Alterations in urine, serum and brain metabolomic profiles exhibit sexual dimorphism during malaria disease progression

<p>Abstract</p> <p>Background</p> <p>Metabolic changes in the host in response to <it>Plasmodium </it>infection play a crucial role in the pathogenesis of malaria. Alterations in metabolism of male and female mice infected with <it>Plasmodium berghei </it>ANKA are reported here.</p> <p>Methods</p> <p>¹H NMR spectra of urine, sera and brain extracts of these mice were analysed over disease progression using Principle Component Analysis and Orthogonal Partial Least Square Discriminant Analysis.</p> <p>Results</p> <p>Analyses of overall changes in urinary profiles during disease progression demonstrate that females show a significant early post-infection shift in metabolism as compared to males. In contrast, serum profiles of female mice remain unaltered in the early infection stages; whereas that of the male mice changed. Brain metabolite profiles do not show global changes in the early stages of infection in either sex. By the late stages urine, serum and brain profiles of both sexes are severely affected. Analyses of individual metabolites show significant increase in lactate, alanine and lysine, kynurenic acid and quinolinic acid in sera of both males and females at this stage. Early changes in female urine are marked by an increase of ureidopropionate, lowering of carnitine and transient enhancement of asparagine and dimethylglycine. Several metabolites when analysed individually in sera and brain reveal significant changes in their levels in the early phase of infection mainly in female mice. Asparagine and dimethylglycine levels decrease and quinolinic acid increases early in sera of infected females. In brain extracts of females, an early rise in levels is also observed for lactate, alanine and glycerol, kynurenic acid, ureidopropionate and 2-hydroxy-2-methylbutyrate.</p> <p>Conclusions</p> <p>These results suggest that <it>P. berghei </it>infection leads to impairment of glycolysis, lipid metabolism, metabolism of tryptophan and degradation of uracil. Characterization of early changes along these pathways may be crucial for prognosis and better disease management. Additionally, the distinct sexual dimorphism exhibited in these responses has a bearing on the understanding of the pathophysiology of malaria.</p

Liver Metabolic Alterations and Changes in Host Intercompartmental Metabolic Correlation during Progression of Malaria

1H NMR-based metabonomics was used to investigate the multimodal response of mice to malarial parasite infection by P. berghei ANKA. Liver metabolism was followed by NMR spectroscopy through the course of the disease in both male and female mice. Our results showed alterations in the level of several metabolites as a result of the infection. Metabolites like kynurenic acid, alanine, carnitine, and β-alanine showed significant alteration in the liver, suggesting altered kynurenic acid, glucose, fatty acid and amino acid pathways. Distinct sexual dimorphism was also observed in the global analysis of the liver metabolic profiles. Multiway principal component analysis (MPCA) was carried out on the liver, brain, and serum metabolic profile in order to explore the correlation of liver and brain metabolic profile to the metabolite profile of serum. Changes in such correlation profile also indicated distinct sexual dimorphism at the early stage of the disease. Indications are that the females are able to regulate their metabolism in the liver in such a way to maintain homeostasis in the blood. In males, however, choline in liver showed anticorrelation to choline content of serum indicating a higher phospholipid degradation process. The brain-serum correlation profile showed an altered energy metabolism in both the sexes. The differential organellar responses during disease progression have implications in malaria management

Global host metabolic response to Plasmodium vivax infection: a 1H NMR based urinary metabonomic study

<p>Abstract</p> <p>Background</p> <p><it>Plasmodium vivax </it>is responsible for the majority of malarial infection in the Indian subcontinent. This species of the parasite is generally believed to cause a relatively benign form of the disease. However, recent reports from different parts of the world indicate that vivax malaria can also have severe manifestation. Host response to the parasite invasion is thought to be an important factor in determining the severity of manifestation. In this paper, attempt was made to determine the host metabolic response associated with <it>P. vivax </it>infection by means of NMR spectroscopy-based metabonomic techniques in an attempt to better understand the disease pathology.</p> <p>Methods</p> <p>NMR spectroscopy of urine samples from <it>P. vivax-</it>infected patients, healthy individuals and non-malarial fever patients were carried out followed by multivariate statistical analysis. Two data analysis techniques were employed, namely, Principal Component Analysis [PCA] and Orthogonal Projection to Latent Structure Discriminant Analysis [OPLS-DA]. Several NMR signals from the urinary metabolites were further selected for univariate comparison among the classes.</p> <p>Results</p> <p>The urine metabolic profiles of <it>P. vivax-</it>infected patients were distinct from those of healthy individuals as well as of non-malarial fever patients. A highly predictive model was constructed from urine profile of malarial and non-malarial fever patients. Several metabolites were found to be varying significantly across these cohorts. Urinary ornithine seems to have the potential to be used as biomarkers of vivax malaria. An increasing trend in pipecolic acid was also observed. The results suggest impairment in the functioning of liver as well as impairment in urea cycle.</p> <p>Conclusions</p> <p>The results open up a possibility of non-invasive analysis and diagnosis of <it>P. vivax </it>using urine metabolic profile. Distinct variations in certain metabolites were recorded, and amongst these, ornithine may have the potential of being used as biomarker of malaria. Pipecolic acid also showed increasing trend in the malaria patient compared to the other groups.</p

Glycolysis in Plasmodium falciparum results in modulation of host enzyme activities

Background & objectives: Plasmodium falciparum, the causative agent of the most serious formof malaria, infects about 5–10% of the world human population per year. It is well established thatthe erythrocytic stages of the malaria parasite rely mainly on glycolysis for their energy supply. Inthe present study, the glucose utilisation of erythrocyte population with parasitaemia levels similarto that of malaria patients was measured. The results allowed us to assess the effect of the parasiteson the glucose utilisation of the vast majority of uninfected erythrocytes.Methods: Using [2-13C]glucose and nuclear magnetic resonance (NMR) technique, the glucoseutilisation in normal red blood cell (RBC) and P. falciparum infected red blood cell (IRBC)populations was measured. The IRBC population consisted of > 96% RBC and < 4% of parasiteinfected red blood cells (PRBC). The glycolytic enzymes were assayed to assess the effect ofinfected red cells on the enzymatic activities of uninfected ones.Results: The rate of glucose utilisation by IRBC was considerably higher than that of RBC. Uponaddition of 25% v/v conditioned culture medium (CM) of IRBC, RBCs exhibited a significantdecrease in glucose utilisation. The CM could directly inhibit the activities of RBC glycolyticenzymes—phosphofructokinase (PFK) and pyruvate kinase (PK), without interfering with theactivity of the pentose phosphate pathway enzyme—glucose-6-phosphate dehydrogenase(G-6-PD).Interpretation & conclusion: The present study showed that the clinical level of P. falciparuminfected RBCs (< 4% parasitaemia) significantly enhance the glycolytic flux as well as downregulatethe glucose utilisation rate in the majority of uninfected RBC population. The mechanismof inhibition seems to be direct inhibition of the regulatory glycolytic enzymes—PFK and PK

Malaria parasite-infected erythrocytes inhibit glucose utilization in uninfected red cells

The erythrocytic stages of the malaria parasite depend on anaerobic glycolysis for energy. Using [2-13C]glucose and nuclear magnetic resonance, the glucose utilization rate and 2,3-diphosphoglycerate (2,3-DPG) level produced in normal RBCs and Plasmodium falciparum infected red blood cell populations (IRBCs, with &lt;4% parasite infected red cells), were measured. The glucose flux in IRBCs was several-folds greater, was proportional to parasitemia, and maximal at trophozoite stage. The 2,3-DPG levels were disproportionately lower in IRBCs, indicating a downregulation of 2,3-DPG flux in non-parasitized RBCs. This may be due to lowered pH leading to selective differential inhibition of the regulatory glycolytic enzyme phosphofructokinase. This downregulation of the glucose utilization rate in the majority (&gt;96%) of uninfected RBCs in an IRBC population may have physiological implications in malaria patients

Glycolysis in Plasmodium falciparum results in modulation of host enzyme activities

Background &amp; objectives: Plasmodium falciparum, the causative agent of the most serious form of malaria, infects about 5-10% of the world human population per year. It is well established that the erythrocytic stages of the malaria parasite rely mainly on glycolysis for their energy supply. In the present study, the glucose utilisation of erythrocyte population with parasitaemia levels similar to that of malaria patients was measured. The results allowed us to assess the effect of the parasites on the glucose utilisation of the vast majority of uninfected erythrocytes. Methods: Using [2-13C]glucose and nuclear magnetic resonance (NMR) technique, the glucose utilisation in normal red blood cell (RBC) and P. falciparum infected red blood cell (IRBC) populations was measured. The IRBC population consisted of &gt;96% RBC and lt;4% of parasite infected red blood cells (PRBC). The glycolytic enzymes were assayed to assess the effect of infected red cells on the enzymatic activities of uninfected ones. Results: The rate of glucose utilisation by IRBC was considerably higher than that of RBC. Upon addition of 25% v/v conditioned culture medium (CM) of IRBC, RBCs exhibited a significant decrease in glucose utilisation. The CM could directly inhibit the activities of RBC glycolytic enzymes-phosphofructokinase (PFK) and pyruvate kinase (PK), without interfering with the activity of the pentose phosphate pathway enzyme-glucose-6-phosphate dehydrogenase (G-6-PD). Interpretation &amp; conclusion: The present study showed that the clinical level of P. falciparum infected RBCs (&lt;4% parasitaemia) significantly enhance the glycolytic flux as well as down-regulate the glucose utilisation rate in the majority of uninfected RBC population. The mechanism of inhibition seems to be direct inhibition of the regulatory glycolytic enzymes-PFK and PK

Structural stabilization of [2Fe-2S] ferredoxin from Halobacterium salinarum

The ferredoxin of the extreme haloarchaeon Halobacterium salinarum requires high (>2 M) concentration of salt for its stability. We have used a variety of spectroscopic probes for identifying the structural elements which necessitate the presence of high salt for its stability. Titration of either the fluorescence intensity of the tryptophan residues or the circular dichroism (CD) at 217 nm with salt has identified a structural form at low (&lt;0.1 M) concentration of salt. This structural form (L) exhibits increased solvent exposure of W side chain(s) and decreased level of secondary structure compared to the native (N) protein at high concentrations of salt. The L-form, however, contains significantly higher levels of both secondary and tertiary structures compared to the form (U) found in highly denaturing conditions such as 8 M urea. The structural integrity of the L-form was highly pH dependent while that of N- or U-form was not. The pH dependence of either fluorescence intensity or CD of the L-form showed the presence of two apparent pK values: ~5 and ~10. The structural integrity of the L-form at low (&lt;5) pH was very similar to that of the N-form. However, titration with denaturants showed that the low pH L-form is significantly less stable than the N-form. The increased destabilization of the L-form with the increase in pH was interpreted to be due to mutual Coulombic repulsion of carboxylate side chains (pK ≈ 6) and due to the disruption of salt bridge(s) between ionized carboxylates and protonated amino groups (pK ≈ 10). Estimation of solvent accessibility of W residues by fluorescence quenching, and measurement of decay kinetics of fluorescence intensity and anisotropy strongly support the above model. Polylysine interacted stoichiometrically with the L-form of ferredoxin resulting in nativelike structure. In conclusion, our studies show that high concentration of salt stabilizes the haloarchaeal ferredoxin in two ways: (i) neutralization of Coulombic repulsion among carboxyl groups of the acidic residues, and (ii) salting out of hydrophobic residues leading to their burial and stronger interaction

Glycolysis and Entner-Doudoroff pathways in Halobacterium halobium: some new observations based on <SUP>13</SUP>C NMR spectroscopy

13C NMR was used to study glucose metabolism in intact cells of Halobacterium halobium. Spectra of glucose grown cells incubated with [1-13C] glucose indicate the presence of gluconate as the initial product. The existence of glycolytic pathway is also indicated. In the extracts of these cells an NADP dependent glucose dehydrogenase was detected. Galactose grown cells failed to metabolise glucose but exhibited glucose dehydrogenase activity although about 20-50% less than that for glucose grown cells. Possible explanation of these experiments are discussed