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Brain amyloid‐β (Aβ) deposits are key pathological hallmarks of both cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD). Microvascular deposits in CAA mainly consist of the Aβ40 peptide, whereas Aβ42 is the predominant variant in parenchymal plaques in AD. The relevance in pathogenesis and diagnostic accuracy of various other Aβ isoforms in CAA remain understudied. We aimed to investigate the biomarker potential of various Aβ isoforms in cerebrospinal fluid (CSF) to differentiate CAA from AD pathology. We included 25 patients with probable CAA, 50 subjects with a CSF profile indicative of AD pathology (AD‐like), and 23 age‐ and sex‐matched controls. CSF levels of Aβ1‐34, Aβ1‐37, Aβ1‐38, Aβ1‐39, Aβ1‐40, and Aβ1‐42 were quantified by liquid chromatography mass spectrometry. Lower CSF levels of all six Aβ peptides were observed in CAA patients compared with controls (p = 0.0005–0.03). Except for Aβ1‐42 (p = 1.0), all peptides were decreased in CAA compared with AD‐like subjects (p = 0.007–0.03). Besides Aβ1‐42, none of the Aβ peptides were decreased in AD‐like subjects compared with controls. All Aβ peptides combined differentiated CAA from AD‐like subjects better (area under the curve [AUC] 0.84) than individual peptide levels (AUC 0.51–0.75). Without Aβ1‐42 in the model (since decreased Aβ1‐42 served as AD‐like selection criterion), the AUC was 0.78 for distinguishing CAA from AD‐like subjects. CAA patients and AD‐like subjects showed distinct disease‐specific CSF Aβ profiles. Peptides shorter than Aβ1‐42 were decreased in CAA patients, but not AD‐like subjects, which could suggest different pathological mechanisms between vascular and parenchymal Aβ accumulation. This study supports the potential use of this panel of CSF Aβ peptides to indicate presence of CAA pathology with high accuracy. [ABSTRACT FROM AUTHOR]

Objective: Recent evidence shows that during slow‐wave sleep (SWS), the brain is cleared from potentially toxic metabolites, such as the amyloid‐beta protein. Poor sleep or elevated cortisol levels can worsen amyloid‐beta clearance, potentially leading to the formation of amyloid plaques, a neuropathological hallmark of Alzheimer disease. Here, we explored how nocturnal neural and endocrine activity affects amyloid‐beta fluctuations in the peripheral blood. Methods: We acquired simultaneous polysomnography and all‐night blood sampling in 60 healthy volunteers aged 20–68 years. Nocturnal plasma concentrations of amyloid‐beta‐40, amyloid‐beta‐42, cortisol, and growth hormone were assessed every 20 minutes. Amyloid‐beta fluctuations were modeled with sleep stages, (non)oscillatory power, and hormones as predictors while controlling for age and participant‐specific random effects. Results: Amyloid‐beta‐40 and amyloid‐beta‐42 levels correlated positively with growth hormone concentrations, SWS proportion, and slow‐wave (0.3–4Hz) oscillatory and high‐band (30–48Hz) nonoscillatory power, but negatively with cortisol concentrations and rapid eye movement sleep (REM) proportion measured 40–100 minutes previously (all t values > |3|, p values < 0.003). Older participants showed higher amyloid‐beta‐40 levels. Interpretation: Slow‐wave oscillations are associated with higher plasma amyloid‐beta levels, whereas REM sleep is related to decreased amyloid‐beta plasma levels, possibly representing changes in central amyloid‐beta production or clearance. Strong associations between cortisol, growth hormone, and amyloid‐beta presumably reflect the sleep‐regulating role of the corresponding releasing hormones. A positive association between age and amyloid‐beta‐40 may indicate that peripheral clearance becomes less efficient with age. ANN NEUROL 2024;96:46–60 [ABSTRACT FROM AUTHOR]

Succinic semialdehyde dehydrogenase deficiency (SSADHD) is a rare neurometabolic disorder caused by disruption of the gamma‐aminobutyric acid (GABA) pathway. A more detailed understanding of its pathophysiology, beyond the accumulation of GABA and gamma‐hydroxybutyric acid (GHB), will increase our understanding of the disease and may support novel therapy development. To this end, we compared biochemical body fluid profiles from SSADHD patients with controls using next‐generation metabolic screening (NGMS). Targeted analysis of NGMS data from cerebrospinal fluid (CSF) showed a moderate increase of aspartic acid, glutaric acid, glycolic acid, 4‐guanidinobutanoic acid, and 2‐hydroxyglutaric acid, and prominent elevations of GHB and 4,5‐dihydroxyhexanoic acid (4,5‐DHHA) in SSADHD samples. Remarkably, the intensities of 4,5‐DHHA and GHB showed a significant positive correlation in control CSF, but not in patient CSF. In an established zebrafish epilepsy model, 4,5‐DHHA showed increased mobility that may reflect limited epileptogenesis. Using untargeted metabolomics, we identified 12 features in CSF with high biomarker potential. These had comparable increased fold changes as GHB and 4,5‐DHHA. For 10 of these features, a similar increase was found in plasma, urine and/or mouse brain tissue for SSADHD compared to controls. One of these was identified as the novel biomarker 4,5‐dihydroxyheptanoic acid. The intensities of selected features in plasma and urine of SSADHD patients positively correlated with the clinical severity score of epilepsy and psychiatric symptoms of those patients, and also showed a high mutual correlation. Our findings provide new insights into the (neuro)metabolic disturbances in SSADHD and give leads for further research concerning SSADHD pathophysiology. [ABSTRACT FROM AUTHOR]

Background: Cerebrospinal fluid (CSF) platelet‐derived growth factor receptor‐β (PDGFRβ) has been proposed as a biomarker of blood–brain barrier (BBB) breakdown. We studied PDGFRβ levels as a biomarker for cerebral amyloid angiopathy (CAA), amnestic mild cognitive impairment (aMCI), or Alzheimer's disease (AD). Methods: CSF PDGFRβ levels were quantified by enzyme‐linked immunosorbent assay in patients with CAA, patients with aMCI/AD, and in matched controls. In aMCI/AD we evaluated CSF PDGFRβ both by clinical phenotype and by using the AT(N) biomarker classification system defined by CSF amyloid (A), tau (T), and neurodegeneration (N) biomarkers. Results: PDGFRβ levels were similar in CAA patients and controls (P =.78) and in aMCI/AD clinical phenotype and controls (P =.91). aMCI/AD patients with an AD+ biomarker profile (A+T+[N+]) had increased PDGFRβ levels compared to (A–T–[N–]) controls (P =.006). Conclusion: Our findings indicate that PDGFRβ levels are associated with an AD+ biomarker profile but are not a suitable biomarker for CAA or aMCI/AD clinical syndrome. [ABSTRACT FROM AUTHOR]

Aims: The aim of this work is to study the association of urokinase plasminogen activator (uPA) with development and progression of cerebral amyloid angiopathy (CAA). Materials and methods: We studied the expression of uPA mRNA by quantitative polymerase chain reaction (qPCR) and co‐localisation of uPA with amyloid‐β (Aβ) using immunohistochemistry in the cerebral vasculature of rTg‐DI rats compared with wild‐type (WT) rats and in a sporadic CAA (sCAA) patient and control subject using immunohistochemistry. Cerebrospinal fluid (CSF) uPA levels were measured in rTg‐DI and WT rats and in two separate cohorts of sCAA and Dutch‐type hereditary CAA (D‐CAA) patients and controls, using enzyme‐linked immunosorbent assays (ELISA). Results: The presence of uPA was clearly detected in the cerebral vasculature of rTg‐DI rats and an sCAA patient but not in WT rats or a non‐CAA human control. uPA expression was highly co‐localised with microvascular Aβ deposits. In rTg‐DI rats, uPA mRNA expression was highly elevated at 3 months of age (coinciding with the emergence of microvascular Aβ deposition) and sustained up to 12 months of age (with severe microvascular CAA deposition) compared with WT rats. CSF uPA levels were elevated in rTg‐DI rats compared with WT rats (p = 0.03), and in sCAA patients compared with controls (after adjustment for age of subjects, p = 0.05 and p = 0.03). No differences in CSF uPA levels were found between asymptomatic and symptomatic D‐CAA patients and their respective controls (after age‐adjustment, p = 0.09 and p = 0.44). Increased cerebrovascular expression of uPA in CAA correlates with increased quantities of CSF uPA in rTg‐DI rats and human CAA patients, suggesting that uPA could serve as a biomarker for CAA. [ABSTRACT FROM AUTHOR]

Background: Oftentimes, the search for novel (protein) biomarkers starts in transgenic animal models, to minimize inter‐individual variation and confounding influences. In our search for novel biomarkers for cerebral amyloid angiopathy (CAA), we have executed shotgun proteomics analyses aimed at identifying novel biomarker candidates on the cerebrospinal fluid (CSF) of rodent models for CAA type I, and compared relative expression of proteins with wild‐type controls. Additionally, we have attempted to validate these candidates by comparing selected biomarker levels in CSF of human sporadic CAA patients (sCAA) compared to Alzheimer's patients and control subjects. Method: A Bruker TIMS‐ToF‐MS/MS instrument was used to analyze CSF samples of rTg‐DI and wild‐type rodent samples, following trypsin digestion. Protein identification was inferred from the Uniprot unreviewed rodent database using Bruker Daltonics Data Analysis. Identified biomarker candidates were additionally researched in human CAA and Alzheimer's Dementia (AD) patients, and controls in CSF in independent validation attempts using targeted analyses including ELISA, or enzyme activity assays. Result: Differential expression levels in rodents were discovered for cathepsins B (CatB; p < 0.001 and p = 0.05) and S (CatS; p < 0.001 and p = 0.06), and hexosaminidase B (HexB; p = 0.003 and p = 0.17) for uncorrected and corrected results respectively. Human CatB and CatS CSF levels measured by ELISA did not differ significantly between CAA, AD patients or controls (p = 0.77 and p = 0.09). Analytical sensitivity of the CatB and CatS activity assays was too low to quantify activity in human CSF, whereas total hexosaminidase (as a measure of HexB activity) and HexA activity analyses in human CSF did show (a trend) in significant decreases in CAA patients compared to controls (p = 0.07 and p = 0.05 respectively). Conclusion: Biomarker candidates identified from untargeted protein screenings do not directly correspond to validation efforts in human biomarker studies. Increased HexB expression levels in rodents contrastingly appear to be reflected in decreased hexosaminidase activity in CSF in human CAA, but would need to be further validated in studies with greater power. This study was funded in the NIH CAFÉ project (5R01NS104147‐02). [ABSTRACT FROM AUTHOR]

Background: Cerebral amyloid angiopathy (CAA) is characterized by progressive vascular deposition of amyloid‐β (Aβ), and can cause cognitive decline in the elderly. Currently, the diagnosis of CAA is based on neuroimaging and includes the identification of lobar (micro‐)bleeds and cortical superficial siderosis. There is, however, a need for alternative methods as these neuroimaging methods are not optimal for detection of CAA during life. Moreover, CAA is strongly associated with the risk to develop edematous or hemorrhagic amyloid‐related imaging abnormalities (ARIA) as a consequence of anti‐Aβ immunotherapy (e.g. aducanumab and lecanemab) for Alzheimer's disease (AD). There is a need for biomarkers that can provide an accurate and early diagnosis of CAA, and additionally help in the identification of AD patients with a high burden of CAA, who are at risk of developing ARIA due to immunotherapy. We aimed to identify novel biomarker candidates for CAA in cerebrospinal fluid (CSF) using a targeted proteomics approach. Method: We analyzed a panel of 367 proteins in CSF samples of 34 CAA patients and 51 age‐ and sex‐matched controls using the Olink Explore multiplex immunoassay platform (Neurology panel; Olink, Uppsala, Sweden). Proteins were considered measurable when their levels were above the limit of detection of the assay in at least 70% of the samples. Result: For 15 of the 263 proteins that could be measured in CSF, we identified significantly different (p<0.05) levels in CSF of CAA patients as compared to controls. The strongest difference was observed for neurofilament light chain (NFL). Among these 15 proteins, there were two proteins (milk fat globule‐epidermal growth factor 8 (MFG‐E8/lactadherin) and urokinase‐type plasminogen activator (uPA)) for which we previously observed a significant changed level in CSF of CAA patients compared to controls 1,2. Conclusion: Confirmation of previously identified CAA biomarker candidates shows the validity and strength of our biomarker identification study using a targeted proteomics approach. The 15 candidates identified in our study, therefore, hold promise for development into biomarkers that may improve the detection of CAA. References: 1 Marazuela et al, Acta Neuropathol Commun. 2021;9(1):154. 2 Vervuurt et al, Neuropathol Appl Neurobiol. 2022;48(5):e12804. [ABSTRACT FROM AUTHOR]

Background: We have previously shown that matrix metalloproteinase 9 (MMP9) and tissue inhibitor of proteinases 3 (TIMP3) are specifically expressed in the vasculature of patients with cerebral amyloid angiopathy (CAA). Moreover, we have demonstrated increased MMP9 and decreased TIMP3 levels, as well as an altered MMP9:TIMP3 ratio in the vasculature of CAA patients that suffered from intracerebral haemorrhages (CAA‐ICH) compared to CAA patients without ICH (CAA‐nonICH). We now extended our studies to investigate whether TIMP4 may have a similar role in CAA, as this has not been studied before. Method: Using immunohistochemistry, we studied occipital lobe tissue of 44 controls (mean age 78.4 years; 50% female) and 58 CAA patients (77.5 years; 55% female; 40 CAA‐nonICH and 18 CAA‐ICH). Vascular TIMP4 staining was scored in a semiquantitative manner. Using ELISA, we measured TIMP4 CSF levels of 33 CAA patients (mean age 72.2 years; 47% female) and 35 controls (mean age 71.2 years; 51% female). For a subset of CSF samples (11 CAA samples and 14 controls), the levels of MMP2, MMP9, and MMP14 have been determined previously, and now their ratios to TIMP4 were calculated. Differences between CAA patients and controls were assessed using (ordinal) linear regression analysis. Result: In brain tissue, CAA cases had increased vascular TIMP4 expression when compared to controls (p = 0.00002, figure 1). TIMP4 expression did not differ between CAA‐nonICH and CAA‐ICH cases. In the absence of vascular TIMP4 staining, we often observed perivascular staining. Decreased levels of perivascular TIMP4 staining were observed in CAA‐ICH cases when compared to CAA‐nonICH cases (p = 0.045) and to controls (p = 0.035). CSF levels of TIMP4 were decreased in CAA patients compared to controls (p = 0.03, figure 2). In addition, the ratios of MMP2 (p = 0.038), MMP9 (p = 0.005), and MMP14 (p = 0.025) to TIMP4 were increased in CAA patients compared to controls. Conclusion: We demonstrated increased TIMP4 expression in vessel walls of CAA patients compared to controls. In contrast, TIMP4 CSF levels were decreased in CAA patients compared to controls, whereas MMP:TIMP4 ratios were increased, indicating a disbalance of MMP/TIMP4 levels in CAA pathophysiology. Funding: BIONIC project (no. 733050822, ZonMW) and CAFÉ project (no. 5R01NS104147‐02, NIH). [ABSTRACT FROM AUTHOR]

Reported prevalence estimates of sporadic cerebral amyloid angiopathy (CAA) vary widely. CAA is associated with cognitive dysfunction and intracerebral hemorrhage, and linked to immunotherapy-related side-effects in Alzheimer’s disease (AD). Given ongoing efforts to develop AD immunotherapy, accurate estimates of CAA prevalence are important. CAA can be diagnosed neuropathologically or during life using MRI markers including strictly lobar microbleeds. In this meta-analysis of 170 studies including over 73,000 subjects, we show that in patients with AD, CAA prevalence based on pathology (48%) is twice that based on presence of strictly lobar cerebral microbleeds (22%); in the general population this difference is three-fold (23% vs 7%). Both methods yield similar estimated prevalences of CAA in cognitively normal elderly (5% to 7%), in patients with intracerebral hemorrhage (19% to 24%), and in patients with lobar intracerebral hemorrhage (50% to 57%). However, we observed large heterogeneity among neuropathology and MRI protocols, which calls for standardized assessment and reporting of CAA. [ABSTRACT FROM AUTHOR]

Background: Spinocerebellar ataxia type 3 is a rare neurodegenerative disease caused by a CAG repeat expansion in the ataxin‐3 gene. Although no curative therapy is yet available, preclinical gene‐silencing approaches to reduce polyglutamine (polyQ) toxicity demonstrate promising results. In view of upcoming clinical trials, quantitative and easily accessible molecular markers are of critical importance as pharmacodynamic and particularly as target engagement markers. Objective: We aimed at developing an ultrasensitive immunoassay to measure specifically polyQ‐expanded ataxin‐3 in plasma and cerebrospinal fluid (CSF). Methods: Using the novel single molecule counting ataxin‐3 immunoassay, we analyzed cross‐sectional and longitudinal patient biomaterials. Results: Statistical analyses revealed a correlation with clinical parameters and a stability of polyQ‐expanded ataxin‐3 during conversion from the pre‐ataxic to the ataxic phases. Conclusions: The novel immunoassay is able to quantify polyQ‐expanded ataxin‐3 in plasma and CSF, whereas ataxin‐3 levels in plasma correlate with disease severity. Longitudinal analyses demonstrated a high stability of polyQ‐expanded ataxin‐3 over a short period. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Dendritic cells (DCs) are key regulators of the immune system that shape T cell responses. Regulation of T cell induction by DCs may occur via the intracellular enzyme indoleamine 2,3‐dioxygenase 1 (IDO), which catalyzes conversion of the essential amino acid tryptophan into kynurenine. Here, we examined the role of IDO in human peripheral blood plasmacytoid DCs (pDCs), and type 1 and type 2 conventional DCs (cDC1s and cDC2s). Our data demonstrate that under homeostatic conditions, IDO is selectively expressed by cDC1s. IFN‐γ or TLR ligation further increases IDO expression in cDC1s and induces modest expression of the enzyme in cDC2s, but not pDCs. IDO expressed by conventional DCs is functionally active as measured by kynurenine production. Furthermore, IDO activity in TLR‐stimulated cDC1s and cDC2s inhibits T cell proliferation in settings were DC‐T cell cell‐cell contact does not play a role. Selective inhibition of IDO1 with epacadostat, an inhibitor currently tested in clinical trials, rescued T cell proliferation without affecting DC maturation status or their ability to cross‐present soluble antigen. Our findings provide new insights into the functional specialization of human blood DC subsets and suggest a possible synergistic enhancement of therapeutic efficacy by combining DC‐based cancer vaccines with IDO inhibition. [ABSTRACT FROM AUTHOR]

Dopamine beta hydroxylase (DBH) deficiency is an extremely rare autosomal recessive disorder with severe orthostatic hypotension, that can be treated with L‐threo‐3,4‐dihydroxyphenylserine (L‐DOPS). We aimed to summarize clinical, biochemical, and genetic data of all world‐wide reported patients with DBH‐deficiency, and to present detailed new data on long‐term follow‐up of a relatively large Dutch cohort. We retrospectively describe 10 patients from a Dutch cohort and 15 additional patients from the literature. We identified 25 patients (15 females) from 20 families. Ten patients were diagnosed in the Netherlands. Duration of follow‐up of Dutch patients ranged from 1 to 21 years (median 13 years). All patients had severe orthostatic hypotension. Severely decreased or absent (nor)epinephrine, and increased dopamine plasma concentrations were found in 24/25 patients. Impaired kidney function and anemia were present in all Dutch patients, hypomagnesaemia in 5 out of 10. Clinically, all patients responded very well to L‐DOPS, with marked reduction of orthostatic complaints. However, orthostatic hypotension remained present, and kidney function, anemia, and hypomagnesaemia only partially improved. Plasma norepinephrine increased and became detectable, while epinephrine remained undetectable in most patients. We confirm the core clinical characteristics of DBH‐deficiency and the pathognomonic profile of catecholamines in body fluids. Impaired renal function, anemia, and hypomagnesaemia can be part of the clinical presentation. The subjective response to L‐DOPS treatment is excellent and sustained, although the neurotransmitter profile in plasma does not normalize completely. Furthermore, orthostatic hypotension as well as renal function, anemia, and hypomagnesaemia improve only partially. [ABSTRACT FROM AUTHOR]

Background: Genetic defects of monoamine neurotransmitters are rare neurological diseases amenable to treatment with variable response. They are major causes of early parkinsonism and other spectrum of movement disorders including dopa‐responsive dystonia. Objectives: The objective of this study was to conduct proteomic studies in cerebrospinal fluid (CSF) samples of patients with monoamine defects to detect biomarkers involved in pathophysiology, clinical phenotypes, and treatment response. Methods: A total of 90 patients from diverse centers of the International Working Group on Neurotransmitter Related Disorders were included in the study (37 untreated before CSF collection, 48 treated and 5 unknown at the collection time). Clinical and molecular metadata were related to the protein abundances in the CSF. Results: Concentrations of 4 proteins were significantly altered, detected by mass spectrometry, and confirmed by immunoassays. First, decreased levels of apolipoprotein D were found in severe cases of aromatic L‐amino acid decarboxylase deficiency. Second, low levels of apolipoprotein H were observed in patients with the severe phenotype of tyrosine hydroxylase deficiency, whereas increased concentrations of oligodendrocyte myelin glycoprotein were found in the same subset of patients with tyrosine hydroxylase deficiency. Third, decreased levels of collagen6A3 were observed in treated patients with tetrahydrobiopterin deficiency. Conclusion: This study with the largest cohort of patients with monoamine defects studied so far reports the proteomic characterization of CSF and identifies 4 novel biomarkers that bring new insights into the consequences of early dopaminergic deprivation in the developing brain. They open new possibilities to understand their role in the pathophysiology of these disorders, and they may serve as potential predictors of disease severity and therapies. © 2020 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Background: Alzheimer's disease is the most common form of dementia and mainly characterized by the accumulation the amyloid β (Aβ) peptide in the parenchyma and often around the blood vessels of the brain. The accumulation of Aβ in vessels walls is referred to as cerebral amyloid angiopathy (CAA). In a subset of AD cases CAA is observed in both capillaries and larger vessels which is designated as CAA type‐1. CAA type‐1 is associated with an increased neuroinflammatory response involving activated microglia and increased oxidative stress, which supposedly results in loss of blood‐brain barrier (BBB) integrity in CAA. Complement activation is an integral part of neuroinflammation associated with parenchymal Aβ deposits and CAA. However, a direct comparison of the complement activation in relation to plaque pathology and CAA type‐1 has not been made. Method: Using immunohistochemistry we performed a semi‐quantitative analysis on the expression and localization of complement factors C1q, C3, C4 and the membrane attack complex (MAC) in post mortem cortical brain tissue derived from AD cases with severe occurrence of CAA type‐1, AD cases without CAA and non‐demented control cases. In addition, label free quantitative mass spectrometry was applied to quantify complement components in whole cortical tissue lysates. Result: The complement factors C1q, C3 and C4 were found to be associated with CAA type‐1. No clear differences were observed in level of occurrence of C1q, C3 and C4 between AD cases with CAA type‐1, AD cases without CAA and non‐demented control cases. Interestingly, a subset of the AD cases with CAA type‐1 displayed MAC in affected vessels, whereas this was not observed in AD cases without CAA or control cases. Mass spectrometry analysis revealed an increase in C9, the primary component of MAC, in CAA type‐1 but not in AD without CAA. Conclusion: Early complement factors are present in all AD cases while the presence of MAC is restricted to a subset of CAA type‐1 cases, indicating full‐blown complement activation in CAA type‐1 but not in AD without CAA. [ABSTRACT FROM AUTHOR]

We thank Dr Kuhlenbäumer and colleagues for their interest in our recent study[1] in which we demonstrate that the cerebrospinal fluid (CSF) panel of the amyloid beta (A ) peptides 38, 40, 42, and 43 discriminates patients with sporadic cerebral amyloid angiopathy (sCAA) from patients with Alzheimer disease (AD) with high accuracy. However, we would like to point out that, despite using decreased CSF A 42 (in combination with increased phospho-tau and total tau) as a criterion for AD, CSF A 42 levels were lower in sCAA than in AD. The area under the curve (AUC) for the combination of CSF A 38, A 40, and A 43 is 0.92 (95% CI: 0.85-0.98), instead of the earlier reported AUC of 0.96 (95% confidence interval [CI] = 0.92-1.00). [Extracted from the article]

Background: Diagnosis of the highly prevalent disease cerebral amyloid angiopathy (CAA) is mainly based on radiological identification of cerebral micro‐ or macrobleeds (according to the diagnostically acclaimed Boston Criteria) in the end‐stage of disease. Body fluid biomarkers (e.g. in cerebrospinal fluid) could potentially act as alternatives and allow for earlier identification of disease in a minimally invasive manner. We have explored the involvement of potential CAA‐biomarker urokinase plasminogen activator (uPA) in CAA development and progression in human patients and rodent disease models (rTg‐DI). Additionally, we analyzed uPA cerebrospinal fluid (CSF) levels in rTg‐DI models and human CAA patients versus controls to assess diagnostic accuracy of uPA as a biomarker for CAA. Method: PLAU gene expression and uPA localization were studied in cerebrovascular tissue of a rTg‐DI models and wild‐type rats, alongside a human sporadic CAA patient and a control subject, using rt‐qPCR and immunohistochemistry respectively. Additionally, CSF Aβ40 and uPA levels were determined in rTg‐DI rats and in human patients with possible or probable CAA (according to the Boston Criteria; n=28), and control subjects (n=40), using ELISA. Result: Immunohistochemistry showed strong overexpression of uPA in brain tissue of rTg‐DI models and human CAA patients. Additionally, uPA showed a strong colocalization with Aβ peptides, restricted to the vasculature of rTg‐DI rats and human CAA patients. Expression and localization of both uPA and Aβ peptides were negligible in controls. Additionally, CAA rats displayed significant overexpression of the PLAU gene in brain vasculature as well as significant elevation of uPA in their CSF. In humans, CSF Aβ40 levels were reduced in CAA patients (7.66 ± 3.36 ng/mL) compared to controls (9.58 ± 3.88 ng/mL, p=0.04). CSF uPA levels were higher in CAA patients (median (IQR): 92.0 (76.1 ‐ 109.0) pg/mL compared to human controls (68.5 (56.6 ‐ 78.4) pg/mL; p<0.001). CSF Aβ40 and uPA combined yielded the highest AUC (0.87) to distinguish CAA from controls. Conclusion: uPA was overexpressed in rTg‐DI rats and its levels were significantly elevated in both rodent and human CAA. CSF Aβ40 and uPA serve as excellent biomarkers to discriminate CAA from controls, especially when combined. [ABSTRACT FROM AUTHOR]

Timely diagnosis is essential for patients with neurometabolic disorders to enable targeted treatment. Next‐Generation Metabolic Screening (NGMS) allows for simultaneous screening of multiple diseases and yields a holistic view of disturbed metabolic pathways. We applied this technique to define a cerebrospinal fluid (CSF) reference metabolome and validated our approach with patients with known neurometabolic disorders. Samples were measured using ultra‐high‐performance liquid chromatography‐quadrupole time‐of‐flight mass spectrometry followed by (un)targeted analysis. For the reference metabolome, CSF samples from patients with normal general chemistry results and no neurometabolic diagnosis were selected and grouped based on sex and age (0‐2/2‐5/5‐10/10‐15 years). We checked the levels of known biomarkers in CSF from seven patients with five different neurometabolic disorders to confirm the suitability of our method for diagnosis. Untargeted analysis of 87 control CSF samples yielded 8036 features for semiquantitative analysis. No sex differences were found, but 1782 features (22%) were different between age groups (q < 0.05). We identified 206 diagnostic metabolites in targeted analysis. In a subset of 20 high‐intensity metabolites and 10 biomarkers, 17 (57%) were age‐dependent. For each neurometabolic patient, ≥1 specific biomarker(s) could be identified in CSF, thus confirming the diagnosis. In two cases, age‐matching was essential for correct interpretation of the metabolomic profile. In conclusion, NGMS in CSF is a powerful tool in defining a diagnosis for neurometabolic disorders. Using our database with many (age‐dependent) features in CSF, our untargeted approach will facilitate biomarker discovery and further understanding of mechanisms of neurometabolic disorders. [ABSTRACT FROM AUTHOR]

Introduction: Within‐person trajectories of cerebrospinal fluid (CSF) biomarkers in Alzheimer's disease (AD) are not well defined. Methods: We included 467 subjects from the BIOMARKAPD study with at least two serial CSF samples. Diagnoses were subjective cognitive decline (n = 75), mild cognitive impairment (n = 128), and AD dementia (n = 110), and a group of cognitively unimpaired subjects (n = 154) were also included. We measured baseline and follow‐up CSF levels of total tau (t‐tau), phosphorylated tau (p‐tau), YKL‐40, and neurofilament light (NfL). Median CSF sampling interval was 2.1 years. Results: CSF levels of t‐tau, p‐tau, NfL, and YKL‐40 were 2% higher per each year of baseline age in controls (P <.001). In AD, t‐tau levels were 1% lower (P <.001) and p‐tau levels did not change per each year of baseline age. Longitudinally, only NfL (P <.001) and YKL‐40 (P <.02) increased during the study period. Discussion: All four CSF biomarkers increase with age, but this effect deviates in AD for t‐tau and p‐tau. [ABSTRACT FROM AUTHOR]

A reliable biomarker is needed for accurate and early differentiation between Parkinson disease and the various forms of atypical parkinsonism. We used a novel real-time quaking-induced conversion (RT-QuIC) assay to detect α-synuclein (α-syn) aggregates in cerebrospinal fluid (CSF) of 118 patients with parkinsonism of uncertain clinical etiology and 52 controls. Diagnostic accuracy to distinguish α-synucleinopathies from non-α-synucleinopathies and controls was 84% (sensitivity = 75%, specificity = 94%, area under the curve = 0.84, 95% confidence interval = 0.78-0.91, p < 0.0001, positive predictive value = 93%). CSF α-syn RT-QuIC could be a useful diagnostic tool to help clinicians differentiate α-synucleinopathies from other forms of parkinsonism when the clinical picture is uncertain. Ann Neurol 2019;85:777-781. [ABSTRACT FROM AUTHOR]

Introduction: Cerebrospinal fluid (CSF) biomarkers have the potential to improve the diagnostic accuracy of Alzheimer's disease, yet there is a lack of harmonized preanalytical CSF handling protocols. Methods: This systematic review summarizes the current literature on the influence of preanalytical variables on CSF biomarker concentration. We evaluated the evidence for three core CSF biomarkers: β‐amyloid 42, total tau, and phosphorylated tau. Results: The clinically important variables with the largest amount of conflicting data included the temperature at which samples are stored, the time nonfrozen samples can be stored, and possible effects of additives such as detergents, blood contamination, and centrifugation. Conversely, we discovered that there is consensus that tube material has a significant effect. Discussion: A unified CSF handling protocol is recommended to reduce preanalytical variability and facilitate comparison of CSF biomarkers across studies and laboratories. In future, experiments should use a gold standard with fresh CSF collected in low binding tubes. [ABSTRACT FROM AUTHOR]

Cerebrospinal fluid ( CSF) has been extensively studied to explore biochemical alterations in subjects with neurodegenerative disorders. In Alzheimer's disease, levels of increased CSF tau protein and decreased levels of β-amyloid 1-42 (Aβ42) have been shown to correlate with brain plaque formation and tangle pathology. Intracellular Lewy inclusions containing aggregated α-synuclein (α-syn) represent a pathological hallmark of Parkinson's disease ( PD). In most - but not all - studies published to date total CSF α-syn concentrations have been found to be decreased in disorders related to α-syn pathology, that is, PD, dementia with Lewy bodies and multiple system atrophy. However, these reports show extensive signal overlap among tested individuals, thereby diminishing its potential for routine use in clinical practice. To investigate potential biological (i.e., non-technical) confounders of reported CSF levels for α-syn, Aβ42, and tau in PD and related disorders, we carried out a methodical review of known factors that underlie signal variability and speculate on those that have not yet been tested. We discuss several biological factors, such as neuropathology, demographics, clinical phenotype, progression and duration of disease, concomitant illnesses and, last but not least, pharmacotherapy, which in isolation or combination can substantially alter values for CSF proteins of interest. Enhanced implementation of standardized clinical protocols, streamlined operating procedures, and further progress in the development of validated assays for CSF proteins have the potential to (i) inform us as to the pathogenesis of disease, (ii) support the laboratory-based diagnosis for symptomatic subjects in the future, and (iii) facilitate breakthrough therapies to alter the course of neurodegenerative disorders, such as PD and Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Background: Cerebral amyloid angiopathy (CAA) is a major cause of intracerebral hemorrhages and contributes to cognitive decline. The currently applied modified Boston criteria fall short in detecting early‐stage disease and biomarkers to track disease progression are lacking. In the CAA Fluid Biomarker Evaluation (CAFE) study we aim to identify novel CAA‐specific biomarkers. We hypothesize that levels of metabolites in cerebrospinal fluid (CSF) are altered due to amyloid‐β deposits. Method: High‐resolution liquid chromatography quadrupole time‐of‐flight mass spectrometry was used to analyze metabolite levels in an untargeted fashion (Coene et al., 2018; Peters et al., 2020) in CSF derived from small‐vessel CAA transgenic (rTg‐DI) and wild‐type (WT) rats. Candidate features identified in a discovery study (n=8 WT; n=10 rTg; 6 months old) were validated in larger groups of rats including various ages (n=30 WT; n=29 rTg; 3‐6‐12 months old). Features were annotated based on accurate mass, specific retention time and semi‐quantitative intensity by comparison with reference standard compounds and online database matching. Result: Of the 48 significantly different features discovered in the pilot, 27 could be validated in the second study. Several features corresponded with reference compounds of metabolites involved in the purine metabolism pathway, which included guanosine, guanine, inosine, xanthine and hypoxanthine. All these levels were significantly decreased in all groups of the rTg rats compared to WT, some progressing with older age (Figure 1). An additional n=605 features were identified with significantly different levels between the various groups. Molecular formulas for other possible interesting features could be computed, whose metabolite identities are currently being confirmed by using standard compounds. Conclusion: Metabolomics analyses of the CSF of transgenic rats shows promise in discovering novel potential biomarkers for CAA. Using a robust animal model allows us to study biomarkers along the trajectory of disease progression. Our results suggest a global down‐regulation of the purine pathway (Figure 2), a finding previously observed in early‐stage Alzheimer’s disease (Alonso‐Andrés et al., 2017). [ABSTRACT FROM AUTHOR]

Analytical validation of a biomarker assay is essential before implementation in clinical practice can occur. In this study, we analytically validated the performance of assays detecting soluble amyloid-β precursor protein (sAPP) α and β in CSF in two laboratories according to previously standard operating procedures serving this goal. sAPPα and sAPPβ ELISA assays from two vendors (IBL-international, Meso Scale Diagnostics) were validated. The performance parameters included precision, sensitivity, dilutional linearity, recovery, and parallelism. Inter-laboratory variation, biomarker comparison (sAPPα vs. sAPPβ) and clinical performance was determined in three laboratories using 60 samples of patients with subjective memory complaints, Alzheimer's disease, or frontotemporal dementia. All performance parameters of the assays were similar between labs and within predefined acceptance criteria. The only exceptions were minor out-of-range results for recovery at low concentrations and, despite being within predefined acceptance criteria, non-comparability of the results for evaluation of the dilutional linearity and hook-effect. Based on the inter-laboratory correlation between Lab #1 and Lab #2, the IBL-international assays were more robust (sAPPα: r2 = 0.92, sAPPβ: r2 = 0.94) than the Meso Scale Diagnostics (MSD) assay (sAPPα: r2 = 0.70, sAPPβ: r2 = 0.80). Specificity of assays was confirmed using assay-specific peptide competitors. Clinical validation showed consistent results across the clinical groups in the different laboratories for all assays. The validated sAPP assays appear to be of sufficient technical quality and perform well. Moreover, the study shows that the newly developed standard operating procedures provide highly useful tools for the validation of new biomarker assays. A recommendation was made for renewed instructions to evaluate the dilutional linearity and hook-effect. [ABSTRACT FROM AUTHOR]

Amyloid-β (Aβ) is the most prominent protein in Alzheimer's disease ( AD) senile plaques. In addition, Aβ interacts with a variety of Aβ-associated proteins (AAPs), some of which can form complexes with Aβ and influence its clearance, aggregation or toxicity. Identification of novel AAPs may shed new light on the pathophysiology of AD and the metabolic fate of Aβ. In this study, we aimed to identify new AAPs by searching for proteins that may form soluble complexes with Aβ in CSF, using a proteomics approach. We identified the secreted Wnt pathway protein Dickkopf-related protein 3 (Dkk-3) as a potential Aβ-associated protein. Using immunohistochemistry on human AD brain tissue, we observed that (i) Dkk-3 co-localizes with Aβ in the brain, both in diffuse and classic plaques. (ii) Dkk-3 is expressed in neurons and in blood vessel walls in the brain and (iii) is secreted by leptomeningeal smooth muscle cells in vitro. Finally, measurements using ELISA revealed that (iv) Dkk-3 protein is abundantly present in both cerebrospinal fluid and serum, but its levels are similar in non-demented controls and patients with AD, Lewy body dementia, and frontotemporal dementia. Our study demonstrates that Dkk-3 is a hitherto unidentified Aβ-associated protein which, given its relatively high cerebral concentrations and co-localization with Aβ, is potentially involved in AD pathology. [ABSTRACT FROM AUTHOR]

Saffold cardiovirus, a newly discovered human cardiovirus, has close similarity with Theiler's murine encephalomyelitis virus ( TMEV) which can cause a chronic demyelinating encephalomyelitis in mice. In this study, we tested whether Saffold cardiovirus infection of the brain is associated with multiple sclerosis ( MS). Autopsy white matter samples from 19 MS and 9 normal brain donors were tested by polymerase chain reaction. All were negative. Paired cerebrospinal fluid and serum samples from 24 MS patients and 27 controls were tested for Saffold cardiovirus-specific oligoclonal bands, two patients and two controls reacted positive. We conclude that an association between Saffold cardiovirus and MS is highly improbable. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Movement disorders are a prominent feature of glucose transporter-1 (GLUT1) deficiency syndrome (GLUT1DS). First-choice treatment is a ketogenic diet, but compliance is poor. We have investigated the effect of the modified Atkins diet as an alternative treatment for movement disorders in GLUT1DS. Methods Four patients with GLUT1DS ages 15 to 30 years who had movement disorders as the most prominent feature were prospectively evaluated after initiation of the modified Atkins diet. Movement disorders included dystonia, ataxia, myoclonus, and spasticity, either continuous or paroxysmal, triggered by action or exercise. Duration of treatment ranged from 3 months to 16 months. Results All patients reached mild to moderate ketosis and experienced remarkable improvement in the frequency and severity of paroxysmal movement disorders. Cognitive function also improved subjectively. Conclusions The modified Atkins diet is an effective and feasible alternative to the ketogenic diet for the treatment of GLUT1DS-related paroxysmal movement disorders in adolescence and adulthood. © 2013 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Background: Current diagnostic criteria for cerebral amyloid angiopathy (CAA) are predominantly based on radiological identification of evidence of CAA (micro‐ or macrobleeds). These criteria present only end‐stage manifestations of the disease, however. The development of transgenic rat models for CAA, carrying the E693Q/D694N mutations in APP (rTg‐DI rats), has the potential of discovery of novel biomarkers for CAA. Shotgun proteomics analysis of rTg‐DI tissue, compared to wild‐type rats has yielded elevated levels of urokinase plasminogen activator (uPA) in CAA. uPA is a serine protease active in the conversion of plasminogen to plasmin, a fibrinolytic factor. We investigated the potential of uPA in a pilot biomarker discovery study for the diagnosis of CAA by analyzing uPA concentrations in cerebrospinal fluid (CSF) of patients with CAA compared to control patients. Method: CSF was obtained from patients with possible or probable CAA (according to the current diagnostic imaging tool, the Boston Criteria) (n=28), and control subjects (n=42). uPA levels in CSF were determined using a uPA Quantikine ELISA (R&D Systems, Minneapolis, USA). Total protein levels were assayed using a Pierce® BCA Protein Assay (Thermo Fisher, Waltham, USA). Associations of uPA with known concentrations of other neurological markers, including aβ peptides and tau proteins were also analysed. Result: The concentration of uPA was significantly increased in the CSF of CAA patients compared to controls (303 ± 23.2 vs. 227 ± 12.5 pg/mL; p=0.001). CSF uPA levels (very) weakly correlated with age at lumbar puncture (rSP=0.33, p=0.005) and total protein content (rSP=0.24, p=0.042). uPA levels in controls were correlated in a weak‐to‐moderate extent with Aβ‐38, 40, 42, and total‐ and phosphorylated tau protein (rSP=0.46, 0.63, 0.47, 0.53 and 0.41 respectively, p<0.02), whereas this correlation was practically absent in the CAA group. Conclusion: Comparison of CSF levels of uPA shows a significant elevation in CAA patients compared against controls. CAA patients show lower levels of correlation of uPA with circulating aβ peptides and tau protein variants as compared to controls. This reinforces the potential of uPA as an effective biomarker in the diagnosis of CAA patients and incentivizes further research into this biomarker. [ABSTRACT FROM AUTHOR]

Background: Neuro‐inflammation is an important mechanism that occurs during the early stages of AD, and this can be studied indirectly via the CSF. Neuroleukin (NLK) can serve as an interesting new inflammatory marker. NLK is a lymphokine product of lectin‐stimulated T‐cells and induces immunoglobulin secretion by human mononuclear cells.1 Moreover, it can serve as a neurotrophic factor for spinal and sensory neurons. Furthermore, It has previously been shown that neuroleukin is expressed in neurons, microglia, oligodendroglia, and in cerebrovascular cells such as smooth muscle cells. In addition, expression of neuroleukin was found in senile plaques and in Aβ‐laden vessels.2 Thus, the aim of our study was to investigate the diagnostic and discriminative value of NLK cerebrospinal fluid (CSF) in patients at various clinical stages of Alzheimer's disease (AD) and in patients with cerebral amyloid angiopathy (CAA). Method: CSF NLK were quantified by ELISA. Cohorts of controls (n=47), patients with AD (n=59; consisting of 19 patients with mild cognitive impairment (clinical dementia rating (CDR) = 0.5), 28 patients with CDR 1.0 and 12 patients with a CDR of ≥ 2.0.) and patients with CAA (n=28) were used to evaluate the diagnostic value of CSF NLK levels. Result: We found that NLK levels were significantly elevated in the CSF of AD patients (4.64 ng/ml (IQR: 3.69‐5.57) compared to controls (3.29 ng/ml (IQR: 2.39‐3.94); p<0.0001) and levels were also significantly elevated in patients with mild cognitive impairment. In CAA patients, NLK was not elevated (3.39 ng/ml, IQR 2.94‐4.17). NLK correlated with total tau levels (rSP = 0.653, p < 0.0001), phosphorylated tau levels (rSP = 0.604 p < 0.0001) and to a lesser extent with amyloid β42 levels (rSP = ‐0.294, p < 0.0001). Conclusion: Our findings indicate that CSF NLK levels are elevated in AD patients compared to controls and support an increased neuroinflammatory state in the various stages of AD. In addition, NLK appears to be associated with neurodegeneration as measured by total tau and phosphorylated tau. References: 1. Chaput et al. Nature, 1988. 332(6163): p. 454‐455, 2. Rensink et al. Neuropathology and Applied Neurobiology, 2004. 30(3): p. 279. [ABSTRACT FROM AUTHOR]

Background: Cerebral amyloid angiopathy (CAA) is a major cause of intracerebral hemorrhages and contributes to cognitive decline. Probable diagnosis is currently determined using the modified Boston criteria. However, these in vivo imaging correlates only represent late‐stage disease manifestations, are unable to set definitive CAA diagnosis, and do not reflect disease progression or track severity. Thus there is an unmet need for an early‐stage CAA biomarker to bypass these limitations. Next to vascular amyloid‐ß accumulation and increased neuroinflammation, metabolite levels may also be altered due to changes induced by amyloid‐ß deposits. Method: In the Cerebral Amyloid Angiopathy Fluid Biomarker Evaluation (CAFE) study, we aim to discover and validate new CAA‐specific biofluid markers. By using a transgenic rat model for small‐vessel CAA, the rTg‐DI model, we are able to study a genetically homogenous group, housed in an environment equal to wild‐type rats. An unbiased combined liquid chromatography‐mass spectrometry protocol to analyze cerebrospinal fluid (CSF) from these rats will be generated and optimized. With the obtained distinct metabolite profiles, we aim to identify novel CAA‐associated metabolite biomarkers. Result: Next‐generation metabolic screening (NGMS) is our newly developed methodology to study the metabolome, using high‐resolution liquid chromatography quadrupole time‐of‐flight mass spectrometry. This high‐throughput unbiased NGMS approach enables us to detect >10,000 different features in one plasma sample, defined by their unique combination of accurate mass, specific retention time and intensity. In human CSF, 206 metabolites were annotated using the Human Metabolome Database. Application to rodent models requires only 25µL of CSF for analysis. Currently, we are analyzing CSF from 6‐months old rTg‐DI rats compared to age‐matched wild‐type rats (each n=10); the results will be presented during the conference. Conclusion: We expect that our powerful innovative technology for untargeted and simultaneous analysis of a large number of metabolites in body fluids will be promising in discovering novel potential biomarkers for CAA. Using a robust animal model allows us to study biomarkers along the trajectory of disease progression. Furthermore, it will gain more insight in underlying processes and metabolic pathways that are involved in the pathophysiology of CAA. After the initial discovery phase, candidate markers will be validated in patient cohorts. [ABSTRACT FROM AUTHOR]

Background: There is large variation in estimates of the prevalence of cerebral amyloid angiopathy (CAA). CAA is associated with an increased risk of cognitive dysfunction and intracerebral hemorrhages, and it is tightly linked to immunotherapy‐related side‐effects in Alzheimer's disease (AD). Thus, accurate estimates of the prevalence of CAA are important. CAA can be diagnosed neuropathologically ('definite CAA'), or during life ('probable CAA') using the (modified) Boston criteria based on MRI markers. Method: We performed a systematic literature search in PubMed and EMBASE for studies on CAA prevalence in cohorts of patients with AD, population‐based individuals, healthy elderly, patients with intracerebral hemorrhage (ICH), and patients with lobar ICH. Study inclusion criteria were: 1) a study population of at least 10 subjects, 2) a mean age of ≥ 55 years, 3) diagnostic criteria included use of neuropathology or MRI (T2* or SWI), 4) outcome measures included CAA prevalence according to neuropathological assessment or the (modified) Boston criteria, or the prevalence of the MRI markers used in the Boston criteria: strictly lobar microbleeds or cortical superficial siderosis. Result: We included 170 studies including over 73,000 subjects. We found that in patients with AD, the estimated prevalence of CAA based on pathology (48%) is twice the prevalence based on the presence of strictly lobar microbleeds (22%). In the general population, this difference is threefold (23% vs 7%). However, both methods yield the same estimated prevalence of CAA in healthy elderly (5‐7%), in patients with ICH (19‐24%), and in patients with lobar ICH (50‐57%). In addition, we observed large heterogeneity in both neuropathology and MRI study protocols. Conclusion: CAA is a very prevalent condition in AD and in the population. Since CAA is associated with the development of amyloid‐related imaging abnormalities in anti‐amyloid β immunotherapy, a faster decline of cognitive function in AD, and a growing spectrum of clinical symptoms, awareness of the high prevalence of CAA is important. In addition, we found that MRI markers seriously underestimate the prevalence of CAA in AD patients and population‐based individuals. Lastly, our results emphasize the need for standardized assessment and reporting of CAA in neuropathology and MRI studies. [ABSTRACT FROM AUTHOR]

Background: Cerebral amyloid angiopathy (CAA) is characterized by the accumulation of amyloid‐beta (Abeta) peptides in the cerebral vasculature and has been associated with vascular dementia and intracerebral haemorrhages (ICH). Currently, the diagnosis of CAA is based on neuroimaging and includes the identification of lobar (micro‐)bleeds and cortical superficial siderosis. However, these MRI markers reflect only late‐stage manifestations and are therefore not suitable for an early diagnosis of CAA. We aimed to evaluate the diagnostic potential of the Abeta peptides AB1‐38, AB1‐40, AB1‐42, and AB1‐43 in cerebrospinal fluid (CSF) to discriminate (early) CAA from controls. Method: We used immunoassays to quantify AB1‐38, AB1‐40 and AB1‐42 in CSF and plasma and AB1‐43 only in CSF. CSF from sporadic CAA patients (n=28) and controls (n=40), and plasma from hereditary Dutch CAA (D‐CAA) patients (asymptomatic and symptomatic), sporadic CAA patients (n=129) and controls (n=99) were analyzed. Result: In CSF we found decreased levels of AB1‐38 (p=0.03; AUC 0.64), AB1‐40 (p=0.04; AUC 0.63), AB1‐42 (p<0.0001, AUC 0.87) and AB1‐43 (p<0.0001, AUC 0.92) in CAA patients compared to controls. In plasma we found significantly decreased levels of AB1‐38, AB1‐40 and AB1‐42 both in asymptomatic and symptomatic D‐CAA mutation carriers compared to controls. The concentrations of all Abeta peptides strongly correlated with each other (Spearman r>0.6, p<0.0001 for each comparison). Conclusion: Abeta peptides have strong biomarker potential for the diagnosis of (early)_CAA. Interestingly, our results indicate that AB1‐43, which has shown to be relatively low‐abundant in vascular amyloid deposits, has the highest diagnostic accuracy to discriminate CAA from controls. In addition, we show that CSF AB1‐38 levels are decreased in CAA compared to controls. [ABSTRACT FROM AUTHOR]

Background: Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are involved in extracellular matrix (ECM) modelling and regulation of basement membrane integrity. A chronic disbalance in the expression and activity of these proteinases and their inhibitors in favor of MMPs can lead to excessive degradation of the ECM, dysfunction of the blood‐brain barrier (BBB) and subsequent (micro)bleeds. Cerebral amyloid angiopathy (CAA) is characterized by accumulation of the amyloid‐β (Aβ) protein in cerebral vessel walls and decreased BBB integrity, and is a major cause of intracerebral hemorrhage and cognitive decline. Currently, diagnosis of CAA is based on neuroimaging, but there is a need for alternative methods as these neuroimaging methods are not optimal for detection of CAA during life at an early stage. Previously, Aβ40 levels in the cerebrospinal fluid (CSF) have been suggested as promising biomarker for CAA. We hypothesize that a disbalance in MMP/TIMP expression is associated with CAA and is reflected in the CSF, and may besides Aβ40, be a potential biomarker candidate for detection of CAA at an early stage. In this study, we aimed to quantify levels of MMPs, TIMPs and Aβ proteins in the CSF to gain more insight in the pathophysiology of CAA and to establish their potential biomarker value for CAA. Method: We used immunoassays to quantify MMP‐14, TIMP‐1 and Aβ40 levels in CSF in a group of controls (n=40) and CAA patients (n=28). Result: The MMP‐14/TIMP‐1 ratio was decreased in CAA (0.016 ± 0.005) vs. controls (0.022 ± 0.008; p=0.0007), which was a stronger difference than observed for either MMP‐14 (not significant: p=0.53) or TIMP‐1 (p=0.0027) alone, or for Aβ40 (p=0.038). The difference of the MMP‐14/TIMP‐1 ratio was robust and remained after correction for age and total protein levels. Conclusion: Our results suggest that a disbalance in the expression of MMP‐14 and TIMP‐1 in CSF is associated with CAA, and may be a promising biomarker both to identify CAA, with a higher diagnostic value than CSF Aβ40, as well as to obtain more insight into the pathophysiological processes in CAA. [ABSTRACT FROM AUTHOR]

Recently, we identified the mimotope UH- CIS6 as a novel candidate antibody target for clinically isolated syndrome ( CIS) and relapsing-remitting ( RR) multiple sclerosis ( MS). The purpose of this study was to further validate UH- CIS6 as an antibody target for CIS and MS and to identify the in vivo antibody target of UH- CIS6. First, a UH- CIS6 peptide ELISA was optimized. Next, we investigated the antibody response toward UH- CIS6 in cerebrospinal fluid ( CSF) from patients with CIS ( n = 20), MS ( n = 43) and other neurological diseases ( n = 42). Immunoprecipitation of anti- UH- CIS6 antibodies on a normal human brain lysate was performed to identify the in vivo antibody target of UH- CIS6. The cellular expression of an in vivo candidate target was investigated by immunohistochemistry using MS brain tissue sections. Antibody reactivity toward UH- CIS6 was detected in a significantly increased proportion of CSF samples from CIS and RR- MS patients as compared with neurological controls ( p = 0.046). We identified and confirmed coronin-1a as the in vivo antibody target for UH- CIS6. Furthermore, coronin-1a was expressed by T cells and macrophages in an active MS lesion. Together, these results demonstrate that coronin-1a is a novel antibody target for CIS and MS. [ABSTRACT FROM AUTHOR]

Abstract: Background: [11C]Pittsburgh compound B ([11C]PIB) and [18F]-2-fluoro-2-deoxy-D-glucose ([18F]FDG) PET measure fibrillar amyloid-β load and glucose metabolism, respectively. We evaluated the impact of these tracers on the diagnostic process in a memory clinic population. Methods: One hundred fifty-four patients underwent paired dynamic [11C]PIB and static [18F]FDG PET scans shortly after completing a standard dementia screening. Two-year clinical follow-up data were available for 39 patients. Parametric PET images were assessed visually and results were reported to the neurologists responsible for the initial diagnosis. Outcome measures were (change in) clinical diagnosis and confidence in that diagnosis before and after disclosing PET results. Results: [11C]PIB scans were positive in 40 of 66 (61%) patients with a clinical diagnosis of Alzheimer’s disease (AD), 5 of 18 (28%) patients with frontotemporal dementia (FTD), 4 of 5 (80%) patients with Lewy body dementia, and 3 of 10 (30%) patients with other dementias. [18F]FDG uptake patterns matched the clinical diagnosis in 38 of 66 (58%) of AD patients, and in 6 of 18 (33%) FTD patients. PET results led to a change in diagnosis in 35 (23%) patients. This only occurred when prior diagnostic certainty was <90%. Diagnostic confidence increased from 71 ± 17% before to 87 ± 16% after PET (p < .001). Two-year clinical follow-up (n = 39) showed that [11C]PIB and [18F]FDG predicted progression to AD for patients with mild cognitive impairment, and that the diagnosis of dementia established after PET remained unchanged in 96% of patients. Conclusions: In a memory clinic setting, combined [11C]PIB and [18F]FDG PET are of additional value on top of the standard diagnostic work-up, especially when prior diagnostic confidence is low. [Copyright &y& Elsevier]

Abstract: Background: We aimed to develop a prediction model based on cerebrospinal fluid (CSF) biomarkers, that would yield a single estimate representing the probability that dementia in a memory clinic patient is due to Alzheimer’s disease (AD). Methods: All patients suspected of dementia in whom the CSF biomarkers had been analyzed were selected from a memory clinic database. Clinical diagnosis was AD (n = 272) or non-AD (n = 289). The prediction model was developed with logistic regression analysis and included CSF amyloid β42, CSF phosphorylated tau181, and sex. Validation was performed on an independent data set from another memory clinic, containing 334 AD and 157 non-AD patients. Results: The prediction model estimated the probability that AD is present as follows: p(AD) = 1/(1 + e – [–0.3315 + score]), where score is calculated from –1.9486 × ln(amyloid β42) + 2.7915 × ln(phosphorylated tau181) + 0.9178 × sex (male = 0, female = 1). When applied to the validation data set, the discriminative ability of the model was very good (area under the receiver operating characteristic curve: 0.85). The agreement between the probability of AD predicted by the model and the observed frequency of AD diagnoses was very good after taking into account the difference in AD prevalence between the two memory clinics. Conclusions: We developed a prediction model that can accurately predict the probability of AD in a memory clinic population suspected of dementia based on CSF amyloid β42, CSF phosphorylated tau181, and sex. [Copyright &y& Elsevier]

OBJECTIVE: Sporadic inclusion body myositis (sIBM) is an inflammatory myopathy characterized by both degenerative and autoimmune features. In contrast to other inflammatory myopathies, myositis-specific autoantibodies had not been found in sIBM patients until recently. We used human skeletal muscle extracts as a source of antigens to detect autoantibodies in sIBM and to characterize the corresponding antigen. METHODS: Autoantibodies to skeletal muscle antigens were detected by immunoblotting. The target antigen was immunoaffinity-purified from skeletal muscle extracts and characterized by mass spectrometry. A cDNA encoding this protein was cloned and expressed in vitro, and its recognition by patient sera was analyzed in an immunoprecipitation assay. Epitopes were mapped using microarrays of overlapping peptides. RESULTS: An Mr 44,000 polypeptide (Mup44) was frequently targeted by sIBM autoantibodies. The target protein was purified, and subsequent mass spectrometry analysis revealed that Mup44 is the cytosolic 5'-nucleotidase 1A (cN1A). By immunoprecipitation of recombinant cN1A, high concentrations of anti-Mup44 autoantibodies were detected in 33% of sIBM patient sera, whereas their prevalence in dermatomyositis, polymyositis, and other neuromuscular disorders appeared to be rare (4.2%, 4.5%, and 3.2%, respectively). Low concentrations of anti-Mup44 antibodies were found in myositis as well as other neuromuscular disorders, but not in healthy controls. Three major autoepitope regions of cN1A were mapped by using microarrays containing a set of overlapping peptides covering the complete cN1A amino acid sequence. INTERPRETATION: Anti-Mup44 autoantibodies, which are targeted to cN1A, represent the first serological biomarker for sIBM and may facilitate the diagnosis of this type of myositis. ANN NEUROL 2013;73:397-407. [ABSTRACT FROM AUTHOR]

Limited information is available on the identity of antigens targeted by antibodies present in cerebrospinal fluid ( CSF) of patients with clinically isolated syndrome ( CIS). The aim of this study was to identify novel antigens for CIS and investigate their prognostic potential to predict conversion to multiple sclerosis ( MS). We applied serological antigen selection ( SAS) to identify antigens interacting with antibodies present in the pooled CSF from four CIS patients, who developed MS. Antibody reactivity towards CIS antigens identified by SAS was tested in CSF and serum from patients with CIS ( n = 123/ n = 108), MS ( n = 65/ n = 44), and other (inflammatory) neurological diseases ( n = 75/ n = 38) as well as in healthy control sera ( n = 44). Using SAS, a panel of six novel CIS candidate antigens was identified. CSF antibody reactivity was detected in both CIS and relapsing-remitting ( RR) MS. Serum reactivity was significantly increased in CIS and RR- MS as compared with controls ( p = 0.03). For two antigens, the frequency of antibody-positive patients was higher in CIS patients who converted to MS as compared with CIS patients without conversion. We identified novel CIS antigens to which antibody reactivity was primarily detected in CIS and RR- MS as compared to controls. Possible prognostic potential could be demonstrated for two antigens. [ABSTRACT FROM AUTHOR]

Objective: This study was designed to establish the reliability of neurologic examination, neuron-specific enolase (NSE), and median nerve somatosensory-evoked potentials (SEPs) to predict poor outcome in patients treated with mild hypothermia after cardiopulmonary resuscitation (CPR). Methods: This multicenter prospective cohort study included adult comatose patients admitted to the intensive care unit (ICU) after CPR and treated with hypothermia (32-34°C). False-positive rates (FPRs 1 − specificity) with their 95% confidence intervals (CIs) were calculated for pupillary light responses, corneal reflexes, and motor scores 72 hours after CPR; NSE levels at admission, 12 hours after reaching target temperature, and 36 hours and 48 hours after collapse; and SEPs during hypothermia and after rewarming. The primary outcome was poor outcome, defined as death, vegetative state, or severe disability (Glasgow Outcome Scale 1-3) after 6 months. Results: Of 391 patients included, 53% had a poor outcome. Absent pupillary light responses (FPR 1; 95% CI, 0-7) or absent corneal reflexes (FPR 4; 95% CI, 1-13) 72 hours after CPR, and absent SEPs during hypothermia (FPR 3; 95% CI, 1-7) and after rewarming (FPR 0; 95% CI, 0-18) were reliable predictors. Motor scores 72 hours after CPR (FPR 10; 95% CI, 6-16) and NSE levels were not. Interpretation: In patients with persisting coma after CPR and therapeutic hypothermia, use of motor score or NSE, as recommended in current guidelines, could possibly lead to inappropriate withdrawal of treatment. Poor outcomes can reliably be predicted by testing brainstem reflexes 72 hours after CPR and performing SEP. ANN NEUROL 2012;71:206-212 [ABSTRACT FROM AUTHOR]

The fibrillization of α-synuclein (α-syn) is a key event in the pathogenesis of α-synucleinopathies. Mutant α-syn (A53T, A30P, or E46K), each linked to familial Parkinson's disease, has altered aggregation properties, fibril morphologies, and fibrillization kinetics. Besides α-syn, Lewy bodies also contain several associated proteins including small heat shock proteins (sHsps). Since α-syn accumulates intracellularly, molecular chaperones like sHsps may regulate α-syn folding and aggregation. Therefore, we investigated if the sHsps αB-crystallin, Hsp27, Hsp20, HspB8, and HspB2B3 bind to α-syn and affect α-syn aggregation. We demonstrate that all sHsps bind to the various α-syns, although the binding kinetics suggests a weak and transient interaction only. Despite this transient interaction, the various sHsps inhibited mature α-syn fibril formation as shown by a Thioflavin T assay and atomic force microscopy. Interestingly, HspB8 was the most potent sHsp in inhibiting mature fibril formation of both wild-type and mutant α-syn. In conclusion, sHsps may regulate α-syn aggregation and, therefore, optimization of the interaction between sHsps and α-syn may be an interesting target for therapeutic intervention in the pathogenesis of α-synucleinopathies. Proteins 2011; © 2011 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Cerebral amyloid angiopathy is caused by deposition of the amyloid β protein in the cerebral vasculature. In analogy to previous observations in Alzheimer disease, we hypothesized that analysis of amyloid β40 and β42 proteins in the cerebrospinal fluid might serve as a molecular biomarker. We observed strongly decreased cerebrospinal fluid amyloid β40 ( p < 0.01 vs controls or Alzheimer disease) and amyloid β42 concentrations ( p < 0.001 vs controls and p < 0.05 vs Alzheimer disease) in cerebral amyloid angiopathy patients. The combination of amyloid β42 and total tau discriminated cerebral amyloid angiopathy from controls, with an area under the receiver operator curve of 0.98. Our data are consistent with neuropathological evidence that amyloid β40 as well as amyloid β42 protein are selectively trapped in the cerebral vasculature from interstitial fluid drainage pathways that otherwise transport amyloid β proteins toward the cerebrospinal fluid. Ann Neurol 2009;66:245-249 [ABSTRACT FROM AUTHOR]

Cerebral amyloid angiopathy is caused by deposition of the amyloid beta protein in the cerebral vasculature. In analogy to previous observations in Alzheimer disease, we hypothesized that analysis of amyloid beta(40) and beta(42) proteins in the cerebrospinal fluid might serve as a molecular biomarker. We observed strongly decreased cerebrospinal fluid amyloid beta(40) (p < 0.01 vs controls or Alzheimer disease) and amyloid beta(42) concentrations (p < 0.001 vs controls and p < 0.05 vs Alzheimer disease) in cerebral amyloid angiopathy patients. The combination of amyloid beta(42) and total tau discriminated cerebral amyloid angiopathy from controls, with an area under the receiver operator curve of 0.98. Our data are consistent with neuropathological evidence that amyloid beta(40) as well as amyloid beta(42) protein are selectively trapped in the cerebral vasculature from interstitial fluid drainage pathways that otherwise transport amyloid beta proteins toward the cerebrospinal fluid. [ABSTRACT FROM AUTHOR]

Tyrosine hydroxylase (TH) deficiency (OMIM 191290) is one cause of early-onset dopa-responsive dystonia. We describe seven cases from five unrelated families with dopa-responsive dystonia and low homovanillic acid in cerebrospinal fluid who were suspected to suffer from TH deficiency. Analysis of part of the TH promotor showed five homozygous and two heterozygous mutations in the highly conserved cyclic adenosine monophosphate response element. Our data suggest that, if no mutations are found in the coding regions of the gene in patients strongly suspected of TH deficiency, the search for pathogenic mutations should be extended to regulatory promotor elements. Ann Neurol 2007 [ABSTRACT FROM AUTHOR]

We investigated whether cerebrospinal fluid (CSF) analysis discriminates between idiopathic Parkinson's disease (PD; n = 35) and multiple system atrophy (MSA; n = 30). The median CSF concentration of the neurotransmitter metabolites 5-hydroxyindolacetic acid (5-HIAA) and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) was reduced significantly (49-70%) in MSA compared to PD. In contrast, several brain-specific proteins (tau, neuron-specific enolase, myelin basic protein) were elevated (130-230%) in MSA compared with those in PD. A combination of CSF tau and MHPG discriminated PD from MSA (adjusted odds ratios: tau, 27.2; MHPG, 0.14). Our data suggest that the more progressive and widespread neurodegenerative nature of MSA, as compared with PD, is reflected in the composition of CSF. We propose that CSF analysis may become part of the diagnostic work-up of patients with parkinsonian syndromes. [ABSTRACT FROM AUTHOR]

Objectives Methods Results Interpretation Spinocerebellar ataxia type 1 (SCA1) is a rare autosomal dominant neurodegenerative disease. Objective surrogate markers sensitive to detect changes in disease severity are needed to reduce sample sizes in interventional trials and identification of predictors of faster disease progression would facilitate patient selection, enrichment, or stratification in such trials.We performed a prospective 1‐year longitudinal, multimodal study in 34 ataxic SCA1 individuals and 21 healthy controls. We collected clinical, patient‐reported outcomes, biochemical and magnetic resonance (MR) biomarkers at baseline and after 1 year. We determined 1‐year progression and evaluated the potential predictive value of several baseline markers on 1‐year disease progression.At baseline, multiple structural and spectroscopic MR markers in pons and cerebellum differentiated SCA1 from healthy controls and correlated with disease severity. Plasma and cerebrospinal fluid (CSF) neurofilament light (NfL) chain and CSF glial fibrillary acidic protein (GFAP) were elevated in SCA1. In longitudinal analysis, total brainstem and pontine volume change, inventory of non‐ataxia signs (INAS) count, and SCA functional index (SCAFI) showed larger responsiveness compared to the Scale for Assessment and Rating of Ataxia (SARA).Longer disease duration, longer non‐expanded CAG repeat length, and higher disease burden were associated with faster SARA increase after 1‐year in the SCA1 group. Similarly, lower baseline brainstem, pontine, and cerebellar volumes, as well as lower levels of N‐acetylaspartate and glutamate in the cerebellar white matter, were also associated with faster SARA increase.Our results guide the selection of the most sensitive measures of disease progression in SCA1 and have identified features associated with accelerated progression that could inform the design of clinical trials. ANN NEUROL 2024 [ABSTRACT FROM AUTHOR]

Background: There is a lack of biomarkers for the early detection of Alzheimer's disease (AD). Cerebral amyloid angiopathy (CAA), which is characterized by the accumulation of amyloid‐β (Aβ) in the cerebral vasculature, is commonly found in AD. Platelet‐derived growth factor receptor‐β (PDGFRβ) is expressed by pericytes and since blood‐brain barrier (BBB) dysfunction is associated with pericyte degeneration, release of PDGFRβ protein may be a biomarker for BBB dysfunction, that is expected in CAA. Indeed, it has recently been described that PDGFRβ levels are elevated in cerebrospinal fluid (CSF) from patients with mild cognitive impairment (MCI) as compared to controls1. The aim of our study was to investigate the diagnostic and discriminative value of PDGFRβ in CSF in patients at various clinical stages of AD and in patients with CAA. Method: CSF PDGFRβ, Aβ42, total tau (t‐tau) and phosphorylated tau (p‐tau) levels were quantified by ELISA. Cohorts of controls (n=47), CAA patients (n=27) and AD patients (n=59; 19 patients with MCI (clinical dementia rating (CDR) = 0.5), 28 patients with CDR 1.0 and 12 patients with a CDR of ≥ 2.0) were studied. Result: CSF PDGFRβ levels were similar in controls, AD and CAA patients. Moreover, PDGFRβ levels were similar in patients at the various clinical stages of AD. PDGFRβ levels also did not correlate with blood‐CSF barrier dysfunction (i.e. elevated albumin ratio). We observed a strong correlation of CSF PDGFRβ levels with t‐tau and p‐tau levels, the degree of which was dependent on the CDR score. Interestingly, CSF PDGFRβ levels were significantly elevated in a selection of MCI/AD patients with an AD‐positive CSF biomarker profile (A+T+) as compared to controls with a completely normal profile of AD biomarkers (A‐T‐N‐). Conclusion: We could neither confirm previously reported elevated CSF PDGFRβ levels in MCI patients1, nor did we find elevated PDGFRβ levels in CAA patients. Our results suggest that CSF PDGFRβ levels are not useful as marker of BBB integrity, but instead may, as previously reported, be associated with AD (tau) pathology2. References: 1Nation et al., Nat Med. 2019;25(2):270‐276; 2Miners et al., Alzheimers Res Ther. 2019;11(1):81. [ABSTRACT FROM AUTHOR]