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Risch F, Scheunemann JF, Reichwald JJ, Lenz B, Ehrens A, Gal J, Fercoq F, Koschel M, Fendler M, Hoerauf A, Martin C, Hübner MP. The efficacy of the benzimidazoles oxfendazole and flubendazole against Litomosoides sigmodontis is dependent on the adaptive and innate immune system. Front Microbiol 2023; 14:1213143. [PMID: 37440891 PMCID: PMC10335397 DOI: 10.3389/fmicb.2023.1213143] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/09/2023] [Indexed: 07/15/2023] Open
Abstract
Filarial nematodes can cause debilitating diseases such as lymphatic filariasis and onchocerciasis. Oxfendazole (OXF) is one promising macrofilaricidal candidate with improved oral availability compared to flubendazole (FBZ), and OXF is currently under preparation for phase 2 clinical trials in filariasis patients. This study aimed to investigate the immune system's role during treatment with OXF and FBZ and explore the potential to boost the treatment efficacy via stimulation of the immune system. Wild type (WT) BALB/c, eosinophil-deficient ΔdblGata1, IL-4r/IL-5-/-, antibody-deficient μMT and B-, T-, NK-cell and ILC-deficient Rag2/IL-2rγ-/- mice were infected with the rodent filaria Litomosoides sigmodontis and treated with an optimal and suboptimal regimen of OXF and FBZ for up to 5 days. In the second part, WT mice were treated for 2-3 days with a combination of OXF and IL-4, IL-5, or IL-33. Treatment of WT mice reduced the adult worm burden by up to 94% (OXF) and 100% (FBZ) compared to vehicle controls. In contrast, treatment efficacy was lower in all immunodeficient strains with a reduction of up to 90% (OXF) and 75% (FBZ) for ΔdblGata1, 50 and 92% for IL-4r/IL-5-/-, 64 and 78% for μMT or 0% for Rag2/IL-2rγ-/- mice. The effect of OXF on microfilariae and embryogenesis displayed a similar pattern, while FBZ's ability to prevent microfilaremia was independent of the host's immune status. Furthermore, flow cytometric analysis revealed strain-and treatment-specific immunological changes. The efficacy of a shortened 3-day treatment of OXF (-33% adult worms vs. vehicle) could be boosted to a 91% worm burden reduction via combination with IL-5, but not IL-4 or IL-33. Our results suggest that various components of the immune system support the filaricidal effect of benzimidazoles in vivo and present an opportunity to boost treatment efficacy.
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Affiliation(s)
- Frederic Risch
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Johanna F. Scheunemann
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Julia J. Reichwald
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Benjamin Lenz
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Alexandra Ehrens
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
| | - Joséphine Gal
- Unité Molécules de Communication et Adaptation des Microorganismes, Sorbonne Université, Muséum national d’Histoire naturelle, CNRS, Paris, France
| | - Frédéric Fercoq
- Unité Molécules de Communication et Adaptation des Microorganismes, Sorbonne Université, Muséum national d’Histoire naturelle, CNRS, Paris, France
| | - Marianne Koschel
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Martina Fendler
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Achim Hoerauf
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
| | - Coralie Martin
- Unité Molécules de Communication et Adaptation des Microorganismes, Sorbonne Université, Muséum national d’Histoire naturelle, CNRS, Paris, France
| | - Marc P. Hübner
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
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2
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Multivariate chemogenomic screening prioritizes new macrofilaricidal leads. Commun Biol 2023; 6:44. [PMID: 36639423 PMCID: PMC9839782 DOI: 10.1038/s42003-023-04435-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 01/05/2023] [Indexed: 01/15/2023] Open
Abstract
Development of direct acting macrofilaricides for the treatment of human filariases is hampered by limitations in screening throughput imposed by the parasite life cycle. In vitro adult screens typically assess single phenotypes without prior enrichment for chemicals with antifilarial potential. We developed a multivariate screen that identified dozens of compounds with submicromolar macrofilaricidal activity, achieving a hit rate of >50% by leveraging abundantly accessible microfilariae. Adult assays were multiplexed to thoroughly characterize compound activity across relevant parasite fitness traits, including neuromuscular control, fecundity, metabolism, and viability. Seventeen compounds from a diverse chemogenomic library elicited strong effects on at least one adult trait, with differential potency against microfilariae and adults. Our screen identified five compounds with high potency against adults but low potency or slow-acting microfilaricidal effects, at least one of which acts through a novel mechanism. We show that the use of microfilariae in a primary screen outperforms model nematode developmental assays and virtual screening of protein structures inferred with deep learning. These data provide new leads for drug development, and the high-content and multiplex assays set a new foundation for antifilarial discovery.
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3
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Gencheva R, Cheng Q, Arnér ESJ. Thioredoxin reductase selenoproteins from different organisms as potential drug targets for treatment of human diseases. Free Radic Biol Med 2022; 190:320-338. [PMID: 35987423 DOI: 10.1016/j.freeradbiomed.2022.07.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/25/2022] [Accepted: 07/26/2022] [Indexed: 11/15/2022]
Abstract
Human thioredoxin reductase (TrxR) is a selenoprotein with a central role in cellular redox homeostasis, utilizing a highly reactive and solvent-exposed selenocysteine (Sec) residue in its active site. Pharmacological modulation of TrxR can be obtained with several classes of small compounds showing different mechanisms of action, but most often dependent upon interactions with its Sec residue. The clinical implications of TrxR modulation as mediated by small compounds have been studied in diverse diseases, from rheumatoid arthritis and ischemia to cancer and parasitic infections. The possible involvement of TrxR in these diseases was in some cases serendipitously discovered, by finding that existing clinically used drugs are also TrxR inhibitors. Inhibiting isoforms of human TrxR is, however, not the only strategy for human disease treatment, as some pathogenic parasites also depend upon Sec-containing TrxR variants, including S. mansoni, B. malayi or O. volvulus. Inhibiting parasite TrxR has been shown to selectively kill parasites and can thus become a promising treatment strategy, especially in the context of quickly emerging resistance towards other drugs. Here we have summarized the basis for the targeting of selenoprotein TrxR variants with small molecules for therapeutic purposes in different human disease contexts. We discuss how Sec engagement appears to be an indispensable part of treatment efficacy and how some therapeutically promising compounds have been evaluated in preclinical or clinical studies. Several research questions remain before a wider application of selenoprotein TrxR inhibition as a first-line treatment strategy might be developed. These include further mechanistic studies of downstream effects that may mediate treatment efficacy, identification of isoform-specific enzyme inhibition patterns for some given therapeutic compounds, and the further elucidation of cell-specific effects in disease contexts such as in the tumor microenvironment or in host-parasite interactions, and which of these effects may be dependent upon the specific targeting of Sec in distinct TrxR isoforms.
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Affiliation(s)
- Radosveta Gencheva
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, 17177, Sweden
| | - Qing Cheng
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, 17177, Sweden
| | - Elias S J Arnér
- Division of Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, 17177, Sweden; Department of Selenoprotein Research, National Tumor Biology Laboratory, National Institute of Oncology, 1122, Budapest, Hungary.
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4
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Hawryluk N, Robinson D, Shen Y, Kyne G, Bedore M, Menon S, Canan S, von Geldern T, Townson S, Gokool S, Ehrens A, Koschel M, Lhermitte-Vallarino N, Martin C, Hoerauf A, Hernandez G, Dalvie D, Specht S, Hübner MP, Scandale I. Discovery of Substituted Di(pyridin-2-yl)-1,2,4-thiadiazol-5-amines as Novel Macrofilaricidal Compounds for the Treatment of Human Filarial Infections. J Med Chem 2022; 65:11388-11403. [PMID: 35972896 PMCID: PMC9421654 DOI: 10.1021/acs.jmedchem.2c00960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Filarial diseases, including lymphatic filariasis and onchocerciasis, are considered among the most devastating of all tropical diseases, affecting about 145 million people worldwide. Efforts to control and eliminate onchocerciasis are impeded by a lack of effective treatments that target the adult filarial stage. Herein, we describe the discovery of a series of substituted di(pyridin-2-yl)-1,2,4-thiadiazol-5-amines as novel macrofilaricides for the treatment of human filarial infections.
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Affiliation(s)
- Natalie Hawryluk
- Bristol Myers Squibb, San Diego, California 92121, United States
| | - Dale Robinson
- Bristol Myers Squibb, San Diego, California 92121, United States
| | - Yixing Shen
- Bristol Myers Squibb, San Diego, California 92121, United States
| | - Graham Kyne
- Zoetis, Kalamazoo, Michigan 49001, United States
| | | | - Sanjay Menon
- Zoetis, Kalamazoo, Michigan 49001, United States
| | - Stacie Canan
- Bristol Myers Squibb, San Diego, California 92121, United States
| | | | - Simon Townson
- Northwick Park Institute for Medical Research, London HA1 3UJ, UK
| | - Suzanne Gokool
- Northwick Park Institute for Medical Research, London HA1 3UJ, UK
| | - Alexandra Ehrens
- Institute for Medical Microbiology, Immunology & Parasitology, University Hospital Bonn, 53127 Bonn, Germany.,German Center for Infection Research (DZIF), partner site Bonn-Cologne, 53127 Bonn, Germany
| | - Marianne Koschel
- Institute for Medical Microbiology, Immunology & Parasitology, University Hospital Bonn, 53127 Bonn, Germany
| | - Nathaly Lhermitte-Vallarino
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM, UMR 7245), Muséum national d'Histoire Naturelle, Paris 75005, France
| | - Coralie Martin
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM, UMR 7245), Muséum national d'Histoire Naturelle, Paris 75005, France
| | - Achim Hoerauf
- Institute for Medical Microbiology, Immunology & Parasitology, University Hospital Bonn, 53127 Bonn, Germany.,German Center for Infection Research (DZIF), partner site Bonn-Cologne, 53127 Bonn, Germany
| | | | - Deepak Dalvie
- Bristol Myers Squibb, San Diego, California 92121, United States
| | - Sabine Specht
- Institute for Medical Microbiology, Immunology & Parasitology, University Hospital Bonn, 53127 Bonn, Germany.,Drugs for Neglected Diseases Initiative, Geneva 1204, Switzerland
| | - Marc Peter Hübner
- Institute for Medical Microbiology, Immunology & Parasitology, University Hospital Bonn, 53127 Bonn, Germany.,German Center for Infection Research (DZIF), partner site Bonn-Cologne, 53127 Bonn, Germany
| | - Ivan Scandale
- Drugs for Neglected Diseases Initiative, Geneva 1204, Switzerland
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5
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Biamonte MA, Cantey PT, Coulibaly YI, Gass KM, Hamill LC, Hanna C, Lammie PJ, Kamgno J, Nutman TB, Oguttu DW, Sankara DP, Stolk WA, Unnasch TR. Onchocerciasis: Target product profiles of in vitro diagnostics to support onchocerciasis elimination mapping and mass drug administration stopping decisions. PLoS Negl Trop Dis 2022; 16:e0010682. [PMID: 35921329 PMCID: PMC9377578 DOI: 10.1371/journal.pntd.0010682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 08/15/2022] [Accepted: 07/20/2022] [Indexed: 11/19/2022] Open
Abstract
In June 2021, the World Health Organization (WHO), recognizing the need for new diagnostics to support the control and elimination of onchocerciasis, published the target product profiles (TPPs) of new tests that would support the two most immediate needs: (a) mapping onchocerciasis in areas of low prevalence and (b) deciding when to stop mass drug administration programs. In both instances, the test should ideally detect an antigen specific for live, adult O. volvulus female worms. The preferred format is a field-deployable rapid test. For mapping, the test needs to be ≥ 60% sensitive and ≥ 99.8% specific, while to support stopping decisions, the test must be ≥ 89% sensitive and ≥ 99.8% specific. The requirement for extremely high specificity is dictated by the need to detect with sufficient statistical confidence the low seroprevalence threshold set by WHO. Surveys designed to detect a 1–2% prevalence of a given biomarker, as is the case here, cannot tolerate more than 0.2% of false-positives. Otherwise, the background noise would drown out the signal. It is recognized that reaching and demonstrating such a stringent specificity criterion will be challenging, but test developers can expect to be assisted by national governments and implementing partners for adequately powered field validation. River blindness, also known as onchocerciasis, affects 21 million people, predominantly in sub-Saharan Africa. For decades, the international community has fought this disease through mass drug administration (MDA) programs focused on controlling morbidity in areas of high prevalence. Now, as part of their 2021–2030 Roadmap for Neglected Tropical Diseases, the World Health Organization (WHO) has set an ambitious goal, shifting from controlling to eliminating onchocerciasis. This implies addressing areas of low infection prevalence. As a result, new diagnostics tools are required to identify and map areas of low onchocerciasis prevalence and to help decide where to initiate MDA. Similarly, new diagnostics are required to decide when the prevalence of onchocerciasis is sufficiently low to justify stopping MDA. A WHO-appointed independent panel, the Diagnostics Technical Advisory Group for Neglected Tropical Diseases, and its subgroup specific to onchocerciasis, have established the desired Target Product Profiles (TPPs) for such new tests. The TPPs were posted in June 2021 on the WHO website. This article describes the methodology used to produce the TPPs, with an emphasis on calculating the required sensitivity and specificity characteristics.
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Affiliation(s)
- Marco A. Biamonte
- Drugs & Diagnostics for Tropical Diseases, San Diego, California, United States of America
- * E-mail:
| | - Paul T. Cantey
- Division of Parasitic Diseases and Malaria, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Yaya I. Coulibaly
- Mali International Center for Excellence in Research, Faculty of Medicine and Odonto-Stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali, Dermatology Hospital of Bamako, Bamako, Mali
| | - Katherine M. Gass
- Neglected Tropical Diseases Support Center, Task Force for Global Health, Decatur, Georgia, United States of America
| | | | - Christopher Hanna
- Global Project Partners, Oakland, California, United States of America
| | - Patrick J. Lammie
- Neglected Tropical Diseases Support Center, Task Force for Global Health, Decatur, Georgia, United States of America
| | - Joseph Kamgno
- Centre for Research on Filariasis and other Tropical Diseases, Yaoundé, Cameroon, Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon
| | - Thomas B. Nutman
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America
| | - David W. Oguttu
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Dieudonné P. Sankara
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Wilma A. Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Thomas R. Unnasch
- Global Health Infectious Disease Research Program, University of South Florida, Tampa, Florida, United States of America
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6
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Hawryluk N, Zhiru L, Carlow C, Gokool S, Townson S, Kreiss T, Chojnowski A, Prorok M, Siekierka J, Ehrens A, Koschel M, Lhermitte-Vallarino N, Martin C, Hoerauf A, Hernandez G, Canan S, Khetani V, Zeldis J, Specht S, Hübner MP, Scandale I. Filarial nematode phenotypic screening cascade to identify compounds with anti-parasitic activity for drug discovery optimization. Int J Parasitol Drugs Drug Resist 2022; 19:89-97. [PMID: 35834918 PMCID: PMC9278491 DOI: 10.1016/j.ijpddr.2022.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 06/13/2022] [Accepted: 06/13/2022] [Indexed: 11/18/2022]
Abstract
Filarial diseases, including lymphatic filariasis and onchocerciasis, are considered among the most devastating of all tropical diseases, affecting over 86 million people worldwide. To control and more rapidly eliminate onchocerciasis requires treatments that target the adult stage of the parasite. Drug discovery efforts are challenged by the lack of preclinical animal models using the human-pathogenic filariae, requiring the use of surrogate parasites for Onchocerca volvulus for both ex vivo and in vivo evaluation. Herein, we describe a platform utilizing phenotypic ex vivo assays consisting of the free-living nematode Caenorhabditis elegans, microfilariae and adult filariae of the bovine filariae Onchocerca lienalis and Onchocerca gutturosa, respectively, as well as microfilariae and adult filariae of the feline filariae Brugia pahangi, the rodent filariae Litomosoides sigmodontis and the human-pathogenic filariae Brugia malayi to assess activity across various surrogate parasites. Utilization of those surrogate nematodes for phenotypic ex vivo assays in order to assess activity across various parasites led to the successful establishment of a screening cascade and identification of multiple compounds with potential macrofilaricidal activity and desirable physicochemical, MW = 200-400 and low lipophilicity, logP <4, and pharmacokinetic properties, rat and human liver S9 stability of ≥70% remaining at 60 min, and AUC exposures above 3 μM h. This platform demonstrated the successful establishment of a screening cascade which resulted in the discovery of potential novel macrofilaricidal compounds for futher drug discovery lead optimization efforts. This screening cascade identified two distinct chemical series wherein one compound produced a significant 68% reduction of adult Litomosoides sigmodontis in the mouse model. Successful demonstration of efficacy prompted lead optimization medicinal chemistry efforts for this novel series.
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Affiliation(s)
| | - Li Zhiru
- New England Biolabs, Ipswich, MA, USA
| | | | - Suzanne Gokool
- Northwick Park Institute for Medical Research, London, UK
| | - Simon Townson
- Northwick Park Institute for Medical Research, London, UK
| | - Tamara Kreiss
- Sokol Institute of Pharmaceutical Life Sciences, Montclair State University, Montclair, NJ, USA
| | - Agnieszka Chojnowski
- Sokol Institute of Pharmaceutical Life Sciences, Montclair State University, Montclair, NJ, USA
| | - Monika Prorok
- Sokol Institute of Pharmaceutical Life Sciences, Montclair State University, Montclair, NJ, USA
| | - John Siekierka
- Sokol Institute of Pharmaceutical Life Sciences, Montclair State University, Montclair, NJ, USA
| | - Alexandra Ehrens
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany; German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
| | - Marianne Koschel
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany
| | | | - Coralie Martin
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM, UMR 7245), Muséum national d'Histoire naturelle, Paris, France
| | - Achim Hoerauf
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany; German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
| | | | | | | | | | - Sabine Specht
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany; Drugs for Neglected Diseases Initiative, Geneva, Switzerland
| | - Marc P Hübner
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Germany; German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany
| | - Ivan Scandale
- Drugs for Neglected Diseases Initiative, Geneva, Switzerland
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7
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Biochemical and structural characterizations of thioredoxin reductase selenoproteins of the parasitic filarial nematodes Brugia malayi and Onchocerca volvulus. Redox Biol 2022; 51:102278. [PMID: 35276442 PMCID: PMC8914392 DOI: 10.1016/j.redox.2022.102278] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 03/02/2022] [Indexed: 01/21/2023] Open
Abstract
Enzymes in the thiol redox systems of microbial pathogens are promising targets for drug development. In this study we characterized the thioredoxin reductase (TrxR) selenoproteins from Brugia malayi and Onchocerca volvulus, filarial nematode parasites and causative agents of lymphatic filariasis and onchocerciasis, respectively. The two filarial enzymes showed similar turnover numbers and affinities for different thioredoxin (Trx) proteins, but with a clear preference for the autologous Trx. Human TrxR1 (hTrxR1) had a high and similar specific activity versus the human and filarial Trxs, suggesting that, in vivo, hTrxR1 could possibly be the reducing agent of parasite Trxs once they are released into the host. Both filarial TrxRs were efficiently inhibited by auranofin and by a recently described inhibitor of human TrxR1 (TRi-1), but not as efficiently by the alternative compound TRi-2. The enzyme from B. malayi was structurally characterized also in complex with NADPH and auranofin, producing the first crystallographic structure of a nematode TrxR. The protein represents an unusual fusion of a mammalian-type TrxR protein architecture with an N-terminal glutaredoxin-like (Grx) domain lacking typical Grx motifs. Unlike thioredoxin glutathione reductases (TGRs) found in platyhelminths and mammals, which are also Grx–TrxR domain fusion proteins, the TrxRs from the filarial nematodes lacked glutathione disulfide reductase and Grx activities. The structural determinations revealed that the Grx domain of TrxR from B. malayi contains a cysteine (C22), conserved in TrxRs from clade IIIc nematodes, that directly interacts with the C-terminal cysteine-selenocysteine motif of the homo-dimeric subunit. Interestingly, despite this finding we found that altering C22 by mutation to serine did not affect enzyme catalysis. Thus, although the function of the Grx domain in these filarial TrxRs remains to be determined, the results obtained provide insights on key properties of this important family of selenoprotein flavoenzymes that are potential drug targets for treatment of filariasis.
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8
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Risch F, Ritter M, Hoerauf A, Hübner MP. Human filariasis-contributions of the Litomosoides sigmodontis and Acanthocheilonema viteae animal model. Parasitol Res 2021; 120:4125-4143. [PMID: 33547508 PMCID: PMC8599372 DOI: 10.1007/s00436-020-07026-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/20/2020] [Indexed: 12/16/2022]
Abstract
Filariae are vector-borne parasitic nematodes that are endemic worldwide, in tropical and subtropical regions. Important human filariae spp. include Onchocerca volvulus, Wuchereria bancrofti and Brugia spp., and Loa loa and Mansonella spp. causing onchocerciasis (river blindness), lymphatic filariasis (lymphedema and hydrocele), loiasis (eye worm), and mansonelliasis, respectively. It is estimated that over 1 billion individuals live in endemic regions where filarial diseases are a public health concern contributing to significant disability adjusted life years (DALYs). Thus, efforts to control and eliminate filarial diseases were already launched by the WHO in the 1970s, especially against lymphatic filariasis and onchocerciasis, and are mainly based on mass drug administration (MDA) of microfilaricidal drugs (ivermectin, diethylcarbamazine, albendazole) to filarial endemic areas accompanied with vector control strategies with the goal to reduce the transmission. With the United Nations Sustainable Development Goals (SDGs), it was decided to eliminate transmission of onchocerciasis and stop lymphatic filariasis as a public health problem by 2030. It was also requested that novel drugs and treatment strategies be developed. Mouse models provide an important platform for anti-filarial drug research in a preclinical setting. This review presents an overview about the Litomosoides sigmodontis and Acanthocheilonema viteae filarial mouse models and their role in immunological research as well as preclinical studies about novel anti-filarial drugs and treatment strategies.
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Affiliation(s)
- Frederic Risch
- Institute for Medical Microbiology, Immunology and Parasitology (IMMIP), University Hospital Bonn, Bonn, Germany
| | - Manuel Ritter
- Institute for Medical Microbiology, Immunology and Parasitology (IMMIP), University Hospital Bonn, Bonn, Germany
| | - Achim Hoerauf
- Institute for Medical Microbiology, Immunology and Parasitology (IMMIP), University Hospital Bonn, Bonn, Germany
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn, Germany
| | - Marc P Hübner
- Institute for Medical Microbiology, Immunology and Parasitology (IMMIP), University Hospital Bonn, Bonn, Germany.
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn, Germany.
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9
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Jawahar S, Tricoche N, Bulman CA, Sakanari J, Lustigman S. Drugs that target early stages of Onchocerca volvulus: A revisited means to facilitate the elimination goals for onchocerciasis. PLoS Negl Trop Dis 2021; 15:e0009064. [PMID: 33600426 PMCID: PMC7891776 DOI: 10.1371/journal.pntd.0009064] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Several issues have been identified with the current programs for the elimination of onchocerciasis that target only transmission by using mass drug administration (MDA) of the drug ivermectin. Alternative and/or complementary treatment regimens as part of a more comprehensive strategy to eliminate onchocerciasis are needed. We posit that the addition of “prophylactic” drugs or therapeutic drugs that can be utilized in a prophylactic strategy to the toolbox of present microfilaricidal drugs and/or future macrofilaricidal treatment regimens will not only improve the chances of meeting the elimination goals but may hasten the time to elimination and also will support achieving a sustained elimination of onchocerciasis. These “prophylactic” drugs will target the infective third- (L3) and fourth-stage (L4) larvae of Onchocerca volvulus and consequently prevent the establishment of new infections not only in uninfected individuals but also in already infected individuals and thus reduce the overall adult worm burden and transmission. Importantly, an effective prophylactic treatment regimen can utilize drugs that are already part of the onchocerciasis elimination program (ivermectin), those being considered for MDA (moxidectin), and/or the potential macrofilaricidal drugs (oxfendazole and emodepside) currently under clinical development. Prophylaxis of onchocerciasis is not a new concept. We present new data showing that these drugs can inhibit L3 molting and/or inhibit motility of L4 at IC50 and IC90 that are covered by the concentration of these drugs in plasma based on the corresponding pharmacological profiles obtained in human clinical trials when these drugs were tested using various doses for the therapeutic treatments of various helminth infections.
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Affiliation(s)
- Shabnam Jawahar
- Molecular Parasitology, Lindsey F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - Nancy Tricoche
- Molecular Parasitology, Lindsey F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - Christina A Bulman
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Judy Sakanari
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Sara Lustigman
- Molecular Parasitology, Lindsey F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
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Zoonotic Implications of Onchocerca Species on Human Health. Pathogens 2020; 9:pathogens9090761. [PMID: 32957647 PMCID: PMC7560048 DOI: 10.3390/pathogens9090761] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/10/2020] [Accepted: 09/15/2020] [Indexed: 12/14/2022] Open
Abstract
The genus Onchocerca includes several species associated with ungulates as hosts, although some have been identified in canids, felids, and humans. Onchocerca species have a wide geographical distribution, and the disease they produce, onchocerciasis, is generally seen in adult individuals because of its large prepatency period. In recent years, Onchocerca species infecting animals have been found as subcutaneous nodules or invading the ocular tissues of humans; the species involved are O. lupi, O. dewittei japonica, O. jakutensis, O. gutturosa, and O. cervicalis. These findings generally involve immature adult female worms, with no evidence of being fertile. However, a few cases with fertile O. lupi, O. dewittei japonica, and O. jakutensis worms have been identified recently in humans. These are relevant because they indicate that the parasite’s life cycle was completed in the new host—humans. In this work, we discuss the establishment of zoonotic Onchocerca infections in humans, and the possibility of these infections to produce symptoms similar to human onchocerciasis, such as dermatitis, ocular damage, and epilepsy. Zoonotic onchocerciasis is thought to be an emerging human parasitic disease, with the need to take measures such as One Health Strategies, in order to identify and control new cases in humans.
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