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[...]the mortality data presented (calculated by quantifying deaths after confirmed positive) suggests increased disease severity in these subjects (10). [...]they reported that APOE ε4ε4 genotype was associated with a 4-fold increase in mortality after testing positive relative to APOE ε3ε3 individuals. Furthermore, individuals carrying the APOE ε4 allele exhibited accelerated breakdown of the blood brain barrier (16,17). [...]this not only creates concern for exacerbated inflammation in the periphery contributing to a cytokine storm during infection, yet also the potential for increased risk of long-term neurodegeneration in APOE ε4 infected patients. [...]these findings encourage comprehensive interpretations of population-specific susceptibilities to COVID-19 like those observed among African Americans (18), and the role that variation in APOE allele frequency may play (19). Given the compelling evidence linking aberrant inflammation to severe COVID-19 (20), and the association of APOE ε4 with exacerbated inflammation, future studies should aim to determine if APOE ε4 is associated with increased inflammatory responses in the periphery following COVID-19 infection. [...]longitudinal effects of COVID-19 infection in APOE ε4 carriers, which exhibit exacerbated neuroinflammatory responses (21), may lead to exacerbated risk for developing these aliments.

Background Anesthesia induces Tau phosphorylation and cognitive impairment in young, but not adult, mice. Apolipoprotein E (ApoE) may play a protective role in neuronal activity and injury repair, whereas its toxic fragments are reported to induce neurodegeneration and neurocognitive impairment in patients with Alzheimer's disease (AD). Therefore, we set out to test the hypothesis that the difference in ApoE fragments, but not the full‐length ApoE, contributes to the difference in Tau phosphorylation and neurocognitive functions following sevoflurane anesthesia in young mice. Methods Sevoflurane was administered to wild‐type (WT), ApoE‐knockout (ApoE‐KO), ApoE3‐targeted replacement (ApoE3 expresses both full‐length and fragmented ApoE), and ApoE2‐targeted replacement (ApoE2 only expresses full‐length ApoE) mice. The mRNA and protein levels of ApoE, phosphorylated Tau (pTau), and cognitive function were tested in the mice. Results Sevoflurane anesthesia enhanced ApoE mRNA, total ApoE, full‐length ApoE, ApoE fragments, Tau phosphorylation (AT8 and PHF1), and cognitive impairment in young mice, but not in adult mice. ApoE2, but not ApoE3 or ApoE‐KO, mice showed reduced sevoflurane‐induced pTau elevation and cognitive impairment. Conclusion These data suggest that elevated ApoE fragments rather than full‐length ApoE might be one of the underlying mechanisms of age‐dependent Tau phosphorylation and cognitive impairment in young mice following sevoflurane anesthesia.

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder characterized by extracellular amyloid β (Aβ) and intraneuronal tau protein aggregations. One risk factor for developing AD is the APOE gene coding for the apolipoprotein E protein (apoE). Humans have three versions of APOE gene: ε2, ε3, and ε4 allele. Carrying the ε4 allele is an AD risk factor while carrying the ε2 allele is protective. ApoE is a component of lipoprotein particles in the plasma at the periphery, as well as in the cerebrospinal fluid (CSF) and in the interstitial fluid (ISF) of brain parenchyma in the central nervous system (CNS). ApoE is a major lipid transporter that plays a pivotal role in the development, maintenance, and repair of the CNS, and that regulates multiple important signaling pathways. This review will focus on the critical role of apoE in AD pathogenesis and some of the currently apoE-based therapeutics developed in the treatment of AD.

Endothelial senescence is an important risk factor leading to atherosclerosis. The mechanism of quercetin against endothelial senescence is worth exploring. Quercetin (20 mg/kg/d) was administered to ApoE mice intragastrically to evaluate the effectiveness of quercetin on atherosclerotic lesion . , human aortic endothelial cells (HAECs) were used to assess the effect of quercetin on cellular senescence induced by oxidized low-density lipoprotein (ox-LDL). Transcriptome microarray and quantitative RT-PCR was conducted to study the pharmacological targets of quercetin. ApoE mice demonstrated obvious lipid deposition in arterial lumina, high level of serum sIcam-1 and IL-6, and high density of Vcam-1 and lower density of Sirt1 in aorta. Quercetin administration decreased lipid deposition in arterial lumina, serum sIcam-1, and IL-6 and Vcam-1 in aorta, while increased the density of Sirt1 in aorta of ApoE mice. , quercetin (0.3, 1, or 3 μmol/L) decreased the expression of senescence-associated β-galactosidase and improved cell morphology of HAECs. And quercetin decreased the cellular apoptosis and increased mitochondrial membrane potential (ΔΨm) in dose-dependent manner, and decreased ROS generation simultaneously. Transcriptome microarray suggested 254 differentially expressed (DE) mRNAs (110 mRNAs were upregulated and 144 mRNAs were downregulated) in HAECs after quercetin treatment (fold change > 1.5,  < 0 .05, Que Ox-LDL). GO and KEGG analysis indicated nitrogen metabolism, ECM-receptor interaction, complement, and coagulation cascades, p53 and mTOR signaling pathway were involved in the pharmacological mechanisms of quercetin against ox-LDL. Quercetin alleviated atherosclerotic lesion both and .

Ferroptosis may play an essential role in lipid peroxidation and endothelial dysfunction of aortic endothelial cells (ECs) in type 2 diabetes mellitus (T2DM) with atherosclerosis (AS). Hydroxysafflor yellow A (HSYA) has shown substantial antioxidant stress and anti-ferroptosis. This study confirms whether HSYA improves symptoms in a mouse model of T2DM/AS and elucidates the underlying mechanisms. ApoE -/- mice were fed with high fat combined with 30 mg/kg streptozotocin to establish a T2DM/AS model. Then mice were treated with intraperitoneal injections of 2.25 mg/kg HSYA for 12 weeks. Human Umbilical Vein Endothelial cells (HUVEC) induced by 33.3 mM d-glucose +100 μg/mL ox-LDL were used to construct a high lipid and high glucose cell model treated with 25 μM HSYA. The changes in oxidative stress- and ferroptosis-related markers were detected, and the regulatory effect of HSYA on the miR-429/SLC7A11 was also verified. Normal ApoE -/- mice or HUVEC cells were used as the control group. HSYA effectively reduced atherosclerotic plaque formation in the T2DM/AS mouse model and inhibited HUVEC ferroptosis, such as upregulating GSH-Px, SLC7A11 and GPX4, but inhibited ACSL4. Furthermore, HSYA also downregulated the expression of miR-429, which further regulated SLC7A11 expression. After miR-429 mimic or SLC7A11 siRNA transfection in the HUVEC, the antioxidative stress and anti-ferroptosis effects of HSYA were significantly abolished. HSYA is expected to become an important health drug to prevent the occurrence and development of T2DM/AS.

Atherosclerosis (AS), the underlying cause of most cardiovascular events, is one of the most common causes of human morbidity and mortality worldwide due to the lack of an efficient strategy for targeted therapy. In this work, we aimed to develop an ideal biomimetic nanoparticle for targeted AS therapy. Based on macrophage \"homing\" into atherosclerotic lesions and cell membrane coating nanotechnology, biomimetic nanoparticles (MM/RAPNPs) were fabricated with a macrophage membrane (MM) coating on the surface of rapamycin-loaded poly (lactic-co-glycolic acid) copolymer (PLGA) nanoparticles (RAPNPs). Subsequently, the physical properties of the MM/RAPNPs were characterized. The biocompatibility and biological functions of MM/RAPNPs were determined . Finally, in AS mouse models, the targeting characteristics, therapeutic efficacy and safety of the MM/RAPNPs were examined. The advanced MM/RAPNPs demonstrated good biocompatibility. Due to the MM coating, the nanoparticles effectively inhibited the phagocytosis by macrophages and targeted activated endothelial cells . In addition, MM-coated nanoparticles effectively targeted and accumulated in atherosclerotic lesions . After a 4-week treatment program, MM/RAPNPs were shown to significantly delay the progression of AS. Furthermore, MM/RAPNPs displayed favorable safety performance after long-term administration. These results demonstrate that MM/RAPNPs could efficiently and safely inhibit the progression of AS. These biomimetic nanoparticles may be potential drug delivery systems for safe and effective anti-AS applications.

Circulating endothelial progenitor cells (EPCs), which function in vascular repair, are the markers of endothelial dysfunction and vascular health. Fibroblast growth factor 21 (FGF21), a liver‐secreted protein, plays a crucial role in glucose homeostasis and lipid metabolism. FGF21 has been reported to attenuate the progression of atherosclerosis, but its impact on EPCs under high oxidative stress conditions remains unclear. In vitro studies showed that the β‐klotho protein was expressed in cultured EPCs and that its expression was upregulated by FGF21 treatment. Hydrogen peroxide (H2O2)‐induced oxidative stress impaired EPC function, including cell viability, migration and tube formation. Pretreatment with FGF21 restored the functions of EPCs after the exposure to H2O2. Administration of N(ω)‐nitro‐L‐arginine methyl ester (L‐NAME), an inhibitor of nitric oxide synthase, inhibited the effects of FGF21 in alleviating oxidative injury by suppressing endothelial nitric oxide synthase (eNOS). In an in vivo study, the administration of FGF21 significantly reduced total cholesterol (TC) and blood glucose levels in apolipoprotein E (ApoE)‐deficient mice that were fed a high‐fat diet (HFD). Endothelial function, as reflected by acetylcholine‐stimulated aortic relaxation, was improved after FGF21 treatment in ApoE‐deficient mice. Analysis of mRNA levels in the aorta indicated that FGF21 increased the mRNA expression of eNOS and upregulated the expression of the antioxidant genes superoxide dismutase (SOD)1 and SOD2 in ApoE‐deficient mice. These data suggest that FGF21 improves EPC functions via the Akt/eNOS/nitric oxide (NO) pathway and reverses endothelial dysfunction under oxidative stress. Therefore, administration of FGF21 may ameliorate a HFD‐induced vascular injury in ApoE‐deficient mice.

Background The apolipoprotein E ( APOE ) gene is the strongest genetic risk factor for late-onset Alzheimer disease (AD). ApoE is produced by both astrocytes and microglia in the brain, whereas hepatocytes produce the majority of apoE found in the periphery. Studies using APOE knock-in and transgenic mice have demonstrated a strong isoform-dependent effect of apoE on the accumulation of amyloid-β (Aβ) deposition in the brain in the form of both Aβ-containing amyloid plaques and cerebral amyloid angiopathy. However, the specific contributions of different apoE pools to AD pathogenesis remain unknown. Methods We have begun to address these questions by generating new lines of APOE knock-in ( APOE -KI) mice (ε2/ε2, ε3/ε3, and ε4/ε4) where the exons in the coding region of APOE are flanked by loxP sites, allowing for cell type-specific manipulation of gene expression. We assessed these mice both alone and after crossing them with mice with amyloid deposition in the brain. Using biochemical and histological methods. We also investigated how removal of APOE expression from hepatocytes affected cerebral amyloid deposition. Results As in other APOE knock-in mice, apoE protein was present predominantly in astrocytes in the brain under basal conditions and was also detected in reactive microglia surrounding amyloid plaques. Primary cultured astrocytes and microglia from the APOE -KI mice secreted apoE in lipoprotein particles of distinct size distribution upon native gel analysis with microglial particles being substantially smaller than the HDL-like particles secreted by astrocytes. Crossing of APP/PS1 transgenic mice to the different APOE -KI mice recapitulated the previously described isoform-specific effect (ε4 > ε3) on amyloid plaque and Aβ accumulation. Deletion of APOE in hepatocytes did not alter brain apoE levels but did lead to a marked decrease in plasma apoE levels and changes in plasma lipid profile. Despite these changes in peripheral apoE and on plasma lipids, cerebral accumulation of amyloid plaques in APP/PS1 mice was not affected. Conclusions Altogether, these new knock-in strains offer a novel and dynamic tool to study the role of APOE in AD pathogenesis in a spatially and temporally controlled manner.

INTRODUCTION We discovered that the APOE3 Christchurch (APOE3Ch) variant may provide resistance to Alzheimer's disease (AD). This resistance may be due to reduced pathological interactions between ApoE3Ch and heparan sulfate proteoglycans (HSPGs). METHODS We developed and characterized the binding, structure, and preclinical efficacy of novel antibodies targeting human ApoE‐HSPG interactions. RESULTS We found that one of these antibodies, called 7C11, preferentially bound ApoE4, a major risk factor for sporadic AD, and disrupts heparin‐ApoE4 interactions. We also determined the crystal structure of a Fab fragment of 7C11 and used computer modeling to predict how it would bind to ApoE. When we tested 7C11 in mouse models, we found that it reduced recombinant ApoE‐induced tau pathology in the retina of MAPT*P301S mice and curbed pTau S396 phosphorylation in brains of systemically treated APOE4 knock‐in mice. Targeting ApoE‐HSPG interactions using 7C11 antibody may be a promising approach to developing new therapies for AD.