Quantification of neurodegeneration by measurement of brain-specific proteins (original) (raw)
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Comparison of two ELISA methods for measuring levels of the phosphorylated neurofilament heavy chain
Journal of Immunological Methods, 2007
Background: Recent studies suggest that the quantification of neurofilament subunits in cerebrospinal fluid (CSF), blood and amniotic fluid may reflect neuroaxonal damage and be of high clinical value. The present study aims to cross-validate two different independently developed ELISA techniques for the quantification of the phosphorylated axonal forms of the neurofilament heavy chain (pNfH). Methods: The London ELISA method is based on barbitone buffer and the commercially available SMI35 capture antibody. The Gainesville method uses Tris-buffered saline (TBS) and an affinity purified chicken polyclonal capture antibody (C-pNfH). Coded CSF from 50 patients with neurological diseases were analyzed in duplicate by both laboratories, each using both ELISA methods, but with each lab using their own detection antibody, tertiary antibody and chromogen. Methods were compared using Bland-Altman plots. Correlation and regression analyses were used to allow for transformation of values between both methods. Results: The Bland-Altman plots demonstrated that 96% of all samples fell into the narrow 95% limits of agreement (0.04 units of OD). There was a high correlation (Spearman R = 0.92, p b 0.0001 and Pearson R = 0.98, p b 0.0001) between the Gainesville (Y) and the London (X) method with Y = 0.132 + 1.104 ⁎ X. The previously determined upper reference limit of 0.73 mg/l (London method) corresponds to 0.94 mg/l for the Gainesville method. CSF pNfH levels above the reference limit were observed in patients with encephalitis, encephalomyelitis, hydrocephalus, subarachnoid haemorrhage, spino-muscular atrophy, stroke and cancer with both methods agreeing in all cases. Conclusion: The two assays are in excellent agreement, suggesting that pNfH, which has a number of unusual protein chemical features, may be the biomarker of choice for the routine and robust detection of axonal injury and degeneration in both research and clinical contexts.
Validation of a novel biomarker for acute axonal injury in experimental autoimmune encephalomyelitis
Journal of Neuroscience Research, 2008
In multiple sclerosis, inflammatory axonal injury is a key pathological mechanism responsible for the development of progressive neurological dysfunction. The injured axon represents a therapeutic target in this disease; however, therapeutic trials of neuroprotective candidates will initially require preclinical testing in an animal model of inflammatory axonal injury and subsequently the development of a reliable paraclinical measure of axonal degeneration in humans. In the present study, we demonstrate the validity of serum phosphorylated neurofilament H (pNF-H) as a marker of axonal injury in murine experimental autoimmune encephalomyelitis (EAE). At the time of maximum disease severity (EAE day 22), the average serum pNF-H level reached 5.7 ng/ml, correlating significantly with the EAE paraplegia score (r 5 0.75, P < 0.001). On average, 40% of axons in the spinal cord were lost in EAE, and serum pNF-H levels were highly correlated with axon loss (r 5 0.8, P < 0.001). Axonal injury was a severe and acute event, insofar as serum pNF-H levels were not significantly elevated at early (EAE day 12) or late (EAE days 35 and 50) disease time points. Our results demonstrate that acute inflammatory axonal injury is a pathological feature of murine MOG 35-55 EAE, indicating that this model may mirror the acute pathological events in active multiple sclerosis lesions. Furthermore, we have validated the serum pNF-H assay as an unbiased measurement of axonal injury in EAE, facilitating rapid screening of potential neuroprotective therapies in this model. V V C 2008 Wiley-Liss, Inc.
A sensitive ELISA for glial fibrillary acidic protein: application in CSF of adults
Journal of Neuroscience Methods, 1994
In the present study we describe a sensitive ELISA for determination of glial fibrillary acidic protein (GFAP). To validate the method combined determinations of GFAP and S-100 protein were performed in cerebrospinal fluid (CSF) of normal children and children with autism. The GFAP ELISA is of sandwich type and uses the biotin-avidin system. Sensitivity was 16 pg/ml. Between-day precision was 0.079 (coeff. of variance). S-100 protein concentrations were measured using a commercially available ELISA kit. Normal CSF from children and young adults were analysed. The CSF levels of GFAP in normal children were low (16-163 pg/ml). Both GFAP and S-100 protein concentrations correlated with age (P &amp;lt; 0.01 and P &amp;lt; 0.05, respectively), but the GFAP increment was more pronounced, probably reflecting the age-dependent expansion of the fibrillary astrocytes in the central nervous system (CNS). GFAP levels in children with infantile autism were higher than those in normal children of the same age range. S-100 protein concentrations were similar in both groups. High levels of GFAP in combination with normal S-100 protein concentrations in CSF indicates reactive astrogliosis in the CNS. In conclusion, the sensitive ELISA described makes it possible to measure low levels of GFAP present in the CSF of children. Combined assays of GFAP and S-100 protein can be used to discriminate between acute and chronic brain disorders in children.
An ELISA for glial fibrillary acidic protein
Journal of Immunological Methods, 2004
Glial fibrillary acidic protein (GFAP) is the major intermediate filament protein of the astrocyte, and body fluid levels of GFAP are an important tool for estimating astrogliosis and astrocytic activation in vivo. This paper presents a new sandwich ELISA allowing quantification of GFAP SMI26 from the cerebrospinal fluid (CSF). The sensitivity of the GFAP SMI26 ELISA is 5 pg/ml with a recovery of 94% and a mean within-and between-batch precision of 6% and 10%, respectively.
Neurofilaments as biomarkers in neurological disorders
Nature Reviews Neurology, 2018
Please check that you are happy with how it reads and that no crucial information has been removed.] Neuroaxonal damage is the pathological substrate of permanent disability in various neurological disorders. Reliable quantification and longitudinal follow-up of such damage is important for assessing disease activity, monitoring treatment responses, facilitating treatment development and prognostic purposes. The neurofilament proteins have promise in this context because their levels rise upon neuroaxonal damage not only in the CSF, but also in blood, and they indicate neuroaxonal injury independent of causal pathways. First-generation (immunoblot) and secondgeneration (enzyme-linked immunosorbent assay) neurofilament assays were of limited sensitivity. Third-generation (electrochemiluminescence) and especially fourth-generation (single molecule array) assays enable reliable measurement of neurofilaments throughout the range of concentrations found in blood samples. This technological advancement has paved the way to investigate neurofilaments in a range of neurological disorders. Here, we review what is known about the structure and function of neurofilaments, discuss analytical aspects and knowledge of age-dependent normal ranges of neurofilaments and provide a comprehensive overview of studies on neurofilament light as a marker for axonal injury in different neurological disorders, including multiple sclerosis, neurodegenerative dementia, stroke, traumatic brain injury, amyotrophic lateral sclerosis and Parkinson disease. We also consider work needed to explore the value of this axonal damage marker in managing neurological diseases in daily practice.
Hyperphosphorylated neurofilament NF-H is a serum biomarker of axonal injury
Biochemical and Biophysical Research Communications, 2005
Several lines of reasoning suggest that the phosphorylated axonal form of the neurofilament subunit NF-H is likely to be released from damaged and diseased neurons in significant amounts. Detection of this protein in serum or CSF might therefore provide information about the presence and degree of neuronal loss. We therefore developed a sensitive NF-H ELISA capable of detecting picogram quantities of phosphorylated NF-H (pNF-H). This assay showed that soluble pNF-H immunoreactivity is readily detectable in the sera of adult rats following various types of experimental spinal cord injury (SCI) and traumatic brain injury (TBI), but is undetectable in the sera of normal animals. Here we describe details of the time course and extent of serum pNF-H expression following experimental SCI and TBI. Following SCI, serum pNF-H showed an initial peak of expression at 16 h and a second, usually larger, peak at 3 days. Following TBI, lower levels of serum pNF-H were detected with a peak at 2 days post-injury. We also show that the higher levels of pNF-H released from injured spinal cord as compared to brain are in line with the $20-fold higher levels of pNF-H present in spinal cord. These findings suggest that serum levels of pNF-H immunoreactivity may be used to conveniently monitor neuronal damage and degeneration in experimental and presumably clinical situations.
Biomedicines
The understanding of neurodegenerative diseases, traditionally considered to be well-defined entities with distinguishable clinical phenotypes, has undergone a major shift over the last 20 years. The diagnosis of neurodegenerative diseases primarily requires functional brain imaging techniques or invasive tests such as lumbar puncture to assess cerebrospinal fluid. A new biological approach and research efforts, especially in vivo, have focused on biomarkers indicating underlying proteinopathy in cerebrospinal fluid and blood serum. However, due to the complexity and heterogeneity of neurodegenerative processes within the central nervous system and the large number of overlapping clinical diagnoses, identifying individual proteinopathies is relatively difficult and often not entirely accurate. For this reason, there is an urgent need to develop laboratory methods for identifying specific biomarkers, understand the molecular basis of neurodegenerative disorders and classify the quant...