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ADMET & DMPK 2024and are responsible for most malaria cases in humans in the African Region and the Americas; these parasites have developed resistance to classic antimalarial drugs....
BACKGROUND AND PURPOSE
and are responsible for most malaria cases in humans in the African Region and the Americas; these parasites have developed resistance to classic antimalarial drugs. On the other hand, previous investigations of the alkyl-linked bis tetrahydro-(2H)-1,3,5-thiadiazine-2-thione (bis-THTT) derivatives compounds show satisfactory results against protozoan parasites such as , , and . Therefore, it is possible to see some effect of bis-THTT derivatives on other protozoan parasites, such as .
EXPERIMENTAL APPROACH
This study aimed to perform an biological evaluation of bis-THTT (JH1 to JH6) derivatives compounds as possible anti-malaria drugs in BALB/c mice infected with ANKA and 17XL strains. In this work, we evaluated the compounds as potential antimalarial drugs in BALB/c mice infected with strains.
KEY RESULTS
For each compound, we assess the percentages of parasitemia by smears from tail blood and the humoral response by indirect ELISA test using each compound as an antigen. We also evaluated the B lymphocyte response and the cytotoxicity of the bis-THTT derivatives compounds with MTT cell proliferation assays.
CONCLUSIONS
Our results show that the bis-THTT derivatives JH2 and JH4 presented effective parasitemia control in mice infected with ; JH5 and JH6 compounds have similar infection control results as chloroquine in mice infected strain. The evaluation of bis-THTT derivatives compounds in a model of BALB/c mice infected with and allowed us to conclude that some of them have an antimalarial effect; however, none of the tested compounds exceeded the efficiency of chloroquine.
PubMed: 38720925
DOI: 10.5599/admet.2105 -
Journal of Neuroinflammation May 2024Cerebral malaria (CM) is the most lethal complication of malaria, and survivors usually endure neurological sequelae. Notably, the cytotoxic effect of infiltrating...
BACKGROUND
Cerebral malaria (CM) is the most lethal complication of malaria, and survivors usually endure neurological sequelae. Notably, the cytotoxic effect of infiltrating Plasmodium-activated CD8 T cells on cerebral microvasculature endothelial cells is a prominent feature of the experimental CM (ECM) model with blood-brain barrier disruption. However, the damage effect of CD8 T cells infiltrating the brain parenchyma on neurons remains unclear. Based on the immunosuppressive effect of the PD-1/PD-L1 pathway on T cells, our previous study demonstrated that the systemic upregulation of PD-L1 to inhibit CD8 T cell function could effectively alleviate the symptoms of ECM mice. However, it has not been reported whether neurons can suppress the pathogenic effect of CD8 T cells through the PD-1/PD-L1 negative immunomodulatory pathway. As the important inflammatory factor of CM, interferons can induce the expression of PD-L1 via different molecular mechanisms according to the neuro-immune microenvironment. Therefore, this study aimed to investigate the direct interaction between CD8 T cells and neurons, as well as the mechanism of neurons to alleviate the pathogenic effect of CD8 T cells through up-regulating PD-L1 induced by IFNs.
METHODS
Using the ECM model of C57BL/6J mice infected with Plasmodium berghei ANKA (PbA), morphological observations were conducted in vivo by electron microscope and IF staining. The interaction between the ECM CD8 T cells (immune magnetic bead sorting from spleen of ECM mice) and primary cultured cortical neurons in vitro was observed by IF staining and time-lapse photography. RNA-seq was performed to analyze the signaling pathway of PD-L1 upregulation in neurons induced by IFNβ or IFNγ, and verified through q-PCR, WB, IF staining, and flow cytometry both in vitro and in vivo using IFNAR or IFNGR gene knockout mice. The protective effect of adenovirus-mediated PD-L1 IgGFc fusion protein expression was verified in ECM mice with brain stereotaxic injection in vivo and in primary cultured neurons via viral infection in vitro.
RESULTS
In vivo, ECM mice showed infiltration of activated CD8 T cells and neuronal injury in the brain parenchyma. In vitro, ECM CD8 T cells were in direct contact with neurons and induced axonal damage, as an active behavior. The PD-L1 protein level was elevated in neurons of ECM mice and in primary cultured neurons induced by IFNβ, IFNγ, or ECM CD8 T cells in vitro. Furthermore, the IFNβ or IFNγ induced neuronal expression of PD-L1 was mediated by increasing STAT1/IRF1 pathway via IFN receptors. The increase of PD-L1 expression in neurons during PbA infection was weakened after deleting the IFNAR or IFNGR. Increased PD-L1 expression by adenovirus partially protected neurons from CD8 T cell-mediated damage both in vitro and in vivo.
CONCLUSION
Our study demonstrates that both type I and type II IFNs can induce neurons to upregulate PD-L1 via the STAT1/IRF1 pathway mediated by IFN receptors to protect against activated CD8 T cell-mediated damage, providing a targeted pathway to alleviate neuroinflammation during ECM.
Topics: Animals; Mice; B7-H1 Antigen; CD8-Positive T-Lymphocytes; Interferon Regulatory Factor-1; Interferon-gamma; Malaria, Cerebral; Mice, Inbred C57BL; Mice, Knockout; Neurons; Plasmodium berghei; Signal Transduction; STAT1 Transcription Factor; Up-Regulation
PubMed: 38715061
DOI: 10.1186/s12974-024-03114-7 -
Computational and Structural... Dec 2024Malaria, a significant global health challenge, is caused by parasites. The liver stage plays a pivotal role in the establishment of the infection. This study focuses...
Malaria, a significant global health challenge, is caused by parasites. The liver stage plays a pivotal role in the establishment of the infection. This study focuses on the liver stage development of the model organism Plasmodium berghei, employing fluorescent microscopy imaging and convolutional neural networks (CNNs) for analysis. Convolutional neural networks have been recently proposed as a viable option for tasks such as malaria detection, prediction of host-pathogen interactions, or drug discovery. Our research aimed to predict the transition of Plasmodium-infected liver cells to the merozoite stage, a key development phase, 15 hours in advance. We collected and analyzed hourly imaging data over a span of at least 38 hours from 400 sequences, encompassing 502 parasites. Our method was compared to human annotations to validate its efficacy. Performance metrics, including the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity, were evaluated on an independent test dataset. The outcomes revealed an AUC of 0.873, a sensitivity of 84.6%, and a specificity of 83.3%, underscoring the potential of our CNN-based framework to predict liver stage development of . These findings not only demonstrate the feasibility of our methodology but also could potentially contribute to the broader understanding of parasite biology.
PubMed: 38690550
DOI: 10.1016/j.csbj.2024.04.029 -
Microbes and Infection Apr 2024Hemozoin is a crystal synthesized by Plasmodium parasites during hemoglobin digestion in the erythrocytic stage. The hemozoin released when the parasites egress from the...
Hemozoin is a crystal synthesized by Plasmodium parasites during hemoglobin digestion in the erythrocytic stage. The hemozoin released when the parasites egress from the red blood cell, which is complexed with parasite DNA, is cleared from the circulation by circulating and tissue-resident monocytes and macrophages, respectively. Recently, we reported that intravenous administration of purified hemozoin complexed with Plasmodium berghei DNA (Hz) resulted in an innate immune response that blocked liver stage development of sporozoites that was dose-dependent and time-limited. Here, we further characterize the organismal, cellular, and molecular events associated with this protective innate response in the liver and report that a large proportion of the IV administered Hz localized to F4/80 cells in the liver and that the rapid and strong protection against liver-stage development waned quickly such that by 1 week post-Hz treatment animals were fully susceptible to infection. RNAseq of the liver after IV administration of Hz demonstrated that the rapid and robust induction of genes associated with the acute phase response, innate immune activation, cellular recruitment, and IFN-γ signaling observed at day 1 was largely absent at day 7. RNAseq analysis implicated NK cells as the major cellular source of IFN-γ. In vivo cell depletion and IFN-γ neutralization experiments supported the hypothesis that tissue-resident macrophages and NK cells are major contributors to the protective response and the NK cell-derived IFN-γ is key to induction of the mechanisms that block sporozoite development in the liver. These findings advance our understanding of the innate immune responses that prevent liver stage malaria infection.
PubMed: 38670216
DOI: 10.1016/j.micinf.2024.105343 -
Malaria Journal Apr 2024The use of fluorescent proteins (FPs) in Plasmodium parasites has been key to understand the biology of this obligate intracellular protozoon. FPs like the green... (Review)
Review
The use of fluorescent proteins (FPs) in Plasmodium parasites has been key to understand the biology of this obligate intracellular protozoon. FPs like the green fluorescent protein (GFP) enabled to explore protein localization, promoter activity as well as dynamic processes like protein export and endocytosis. Furthermore, FP biosensors have provided detailed information on physiological parameters at the subcellular level, and fluorescent reporter lines greatly extended the malariology toolbox. Still, in order to achieve optimal results, it is crucial to know exactly the properties of the FP of choice and the genetic scenario in which it will be used. This review highlights advantages and disadvantages of available landing sites and promoters that have been successfully applied for the ectopic expression of FPs in Plasmodium berghei and Plasmodium falciparum. Furthermore, the properties of newly developed FPs beyond DsRed and EGFP, in the visualization of cells and cellular structures as well as in the sensing of small molecules are discussed.
Topics: Green Fluorescent Proteins; Plasmodium berghei; Promoter Regions, Genetic; Plasmodium falciparum; Protein Transport
PubMed: 38643106
DOI: 10.1186/s12936-024-04936-9 -
Antimicrobial Agents and Chemotherapy Apr 2024The development of novel antiplasmodial compounds with broad-spectrum activity against different stages of parasites is crucial to prevent malaria disease and parasite...
The development of novel antiplasmodial compounds with broad-spectrum activity against different stages of 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 parasites. All CB compounds inhibited blood stage proliferation of drug-resistant or sensitive strains of in the low micromolar to nanomolar range. Interestingly, CB-41 exhibited prophylactic activity against hypnozoites and liver schizonts in , a primate model for . Four CB compounds (CB-27, CB-41, CB-53, and CB-61) inhibited oocyst formation in mosquitoes and five CB compounds (CB-27, CB-41, CB-53, CB-58, and CB-61) hindered the development of ookinetes. The CB compounds did not inhibit the activation of female and male gametocytes . 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 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.
PubMed: 38639491
DOI: 10.1128/aac.01643-23 -
Journal of Vector Borne Diseases Apr 2024The persistent threat of drug resistant malaria demands new cures. Low prevalence of malaria in the Indian state of Kerala compared with other proximal states made us...
BACKGROUND OBJECTIVES
The persistent threat of drug resistant malaria demands new cures. Low prevalence of malaria in the Indian state of Kerala compared with other proximal states made us explore if there is any traditional practice in Kerala which may confer protection against malaria. In this context, our attention was drawn to 'Pathimugam' i.e., Ceasalpinia sappan whose heartwood is used to prepare a red aqueous extract which is a uniquely popular drink in Kerala.
METHODS
Aqueous and methanolic extracts of various organs of C. sappan were prepared and tested against Plasmodium falciparum grown in vitro culture using SYBR Green-I assay. The cytotoxicity of active extracts/fractions was studied using mammalian HeLa cell line. in vivo efficacy was determined using P. berghei ANKA infected mice.
RESULTS
The highest antiplasmodial activities in the alcoholic and aqueous extracts were observed in leaf methanolic extract (IC50 2 μg/ml) and heartwood aqueous extract (IC50 12.5 μg/ml). Ceasalpinia sappan extracts were equipotent against both chloroquine-sensitive Pf3D7 and resistant PfINDO strains and showed suppression of percentage parasitemia in P. berghei infected mice. Activity- guided chromatographic fractionation of aqueous wood extract led to the fortification of antiplasmodial activity (IC50 5 μg/ml).
INTERPRETATION CONCLUSION
Our results establish the antiplasmodial potential of C. sappan and suggest that its regular use might have prophylactic or curative actions that may assist in keeping check on malaria in the Indian state of Kerala.
PubMed: 38634464
DOI: 10.4103/JVBD.JVBD_18_24 -
ACS Medicinal Chemistry Letters Apr 2024Toward addressing the cardiotoxicity liability associated with the antimalarial drug astemizole (AST, hERG IC = 0.0042 μM) and its derivatives, we designed and...
Toward addressing the cardiotoxicity liability associated with the antimalarial drug astemizole (AST, hERG IC = 0.0042 μM) and its derivatives, we designed and synthesized analogues based on compound ( NF54 IC = 0.012 μM; hERG IC = 0.63 μM), our previously identified 3-trifluoromethyl-1,2,4-oxadiazole AST analogue. Compound retained multistage antiplasmodium activity (ABS NF54 IC = 0.017 μM; gametocytes iGc/LGc IC = 1.24/1.39 μM, and liver-stage HepG2 IC = 2.30 μM), good microsomal metabolic stability (MLM CL < 11 μL·min·mg, < 0.33), and solubility (150 μM). It shows a ∼6-fold and >6000-fold higher selectivity against human ether-á-go-go-related gene higher selectively potential over hERG relative to and AST, respectively. Despite the excellent antiplasmodium activity profile, efficacy in the mouse infection model was diminished, attributable to suboptimal oral bioavailability ( = 14.9%) at 10 mg·kg resulting from poor permeability (log = -0.82). No cross-resistance was observed against 44 common mutant lines, suggesting activity via a novel mechanism of action.
PubMed: 38628794
DOI: 10.1021/acsmedchemlett.3c00496 -
International Journal For Parasitology.... Apr 2024Infection with Plasmodium falciparum is often deadly when it results in cerebral malaria, which is associated with neuropathology described as an overwhelming...
Infection with Plasmodium falciparum is often deadly when it results in cerebral malaria, which is associated with neuropathology described as an overwhelming inflammatory response and mechanical obstruction of cerebral microvascular. PI3Kγ is a critical component of intracellular signal transduction and plays a central role in regulating cell chemotaxis, migration, and activation. The purpose of this study was to examine the relationship between inhibiting the PI3Kγ pathway and the outcome of experimental cerebral malaria (ECM) in C57BL/6J mice infected with the mouse malaria parasite, Plasmodium berghei ANKA. We observed that oral administration of the PI3Kγ inhibitor IPI549 after infection completely protected mice from ECM. IPI549 treatment significantly dampened the magnitude of inflammatory responses, with reduced production of pro-inflammatory factors, decreased T cell activation, and altered differentiation of antigen-presenting cells. IPI549 treatment protected the infected mice from neuropathology, as assessed by an observed reduction of pathogenic T cells in the brain. Treating the infected mice with IPI549 three days after parasite inoculation improved the murine blood brain barrier (BBB) integrity and helped the mice pass the onset of ECM. Together, these data indicate that oral administration of the PI3Kγ inhibitor IPI549 has a suppressive role in host inflammation and alleviates cerebral pathology, which supports IPI549 as a new malaria treatment option with potential therapeutic implications for cerebral malaria.
PubMed: 38621317
DOI: 10.1016/j.ijpddr.2024.100539 -
Bioorganic & Medicinal Chemistry Apr 20244,9-diaminoacridines with reported antiplasmodial activity were coupled to different trans-cinnamic acids, delivering a new series of conjugates inspired by the covalent...
4,9-diaminoacridines with reported antiplasmodial activity were coupled to different trans-cinnamic acids, delivering a new series of conjugates inspired by the covalent bitherapy concept. The new compounds were more potent than primaquine against hepatic stages of Plasmodium berghei, although this was accompanied by cytotoxic effects on Huh-7 hepatocytes. Relevantly, the conjugates displayed nanomolar activities against blood stage P. falciparum parasites, with no evidence of hemolytic effects below 100 µM. Moreover, the new compounds were at least 25-fold more potent than primaquine against P. falciparum gametocytes. Thus, the new antiplasmodial hits disclosed herein emerge as valuable templates for the development of multi-stage antiplasmodial drug candidates.
Topics: Humans; Antimalarials; Primaquine; Disclosure; Plasmodium falciparum; Malaria, Falciparum; Plasmodium berghei; Cinnamates
PubMed: 38582046
DOI: 10.1016/j.bmc.2024.117714