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1.
Korean J Parasitol ; 60(2): 109-116, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35500892

RESUMO

Drug resistance is an important problem hindering malaria elimination in tropical areas. Point mutations in Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) genes confer resistance to antifolate drug, sulfadoxine-pyrimethamine (SP) while P. falciparum chloroquine-resistant transporter (Pfcrt) genes caused resistance to chloroquine (CQ). Decline in Pfdhfr/Pfdhps and Pfcrt mutations after withdrawal of SP and CQ has been reported. The aim of present study was to investigate the prevalence of Pfdhfr, Pfdhps, and Pfcrt mutation from 2 endemic areas of Thailand. All of 200 blood samples collected from western area (Thai-Myanmar) and southern area (Thai-Malaysian) contained multiple mutations in Pfdhfr and Pfdhps genes. The most prevalent haplotypes for Pfdhfr and Pfdhps were quadruple and double mutations, respectively. The quadruple and triple mutations of Pfdhfr and Pfdhps were common in western samples, whereas low frequency of triple and double mutations was found in southern samples, respectively. The Pfcrt 76T mutation was present in all samples examined. Malaria isolated from 2 different endemic regions of Thailand had high mutation rates in the Pfdhfr, Pfdhps, and Pfcrt genes. These findings highlighted the fixation of mutant alleles causing resistance of SP and CQ in this area. It is necessary to monitor the re-emergence of SP and CQ sensitive parasites in this area.


Assuntos
Antimaláricos , Cloroquina , Resistência a Medicamentos , Malária Falciparum , Plasmodium falciparum , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Cloroquina/farmacologia , Cloroquina/uso terapêutico , Combinação de Medicamentos , Humanos , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/genética , Pirimetamina/farmacologia , Pirimetamina/uso terapêutico , Sulfadoxina/farmacologia , Sulfadoxina/uso terapêutico , Tailândia
2.
Front Immunol ; 13: 822567, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35572567

RESUMO

Toxoplasma gondii infects one-third of the world population. For decades, it has been considered a silent lifelong infection. However, chronically T. gondii-infected persons may present psychiatric and neurocognitive changes as anxiety, depression, and memory loss. In a model of long-term chronic infection, behavioral alterations parallel neuroinflammation and systemic high cytokine levels, and may reflect brain cyst load. Recent findings support that in chronic infection an active parasite-host interplay involves an immune-mediated control of tissue cysts. Here, we tested the idea that etiological treatment in chronic phase may add advantage to intrinsic immune-mediated cyst control and impact behavioral changes. Thus, we combined sulfadiazine-plus-pyrimethamine (S+P), the first-choice therapy for toxoplasmosis, to study the association of brain cyst load and biological processes related to the immune response (neuroinflammation, blood-brain barrier -BBB- disruption and serum cytokine levels), with behavioral and neurocognitive changes of long-term chronic infection. Female C57BL/6 mice (H-2b) were infected (5 cysts, ME-49 strain) and treated with S+P from 30 to 60 days postinfection (dpi), compared with vehicle (Veh)-treated and noninfected controls. At endpoints (pre-therapy, 30 dpi; S+P therapy, 60 dpi; after ceased therapy, 90 dpi), independent groups were subjected to behavioral tests, and brain tissues and sera were collected. Multiple behavioral and neurocognitive changes were detected in the early (30 dpi) and long-term (60 and 90 dpi) chronic infection. S+P therapy resolved locomotor alterations, anxiety, and depressive-like behavior, partially or transiently ameliorated hyperactivity and habituation memory loss. Analysis after therapy cessation showed that S+P therapy reduced the number of stimuli required for aversive memory consolidation. S+P therapy resulted in reduced brain cyst load, neuroinflammation and BBB disruption, and lowered systemic Th1-cytokine levels. Correlation analysis revealed association between IFNγ, TNF and MCP-1/CCL2 serum levels, brain cyst load and behavioral and neurocognitive alterations. Moreover, principal-component analysis (PCA-2D and 3D projections) highlighted distinction between clusters (noninfected; Veh-treated and S+P-treated infected). Thus, our data suggest that S+P therapy added gain to intrinsic brain cyst control and, direct or indirectly, ameliorated inflammation-related alterations, traits associated with behavioral and neurocognitive alterations.


Assuntos
Encéfalo , Pirimetamina , Sulfadiazina , Toxoplasmose , Animais , Encéfalo/parasitologia , Citocinas , Feminino , Inflamação/tratamento farmacológico , Transtornos da Memória/parasitologia , Camundongos , Camundongos Endogâmicos C57BL , Pirimetamina/farmacologia , Pirimetamina/uso terapêutico , Sulfadiazina/farmacologia , Sulfadiazina/uso terapêutico , Toxoplasmose/tratamento farmacológico , Toxoplasmose/patologia
3.
Malar J ; 21(1): 39, 2022 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-35135546

RESUMO

BACKGROUND: In 2012, seasonal malaria chemoprevention (SMC) was recommended as policy for malaria control by the World Health Organization (WHO) in areas of highly seasonal malaria transmission across the Sahel sub-region in Africa along with monitoring of drug resistance. We assessed the long-term impact of SMC on Plasmodium falciparum resistance to sulfadoxine-pyrimethamine (SP) and amodiaquine (AQ) over a 3-year period of SMC implementation in the health district of Ouelessebougou, Mali. METHODS: In 8 randomly selected sub-districts of Ouelessebougou, Mali, children aged 0-5 years were randomly selected during cross-sectional surveys at baseline (August 2014) and 1, 2 and 3 years post-SMC, at the beginning and end of the malaria transmission season. Blood smears and blood spots on filter paper were obtained and frequencies of mutation in P. falciparum genes related to resistance to SP and AQ (Pfdhfr, Pfdhps, Pfmdr1, and Pfcrt) were assessed by PCR amplification on individual samples and PCR amplification followed by deep sequencing on pooled (by site and year) samples. RESULTS: At each survey, approximately 50-100 individual samples were analysed by PCR amplification and a total of 1,164 samples were analysed by deep sequencing with an average read depth of 18,018-36,918 after pooling by site and year. Most molecular markers of resistance did not increase in frequency over the period of study (2014-2016). After 3 years of SMC, the frequencies of Pfdhps 540E, Pfdhps 437G and Pfcrt K76T remained similar compared to baseline (4.0 vs 1.4%, p = 0.41; 74.5 vs 64.6%, p = 0.22; 71.3 vs 67.4%, p = 0.69). Nearly all samples tested carried Pfdhfr 59R, and this proportion remained similar 3 years after SMC implementation (98.8 vs 100%, p = 1). The frequency of Pfmdr1 N86Y increased significantly over time from 5.6% at baseline to 18.6% after 3 years of SMC (p = 0.016). Results of pooled analysis using deep sequencing were consistent with those by individual analysis with standard PCR, but also indicated for the first time the presence of mutations at the Pfdhps A581G allele at a frequency of 11.7% after 2 years of SMC, as well as the Pfdhps I431V allele at frequencies of 1.6-9.3% following 1 and 2 years of SMC, respectively. CONCLUSION: Two and 3 years of SMC implementation were associated with increased frequency of the Pfmdr1 N86Y mutation but not Pfdhps 540E, Pfdhps 437G and Pfcrt K76T. The first-time detection of the Pfdhps haplotype bearing the I431V and A581G mutations in Mali, even at low frequency, warrants further long-term surveillance.


Assuntos
Antimaláricos , Malária Falciparum , Malária , Amodiaquina/farmacologia , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Quimioprevenção , Criança , Pré-Escolar , Estudos Transversais , Combinação de Medicamentos , Resistência a Medicamentos/genética , Humanos , Lactente , Recém-Nascido , Malária/tratamento farmacológico , Malária Falciparum/tratamento farmacológico , Malária Falciparum/prevenção & controle , Mali , Plasmodium falciparum/genética , Pirimetamina/farmacologia , Estações do Ano , Sulfadoxina/farmacologia
4.
Antimicrob Agents Chemother ; 66(2): e0153821, 2022 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-34930029

RESUMO

Antifolates targeting dihydrofolate reductase (DHFR) are antimalarial compounds that have long been used for malaria treatment and chemoprevention (inhibition of infection from mosquitoes to humans). Despite their extensive applications, a thorough understanding of antifolate activity against hepatic malaria parasites, especially resistant parasites, has yet to be achieved. Using a transgenic Plasmodium berghei harboring quadruple mutant dhfr from Plasmodium falciparum (Pb::Pfdhfr-4M), we demonstrated that quadruple mutations on Pfdhfr confer complete chemoprevention resistance to pyrimethamine, the previous generation of antifolate, but not to a new class of antifolate designed to overcome the resistance, such as P218. Detailed investigation to pinpoint stage-specific chemoprevention further demonstrated that it is unnecessary for the drug to be present throughout hepatic development. The drug is most potent against the developmental stages from early hepatic trophozoite to late hepatic trophozoite, but it is not effective at inhibiting sporozoite and early hepatic stage development from sporozoite to early trophozoite. Our data show that P218 also inhibited the late hepatic-stage development, from trophozoite to mature schizonts to a lesser extent. With a single dose of 15 mg/kg of body weight, P218 prevented infection from up to 25,000 pyrimethamine-resistant sporozoites, a number equal to thousands of infectious mosquito bites. Additionally, the hepatic stage of malaria parasite is much more susceptible to antifolates than the asexual blood stage. This study provides important insights into the activity of antifolates as a chemopreventive therapeutic which could lead to a more efficient and cost-effective treatment regime.


Assuntos
Antimaláricos , Antagonistas do Ácido Fólico , Malária Falciparum , Animais , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Resistência a Medicamentos/genética , Antagonistas do Ácido Fólico/farmacologia , Humanos , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/genética , Pirimetamina/farmacologia , Pirimetamina/uso terapêutico , Tetra-Hidrofolato Desidrogenase/genética
5.
IUBMB Life ; 74(3): 198-212, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34921584

RESUMO

Cancer accounted for nearly 10 million deaths in 2020 and is the second leading cause of death worldwide. The chemotherapeutic agents that are in clinical practice possess a broad range of severe adverse effects towards vital organs which emphasizes the importance of the discovery of new therapeutic agents or repurposing of existing drugs for the treatment of human cancers. Pyrimethamine is an antiparasitic drug used for the treatment of malaria and toxoplasmosis with a well-documented excellent safety profile. In the last 5 years, numerous efforts have been made to explore the anticancer potential of pyrimethamine in in vitro and in vivo preclinical models and to repurpose it as an anticancer agent. The studies have demonstrated that pyrimethamine inhibits oncogenic proteins such as STAT3, NF-κB, DX2, MAPK, DHFR, thymidine phosphorylase, telomerase, and many more in a different types of cancer models. Moreover, pyrimethamine has been reported to work in synergy with other anticancer agents, such as temozolomide, to induce apoptosis of tumor cells. Recently, the results of phase-1/2 clinical trials demonstrated that pyrimethamine administration reduces the expression of STAT3 signature genes in tumor tissues of chronic lymphocytic leukemia patients with a good therapeutic response. In the present article, we have reviewed most of the published articles related to the antitumor effects of pyrimethamine in malignancies of breast, liver, lung, skin, ovary, prostate, pituitary, and leukemia in in vitro and in vivo settings. We have also discussed the pharmacokinetic profile and results of clinical trials obtained after pyrimethamine treatment. From these studies, we believe that pyrimethamine has the potential to be repurposed as an anticancer drug.


Assuntos
Antineoplásicos , Neoplasias , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Apoptose , Feminino , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/genética , Pirimetamina/farmacologia , Pirimetamina/uso terapêutico , Temozolomida/farmacologia
6.
Molecules ; 26(21)2021 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-34771128

RESUMO

In this work, co-crystal screening was carried out for two important dihydrofolate reductase (DHFR) inhibitors, trimethoprim (TMP) and pyrimethamine (PMA), and for 2,4-diaminopyrimidine (DAP), which is the pharmacophore of these active pharmaceutical ingredients (API). The isomeric pyridinecarboxamides and two xanthines, theophylline (THEO) and caffeine (CAF), were used as co-formers in the same experimental conditions, in order to evaluate the potential for the pharmacophore to be used as a guide in the screening process. In silico co-crystal screening was carried out using BIOVIA COSMOquick and experimental screening was performed by mechanochemistry and supported by (solid + liquid) binary phase diagrams, infrared spectroscopy (FTIR) and X-ray powder diffraction (XRPD). The in silico prediction of low propensities for DAP, TMP and PMA to co-crystallize with pyridinecarboxamides was confirmed: a successful outcome was only observed for DAP + nicotinamide. Successful synthesis of multicomponent solid forms was achieved for all three target molecules with theophylline, with DAP co-crystals revealing a greater variety of stoichiometries. The crystalline structures of a (1:2) TMP:THEO co-crystal and of a (1:2:1) DAP:THEO:ethyl acetate solvate were solved. This work demonstrated the possible use of the pharmacophore of DHFR inhibitors as a guide for co-crystal screening, recognizing some similar trends in the outcome of association in the solid state and in the molecular aggregation in the co-crystals, characterized by the same supramolecular synthons.


Assuntos
Inibidores Enzimáticos/farmacologia , Pirimetamina/farmacologia , Pirimidinas/farmacologia , Tetra-Hidrofolato Desidrogenase/metabolismo , Trimetoprima/farmacologia , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/química , Humanos , Modelos Moleculares , Estrutura Molecular , Pirimetamina/química , Pirimidinas/química , Trimetoprima/química
7.
Int J Mol Sci ; 22(15)2021 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-34360911

RESUMO

Pyrimethamine (Pyri) is being used in combination with other medications to treat serious parasitic infections of the body, brain, or eye and to also reduce toxoplasmosis infection in the patients with HIV infection. Additionally, Pyri can display significant anti-cancer potential in different tumor models, but the possible mode of its actions remains unclear. Hence, in this study, the possible anti-tumoral impact of Pyri on human chronic myeloid leukemia (CML) was deciphered. Pyri inhibited cell growth in various types of tumor cells and exhibited a marked inhibitory action on CML cells. In addition to apoptosis, Pyri also triggered sustained autophagy. Targeted inhibition of autophagy sensitized the tumor cells to Pyri-induced apoptotic cell death. Moreover, the activation of signal transducer and activator of transcription 5 (STAT5) and its downstream target gene Bcl-2 was attenuated by Pyri. Accordingly, small interfering RNA (siRNA)-mediated STAT5 knockdown augmented Pyri-induced autophagy and apoptosis and promoted the suppressive action of Pyri on cell viability. Moreover, ectopic overexpression of Bcl-2 protected the cells from Pyri-mediated autophagy and apoptosis. Overall, the data indicated that the attenuation of STAT5-Bcl-2 cascade by Pyri can regulate its growth inhibitory properties by simultaneously targeting both apoptosis and autophagy cell death mechanism(s).


Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Pirimetamina/farmacologia , Apoptose/genética , Autofagia/genética , Proteína 7 Relacionada à Autofagia/deficiência , Proteína 7 Relacionada à Autofagia/genética , Proteína Beclina-1/deficiência , Proteína Beclina-1/genética , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Técnicas de Silenciamento de Genes , Humanos , Células K562 , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Fator de Transcrição STAT5/deficiência , Fator de Transcrição STAT5/genética , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Células THP-1 , Transfecção , Proteínas Supressoras de Tumor/deficiência , Proteínas Supressoras de Tumor/genética
8.
Trop Med Int Health ; 26(10): 1314-1323, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34407273

RESUMO

OBJECTIVE: The main objective of the MACOMBA (Maternity and Control of Malaria-HIV co-infection in Bangui) trial was to show that cotrimoxazole (CTX) is more effective than sulphadoxine-pyremethamine-IPTp (IPTp-SP) to prevent placental malaria infection (primary end point) among HIV-positive pregnant women with a CD4+ count ≥350 cells/mm3 in Bangui, CAR. METHODS: MACOMBA is a multicentre, open-label randomised trial conducted in four maternity hospitals in Bangui. Between 2013 and 2017, 193 women were randomised and 112 (59 and 53 in CTX and IPTp-SP arms, respectively) were assessed for placental infection defined by microscopic parasitaemia or PCR. RESULTS: Thirteen women had a placental infection: five in the CTX arm (one by microscopic placental parasitaemia and four by PCR) and eight by PCR in the SP-IPTp (8.5% vs. 15.1%, p = 0.28). The percentage of newborns with low birthweight (<2500 g) did not differ statistically between the two arms. Self-reported compliance to CTX prophylaxis was good. There was a low overall rate of adverse events in both arms. CONCLUSION: Although our results do not allow us to conclude that CTX is more effective, drug safety and good compliance among women with this treatment favour its widespread use among HIV-infected pregnant women, as currently recommended by WHO.


Assuntos
Infecções por HIV/complicações , Malária/prevenção & controle , Complicações Parasitárias na Gravidez/tratamento farmacológico , Pirimetamina/farmacologia , Sulfadoxina/farmacologia , Combinação Trimetoprima e Sulfametoxazol/farmacologia , Adulto , Antimaláricos/administração & dosagem , Antimaláricos/uso terapêutico , República Centro-Africana/epidemiologia , Combinação de Medicamentos , Feminino , Infecções por HIV/epidemiologia , Humanos , Malária/epidemiologia , Gravidez , Adulto Jovem
9.
Pharmacol Biochem Behav ; 209: 173257, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34418452

RESUMO

Metoprine increases the content of histamine in brain by inhibiting histamine N-methyltransferase (HMT), a centrally acting histamine degrading enzyme. We present data demonstrating that pretreatment with metoprine attenuates the hyperlocomotive effects of METH in mice using a multi-configuration behavior apparatus designed to monitor four behavioral outcomes [horizontal locomotion, appetitive behavior (food access), and food and water intake]. Metoprine pretreatment itself induced hyperlocomotion in mice challenged with saline during the large part of light phase. The trend was also observed during the following dark phase. This is the first report that metoprine has a long-lasting locomotor stimulating property. Similarly, in a tail suspension test, a single injection of metoprine significantly reduced total time of immobility in mice, consistent with the idea that metoprine possesses motor stimulating properties. Metoprine pretreatment did not affect other aspects of behavior. Metoprine did not affect the appetitive and drinking behavior while exerted an effect on stereotypy. No stereotyped behavior was observed in mice pretreated with vehicle followed by METH, while stereotyped sniffing was observed in mice pretreated with metoprine followed by METH. The metoprine pretreatment attenuated METH-induced hyperlocomotion during the first 2 h of light phase, suggesting that metoprine-induced locomotor stimulating property might be different from that of METH. The hypothalamic content of histamine (but not its brain metabolite) was increased after metoprine or METH administration. Both METH and metoprine reduced dopamine and histamine turnover in the striatum and the nucleus accumbens and the hypothalamus, respectively, and there is a significant metoprine pretreatment x METH challenge interaction in the histamine turnover. It is likely that metoprine may attenuate METH-induced hyperlocomotion via activation of histaminergic neurotransmission. Metoprine also might induce a long-lasting locomotor stimulating effect via a putative mechanism different from that whereby METH induces the locomotor stimulating effect.


Assuntos
Histamina/metabolismo , Locomoção/efeitos dos fármacos , Metanfetamina/farmacologia , Pirimetamina/análogos & derivados , Transmissão Sináptica/efeitos dos fármacos , Animais , Comportamento Animal/efeitos dos fármacos , Dopamina/metabolismo , Inibidores Enzimáticos/farmacologia , Comportamento Alimentar/efeitos dos fármacos , Histamina N-Metiltransferase/antagonistas & inibidores , Hipotálamo/metabolismo , Masculino , Metanfetamina/efeitos adversos , Camundongos , Camundongos Endogâmicos ICR , Núcleo Accumbens/metabolismo , Pirimetamina/farmacologia , Comportamento Estereotipado/efeitos dos fármacos
10.
J Gen Virol ; 102(8)2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34342560

RESUMO

Human respiratory syncytial virus (hRSV) is a major cause of respiratory illness in young children and can cause severe infections in the elderly or in immunocompromised adults. To date, there is no vaccine to prevent hRSV infections, and disease management is limited to preventive care by palivizumab in infants and supportive care for adults. Intervention with small-molecule antivirals specific for hRSV represents a good alternative, but no such compounds are currently approved. The investigation of existing drugs for new therapeutic purposes (drug repositioning) can be a faster approach to address this issue. In this study, we show that chloroquine and pyrimethamine inhibit the replication of human respiratory syncytial virus A (long strain) and synergistically increase the anti-replicative effect of ribavirin in cellulo. Moreover, chloroquine, but not pyrimethamine, inhibits hRSV replication in the mouse model. Our results show that chloroquine can potentially be an interesting compound for treatment of hRSV infection in monotherapy or in combination with other antivirals.


Assuntos
Antivirais/farmacologia , Cloroquina/farmacologia , Pirimetamina/farmacologia , Vírus Sincicial Respiratório Humano/efeitos dos fármacos , Replicação Viral/efeitos dos fármacos , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Modelos Animais de Doenças , Feminino , Humanos , Hospedeiro Imunocomprometido , Camundongos , Camundongos Endogâmicos BALB C , Infecções por Vírus Respiratório Sincicial/tratamento farmacológico , Infecções por Vírus Respiratório Sincicial/virologia , Ribavirina/farmacologia
11.
Acta Trop ; 222: 106049, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34273314

RESUMO

Genetic changes conferring drug resistance are generally believed to impose fitness costs to pathogens in the absence of the drug. However, the fitness of resistant parasites against sulfadoxine/pyrimethamine has been inconclusive in Plasmodium falciparum. This is because resistance is conferred by the complex combination of mutations in dihydropteroate synthase (dhps) and dihydrofolate reductase (dhfr), which makes it difficult to separately assess the extent and magnitude of the costs imposed by mutations in dhps and dhfr. To assess the fitness costs imposed by sulfadoxine resistance alone, we generated a transgenic rodent malaria parasite, P. berghei clone harboring an A394G mutation in dhps (PbDHPS-A394G), corresponding to the causative mutation for sulfadoxine resistance in P. falciparum (PfDHPS-A437G). A four-day suppressive test confirmed that the PbDHPS-A394G clone was resistant to sulfadoxine. PbDHPS-A394G and wild-type clones showed similar growth rates and gametocyte production. This observation was confirmed in competitive experiments in which PbDHPS-A394G and wild-type clones were co-infected into mice to directly assess the survival competition between them. In the mosquitoes, there were no significant differences in oocyst production between PbDHPS-A394G and wild-type. These results indicate that the PbDHPS-A394G mutation alters the parasites to sulfadoxine resistance but may not impose fitness disadvantages during the blood stages in mice and oocyst formation in mosquitoes. These results partly explain the persistence of the PfDHPS-A437G mutant in the natural parasite populations.


Assuntos
Antimaláricos , Resistência a Medicamentos , Sulfadoxina , Tetra-Hidrofolato Desidrogenase , Animais , Antimaláricos/farmacologia , Di-Hidropteroato Sintase/genética , Combinação de Medicamentos , Resistência a Medicamentos/genética , Camundongos , Mutação , Plasmodium berghei/efeitos dos fármacos , Plasmodium berghei/enzimologia , Plasmodium berghei/genética , Pirimetamina/farmacologia , Sulfadoxina/farmacologia , Tetra-Hidrofolato Desidrogenase/genética
12.
J Ethnopharmacol ; 280: 114448, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34303805

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Milk production, processing and consumption are integral part of traditional practices in Fulani tribe of Cameroon. It has been observed that Fulani are resistant to malaria. Dairy products traditionally processed by Fulani are intensively used in the ritual treatment of malarial, inflammations and behavioural disorders. Many studies have demonstrated that fermented milk is a rich source of probiotic bacteria. However, the antimalarial activity of probiotics isolated from this natural source has not been experimentally tested. AIM OF THE STUDY: Hence, this study was therefore aimed at evaluating the antimalarial activity of a probiotic bacterium Lactobacillus sakei isolated from traditionally fermented milk in mice infected with chloroquine sensitive Plasmodium berghei ANKA. MATERIALS AND METHODS: The probiotic bacterium was isolated from the Cameroonian Mborro Fulani's traditionally fermented milk and identified using the 16S r RNA gene sequencing. The schizontocidal activity of Lactobacillus sakei on established malaria infection was evaluated. Eighty-four healthy young adult Balb/c mice infected with Plasmodium berghei parasite were randomly divided into two sets of seven group of six mice each, and were given three different doses of Lactobacillus sakei, chloroquine and sulfadoxine/pyrimethamine for seven and fourteen days respectively. The level of parasitaemia, body temperature, survival time and haematological parameters were evaluated. RESULTS: The parasite growth inhibition was observed to increase with increasing dose of probiotic bacterium with maximum suppression being 100 % at dose 3 on day 20. Also, the probiotic bacterium significantly prevented body weight loss and was associated with body temperature reduction and prevented (p<0.05) a decrease in haematological parameters compared to that untreated malaria infected mice. CONCLUSION: The results obtained suggest that Lactobacillus sakei is a probiotic bacterium with antimalarial activity in mice infected with chloroquine sensitive Plasmodium berghei.


Assuntos
Antimaláricos/farmacologia , Lactobacillus sakei , Malária/terapia , Plasmodium berghei/efeitos dos fármacos , Probióticos/farmacologia , Animais , Antimaláricos/administração & dosagem , Camarões , Cloroquina/farmacologia , Modelos Animais de Doenças , Combinação de Medicamentos , Malária/parasitologia , Camundongos , Camundongos Endogâmicos BALB C , Leite/microbiologia , Parasitemia/parasitologia , Parasitemia/terapia , Probióticos/administração & dosagem , Pirimetamina/farmacologia , Sulfadoxina/farmacologia
13.
Future Med Chem ; 13(15): 1253-1269, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34180263

RESUMO

Background: STAT3 is a pro-oncogenic transcription factor. Pyrimethamine (PYM) is a STAT3 inhibitor that suppresses the proliferation of some cancer cells through downregulation of STAT3 target proteins. Methodology & Results: We have used structure-based tools to design novel PYM-based compounds. Intracellular target validation studies revealed that representative compounds 11b-d and 15a downregulate STAT3 downstream proteins and inhibit STAT3 DNA binding domain (DBD). Relative to PYM, a cohort of these compounds are >100-fold more cytotoxic to cancer cells with constitutively active (high pSTAT3) and basal (low pSTAT3) STAT3 signaling, suggesting that STAT3 DBD inhibition is deleterious to the proliferation of cancer cells with low and high pSTAT3 levels. Conclusion: These are promising leads for further preclinical evaluation as therapeutic agents for STAT3-dependent cancers.


Assuntos
DNA/química , Desenho de Fármacos , Pirimetamina/química , Fator de Transcrição STAT3/antagonistas & inibidores , Sítios de Ligação , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , DNA/metabolismo , Regulação para Baixo/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Simulação de Acoplamento Molecular , Domínios Proteicos , Pirimetamina/metabolismo , Pirimetamina/farmacologia , Pontos de Checagem da Fase S do Ciclo Celular/efeitos dos fármacos , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais/efeitos dos fármacos , Relação Estrutura-Atividade
14.
Nat Commun ; 12(1): 1579, 2021 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-33707425

RESUMO

Random mutagenesis is a technique used to generate diversity and engineer biological systems. In vivo random mutagenesis generates diversity directly in a host organism, enabling applications such as lineage tracing, continuous evolution, and protein engineering. Here we describe TRIDENT (TaRgeted In vivo Diversification ENabled by T7 RNAP), a platform for targeted, continual, and inducible diversification at genes of interest at mutation rates one-million fold higher than natural genomic error rates. TRIDENT targets mutagenic enzymes to precise genetic loci by fusion to T7 RNA polymerase, resulting in mutation windows following a mutation targeting T7 promoter. Mutational diversity is tuned by DNA repair factors localized to sites of deaminase-driven mutation, enabling sustained mutation of all four DNA nucleotides at rates greater than 10-4 mutations per bp. We show TRIDENT can be applied to routine in vivo mutagenesis applications by evolving a red-shifted fluorescent protein and drug-resistant mutants of an essential enzyme.


Assuntos
RNA Polimerases Dirigidas por DNA/metabolismo , Evolução Molecular Direcionada/métodos , Farmacorresistência Fúngica/genética , Engenharia de Proteínas/métodos , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Proteínas Virais/metabolismo , Antifúngicos/farmacologia , Escherichia coli/genética , Escherichia coli/metabolismo , Mutagênese/genética , Regiões Promotoras Genéticas/genética , Pirimetamina/farmacologia
15.
Clin Pharmacol Ther ; 110(4): 926-940, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-33763871

RESUMO

Malaria is an infectious disease which disproportionately effects children and pregnant women. These vulnerable populations are often excluded from clinical trials resulting in one-size-fits-all treatment regimens based on those established for a nonpregnant adult population. Pharmacokinetic/pharmacodynamic (PK/PD) models can be used to optimize dose selection as they define the drug exposure-response relationship. Additionally, these models are able to identify patient characteristics that cause alterations in the expected PK/PD profiles and through simulations can recommend changes to dosing which compensate for the differences. In this review, we examine how PK/PD models have been applied to optimize antimalarial dosing recommendations for young children, including those who are malnourished, pregnant women, and individuals receiving concomitant therapies such as those for HIV treatment. The malaria field has had great success in utilizing PK/PD models as a foundation to update treatment guidelines and propose the next generation of dosing regimens to investigate in clinical trials. We propose how the malaria field can continue to use modeling to improve therapies by further integrating PK data into clinical studies and including data on drug resistance and host immunity in PK/PD models. Finally, we suggest that other disease areas can achieve similar success in applying pharmacometrics to improve outcomes by implementing three key principals.


Assuntos
Fármacos Anti-HIV/uso terapêutico , Antimaláricos/uso terapêutico , Saúde Global , Infecções por HIV/tratamento farmacológico , Malária/tratamento farmacológico , Desnutrição/metabolismo , Complicações Parasitárias na Gravidez/tratamento farmacológico , Populações Vulneráveis , Amodiaquina/farmacologia , Amodiaquina/uso terapêutico , Antimaláricos/farmacologia , Combinação Arteméter e Lumefantrina/farmacologia , Combinação Arteméter e Lumefantrina/uso terapêutico , Artemisininas/farmacologia , Artemisininas/uso terapêutico , Artesunato/farmacologia , Artesunato/uso terapêutico , Pré-Escolar , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Interações Medicamentosas , Quimioterapia Combinada , Feminino , Infecções por HIV/complicações , Humanos , Mefloquina/farmacologia , Mefloquina/uso terapêutico , Modelos Biológicos , Gravidez , Pirimetamina/farmacologia , Pirimetamina/uso terapêutico , Quinolinas/farmacologia , Quinolinas/uso terapêutico , Sulfadoxina/farmacologia , Sulfadoxina/uso terapêutico
16.
Malar J ; 20(1): 152, 2021 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-33731134

RESUMO

BACKGROUND: Anti-malarial drug resistance remains a key concern for the global fight against malaria. In Ghana sulfadoxine-pyrimethamine (SP) is used for intermittent preventive treatment of malaria in pregnancy and combined with amodiaquine for Seasonal Malaria Chemoprevention (SMC) during the high malaria season. Thus, surveillance of molecular markers of SP resistance is important to guide decision-making for these interventions in Ghana. METHODS: A total of 4469 samples from uncomplicated malaria patients collected from 2009 to 2018 was submitted to the Wellcome Trust Sanger Institute, UK for DNA sequencing using MiSeq. Genotypes were successfully translated into haplotypes in 2694 and 846 mono infections respectively for pfdhfr and pfdhps genes and the combined pfhdfr/pfdhps genes across all years. RESULTS: At the pfdhfr locus, a consistently high (> 60%) prevalence of parasites carrying triple mutants (IRNI) were detected from 2009 to 2018. Two double mutant haplotypes (NRNI and ICNI) were found, with haplotype NRNI having a much higher prevalence (average 13.8%) than ICNI (average 3.2%) across all years. Six pfdhps haplotypes were detected. Of these, prevalence of five fluctuated in a downward trend over time from 2009 to 2018, except a pfdhps double mutant (AGKAA), which increased consistently from 2.5% in 2009 to 78.2% in 2018. Across both genes, pfdhfr/pfdhps combined triple (NRNI + AAKAA) mutants were only detected in 2009, 2014, 2015 and 2018, prevalence of which fluctuated between 3.5 and 5.5%. The combined quadruple (IRNI + AAKAA) genotype increased in prevalence from 19.3% in 2009 to 87.5% in 2011 before fluctuating downwards to 19.6% in 2018 with an average prevalence of 37.4% within the nine years. Prevalence of parasites carrying the quintuple (IRNI + AGKAA or SGEAA) mutant haplotypes, which are highly refractory to SP increased over time from 14.0% in 2009 to 89.0% in 2016 before decreasing to 78.9 and 76.6% in 2017 and 2018 respectively. Though quintuple mutants are rising in prevalence in both malaria seasons, together these combined genotypes vary significantly within season but not between seasons. CONCLUSIONS: Despite high prevalence of pfdhfr triple mutants and combined pfdhfr/pfdhps quadruple and quintuple mutants in this setting SP may still be efficacious. These findings are significant as they highlight the need to continuously monitor SP resistance, particularly using deep targeted sequencing to ascertain changing resistance patterns.


Assuntos
Antimaláricos/farmacologia , Resistência a Medicamentos/genética , Variação Genética , Genótipo , Malária Falciparum/prevenção & controle , Plasmodium falciparum/genética , Pirimetamina/farmacologia , Sulfadoxina/farmacologia , Adolescente , Criança , Pré-Escolar , Combinação de Medicamentos , Feminino , Variação Genética/efeitos dos fármacos , Gana , Humanos , Masculino , Plasmodium falciparum/efeitos dos fármacos , Estações do Ano , Adulto Jovem
17.
Int J Parasitol ; 51(8): 635-642, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33713651

RESUMO

Antimalarial drugs capable of targeting multiple parasite stages, particularly the transmissible stages, can be valuable tools for advancing the malaria elimination agenda. Current antifolate drugs such as pyrimethamine can inhibit replicative parasite stages in both humans and mosquitoes, but antifolate resistance remains a challenge. The lack of reliable gametocyte-producing, antifolate-resistant Plasmodium falciparum laboratory strain hinders the study of new antifolate compounds that can overcome antifolate resistance including development stages in the mosquito. We used clustered regularly interspaced short palindromic repeats-Cas9 genome editing to develop a transgenic gametocyte-producing strain of P. falciparum with quadruple mutations (N51I, C59R, S108N, I164L) in the dihydrofolate reductase (dhfr) gene, using NF54 as a parental strain. The transgenic parasites exhibited pyrimethamine resistance while maintaining their gametocyte-producing activity. We then demonstrated that pyrimethamine could no longer inhibit male gametocyte exflagellation in the transgenic parasite. In contrast, P218, the novel antifolate, designed to overcome antifolate resistance, potently inhibited exflagellation. The exflagellation IC50 of P218 was five times lower than the asexual stage half maximal inhibitory concentration (IC50), suggesting a strong barrier for transmission of P218-resistant parasites. The transgenic gametocyte-producing, pyrimethamine-resistant parasite is a robust system for evaluating novel antifolate compounds against non-asexual stage development.


Assuntos
Antimaláricos , Antagonistas do Ácido Fólico , Malária Falciparum , Preparações Farmacêuticas , Animais , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Resistência a Medicamentos , Antagonistas do Ácido Fólico/farmacologia , Humanos , Malária Falciparum/tratamento farmacológico , Masculino , Mutação , Plasmodium falciparum/genética , Pirimetamina/farmacologia , Pirimetamina/uso terapêutico , Tetra-Hidrofolato Desidrogenase/genética
18.
J Glob Antimicrob Resist ; 25: 181-186, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33774217

RESUMO

OBJECTIVES: Pregnancy-associated malaria (PAM) is a complex form of malaria. To prevent PAM, several African countries have adopted intermittent preventive treatment with sulfadoxine/pyrimethamine (IPT-SP). However, resistance to SP has been reported, associated with mutations in the genes Plasmodium falciparum dihydropteroate synthase (Pfdhps) and P. falciparum dihydrofolate reductase (Pfdhfr). The aim of this study was to investigate the prevalence of mutations in Pfdhfr and Pfdhps in P. falciparum isolates from rural areas of Gabon. METHODS: A cross-sectional survey of febrile patients (n = 202) who consulted Fougamou Health Center between February-May 2016 was performed. DNA was extracted from patient samples and the Pfdhfr and Pfdhps genes were genotyped using PCR-RFLP. Statistical analyses were performed. RESULTS: The malaria prevalence in febrile patients included in the study was 60.4% (122/202). The main parasite species was P. falciparum (96.7%; 118/122), followed by Plasmodium malariae (3.3%; 4/122). Genotypes on codons 16, 51, 59 and 108 of Pfdhfr were highly mutated (>96%). In Pfdhps, codons 436, 437, 540 and 613 also expressed high mutation rates. The prevalence of triple mutations of Pfdhfr VIRNI and AIRNI was 12.1% and 84.5%, respectively. The prevalence of mutant haplotypes of Pfdhps SGEA, SGKA and AGEA was 37.9%, 25.9% and 12.1%, respectively. The prevalence of quadruple mutants IRN-A and IRN-G was 20.0% and 93.1%, respectively, whereas quintuple mutants were found at 57.8% (IRN-GE) and 5.0% (IRN-AE). CONCLUSION: Our data show a high prevalence of genotypes associated with SP resistance. Clinical trials to investigate the efficacy of IPT-SP are much needed.


Assuntos
Antimaláricos , Sulfadoxina , Antimaláricos/farmacologia , Estudos Transversais , Resistência a Medicamentos , Feminino , Gabão/epidemiologia , Genótipo , Humanos , Plasmodium falciparum/genética , Gravidez , Prevalência , Pirimetamina/farmacologia , Sulfadoxina/farmacologia
19.
Int J Parasitol ; 51(7): 505-525, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33775670

RESUMO

The global spread of sulfadoxine (Sdx, S) and pyrimethamine (Pyr, P) resistance is attributed to increasing number of mutations in DHPS and DHFR enzymes encoded by malaria parasites. The association between drug resistance mutations and SP efficacy is complex. Here we provide an overview of the geographical spread of SP resistance mutations in Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) encoded dhps and dhfr genes. In addition, we have collated the mutation data and mapped it on to the three-dimensional structures of DHPS and DHFR which have become available. Data from genomic databases and 286 studies were collated to provide a comprehensive landscape of mutational data from 2005 to 2019. Our analyses show that the Pyr-resistant double mutations are widespread in Pf/PvDHFR (P. falciparum ∼61% in Asia and the Middle East, and in the Indian sub-continent; in P. vivax ∼33% globally) with triple mutations prevailing in Africa (∼66%) and South America (∼33%). For PfDHPS, triple mutations dominate South America (∼44%), Asia and the Middle East (∼34%) and the Indian sub-continent (∼27%), while single mutations are widespread in Africa (∼45%). Contrary to the status for P. falciparum, Sdx-resistant single point mutations in PvDHPS dominate globally. Alarmingly, highly resistant quintuple and sextuple mutations are rising in Africa (PfDHFR-DHPS) and Asia (Pf/PvDHFR-DHPS). Structural analyses of DHFR and DHPS proteins in complexes with substrates/drugs have revealed that resistance mutations map proximal to Sdx and Pyr binding sites. Thus new studies can focus on discovery of novel inhibitors that target the non-substrate binding grooves in these two validated malaria parasite drug targets.


Assuntos
Antimaláricos , Plasmodium falciparum/efeitos dos fármacos , Antimaláricos/farmacologia , Di-Hidropteroato Sintase/genética , Combinação de Medicamentos , Resistência a Medicamentos , Genótipo , Mutação , Plasmodium falciparum/genética , Pirimetamina/farmacologia , Sulfadoxina/farmacologia , Tetra-Hidrofolato Desidrogenase/genética
20.
Malar J ; 20(1): 72, 2021 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-33546703

RESUMO

BACKGROUND: In 2004, in response to high levels of treatment failure associated with sulfadoxine-pyrimethamine (SP) resistance, Benin changed its first-line malaria treatment from SP to artemisinin-based combination therapy for treatment of uncomplicated Plasmodium falciparum malaria. Resistance to SP is conferred by accumulation of single nucleotide polymorphisms (SNPs) in P. falciparum genes involved in folate metabolism, dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps), targeted by pyrimethamine and sulfadoxine, respectively. Because SP is still used for intermittent preventive treatment in pregnant women (IPTp) and seasonal malaria chemoprevention (SMCP) in Benin, the prevalence of Pfdhfr and Pfdhps SNPs in P. falciparum isolates collected in 2017 were investigated. METHODS: This study was carried out in two sites where the transmission of P. falciparum malaria is hyper-endemic: Klouékanmey and Djougou. Blood samples were collected from 178 febrile children 6-59 months old with confirmed uncomplicated P. falciparum malaria and were genotyped for SNPs associated with SP resistance. RESULTS: The Pfdhfr triple mutant IRN (N51I, C59R, and S108N) was the most prevalent (84.6%) haplotype and was commonly found with the Pfdhps single mutant A437G (50.5%) or with the Pfdhps double mutant S436A and A437G (33.7%). The quintuple mutant, Pfdhfr IRN/Pfdhps GE (A437G and K540E), was rarely observed (0.8%). The A581G and A613S mutant alleles were found in 2.6 and 3.9% of isolates, respectively. Six isolates (3.9%) were shown to harbour a mutation at codon I431V, recently identified in West African parasites. CONCLUSIONS: This study showed that Pfdhfr triple IRN mutants are near fixation in this population and that the highly sulfadoxine-resistant Pfdhps alleles are not widespread in Benin. These data support the continued use of SP for chemoprevention in these study sites, which should be complemented by periodic nationwide molecular surveillance to detect emergence of resistant genotypes.


Assuntos
Antimaláricos/farmacologia , Di-Hidropteroato Sintase/genética , Resistência a Medicamentos/genética , Plasmodium falciparum/genética , Sulfadoxina/farmacologia , Alelos , Benin/epidemiologia , Pré-Escolar , Di-Hidropteroato Sintase/metabolismo , Combinação de Medicamentos , Feminino , Humanos , Lactente , Malária Falciparum/epidemiologia , Masculino , Plasmodium falciparum/enzimologia , Prevalência , Pirimetamina/farmacologia
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