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Dynamic control of gene expression is critical for blood stage development of malaria parasites. Here, we used multi-omic analyses to investigate transcriptional regulation by the chromatin-associated microrchidia protein, MORC, during asexual blood stage development of the human malaria parasite Plasmodium falciparum. We show that PfMORC (PF3D7_1468100) interacts with a suite of nuclear proteins, including APETALA2 (ApiAP2) transcription factors (PfAP2-G5, PfAP2-O5, PfAP2-I, PF3D7_0420300, PF3D7_0613800, PF3D7_1107800, and PF3D7_1239200), a DNA helicase DS60 (PF3D7_1227100), and other chromatin remodelers (PfCHD1 and PfEELM2). Transcriptomic analysis of PfMORCHA-glmS knockdown parasites revealed 163 differentially expressed genes belonging to hypervariable multigene families, along with upregulation of genes mostly involved in host cell invasion. In vivo genome-wide chromatin occupancy analysis during both trophozoite and schizont stages of development demonstrates that PfMORC is recruited to repressed, multigene families, including the var genes in subtelomeric chromosomal regions. Collectively, we find that PfMORC is found in chromatin complexes that play a role in the epigenetic control of asexual blood stage transcriptional regulation and chromatin organization.
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Epigénesis Genética , Heterocromatina , Plasmodium falciparum , Proteínas Protozoarias , Plasmodium falciparum/genética , Plasmodium falciparum/metabolismo , Plasmodium falciparum/crecimiento & desarrollo , Proteínas Protozoarias/metabolismo , Proteínas Protozoarias/genética , Heterocromatina/metabolismo , Heterocromatina/genética , Humanos , Regulación de la Expresión Génica , Malaria Falciparum/parasitologíaRESUMEN
Background: The ability to predict and comprehend molecular interactions offers significant insights into the biological functions of proteins. The interaction between surface protein 47 of Plasmodium falciparum (Pfs47) and receptor of the protein 47 (P47Rec) has attracted increased attention due to their role in parasite evasion of the mosquito immune system and the concept of geographical coevolution between species. The aims of this study were as follows: to apply a bioinformatics approach to investigate the interaction between Pfs47 and P47Rec proteins and to identify the potential binding sites, protein orientations and receptor specificity sites concerning the geographical origins of the vectors and the parasite. Methods: Public sequences of the pfs47 and p47rec genes were downloaded and subsequently filtered to predict functional and structural annotations of the Pfs47-P47Rec complex. Phylogenetic analyses of both proteins were carried out. In addition, the p47Rec gene was subjected to sequencing and subsequent analysis in 2 distinct Anopheles species collected in Honduras. Results: The examination of motifs reveals a significant degree of conservation in pfs47, suggesting that Pfs47 might have undergone recent evolutionary development and adaptation. Structural models and docking analyses supported the theory of selectivity of Plasmodium falciparum strains towards their vectors in diverse geographical regions. A detailed description of the putative interaction between the Pfs47-P47Rec complex is shown. Conclusions: The study identifies coevolutionary patterns between P47Rec and Pfs47 related to the speciation and geographic dispersion of Anopheles species and Plasmodium falciparum, with Pfs47 evolving more recently than P47Rec. This suggests a link between the parasite's adaptability and existing anopheline species across different regions. P47Rec likely has a cytoplasmic localization due to its lack of membrane attachment elements. However, these findings are based on simulations and require validation through methods like cryo-electron microscopy. A significant limitation is the scarcity of sequences in global databases, which restricts precise interaction modelling. Further research with diverse parasite isolates and anopheline species is recommended to enhance understanding of these proteins' structure and interaction.
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OBJECTIVES: The isolated Príncipe is at the malaria pre-elimination stage. Autochthonous clinical cases have been reported sporadically on the island, signaling the possibility of a sizable subpatent (i.e., rapid diagnostic test- and microscopy-negative and polymerase chain reaction [PCR]-positive) parasite reservoir. METHODS: Asymptomatic low-density infections were detected by quantitative PCR (qPCR) targeting Plasmodium falciparum multicopy genes (pfr364 and varATS). Positivity rates were assayed for samples surveyed by active case detection (n = 112) and reactive case detection (n = 221) in 2022. RESULTS: qPCR unveiled 70% of low parasitemia carriers, reaching >90% in reactive case detection. The high P. falciparum prevalence was confirmed by the two high-sensitivity qPCR protocols. Higher positivity rates were observed in the localities where most malaria cases were reported in 2022. Most parasitemias were very low (<2 Pf /µl). CONCLUSIONS: These findings suggest that pre-elimination surveillance can benefit from the routine application of highly sensitive tools to unveil otherwise invisible but potentially relevant parasite populations.
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Malaria Falciparum , Plasmodium falciparum , Plasmodium falciparum/genética , Plasmodium falciparum/aislamiento & purificación , Humanos , Malaria Falciparum/epidemiología , Malaria Falciparum/diagnóstico , Malaria Falciparum/parasitología , Prevalencia , Reservorios de Enfermedades/parasitología , Parasitemia/epidemiología , Parasitemia/diagnóstico , Parasitemia/parasitología , Reacción en Cadena en Tiempo Real de la Polimerasa , Masculino , Femenino , Adulto , Niño , Adolescente , Preescolar , Adulto JovenRESUMEN
Malaria during pregnancy has been associated with significant risks to both the mother and the fetus, leading to complications such as anemia, low birth weight, and increased infant mortality. The trophoblast cells, a key component of the placenta, are crucial for nutrient and oxygen exchange between mother and fetus. The differentiation of cytotrophoblasts (CTBs) into syncytiotrophoblasts (STBs) is critical for proper pregnancy development. These cells form the bi-stratified epithelium surrounding the placental villi. While previous studies have described an inflammatory activation of STB cells exposed to Plasmodium falciparum-infected erythrocytes (P. falciparum-IE) or components such as hemozoin (HZ), little is known about the direct effect this parasite may have on the epithelial turnover and function of trophoblast cells. This study aims to contribute to understanding mechanisms leading to placental damage during placental malaria using a BeWo cell line as a differentiation model. It was found that P. falciparum-IE interferes with the fusion of BeWo cells, affecting the differentiation process of trophoblast. A reduction in syncytialization could be associated with the adverse effects of infection in fetal health, altering the remodeling of the trophoblast epithelial barrier and reducing their capacity to exchange substances. However, further studies are necessary to assess alterations in the functionality of this epithelium.
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Malaria is increasingly diagnosed in urban centers across the Amazon Basin. In this study, we combined repeated prevalence surveys over a 4-year period of a household-based random sample of 2,774 persons with parasite genotyping to investigate the epidemiology of malaria in Mâncio Lima, the main urban transmission hotspot in Amazonian Brazil. We found that most malarial infections were asymptomatic and undetected by point-of-care microscopy. Our findings indicate that as malaria transmission decreases, the detection threshold of microscopy rises, resulting in more missed infections despite similar parasite densities estimated by molecular methods. We identified genetically highly diverse populations of Plasmodium vivax and P. falciparum in the region; occasional shared lineages between urban and rural residents suggest cross-boundary propagation. The prevalence of low-density and asymptomatic infections poses a significant challenge for routine surveillance and the effectiveness of malaria control and elimination strategies in urbanized areas with readily accessible laboratory facilities.
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Microscopía , Brasil/epidemiología , Humanos , Prevalencia , Microscopía/métodos , Femenino , Masculino , Adulto , Adolescente , Malaria Vivax/epidemiología , Malaria Vivax/parasitología , Niño , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Malaria Falciparum/prevención & control , Malaria/epidemiología , Malaria/transmisión , Malaria/prevención & control , Malaria/parasitología , Plasmodium vivax/genética , Población Urbana , Preescolar , Plasmodium falciparum/genética , Persona de Mediana Edad , Adulto Joven , Lactante , Historia del Siglo XXIRESUMEN
Several countries are reporting natural populations of P. falciparum with deletions in the pfhrp2/3 genes that can lead to false-negative results in rapid diagnostic tests. To investigate the prevalence of deletion in the pfhrp2/3 genes in the Rio Negro basin in the Brazilian Amazon and identify whether there is clinical differentiation between individuals infected by these parasites, clinical samples collected from 2003 to 2016 were analyzed from symptomatic and asymptomatic P. falciparum-infected individuals. The molecular deletion of pfhrp2 and pfhrp3 genes was evaluated using the protocols recommended by the WHO. From 82 samples used, 28 (34.2%) had a single deletion in pfhrp2, 19 (23.2%) had a single deletion in pfhrp3, 15 (18.3%) had a double deletion (pfhrp2/3), and 20 (24.4%) did not have a deletion in either gene. In total, 29.3% of individuals had an asymptomatic plasmodial infection and were 3.64 times more likely to have parasites with a double deletion (pfhrp2/3) than patients with clinical malaria (p = 0.02). The high prevalence of parasites with pfhrp2/3 deletions shows the need to implement a surveillance program in this area. Deletions in parasites may be associated with the clinical pattern of the disease in this area. More studies must be carried out to elucidate these findings.
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In response to the spread of artemisinin (ART) resistance, ART-based hybrid drugs were developed, and their activity profile was characterized against drug-sensitive and drug-resistant Plasmodium falciparum parasites. Two hybrids were found to display parasite growth reduction, stage-specificity, speed of activity, additivity of activity in drug combinations, and stability in hepatic microsomes of similar levels to those displayed by dihydroartemisinin (DHA). Conversely, the rate of chemical homolysis of the peroxide bonds is slower in hybrids than in DHA. From a mechanistic perspective, heme plays a central role in the chemical homolysis of peroxide, inhibiting heme detoxification and disrupting parasite heme redox homeostasis. The hybrid exhibiting slow homolysis of peroxide bonds was more potent in reducing the viability of ART-resistant parasites in a ring-stage survival assay than the hybrid exhibiting fast homolysis. However, both hybrids showed limited activity against ART-induced quiescent parasites in the quiescent-stage survival assay. Our findings are consistent with previous results showing that slow homolysis of peroxide-containing drugs may retain activity against proliferating ART-resistant parasites. However, our data suggest that this property does not overcome the limited activity of peroxides in killing non-proliferating parasites in a quiescent state.
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Antimaláricos , Artemisininas , Plasmodium falciparum , Artemisininas/farmacología , Antimaláricos/farmacología , Plasmodium falciparum/efectos de los fármacos , Resistencia a Medicamentos/efectos de los fármacos , Microsomas Hepáticos/metabolismo , Humanos , Pruebas de Sensibilidad Parasitaria , Animales , Peróxidos/farmacologíaRESUMEN
An optimization of the pyridylpiperazine series against Plasmodium falciparum has been performed, exploring a structure-activity relationship carried out on the toluyl fragment of hit 1, a compound with low micromolar activity against Plasmodium falciparum discovered by high-throughput screening. After confirming the crucial role played by this aryl fragment in the antiplasmodial activity, the replacement of the ortho-methyl substituent of 1 by halogenated ones led to an improvement for four analogs, either in terms of potency, expected pharmacokinetics profile, or both. Further introduction of endocyclic nitrogens in this fragment identified two more optimized compounds, 20 and 23, which are expected to be much more metabolically stable than 1. Additional assessment of the cytotoxicity, Ligand Lipophilic Efficiency, potency against the chloroquine-resistant Dd2 strain and in silico ADMET predictions revealed a satisfactory profile for most compounds, ultimately identifying the four optimized compounds 7, 9, 20 and 23 as promising compounds for further lead optimization of this series against Plasmodium falciparum.
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Antimaláricos , Diseño de Fármacos , Pruebas de Sensibilidad Parasitaria , Piperazinas , Plasmodium falciparum , Antimaláricos/farmacología , Antimaláricos/síntesis química , Antimaláricos/química , Plasmodium falciparum/efectos de los fármacos , Relación Estructura-Actividad , Piperazinas/química , Piperazinas/farmacología , Piperazinas/síntesis química , Humanos , Estructura Molecular , Relación Dosis-Respuesta a Droga , AnimalesRESUMEN
The human malaria-Aotus monkey model has served the malaria research community since its inception in 1966 at the Gorgas Memorial Laboratory (GML) in Panama. Spanning over five decades, this model has been instrumental in evaluating the in vivo efficacy and pharmacokinetics of a wide array of candidate antimalarial drugs, whether used singly or in combination. The animal model could be infected with drug-resistant and susceptible Plasmodium falciparum and Plasmodium vivax strains that follow a characteristic and reproducible course of infection, remarkably like human untreated and treated infections. Over the years, the model has enabled the evaluation of several synthetic and semisynthetic endoperoxides, for instance, artelinic acid, artesunate, artemether, arteether, and artemisone. These compounds have been evaluated alone and in combination with long-acting partner drugs, commonly referred to as artemisinin-based combination therapies, which are recommended as first-line treatment against uncomplicated malaria. Further, the model has also supported the evaluation of the primaquine analog tafenoquine against blood stages of P. vivax, contributing to its progression to clinical trials and eventual approval. Besides, the P. falciparum/Aotus model at GML has also played a pivotal role in exploring the biology, immunology, and pathogenesis of malaria and in the characterization of drug-resistant P. falciparum and P. vivax strains. This minireview offers a historical overview of the most significant contributions made by the Panamanian owl monkey (Aotus lemurinus lemurinus) to malaria chemotherapy research.
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Antimaláricos , Artemisininas , Modelos Animales de Enfermedad , Animales , Antimaláricos/uso terapéutico , Antimaláricos/farmacocinética , Antimaláricos/farmacología , Artemisininas/uso terapéutico , Artemisininas/farmacología , Humanos , Panamá , Aotidae , Plasmodium falciparum/efectos de los fármacos , Malaria/tratamiento farmacológico , Plasmodium vivax/efectos de los fármacos , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/parasitología , Artesunato/uso terapéutico , Artesunato/farmacología , Artesunato/farmacocinética , Malaria Vivax/tratamiento farmacológico , Malaria Vivax/parasitología , Historia del Siglo XX , AminoquinolinasRESUMEN
BACKGROUND: The sequestration of Plasmodium falciparum infected erythrocytes in the placenta, and the resulting inflammatory response affects maternal and child health. Despite existing information, little is known about the direct impact of P. falciparum on the placental barrier formed by trophoblast and villous stroma. This study aimed to assess placental tissue damage caused by P. falciparum in human placental explants (HPEs). METHODS: HPEs from chorionic villi obtained of human term placentas (n = 9) from normal pregnancies were exposed to P. falciparum-infected erythrocytes (IE) for 24 h. HPEs were embedded in paraffin blocks and used to study tissue damage through histopathological and histochemical analysis and apoptosis using TUNEL staining. Culture supernatants were collected to measure cytokine and angiogenic factors and to determine LDH activity as a marker of cytotoxicity. A subset of archived human term placenta paraffin-embedded blocks from pregnant women with malaria were used to confirm ex vivo findings. RESULTS: Plasmodium falciparum-IE significantly damages the trophoblast layer and the villous stroma of the chorionic villi. The increased LDH activity and pathological findings such as syncytial knots, fibrin deposits, infarction, trophoblast detachment, and collagen disorganization supported these findings. The specific damage to the trophoblast and the thickening of the subjacent basal lamina were more pronounced in the ex vivo infection. In contrast, apoptosis was higher in the in vivo infection. This disparity could be attributed to the duration of exposure to the infection, which significantly varied between individuals naturally exposed over time and the 24-h exposure in the ex vivo HPE model. CONCLUSION: Exposure to P. falciparum-IE induces a detachment of the syncytiotrophoblast, disorganization of the stroma villi, and an increase in apoptosis, alterations that may be associated with adverse results such as intrauterine growth restriction and low birth weight.
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Vellosidades Coriónicas , Plasmodium falciparum , Trofoblastos , Humanos , Femenino , Vellosidades Coriónicas/parasitología , Vellosidades Coriónicas/patología , Embarazo , Plasmodium falciparum/fisiología , Trofoblastos/parasitología , Apoptosis , Malaria Falciparum/parasitología , Malaria Falciparum/patología , Placenta/parasitología , Placenta/patología , Citocinas/metabolismoRESUMEN
BACKGROUND: Plasmodium falciparum malaria is a public health issue mostly seen in tropical countries. Until now, there is no effective malaria vaccine against antigens specific to the blood-stage of P. falciparum infection. Because the pathogenesis of malarial disease results from blood-stage infection, it is essential to identify the most promising blood-stage vaccine candidate antigens under natural exposure to malaria infection. METHODS: A cohort of 400 pregnant women and their infants was implemented in South Benin. An active and passive protocol of malaria surveillance was established during pregnancy and infancy to precisely ascertain malaria infections during the follow-up. Twenty-eight antibody (Ab) responses specific to seven malaria candidate vaccine antigens were repeatedly quantified during pregnancy (3 time points) and infancy (6 time points) in order to study the Ab kinetics and their protective role. Abs were quantified by ELISA and logistic, linear and cox-proportional hazard model were performed to analyse the associations between Ab responses and protection against malaria in mothers and infants, taking into account socio-economic factors and for infants an environmental risk of exposure. RESULTS: The levels of IgM against MSP1, MSP2 and MSP3 showed an early protective response against the onset of symptomatic malaria infections starting from the 18th month of life, whereas no association was found for IgG responses during infancy. In women, some IgG responses tend to be associated with a protection against malaria risk along pregnancy and at delivery, among them IgG3 against GLURP-R0 and IgG2 against MSP1. CONCLUSION: The main finding suggests that IgM should be considered in vaccine designs during infanthood. Investigation of the functional role played by IgM in malaria protection needs further attention.
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Anticuerpos Antiprotozoarios , Antígenos de Protozoos , Inmunoglobulina G , Inmunoglobulina M , Malaria Falciparum , Plasmodium falciparum , Humanos , Femenino , Plasmodium falciparum/inmunología , Malaria Falciparum/prevención & control , Malaria Falciparum/inmunología , Embarazo , Lactante , Inmunoglobulina M/sangre , Inmunoglobulina G/sangre , Anticuerpos Antiprotozoarios/sangre , Benin , Antígenos de Protozoos/inmunología , Adulto , Adulto Joven , Ensayo de Inmunoadsorción Enzimática , Recién Nacido , Complicaciones Parasitarias del Embarazo/prevención & control , Complicaciones Parasitarias del Embarazo/inmunología , Estudios de CohortesRESUMEN
CONTEXT: Malaria remains a significant global health challenge with emerging resistance to current treatments. Plasmodium falciparum glutathione reductase (PfGR) plays a critical role in the defense mechanisms of malaria parasites against oxidative stress. In this study, we investigate the potential of targeting PfGR with conventional antimalarials and dual drugs combining aminoquinoline derivatives with GR inhibitors, which reveal promising interactions between PfGR and studied drugs. The naphthoquinone Atovaquone demonstrated particularly high affinity and potential dual-mode binding with the enzyme active site and cavity. Furthermore, dual drugs exhibit enhanced binding affinity, suggesting their efficacy in inhibiting PfGR, where the aliphatic ester bond (linker) is essential for effective binding with the enzyme's active site. Overall, this research provides important insights into the interactions between antimalarial agents and PfGR and encourages further exploration of its role in the mechanisms of action of antimalarials, including dual drugs, to enhance antiparasitic efficacy. METHODS: The drugs were tested as PfGR potential inhibitors via molecular docking on AutoDock 4, which was performed based on the preoptimized structures in HF/3-21G-PCM level of theory on ORCA 5. Drug-receptor systems with the most promising binding affinities were then studied with a molecular dynamic's simulation on AMBER 16. The molecular dynamics simulations were performed with a 100 ns NPT ensemble employing GAFF2 forcefield in the temperature of 310 K, integration time step of 2 fs, and non-bond cutoff distance of 6.0 Å.
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Antimaláricos , Glutatión Reductasa , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Plasmodium falciparum , Antimaláricos/química , Antimaláricos/farmacología , Plasmodium falciparum/enzimología , Plasmodium falciparum/efectos de los fármacos , Glutatión Reductasa/antagonistas & inhibidores , Glutatión Reductasa/química , Glutatión Reductasa/metabolismo , Unión Proteica , Dominio Catalítico , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , HumanosRESUMEN
The development of novel antiplasmodial compounds with broad-spectrum activity against different stages of Plasmodium parasites is crucial to prevent malaria disease and parasite transmission. This study evaluated the antiplasmodial activity of seven novel hydrazone compounds (referred to as CB compounds: CB-27, CB-41, CB-50, CB-53, CB-58, CB-59, and CB-61) against multiple stages of Plasmodium parasites. All CB compounds inhibited blood stage proliferation of drug-resistant or sensitive strains of Plasmodium falciparum in the low micromolar to nanomolar range. Interestingly, CB-41 exhibited prophylactic activity against hypnozoites and liver schizonts in Plasmodium cynomolgi, a primate model for Plasmodium vivax. Four CB compounds (CB-27, CB-41, CB-53, and CB-61) inhibited P. falciparum oocyst formation in mosquitoes, and five CB compounds (CB-27, CB-41, CB-53, CB-58, and CB-61) hindered the in vitro development of Plasmodium berghei ookinetes. The CB compounds did not inhibit the activation of P. berghei female and male gametocytes in vitro. Isobologram assays demonstrated synergistic interactions between CB-61 and the FDA-approved antimalarial drugs, clindamycin and halofantrine. Testing of six CB compounds showed no inhibition of Plasmodium glutathione S-transferase as a putative target and no cytotoxicity in HepG2 liver cells. CB compounds are promising candidates for further development as antimalarial drugs against multidrug-resistant parasites, which could also prevent malaria transmission.
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OBJECTIVES: The accuracy of malaria rapid diagnostic tests is threatened by Plasmodium falciparum with pfhrp2/3 deletions. This study compares gene deletion prevalence determined by multiplex real time polymerase chain reaction (qPCR) and conventional polymerase chain reaction (cPCR) using existing samples with clonality previously determined by microsatellite genotyping. METHODS: Multiplex qPCR was used to estimate prevalence of pfhrp2/3 deletions in three sets of previously collected patient samples from Eritrea and Peru. The qPCR was validated by multiplex digital polymerase chain reaction. Sample classification was compared with cPCR, and receiver operating characteristic curve analysis was used to determine the optimal ΔCq threshold that aligned the results of the two assays. RESULTS: qPCR classified 75% (637 of 849) of samples as single, and 212 as mixed-pfhrp2/3 genotypes, with a positive association between clonality and proportion of mixed-pfhrp2/3 genotype samples. The sample classification agreement between cPCR and qPCR was 75.1% (95% confidence interval [CI] 68.6-80.7%) and 47.8% (95% CI 38.9-56.9%) for monoclonal and polyclonal infections. The qPCR prevalence estimates of pfhrp2/3 deletions showed almost perfect (κ = 0.804, 95% CI 0.714-0.895) and substantial agreement (κ = 0.717, 95% CI 0.562-0.872) with cPCR for Peru and 2016 Eritrean samples, respectively. For 2019 Eritrean samples, the prevalence of double pfhrp2/3 deletions was approximately two-fold higher using qPCR. The optimal threshold for matching the assay results was ΔCq = 3. CONCLUSIONS: Multiplex qPCR and cPCR produce comparable estimates of gene deletion prevalence when monoclonal infections dominate; however, qPCR provides higher estimates where multi-clonal infections are common.
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Antígenos de Protozoos , Malaria Falciparum , Reacción en Cadena de la Polimerasa Multiplex , Plasmodium falciparum , Proteínas Protozoarias , Plasmodium falciparum/genética , Humanos , Malaria Falciparum/epidemiología , Malaria Falciparum/diagnóstico , Malaria Falciparum/parasitología , Proteínas Protozoarias/genética , Reacción en Cadena de la Polimerasa Multiplex/métodos , Prevalencia , Antígenos de Protozoos/genética , Eliminación de Gen , Reacción en Cadena en Tiempo Real de la Polimerasa/métodos , Perú/epidemiología , GenotipoRESUMEN
Malaria continues to be a significant burden, particularly in Africa, which accounts for 95% of malaria deaths worldwide. Despite advances in malaria treatments, malaria eradication is hampered by insecticide and antimalarial drug resistance. Consequently, the need to discover new antimalarial lead compounds remains urgent. To help address this need, we evaluated the antiplasmodial activity of twenty-two amides and thioamides with pyridine cores and their non-pyridine analogues. Twelve of these compounds showed in vitro anti-proliferative activity against the intraerythrocytic stage of Plasmodium falciparum, the most virulent species of Plasmodium infecting humans. Thiopicolinamide 13i was found to possess submicromolar activity (IC50 = 142 nM) and was >88-fold less active against a human cell line. The compound was equally effective against chloroquine-sensitive and -resistant parasites and did not inhibit ß-hematin formation, pH regulation or PfATP4. Compound 13i may therefore possess a novel mechanism of action.
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Antimaláricos , Plasmodium falciparum , Piridinas , Plasmodium falciparum/efectos de los fármacos , Antimaláricos/farmacología , Antimaláricos/química , Humanos , Piridinas/farmacología , Piridinas/química , Amidas/farmacología , Línea Celular , Concentración 50 Inhibidora , Resistencia a Medicamentos , Descubrimiento de Drogas , Eritrocitos/efectos de los fármacos , Eritrocitos/parasitología , Tioamidas/farmacología , Tioamidas/química , Pruebas de Sensibilidad ParasitariaRESUMEN
Plasmodium parasites, the causal agents of malaria, are eukaryotic organisms that obligately undergo sexual recombination within mosquitoes. However, in low transmission settings where most mosquitoes become infected with only a single parasite clone, parasites recombine with themselves, and the clonal lineage is propagated rather than broken up by outcrossing. We investigated whether stochastic/neutral factors drive the persistence and abundance of Plasmodium falciparum clonal lineages in Guyana, a country with relatively low malaria transmission, but the only setting in the Americas in which an important artemisinin resistance mutation (pfk13 C580Y) has been observed. To investigate whether this clonality was potentially associated with the persistence and spatial spread of the mutation, we performed whole genome sequencing on 1,727 Plasmodium falciparum samples collected from infected patients across a five-year period (2016-2021). We characterized the relatedness between each pair of monoclonal infections (n=1,409) through estimation of identity by descent (IBD) and also typed each sample for known or candidate drug resistance mutations. A total of 160 clones (mean IBD ≥ 0.90) were circulating in Guyana during the study period, comprising 13 highly related clusters (mean IBD ≥ 0.40). In the five-year study period, we observed a decrease in frequency of a mutation associated with artemisinin partner drug (piperaquine) resistance (pfcrt C350R) and limited co-occurence of pfcrt C350R with duplications of plasmepsin 2/3, an epistatic interaction associated with piperaquine resistance. We additionally report polymorphisms exhibiting evidence of selection for drug resistance or other phenotypes and reported a novel pfk13 mutation (G718S) as well as 61 nonsynonymous substitutions that increased markedly in frequency. However, P. falciparum clonal dynamics in Guyana appear to be largely driven by stochastic factors, in contrast to other geographic regions. The use of multiple artemisinin combination therapies in Guyana may have contributed to the disappearance of the pfk13 C580Y mutation.
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Malaria, Chagas disease, and leishmaniasis are tropical diseases caused by protozoan parasites of the genera Plasmodium, Trypanosoma and Leishmania, respectively. These diseases constitute a major burden on public health in several regions worldwide, mainly affecting low-income populations in economically poor countries. Severe side effects of currently available drug treatments and the emergence of resistant parasites need to be addressed by the development of novel drug candidates. Natural 2,5-Diketopiperazines (2,5-DKPs) constitute N-heterocyclic secondary metabolites with a wide range of biological activities of medicinal interest. Its structural and physicochemical properties make the 2,5-DKP ring a versatile, peptide-like, and stable pharmacophore attractive for synthetic drug design. In the present work, twenty-three novel synthetic 2,5-DKPs, previously synthesized through the versatile Ugi multicomponent reaction, were assayed for their anti-protozoal activities against P. falciparum, T. cruzi, and L. infantum. Some of the 2,5-DKPs have shown promising activities against the target protozoans, with inhibitory concentrations (IC50) ranging from 5.4 to 9.5 µg/mL. The most active compounds also show low cytotoxicity (CC50), affording selectivity indices ≥ 15. Results allowed for observing a clear relationship between the substitution pattern at the aromatic rings of the 2,5-DKPs and their corresponding anti-Plasmodium activity. Finally, calculated drug-like properties of the compounds revealed points for further structure optimization of promising drug candidates.
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To provide a continuous update on the safety and efficacy of artesunate-mefloquine (ASMQ) compared with other artemisinin combination therapy (ACT) schemes used in the treatment of uncomplicated malaria caused by Plasmodium falciparum, this study updated and expanded the results of the systematic literature review published in 2016. Only randomised controlled clinical trials published from 1 January 2001 to 12 June 2023 from five databases were included in this study. The results related to efficacy, expressed through RR, were summarized in meta-analyses, performed according to the compared ACTs and with the intention-to-treat and per-protocol analyses. The results related to safety were synthesized in a descriptive manner. Thirty-two studies were included, of which 24 had been analysed in the 2016 review and eight new ones were added. Although the methodological quality of most studies was considered moderate, the body of evidence gathered indicates that ASMQ continues to be safe and effective for the treatment of uncomplicated infections caused by P. falciparum compared with other ACTs. However, the inclusion of two new studies, which identified failure rates exceeding 10%, suggests a possible reduction in the efficacy of ASMQ in the analysed locations. The incidence of serious adverse effects, such as seizure, encephalopathy and cardiac arrhythmia, was infrequent in both the ASMQ group and the comparison groups. After including new evidence, ASMQ is still recommended as a first-line treatment of uncomplicated malaria caused by P. falciparum, although local aspects need to be considered.
Asunto(s)
Antimaláricos , Malaria Falciparum , Malaria , Humanos , Mefloquina/efectos adversos , Artesunato/uso terapéutico , Antimaláricos/efectos adversos , Quimioterapia Combinada , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Malaria/tratamiento farmacológico , Plasmodium falciparumRESUMEN
Introducción: El Plasmodium falciparum es el causante de más del 90 porciento de los casos de malaria en el mundo. Objetivo: Describir aspectos clínico-epidemiológicos de pacientes con malaria grave, atendidos en el Hospital Municipal de Cuimba, provincia de Zaire, República de Angola. Método: Estudio observacional, descriptivo, de corte transversal y retrospectivo, durante el periodo comprendido entre enero-junio de 2023, en pacientes con diagnóstico de malaria grave. El universo fue conformado por 452 pacientes positivos de malaria, la muestra quedó conformada por 97 pacientes que desarrollaron malaria grave. Se estudiaron variables asociadas como: anemia severa, convulsiones, hiperparasitemia, entre otras. Resultados: La media de edad fue de 14,8 años, el 43,3 porciento menor de cinco años, con predominio del sexo masculino (53,9 porciento). El Plasmodium falciparum estuvo presente en 59 casos (60,8 porciento), con elevadas tasas de parasitemia. Las manifestaciones de disfunción cerebral en asociación con la anemia severa resultaron estar en el cuadro clínico del 31 porciento de los pacientes. El 40,2 porciento de los enfermos no presentó complicaciones en su estadía hospitalaria. El síndrome de dificultad respiratoria aguda (18,6 porciento) fue la complicación más frecuente que sobrellevó al fallecimiento del 12,4 porciento de los pacientes. El artesunato fue usado en 77,3 porciento de los pacientes. Conclusiones: El paludismo representa un problema de salud en el Hospital Municipal de Cuimba, con mayor frecuencia en los menores de cinco años. Prevalece la infección por Plasmodium falciparum en pacientes con anemia severa.(AU)
Introduction: Plasmodium falciparum is responsible for more than 90 percent of malaria worldwide. Objective: Characterization of Clinical-epidemiological aspects of severe malaria in patients treated at the Municipal Hospital of Cuimba, Zaire, Angola. Method: An observational, descriptive, cross-sectional and retrospective study was conducted, during the period January - June 2023, in patients reported with severe malaria. The study involved a total of 452 patients with positive malaria but only 97 of them, who presented a complication of severe malaria, were selected as sample. The variables used were as follow: severe anemia, convulsions, hyperparasitemia, among others. Results: Male sex was predominant, with an average age of 14.8 percent and 43.3 percent of patients under five years of age. Plasmodium falciparum was found in 59 patients (60.8 percent) with a high parasitaemia prevalence. Manifestations of cerebral dysfunction in association with severe anemia were found in the clinical picture of 31 percent of patients. The 40.2 percent of patients had no complications in admission period. Acute Respiratory Distress Syndrome was the most frequent complication (18.6 percent), and it was the leading cause of death in 12.4 percent of patients. Artesunate was used in 77.3 percent of patients. Conclusions: Malaria is a health problem in Municipal Hospital of Cuimba, with a higher incidence in children under five years of age; Plasmodium falciparum infection prevailed in patients with severe anemia.(AU)
Introdução: O Plasmodium falciparum é responsável por mais de 90 porcento da malária em todo o mundo. Objetivo: Caracterização dos aspectos clínico-epidemiológicos da malária grave em pacientes atendidos no Hospital Municipal de Cuimba, Zaire, Angola. Método: Foi realizado um estudo observacional, descritivo, transversal e retrospetivo, durante o período de janeiro a junho de 2023, em doentes notificados com malária grave. O estudo envolveu um total de 452 doentes com malária positiva, mas apenas 97 deles, que apresentavam uma complicação de malária grave, foram seleccionados como amostra. As variáveis utilizadas foram as seguintes: anemia grave, convulsões, hiperparasitemia, entre outras. Resultados: O sexo masculino foi predominante, com uma idade média de 14,8 anos e 43,3 porcento dos doentes com menos de cinco anos de idade. O Plasmodium falciparum foi encontrado em 59 doentes (60,8 porcento) com uma elevada prevalência de parasitemia. Manifestações de disfunção cerebral em associação com anemia grave foram encontradas no quadro clínico de 31 porcento dos doentes. Os 40,2 porcento dos doentes não tiveram complicações no período de admissão. A Síndrome de Angústia Respiratória Aguda foi a complicação mais frequente (18,6 porcento) e foi a principal causa de morte em 12,4 porcento dos doentes. O artesunato foi utilizado em 77,3 porcento dos doentes. Conclusões: A malária é um problema de saúde em Hospital Municipal de Cuimba, com uma maior incidência em crianças com menos de cinco anos de idade; a infeção por Plasmodium falciparum prevaleceu em pacientes com anemia grave.(AU)
Asunto(s)
MalariaRESUMEN
Cerebral malaria (CM) pathogenesis is described as a multistep mechanism. In this context, monocytes have been implicated in CM pathogenesis by increasing the sequestration of infected red blood cells to the brain microvasculature. In disease, endothelial activation is followed by reduced monocyte rolling and increased adhesion. Nowadays, an important challenge is to identify potential pro-inflammatory stimuli that can modulate monocytes behavior. Our group have demonstrated that bradykinin (BK), a pro-inflammatory peptide involved in CM, is generated during the erythrocytic cycle of P. falciparum and is detected in culture supernatant (conditioned medium). Herein we investigated the role of BK in the adhesion of monocytes to endothelial cells of blood brain barrier (BBB). To address this issue human monocytic cell line (THP-1) and human brain microvascular endothelial cells (hBMECs) were used. It was observed that 20% conditioned medium from P. falciparum infected erythrocytes (Pf-iRBC sup) increased the adhesion of THP-1 cells to hBMECs. This effect was mediated by BK through the activation of B2 and B1 receptors and involves the increase in ICAM-1 expression in THP-1 cells. Additionally, it was observed that angiotensin-converting enzyme (ACE) inhibitor, captopril, enhanced the effect of both BK and Pf-iRBC sup on THP-1 adhesion. Together these data show that BK, generated during the erythrocytic cycle of P. falciparum, could play an important role in adhesion of monocytes in endothelial cells lining the BBB.