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1.
PLoS Negl Trop Dis ; 14(9): e0008518, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32915790

RESUMO

To eliminate schistosomiasis, appropriate diagnostic tests are required to monitor its prevalence and transmission, especially in the settings with low endemicity resulting from the consecutive mass drug administration. Antibodies that react with either crude soluble schistosome egg antigens or soluble worm antigen preparations have been used to monitor infection in low-prevalence regions. However, these detection methods cannot discriminate current and past infections and are cross-reactive with other parasites because both antigens contain numerous proteins and glycans from schistosomes, and standard preparations need maintenance of the life cycle of the schistosome. To evaluate the potential utility of nine recombinant Schistosoma mansoni proteins as single defined antigens for serological diagnosis, we monitored the kinetics of antibodies to each antigen during S. mansoni infection in mice before and after the treatment with praziquantel. C57BL/6 mice were infected with 50 cercariae. The levels of immunoglobulin G (IgG) raised against five recombinant antigens (RP26, sm31, sm32, GST, and LAP1) significantly increased as early as 2-4 weeks after infection and rapidly declined by 2 weeks after the treatment, whereas those raised against crude S. mansoni egg antigens or other antigens remained elevated long after the treatment. The IgG1 raised against RP26, sm31, and serpin decreased after the treatment with praziquantel, whereas the IgE raised against serpin declined strikingly after the treatment. This study clarifies the dynamics of the serological responses to recombinant S. mansoni proteins during infection and after the treatment with praziquantel and identifies several candidate antigens with potential utility in the monitoring and surveillance of schistosomiasis toward the elimination of schistosomiasis.


Assuntos
Praziquantel/farmacologia , Schistosoma mansoni/imunologia , Esquistossomose mansoni/imunologia , Animais , Anti-Helmínticos/farmacologia , Anticorpos Anti-Helmínticos , Antígenos de Helmintos/imunologia , Feminino , Proteínas de Helminto/imunologia , Imunoglobulina G , Camundongos Endogâmicos C57BL , Proteínas Recombinantes/imunologia , Schistosoma mansoni/efeitos dos fármacos , Esquistossomose mansoni/diagnóstico , Esquistossomose mansoni/tratamento farmacológico , Serpinas
2.
PLoS Negl Trop Dis ; 14(8): e0008517, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32810153

RESUMO

Currently there is only one method of treatment for human schistosomiasis, the drug praziquantel. Strong selective pressure has caused a serious concern for a rise in resistance to praziquantel leading to the necessity for additional pharmaceuticals, with a distinctly different mechanism of action, to be used in combination therapy with praziquantel. Previous treatment of Schistosoma mansoni included the use of oxamniquine (OXA), a prodrug that is enzymatically activated in S. mansoni but is ineffective against S. haematobium and S. japonicum. The oxamniquine activating enzyme was identified as a S. mansoni sulfotransferase (SmSULT-OR). Structural data have allowed for directed drug development in reengineering oxamniquine to be effective against S. haematobium and S. japonicum. Guided by data from X-ray crystallographic studies and Schistosoma worm killing assays on oxamniquine, our structure-based drug design approach produced a robust SAR program that tested over 300 derivatives and identified several new lead compounds with effective worm killing in vitro. Previous studies resulted in the discovery of compound CIDD-0066790, which demonstrated broad-species activity in killing of schistosome species. As these compounds are racemic mixtures, we tested and demonstrate that the R enantiomer CIDD-007229 kills S. mansoni, S. haematobium and S. japonicum better than the parent drug (CIDD-0066790). The search for derivatives that kill better than CIDD-0066790 has resulted in a derivative (CIDD- 149830) that kills 100% of S. mansoni, S. haematobium and S. japonicum adult worms within 7 days. We hypothesize that the difference in activation and thus killing by the derivatives is due to the ability of the derivative to fit in the binding pocket of each sulfotransferase (SmSULT-OR, ShSULT-OR, SjSULT-OR) and to be efficiently sulfated. The purpose of this research is to develop a second drug to be used in conjunction with praziquantel to treat the major human species of Schistosoma. Collectively, our findings show that CIDD-00149830 and CIDD-0072229 are promising novel drugs for the treatment of human schistosomiasis and strongly support further development and in vivo testing.


Assuntos
Anti-Helmínticos/farmacologia , Oxamniquine/análogos & derivados , Oxamniquine/farmacologia , Schistosoma/efeitos dos fármacos , Esquistossomose/parasitologia , Animais , Anti-Helmínticos/química , Simulação por Computador , Proteínas de Helminto/química , Proteínas de Helminto/metabolismo , Humanos , Modelos Biológicos , Modelos Moleculares , Estrutura Molecular , Oxamniquine/química , Ligação Proteica
3.
Parasitol Res ; 119(8): 2371-2382, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32607709

RESUMO

After almost 50 years of praziquantel (PZQ) research, Park and Marchant (Trends Parasitol 36:182-194, 2020) described the Ca++-permeable transient receptor potential (TRP) channel Sm.TRPMPZQ in Schistosoma mansoni as target of PZQ. Here we describe the deadly cascade in schistosomes which is induced by the (R)-PZQ enantiomer that includes contemporaneous stereoselective activation of Sm.TRPMPZQ-mediated Ca++ influx, disturbed Ca++ homeostasis, Ca++-dependent spastic paralysis, and Ca++- and PZQ-dependent disruption of parasitic teguments. Under normal conditions, there is a reversible balance between bilayer, isotropic, and HII phases in biological membranes (Jouhet 2013). In vitro, we could observe an irreversible but not stereoselective transition to the HII phase in liposomes consisting of phosphatidylethanolamine (PE) and phosphatidylserine (PS), two naturally occurring phospholipids in schistosomes, by the concerted action of Ca++ and PZQ (Harder 2013). HII structures are a prerequisite for induction of fusion processes (Jouhet 2013), which, indeed, become visible as blebs, vacuolation processes, and large balloon-like surface exudates in a large variety of PZQ-sensitive parasitic flukes and cestodes after PZQ treatment. These tegument damages are irreversible. As homologs of Sm.TRPMPZQ are also present in the other trematodes S. japonicum, S. haematobium, or Clonorchis sinensis and cestodes Taenia solium, Echinococcus multilocularis, or Hymenolepis microstoma (Park and Marchant, Trends Parasitol 36:182-194, 2020), it is suggested that a similar deadly cascade will be operating generally in PZQ-sensitive parasites.


Assuntos
Cestoides/efeitos dos fármacos , Praziquantel/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Trematódeos/efeitos dos fármacos , Animais , Anti-Helmínticos/farmacologia , Anti-Helmínticos/uso terapêutico , Praziquantel/uso terapêutico , Esquistossomose mansoni/tratamento farmacológico , Esquistossomose mansoni/parasitologia , Canais de Cátion TRPM/efeitos dos fármacos
4.
Exp Parasitol ; 217: 107957, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32687847

RESUMO

The ruminant livestock production sector is under threat due to the infections with gastrointestinal nematode parasites and the subsequent development of anthelmintic resistance. One of most common and pathogenic species in small ruminants is Haemonchus contortus. The ability to control the infections with this and other gastrointestinal nematodes relies heavily on the use of anthelmintic drugs. Although resistance to all major classes of anthelmintics has been shown in H. contortus, the precise mechanism of resistance acquisition is only known for benzimidazoles. F200Y (TAC) is a common point mutation in the isotype 1 ß tubulin gene which is associated with an effective increase in the resistance towards benzimidazole drugs. Here, we show the utility of using this mutation as a marker in a droplet digital PCR assay to track how two H. contortus laboratory strains, characterized by different resistance levels, change with respect to this mutation, when subjected to increasing concentrations of thiabendazole. Additionally, we wanted to investigate whether exposure to a discriminating dose of thiabendazole in the egg hatch test resulted in the death of all H. contortus eggs with a susceptible genotype. We found the MHco5 strain to maintain an overall higher frequency of the F200Y mutation (80-100%) over all drug concentrations, whilst a steady, gradual increase from around 30%-60% was observed in the case of the MHco4 strain. This is further supported by the dose-response curves, displaying a much higher tolerance of the MHco5 strain (LD50 = 0.38 µg/ml) in comparison to the MHco4 strain (LD50 = 0.07 µg/ml) to the effects of thiabendazole. All things considered, we show that the F200Y mutation is still a viable and reliable marker for the detection and surveillance of benzimidazole drug resistance in H. contortus in Europe.


Assuntos
Anti-Helmínticos/farmacologia , Haemonchus/genética , Taxa de Mutação , Tiabendazol/farmacologia , Tubulina (Proteína)/genética , Animais , DNA de Helmintos/isolamento & purificação , Relação Dose-Resposta a Droga , Resistência a Medicamentos/genética , Frequência do Gene , Marcadores Genéticos , Genótipo , Hemoncose/parasitologia , Hemoncose/veterinária , Haemonchus/classificação , Haemonchus/efeitos dos fármacos , Dose Letal Mediana , Óvulo/efeitos dos fármacos , Fenótipo , Mutação Puntual , Reação em Cadeia da Polimerase , Ovinos , Doenças dos Ovinos/parasitologia
5.
Parasitol Res ; 119(9): 2851-2862, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32651637

RESUMO

The field strain of Haemonchus contortus has a long history of anthelmintic resistance. To understand this phenomenon, the benzimidazole resistance profile was characterized from the Malaysian field-resistant strain by integrating phenotypic, genotypic and proteomic approaches. The faecal egg count reduction test (FECRT) demonstrated that benzimidazole resistance was at a critical level in the studied strain. The primary resistance mechanism was attributed to F200Y mutation in the isotype 1 ß-tubulin gene as revealed by AS-PCR and direct sequencing. Furthermore, the protein response of the resistant strain towards benzimidazole (i.e., albendazole) treatment was investigated via two-dimensional difference gel electrophoresis (2D-DIGE) and tandem liquid chromatography-mass spectrometry (LC-MS/MS). These investigations illustrated an up-regulation of antioxidant (i.e., ATP-binding region and heat-shock protein 90, superoxide dismutase) and metabolic (i.e., glutamate dehydrogenase) enzymes and down-regulation of glutathione S-transferase, malate dehydrogenase, and other structural and cytoskeletal proteins (i.e., actin, troponin T). Findings from this study are pivotal in updating the current knowledge on anthelmintic resistance and providing new insights into the defence mechanisms of resistant nematodes towards drug treatment.


Assuntos
Albendazol/farmacologia , Anti-Helmínticos/farmacologia , Benzimidazóis/farmacologia , Resistência a Medicamentos/genética , Haemonchus/efeitos dos fármacos , Animais , Antioxidantes/metabolismo , Cromatografia Líquida , Glutamato Desidrogenase/metabolismo , Hemoncose/tratamento farmacológico , Haemonchus/genética , Reação em Cadeia da Polimerase , Proteômica , Ovinos , Doenças dos Ovinos/parasitologia , Espectrometria de Massas em Tandem , Tubulina (Proteína)/genética
6.
PLoS Negl Trop Dis ; 14(7): e0008332, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32609727

RESUMO

Treatment and control of schistosomiasis still rely on only one effective drug, praziquantel (PZQ) and, due to mass treatment, the increasing risk of selecting for schistosome strains that are resistant to PZQ has alerted investigators to the urgent need to develop novel therapeutic strategies. The histone-modifying enzymes (HMEs) represent promising targets for the development of epigenetic drugs against Schistosoma mansoni. In the present study, we targeted the S. mansoni lysine-specific demethylase 1 (SmLSD1), a transcriptional corepressor, using a novel and selective synthetic inhibitor, MC3935, which was used to treat schistosomula and adult worms in vitro. By using cell viability assays and optical and electron microscopy, we showed that treatment with MC3935 affected parasite motility, egg-laying, tegument, and cellular organelle structures, culminating in the death of schistosomula and adult worms. In silico molecular modeling and docking analysis suggested that MC3935 binds to the catalytic pocket of SmLSD1. Western blot analysis revealed that MC3935 inhibited SmLSD1 demethylation activity of H3K4me1/2. Knockdown of SmLSD1 by RNAi recapitulated MC3935 phenotypes in adult worms. RNA-Seq analysis of MC3935-treated parasites revealed significant differences in gene expression related to critical biological processes. Collectively, our findings show that SmLSD1 is a promising drug target for the treatment of schistosomiasis and strongly support the further development and in vivo testing of selective schistosome LSD1 inhibitors.


Assuntos
Inibidores Enzimáticos/farmacologia , Histona Desmetilases/antagonistas & inibidores , Schistosoma mansoni/efeitos dos fármacos , Schistosoma mansoni/ultraestrutura , Esquistossomose mansoni/tratamento farmacológico , Animais , Anti-Helmínticos/farmacologia , Resistência a Medicamentos , Microscopia Eletrônica de Varredura , Oviposição/efeitos dos fármacos , Praziquantel/farmacologia , Esquistossomose mansoni/parasitologia , Esquistossomose mansoni/patologia
7.
PLoS One ; 15(6): e0235072, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32574178

RESUMO

The abomasal parasitic nematode Haemonchus contortus can influence the abomasal microbiome of the host. On the other hand, no information occurs on the influence of the parasite on the hindgut microbiome of the host. We evaluated the impact of Haemonchus contortus on the fecal microbial community of the experimentally infected lambs treated with a mixture of medicinal herbs to ameliorate the haemonchosis. Twenty-four female lambs were divided into four groups: infected animals (Inf), infected animals supplemented with a blend of medicinal herbs (Inf+Herb), uninfected control animals (Control), and uninfected animals supplemented with medicinal herbs (C+Herb). Inf and Inf+Herb lambs were infected orally with approximately 5000 L3 larvae of a strain of H. contortus susceptible to anthelmintics (MHco1). Herb blend (Herbmix) consisted of dry medicinal plants of Althaea officinalis, Petasites hybridus, Inula helenium, Malva sylvestris, Chamomilla recutita, Plantago lanceolata, Rosmarinus officinalis, Solidago virgaurea, Fumaria officinalis, Hyssopus officinalis, Melisa officinalis, Foeniculum vulgare, and Artemisia absinthium. Each animal was fed meadow hay and a commercial concentrate (600 + 350 g DM/d). Inf+Herb and C+Herb lambs were fed Herbmix (100 g DM/d and animal). Treatment lasted for 50 days. The fecal microbial fermentation parameters (short-chain fatty acids, ammonia, and pH) were evaluated at intervals of 0, 20, 32, and 50 days. The fecal eubacterial populations were evaluated by denaturing gradient gel electrophoresis (DGGE) at day 32 when H. contortus infection was the highest. No substantial effects of the H. contortus infection and the herbal treatment on fecal microbial fermentation parameters and fecal eubacterial populations were observed. Evaluation of DGGE patterns by Principal component analysis pointed to the tendency to branch the C+Herb group from the other experimental groups on Day 32. The results indicate that hindgut microbial activity was not disturbed by H. contortus infection and herbal treatment.


Assuntos
Abomaso/efeitos dos fármacos , Sistema Digestório/efeitos dos fármacos , Hemoncose/tratamento farmacológico , Haemonchus/efeitos dos fármacos , Preparações de Plantas/farmacologia , Plantas Medicinais/química , Doenças dos Ovinos/tratamento farmacológico , Abomaso/microbiologia , Abomaso/parasitologia , Animais , Anti-Helmínticos/farmacologia , Sistema Digestório/microbiologia , Sistema Digestório/parasitologia , Quimioterapia Combinada , Fezes/microbiologia , Fezes/parasitologia , Feminino , Hemoncose/parasitologia , Hemoncose/veterinária , Haemonchus/fisiologia , Microbiota/efeitos dos fármacos , Microbiota/fisiologia , Fitoterapia/métodos , Plantas Medicinais/classificação , Ovinos , Doenças dos Ovinos/parasitologia , Especificidade da Espécie
8.
Parasitol Res ; 119(9): 3093-3097, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32591863

RESUMO

The efficacy of pyrantel pamoate, pyrvinium pamoate, ivermectin, and piperazine citrate against pinworm in cockroach was evaluated. Laboratory-reared German cockroaches naturally infected with Blatticola blattae were treated with the anthelmintics and necropsied at 3 to 35 days after treatment. Ivermectin at over 5 ppm and piperazine citrate at over 2000 ppm killed all the treated cockroaches. Pinworms were still detected in cockroaches given lower concentration of the aforementioned drugs. Administration of pyrantel pamoate (100-1000 ppm) and pyrvinium pamoate (2000 ppm) did not kill the cockroaches, and no pinworms were detected at 3 and 17 days after treatment. Thus, pyrantel pamoate and pyrvinium pamoate were found to be effective for deworming B. blattae in the German cockroaches, without causing mortality for the host. Our results showed that anthelmintics selection is essential for eradication of pinworms in cockroaches because of the toxicity for the host such as ivermectin or piperazine citrate. This is the first report of piperazine citrate toxicity in cockroaches.


Assuntos
Anti-Helmínticos/farmacologia , Baratas/parasitologia , Enterobíase/parasitologia , Enterobius/efeitos dos fármacos , Animais , Avaliação Pré-Clínica de Medicamentos , Enterobíase/tratamento farmacológico , Enterobius/fisiologia , Humanos , Ivermectina/farmacologia , Piperazinas/farmacologia , Pamoato de Pirantel/farmacologia
9.
PLoS Negl Trop Dis ; 14(5): e0007942, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32453724

RESUMO

Efforts to identify new drugs for therapeutic and preventive treatments against parasitic nematodes have gained increasing interest with expanding pathogen omics databases and drug databases from which new anthelmintic compounds might be identified. Here, a novel approach focused on integrating a pan-Nematoda multi-omics data targeted to a specific nematode organ system (the intestinal tract) with evidence-based filtering and chemogenomic screening was undertaken. Based on de novo computational target prioritization of the 3,564 conserved intestine genes in A. suum, exocytosis was identified as a high priority pathway, and predicted inhibitors of exocytosis were tested using the large roundworm (Ascaris suum larval stages), a filarial worm (Brugia pahangi adult and L3), a whipworm (Trichuris muris adult), and the non-parasitic nematode Caenorhabditis elegans. 10 of 13 inhibitors were found to cause rapid immotility in A. suum L3 larvae, and five inhibitors were effective against the three phylogenetically diverse parasitic nematode species, indicating potential for a broad spectrum anthelmintics. Several distinct pathologic phenotypes were resolved related to molting, motility, or intestinal cell and tissue damage using conventional and novel histologic methods. Pathologic profiles characteristic for each inhibitor will guide future research to uncover mechanisms of the anthelmintic effects and improve on drug designs. This progress firmly validates the focus on intestinal cell biology as a useful resource to develop novel anthelmintic strategies.


Assuntos
Anti-Helmínticos/farmacologia , Nematoides/efeitos dos fármacos , Animais , Células Cultivadas , Sistemas de Liberação de Medicamentos , Descoberta de Drogas , Intestinos/citologia , Intestinos/efeitos dos fármacos , Larva/efeitos dos fármacos
10.
Vet Parasitol ; 281: 109121, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32361524

RESUMO

The search of novel strategies for anthelmintic control is a crucial need considering the widespread increase in resistant parasitic populations in livestock. Bioactive phytochemicals may contribute to improve parasite control by enhancing the effect of existing anthelmintic drugs. The aim of the current work was to evaluate the in vivo and in vitro pharmaco-chemical interaction and the in vivo efficacy of the combination of albendazole (ABZ) with thymol (TML) in lambs naturally infected with resistant gastrointestinal nematodes. Thirty (30) lambs were allocated into three experimental groups. Each group was treated orally with either ABZ (5 mg/kg), TML (150 mg/kg, twice every 24 h) or the co-administration of both compounds. Blood samples were collected between 0 and 51 h post-treatment and TML, ABZ and its metabolites were measured by HPLC. Individual faecal samples were collected at days -1 and 14 post-treatment to perform the faecal egg count reduction test. Additionally, the effect of TML on the sulphoreduction and sulphonation of ABZ sulphoxide was assessed in vitro using ruminal content and liver microsomes, respectively. The metabolism of TML in the ruminal content was very low and the monoterpene exhibited a low degree of association with the particulate phase of the ruminal content. No changes in the pharmacokinetic behavior of ABZ sulphoxide were observed in the presence of the natural product (TML). In contrast, the ABZ sulphone Cmax and AUC were lower (P 0.002 and 0.001 respectively) in the co-administered animals (0.16 ±â€¯0.07 µg/mL and 3.63 ±â€¯1.21 µg.h/mL) compared with those that received ABZ alone (0.45 ±â€¯0.15 µg/mL and 9.50 ±â€¯2.84 µg.h/mL). TML was detected in the bloodstream between 1 and 48 h post-treatment, which indicates the time of target nematodes being exposed to the bioactive monoterpene. However, the in vivo efficacy of TML was 0% and the presence of this terpene did not increase the efficacy of ABZ. The presence of TML significantly inhibited the ruminal sulphoreduction (P 0.001) and the hepatic sulphonation (P 0.001) of ABZ sulphoxide. These observations point out that in vivo pharmaco-parasitological studies are relevant to corroborate the adverse kinetic/metabolic interactions and the efficacy of bioactive natural products combined with synthetic anthelmintics.


Assuntos
Albendazol/administração & dosagem , Resistência a Medicamentos/efeitos dos fármacos , Gastroenteropatias/tratamento farmacológico , Helmintíase Animal/tratamento farmacológico , Doenças dos Ovinos/tratamento farmacológico , Timol/administração & dosagem , Animais , Anti-Helmínticos/administração & dosagem , Anti-Helmínticos/farmacologia , Quimioterapia Combinada , Gastroenteropatias/parasitologia , Helmintíase Animal/parasitologia , Compostos Fitoquímicos/farmacologia , Ovinos , Doenças dos Ovinos/parasitologia , Resultado do Tratamento
11.
PLoS Pathog ; 16(4): e1008465, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32271834

RESUMO

Roundworm parasite infections are a major cause of human and livestock disease worldwide and a threat to global food security. Disease control currently relies on anthelmintic drugs to which roundworms are becoming increasingly resistant. An alternative approach is control by vaccination and 'hidden antigens', components of the worm gut not encountered by the infected host, have been exploited to produce Barbervax, the first commercial vaccine for a gut dwelling nematode of any host. Here we present the structure of H-gal-GP, a hidden antigen from Haemonchus contortus, the Barber's Pole worm, and a major component of Barbervax. We demonstrate its novel architecture, subunit composition and topology, flexibility and heterogeneity using cryo-electron microscopy, mass spectrometry, and modelling. Importantly, we demonstrate that complexes with the same architecture are present in other Strongylid roundworm parasites including human hookworm. This suggests a common ancestry and the potential for development of a unified hidden antigen vaccine.


Assuntos
Endopeptidases/metabolismo , Endopeptidases/ultraestrutura , Haemonchus/imunologia , Proteínas de Helminto/metabolismo , Proteínas de Helminto/ultraestrutura , Glicoproteínas de Membrana/metabolismo , Glicoproteínas de Membrana/ultraestrutura , Animais , Anti-Helmínticos/farmacologia , Anticorpos Anti-Helmínticos , Antígenos de Helmintos/imunologia , Microscopia Crioeletrônica , Endopeptidases/imunologia , Haemonchus/patogenicidade , Proteínas de Helminto/imunologia , Glicoproteínas de Membrana/imunologia , Parasitos , Vacinação , Vacinas/imunologia
12.
Adv Parasitol ; 108: 1-45, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32291083

RESUMO

Parasitic roundworms (nematodes) cause substantial morbidity and mortality in animals worldwide. Anthelmintic treatment is central to controlling these worms, but widespread resistance to most of the commercially available anthelmintics for veterinary and agricultural use is compromising control, such that there is an urgency to discover new and effective drugs. The purpose of this article is to review information on parasitic nematodes, the treatment and control of parasitic nematode infections and aspects of discovering new anthelmintics in the context of anthelmintic resistance problems, and then to discuss some progress that our group has made in identifying selected compounds with activity against nematodes. The focus of our recent work has been on discovering new chemical entities and known drugs with anthelmintic activities against Haemonchus contortus as well as other socioeconomically important parasitic nematodes for subsequent development. Using whole worm-based phenotypic assays, we have been screening compound collections obtained via product-development-partnerships and/or collaborators, and active compounds have been assessed for their potential as anthelmintic candidates. Following the screening of 15,333 chemicals from five distinct compound collections against H. contortus, we have discovered one new chemical entity (designated SN00797439), two human kinase inhibitors (SNS-032 and AG-1295), 14 tetrahydroquinoxaline analogues, one insecticide (tolfenpyrad) and two tolfenpyrad (pyrazole-5-carboxamide) derivatives (a-15 and a-17) with anthelmintic activity in vitro. Some of these 20 'hit' compounds have selectivity against H. contortus in vitro when compared to particular human cell lines. In our opinion, some of these compounds could represent starting points for 'lead' development. Accordingly, the next research steps to be pursued include: (i) chemical optimisation of representative chemicals via structure-activity relationship (SAR) evaluations; (ii) assessment of the breadth of spectrum of anthelmintic activity on a range of other parasitic nematodes, such as strongyloids, ascaridoids, enoplids and filarioids; (iii) detailed investigations of the absorption, distribution, metabolism, excretion and toxicity (ADMET) of optimised chemicals with broad nematocidal or nematostatic activity; and (iv) establishment of the modes of action of lead candidates.


Assuntos
Anti-Helmínticos/farmacologia , Descoberta de Drogas/tendências , Infecções por Nematoides/tratamento farmacológico , Animais , Humanos , Nematoides/efeitos dos fármacos
13.
Artigo em Inglês | MEDLINE | ID: mdl-32251964

RESUMO

Benzimidazoles (BZ) have been the anthelmintic of choice for controlling Nematodirus battus infections since their release in the 1950s. Despite heavy reliance on this single anthelmintic drug class, resistance was not identified in this nematode until 2010 (Mitchell et al., 2011). The study aimed to explore the prevalence of BZ-resistance mutations in N. battus from UK sheep flocks using deep amplicon sequencing and pyrosequencing platforms. Based on evidence from other gastrointestinal nematodes, resistance in N. battus is likely to be conferred by single nucleotide polymorphisms (SNP) within the ß-tubulin isotype 1 locus at codons 167, 198 and 200. Pyrosequencing and deep amplicon sequencing assays were designed to identify the F167Y (TTC to TAC), E198A (GAA to GCA) and F200Y (TTC to TAC) SNPs. Nematodirus battus populations from 253 independent farms were analysed by pyrosequencing; 174 farm populations were included in deep amplicon sequencing and 170 were analysed using both technologies. F200Y was the most prevalent SNP identified throughout the UK, in 12-27% of the populations tested depending on assay, at a low overall individual frequency of 2.2 ±â€¯0.6% (mean ±â€¯SEM, based on pyrosequencing results). Four out of the five populations with high frequencies (>20%) of the F200Y mutation were located in NW England. The F167Y SNP was identified, for the first time in this species, in four of the populations tested at a low frequency (1.2% ±â€¯0.01), indicating the early emergence of the mutation. E198A or E198L were not identified in any of the isolates. Results obtained were comparable between both techniques for F200Y (Lins' CCC, rc = 0.96) with discrepancies being limited to populations with low frequencies. The recent emergence of resistance in this species will provide a unique opportunity to study the early stages of anthelmintic resistance within a natural setting and track its progress in the future.


Assuntos
Benzimidazóis/farmacologia , Resistência a Medicamentos/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Nematodirus/genética , Doenças dos Ovinos/parasitologia , Infecções por Strongylida/veterinária , Animais , Anti-Helmínticos/farmacologia , Fazendas , Fezes/parasitologia , Frequência do Gene , Genótipo , Mutação , Nematodirus/efeitos dos fármacos , Análise de Sequência de DNA , Ovinos , Doenças dos Ovinos/tratamento farmacológico , Doenças dos Ovinos/epidemiologia , Infecções por Strongylida/tratamento farmacológico , Infecções por Strongylida/epidemiologia , Reino Unido/epidemiologia
14.
PLoS Negl Trop Dis ; 14(3): e0008220, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32226018

RESUMO

Human clonorchiasis, caused by Clonorchis sinensis, is endemic in East Asian countries. C. sinensis metacercariae excyst in the duodenum of mammalian hosts, migrate to the intrahepatic bile duct, and mature into adults in the milieu of bile. We have previously shown that newly excysted juvenile C. sinensis move chemotactically toward bile and bile acids. Here, the chemotactic behavior of adult C. sinensis (CsAd) toward bile and bile acids was investigated. CsAds moved toward 0.05-5% bile and were most attracted to 0.5% bile but moved away from 10% bile. Upon exposure to 1-10% bile, CsAds eventually stopped moving and then died quickly. Among bile acids, CsAds showed strong chemotaxis toward cholic acid (CA) and deoxycholic acid. On the contrary, CsAds repelled from lithocholic acid (LCA). Moreover, at higher than 10 mM LCA, CsAds became sluggish and eventually died. Dopamine D1 receptor antagonists (LE-300 and SKF-83566), D2/3 receptor antagonists (raclopride and its derivative CS-49612), and a dopamine re-uptake inhibitor inhibited CA-induced chemotaxis of CsAds almost completely. Clinically used antipsychotic drugs, namely chlorpromazine, haloperidol, and clozapine, are dopaminergic antagonists and are secreted into bile. They completely inhibited chemotaxis of CsAds toward CA. At the maximum doses used to treat patients, the three tested medicines only expelled 2-12% of CsAds from the experimentally infected rabbits, but reduced egg production by 64-79%. Thus, antipsychotic medicines with dopaminergic antagonism could be considered as new anthelmintic candidates for human C. sinensis infections.


Assuntos
Anti-Helmínticos/farmacologia , Antipsicóticos/farmacologia , Quimiotaxia/efeitos dos fármacos , Clonorchis sinensis/efeitos dos fármacos , Clonorchis sinensis/fisiologia , Antagonistas de Dopamina/farmacologia , Animais , Anti-Helmínticos/administração & dosagem , Antipsicóticos/administração & dosagem , Bile/metabolismo , Fatores Quimiotáticos/metabolismo , Ácido Cólico/metabolismo , Clonorquíase/tratamento farmacológico , Modelos Animais de Doenças , Antagonistas de Dopamina/administração & dosagem , Feminino , Fertilidade/efeitos dos fármacos , Humanos , Ácido Litocólico/metabolismo , Coelhos , Análise de Sobrevida , Resultado do Tratamento
15.
Parasite Immunol ; 42(7): e12708, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32145033

RESUMO

Litomosoides sigmodontis is the only filarial nematode where the full life cycle, from larval delivery to the skin through to circulating microfilaria, can be completed in immunocompetent laboratory mice. It is thus an invaluable tool for the study of filariasis. It has been used for the study of novel anti-helminthic therapeutics, the development of vaccines against filariasis, the development of immunomodulatory drugs for the treatment of inflammatory disease and the study of basic immune responses to filarial nematodes. This review will focus on the latter and aims to summarize how the L sigmodontis model has advanced our basic understanding of immune responses to helminths, led to major discoveries in macrophage biology and provided new insights into the immunological functions of the pleural cavity. Finally, and most importantly L sigmodontis represents a suitable platform to study how host genotype affects immune responses, with the potential for further discovery in myeloid cell biology and beyond.


Assuntos
Filariose/imunologia , Filarioidea/imunologia , Interações Hospedeiro-Parasita/imunologia , Animais , Anti-Helmínticos/farmacologia , Modelos Animais de Doenças , Feminino , Filariose/tratamento farmacológico , Filariose/prevenção & controle , Genótipo , Interações Hospedeiro-Parasita/genética , Estágios do Ciclo de Vida , Camundongos , Camundongos Endogâmicos BALB C , Microfilárias/imunologia , Células Mieloides/imunologia
16.
Ann Parasitol ; 66(1): 49­60, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32198995

RESUMO

Resistance of strongylids in domestic horses to benzimidazole anthelmintics (BZ) has been detected worldwide; however, information on the presence of BZ-resistance in wild equids has not been published to date. The purpose of this study was to analyze the manifestations of the BZ resistance in strongylids in domestic and wild equids kept in the Askania Nova Biosphere Reserve, Ukraine. Four species of equids: domestic horses and Shetland ponies (Equus caballus), donkeys (E. asinus), plains zebras (E. burchelli) and Grévy's zebras (E. grevyi) kept under semi-free conditions were examined using the Fecal Egg Count Reduction Test (FECRT) in order to detect the presence of resistance to the BZ anthelmintics. Analysis of long-term data (2009­2019) revealed a decrease in the efficacy of BZ drugs against strongylids in these four species of equids from 97.6% in 2009 to <75% in 2019. The efficacy of anthelmintic treatments was low in all species of equids: in plains zebras ­ 69.4%, Grévy's zebras ­ 72.7%, horses ­ 66.4%, ponies ­ 61.1% and donkeys ­ 45.2%. Ten species of cyathostomins (Cyathostomum catinatum, Cylicocyclus nassatus, C. ashworthi, C. leptostomus, Cylicostephanus calicatus, C. goldi, C. longibursatus, C. minutus, Coronocyclus labiatus, C. labratus) were found after horse deworming with albendazole. Our results are the first detection of BZ-resistance in strongylids of wild equids kept under semi-free conditions in the Reserve.


Assuntos
Albendazol , Anti-Helmínticos , Resistência a Medicamentos , Doenças dos Cavalos , Albendazol/farmacologia , Animais , Anti-Helmínticos/farmacologia , Doenças dos Cavalos/parasitologia , Cavalos , Strongyloidea/efeitos dos fármacos , Ucrânia
17.
Acta Trop ; 206: 105448, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32194066

RESUMO

Taenia crassiceps is an experimental model used for cysticercosis studies and has suffered metabolic analyzes regarding the effect of anthelminthic drugs. The metabolic analyses are useful tools to determine the drugs mode of action and the parasite`s survival mechanisms. The energetic pathways are good candidates for this kind of approach as they are essential for the parasite`s survival and adaptation to the environment. In this review we discuss the anthelminthic drugs mode of action and its metabolic impact on Taenia crassiceps cysticerci.


Assuntos
Anti-Helmínticos/farmacologia , Cisticercose/tratamento farmacológico , Taenia/efeitos dos fármacos , Animais , Humanos , Larva/efeitos dos fármacos , Larva/metabolismo , Taenia/metabolismo
18.
Parasit Vectors ; 13(1): 140, 2020 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-32178714

RESUMO

BACKGROUND: Schistosomiasis chemotherapy is largely based on praziquantel (PZQ). Although PZQ is very safe and tolerable, it does not prevent reinfection and emerging resistance is a primary concern. Recent studies have shown that the targeting of epigenetic machinery in Schistosoma mansoni may result in severe alterations in parasite development, leading to death. This new route for drug discovery in schistosomiasis has focused on classes of histone deacetylases (HDACs) and histone acetyltransferases (HATs) as epigenetic drug targets. Schistosoma histone demethylases also seem to be important in the transition of cercariae into schistosomula, as well as sexual differentiation in adult worms. METHODS: The Target-Pathogen database and molecular docking assays were used to prioritize the druggability of S. mansoni histone demethylases. The transcription profile of Smp_03400 was re-analyzed using available databases. The effect of GSK-J4 inhibitor in schistosomula and adult worms' motility/viability/oviposition was assessed by in vitro assays. Ultrastructural analysis was performed on adult worms exposed to GSK-J4 by scanning electron microscopy, while internal structures and muscle fiber integrity was investigated by confocal microscopy after Langeron's carmine or phalloidin staining. RESULTS: The present evaluation of the potential druggability of 14 annotated S. mansoni demethylase enzymes identified the S. mansoni ortholog of human KDM6A/UTX (Smp_034000) as the most suitable druggable target. In silico analysis and molecular modeling indicated the potential for cofactor displacement by the chemical probe GSK-J4. Our re-analysis of transcriptomic data revealed that Smp_034000 expression peaks at 24 h in newly transformed schistosomula and 5-week-old adult worms. Moreover, this gene was highly expressed in the testes of mature male worms compared to the rest of the parasite body. In in vitro schistosome cultures, treatment with GSK-J4 produced striking effects on schistosomula mortality and adult worm motility and mortality, as well as egg oviposition, in a dose- and time-dependent manner. Unexpectedly, western blot assays did not demonstrate overall modulation of H3K27me3 levels in response to GSK-J4. Confocal and scanning electron microscopy revealed the loss of original features in muscle fibers and alterations in cell-cell contact following GSK-J4 treatment. CONCLUSIONS: GSK-J4 presents promising potential for antischistosomal control; however, the underlying mechanisms warrant further investigation.


Assuntos
Anti-Helmínticos/farmacologia , Benzazepinas/farmacologia , Descoberta de Drogas/métodos , Histona Desmetilases com o Domínio Jumonji/antagonistas & inibidores , Modelos Moleculares , Pirimidinas/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Animais , Biologia Computacional , Epigênese Genética/efeitos dos fármacos , Feminino , Histona Desmetilases com o Domínio Jumonji/genética , Masculino , Microscopia Eletrônica de Varredura , Simulação de Acoplamento Molecular , Schistosoma mansoni/genética , Schistosoma mansoni/ultraestrutura , Esquistossomose mansoni/tratamento farmacológico , Transcriptoma
19.
Artigo em Inglês | MEDLINE | ID: mdl-32179499

RESUMO

Liver flukes include Fasciola hepatica, Fasciola gigantica, Clonorchis sinensis, Opisthorchis spp., Fascioloides magna, Gigantocotyle explanatum and Dicrocoelium spp. The two main species, F. hepatica and F. gigantica, are major parasites of livestock and infections result in huge economic losses. As with C. sinensis, Opisthorchis spp. and Dicrocoelium spp., they affect millions of people worldwide, causing severe health problems. Collectively, the group is referred to as the Food-Borne Trematodes and their true significance is now being more widely recognised. However, reports of resistance to triclabendazole (TCBZ), the most widely used anti-Fasciola drug, and to other current drugs are increasing. This is a worrying scenario. In this review, progress in understanding the mechanism(s) of resistance to TCBZ is discussed, focusing on tubulin mutations, altered drug uptake and changes in drug metabolism. There is much interest in the development of new drugs and drug combinations, the re-purposing of non-flukicidal drugs, and the development of new drug formulations and delivery systems; all this work will be reviewed. Sound farm management practices also need to be put in place, with effective treatment programmes, so that drugs can be used wisely and their efficacy conserved as much as is possible. This depends on reliable advice being given by veterinarians and other advisors. Accurate diagnosis and identification of drug-resistant fluke populations is central to effective control: to determine the actual extent of the problem and to determine how well or otherwise a treatment has worked; for research on establishing the mechanism of resistance (and identifying molecular markers of resistance); for informing treatment options; and for testing the efficacy of new drug candidates. Several diagnostic methods are available, but there are no recommended guidelines or standardised protocols in place and this is an issue that needs to be addressed.


Assuntos
Anti-Helmínticos/farmacologia , Resistência a Medicamentos , Fasciola hepatica/efeitos dos fármacos , Fígado/parasitologia , Animais , Benzimidazóis/farmacologia , Fasciola hepatica/classificação , Fasciolíase/diagnóstico , Fasciolíase/tratamento farmacológico , Fasciolíase/parasitologia , Triclabendazol/farmacologia
20.
Acta Trop ; 205: 105411, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32101761

RESUMO

Alveolar echinococcosis is one of the most dangerous parasitic zoonoses. This disease, widely distributed in the northern hemisphere, is caused by the metacestode stage of the tapeworm Echinococcus multilocularis. All surgical and non-surgical patients should perform chemotherapy with benzimidazoles, mainly with albendazole. However, the efficacy of albendazole is variable due to its deficient pharmacokinetic properties. Therefore, the need to find new therapeutic alternatives for the treatment of alveolar echinococcosis is evident. Menthol is a natural compound of low toxicity, used in industries such as cosmetics and gastronomy and generally recognized as safe by the Food and Drug Administration. In addition, menthol has important pharmacological effects and is effective against a wide variety of organisms. The development of prodrugs allows improving the pharmacokinetic properties of the parental drug. To improve lipophilicity and therefore the bioavailability of menthol, a novel prodrug called menthol-pentanol was developed by masking the functional polar group of menthol by linking n-pentanol by a carbonate bond. The aim of the current work was to evaluate the in vitro and in vivo efficacy of menthol and menthol-pentanol against E. multilocularis. Menthol-pentanol had a greater protoscolicidal effect than menthol. In addition, the prodrug demonstrated a similar clinical efficacy to albendazole. The increase in lipophilicity of the prodrug with respect to menthol was reflected in an increase in its antiparasitic activity against E. multilocularis. Thus, menthol-pentanol appears as a promising candidate for further evaluation as a potential alternative for the treatment of alveolar echinococcosis.


Assuntos
Anti-Helmínticos/farmacologia , Echinococcus multilocularis/efeitos dos fármacos , Mentol/farmacologia , Pentanóis/farmacologia , Pró-Fármacos , Albendazol/farmacologia , Animais , Anti-Helmínticos/química , Benzimidazóis/farmacologia , Carboximetilcelulose Sódica/química , Relação Dose-Resposta a Droga , Equinococose , Feminino , Humanos , Mentol/administração & dosagem , Mentol/química , Camundongos , Estrutura Molecular , Pentanóis/administração & dosagem , Pentanóis/química
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