| 1. |
- Tanrioever, Gaye, et al.
(författare)
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Prominent microglial inclusions in transgenic mouse models of alpha-synucleinopathy that are distinct from neuronal lesions
- 2020
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Ingår i: Acta neuropathologica communications. - : BMC. - 2051-5960. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Alpha-synucleinopathies are a group of progressive neurodegenerative disorders, characterized by intracellular deposits of aggregated alpha-synuclein (alpha S). The clinical heterogeneity of these diseases is thought to be attributed to conformers (or strains) of alpha S but the contribution of inclusions in various cell types is unclear. The aim of the present work was to study alpha S conformers among different transgenic (TG) mouse models of alpha-synucleinopathies. To this end, four different TG mouse models were studied (Prnp-h[A53T]alpha S; Thy1-h[A53T]alpha S; Thy1-h[A30P]alpha S; Thy1-m alpha S) that overexpress human or murine alpha S and differed in their age-of-symptom onset and subsequent disease progression. Postmortem analysis of end-stage brains revealed robust neuronal alpha S pathology as evidenced by accumulation of alpha S serine 129 (p-alpha S) phosphorylation in the brainstem of all four TG mouse lines. Overall appearance of the pathology was similar and only modest differences were observed among additionally affected brain regions. To study alpha S conformers in these mice, we used pentameric formyl thiophene acetic acid (pFTAA), a fluorescent dye with amyloid conformation-dependent spectral properties. Unexpectedly, besides the neuronal alpha S pathology, we also found abundant pFTAA-positive inclusions in microglia of all four TG mouse lines. These microglial inclusions were also positive for Thioflavin S and showed immunoreactivity with antibodies recognizing the N-terminus of alpha S, but were largely p-alpha S-negative. In all four lines, spectral pFTAA analysis revealed conformational differences between microglia and neuronal inclusions but not among the different mouse models. Concomitant with neuronal lesions, microglial inclusions were already present at presymptomatic stages and could also be induced by seeded alpha S aggregation. Although nature and significance of microglial inclusions for human alpha-synucleinopathies remain to be clarified, the previously overlooked abundance of microglial inclusions in TG mouse models of alpha-synucleinopathy bears importance for mechanistic and preclinical-translational studies.
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| 2. |
- Wagner, Jessica, et al.
(författare)
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Medin co-aggregates with vascular amyloid-beta in Alzheimers disease
- 2022
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Ingår i: Nature. - : Nature Portfolio. - 0028-0836 .- 1476-4687. ; 612, s. 123-131
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Tidskriftsartikel (refereegranskat)abstract
- Aggregates of medin amyloid (a fragment of the protein MFG-E8, also known as lactadherin) are found in the vasculature of almost all humans over 50 years of age(1,)(2), making it the most common amyloid currently known. We recently reported that medin also aggregates in blood vessels of ageing wild-type mice, causing cerebrovascular dysfunction(3). Here we demonstrate in amyloid-beta precursor protein (APP) transgenic mice and in patients with Alzheimers disease that medin co-localizes with vascular amyloid-beta deposits, and that in mice, medin deficiency reduces vascular amyloid-beta deposition by half. Moreover, in both the mouse and human brain, MFG-E8 is highly enriched in the vasculature and both MFG-E8 and medin levels increase with the severity of vascular amyloid-beta burden. Additionally, analysing data from 566 individuals in the ROSMAP cohort, we find that patients with Alzheimers disease have higher MFGE8 expression levels, which are attributable to vascular cells and are associated with increased measures of cognitive decline, independent of plaque and tau pathology. Mechanistically, we demonstrate that medin interacts directly with amyloid-beta to promote its aggregation, as medin forms heterologous fibrils with amyloid-beta, affects amyloid-beta fibril structure, and cross-seeds amyloid-beta aggregation both in vitro and in vivo. Thus, medin could be a therapeutic target for prevention of vascular damage and cognitive decline resulting from amyloid-beta deposition in the blood vessels of the brain.
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