Cerebrospinal fluid catecholamines in Alzheimer's disease patients with and without biological disease

Noradrenergic and dopaminergic neurons are involved in cognitive functions, relate to behavioral and psychological symptoms in dementia and are affected in Alzheimer's disease (AD). Amyloid plaques (A), neurofibrillary tangles (T) and neurodegeneration (N) hallmarks the AD neuropathology. Today, the AT(N) pathophysiology can be assessed through biomarkers. Previous studies report cerebrospinal fluid (CSF) catecholamine concentrations in AD patients without biomarker refinement. We explored if CSF catecholamines relate to AD clinical presentation or neuropathology as reflected by CSF biomarkers. CSF catecholamines were analyzed in AD patients at the mild cognitive impairment (MCI; n = 54) or dementia stage (n = 240) and in cognitively unimpaired (n = 113). CSF biomarkers determined AT status and indicated synaptic damage (neurogranin). The AD patients (n = 294) had higher CSF noradrenaline and adrenaline concentrations, but lower dopamine concentrations compared to the cognitively unimpaired (n = 113). AD patients in the MCI and dementia stage of the disease had similar CSF catecholamine concentrations. In the CSF neurogranin positively associated with noradrenaline and adrenaline but not with dopamine. Adjusted regression analyses including AT status, CSF neurogranin, age, gender, and APOEε4 status verified the findings. In restricted analyses comparing A+T+ patients to A-T- cognitively unimpaired, the findings for CSF adrenaline remained significant (p < 0.001) but not for CSF noradrenaline (p = 0.07) and CSF dopamine (p = 0.33). There were no differences between A+T+ and A-T- cognitively unimpaired. Thus, we find alterations in CSF catecholamines in symptomatic AD and the CSF adrenergic transmitters to increase simultaneously with synaptic damage as indexed by CSF neurogranin

Towards a representative in vitro model for testing putative neuroprotective drugs in stroke : dissecting factors that govern the selectivity and time cource of OGD-induced damage

A stroke occurs when the blood flow to a brain region is disturbed causing oxygen and glucose deprivation (OGD) and the initiation of an ischemic signalling cascade leading to cell death. In industrialized countries stroke is the third leading cause of death and the leading cause of disability. The only approved treatment for stroke patients is administration of the thrombolytic tissue plasminogen activator (t-PA) to dissolve the clot and restore the blood flow. However, t-PA can be given only within ~3 hours after onset of the insult. Since the the discovery of the involvement of glutamate excitotoxicity in ischemic cell death, there has been extensive search for neuroprotective drugs in stroke. Many have proved neuroprotective in in vitro and in vivo models, but so far all of them have failed in clinical trials. Good in vitro and in vivo models for ischemia are a prerequiste both for improving the understanding of stroke pathology and for promoting drug development. This thesis focuses on an in vitro ischemia model based on organotypical hippocampal slice cultures exposed to OGD. The major aim was to optimize this model with regard to the important features of ischemic cell death seen in vivo and in stroke patients namely delayed development of cell death and selective vulnerability of the CA1 pyramidal cells of the hippocampus. We also wanted to use the improved slice culture protocol to test bumetanide (selective antagonist of the Na+/K+/Cl- co-transporter NKCC1) for cytoprotective effects after OGD in the hippocampus. We found that by subjecting the slice cultures to immediate onset hypoxia (resembling the abrupt interruption of the blood flow in vivo) in combination with an incubation buffer resembling the ionic concentration of the cerebral spinal fluid during a stroke, a delayed cell death pattern characterised by selectivity for the CA1 region was obtained. We also found that the vehicle ethanol potentiated OGD induced cell death which could be attenuated by administration of bumetanide. However, bumetanide failed to provide neuroprotection after OGD when compared to a control group not exposed to vehicle ethanol. NMDA induced excitotoxicity could be blocked by the NMDA receptor antagonist MK-801 but not by bumetanide. In conclusion the results indicate that the role of NKCC1 in ischemic cell death is not directly coupled to excitotoxic cell death signalling

Analyzing microglial-associated Aβ in Alzheimer’s disease transgenic mice with a novel mid-domain Aβ-antibody

The mechanisms of amyloid-β (Aβ)-degradation and clearance in Alzheimer’s disease (AD) pathogenesis have been relatively little studied. Short Aβ-fragments form by enzymatic cleavage and alternate amyloid-beta precursor protein (APP)-processing. Here we characterized a novel polyclonal Aβ-antibody raised against an Aβ mid-domain and used it to investigate microglial Aβ-uptake in situ by microscopy at the light- and ultrastructural levels. The rabbit Aβ-mid-domain antibody (ab338), raised against the mid-domain amino acids 21–34 (Aβ21–34), was characterized with biochemical and histological techniques. To identify the epitope in Aβ recognized by ab338, solid phase and solution binding data were compared with peptide folding scores as calculated with the Tango software. The ab338 antibody displayed high average affinity (KD: 6.2 × 10−10 M) and showed preference for C-terminal truncated Aβ-peptides ending at amino acid 34 and Aβ-mid domain peptides with high scores of β-turn structure. In transgenic APP-mouse brain, ab338 labelled amyloid plaques and detected Aβ-fragments in microglia at the ultra- and light microscopic levels. This reinforces a role of microglia/macrophages in Aβ-clearance in vivo. The ab338 antibody might be a valuable tool to study Aβ-clearance by microglial uptake and Aβ-mid-domain peptides generated by enzymatic degradation and alternate production

CSF sTREM2 in delirium—relation to Alzheimer’s disease CSF biomarkers Aβ42, t-tau and p-tau

Abstract Background Delirium and dementia share symptoms of cognitive dysfunctions, and mechanisms of neuroinflammation appear involved in both conditions. Triggering receptor expressed on myeloid cells 2 (TREM2) is linked to dementia and neurodegenerative disease. It encodes expression of an innate immune receptor in the brain expressed by microglia. The level of the soluble fragment of TREM2 (sTREM2) is reported to increase in the cerebrospinal fluid (CSF) already in prodromal and asymptomatic Alzheimer’s disease. Methods We analyzed the level of CSF sTREM2 in relation to delirium and dementia. The study included patients with or without pre-existing dementia who underwent acute hip fracture surgery (n = 120), and some of the patients developed delirium (n = 65). A medical delirium cohort (n = 26) was also examined. ELISA was used to determine the level of sTREM2 in CSF. Results Delirium was associated with a higher level of CSF sTREM2 only among those without pre-existing dementia (p = 0.046, n = 15, n = 44), particularly among patients developing delirium after CSF sampling (p = 0.02, n = 7, n = 44). Between patients with dementia, there was no group difference, but the CSF sTREM2 level increased with waiting time for surgery (r S = 0.39, p = 0.002, n = 60) and correlated well with the CSF Alzheimer’s disease biomarkers, Aβ42, and t-tau/p-tau (r S = 0.40, p = 0.002, r S = 0.46, p < 0.001/ r S = 0.49, p < 0.001, n = 60). Among patients with dementia, the level of Aβ38 and Aβ40 also correlated positively with sTREM2 in CSF (Aβ38MSD r S = 0.44, p = 0.001; Aβ40MSD r S = 0.48, p < 0.001; Aβ42MSD r S = 0.43, p < 0.001, n = 60). Conclusion The findings reinforce the involvement of neuroinflammation in delirium, yet with separate responses in patients with or without pre-existing dementia. Our findings support the concept of primed microglia in neurodegenerative disease and central immune activation after a peripheral trauma in such patients. A CSF biomarker panel of neuroinflammation might be valuable to prevent delirium by identifying patients at risk

Cerebrospinal fluid soluble TREM2 in aging and Alzheimer’s disease

Background Alzheimer’s disease (AD) neuropathology is associated with neuroinflammation, but there are few useful biomarkers. Mutant variants of triggering receptor expressed on myeloid cells 2 (TREM2) have recently been linked to late-onset AD and other neurodegenerative disorders. TREM2, a microglial receptor, is involved in innate immunity. A cleaved fragment, soluble TREM2 (sTREM2), is present in the cerebrospinal fluid (CSF). Methods We developed and used a novel enzyme-linked immunosorbent assay to investigate the potential value of CSF sTREM2 as an AD biomarker in two independent cohorts: an AD/mild cognitive impairment (MCI)/control cohort (n = 100) and an AD/control cohort (n = 50). Results We found no significant difference in sTREM2 levels between groups of controls and patients with AD or MCI. However, among all controls there was a positive correlation between sTREM2 and age (Spearman rho = 0.50; p < 0.001; n = 75). In the AD/MCI/control cohort, CSF sTREM2 correlated positively with total Tau (T-tau) (Spearman rho 0.57; p < 0.001; n = 50), phosphorylated Tau (P-tau) (Spearman rho 0.63; p < 0.001; n = 50) and amyloid-β1–42 (Aβ42) (Spearman rho 0.35; p = 0.01; n = 50) in control subjects. Among controls with a CSF Aβ42 above a cut-off value (700 pg/ml) in this cohort, the positive correlation between sTREM2 and Aβ42 was stronger (Spearman rho = 0.44; p = 0.002; n = 46). Conclusions sTREM2 in CSF correlates with aging in controls, and with the neurodegenerative markers CSF T-tau/P-tau among controls who are negative for AD CSF core biomarkers Aβ42, T-tau or P-tau

Fatty Acid-Binding Protein 3 in Cerebrospinal Fluid of Hip Fracture Patients with Delirium

Background: Delirium is associated with dementia and thus biomarkers reflecting neurodegeneration are of interest. Fatty acid-binding protein 3 (FABP3) is a cytoplasmic neuronal protein that has been isolated from the brain. It is released following brain injury and concentrations in cerebrospinal fluid (CSF) are also higher in neurodegenerative disorders such as Alzheimer’s disease (AD). Objective: To examine the relationship between CSF FABP3 concentration and delirium in hip fracture patients compared to a group of cognitively normal controls. Methods: CFS FABP3 concentration was measured in 128 hip fracture patients with (n = 71) and without (n = 57) delirium, and in cognitively unimpaired adults ≥64 years (n = 124) undergoing elective surgery. Results: CSF FABP3 (pg/ml) concentration (median (IQR)) was higher in hip-fracture patients compared to cognitively normal controls (5.7 (4.2–7.7) versus 4.5 (3.4–6.1), p &lt; 0.001). There was a significant weak correlation between age and CSF FABP3 (ρ= 0.3, p &lt; 0.001). After adjustment for age, the association between CSF FABP3 and hip-fracture was no longer statistically significant (β= 0.05, p = 0.5). There were no significant differences in CSF FABP3 concentration between hip fracture patients with (5.4 (4.1–8.2)) and without (5.8 (4.2–7.2)) delirium. CSF FABP3 concentration correlated positively with CSF AD biomarkers p-tau (ρ= 0.7, p &lt; 0.01) and t-tau (ρ= 0.7, p &lt; 0.01). Conclusion: CSF FABP3 concentrations were higher in hip fracture patients compared with cognitively normal older adults, indicating ongoing age-related neurodegeneration in these patients. There were no differences of CSF FABP3 concentrations across delirium groups, suggesting that neuronal damage or degeneration reflected by FABP3 may not be directly linked to delirium pathophysiology

Cerebrospinal fluid catecholamines in Alzheimer's disease patients with and without biological disease

Abstract Noradrenergic and dopaminergic neurons are involved in cognitive functions, relate to behavioral and psychological symptoms in dementia and are affected in Alzheimer’s disease (AD). Amyloid plaques (A), neurofibrillary tangles (T) and neurodegeneration (N) hallmarks the AD neuropathology. Today, the AT(N) pathophysiology can be assessed through biomarkers. Previous studies report cerebrospinal fluid (CSF) catecholamine concentrations in AD patients without biomarker refinement. We explored if CSF catecholamines relate to AD clinical presentation or neuropathology as reflected by CSF biomarkers. CSF catecholamines were analyzed in AD patients at the mild cognitive impairment (MCI; n  = 54) or dementia stage ( n  = 240) and in cognitively unimpaired ( n  = 113). CSF biomarkers determined AT status and indicated synaptic damage (neurogranin). The AD patients ( n  = 294) had higher CSF noradrenaline and adrenaline concentrations, but lower dopamine concentrations compared to the cognitively unimpaired ( n  = 113). AD patients in the MCI and dementia stage of the disease had similar CSF catecholamine concentrations. In the CSF neurogranin positively associated with noradrenaline and adrenaline but not with dopamine. Adjusted regression analyses including AT status, CSF neurogranin, age, gender, and APOEε4 status verified the findings. In restricted analyses comparing A+T+ patients to A−T− cognitively unimpaired, the findings for CSF adrenaline remained significant ( p  &lt; 0.001) but not for CSF noradrenaline ( p  = 0.07) and CSF dopamine ( p  = 0.33). There were no differences between A+T+ and A−T− cognitively unimpaired. Thus, we find alterations in CSF catecholamines in symptomatic AD and the CSF adrenergic transmitters to increase simultaneously with synaptic damage as indexed by CSF neurogranin

Cerebrospinal fluid sTREM2 in Alzheimer’s disease: comparisons between clinical presentation and AT classification

Triggering receptor expressed on myeloid cells 2 (TREM2) is an innate immune receptor expressed by microglia. Its cleaved fragments, soluble TREM2 (sTREM2), can be measured in the cerebrospinal fluid (CSF). Previous studies indicate higher CSF sTREM2 in symptomatic AD; however most of these studies have included biomarker positive AD cases and biomarker negative controls. The aim of the study was to explore potential differences in the CSF level of sTREM2 and factors associated with an increased sTREM2 level in patients diagnosed with mild cognitive impairment (MCI) or dementia due to AD compared with cognitively unimpaired controls as judged by clinical symptoms and biomarker category (AT). We included 299 memory clinic patients, 62 (20.7%) with AD-MCI and 237 (79.3%) with AD dementia, and 113 cognitively unimpaired controls. CSF measures of the core biomarkers were applied to determine AT status. CSF sTREM2 was analyzed by ELISA. Patients presented with comparable CSF sTREM2 levels as the cognitively unimpaired (9.6 ng/ml [SD 4.7] versus 8.8 ng/ml [SD 3.6], p = 0.27). We found that CSF sTREM2 associated with age-related neuroinflammation and tauopathy irrespectively of amyloid β, APOE ε4 status or gender. The findings were similar in both symptomatic and non-symptomatic individuals

Additional file 1: of Cerebrospinal fluid soluble TREM2 in aging and Alzheimer’s disease

Figure S1 showing ELISA validation; Figure S2 showing freeze–thaw cycles; Figure S3 showing PET imaging versus CSF Aβ42 in patients; Figure S4 showing a scatter plot of CSF sTREM2 in relation to CSF levels of Aβ38 MSD (A), Aβ40 MSD (B) and Aβ42 MSD (C) in the Norwegian AD/MCI/control cohort; Figure S5 showing a scatter plot of different CSF Aβ measures with Innotest® and MSD; Figure S6 showing a scatter plot of CSF sTREM2 in relation to levels of Aβ42 (A), T-tau (B) and P-tau (C) in CSF in the Swedish AD/control cohort; Figure S7 showing a surface plot of CSF sTREM2 in relation to age and Aβ38 MSD (A) and in relation to age and Aβ40 MSD (B) in controls; Table S1 presenting correlations between different CSF Aβ measures (Aβ42 Innotest®, Aβ38 MSD, Aβ40 MSD and Aβ42 MSD); and Table S2 presenting correlation analyses between different CSF sTREM2 and age and biomarkers (Aβ42 Innotest®, Aβ38 MSD, Aβ40 MSD and Aβ42 MSD, T-tau and P-tau). (PDF 647 kb