NFL and GFAP in (pre)symptomatic RVCL-S carriers: a monogenic cerebral small vessel disease.

BACKGROUND: Neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) have emerged as biomarkers for cerebral small vessel disease (SVD). We investigated their role in a hereditary SVD model, retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S). METHODS: NfL and GFAP levels of 17 pre-symptomatic, 22 symptomatic RVCL-S mutation carriers and 69 controls were measured using a Simoa assay. We assessed the association of serum and cerebrospinal fluid (CSF) levels of NfL and GFAP with RVCL-S symptomatology and neuropsychological functioning. RESULTS: Serum and CSF NfL levels were higher in symptomatic RVCL-S compared to controls ≥ 45 years (33.5 pg/mL vs. 9.2 pg/mL, p < 0.01; 8.5*102 pg/mL vs. 3.9*102 pg/mL, p < 0.01, respectively). Serum NfL levels were higher in symptomatic RVCL-S than pre-symptomatic carriers (33.5 pg/mL vs. 5.9 pg/mL, p = 0.02). Pre-symptomatic RVCL-S carriers had increased CSF NfL levels compared to controls < 45 years (5.2*102 pg/mL vs. 1.9*102 pg/mL, p < 0.01). No differences were found in GFAP levels across groups, but in RVCL-S carriers higher serum levels of both NfL and GFAP were linked to poorer global cognitive functioning (ß[95%CI] = - 2.86 [- 5.58 to - 0.13], p = 0.04 and ß[95%CI] = - 6.85 [- 11.54 to - 2.15], p = 0.01, respectively) and prolonged psychomotor test times (ß[95%CI] = 6.71 [0.78-12.65], p = 0.03 and ß[95%CI] = 13.84 [3.09-24.60], p = 0.01). DISCUSSION: Higher levels of serum NfL and GFAP are associated with worse cognitive functioning in RVCL-S carriers and may serve as marker for disease progression. CSF NfL levels may serve as early marker as pre-symptomatic RVCL-S patients already show differences compared to young controls.

ASURE Clinical Trial Protocol: A Randomized, Placebo-Controlled, Proof-of-Concept Study Aiming to Evaluate Safety and Target Engagement following Administration of TW001 in Early Alzheimer's Disease Patients.

BACKGROUND: Alzheimer's disease (AD) is a neurodegenerative disease with complex disease etiology and pathological processes. These include formation of plaques and tangles, aberrant lipid processing, neuroinflammation, cerebrovascular dysregulation, ion channel and mitochondrial dysfunction, and oxidative stress. Disease-modifying therapies focusing on all these different facets are needed. TW001 is an oral formulation with the radical scavenger edaravone as its active ingredient, targeting oxidative stress. OBJECTIVES: This manuscript describes the trial design for Phase IIA Alzheimer Study Using oRal Edaravone (ASURE). METHODS: ASURE is a randomized, placebo-controlled, proof-of-concept study aiming to evaluate safety and target engagement following administration of TW001 in early AD patients. Patients should have a biomarker confirmed diagnosis to be included in the trial and will be treated for 90 days. The primary endpoints include safety and effect of TW001 on oxidative stress biomarkers. Exploratory endpoints focus on a panel of AD(-related) fluid-based biomarkers and EEG. In addition, a recently developed cognitive functional composite (CFC) score will measure early signs of cognitive and functional effects of TW001. RESULTS: This article outlines the design of the clinical study, no results are included. CONCLUSIONS: The ASURE trial design is discussed, with a particular focus on fluid biomarkers, EEG, and CFC as endpoints. By testing multiple measures related to pathology, pharmacodynamics, EEG as proxy for cognition, and cognitive functional scores, it is expected that small changes will be detectable in trials of shorter duration. Moreover, the wide range of endpoints allows to make well-informed decisions for designing pivotal studies later.

Axonal damage and astrocytosis are biological correlates of grey matter network integrity loss: a cohort study in autosomal dominant Alzheimer disease.

Brain development and maturation leads to grey matter networks that can be measured using magnetic resonance imaging. Network integrity is an indicator of information processing capacity which declines in neurodegenerative disorders such as Alzheimer disease (AD). The biological mechanisms causing this loss of network integrity remain unknown. Cerebrospinal fluid (CSF) protein biomarkers are available for studying diverse pathological mechanisms in humans and can provide insight into decline. We investigated the relationships between 10 CSF proteins and network integrity in mutation carriers (N=219) and noncarriers (N=136) of the Dominantly Inherited Alzheimer Network Observational study. Abnormalities in Aß, Tau, synaptic (SNAP-25, neurogranin) and neuronal calcium-sensor protein (VILIP-1) preceded grey matter network disruptions by several years, while inflammation related (YKL-40) and axonal injury (NfL) abnormalities co-occurred and correlated with network integrity. This suggests that axonal loss and inflammation play a role in structural grey matter network changes. Key points: Abnormal levels of fluid markers for neuronal damage and inflammatory processes in CSF are associated with grey matter network disruptions.The strongest association was with NfL, suggesting that axonal loss may contribute to disrupted network organization as observed in AD.Tracking biomarker trajectories over the disease course, changes in CSF biomarkers generally precede changes in brain networks by several years.

The wearing-off phenomenon of ocrelizumab in patients with multiple sclerosis.

BACKGROUND: Patients with multiple sclerosis (MS) who are treated with monoclonal antibodies frequently report an increase of MS-related symptoms prior to the next dose known as the wearing-off phenomenon. The objective of this study was to assess the prevalence and predicting factors of the wearing-off phenomenon in patients with MS using ocrelizumab. METHODS: This was a prospective cohort study in patients with MS receiving ocrelizumab ≥1 year. Most participants received B-cell guided personalized extended interval dosing to limit ocrelizumab exposure and hospital visits during the COVID-19 pandemic (cut-off ≥ 10 cells/µL). Participants completed questionnaires during ocrelizumab infusion and 2 weeks thereafter. Demographics, clinical and radiological characteristics, CD19 B-cell counts, and serum neurofilament light (sNfL) levels were collected. Data were analyzed using logistic regression analyses. RESULTS: Seventy-one (61%) out of 117 participants reported the wearing-off phenomenon during ocrelizumab treatment. The most frequently reported symptoms were fatigue, cognitive disability and sensory symptoms. Wearing-off symptoms started < 1 week (11%), 1-4 weeks (49%) or more than 4 weeks (37%) before ocrelizumab infusion. Fifty participants (43%) reported a current wearing-off phenomenon at the first questionnaire. Higher body mass index (threshold BMI ≥ 25) increased the odds of reporting a current wearing-off phenomenon (OR 2.70, 95% CI 1.26 to 5.80, p = .011). Infusion interval, EDSS score, MRI disease activity, clinical relapses, CD19 B-cell counts, and sNfL levels were no predictors. Disappearance of the wearing-off phenomenon occurred in the first week after ocrelizumab infusion in most participants. Participants with a current wearing-off phenomenon significantly improved in self-reported physical and psychological functioning after ocrelizumab infusion. Reporting the wearing-off phenomenon did not influence treatment satisfaction. Forty of 109 participants (37%) reported post-infusion symptoms, such as fatigue, flu-like symptoms or walking difficulties. These post-infusion symptoms started directly or in the first week after ocrelizumab infusion and disappeared within 2 weeks. CONCLUSIONS: The wearing-off phenomenon is reported by more than half of patients with MS using ocrelizumab. Only BMI was identified as a predicting factor. The wearing-off phenomenon was not elicited by extending infusion intervals or higher B-cell counts. The wearing-off phenomenon of ocrelizumab therefore does not seem to reflect suboptimal control of MS disease activity.

Ocrelizumab after natalizumab in JC-virus positive relapsing remitting multiple sclerosis patients.

Ocrelizumab is often used as an alternative therapy in natalizumab-treated MS patients at risk for progressive multifocal leukoencephalopathy (PML). Our objective was to assess efficacy and safety of JC-virus positive patients switching (either directly or indirectly) from natalizumab to ocrelizumab. Forty-two patients were included from an observational cohort (median follow-up 21 months). No evidence of disease activity was found in 83% of direct switchers and 50% of indirect switchers. Two direct switchers were diagnosed with carry-over PML. Our data support a direct switch for adequate disease suppression, although carry-over PML illustrates the dilemma when choosing between a direct or indirect switch.

A neurologist's perspective on serum neurofilament light in the memory clinic: a prospective implementation study.

BACKGROUND: Neurofilament light in serum (sNfL) is a biomarker for axonal damage with elevated levels in many neurological disorders, including neurodegenerative dementias. Since within-group variation of sNfL is large and concentrations increase with aging, sNfL's clinical use in memory clinic practice remains to be established. The objective of the current study was to evaluate the clinical use of serum neurofilament light (sNfL), a cross-disease biomarker for axonal damage, in a tertiary memory clinic cohort. METHODS: Six neurologists completed questionnaires regarding the usefulness of sNfL (n = 5-42 questionnaires/neurologist). Patients that visited the Alzheimer Center Amsterdam for the first time between May and October 2019 (n = 109) were prospectively included in this single-center implementation study. SNfL levels were analyzed on Simoa and reported together with normal values in relation to age, as part of routine diagnostic work-up and in addition to cerebrospinal fluid (CSF) biomarker analysis. RESULTS: SNfL was perceived as useful in 53% (n = 58) of the cases. SNfL was more often perceived as useful in patients < 62 years (29/48, 60%, p = 0.05) and males (41/65, 63%, p < 0.01). Availability of CSF biomarker results at time of result discussion had no influence. We observed non-significant trends for increased perceived usefulness of sNfL for patients with the diagnosis subjective cognitive decline (64%), psychiatric disorder (71%), or uncertain diagnosis (67%). SNfL was mostly helpful to neurologists in confirming or excluding neurodegeneration. Whether sNfL was regarded as useful strongly depended on which neurologist filled out the questionnaire (ranging from 0 to 73% of useful cases/neurologist). DISCUSSION: Regardless of the availability of CSF biomarker results, sNfL was perceived as a useful tool in more than half of the evaluated cases in a tertiary memory clinic practice. Based on our results, we recommend the analysis of the biomarker sNfL to confirm or exclude neurodegeneration in patients below 62 years old and in males.

Characterization of symptoms and determinants of disease burden in dementia with Lewy bodies: DEvELOP design and baseline results.

BACKGROUND: The DEmEntia with LEwy bOdies Project (DEvELOP) aims to phenotype patients with dementia with Lewy bodies (DLB) and study the symptoms and biomarkers over time. Here, we describe the design and baseline results of DEvELOP. We investigated the associations between core and suggestive DLB symptoms and different aspects of disease burden, i.e., instrumental activities of daily living (IADL) functioning, quality of life (QoL), and caregiver burden. METHODS: We included 100 DLB patients (69 ± 6 years, 10%F, MMSE 25 ± 3) in the prospective DEvELOP cohort. Patients underwent extensive assessment including MRI, EEG/MEG, 123FP-CIT SPECT, and CSF and blood collection, with annual follow-up. Core (hallucinations, parkinsonism, fluctuations, RBD) and suggestive (autonomous dysfunction, neuropsychiatric symptoms) symptoms were assessed using standardized questionnaires. We used multivariate regression analyses, adjusted for age, sex, and MMSE, to evaluate how symptoms related to the Functional Activities Questionnaire, QoL-AD questionnaire, and Zarit Caregiver Burden Interview. RESULTS: In our cohort, RBD was the most frequently reported core feature (75%), while visual hallucinations were least frequently reported (39%) and caused minimal distress. Suggestive clinical features were commonly present, of which orthostatic hypotension was most frequently reported (64%). Ninety-five percent of patients showed EEG/MEG abnormalities, 88% of 123FP-CIT SPECT scans were abnormal, and 53% had a CSF Alzheimer's disease profile. Presence of fluctuations, lower MMSE, parkinsonism, and apathy were associated with higher IADL dependency. Depression, constipation, and lower IADL were associated with lower QoL-AD. Apathy and higher IADL dependency predisposed for higher caregiver burden. CONCLUSION: Baseline data of our prospective DLB cohort show clinically relevant associations between symptomatology and disease burden. Cognitive and motor symptoms are related to IADL functioning, while negative neuropsychiatric symptoms and functional dependency are important determinants of QoL and caregiver burden. Follow-up is currently ongoing to address specific gaps in DLB research.

Variations in consecutive serum neurofilament light levels in healthy controls and multiple sclerosis patients.

Background Neurofilament light is a neuronal protein detectable in serum (sNfL), with high potential as disease activity biomarker in multiple sclerosis (MS). To date, little is known about sNfL fluctuations between 2 consecutive measurements in healthy controls (HC) and MS patients. Yet this information is critical, as it will help define a clinically significant variation. Methods sNfL was measured at 2 consecutive time points in a cohort of 90 MS patients (untreated relapsing remitting MS (uRRMS), n=35; treated relapsing remitting MS (tRRMS), n= 21; secondary progressive MS, SPMS, n=21; primary progressive MS, PPMS, n=13), and 90 age-matched HC, using the Simoa NfL light® assay. Results Mean sNfL was elevated in all MS subtypes compared to HC (p<0.0001), and positively associated with age in HC (r=0.70, p<0.001), confirming previous reports. Mean sNfL was higher at follow-up compared to baseline in HC (p<0.001), and lower in uRRMS(p=0.036) and tRRMS (p=0.008). At follow-up, a similar proportion of HC (50.0%), untreated RRMS (51.4%), treated RRMS (33.3%), SPMS (45.0%) and PPMS (46.2%) had variations in sNfL levels exceeding 20% of baseline levels. Conclusions Our data suggest variations in sNfL occur both in HC and MS populations to a similar extent and magnitude. Variations between two consecutive sNfL measurements may reflect natural variations and not necessarily variations in inflammatory disease activity.

Sex-specific associations with cerebrospinal fluid biomarkers in dementia with Lewy bodies.

BACKGROUND: Dementia with Lewy bodies (DLB) is more prevalent in men than in women. In addition, post-mortem studies found sex differences in underlying pathology. It remains unclear whether these differences are also present antemortem in in vivo biomarkers, and whether sex differences translate to variability in clinical manifestation. The objective of this study was to evaluate sex differences in cerebrospinal fluid (CSF) biomarker concentrations (i.e., alpha-synuclein (α-syn), amyloid ß1-42 (Aß42), total tau (Tau), phosphorylated tau at threonine 181 (pTau)) and clinical characteristics in DLB. METHODS: We included 223 DLB patients from the Amsterdam Dementia Cohort, of which 39 were women (17%, age 70 ± 6, MMSE 21 ± 6) and 184 men (83%, age 68 ± 7, MMSE 23 ± 4). Sex differences in CSF biomarker concentrations (i.e., α-syn, Aß42, Tau, and pTau) were evaluated using age-corrected general linear models (GLM). In addition, we analyzed sex differences in core clinical features (i.e., visual hallucinations, parkinsonism, cognitive fluctuations, and REM sleep behavior disorder (RBD) and cognitive test scores using age- and education-adjusted GLM. RESULTS: Women had lower CSF α-syn levels (F 1429 ± 164 vs M 1831 ± 60, p = 0.02) and CSF Aß42 levels (F 712 ± 39 vs M 821 ± 18, p = 0.01) compared to men. There were no sex differences for (p) Tau concentrations (p > 0.05). Clinically, women were older, had a shorter duration of complaints (F 2 ± 1 vs M 4 ± 3, p < 0.001), more frequent hallucinations (58% vs 38%, p = 0.02), and scored lower on MMSE and a fluency task (MMSE, p = 0.02; animal fluency, p = 0.006). Men and women did not differ on fluctuations, RBD, parkinsonism, or other cognitive tests. CONCLUSIONS: Women had lower Aß42 and α-syn levels than men, alongside a shorter duration of complaints. Moreover, at the time of diagnosis, women had lower cognitive test scores and more frequent hallucinations. Based on our findings, one could hypothesize that women have a more aggressive disease course in DLB compared to men. Future research should investigate whether women and men with DLB might benefit from sex-specific treatment strategies.

Olfactory and gustatory functioning and food preferences of patients with Alzheimer's disease and mild cognitive impairment compared to controls: the NUDAD project.

Our aim is to compare olfactory and gustatory function and food preferences of patients with Mild Cognitive Impairment (MCI) and Alzheimer's disease (AD) with controls. We included 22 patients with MCI, 30 patients with AD and 40 controls and assessed olfactory threshold, odor discrimination and odor identification (Sniffin' Sticks), gustatory functioning (Taste Strips), and food preferences (Macronutrient and Taste Preference Ranking Task). Linear regression analyses were used to study associations of five cognitive domains or AD biomarkers with olfactory functioning. Groups did not differ in olfactory threshold, gustatory function and food preferences. Patients with MCI and AD scored lower on odor discrimination and identification than controls. Poorer memory, but no other cognitive domain, was associated with poorer odor discrimination and odor identification, but not with odor threshold. No associations with AD biomarkers were found. In conclusion, patients with MCI and AD have poorer odor discrimination and identification ability than controls, but similar detection thresholds. This is likely a consequence of poorer memory rather than directly caused by AD pathology.

Systemic and intrathecal immune activation in association with cerebral and cognitive outcomes in paediatric HIV.

Despite treatment, immune activation is thought to contribute to cerebral injury in children perinatally infected with human immunodeficiency virus (HIV). We aimed to characterize immune activation in relation to neuroimaging and cognitive outcomes. We therefore measured immunological, coagulation, and neuronal biomarkers in plasma and cerebrospinal fluid (CSF) samples of 34 perinatally HIV-infected children aged 8-18 years, and in plasma samples of 37 controls of comparable age, sex, ethnicity, and socio-economic status. We then compared plasma biomarker levels between groups, and explored associations between plasma/CSF biomarkers and neuroimaging and cognitive outcomes using network analysis. HIV-infected children showed higher plasma levels of C-reactive protein, interferon-gamma, interferon-gamma-inducible protein-10, and monocyte chemoattractant protein-1 than controls. In HIV-infected participants, plasma soluble CD14 was positively associated with microstructural white matter (WM) damage, and plasma D-dimer was negatively associated with WM blood flow. In CSF, IL-6 was negatively associated with WM volume, and neurofilament heavy-chain (NFH) was negatively associated with intelligence quotient and working memory. These markers of ongoing inflammation, immune activation, coagulation, and neuronal damage could be used to further evaluate the pathophysiology and clinical course of cerebral and cognitive deficits in perinatally acquired HIV.

Cerebrospinal fluid mtDNA concentration is elevated in multiple sclerosis disease and responds to treatment.

BACKGROUND: Mitochondrial dysfunction is increasingly recognized as an important feature of multiple sclerosis (MS) pathology and may be relevant for clinical disease progression. However, it is unknown whether mitochondrial DNA (mtDNA) levels in the cerebrospinal fluid (CSF) associate with disease progression and therapeutic response. OBJECTIVES: To evaluate whether CSF concentrations of mtDNA in MS patients can serve as a marker of ongoing neuropathology and may be helpful to differentiate between MS disease subtypes. To explore the effect of disease-modifying therapies on mtDNA levels in the CSF. METHODS: CSF mtDNA was measured using a digital polymerase chain reaction (PCR) CSF mtDNA in two independent MS cohorts. The cohorts included 92 relapsing-remitting multiple sclerosis (RRMS) patients, 40 progressive multiple sclerosis (PMS) patients (27 secondary progressive and 13 primary progressive), 50 various neurologic disease controls, and 5 healthy controls. RESULTS: Patients with PMS showed a significant increase in CSF mtDNA compared to non-inflammatory neurologic disease controls. Patients with higher T2 lesion volumes and lower normalized brain volumes showed increased concentration of mtDNA. Patients treated with fingolimod had significantly lower mtDNA copy levels at follow-up compared to baseline. CONCLUSION: Our results showed a non-specific elevation of concentration of mtDNA in PMS patients. mtDNA concentrations respond to fingolimod and may be used to monitor biological effect of this treatment.

Brain endothelial cell expression of SPARCL-1 is specific to chronic multiple sclerosis lesions and is regulated by inflammatory mediators in vitro.

AIMS: Cell matrix modulating protein SPARCL-1 is highly expressed by astrocytes during CNS development and following acute CNS damage. Applying NanoLC-MS/MS to CSF of RRMS and SPMS patients, we identified SPARCL-1 as differentially expressed between these two stages of MS, suggesting a potential as CSF biomarker to differentiate RRMS from SPMS and a role in MS pathogenesis. METHODS: This study examines the potential of SPARCL-1 as CSF biomarker discriminating RRMS from SPMS in three independent cohorts (n = 249), analyses its expression pattern in MS lesions (n = 26), and studies its regulation in cultured human brain microvasculature endothelial cells (BEC) after exposure to MS-relevant inflammatory mediators. RESULTS: SPARCL-1 expression in CSF was significantly higher in SPMS compared to RRMS in a Dutch cohort of 76 patients. This finding was not replicated in 2 additional cohorts of MS patients from Sweden (n = 81) and Switzerland (n = 92). In chronic MS lesions, but not active lesions or NAWM, a vessel expression pattern of SPARCL-1 was observed in addition to the expression by astrocytes. EC were found to express SPARCL-1 in chronic MS lesions, and SPARCL-1 expression was regulated by MS-relevant inflammatory mediators in cultured human BEC. CONCLUSIONS: Conflicting results of SPARCL-1's differential expression in CSF of three independent cohorts of RRMS and SPMS patients precludes its use as biomarker for disease progression. The expression of SPARCL-1 by BEC in chronic MS lesions together with its regulation by inflammatory mediators in vitro suggest a role for SPARCL-1 in MS neuropathology, possibly at the brain vascular level.

The use of cerebrospinal fluid in biomarker studies.

Cerebrospinal fluid (CSF) is an extremely useful matrix for biomarker research for several purposes, such as diagnosis, prognosis, monitoring, and identification of prominent leads in pathways of neurologic diseases. Such biomarkers can be identified based on a priori hypotheses around prominent protein changes, but also by applying -omics technologies. Proteomics is widely used, but metabolomics and transcriptomics are rapidly revealing their potential for CSF studies. The basis of such studies is the availability of high-quality biobanks. Furthermore, profound knowledge and consequent optimization of all aspects in biomarker development are needed. Here we discuss current knowledge and recently developed protocols for successful biomarker studies, from collection of CSF by lumbar puncture, processing, and biobanking protocols, preanalytic confounding factors, and cost-efficient development and validation of assays for implementation into clinical practice or research.

Concomitant AD pathology affects clinical manifestation and survival in dementia with Lewy bodies.

OBJECTIVE: To investigate whether concomitant Alzheimer's disease (AD) pathology, reflected by cerebrospinal fluid (CSF) biomarkers, has an impact on dementia with Lewy bodies (DLB) in terms of clinical presentation, cognitive decline, nursing home admittance and survival. PARTICIPANTS: We selected 111 patients with probable DLB and CSF available from the Amsterdam Dementia Cohort. On the basis of the AD biomarker profile (CSF tau/amyloid-ß 1-42 (Aß42) ratio >0.52), we divided patients into a DLB/AD+ and DLB/AD- group. Of the 111 patients, 42 (38%) had an AD CSF biomarker profile. We investigated differences between groups in memory, attention, executive functions, language and visuospatial functions. Difference in global cognitive decline (repeated Mini-Mental State Examination (MMSE)) was investigated using linear mixed models. Cox proportional hazard analyses were used to investigate the effects of the AD biomarker profile on time to nursing home admittance and time to death. RESULTS: Memory performance was worse in DLB/AD+ patients compared with DLB/AD- patients (p<0.01), also after correction for age and sex. Hallucinations were more frequent in DLB/AD+ (OR=3.34, 95% CI 1.22-9.18). There was no significant difference in the rate of cognitive decline. DLB/AD+ patients had a higher mortality risk (HR=3.13, 95% CI 1.57 to 6.24) and nursing home admittance risk (HR=11.70, 95% CI 3.74 to 36.55) compared with DLB/AD- patients. CONCLUSIONS: DLB-patients with a CSF AD profile have a more severe manifestation of the disease and a higher risk of institutionalisation and mortality. In clinical practice, CSF biomarkers may aid in predicting prognosis in DLB. In addition, DLB-patients with positive AD biomarkers could benefit from future treatment targeting AD pathology.

Gray matter network differences between behavioral variant frontotemporal dementia and Alzheimer's disease.

We set out to study whether single-subject gray matter (GM) networks show disturbances that are specific for Alzheimer's disease (AD; n = 90) or behavioral variant frontotemporal dementia (bvFTD; n = 59), and whether such disturbances would be related to cognitive deficits measured with mini-mental state examination and a neuropsychological battery, using subjective cognitive decline subjects as reference. AD and bvFTD patients had a lower degree, connectivity density, clustering, path length, betweenness centrality, and small world values compared with subjective cognitive decline. AD patients had a lower connectivity density than bvFTD patients (F = 5.79, p = 0.02; mean ± standard deviation bvFTD 16.10 ± 1.19%; mean ± standard deviation AD 15.64 ± 1.02%). Lasso logistic regression showed that connectivity differences between bvFTD and AD were specific to 23 anatomical areas, in terms of local GM volume, degree, and clustering. Lower clustering values and lower degree values were specifically associated with worse mini-mental state examination scores and lower performance on the neuropsychological tests. GM showed disease-specific alterations, when comparing bvFTD with AD patients, and these alterations were associated with cognitive deficits.

The inflammatory marker GDF-15 is not independently associated with late-life depression.

OBJECTIVES: Growth differentiation factor-15 (GDF-15) is an inflammatory molecule that reacts to cell stress. Since major depression is associated with inflammation, we examined whether GDF-15 levels are elevated in patients with late-life depression. METHODS: Plasma GDF-15 levels were analyzed in 350 patients diagnosed with major depressive disorder in the last six months and 128 non-depressed controls from the Netherlands Study of Depression in Older persons (age ≥ 60 years). Major depressive disorder and age of onset were assessed with the Composite International Diagnostic Interview. Severity of depressive symptoms was measured with the Inventory of Depressive Symptoms (IDS-30). Multiple linear regression models were applied to study depression (diagnosis, onset age, severity, antidepressant drug use) as determinant of GDF-15 level, adjusted for demographic and clinical variables. RESULTS: Plasma GDF-15 levels were 22% higher in patients with major depression compared to controls. Within the depressed group, levels were higher in patients with older age of onset. GDF-15 levels showed a small, positive correlation to the levels of the inflammatory mediators IL-6 and C-reactive protein (r=0.23, and 0.24, p<0.05). This increase was independent from comorbidities, such as cardiovascular disease, rheumatism and diabetes, and anti-inflammatory drugs. However, this increase was dependent on lifestyle factors as smoking, physical activity and alcohol use. Within the depressed subgroup, neither depression severity or antidepressant drug use was associated with GDF-15 levels in the fully adjusted models. CONCLUSION: The inflammatory factor GDF-15 does not seem to be an independent inflammatory marker for late-life major depressive disorder.

Accumulation of BRI2-BRICHOS ectodomain correlates with a decreased clearance of Aß by insulin degrading enzyme (IDE) in Alzheimer's disease.

The precursor protein BRI2 that in its mutated form is associated with British and Danish dementia, can regulate critical processes involved in AD pathogenesis including not only the metabolism of amyloid precursor protein (APP) and formation of Aß, but also the levels of secreted insulin degrading enzyme (IDE), an enzyme involved in Aß clearance. We recently observed increased levels of a 45kDa BRI2 form as well as BRI2 ectodomain deposits in Aß plaques in human AD hippocampus, which may affect BRI2 functional activity. Since BRI2 regulated the levels of secreted IDE and subsequent degradation of Aß in human cell culture models, we explored if BRI2 changes could affect the Aß degradation capacity of IDE in human hippocampus (n=28). We observed that IDE is the main enzyme involved in Aß degradation, and both IDE levels as well as Aß degradation tend to be decreased in AD. Interestingly, the levels of the 45kDa BRI2 form and BRI2 deposits in hippocampal tissue were inversely correlated with IDE protein levels (r=-0.52, p=0.005; r=-0.4, p=0.045) and IDE activity (r=-0.5935, p=0.0004; r=-0.4, p=0.03). Taken together, the current results suggest a relationship between BRI2 protein changes, IDE activity and Aß levels in human hippocampus. Thus, the formation and accumulation high of molecular weight BRI2 forms observed in AD may impair IDE functioning and consequently lead to impaired Aß clearance and to the accumulation of Aß.

BRI2 ectodomain affects Aß42 fibrillation and tau truncation in human neuroblastoma cells.

Alzheimer's disease (AD) is pathologically characterized by the presence of misfolded proteins such as amyloid beta (Aß) in senile plaques, and hyperphosphorylated tau and truncated tau in neurofibrillary tangles (NFT). The BRI2 protein inhibits Aß aggregation via its BRICHOS domain and regulates critical proteins involved in initiating the amyloid cascade, which has been hypothesized to be central in AD pathogenesis. We recently detected the deposition of BRI2 ectodomain associated with Aß plaques and concomitant changes in its processing enzymes in early stages of AD. Here, we aimed to investigate the effects of recombinant BRI2 ectodomain (rBRI276-266) on Aß aggregation and on important molecular pathways involved in early stages of AD, including the unfolded protein response (UPR), phosphorylation and truncation of tau, as well as apoptosis. We found that rBRI276-266 delays Aß fibril formation, although less efficiently than the BRI2 BRICHOS domain (BRI2 residues 113-231). In human neuroblastoma SH-SY5Y cells, rBRI276-266 slightly decreased cell viability and increased up to two-fold the Bax/Bcl-2 ratio and the subsequent activity of caspases 3 and 9, indicating activation of apoptosis. rBRI276-266 upregulated the chaperone BiP but did not modify the mRNA expression of other UPR markers (CHOP and Xbp-1). Strikingly, rBRI276-266 induced the activation of GSK3ß but not the phosphorylation of tau. However, exposure to rBRI276-266 significantly induced the truncation of tau, indicating that BRI2 ectodomain can contribute to NFT formation. Since BRI2 can also regulate the metabolism of Aß, the current data suggests that BRI2 ectodomain is a potential nexus between Aß, tau pathology and neurodegeneration.

Application of serum natalizumab levels during plasma exchange in MS patients with progressive multifocal leukoencephalopathy.

Progressive multifocal leukoencephalopathy (PML) is a severe complication of natalizumab treatment. Restoring immune function by plasmapheresis/immunoadsorption (PLEX/IA) is important for the outcome of PML. We report on four multiple sclerosis (MS) patients whom developed PML during natalizumab treatment, in whom we measured serum natalizumab concentrations before and during PLEX. Depending on the serum natalizumab concentration at the time of PML diagnosis, the number of PLEX treatments necessary to reach subtherapeutic serum natalizumab concentrations is variable. Measuring serum natalizumab concentrations before and during PLEX is helpful to determine the optimum number of PLEX treatments in individual MS patients with PML.