ERK2 is increased in cerebrospinal fluid of Creutzfeldt-Jakob disease patients.

The clinical diagnosis of Creutzfeldt-Jakob disease (CJD) can be supported by several biochemical markers in cerebrospinal fluid (CSF) such as 14-3-3 proteins and tau protein. Unfortunately, none of the currently known markers are suited for screening or seems to be directly related to the pathophysiological process. A marker fulfilling these criteria might facilitate the early detection and might also serve in monitoring drug efficacy. Recently, the extracellular signal-regulated kinase ERK1/2 was detected in CSF of patients with neuropsychiatric disorders. Furthermore, ERK1/2 was reported to be activated in brains of animals infected with pathological prion protein. Therefore, we investigated CSF of 19 patients with CJD, 23 patients with other dementias including patients with Alzheimer's disease, and 12 patients with other neurological disorders. The measurement of ERK1/2 in the CSF samples was performed with an electrochemiluminescence assay and Western immunoblot. ERK1/2 and doubly phosphorylated ERK1/2 (pERK1/2) were detected in all patient groups. Significantly elevated mean levels of total ERK1/2 and pERK1/2 were found in the CJD patients. This increase was also observed in a CJD case that was negative for 14-3-3 protein or in CJD cases that had low levels of tau protein. Western immunoblot analysis suggested that ERK2 was the predominant form of ERKs present in our CSF samples. This pilot study suggests that ERK1/2 is a potential CSF biomarker for CJD, directly associated with the pathophysiological processes. Analysis of larger sample cohorts including other diseases with rapid neurodegeneration are required to confirm our findings.

Ubiquitin as potential cerebrospinal fluid marker of Creutzfeldt-Jakob disease.

Until today, a definite diagnosis of Creutzfeldt-Jakob disease (CJD) can only be made neuropathologically. At lifetime the early and differential diagnosis is often a problem. With SELDI we analyzed cerebrospinal fluid (CSF) from 32 CJD patients, 32 patients having other dementive diseases and 31 non-demented control subjects for diagnosis-dependent protein pattern differences. In a screening set of patients, peaks that discriminate best between groups were identified. These peaks were subsequently analyzed using an independent validation set of patients. Diagnostic accuracies were compared with established markers like tau protein and 14-3-3-protein. Potential marker proteins were purified and identified by LC-MS/MS. In the validation set only one peak of 8.6 kDa out of ten in the screening set could be confirmed. This protein was identified to be ubiquitin and increased levels in CSF (but not in serum) of CJD patients were confirmed by Western blot. Ubiquitin allows the correct diagnoses of that CJD cases missed by tau protein or 14-3-3-protein. We conclude that ubiquitin is a promising additional CSF biomarker for diagnosis of CJD, especially in differential diagnostically difficult cases. The selective increase of ubiquitin in CSF of CJD patients might point to an involvement of ubiquitin in pathophysiological process.

Concentrations of beta-amyloid precursor protein processing products in cerebrospinal fluid of patients with amyotrophic lateral sclerosis and frontotemporal lobar degeneration.

Frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) are neurodegenerative disorders with heterogeneous clinical presentation but common neuropathological characteristics and pathophysiological substrates, which led to the view of ALS and FTLD representing two manifestations of a clinicopathological spectrum. For both diseases, changes in metabolism of beta-amyloid precursor protein (APP) are reported. In a pilot study, we analyzed cerebrospinal fluid from patients of the ALS-FTLD spectrum for APP processing products. ALS patients show elevated absolute levels of soluble APP and a shift towards the nonamyloidogenic APP processing pathway in contrast to patients with FTLD or ALS + FTLD. Changes in Abeta pattern could be described, allowing separation of patients with pure FTLD from ALS + FTLD. Combination of sAPP and Abeta values improves group differentiation. These findings may provide information on pathophysiological processes in the ALS-FTLD disease spectrum and could have impact in neurochemical diagnosis. We propose to expand this study to larger patient groups comprising followed up cases with known neuropathology.

TDP-43 in cerebrospinal fluid of patients with frontotemporal lobar degeneration and amyotrophic lateral sclerosis.

BACKGROUND: Recently, TAR DNA-binding protein 43 (TDP-43) was identified as the major component of ubiquitin-positive tau-negative neuronal and glial inclusions in the most common form of frontotemporal lobar degeneration (FTLD) and in amyotrophic lateral sclerosis (ALS). It was demonstrated that different TDP-43 profiles correspond to clinical phenotypes of FTLD or ALS subgroups, and the differential diagnostic potential of TDP-43 was suggested. OBJECTIVES: To examine TDP-43 in cerebrospinal fluid (CSF) and to analyze whether it could serve as a diagnostic marker. DESIGN: We characterized CSF TDP-43 by immunoblot using different TDP-43 antibodies and determined the relative TDP-43 levels in CSF samples from patients. SETTING: Academic research. PATIENTS: Twelve patients with FTLD, 15 patients with ALS, 9 patients with ALS plus FTLD, 3 patients with ALS plus additional signs of frontal disinhibition, and 13 control subjects. MAIN OUTCOME MEASURES: Results of TDP-43 immunoblot. RESULTS: Polyclonal TDP-43 antibodies recognized a 45-kDa band in all analyzed samples. Two monoclonal and N-terminus-specific antibodies did not detect any specific bands, but C-terminus-specific antibodies detected a 45-kDa band and additional bands at approximately 20 kDa in all CSF samples. Relative quantification of 45-kDa bands revealed significant differences among the diagnostic groups (P =.046). Specifically, patients with ALS (P =.03) and FTLD (P =.02) had higher TDP-43 levels than controls but with a prominent overlap of values. CONCLUSION: Although there is no evidence of pathologically altered TDP-43 proteins in CSF, TDP-43 levels in CSF might aid in characterizing subgroups of patients across the ALS and FTLD disease spectrum.