As a unicellular organism, Plasmodium displays a panoply of lipid metabolism pathways that are seldom found together in a unicellular organism. These pathways mostly involve the Plasmodium-encoded enzymatic machinery and meet the requirements of membrane synthesis during the rapid cell growth and division throughout the life cycle. Different lipids have varied synthesis and meta-bolism pathways. For example, the major phospholipids are synthesized via CDP-diacylglycerol-dependent pathway in prokaryotes and de novo pathway in eukaryotes, and fatty acids are synthesized mainly via type Ⅱ fatty acid synthesis pathway. The available studies have demonstrated the impacts of artemisinin and its derivatives, the front-line compounds against malaria, on the lipid metabolism of Plasmodium. Therefore, this article reviewed the known lipid metabolism pathways and the effects of artemisinin and its derivatives on these pathways, aiming to deepen the understanding of lipid synthesis and metabolism in Plasmodium and provide a theoretical basis for the research on the mechanisms and drug resistance of artemisinin and other anti-malarial drugs.
Antimalarials/pharmacology* ; Artemisinins/therapeutic use* ; Humans ; Lipid Metabolism ; Malaria/drug therapy* ; Plasmodium

The vir genes are antigenic genes and are considered to be possible vaccine targets. Since India is highly endemic to Plasmodium vivax, we sequenced 5 different vir genes and investigated DNA sequence variations in 93 single-clonal P. vivax isolates. High variability was observed in all the 5 vir genes; the vir 1/9 gene was highly diverged across Indian populations. The patterns of genetic diversity do not follow geographical locations, as geographically distant populations were found to be genetically similar. The results in general present complex genetic diversity patterns in India, requiring further in-depth population genetic and functional studies.
Antigens, Protozoan/*genetics ; Humans ; India/epidemiology ; Malaria, Vivax/epidemiology/parasitology ; Phylogeny ; Plasmodium vivax/*genetics ; *Polymorphism, Genetic ; Protozoan Proteins/genetics/*metabolism

OBJECTIVES: The CYP2B6 is one of the most polymorphic CYP genes in humans that has the potential to modify the pharmacological and toxicological responses to clinically important drugs such as antimalarial artemisinin and its derivatives. The aim of the study was to determine the frequency of CYP2B6 polymorphisms in Timor malaria endemic area, East Nusa Tenggara, Indonesia where Artemisin-based Combination Therapy (ACT) has been used to treat uncomplicated malaria. METHODS: A total of 109 healthy subjects were participated in this study. CYP2B6*4, *6 and *9 polymorphisms were analyzed using PCR-RFLP to confirm the SNPs prevalence of 516G>T and 785A>G in exon 4 and 5. RESULTS: There were 96 subjects included in the analysis. In the exon 4 of CYP2B6 516G>T, the frequency of the T mutation was 37.5% (39/96), and the wildtype 27.1% (26/96). In the exon 5, CYP2B6 785A>G mutant was detected in 29.2% (28/96) of individuals, and the wildtype allele in 35.4% (34/96). The frequency of CYP2B6*9 (516G>T), CYP2B6*4 (785A>G) and CYP2B6*6 (516G>T and 785A>G) were 40.6%, 29.2% and 22.9%, respectively. The prevalence of these CYP2B6 gene polymorphisms in Timorian ethnic were higher than that in Malay, Han Chinese, Indian, and Egyptian populations. CONCLUSION: The prevalence of these CYP2B6 516G>T and 785A>G polymorphisms in Timorian ethnic is higher than that in other populations. These polymorphisms may affect the metabolism of artemisinin and its derivatives.
Alleles ; Asian Continental Ancestry Group ; Cytochrome P-450 CYP2B6* ; Exons ; Healthy Volunteers ; Humans ; Indonesia* ; Malaria ; Metabolism ; Polymorphism, Single Nucleotide ; Prevalence*

Objective To investigate the effect of T cell immunoreceptor with Ig and ITIM domains (TIGIT) on the function of CD8⁺ T cells in the lungs of Plasmodium infected mice. Methods The lungs of the mice infected with Plasmodium yoelii were isolated, weighed and photographed after 12 days' infection. After dissolution, lung lymphocytes were isolated, counted and stained, and then the contents of CD8⁺ and TIGIT⁺CD8⁺ T cells were detected by flow cytometry. The expressions of L selectin (CD62L), CD69, programmed death 1 (PD-1), CD25, and C-X3-C motif chemokine receptor 1 (CX3CR1) on TIGIT⁺CD8⁺ T cells were detected by flow cytometry. After stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin, the ability of TIGIT⁺CD8⁺T cells to secrete interferon γ(IFN-γ), interleukin 21 (IL-21), IL-4, IL-17, and IL-10 was detected. Results The body mass of mice with Plasmodium infection was reduced. The lungs became darker, and the ratio of the lung mass to body mass was significantly increased. Compared with the normal mice, the percentages and absolute quantity of CD8⁺ and TIGIT⁺CD8⁺ T cells in the lungs of the infected mice were significantly increased. The percentage of TIGIT⁺CD8⁺ T cells expressing CD62L in the infected group was significantly lower, while the percentage of the CD69, PD-1, and CX3CR1 cells were significantly higher than that of TIGIT⁺CD8⁺ T cells from the normal mice. The percentages of TIGIT⁺CD8⁺ T cells secreting IL-21, IL-4, IL-17 and IL-10 cells in the infected group were significantly lower. Conclusion The lung lesions from mice with Plasmodium infection are obvious, the numbers of TIGIT⁺CD8⁺ T cells increase, and these cells express a variety of activation-related molecules, but the ability to secrete cytokines is reduced.
Animals ; Mice ; CD8-Positive T-Lymphocytes ; Cytokines/metabolism* ; Interferon-gamma/metabolism* ; Interleukin-10/metabolism* ; Interleukin-17/metabolism* ; Interleukin-4/metabolism* ; Lung/metabolism* ; Malaria/metabolism* ; Plasmodium yoelii/metabolism* ; Programmed Cell Death 1 Receptor/metabolism*

Malaria is still a leading cause of morbidity and mortality. The increase in lipid peroxidation reported in malaria infection and antioxidant status may be a useful marker of oxidative stress during malaria infection. The aim of this study was to investigate the role of antioxidant enzymes against toxic reactive oxygen species in patients infected with Plasmodium vivax and healthy controls. Malondialdehyde levels, superoxide dismutase, and glutathione peroxidase activities were determined in 91 P. vivax patients and compared with 52 controls. Malondialdehyde levels, superoxide dismutase, and glutathione peroxidase activities were 8.07+/-2.29 nM/ml, 2.69+/-0.33 U/ml, and 49.6+/-3.2 U/g Hb in the patient group and 2.72+/-0.50 nM/ml, 3.71+/-0.47 U/ml, and 62.3+/-4.3 U/g Hb in the control group, respectively. Malondialdehyde levels were found statistically significant in patients with vivax malaria higher than in healthy controls (P<0.001). On the other hand, superoxide dismutase and glutathione peroxidase activities were found to be significantly lower in vivax malaria patients than in controls (P<0.05). There was an increase in oxidative stress in vivax malaria. The results suggested that antioxidant defense mechanisms may play an important role in the pathogenesis of P. vivax.
Adult ; Animals ; Antioxidants/*metabolism ; Biological Markers/metabolism ; Female ; Glutathione Peroxidase/metabolism ; Humans ; Lipid Peroxidation ; Malaria, Vivax/*metabolism/parasitology ; Male ; Malondialdehyde/metabolism ; *Oxidative Stress ; Plasmodium vivax/*metabolism ; Reactive Oxygen Species/*metabolism ; Superoxide Dismutase/metabolism ; Young Adult

Hemoglobinopathy and malaria are commonly found worldwide particularly in malaria endemic areas. Thalassemia, the alteration of globin chain synthesis, has been reported to confer resistance against malaria. The prevalence of thalassemia was investigated in 101 malaria patients with Plasmodium falciparum and Plasmodium vivax along the Thai-Myanmar border to examine protective effect of thalassemia against severe malaria. Hemoglobin typing was performed using low pressure liquid chromatography (LPLC) and alpha-thalassemia was confirmed by multiplex PCR. Five types of thalassemia were observed in malaria patients. The 2 major types of thalassemia were Hb E (18.8%) and alpha-thalassemia-2 (11.9%). There was no association between thalassemia hemoglobinopathy and malaria parasitemia, an indicator of malaria disease severity. Thalassemia had no significant association with P. vivax infection, but the parasitemia in patients with coexistence of P. vivax and thalassemia was about 2-3 times lower than those with coexistence of P. falciparum and thalassemia and malaria without thalassemia. Furthermore, the parasitemia of P. vivax in patients with coexistence of Hb E showed lower value than coexistence with other types of thalassemia and malaria without coexistence. Parasitemia, hemoglobin, and hematocrit values in patients with coexistence of thalassemia other than Hb E were significantly lower than those without coexistence of thalassemia. Furthermore, parasitemia with coexistence of Hb E were 2 times lower than those with coexistence of thalassemia other than Hb E. In conclusion, the results may, at least in part, support the protective effect of thalassemia on the development of hyperparasitemia and severe anemia in malaria patients.
Female ; Hemoglobins/genetics/metabolism ; Humans ; Malaria, Falciparum/blood/complications/*genetics/parasitology ; Malaria, Vivax/blood/complications/*genetics/parasitology ; Male ; Middle Aged ; Plasmodium falciparum/physiology ; Plasmodium vivax/physiology ; Thailand/epidemiology ; Thalassemia/blood/complications/epidemiology/*genetics

Astrocytes are the most abundant cells in the central nervous system that play roles in maintaining the blood-brain-barrier and in neural injury, including cerebral malaria, a severe complication of Plasmodium falciparum infection. Prostaglandin (PG) D2 is abundantly produced in the brain and regulates the sleep response. Moreover, PGD2 is a potential factor derived from P. falciparum within erythrocytes. Heme oxygenase-1 (HO-1) is catalyzing enzyme in heme breakdown process to release iron, carbon monoxide, and biliverdin/bilirubin, and may influence iron supply to the P. falciparum parasites. Here, we showed that treatment of a human astrocyte cell line, CCF-STTG1, with PGD2 significantly increased the expression levels of HO-1 mRNA by RT-PCR. Western blot analysis showed that PGD2 treatment increased the level of HO-1 protein, in a dose- and time-dependent manner. Thus, PGD2 may be involved in the pathogenesis of cerebral malaria by inducing HO-1 expression in malaria patients.
Animals ; Astrocytes/*enzymology ; Blotting, Western ; Cell Line ; Gene Expression Profiling ; Heme Oxygenase-1/*biosynthesis ; Humans ; Malaria, Cerebral/*pathology ; Malaria, Falciparum/*complications/*pathology ; Plasmodium falciparum/*pathogenicity ; Prostaglandins/*metabolism ; Reverse Transcriptase Polymerase Chain Reaction

BACKGROUNDDuring the blood stage of malaria infection, parasites internalize in the host red blood cells and degrade massive amounts of hemoglobin for their development. Although the morphology of the parasite's hemoglobin uptake pathway has been clearly observed, little has been known about its molecular mechanisms.

METHODSThe recombinant proteins from Plasmodium falciparum, dynamin like protein 1 (PfDYN1) and 2 (PfDYN2) GTPase domain, were expressed in E.coli and showed GTPase activity. By using a dynamin inhibitor, dynasore, we demonstrated the involvement of PfDYN1 in the hemoglobin uptake pathway.

RESULTSThe GTPase activity of the two recombinant proteins was inhibited by dynasore in vitro. Treatment of parasite cultures with 80 micromol/L dynasore at the ring and early trophozoite stage resulted in substantial inhibition of parasite growth and in an obvious decline of hemoglobin quantum. Furthermore, reduced intracellular hemozoin accumulation and decreased uptake of the FITC-dextran were also observed, together with distinctive changes in the ultrastructure of parasites after the dynasore treatment.

CONCLUSIONSOur results show that PfDYN1 plays an important role in the hemoglobin uptake pathway of P. falciparum and suggest its possibility of being a novel target for malaria chemotherapy.

Animals ; Antimalarials ; pharmacology ; Dynamins ; antagonists & inhibitors ; GTP Phosphohydrolases ; genetics ; metabolism ; Hemoglobins ; metabolism ; Hydrazones ; pharmacology ; Malaria, Falciparum ; metabolism ; Microscopy, Electron, Transmission ; Plasmodium falciparum ; drug effects ; metabolism ; ultrastructure ; Protozoan Proteins ; genetics ; metabolism ; Recombinant Proteins ; genetics ; metabolism

The sequestration of infected erythrocytes in the placenta can activate the syncytiotrophoblast to release cytokines that affect the micro-environment and influence the delivery of nutrients and oxygen to fetus. The high level of IL-10 has been reported in the intervillous space and could prevent the pathological effects. There is still no data of Th17 involvement in the pathogenesis of placental malaria. This study was conducted to reveal the influence of placental IL-17 and IL-10 levels on fetal weights in malaria placenta. Seventeen pregnant BALB/C mice were divided into control (8 pregnant mice) and treatment group (9 pregnant mice infected by Plasmodium berghei). Placental specimens stained with hematoxylin and eosin were examined to determine the level of cytoadherence by counting the infected erythrocytes in the intervillous space of placenta. Levels of IL-17 and IL-10 in the placenta were measured using ELISA. All fetuses were weighed by analytical balance. Statistical analysis using Structural Equation Modeling showed that cytoadherence caused an increased level of placental IL-17 and a decreased level of placental IL-10. Cytoadherence also caused low fetal weight. The increased level of placental IL-17 caused low fetal weight, and interestingly low fetal weight was caused by a decrease of placental IL-10. It can be concluded that low fetal weight in placental malaria is directly caused by sequestration of the parasites and indirectly by the local imbalance of IL-17 and IL-10 levels.
Animals ; Female ; *Fetal Weight ; Humans ; Interleukin-10/*analysis/metabolism ; Interleukin-17/*analysis/metabolism ; Malaria/*metabolism/parasitology/physiopathology ; Male ; Mice ; Mice, Inbred BALB C ; Placenta/*chemistry/metabolism ; Plasmodium berghei/*physiology ; Pregnancy ; Pregnancy Complications, Parasitic/*metabolism/parasitology/physiopathology

Different functions have been attributed to CD4+CD25+Foxp3+ regulatory T-cells (Tregs) during malaria infection. Herein, we describe the disparity in Treg response and pro- and anti-inflammatory cytokines during infection with Plasmodium berghei ANKA between young (3-week-old) and middle-aged (8-month-old) C57BL/6 mice. Young mice were susceptible to cerebral malaria (CM), while the middle-aged mice were resistant to CM and succumbed to hyperparasitemia and severe anemia. The levels of pro-inflammatory cytokines, such as TNF-alpha, in young CM-susceptible mice were markedly higher than in middle-aged CM-resistant mice. An increased absolute number of Tregs 3-5 days post-inoculation, co-occurring with elevated IL-10 levels, was observed in middle-aged CM-resistant mice but not in young CM-susceptible mice. Our findings suggest that Treg proliferation might be associated with the suppression of excessive pro-inflammatory Th1 response during early malaria infection, leading to resistance to CM in the middle-aged mice, possibly in an IL-10-dependent manner.
Aging/*immunology ; Animals ; Cytokines/genetics/metabolism ; Female ; Gene Expression Regulation ; Malaria/*immunology/*parasitology ; Mice ; Plasmodium berghei/*classification ; T-Lymphocytes, Regulatory/classification/*physiology