments with universal efficacy, drug discovery efforts against cryptosporidiosis are necessary to find therapeutics more efficacious than the standard of care. To date, cryptosporidiosis drug discovery efforts have been limited to a few targeted mechanisms in the parasite and whole cell phenotypic screens against small, focused collections of compounds. Using a previous screen as a basis, we initiated the largest known drug discovery effort to identify novel anticryptosporidial agents. A high-content imaging assay for inhibitors of Cryptosporidium parvum proliferation within a human intestinal epithelial cell line was miniaturized and automated to enable high-throughput phenotypic screening against a large, diverse library of small molecules. A screen of 78,942 compounds identified 12 anticryptosporidial hits with sub-micromolar activity, including clofazimine, an FDA-approved drug for the treatment of leprosy, which demonstrated potent and selective in vitro activity (EC50 = 15 nM) against C. parvum. Clofazimine also displayed activity against C. hominis-the other most clinically-relevant species of Cryptosporidium. Importantly, clofazimine is known to accumulate within epithelial cells of the small intestine, the primary site of Cryptosporidium infection. In a mouse model of acute cryptosporidiosis, a once daily dosage regimen for three consecutive days or a single high dose resulted in reduction of oocyst shedding below the limit detectable by flow cytometry. Recently, a target product profile (TPP) for an anticryptosporidial compound was proposed by Huston et al. and highlights the need for a short dosing regimen (< 7 days) and formulations for children < 2 years. Clofazimine has a long history of use and has demonstrated a good safety profile for a disease that requires chronic dosing for a period of time ranging 3-36 months. These results, taken with clofazimine's status as an FDA-approved drug with over four decades of use for the treatment of leprosy, support the continued investigation of clofazimine both as a new chemical tool for understanding cryptosporidium biology and a potential new treatment of cryptosporidiosis.
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Affiliation(s)
- Melissa S. Love
- California Institute for Biomedical Research, La Jolla, California, United States of America
| | - Federico C. Beasley
- California Institute for Biomedical Research, La Jolla, California, United States of America
| | - Rajiv S. Jumani
- Department of Medicine, University of Vermont College of Medicine, Burlington, Vermont, United States of America
| | - Timothy M. Wright
- California Institute for Biomedical Research, La Jolla, California, United States of America
| | - Arnab K. Chatterjee
- California Institute for Biomedical Research, La Jolla, California, United States of America
| | - Christopher D. Huston
- Department of Medicine, University of Vermont College of Medicine, Burlington, Vermont, United States of America
| | - Peter G. Schultz
- California Institute for Biomedical Research, La Jolla, California, United States of America
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Case W. McNamara
- California Institute for Biomedical Research, La Jolla, California, United States of America
- * E-mail:
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24
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Huston CD, Spangenberg T, Burrows J, Willis P, Wells TNC, van Voorhis W. A Proposed Target Product Profile and Developmental Cascade for New Cryptosporidiosis Treatments. PLoS Negl Trop Dis 2015; 9:e0003987. [PMID: 26447884 PMCID: PMC4598153 DOI: 10.1371/journal.pntd.0003987] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Christopher D. Huston
- Department of Medicine, University of Vermont College of Medicine, Burlington, Vermont, United States of America
- * E-mail:
| | | | | | - Paul Willis
- Medicines for Malaria Venture, Geneva, Switzerland
| | | | - Wesley van Voorhis
- Medicines for Malaria Venture, Geneva, Switzerland
- Department of Medicine, University of Washington School of Medicine, Seattle, Washington, United States of America
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25
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Checkley W, White AC, Jaganath D, Arrowood MJ, Chalmers RM, Chen XM, Fayer R, Griffiths JK, Guerrant RL, Hedstrom L, Huston CD, Kotloff KL, Kang G, Mead JR, Miller M, Petri WA, Priest JW, Roos DS, Striepen B, Thompson RCA, Ward HD, Van Voorhis WA, Xiao L, Zhu G, Houpt ER. A review of the global burden, novel diagnostics, therapeutics, and vaccine targets for cryptosporidium. Lancet Infect Dis 2014; 15:85-94. [PMID: 25278220 DOI: 10.1016/s1473-3099(14)70772-8] [Citation(s) in RCA: 597] [Impact Index Per Article: 59.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cryptosporidium spp are well recognised as causes of diarrhoeal disease during waterborne epidemics and in immunocompromised hosts. Studies have also drawn attention to an underestimated global burden and suggest major gaps in optimum diagnosis, treatment, and immunisation. Cryptosporidiosis is increasingly identified as an important cause of morbidity and mortality worldwide. Studies in low-resource settings and high-income countries have confirmed the importance of cryptosporidium as a cause of diarrhoea and childhood malnutrition. Diagnostic tests for cryptosporidium infection are suboptimum, necessitating specialised tests that are often insensitive. Antigen-detection and PCR improve sensitivity, and multiplexed antigen detection and molecular assays are underused. Therapy has some effect in healthy hosts and no proven efficacy in patients with AIDS. Use of cryptosporidium genomes has helped to identify promising therapeutic targets, and drugs are in development, but methods to assess the efficacy in vitro and in animals are not well standardised. Partial immunity after exposure suggests the potential for successful vaccines, and several are in development; however, surrogates of protection are not well defined. Improved methods for propagation and genetic manipulation of the organism would be significant advances.
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Affiliation(s)
- William Checkley
- Program in Global Disease Epidemiology and Control, Department of International Health, Johns Hopkins University, Baltimore, MD, USA; Fogarty International Center, National Institutes of Health, Bethesda, MD, USA.
| | - A Clinton White
- Division of Infectious Diseases, University of Texas Medical Branch, Galveston, TX, USA
| | - Devan Jaganath
- Program in Global Disease Epidemiology and Control, Department of International Health, Johns Hopkins University, Baltimore, MD, USA
| | | | - Rachel M Chalmers
- National Cryptosporidium Reference Unit, Public Health Wales, Swansea, UK
| | - Xian-Ming Chen
- Department of Medical Microbiology and Immunology, Creighton University, Omaha, NE, USA
| | - Ronald Fayer
- Environmental Microbial Food Safety Laboratory, USDA, Beltsville, MD, USA
| | - Jeffrey K Griffiths
- Department of Public Health and Community Medicine, Tufts University, Boston, MA, USA
| | - Richard L Guerrant
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA
| | - Lizbeth Hedstrom
- Department of Biology and Department of Chemistry, Brandeis University, Waltham, MA, USA
| | | | - Karen L Kotloff
- Division of Infectious Disease and Tropical Pediatrics, Department of Pediatrics, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Gagandeep Kang
- Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | - Jan R Mead
- Department of Pediatrics, Emory University, Atlanta, GA, USA; Atlanta VA Medical Center, Decatur, GA, USA
| | - Mark Miller
- Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
| | - William A Petri
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA
| | | | - David S Roos
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Boris Striepen
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, USA
| | - R C Andrew Thompson
- School of Veterinary and Life Sciences, Murdoch University, Perth, WA, Australia
| | - Honorine D Ward
- Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center Boston, MA, USA
| | - Wesley A Van Voorhis
- Allergy and Infectious Diseases Division, Departments of Medicine, Global Health, and Microbiology, University of Washington, Seattle, WA, USA
| | - Lihua Xiao
- Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Guan Zhu
- Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA
| | - Eric R Houpt
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA
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26
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Bessoff K, Spangenberg T, Foderaro JE, Jumani RS, Ward GE, Huston CD. Identification of Cryptosporidium parvum active chemical series by Repurposing the open access malaria box. Antimicrob Agents Chemother 2014; 58:2731-9. [PMID: 24566188 PMCID: PMC3993250 DOI: 10.1128/aac.02641-13] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/20/2014] [Indexed: 01/19/2023] Open
Abstract
The apicomplexan parasites Cryptosporidium parvum and Cryptosporidium hominis are major etiologic agents of human cryptosporidiosis. The infection is typically self-limited in immunocompetent adults, but it can cause chronic fulminant diarrhea in immunocompromised patients and malnutrition and stunting in children. Nitazoxanide, the current standard of care for cryptosporidiosis, is only partially efficacious for children and is no more effective than a placebo for AIDS patients. Unfortunately, financial obstacles to drug discovery for diseases that disproportionately affect low-income countries and technical limitations associated with studies of Cryptosporidium biology impede the development of better drugs for treating cryptosporidiosis. Using a cell-based high-throughput screen, we queried the Medicines for Malaria Venture (MMV) Open Access Malaria Box for activity against C. parvum. We identified 3 novel chemical series derived from the quinolin-8-ol, allopurinol-based, and 2,4-diamino-quinazoline chemical scaffolds that exhibited submicromolar potency against C. parvum. Potency was conserved in a subset of compounds from each scaffold with varied physicochemical properties, and two of the scaffolds identified exhibit more rapid inhibition of C. parvum growth than nitazoxanide, making them excellent candidates for further development. The 2,4-diamino-quinazoline and allopurinol-based compounds were also potent growth inhibitors of the related apicomplexan parasite Toxoplasma gondii, and a good correlation was observed in the relative activities of the compounds in the allopurinol-based series against T. gondii and C. parvum. Taken together, these data illustrate the utility of the Open Access Malaria Box as a source of both potential leads for drug development and chemical probes to elucidate basic biological processes in C. parvum and other apicomplexan parasites.
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Affiliation(s)
- Kovi Bessoff
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
| | | | - Jenna E. Foderaro
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
| | - Rajiv S. Jumani
- Cell, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, USA
| | - Gary E. Ward
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
- Cell, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, USA
| | - Christopher D. Huston
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
- Cell, Molecular, and Biomedical Sciences Graduate Program, University of Vermont, Burlington, Vermont, USA
- Department of Medicine, University of Vermont, Burlington, Vermont, USA
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27
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Abstract
Entamoeba histolytica is a protozoan parasite responsible for invasive intestinal and extraintestinal amebiasis. The pathology of amebiasis is still poorly understood, which can be largely attributed to lack of molecular tools. Here we present the optimization of SNAP-tag technology via codon optimization specific for E. histolytica. The resultant SNAP protein is highly expressed in amebic trophozoites, and shows proper localization when tagged with an endoplasmic reticulum retention signal. We further demonstrate the capabilities of this system using super resolution microscopy, done for the first time in E. histolytica.
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Affiliation(s)
- Adam Sateriale
- University of Vermont Cellular, Molecular, and Biomedical Sciences Program, Burlington, Vermont, United States of America
- University of Vermont Department of Medicine, Burlington, Vermont, United States of America
| | - Nathan H. Roy
- University of Vermont Cellular, Molecular, and Biomedical Sciences Program, Burlington, Vermont, United States of America
- University of Vermont Microbiology and Molecular Genetics, Burlington, Vermont, United States of America
| | - Christopher D. Huston
- University of Vermont Cellular, Molecular, and Biomedical Sciences Program, Burlington, Vermont, United States of America
- University of Vermont Microbiology and Molecular Genetics, Burlington, Vermont, United States of America
- University of Vermont Department of Medicine, Burlington, Vermont, United States of America
- * E-mail:
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28
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Abstract
OBJECTIVE To identify potential opportunities for drug repurposing by developing an automated approach to pre-screen the predicted proteomes of any organism against databases of known drug targets using only freely available resources. MATERIALS AND METHODS We employed a combination of Ruby scripts that leverage data from the DrugBank and ChEMBL databases, MySQL, and BLAST to predict potential drugs and their targets from 13 published genomes. Results from a previous cell-based screen to identify inhibitors of Cryptosporidium parvum growth were used to validate our in-silico prediction method. RESULTS In-vitro validation of these results, using a cell-based C parvum growth assay, showed that the predicted inhibitors were significantly more likely than expected by chance to have confirmed activity, with 8.9-15.6% of predicted inhibitors confirmed depending on the drug target database used. This method was then used to predict inhibitors for the following 13 disease-causing protozoan parasites, including: C parvum, Entamoeba histolytica, Giardia intestinalis, Leishmania braziliensis, Leishmania donovani, Leishmania major, Naegleria gruberi (in proxy of Naegleria fowleri), Plasmodium falciparum, Plasmodium vivax, Toxoplasma gondii, Trichomonas vaginalis, Trypanosoma brucei and Trypanosoma cruzi. CONCLUSIONS Although proteome-wide screens for drug targets have disadvantages, in-silico methods can be developed that are fast, broad, inexpensive, and effective. In-vitro validation of our results for C parvum indicate that the method presented here can be used to construct a library for more directed small molecule screening, or pipelined into structural modeling and docking programs to facilitate target-based drug development.
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Affiliation(s)
- Adam Sateriale
- Cell, Molecular, and Biomedical Sciences Graduate Program, University of Vermont College of Medicine, Burlington, Vermont, USA
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Vaithilingam A, Teixeira JE, Huston CD. Endoplasmic reticulum continuity in the protozoan parasite Entamoeba histolytica: Evolutionary implications and a cautionary note. Commun Integr Biol 2012; 1:172-4. [PMID: 19704884 DOI: 10.4161/cib.1.2.7143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Accepted: 10/03/2008] [Indexed: 11/19/2022] Open
Abstract
Entamoeba histolytica has been described as an early branching eukaryotic parasite based on the lack of organelles such as mitochondria and peroxisomes, and on morphologic studies that concluded it possesses a vesicular endoplasmic reticulum (ER) and Golgi complex. However, a recent study from our laboratory showed that the E. histolytica ER is continuous by using an ER-targeted green fluorescent protein fusion protein and photobleaching experiments. We proposed that the vesicular ER seen earlier was likely an artifact of fixation. We now report data using an alternative fixation protocol that preserves the continuous ER morphology. These data confirm that the vesicular ER reported earlier was indeed a fixation artifact; furthermore, since we observed the same ER structure when staining for the native antigen HSP-70 in wild-type amebae, the data provide direct evidence that the continuous ER morphology we reported is correct. This work has important implications for cell biologists studying E. histolytica virulence, emphasizes the frequent need to reassess assumptions based on published data, and provides additional evidence that E. histolytica actually diverged relatively late in evolution and that many of its unusual features are likely due to loss of features during adaptation to its ecological niche.
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Heron BT, Sateriale A, Teixeira JE, Huston CD. Evidence for a novel Entamoeba histolytica lectin activity that recognises carbohydrates present on ovalbumin. Int J Parasitol 2010; 41:137-44. [PMID: 20807536 DOI: 10.1016/j.ijpara.2010.07.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Accepted: 07/19/2010] [Indexed: 11/29/2022]
Abstract
Entamoeba histolytica, an intestinal amoeba that causes dysentery and liver abscesses, acquires nutrients by engulfing bacteria in the colonic lumen and phagocytoses apoptotic cells during tissue invasion. In preliminary studies to identify ligands that stimulate amoebic phagocytosis, we used ovalbumin immobilized on latex particles as a potential negative control protein. Surprisingly, ovalbumin strongly stimulated E. histolytica particle uptake. Experiments using highly purified ovalbumin confirmed the specificity of this finding. The mechanism of particle uptake was actin-dependent, and the Entamoeba phagosome marker amoebapore A localised to ovalbumin-bead containing vacuoles. The most well described amoebic receptor is a Gal/GalNAc-specific lectin, but d-galactose had no effect on ovalbumin-stimulated phagocytosis. Ovalbumin has a single N-glycosylation site (Asn(292)) and is modified with oligomannose and hybrid-type oligosaccharides. We used both trifluoromethanesulfonic acid and N-glycanase to deglycosylate ovalbumin and tested the effect. Both methods substantially reduced the stimulatory effect of ovalbumin. Biotinylated ovalbumin bound the surface of fixed E. histolytica trophozoites saturably; furthermore, denatured ovalbumin and native ovalbumin both specifically inhibited ovalbumin-biotin binding, but deglycosylated ovalbumin had no effect. Collectively, these data suggest that E. histolytica has a previously unrecognised surface lectin activity that binds to carbohydrates on ovalbumin and stimulates phagocytosis.
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Affiliation(s)
- Bradley T Heron
- Cell and Molecular Biology Program, University of Vermont College of Medicine, Burlington, VT 05405, USA
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Boettner DR, Huston CD, Linford AS, Buss SN, Houpt E, Sherman NE, Petri WA. Entamoeba histolytica phagocytosis of human erythrocytes involves PATMK, a member of the transmembrane kinase family. PLoS Pathog 2008; 4:e8. [PMID: 18208324 PMCID: PMC2211552 DOI: 10.1371/journal.ppat.0040008] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Accepted: 12/10/2007] [Indexed: 11/19/2022] Open
Abstract
Entamoeba histolytica is the cause of amebic colitis and liver abscess. This parasite induces apoptosis in host cells and utilizes exposed ligands such as phosphatidylserine to ingest the apoptotic corpses and invade deeper into host tissue. The purpose of this work was to identify amebic proteins involved in the recognition and ingestion of dead cells. A member of the transmembrane kinase family, phagosome-associated TMK96 (PATMK), was identified in a proteomic screen for early phagosomal proteins. Anti-peptide affinity-purified antibody produced against PATMK demonstrated that it was a type I integral membrane protein that was expressed on the trophozoite surface, and that co-localized with human erythrocytes at the site of contact. The role of PATMK in erythrophagocytosis in vitro was demonstrated by: (i) incubation of ameba with anti-PATMK antibodies; (ii) PATMK mRNA knock-down using a novel shRNA expression system; and (iii) expression of a carboxy-truncation of PATMK (PATMKΔ932). Expression of the carboxy-truncation of PATMKΔ932 also caused a specific reduction in the ability of E. histolytica to establish infection in the intestinal model of amebiasis, however these amebae retained the ability to cause hepatic abscesses when directly injected in the liver. In conclusion, PATMK was identified as a member of the TMK family that participates in erythrophagocytosis and is uniquely required for intestinal infection. There is a highly ordered process by which the parasite Entamoeba histolytica interacts with human cells. Adherence via a parasite lectin is followed in seconds by killing, with only the corpse and not a living cell ingested by the ameba. This process is so central to pathogenesis that clinicians use the presence of ingested erythrocytes to identify E. histolytica and distinguish it from harmless commensal amebae of the gut. We hypothesized that identification of molecules involved in the ingestion of the corpse might provide insight into how amebae cause colitis. We identified a member of the transmembrane kinase family as an early component of the phagosome. Inhibition of this kinase blocked red cell ingestion and prevented amebae from colonizing and invading the gut. There was no impact on dominant-negative parasites to cause liver abscess, suggesting the pathogenesis program differs between anatomic sites. Future studies of the transmembrane kinanse in erythrophagocytosis may provide insight into how amebae colonize and invade the gut, with the ultimate goal of preventing disease.
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Affiliation(s)
- Douglas R Boettner
- Department of Microbiology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Christopher D Huston
- Department of Medicine, University of Vermont, Burlington, Vermont, United States of America
- Department of Microbiology, University of Vermont, Burlington, Vermont, United States of America
| | - Alicia S Linford
- Department of Microbiology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Sarah N Buss
- Department of Microbiology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Eric Houpt
- Department of Medicine, University of Virginia, Charlottesville, Virginia, United States of America
| | - Nicholas E Sherman
- Department of Microbiology, University of Virginia, Charlottesville, Virginia, United States of America
| | - William A Petri
- Department of Microbiology, University of Virginia, Charlottesville, Virginia, United States of America
- Department of Medicine, University of Virginia, Charlottesville, Virginia, United States of America
- Department of Pathology, University of Virginia, Charlottesville, Virginia, United States of America
- * To whom correspondence should be addressed. E-mail:
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Teixeira JE, Huston CD. Participation of the serine-rich Entamoeba histolytica protein in amebic phagocytosis of apoptotic host cells. Infect Immun 2008; 76:959-66. [PMID: 18086807 PMCID: PMC2258814 DOI: 10.1128/iai.01455-07] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 11/28/2007] [Accepted: 12/07/2007] [Indexed: 11/20/2022] Open
Abstract
Entamoeba histolytica is an intestinal ameba that causes dysentery and liver abscesses. Cytotoxicity and phagocytosis of host cells characterize invasive E. histolytica infection. Prior to phagocytosis of host cells, E. histolytica induces apoptotic host cell death, using a mechanism that requires contact via an amebic galactose-specific lectin. However, lectin inhibition only partially blocks phagocytosis of already dead cells, implicating at least one additional receptor in phagocytosis. To identify receptors for engulfment of apoptotic cells, monoclonal antibodies against E. histolytica membrane antigens were screened for inhibition of phagocytosis. Of 43 antibodies screened, one blocked lectin-independent uptake of apoptotic cells, with >90% inhibition at a dose of 20 microg/ml (P < 0.0003 versus control). The same antibody also inhibited adherence to apoptotic lymphocytes and, to a lesser extent, adherence to and killing of viable lymphocytes. The antigen recognized by the inhibitory antibody was purified by affinity chromatography and identified by liquid chromatography-mass spectrometry as the serine-rich E. histolytica protein (SREHP). Consistent with this, the inhibitory antibody bound to recombinant SREHP present in bacterial lysates on immunoblots. The SREHP is an abundant immunogenic surface protein of unclear function. The results of this unbiased antibody screen strongly implicate the SREHP as a participant in E. histolytica phagocytosis and suggest that it may play an important role in adherence to apoptotic cells.
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Affiliation(s)
- Jose E Teixeira
- Department of Medicine, University of Vermont College of Medicine, Burlington, VT 05405, USA
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Kirkpatrick BD, Huston CD, Wagner D, Noel F, Rouzier P, Pape JW, Bois G, Larsson CJ, Alston WK, Tenney K, Powden C, O'Neill JP, Sears CL. Serum mannose-binding lectin deficiency is associated with cryptosporidiosis in young Haitian children. Clin Infect Dis 2006; 43:289-94. [PMID: 16804841 DOI: 10.1086/505396] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Accepted: 03/20/2006] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Mannose-binding lectin (MBL) is a component of the innate immune response and binds microbial surfaces through carbohydrate recognition domains. MBL deficiency may contribute to susceptibility to a variety of infectious diseases, particularly in young children. MBL binds to the Cryptosporidium sporozoite and may be important in resistance to cryptosporidiosis. METHODS We studied the association of serum MBL levels and cryptosporidiosis in a case-control study of young Haitian children with cryptosporidiosis versus children who were control subjects. RESULTS Ninety-nine children were enrolled, as follows: 49 children with cryptosporidiosis, 41 healthy controls, and 9 children with diarrhea from other causes. Case children were more malnourished than controls, and 49% had persistent or chronic diarrhea. At enrollment, mean serum MBL levels were markedly lower in children with cryptosporidiosis (P = .002), as was the number of children with an MBL deficiency of < or = 70 ng/mL (P = .005). In multivariate analysis, the association of cryptosporidiosis and MBL deficiency persisted (P = .002; adjusted odds ratio, 22.4), as did the association of cryptosporidiosis with general malnutrition. The subset of children with cryptosporidiosis and MBL deficiency were more likely to be male (P = .025). CONCLUSIONS MBL may be an important component of innate immune protection against Cryptosporidium infection in young children. Additional studies are necessary to determine whether MBL intestinal losses, deficient epithelial expression, and/or genetic polymorphisms in the MBL gene contribute to MBL deficiency in cryptosporidiosis and other enteric infections in young children.
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Affiliation(s)
- B D Kirkpatrick
- Department of Medicine Unit of Infectious Diseases, University of Vermont College of Medicine, Burlington, Vermont 05405, USA.
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Huston CD, Miller-Sims VC, Teixeira JE. Identification and characterization of EhABC A1, an Entamoeba histolytica Group A ABC transporter with similarity to Ced-7. Mol Biochem Parasitol 2006; 146:272-6. [PMID: 16442643 DOI: 10.1016/j.molbiopara.2005.12.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 12/21/2005] [Accepted: 12/24/2005] [Indexed: 11/24/2022]
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Okada M, Huston CD, Oue M, Mann BJ, Petri WA, Kita K, Nozaki T. Kinetics and strain variation of phagosome proteins of Entamoeba histolytica by proteomic analysis. Mol Biochem Parasitol 2005; 145:171-83. [PMID: 16290089 DOI: 10.1016/j.molbiopara.2005.10.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 09/29/2005] [Accepted: 10/03/2005] [Indexed: 12/01/2022]
Abstract
The protozoan parasite Entamoeba histolytica ingests and feeds on microorganisms and mammalian cells. Phagocytosis is essential for cell growth and implicated in pathogenesis of E. histolytica. We report here the dynamic changes of phagosome proteins during phagosome maturation by proteomic analysis using reversed-phase capillary liquid chromatography and ion trap tandem mass spectrometry. Phagosomes were isolated at various intervals after internalization of latex beads. Immunoblot analysis and electron microscopy verified successful isolation of phagosomes. A total of 159 proteins were identified from the reference strain HM1 at different stages of phagosome maturation. Approximately 70% of them were detected in a time-dependent fashion, suggesting dynamism of phagosome biogenesis. The kinetics of representative proteins were verified by immunoblots and also by video microscopy of live transgenic amebae expressing green fluorescent protein-fused EhRab7A. Furthermore, we observed significant differences in phagosome profiles between HM1 and two recent clinical isolates. Approximately 60% of 229 proteins detected in at least one of these three strains were identified only in one strain, while approximately 20% of these proteins were detected in all three strains. These data should provide significant insights into molecular characterization of phagosome biogenesis, and help to elucidate the pathogenesis of this important infection.
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Affiliation(s)
- Mami Okada
- Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
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Okada M, Huston CD, Mann BJ, Petri WA, Kita K, Nozaki T. Proteomic analysis of phagocytosis in the enteric protozoan parasite Entamoeba histolytica. Eukaryot Cell 2005; 4:827-31. [PMID: 15821141 PMCID: PMC1087816 DOI: 10.1128/ec.4.4.827-831.2005] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Proteomic analysis of phagosomes isolated from Entamoeba histolytica by liquid chromatography and mass spectrometry identified 85 proteins involved in surface recognition, actin cytoskeleton rearrangement, vesicular trafficking, and degradation. Phagosome localization of representative proteins was verified by immunofluorescence assay. This study should provide a basis for molecular identification and characterization of phagosome biogenesis.
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Affiliation(s)
- Mami Okada
- Department of Parasitology, Gunma University Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
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Boettner DR, Huston CD, Sullivan JA, Petri WA. Entamoeba histolytica and Entamoeba dispar utilize externalized phosphatidylserine for recognition and phagocytosis of erythrocytes. Infect Immun 2005; 73:3422-30. [PMID: 15908370 PMCID: PMC1111853 DOI: 10.1128/iai.73.6.3422-3430.2005] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Amebic erythrophagocytosis is characteristic of invasive amebiasis, and mutants deficient in erythrocyte ingestion are avirulent. We sought to understand the molecular mechanisms underlying erythrocyte phagocytosis by Entamoeba histolytica. Following adherence to amebae, erythrocytes became round and crenulated, and phosphatidylserine (PS) was exposed on their outer membrane leaflets. These changes were similar to the effects of calcium treatment on erythrocytes, which we utilized to separate ameba-induced exposure of erythrocyte PS from the process of phagocytosis. The adherence and phagocytosis of calcium-treated erythrocytes were less inhibited by galactose than were those of healthy erythrocytes, suggesting the existence of an amebic coreceptor specific for PS. To test whether PS was recognized by amebae, calcium-treated cells were incubated with annexin V prior to adherence to or ingestion by E. histolytica. Annexin V blocked both adherence (50% +/- 12% inhibition; P < 0.05) and phagocytosis (65% +/- 10%; P < 0.05), providing evidence that at least one galactose-independent coreceptor was involved in the adherence and ingestion of red blood cells. The coreceptor was inhibited by phospho-l-serine and to a lesser extent by phospho-d-serine but not by phospho-l-threonine, which is consistent with the coreceptor functioning in the adherence and ingestion of erythrocytes via recognition of PS. We expanded our investigations to the highly related but noninvasive parasite Entamoeba dispar and demonstrated that it was deficient in red-blood-cell adherence, induction of PS exposure, and phagocytosis. These findings establish phosphatidylserine involvement in erythrophagocytosis by amebae and suggest the existence of a PS receptor on the surfaces of both E. histolytica and E. dispar.
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Affiliation(s)
- Douglas R Boettner
- Division of Infectious Diseases and International Health, P. O. Box 801340, Rm. 2115, MR4 Building, University of Virginia Health System, Charlottesville, VA 22908-1340, USA
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Affiliation(s)
- Christopher D Huston
- Department of Medicine, Division of Infectious Disease, University of Vermont College of Medicine, 304 Burgess Building, Fletcher Allen Health Care, 111 Colchester Avenue, Burlington, VT 05401, USA.
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Affiliation(s)
- Rashidul Haque
- International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
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40
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Huston CD, Boettner DR, Miller-Sims V, Petri WA. Apoptotic killing and phagocytosis of host cells by the parasite Entamoeba histolytica. Infect Immun 2003; 71:964-72. [PMID: 12540579 PMCID: PMC145391 DOI: 10.1128/iai.71.2.964-972.2003] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2002] [Revised: 10/11/2002] [Accepted: 10/25/2002] [Indexed: 11/20/2022] Open
Abstract
The ability of Entamoeba histolytica to kill and phagocytose host cells correlates with parasite virulence. This study addressed the role of apoptotic cell killing and host cell phosphatidylserine exposure in the subsequent phagocytosis of Jurkat T cells by E. histolytica. Ingested host cells were apoptotic, as evidenced by the activation of caspase 3 in 88% +/- 3% (mean and standard deviation [SD] of the mean) of Jurkat cells engulfed by E. histolytica; ingested cells without detectable active caspase 3 were already disrupted and partially digested. That apoptotic cell killing preceded phagocytosis was supported by the demonstration that a higher percentage of amebae ingested apoptotic cells than ingested healthy cells (62% +/- 7% versus 30% +/- 9%, respectively [mean and SD]) (P = 0.008). E. histolytica also ingested apoptotic Jurkat cells more rapidly than necrotic control cells (8.5% +/- 0.4% versus 3.5% +/- 0.7%, respectively [mean and SD]) (P < 0.001). The inhibition of amebic cytotoxicity with D-galactose (which blocks the amebic Gal/GalNAc lectin) blocked the phagocytosis of healthy cells by greater than 80%, providing further evidence that apoptosis preceded engulfment. In contrast, D-galactose blocked the phagocytosis of already apoptotic cells by only 40%, implicating an additional host ligand (besides D-galactose) in amebic engulfment of apoptotic cells. The most characteristic surface change on apoptotic cells is phosphatidylserine exposure. Consistent with a role for host cell phosphatidylserine exposure in amebic ingestion of killed cells, Jurkat cell phosphatidylserine was exposed during incubation with E. histolytica (27% +/- 1% [mean and SD] specific increase at 30 min) (the P value versus the control was 0.0003). Approximately 50% more amebae ingested viable Jurkat cells expressing phosphatidylserine on the outer leaflet of the plasma membrane than ingested control cells (30.3% +/- 2.2% versus 19.8% +/- 1.9%, respectively [mean and SD]) (P = 0.003). By analogy with phagocytic clearance during apoptosis in metazoans, amebic apoptotic host cell killing followed by phagocytosis may limit inflammation and enable amebae to evade the host immune response.
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Affiliation(s)
- Christopher D Huston
- Department of Medicine, University of Virginia Health System, Charlottesville 22908.
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Cheng XJ, Hughes MA, Huston CD, Loftus B, Gilchrist CA, Lockhart LA, Ghosh S, Miller-Sims V, Mann BJ, Petri WA, Tachibana H. Intermediate subunit of the Gal/GalNAc lectin of Entamoeba histolytica is a member of a gene family containing multiple CXXC sequence motifs. Infect Immun 2001; 69:5892-8. [PMID: 11500468 PMCID: PMC98708 DOI: 10.1128/iai.69.9.5892-5898.2001] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Killing by Entamoeba histolytica requires parasite adherence to host galactose- and N-acetyl-D-galactosamine (Gal/GalNAc)-containing cell surface receptors. A 260-kDa heterodimeric E. histolytica Gal/GalNAc lectin composed of heavy (Hgl) and light (Lgl) subunits has been previously described. Here we present the cloning and characterization of Igl, a 150-kDa intermediate subunit of the Gal/GalNAc lectin. Igl, Hgl, and Lgl colocalized on the surface membrane of trophozoites. Two unlinked copies of genes encoding Igl shared 81% amino acid sequence identity (GenBank accession no. AF337950 and AF337951). They encoded cysteine-rich proteins with amino- and carboxy-terminal hydrophobic signal sequences characteristic of glycosylphosphatidylinositol (GPI)-anchored membrane proteins. The igl genes lacked carbohydrate recognition domains but were members of a large family of amebic genes containing CXXC and CXC motifs. These data indicate that Igl is part of the parasite's multimolecular Gal/GalNAc adhesin required for host interaction.
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Affiliation(s)
- X J Cheng
- Department of Infectious Diseases, Tokai University School of Medicine, Bohseidai, Isehara, Kanagawa 259-1193, Japan
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Abstract
The intestinal protozoa have gained importance to physicians practicing medicine in the United States, Canada, and Europe during recent years as a result of increasing world travel, the globalization of the world's economy, and the growing number of chronically immunosuppressed people. During the spring of 1996, Cyclospora cayetanensis caused diarrhea in approximately 1500 people exposed to Guatemalan raspberries. This epidemic recurred in 1997, emphasizing the risks of the global economy and food supply on which we depend. In addition to importation of intestinal protozoa from the tropics, AIDS and the increasing use of organ transplants have created a new population of people at risk for chronic infection by ubiquitous protozoa previously not known to cause serious human disease. These infections include cryptosporidiosis, isosporiasis, and microsporidiosis. Finally, Entamoeba histolytica, the etiologic agent of invasive amebiasis, has only recently been recognized to be a distinct species from a nonpathogenic but indistinguishable (by light microscopy) intestinal commensal, Entamoeba dispar. The rapidly changing epidemiology of these intestinal protozoa, as well as new approaches to diagnosis and treatment of these protozoa, are discussed.
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Affiliation(s)
- C D Huston
- Departments of Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA.
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Abstract
The parasite Entamoeba histolytica is named for its ability to lyse host tissues. To determine the factors responsible, we have initiated an examination of the contribution of parasite virulence factors and host caspases to cellular destruction by the parasite. Amoebic colitis in C3H/HeJ mice was associated with extensive host apoptosis at sites of E. histolytica invasion. In vitro studies of E. histolytica-Jurkat T-cell interactions demonstrated that apoptosis required contact via the amoebic Gal/GalNAc lectin, but was unaffected by 75% inhibition of the amoebic cysteine proteinases. Parasite-induced DNA fragmentation was unaffected in caspase 8-deficient Jurkat cells treated with the caspase 9 inhibitor Ac-LEHD-fmk. In contrast, caspase 3-like activity was observed within minutes of E. histolytica contact and the caspase 3 inhibitor Ac-DEVD-CHO blocked Jurkat T cell death, as measured by both DNA fragmentation and 51Cr release. These data demonstrate rapid parasite-induced activation of caspase 3-like caspases, independent of the upstream caspases 8 and 9, which is required for host cell death.
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Affiliation(s)
- C D Huston
- Department of Medicine, University of Virginia Health, Sciences Center, Charlottesville 22908-1340, USA
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Affiliation(s)
- C D Huston
- Departments of Medicine and Microbiology, University of Virginia Health Sciences Center, Charlottesville, VA 22908-1340, USA
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Abstract
Infection with Entamoeba histolytica, the protozoan parasite that causes amoebic
colitis and liver abscess, results in 34 million to 50 million symptomatic cases
of amoebiasis (all illnesses caused by E. histolytica, including amoebic dysentery)
worldwide each year, causing 40 thousand to 100 thousand deaths annually. As
a result of accruing biochemical, genetic and immunological data, E. histolytica
was re-defined in 1993 to recognise the existence of two morphologically identical
but genetically distinct human parasites: E. histolytica, the aetiological agent
of invasive intestinal and extraintestinal amoebiasis, and Entamoeba dispar,
a non-pathogenic intestinal parasite. Because microscopy is unable to distinguish
between these two organisms, it should no longer be relied upon to diagnose
amoebiasis. Sensitive and specific molecular techniques that are able to distinguish
E. histolytica from E. dispar have been developed recently; they include (1)
the detection of an E. histolytica antigen using an enzyme-linked immunosorbent
assay (ELISA), (2) the use of the polymerase chain reaction (PCR) to amplify
amoebic DNA, and (3) the culture of stool samples followed by isoenzyme analysis.
Of these three test methods, only antigen detection using ELISA can be performed
rapidly and easily, making it the diagnostic test method of choice for clinical
use in the developing world, where the morbidity and mortality caused by E.
histolytica are greatest. However, the PCR method is a powerful tool for the
genetic typing of different amoebic strains. Together these two methods should
result in both improved clinical diagnosis and treatment of amoebiasis, and
a greater understanding of the epidemiology of E. histolytica. Such knowledge
will not only assist public health efforts to control amoebiasis, but also facilitate
the careful testing of the anti-amoebic vaccines that are currently being developed.
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Affiliation(s)
- C D Huston
- University of Virginia Health Sciences Center, MR-4 Building, Room 2115, Charlottesville, VA 22908, USA
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Vincent MS, Roessner K, Sellati T, Huston CD, Sigal LH, Behar SM, Radolf JD, Budd RC. Lyme Arthritis Synovial γδ T Cells Respond to Borrelia burgdorferi Lipoproteins and Lipidated Hexapeptides. The Journal of Immunology 1998. [DOI: 10.4049/jimmunol.161.10.5762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Lyme arthritis synovial fluid contains a large proportion of γδ T cells that proliferates upon stimulation with the causative spirochete, Borrelia burgdorferi. A panel of Borrelia-reactive γδ T cell clones was derived from synovial fluid of two patients with Lyme arthritis. Each of six γδ clones from one patient used the Vδ1 TCR segment but had otherwise unique CDR3 sequences and diverse Vγ segment usage. Stimulation of the Vδ1 clones was optimal in the presence of Borrelia, dendritic cells, and exogenous IL-2, which was reflected by proliferation, TCR down-modulation, as well as induction of CD25 and Fas ligand expression. Stimulation by B. burgdorferi-pulsed dendritic cells withstood chemical fixation and was not restricted to class I or class II MHC, CD1a, CD1b, or CD1c. In contrast, anti-γδ antibody potently inhibited proliferation. Extraction of B. burgdorferi lipoproteins with Triton X-114 enriched for the stimulatory component. This was confirmed using lipidated vs nonlipidated hexapeptides of Borrelia outer surface proteins. These observations suggest that synovial Vδ1 T cells may mediate an innate immune response to common lipoprotein products of spirochetes.
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Affiliation(s)
- Michael S. Vincent
- *Divisions of Immunobiology and Rheumatology, Department of Medicine, University of Vermont College of Medicine, Burlington, VT 05405; Departments of
| | - Karen Roessner
- *Divisions of Immunobiology and Rheumatology, Department of Medicine, University of Vermont College of Medicine, Burlington, VT 05405; Departments of
| | | | - Christopher D. Huston
- *Divisions of Immunobiology and Rheumatology, Department of Medicine, University of Vermont College of Medicine, Burlington, VT 05405; Departments of
| | - Leonard H. Sigal
- §Department of Medicine, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick, NJ 08903; and
| | - Samuel M. Behar
- ¶Lymphocyte Biology Section, Division of Rheumatology and Immunology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
| | - Justin D. Radolf
- †Internal Medicine and
- ‡Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75235
| | - Ralph C. Budd
- *Divisions of Immunobiology and Rheumatology, Department of Medicine, University of Vermont College of Medicine, Burlington, VT 05405; Departments of
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Vincent MS, Roessner K, Sellati T, Huston CD, Sigal LH, Behar SM, Radolf JD, Budd RC. Lyme arthritis synovial gamma delta T cells respond to Borrelia burgdorferi lipoproteins and lipidated hexapeptides. J Immunol 1998; 161:5762-71. [PMID: 9820558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Lyme arthritis synovial fluid contains a large proportion of gamma delta T cells that proliferates upon stimulation with the causative spirochete, Borrelia burgdorferi. A panel of Borrelia-reactive gamma delta T cell clones was derived from synovial fluid of two patients with Lyme arthritis. Each of six gamma delta clones from one patient used the V delta 1 TCR segment but had otherwise unique CDR3 sequences and diverse V gamma segment usage. Stimulation of the V delta 1 clones was optimal in the presence of Borrelia, dendritic cells, and exogenous IL-2, which was reflected by proliferation, TCR down-modulation, as well as induction of CD25 and Fas ligand expression. Stimulation by B. burgdorferi-pulsed dendritic cells withstood chemical fixation and was not restricted to class I or class II MHC, CD1a, CD1b, or CD1c. In contrast, anti-gamma delta antibody potently inhibited proliferation. Extraction of B. burgdorferi lipoproteins with Triton X-114 enriched for the stimulatory component. This was confirmed using lipidated vs nonlipidated hexapeptides of Borrelia outer surface proteins. These observations suggest that synovial V delta 1 T cells may mediate an innate immune response to common lipoprotein products of spirochetes.
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Affiliation(s)
- M S Vincent
- Department of Medicine, University of Vermont College of Medicine, Burlington 05405-0068, USA
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Abstract
Entamoeba histolytica, the causative organism of invasive intestinal and extraintestinal amebiasis, infects approximately 50 million people each year, causing an estimated 40 to 100 thousand deaths annually. Because amebae only infect humans and some higher non-human primates, an anti-amebic vaccine could theoretically eradicate the organism. Uncontrolled epidemiologic studies indicate that acquired immunity to amebic infection probably occurs and that such a vaccine might be feasible. Application of molecular biologic techniques has led to rapid progress towards understanding how Entamoeba histolytica causes disease, and to the identification of several amebic proteins associated with virulence. These proteins are now being evaluated as potential vaccine components. Parenteral and oral vaccine preparations containing recombinant amebic proteins have been effective in preventing disease in a gerbil model of amebic liver abscess. Although systemic and mucosal cellular and humoral immunity both appear to play a role in protection against Entamoeba histolytica, the relative importance of each in the human immune response remains unknown. No animal model of intestinal amebiasis currently exists, moreover, so it has been impossible to evaluate protection against colonization and colitis. Further investigation of the fundamental mechanisms by which Entamoeba histolytica causes disease and of the human immune response to amebic infection is necessary to assess the true feasibility of an anti-amebic vaccine.
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Affiliation(s)
- C D Huston
- Department of Internal Medicine, University of Vermont College of Medicine, Burlington 05401, USA
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