Analyses of haptoglobin level in the cerebrospinal fluid and serum of patients with neuromyelitis optica and multiple sclerosis

Evaluation of Apo A IV and Haptoglobin as Potential CSF Markers in Patients with Guillain-Barre´ Syndrome: A Cross-Sectional Study

BACKGROUND

Brain- and blood-derived protein analysis in the cerebro-spinal fluid (CSF) in various studies performed abroad found that some proteins and their isoforms were altered significantly in Guillain-Barre´ syndrome (GBS) patients in comparison to controls. However, data are lacking in India with respect to the blood- or brain-derived proteins in patients of GBS.

OBJECTIVE

This study aimed to identify the role of apolipoprotein A IV (Apo A IV) and haptoglobin as potential protein markers in CSF of patients with GBS in our population.

MATERIALS AND METHODS

The study comprised 28 participants where 12 confirmed cases of GBS and 16 control subjects admitted for non-infectious neurological disorders were recruited after obtaining approval from the Institutional Ethics Committee. CSF glucose, protein, and adenosine deaminase were analyzed using an autoanalyzer. The concentrations of Apo A IV and haptoglobin were estimated with enzyme-linked immuno-sorbent assay (ELISA) kits.

RESULTS

The CSF protein concentrations of cases were higher as compared to controls. The concentrations of haptoglobin and Apo A IV were higher in the confirmed cases of GBS as compared to the control subjects, and this difference was found to be significant. The receiver operating characteristic curve analysis for haptoglobin revealed that the area under the curve (AUC) was 0.867 (95% CI: 0.732-1.001), with a sensitivity of 83.8% and a specificity of 63.3%. The AUC for Apo A IV was 0.883 (95% CI: 0.758-1.009), with a sensitivity of 91.7% and a specificity of 73.3%.

CONCLUSIONS

Haptoglobin along with Apo A IV can emerge as a potential biochemical marker in CSF for the diagnosis of GBS.

Quantitative serum proteome analysis using tandem mass tags in dogs with epilepsy

This study included four groups of dogs (group A: healthy controls, group B: idiopathic epilepsy receiving antiepileptic medication (AEM), group C: idiopathic epilepsy without AEM, group D: structural epilepsy). Comparative quantitative proteomic analysis of serum samples among the groups was the main target of the study. Samples were analyzed by a quantitative Tandem-Mass-Tags approach on the Q-Exactive-Plus Hybrid Quadrupole-Orbitrap mass-spectrometer. Identification and relative quantification were performed in Proteome Discoverer. Data were analyzed using R. Gene ontology terms were analyzed based on Canis lupus familiaris database. Data are available via ProteomeXchange with identifier PXD041129. Eighty-one proteins with different relative adundance were identified in the four groups and 25 were master proteins (p < 0.05). Clusterin (CLU), and apolipoprotein A1 (APOA1) had higher abundance in the three groups of dogs (groups B, C, D) compared to controls. Amine oxidase (AOC3) was higher in abundance in group B compared to groups C and D, and lower in group A. Adiponectin (ADIPOQ) had higher abundance in groups C compared to group A. ADIPOQ and fibronectin (FN1) had higher abundance in group B compared to group C and D. Peroxidase activity assay was used to quantify HP abundance change, validating and correlating with proteomic analysis (r = 0.8796). SIGNIFICANCE: The proteomic analysis of serum samples from epileptic dogs indicated potential markers of epilepsy (CLU), proteins that may contribute to nerve tissue regeneration (APOA1), and contributing factors to epileptogenesis (AOC3). AEM could alter extracellular matrix proteins (FN1). Illness (epilepsy) severity could influence ADIPOQ abundance.

The Haptoglobin Response after Aneurysmal Subarachnoid Haemorrhage

Haptoglobin is the body's first line of defence against the toxicity of extracellular haemoglobin released following a subarachnoid haemorrhage (SAH). We investigated the haptoglobin response after SAH in cerebrospinal fluid (CSF) and serum. Paired CSF and serum samples from 19 controls and 92 SAH patients were assayed as follows: ultra-performance liquid chromatography for CSF haemoglobin and haptoglobin, immunoassay for serum haptoglobin and multiplexed CSF cytokines, and colorimetry for albumin. There was marked CSF haptoglobin deficiency: 99% of extracellular haemoglobin was unbound. The quotients for both CSF/serum albumin (qAlb) and haptoglobin (qHp) were used to compute the CSF haptoglobin index (qHp/qAlb). CSF from SAH patients had a significantly lower haptoglobin index compared to controls, especially in Haptoglobin-1 allele carriers. Serum haptoglobin levels increased after SAH and were correlated with CSF cytokine levels. Haptoglobin variables were not associated with long-term clinical outcomes post-SAH. We conclude that: (1) intrathecal haptoglobin consumption occurs after SAH, more so in haptoglobin-1 allele carriers; (2) serum haptoglobin is upregulated after SAH, in keeping with the liver acute phase response to central inflammation; (3) haptoglobin in the CSF is so low that any variation is too small for this to affect long-term outcomes, emphasising the potential for therapeutic haptoglobin supplementation.

Prospective outcome analysis of multiple sclerosis cases reveals candidate prognostic cerebrospinal fluid markers

BACKGROUND

Predicting the long-term disability outcomes of multiple sclerosis (MS) cases is challenging.

OBJECTIVE

We prospectively analysed our previous MS cohort with initial cerebrospinal fluid (CSF) proteomics data to reveal disability markers after 8.2±2.2 years of follow-up.

METHODS

Patients with regular follow-up visits were assigned into two groups: those with an age-related MS severity (ARMSS) score ≥5 (unfavourable course group, N = 27) and ARMSS score <5 (favourable course group, N = 67). A machine learning-based algorithm was applied to reveal candidate poor prognosis-associated initial CSF proteins, which were measured in an independent MS cohort (verification group, N = 40) by ELISA. Additionally, the correlation of initial clinical and radiological parameters with long-term disability was analysed.

RESULTS

CSF alpha-2-macroglobulin (P = 0.0015), apo-A1 (P = 0.0016), and haptoglobin (P = 0.0003) protein levels, as well as cerebral lesion load (>9 lesions) on magnetic resonance imaging, gait disturbance (P = 0.04), and bladder/bowel symptoms (P = 0.01) were significantly higher in the unfavourable course group than in the favourable course group. Optic nerve involvement evident on initial magnetic resonance imaging (P = 0.002) and optic neuritis (P = 0.01) were more frequent in the favourable course group.

CONCLUSION

The herein identified initial CSF protein levels, in addition to the clinical and radiological parameters at disease onset, have predictive value for long-term disability in MS cases.

Experimental Analysis of Tear Fluid and Its Processing for the Diagnosis of Multiple Sclerosis

A pilot analysis of the tear fluid of patients with multiple sclerosis (MS) collected by glass microcapillary was performed using various experimental methods: liquid chromatography-mass spectrometry, Raman spectroscopy, infrared spectroscopy, and atomic-force microscopy. Infrared spectroscopy found no significant difference between the tear fluid of MS patients and the control spectra; all three significant peaks were located at around the same positions. Raman analysis showed differences between the spectra of the tear fluid of MS patients and the spectra of healthy subjects, which indicated a decrease in tryptophan and phenylalanine content and changes in the relative contributions of the secondary structures of the polypeptide chains of tear proteins. Atomic-force microscopy exhibited a surface fern-shaped dendrite morphology of the tear fluid of patients with MS, with less roughness on both oriented silicon (100) and glass substrates compared to the tear fluid of control subjects. The results of liquid chromatography-mass spectrometry showed downregulation of glycosphingolipid metabolism, sphingolipid metabolism, and lipid metabolism. Proteomic analysis identified upregulated proteins in the tear fluid of patients with MS such as cystatine, phospholipid transfer protein, transcobalamin-1, immunoglobulin lambda variable 1-47, lactoperoxidase, and ferroptosis suppressor protein 1; and downregulated proteins such as haptoglobin, prosaposin, cytoskeletal keratin type I pre-mRNA-processing factor 17, neutrophil gelatinase-associated lipocalin, and phospholipase A2. This study showed that the tear proteome in patients with MS is modified and can reflect inflammation. Tear fluid is not a commonly used biological material in clinico-biochemical laboratories. Experimental proteomics has the potential to become a promising contemporary tool for personalized medicine, and it might be applied in clinical practice by providing a detailed analysis of the tear-fluid proteomic profile of patients with MS.

Analysis of plasma proteins using 2D gels and novel fluorescent probes: in search of blood based biomarkers for Alzheimer's disease

BACKGROUND

The Australian Imaging and Biomarker Lifestyle (AIBL) study of aging is designed to aid the discovery of biomarkers. The current study aimed to discover differentially expressed plasma proteins that could yield a blood-based screening tool for Alzheimer's disease.

METHODS

The concentration of proteins in plasma covers a vast range of 12 orders of magnitude. Therefore, to search for medium to low abundant biomarkers and elucidate mechanisms of AD, we immuno-depleted the most abundant plasma proteins and pre-fractionated the remaining proteins by HPLC, prior to two-dimensional gel electrophoresis. The relative levels of approximately 3400 protein species resolved on the 2D gels were compared using in-gel differential analysis with spectrally resolved fluorescent protein detection dyes (Zdyes™). Here we report on analysis of pooled plasma samples from an initial screen of a sex-matched cohort of 72 probable AD patients and 72 healthy controls from the baseline time point of AIBL.

RESULTS

We report significant changes in variants of apolipoprotein E, haptoglobin, α1 anti-trypsin, inter-α trypsin inhibitor, histidine-rich glycoprotein, and a protein of unknown identity. α1 anti-trypsin and α1 anti-chymotrypsin demonstrated plasma concentrations that were dependent on APOE ε4 allele dose. Our analysis also identified an association with the level of Vitamin D binding protein fragments and complement factor I with sex. We then conducted a preliminary validation study, on unique individual samples compared to the discovery cohort, using a targeted LC-MS/MS assay on a subset of discovered biomarkers. We found that targets that displayed a high degree of isoform specific changes in the 2D gels were not changed in the targeted MS assay which reports on the total level of the biomarker.

CONCLUSIONS

This demonstrates that further development of mass spectrometry assays is needed to capture the isoform complexity that exists in theses biological samples. However, this study indicates that a peripheral protein signature has potential to aid in the characterization of AD.

Identification of blood-based biomarkers for diagnosis and prognosis of Parkinson's disease: A systematic review of proteomics studies

Parkinson's Disease (PD), a neurodegenerative disorder, is characterised by the loss of motor function and dopamine neurons. Therapeutic avenues remain a challenge due to lack of accuracy in early diagnosis, monitoring of disease progression and limited therapeutic options. Proteomic platforms have been utilised to discover biomarkers for numerous diseases, a tool that may benefit the diagnosis and monitoring of disease progression in PD patients. Therefore, this systematic review focuses on analysing blood-based candidate biomarkers (CB) identified via proteomics platforms for PD. This study systematically reviewed articles across six databases (EMBASE, Cochrane, Ovid Medline, Scopus, Science Direct and PubMed) published between 2010 and 2020. Of the 504 articles identified, 12 controlled-PD studies were selected for further analysis. A total of 115 candidate biomarkers (CB) were identified across selected 12-controlled studies, of which 23 CB were found to be replicable in more than two cohorts. Using the PANTHER Go-Slim classification system and STRING network, the gene function and protein interactions between biomarkers were analysed. Our analysis highlights Apolipoprotein A-I (ApoA-I), which is essential in lipid metabolism, oxidative stress, and neuroprotection demonstrates high replicability across five cohorts with consistent downregulation across four cohorts. Since ApoA-I was highly replicable across blood fractions, proteomic platforms and continents, its relationship with cholesterol, statin and oxidative stress as PD biomarker, its role in the pathogenesis of PD is discussed in this paper. The present study identified ApoA-I as a potential biomarker via proteomics analysis of PD for the early diagnosis and prediction of disease progression.

Identifying new molecular players in extracellular proteostasis

Proteostasis refers to a delicately tuned balance between the processes of protein synthesis, folding, localization, and the degradation of proteins found inside and outside cells. Our understanding of extracellular proteostasis is rather limited and largely restricted to knowledge of 11 currently established extracellular chaperones (ECs). This review will briefly outline what is known of the established ECs, before moving on to discuss experimental strategies used to identify new members of this growing family, and an examination of a group of putative new ECs identified using one of these approaches. An observation that emerges from an analysis of the expanding number of ECs is that all of these proteins are multifunctional. Strikingly, the armory of activities each possess uniquely suit them as a group to act together at sites of tissue damage, infection, and inflammation to restore homeostasis. Lastly, we highlight outstanding questions to guide future research in this field.

Multiple Sclerosis Biomarker Discoveries by Proteomics and Metabolomics Approaches

Multiple sclerosis (MS) is an autoimmune inflammatory disorder of the central nervous system (CNS) resulting in demyelination and axonal loss in the brain and spinal cord. The precise pathogenesis and etiology of this complex disease are still a mystery. Despite many studies that have been aimed to identify biomarkers, no protein marker has yet been approved for MS. There is urgently needed for biomarkers, which could clarify pathology, monitor disease progression, response to treatment, and prognosis in MS. Proteomics and metabolomics analysis are powerful tools to identify putative and novel candidate biomarkers. Different human compartments analysis using proteomics, metabolomics, and bioinformatics approaches has generated new information for further clarification of MS pathology, elucidating the mechanisms of the disease, finding new targets, and monitoring treatment response. Overall, omics approaches can develop different therapeutic and diagnostic aspects of complex disorders such as multiple sclerosis, from biomarker discovery to personalized medicine.

Nusinersen Modulates Proteomics Profiles of Cerebrospinal Fluid in Spinal Muscular Atrophy Type 1 Patients

Spinal muscular atrophy (SMA) type 1 is a severe infantile autosomal-recessive neuromuscular disorder caused by a survival motor neuron 1 gene (SMN1) mutation and characterized by progressive muscle weakness. Without supportive care, SMA type 1 is rapidly fatal. The antisense oligonucleotide nusinersen has recently improved the natural course of this disease. Here, we investigated, with a functional proteomic approach, cerebrospinal fluid (CSF) protein profiles from SMA type 1 patients who underwent nusinersen administration to clarify the biochemical response to the treatment and to monitor disease progression based on therapy. Six months after starting treatment (12 mg/5 mL × four doses of loading regimen administered at days 0, 14, 28, and 63), we observed a generalized reversion trend of the CSF protein pattern from our patient cohort to that of control donors. Notably, a marked up-regulation of apolipoprotein A1 and apolipoprotein E and a consistent variation in transthyretin proteoform occurrence were detected. Since these multifunctional proteins are critically active in biomolecular processes aberrant in SMA, i.e., synaptogenesis and neurite growth, neuronal survival and plasticity, inflammation, and oxidative stress control, their nusinersen induced modulation may support SMN improved-expression effects. Hence, these lipoproteins and transthyretin could represent valuable biomarkers to assess patient responsiveness and disease progression.

The Chemical Basis of Intracerebral Hemorrhage and Cell Toxicity With Contributions From Eryptosis and Ferroptosis

Intracerebral hemorrhage (ICH) is a particularly devastating event both because of the direct injury from space-occupying blood to the sequelae of the brain exposed to free blood components from which it is normally protected. Not surprisingly, the usual metabolic and energy pathways are overwhelmed in this situation. In this review article, we detail the complexity of red blood cell degradation, the contribution of eryptosis leading to hemoglobin breakdown into its constituents, the participants in that process, and the points at which injury can be propagated such as elaboration of toxic radicals through the metabolism of the breakdown products. Two prominent products of this breakdown sequence, hemin, and iron, induce a variety of pathologies including free radical damage and DNA breakage, which appear to include events independent from typical oxidative DNA injury. As a result of this confluence of damaging elements, multiple pathways of injury, cell death, and survival are likely engaged including ferroptosis (which may be the same as oxytosis but viewed from a different perspective) and senescence, suggesting that targeting any single cause will likely not be a sufficient strategy to maximally improve outcome. Combination therapies in addition to safe methods to reduce blood burden should be pursued.

Quantitative proteomics of cerebrospinal fluid using tandem mass tags in dogs with recurrent epileptic seizures

This prospective study included four dog groups (group A: healthy dogs, groups B: dogs with idiopathic epilepsy under antiepileptic medication (AEM), C: idiopathic epilepsy dogs without AEM administration, D: dogs with structural epilepsy). The purpose of the study was to compare the proteomic profile among the four groups. Samples were analyzed by a quantitative Tandem Mass Tags approach using a Q-Exactive-Plus mass-spectrometer. Identification and relative quantification were performed using Proteome Discoverer, and data were analyzed using R. Gene ontology terms were analyzed based on Canis lupus familiaris database. Data are available via ProteomeXchange with identifier PXD018893. Eighteen proteins were statistically significant among the four groups (P < 0.05). MMP2 and EFEMP2 appeared down-regulated whereas HP and APO-A1 were up-regulated (groups B, D). CLEC3B and PEBP4 were up-regulated whereas APO-A1 was down-regulated (group C). IGLL1 was down-regulated (groups B, C) and up-regulated (group D). EFEMP2 was the only protein detected among the four groups and PEBP4 was significantly different among the epileptic dogs. Western blot and SPARCL immunoassay were used to quantify HP abundance change, validating proteomic analysis. Both, showed good correlation with HP levels identified through proteomic analysis (r = 0.712 and r = 0.703, respectively). SIGNIFICANCE: The proteomic analysis from CSF of dogs with epileptic seizures could reflect that MMP2, HP and APO-A1 may contribute to a blood-brain barrier disruption through the seizure-induced inflammatory process in the brain. MMP2 change may indicate the activation of protective mechanisms within the brain tissue. Antiepileptic medication could influence several cellular responses and alter the CSF proteome composition.

Metabolomic Profiling in Neuromyelitis Optica Spectrum Disorder Biomarker Discovery

There is no specific test for diagnosing neuromyelitis optica spectrum disorder (NMOSD), a disabling autoimmune disease of the central nervous system. Instead, diagnosis relies on ruling out other related disorders with overlapping clinical symptoms. An urgency for NMOSD biomarker discovery is underscored by adverse responses to treatment following misdiagnosis and poor prognosis following the delayed onset of treatment. Pathogenic autoantibiotics that target the water channel aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) contribute to NMOSD pathology. The importance of early diagnosis between AQP4-Ab⁺ NMOSD, MOG-Ab⁺ NMOSD, AQP4-Ab⁻ MOG-Ab⁻ NMOSD, and related disorders cannot be overemphasized. Here, we provide a comprehensive data collection and analysis of the currently known metabolomic perturbations and related proteomic outcomes of NMOSD. We highlight short chain fatty acids, lipoproteins, amino acids, and lactate as candidate diagnostic biomarkers. Although the application of metabolomic profiling to individual NMOSD patient care shows promise, more research is needed.

Haptoglobin: From hemoglobin scavenging to human health

Haptoglobin (Hp) belongs to the family of acute-phase plasma proteins and represents the most important plasma detoxifier of hemoglobin (Hb). The basic Hp molecule is a tetrameric protein built by two α/β dimers. Each Hp α/β dimer is encoded by a single gene and is synthesized as a single polypeptide. Following post-translational protease-dependent cleavage of the Hp polypeptide, the α and β chains are linked by disulfide bridge(s) to generate the mature Hp protein. As human Hp gene is characterized by two common Hp1 and Hp2 alleles, three major genotypes can result (i.e., Hp1-1, Hp2-1, and Hp2-2). Hp regulates Hb clearance from circulation by the macrophage-specific receptor CD163, thus preventing Hb-mediated severe consequences for health. Indeed, the antioxidant and Hb binding properties of Hp as well as its ability to stimulate cells of the monocyte/macrophage lineage and to modulate the helper T-cell type 1 and type 2 balance significantly associate with a variety of pathogenic disorders (e.g., infectious diseases, diabetes, cardiovascular diseases, and cancer). Alternative functions of the variants Hp1 and Hp2 have been reported, particularly in the susceptibility and protection against infectious (e.g., pulmonary tuberculosis, HIV, and malaria) and non-infectious (e.g., diabetes, cardiovascular diseases and obesity) diseases. Both high and low levels of Hp are indicative of clinical conditions: Hp plasma levels increase during infections, inflammation, and various malignant diseases, and decrease during malnutrition, hemolysis, hepatic disease, allergic reactions, and seizure disorders. Of note, the Hp:Hb complexes display heme-based reactivity; in fact, they bind several ferrous and ferric ligands, including O₂, CO, and NO, and display (pseudo-)enzymatic properties (e.g., NO and peroxynitrite detoxification). Here, genetic, biochemical, biomedical, and biotechnological aspects of Hp are reviewed.

The role of haptoglobin and hemopexin in the prevention of delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage: a review of current literature

Delayed cerebral ischaemia (DCI) after aneurysmal subarachnoid haemorrhage (aSAH) is a major cause of mortality and morbidity. The pathophysiology of DCI after aSAH is thought to involve toxic mediators released from lysis of red blood cells within the subarachnoid space, including free haemoglobin and haem. Haptoglobin and hemopexin are endogenously produced acute phase proteins that are involved in the clearance of these toxic mediators. The aim of this review is to investigate the pathophysiological mechanisms involved in DCI and the role of both endogenous as well as exogenously administered haptoglobin and hemopexin in the prevention of DCI.

Temporal and age-dependent effects of haptoglobin deletion on intracerebral hemorrhage-induced brain damage and neurobehavioral outcomes

Intracerebral hemorrhage (ICH) is a devastating stroke subtype and the presence of extracorpuscular hemoglobin (Hb) exacerbates brain damage. Haptoglobin (Hp) binds Hb, which prevents its oxidation and participation in neurotoxic reactions. Multiple studies have investigated the role of Hp under conditions of intravascular hemolysis, but little is known about its role in the brain and following ICH where extravascular hemolysis is rampant. Young and aged wildtype and Hp^-/- mice underwent the autologous blood or collagenase ICH model. Early after ICH, Hp^-/- mice display 58.0 ± 5.6% and 36.7 ± 6.9% less brain damage in the autologous blood and collagenase ICH models, respectively. In line with these findings, Hp^-/- mice display less neurological deficits on several neurobehavioral tests. Hp^-/- mice have less Perl's iron content, HO1 expression, and blood brain barrier dysfunction, but no difference in brain Hb content, astrogliosis and angiogenesis/neovascularization. At the later endpoint, the young cohort displays 27.8 ± 9.3% less brain damage, while no difference is seen with the aged cohort. For both cohorts, no differences are seen in HO1 levels or iron accumulation, but young Hp^-/- mice display less thalamic astrogliosis and striatal microgliosis. This study reveals that the presence or absence of Hp exerts important time- and age-dependent influences on ICH outcomes.

Proteomic Analysis of Cerebrospinal Fluid: A Search for Biomarkers of Neuropsychiatric Systemic Lupus Erythematosus

Background:

Neuropsychiatric systemic lupus erythematosus or NPSLE, as its name suggests, refers to the neurological and psychiatric manifestations of Systemic Lupus Erythematosus (SLE). In clinical practice, it is often difficult to reach an accurate diagnosis, as this disease presents differently in different patients, and the available diagnostic tests are often not specific enough.

Objectives:

The aim of this study was to search for proteomic biomarkers in cerebrospinal fluid that could be proposed as diagnostic aids for this disease.

Methods:

The proteomic profile of cerebrospinal fluid samples of 19 patients with NPSLE, 12 patients with SLE and no neuropsychiatric manifestation (SLEnoNP), 6 patients with neuropsychiatric symptoms but no SLE (NPnoSLE), 5 with Other Autoimmune Disorders without neuropsychiatric manifestations (OADs), and 4 Healthy Controls (HC), were obtained by two-dimensional gel electrophoresis and compared using ImageMaster Platinum 7.0 software.

Results:

The comparative analysis of the different study groups revealed three proteins of interest that were consistently over-expressed in NPSLE patients. These were identified by mass spectrometry as albumin (spot 16), haptoglobin (spot 160), and beta-2 microglobulin (spot 161).

Conclusion:

This work is one of the few proteomic studies of NPSLE that uses cerebrospinal fluid as the biological sample. Albumin has previously been proposed as a potential biomarker of rheumatoid arthritis and SLE, which is coherent with these results; but this is the first report of haptoglobin and beta-2 microglobulin in NPSLE, although haptoglobin has been associated with increased antibody production and beta-2 microglobulin with lupus nephritis.

Proteomic analysis of age-related changes in ovine cerebrospinal fluid

Cerebrospinal fluid (CSF) circulates through the brain and has a unique composition reflecting the biological processes of the brain. Identifying ageing CSF biomarkers can aid in understanding the ageing process and interpreting CSF protein changes in neurodegenerative diseases. In this study, ovine CSF proteins from young (1-2 year old), middle aged (3-6 year old) and old (7-10 year old) sheep were systemically studied. CSF proteins were labelled with iTRAQ tagging reagents and fractionated by 2-dimensional high performance, liquid chromatography. Tryptic peptides were identified using MS/MS fragmentation ions for sequencing and quantified from iTRAQ reporter ion intensities at m/z 114, 115, 116 and 117. Two hundred thirty one peptides were detected, from which 143 proteins were identified. There were 52 proteins with >25% increase in concentrations in the old sheep compared to the young. 33 of them increased >25% but <50%, 13 increased >50% but <1 fold, 6 increased >1 fold [i.e. haptoglobin (Hp), haemoglobin, neuroendocrine protein 7B2, IgM, fibrous sheath interacting protein 1, vimentin]. There were 18 proteins with >25% decrease in concentrations in the old sheep compared to the young. 17 of them decreased >25% but <50%, and histone deacetylase 7 (HDAC7) was gradually decreased for over 80%. Glutathione S-transferase was decreased in middle aged CSF compared to both young and old CSF. The differential expressions of 3 proteins (Hp, neuroendocrine protein 7B2, IgM) were confirmed by immunoassays. These data expand our current knowledge regarding ovine CSF proteins, supply the necessary information to understand the ageing process in the brain and provide a basis for diagnosis of neurodegenerative diseases.

Gray matter-related proteins are associated with childhood-onset multiple sclerosis

Objective:

To identify CSF biomarkers for multiple sclerosis (MS) in children with an initial acquired CNS demyelinating syndrome (ADS).

Methods:

CSF was collected from a cohort of 39 children with initial ADS, 18 of whom were diagnosed with MS and 21 of whom had a monophasic disease course. Proteomic analysis of trypsinized CSF (20 μL) was performed by nano-liquid chromatography Orbitrap mass spectrometry. Univariate statistical analysis was used to identify differentially abundant proteins between childhood-onset MS and monophasic ADS.

Results:

A total of 2,260 peptides corresponding to 318 proteins were identified in the total set of samples. Of these 2,260 peptides, 88 were identified as being most distinctive between MS and ADS. Fifty-three peptides, corresponding to 14 proteins, had higher abundance in children with MS compared to children with monophasic ADS. Twelve of these 14 proteins were linked to neuronal functions and structures, such as synapses, axons, and CNS proteases (e.g., neurofascin, carboxypeptidase E, brevican core protein, and contactin-2). The other 2 were functionally related to immune function. The 35 peptides identified with decreased abundance in children with MS corresponded to 7 proteins. Six of them were linked to innate immune function (e.g., haptoglobin, haptoglobin-related protein, C4b-binding protein alpha chain, and monocyte differentiation antigen CD14) and 1 was linked to cellular adhesion (protein diaphanous homolog 1).

Conclusion:

At first onset of ADS, CSF of children diagnosed with MS showed increased abundance of CNS gray matter–related proteins, whereas CSF of children with a monophasic disease course showed increased abundance of innate immunity–related proteins.

Body fluid biomarkers for multiple sclerosis--the long road to clinical application

There is a strong unmet clinical need for objective body fluid biomarkers to assist early diagnosis and estimate long-term prognosis, monitor treatment response and predict potential adverse effects in multiple sclerosis (MS). Here, we review recent studies (focusing on 2012 to early 2015) on body fluid markers in MS from the perspective of their clinical utility. Because the first step towards clinical implementation of a newly discovered biomarker is independent replication, we focus on biomarkers that have been validated in at least two independent cohorts. We also discuss recent data challenging earlier findings, and biomarkers for which new clinical uses are suggested. For early MS diagnosis and prediction of conversion from clinically isolated syndrome to MS, several new B-cell-associated candidate blood biomarkers have emerged. For prognosis, several novel axonal damage markers should be adopted to biomarker panels. The number of disease-modifying treatments for MS has increased sharply, but biomarkers for treatment response monitoring and adverse effect prediction are scarce, and markers for subtyping and staging of MS are still lacking. In view of the availability and implementation of several standardized protocols to optimize biomarker studies, we expect biomarker development for MS to be improved and accelerated, with clinical implementation in the near future.

Acute Phase Proteins in Cerebrospinal Fluid from Dogs with Naturally-Occurring Spinal Cord Injury

Spinal cord injury (SCI) affects thousands of people each year and there are no treatments that dramatically improve clinical outcome. Canine intervertebral disc herniation is a naturally-occurring SCI that has similarities to human injury and can be used as a translational model for evaluating therapeutic interventions. Here, we characterized cerebrospinal fluid (CSF) acute phase proteins (APPs) that have altered expression across a spectrum of neurological disorders, using this canine model system. The concentrations of C-reactive protein (CRP), haptoglobin (Hp), alpha-1-glycoprotein, and serum amyloid A were determined in the CSF of 42 acutely injured dogs, compared with 21 healthy control dogs. Concentrations of APPs also were examined with respect to initial injury severity and motor outcome 42 d post-injury. Hp concentration was significantly higher (p<0.0001) in the CSF of affected dogs, compared with healthy control dogs. Additionally, the concentrations of CRP and Hp were significantly (p=0.0001 and p=0.0079, respectively) and positively associated with CSF total protein concentration. The concentrations of CRP and Hp were significantly higher (p=0.0071 and p=0.0197, respectively) in dogs with severe injury, compared with those with mild-to-moderate SCI, but there was no significant correlation between assessed CSF APP concentrations and 42 d motor outcome. This study demonstrated that CSF APPs were dysregulated in dogs with naturally-occurring SCI and could be used as markers for SCI severity. As Hp was increased following severe SCI and is neuroprotective across a number of model systems, it may represent a viable therapeutic target.

Multivariate proteomic analysis of the cerebrospinal fluid of patients with peripheral neuropathic pain and healthy controls - a hypothesis-generating pilot study

Pain medicine lacks objective biomarkers to guide diagnosis and treatment. Combining two-dimensional gel proteomics with multivariate data analysis by projection, we exploratively analyzed the cerebrospinal fluid of eleven patients with severe peripheral neuropathic pain due to trauma and/or surgery refractory to conventional treatment and eleven healthy controls. Using orthogonal partial least squares discriminant analysis, we identified a panel of 36 proteins highly discriminating between the two groups. Due to a possible confounding effect of age, a new model with age as outcome variable was computed for patients (n=11), and four out of 36 protein spots were excluded due to a probable influence of age. Of the 32 remaining proteins, the following seven had the highest discriminatory power between the two groups: an isoform of angiotensinogen (upregulated in patients), two isoforms of alpha-1-antitrypsin (downregulated in patients), three isoforms of haptoglobin (upregulated in patients), and one isoform of pigment epithelium-derived factor (downregulated in patients). It has recently been hypothesized that the renin–angiotensin system may play a role in the pathophysiology of neuropathic pain, and a clinical trial of an angiotensin II receptor antagonist was recently published. It is noteworthy that when searching for neuropathic pain biomarkers with a purely explorative methodology, it was indeed a renin–angiotensin system protein that had the highest discriminatory power between patients and controls in the present study. The results from this hypothesis-generating pilot study have to be confirmed in larger, hypothesis-driven studies with age-matched controls, but the present study illustrates the fruitfulness of combining proteomics with multivariate data analysis in hypothesis-generating pain biomarker studies in humans.

Proteomic analysis of cerebrospinal fluid in canine cervical spondylomyelopathy

STUDY DESIGN

Prospective study.

OBJECTIVE

To identify proteins with differential expression in the cerebrospinal fluid (CSF) from 15 clinically normal (control) dogs and 15 dogs with cervical spondylomyelopathy (CSM).

SUMMARY OF BACKGROUND DATA

Canine CSM is a spontaneous, chronic, compressive cervical myelopathy similar to human cervical spondylotic myelopathy. There is a limited knowledge of the molecular mechanisms underlying these conditions. Differentially expressed CSF proteins may contribute with novel information about the disease pathogenesis in both dogs and humans.

METHODS

Protein separation was performed with 2-dimensional electrophoresis. A Student t test was used to detect significant differences between groups (P < 0.05). Three comparisons were made: (1) control versus CSM-affected dogs, (2) control versus non-corticosteroid-treated CSM-affected dogs, and (3) non-corticosteroid-treated CSM-affected versus corticosteroid-treated CSM-affected dogs. Protein spots exhibiting at least a statistically significant 1.25-fold change between groups were selected for subsequent identification with capillary-liquid chromatography tandem mass spectrometry.

RESULTS

A total of 96 spots had a significant average change of at least 1.25-fold in 1 of the 3 comparisons. Compared with the CSF of control dogs, CSM-affected dogs demonstrated increased CSF expression of 8 proteins including vitamin D-binding protein, gelsolin, creatine kinase B-type, angiotensinogen, α-2-HS-glycoprotein, SPARC (secreted protein, acidic, rich in cysteine), calsyntenin-1, and complement C3, and decreased expression of pigment epithelium-derived factor, prostaglandin-H2 D-isomerase, apolipoprotein E, and clusterin. In the CSF of CSM-affected dogs, corticosteroid treatment increased the expression of haptoglobin, transthyretin isoform 2, cystatin C-like, apolipoprotein E, and clusterin, and decreased the expression of angiotensinogen, α-2-HS-glycoprotein, and gelsolin.

CONCLUSION

Many of the differentially expressed proteins are associated with damaged neural tissue, bone turnover, and/or compromised blood-spinal cord barrier. The knowledge of the protein changes that occur in CSM and upon corticosteroid treatment of CSM-affected patients will aid in further understanding the pathomechanisms underlying this disease.

LEVEL OF EVIDENCE

N/A.

Association between serum haptoglobin and the pathogenesis of Alzheimer's disease

OBJECTIVE

Haptoglobin (Hpg) is known to have several functional properties, including antioxidant and anti-inflammatory activities. In addition, it has been shown that the pathogenesis of neurodegenerative disorders, such as Alzheimer's disease (AD), involves inflammation as well as oxidative stress. However, evidence suggesting an association between the serum Hpg level and AD is lacking. Therefore, we conducted this study in order to investigate whether serum Hpg is associated with AD.

METHODS

We compared the serum Hpg levels of 121 patients with newly diagnosed AD, 58 patients with Parkinson's disease (PD) and 43 healthy controls. We also evaluated the relationship between the severity of cognitive impairment in patients with AD and the serum Hpg level.

RESULTS

The mean serum Hpg level of the patients with AD was significantly higher than that of the healthy controls (p=0.042), although it was not significant different from that observed in the PD group (p=0.613). We also found a significant positive association between the serum Hpg level and the severity of cognitive impairment, as measured using several neuropsychological tests, in the patients with AD. The odds ratio (95% confidence interval) of the patients with AD grouped according to the Hpg level was 2.417 (95% confidence interval=1.134-5.149).

CONCLUSION

We observed a significantly higher mean serum Hpg level among the patients with AD compared to the healthy controls. These results support the hypothesis that oxidative stress and neuroinflammatory reactions play a role in the pathogenesis of AD.

Biomarkers for neuromyelitis optica

Neuromyelitis optica (NMO) is an acquired, heterogeneous inflammatory disorder, which is characterized by recurrent optic neuritis and longitudinally extensive spinal cord lesions. The discovery of the serum autoantibody marker, anti-aquaporin 4 (anti-AQP4) antibody, revolutionizes our understanding of pathogenesis of NMO. In addition to anti-AQP4 antibody, other biomarkers for NMO are also reported. These candidate biomarkers are particularly involved in T helper (Th)17 and astrocytic damages, which play a critical role in the development of NMO lesions. Among them, IL-6 in the peripheral blood is associated with anti-AQP4 antibody production. Glial fibrillary acidic protein (GFAP) in CSF demonstrates good correlations with clinical severity of NMO relapses. Detecting these useful biomarkers may be useful in the diagnosis and evaluation of disease activity of NMO. Development of compounds targeting these biomarkers may provide novel therapeutic strategies for NMO. This article will review the related biomarker studies in NMO and discuss the potential therapeutics targeting these biomarkers.