Phosphorylated 14-3-3zeta protein in the CSF of neuroleptic-treated patients

High Diagnostic Accuracy of RT-QuIC Assay in a Prospective Study of Patients with Suspected sCJD

The early and accurate in vivo diagnosis of sporadic Creutzfeldt–Jakob disease (sCJD) is essential in order to differentiate CJD from treatable rapidly progressive dementias. Diagnostic investigations supportive of clinical CJD diagnosis include magnetic resonance imaging (MRI), electroencephalogram (EEG), 14-3-3 protein detection, and/or real-time quaking-induced conversion (RT-QuIC) assay positivity in the cerebrospinal fluid (CSF) or in other tissues. The total CSF tau protein concentration has also been used in a clinical setting for improving the CJD diagnostic sensitivity and specificity. We analyzed 182 CSF samples and 42 olfactory mucosa (OM) brushings from patients suspected of having sCJD with rapidly progressive dementia (RPD), in order to determine the diagnostic accuracy of 14-3-3, the total tau protein, and the RT-QuIC assay. A probable and definite sCJD diagnosis was assessed in 102 patients. The RT-QuIC assay on the CSF samples showed a 100% specificity and a 96% sensitivity, significantly higher compared with 14-3-3 (84% sensitivity and 46% specificity) and tau (85% sensitivity and 70% specificity); however, the combination of RT-QuIC testing of the CSF and OM samples resulted in 100% sensitivity and specificity, proving a significantly higher accuracy of RT-QuIC compared with the surrogate biomarkers in the diagnostic setting of patients with RPD. Moreover, we showed that CSF blood contamination or high protein levels might interfere with RT-QuIC seeding. In conclusion, we provided further evidence that the inclusion of an RT-QuIC assay of the CSF and OM in the diagnostic criteria for sCJD has radically changed the clinical approach towards the diagnosis.

Accuracy of diagnosis criteria in patients with suspected diagnosis of sporadic Creutzfeldt-Jakob disease and detection of 14-3-3 protein, France, 1992 to 2009

Diagnostic criteria of Creutzfeldt–Jakob disease (CJD), a rare and fatal transmissible nervous system disease with public health implications, are determined by clinical data, electroencephalogram (EEG), detection of 14-3-3 protein in cerebrospinal fluid (CSF), brain magnetic resonance imaging and prion protein gene examination. The specificity of protein 14-3-3 has been questioned. We reviewed data from 1,572 autopsied patients collected over an 18-year period (1992–2009) and assessed whether and how 14-3-3 detection impacted the diagnosis of sporadic CJD in France, and whether this led to the misdiagnosis of treatable disorders. 14-3-3 detection was introduced into diagnostic criteria for CJD in 1998. Diagnostic accuracy decreased from 92% for the 1992–1997 period to 85% for the 1998–2009 period. This was associated with positive detections of 14-3-3 in cases with negative EEG and alternative diagnosis at autopsy. Potentially treatable diseases were found in 163 patients (10.5%). This study confirms the usefulness of the recent modification of diagnosis criteria by the addition of the results of CSF real-time quaking-induced conversion, a method based on prion seed-induced misfolding and aggregation of recombinant prion protein substrate that has proven to be a highly specific test for diagnosis of sporadic CJD.

Advanced tests for early and accurate diagnosis of Creutzfeldt-Jakob disease

Early and accurate diagnosis of Creutzfeldt-Jakob disease (CJD) is a necessary to distinguish this untreatable disease from treatable rapidly progressive dementias, and to prevent iatrogenic transmission. Currently, definitive diagnosis of CJD requires detection of the abnormally folded, CJD-specific form of protease-resistant prion protein (PrP(CJD)) in brain tissue obtained postmortem or via biopsy; therefore, diagnosis of sporadic CJD in clinical practice is often challenging. Supporting investigations, including MRI, EEG and conventional analyses of cerebrospinal fluid (CSF) biomarkers, are helpful in the diagnostic work-up, but do not allow definitive diagnosis. Recently, novel ultrasensitive seeding assays, based on the amplified detection of PrP(CJD), have improved the diagnostic process; for example, real-time quaking-induced conversion (RT-QuIC) is a sensitive method to detect prion-seeding activity in brain homogenate from humans with any subtype of sporadic CJD. RT-QuIC can also be used for in vivo diagnosis of CJD: its diagnostic sensitivity in detecting PrP(CJD) in CSF samples is 96%, and its specificity is 100%. Recently, we provided evidence that RT-QuIC of olfactory mucosa brushings is a 97% sensitive and 100% specific for sporadic CJD. These assays provide a basis for definitive antemortem diagnosis of prion diseases and, in doing so, improve prospects for reducing the risk of prion transmission. Moreover, they can be used to evaluate outcome measures in therapeutic trials for these as yet untreatable infections.

Alternative application of Tau protein in Creutzfeldt-Jakob disease diagnosis: Improvement for weakly positive 14-3-3 protein in the laboratory

The 14-3-3 protein has been used as a biomarker for the diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD). However, weakly positive 14-3-3 leads to false positive results and an incorrect diagnosis. We attempted to use quantitative data for tau protein to provide an accurate diagnosis based on weak 14-3-3 protein. Sixty-two patients with sCJD, including pathologically confirmed, clinically definite, and probable cases, and 89 non-CJD patients were investigated based on a Korean population. Among them, 20 sCJD and 14 non-CJD showed weakly positive 14-3-3. The total tau (t-tau) and phosphorylated tau (p-tau) protein levels were measured by ELISA, and the p-tau to t-tau ratio (p/t ratio) was calculated. The combined use of the 14-3-3 protein assay, t-tau levels, and p/t ratio improved the specificity of diagnosis compared with the use of the 14-3-3 protein assay alone (47% for 14-3-3 alone; 85.94% for 14-3-3 combined with t-tau; 90.62% for 14-3-3 combined with the p/t ratio). In addition, 18 of 20 sCJD and 12 of 14 non-CJD who were weakly positive for 14-3-3 were positive for the p/t ratio and negative for the p/t ratio, respectively. When used in combination with the 14-3-3 protein, the tau protein is useful as a biomarker for the precise diagnosis of sCJD.

How many biomarkers to discriminate neurodegenerative dementia?

A number of cerebrospinal fluid (CSF) biomarkers are currently used for the diagnosis of dementia. Opposite changes in the level of amyloid-β(1-42) versus total tau and phosphorylated-tau181 in the CSF reflect the specific pathology of Alzheimer's disease (AD) in the brain. This panel of biomarkers has proven to be effective to differentiate AD from controls and from the major types of neurodegenerative dementia, and to evaluate the progression from mild cognitive impairment to AD. In the absence of specific biomarkers reflecting the pathologies of the other most common forms of dementia, such as Lewy Body disease, Frontotemporal lobar degeneration, Creutzfeldt-Jakob disease, etc., the evaluation of biomarkers of AD pathology is used, attempting to exclude rather than to confirm AD. Other biomarkers included in the common clinical practice do not clearly relate to the underlying pathology: progranulin (PGRN) is a selective marker of frontotemporal dementia with mutations in the PGRN gene; the 14-3-3 protein is a highly sensitive and specific marker for Creutzfeldt-Jakob disease, but has to be used carefully in differentiating rapid progressive dementia; and α-synuclein is an emerging candidate biomarker of the different forms of synucleinopathy. This review summarizes several biomarkers of neurodegenerative dementia validated based on the neuropathological processes occurring in brain tissue. Notwithstanding the paucity of pathologically validated biomarkers and their high analytical variability, the combinations of these biomarkers may well represent a key and more precise analytical and diagnostic tool in the complex plethora of degenerative dementia.

Complex proteinopathy with accumulations of prion protein, hyperphosphorylated tau, α-synuclein and ubiquitin in experimental bovine spongiform encephalopathy of monkeys

Proteins aggregate in several slowly progressive neurodegenerative diseases called 'proteinopathies'. Studies with cell cultures and transgenic mice overexpressing mutated proteins suggested that aggregates of one protein induced misfolding and aggregation of other proteins as well - a possible common mechanism for some neurodegenerative diseases. However, most proteinopathies are 'sporadic', without gene mutation or overexpression. Thus, proteinopathies in WT animals genetically close to humans might be informative. Squirrel monkeys infected with the classical bovine spongiform encephalopathy agent developed an encephalopathy resembling variant Creutzfeldt-Jakob disease with accumulations not only of abnormal prion protein (PrP(TSE)), but also three other proteins: hyperphosphorylated tau (p-tau), α-synuclein and ubiquitin; β-amyloid protein (Aβ) did not accumulate. Severity of brain lesions correlated with spongiform degeneration. No amyloid was detected. These results suggested that PrP(TSE) enhanced formation of p-tau and aggregation of α-synuclein and ubiquitin, but not Aβ, providing a new experimental model for neurodegenerative diseases associated with complex proteinopathies.

Cerebrospinal fluid markers in sporadic Creutzfeldt-Jakob disease

Sporadic Creutzfeldt-Jakob disease (sCJD) is the commonest form of human prion diseases, accounting for about 85% of all cases. Current criteria for intra vitam diagnosis include a distinct phenotype, periodic sharp and slow-wave complexes at electroencephalography (EEG), and a positive 14-3-3-protein assay in the cerebrospinal fluid (CSF). In sCJD, the disease phenotype may vary, depending upon the genotype at codon 129 of the prion protein gene (PRNP), a site of a common methionine/valine polymorphism, and two distinct conformers of the pathological prion protein. Based on the combination of these molecular determinants, six different sCJD subtypes are recognized, each with distinctive clinical and pathologic phenotypes. We analyzed CSF samples from 127 subjects with definite sCJD to assess the diagnostic value of 14-3-3 protein, total tau protein, phosphorylated₁₈₁ tau, and amyloid beta (Aβ) peptide 1-42, either alone or in combination. While the 14-3-3 assay and tau protein levels were the most sensitive indicators of sCJD, the highest sensitivity, specificity and positive predictive value were obtained when all the above markers were combined. The latter approach also allowed a reliable differential diagnosis with other neurodegenerative dementias.

Atypical prion protein conformation in familial prion disease with PRNP P105T mutation

Protease-resistant prion protein (PrP(Sc) ) is diagnostic of prion disease, yet its detection is frequently difficult. Here, we describe a patient with a PRNP P105T mutation and typical familial prion disease. Brain PrP(Sc) was undetectable by conventional Western blotting and barely detectable after phosphotungstate precipitation, where it displayed an atypical pattern suggestive of noncanonical conformation. Therefore, we used a novel misfolded protein assay (MPA) that detects PrP aggregates independently of their protease resistance. The MPA revealed the presence of aggregated PrP in similar amounts as in typical sporadic Creutzfeldt-Jakob disease. These findings suggest that measurements of PrP aggregation with the MPA may be potentially more sensitive than protease-based methodologies.

Detection of 14-3-3zeta in cerebrospinal fluid following experimentally evoked seizures

Surrogate and peripheral (bio)markers of neuronal injury may be of value in assessing effects of seizures on the brain or epilepsy development following trauma. The presence of 14-3-3 isoforms in cerebrospinal fluid (CSF) is a diagnostic indicator of Creutzfeldt-Jakob disease but these proteins may also be present following acute neurological insults. Here, we examined neuronal and 14-3-3 proteins in CSF from rats after seizures. Seizures induced by intra-amygdala microinjection of 0.1 microg kainic acid (KA) caused damage which was mainly restricted to the ipsilateral CA3 subfield of the hippocampus. 14-3-3zeta was detected at significant levels in CSF sampled 4 h after seizures compared with near absence in control CSF. Neuron-specific nuclear protein (NeuN) was also elevated in CSF in seizure rats. CSF 14-3-3zeta levels were significantly lower in rats treated with 0.01 microg KA. These data suggest the presence of 14-3-3zeta within CSF may be a biomarker of acute seizure damage.

Post-polio syndrome: clinical manifestations and cerebrospinal fluid markers

Post-polio syndrome (PPS) refers to a constellation of new neurological, musculoskeletal and general symptoms occurring in survivors of poliomyelitis decades after acute paralytic and nonparalytic disease. The common manifestations of PPS include generalized, central and peripheral fatigue, muscle weakness and musculoskeletal pain. The pathogenesis of PPS remains obscure. Three prevailing hypotheses have been advanced: stress-induced degeneration of surviving neurons, persistent poliovirus replication or virus reactivation and immune-mediated damage. The diagnosis of PPS is based on medical history and clinical examination, since no specific diagnostic tests are available. In the light of recent studies demonstrating a partial beneficial effect of intravenous immunoglobulin, this article will focus on cerebrospinal fluid biomarkers reflecting disease activity and pathogenic processes in PPS.

CNS 14-3-3zeta: changes with sex but not psychiatric diagnoses or psychotropic drug treatment

mRNA for 14-3-3zeta, an abundant signalling protein in human CNS, is reported as decreased or unchanged in cortex from subjects with schizophrenia. Addressing this dichotomy, using Western blot analyses, we measured levels of 14-3-3zeta proteins in cortex and caudate nucleus from subjects with schizophrenia, bipolar disorder, age/sex matched controls and in analogous CNS regions from rats treated with psychotropic drugs. Anti-14-3-3zeta antibody bound to three proteins (molecular weights: 27, 54 and 70 kDa), in all CNS tissue. Levels of all proteins did not vary with diagnoses (27 kDa: F(2,42.0)=0.35, p=0.71; 54 kDa: F(2,42.1)=0.62, p=0.54; 70 kDa: F(2,41.0)=2.43, p=0.10). By contrast, independent of diagnoses, there were significant increases in the levels of the 27 kDa protein (+32%; p<0.001) and 54 kDa protein (51%; p=0.001) in the caudate nucleus from males compared to females. In addition, there was a trend (-25%; p=0.06) to decreased levels of the 70 kDa protein in BA 9 in males compared to females. Treating with haloperidol, olanzapine, lithium or a combination thereof did not alter 14-3-3zeta levels in rat cortex or striatum. Therefore, this study suggests that 14-3-3zeta proteins are not altered in the cortex or caudate nucleus in schizophrenia, bipolar disorder or in analogous regions in psychotropic drug treated rats. By contrast, our study suggests that levels of 14-3-3zeta in some regions of the human CNS may be modulated by some sex-specific mechanism.

Structural basis for protein-protein interactions in the 14-3-3 protein family

The seven members of the human 14-3-3 protein family regulate a diverse range of cell signaling pathways by formation of protein-protein complexes with signaling proteins that contain phosphorylated Ser/Thr residues within specific sequence motifs. Previously, crystal structures of three 14-3-3 isoforms (zeta, sigma, and tau) have been reported, with structural data for two isoforms deposited in the Protein Data Bank (zeta and sigma). In this study, we provide structural detail for five 14-3-3 isoforms bound to ligands, providing structural coverage for all isoforms of a human protein family. A comparative structural analysis of the seven 14-3-3 proteins revealed specificity determinants for binding of phosphopeptides in a specific orientation, target domain interaction surfaces and flexible adaptation of 14-3-3 proteins through domain movements. Specifically, the structures of the beta isoform in its apo and peptide bound forms showed that its binding site can exhibit structural flexibility to facilitate binding of its protein and peptide partners. In addition, the complex of 14-3-3 beta with the exoenzyme S peptide displayed a secondary structural element in the 14-3-3 peptide binding groove. These results show that the 14-3-3 proteins are adaptable structures in which internal flexibility is likely to facilitate recognition and binding of their interaction partners.

Searching for markers of Creutzfeldt-Jakob disease in cerebrospinal fluid by two-dimensional mapping

Differential proteomic analysis has been performed on the cerebrospinal fluid (CSF) of six healthy and six patients suffering form sporadic Creutzfeldt-Jakob disease (sCJD), age- and sex-matched, after immuno-subtraction of albumin and immunoglobulins. These maps have revealed 28 polypeptide chains differentially modulated in the sCJD samples, of which 10 appeared to be up-regulated, the remaining 18 being down-regulated. Among those, 13 could be identified upon digestion and MALDI-TOF, MS analysis. In addition, the strong modulation of cystatin C was also confirmed by immunoblot analysis and the highly altered level of the 14-3-3 proteins that escaped detection by 2-D mapping, could be assessed by Western blots and immuno-detection of monomeric and homo- and hetero-dimeric 14-3-3 isotypes. In search for a panel of potential markers for sCJD, we highlight cystatin C, 14-3-3 proteins, transferrin, ubiquitin, Apoliprotein J and perhaps some of the still unidentified, but strongly modulated polypeptide chains detected in the differential map.