CSF amyloid ß38 as a novel diagnostic marker for dementia with Lewy bodies.

BACKGROUND: The clinical distinction between Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) is sometimes difficult, particularly in mild cases. Although CSF markers such as amyloid ß42 (Aß42) and P-tau can distinguish between AD and normal controls, their ability to distinguish between AD and DLB is not adequate. OBJECTIVE: This study aims to investigate whether CSF markers, in particular levels of Aß38, can differentiate between mild AD and DLB. METHODS: 85 individuals were included after standardised diagnostic procedures: 30 diagnosed as probable AD, 23 probable DLB, 20 probable Parkinson's disease dementia and 12 non-demented control subjects. CSF levels of Aß38, Aß40 and Aß42 were determined using commercially available ultra-sensitive multi-array kit assay (MSD) for human Aß peptides. Total tau (T-tau) and phosphorylated tau (P-tau) were analysed using ELISA (Innotest). In addition, combinations (Aß42/Aß38, Aß42/Aß40, Aß42/P-tau and Aß42/Aß38/P-tau) were assessed. RESULTS: Significant between group differences were found for all CSF measures, and all except Aß40, Aß42 and Aß42/P-tau differed between AD and DLB. The Aß42/Aß38 ratio was the measure that best discriminated between AD and DLB (AUC 0.765; p<0.005), with a sensitivity of 78% and a specificity of 67%. CONCLUSION: This study suggests that the level of Aß38 can potentially contribute in the diagnostic distinction between AD and DLB when combined with Aß42. Single measures had low diagnostic accuracy, suggesting that developing a panel of markers is the most promising strategy. Studies with independent and larger samples and a priori cut-offs are needed to test this hypothesis.

Identification of novel α-synuclein isoforms in human brain tissue by using an online nanoLC-ESI-FTICR-MS method.

Parkinson's disease (PD) and Dementia with Lewy bodies (DLB) are neurodegenerative diseases that are characterized by intra-neuronal inclusions of Lewy bodies in distinct brain regions. These inclusions consist mainly of aggregated α-synuclein (α-syn) protein. The present study used immunoprecipitation combined with nanoflow liquid chromatography (LC) coupled to high resolution electrospray ionization Fourier transform ion cyclotron resonance tandem mass spectrometry (ESI-FTICR-MS/MS) to determine known and novel isoforms of α-syn in brain tissue homogenates. N-terminally acetylated full-length α-syn (Ac-α-syn1₋140) and two N-terminally acetylated C-terminally truncated forms of α-syn (Ac-α-syn1₋139 and Ac-α-syn1₋103) were found. The different forms of α-syn were further studied by Western blotting in brain tissue homogenates from the temporal cortex Brodmann area 36 (BA36) and the dorsolateral prefrontal cortex BA9 derived from controls, patients with DLB and PD with dementia (PDD). Quantification of α-syn in each brain tissue fraction was performed using a novel enzyme-linked immunosorbent assay (ELISA).

[Biomarkers in spinal fluid of patients with dementia]. / Biomarkører i spinalvæske ved demens.

BACKGROUND: We wanted to assess whether biomarkers abeta42, tau and p-tau could differentiate between Alzheimer's disease and other dementia illnesses. MATERIAL AND METHODS: Following systematic Pubmed searches, 25 articles which reported sensitivity and specificity for Alzheimer's disease and other dementias were included. RESULTS: Most studies showed significant differences for all three markers between Alzheimer's disease and other dementia illnesses, except abeta42 which did not differ between Alzheimer's disease and dementia with Lewy bodies. Alzheimer's disease was distinguished from vascular dementia with sensitivities and specificities 77 % - 87 % and 62-80 % (abeta42); 79-100 % and 14-100 % (tau); and 78-80 % and 63-96 % (p-tau181). Alzheimer's disease and dementia with Lewy bodies were differentiated by tau and p-tau181 with sensitivities and specificities of 72-94 % and 53-92 %, and of 68-85 % and 61-85 %. Markers separated Alzheimer's disease from frontal lobe dementia with sensitivities and specificities of 37-91 % and 59-92 % (abeta42), 58-88 % and 68-92 % (tau) and 44-91 % and 79-100 % (p-tau181). INTERPRETATION: Methodological weaknesses impede the interpretation. CSF markers are not yet sufficient to differentiate between Alzheimer's disease and other forms of dementia.

CSF amyloid-beta and tau proteins, and cognitive performance, in early and untreated Parkinson's disease: the Norwegian ParkWest study.

BACKGROUND: Alzheimer's disease (AD) pathology is found in a considerable portion of patients with Parkinson's disease (PD), particularly those with early dementia (PDD). Altered cerebrospinal fluid (CSF) levels of amyloid-ß (Aß) and tau proteins have been found in PDD, with intermediate changes for Aß42 in non-demented PD. The authors investigated whether AD-related CSF protein levels are altered and relate to neuropsychological performance in early, untreated PD. METHODS: CSF concentrations of Aß42, Aß40 and Aß38 were measured by electrochemiluminiscene and levels of total tau (T-tau) and phosphorylated tau (P-tau) by ELISA in 109 newly diagnosed, unmedicated, non-demented, community-based PD patients who had undergone comprehensive neuropsychological testing, and were compared with those of 36 age-matched normal controls and 20 subjects with mild AD. RESULTS: PD patients displayed significant reductions in Aß42 (19%; p=0.009), Aß40 (15.5%; p=0.008) and Aß38 (23%; p=0.004) but not T-tau (p=0.816) or P-tau (p=0.531) compared with controls. CSF Aß42 reductions in PD were less marked than in AD (53%; p=0.002). Sequential regression analyses demonstrated significant associations between CSF levels of Aß42 (ß=0.205; p=0.019), Aß40 (ß=0.378; p<0.001) and Aß38 (ß=0.288; p=0.001) and memory impairment, but not executive-attentional or visuospatial dysfunction. Tau protein levels did not correlate with cognitive measures. CONCLUSION: CSF Aß levels are altered in a subset of patients with early PD and relate to memory impairment. Our study suggests that alterations in Aß protein metabolism may contribute to the heterogeneity in pattern and course of cognitive decline associated with PD. Longitudinal studies are needed to clarify the clinical significance of CSF Aß peptides as prognostic biomarkers in PD.

Glycan analysis of erythropoiesis-stimulating agents.

Erythropoiesis stimulating agents (ESAs) are a group of therapeutic glycoproteins used to treat anaemia caused by chronic kidney disease or chemotherapy. A variety of ESA products are available in the European Union, including innovator, biosimilar and second-generation medicines. Glycosylation is a critical quality attribute of ESA products, as it has a crucial influence upon in vivo biological activity. In this study, a combination of chromatography and mass spectrometry analysis has been used to characterise and compare the glycosylation profiles of five ESA products; Eprex® (epoetin alfa), NeoRecormon® (epoetin beta), Binocrit® (epoetin alfa biosimilar), Silapo (epoetin alfa biosimilar) and Aranesp® (darbepoetin alfa). The methods utilised include mixed-mode anion-exchange/hydrophilic interaction chromatography (AEX/HILIC-MS) for N-glycan identification and quantitation, and HILIC-MS for O-glycan characterisation. The products exhibit notable differences in N- and O-glycosylation, including attributes such as sialic acid occupation, O-acetylation, N-acetyllactosamine extended antennae and sulphated/penta-sialylated N-glycans, which have the potential to cause divergence of therapeutic potencies. The study highlights the need for continued monitoring of ESA product glycosylation, ideally allied to pharmacological data, in order to ensure consistency and therapeutic equivalence between products and enhance our understanding of ESA structure-activity-relationships.

CSF biomarkers and incipient Alzheimer disease in patients with mild cognitive impairment.

CONTEXT: Small single-center studies have shown that cerebrospinal fluid (CSF) biomarkers may be useful to identify incipient Alzheimer disease (AD) in patients with mild cognitive impairment (MCI), but large-scale multicenter studies have not been conducted. OBJECTIVE: To determine the diagnostic accuracy of CSF beta-amyloid(1-42) (Abeta42), total tau protein (T-tau), and tau phosphorylated at position threonine 181 (P-tau) for predicting incipient AD in patients with MCI. DESIGN, SETTING, AND PARTICIPANTS: The study had 2 parts: a cross-sectional study involving patients with AD and controls to identify cut points, followed by a prospective cohort study involving patients with MCI, conducted 1990-2007. A total of 750 individuals with MCI, 529 with AD, and 304 controls were recruited by 12 centers in Europe and the United States. Individuals with MCI were followed up for at least 2 years or until symptoms had progressed to clinical dementia. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive and negative likelihood ratios (LRs) of CSF Abeta42, T-tau, and P-tau for identifying incipient AD. RESULTS: During follow-up, 271 participants with MCI were diagnosed with AD and 59 with other dementias. The Abeta42 assay in particular had considerable intersite variability. Patients who developed AD had lower median Abeta42 (356; range, 96-1075 ng/L) and higher P-tau (81; range, 15-183 ng/L) and T-tau (582; range, 83-2174 ng/L) levels than MCI patients who did not develop AD during follow-up (579; range, 121-1420 ng/L for Abeta42; 53; range, 15-163 ng/L for P-tau; and 294; range, 31-2483 ng/L for T-tau, P < .001). The area under the receiver operating characteristic curve was 0.78 (95% confidence interval [CI], 0.75-0.82) for Abeta42, 0.76 (95% CI, 0.72-0.80) for P-tau, and 0.79 (95% CI, 0.76-0.83) for T-tau. Cut-offs with sensitivity set to 85% were defined in the AD and control groups and tested in the MCI group, where the combination of Abeta42/P-tau ratio and T-tau identified incipient AD with a sensitivity of 83% (95% CI, 78%-88%), specificity 72% (95% CI, 68%-76%), positive LR, 3.0 (95% CI, 2.5-3.4), and negative LR, 0.24 (95% CI, 0.21-0.28). The positive predictive value was 62% and the negative predictive value was 88%. CONCLUSIONS: This multicenter study found that CSF Abeta42, T-tau, and P-tau identify incipient AD with good accuracy, but less accurately than reported from single-center studies. Intersite assay variability highlights a need for standardization of analytical techniques and clinical procedures.

Neuropsychiatric correlates of cerebrospinal fluid biomarkers in Alzheimer's disease.

BACKGROUND: The aim of this study was to explore the relationship between cerebrospinal fluid biomarkers and neuropsychiatric symptoms in people with Alzheimer's disease. Psychosis, agitation, apathy and depression were assessed using standardised measures in 32 patients with mild Alzheimer's disease. METHODS: The levels of the 42-amino-acid form of beta-amyloid (A beta(1-42)), tau and p-tau (phosphorylated at threonine 181) were quantified using the conventional enzyme-linked immunosorbent assay method. RESULTS: Our result shows that apathy is significantly correlated with tau and p-tau but not with A beta(1-42). There were no significant correlations between indices of psychosis/agitation,or depression and cerebrospinal fluid A beta(1-42), tau or p-tau concentrations. CONCLUSION: Our finding suggests that apathy is associated with the level of neurofibrillary tangles in people with mild Alzheimer's disease. In contrast, the overall levels of neurofibrillary tangles or amyloid plaques do not seem to be associated with depression or psychosis, indicating that other brain changes contribute to these symptoms.

Inflammatory mediators in the frontal lobe of patients with mixed and vascular dementia.

Vascular dementia (VaD) accounts for about 20% of all dementias, and vascular risk is a key factor in more than 40% of people with Alzheimer's disease (AD). Little is known about inflammatory processes in the brains of these individuals. We have examined inflammatory mediators (interleukin (IL)-1beta, IL-1alpha, IL-6 and tumour necrosis factor alpha) and chemokines (macrophage inflammatory protein 1, monocyte chemo-attractant protein (MCP)-1 and granulocyte macrophage colony-stimulating factor) in brain homogenates from grey and white matter of the frontal cortex (Brodmann area 9) from patients with VaD (n = 11), those with concurrent VaD and AD (mixed dementia; n = 8) and from age-matched controls (n = 13) using ELISA assays. We found a dramatic reduction of MCP-1 levels in the grey matter in VaD and mixed dementia in comparison to controls (55 and 66%, respectively). IL-6 decreases were also observed in the grey matter of VaD and mixed dementia (72 and 71%, respectively), with a more modest decrease (30%) in the white matter of patients with VaD or mixed dementia. In the first study to examine the status of inflammatory mediators in a brain region severely affected by white-matter lesions, our findings highlight - in contrast to previous reports in AD - that patients at the later stage of VaD or mixed dementia have a significantly attenuated neuro-inflammatory response.

Loss of muscarinic M4 receptors in spinal cord of arthritic rats: implications for a role of M4 receptors in pain response.

Changes in the levels of muscarinic M4 receptors in spinal cord of acute and chronic arthritic rats (animal models of pain) were studied by receptor autoradiography using muscarinic M4 receptor subtype selective ligand. Arthritis was induced in female Lewis rats by single intradermal injection of heat-killed Mycobacterium butyricum and sacrificed 12 days (acute group) and 30 days (chronic and control groups) after induction of arthritis. Our results demonstrate significant reduction in the level of M4 receptors in the spinal cord (Rexed laminae I-X) of acute and chronic arthritic rats compared to controls. These findings suggest that the muscarinic M4 receptor subtype may be involved in cholinergic mechanisms of analgesia.

Loss of muscarinic M4 receptors in hippocampus of Alzheimer patients.

We assessed muscarinic M(1), M(2) and M(4) receptor subtypes in the hippocampus of Alzheimer's and control brains by receptor autoradiography using ligands such as [(125)I]muscarinic toxin-1 ([(125)I]MT-1, M(1) selective), [(3)H]AFDX-384 (M(2) partially selective) and [(125)I]muscarinic toxin 4 ([(125)I]M(4) toxin-1, M(4) selective). Our results revealed a significant decrease in muscarinic M(4) receptor binding in the dentate gyrus and CA4 regions of brain sections from Alzheimer's patients compared to controls. No changes in the density of M(1) or M(2) receptor binding were observed. Our findings suggest that, relative to other muscarinic receptor subtypes, the M(4) receptor could be the subtype which is selectively compromised in Alzeheimer's disease (AD).

Dynamin protein in stroke and vascular dementia.

Damage to sub-cortical white matter is a key substrate of vascular dementia (VaD) leading to deficits in executive function and cognitive processing speed. Dynamin1 is a 100 kDa protein, accounting for 0.4% of the total brain protein, and has a central role in many intracellular processes such as synaptic vesicle trafficking and recycling. In this study, we examined the status of Dynamin1 in the white matter from frontal cortex area. In order to measure the levels of Dynamin1, we isolated cortical white matter from a total of 34 post-mortem brains derived from controls (N=11), mixed Alzheimer's disease (AD) and VaD (N=8), VaD (N=7), and stroke no dementia (SND, N=8) subjects. A commercial ELISA kit was then used to determine the level of Dynamin1. In comparison to controls, Dynamin1 was elevated in patients SND (+400%) and reduced in patients with mixed VaD (-50%). Furthermore, levels of Dynamin1 were significantly associated with preserved cognition as indicated by the MMSE and CAMCOG and upregulation of vesicular glutamate transporter 1. This work indicates that Dynamin1 is associated with both preserved cognition and regenerative responses in older people with cerebrovascular disease and may represent a novel treatment target.

Cerebrospinal Fluid Levels of sAPPα and sAPPß in Lewy Body and Alzheimer's Disease: Clinical and Neurochemical Correlates.

We measured cerebrospinal fluid (CSF) levels of the soluble isoforms of amyloid precursor protein (APP; sAPPα sAPPß) and other CSF biomarkers in 107 patients with Alzheimer's disease (AD), dementia with Lewy body dementia (DLB), Parkinson's disease dementia (PDD), and normal controls (NC) using commercial kits. DLB and PDD were combined in a Lewy body dementia group (LBD). No differences were observed in sAPPα and sAPPß levels between the groups. Significant correlations were observed between sAPPα and sAPPß and between sAPPß and Mini-Mental State Examination scores in the total group analysis as well as when LBD and AD groups were analyzed separately. sAPPα and sAPPß levels correlated with Aß38, Aß40, Aß42, and Tau in the LBD group. In AD, sAPPα correlated with p-Tau and sAPPß with Aß40. The differential association between sAPPα and sAPPß with Aß and Tau species between LBD and AD groups suggests a possible relationship with the underlying pathologies in LBD and AD.

Temporal and region-dependent changes in muscarinic M4 receptors in the hippocampus and entorhinal cortex of adrenalectomized rats.

Long-term adrenalectomy induces a dramatic loss of cells in the dentate gyrus and CA1-CA4 fields of the hippocampus resulting in an impairment of cognitive functions such as spatial learning, memory and exploratory behaviour. Muscarinic M1 and M4 receptor levels in the hippocampus and entorhinal cortex of adult male Wistar rats were examined 3, 14, 30, 90, and 150 days after adrenalectomy. Receptor levels in the entorhinal cortex and the hippocampus were determined by quantitative autoradiography using 125I-M1-toxin-1 and 125I-M4-toxin-1, M1 and M4 subtype selective antagonists, respectively. Moreover, the level of hippocampal M1 and M4 muscarinic receptors were evaluated 1 month after adrenalectomy by immunoblot analysis. Adrenalectomy induced apoptotic processes were examined by analysing apoptotic markers using Western blot analysis. No significant changes were observed in the level of muscarinic M1 receptors in the entorhinal cortex, the dentate gyrus and in the different CA fields of the hippocampus of adrenalectomized (ADX) rats. However, M4 receptors showed a significant decrease in the entorhinal cortex (at 3 days), dentate gyrus and CA4 (at 14 days), CA3 (at 30 days), and CA2 and CA1 (at 90 days) after adrenalectomy. Moreover, a decrease in the level of M4 receptors was detected in ADX rats 1 month after adrenalectomy as compared with sham groups using M4 specific antibody. Apoptotic markers such as PARP and p53 were significantly increased whereas Bcl-2 marker was decreased in ADX rat brain homogenates compared to controls. Our results show that M1 and M4 receptors are differentially affected by adrenalectomy and indicate that these subtypes have different functions in the hippocampus. Our data on time and region-dependent decreases in hippocampal M4 receptors indicate that the M4 receptor subtype is influenced by adrenal hormones and suggest that the M4 receptor might be linked to memory function in the hippocampus.