Metabolites of alveolar Echinococcus as determined by [31P]- and [1H]-nuclear magnetic resonance spectroscopy

In vitro metabolomic footprint of the Echinococcus multilocularis metacestode

Alveolar echinococcosis (AE) is a zoonotic disease that is deadly if left untreated. AE is caused by the larval metacestode stage of the cestode Echinococcus multilocularis. Better knowledge on the host-parasite interface could yield novel targets for improvement of the treatment against AE. We analyzed culture media incubated with in vitro grown E. multilocularis metacestodes by 1H nuclear magnetic resonance spectroscopy to identify the unknown metabolic footprint of the parasite. Moreover, we quantitatively analyzed all amino acids, acetate, glucose, lactate, and succinate in time-course experiments using liquid chromatography and enzymatic assays. The E. multilocularis metacestodes consumed glucose and, surprisingly, threonine and produced succinate, acetate, and alanine as major fermentation products. The metabolic composition of vesicle fluid (VF) from in vitro grown E. multilocularis metacestodes was different from parasite-incubated culture medium with respect to the abundance, but not the spectrum, of metabolites, and some metabolites, in particular amino acids, accumulated in the VF. Overall, this study presents the first characterization of the in vitro metabolic footprint of E. multilocularis metacestodes and VF composition, and it provides the basis for analyses of potentially targetable pathways for future drug development.

Bacterial, Fungal, and Parasitic Infections of the Central Nervous System: Radiologic-Pathologic Correlation and Historical Perspectives

Despite remarkable progress in prevention and treatment, infectious diseases affecting the central nervous system remain an important source of morbidity and mortality, particularly in less-developed countries and in immunocompromised persons. Bacterial, fungal, and parasitic pathogens are derived from living organisms and affect the brain, spinal cord, or meninges. Infections due to these pathogens are associated with a variety of neuroimaging patterns that can be appreciated at magnetic resonance imaging in most cases. Bacterial infections, most often due to Streptococcus, Haemophilus, and Neisseria species, cause significant meningitis, whereas the less common cerebritis and subsequent abscess formation have well-documented progression, with increasingly prominent altered signal intensity and corresponding contrast enhancement. Atypical bacterial infections are characterized by the development of a granulomatous response, classically seen in tuberculosis, in which the tuberculoma is the most common parenchymal form of the disease; spirochetal and rickettsial diseases are less common. Fungal infections predominate in immunocompromised hosts and are caused by yeasts, molds, and dimorphic fungi. Cryptococcal meningitis is the most common fungal infection, whereas candidiasis is the most common nosocomial infection. Mucormycosis and aspergillosis are characterized by angioinvasiveness and are associated with high morbidity and mortality among immunocompromised patients. In terms of potential exposure in the worldwide population, parasitic infections, including neurocysticercosis, toxoplasmosis, echinococcosis, malaria, and schistosomiasis, are the greatest threat. Rare amebic infections are noteworthy for their extreme virulence and high mortality. The objective of this article is to highlight the characteristic neuroimaging manifestations of bacterial, fungal, and parasitic diseases, with emphasis on radiologic-pathologic correlation and historical perspectives.

Partial reverse of the TCA cycle is enhanced in Taenia crassiceps experimental neurocysticercosis after in vivo treatment with anthelminthic drugs

Neurocysticercosis (NCC) is the most common helminthic infection and neglected disease of the central nervous system. It is the leading cause of acquired epilepsy and seizures worldwide. Therefore, to study this important neglected disease, it is important to use experimental models. There is no report in the literature on how the parasite's metabolism reacts to antihelminthic treatment when it is still within the central nervous system of the host. Therefore, the aim of this study was to investigate the energetic metabolism of cysticerci experimentally inoculated in the encephala of BALB/c mice after treatment with low dosages (not sufficient to kill the parasite) of albendazole (ABDZ) and praziquantel (PZQ). BALB/c mice were intracranially inoculated with Taenia crassiceps cysticerci and, after 30 days, received treatment with low dosages of ABDZ and PZQ. After 24 h of treatment, the mice were euthanized, and the cysticerci were removed and analyzed through high-performance liquid chromatography (HPLC) to quantify the organic acids related to the energetic metabolism of the parasite. The partial reverse of the TCA cycle was enhanced by the ABDZ and PZQ treatments both with the higher dosage, as the organic acids of this pathway were significantly increased when compared to the control group and to the other dosages. In conclusion, it was possible to detect the increase of this pathway in the parasites that were exposed to low dosages of ABDZ and PZQ, as it is a mechanism that would amplify the energy production in a hostile environment.

Pilot study on the effect of grounding on delayed-onset muscle soreness

OBJECTIVES

The purpose of this pilot study was to determine whether there are markers that can be used to study the effects of grounding on delayed-onset muscle soreness (DOMS).

DESIGN AND SUBJECTS

Eight (8) healthy subjects were exposed to an eccentric exercise that caused DOMS in gastrocnemius muscles of both legs. Four (4) subjects were grounded with electrode patches and patented conductive sheets connected to the earth. Four (4) control subjects were treated identically, except that the grounding systems were not connected to the earth.

OUTCOME MEASURES

Complete blood counts, blood chemistry, enzyme chemistry, serum and saliva cortisols, magnetic resonance imaging and spectroscopy and pain levels were taken at the same time of day before the eccentric exercise and 24, 48, and 72 hours afterwards. Parameters consistently differing by 10% or more, normalized to baseline, were considered worthy of further study.

RESULTS

Parameters that differed by these criteria included white blood cell counts, bilirubin, creatine kinase, phosphocreatine/inorganic phosphate ratios, glycerolphosphorylcholine, phosphorylcholine, the visual analogue pain scale, and pressure measurements on the right gastrocnemius.

CONCLUSIONS

In a pilot study, grounding the body to the earth alters measures of immune system activity and pain. Since this is the first intervention that appears to speed recovery from DOMS, the pilot provides a basis for a larger study.

The evolution of metabolic profiling in parasitology

The uses of metabolic profiling technologies such as mass spectrometry and nuclear magnetic resonance spectroscopy in parasitology have been multi-faceted. Traditional uses of spectroscopic platforms focused on determining the chemical composition of drugs or natural products used for treatment of parasitic infection. A natural progression of the use of these tools led to the generation of chemical profiles of the parasite in in vitro systems, monitoring the response of the parasite to chemotherapeutics, profiling metabolic consequences in the host organism and to deriving host-parasite interactions. With the dawn of the post-genomic era the paradigm in many research areas shifted towards Systems Biology and the integration of biomolecular interactions at the level of the gene, protein and metabolite. Although these technologies have yet to deliver their full potential, metabolic profiling has a key role to play in defining diagnostic or even prognostic metabolic signatures of parasitic infection and in deciphering the molecular mechanisms underpinning the development of parasite-induced pathologies. The strengths and weaknesses of the various spectroscopic technologies and analytical strategies are summarized here with respect to achieving these goals.

Metabolic viability assessment of cystic echinococcosis using high-field 1H MRS of cyst contents

Cystic echinococcosis is a worldwide disease caused by larval stages of the parasite Echinococcus granulosus (canine tapeworm). In clinical practice, staging of cyst development by ultrasonography (US) has allowed treatment options to be tailored to individual patient needs. However, the empirical correlation between cyst morphology and parasite viability is not always dependable and has, until now, required confirmation by invasive assessment of cyst content by light microscopy (LM), for example. Alternatively, high-field 1H MRS may be used to examine cyst fluid ex vivo and prepare detailed quantitative metabolite profiles, enabling a multivariate metabolomics approach to cyst staging. One-dimensional and two-dimensional 1H and 1H/13C MRS at 600 MHz (14.1 T) was used to analyze 50 cyst aspirates of various US and LM classes. MR parameters and concentrations relative to internal valine were determined for 44 metabolites and four substance classes. The high concentrations of succinate, fumarate, malate, acetate, alanine, and lactate found in earlier studies of viable cysts were confirmed, and additional metabolites such as myo-inositol, sorbitol, 1,5-anhydro-D-glucitol, betaine, and 2-hydroxyisovalerate were identified. Data analysis and cyst classification were performed using univariate (succinate), bivariate (succinate vs fumarate), and multivariate partial least squares discriminant analysis (PSL-DA) methods (with up to 48 metabolite variables). Metabolic classification of 23 viable and 18 nonviable cysts on the basis of succinate alone agreed with LM results. However, for seven samples, LM and MRS gave opposing results. Reclassification of these samples and two unclassified samples by PLS-DA prediction techniques led to a set of 50 samples that could be completely separated into viable and nonviable MRS classes with no overlap, using as few as nine variables: succinate, formate, malate, 2-hydroxyisovalerate, acetate, total protein content, 1,5-anhydro-D-glucitol, alanine, and betaine. Thus, future noninvasive in vivo applications of MRS would appear promising.

Hepatic [2-13C]acetate metabolism by jirds infected with Echinococcus multilocularis

Carbon-13 decoupled 1H spin echo NMR spectroscopy, with and without population inversion, was used to study carbon flow between the host, Meriones unguiculatus, and the parasite, Echinococcus multilocularis. This was accomplished by monitoring [2-13C]acetate metabolism in the liver of jirds infected with metacestodes of this parasite. Thirty minutes after injection of labelled acetate solution into the portal vein, 13C enrichment was observed in hepatic acetate, β–hydroxybutyrate, succinate, alanine, lactate and glucose. For E. multilocularis cysts, at this time,13C enrichment was observed in the same metabolites as in livers and, in addition, citrate. At 120 min there was a significant decrease in the amount of label present in all hepatic metabolites whereas more label was found in the majority of the parasite metabolites. The results confirm that exogenous acetate, through randomization of the 13C in biochemical pathways of host liver, ends up in hepatic glucose. As this biosynthetic route is not available to the parasite, the presence of 13C enriched glucose in the cysts clearly indicates that the parasite is siphoning off glucose that is newly synthesized by the host. At 120 min some of this labelled glucose was stored in parasite glycogen whereas some of it had been catabolized to succinate, alanine, lactate and acetate, end products which are excreted back into the host.

Differentiation of hydatid cyst from cysticercus cyst by proton MR spectroscopy

The metabolite patterns obtained by ex vivo proton MR spectroscopy of fluid from different locations of hydatid cysts of sheep and humans (n = 16) and cysticercus cysts of swine and humans (n = 25) were compared with an objective of differentiating the two parasites on the basis of their metabolite pattern. The spectra from hydatid fluid differed from cysticercus cyst by the absence of creatine in the former. When the hydatid cyst was fertile, malate and/or fumarate was also observed, which was absent in cysticercus cyst. The most likely explanation for the presence of creatine only in the cysticercus fluid is its active diffusion from the surrounding host tissue along with a contribution from the musculature present in the bladder wall of the cyst.

Fertility assessment of hydatid cyst by proton MR spectroscopy

BACKGROUND

Hydatid cysts, the larvae of the parasite Echinococcus granulosus, may lodge in any organ of intermediate hosts, namely, man and sheep. Complete cyst removal is the treatment of choice; however, spillage of fertile cysts during surgery leads to disease recurrence that may be prevented by preoperative detection of the fertility status of the cyst. With this perspective, ex vivo proton (1H) MR spectroscopy of hydatid fluid of human and sheep origin was performed to differentiate fertile from sterile cysts on the basis of their metabolite pattern.

PATIENTS AND MATERIALS

Cysts of sheep and human origin were used as source of hydatid fluid. A fraction of this fluid was tested for cyst fertility and the rest was used for ex vivo1H spectroscopy. Histopathology of the cyst wall was done as a gold standard for this study.

RESULTS

Of 10 sheep samples, 7 were fertile and 3 were sterile, while among 6 human samples, 5 were fertile and 1 was sterile. Spectroscopic and histopathological results corroborated each other. The fluid from microbiologically proven fertile cysts contained malate and fumarate along with other resonances and the histopathology of the fertile cyst wall demonstrated germinal lining and protoscoleces.

CONCLUSIONS

The ex vivo spectroscopic differentiation of fertile and sterile cysts may be a stepping-stone for their in vivo separation in future and thus help in framing strategies for percutaneous/surgical management.

Efficacies of albendazole sulfoxide and albendazole sulfone against In vitro-cultivated Echinococcus multilocularis metacestodes

The metacestode stage of Echinococcus multilocularis is the causative agent of alveolar echinococcosis (AE), a parasitic disease affecting the liver, with occasional metastasis into other organs. Benzimidazole carbamate derivatives such as mebendazole and albendazole are currently used for chemotherapeutic treatment of AE. Albendazole is poorly resorbed and is metabolically converted to its main metabolite albendazole sulfoxide, which is believed to be the active component, and further to albendazole sulfone. Chemotherapy with albendazole has been shown to have a parasitostatic rather than a parasitocidal effect; it is not effective in all cases, and the recurrence rate is rather high once chemotherapy is stopped. Thus, development of new means of chemotherapy of AE is needed. This could include modifications of benzimidazoles and elucidiation of the respective biological pathways. In this study we performed in vitro drug treatment of E. multilocularis metacestodes with albendazole sulfoxide and albendazole sulfone. High-performance liquid chromatography analysis of vesicle fluids showed that the drugs were taken up rapidly by the parasite. Transmission electron microscopic investigation of parasite tissues and nuclear magnetic resonance spectroscopy of vesicle fluids demonstrated that albendazole sulfoxide and albendazole sulfone had similar effects with respect to parasite ultrastructure and changes in metabolites in vesicle fluids. This study shows that the in vitro cultivation model presented here provides an ideal first-round test system for screening of antiparasite drugs.

Treatment of experimental alveolar echinococcosis with albendazole: a 1H NMR spectroscopic study

The Meriones unguiculatus (jird) – Echinococcus multilocularis host–parasite model was used to evaluate metabolic changes in livers and cysts treated with albendazole (ABZ). Hydrogen-1 nuclear magnetic resonance spectra of liver extracts showed that livers of uninfected jirds fed olive oil contained more glycine but less glycerophosphocholine (GPC) than those of uninfected untreated controls. When ABZ was added to the olive oil and tested on uninfected animals, other modifications in the metabolic profile of the liver could be seen. While the concentration of GPC stayed reduced and that of glycine reverted to normal, the levels of glycogen, phosphocreatine/creatine (PCr/Cr), succinate, and acetate were lower than those in the normal liver. The metabolic pathology in this organ was further magnified in jirds infected with E. multilocularis. In this case, the liver was depleted of glycogen, glucose, taurine, GPC, and acetate, but had more betaine, phosphocholine, choline, PCr/Cr, and succinate. These abnormalities were markedly diminished by ABZ treatment, with only glycogen, GPC, and acetate concentrations being low when the treatment was terminated. Also, the drug suppressed the growth of the parasite by 75%, and extracts of these parasite cysts contained less glycogen, glycine, succinate, acetate, and alanine but more taurine, GPC, and PCr/Cr than extracts of those from untreated hosts.

In vivo proton magnetic resonance spectroscopy in a case of intracranial hydatid cyst

We performed in vivo proton magnetic resonance spectroscopy (MRS) in a patient who had an intracranial hydatid cyst. Besides lactate, alanine, and acetate, a large resonance for pyruvate was observed. These findings were further confirmed by ex vivo high-resolution NMR spectroscopy of the evacuated cyst fluid, as well as of the fluid aspirated from a cyst in the liver of the same patient. The MRS pattern appeared different from that seen in other cystic lesions of the CNS. In vivo MRS may be used as an adjunct to imaging in the diagnosis of intracranial hydatid cysts. It may also have a role in monitoring drug therapy.

Metabolism ofD-[1-13C]glucose in livers ofMeriones unguiculatusinfected withEchinococcus multilocularis

Following administration of [1-13C]glucose, sequential13C nuclear magnetic resonance (NMR) in situ spectra were obtained from the liver of uninfected jirds (Meriones unguiculatus) and those infected with Echinococcus multilocularis over a period of 2 h. Quantitative evaluation of the flow of labelled carbon through the liver at 80 and 120 min after glucose administration revealed that although the percentage of labelled glucose utilized by the liver was the same for both groups, glycogen synthesis differed. At both times, the livers of infected animals had incorporated a smaller percentage of the [1-13C]glucose into glycogen labelled at C1and a larger percentage into the C6position of glucose/glycogen. In another experiment, identical with respect to the substrate administered, NMR analysis of perchloric acid extracts revealed that the livers of infected animals had lower concentrations of labelled glucose and glycogen and higher concentrations of labelled alanine and lactate than those of uninfected controls. Concentration differences were also noted for some of the unlabelled metabolites. Echinococcus multilocularis cysts contained the same labelled metabolites as the livers but the concentration of lactate was much higher. Parasite cysts also contained labelled acetate.

Metabolic alterations in organs of Meriones unguiculatus infected with Echinococcus multilocularis

1. 1H-NMR spectra of liver, spleen and kidney extracts from Meriones unguiculatus infected with Echinococcus multilocularis showed decreased levels of glucose. In addition, the liver extracts were severely glycogen-depleted. 2. Both livers and spleens contained less glycine, taurine and acetate. Spleens also had fewer cholines and less lactate but more betaine and alanine. 3. In the kidneys, elevated concentrations of succinate, acetate and lactate were found.