Aβ-induced acceleration of Alzheimer-related τ-pathology spreading and its association with prion protein

Extracellular deposition of amyloid β-protein (Aβ) in amyloid plaques and intracellular accumulation of abnormally phosphorylated τ-protein (p-τ) in neurofibrillary tangles (NFTs) represent pathological hallmark lesions of Alzheimer's disease (AD). Both lesions develop in parallel in the human brain throughout the preclinical and clinical course of AD. Nevertheless, it is not yet clear whether there is a direct link between Aβ and τ pathology or whether other proteins are involved in this process. To address this question, we crossed amyloid precursor protein (APP) transgenic mice overexpressing human APP with the Swedish mutation (670/671 KM → NL) (APP23), human wild-type APP (APP51/16), or a proenkephalin signal peptide linked to human Aβ₄₂ (APP48) with τ-transgenic mice overexpressing human mutant 4-repeat τ-protein with the P301S mutation (TAU58). In 6-month-old APP23xTAU58 and APP51/16xTAU58 mice, soluble Aβ was associated with the aggravation of p-τ pathology propagation into the CA1/subiculum region, whereas 6-month-old TAU58 and APP48xTAU58 mice neither exhibited significant amounts of p-τ pathology in the CA1/subiculum region nor displayed significant levels of soluble Aβ in the forebrain. In APP23xTAU58 and APP51/16xTAU58 mice showing an acceleration of p-τ propagation, Aβ and p-τ were co-immunoprecipitated with cellular prion protein (PrP^C). A similar interaction between PrP^C, p-τ and Aβ was observed in human AD brains. This association was particularly noticed in 60% of the symptomatic AD cases in our sample, suggesting that PrP^C may play a role in the progression of AD pathology. An in vitro pull-down assay confirmed that PrP^C is capable of interacting with Aβ and p-τ. Using a proximity ligation assay, we could demonstrate proximity (less than ~ 30-40 nm distance) between PrP^C and Aβ and between PrP^C and p-τ in APP23xTAU58 mouse brain as well as in human AD brain. Proximity between PrP^C and p-τ was also seen in APP51/16xTAU58, APP48xTAU58, and TAU58 mice. Based on these findings, it is tempting to speculate that PrP^C is a critical player in the interplay between Aβ and p-τ propagation at least in a large group of AD cases. Preexisting p-τ pathology interacting with PrP^C, thereby, appears to be a prerequisite for Aβ to function as a p-τ pathology accelerator via PrP^C.

Fingerprints of CD8+ T cells on human pre-plasma and memory B cells

Differentiation of B cells is a stringently controlled multi-step process, which is still incompletely understood. Here we identify and characterize a rare population of human B cells, which surprisingly carry CD8AB on their surface. Existence of such cells was demonstrated both in tonsils and in human apheresis material. Gene expression profiling and real time PCR detected however no CD8A or CD8B message in these cells. Instead, we found that surface CD8 was hijacked from activated CD8+ T cells by a transfer process that required direct cell-to-cell contact. A focused transcriptome analysis at single cell level allowed the dissection of the CD8 positive B cell population. We found that the affected cells are characteristically of the CD27+CD200- phenotype, and consist of two discrete late-stage subpopulations that carry signatures of activated memory B like cells, and early plasmablasts. Thus, there is only a restricted time window in the differentiation process during which B cells can intimately interact with CD8+ T cells. The findings point to a novel link between the T and B arms of the adaptive immune system, and suggest that CD8+ T cells have the capability to directly shape the global antibody repertoire.

Deletion of the EGF receptor in vascular smooth muscle cells prevents chronic angiotensin II-induced arterial wall stiffening and media thickening

AIM

In vivo vascular smooth muscle cell (VSMC) EGF receptor (EGFR) contributes to acute angiotensin II (AII) effects on vascular tone and blood pressure. The ubiquitously expressed EGFR has been implicated in vascular remodelling preceding end-organ damage by pharmacological inhibition, and AII signalling in cultured vascular cells is partly EGFR-dependent. However, the role of VSMC-EGFR in vivo during AII-induced pathophysiological processes is not known.

METHODS

This study assesses the in vivo relevance of VSMC-EGFR during chronic AII challenge without further stressors, using a mouse model with inducible, VSMC-specific EGFR knock out (VSMC-EGFR-KO). In these mice functional and structural vascular, renal and cardiac effects or biomarkers were investigated in vivo and ex vivo.

RESULTS

Vascular smooth muscle cell-EGFR-KO prevented AII-induced media hypertrophy of mesenteric arteries, renal arterioles and the aorta, VSMC ERK1/2-phosphorylation as well as the impairment of vascular compliance. Furthermore, induction of vascular fibrosis, creatinineamia, renal interstitial fibrosis as well as the increase in fractional water excretion was prevented. AII-induced increase in systolic blood pressure was mitigated. By contrast, endothelial dysfunction, induction of vascular inflammatory marker mRNA and albuminuria were not inhibited. Cardiac and cardiomyocyte hypertrophy were also not prevented by VSMC-EGFR-KO.

CONCLUSION

Vascular smooth muscle cell-EGFRs are relevant for pathological AII action in vivo. Our data show in vivo and ex vivo the necessity of VSMC-EGFR for AII-induced structural and functional vascular remodelling, not including endothelial dysfunction. Hereby, VSMC-EGFR gains importance for complete AII-induced renal end-organ damage succeeding vascular remodelling.

[Subjective Aspects of Return to Work and Social Reintegration in Patients with Extensive Work-related Problems in Cardiac Rehabilitation - Results of a Qualitative Investigation]

This study investigated subjective biopsychosocial effects of coronary heart disease (CHD), coping strategies and social support in patients undergoing cardiac rehabilitation (CR) and having extensive work-related problems. A qualitative investigation was performed in 17 patients (48.9±7.0 y, 13 male) with extensive work-related problems (SIMBO-C>30). All patients were interviewed with structured surveys. Data analysis was performed using a software that is based on the content analysis approach of Mayring. In regard to effects of disease, patients indicated social aspects including occupational aspects (62%) more often than physical or mental factors (9 or 29%). Applied coping strategies and support services are mainly focused on physical impairments (70 or 45%). The development of appropriate coping strategies was insufficient although social effects of disease were subjectively meaningful for patients in CR.

Transgenic expression of β1 antibody in brain neurons impairs age-dependent amyloid deposition in APP23 mice

Heterologous expression of the functional amyloid beta (Aβ) antibody β1 in the central nervous system was engineered to maximize antibody exposure in the brain and assess the effects on Aβ production and accumulation in these conditions. A single open reading frame encoding the heavy and light chains of β1 linked by the mouth and foot virus peptide 2A was expressed in brain neurons of transgenic mice. Two of the resulting BIN66 transgenic lines were crossed with APP23 mice, which develop severe central amyloidosis. Brain concentrations at steady-state 5 times greater than those found after peripheral β1 administration were obtained. Similar brain and plasma β1 concentrations indicated robust antibody efflux from the brain. In preplaque mice, β1 formed a complex with Aβ that caused a modest Aβ increase in brain and plasma. At 11 months of age, β1 expression reduced amyloid by 97% compared with age-matched APP23 mice. Interference of β1 with β-secretase cleavage of amyloid precursor protein was relatively small. Our data suggest that severely impaired amyloid formation was primarily mediated by a complex of β1 with soluble Aβ, which might have prevented Aβ aggregation or favored transport out of the brain.

Beta-amyloid peptide variants in brains and cerebrospinal fluid from amyloid precursor protein (APP) transgenic mice: comparison with human Alzheimer amyloid

In this study, we report a detailed analysis of the different variants of amyloid-β (Aβ) peptides in the brains and the cerebrospinal fluid from APP23 transgenic mice, expressing amyloid precursor protein with the Swedish familial Alzheimer disease mutation, at different ages. Using one- and two-dimensional gel electrophoresis, immunoblotting, and mass spectrometry, we identified the Aβ peptides Aβ(1-40), -(1-42), -(1-39), -(1-38), -(1-37), -(2-40), and -(3-40) as well as minor amounts of pyroglutamate-modified Aβ (Aβ(N3pE)) and endogenous murine Aβ in brains from 24-month-old mice. Chemical modifications of the N-terminal amino group of Aβ were identified that had clearly been introduced during standard experimental procedures. To address this issue, we additionally applied amyloid extraction in ultrapure water. Clear differences between APP23 mice and Alzheimer disease (AD) brain samples were observed in terms of the relative abundance of specific variants of Aβ peptides, such as Aβ(N3pE), Aβ(1-42), and N-terminally truncated Aβ(2/3-42). These differences to human AD amyloid were also noticed in a related mouse line transgenic for human wild type amyloid precursor protein. Taken together, our findings suggest different underlying molecular mechanisms driving the amyloid deposition in transgenic mice and AD patients.

First Preparation of Nanocrystalline Zinc Silicate by Chemical Vapor Synthesis Using an Organometallic Single-Source Precursor

A method is presented to prepare nanocrystalline alpha-Zn(2)SiO(4) with the smallest crystal size reported so far for this system. Our approach combines the advantages of organometallic single-source precursor routes with aerosol processing techniques. The chemical design of the precursor enables the preferential formation of pure zinc silicates. Since gas-phase synthesis reduces intermolecular processes, and keeps the particles small, zinc silicate was synthesized from the volatile organometallic precursor [[MeZnOSiMe(3)](4)], possessing a Zn-methyl- and O-silyl-substituted Zn(4)O(4)-heterocubane framework (cubane), under oxidizing conditions, using the chemical vapor synthesis (CVS) method. The products obtained under different process conditions and their structural evolution after sintering were investigated by using various analytical techniques (powder X-ray diffraction, transmission electron microscopy, EDX analysis, solid-state NMR, IR, Raman, and UV/Vis spectroscopy). The deposited aerosol obtained first (processing temperature 750 degrees C) was amorphous, and contained agglomerates with primary particles of 12 nm in size. These primary particles can be described by a [Zn-O-Si] phase without long-range order. The deposit obtained at 900 degrees C contained particles with embedded nanocrystallites (3-5 nm) of beta-Zn(2)SiO(4), Zn(1.7)SiO(4), and ZnO in an amorphous matrix. On further ageing, the as-deposited particles obtained at 900 degrees C form alpha-Zn(2)SiO(4) imbedded in amorphous SiO(2). The crystallite sizes and primary particle sizes in the formed alpha-Zn(2)SiO(4) were found to be below approximately 50 nm and mainly spherical in morphology. A gas-phase mechanism for the particle formation is proposed. In addition, the solid-state reactions of the same precursor were studied in detail to investigate the fundamental differences between a gas-phase and a solid-state synthesis route.

Low polarization dependent diffraction grating for wavelength demultimlexing

A low polarization dependent, high diffraction efficiency grating for wavelength demultiplexer is proposed, manufactured by standard crystallographic etching of Si surface. Light is incident and diffracted inside the wafer, which is covered with reflecting metal. Optimized groove form results in a flat spectral response for TE and TM polarizations.

Phylogenetic conservation of the benzodiazepine binding sites: pharmacological evidence

Phylogenetic research can help to elucidate the structure of the GABA/benzodiazepine receptor complex. In this study the evolution of the beta-carboline binding site was traced to see whether it paralleled that of the benzodiazepine binding site. The ratio of [3H]ethyl-beta-carboline-3-carboxylate (beta-CCE) to [3H]flunitrazepam (FNZ) binding sites was determined in several nonmammalian species. The results further substantiate the tight link between these two binding sites. Photoaffinity labelling of the benzodiazepine receptor (BZR) has revealed phylogenetic variation of the molecular weight of the benzodiazepine binding proteins. The IC50 values for inhibition of [3H]FNZ by various compounds which are active at the central benzodiazepine receptors were determined in three phylogenetically distant species that each showed distinct subunit patterns. In these species, the respective affinities of the compounds were remarkably similar, suggesting that the binding sites for benzodiazepines are conserved in higher bony fishes and tetrapods. The conserved binding sites, in addition to recent immunological results obtained in other research groups, provide further evidence for the existence of the GABA/BZR as an isoreceptor complex.