Elevated haptoglobin level of cerebrospinal fluid in Guillain-Barré syndrome revealed by proteomics analysis

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.

Potential biomarkers identified by tandem mass tags based quantitative proteomics for diagnosis and classification of Guillain-Barré syndrome

BACKGROUND AND PURPOSE

Guillain-Barré syndrome (GBS) is an acute inflammatory autoimmune and demyelinating disease of the peripheral nervous system. Currently, valid biomarkers are unavailable for the diagnosis of GBS.

METHODS

A comparative proteomics analysis was performed on the cerebrospinal fluid (CSF) from 10 patients with GBS and 10 patients with noninflammatory neurological disease (NND) using the tandem mass tags technique. The differentially expressed proteins were analyzed by bioinformatics, and then the candidate proteins were validated by the enzyme-linked immunosorbent assay method in another cohort containing 160 samples (paired CSF and plasma of 40 patients with GBS, CSF of 40 NND patients and plasma of 40 healthy individuals).

RESULTS

In all, 298 proteins were successfully identified in the CSF samples, of which 97 differentially expressed proteins were identified in the GBS and NND groups. Three key molecules were identified as candidate molecules for further validation. The CSF levels of TGOLN2 and NCAM1 decreased in GBS patients compared with NND patients, whereas the CSF levels of APOC3 increased. The enzyme-linked immunosorbent assay results were consistent with our proteomics analysis. Interestingly, in the validation cohort, serum APOC3 levels in the GBS group were consistent with those in the CSF samples and significantly higher than those in the healthy control group.

CONCLUSIONS

Our preliminary data suggest that the CSF protein expression profile of patients with GBS is different from that of patients with NND. Moreover, alterations of TGOLN2, NCAM1and APOC3 may be used as novel biomarkers for identifying patients with GBS.

CSF Diagnostics: A Potentially Valuable Tool in Neurodegenerative and Inflammatory Disorders Involving Motor Neurons: A Review

Cerebrospinal fluid (CSF) diagnostics has emerged as a valid tool for a variety of neurological diseases. However, CSF diagnostics has been playing a subordinate role in the diagnosis of many neurological conditions. Thus, in the multitude of neuromuscular diseases in which motor neurons are affected, a CSF sample is rarely taken routinely. However, CSF diagnostics has the potential to specify the diagnosis and monitor the treatment of neuromuscular disorders. In this review, we therefore focused on a variety of neuromuscular diseases, among them amyotrophic lateral sclerosis (ALS), peripheral neuropathies, and spinal muscular atrophy (SMA), for which CSF diagnostics has emerged as a promising option for determining the disease itself and its progression. We focus on potentially valuable biomarkers among different disorders, such as neurofilaments, cytokines, other proteins, and lipids to determine their suitability, differentiating between different neurological disorders and their potential to determine early disease onset, disease progression, and treatment outcome. We further recommend novel approaches, e.g., the use of mass spectrometry as a promising alternative techniques to standard ELISA assays, potentially enhancing biomarker significance in clinical applications.

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.

Integrative metabolomics reveals unique metabolic traits in Guillain-Barré Syndrome and its variants

Guillain-Barré syndrome (GBS) is an acute fatal progressive disease caused by autoimmune mechanism mainly affecting peripheral nervous system. Although the syndrome is clinically sub-classified into several variants, specific biomarker and exact pathomechanism of each subtypes are not well elucidated yet. In current study, integrative metabolomic and lipidomic profiles were acquisitioned from cerebrospinal fluid samples of 86 GBS from three variants and 20 disease controls. And the data were systematically compared to our previous result on inflammatory demyelination disorders of central nervous system (IDDs) and healthy controls. Primary metabolite profiles revealed unique metabolic traits in which 9 and 7 compounds were specifically changed in GBS and IDD, respectively. Next, the biomarker panel with 10 primary metabolites showed a fairly good discrimination power among 3 GBS subtypes, healthy controls, and disease controls (AUCs ranged 0.849-0.999). The robustness of the biomarker panel was vigorously validated by multi-step statistical evaluation. Subsequent lipidomics revealed GBS variant-specific alteration where the significant elevations of lyso-phosphatidylcholines and sphingomyelins were unique to AIDP (acute inflammatory demyelinating polyneuropathy) and AMAN (acute motor axonal neuropathy), respectively. And metabolome-wide multivariate correlation analysis identified potential clinical association between GBS disability scale (Hughes score) and CSF lipids (monoacylglycerols, and sphingomyelins). Finally, Bayesian network analysis of covarianced structures of primary metabolites and lipids proposed metabolic hub and potential biochemical linkage associated with the pathology.

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.

Identification of CSF biomarkers by proteomics in Guillain-Barré syndrome

The purpose of the present study was to screen for differentially expressed proteins in the cerebrospinal fluid (CSF) of patients with Guillain-Barré syndrome (GBS). The identification of differentially expressed protein can provide new targets for understanding the pathogenic mechanism, early clinical diagnosis, prognosis and for measuring the effectiveness of interventions. We enrolled 50 GBS patients and 50 meningitis patients (control group) to compare protein expression in CSF. The GBS cases included 28 cases of acute inflammatory demyelinating polyneuropathy (AIDP) and 22 cases of acute motor axonal neuropathy (AMAN). We then performed two-dimensional differential in-gel electrophoresis combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to identify the differentially expressed proteins. The expression levels were validated by ELISA, and their accuracy, sensitivity, and specificity in GBS diagnosis were analyzed by the receiver operating characteristic curve. Three differentially expressed proteins were identified, including the upregulated haptoglobin (Hp) and heat shock protein 70 (Hsp70), and downregulated cystatin C. There were no significant differences between the AIDP and AMAN patients in the positive rates and quantitative expression levels of the three differentially expressed proteins. The accuracy of Hp in the diagnosis of GBS was 0.835, sensitivity was 86.7%, and specificity was 88.2%. The accuracy of cystatin C in the diagnosis of GBS was 0.827, sensitivity was 85.5%, and specificity was 89.7%. The accuracy of Hsp70 in the diagnosis of GBS was 0.841, its sensitivity was 87.8%, and its specificity was 92.3%. Hp and Hsp70 are significantly increased, and cystatin C is downregulated in CSF of GBS patients, which provides important biomarkers for early GBS diagnosis, although these proteins cannot distinguish AIDP and AMAN.

Could Proteomics Become a Future Useful Tool to Shed Light on the Mechanisms of Rare Neurodegenerative Disorders?

Very often the clinical features of rare neurodegenerative disorders overlap with those of other, more common clinical disturbances. As a consequence, not only the true incidence of these disorders is underestimated, but many patients also experience a significant delay before a definitive diagnosis. Under this scenario, it appears clear that any accurate tool producing information about the pathological mechanisms of these disorders would offer a novel context for their precise identification by strongly enhancing the interpretation of symptoms. With the advent of proteomics, detection and identification of proteins in different organs/tissues, aimed at understanding whether they represent an attractive tool for monitoring alterations in these districts, has become an area of increasing interest. The aim of this report is to provide an overview of the most recent applications of proteomics as a new strategy for identifying biomarkers with a clinical utility for the investigation of rare neurodegenerative disorders.

Disturbance of Plasma Lipid Metabolic Profile in Guillain-Barre Syndrome

Guillain-Barre Syndrome (GBS) is an inflammatory disease of the peripheral nervous system. Given that plasma metabolic profiles in GBS patients have never been explored, plasma samples of 38 GBS patients, 22 multiple sclerosis (MS) patients, and 40 healthy controls were analyzed by using untargeted and targeted metabolomics analysis. The untargeted analysis showed that levels of a set of plasma lipid metabolites were significantly decreased in GBS patients compared to the controls. Furthermore, the targeted analysis demonstrated that levels of 41 metabolites in GBS patients were significantly changed compared to either the controls or MS patients. A further metabolic analysis showed that 12 of 41 metabolites were significantly lower in classical GBS patients compared to Miller-Fisher syndrome. Among them, each of PCae C34:0, PCae C42:2, PCae C42:3, and SM C24:0 was inversely correlated with Hughes functional grading scale of GBS patients at both nadir and discharge. Receiver operating characteristic curve analysis of combination of three metabolites (PCaa C42:2, PCae C36:0 and SM C24:0) showed a good discrimination between the GBS and the controls (area under curve = 0.86). This study has demonstrated disruption of lipid metabolites in GBS may be potential biomarkers to indicate disease severity and prognosis of GBS.

Alterations of plasma concentrations of lipophilic antioxidants are associated with Guillain-Barre syndrome

BACKGROUND

Guillain-Barré syndrome (GBS) is an acute inflammatory polyneuropathy resulting in demyelination in peripheral nervous system. Myelin enriched in lipids is easily oxidized by reactive oxygen species during inflammation. Oxidative stress and lipophilic anti-oxidative capacities in GBS patients have not been fully explored. To evaluate the redox status of GBS patients, we measured malondialdehyde (MDA), myeloperoxidase (MPO), lipophilic antioxidants, and tocopherols concentrations in plasma from GBS patients and age-matched healthy controls.

RESULTS

Concentrations of γ-tocopherol and δ-tocopherol decreased significantly, and α-carotene significantly increased in GBS patients compared to healthy controls. However, no significant changes in MDA and MPO concentrations were detected. In GBS patients, the γ-tocopherol concentration correlated positively with concentrations of δ-tocopherol, α-tocopherol, lutein, Q10, and γ-CEHC, respectively. Similarly, the δ-tocopherol concentration correlated positively with γ-tocopherol, α-tocopherol, lutein, Q10, δ-CEHC, and γ-CEHC concentrations, respectively. The receiver operating characteristics curve analysis showed that γ-tocopherol may serve as a good predictor for GBS.

CONCLUSIONS

Diminished lipophilic antioxidant defense, mainly γ-tocopherol and δ-tocopherol, in GBS patients accounting for their lowered resistance to reactive oxygen species is probably associated with pathogenesis of GBS, and potentially useful for the development of therapeutic strategies.

Cerebrospinal fluid findings in Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathies

The classic immunologic alteration of the cerebrospinal fluid (CSF) in Guillain-Barré syndrome (GBS), albuminocytologic dissociation, has been known since the original paper by Guillain, Barré, and Strohl. Albuminocytologic dissociation has been also described in other forms of the GBS spectrum, such as axonal motor or motor-sensory forms (AMAN, AMSAN), the anti-GQ1b spectrum of Miller Fisher syndrome, and Bickerstaff brainstem encephalitis. Cytokines, chemokines, antibodies, complement components, and molecules with a putative neuroprotective role or indicating axonal damage have also been examined using different methods. Besides these candidate approaches, proteomics has been recently applied to discover potential biomarkers. The overall results support the immunopathogenesis of GBS, but albuminocytologic dissociation remained the only consistent CSF biomarker supporting the diagnosis of GBS. Chronic inflammatory neuropathies also comprise a heterogeneous group of diseases. Increased protein in the CSF is a supportive factor of chronic inflammatory demyelinating polyneuropathy, especially in the absence of definite electrophysiologic criteria. A number of other markers have also been investigated in the CSF of patients with chronic inflammatory neuropathies, similar to GBS. However, none has been used in supporting diagnosis, differentiating among syndromes, or predicting the clinical course and treatment responses.

Increased serum concentrations of transforming growth factor-β1 (TGF-β1) in patients with Guillain-Barré syndrome

BACKGROUND

Guillain-Barré syndrome (GBS) is an acquired demyelinating peripheral neuropathy. It has shown that macrophage activation contribute to the pathogenesis of GBS. Therefore macrophage-mediated factors could be the potential markers for disease diagnosis and status of GBS.

METHODS

We measured serum concentrations of 4 macrophage-mediated factors, including interleukin-6 (IL-6), transforming growth factor-β1 (TGF-β1), vascular cell adhesion protein 1 (VCAM-1) and vascular endothelial growth factor (VEGF), in 23 chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), 28 GBS, 11 Miller-Fisher syndrome (MFS), 40 multiple sclerosis (MS), and 12 Alzheimer's disease (AD) patients, as well as 15 healthy controls.

RESULTS

Serum TGF-β1 concentration of GBS patients (35.94±2.55ng/ml) was significantly higher compared with CIDP (25.46±1.40ng/ml, P<0.001), MFS (25.32±2.31ng/ml, P=0.010), MS (21.35±0.90ng/ml, P<0.001) and AD patients (22.92±1.82ng/ml, P<0.001), as well as healthy controls (23.12±1.67ng/ml, P<0.001). A positive correlation between serum TGF-β1 concentrations and Hughes' functional grading scales was observed in GBS patients. Serum concentrations of IL-6, VCAM-1 and VEGF were similar between the studied groups.

CONCLUSION

The high serum concentrations of TGF-β1 and the correlation between serum TGF-β1 concentration and disease severity highlight the potential of TGF-β1 as a biomarker of GBS.

The immunobiology of Campylobacter jejuni: Innate immunity and autoimmune diseases

The Gram-negative bacterium Campylobacter jejuni causes gastroenteritis and Guillain-Barré syndrome in humans. Recent advances in the immunobiology of C. jejuni have been made. This review summarizes C. jejuni-binding innate receptors and highlights the role of innate immunity in autoimmune diseases. This human pathogen produces a variety of glycoconjugates, including human ganglioside-like determinants and multiple activators of Toll-like receptors (TLRs). Furthermore, C. jejuni targets MyD88, NLRP3 inflammasome, TIR-domain-containing adapter-inducing interferon-β (TRIF), sialic acid-binding immunoglobulin-like lectins (Siglecs), macrophage galactose-type lectin (MGL), and immunoglobulin-like receptors (TREM2, LMIR5/CD300b). The roles of these innate receptors and signaling molecules have been extensively studied. MyD88-mediated TLR activation or inflammasome-dependent IL-1β secretion is essential for autoimmune induction. TRIF mediates the production of type I interferons that promote humoral immune responses and immunoglobulin class-switching. Siglec-1 and Siglec-7 interact directly with gangliosides. Siglec-1 activation enhances phagocytosis and inflammatory responses. MGL internalizes GalNAc-containing glycoconjugates. TREM2 is well-known for its role in phagocytosis. LMIR5 recognizes C. jejuni components and endogenous sulfoglycolipids. Several lines of evidence from animal models of autoimmune diseases suggest that simultaneous activation of innate immunity in the presence of autoreactive lymphocytes or antigen mimicry may link C. jejuni to immunopathology.

Inflammatory neuropathies: pathology, molecular markers and targets for specific therapeutic intervention

Inflammatory neuropathies encompass groups of heterogeneous disorders characterized by pathogenic immune-mediated hematogenous leukocyte infiltration of peripheral nerves, nerve roots or both, with resultant demyelination or axonal degeneration or both. Inflammatory neuropathies may be divided into three major disease categories: Guillain-Barré syndrome (particularly the acute inflammatory demyelinating polyradiculoneuropathy variant), chronic inflammatory demyelinating polyradiculoneuropathy and nonsystemic vasculitic neuropathy (or peripheral nerve vasculitis). Despite major advances in molecular biology, pathology and genetics, the pathogenesis of these disorders remains elusive. There is insufficient knowledge on the mechanisms of hematogenous leukocyte trafficking into the peripheral nervous system to guide the development of specific molecular therapies for immune-mediated inflammatory neuropathies compared to disorders such as psoriasis, inflammatory bowel disease, rheumatoid arthritis or multiple sclerosis. The recent isolation and characterization of human endoneurial endothelial cells that form the blood-nerve barrier provides an opportunity to elucidate leukocyte-endothelial cell interactions critical to the pathogenesis of inflammatory neuropathies at the interface between the systemic circulation and peripheral nerve endoneurium. This review discusses our current knowledge of the classic pathological features of inflammatory neuropathies, attempts at molecular classification and genetic determinants, the utilization of in vitro and in vivo animal models to determine pathogenic mechanisms at the interface between the systemic circulation and the peripheral nervous system relevant to these disorders and prospects for future potential molecular pathology biomarkers and targets for specific therapeutic intervention.

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.

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

BACKGROUND

Neuromyelitis optica (NMO), which was previously considered a variant of multiple sclerosis (MS), is characterized by recurrent optic neuritis and longitudinally extensive spinal cord lesions. It has been shown that the level of haptoglobin in cerebrospinal fluid (CSF) is elevated in NMO. However, it is uncertain whether this change is specific to NMO, or is also seen in MS and other neurological diseases.

METHODS

We used an enzyme-linked immunosorbent assay (ELISA) to measure the haptoglobin levels in the CSF and serum in 25 NMO, 16 MS, and 15 Alzheimer's disease (AD) patients and 22 controls.

RESULTS

The CSF haptoglobin concentration of the NMO patients (0.309±0.074mg/dl, P<0.001) was significantly higher than that of MS patients (0.081±0.016mg/dl) and AD patients (0.058±0.011mg/dl), and the controls (0.060±0.009mg/dl), whereas the serum haptoglobin and albumin concentrations in the serum and CSF did not differ significantly across groups. NMO patients (0.59±0.15, P=0.001) demonstrated a higher haptoglobin index than MS patients (0.13±0.01), AD patients (0.12±0.03), and the controls (0.17±0.04). Furthermore, the haptoglobin concentration and haptoglobin index in the CSF correlated significantly with the expanded disability scale score (EDSS) in NMO patients.

CONCLUSIONS

The high CSF haptoglobin concentration in NMO may be explained by increased intrathecal haptoglobin synthesis. The correlation between CSF haptoglobin concentration/haptoglobin index and EDSS highlights the potential of haptoglobin as a biomarker of NMO.

Proteomics-based identification of haptoglobin as a favourable serum biomarker for predicting long-term response to splenectomy in patients with primary immune thrombocytopenia

BACKGROUND

Splenectomy is the most effective treatment for patients with primary immune thrombocytopenia (ITP) who fail to respond to steroid therapy. Thus far, there is no effective means to predict the long-term haematological response of the procedure. The purpose of this study was to identify serum biomarkers as predictors of long-term response based on a proteomics approach.

METHODS

The serum samples of ITP patients were collected before splenectomy and seven days after surgery. After depletion of the abundant serum proteins, pooled preoperative serum samples from four responders to splenectomy, four nonresponders and four healthy controls were subjected to two-dimensional gel electrophoresis (2-DE). Nine protein spots with at least a five-fold alteration in expression between responders and nonresponders were all identified as haptoglobin (Hp) by matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometer (MS) analysis. The validation of serum Hp expression was performed using enzyme-linked immunosorbent assays (ELISA) in thirty-seven responders, thirteen nonresponders and twenty-one healthy controls.

RESULTS

The preoperative serum levels of Hp in the nonresponders (925.9 ± 293.5 μg/ml) were significantly lower than those in the responders (1417.4 ± 315.0 μg/ml, p <0.001) and the healthy controls (1409.1 ± 354.2 μg/ml, p <0.001), while there was no significant difference between the latter two groups. The postoperative serum levels of Hp in responders and nonresponders were (1414.1 ± 225.0 μg/ml) and (952.9 ± 202.4 μg/ml), respectively. There were no significant differences between the serum Hp levels before and after surgery in both responders and nonresponders (p>0.05). The preoperative serum levels of Hp did not significantly correlate with preoperative platelet count of the same blood samples (r = 0.244, p = 0.087), while it positively correlated with postoperative peak platelet count (r = 0.622, p < 0.001). The optimal cutoff value of preoperative serum Hp levels (1173.80 μg/ml) derived from the receiver operating characteristic (ROC) curve led to 78.4% sensitivity and 84.6% specificity.

CONCLUSIONS

These results suggest that serum Hp levels may serve as a favourable predictor for the long-term response to splenectomy in ITP and may help to understand the pathophysiological differences between responders and nonresponders.

Altered cerebrospinal fluid index of prealbumin, fibrinogen, and haptoglobin in patients with Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy

OBJECTIVES

Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP) are autoimmune diseases of the peripheral nervous system. A clinical hallmark of GBS and CIDP is the albumino-cytologic dissociation in the cerebrospinal fluid (CSF). Changes in the CSF levels of proteins other than albumin in patients with GBS and CIDP are not as well studied. If altered, aberrant levels of CSF proteins may render it possible to establish useful biomarkers for GBS and CIDP.

MATERIALS AND METHODS

Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of prealbumin, fibrinogen, haptoglobin, apolipoprotein E, apolipoprotein A4 in both CSF and plasma samples from 19 patients with GBS and eight with CIDP, 24 controls with multiple sclerosis (MS) as well as 20 patients with other non-inflammatory neurological disorders (OND).

RESULTS

The levels of prealbumin in both the plasma and the CSF were elevated in patients with GBS and MS compared with the controls. The higher levels of fibrinogen were seen in the CSF of patients with GBS and CIDP, but not in the plasma. The levels of CSF prealbumin and fibrinogen, measured by the CSF index of these proteins, were lower in patients with GBS and that of fibrinogen in patients with CIDP compared with controls with OND. Haptoglobin levels in the CSF rather than in the plasma were higher in patients with GBS and CIDP than in controls. The CSF haptoglobin index was higher in patients with CIDP and MS, but not in those with GBS. No correlation was found between levels of CSF proteins and clinical parameters in patients with GBS and CIDP.

CONCLUSIONS

Our data provide preliminary evidence that GBS is associated with low CSF index levels of prealbumin and fibrinogen, but normal levels of haptoglobin, whereas CIDP is associated with normal CSF index levels of prealbumin, low fibrinogen, and high levels of haptoglobin. Further studies are needed to identify the underlying mechanisms behind these CSF protein alterations and to clarify whether prealbumin, fibrinogen, and haptoglobin can serve as useful biomarkers for GBS and CIDP.

Identification of gene networks and pathways associated with Guillain-Barré syndrome

BACKGROUND

The underlying change of gene network expression of Guillain-Barré syndrome (GBS) remains elusive. We sought to identify GBS-associated gene networks and signaling pathways by analyzing the transcriptional profile of leukocytes in the patients with GBS.

METHODS AND FINDINGS

Quantitative global gene expression microarray analysis of peripheral blood leukocytes was performed on 7 patients with GBS and 7 healthy controls. Gene expression profiles were compared between patients and controls after standardization. The set of genes that significantly correlated with GBS was further analyzed by Ingenuity Pathways Analyses. 256 genes and 18 gene networks were significantly associated with GBS (fold change ≥2, P<0.05). FOS, PTGS2, HMGB2 and MMP9 are the top four of 246 significantly up-regulated genes. The most significant disease and altered biological function genes associated with GBS were those involved in inflammatory response, infectious disease, and respiratory disease. Cell death, cellular development and cellular movement were the top significant molecular and cellular functions involved in GBS. Hematological system development and function, immune cell trafficking and organismal survival were the most significant GBS-associated function in physiological development and system category. Several hub genes, such as MMP9, PTGS2 and CREB1 were identified in the associated gene networks. Canonical pathway analysis showed that GnRH, corticotrophin-releasing hormone and ERK/MAPK signaling were the most significant pathways in the up-regulated gene set in GBS.

CONCLUSIONS

This study reveals the gene networks and canonical pathways associated with GBS. These data provide not only networks between the genes for understanding the pathogenic properties of GBS but also map significant pathways for the future development of novel therapeutic strategies.

Increased prothrombin, apolipoprotein A-IV, and haptoglobin in the cerebrospinal fluid of patients with Huntington's disease

Huntington's disease (HD) is a progressive neurodegenerative disease caused by an unstable CAG trinucleotide repeat expansion. The need for biomarkers of onset and progression in HD is imperative, since currently reliable outcome measures are lacking. We used two-dimensional electrophoresis and mass spectrometry to analyze the proteome profiles in cerebrospinal fluid (CSF) of 6 pairs of HD patients and controls. Prothrombin, apolipoprotein A-IV (Apo A-IV) and haptoglobin were elevated in CSF of the HD patients in comparison with the controls. We used western blot as a semi-quantified measurement for prothrombin and Apo A-IV, as well as enzyme linked immunosorbent assay (ELISA) for measurement of haptoglobin, in 9 HD patients and 9 controls. The albumin quotient (Qalb), a marker of blood-brain barrier (BBB) function, was not different between the HD patients and the controls. The ratios of CSF prothrombin/albumin (prothrombin/Alb) and Apo A-IV/albumin (Apo A-IV/Alb), and haptoglobin level were significantly elevated in HD. The ratio of CSF prothrombin/Alb significantly correlated with the disease severity assessed by Unified Huntington's Disease Rating Scale (UHDRS). The results implicate that increased CSF prothrombin, Apo A-IV, and haptoglobin may be involved in pathogenesis of HD and may serve as potential biomarkers for HD.

Analyses of transthyretin concentration in the cerebrospinal fluid of patients with Guillain-Barré syndrome and other neurological disorders

BACKGROUND

Guillain-Barré syndrome (GBS) is an autoimmune inflammatory polyradiculoneuropathy that causes acute areflexic paralysis with a high risk of respiratory failure. Previously, using two-dimensional gel electrophoresis and mass spectrometry, we found that the transthyretin level was altered in the cerebrospinal fluid (CSF) of GBS patients when compared to that in CSF of control patients.

METHODS

We used enzyme-linked immunosorbent assay (ELISA) to measure the transthyretin levels in the CSF and serum from 22 GBS, 4 Miller-Fisher syndrome (MFS), 9 chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), 22 multiple sclerosis (MS), 10 Alzheimer's disease (AD), and 6 viral meningitis (VM) patients, and 18 controls.

RESULTS

The results show that CSF transthyretin concentration of the GBS patients is significantly higher than that of the control, MS, AD and VM patients (p<0.05), although not significantly different from that of MFS and CIDP patients.

CONCLUSION

The increased CSF transthyretin level may be explained by barrier dysfunction or decreased CSF flow in the GBS patients along with increased intrathecal synthesis of transthyretin that might be a protective response to nerve damage.

Decreased intrathecal synthesis of prostaglandin D2 synthase in the cerebrospinal fluid of patients with acute inflammatory demyelinating polyneuropathy

Prostaglandin D(2) synthase (PGDS) is the most abundant brain protein in cerebrospinal fluid (CSF) and is tied closely with inflammatory processes. This study investigated whether CSF PGDS levels in patients with acute inflammatory demyelinating polyneuropathy (AIDP) are altered. The results suggest that PGDS concentration is significantly increased in the CSF of AIDP patients compared with the control patients (p<0.05) due to a blood-CSF barrier dysfunction, whereas the intrathecal synthesis of PGDS, reflected by the CSF PGDS/albumin ratio, is significantly decreased in AIDP compared with the control group (p<0.05). The changes of CSF PGDS/albumin ratio are only observed in AIDP patients, but not in Miller Fisher Syndrome (MFS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), or multiple sclerosis (MS) patients.

MALDI-TOF/TOF-MS reveals elevated serum haptoglobin and amyloid A in Behcet's disease

Behcet's disease (BD) is a multisystemic autoimmune disease with unclear etiology and pathogenesis. To screen aberrant serum proteins in BD, serum samples were obtained from eight male BD patients with active uveitis and eight male healthy volunteers with informed consent. The serum samples from active BD patients and normal controls were pooled. Highly abundant serum proteins (albumin and IgG) were depleted from these two samples using an affinity capture based kit. The obtained samples were subjected to two-dimensional gel electrophoresis (2-DE). Protein spots were visualized with the "blue silver" staining. Differently expressed proteins were subsequently identified by matrix-assisted laser desorption /ionization tandem time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). Western blot and enzyme-linked immunosorbent assay (ELISA) were performed using the serum samples from 18 patients with active BD, 6 patients with inactive BD, 22 patients with Vogt-Koyanagi-Harada (VKH) syndrome, and 20 healthy volunteers to validate the results of 2-DE and MS. Proteomic profiles of the pooled samples were compared, and approximately 800 protein spots were observed in each of the gels. Expression levels of four of the protein spots in active BD were significantly higher than those in the normal controls. Mass spectrometric protein identification revealed that the four protein spots corresponded to two proteins: haptoglobin (Hp) and serum amyloid A (SAA). Western blot and ELISA showed that Hp was only overexpressed in active BD but not in inactive BD, VKH syndrome, or healthy controls. An obvious band of SAA was detected in 72.2% of the serum samples from BD patients, whereas a vague band of this protein was found in 10.0% of the tested normal samples and 9.1% of VKH samples. Our results revealed a significantly increased expression of Hp and SAA in serum of active BD patients. These two proteins may be involved in the development of BD.