Clinical peptidomic analysis by a one-step direct transfer technology: Its potential utility for monitoring of pathophysiological status in female reproductive system disorders

Neuroproteomics Chip-Based Mass Spectrometry and Other Techniques for Alzheimer´S Disease Biomarkers – Update

Background:

Alzheimer's disease (AD) is a progressive neurodegenerative disease of growing interest given that there is cognitive damage and symptom onset acceleration. Therefore, it is important to find AD biomarkers for early diagnosis, disease progression, and discrimination of AD and other diseases.

Objective:

To update the relevance of mass spectrometry for the identification of peptides and proteins involved in AD useful as discriminating biomarkers.

Methods:

Proteomics and peptidomics technologies that show the highest possible specificity and selectivity for AD biomarkers are analyzed, together with the biological fluids used. In addition to positron emission tomography and magnetic resonance imaging, MALDI-TOF mass spectrometry is widely used to identify proteins and peptides involved in AD. The use of protein chips in SELDI technology and electroblotting chips for peptides makes feasible small amounts (L) of samples for analysis.

Results:

Suitable biomarkers are related to AD pathology, such as intracellular neurofibrillary tangles; extraneuronal senile plaques; neuronal and axonal degeneration; inflammation and oxidative stress. Recently, peptides were added to the candidate list, which are not amyloid-b or tau fragments, but are related to coagulation, brain plasticity, and complement/neuroinflammation systems involving the neurovascular unit.

Conclusion:

The progress made in the application of mass spectrometry and recent chip techniques is promising for discriminating between AD, mild cognitive impairment, and matched healthy controls. The application of this technique to blood samples from patients with AD has shown to be less invasive and fast enough to determine the diagnosis, stage of the disease, prognosis, and follow-up of the therapeutic response.

Associations of cardiovascular risk with circulating peptides related to hypertensive disorders of pregnancy

We previously identified seven peptides in serum that are associated with hypertensive disorders of pregnancy (HDP). However, the significance of these peptides in the general population is unknown. The aim of this study was to clarify the relationships of HDP-associated peptides with hypertension and other cardiovascular risks in adult men. We investigated the relationships of peptide levels with cardiovascular risk factors, including adiposity, blood pressure, blood lipids and glycemic status, in men (mean age: 46.4 years) who were receiving annual health checkups at their workplace. The concentrations of the abovementioned seven peptides in serum were measured simultaneously using a mass spectrometer. Among the seven peptides, only a peptide with m/z 2091 (P-2091) derived from fibrinogen-α showed a significant correlation with diastolic blood pressure (Spearman's rank correlation coefficient [r], -0.446). Another peptide with m/z 2378 (P-2378) originating from complement component 4 showed a significant positive correlation with body mass index (r, 0.273) and a significant inverse correlation with HDL cholesterol (r, -0.336). In addition, a peptide with m/z 3156 (P-3156) derived from an inter-α-trypsin inhibitor showed significant inverse correlations with body mass index (r, -0.258) and triglycerides (r, -0.334). There was no significant correlation of the levels of any of the seven peptides with hemoglobin A1c. Among the seven peptides related to HDP, P-2091, P-2378 and P-3156 were inversely associated with diastolic blood pressure, HDL cholesterol and triglycerides, respectively. Therefore, these peptides are possible biomarkers for discriminating cardiovascular risk in a general population.

Exploration of novel biomarkers for hypertensive disorders of pregnancy by comprehensive analysis of peptide fragments in blood: their potential and technologies supporting quantification

Among the many complications associated with pregnancy, hypertensive disorders of pregnancy (HDP) constitute one of the most important. Since the pathophysiology of HDP is complex, new disease biomarkers (DBMs) are needed to serve as indicators of disease activity. However, in the current status of laboratory medicine, despite the fact that blood pressure measurement has been used for a long time, not many DBMs contribute adequately to the subsequent diagnosis and treatment. In this article, we discuss studies focusing on peptide fragments in blood identified by comprehensive quantitative methods, among the currently proposed DBM candidates. Furthermore, we describe the basic techniques of peptidomics, especially quantitative proteomics, and outline the current status and challenges of measuring peptides in blood as DBM for HDP.

Hypertensive disorders of pregnancy: Strategy to develop clinical peptide biomarkers for more accurate evaluation of the pathophysiological status of this syndrome

Hypertensive disorders of pregnancy (HDP) is the most common and widely known as serious complication of pregnancy. As this syndrome is a major leading cause of maternal, fetal, and neonatal morbidity/mortality worldwide, many studies have sought to identify candidate molecules as potential disease biomarkers (DBMs) for use in clinical examinations. Accumulating evidence over the past 2 decades that the many proteolytic peptides appear in human humoral fluids, including peripheral blood, in association with an individual's health condition. This review provides the potential utility of peptidomic analysis for monitoring for pathophysiological status in HDP, and presents an overview of current status of peptide quantification technology. Especially, the technical limitations of the methods used for DBM discovery in the blood are discussed.

The simultaneous quantification of candidate serum biomarker peptides for hypertensive disorders of pregnancy

Background

Hypertensive disorders of pregnancy are defined as syndromes characterized by high blood pressure that develop after 20 weeks of pregnancy. The pathogenesis of hypertensive disorders of pregnancy has not been fully elucidated, and the most effective treatment is the termination of pregnancy. Therefore, methods for an early predictive diagnosis should be developed to rescue both the mother and the child.

Methods

Previously, we explored the serum peptides whose concentration varied specifically between patients with hypertensive disorders of pregnancy and normal pregnant women using peptidomics analysis and identified seven candidate marker peptides. To quantify the marker peptides more reliably, we attempted to quantify these peptides simultaneously by multiple reaction monitoring using liquid chromatography/tandem mass spectrometry (LC-MRM/MS). Non-labelled and stable isotope-labelled forms of the seven peptides were synthesized as standards, and the multiple reaction monitoring transitions for their quantification were determined.

Results

As the retention of the peptides by the reversed-phase column was dependent on their hydrophobicity, two solvent compositions were required for the retention of all peptides. Under these conditions, we detected the peptides by LC-MRM/MS using a column-switching method. Further, we succeeded in quantifying the peptides in the serum of pregnant women using stable isotope dilution.

Conclusion

Our new peptidomics method has great value for peptides, particularly those that have no specific antibody as a detection tool. Using this system, the serum peptides in patients with hypertensive disorders of pregnancy can be validated as diagnostic markers of hypertensive disorders of pregnancy. Further, this method can potentially be applied to the general quantification of other serum peptides.

Quantitative measurement of a candidate serum biomarker peptide derived from α2-HS-glycoprotein, and a preliminary trial of multidimensional peptide analysis in females with pregnancy-induced hypertension

Purpose

We previously attempted to develop quantitative enzyme-linked immunosorbent assay (ELISA) systems for the PDA039/044/071 peptides, potential serum disease biomarkers (DBMs) of pregnancy-induced hypertension (PIH), primarily identified by a peptidomic approach (BLOTCHIP®-mass spectrometry (MS)). However, our methodology did not extend to PDA071 (cysteinyl α2-HS-glycoprotein341–367), due to difficulty to produce a specific antibody against the peptide. The aim of the present study was to establish an alternative PDA071 quantitation system using liquid chromatography-multiple reaction monitoring (LC-MRM)/MS, to explore the potential utility of PDA071 as a DBM for PIH.

Methods

We tested heat/acid denaturation methods in efforts to purify serum PDA071 and developed an LC-MRM/MS method allowing for specific quantitation thereof. We measured serum PDA071 concentrations, and these results were validated including by three-dimensional (3D) plotting against PDA039 (kininogen-1439–456)/044 (kininogen-1438–456) concentrations, followed by discriminant analysis.

Results

PDA071 was successfully extracted from serum using a heat denaturation method. Optimum conditions for quantitation via LC-MRM/MS were developed; the assayed serum PDA071 correlated well with the BLOTCHIP® assay values. Although the PDA071 alone did not significantly differ between patients and controls, 3D plotting of PDA039/044/071 peptide concentrations and construction of a Jackknife classification matrix were satisfactory in terms of PIH diagnostic precision.

Conclusions

Combination analysis using both PDA071 and PDA039/044 concentrations allowed PIH diagnostic accuracy to be attained, and our method will be valuable in future pathophysiological studies of hypertensive disorders of pregnancy.

Simple quantitation for potential serum disease biomarker peptides, primarily identified by a peptidomics approach in the serum with hypertensive disorders of pregnancy

BACKGROUND

We previously reported peptide candidates of disease biomarkers for pregnancy-induced hypertension syndrome using a novel peptidomic analytical method, BLOTCHIP®-MS. The aim of this study was to establish a sandwich enzyme-linked immunosorbent assay system for quantitation of such peptides and to validate their usefulness as disease biomarkers of pregnancy-induced hypertension syndrome including gestational hypertension/pre-eclampsia.

METHODS

We focused on three peptide fragments, kininogen-1439-456 (PDA039), kininogen-1438-456 (PDA044) and cysteinyl α2-HS-glycoprotein341-367 (PDA071). Using polyclonal antibodies specific for each peptide, suitable conditions for the sandwich enzyme-linked immunosorbent assay system were investigated. The quantitative enzyme-linked immunosorbent assay values were confirmed by quantitative matrix assisted laser desorption/ionization time-of-flight MS analyses. Using the established enzyme-linked immunosorbent assay systems, serum samples from gestational hypertension/pre-eclampsia patients and paired serum samples from healthy pregnant females were analysed.

RESULTS

The optimum sandwich enzyme-linked immunosorbent assay conditions for PDA039/044 quantitation were developed. Quantitation of PDA071 by enzyme-linked immunosorbent assay failed, presumably due to issues with polyclonal antibody specificity for the native peptide. Bland-Altman plots showed a satisfactory correlation between the serum PDA039/044 concentration by enzyme-linked immunosorbent assay and that by quantitative MS analysis. Although the PDA044 concentration showed no significant change during pregnancy, including gestational hypertension/pre-eclampsia patients, the serum PDA039 concentration was significantly increased (P < 0.0001) in the patients.

CONCLUSIONS

The simple quantitation technology for PDA039 by enzyme-linked immunosorbent assay was established for the first time. PDA039 confirmed its clinical utility as a disease biomarker for gestational hypertension/pre-eclampsia by the enzyme-linked immunosorbent assay system using clinical samples. The information provided from the present study would be a new valuable addition in the field of gestational hypertension/pre-eclampsia research.