Evidence for a Role of Nerve Injury in Painful Intervertebral Disc Degeneration: A Cross-Sectional Proteomic Analysis of Human Cerebrospinal Fluid.

Intervertebral disc degeneration (DD) is a cause of low back pain (LBP) in some individuals. However, although >30% of adults have DD, LBP only develops in a subset of individuals. To gain insight into the mechanisms underlying nonpainful versus painful DD, human cerebrospinal fluid (CSF) was examined using differential expression shotgun proteomic techniques comparing healthy control participants, subjects with nonpainful DD, and patients with painful DD scheduled for spinal fusion surgery. Eighty-eight proteins were detected, 27 of which were differentially expressed. Proteins associated with DD tended to be related to inflammation (eg, cystatin C) regardless of pain status. In contrast, most differentially expressed proteins in DD-associated chronic LBP patients were linked to nerve injury (eg, hemopexin). Cystatin C and hemopexin were selected for further examination using enzyme-linked immunosorbent assay in a larger cohort. While cystatin C correlated with DD severity but not pain or disability, hemopexin correlated with pain intensity, physical disability, and DD severity. This study shows that CSF can be used to study mechanisms underlying painful DD in humans, and suggests that while painful DD is associated with nerve injury, inflammation itself is not sufficient to develop LBP. PERSPECTIVE: CSF was examined for differential protein expression in healthy control participants, pain-free adults with asymptomatic intervertebral DD, and LBP patients with painful intervertebral DD. While DD was related to inflammation regardless of pain status, painful degeneration was associated with markers linked to nerve injury.

Heme-Hemopexin Scavenging Is Active in the Brain and Associates With Outcome After Subarachnoid Hemorrhage.

BACKGROUND AND PURPOSE: Long-term outcome after subarachnoid hemorrhage (SAH) is potentially linked to cytotoxic heme. Free heme is bound by hemopexin and rapidly scavenged by CD91. We hypothesized that heme scavenging in the brain would be associated with outcome after hemorrhage. METHODS: Using cerebrospinal fluid and tissue from patients with SAH and control individuals, the activity of the intracranial CD91-hemopexin system was examined using ELISA, ultrahigh performance liquid chromatography, and immunohistochemistry. RESULTS: In control individuals, cerebrospinal fluid hemopexin was mainly synthesized intrathecally. After SAH, cerebrospinal fluid hemopexin was high in one third of cases, and these patients had a higher probability of delayed cerebral ischemia and poorer neurological outcome. The intracranial CD91-hemopexin system was active after SAH because CD91 positively correlated with iron deposition in brain tissue. Heme-hemopexin uptake saturated rapidly after SAH because bound heme accumulated early in the cerebrospinal fluid. When the blood-brain barrier was compromised after SAH, serum hemopexin level was lower, suggesting heme transfer to the circulation for peripheral CD91 scavenging. CONCLUSIONS: The CD91-heme-hemopexin scavenging system is important after SAH and merits further study as a potential prognostic marker and therapeutic target.

Proteomics-derived cerebrospinal fluid markers of autopsy-confirmed Alzheimer's disease.

The diagnostic performance of several candidate cerebrospinal fluid (CSF) protein biomarkers in neuropathologically confirmed Alzheimer's disease (AD), non-demented (ND) elderly controls and non-AD dementias (NADD) was assessed. Candidate markers were selected on the basis of initial two-dimensional gel electrophoresis studies or by literature review. Markers selected by the former method included apolipoprotein A-1 (ApoA1), haemopexin (HPX), transthyretin (TTR) and pigment epithelium-derived factor (PEDF), while markers identified from the literature included Abeta1-40, Abeta1-42, total tau, phosphorylated tau, alpha-1 acid glycoprotein (A1GP), haptoglobin, zinc alpha-2 glycoprotein (Z2GP) and apolipoprotein E (ApoE). Ventricular CSF concentrations of the markers were measured by enzyme-linked immunosorbent assay (ELISA). The concentrations of Abeta1-42, ApoA1, A1GP, ApoE, HPX and Z2GP differed significantly among AD, ND and NADD subjects. Logistic regression analysis for the diagnostic discrimination of AD from ND found that Abeta1-42, ApoA1 and HPX each had significant and independent associations with diagnosis. The CSF concentrations of these three markers distinguished AD from ND subjects with 84% sensitivity and 72% specificity, with 78% of subjects correctly classified. By comparison, using Abeta1-42 alone gave 79% sensitivity and 61% specificity, with 68% of subjects correctly classified. For the diagnostic discrimination of AD from NADD, only the concentration of Abeta1-42 was significantly related to diagnosis, with a sensitivity of 58%, specificity of 86% and 86% correctly classified. The results indicate that for the discrimination of AD from ND control subjects, measurement of a set of markers including Abeta1-42, ApoA1 and HPX improved diagnostic performance over that obtained by measurement of Abeta1-42 alone. For the discrimination of AD from NADD subjects, measurement of Abeta1-42 alone was superior.

Comparative proteomics of cerebrospinal fluid in neuropathologically-confirmed Alzheimer's disease and non-demented elderly subjects.

OBJECTIVES: Diagnostic tests able to reveal Alzheimer's disease (AD) in living patients before cognitive ability is destroyed are urgently needed. Such tests must distinguish AD from other dementia causes, as well as differentiate subtle changes associated with normal aging from true pathology emergence. A single biomarker offering such diagnostic and prognostic capacities has eluded identification. Therefore, a valuable test for AD is likely to be based on a specific pattern of change in a set of proteins, rather than a single protein. METHODS: We examined pooled cerebrospinal fluid (CSF) samples obtained from neuropathologically-confirmed AD (n=43) and non-demented control subjects (n=43) using 2-dimensional gel electrophoresis (2DE) proteomic methodology to detect differentially expressed proteins. Proteins exhibiting expression level differences between the pools were recovered and identified using matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. RESULTS: Five differentially-expressed proteins with potential roles in amyloid-beta metabolism and vascular and brain physiology [apolipoprotein A-1 (Apo A-1), cathepsin D (CatD), hemopexin (HPX), transthyretin (TTR), and two pigment epithelium-derived factor (PEDF) isoforms] were identified. Apo A-1, CatD and TTR were significantly reduced in the AD pool sample, while HPX and the PEDF isoforms were increased in AD CSF. DISCUSSION: These results suggest that multi-factor proteomic pattern analysis of the CSF may provide a means to diagnose and assess AD.

Differential changes in alpha2-macroglobulin and hemopexin in brain and liver in response to acute inflammation.

Changes in serum and cerebrospinal fluid (CSF) proteins following generalized acute inflammation induced by fermented yeast in the rat was examined by concanavalin A-blotting, immunoblotting, and radioimmunoassay. Using alpha2-macroglobulin (alpha2-M) and hemopexin (HPX) as marker proteins, the concentration alpha2-M was found to increase in serum and CSF by 150- and 5-fold, respectively, whereas the concentration of HPX increased by about 4-fold in both fluids following yeast-induced inflammation. The lesser increase in alpha2-M in the CSF versus the systemic circulation is not likely to be the result of changes in the permeability of the blood--brain barrier, since no change in the total protein content of CSF was detected in inflamed rats when compared to control animals. These results, however, illustrate the regulation of the same protein, such as alpha2-M, in two separate organs within the same animal can be drastically different. These results also suggest a possible protective role of alpha2-M in the brain during acute inflammation. Moreover, these observations are consistent with the previous observation that there is a differential response in the level of alpha2-M between the testis and the systemic circulation during inflammation.

[On the origin and diagnostic value of the CSF-beta-globulins (author's transl)]. / Zur Frage der Herkunft und der diagnostischen Bedeutung der Liquor-Beta-Globuline.

208 cerebrospinal fluid samples were taken from patients having various patterns of neurological diseases. The following beta-globulins: transferrin, haemopexin, beta-1 A-globulin, beta-1 E-globulin, beta-2-glycoproteid and beta-lipoproteid were determined immunologically quantitatively in the CSF and partly quantitatively in the serum, and their behaviour was compared with that of the beta and tau fraction in CSF electrophoresis. It was found that changes in the fractions in CSF electrophoresis agreed only slightly with those of the quantitatively determined globulins, although these globulins represent 70--80% of the beta and tau fraction. Increases in the number of beta-1 A and beta-1 E-globulins are more significantly marked in intracranial haemorrhages than with other diseases. In all other respects, increases or decreases in the number of beta-globulins do not appear to be typical of any particular disease pattern determined by electrophoresis or quantitatively. Due to the linearity of the changes in case of disturbances of the CSF barrier, and also on account of the absolutely parallel behaviour of the beta-globulins, it was concluded that transferrin--contrary to the opinion held so far--is produced cerebrally in only small quantities or possibly not at all, and that the entirety of beta-globulins originate from the serum.