Different inflammatory signatures based on CSF biomarkers relate to preserved or diminished brain structure and cognition.

Neuroinflammation is a hallmark of Alzheimer's disease (AD) and both positive and negative associations of individual inflammation-related markers with brain structure and cognitive function have been described. We aimed to identify inflammatory signatures of CSF immune-related markers that relate to changes of brain structure and cognition across the clinical spectrum ranging from normal aging to AD. A panel of 16 inflammatory markers, Aß42/40 and p-tau181 were measured in CSF at baseline in the DZNE DELCODE cohort (n = 295); a longitudinal observational study focusing on at-risk stages of AD. Volumetric maps of gray and white matter (GM/WM; n = 261) and white matter hyperintensities (WMHs, n = 249) were derived from baseline MRIs. Cognitive decline (n = 204) and the rate of change in GM volume was measured in subjects with at least 3 visits (n = 175). A principal component analysis on the CSF markers revealed four inflammatory components (PCs). Of these, the first component PC1 (highly loading on sTyro3, sAXL, sTREM2, YKL-40, and C1q) was associated with older age and higher p-tau levels, but with less pathological Aß when controlling for p-tau. PC2 (highly loading on CRP, IL-18, complement factor F/H and C4) was related to male gender, higher body mass index and greater vascular risk. PC1 levels, adjusted for AD markers, were related to higher GM and WM volumes, less WMHs, better baseline memory, and to slower atrophy rates in AD-related areas and less cognitive decline. In contrast, PC2 related to less GM and WM volumes and worse memory at baseline. Similar inflammatory signatures and associations were identified in the independent F.ACE cohort. Our data suggest that there are beneficial and detrimental signatures of inflammatory CSF biomarkers. While higher levels of TAM receptors (sTyro/sAXL) or sTREM2 might reflect a protective glia response to degeneration related to phagocytic clearance, other markers might rather reflect proinflammatory states that have detrimental impact on brain integrity.

NfL reliability across laboratories, stage-dependent diagnostic performance and matrix comparability in genetic FTD: a large GENFI study.

BACKGROUND: Blood neurofilament light chain (NfL) is increasingly considered as a key trial biomarker in genetic frontotemporal dementia (gFTD). We aimed to facilitate the use of NfL in gFTD multicentre trials by testing its (1) reliability across labs; (2) reliability to stratify gFTD disease stages; (3) comparability between blood matrices and (4) stability across recruiting sites. METHODS: Comparative analysis of blood NfL levels in a large gFTD cohort (GENFI) for (1)-(4), with n=344 samples (n=148 presymptomatic, n=11 converter, n=46 symptomatic subjects, with mutations in C9orf72, GRN or MAPT; and n=139 within-family controls), each measured in three different international labs by Simoa HD-1 analyzer. RESULTS: NfL revealed an excellent consistency (intraclass correlation coefficient (ICC) 0.964) and high reliability across the three labs (maximal bias (pg/mL) in Bland-Altman analysis: 1.12±1.20). High concordance of NfL across laboratories was moreover reflected by high areas under the curve for discriminating conversion stage against the (non-converting) presymptomatic stage across all three labs. Serum and plasma NfL were largely comparable (ICC 0.967). The robustness of NfL across 13 recruiting sites was demonstrated by a linear mixed effect model. CONCLUSIONS: Our results underline the suitability of blood NfL in gFTD multicentre trials, including cross-lab reliable stratification of the highly trial-relevant conversion stage, matrix comparability and cross-site robustness.

GAA-FGF14 ataxia (SCA27B): phenotypic profile, natural history progression and 4-aminopyridine treatment response.

Ataxia due to an autosomal dominant intronic GAA repeat expansion in FGF14 [GAA-FGF14 ataxia, spinocerebellar ataxia 27B (SCA27B)] has recently been identified as one of the most common genetic late-onset ataxias. We here aimed to characterize its phenotypic profile, natural history progression, and 4-aminopyridine (4-AP) treatment response. We conducted a multi-modal cohort study of 50 GAA-FGF14 patients, comprising in-depth phenotyping, cross-sectional and longitudinal progression data (up to 7 years), MRI findings, serum neurofilament light (sNfL) levels, neuropathology, and 4-AP treatment response data, including a series of n-of-1 treatment studies. GAA-FGF14 ataxia consistently presented as late-onset [60.0 years (53.5-68.5), median (interquartile range)] pancerebellar syndrome, partly combined with afferent sensory deficits (55%) and dysautonomia (28%). Dysautonomia increased with duration while cognitive impairment remained infrequent, even in advanced stages. Cross-sectional and longitudinal assessments consistently indicated mild progression of ataxia [0.29 Scale for the Assessment and Rating of Ataxia (SARA) points/year], not exceeding a moderate disease severity even in advanced stages (maximum SARA score: 18 points). Functional impairment increased relatively slowly (unilateral mobility aids after 8 years in 50% of patients). Corresponding to slow progression and low extra-cerebellar involvement, sNfL was not increased relative to controls. Concurrent second diseases (including progressive supranuclear palsy neuropathology) represented major individual aggravators of disease severity, constituting important caveats for planning future GAA-FGF14 trials. A treatment response to 4-AP with relevance for everyday living was reported by 86% of treated patients. A series of three prospective n-of-1 treatment experiences with on/off design showed marked reduction in daily symptomatic time and symptom severity on 4-AP. Our study characterizes the phenotypic profile, natural history progression, and 4-AP treatment response of GAA-FGF14 ataxia. It paves the way towards large-scale natural history studies and 4-AP treatment trials in this newly discovered, possibly most frequent, and treatable late-onset ataxia.

Transmission of amyloid-ß protein pathology from cadaveric pituitary growth hormone.

We previously reported1 the presence of amyloid-ß protein (Aß) deposits in individuals with Creutzfeldt-Jakob disease (CJD) who had been treated during childhood with human cadaveric pituitary-derived growth hormone (c-hGH) contaminated with prions. The marked deposition of parenchymal and vascular Aß in these relatively young individuals with treatment-induced (iatrogenic) CJD (iCJD), in contrast to other prion-disease patients and population controls, allied with the ability of Alzheimer's disease brain homogenates to seed Aß deposition in laboratory animals, led us to argue that the implicated c-hGH batches might have been contaminated with Aß seeds as well as with prions. However, this was necessarily an association, and not an experimental, study in humans and causality could not be concluded. Given the public health importance of our hypothesis, we proceeded to identify and biochemically analyse archived vials of c-hGH. Here we show that certain c-hGH batches to which patients with iCJD and Aß pathology were exposed have substantial levels of Aß40, Aß42 and tau proteins, and that this material can seed the formation of Aß plaques and cerebral Aß-amyloid angiopathy in intracerebrally inoculated mice expressing a mutant, humanized amyloid precursor protein. These results confirm the presence of Aß seeds in archived c-hGH vials and are consistent with the hypothesized iatrogenic human transmission of Aß pathology. This experimental confirmation has implications for both the prevention and the treatment of Alzheimer's disease, and should prompt a review of the risk of iatrogenic transmission of Aß seeds by medical and surgical procedures long recognized to pose a risk of accidental prion transmission2,3.

Evolution of Clinical Outcome Measures and Biomarkers in Sporadic Adult-Onset Degenerative Ataxia.

BACKGROUND: Sporadic adult-onset ataxias without known genetic or acquired cause are subdivided into multiple system atrophy of cerebellar type (MSA-C) and sporadic adult-onset ataxia of unknown etiology (SAOA). OBJECTIVES: To study the differential evolution of both conditions including plasma neurofilament light chain (NfL) levels and magnetic resonance imaging (MRI) markers. METHODS: SPORTAX is a prospective registry of sporadic ataxia patients with an onset >40 years. Scale for the Assessment and Rating of Ataxia was the primary outcome measure. In subgroups, blood samples were taken and MRIs performed. Plasma NfL was measured via a single molecule assay. Regional brain volumes were automatically measured. To assess signal changes, we defined the pons and middle cerebellar peduncle abnormality score (PMAS). Using mixed-effects models, we analyzed changes on a time scale starting with ataxia onset. RESULTS: Of 404 patients without genetic diagnosis, 130 met criteria of probable MSA-C at baseline and 26 during follow-up suggesting clinical conversion to MSA-C. The remaining 248 were classified as SAOA. At baseline, NfL, cerebellar white matter (CWM) and pons volume, and PMAS separated MSA-C from SAOA. NfL decreased in MSA-C and did not change in SAOA. CWM and pons volume decreased faster, whereas PMAS increased faster in MSA-C. In MSA-C, pons volume had highest sensitivity to change, and PMAS was a predictor of faster progression. Fulfillment of possible MSA criteria, NfL and PMAS were risk factors, CWM and pons volume protective factors for conversion to MSA-C. CONCLUSIONS: This study provides detailed information on differential evolution and prognostic relevance of biomarkers in MSA-C and SAOA. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Standards of Fluid Biomarker Collection and Pre-analytical Processes in Humans and Mice: Recommendations by the Ataxia Global Initiative Working Group on Biomarkers.

The Ataxia Global Initiative (AGI) aims to serve as a platform to facilitate clinical trial readiness for the hereditary ataxias. Clinical trials for these diseases have been hampered by the lack of objective measures to study disease onset, progression, and treatment efficacy. While these issues are not unique to the genetic ataxias, the relative rarity of these diseases makes the need for such measures even more pressing to achieve statistical power in clinical trials. In this report, we have described the efforts of the AGI fluid biomarker working group (WG) in developing uniform protocols for biomarker sampling and storage, both for human and preclinical studies in mice. By reducing collection variability, we anticipate reduced noise in downstream biomarker analysis that will improve statistical power and minimize the necessary sample size. The emphasis has been on defining and standardizing the sampling and pre-analytical work-up of minimal set of biological samples, specifically blood plasma and serum, keeping in mind the need for harmonization of collection and storage that can be achieved with relatively limited cost and resources. An optional package is detailed for those centers that have the resources and commitment for additional biofluids/sample processing and storage. Finally, we have delineated similar standardized protocols for mice that will be important for preclinical studies in the field.

Fc N-glycosylation of autoreactive Aß antibodies as a blood-based biomarker for Alzheimer's disease.

INTRODUCTION: Naturally occurring autoantibodies (nAbs) against the pathologic isoform of amyloid beta (Aß42 ) were found in body fluids and indicate a systemic B cell response that may prevent Alzheimer's disease (AD) onset. N-glycans attached to immunoglobulin G-Fab/Fc fragments are features that influence their mechanism of action. The aim was to study the role of N-glycans in nAbs-Aß42 . METHODS: nAbs-Aß42 were isolated from AD patients and age-/sex-matched controls (n = 40) and immunoglobulin preparations. Glycosylated/deglycosylated nAbs-Aß42 were analyzed for their effect on Aß42 's aggregation, toxicity, and phagocytosis. Glycan structure was analyzed using matrix assisted laser desorption ionization time of flight mass spectrometry. RESULTS: Deglycosylation of nAbs-Aß42 had a major impact on Aß42 's aggregation/toxicity/phagocytosis. The glycan structure showed considerable differences between AD and controls. We were able to predict disease status with a sensitivity/specificity of 95% (confidence interval [CI]: 76.4-99.7%)/100% (CI: 83.9-100%). DISCUSSION: N-glycosylation has been identified as a critical attribute maintaining the beneficial effects of autoreactive Aß antibodies. These data have consequences for the development of monocloncal Aß antibodies and may open new avenues for diagnostics.

Plasma NT1 Tau is a Specific and Early Marker of Alzheimer's Disease.

OBJECTIVE: There is an urgent need for sensitive, widely available, blood-based screening tests to identify presymptomatic individuals destined to develop Alzheimer's disease (AD). We investigated whether tau detected in plasma by our in-house NT1 assay is specifically altered in AD, and when applied to patients with subjective cognitive decline (SCD) or mild cognitive impairment (MCI) can serve to predict progression to AD dementia. The predictive value of NT1 versus tau measured using assays from Quanterix and Roche, and the specificity of NT1 for AD versus a nonspecific marker of neurodegeneration (neurofilament light [NfL]) were also examined. METHODS: NT1 tau and NfL were measured in plasma from prospectively followed patients with SCD or MCI who remained cognitively stable, converted to AD dementia, or converted to non-AD dementias, and in cognitively unimpaired participants. Tau was measured using Quanterix and Roche assays in baseline subjects with SCD and MCI. RESULTS: Plasma NT1 tau was specifically elevated in AD, but not in non-AD dementia compared with controls, whereas NfL was increased in both AD and non-AD dementias. Baseline specimens from individuals who had SCD or MCI revealed that NT1 tau, but not tau measured using Quanterix or Roche assays, is elevated in subjects who progress to AD dementia. As expected, baseline plasma NfL is elevated in those who progress to AD and non-AD dementias. INTERPRETATION: Plasma NT1 tau is a specific marker of AD, which is elevated early in disease and may prove useful as a first round screen to identify individuals at risk of developing AD. ANN NEUROL 2020;88:878-892.

Longitudinal plasma p-tau217 is increased in early stages of Alzheimer's disease.

Plasma levels of tau phosphorylated at threonine-217 (p-tau217) is a candidate tool to monitor Alzheimer's disease. We studied 150 cognitively unimpaired participants and 100 patients with mild cognitive impairment in the Swedish BioFINDER study. P-tau217 was measured repeatedly for up to 6 years (median three samples per person, median time from first to last sample, 4.3 years). Preclinical (amyloid-ß-positive cognitively unimpaired, n = 62) and prodromal (amyloid-ß-positive mild cognitive impairment, n = 49) Alzheimer's disease had accelerated p-tau217 compared to amyloid-ß-negative cognitively unimpaired (ß = 0.56, P < 0.001, using linear mixed effects models) and amyloid-ß-negative mild cognitive impairment patients (ß = 0.67, P < 0.001), respectively. Mild cognitive impairment patients who later converted to Alzheimer's disease dementia (n = 40) had accelerated p-tau217 compared to other mild cognitive impairment patients (ß = 0.79, P < 0.001). P-tau217 did not change in amyloid-ß-negative participants, or in patients with mild cognitive impairment who did not convert to Alzheimer's disease dementia. For 80% power, 109 participants per arm were required to observe a slope reduction in amyloid-ß-positive cognitively unimpaired (71 participants per arm in amyloid-ß-positive mild cognitive impairment). Longitudinal increases in p-tau217 correlated with longitudinal worsening of cognition and brain atrophy. In summary, plasma p-tau217 increases during early Alzheimer's disease and can be used to monitor disease progression.

Target engagement in an alzheimer trial: Crenezumab lowers amyloid ß oligomers in cerebrospinal fluid.

OBJECTIVE: Oligomeric forms of amyloid ß protein (oAß) are believed to be principally responsible for neurotoxicity in Alzheimer disease (AD), but it is not known whether anti-Aß antibodies are capable of lowering oAß levels in humans. METHODS: We developed an ultrasensitive immunoassay and used it to measure oAß in cerebrospinal fluid (CSF) from 104 AD subjects participating in the ABBY and BLAZE phase 2 trials of the anti-Aß antibody crenezumab. Patients received subcutaneous (SC) crenezumab (300mg) or placebo every 2 weeks, or intravenous (IV) crenezumab (15mg/kg) or placebo every 4 weeks for 68 weeks. Ninety-eight of the 104 patients had measurable baseline oAß levels, and these were compared to levels at week 69 in placebo (n = 28), SC (n = 35), and IV (n = 35) treated patients. RESULTS: Among those receiving crenezumab, 89% of SC and 86% of IV patients had lower levels of oAß at week 69 versus baseline. The difference in the proportion of patients with decreasing levels was significant for both treatment arms: p = 0.0035 for SC and p = 0.01 for IV crenezumab versus placebo. The median percentage change was -48% in the SC arm and -43% in the IV arm. No systematic change was observed in the placebo group, with a median change of -13% and equivalent portions with negative and positive change. INTERPRETATION: Crenezumab lowered CSF oAß levels in the large majority of treated patients tested. These results support engagement of the principal pathobiological target in AD and identify CSF oAß as a novel pharmacodynamic biomarker for use in trials of anti-Aß agents. ANN NEUROL 2019;86:215-224.

Learnings about the complexity of extracellular tau aid development of a blood-based screen for Alzheimer's disease.

INTRODUCTION: The tau protein plays a central role in Alzheimer's disease (AD), and there is huge interest in measuring tau in blood and cerebrospinal fluid (CSF). METHODS: We developed a set of immunoassays to measure tau in specimens from humans diagnosed based on current best clinical and CSF biomarker criteria. RESULTS: In CSF, mid-region- and N-terminal-detected tau predominated and rose in disease. In plasma, an N-terminal assay (NT1) detected elevated levels of tau in AD and AD-mild cognitive impairment (MCI). Plasma NT1 measurements separated controls from AD-MCI (area under the curve [AUC] = 0.88) and AD (AUC = 0.96) in a discovery cohort and in a Validation Cohort (with AUCs = 0.79 and 0.75, respectively). DISCUSSION: The forms of tau in CSF and plasma are distinct, but in each specimen type, the levels of certain fragments are increased in AD. Measurement of plasma NT1 tau should be aggressively pursued as a potential blood-based screening test for AD/AD-MCI.

Costs of illness in chronic inflammatory demyelinating polyneuropathy in Germany.

INTRODUCTION: Cost of illness studies are essential to estimate societal costs of chronic inflammatory demyelinating polyneuropathy (CIDP) and identify cost-driving factors. METHODS: In total, 108 patients were recruited from 3 specialized neuroimmunological clinics. Costs were calculated for a 3-month period, including direct and indirect costs. The following outcomes were assessed: inflammatory neuropathy cause and treatment disability scale, Mini-Mental State Examination, Beck Depression Inventory, Charlson comorbidity index, EuroQol-5D, World Health Organization quality of life instrument, and socioeconomic status. Univariate and multivariate analyses were applied to identify cost-driving factors. RESULTS: Total quarterly costs were €11,333. Direct costs contributed to 83% of total costs (€9,423), whereas indirect costs accounted for 17% (€1,910) of total costs. The cost of intravenous immunoglobulin (IVIg) was the main determinant of total costs (67%). Reduced health-related quality of life and depressive symptoms were identified as independent predictors of higher total costs. DISCUSSION: CIDP is associated with high societal costs, mainly resulting from the cost of IVIg treatment. Muscle Nerve 58: 681-687, 2018.

Detection of Aggregation-Competent Tau in Neuron-Derived Extracellular Vesicles.

Progressive cerebral accumulation of tau aggregates is a defining feature of Alzheimer's disease (AD). A popular theory that seeks to explain the apparent spread of neurofibrillary tangle pathology proposes that aggregated tau is passed from neuron to neuron. Such a templated seeding process requires that the transferred tau contains the microtubule binding repeat domains that are necessary for aggregation. While it is not clear how a protein such as tau can move from cell to cell, previous reports have suggested that this may involve extracellular vesicles (EVs). Thus, measurement of tau in EVs may both provide insights on the molecular pathology of AD and facilitate biomarker development. Here, we report the use of sensitive immunoassays specific for full-length (FL) tau and mid-region tau, which we applied to analyze EVs from human induced pluripotent stem cell (iPSC)-derived neuron (iN) conditioned media, cerebrospinal fluid (CSF), and plasma. In each case, most tau was free-floating with a small component inside EVs. The majority of free-floating tau detected by the mid-region assay was not detected by our FL assays, indicating that most free-floating tau is truncated. Inside EVs, the mid-region assay also detected more tau than the FL assay, but the ratio of FL-positive to mid-region-positive tau was higher inside exosomes than in free solution. These studies demonstrate the presence of minute amounts of free-floating and exosome-contained FL tau in human biofluids. Given the potential for FL tau to aggregate, we conclude that further investigation of these pools of extracellular tau and how they change during disease is merited.

[Inclusion Body Myopathy, Paget's Disease, and Fronto-temporal Dementia: a VCP-related Multi-systemic Proteinopathy]. / Einschlusskörpermyopathie, Paget-Krankheit und frontotemporale Demenz: eine VCP-bedingte, multisystemische Proteinopathie.

Mutations of the human VCP gene, which encodes the V: alosin C: ontaining P: rotein (synonyms: p97, TER ATPase), are associated with various multi-systemic protein aggregation diseases. We report on a patient with progressive myopathy and incipient cognitive deficits. A diagnostic muscle biopsy revealed an inclusion body myopathy with protein aggregates. Magnetic resonance imaging and F18-positron-emission-tomography disclosed a fronto-temporal atrophy and glucose hypometabolism of the frontal and temporal lobes, respectively. Based on the clinical findings, a genetic analysis was performed which revealed a heterozygous c.277C>T (p.Arg93Cys) mutation of the VCP gene, thus confirming the diagnosis of IBMPFD (I: nclusion B: ody M: yopathie with P: aget Disease of the Bones and F: ronto-temporal D: ementia).

α1-antitrypsin modulates microglial-mediated neuroinflammation and protects microglial cells from amyloid-ß-induced toxicity.

BACKGROUND: One hallmark of Alzheimer disease is microglial activation. Therapeutic approaches for this neurodegenerative disease include the modulation of microglial cells. α1-antitrypsin (A1AT) has been shown to exert anti-inflammatory effects on macrophages and lung epithelial cells and an inhibition of calpain activity in neutrophil granulocytes. Nothing is known about the effect of A1AT on microglial-mediated neuroinflammation. Our aim was to investigate the effect of A1AT on amyloid-ß (Aß)- and LPS-treated microglial cells in vitro with respect to cytokine production, stress pathways, cell viability, phagocytotic abilities and the underlying mechanisms. METHODS: Primary microglial cells were isolated from Swiss Webster mouse embryos on embryonic day 13.5. Cytokines in the supernatants of treated primary microglial cells were analyzed with ELISAs, and accumulated nitrite was detected with Griess reagents. Intracellular stress pathways were investigated in cell lysates using western blotting. Intracellular calcium levels were detected in BV-2 microglial cells loaded with the Ca2+-sensitive (fluorescent) dye Fluo-4. Calpain activity in primary microglial cells was assessed by using a calpain activity assay. Cell viability of Aß-treated microglial cells was analyzed using MTT assay. Phagocytosis of Aß was evaluated with western blot analysis. RESULTS: Upon co-administration, A1AT reduced pro-inflammatory mediators induced by LPS or Aß. Interestingly, we detected a reduction in calpain activity and in the concentration of intracellular calcium that might mediate the anti-inflammatory effects of A1AT. Inhibition of the classic activation pathways, such as phosphorylation of mitogen-activated protein kinases or activation of protein kinase A were excluded as a mechanism of A1AT-mediated effects. In addition, A1AT increased the viability of Aß-treated microglial cells and reduced Aß phagocytosis. CONCLUSIONS: We provide evidence on the mechanism of action of A1AT on microglial-mediated neuroinflammation in vitro. Our in vitro data indicate that A1AT treatment modulates microglial cells in inflammatory conditions and that this modulation is due to an inhibition of calpain activity and intracellular calcium levels. The underlying mechanisms of the effects observed here are promising for future therapeutic strategies and should thus be further pursued in transgenic mouse models of Alzheimer disease.

A systematic review of progranulin concentrations in biofluids in over 7,000 people-assessing the pathogenicity of GRN mutations and other influencing factors.

BACKGROUND: Pathogenic heterozygous mutations in the progranulin gene (GRN) are a key cause of frontotemporal dementia (FTD), leading to significantly reduced biofluid concentrations of the progranulin protein (PGRN). This has led to a number of ongoing therapeutic trials aiming to treat this form of FTD by increasing PGRN levels in mutation carriers. However, we currently lack a complete understanding of factors that affect PGRN levels and potential variation in measurement methods. Here, we aimed to address this gap in knowledge by systematically reviewing published literature on biofluid PGRN concentrations. METHODS: Published data including biofluid PGRN concentration, age, sex, diagnosis and GRN mutation were collected for 7071 individuals from 75 publications. The majority of analyses (72%) had focused on plasma PGRN concentrations, with many of these (56%) measured with a single assay type (Adipogen) and so the influence of mutation type, age at onset, sex, and diagnosis were investigated in this subset of the data. RESULTS: We established a plasma PGRN concentration cut-off between pathogenic mutation carriers and non-carriers of 74.8 ng/mL using the Adipogen assay based on 3301 individuals, with a CSF concentration cut-off of 3.43 ng/mL. Plasma PGRN concentration varied by GRN mutation type as well as by clinical diagnosis in those without a GRN mutation. Plasma PGRN concentration was significantly higher in women than men in GRN mutation carriers (p = 0.007) with a trend in non-carriers (p = 0.062), and there was a significant but weak positive correlation with age in both GRN mutation carriers and non-carriers. No significant association was seen with weight or with TMEM106B rs1990622 genotype. However, higher plasma PGRN levels were seen in those with the GRN rs5848 CC genotype in both GRN mutation carriers and non-carriers. CONCLUSIONS: These results further support the usefulness of PGRN concentration for the identification of the large majority of pathogenic mutations in the GRN gene. Furthermore, these results highlight the importance of considering additional factors, such as mutation type, sex and age when interpreting PGRN concentrations. This will be particularly important as we enter the era of trials for progranulin-associated FTD.

Mechanisms of action of naturally occurring antibodies against ß-amyloid on microglia.

BACKGROUND: Naturally occurring autoantibodies against amyloid-ß (nAbs-Aß) have been shown to exert beneficial effects on transgenic Alzheimer's disease (AD) animals in vivo and on primary neurons in vitro. Not much is known about their effect on microglial cells. Our aim was to investigate the effect of nAbs-Aß on amyloid-ß (Aß)-treated microglial cells in vitro with respect to cell viability, stress pathways, cytokine production and phagocytotic abilities and whether these effects can be conveyed to neurons. METHODS: Primary microglial cells isolated from Swiss Webster mouse mesencephalons on embryonic day 13.5 were pretreated with nAbs-Aß and then treated with Aß oligomers. After 3 hours, phagocytosis as well as western blot analysis were evaluated to measure the amount of phagocytized Aß. Cell viability was analyzed using an MTT assay 24 hours after treatment. Pro-inflammatory cytokines in the supernatants were analyzed with ELISAs and then we treated primary neuronal cells with these conditioned microglia supernatants. Twenty-four hours later we did a MTT assay of the treated neurons. We further investigated the effect of a single nAbs-Aß administration on Tg2576 mice in vivo. RESULTS: Upon co-administration of Aß and nAbs-Aß no change in microglia viability was observed. However, there was an increase in phosphorylated p38 protein level, an increase in the pro-inflammatory cytokines TNF-α and IL-6 and an increase in Aß uptake by microglial cells. Treatment of primary neurons with conditioned microglia medium led to a 10% improvement in cell viability when nAbs-Aß were co-administered compared to Aß-treated cells alone. We were unable to detect changes in cytokine production in brain lysates of Tg2576 mice. CONCLUSIONS: We provide evidence on the mechanism of action of nAbs-Aß on microglia in vitro. Interestingly, our in vivo data indicate that nAbs-Aß administration should be considered as a therapeutic strategy in AD, since there is no inflammatory reaction.

Blood neurofilament light chain levels are associated with disease progression in a transgenic SCA3 mouse model.

Increased neurofilament light (NfL) protein in biofluids is reflective of neurodegeneration and has gained interest as a biomarker across neurodegenerative diseases. In spinocerebellar ataxia type 3 (SCA3), the most common dominantly inherited ataxia, patients exhibit progressive NfL increases in peripheral blood when becoming symptomatic, remaining stably elevated throughout further disease course. However, progressive NfL changes are not yet validated in relevant preclinical SCA3 animal models, hindering its application as a biomarker during therapeutic development. We used ultra-sensitive single-molecule array (Simoa) to measure blood NfL over disease progression in the YACQ84 mouse, assessing relationships with measures of disease severity including age, CAG repeat size, and magnetic resonance spectroscopy. We show that YACQ84 mice exhibit increased blood NfL, concomitant with ataxia-related motor deficits and correlated with neurometabolite abnormalities. Our findings establish natural history progression of NfL increases in the preclinical YACQ84 mouse, further supporting the utility of blood NfL as a peripheral neurodegeneration biomarker and informing coinciding timelines of different measures of SCA3 pathogenesis. Summary statement: Peripheral blood of SCA3 YACQ84 mice exhibits increased abundance of neuronal-specific NfL protein directly associating with disease progression, providing an accessible disease biofluid biomarker to interrogate in preclinical therapeutic studies.

Blood levels of neurofilament light are associated with disease progression in a mouse model of spinocerebellar ataxia type 3.

Increased neurofilament light (NfL; NEFL) protein in biofluids is reflective of neurodegeneration and has gained interest as a biomarker across neurodegenerative diseases. In spinocerebellar ataxia type 3 (SCA3), the most common dominantly inherited ataxia, patients exhibit progressive NfL increases in peripheral blood when becoming symptomatic, and NfL remains stably elevated throughout further disease course. However, progressive NfL changes are not yet validated in relevant preclinical SCA3 animal models, hindering its application as a biomarker during therapeutic development. We used ultra-sensitive single-molecule array (Simoa) to measure blood NfL over disease progression in YACQ84 mice, a model of SCA3, assessing relationships with measures of disease severity including age, CAG repeat size and magnetic resonance spectroscopy. YACQ84 mice exhibited plasma NfL increases that were concomitant with ataxia-related motor deficits as well as increased serum NfL, which correlated with previously established neurometabolite abnormalities, two relevant measures of disease in patients with SCA3. Our findings establish the progression of NfL increases in the preclinical YACQ84 mouse, further supporting the utility of blood NfL as a peripheral neurodegeneration biomarker and informing on coinciding timelines of different measures of SCA3 pathogenesis.