Amyloid ß aggregation induces human brain microvascular endothelial cell death with abnormal actin organization.

Cerebral amyloid angiopathy (CAA) is a disease in which amyloid ß (Aß) is deposited on the walls of blood vessels in the brain, making those walls brittle and causing cerebral hemorrhage. However, the mechanism underlying its onset is not well understood. The aggregation and accumulation of Aß cause the occlusion and fragility of blood vessels due to endothelial cell damage, breakdown of the blood-brain barrier, and replacement with elements constituting the blood vessel wall. In this study, we observed the effect of Aß on human primary brain microvascular endothelial cells (hBMECs) in real-time using quantum dot nanoprobes to elucidate the mechanism of vascular weakening by Aß. It was observed that Aß began to aggregate around hBMECs after the start of incubation and that the cells were covered with aggregates. Aß aggregates firmly anchored the cells on the plate surface, and eventually suppressed cell motility and caused cell death. Furthermore, Aß aggregation induced the organization of abnormal actin, resulting in a significant increase in intracellular actin dots over 10 µm2. These results suggest that the mechanism by which Aß forms a fragile vessel wall is as follows: Aß aggregation around vascular endothelial cells anchors them to the substrate, induces abnormal actin organization, and leads to cell death.

Pineal cyst apoplexy and memory loss: a novel complication.

An 8-year-old boy presented to our hospital complaining of a bilateral headache associated with episodes of anterograde amnesia. He had a road traffic accident 3 years ago when a computed tomography (CT) scan revealed traumatic brain injury. In addition, a small pineal cyst (PC) was noted with minor intramural calcifications. A follow-up CT a day later demonstrated increased density in the pineal gland of 60 Hounsfield Units, suggestive of apoplectic changes in the PC. However, the patient was lost to follow-up and presented with memory loss a year and a half later, upon which CT and magnetic resonance imaging revealed enlargement of the PC. PC apoplexy is a very rare occurrence usually affecting young adult women; cases in children are rarely reported. Furthermore, PC apoplexy secondary to severe craniofacial trauma manifesting as memory loss has not yet been reported in the literature to the best of our knowledge.

Targeting whole body metabolism and mitochondrial bioenergetics in the drug development for Alzheimer's disease.

Aging is by far the most prominent risk factor for Alzheimer's disease (AD), and both aging and AD are associated with apparent metabolic alterations. As developing effective therapeutic interventions to treat AD is clearly in urgent need, the impact of modulating whole-body and intracellular metabolism in preclinical models and in human patients, on disease pathogenesis, have been explored. There is also an increasing awareness of differential risk and potential targeting strategies related to biological sex, microbiome, and circadian regulation. As a major part of intracellular metabolism, mitochondrial bioenergetics, mitochondrial quality-control mechanisms, and mitochondria-linked inflammatory responses have been considered for AD therapeutic interventions. This review summarizes and highlights these efforts.

Amyloid fibril formation is suppressed in microgravity.

In the future, humans may live in space because of global pollution and weather fluctuations. In microgravity, convection does not occur, which may change the amyloidogenicity of proteins. However, the effect of gravity on amyloid fibril formation is unclear and remains to be elucidated. Here, we analyzed the effect of microgravity on amyloid fibril formation of amyloidogenic proteins including insulin, amyloid ß42 (Aß42), and transthyretin (TTR). We produced microgravity (10-3 g) by using the gravity controller Gravite. Human insulin, Aß42, and human wild-type TTR (TTRwt) were incubated at pH 3.0, 7.0, and 3.5 at 37 °C, respectively, in 1 g on the ground or in microgravity. We measured amyloidogenicity via the thioflavin T (ThT) method and cell-based 1-fluoro-2,5-bis[(E)-3-carboxy-4-hydroxystyryl]benzene (FSB) assay. ThT fluorescence intensity and cell-based FSB assay results for human insulin samples were decreased in microgravity compared with results in 1 g. Aß42 samples did not differ in ThT fluorescence intensity in microgravity and in 1 g on the ground. However, in the cell-based FSB assay, the staining intensity was reduced in microgravity compared with that on 1 g. Human TTRwt tended to form fewer amyloid fibrils in ThT fluorescence intensity and cell-based FSB assays in microgravity than in 1 g. Human insulin and Aß42 showed decreased amyloid fibril formation in microgravity compared with that in 1 g. Human TTRwt tended to form fewer amyloid fibrils in microgravity. Our experiments suggest that the earth's gravity may be an accelerating factor for amyloid fibril formation.

Cysteine proteases as therapeutic targets: does selectivity matter? A systematic review of calpain and cathepsin inhibitors.

Cysteine proteases continue to provide validated targets for treatment of human diseases. In neurodegenerative disorders, multiple cysteine proteases provide targets for enzyme inhibitors, notably caspases, calpains, and cathepsins. The reactive, active-site cysteine provides specificity for many inhibitor designs over other families of proteases, such as aspartate and serine; however, a) inhibitor strategies often use covalent enzyme modification, and b) obtaining selectivity within families of cysteine proteases and their isozymes is problematic. This review provides a general update on strategies for cysteine protease inhibitor design and a focus on cathepsin B and calpain 1 as drug targets for neurodegenerative disorders; the latter focus providing an interesting query for the contemporary assumptions that irreversible, covalent protein modification and low selectivity are anathema to therapeutic safety and efficacy.

Dual induction of TREM2 and tolerance-related transcript, Tmem176b, in amyloid transgenic mice: implications for vaccine-based therapies for Alzheimer's disease.

Vaccine-based autoimmune (anti-amyloid) treatments are currently being examined for their therapeutic potential in Alzheimer's disease. In the present study we examined, in a transgenic model of amyloid pathology, the expression of two molecules previously implicated in decreasing the severity of autoimmune responses: TREM2 (triggering receptor expressed on myeloid cells 2) and the intracellular tolerance-associated transcript, Tmem176b (transmembrane domain protein 176b). In situ hybridization analysis revealed that both molecules were highly expressed in plaque-associated microglia, but their expression defined two different zones of plaque-associated activation. Tmem176b expression was highest in the inner zone of amyloid plaques, whereas TREM2 expression was highest in the outer zone. Induced expression of TREM2 occurred co-incident with detection of thioflavine-S-positive amyloid deposits. Transfection studies revealed that expression of TREM2 correlated negatively with motility, but correlated positively with the ability of microglia to stimulate CD4(+) T-cell proliferation, TNF (tumour necrosis factor) and CCL2 (chemokine ligand 2) production, but not IFNgamma (interferon gamma) production. TREM2 expression also showed a positive correlation with amyloid phagocytosis in unactivated cells. However, activating cells with LPS (lipopolysaccharide), but not IFNgamma, reduced the correlation between TREM2 expression and phagocytosis. Transfection of Tmem176b into both microglial and macrophage cell lines increased apoptosis. Taken together, these data suggest that, in vivo, Tmem176b(+) cells in closest apposition to amyloid may be the least able to clear amyloid. Conversely, the phagocytic TREM2(+) microglia on the plaque outer zones are positioned to capture and present self-antigens to CNS (central nervous system)-infiltrating lymphocytes without promoting pro-inflammatory lymphocyte responses. Instead, plaque-associated TREM2(+) microglia have the potential to evoke neuroprotective immune responses that may serve to support CNS function during pro-inflammatory anti-amyloid immune therapies.