Abnormal serum concentrations of proteins in Parkinson's disease

Peripheral Upregulation of Parkinson's Disease-Associated Genes Encoding α-Synuclein, β-Glucocerebrosidase, and Ceramide Glucosyltransferase in Major Depression

Due to the high comorbidity of Parkinson's disease (PD) with major depressive disorder (MDD) and the involvement of sphingolipids in both conditions, we investigated the peripheral expression levels of three primarily PD-associated genes: α-synuclein (SNCA), lysosomal enzyme β-glucocerebrosidase (GBA1), and UDP-glucose ceramide glucosyltransferase (UGCG) in a sex-balanced MDD cohort. Normalized gene expression was determined by quantitative PCR in patients suffering from MDD (unmedicated n = 63, medicated n = 66) and controls (remitted MDD n = 39, healthy subjects n = 61). We observed that expression levels of SNCA (p = 0.036), GBA1 (p = 0.014), and UGCG (p = 0.0002) were higher in currently depressed patients compared to controls and remitted patients, and expression of GBA1 and UGCG decreased in medicated patients during three weeks of therapy. Additionally, in subgroups, expression was positively correlated with the severity of depression and anxiety. Furthermore, we identified correlations between the gene expression levels and PD-related laboratory parameters. Our findings suggest that SNCA, GBA1, and UGCG analysis could be instrumental in the search for biomarkers of MDD and in understanding the overlapping pathological mechanisms underlying neuro-psychiatric diseases.

An update on new-age potential biomarkers for Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder that deals with dopaminergic deficiency in Substantia nigra pars compact (SNpc) region of the brain. Dopaminergic deficiency manifests into motor dysfunction. Alpha-synuclein protein aggregation is the source for inception of the pathology. Motor symptoms include rigidity, akinesia, tremor and gait dysfunction. Pre-motor symptoms are also seen in early stage of the disease; however, they are not distinguishable. Lack of early diagnosis in PD pathology poses a major challenge for development of disease modifying therapeutics. Substantial neuronal loss has already been occurred before the clinical manifestations appear and hence, it becomes impossible to halt the disease progression. Current diagnostics are majorly based on the clinical symptoms and thus fail to detect early progression of the disease. Thus, there is need for early diagnosis of PD, for detection of the disease at its inception. This will facilitate the effective use of therapies that halt the progression and will make remission possible. Many novel biomarkers are being developed that include blood-based biomarker, CSF biomarker. Other than that, there are non-invasive techniques that can detect biomarkers. We aim to discuss potential role of these new age biomarkers and their association with PD pathogenesis in this review.

Plasma proteome profiling using tandem mass tag labeling technology reveals potential biomarkers for Parkinson's disease: a preliminary study

PURPOSE

Parkinson's disease (PD) is the second most frequently occurring progressive neurodegenerative disorder. Biomarkers are useful indicators for tracking disease progression, early diagnosis, and intervention of disease progression. We aimed to develop plasma biomarker panel which maybe aid to predict the onset and progression of PD.

EXPERIMENTAL DESIGN

Tandem mass tag (TMT) mass spectrometry was applied using an Orbitrap Lumos mass spectrometer to analyze plasma protein expression in patients diagnosed with PD and healthy controls.

RESULTS

In total, 555 proteins were quantified. Using a cut-off of p < 0.05 and a fold change of >1.2 for the variation in expression, 25 proteins were differentially expressed between the PD and control groups. Sixteen proteins were upregulated and nine were downregulated. Several proteins, including Chitinase-3-like protein 1 (CHI3L1) and thymosin beta-4 (TMSB4X) were implicated in PD pathogenesis.

CONCLUSIONS

The data from the TMT-based proteomic profiling of plasma samples in PD may help advance the understanding of the molecular mechanisms of PD and identify potential novel biomarkers of PD for further characterization.

Proteomics in Human Parkinson's Disease: Present Scenario and Future Directions

Parkinson's disease (PD) is an age-related, threatening neurodegenerative disorder with no reliable treatment till date. Identification of specific and reliable biomarker is a major challenge for disease diagnosis and designing effective therapeutic strategy against it. PD pathology at molecular level involves abnormal expression and function of several proteins, including alpha-synuclein. These proteins affect the normal functioning of neurons through various post-translational modifications and interaction with other cellular components. The role of protein anomalies during PD pathogenesis can be better understood by the application of proteomics approach. A number of proteomic studies conducted on brain tissue, blood, and cerebrospinal fluid of PD patients have identified a wide array of protein alterations underlying disease pathogenesis. However, these studies are limited by the types of brain regions or biofluids utilized in the research. For a complete understanding of PD mechanism and discovery of reliable protein biomarkers, it is essential to analyze the proteome of different PD-associated brain regions and easily accessible biofluids such as saliva and urine. The present review summarizes the major advances in the field of PD research in humans utilizing proteomic techniques. Moreover, potential samples for proteomic analysis and limitations associated with the analyses of different types of samples have also been discussed.

Diagnostic validity of biomarkers in Parkinson's Disease: systematic review and meta-analysis

OBJECTIVE

To identify biomarkers for Parkinson's disease, cerebrospinal fluid, blood, saliva, and urine.

METHOD

The studies were collected from the Cochrane, LILACS, PubMed, SCOPUS, WEB OF SCIENCE, OpenGrey, ProQuest and Google Scholar databases starting from May 3, 2016 and updated on March 20, 2017. Twenty-two studies were evaluated, by the Quality Assessment Tool for Diagnostic Accuracy Studies and Review Manager 5.3.

RESULTS

Evidence shows that serum antibodies can be used as highly specific and accurate biomarkers for the diagnosis of Parkinson's disease at the outset. Biomarkers in the cerebrospinal fluid are related to increased motor severity, postural instability, gait abnormality, and cognitive impairment.

CONCLUSION

Serum and cerebrospinal antibodies can be used as diagnostic biomarkers at the onset of the disease.

Neuroprotective and Therapeutic Strategies against Parkinson's Disease: Recent Perspectives

Parkinsonism is a progressive motor disease that affects 1.5 million Americans and is the second most common neurodegenerative disease after Alzheimer’s. Typical neuropathological features of Parkinson’s disease (PD) include degeneration of dopaminergic neurons located in the pars compacta of the substantia nigra that project to the striatum (nigro-striatal pathway) and depositions of cytoplasmic fibrillary inclusions (Lewy bodies) which contain ubiquitin and α-synuclein. The cardinal motor signs of PD are tremors, rigidity, slow movement (bradykinesia), poor balance, and difficulty in walking (Parkinsonian gait). In addition to motor symptoms, non-motor symptoms that include autonomic and psychiatric as well as cognitive impairments are pressing issues that need to be addressed. Several different mechanisms play an important role in generation of Lewy bodies; endoplasmic reticulum (ER) stress induced unfolded proteins, neuroinflammation and eventual loss of dopaminergic neurons in the substantia nigra of mid brain in PD. Moreover, these diverse processes that result in PD make modeling of the disease and evaluation of therapeutics against this devastating disease difficult. Here, we will discuss diverse mechanisms that are involved in PD, neuroprotective and therapeutic strategies currently in clinical trial or in preclinical stages, and impart views about strategies that are promising to mitigate PD pathology.

Protein biomarkers in Parkinson's disease: Focus on cerebrospinal fluid markers and synaptic proteins

Despite extensive research, to date, no validated biomarkers for PD have been found. This review seeks to summarize studies approaching the detection of biomarker candidates for PD and introduce promising ones in more detail, with special attention to synaptic proteins. To this end, we performed a PubMed search and included studies using proteomic tools (2-dimensional difference in gel electrophoresis and/or mass spectrometry) for the comparison of samples from PD and control patients. We found 27 studies reporting more than 500 differentially expressed proteins in which a total of 28 were detected in 2 and 17 in 3 or more independent studies, including posttranslationally modified proteins. In addition, of these 500 proteins, 25 were found to be brain specific, and 14 were enriched in synapses. Special attention was given to the applicability of the biomarker regarding sampling procedures, that is, using CSF/serum material for diagnosis. Furthermore, presynaptic proteins involved in vesicle membrane fusion seem to be interesting candidates for future analyses. Nonetheless, even though such promising biomarker candidates for PD exist, validation of these biomarkers in large-scale clinical studies is necessary to evaluate the diagnostic potential. © 2016 International Parkinson and Movement Disorder Society.

Longitudinal Protein Changes in Blood Plasma Associated with the Rate of Cognitive Decline in Alzheimer's Disease

Biomarkers of Alzheimer's disease (AD) progression are needed to support the development of urgently needed disease modifying drugs. We employed a SOMAscan assay for quantifying 1,001 proteins in blood samples from 90 AD subjects, 37 stable mild cognitive impaired (MCI) subjects, 39 MCI subjects converting to AD within a year and 69 controls at baseline and one year follow up. We used linear mixed effects models to identify proteins changing significantly over one year with the rate of cognitive decline, which was quantified as the reduction in Mini Mental State Examination (MMSE) scores. Additionally, we investigated proteins changing differently across disease groups and during the conversion from MCI to AD. We found that levels of proteins belonging to the complement cascade increase significantly in fast declining AD patients. Longitudinal changes in the complement cascade might be a surrogate biomarker for disease progression. We also found that members of the cytokine-cytokine receptor interaction pathway change during AD when compared to healthy aging subjects.

Specific changes of serum proteins in Parkinson's disease patients

The aim of this study is to identify and validate protein change in the serum from PD patients. We used serum samples from 21 PD patients and 20 age-matched normal people as control to conduct a comparative proteomic study. We performed 2-DE and analyzed the differentially expressed protein spots by LC-MS/MS. In PD group 13 spots were shown to be differentially expressed compared to control group. They were identified as 6 proteins. Among these, 3 proteins were confirmed by Western blot analysis. It showed that the frequency of fibrinogen γ-chain (FGG) appeared 70% in PD, which could not be detected in control group. The protein of inter-alpha-trypsin inhibitor heavy chain H4 (ITI-H4) was found to exist two forms in serum. The full size (120 kDa) of the protein was increased and the fragmented ITI-H4 (35 kDa) was decreased in PD group. The ratio of full size ITI-H4 to fragmented ITI-H4 in PD patients was 3.85±0.29-fold higher than in control group. Furthermore, fragmented Apo A-IV (∼26 kDa) was mainly detected in control group, while it was rare to be found in PD group. Above findings might be useful for diagnosis of PD. When the expressions of FGG and 120 kDa ITI-H4 are increase, as well as ∼26 kDa Apo A-IV disappear would provide strong evidence for PD.

Diagnostic markers for Parkinson's disease

PURPOSE OF REVIEW

This review enumerates recent developments in the early diagnosis of Parkinson's disease, with an emphasis on detection of preclinical Parkinson's disease.

RECENT FINDINGS

Several clinical, laboratory, and imaging tests are now being investigated as potential early markers of Parkinson's disease. These include various nonmotor features that predate the motor manifestations of Parkinson's disease, including sleep abnormalities, neurobehavioral symptoms, and olfactory dysfunction. Tests of the autonomic nervous system, such as cardiac functional imaging, allow for a measure of cardiac sympathetic denervation. Cerebrospinal fluid and serum tests, including α-synuclein and DJ-1, are being developed and refined. Various imaging modalities have contributed to the diagnostic armamentarium in Parkinson's disease, including transcranial Doppler ultrasonography, radiolabeled tracer imaging, and magnetic resonance imaging. Early Parkinson's disease detection will pave the way for major advances in disease modifying therapies.

SUMMARY

Various diagnostic modalities hold promise for the early and preclinical diagnosis of Parkinson's disease. It is likely that the future diagnosis of Parkinson's disease will rely on a combination of clinical, laboratory, imaging, and genetic data.

Brainstem deficiency of the 14-3-3 regulator of serotonin synthesis: a proteomics analysis in the sudden infant death syndrome

Impaired brainstem responses to homeostatic challenges during sleep may result in the sudden infant death syndrome (SIDS). Previously we reported a deficiency of serotonin (5-HT) and its key biosynthetic enzyme, tryptophan hydroxylase (TPH2), in SIDS infants in the medullary 5-HT system that modulates homeostatic responses during sleep. Yet, the underlying basis of the TPH2 and 5-HT deficiency is unknown. In this study, we tested the hypothesis that proteomics would uncover previously unrecognized abnormal levels of proteins related to TPH2 and 5-HT regulation in SIDS cases compared with controls, which could provide novel insight into the basis of their deficiency. We first performed a discovery proteomic analysis of the gigantocellularis of the medullary 5-HT system in the same data set with deficiencies of TPH2 and 5-HT levels. Analysis in 6 SIDS cases and 4 controls revealed a 42-75% reduction in abundance in 5 of the 6 isoforms identified of the 14-3-3 signal transduction family, which is known to influence TPH2 activity (p < 0.07). These findings were corroborated in an additional SIDS and control sample using an orthogonal MS(E)-based quantitative proteomic strategy. To confirm these proteomics results in a larger data set (38 SIDS, 11 controls), we applied Western blot analysis in the gigantocellularis and found that 4/7 14-3-3 isoforms identified were significantly reduced in SIDS cases (p ≤ 0.02), with a 43% reduction in all 14-3-3 isoforms combined (p < 0.001). Abnormalities in 5-HT and TPH2 levels and 5-HT(1A) receptor binding were associated with the 14-3-3 deficits in the same SIDS cases. These data suggest a potential molecular defect in SIDS related to TPH2 regulation, as 14-3-3 is critical in this process.

Blood-based protein biomarkers for diagnosis and classification of neurodegenerative diseases: current progress and clinical potential

Biomarker research is a rapidly advancing field in medicine. Recent advances in genomic, genetic, epigenetic, neuroscientific, proteomic, and metabolomic knowledge and technologies have opened the way to thriving research. In the most general sense, a biomarker refers to any useful characteristic that can be measured and used as an indicator of a normal biologic process, a pathogenic process, or a pharmacologic response to a therapeutic agent. Despite the extensive resources concentrated on this area, there are very few biomarkers currently available that qualify and are satisfactorily validated for mental disorders, and there is still a major lack of biomarkers for typifying neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. This article provides an overview of this field of research and focuses on recent advances in biomarker research in Alzheimer's disease and Parkinson's disease.