C1q is increased in cerebrospinal fluid-derived extracellular vesicles in Alzheimer's disease: A multi-cohort proteomics and immuno-assay validation study.

INTRODUCTION: Extracellular vesicles (EVs) may propagate and modulate Alzheimer's disease (AD) pathology. We aimed to comprehensively characterize the proteome of cerebrospinal fluid (CSF) EVs to identify proteins and pathways altered in AD. METHODS: CSF EVs were isolated by ultracentrifugation (Cohort 1) or Vn96 peptide (Cohort 2) from non-neurodegenerative controls (n = 15, 16) and AD patients (n = 22, 20, respectively). EVs were subjected to untargeted quantitative mass spectrometry-based proteomics. Results were validated by enzyme-linked immunosorbent assay (ELISA) in Cohorts 3 and 4, consisting of controls (n = 16, n = 43, (Cohort3, Cohort4)), and patients with AD (n = 24, n = 100). RESULTS: We found > 30 differentially expressed proteins in AD CSF EVs involved in immune-regulation. Increase of C1q levels in AD compared to non-demented controls was validated by ELISA (∼ 1.5 fold, p (Cohort 3) = 0.03, p (Cohort 4) = 0.005). DISCUSSION: EVs may be utilized as a potential biomarker and may play a so far unprecedented role in immune-regulation in AD.

Evaluation of the methoxy-X04 derivative BSC4090 for diagnosis of prodromal and early Alzheimer's disease from bioptic olfactory mucosa.

Alzheimer's disease (AD) pathology precedes the onset of clinical symptoms by several decades. Thus, biomarkers are required to identify prodromal disease stages to allow for the early and effective treatment. The methoxy-X04-derivative BSC4090 is a fluorescent ligand which was designed to target neurofibrillary tangles in AD. BSC4090 staining was previously detected in post-mortem brains and olfactory mucosa derived from AD patients. We tested BSC4090 as a potential diagnostic marker of prodromal and early AD using olfactory mucosa biopsies from 12 individuals with AD, 13 with mild cognitive impairment (MCI), and 10 cognitively normal (CN) controls. Receiver-operating curve analysis revealed areas under the curve of 0.78 for AD versus CN and of 0.86 for MCI due to AD versus MCI of other causes. BSC4090 labeling correlated significantly with cerebrospinal fluid levels of tau protein phosphorylated at T181. Using NMR spectroscopy, we find that BSC4090 binds to fibrillar and pre-fibrillar but not to monomeric tau. Thus, BSC4090 may be an interesting candidate to detect AD at the early disease stages.

Induction of α-synuclein aggregate formation by CSF exosomes from patients with Parkinson's disease and dementia with Lewy bodies.

Extracellular α-synuclein has been proposed as a crucial mechanism for induction of pathological aggregate formation in previously healthy cells. In vitro, extracellular α-synuclein is partially associated with exosomal vesicles. Recently, we have provided evidence that exosomal α-synuclein is present in the central nervous system in vivo. We hypothesized that exosomal α-synuclein species from patients with α-synuclein related neurodegeneration serve as carriers for interneuronal disease transmission. We isolated exosomes from cerebrospinal fluid from patients with Parkinson's disease, dementia with Lewy bodies, progressive supranuclear palsy as a non-α-synuclein related disorder that clinically overlaps with Parkinson's disease, and neurological controls. Cerebrospinal fluid exosome numbers, α-synuclein protein content of cerebrospinal fluid exosomes and their potential to induce oligomerization of α-synuclein were analysed. The quantification of cerebrospinal fluid exosomal α-synuclein showed distinct differences between patients with Parkinson's disease and dementia with Lewy bodies. In addition, exosomal α-synuclein levels correlated with the severity of cognitive impairment in cross-sectional samples from patients with dementia with Lewy bodies. Importantly, cerebrospinal fluid exosomes derived from Parkinson's disease and dementia with Lewy bodies induce oligomerization of α-synuclein in a reporter cell line in a dose-dependent manner. Our data suggest that cerebrospinal fluid exosomes from patients with Parkinson's disease and dementia with Lewy bodies contain a pathogenic species of α-synuclein, which could initiate oligomerization of soluble α-synuclein in target cells and confer disease pathology.

Extracellular vesicle sorting of α-Synuclein is regulated by sumoylation.

Extracellular α-Synuclein has been implicated in interneuronal propagation of disease pathology in Parkinson's Disease. How α-Synuclein is released into the extracellular space is still unclear. Here, we show that α-Synuclein is present in extracellular vesicles in the central nervous system. We find that sorting of α-Synuclein in extracellular vesicles is regulated by sumoylation and that sumoylation acts as a sorting factor for targeting of both, cytosolic and transmembrane proteins, to extracellular vesicles. We provide evidence that the SUMO-dependent sorting utilizes the endosomal sorting complex required for transport (ESCRT) by interaction with phosphoinositols. Ubiquitination of cargo proteins is so far the only known determinant for ESCRT-dependent sorting into the extracellular vesicle pathway. Our study reveals a function of SUMO protein modification as a Ubiquitin-independent ESCRT sorting signal, regulating the extracellular vesicle release of α-Synuclein. We deciphered in detail the molecular mechanism which directs α-Synuclein into extracellular vesicles which is of highest relevance for the understanding of Parkinson's disease pathogenesis and progression at the molecular level. We furthermore propose that sumo-dependent sorting constitutes a mechanism with more general implications for cell biology.

Patient knowledge about risk factors, achievement of target values and guideline adherent secondary prevention therapies 12 months after acute myocardial infarction.

AIMS: The prospective GULLIVE-R study aimed to evaluate adherence to guideline recommended secondary prevention, physicians' and patients' estimation of cardiac risk, and patients' knowledge about target values of risk factors after acute myocardial infarction (AMI). METHODS: We performed a prospective study enrolling patients 9-12 months after AMI. Guideline recommended secondary prevention therapies and physicians as well as patients' estimation about their risk, and patients' knowledge about target values were prospectively collected. RESULTS: Between 07/2019 and 06/2021 a total of 2509 outpatients were enrolled in 150 German centers 10 months after AMI. The mean age was 66 years, 26.4% were women, 45.3% had STEMI, 54.7% had NSTEMI, 93.6% had revascularization (84.0% PCI, 7.4% CABG, 1.8% both). Guideline recommended secondary drug therapies were prescribed in over 80% of patients, while only about 50% received all five recommended drugs (aspirin, P2Y12 inhibitors, statins, beta-blockers, RAAS inhibitors) and regular exercise was performed by only one third. About 90% of patients felt well informed about secondary prevention, but the correct target value for blood pressure was known in only 37.9% and for LDL-C in only 8.2%. Both, physicians and patients underestimated the objective risk for future AMIs as determined by the TIMI risk score for secondary prevention. CONCLUSIONS: There is still room for improvement in patient education and implementation of guideline recommended non-pharmacological and pharmacological secondary prevention therapies in patients in the chronic phase after AMI.

Bullet points: Between 07/2019 and 06/2021 a total of 2509 outpatients were enrolled in 150 German centers 10 months after AMI. Guideline recommended secondary drug therapies were applied in over 80% of patients, while only about 50% received all five recommended drugs (aspirin, P2Y12 inhibitors, statins, beta-blockers, RAAS inhibitors) and regular exercise was performed by only one third. About 90% of patients felt well informed about secondary prevention, but the correct target value for blood pressure was known in only 37.9% and for LDL-C in only 8.2%. ESC recommended target values for systolic blood pressure and LDL-cholesterol were achieved in 38.8% and 36.0%, respectively. There was an underestimation of risk for future AMIs as determined by the TIMI Risk Score for Secondary Prevention (TRS2P) both by physicians and patients.