ApoA-I Deficiency Increases Cortical Amyloid Deposition, Cerebral Amyloid Angiopathy, Cortical and Hippocampal Astrogliosis, and Amyloid-associated Astrocyte Reactivity in APP/PS1 Mice

Background Alzheimer’s disease (AD) is defined by amyloid beta (Aβ) plaques and neurofibrillary tangles and characterized by neurodegeneration and memory loss. The majority of AD patients also have Aβ deposition in cerebral vessels known as cerebral amyloid angiopathy (CAA), microhemorrhages, and vascular co-morbidities, suggesting that cerebrovascular dysfunction contributes to AD etiology. Promoting cerebrovascular resilience may therefore be a promising therapeutic or preventative strategy for AD. Plasma high-density lipoproteins (HDL) have several vasoprotective functions and are associated with reduced AD risk in some epidemiological studies and with reduced Aβ deposition and Aβ-induced inflammation in 3D engineered human cerebral vessels. In mice, deficiency of apoA-I, the primary protein component of HDL, increases CAA and cognitive dysfunction, whereas overexpression of apoA-I from its native promoter in liver and intestine has the opposite effect and lessens neuroinflammation. Similarly, acute peripheral administration of HDL reduces soluble Aβ pools in the brain and some studies have observed reduced CAA as well. Here, we expand upon the known effects of plasma HDL in mouse models and in vitro 3D artery models to investigate the interaction of amyloid, astrocytes, and HDL on the cerebrovasculature in APP/PS1 mice. Methods APP/PS1 mice deficient or hemizygous for Apoa1 were aged to 12 months. Plasma lipids, amyloid plaque deposition, Aβ protein levels, protein and mRNA markers of neuroinflammation, and astrogliosis were assessed using ELISA, qRT-PCR, and immunofluorescence. Contextual and cued fear conditioning were used to assess behavior. Results In APP/PS1 mice, complete apoA-I deficiency increased total and vascular Aβ deposition in the cortex but not the hippocampus compared to APP/PS1 littermate controls hemizygous for apoA-I. Markers of both general and vascular neuroinflammation, including Il1b mRNA, ICAM-1 protein, PDGFRβ protein, and GFAP protein, were elevated in apoA-I-deficient APP/PS1 mice. Additionally, apoA-I-deficient APP/PS1 mice had elevated levels of vascular-associated ICAM-1 in the cortex and hippocampus and vascular-associated GFAP in the cortex. A striking observation was that astrocytes associated with cerebral vessels laden with Aβ or associated with Aβ plaques showed increased reactivity in APP/PS1 mice lacking apoA-I. No behavioral changes were observed. Conclusions ApoA-I-containing HDL can reduce amyloid pathology and astrocyte reactivity to parenchymal and vascular amyloid in APP/PS1 mice

第774回 千葉医学会例会・第二内科例会 64.

The apolipoprotein E (APOE) gene is the most highly associated susceptibility locus for late onset Alzheimer's Disease (AD), and augmenting the beneficial physiological functions of apoE is a proposed therapeutic strategy. In a high throughput phenotypic screen for small molecules that enhance apoE secretion from human CCF-STTG1 astrocytoma cells, we show the chrysanthemic ester 82879 robustly increases expressed apoE up to 9.4-fold and secreted apoE up to 6-fold and is associated with increased total cholesterol in conditioned media. Compound 82879 is unique as structural analogues, including pyrethroid esters, show no effect on apoE expression or secretion. 82879 also stimulates liver x receptor (LXR) target genes including ATP binding cassette A1 (ABCA1), LXRα and inducible degrader of low density lipoprotein receptor (IDOL) at both mRNA and protein levels. In particular, the lipid transporter ABCA1 was increased by up to 10.6-fold upon 82879 treatment. The findings from CCF-STTG1 cells were confirmed in primary human astrocytes from three donors, where increased apoE and ABCA1 was observed along with elevated secretion of high-density lipoprotein (HDL)-like apoE particles. Nuclear receptor transactivation assays revealed modest direct LXR agonism by compound 82879, yet 10 μM of 82879 significantly upregulated apoE mRNA in mouse embryonic fibroblasts (MEFs) depleted of both LXRα and LXRβ, demonstrating that 82879 can also induce apoE expression independent of LXR transactivation. By contrast, deletion of LXRs in MEFs completely blocked mRNA changes in ABCA1 even at 10 μM of 82879, indicating the ability of 82879 to stimulate ABCA1 expression is entirely dependent on LXR transactivation. Taken together, compound 82879 is a novel chrysanthemic ester capable of modulating apoE secretion as well as apoE-associated lipid metabolic pathways in astrocytes, which is structurally and mechanistically distinct from known LXR agonists

Regulation of apolipoprotein E secretion, lipidation and recycling in the central nervous system

Lipid transport in the brain is coordinated by glia-derived lipoproteins that contain apolipoprotein E (apoE) as their primary protein. ApoE plays an important role in the pathogenesis of neurodegenerative diseases such as Alzheimer's disease (AD). ATP-binding cassette transporter A1 (ABCA1) effluxes cholesterol and phospholipids to apolipoprotein acceptors including apoE. ABCA1 is a key regulator of apoE levels and lipidation in the brain and deficiency of ABCA1 increases amyloid burden in AD mouse models. Translating these findings to potential therapies for AD will require a more thorough understanding of the biochemical nature of nascent apoE particles generated from glia and of lipoprotein remodeling in the CNS in general. In this thesis, I show that apoE is secreted from wild-type primary murine mixed glia as nascent lipoprotein subspecies ranging from 7.5 to 17 nm in diameter. Glia lacking ABCA1 secrete only one species of small particles (~8.1nm), which are poorly lipidated, but can accept lipids to form the full repertoire of wild-type apoE particles. Inhibition of apoE receptor function blocks appearance of the 8.1 nm species, suggesting that this particle may arise through apoE recycling. Selective deletion of the LDL receptor significantly reduces the level of the 8.1 nm particles, suggesting that apoE is preferentially recycled through LDLR. These results suggest that nascent glial apoE lipoproteins are secreted through multiple pathways. Modulating the expression, secretion or function of apoE may provide potential therapeutic approaches to protect the brain from chronic and acute damage. This thesis shows that progesterone and a synthetic progestin, lynestrenol, significantly induce apoE secretion from human CCF-STTG1 astrocytoma cells, whereas estrogens have negligible effects. Intriguingly, lynestrenol also increases expression of ABCA1 in human astrocytoma cells, primary murine glia, and immortalized murine astrocytes that express human apoE3. The progesterone receptor (PR) inhibitor RU486 attenuates the effect of progestins on apoE expression in astrocytoma but has no effect on ABCA1 expression in all glial cell models tested, suggesting that PR may participate in apoE but does not affect ABCA1 regulation. These results suggest that selective reproductive steroid hormones have the potential to influence glial lipid homeostasis through LXR-dependent and PR-dependent pathways.Medicine, Faculty ofGraduat

Sensitivity Factors Analysis on the Compressive Strength and Flexural Strength of Recycled Aggregate Infill Wall Materials

This paper describes an experimental research study designed to evaluate the feasibility of usage of the crushed clay brick and concrete block as fine aggregate raw materials producing recycled aggregate infill wall materials. To better understand the influences of various factors, an investigation was carried out with 96 specimens made by regenerated brick granule and concrete block. The regenerated brick granule content (regenerated brick granule and concrete granule proportion), water–cement ratio, aggregate–cement ratio, lime content and aggregate replacement rate were considered in an orthogonal experimental design method (DOE method) involving five factors and four factor levels. The mechanical properties of the recycled aggregate infill wall materials (RAIW) between each factor and level were evaluated by compressive strength, flexural strength and the flexural–compressive ratio. The empirical relationship among mechanical properties and factors of recycled aggregate infill wall materials was proposed by using multivariate regression analysis. The results showed that the water–cement ratio was 0.7–0.8 which is especially effective for improving the compressive strength and flexural strength of recycled aggregate infill wall materials, and the aggregate–cement ratio was the most significant factor in the flexural–compressive ratio

The mechanisms of inhibition and lubrication of clean fracturing flowback fluids in water-based drilling fluids

This study presents a novel approach for the reuse of uncontaminated fracturing flowback fluids to improve the inhibitory and lubricating properties of water-based drilling fluids (WBFs), curb environmental pollution arising from flowback fluids, and substantially mitigate the expenses associated with WBFs. The experimental design was optimized using orthogonal experiments and range analyses, whereby the modified rubber powder was set at 2.0%, xanthan gum at 0.15%, and a plant phenol to modified complexing agent ratio of 1:0.01. The assessment of the performance evaluation tests indicated that the use of uncontaminated fracturing flowback fluids as the base water can remarkably enhance the inhibitory and lubricating properties of WBFs. Precisely, this approach reduces the linear expansion rate from 62.31% to 21.25%, the reduction rate of extreme pressure lubrication coefficient by 87.98%, and the reduction rate of mud cake sticking factor by 59.86%. This investigation has established the potential environmental and economic benefits of reusing clean fracturing flowback fluids in WBFs

Hormonal modulators of glial ABCA1 and apoE levels[S]

Apolipoprotein E (apoE) is the major lipid carrier in the central nervous system. As apoE plays a major role in the pathogenesis of Alzheimer disease (AD) and also mediates repair pathways after several forms of acute brain injury, modulating the expression, secretion, or function of apoE may provide potential therapeutic approaches for several neurological disorders. Here we show that progesterone and a synthetic progestin, lynestrenol, significantly induce apoE secretion from human CCF-STTG1 astrocytoma cells, whereas estrogens and the progesterone metabolite allopregnanolone have negligible effects. Intriguingly, lynestrenol also increases expression of the cholesterol transporter ABCA1 in CCF-STTG1 astrocytoma cells, primary murine glia, and immortalized murine astrocytes that express human apoE3. The progesterone receptor inhibitor RU486 attenuates the effect of progestins on apoE expression in CCF-STTG1 astrocytoma cells but has no effect on ABCA1 expression in all glial cell models tested, suggesting that the progesterone receptor (PR) may participate in apoE but does not affect ABCA1 regulation. These results suggest that selective reproductive steroid hormones have the potential to influence glial lipid homeostasis through liver X receptor-dependent and progesterone receptor-dependent pathways

Highly efficient catalytic direct air capture of CO2 using amphoyeric amino acid sorbent with acid‐base bi‐functional 3D graphene catalyst

Direct air capture (DAC) of CO2 is vital for combating global climate change, but DAC technologies have a low absorption efficiency due to the low concentration (∼400 ppm) of atmospheric CO2. A novel DAC technology was developed to solve this issue using lysine (an amino acid) as a sorbent and N-doped 3D graphene as an absorption/desorption-enhanced bifunctional catalyst. Introducing only 500 ppm N-3DG catalyst increased the working time (≥90% CO2 absorption efficiency) by 233% and its absorption capacity by 197%. The catalyst also significantly accelerated the CO2 working desorption capacity and rate by ∼280% and ∼338% at 70 °C, enabling regeneration of the sorbent by utilizing low-temperature waste heats. Furthermore, the excellent stability of the system was confirmed by 50 cyclic tests. The chemical mechanism driving catalytic CO2 capture was postulated and confirmed by density functional theory computations. This study provides a new strategy for developing next-generation DAC technologies

ApoA-I deficiency increases cortical amyloid deposition, cerebral amyloid angiopathy, cortical and hippocampal astrogliosis, and amyloid-associated astrocyte reactivity in APP/PS1 mice

Background: Alzheimer’s disease (AD) is defined by amyloid beta (Aβ) plaques and neurofibrillary tangles and characterized by neurodegeneration and memory loss. The majority of AD patients also have Aβ deposition in cerebral vessels known as cerebral amyloid angiopathy (CAA), microhemorrhages, and vascular co-morbidities, suggesting that cerebrovascular dysfunction contributes to AD etiology. Promoting cerebrovascular resilience may therefore be a promising therapeutic or preventative strategy for AD. Plasma high-density lipoproteins (HDL) have several vasoprotective functions and are associated with reduced AD risk in some epidemiological studies and with reduced Aβ deposition and Aβ-induced inflammation in 3D engineered human cerebral vessels. In mice, deficiency of apoA-I, the primary protein component of HDL, increases CAA and cognitive dysfunction, whereas overexpression of apoA-I from its native promoter in liver and intestine has the opposite effect and lessens neuroinflammation. Similarly, acute peripheral administration of HDL reduces soluble Aβ pools in the brain and some studies have observed reduced CAA as well. Here, we expand upon the known effects of plasma HDL in mouse models and in vitro 3D artery models to investigate the interaction of amyloid, astrocytes, and HDL on the cerebrovasculature in APP/PS1 mice. Methods: APP/PS1 mice deficient or hemizygous for Apoa1 were aged to 12 months. Plasma lipids, amyloid plaque deposition, Aβ protein levels, protein and mRNA markers of neuroinflammation, and astrogliosis were assessed using ELISA, qRT-PCR, and immunofluorescence. Contextual and cued fear conditioning were used to assess behavior. Results: In APP/PS1 mice, complete apoA-I deficiency increased total and vascular Aβ deposition in the cortex but not the hippocampus compared to APP/PS1 littermate controls hemizygous for apoA-I. Markers of both general and vascular neuroinflammation, including Il1b mRNA, ICAM-1 protein, PDGFRβ protein, and GFAP protein, were elevated in apoA-I-deficient APP/PS1 mice. Additionally, apoA-I-deficient APP/PS1 mice had elevated levels of vascular-associated ICAM-1 in the cortex and hippocampus and vascular-associated GFAP in the cortex. A striking observation was that astrocytes associated with cerebral vessels laden with Aβ or associated with Aβ plaques showed increased reactivity in APP/PS1 mice lacking apoA-I. No behavioral changes were observed. Conclusions: ApoA-I-containing HDL can reduce amyloid pathology and astrocyte reactivity to parenchymal and vascular amyloid in APP/PS1 mice.Medicine, Faculty ofOther UBCNon UBCPathology and Laboratory Medicine, Department ofReviewedFacult

The liver X receptor agonist GW3965 improves recovery from mild repetitive traumatic brain injury in mice partly through apolipoprotein E.

Traumatic brain injury (TBI) increases Alzheimer's disease (AD) risk and leads to the deposition of neurofibrillary tangles and amyloid deposits similar to those found in AD. Agonists of Liver X receptors (LXRs), which regulate the expression of many genes involved in lipid homeostasis and inflammation, improve cognition and reduce neuropathology in AD mice. One pathway by which LXR agonists exert their beneficial effects is through ATP-binding cassette transporter A1 (ABCA1)-mediated lipid transport onto apolipoprotein E (apoE). To test the therapeutic utility of this pathway for TBI, we subjected male wild-type (WT) and apoE-/- mice to mild repetitive traumatic brain injury (mrTBI) followed by treatment with vehicle or the LXR agonist GW3965 at 15 mg/kg/day. GW3965 treatment restored impaired novel object recognition memory in WT but not apoE-/- mice. GW3965 did not significantly enhance the spontaneous recovery of motor deficits observed in all groups. Total soluble Aβ(40) and Aβ(42) levels were significantly elevated in WT and apoE-/- mice after injury, a response that was suppressed by GW3965 in both genotypes. WT mice showed mild but significant axonal damage at 2 d post-mrTBI, which was suppressed by GW3965. In contrast, apoE-/- mice showed severe axonal damage from 2 to 14 d after mrTBI that was unresponsive to GW3965. Because our mrTBI model does not produce significant inflammation, the beneficial effects of GW3965 we observed are unlikely to be related to reduced inflammation. Rather, our results suggest that both apoE-dependent and apoE-independent pathways contribute to the ability of GW3965 to promote recovery from mrTBI