MyCartis NV.

MyCartis NV, a new player on the clinical and translational research market, aims at revolutionizing current healthcare systems. These are mostly based on treating the diseased rather than on caring better and longer for the healthy. The 'one size fits all' model is no longer sufficient and is unsustainable in the long run. Although it comes very scattered, today's access to molecular information has the potential to make healthcare more personal and effective, shifting it from treating diseases to improving quality of life. MyCartis wants to contribute to this process by developing broadly available next generation multiplex biomarker analysis solutions both at the technical and content levels. The Evalution™ platform provides a 'one technology fits all' solution to enable researchers to validate their biomarkers and assay providers to utilize them, no matter their physical nature: multiplexing in its true sense. The ability to quantify different types of markers on a single platform will help produce more comprehensive and coherent multiplex datasets, which will facilitate the integration into syndromic assay formats.

The identification of three novel biomarkers of major adverse kidney events.

AIM: To describe the prognostic value of three novel biomarkers for acute adverse kidney events compared with routine biological markers. MATERIAL & METHODS: We used high-end MS to quantify biomarkers predictive of acute kidney injury (AKI) and major adverse kidney events (MAKE) in 100 adult patients after open heart surgery (n = 100). RESULTS: Early postoperatively measured LG3 (a C-terminal fragment of perlecan), LTBP2 (latent transforming growth factor binding protein-2), Cathepsin L as well as two other renal biomarkers (NGAL, Cystatin C) had greater predictive value for AKI (n = 23) and MAKE (n = 24) compared with creatinine, urea and urine output. CONCLUSIONS: LG3, LTBP2 and Cathepsin L deserve further exploration as biomarkers for the early identification of patients at risk of MAKE.

Integrated proteomics pipeline yields novel biomarkers for predicting preeclampsia.

Preeclampsia, a hypertensive pregnancy complication, is largely unpredictable in healthy nulliparous pregnant women. Accurate preeclampsia prediction in this population would transform antenatal care. To identify novel protein markers relevant to the prediction of preeclampsia, a 3-step mass spectrometric work flow was applied. On selection of candidate biomarkers, mostly from an unbiased discovery experiment (19 women), targeted quantitation was used to verify and validate candidate biomarkers in 2 independent cohorts from the SCOPE (SCreening fOr Pregnancy Endpoints) study. Candidate proteins were measured in plasma specimens collected at 19 to 21 weeks' gestation from 100 women who later developed preeclampsia and 200 women without preeclampsia recruited from Australia and New Zealand. Protein levels (n=25), age, and blood pressure were then analyzed using logistic regression to identify multimarker models (maximum 6 markers) that met predefined criteria: sensitivity ≥50% at 20% positive predictive value. These 44 algorithms were then tested in an independent European cohort (n=300) yielding 8 validated models. These 8 models detected 50% to 56% of preeclampsia cases in the training and validation sets; the detection rate for preterm preeclampsia cases was 80%. Validated models combine insulin-like growth factor acid labile subunit and soluble endoglin, supplemented with maximally 4 markers of placental growth factor, serine peptidase inhibitor Kunitz type 1, melanoma cell adhesion molecule, selenoprotein P, and blood pressure. Predictive performances were maintained when exchanging mass spectrometry measurements with ELISA measurements for insulin-like growth factor acid labile subunit. In conclusion, we demonstrated that biomarker combinations centered on insulin-like growth factor acid labile subunit have the potential to predict preeclampsia in healthy nulliparous women.

Unbiased plasma proteomics for novel diagnostic biomarkers in cardiovascular disease: identification of quiescin Q6 as a candidate biomarker of acutely decompensated heart failure.

AIMS: Biochemical marker testing has improved the evaluation and management of patients with cardiovascular diseases over the past decade. Natriuretic peptides (NPs), used in clinical practice to assess cardiac dysfunction, exhibit many limitations, however. We used an unbiased proteomics approach for the discovery of novel diagnostic plasma biomarkers of heart failure (HF). METHODS AND RESULTS: A proteomics pipeline adapted for very low-abundant plasma proteins was applied to clinical samples from patients admitted with acute decompensated HF (ADHF). Quiescin Q6 (QSOX1), a protein involved in the formation of disulfide bridges, emerged as the best performing marker for ADHF (with an area under the receiver operator characteristic curve of 0.86, 95% confidence interval: 0.79-0.92), and novel isoforms of NPs were also identified. Diagnostic performance of QSOX1 for ADHF was confirmed in 267 prospectively collected subjects of whom 76 had ADHF. Combining QSOX1 to B-type NP (BNP) significantly improved diagnostic accuracy for ADHF by particularly improving specificity. Using thoracic aortic constriction in rats, QSOX1 was specifically induced within both left atria and ventricles at the time of HF onset. CONCLUSION: The novel biomarker QSOX1 accurately identifies ADHF, particularly when combined with BNP. Through both clinical and experimental studies we provide lines of evidence for a link between ADHF and cardiovascular production of QSOX1.

The novel marker LTBP2 predicts all-cause and pulmonary death in patients with acute dyspnoea.

The risk stratification in patients presenting with acute dyspnoea remains a challenge. We therefore conducted a prospective, observational cohort study enrolling 292 patients presenting to the emergency department with acute dyspnoea. A proteomic approach for antibody-free targeted protein quantification based on high-end MS was used to measure LTBP2 [latent TGF (transforming growth factor)-binding protein 2] levels. Final diagnosis and death during follow-up were adjudicated blinded to LTBP2 levels. AHF (acute heart failure) was the final diagnosis in 54% of patients. In both AHF (P<0.001) and non-AHF (P=0.015) patients, LTBP2 levels at presentation were significantly higher in non-survivors compared with survivors with differences on median levels being 2.2- and 1.5-fold respectively. When assessing the cause of death, LTBP2 levels were significantly higher in patients dying from pulmonary causes (P=0.0005). Overall, LTBP2 powerfully predicted early pulmonary death {AUC (area under the curve), 0.95 [95% CI (confidence interval), 0.91-0.98]}. In ROC (receiver operating characteristic) curve analyses for the prediction of 1-year mortality LTBP2 achieved an AUC of 0.77 (95% CI, 0.71-0.84); comparable with the predictive potential of NT-proBNP [N-terminal pro-B-type natriuruetic peptide; 0.77 (95% CI, 0.72-0.82)]. Importantly, the predictive potential of LTBP2 persisted in patients with AHF as the cause of dypnea (AUC 0.78) and was independent of renal dysfunction (AUC 0.77). In a multivariate Cox regression analysis, LTBP2 was the strongest independent predictor of death [HR (hazard ratio), 3.76 (95% CI, 2.13-6.64); P<0.0001]. In conclusion, plasma levels of LTBP2 present a novel and powerful predictor of all-cause mortality, and particularly pulmonary death. Cause-specific prediction of death would enable targeted prevention, e.g. with pre-emptive antibiotic therapy.

GlycoFibroTest is a highly performant liver fibrosis biomarker derived from DNA sequencer-based serum protein glycomics.

Liver fibrosis is currently assessed by liver biopsy, a costly and rather cumbersome procedure that is unsuitable for frequent patient monitoring, which drives research into biomarkers for this purpose. To investigate whether the serum N-glycome contains information suitable for this goal, we developed a 96-well plate-based serum N-glycomics sample preparation protocol that only involves fluid transfer steps and incubations in a PCR thermocycler yielding 8-aminopyrene-1,3,6-trisulfonic acid-labeled N-glycans. These N-glycans are then ready for analysis on the capillary electrophoresis-based DNA sequencers that are the current standard in clinical genetics laboratories worldwide. Subsequently we performed a multicenter, blinded study of 376 consecutive chronic hepatitis C virus patients for which liver biopsies and extensive serum biochemistry data were available. Among patients, the METAVIR fibrosis stage distribution was as follows: 10.6% F0, 44.4% F1, 20.5% F2, 18.4% F3, and 6.1% F4. We found that the ratio of two N-glycans, here called GlycoFibroTest, correlates with the histological fibrosis stage equally well as FibroTest (rho = 0.4-0.5 in F1-F4), which is used in the clinic today. Finally using affinity chromatography we depleted sera of immunoglobulin G, and this resulted in a complete removal of the undergalactosylated biantennary glycans from the N-glycome, which are partially determining GlycoFibroTest.

E-selectin receptors on human leukocytes.

Selectins on activated vascular endothelium mediate inflammation by binding to complementary carbohydrates on circulating neutrophils. The human neutrophil receptor for E-selectin has not been established. We report here that sialylated glycosphingolipids with 5 N-acetyllactosamine (LacNAc, Galbeta1-4GlcNAcbeta1-3) repeats and 2 to 3 fucose residues are major functional E-selectin receptors on human neutrophils. Glycolipids were extracted from 10(10) normal peripheral blood human neutrophils. Individual glycolipid species were resolved by chromatography, adsorbed as model membrane monolayers and selectin-mediated cell tethering and rolling under fluid shear was quantified as a function of glycolipid density. E-selectin-expressing cells tethered and rolled on selected glycolipids, whereas P-selectin-expressing cells failed to interact. Quantitatively minor terminally sialylated glycosphingolipids with 5 to 6 LacNAc repeats and 2 to 3 fucose residues were highly potent E-selectin receptors, constituting more than 60% of the E-selectin-binding activity in the extract. These glycolipids are expressed on human blood neutrophils at densities exceeding those required to support E-selectin-mediated tethering and rolling. Blocking glycosphingolipid biosynthesis in cultured human neutrophils diminished E-selectin, but not P-selectin, adhesion. The data support the conclusion that on human neutrophils the glycosphingolipid NeuAcalpha2-3Galbeta1-4GlcNAcbeta1-3[Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-3](2)[Galbeta1-4GlcNAcbeta1-3](2)Galbeta1-4GlcbetaCer (and closely related structures) are functional E-selectin receptors.

N-glycan profiling in the study of human aging.

Most secreted proteins produced by the human body are modified by glycosylation. It is well known that the oligosaccharides (glycans) of glycoproteins are important for initiation of various cellular recognition signals that are essential for the maintenance of the ordered social life of each cell within a multi-cellular organism. The sugar chains can be altered by the physiological or pathophysiological condition of the cell. We describe a detailed protocol for the analysis of N-linked glycans in blood via DNA sequencing equipment-Fluorophore Assisted Carbohydrate Electrophoresis (DSA-FACE). The key features of this technique are its robustness, high throughput, high sensitivity and reliable quantification. Based on DSA-FACE technology, we previously reported that N-glycan profiling of the human serum shows substantial changes with increasing age in three major N-glycan structures. We proposed that measurement of the N-glycan level changes could provide a surrogate marker for general health or for age-related disease progression, and for monitoring the improvement of health after therapy.

Immunization with an engineered mutant trans-sialidase highly protects mice from experimental Trypanosoma cruzi infection: a vaccine candidate.

Chagas' disease is a major tropical disease for which a cure for chronic phase does not exist yet. Trypanosoma cruzi trans-sialidase (TS) seems to be involved in relevant processes such as infectivity, host survival and, very importantly, disease pathogenesis. In this study, we show that mice vaccinated with an engineered enzymatically deficient mutant TS containing the catalytic domain without the immunodominant SAPA (Shed Acute Phase Antigen) repeats, were highly protected against T. cruzi infection. Adult male BALB/c mice were immunized with mutant protein, purified from Pichia pastoris yeast, using three inoculations in Freund's adjuvant. All immunized mice were protected against challenge with a lethal dose of T. cruzi trypomastigotes. The protected immunized mice developed no clinical or tissue evidence of infection throughout the study. In contrast, 60-90% mortality and 100% occurrence of myocardial lesions were observed in the non-immunized counterparts. Titers of circulating antibody against TS did not correlate with protection, while anti-SAPA antibodies were coincident with disease severity. Further studies indicated that a single inoculation of mutant recombinant protein in Freund's complete adjuvant was not associated with blood or organic alterations, per se. Mutant TS vaccination seems to be a promising tool for immune intervention strategies in Chagas' disease, aimed at preventing T. cruzi-related heart tissue damage.

N-glycomic changes in serum proteins during human aging.

N-glycan profiling of the human serum glycoproteins including immunoglobulin fraction on different age groups of healthy persons shows substantial changes with increasing age in three major N-glycan structures. In individuals more than 40-50 years of age, there is an increase in under-galactosylated glycans and a decrease in the core alpha-1,6-fucosylated bi-galactosylated biantennary structure. These three glycan structures are also substantially changed in a Werner syndrome patient, to a level comparable or even more pronounced than those observed in a healthy Italian centenarian population. These data show that the glycosylation machineries in both liver cells and B-cells are affected in a similar way by the aging process despite their highly different nature. The observed changes in the glycan structures are indicative that biosynthetic processes are at the basis of the changes, possibly together with changes in serum clearing of glycan-altered proteins. Our data suggest that measurement of the N-glycan level changes could provide a noninvasive surrogate marker for general health or for age-related disease progression, and for monitoring the improvement of health after therapy.

N-glycomic changes in hepatocellular carcinoma patients with liver cirrhosis induced by hepatitis B virus.

UNLABELLED: We evaluated the use of blood serum N-glycan fingerprinting as a tool for the diagnosis of hepatocellular carcinoma (HCC) in patients with cirrhosis induced by hepatitis B virus (HBV). A group of 450 HBV-infected patients with liver fibrosis or cirrhosis with or without HCC were studied. HCC was diagnosed by alpha-fetoprotein (AFP) analysis, ultrasonography, and/or computed tomography and was studied histologically. N-glycan profiles of serum proteins were determined with DNA sequencer-based carbohydrate analytical profiling technology. In this study, we found that a branch alpha(1,3)-fucosylated triantennary glycan was more abundant in patients with HCC than in patients with cirrhosis, patients with fibrosis, and healthy blood donors, whereas a bisecting core alpha(1,6)-fucosylated biantennary glycan was elevated in patients with cirrhosis. The concentration of these 2 glycans and the log ratio of peak 9 to peak 7 (renamed the GlycoHCCTest) were associated with the tumor stage. Moreover, for screening patients with HCC from patients with cirrhosis, the overall sensitivity and specificity of the GlycoHCCTest were very similar to those of AFP. CONCLUSION: This study indicates that a branch alpha(1,3)-fucosylated glycan is associated with the development of HCC. The serum N-glycan profile is a promising noninvasive method for detecting HCC in patients with cirrhosis and could be a valuable supplement to AFP in the diagnosis of HCC in HBV-infected patients with liver cirrhosis. Its use for the screening, follow-up, and management of patients with cirrhosis and HCC should be evaluated further.

Clinical laboratory testing in human medicine based on the detection of glycoconjugates.

The purpose of this review is to provide a concise overview of developments over the last 15 years in the field of laboratory tests in human medicine that are based on the detection of alterations in the glycan part of glycoconjugates. We show how glycosylation-based diagnostic testing is widespread in the current clinical practice, in different formats. To provide the necessary focus in this extremely broad field, we have only included assays that are either in actual clinical use or that are under active development towards clinical use, with some bias towards assays that were recently developed. The fields included are: cancer, infectious disease, genetic defects of glycoconjugate biosynthesis and catabolism, auto-immunity, drug abuse and liver disease. To conclude this review, we provide a viewpoint on the future of the glyco-diagnostics field in terms of novel technologies, especially with regard to the discovery and clinical implementation of biomarkers that are based on pathologically altered endogenous glycotopes.

Trypanosome trans-sialidase mediates neuroprotection against oxidative stress, serum/glucose deprivation, and hypoxia-induced neurite retraction in Trk-expressing PC12 cells.

Trypanosome trans-sialidase (TS) is a sialic acid-transferring enzyme and a novel ligand of tyrosine kinase (TrkA) receptors but not of neurotrophin receptor p75NTR. Here, we show that TS targets TrkB receptors on TrkB-expressing pheochromocytoma PC12 cells and colocalizes with TrkB receptor internalization and phosphorylation (pTrkB). Wild-type TS but not the catalytically inactive mutant TSDeltaAsp98-Glu induces pTrkB and mediates cell survival responses against death caused by oxidative stress in TrkA- and TrkB-expressing cells like those seen with nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). These same effects are not observed in Trk deficient PC12(nnr5) cells, but are re-established in PC12(nnr5) cells stably transfected with TrkA or TrkB, are partially blocked by inhibitors of tyrosine kinase (K-252a), mitogen-activated protein/mitogen-activated kinase (PD98059) and completely blocked by LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3K). Both TrkA- and TrkB-expressing cells pretreated with TS or their natural ligands are protected against cell death caused by serum/glucose deprivation or from hypoxia-induced neurite retraction. The cell survival effects of NGF and BDNF against oxidative stress are significantly inhibited by the neuraminidase inhibitor, Tamiflu. Together, these observations suggest that trypanosome TS mimics neurotrophic factors in cell survival responses against oxidative stress, hypoxia-induced neurite retraction and serum/glucose deprivation.

Dependence of neurotrophic factor activation of Trk tyrosine kinase receptors on cellular sialidase.

A direct link between receptor glycosylation and activation following natural ligand interaction has not been observed. Here, we discover a membrane sialidase-controlling mechanism that depends on ligand binding to its receptor to induce enzyme activity which targets and desialylates the receptor and, consequently, causes the induction of receptor dimerization and activation. We also identify a specific sialyl alpha-2,3-linked beta-galactosyl sugar residue of TrkA tyrosine kinase receptor, which is rapidly targeted and hydrolyzed by the sialidase. Trk-expressing cells and primary cortical neurons following stimulation with specific neurotrophic growth factors express a vigorous membrane sialidase activity. Neuraminidase inhibitors, Tamiflu, BCX1812, and BCX1827, block sialidase activity induced by nerve growth factor (NGF) in TrkA-PC12 cells and by brain-derived neurotrophic factor (BDNF) in primary cortical neurons. In contrast, the neuraminidase inhibitor, 2-deoxy-2,3-dehydro-N-acetylneuraminic acid, specific for plasma membrane ganglioside Neu3 and Neu2 sialidases has no inhibitory effect on NGF-induced pTrkA. The GM1 ganglioside specific cholera toxin subunit B applied to TrkA-PC12 cells has no inhibitory effect on NGF-induced sialidase activity. Neurite outgrowths induced by NGF-treated TrkA-PC12 and BDNF-treated PC12(nnr5) stably transfected with TrkB receptors (TrkB-nnr5) cells are significantly inhibited by Tamiflu. Our results establish a novel mode of regulation of receptor activation by its natural ligand and define a new function for cellular sialidases.

Secretion of functional human enzymes by Tetrahymena thermophila.

BACKGROUND: The non-pathogenic ciliate Tetrahymena thermophila is one of the best-characterized unicellular eucaryotes used in various research fields. Previous work has shown that this unicellular organism provides many biological features to become a high-quality expression system, like multiplying to high cell densities with short generation times in bioreactors. In addition, the expression of surface antigens from the malaria parasite Plasmodium falciparum and the ciliate Ichthyophthirius multifiliis suggests that T. thermophila might play an important role in vaccine development. However, the expression of functional mammalian or human enzymes remains so far to be seen. RESULTS: We have been able to express a human enzyme in T. thermophila using expression modules that encode a fusion protein consisting of the endogenous phospholipase A1 precursor and mature human DNaseI. The recombinant human enzyme is active, indicating that also disulfide bridges are correctly formed. Furthermore, a detailed N-glycan structure of the recombinant enzyme is presented, illustrating a very consistent glycosylation pattern. CONCLUSION: The ciliate expression system has the potential to become an excellent expression system. However, additional optimisation steps including host strain improvement as wells as measures to increase the yield of expression are necessary to be able to provide an alternative to the common E. coli and yeast-based systems as well as to transformed mammalian cell lines.

Glycome mapping on DNA sequencing equipment.

Here we provide a detailed protocol for the analysis of protein-linked glycans on DNA sequencing equipment. This protocol satisfies the glyco-analytical needs of many projects and can form the basis of 'glycomics' studies, in which robustness, high throughput, high sensitivity and reliable quantification are of paramount importance. The protocol routinely resolves isobaric glycan stereoisomers, which is much more difficult by mass spectrometry (MS). Earlier methods made use of polyacrylamide gel-based sequencers, but we have now adapted the technique to multicapillary DNA sequencers, which represent the state of the art today. In addition, we have integrated an option for HPLC-based fractionation of highly anionic 8-amino-1,3,6-pyrenetrisulfonic acid (APTS)-labeled glycans before rapid capillary electrophoretic profiling. This option facilitates either two-dimensional profiling of complex glycan mixtures and exoglycosidase sequencing, or MS analysis of particular compounds of interest rather than of the total pool of glycans in a sample.

Trypanosome trans-sialidase targets TrkA tyrosine kinase receptor and induces receptor internalization and activation.

Trypanosome trans-sialidase (TS) is a sialic acid-transferring enzyme that hydrolyzes alpha2,3-linked sialic acids and transfers them to acceptor molecules. Here we show that a highly purified recombinant TS derived from T. cruzi parasites targets TrkA receptors on TrkA-expressing PC12 cells and colocalizes with TrkA internalization and phosphorylation (pTrkA). Maackia amurensis lectin II (MAL-II) and Sambucus nigra lectin (SNA) block TS binding to TrkA-PC12 cells in a dose-dependent manner with subsequent inhibition of TS colocalization with pTrkA. Cells treated with lectins alone do not express pTrkA. The catalytically inactive mutant TSDeltaAsp98-Glu also binds to TrkA-expressing cells, but is unable to induce pTrkA. TrkA-PC12 cells treated with a purified recombinant alpha2,3-neuraminidase (Streptococcus pneumoniae) express pTrkA. Wild-type TS but not the mutant TSDeltaAsp98-Glu promotes neurite outgrowth in TrkA-expressing PC12 cells. In contrast, these effects are not observed in TrkA deficient PC12nnr5 cells but are reestablished in PC12nnr5 cells stably transfected with TrkA and are significantly blocked by inhibitors of tyrosine kinase (K-252a) and MAP/MEK protein kinase (PD98059). Together these observations suggest for the first time that hydrolysis of sialyl alpha2,3-linked beta-galactosyl residues of TrkA receptors plays an important role in TrkA receptor activation, sufficient to promote cell differentiation (neurite outgrowth) independent of nerve growth factor.

Noninvasive diagnosis of liver cirrhosis using DNA sequencer-based total serum protein glycomics.

We applied our 'clinical glycomics' technology, based on DNA sequencer/fragment analyzers, to generate profiles of serum protein N-glycans of liver disease patients. This technology yielded a biomarker that distinguished compensated cirrhotic from noncirrhotic chronic liver disease patients, with 79% sensitivity and 86% specificity (100% sensitivity and specificity for decompensated cirrhosis). In combination with the clinical chemistry-based Fibrotest biomarker, compensated cirrhosis was detected with 100% specificity and 75% sensitivity. The current 'gold standard' for liver cirrhosis detection is an invasive, costly, often painful liver biopsy. Consequently, the highly specific set of biomarkers presented could obviate biopsy in many cirrhosis patients. This biomarker combination could eventually be used in follow-up examinations of chronic liver disease patients, to yield a warning that cirrhosis has developed and that the risk of complications (such as hepatocellular carcinoma) has increased considerably. Our clinical glycomics technique can easily be implemented in existing molecular diagnostics laboratories.

Anti-ganglioside antibodies bind with enhanced affinity to gangliosides containing very long chain fatty acids.

Gangliosides function in both physiological and pathological molecular recognition. Although much research has focused on the role of ganglioside glycans in recognition, fewer studies have addressed the role of the ceramide moiety. Ceramides of major brain gangliosides are composed predominantly of monounsaturated 18-carbon and 20-carbon long chain bases with a saturated 18-carbon fatty acid amide. In contrast, gangliosides of X-linked adrenoleukodystrophy patients are characterized by abnormal very long chain fatty acids that are proposed to be associated with autoimmune inflammation. In the current study we synthesized and characterized derivatives of the major brain ganglioside GD1a bearing defined very long chain fatty acid amides (C24:0, C24:1, and C26:0). When tested in a solid phase binding assay in the presence of auxiliary membrane lipids, GD1a species with long chain fatty acids were up to 8-fold more potent than normal brain GD1a in binding four different anti-GD1a monoclonal antibodies. These data support the hypothesis that gangliosides bearing very long chain fatty acids are differentially displayed on membranes, which may lead to altered antigenicity.