Search

Purpose: To describe the effect of long-term, low-dose pyrimethamine for the prevention of ocular toxoplasmosis (OT) recurrences. Methods: Sixty-three consecutive patients with inactive ocular toxoplasmosis and positive toxoplasma IgG serology were included. Pyrimethamine (25 mg) + folinic acid (15 mg) were administered every other day (three times weekly) for 12 months. Eighteen patients received the treatment for an additional six months as part of an extension study. Results: Thirty-eight patients (60.3%, n = 63) were female; 38 (60.3%) had a previous history of recurrence and 37 (58.7%) had active OT within the preceding 12 months. Three (4.8%) patients had unilateral recurrences at 8, 12 and 18 months after starting intermittent pyrimethamine treatment. Five patients (7.9%) were discontinued due to hematological, renal and hepatic changes. Treatment was considered successful in 42 patients (84%). Conclusion: Long-term, low-dose pyrimethamine can be considered as a treatment option for the prevention of ocular toxoplasmosis recurrence in selected patients, with only a few, mild and reversible systemic adverse events. [ABSTRACT FROM AUTHOR]

Leishmaniasis is considered one of the most critical health concerns in the world. Unfortunately, no protective vaccines exist and conventional treatments are relatively ineffective. Therefore, new strategies are necessary against leishmaniasis. In recent years, exosomes have shown promising therapeutic outcomes in various diseases, including infectious diseases. In this regard, we aimed to explore the effect of the exosome, pyrimethamine and their combination on the anti‐parasitic function of RAW264.7 cells against Leishmania major. Exosomes were isolated from the C57BL/6 peritoneal macrophages. L. major infected and non‐infected RAW264.7 cells treated with exosomes, pyrimethamine (PM), and exosomes along with PM. The effect of the treatments was analysed on phagocytosis, efferocytosis, the intracellular parasite count, arginase activity, nitric oxide (NO) and reactive oxygen species (ROS) production. Exosomes could significantly elevate the phagocytosis, efferocytosis, NO and ROS in both infected and non‐infected groups (Pv < 0.05). The exosomes reduced the arginase activity in both groups (Pv < 0.05). The intracellular parasite count was significantly lower after treatment with exosomes (Pv < 0.05). These results demonstrate that MQ‐derived exosomes can enhance in vitro anti‐parasitic responses against L. major. This provides a potential pathway for more effective treatments and underscores the importance of further research in this area. [ABSTRACT FROM AUTHOR]

We employed a BONCAT-iTRAQ labelling approach to investigate newly synthesised proteins (NSPs) in Toxoplasma gondii subjected to varying concentrations of the antifolate drug pyrimethamine. Our results reveal that numerous NSPs exhibited altered expression levels in response to the drug, with significant upregulation observed at higher concentrations. Key proteins involved in protein synthesis, stress responses, energy metabolism, and cytoskeletal dynamics were identified, indicating that T. gondii undergoes complex adaptive responses to pyrimethamine treatment. While some of the identified pathways reflect a generic stress response, this study provides important molecular markers and mechanistic insights specific to the parasite's adaptation strategies. These findings contribute to understanding how T. gondii modulates its proteome in response to drug-induced stress and lay the groundwork for further investigations into potential therapeutic targets. [ABSTRACT FROM AUTHOR]

Introduction In accordance with its mandate to provide guidance to Member States on health policy matters, WHO issues a series of regularly updated position papers on vaccines and combinations of [...]

BackgroundMalaria in pregnancy has been associated with worse cognitive outcomes in children, but its association with behavioral outcomes and the effectiveness of malaria chemoprevention on child neurodevelopment are not well characterized.MethodsTo determine if more effective malaria chemoprevention in mothers and their children results in better neurodevelopment, 305 pregnant women were randomly assigned to 3 doses of sulfadoxine-pyrimethamine, 3 doses of dihydroartemisinin-piperaquine (DP), or monthly DP during pregnancy, and their 293 children were assigned to DP every 3 months or monthly DP from 2 to 24 months of age. Cognition, language, and motor function were assessed at 12, 24. and 36 months of age, and attention, memory, behavior, and executive function were assessed at 24 and 36 months of age.ResultsChildren of mothers with versus without malaria in pregnancy had worse scores on cognitive, behavioral, and executive function outcomes at 24 months. Clinical malaria in children within the first 12 months was similarly associated with poorer scores in behavior and executive function at 24 months, language at 24 and 36 months, and motor function scores at 36 months. However, more effective malaria chemoprevention in the mothers and children was not associated with better outcomes.ConclusionsMalaria in pregnancy was associated with worse cognitive, behavioral, and executive function scores in affected children, but more effective malaria chemoprevention measures did not result in better outcomes. Malaria chemoprevention prior to and early in gestation and with even higher efficacy in mothers and children may be required to prevent neurodevelopmental impairment in children. Clinical Trials Registration. NCT02557425.

Pyrimethamine (PYM) is an antiparasitic drug used in the treatment of congenital toxoplasmosis, available only as tablets. Therefore, preparing extemporaneous formulations and their quality control is essential for safe pediatric treatment. This study aimed to develop and validate a stability-indicating method by ultra-performance liquid chromatography (UPLC) to quantify PYM and methylparaben (MP) in extemporaneous oral suspension and evaluate its applicability to the tablets assay. The analytical conditions included RP-C18 column, mobile phase composed of 0.05 M acetate buffer pH 4.5 and organic mixture (acetonitrile:methanol), at 60:40 (v/v), flow rate of 0.2 mL/min, injection volume of 2 µL and detection at 272 nm. PYM was detected at 3.9 min and MP at 4.7 min, without interference of the degradation products or other excipients. Linearity was observed in the range of 0.5 to 25 μg/mL. The method showed accuracy (mean recovery between 98.0 and 102.0%) and precision (RSD < 2%) for suspension and tablets; the method was robust regarding the variations in the analytical conditions. The developed method met the requirements of current guidelines, was indicative of stability, and was suitable for PYM determination in extemporaneous preparations and tablets. [ABSTRACT FROM AUTHOR]

We employed a BONCAT-iTRAQ labelling approach to investigate newly synthesised proteins (NSPs) in Toxoplasma gondii subjected to varying concentrations of the antifolate drug pyrimethamine. Our results reveal that numerous NSPs exhibited altered expression levels in response to the drug, with significant upregulation observed at higher concentrations. Key proteins involved in protein synthesis, stress responses, energy metabolism, and cytoskeletal dynamics were identified, indicating that T. gondii undergoes complex adaptive responses to pyrimethamine treatment. While some of the identified pathways reflect a generic stress response, this study provides important molecular markers and mechanistic insights specific to the parasite’s adaptation strategies. These findings contribute to understanding how T. gondii modulates its proteome in response to drug-induced stress and lay the groundwork for further investigations into potential therapeutic targets.

Hepatocellular carcinoma (HCC) is one of the most common tumor types and remains a major clinical challenge. Increasing evidence has revealed that mitophagy inhibitors can enhance the effect of chemotherapy on HCC. However, few mitophagy inhibitors have been approved for clinical use in humans. Pyrimethamine (Pyr) is used to treat infections caused by protozoan parasites. Recent studies have reported that Pyr may be beneficial in the treatment of various tumors. However, its mechanism of action is still not clearly defined. Here, we found that blocking mitophagy sensitized cells to Pyr-induced apoptosis. Mechanistically, Pyr potently induced the accumulation of autophagosomes by inhibiting autophagosome-lysosome fusion in human HCC cells. In vitro and in vivo studies revealed that Pyr blocked autophagosome-lysosome fusion by upregulating BNIP3 to inhibit synaptosomal-associated protein 29 (SNAP29)-vesicle-associated membrane protein 8 (VAMP8) interaction. Moreover, Pyr acted synergistically with sorafenib (Sora) to induce apoptosis and inhibit HCC proliferation in vitro and in vivo. Pyr enhances the sensitivity of HCC cells to Sora, a common chemotherapeutic, by inhibiting mitophagy. Thus, these results provide new insights into the mechanism of action of Pyr and imply that Pyr could potentially be further developed as a novel mitophagy inhibitor. Notably, Pyr and Sora combination therapy could be a promising treatment for malignant HCC. [Display omitted] • Pyr regulates mitophagy by interfering with autophagosome-lysosome formation. • Pyr blocks autolysosomes formation by inhibiting SNAP29-VAMP8 interactions. • Pyr upregulates BNIP3 and induces the interaction of SNAP29 with BNIP3. • Restoration of the interaction between SNAP29 and VAMP8 by BNIP3 depletion. • Pyr enhances the sensitivity of HCC to Sora in vitro and in vivo. [ABSTRACT FROM AUTHOR]

BackgroundThe Plasmodium falciparum dihydrofolate reductase (PfDHFR) inhibitors pyrimethamine and cycloguanil (the active metabolite of proguanil) have important roles in malaria chemoprevention, but drug resistance challenges their efficacies. A new compound, P218, was designed to overcome resistance, but drug-susceptibility data for P falciparum field isolates are limited.MethodsWe studied ex vivo PfDHFR inhibitor susceptibilities of 559 isolates from Tororo and Busia districts, Uganda, from 2016 to 2020, sequenced 383 isolates, and assessed associations between genotypes and drug-susceptibility phenotypes.ResultsMedian half-maximal inhibitory concentrations (IC50s) were 42 100 nM for pyrimethamine, 1200 nM for cycloguanil, 13000 nM for proguanil, and 0.6 nM for P218. Among sequenced isolates, 3 PfDHFR mutations, 51I (100%), 59R (93.7%), and 108N (100%), were very common, as previously seen in Uganda, and another mutation, 164L (12.8%), had moderate prevalence. Increasing numbers of mutations were associated with decreasing susceptibility to pyrimethamine, cycloguanil, and P218, but not proguanil, which does not act directly against PfDHFR. Differences in P218 susceptibilities were modest, with median IC50s of 1.4 nM for parasites with mixed genotype at position 164 and 5.7 nM for pure quadruple mutant (51I/59R/108N/164L) parasites.ConclusionsResistance-mediating PfDHFR mutations were common in Ugandan isolates, but P218 retained excellent activity against mutant parasites.

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.

BackgroundIntermittent preventive treatment of malaria during pregnancy (IPTp) with dihydroartemisinin-piperaquine (DP) significantly reduces the burden of malaria during pregnancy compared to sulfadoxine-pyrimethamine (SP), the current standard of care, but its impact on the incidence of malaria during infancy is unknown.MethodsWe conducted a double-blind randomized trial to compare the incidence of malaria during infancy among infants born to HIV-uninfected pregnant women who were randomized to monthly IPTp with either DP or SP. Infants were followed for all their medical care in a dedicated study clinic, and routine assessments were conducted every 4 weeks. At all visits, infants with fever and a positive thick blood smear were diagnosed and treated for malaria. The primary outcome was malaria incidence during the first 12 months of life. All analyses were done by modified intention to treat.ResultsOf the 782 women enrolled, 687 were followed through delivery from December 9, 2016, to December 5, 2017, resulting in 678 live births: 339 born to mothers randomized to SP and 339 born to those randomized to DP. Of these, 581 infants (85.7%) were followed up to 12 months of age. Overall, the incidence of malaria was lower among infants born to mothers randomized to DP compared to SP, but the difference was not statistically significant (1.71 vs 1.98 episodes per person-year, incidence rate ratio (IRR) 0.87, 95% confidence interval (CI) 0.73-1.03, p = 0.11). Stratifying by infant sex, IPTp with DP was associated with a lower incidence of malaria among male infants (IRR 0.75, 95% CI 0.58-0.98, p = 0.03) but not female infants (IRR 0.99, 95% CI 0.79-1.24, p = 0.93).ConclusionDespite the superiority of DP for IPTp, there was no evidence of a difference in malaria incidence during infancy in infants born to mothers who received DP compared to those born to mothers who received SP. Only male infants appeared to benefit from IPTp-DP suggesting that IPTp-DP may provide additional benefits beyond birth. Further research is needed to further explore the benefits of DP versus SP for IPTp on the health outcomes of infants.Trial registrationClinicalTrials.gov, NCT02793622 . Registered on June 8, 2016.