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Cerebral amyloid angiopathy (CAA) is an age-related condition and a major cause of intracerebral hemorrhage and cognitive decline that shows close links with Alzheimer's disease (AD). CAA is characterized by the aggregation of amyloid-β (Aβ) peptides and formation of Aβ deposits in the brain vasculature resulting in a disruption of the angioarchitecture. Capillaries are a critical site of Aβ pathology in CAA type 1 and become dysfunctional during disease progression. Here, applying an advanced protocol for the isolation of parenchymal microvessels from post-mortem brain tissue combined with liquid chromatography tandem mass spectrometry (LC–MS/MS), we determined the proteomes of CAA type 1 cases (n = 12) including a patient with hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D), and of AD cases without microvascular amyloid pathology (n = 13) in comparison to neurologically healthy controls (n = 12). ELISA measurements revealed microvascular Aβ1-40 levels to be exclusively enriched in CAA samples (mean: > 3000-fold compared to controls). The proteomic profile of CAA type 1 was characterized by massive enrichment of multiple predominantly secreted proteins and showed significant overlap with the recently reported brain microvascular proteome of patients with cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a hereditary cerebral small vessel disease (SVD) characterized by the aggregation of the Notch3 extracellular domain. We found this overlap to be largely attributable to the accumulation of high-temperature requirement protein A1 (HTRA1), a serine protease with an established role in the brain vasculature, and several of its substrates. Notably, this signature was not present in AD cases. We further show that HTRA1 co-localizes with Aβ deposits in brain capillaries from CAA type 1 patients indicating a pathologic recruitment process. Together, these findings suggest a central role of HTRA1-dependent protein homeostasis in the CAA microvasculature and a molecular connection between multiple types of brain microvascular disease. [ABSTRACT FROM AUTHOR]

This study investigated the capability of electromembrane extraction (EME) as a general technique for peptides, by extracting complex pools of peptides comprising in total of 5953 different substances, varying in size from seven to 16 amino acids. Electromembrane extraction was conducted from a sample adjusted to pH 3.0 and utilized a liquid membrane consisting of 2‐nitrophenyl octyl ether and carvacrol (1:1 w/w), containing 2% (w/w) di(2‐ethylhexyl) phosphate. The acceptor phase was 50 mM phosphoric acid (pH 1.8), the extraction time was 45 min, and 10 V was used. High extraction efficiency, defined as a higher peptide signal in the acceptor than the sample after extraction, was achieved for 3706 different peptides. Extraction efficiencies were predominantly influenced by the hydrophobicity of the peptides and their net charge in the sample. Hydrophobic peptides were extracted with a net charge of +1, while hydrophilic peptides were extracted when the net charge was +2 or higher. A computational model based on machine learning was developed to predict the extractability of peptides based on peptide descriptors, including the grand average of hydropathy index and net charge at pH 3.0 (sample pH). This research shows that EME has general applicability for peptides and represents the first steps toward in silico prediction of extraction efficiency. [ABSTRACT FROM AUTHOR]

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and a phenotypically similar recessive condition (CARASIL) have emerged as important genetic model diseases for studying the molecular pathomechanisms of cerebral small vessel disease (SVD). CADASIL, the most frequent and intensely explored monogenic SVD, is characterized by a severe pathology in the cerebral vasculature including the mutation-induced aggregation of the Notch3 extracellular domain (Notch3ECD) and the formation of protein deposits of insufficiently determined composition in vessel walls. To identify key molecules and pathways involved in this process, we quantitatively determined the brain vessel proteome from CADASIL patient and control autopsy samples (n = 6 for each group), obtaining 95 proteins with significantly increased abundance. Intriguingly, high-temperature requirement protein A1 (HTRA1), the extracellular protease mutated in CARASIL, was found to be strongly enriched (4.9-fold, p = 1.6 × 10−3) and to colocalize with Notch3ECD deposits in patient vessels suggesting a sequestration process. Furthermore, the presence of increased levels of several HTRA1 substrates in the CADASIL proteome was compatible with their reduced degradation as consequence of a loss of HTRA1 activity. Indeed, a comparison with the brain vessel proteome of HTRA1 knockout mice (n = 5) revealed a highly significant overlap of 18 enriched proteins (p = 2.2 × 10−16), primarily representing secreted and extracellular matrix factors. Several of them were shown to be processed by HTRA1 in an in vitro proteolysis assay identifying them as novel substrates. Our study provides evidence for a loss of HTRA1 function as a critical step in the development of CADASIL pathology linking the molecular mechanisms of two distinct SVD forms. [ABSTRACT FROM AUTHOR]

Ischemic stroke is a major global health issue and characterized by acute vascular dysfunction and subsequent neuroinflammation. However, the relationship between these processes remains elusive. In the current study, we investigated whether alleviating vascular dysfunction by restoring vascular nitric oxide (NO) reduces post-stroke inflammation. Mice were subjected to experimental stroke and received inhaled NO (iNO; 50 ppm) after reperfusion. iNO normalized vascular cyclic guanosine monophosphate (cGMP) levels, reduced the elevated expression of intercellular adhesion molecule-1 (ICAM-1), and returned leukocyte adhesion to baseline levels. Reduction of vascular pathology significantly reduced the inflammatory cytokines interleukin-1β (Il-1β), interleukin-6 (Il-6), and tumor necrosis factor-α (TNF-α), within the brain parenchyma. These findings suggest that vascular dysfunction is responsible for leukocyte adhesion and that these processes drive parenchymal inflammation. Reversing vascular dysfunction may therefore emerge as a novel approach to diminish neuroinflammation after ischemic stroke and possibly other ischemic disorders. [ABSTRACT FROM AUTHOR]

: Theo Rein and colleagues examine the role of FKBP51 in the actions of antidepressants, with a particular focus on pathways of autophagy. Please see later in the article for the Editors' Summary [ABSTRACT FROM AUTHOR]