Quantitative phosphoproteome analysis reveals differential whey phosphoproteins of bovine milk during lactation

Whey proteins in bovine milk, as the most widely used nutritional components for infant formulae, have been paid more attention. However, the phosphorylation of proteins in bovine whey during lactation has not been thoroughly researched. In this study, a total of 185 phosphorylation sites on 72 phosphoproteins were identified in bovine whey during lactation. 45 differentially expressed whey phosphoproteins (DEWPPs) in colostrum and mature milk were focused on by bioinformatics approaches. Gene Ontology annotation indicated that blood coagulation, extractive space, and protein binding played a key role in bovine milk. The critical pathway of DEWPPs was related to the immune system according to KEGG analysis. Our study investigated the biological functions of whey proteins from a phosphorylation perspective for the first time. The results elucidate and increase our knowledge of differentially phosphorylation sites and phosphoproteins in bovine whey during lactation. Additionally, the data might offer fresh insight into the development of whey protein nutrition.

Post-translational modifications glycosylation and phosphorylation of the major hepatic plasma protein fetuin-A are associated with CNS inflammation in children

Fetuin-A is a liver derived plasma protein showing highest serum concentrations in utero, preterm infants, and neonates. Fetuin-A is also present in cerebrospinal fluid (CSF). The origin of CSF fetuin-A, blood-derived via the blood-CSF barrier or synthesized intrathecally, is presently unclear. Fetuin-A prevents ectopic calcification by stabilizing calcium and phosphate as colloidal calciprotein particles mediating their transport and clearance. Thus, fetuin-A plays a suppressive role in inflammation. Fetuin-A is a negative acute-phase protein under investigation as a biomarker for multiple sclerosis (MS). Here we studied the association of pediatric inflammatory CNS diseases with fetuin-A glycosylation and phosphorylation. Paired blood and CSF samples from 66 children were included in the study. Concentration measurements were performed using a commercial human fetuin-A/AHSG ELISA. Of 60 pairs, 23 pairs were analyzed by SDS-PAGE following glycosidase digestion with PNGase-F and Sialidase-AU. Phosphorylation was analyzed in 43 pairs by Phos-TagTM acrylamide electrophoresis following alkaline phosphatase digestion. Mean serum and CSF fetuin-A levels were 0.30 ± 0.06 mg/ml and 0.644 ± 0.55 μg/ml, respectively. This study showed that serum fetuin-A levels decreased in inflammation corroborating its role as a negative acute-phase protein. Blood-CSF barrier disruption was associated with elevated fetuin-A in CSF. A strong positive correlation was found between the CSF fetuin-A/serum fetuin-A quotient and the CSF albumin/serum albumin quotient, suggesting predominantly transport across the blood-CSF barrier rather than intrathecal fetuin-A synthesis. Sialidase digestion showed increased asialofetuin-A levels in serum and CSF samples from children with neuroinflammatory diseases. Desialylation enhanced hepatic fetuin-A clearance via the asialoglycoprotein receptor thus rapidly reducing serum levels during inflammation. Phosphorylation of fetuin-A was more abundant in serum samples than in CSF, suggesting that phosphorylation may regulate fetuin-A influx into the CNS. These results may help establish Fetuin-A as a potential biomarker for neuroinflammatory diseases.

Novel Combined Enzymatic Approach to Analyze Nonsialylated N-Linked Glycans through MALDI Imaging Mass Spectrometry

Alterations to N-glycan expression are relevant to the progression of various diseases, particularly cancer. In many cases, specific N-glycan structural features such as sialylation, fucosylation, and branching are of specific interest. A novel MALDI imaging mass spectrometry workflow has been recently developed to analyze these features of N-glycosylation through the utilization of endoglycosidase enzymes to cleave N-glycans from associated glycoproteins. Enzymes that have previously been utilized to cleave N-glycans include peptide-N-glycosidase F (PNGase F) to target N-glycans indiscriminately and endoglycosidase F3 (Endo F3) to target core fucosylated N-glycans. In addition to these endoglycosidases, additional N-glycan cleaving enzymes could be used to target specific structural features. Sialidases, also termed neuraminidases, are a family of enzymes that remove terminal sialic acids from glycoconjugates. This work aims to utilize sialidase, in conjunction with PNGase F/Endo F3, to enzymatically remove sialic acids from N-glycans in an effort to increase sensitivity for nonsialylated N-glycan MALDI-IMS peaks. Improving detection of nonsialylated N-glycans allows for a more thorough analysis of specific structural features such as fucosylation or branching, particularly of low abundant structures. Sialidase utilization in MALDI-IMS dramatically increases sensitivity and increases on-tissue endoglycosidase efficiency, making it a very useful companion technique to specifically detect nonsialylated N-glycans.

Comparative Proteomic Assessment of Normal vs. Polyhydramnios Amniotic Fluid Based on Computational Analysis

Mass spectrometry-based proteomics have become a valued tool for conducting comprehensive analyses in amniotic fluid samples with pathologies. Our research interest is the finding and characterization of proteins related to normal vs. polyhydramnios (non-immune hydrops) pregnancy. Proteomic analysis was performed on proteins isolated from fresh amniotic fluid samples. Proteins were fractionated by 2DE using a different pI range (pI 3–11, pI 4–7) and analyzed with MALDI-TOF-MS. Furthermore, by using computational analysis, identified proteins in protein maps specific to normal vs. polyhydramnios pregnancy were compared and the quantities of expressed proteins were evaluated mathematically. Comparative analysis of proteome characteristic for the same polyhydramnios pregnancy fractionated by 2DE in different pI range (3–11 and 4–7) was performed and particular protein groups were evaluated for the quantification of changes within the same protein level. Proteins of normal and polyhydramnios pregnancies were fractionated by 2DE in pI range 3–11 and in pI range 4–7. Mass spectrometry analysis of proteins has revealed that the quantity changes of the main identified proteins in normal vs. polyhydramnios pregnancy could be assigned to immune response and inflammation proteins, cellular signaling and regulation proteins, metabolic proteins, etc. Specifically, we have identified and characterized proteins associated with heart function and circulatory system and proteins associated with abnormalities in prenatal medicine. The following are: serotransferrin, prothrombin, haptoglobin, transthyretin, alpha-1-antitrypsin, zinc-alpha-2-glycprotein, haptoglobin kininogen-1, hemopexin, clusterin, lumican, afamin, gelsolin. By using computational analysis, we demonstrated that some of these proteins increased a few times in pathological pregnancy. Computer assistance analysis of 2DE images suggested that, for the better isolation of the proteins’ isoforms, those levels increased/decreased in normal vs. polyhydramnios pregnancy, and the fractionation of proteins in pI rage 3–11 and 4–7 could be substantial. We analyzed and identified by MS proteins specific for normal and polyhydramnios pregnancies. Identified protein levels increased and/or modification changed in case of non-immune hydrops fetus and in cases of cardiovascular, anemia, growth restriction, and metabolic disorders. Computational analysis for proteomic characterization empower to estimate the quantitative changes of proteins specific for normal vs. polyhydramnios pregnancies.

New Enzymatic Approach to Distinguish Fucosylation Isomers of N-Linked Glycans in Tissues Using MALDI Imaging Mass Spectrometry

Specific alterations in N-linked glycans, such as core fucosylation, are associated with many cancers and other disease states. Because of the many possible anomeric linkages associated with fucosylated N-glycans, determination of specific anomeric linkages and the site of fucosylation (i.e., core vs outer arm) can be difficult to elucidate. A new MALDI mass spectrometry imaging workflow in formalin-fixed clinical tissues is described using recombinant endoglycosidase F3 (Endo F3), an enzyme with a specific preference for cleaving core-fucosylated N-glycans attached to glycoproteins. In contrast to the broader substrate enzyme peptide-N-glycosidase F (PNGaseF), Endo F3 cleaves between the two core N-acetylglucosamine residues at the protein attachment site. On tissues, this results in a mass shift of 349.137 a.m.u. for core-fucosylated N-glycans when compared to N-glycans released with standard PNGaseF. Endo F3 can be used singly and in combination with PNGaseF digestion of the same tissue sections. Initial results in liver and prostate tissues indicate core-fucosylated glycans associated to specific tissue regions while still demonstrating a diverse mix of core- and outer arm-fucosylated glycans throughout all regions of tissue. By determining these specific linkages while preserving localization, more targeted diagnostic biomarkers for disease states are possible without the need for microdissection or solubilization of the tissue.

Fetuin-A and fetal growth in gestational diabetes mellitus

OBJECTIVE

Fetuin-A is a glycoprotein produced by hepatocytes and has been associated with insulin resistance and bone growth in postnatal life. Gestational diabetes mellitus (GDM) is a condition characterized by insulin resistance. It is unclear whether GDM may affect cord blood fetuin-A levels and whether fetuin-A is associated with fetal growth.

RESEARCH DESIGN AND METHODS

In a nested case-control study of 153 matched pairs of neonates of mothers with GDM and euglycemic pregnancies in the Shanghai Birth Cohort, we evaluated cord blood fetuin-A in association with GDM and fetal growth.

RESULTS

Comparing the newborns of GDM versus euglycemic mothers, cord blood fetuin-A concentrations were similar (mean±SD: 783.6±320.0 vs 754.8±281.9 µg/mL, p=0.53), while insulin-like growth factor (IGF)-I (76.6±27.8 ng/mL vs 68.1±25.1 ng/mL, p=0.008) and IGF-II (195.3±32.5 ng/mL vs 187.5±30.8 ng/mL, p=0.042) concentrations were higher. Cord blood fetuin-A was not correlated with insulin, IGF-I or IGF-II. Cord blood fetuin-A was negatively correlated with birth weight (r=-0.19, p=0.025) and birth length (r=-0.24, p=0.005) z scores in GDM pregnancies, while there were no significant correlations in euglycemic pregnancies (tests for interaction: p=0.014 for birth length, p=0.013 for birth length). Adjusting for maternal and neonatal characteristics, the differential associations remained.

CONCLUSIONS

GDM was not associated with cord blood fetuin-A levels. Fetuin-A was negatively associated with fetal growth in GDM but not in euglycemic pregnancies. This novel observation suggests a GDM-conditional negative correlation of fetuin-A with fetal growth.

Fetuin-A in Infants Born Small- or Large-for-Gestational-Age

Fetuin-A is a multifunctional glycoprotein that has been implicated in insulin resistance and bone metabolism. We assessed whether fetuin-A is associated with poor or excessive fetal growth. In the Shanghai Birth Cohort, we conducted a nested case-control study of 60 trios of small-for-gestational-age (SGA, birth weight <10th percentile), optimal-for-gestational-age (OGA, 25-75th, the reference) and large-for-gestational-age (LGA, >90th percentile) infants matched by sex and gestational age. Cord plasma concentrations of fetuin-A and fetal growth factors [insulin, proinsulin, insulin-like growth factor (IGF)-I and IGF-II] were measured. Cord plasma fetuin-A concentrations were higher in SGA (809.4 ± 306.9 μg/ml, P = 0.026) and LGA (924.2 ± 375.9 μg/ml, P < 0.001) relative to OGA (680.7 ± 262.1 μg/ml) newborns, and were not correlated to insulin, proinsulin, IGF-I and IGF-II (all P > 0.2). Higher fetuin-A concentrations were associated with increased risks of SGA [OR = 1.67 (1.08-2.58) per SD increment, P = 0.024] and LGA [OR = 2.36 (1.53-3.66), P < 0.001]. Adjusting for maternal and neonatal characteristics and fetal growth factors, the elevated risk changed little for LGA [adjusted OR = 2.28 (1.29-4.01), P = 0.005], but became non-significant for SGA (P = 0.202). Our study is the first to demonstrate that fetuin-A may be involved in excessive fetal growth. This association is independent of fetal growth factors.

Can Fetuin-A, CRP, and WBC Levels Be Predictive Values in the Diagnosis of Acute Appendicitis in Children with Abdominal Pain?

Background: Acute appendicitis (AA) is the most common cause of emergency surgery. Therefore, perforation is common. Early diagnosis and new markers are needed. The aim of this study was to investigate the effects of plasma Fetuin-A (FA) levels in patients with an acute abdomen (AB). Material and Method: This prospective study included 107 patients younger than 16 years of age who were admitted to the emergency department for abdominal pain between January and December 2018. The patients who presented abdominal pain were divided into two groups as AA and other causes (OC) of AB. Patients with acute appendicitis; intraperitoneal, retrocolic/retrocecal, and appendicitis were divided into three groups. Additionally, the AA group was divided into two groups as perforated appendicitis and non-perforated appendicitis. Serum FA levels of the patients were evaluated in the emergency department. Results: In the AA group, C-reactive protein (CRP) and white blood cell (WBC) levels were higher, and FA levels were significantly lower than in the AB group. Intraperitoneal localization was 95.2% and perforation was frequent. When significant values in the univariate regression analysis for acute abdomen and perforation were compared in the multivariate regression analysis, CRP, WBC, and FA levels were found to be prognostic. Furthermore, decreased FA levels were associated with AA, while too greatly decreased FA levels were associated with the risk of perforation. Conclusion: Current diagnosis can be made by history, physical examination, laboratory, and imaging methods in appendicitis cases. While trying to diagnose AA in children, the FA, CRP, and WBC levels may be predictive values to identify risk factors.

Maternal plasma fetuin-A levels in fetal growth restriction: A case-control study

Background

Higher Fetuin-A (FA) concentrations were found to be associated with obesity and there is an interest to the relation between maternal FA and pregnancy outcomes.

Objective

In this study, our aim was to evaluate the association of maternal plasma levels of FA with fetal growth restriction (FGR).

Materials and Methods

41 pregnant women with FGR and 40 controls were recruited in this case-control study between July and November 2015. At the diagnosis of FGR, venous blood samples (10 cc) were obtained for FA analysis.

Results

Maternal plasma FA levels were significantly higher in fetal growth-restricted pregnant women compared with controls (19.3 ± 3.0 ng/ml vs 25.9 ± 6.8 ng/ml, p = 0.001). Area under receiver operating characteristic curve analysis of FA in FGR was 0.815 (95% confidence interval (CI): 0.718-0.912, p < 0.001). The maternal FA levels with values more than 22.5 ng/ml had a sensitivity of about 73.17% (95% CI: 56.79-85.25) and a specificity of about 82.5% (95% CI: 66.64-92.11) with positive and negative predictive values of about 81.08% (95% CI: 64.29-91.45) and 75% (95% CI: 59.35-86.30), respectively. Therefore, the diagnostic accuracy was obtained about 77.78%.

Conclusion

The results of this study show higher maternal plasma levels of FA in FGR. Further studies are needed in order to demonstrate the long-term effects of FA in pregnancies complicated with FGR and early prediction of FGR.

Proteomic analysis of adipose tissue during the last weeks of gestation in pure and crossbred Large White or Meishan fetuses gestated by sows of either breed

Background

The degree of adipose tissue development at birth may influence neonatal survival and subsequent health outcomes. Despite their lower birth weights, piglets from Meishan sows (a fat breed with excellent maternal ability) have a higher survival rate than piglets from Large White sows (a lean breed). To identify the main pathways involved in subcutaneous adipose tissue maturation during the last month of gestation, we compared the proteome and the expression levels of some genes at d 90 and d 110 of gestation in purebred and crossbred Large White or Meishan fetuses gestated by sows of either breed.

Results

A total of 52 proteins in fetal subcutaneous adipose tissue were identified as differentially expressed over the course of gestation. Many proteins involved in energy metabolism were more abundant, whereas some proteins participating in cytoskeleton organization were reduced in abundance on d 110 compared with d 90. Irrespective of age, 24 proteins differed in abundance between fetal genotypes, and an interaction effect between fetal age and genotype was observed for 13 proteins. The abundance levels of proteins known to be responsive to nutrient levels such as aldolase and fatty acid binding proteins, as well as the expression levels of FASN, a key lipogenic enzyme, and MLXIPL, a pivotal transcriptional mediator of glucose-related stimulation of lipogenic genes, were elevated in the adipose tissue of pure and crossbred fetuses from Meishan sows. These data suggested that the adipose tissue of these fetuses had superior metabolic functionality, whatever their paternal genes. Conversely, proteins participating in redox homeostasis and apoptotic cell clearance had a lower abundance in Meishan than in Large White fetuses. Time-course differences in adipose tissue protein abundance were revealed between fetal genotypes for a few secreted proteins participating in responses to organic substances, such as alpha-2-HS-glycoprotein, transferrin and albumin.

Conclusions

These results underline the importance of not only fetal age but also maternal intrauterine environment in the regulation of several proteins in subcutaneous adipose tissue. These proteins may be used to estimate the maturity grade of piglet neonates.

Electronic supplementary material

The online version of this article (10.1186/s40104-018-0244-2) contains supplementary material, which is available to authorized users.

Pediatric endocrine and metabolic diseases and proteomics

The principles of Predictive, Preventive and Personalized Medicine (PPPM) dictate the need to recognize individual susceptibility to disease in a timely fashion and to offer targeted preventive interventions and treatments. Proteomics is a state-of-the art technology- driven science aiming at expanding our understanding of the pathophysiologic mechanisms that underlie disease, but also at identifying accurate predictive, diagnostic and therapeutic biomarkers, that will eventually promote the implementation of PPPM. In this review, we summarize the wide spectrum of the applications of Mass Spectrometry-based proteomics in the various fields of Pediatric Endocrinology, including Inborn Errors of Metabolism, type 1 diabetes, Adrenal Disease, Metabolic Syndrome and Thyroid disease, ranging from neonatal screening to early recognition of specific at-risk populations for disease manifestations or complications in adult life and to monitoring of disease progression and response to treatment.

SIGNIFICANCE

Proteomics is a state-of-the art technology- driven science aiming at expanding our understanding of the pathophysiologic mechanisms that underlie disease, but also at identifying accurate predictive, diagnostic and therapeutic biomarkers that will eventually lead to successful, targeted, patient-centric, individualized approach of each patient, as dictated by the principles of Predictive, Preventive and Personalized Medicine. In this review, we summarize the wide spectrum of the applications of Mass Spectrometry-based proteomics in the various fields of Pediatric Endocrinology, including Inborn Errors of Metabolism, type 1 diabetes, Adrenal Disease, Metabolic Syndrome and Thyroid disease, ranging from neonatal screening, accurate diagnosis, early recognition of specific at-risk populations for the prevention of disease manifestation or future complications.

Low-Dose Spironolactone-Pioglitazone-Metformin Normalizes Circulating Fetuin-A Concentrations in Adolescent Girls with Polycystic Ovary Syndrome

BACKGROUND

Fetuin-A is a glycoprotein produced in the liver and related to metabolic syndrome; fetuin-A secretion is divergently regulated in different pathological conditions. In girls with polycystic ovary syndrome (PCOS), insulin sensitization results in a more favorable endocrine-metabolic outcome than oral contraception; we assessed whether those differences are underscored by changes in circulating fetuin-A.

METHODS

Fetuin-A concentration endocrine-metabolic markers and hepatovisceral fat were measured longitudinally in 35 PCOS girls [age, 16 yr; body mass index (BMI), 23 kg/m²] randomized to receive either oral contraception [ethinylestradiol-levonorgestrel (n = 18)] or a low-dose combination of spironolactone, pioglitazone, and metformin (SPIOMET, n = 17) over 12 months. Healthy adolescent girls (age- and BMI-matched) were used as controls (n = 25).

RESULTS

Pretreatment fetuin-A serum levels in PCOS girls were lower than those in controls. After 12 months on treatment, fetuin-A raised to control levels only in the SPIOMET subgroup (P = 0.009, versus oral contraception); this increase was paralleled by a healthier metabolic profile with less hepatic fat (by MRI); baseline serum fetuin-A as well as the changes over 12 months was inversely related to hepatic adiposity.

CONCLUSIONS

A low-dose combination of insulin sensitizers and an antiandrogen-but not oral contraception-normalizes fetuin-A levels in adolescent girls with PCOS. This trial is registered with ISRCTN29234515.

Targeted Measurements of O- and N-Glycopeptides Show That Proteins in High Density Lipoprotein Particles Are Enriched with Specific Glycosylation Compared to Plasma

High density lipoprotein (HDL) particles are believed to be protective due to their inverse correlation with the prevalence of cardiovascular diseases. However, recent studies show that in some conditions such as heart disease and diabetes, HDL particles can become dysfunctional. Great attention has been directed toward HDL particle composition because the relative abundances of HDL constituents determine HDL's functional properties. A key factor to consider when studying the structure and composition of plasma particles is the protein glycosylation. Here, we profile the O- and N-linked glycosylation of HDL associated-proteins including the truncated form of Apo CIII and their glycan heterogeneity in a site-specific manner. Apolipoprotein CIII, fetuin A, and alpha 1 antitrypsin are glycoproteins associated with lipoproteins and are implicated in many cardiovascular and other disease conditions. A targeted method (UHPLC-QQQ) was used to measure the glycoprotein concentrations and site-specific glycovariations of the proteins in human plasma and compared with HDL particles isolated from the same plasma samples. The proteins found in the plasma are differentially glycosylated compared to those isolated in HDL. The results of this study suggest that glycosylation may play a role in protein partitioning in the blood, with possible functional implications.

The Use of Proteomics in Assisted Reproduction

Despite the explosive increase in the use of Assisted Reproductive Technologies (ART) over the last 30 years, their success rates remain suboptimal. Proteomics is a rapidly-evolving technology-driven science that has already been widely applied in the exploration of human reproduction and fertility, providing useful insights into its physiology and leading to the identification of numerous proteins that may be potential biomarkers and/or treatment targets of a successful ART pregnancy. Here we present a brief overview of the techniques used in proteomic analyses and attempt a comprehensive presentation of recent data from mass spectrometry-based proteomic studies in humans, regarding all components of ARTs, including the male and female gamete, the derived zygote and embryo, the endometrium and, finally, the ART offspring both pre- and postnatally.

Proteomics of Children Born After Intracytoplasmic Sperm Injection Reveal Indices of an Adverse Cardiometabolic Profile

CONTEXT

Assisted reproduction technologies (ART), classic in vitro fertilization (IVF), and intracytoplasmic sperm injection (ICSI) are increasingly used. Several studies have demonstrated an unfavorable cardiometabolic profile of the ART offspring. Proteomics is a state-of-the-art technology used for the identification of early biomarkers of disease.

OBJECTIVES

To investigate the proteomic profile of children born after ICSI compared with naturally conceived (NC) controls in search of cardiometabolic risk markers.

DESIGN

Cross-sectional case-control study: qualitative, comparative proteomic plasma analysis.

SETTING

Pediatric Endocrinology and IVF Outpatient Clinics, University of Athens and the Biomedical Research Foundation of the Academy of Athens.

PARTICIPANTS

Forty-two sex- and age-matched couples of ICSI and NC children were assessed. Ten pairs additionally matched for birth weight and twin/single pregnancies were submitted to proteomic analysis.

INTERVENTION

Medical history, clinical examination, and blood biochemical, hormonal, and proteomic analyses.

MAIN OUTCOME MEASURES

(1) Differences in auxological and laboratory data between groups. (2) Differences in plasma proteomic profile in 10 individual pairs and pooled samples.

RESULTS

The ICSI group had shorter gestation, more cesarean sections, smaller birth weight/length, and advanced maternal age. No major differences were observed regarding biochemical markers. Proteomic analysis revealed 19 over- and three underexpressed proteins in ICSI. Most overexpressed proteins are implicated in acute-phase reaction, blood coagulation, complement pathway activation, and iron and lipid metabolism, suggesting a subclinical unfavorable cardiometabolic profile.

CONCLUSIONS

This study applies proteomics in ICSI-conceived children, providing evidence for an early adverse cardiometabolic profile and supporting the necessity of their long-term monitoring.

Protein-drug nanoconjugates: Finding the alternative proteins as drug carrier

Present study was conducted to establish the interaction of bovine fetuin-A to validate its binding modalities with doxorubicin (Dox). Fetuin-A was purified to highest purity and monodispersity. Green synthesis of fetuin-A conjugated gold nanoparticles (F-GNPs) has been performed giving typical UV-maxima with subtle variation in fourier transform infrared spectroscopy (FTIR). Atomic force microscopy (AFM) revealed spherical shaped, polydisperse F-GNPs of varying sizes, complementing the radius of hydration (19.5-62.4nm) by dynamic light scattering (DLS). Circular dichroism (CD) analysis of fetuin-A with respect to Dox interaction shows remarkable reduction in ellipticity with increasing concentrations of Dox (20-120μM). Fetuin-A:Dox and F-GNPs:Dox at variable concentrations revealed significantly enhanced absorption spectra, while a continuous decrease in florescence (560nm). This effect was more drastic when Dox interact with fetuin-A as compared to F-GNPs. Some known antimicrobial drugs were also investigated under similar conditions, giving strong quenching effect in a dose dependent manner suggesting the significant yet differential interactions. In cytotoxicity assay, fetuin-A:Dox conjugates revealed less toxicity as compared to F-GNPs:Dox and Dox alone. In-silico studies of the fetuin-A:Dox complex suggest that the drug binds in the major grove between beta-sheet and long loop region of D1 domain and stabilized by several hydrogen bonds.

Sialylated Fetuin-A as a candidate predictive biomarker for successful grass pollen allergen immunotherapy

BACKGROUND

Eligibility to immunotherapy is based on the determination of IgE reactivity to a specific allergen by means of skin prick or in vitro testing. Biomarkers predicting the likelihood of clinical improvement during immunotherapy would significantly improve patient selection.

METHODS

Proteins were differentially assessed by using 2-dimensional differential gel electrophoresis and label-free mass spectrometry in pretreatment sera obtained from clinical responders and nonresponders within a cohort of 82 patients with grass pollen allergy receiving sublingual immunotherapy or placebo. Functional studies of Fetuin-A (FetA) were conducted by using gene silencing in a mouse asthma model, human dendritic cell in vitro stimulation assays, and surface plasmon resonance.

RESULTS

Analysis by using quantitative proteomics of pretreatment sera from patients with grass pollen allergy reveals that high levels of O-glycosylated sialylated FetA isoforms are found in patients exhibiting a strong decrease in rhinoconjunctivitis symptoms after sublingual immunotherapy. Although FetA is involved in numerous inflammatory conditions, its potential role in allergy is unknown. In vivo silencing of the FETUA gene in BALB/c mice results in a dramatic upregulation of airway hyperresponsiveness, lung resistance, and T_H2 responses after allergic sensitization to ovalbumin. Both sialylated and nonsialytated FetA bind to LPS, but only the former synergizes with LPS and grass pollen or mite allergens to enhance the Toll-like receptor 4-mediated proallergic properties of human dendritic cells.

CONCLUSIONS

As a reflection of the patient's inflammatory status, pretreatment levels of sialylated FetA in the blood are indicative of the likelihood of clinical responses during grass pollen immunotherapy.

The diagnostic value of serum fucosylated fetuin A in hepatitis B virus-related liver diseases

BACKGROUND

Some changes of glycoproteins have been identified in the serum of patients with different liver diseases, which provided potential glycan biomarkers for diagnosis, prognosis and monitoring of disease progression.

METHODS

We established a lectin-antibody sandwich ELISA method to detect fucosylated fetuin A (fuc-fetuin A) level in serum, in which biotinylated Aleuria aurantia lectin (AAL) was used for specific recognition. Then serum fuc-fetuin A level was detected in 108 healthy controls and 548 hepatitis B virus (HBV)-infected patients, including 232 hepatocellular carcinoma (HCC) patients, 114 liver cirrhosis (LC) patients, 86 liver fibrosis (LF) patients, and 116 asymptomatic HBV carriers, to assess its diagnostic and prognostic value in HBV-related liver diseases.

RESULTS

Serum fetuin A level decreased in LC patients as compared to HCC patients or healthy controls, while it decreased further according to the increasing Child-Pugh grades. The fuc-fetuin A level was in a decreasing order in LC, HCC, LF, HBV-carriers and healthy controls. For distinguishing LC and HCC patients from LF, HBV-carriers and healthy controls, the area under the receiver operating characteristic (ROC) curve is 0.871, with a sensitivity of 0.818 and specificity of 0.819. The survival analysis revealed that higher fuc-fetuin A level was significantly associated with worse recurrence-free survival in HCC patients (p=0.018).

CONCLUSIONS

The results indicated that the serum fuc-fetuin A might serve as a potential glycan biomarker for distinguishing LC and HCC from LF, HBV-carriers and healthy controls. Furthermore, the preoperative fuc-fetuin A level could be a useful prognostic biomarker for HCC patients.

Preeclampsia transforms membrane N-glycome in human placenta

Posttranslational modifications (PTM) which accompany pathological conditions affect protein structure, characteristics and modulate its activity. Glycosylation is one of the most frequent PTM influencing protein folding, localisation and function. Hypertension is a common gestational complication, which can lead to foetal growth restriction (IUGR) and even to foetal or maternal death. In this work we focused on the impact of preeclampsia complicated with IUGR on placental membrane N-glycome. Results have shown that preeclampsia reduced fucosylation of placental glycans, increased the appearance of paucimannosidic and mannosidic structures with lower number of mannose residues and decreased the amount of glycans with more mannose residues. Since preeclampsia is tightly connected to IUGR, glycosylation changes were investigated also on the functional membrane receptors responsible for growth: insulin receptor and the type 1 insulin-like growth factor receptor (IR and IGF1R). It was found that IR present in the IUGR placenta contained significantly less α2,6-Sia. Therefore, glycans on placental membranes alter due to preeclampsia, but changes seen at the level of the entire N-glycome may be different from the changes detected at the level of a specific glycoprotein. The difference recorded due to pathology in one membrane molecule (IR) was not found in another homologous molecule (IGF1R). Thus, besides studying the glycosylation pattern of the entire placental membrane due to preeclampsia, it is inevitable to study directly glycoprotein of interest, as no general assumptions or extrapolations can be made.

Utility of proteomics in obstetric disorders: a review

The study of proteomics could explain many aspects of obstetric disorders. We undertook this review with the aim of assessing the utility of proteomics in the specialty of obstetrics. We searched the electronic databases of MEDLINE, EBSCOhost, BVS Bireme, and SciELO, using various search terms with the assistance of a librarian. We considered cohort studies, case-control studies, case series, and systematic review articles published until October 2014 in the English or Spanish language, and evaluated their quality and the internal validity of the evidence provided. Two reviewers extracted the data independently, then both researchers simultaneously revised the data later, to arrive at a consensus. The search retrieved 1,158 papers, of which 965 were excluded for being duplicates, not relevant, or unrelated studies. A further 86 papers were excluded for being guidelines, protocols, or case reports, along with another 64 that did not contain relevant information, leaving 43 studies for inclusion. Many of these studies showed the utility of proteomic techniques for prediction, pathophysiology, diagnosis, management, monitoring, and prognosis of pre-eclampsia, perinatal infection, premature rupture of membranes, preterm birth, intrauterine growth restriction, and ectopic pregnancy. Proteomic techniques have enormous clinical significance and constitute an invaluable weapon in the management of obstetric disorders that increase maternal and perinatal morbidity and mortality.

HSP70, Peroxiredoxin-3 and -6 are upregulated during renal warm ischaemia in a donation after circulatory death model

BACKGROUND

The use of donation after circulatory death (DCD) kidneys for transplantation is increasing. Subsequent delayed graft function is related to ischaemia/reperfusion injury (I/R), warm ischaemia (WI) being one of the main contributing factors. This proteomics study aimed to identify candidate biomarkers of WI.

METHODS

Termination biopsies were obtained over 180min in 6 pigs. Proteins were subjected to differential in-gel electrophoresis (DIGE) and identified using LC MS/MS.

RESULTS

Thirty nine protein spots showed significant changes in expression (ANOVA, p<0.05). Peroxiredoxin-3 and -6 (PRX3 and PRX6) were expressed with a fold change (FD) of +1.8 (p=0.03 and 0.02 respectively). A significant upregulation of Alpha-2-HS-glycoprotein (A2HSG, FD+1.9, p=0.047) and heat-shock protein 70-1b (HSP70-1b, FD+2.1 p=0.002) was recorded.

CONCLUSIONS

The expression of PRX3, PRX6 and HSP70-1b during the first 30min of WI may be critical in measuring cellular responses. This is the first large animal model to describe the novel candidate biomarker, structural protein A2HSG. A2HSG upregulation during WI alone in this study is encouraging and further assessment in a DCD auto-transplant model is warranted.

BIOLOGICAL SIGNIFICANCE

Warm ischaemia (WI) during donation after circulatory death (DCD) organ retrieval is associated with higher rates of post transplant organ dysfunction. The cellular and molecular mechanism of this paradigm is poorly reported. The work carried out in this large animal study has been performed to enable better understanding of protein expression during DCD WI at the time of retrieval. We have identified differential increased expression of PRX3, PRX6 and HSP70 during the first 30min of WI. Observation of this behaviour has not been reported before. Application of these results in a reperfusion model or autograft animal study would further help study of the named proteins as clinical biomarkers of WI. Alpha 2-HS Glycoprotein (A2HSG) species were also differentially expressed during the WI period. This remains a novel finding. Assessment of A2HSG is also recommended for further study in a reperfusion context. Previous reports of A2HSG have suggested an association in chronic kidney disease and diabetes, but no association with WI has previously been noted in either small or large animals.

Low abundance plasma proteins in labour

Every year, millions of births worldwide are complicated by prematurity or difficult post-term deliveries, resulting in a high incidence of perinatal mortality and morbidity. Our poor understanding of human parturition is a key reason for our inability to improve the management of preterm and post-term birth. In this study, we used proteomic techniques to look into protein changes in placental blood plasma obtained from women before or after spontaneous or induced labour, with vaginal or caesarean section deliveries. Our aim was to understand the basic mechanisms of human parturition regardless of whether the signals that trigger labour are of maternal and/or fetal origin. We found proteins from 33 genes with significantly altered expression profiles in relation to mode of labour and delivery. Most changes in labour occurred in proteins associated with ‘immune and defence responses’. Although the signal transduction and regulation of these pathways varied among modes of delivery, hepatocyte nuclear factor 1 homeobox A emerged as a shared protein in the mechanism of labour. Moreover, several apolipoproteins such as apolipoprotein A-IV and APOE were found to change with labour, and these changes were also confirmed in maternal plasma. This study has identified significant protein changes in placental intervillous plasma with labour and has revealed several pathways related to human parturition.

Prioritization of biomarker targets in human umbilical cord blood: identification of proteins in infant blood serving as validated biomarkers in adults

BACKGROUND

Early diagnosis represents one of the best lines of defense in the fight against a wide array of human diseases. Umbilical cord blood (UCB) is one of the first easily available diagnostic biofluids and can inform about the health status of newborns. However, compared with adult blood, its diagnostic potential remains largely untapped.

OBJECTIVES

Our goal was to accelerate biomarker research on UCB by exploring its detectable protein content and providing a priority list of potential biomarkers based on known proteins involved in disease pathways.

METHODS

We explored cord blood serum proteins by profiling a UCB pool of 12 neonates with different backgrounds using a combination of isoelectric focusing and liquid chromatography coupled with matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-MS/MS) and by comparing results with information contained in metabolic and disease databases available for adult blood.

RESULTS

A total of 1,210 UCB proteins were identified with a protein-level false discovery rate of ~ 5% as estimated by naïve target-decoy and MAYU approaches, signifying a 6-fold increase in the number of UCB proteins described to date. Identified proteins correspond to 138 different metabolic and disease pathways and provide a platform of mechanistically linked biomarker candidates for tracking disruptions in cellular processes. Moreover, among the identified proteins, 38 were found to be approved biomarkers for adult blood.

CONCLUSIONS

The results of this study advance current knowledge of the human cord blood serum proteome. They showcase the potential of UCB as a diagnostic medium for assessing infant health by detection and identification of candidate biomarkers for known disease pathways using a global, nontargeted approach. These biomarkers may inform about mechanisms of exposure-disease relationships. Furthermore, biomarkers approved by the U.S. Food and Drug Administration for screening in adult blood were detected in UCB and represent high-priority targets for immediate validation.

Microfluidic digital isoelectric fractionation for rapid multidimensional glycoprotein analysis

Here we present an integrated microfluidic device for rapid and automated isolation and quantification of glycoprotein biomarkers directly from biological samples on a multidimensional analysis platform. In the first dimension, digital isoelectric fractionation (dIEF) uses discrete pH-specific membranes to separate proteins and their isoforms into precise bins in a highly flexible spatial arrangement on-chip. dIEF provides high sample preconcentration factors followed by immediate high-fidelity transfer of fractions for downstream analysis. We successfully fractionate isoforms of two potential glycoprotein cancer markers, fetuin and prostate-specific antigen (PSA), with 10 min run time, and results are compared qualitatively and quantitatively to conventional slab gel IEF. In the second dimension, functionalized monolithic columns are used to capture and detect targeted analytes from each fraction. We demonstrate rapid two-dimensional fractionation, immunocapture, and detection of C-reactive protein (CRP) spiked in human serum. This rapid, flexible, and automated approach is well-suited for glycoprotein biomarker research and verification studies and represents a practical avenue for glycoprotein isoform-based diagnostic testing.

Plasma clusterin increased prior to small for gestational age (SGA) associated with preeclampsia and decreased prior to SGA in normotensive pregnancies

In our search for early biomarkers for the pregnancy complicationssmall for gestational age (SGA) and preeclampsia (PE) we analysed plasma from 19-21 weeks gestation in women recruited into the SCOPE study, a prospective cohort of nulliparous women, by differential in gel electrophoresis (DIGE). DIGE revealed the differential expression of clusterin levels and its isoforms in top6-depleted plasma of women who delivered an SGA infant but remained normotensive (SGA-NT; N = 8) compared to healthy women with an uncomplicated pregnancy outcome (Controls, N = 8). Immunosorbent enzyme-linked assay (ELISA) showed that compared to plasma clusterin levels from healthy controls [71.1 (SD 12.4) µg/mL, n = 39], clusterin was decreased in SGA-NT [58.3 (SD 11.7), N = 20, P < 0.0001], increased in women with SGA and PE [81.5 (SD 14.8), N = 20, P < 0.01], but similar in PE alone [71.2 (SD 9.4)g/ml, P = 1.0]. Screening for clusterin levels and/or its different isoformsmay be useful in mid-pregnancy to identify women who subsequently develop SGA but remain normotensive or who develop preeclampsia with SGA.

Fetuin A concentration in the second trimester amniotic fluid of fetuses with trisomy 21 appears to be lower: phenotypic considerations

OBJECTIVE

We investigated whether the concentration of the glycoprotein fetuin A is altered in the second trimester amniotic fluid of trisomy 21 pregnancies compared with euploid pregnancies.

METHODS

25 pregnancies with an extra chromosome 21 were matched for maternal and gestational age with 25 pregnancies with normal karyotype. Levels of fetuin A in amniotic fluid were measured by a commercially available enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

The median concentration of fetuin A in amniotic fluid of trisomy 21 pregnancies (5.3 ng/ml) was statistically significantly lower (P value = 0.008) compared with that in euploid pregnancies (6.8 ng/mL).

CONCLUSION

Lower levels of fetuin A in trisomy 21 may indicate an association with altered metabolic pathways in this early stage that could potentially be associated with features of the syndrome, such as growth restriction or impaired osteogenesis.

Plasma proteomic analysis in obese and overweight prepubertal children

BACKGROUND

Childhood obesity represents one of the most challenging health problems of our century and is associated with significant morbidity and mortality in adult life. Proteomics is a large-scale analysis of proteins, which provides, information on protein expression levels, post-translational modifications, subcellular localization and interactions.

OBJECTIVE

To investigate whether obesity in childhood is associated with alterations in plasma protein expression profiles.

METHODS

Plasma samples from 10 obese [age: 10·75 ± 0·16 year; body mass index (BMI): 27·50 ± 0·69 kg m(-2) ], 10 overweight (age: 10·54 ± 0·1 year; BMI: 21·88 ± 0·28 kg m(-2) ) and 10 normal-weight (age: 10·89 ± 0·19 year; BMI: 18·34 ± 0·42kg m(-2) ) prepubertal boys were subjected to protein fractionation and analysed by two-dimensional electrophoresis, followed by protein identification using matrix-assisted laser desorption time-of-flight mass spectrometry. Fasting plasma glucose and serum insulin, lipid and apolipopoprotein concentrations were determined in all subjects.

RESULTS

The expression of apolipoprotein (Apo) A-I (ApoA-I) was significantly lower in obese and overweight children compared with children of normal BMI (P < 0·05). The expression of ApoE was significantly lower in overweight compared with normal-weight children (P < 0·05), while that of ApoA-IV was significantly higher in obese children compared with their normal counterparts (P < 0·01). Serum ApoA-I concentrations were significantly lower in obese (147 ± 4·27mg dL(-1) ) and overweight (145·5 ± 9·65mg dL(-1) ) than in normal-weight (157 ± 8·77mg dL(-1) ; P = 0·036) children.

CONCLUSIONS

Obese and overweight prepubertal children demonstrated prominent alterations in the expression of plasma apolipoproteins compared with their normal counterparts. Low ApoA-I plasma expression levels and serum concentrations in obesity might be present in childhood before any significant alterations in total or high-density lipoprotein-cholesterol concentrations are documented. We recommend that serum ApoA-I concentrations are determined in all overweight and obese children.

Mass spectrometry of peptides and proteins from human blood

It is difficult to convey the accelerating rate and growing importance of mass spectrometry applications to human blood proteins and peptides. Mass spectrometry can rapidly detect and identify the ionizable peptides from the proteins in a simple mixture and reveal many of their post-translational modifications. However, blood is a complex mixture that may contain many proteins first expressed in cells and tissues. The complete analysis of blood proteins is a daunting task that will rely on a wide range of disciplines from physics, chemistry, biochemistry, genetics, electromagnetic instrumentation, mathematics and computation. Therefore the comprehensive discovery and analysis of blood proteins will rank among the great technical challenges and require the cumulative sum of many of mankind's scientific achievements together. A variety of methods have been used to fractionate, analyze and identify proteins from blood, each yielding a small piece of the whole and throwing the great size of the task into sharp relief. The approaches attempted to date clearly indicate that enumerating the proteins and peptides of blood can be accomplished. There is no doubt that the mass spectrometry of blood will be crucial to the discovery and analysis of proteins, enzyme activities, and post-translational processes that underlay the mechanisms of disease. At present both discovery and quantification of proteins from blood are commonly reaching sensitivities of ∼1 ng/mL.

The physiologic development of fetuin-a serum concentrations in children

Fetuin-A prevents tissue calcification by forming soluble complexes with calcium and phosphate. A pathological depletion of serum fetuin-A has been observed in children on dialysis or after renal transplantation but knowledge on physiologic age-related changes in serum fetuin-A is limited. We prospectively evaluated serum fetuin-A in 133 infants and children, ranging from very low birth weight infants to adolescents. Highest serum fetuin-A levels were present between 23 and 30 wk of gestation (1 +/- 0.33 mg/mL). Thereafter, the values decreased. This decrease was linked to biological rather than chronological age. At 32 to 36 and 37 to 40 wk of gestation, the serum fetuin-A concentration was 0.63 +/- 0.26 and 0.63 +/- 0.21 mg/mL, respectively. Thereafter, the concentrations remained stable until adolescence at 0.58 +/- 0.12 mg/mL. Intercurrent infections were associated with a transient decrease of serum fetuin-A levels. The high serum fetuin-A concentrations in preterm children suggest that fetuin-A is of high physiologic impact for the fetal and the preterm-born organism, showing extensive tissue formation. This might point to a new mechanism contributing to organ damage in these patients, comparable with children on dialysis.

The proteomic analysis of human neonatal umbilical cord serum by mass spectrometry

AIM

To investigate the proteome composition and function of human neonatal arterial umbilical cord.

METHODS

Serum proteomic analyses were performed on samples from both males and females by using a combination of techniques: (1) removal of six high-abundance proteins, (2) tryptic digestion of low-abundance proteins, (3) separation of peptide mixtures by reverse-phase high-performance liquid chromatography (RP-HPLC), and (4) peptide identification using electrospray ionization tandem mass spectrometry (ESI-MS/MS).

RESULTS

A total of 837 non-redundant proteins were identified, with 213 male-specific and 239 female-specific proteins. Among them, 319 proteins were identified by at least 2 distinct peptides. The subcellular localization, function, and pathway involvement for each of the identified proteins were analyzed. A comparison of this neonatal proteome to that of adult serum proteome revealed novel biomarkers, such as alpha-fetoprotein and periostin that were specific to newborn infants.

CONCLUSION

These data will contribute to a better understanding of the composition of umbilical cord serum and aid the discovery of novel biomarkers for the prenatal diagnosis of fetal abnormalities.