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Journal of Evidence-based Integrative... 2021and are ethnomedicinally used for the treatment of malaria and have been experimentally shown to have an anti-plasmodial effect, but the mechanisms involved are not...
BACKGROUND
and are ethnomedicinally used for the treatment of malaria and have been experimentally shown to have an anti-plasmodial effect, but the mechanisms involved are not fully understood. This study investigated the effect of the ethanol extracts of their leaves on parasitemia, radical scavenging and cytokines in ANKA-infected BALB/c mice.
METHODS
mice were infected with P. and treated with chloroquine, or extract for 4 days. The percentage of parasitemia and the level of cytokine expression were determined after treatment. Trace element, phytochemical and nitric oxide (NO) scavenging activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging properties assays were done to study the antioxidant effects of AN and KG
RESULTS
consistently increased parasitemia in mice. The tested doses (100-, 200-, and 400 mg/kg) of and attenuated the -induced elevation of parasitemia and cytokines (TNF-α, IL-5, and IL-6) during the experimental period, though not as much as chloroquine. Moreover, both extracts scavenged the DPPH and NO radicals, though had more anti-oxidant effect than
CONCLUSION
The ethanol extracts of and reduce parasitemia in -treated mice BALB/c by scavenging free radicals and reducing cytokines, though the extracts were not as effective as chloroquine.
Topics: Animals; Annona; Chloroquine; Cytokines; Disease Models, Animal; Malaria; Meliaceae; Mice; Mice, Inbred BALB C; Oxidative Stress; Parasitemia; Plant Extracts; Plant Leaves; Plasmodium berghei
PubMed: 34350806
DOI: 10.1177/2515690X211036669 -
ELife Dec 2023Lipophorin is an essential, highly expressed lipid transport protein that is secreted and circulates in insect hemolymph. We hijacked the gene to make it co-express a...
Lipophorin is an essential, highly expressed lipid transport protein that is secreted and circulates in insect hemolymph. We hijacked the gene to make it co-express a single-chain version of antibody 2A10, which binds sporozoites of the malaria parasite . The resulting transgenic mosquitoes show a markedly decreased ability to transmit expressing the circumsporozoite protein to mice. To force the spread of this antimalarial transgene in a mosquito population, we designed and tested several CRISPR/Cas9-based gene drives. One of these is installed in, and disrupts, the pro-parasitic gene and also cleaves wild-type causing the anti-malarial modified version to replace the wild type and hitch-hike together with the drive. Although generating drive-resistant alleles and showing instability in its gRNA-encoding multiplex array, the -based gene drive reached high levels in caged mosquito populations and efficiently promoted the simultaneous spread of the antimalarial allele. This combination is expected to decrease parasite transmission via two different mechanisms. This work contributes to the design of novel strategies to spread antimalarial transgenes in mosquitoes, and illustrates some expected and unexpected outcomes encountered when establishing a population modification gene drive.
Topics: Animals; Mice; Anopheles; Gene Drive Technology; Antimalarials; Mosquito Vectors; RNA, Guide, CRISPR-Cas Systems; Plasmodium falciparum; Plasmodium berghei; Lipoproteins
PubMed: 38051195
DOI: 10.7554/eLife.93142 -
International Journal For Parasitology.... Aug 2022With the emergence of resistance to front-line antimalarials, there is an urgent need to develop new medicines, including those targeting sexual development. This study...
BACKGROUND
With the emergence of resistance to front-line antimalarials, there is an urgent need to develop new medicines, including those targeting sexual development. This study aimed to assess the activity of a panel of phosphatase inhibitors against the sexual development of Plasmodium berghei and evaluate their potential as transmission-blocking agents.
METHODS
Twenty-five compounds were screened for transmission-blocking activity in vitro using the P. berghei ookinete culture assay. The inhibitory effects on male gametogenesis, gamete-ookinete, and zygote-ookinete formation were evaluated. The transmission-blocking activity of two compounds was evaluated using an in vivo mosquito feeding assay. Their cytotoxic effects were assessed on the human cell line HepG2.
RESULTS
Twelve compounds inhibited P. berghei ookinete formation with an IC < 10 μM. Two compounds, BVT-948 and alexidine dihydrochloride, significantly inhibited different developmental stages from gametogenesis through ookinete maturation. They also showed a substantial in vivo transmission-blocking activity by the mosquito feeding assay.
CONCLUSIONS
Some phosphatase inhibitors effectively inhibited Plasmodium sexual development and exhibited evident transmission-blocking activity, suggesting that phosphatases are valid targets for antimalarial development.
Topics: Animals; Antimalarials; Biguanides; Culicidae; Enzyme Inhibitors; Humans; Malaria; Male; Parasites; Phosphoric Monoester Hydrolases; Plasmodium berghei; Sexual Development
PubMed: 35792443
DOI: 10.1016/j.ijpddr.2022.06.003 -
Microbiology Spectrum Apr 2022Gametogenesis is essential for malaria parasite transmission, but the molecular mechanism of this process remains to be refined. Here, we identified a G-protein-coupled...
Gametogenesis is essential for malaria parasite transmission, but the molecular mechanism of this process remains to be refined. Here, we identified a G-protein-coupled receptor 180 (GPR180) that plays a critical role in signal transduction during gametogenesis in The P. berghei GPR180 was predominantly expressed in gametocytes and ookinetes and associated with the plasma membrane in female gametes and ookinetes. Knockout of (Δ) had no noticeable effect on blood-stage development but impaired gamete formation and reduced transmission of the parasites to mosquitoes. Transcriptome analysis revealed that a large proportion of the dysregulated genes in the Δ gametocytes had assigned functions in cyclic nucleotide signal transduction. In the Δ gametocytes, the intracellular cGMP level was significantly reduced, and the cytosolic Ca mobilization showed a delay and a reduction in the magnitude during gametocyte activation. These results suggest that PbGPR180 functions upstream of the cGMP-protein kinase G-Ca signaling pathway. In line with this functional prediction, the PbGPR180 protein was found to interact with several transmembrane transporter proteins and the small GTPase Rab6 in activated gametocytes. Allele replacement of with the P. vivax ortholog showed equal competence of the transgenic parasite in sexual development, suggesting functional conservation of this gene in spp. Furthermore, an anti-PbGPR180 monoclonal antibody and the anti-PvGPR180 serum possessed robust transmission-blocking activities. These results indicate that GPR180 is involved in signal transduction during gametogenesis in malaria parasites and is a promising target for blocking parasite transmission. Environmental changes from humans to mosquitoes activate gametogenesis of the malaria parasite, an obligative process for parasite transmission, but how the signals are relayed remains poorly understood. Here, we show the identification of a G-protein-coupled receptor, GPR180, and the characterization of its function in gametogenesis. In P. berghei, GPR180 is dispensable for asexual development and gametocytogenesis, but its deletion impairs gametogenesis and reduces transmission to mosquitoes. GPR180 appears to function upstream of the cGMP-protein kinase G-Ca signaling pathway and is required for the maximum activity of this pathway. Genetic complementation shows that the GPR180 ortholog from the human malaria parasite P. vivax was fully functional in P. berghei, indicating functional conservation of GPR180 in spp. With predominant expression and membrane association of GPR180 in sexual stages, GPR180 is a promising target for blocking transmission, and antibodies against GPR180 possess robust transmission-blocking activities.
Topics: Animals; Culicidae; Cyclic GMP-Dependent Protein Kinases; Female; Gametogenesis; Humans; Malaria; Parasites; Plasmodium berghei; Plasmodium falciparum; Protozoan Proteins; Receptors, G-Protein-Coupled; Signal Transduction
PubMed: 35404079
DOI: 10.1128/spectrum.00150-22 -
Acta Parasitologica Sep 2019Piperaquine (PQ) is one of the major components of artemisinin-based combination therapy for malaria. However, the mechanism of PQ resistance has remained unclear. (Comparative Study)
Comparative Study
BACKGROUND
Piperaquine (PQ) is one of the major components of artemisinin-based combination therapy for malaria. However, the mechanism of PQ resistance has remained unclear.
METHODS
In this study, we infected mice with PQ-resistant Plasmodium berghei ANKA strain line (PbPQR) or PQ-sensitive P. berghei ANKA strain line (PbPQS) and their survival rates, parasitemia, and spleen sizes were compared. In addition, we constructed genomic DNA subtractive library of spleens from the infected mice, and screened the potential PQ-resistant related genes from genomic DNA of PbPQR line using the representational difference analysis (RDA) method. Clones of the subtractive library were screened by PCR, and related genes were sequenced and analyzed using BLAST software of NCBI.
RESULTS
Compared to PbPQS-infected mice, PbPQR-infected mice survived significantly longer, and had significantly lowered parasitemia rate and significantly increased splenomegaly. Among the total of 502 clones picked, 494 were sequenced and 96 unique PCR fragments were obtained; in which 24 DNA fragments were homologous to chromosomes related to immune function of mice. ORF Finder blasting showed that at the protein level, 26 encoded proteins were homologous to 18 hypothetical PbANKA proteins and 13 encoded proteins were homologous to "ferlin-like protein" family of PbANKA. In addition, there were more immune-related DNA molecules, ubiquitous PbANKA homology at the ORF fragment level, and enriched ferlin-like protein families identified from PbPQR-infected mice than those from PbPQS-infected mice.
CONCLUSION
These findings suggest that PbPQR may induce stronger protective immune response than that of PbPQS in infected mice.
Topics: Animals; Antimalarials; Disease Models, Animal; Humans; Malaria; Male; Mice; Plasmodium berghei; Protozoan Proteins; Quinolines; Virulence
PubMed: 31321598
DOI: 10.2478/s11686-019-00100-5 -
Infection and Immunity Jan 2023In the acidic lysosome-like digestive vacuole, parasites crystallize heme from hemoglobin into hemozoin, or malaria pigment. Upon release of progeny merozoites, the...
In the acidic lysosome-like digestive vacuole, parasites crystallize heme from hemoglobin into hemozoin, or malaria pigment. Upon release of progeny merozoites, the residual hemozoin is phagocytized by macrophages principally in the liver and spleen where the heme crystals can persist for months to years, as heme oxygenase does not readily degrade the crystal. Previous studies demonstrated hemozoin modulation of monocytes and macrophages. Hemozoin modulates immune function activity of monocytes/macrophages. Here, we used purified/washed hemozoin (W-Hz) isolated from murine Plasmodium berghei infections and intravenously (i.v.) injected it back into naive mice. We characterized the modulating effect of W-Hz on liver-stage replication. Purified washed hemozoin decreases P. berghei liver levels both at 1 week and 1 month after i.v. injection in a dose and time dependent fashion. The injected hemozoin fully protected in nine out of 10 mice given a 50 sporozoite inoculum, and in 10 out of 10 mice against 2,000 sporozoites when they were infected an hour or a day after hemozoin inoculation. DNase treatment at the hemozoin reversed the observed liver load reduction. The liver load reduction was similar in mature B- and T-cell-deficient RAG-1 knockout (KO) mice suggesting an innate immune protection mechanism. This work indicates a role for residual hemozoin in down modulation of liver stages.
Topics: Mice; Animals; Malaria; Mice, Inbred BALB C; Plasmodium berghei; Sporozoites; Liver; Heme; DNA
PubMed: 36622216
DOI: 10.1128/iai.00304-22 -
Parasites & Vectors Sep 2020Although Plasmodium parasites and intestinal helminths share common endemic areas, the mechanisms of these co-infections on the host immune response remain not fully...
BACKGROUND
Although Plasmodium parasites and intestinal helminths share common endemic areas, the mechanisms of these co-infections on the host immune response remain not fully understood. Liver involvement in severe Plasmodium falciparum infections is a significant cause of morbidity and mortality. However, the effect of pre-existing Trichinella spiralis infection on the immune response and liver immune-pathogenesis in P. berghei ANKA (PbANKA)-infected mice needs to be elucidated.
METHODS
Outbred Kunming mice were infected with T. spiralis and 9 days later were challenged with P. berghei ANKA (PbANKA), and the investigation occurred at 13 days after co-infection.
RESULTS
Compared with PbANKA-mono-infected mice, T. spiralis + PbANKA-co-infected mice had similar survival rate but lower PbANKA parasitaemia; however, there were more severe hepatosplenomegaly, increased liver and spleen indexes, and increased liver pathology observed by hematoxylin and eosin staining; higher expression levels of galectin (Gal)-1, Gal-3, CD68 macrophages, and elastase-positive neutrophils measured by immunohistochemical staining; upregulated mRNA expression levels of Gal-1, Gal-3, cytokines (interferon-gamma (IFNγ) and interleukin (IL)-6), and M1 macrophage polarization marker (inducible nitric oxide synthase (iNOS)) in the liver, and increased expression levels of Gal-1, IFNγ, IL-6, eosinophil cationic protein, eosinophil protein X, and M1 (IL-1β and iNOS) and M2 (Ym1) macrophage polarization markers in the spleen of co-infected mice detected by using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). In vitro study showed that compared with PbANKA-mono-infected mice, there were significantly increased expression levels of Gal-1, Gal-3, IL-6, IL-1β, and iNOS in the peritoneal macrophage isolated from co-infected mice detected by using qRT-PCR. Correlation analysis revealed significant positive correlations between Gal-3 and IL-1β in the peritoneal macrophages isolated from PbANKA-mono-infected mice, between Gal-3 and IFNγ in the spleen of co-infected mice, and between Gal-1 and Ym1 in the peritoneal macrophages isolated from co-infected mice.
CONCLUSIONS
Our data indicate that pre-existing infection of T. spiralis may suppress P. berghei parasitaemia and aggravate malaria-induced liver pathology through stimulating Gal-1 and Gal-3 expression, activating macrophages, neutrophils, and eosinophils, and promoting mediator release and cytokine production.
Topics: Animals; Blood Cell Count; Coinfection; Cytokines; Disease Models, Animal; Eosinophils; Galectins; Liver; Macrophages; Malaria; Mice; Neutrophils; Parasitemia; Plasmodium berghei; Spleen; Trichinella spiralis; Trichinellosis
PubMed: 32883347
DOI: 10.1186/s13071-020-04309-6 -
Emerging Microbes & Infections Dec 2022The family of apicomplexan specific proteins contains caspases-like proteins called "metacaspases". These enzymes are present in the malaria parasite but absent in...
The family of apicomplexan specific proteins contains caspases-like proteins called "metacaspases". These enzymes are present in the malaria parasite but absent in human; therefore, these can be explored as potential drug targets. We deleted the MCA-2 gene from genome using a gene knockout strategy to decipher its precise function. This study has identified that MCA-2 plays an important role in parasite transmission since it is critical for the formation of gametocytes and for maintaining an appropriate number of infectious sporozoites required for sporogony. It is noticeable that a significant reduction in gametocyte, oocysts, ookinete and sporozoites load along with a delay in hepatocytes invasion were observed in the MCA-2 knockout parasite. Furthermore, a study found the two MCA-2 inhibitory molecules known as C-532 and C-533, which remarkably inhibited the MCA-2 activity, abolished the parasite growth, and also impaired the transmission cycle of and in . Our findings indicate that the deletion of MCA-2 hampers the development during erythrocytic and exo-erythrocytic stages, and its inhibition by C-532 and C-533 critically affects the malaria transmission biology.
Topics: Animals; Gametogenesis; Humans; Malaria; Plasmodium berghei; Protozoan Proteins; Sporozoites
PubMed: 35264080
DOI: 10.1080/22221751.2022.2052357 -
Scientific Reports Jan 2022With its strong effect on vector-borne diseases, and insecticidal effect on mosquito vectors of malaria, inhibition of sporogonic and blood-stage development of...
With its strong effect on vector-borne diseases, and insecticidal effect on mosquito vectors of malaria, inhibition of sporogonic and blood-stage development of Plasmodium falciparum, as well as in vitro and in vivo impairment of the P. berghei development inside hepatocytes, ivermectin (IVM) continues to represent an antimalarial therapeutic worthy of investigation. The in vitro activity of the first-generation IVM hybrids synthesized by appending the IVM macrolide with heterocyclic and organometallic antimalarial pharmacophores, against the blood-stage and liver-stage infections by Plasmodium parasites prompted us to design second-generation molecular hybrids of IVM. Here, a structural modification of IVM to produce novel molecular hybrids by using sub-structures of 4- and 8-aminoquinolines, the time-tested antiplasmodial agents used for treating the blood and hepatic stage of Plasmodium infections, respectively, is presented. Successful isolation of regioisomers and epimers has been demonstrated, and the evaluation of their in vitro antiplasmodial activity against both the blood stages of P. falciparum and the hepatic stages of P. berghei have been undertaken. These compounds displayed structure-dependent antiplasmodial activity, in the nM range, which was more potent than that of IVM, its aglycon or primaquine, highlighting the superiority of this hybridization strategy in designing new antiplasmodial agents.
Topics: Antimalarials; Chloroquine; Isomerism; Ivermectin; Microbial Sensitivity Tests; Plasmodium berghei; Plasmodium falciparum
PubMed: 35022455
DOI: 10.1038/s41598-021-04532-w -
Scientific Reports Mar 2021The use of medicinal plants in the treatment of malaria is gaining global attention due to their efficacy and cost effectiveness. This study evaluated the...
The use of medicinal plants in the treatment of malaria is gaining global attention due to their efficacy and cost effectiveness. This study evaluated the bioactivity-guided antiplasmodial efficacy and immunomodulatory effects of solvent fractions of Diospyros mespiliformis in mice infected with a susceptible strain of Plasmodium berghei (NK 65). The crude methanol extract of the stem of D. mespiliformis (DM) was partitioned between n-hexane, dichloromethane, ethyl acetate and methanol. Male Swiss mice (20 ± 2 g) infected with P. berghei were grouped and treated with vehicle (10 mL/kg, control), Artemether lumefantrine (10 mg/kg), 100, 200 and 400 mg/kg of n-hexane, dichloromethane, ethyl acetate and methanol fractions of D. mespiliformis for seven days. Blood was obtained for heme and hemozoin contents while serum was obtained for inflammatory cytokines and immunoglobulins G and M assessments. Liver mitochondria were isolated for mitochondrial permeability transition (mPT), mitochondrial FF ATPase (mATPase) and lipid peroxidation (mLPO) assays. The GC-MS was used to identify the compounds present in the most potent fraction. The dichloromethane fraction had the highest parasite clearance and improved hematological indices relative to the drug control. The heme values increased, while the hemozoin content significantly (P < 0.05) decreased compared with the drug control. The highest dose of HF and MF opened the mPT pore while the reversal effects of DF on mPT, mATPase and mLPO were dose-dependent. The levels of IgG, IgM and TNFα in the DF group were significantly higher than the drug control, while the IL-1β and IL-6 values did not vary linearly with the dose. Lupeol and Stigmastan-3,5-diene were the most abundant phytochemicals in the DF. The outcome of this study showed that the DF has immunomodulatory effects in infected mice, reduced proliferation of the malaria parasite and thus protect liver cells.
Topics: Animals; Diospyros; Drug Evaluation, Preclinical; Malaria; Male; Mice; Mitochondria, Liver; Parasite Load; Phytotherapy; Plant Extracts; Plants, Medicinal; Plasmodium berghei
PubMed: 33767260
DOI: 10.1038/s41598-021-85790-6