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Microbiology Spectrum Jun 2023The human malaria parasite undergoes a noncanonical cell division, namely, endoreduplication, where several rounds of nuclear, mitochondrial, and apicoplast replication...
The human malaria parasite undergoes a noncanonical cell division, namely, endoreduplication, where several rounds of nuclear, mitochondrial, and apicoplast replication occur without cytoplasmic division. Despite its importance in biology, the topoisomerases essential for decatenation of replicated chromosome during endoreduplication remain elusive. We hypothesize that the topoisomerase VI complex, containing Plasmodium falciparum topiosomerase VIB (PfTopoVIB) and catalytic P. falciparum Spo11 (PfSpo11), might be involved in the segregation of the mitochondrial genome. Here, we demonstrate that the putative PfSpo11 is the functional ortholog of yeast Spo11 that can complement the sporulation defects of the yeast Δ strain, and the catalytic mutant Pfspo11Y65F cannot complement such defects. PfTopoVIB and PfSpo11 display a distinct expression pattern compared to the other type II topoisomerases of and are induced specifically at the late schizont stage of the parasite, when the mitochondrial genome segregation occurs. Furthermore, PfTopoVIB and PfSpo11 are physically associated with each other at the late schizont stage, and both subunits are localized in the mitochondria. Using PfTopoVIB- and PfSpo11-specific antibodies, we immunoprecipitated the chromatin of tightly synchronous early, mid-, and late schizont stage-specific parasites and found that both the subunits are associated with the mitochondrial genome during the late schizont stage of the parasite. Furthermore, PfTopoVIB inhibitor radicicol and atovaquone show synergistic interaction. Accordingly, atovaquone-mediated disruption of mitochondrial membrane potential reduces the import and recruitment of both subunits of PfTopoVI to mitochondrial DNA (mtDNA) in a dose-dependent manner. The structural differences between PfTopoVIB and human TopoVIB-like protein could be exploited for development of a novel antimalarial agent. This study demonstrates a likely role of topoisomerase VI in the mitochondrial genome segregation of Plasmodium falciparum during endoreduplication. We show that PfTopoVIB and PfSpo11 remain associated and form the functional holoenzyme within the parasite. The spatiotemporal expression of both subunits of PfTopoVI correlates well with their recruitment to the mitochondrial DNA at the late schizont stage of the parasite. Additionally, the synergistic interaction between PfTopoVI inhibitor and the disruptor of mitochondrial membrane potential, atovaquone, supports that topoisomerase VI is the mitochondrial topoisomerase of the malaria parasite. We propose that topoisomerase VI may act as a novel target against malaria.
Topics: Animals; Humans; Parasites; Atovaquone; Saccharomyces cerevisiae; Plasmodium falciparum; Malaria, Falciparum; Malaria; DNA, Mitochondrial; Protozoan Proteins; Endodeoxyribonucleases; Saccharomyces cerevisiae Proteins
PubMed: 37212694
DOI: 10.1128/spectrum.04980-22 -
Travel Medicine and Infectious Disease 2023Hair analysis to identify substance use is an established methodology. This could also be a method to monitor adherence to antimalarial drugs. We aimed to establish a...
BACKGROUND
Hair analysis to identify substance use is an established methodology. This could also be a method to monitor adherence to antimalarial drugs. We aimed to establish a methodology to determine hair concentrations of atovaquone, proguanil and mefloquine in travellers using chemoprophylaxis.
METHODS
A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous analysis of the antimalarial drugs -atovaquone (ATQ), proguanil (PRO) and mefloquine (MQ), in human hair. The hair samples from five volunteers were used for this proof-of-concept analysis. Three volunteers were taking daily atovaquone/proguanil (ATQ/PRO) chemoprophylaxis and two volunteers were using weekly mefloquine (MQ) chemoprophylaxis.
RESULTS
With this proof-of-principle analysis, we could show that ATQ/PRO and MQ are integrated into the hair matrix. Chemoprophylaxis could be quantified with the established method. In hair segments, maximal concentrations of 3.0 ng/mL/20 mg hair proguanil, 1.3 ng/mL/20 mg hair atovaquone and 78.3 ng/mL/20 mg hair mefloquine were measured. Moreover, malaria drug concentration changes correlated with the time interval since finishing the chemoprophylaxis regimen.
CONCLUSIONS
The validated method was used successfully for the analysis of antimalarial-drug positive hair samples containing atovaquone, proguanil or mefloquine. This research shows that hair can be used for adherence monitoring of chemoprophylaxis and paves the way for larger studies and optimized procedures.
Topics: Humans; Antimalarials; Proguanil; Atovaquone; Mefloquine; Chromatography, Liquid; Drug Therapy, Combination; Travel; Tandem Mass Spectrometry; Drug Combinations
PubMed: 37209974
DOI: 10.1016/j.tmaid.2023.102590 -
International Journal of Antimicrobial... Jul 2023A major threat to the goal of eliminating malaria, particularly in Southeast Asia, is the spread of Plasmodium falciparum resistant to artemisinin-based combination...
A major threat to the goal of eliminating malaria, particularly in Southeast Asia, is the spread of Plasmodium falciparum resistant to artemisinin-based combination therapies. P218 is a drug candidate designed to combat antifolate-sensitive and -resistant parasites. However, there is no evidence that P218 is effective against artemisinin-resistant P. falciparum. This report investigated the susceptibilities of 10 parasite isolates from Southeast Asia to P218 and other antimalarial drugs. All isolates with different levels of artemisinin resistance were genetically distinct from one another, although common haplotypes associated with antimalarial resistance were identified. All isolates were highly resistant to pyrimethamine, and none of them were significantly less sensitive to P218 than the pyrimethamine-resistant laboratory strain V1/S. Significant differences in sensitivity to other types of antimalarials (mefloquine, atovaquone and chloroquine) compared with V1/S were found for some isolates, although the differences were not clinically relevant. P218 is thus efficacious against multi-drug (including artemisinin-resistant P. falciparum.
Topics: Humans; Antimalarials; Artemisinins; Drug Resistance; Folic Acid Antagonists; Malaria, Falciparum; Plasmodium falciparum; Pyrimethamine
PubMed: 37160237
DOI: 10.1016/j.ijantimicag.2023.106838 -
Antimicrobial Agents and Chemotherapy Jun 2023Atovaquone-proguanil (AP) is used as treatment for uncomplicated malaria, and as a chemoprophylactic agent against Plasmodium falciparum. Imported malaria remains one of...
Atovaquone-proguanil (AP) is used as treatment for uncomplicated malaria, and as a chemoprophylactic agent against Plasmodium falciparum. Imported malaria remains one of the top causes of fever in Canadian returning travelers. Twelve sequential whole-blood samples before and after AP treatment failure were obtained from a patient diagnosed with P. falciparum malaria upon their return from Uganda and Sudan. Ultradeep sequencing was performed on the and markers of treatment resistance before and during the episode of recrudescence. Haplotyping profiles were generated using three different approaches: agarose and capillary electrophoresis, and using amplicon deep sequencing (ADS). A complexity of infection (COI) analysis was conducted. Y268C mutants strains were observed during an episode of recrudescence 17 days and 16 h after the initial malaria diagnosis and AP treatment initiation. No Y268C mutant reads were observed in any of the samples prior to the recrudescence. SNPs in the and genes were observed upon initial presentation. The haplotyping profiles suggest multiple clones mutating under AP selection pressure (COI > 3). Significant differences in COI were observed by capillary electrophoresis and ADS compared to the agarose gel results. ADS using revealed the lowest haplotype variation across the longitudinal analysis. Our findings highlight the value of ultra-deep sequencing methods in the understanding of P. falciparum haplotype infection dynamics. Longitudinal samples should be analyzed in genotyping studies to increase the analytical sensitivity.
Topics: Humans; Plasmodium falciparum; Antimalarials; Sepharose; Canada; Proguanil; Atovaquone; Malaria, Falciparum; Drug Combinations; Treatment Failure; Tetrahydrofolate Dehydrogenase; High-Throughput Nucleotide Sequencing; Recurrence
PubMed: 37154745
DOI: 10.1128/aac.01709-22 -
Antibiotics (Basel, Switzerland) Mar 2023The environmental release of antimicrobial pharmaceuticals is an imminent threat due to ecological impacts and microbial resistance phenomena. The recent COVID-19...
Predicted Environmental Risk Assessment of Antimicrobials with Increased Consumption in Portugal during the COVID-19 Pandemic; The Groundwork for the Forthcoming Water Quality Survey.
The environmental release of antimicrobial pharmaceuticals is an imminent threat due to ecological impacts and microbial resistance phenomena. The recent COVID-19 outbreak will likely lead to greater loads of antimicrobials in the environment. Thus, identifying the most used antimicrobials likely to pose environmental risks would be valuable. For that, the ambulatory and hospital consumption patterns of antimicrobials in Portugal during the COVID-19 pandemic (2020-2021) were compared with those of 2019. A predicted risk assessment screening approach based on exposure and hazard in the surface water was conducted, combining consumption, excretion rates, and ecotoxicological/microbiological endpoints in five different regions of Portugal. Among the 22 selected substances, only rifaximin and atovaquone demonstrated predicted potential ecotoxicological risks for aquatic organisms. Flucloxacillin, piperacillin, tazobactam, meropenem, ceftriaxone, fosfomycin, and metronidazole showed the most significant potential for antibiotic resistance in all analysed regions. Regarding the current screening approach and the lack of environmental data, it is advisable to consider rifaximin and atovaquone in subsequent water quality surveys. These results might support the forthcoming monitorisation of surface water quality in a post-pandemic survey.
PubMed: 37107014
DOI: 10.3390/antibiotics12040652 -
Advanced Healthcare Materials Jul 2023Although the combination of chemotherapy and immune checkpoint inhibitors (ICIs) can treat triple-negative breast cancer (TNBC), the severe effects of chemotherapy on...
Although the combination of chemotherapy and immune checkpoint inhibitors (ICIs) can treat triple-negative breast cancer (TNBC), the severe effects of chemotherapy on immune cells significantly reduce the efficacy of the ICIs. Photodynamic therapy (PDT) with high selectivity is an alternative to chemotherapy that can also effectively treat hypoxic TNBC. However, high levels of immunosuppressive cells, and low infiltration of cytotoxic T lymphocytes (CTLs) limit the efficacy of PDT combined with ICIs. This study aims to evaluate the role of drug self-delivery nanocubes (ATO/PpIX-SMN) combined with anti-PD-L1 in TNBC treatment. Anti-malarial atovaquone (ATO) enhances protoporphyrin IX (PpIX)-mediated PDT-induced immunogenic cell death and downregulates tumor Wnt/β-catenin signaling. Furthermore, the nanocubes combined with anti-PD-L1, which synergistically induce maturation of dendritic cells, promote infiltration of CTLs, reduce regulatory T cells, and significantly activate the host immune system, thus treating primary and distal tumors. This work demonstrates that ATO/PpIX-SMN can enhance the response rate of anti-PD-L1 in TNBC treatment via O -economized photodynamic-downregulating Wnt/β-catenin signaling.
Topics: Humans; Cell Line, Tumor; Triple Negative Breast Neoplasms; beta Catenin; Wnt Signaling Pathway; Immunotherapy
PubMed: 37104840
DOI: 10.1002/adhm.202203019 -
Journal of Travel Medicine May 2023Perceived adverse effects of antimalarial chemoprophylaxis can be difficult to distinguish from travel-related illness and are often cited as important reasons for...
BACKGROUND
Perceived adverse effects of antimalarial chemoprophylaxis can be difficult to distinguish from travel-related illness and are often cited as important reasons for non-adherence or refusal of antimalarial chemoprophylaxis. We aimed to investigate the occurrence of symptoms of illness in travellers with and without chemoprophylaxis in a cross-sectional study after travel and to identify risk factors for non-adherence to prophylaxis.
METHODS
We enrolled 458 travellers to Africa and South America during their pre-travel medical consultation at the travel clinic of the University Medical Centre Hamburg-Eppendorf and conducted post-travel interviews on symptoms of illness and intake of malaria prophylaxis.
RESULTS
Eleven percent (49/437) of the participants reported symptoms of illness during travel. In total, 36% (160/448) of the participants reported prescription of chemoprophylaxis, the vast majority of these travelled to Africa (98%) and received atovaquone/proguanil (93%). Frequency of symptoms did not differ significantly between participants without prophylaxis and those taking atovaquone/proguanil. Non-adherence to prophylaxis was frequent (20%), but only 3% (4/149) of the participants stopped the medication early because of perceived side effects. Risk factors associated with non-adherence to prophylaxis included age under 30 years, travel to West or Central Africa and travel duration greater than 14 days.
CONCLUSIONS
Symptoms of illness during travel occurred at similar frequencies irrespective of intake of chemoprophylaxis. Travellers should be informed about chemoprophylaxis in a balanced way, without raising fear of side effects, especially among groups at higher risk for incorrect use of prophylaxis.
Topics: Humans; Adult; Antimalarials; Proguanil; Atovaquone; Travel; Malaria; Cross-Sectional Studies; Travel-Related Illness; Risk Factors; Prescriptions; Drug-Related Side Effects and Adverse Reactions; Germany
PubMed: 37098163
DOI: 10.1093/jtm/taad055 -
International Journal of Pharmaceutics May 2023The low level of T-lymphocyte infiltration in tumor is a key issue in cancer immunotherapy. Stimulating anti-tumor immune responses and improving the tumor...
The low level of T-lymphocyte infiltration in tumor is a key issue in cancer immunotherapy. Stimulating anti-tumor immune responses and improving the tumor microenvironment are essential for enhancing anti-PD-L1 immunotherapy. Herein, atovaquone (ATO), protoporphyrin IX (PpIX), and stabilizer (ATO/PpIX NPs) were constructed to self-assemble with hydrophobic interaction and passively targeted to tumor for the first time. The studies have indicated that PpIX-mediated photodynamic induction of immunogenic cell death combined with relieving tumor hypoxia by ATO, leading to maturation of dendritic cells, polarization of M2-type tumor-associated macrophages (TAMs) towards M1-type TAMs, infiltration of cytotoxic T lymphocytes, reduction of regulatory T cells, release of pro-inflammatory cytokines, resulting in an effective anti-tumor immune response synergized with anti-PD-L1 against primary tumor and pulmonary metastasis. Taken together, the combined nanoplatform may be a promising strategy to enhance cancer immunotherapy.
Topics: Humans; Nanomedicine; Immunotherapy; Neoplasms; T-Lymphocytes, Cytotoxic; Lung Neoplasms; Hypoxia; Tumor Microenvironment; Cell Line, Tumor
PubMed: 37084832
DOI: 10.1016/j.ijpharm.2023.122970 -
Current Topics in Medicinal Chemistry 2023Malaria has created havoc since time immemorial. It has actually become a major health concern due to its high prevalence in developing countries where poor sanitary... (Review)
Review
Malaria has created havoc since time immemorial. It has actually become a major health concern due to its high prevalence in developing countries where poor sanitary conditions facilitate the seasonal breeding of the vector, the female Anopheles mosquito. Even after tremendous advancements in pest control and pharmacology science, managing this disease has not been successful, and the cure for this deadly infection has not proven effective lately. The various conventional drugs used are chloroquine, primaquine, mefloquine, atovaquone, quinine, artemisinin etc. All of these have one or other major disadvantages like multi-drug resistance, high dose requirements, aggravated toxicity, non-specificity of conventional drugs, and the emergence of drug-resistant parasites. Therefore, it is necessary to surpass these limitations and look for an alternative to curb the spread of this disease using an emerging technology platform. Nanomedicine is showing promise as an effective alternative tool for the management of malaria. The idea of this tool resonates well with David J. Triggle's outstanding suggestion "The chemist is as the astronaut, searching for biologically useful space in the chemical universe. This review presents a detailed discussion on various nanocarriers, their mode of action and future perspective in treating malaria. Nanotechnology-based drug delivery methods are highly specific, require a lower dose, offer more bioavailability with prolonged drug release and stay in the body longer. Recent nano drug encapsulation and delivery vehicles comprise nanocarriers like liposomes, and organic and inorganic nanoparticles, emerging as promising alternatives for malaria management.
Topics: Animals; Female; Humans; Antimalarials; Malaria, Falciparum; Nanomedicine; Malaria; Primaquine; Antiparasitic Agents
PubMed: 37073152
DOI: 10.2174/1568026623666230417083401 -
Biomedicine & Pharmacotherapy =... Jun 2023The continuing heavy toll of the COVID-19 pandemic necessitates development of therapeutic options. We adopted structure-based drug repurposing to screen FDA-approved...
The continuing heavy toll of the COVID-19 pandemic necessitates development of therapeutic options. We adopted structure-based drug repurposing to screen FDA-approved drugs for inhibitory effects against main protease enzyme (Mpro) substrate-binding pocket of SARS-CoV-2 for non-covalent and covalent binding. Top candidates were screened against infectious SARS-CoV-2 in a cell-based viral replication assay. Promising candidates included atovaquone, mebendazole, ouabain, dronedarone, and entacapone, although atovaquone and mebendazole were the only two candidates with IC50s that fall within their therapeutic plasma concentration. Additionally, we performed Mpro assays on the top hits, which demonstrated inhibition of Mpro by dronedarone (IC50 18 µM), mebendazole (IC50 19 µM) and entacapone (IC50 9 µM). Atovaquone showed only modest Mpro inhibition, and thus we explored other potential mechanisms. Although atovaquone is Dihydroorotate dehydrogenase (DHODH) inhibitor, we did not observe inhibition of DHODH at the respective SARS-CoV-2 IC50. Metabolomic profiling of atovaquone treated cells showed dysregulation of purine metabolism pathway metabolite, where ecto-5'-nucleotidase (NT5E) was downregulated by atovaquone at concentrations equivalent to its antiviral IC50. Atovaquone and mebendazole are promising candidates with SARS-CoV-2 antiviral activity. While mebendazole does appear to target Mpro, atovaquone may inhibit SARS-CoV-2 viral replication by targeting host purine metabolism.
Topics: Humans; Antiviral Agents; SARS-CoV-2; COVID-19; Dihydroorotate Dehydrogenase; Drug Repositioning; Dronedarone; Pandemics; Atovaquone; Mebendazole; Purines; Molecular Docking Simulation; Protease Inhibitors; Molecular Dynamics Simulation
PubMed: 37068330
DOI: 10.1016/j.biopha.2023.114614