Elevated low-density lipoprotein in Alzheimer's disease correlates with brain abeta 1-42 levels

Altering plasma lipids and liver enzyme activities via hippocampal injections of hen Lysozyme amyloid aggregates in an Alzheimer's disease mouse model: Insights into the therapeutic role of Bis (Indolyl) phenylmethane

Alzheimer's disease (AD) is a prevalent form of dementia in the elderly. There is currently no effective treatment available for this disease. Diagnosis of AD typically relies on clinical manifestations and specific biomarkers. The present study investigated the impact of inducing Alzheimer's disease (AD) in mice through the injection of lysozyme amyloids formed in the presence or absence of Bis (Indolyl) phenylmethane (BIPM) on alterations in plasma lipid profiles and liver enzyme activities. 24 adult Wistar rats were divided into control, Scopolamine, Lysozyme, BIPM groups and the blood samples were obtained from the groups for biochemical analysis. The findings of the study revealed significant changes in the plasma lipid profiles and liver enzyme markers of the Lysozyme group compared to the control group. The Lysozyme group exhibited elevated triglycerides (n = 6, P < 0.02) and LDL levels (n = 6, P < 0.02), reduced HDL (n = 6, P < 0.05) and cholesterol levels (n = 6, P < 0.02), and altered serum glutamic oxaloacetic transaminase (SGOT) level (n = 6, P < 0.05) compared to controls. While the level of serum glutamic pyruvic transaminase (SGPT) did not change significantly compared to the control. BIPM groups showed no significant changes in lipid or enzyme levels compared to controls. Overall, our research has shown that BIPM has the ability to modify the structure of HEWL aggregates, thereby improving the detrimental effects associated with AD caused by these aggregates. Analyzing lipid profiles and liver enzyme markers presents a promising avenue for targeted therapeutic approaches. These alterations observed in the plasma may potentially serve as candidate biomarkers for diagnosing this disease.

Mendelian randomization reveals apolipoprotein B shortens healthspan and possibly increases risk for Alzheimer's disease

Apolipoprotein B-100 (APOB) is a component of fat- and cholesterol-transporting molecules in the bloodstream. It is the main lipoprotein in low-density lipoprotein cholesterol (LDL) and has been implicated in conditions that end healthspan (the interval between birth and onset of chronic disease). However, APOB's direct relationship with healthspan remains uncertain. With Mendelian randomization, we show that higher levels of APOB and LDL shorten healthspan in humans. Multivariable Mendelian randomization of APOB and LDL on healthspan suggests that the predominant trait accounting for the relationship is APOB. In addition, we provide preliminary evidence that APOB increases risk for Alzheimer's disease, a condition that ends healthspan. If these relationships are causal, they suggest that interventions to improve healthspan in aging populations could include strategies targeting APOB. Ultimately, given that more than 44 million people currently suffer from Alzheimer's disease worldwide, such interventions are needed.

Associations of dietary cholesterol and fat, blood lipids, and risk for dementia in older women vary by APOE genotype

INTRODUCTION

Whether apolipoprotein E's (APOE's) involvement in lipid metabolism contributes to Alzheimer's disease (AD) risk remains unknown.

METHODS

Incident probable dementia and cognitive impairment (probable dementia+mild cognitive impairment) were analyzed in relation to baseline serum lipids (total, low-density lipoprotein [LDL], high-density lipoprotein [HDL], non-HDL cholesterol, total-to-HDL, LDL-to-HDL, remnant cholesterol, and triglycerides) using Mendelian randomization in 5358 postmenopausal women from the Women's Health Initiative Memory Study. We also examined associations of baseline dietary cholesterol and fat with lipids based on APOE status.

RESULTS

After an average of 11.13 years, less favorable lipid levels related to greater dementia and cognitive impairment risk. Dementia (odds ratio [OR] = 3.13; 95% confidence interval [CI]: 2.31 to 4.24) and cognitive impairment (OR = 2.38; 95% CI: 1.85 to 3.06) risk were greatest in relation to higher remnant cholesterol levels. Greater cholesterol consumption related to poorer lipids in APOE4+ compared to APOE3 carriers.

DISCUSSION

APOE4+ carriers consuming more cholesterol had less favorable lipids, which were associated with greater dementia and cognitive impairment risk.

HIGHLIGHTS

Less favorable serum lipids were associated with higher dementia incidence. Mendelian randomization findings suggest causality between lipids and dementia. Lipid levels in older women may be clinical indicators of dementia risk. APOE4 carriers had poorest lipid profiles in relation to cholesterol consumption. APOE risk for dementia may be modifiable through lipid management.

Unraveling the impact of 27-hydroxycholesterol in autoimmune diseases: Exploring promising therapeutic approaches

The role of 27-hydroxycholesterol (27-OHC) in autoimmune diseases has become a subject of intense research in recent years. This oxysterol, derived from cholesterol, has been identified as a significant player in modulating immune responses and inflammation. Its involvement in autoimmune pathogenesis has drawn attention to its potential as a therapeutic target for managing autoimmune disorders effectively. 27-OHC, an oxysterol derived from cholesterol, has emerged as a key player in modulating immune responses and inflammatory processes. It exerts its effects through various mechanisms, including activation of nuclear receptors, interaction with immune cells, and modulation of neuroinflammation. Additionally, 27-OHC has been implicated in the dysregulation of lipid metabolism, neurotoxicity, and blood-brain barrier (BBB) disruption. Understanding the intricate interplay between 27-OHC and autoimmune diseases, particularly neurodegenerative disorders, holds promise for developing targeted therapeutic strategies. Additionally, emerging evidence suggests that 27-OHC may interact with specific receptors and transcription factors, thus influencing gene expression and cellular processes in autoimmune disorders. Understanding the intricate mechanisms by which 27-OHC influences immune dysregulation and tissue damage in autoimmune diseases is crucial for developing targeted therapeutic interventions. Further investigations into the molecular pathways and signaling networks involving 27-OHC are warranted to unravel its full potential as a therapeutic target in autoimmune diseases, thereby offering new avenues for disease intervention and management.

Pantethine Ameliorates Recognition Impairment in a Mouse Model of Alzheimer's Disease by Modulating Cholesterol Content and Intestinal Flora Species

SCOPE

As a natural dietary low-molecular-weight thiol, pantethine helps maintain brain homeostasis and function in Alzheimer's disease (AD) mice. The current study aims to investigate the protective effects and underlying mechanisms of pantethine on the mitigation of cognitive deficits and pathology in a triple transgenic AD mouse model.

METHODS AND RESULTS

Compared to control mice, oral administration of pantethine improve spatial learning and memory ability, relieve anxiety, and reduce the production of amyloid-β (Aβ), neuronal damage, and inflammation in 3×Tg-AD mice. Pantethine reduces body weight, body fat, and the production of cholesterol in 3×Tg-AD mice by inhibiting sterol regulatory element-binding protein (SREBP2) signal pathway and apolipoprotein E (APOE) expression; lipid rafts in the brain, which are necessary for the processing of the Aβ precursor protein (APP), are also decreased. In addition, pantethine regulates the composition, distribution, and abundance of characteristic flora in the intestine; these floras are considered protective and anti-inflammatory in the gastrointestinal tract, suggesting a possible improvement in the gut flora of 3×Tg-AD mice.

CONCLUSION

This study highlights the potential therapeutic effect of pantethine in AD by reducing cholesterol and lipid raft formation and regulating intestinal flora, suggesting a new option for the development of clinical drugs for AD.

Cholesterol twists the transmembrane Di-Gly region of amyloid-precursor protein

Nearly 95% of Alzheimer's disease (AD) occurs sporadically without genetic linkage. Aging, hypertension, high cholesterol content, and diabetes are known nongenomic risk factors of AD. Aggregation of Aβ peptides is an initial event of AD pathogenesis. Aβ peptides are catabolic products of a type I membrane protein called amyloid precursor protein (APP). Aβ40 is the major product, whereas the 2-residue-longer version, Aβ42, induces amyloid plaque formation in the AD brain. Since cholesterol content is one risk factor for sporadic AD, we aimed to explore whether cholesterol in the membrane affects the structure of the APP transmembrane region, thereby modulating the γ-secretase cutting behavior. Here, we synthesized several peptides containing the APP transmembrane region (sequence 693-726, corresponding to the Aβ_22-55 sequence) with one or two Cys mutations for spin labeling. We performed three electron spin resonance experiments to examine the structural changes of the peptides in liposomes composed of dioleoyl phosphatidylcholine and different cholesterol content. Our results show that cholesterol increases membrane thickness by 10% and peptide length accordingly. We identified that the di-glycine region of Aβ_36-40 (sequence VGGVV) exhibits the most profound change in response to cholesterol compared with other segments, explaining how the presence of cholesterol affects the γ-secretase cutting site. This study provides spectroscopic evidence showing how cholesterol modulates the structure of the APP transmembrane region in a lipid bilayer.

Metabolic Overlap between Alzheimer's Disease and Metabolic Syndrome Identifies the PVRL2 Gene as a New Modulator of Diabetic Dyslipidemia

BACKGROUND

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) share metabolic alterations such as abnormal insulin and lipid metabolism and have some common genetic factors such as APOE genotype. Taking this into account, we hypothesized that we could identify common genetic factors involved in the development of diabetes and cardiovascular diseases.

METHODOLOGY

We first genotyped 48 single nucleotide polymorphisms (SNPs) previously associated with AD in a cohort composed of 330 patients with cognitive impairment (CI) to assess their association with plasma lipids. Second, we conducted pleiotropy-informed conjunctional false discovery rate (FDR) analysis designed to identify shared variants between AD and plasma lipid levels. Finally, we used the SNPs to be found associated with lipid parameters and AD to search for associations with lipoprotein parameters in 281 patients with cardiometabolic risk.

RESULTS

Five SNPs were significantly associated with lower levels of cholesterol transported in remnant lipoprotein particles (RLPc) in subjects with CI; among these SNPs was the rs73572039 variant in PVRL2. Stratified QQ-plots were conducted on GWAS designed for AD and triglycerides (TG). The cross-trait analysis resulted in a total of 22 independent genomic loci associated with both AD and TG levels with a conjFDR < 0.05. Among these loci, two pleiotropic variants were located in PVRL2 (rs12978931 and rs11667640). The three SNPs in PVRL2 were significantly associated with RLPc, TG, and number of circulating VLDL and HDL particles in subjects with cardiometabolic risk.

CONCLUSIONS

We have identified three variants in PVRL2 that predispose individuals to AD that also influence the lipid profile that confers cardiovascular risk in T2DM subjects. PVRL2 is a potential new modulating factor of atherogenic dyslipidemia.

Status of Metabolomic Measurement for Insights in Alzheimer's Disease Progression-What Is Missing?

Alzheimer's disease (AD) is an aging-related neurodegenerative disease, leading to the progressive loss of memory and other cognitive functions. As there is still no cure for AD, the growth in the number of susceptible individuals represents a major emerging threat to public health. Currently, the pathogenesis and etiology of AD remain poorly understood, while no efficient treatments are available to slow down the degenerative effects of AD. Metabolomics allows the study of biochemical alterations in pathological processes which may be involved in AD progression and to discover new therapeutic targets. In this review, we summarized and analyzed the results from studies on metabolomics analysis performed in biological samples of AD subjects and AD animal models. Then this information was analyzed by using MetaboAnalyst to find the disturbed pathways among different sample types in human and animal models at different disease stages. We discuss the underlying biochemical mechanisms involved, and the extent to which they could impact the specific hallmarks of AD. Then we identify gaps and challenges and provide recommendations for future metabolomics approaches to better understand AD pathogenesis.

A Comprehensive Investigation of the Potential Role of Lipoproteins and Metabolite Profile as Biomarkers of Alzheimer's Disease Compared to the Known CSF Biomarkers

Introduction

While cerebrospinal fluid (CSF) core biomarkers have been considered diagnostic biomarkers for a long time, special attention has been recently dedicated to lipoproteins and metabolites that could be potentially associated with Alzheimer's disease (AD) neurodegeneration. Herein, we aimed to investigate the relationship between the levels of CSF core biomarkers including Aβ-42, TAU, and P-TAU and plasma lipoproteins and metabolites of patients with AD from the baseline cohort of the Alzheimer's Disease Neuroimaging Initiative (ADNI) database.

Method

Using the ADNI database, fourteen subclasses of lipoproteins as well as a number of lipids and fatty acids and low-molecular metabolites including amino acids, ketone bodies, and glycolysis-related metabolites in blood samples were measured as potential noninvasive markers, and their association with the CSF core biomarkers was statistically investigated controlling for age and gender.

Results

A total number of 251 AD subjects were included, among whom 71 subjects were negative for the Apo-E ε4 allele and 150 were positive. There was no significant difference between the two groups regarding cognitive assessments, CSF core biomarkers, and lipoproteins and metabolites except the level of Aβ-42 (p < 0.001) and phenylalanine (p = 0.049), which were higher in the negative group. CSF TAU and P-TAU were significantly correlated with medium and small HDL in the negative group, and with extremely large VLDL in the positive group. Our results also indicated significant correlations of metabolites including unsaturated fatty acids, glycerol, and leucine with CSF core biomarkers.

Conclusion

Based on our findings, a number of lipoproteins and metabolites were associated with CSF core biomarkers of AD. These correlations showed some differences in Apo-E ε4 positive and negative groups, which reminds the role of Apo-E gene status in the pathophysiology of AD development. However, further research is warranted to explore the exact association of lipoproteins and other metabolites with AD core biomarkers and pathology.

Implication of saturated fats in the aetiology of childhood attention deficit/hyperactivity disorder - A narrative review

Attention Deficit/Hyperactivity Disorder (ADHD) is the most common mental health disorder in the paediatric population. ADHD is highly comorbid with obesity, and has also been associated with poor dietary patterns such as increased consumption of refined carbohydrates and saturated fats. Although ADHD in children was associated with high consumption of saturated fats, so far there has been no evidence-based attempt to integrate dietary strategies controlling for intake of saturated fats into the etiological framework of the disorder. Evidence from human studies and animal models has shown that diets high in saturated fats are detrimental for the development of dopaminergic neurocircuitries, synthesis of neurofactors (e.g. brain derived neurotrophic factor) and may promote brain inflammatory processes. Notably, animal models provide evidence that early life consumption of a high saturated fats diet may impair the development of central dopamine pathways. In the present paper, we review the impact of high saturated fats diets on neurobiological processes in human studies and animal models, and how these associations may be relevant to the neuropathophysiology of ADHD in children. The validation of this relationship and its underlying mechanisms through future investigative studies could have implications for the prevention or exacerbation of ADHD symptoms, improve the understanding of the pathogenesis of the disorder, and help design future dietary studies in patients with ADHD.

Structural Determinant of β-Amyloid Formation: From Transmembrane Protein Dimerization to β-Amyloid Aggregates

Most neurodegenerative diseases have the characteristics of protein folding disorders, i.e., they cause lesions to appear in vulnerable regions of the nervous system, corresponding to protein aggregates that progressively spread through the neuronal network as the symptoms progress. Alzheimer's disease is one of these diseases. It is characterized by two types of lesions: neurofibrillary tangles (NFTs) composed of tau proteins and senile plaques, formed essentially of amyloid peptides (Aβ). A combination of factors ranging from genetic mutations to age-related changes in the cellular context converge in this disease to accelerate Aβ deposition. Over the last two decades, numerous studies have attempted to elucidate how structural determinants of its precursor (APP) modify Aβ production, and to understand the processes leading to the formation of different Aβ aggregates, e.g., fibrils and oligomers. The synthesis proposed in this review indicates that the same motifs can control APP function and Aβ production essentially by regulating membrane protein dimerization, and subsequently Aβ aggregation processes. The distinct properties of these motifs and the cellular context regulate the APP conformation to trigger the transition to the amyloid pathology. This concept is critical to better decipher the patterns switching APP protein conformation from physiological to pathological and improve our understanding of the mechanisms underpinning the formation of amyloid fibrils that devastate neuronal functions.

Brain Endothelial Cells in Contrary to the Aortic Do Not Transport but Degrade Low-Density Lipoproteins via Both LDLR and ALK1

The transport of low-density lipoprotein (LDL) through the endothelium is a key step in the development of atherosclerosis, but it is notorious that phenotypic differences exist between endothelial cells originating from different vascular beds. Endothelial cells forming the blood–brain barrier restrict paracellular and transcellular passage of plasma proteins. Here, we systematically compared brain versus aortic endothelial cells towards their interaction with LDL and the role of proteins known to regulate the uptake of LDL by endothelial cells. Both brain endothelial cells and aortic endothelial cells bind and internalize LDL. However, whereas aortic endothelial cells degrade very small amounts of LDL and transcytose the majority, brain endothelial cells degrade but do not transport LDL. Using RNA interference (siRNA), we found that the LDLR–clathrin pathway leads to LDL degradation in either endothelial cell type. Both loss- and gain-of-function experiments showed that ALK1, which promotes transcellular LDL transport in aortic endothelial cells, also limits LDL degradation in brain endothelial cells. SR-BI and caveolin-1, which promote LDL uptake and transport into aortic endothelial cells, limit neither binding nor association of LDL to brain endothelial cells. Together, these results indicate distinct LDL trafficking by brain microvascular endothelial cells and aortic endothelial cells.

Crosstalk between neurological, cardiovascular, and lifestyle disorders: insulin and lipoproteins in the lead role

Insulin resistance and impaired lipoprotein metabolism contribute to a plethora of metabolic and cardiovascular disorders. These alterations have been extensively linked with poor lifestyle choices, such as consumption of a high-fat diet, smoking, stress, and a redundant lifestyle. Moreover, these are also known to increase the co-morbidity of diseases like Type 2 diabetes mellitus and atherosclerosis. Under normal physiological conditions, insulin and lipoproteins exert a neuroprotective role in the central nervous system. However, the tripping of balance between the periphery and center may alter the normal functioning of the brain and lead to neurological disorders such as Alzheimer's disease, Parkinson's disease, stroke, depression, and multiple sclerosis. These neurological disorders are further characterized by certain behavioral and molecular changes that show consistent overlap with alteration in insulin and lipoprotein signaling pathways. Therefore, targeting these two mechanisms not only reveals a way to manage the co-morbidities associated with the circle of the metabolic, central nervous system, and cardiovascular disorders but also exclusively work as a disease-modifying therapy for neurological disorders. In this review, we summarize the role of insulin resistance and lipoproteins in the progression of various neurological conditions and discuss the therapeutic options currently in the clinical pipeline targeting these two mechanisms; in addition, challenges faced in designing these therapeutic approaches have also been touched upon briefly.

Profiling of circulating chromosome 21-encoded microRNAs, miR-155, and let-7c, in down syndrome

Background

Down syndrome (DS) is the most common chromosomal survival aneuploidy. The increase in DS life expectancy further heightens the risk of dementia, principally early‐onset Alzheimer's disease (AD). AD risk in DS is higher, considering that this population may also develop metabolic diseases such as obesity, dyslipidemias, and diabetes mellitus. The extra genetic material that characterizes DS causes an imbalance in the genetic dosage, including over‐expression of AD's key pathophysiological molecules and the gene expression regulators, the microRNAs (miRNAs). Two miRNAs, chromosome 21‐encoded, miR‐155, and let‐7c, are associated with cognitive impairment and dementia in adults; but, expression dynamics and relationship with clinical variables during the DS's lifespan had remained hitherto unexplored.

Methods

The anthropometric, clinical, biochemical, and profile expression of circulating miR‐155 and let‐7c were analyzed in a population of 52 control and 50 DS subjects divided into the young group (Aged ≤20 years) and the adult group (Aged ≥21 years).

Results

The expression changes for miR‐155 were not significant; nevertheless, a negative correlation with HDL‐Cholesterol concentrations was observed. Notably, let‐7c was over‐expressed in DS from young and old ages.

Conclusion

Overall, our results suggest that let‐7c plays a role from the early stages of DS's cognitive impairment while overexpression of miR‐155 may be related to lipid metabolism changes. Further studies of both miRNAs will shed light on their potential as therapeutic targets to prevent or delay DS's cognitive impairment.

Total Cholesterol and APOE-Related Risk for Alzheimer's Disease in the Alzheimer's Disease Neuroimaging Initiative

BACKGROUND

APOEɛ4 allele confers greatest genetic risk for Alzheimer's disease (AD), yet mechanisms underlying this risk remain elusive. APOE is involved in lipid metabolism, and literature suggest relationships between high total cholesterol, APOE, and AD. Further investigation is needed to elucidate the potential role of total cholesterol in AD risk.

OBJECTIVE

To investigate the relationship between total cholesterol and APOE-related AD risk in the Alzheimer's Disease Neuroimaging Initiative.

METHODS

Participants (N = 1,534) were classified as controls (cognitively normal; N = 404), early mild cognitive impairment (MCI; N = 294), late MCI (N = 539), or AD (N = 297). Total cholesterol levels were compared across APOE genotype and diagnosis. Mendelian randomization was performed to examine causality between total cholesterol and AD risk using APOE as a genetic instrument.

RESULTS

Total cholesterol was higher in APOE4+ compared to APOE3 and APOE2+ (ps < 0.04) carriers. Those with AD and late MCI (ps < 0.001) had higher total cholesterol than the control group. Comparing APOE4+ to APOE3 carriers, the predicted odds ratios per mg/dL greater total cholesterol were 1.11 for MCI (95% confidence interval, 1.04-7.32), 1.05 for early MCI (1.01-3.22), 1.13 for late MCI (1.05-11.70), 1.21 for AD (1.09-54.05), and 1.13 for composite dementia (MCI or AD; 1.06-11.59) (ps < 0.05, F-statistics > 10).

CONCLUSION

Higher total cholesterol may be a significant contributor to AD risk, particularly in APOE4 carriers who, based on existing literature, tend to have impaired cholesterol metabolism. Our findings highlight a possible mechanism by which APOE confers AD risk and indicate potential for AD risk modification through maintenance of healthy total cholesterol levels.

Investigating Causal Relations Between Circulating Metabolites and Alzheimer's Disease: A Mendelian Randomization Study

BACKGROUND

Metabolomics is a promising approach that can be used to understand pathophysiological pathways of Alzheimer's disease (AD). However, the causal relationships between metabolism and AD are poorly understood.

OBJECTIVE

We aimed to investigate the causal association between circulating metabolites and risk of AD through two-sample Mendelian randomization (MR) approach.

METHODS

Genetic associations with 123 circulating metabolic traits were utilized as exposures. Summary statistics data from International Genomics of Alzheimer's Project was used in primary analysis, including 21,982 AD cases and 41,944 controls. Validation was performed using family history of AD data from UK Biobank (27,696 cases of maternal AD, 14,338 cases of paternal AD, and 272,244 controls). We utilized inverse-variance weighted method as primary method.

RESULTS

We found significantly increased risks of developing AD per standard deviation increase in the levels of circulating ApoB (odd ratio[OR] = 3.18; 95% confidence interval[CI]: 1.52-6.66, p = 0.0022), glycoprotein acetyls (OR = 1.21; 95% CI: 1.05-1.39, p = 0.0093), total cholesterol (OR = 2.73; 95% CI: 1.41-5.30, p = 0.0030), and low-density lipoprotein (LDL) cholesterol (OR = 2.34; 95% CI: 1.53-3.57, p = 0.0001). Whereas glutamine (OR = 0.81; 95% CI: 0.71-0.92, p = 0.0011) were significantly associated with lower risk of AD. We also detected causal effects of several different composition of LDL fractions on increased AD risk, which has been verified in validation. However, we found no association between circulating high-density lipoprotein cholesterol and AD.

CONCLUSION

Our findings suggest causal effects of circulating glycoprotein acetyls, ApoB, LDL cholesterol, and serum total cholesterol on higher risk of AD, whereas glutamine showed the protective effect.

Lipids in Pathophysiology and Development of the Membrane Lipid Therapy: New Bioactive Lipids

Membranes are mainly composed of a lipid bilayer and proteins, constituting a checkpoint for the entry and passage of signals and other molecules. Their composition can be modulated by diet, pathophysiological processes, and nutritional/pharmaceutical interventions. In addition to their use as an energy source, lipids have important structural and functional roles, e.g., fatty acyl moieties in phospholipids have distinct impacts on human health depending on their saturation, carbon length, and isometry. These and other membrane lipids have quite specific effects on the lipid bilayer structure, which regulates the interaction with signaling proteins. Alterations to lipids have been associated with important diseases, and, consequently, normalization of these alterations or regulatory interventions that control membrane lipid composition have therapeutic potential. This approach, termed membrane lipid therapy or membrane lipid replacement, has emerged as a novel technology platform for nutraceutical interventions and drug discovery. Several clinical trials and therapeutic products have validated this technology based on the understanding of membrane structure and function. The present review analyzes the molecular basis of this innovative approach, describing how membrane lipid composition and structure affects protein-lipid interactions, cell signaling, disease, and therapy (e.g., fatigue and cardiovascular, neurodegenerative, tumor, infectious diseases).

Phytosterols: Potential Metabolic Modulators in Neurodegenerative Diseases

Phytosterols constitute a class of natural products that are an important component of diet and have vast applications in foods, cosmetics, and herbal medicines. With many and diverse isolated structures in nature, they exhibit a broad range of biological and pharmacological activities. Among over 200 types of phytosterols, stigmasterol and β-sitosterol were ubiquitous in many plant species, exhibiting important aspects of activities related to neurodegenerative diseases. Hence, this mini-review presented an overview of the reported studies on selected phytosterols related to neurodegenerative diseases. It covered the major phytosterols based on biosynthetic considerations, including other phytosterols with significant in vitro and in vivo biological activities.

Apolipoprotein B is a novel marker for early tau pathology in Alzheimer's disease

INTRODUCTION

We examine the role of brain apolipoprotein B (apoB) as a putative marker of early tau pathology and cognitive decline.

METHODS

Cerebrospinal fluid (CSF) samples from cognitively normal and Alzheimer's disease (AD) participants were collected to measure protein levels of apoB and AD biomarkers amyloid beta (Aβ), t-tau and p-tau, as well as synaptic markers GAP43, SYNAPTOTAGMIN-1, synaptosome associated protein 25 (SNAP-25), and NEUROGRANIN. CSF apoB levels were contrasted with positron emission tomography (PET) scan measures of Aβ (18F-NAV4694) and Tau (flortaucipir) along with cognitive assessment alterations over 6 to 8 years.

RESULTS

CSF apoB levels were elevated in AD participants and correlated with t-tau, p-tau, and the four synaptic markers in pre-symptomatic individuals. In the latter, CSF apoB levels correlated with PET flortaucipir-binding in entorhinal, parahippocampal, and fusiform regions. Baseline CSF apoB levels were associated with longitudinal visuospatial cognitive decline.

DISCUSSION

CSF apoB markedly associates with early tau dysregulation in asymptomatic subjects and identifies at-risk individuals predisposed to develop visuospatial cognitive decline over time.

A multitude of signaling pathways associated with Alzheimer's disease and their roles in AD pathogenesis and therapy

The exact molecular mechanisms associated with Alzheimer's disease (AD) pathology continue to represent a mystery. In the past decades, comprehensive data were generated on the involvement of different signaling pathways in the AD pathogenesis. However, the utilization of signaling pathways as potential targets for the development of drugs against AD is rather limited due to the immense complexity of the brain and intricate molecular links between these pathways. Therefore, finding a correlation and cross-talk between these signaling pathways and establishing different therapeutic targets within and between those pathways are needed for better understanding of the biological events responsible for the AD-related neurodegeneration. For example, autophagy is a conservative cellular process that shows link with many other AD-related pathways and is crucial for maintenance of the correct cellular balance by degrading AD-associated pathogenic proteins. Considering the central role of autophagy in AD and its interplay with many other pathways, the finest therapeutic strategy to fight against AD is the use of autophagy as a target. As an essential step in this direction, this comprehensive review represents recent findings on the individual AD-related signaling pathways, describes key features of these pathways and their cross-talk with autophagy, represents current drug development, and introduces some of the multitarget beneficial approaches and strategies for the therapeutic intervention of AD.

Association between statin use and Alzheimer's disease with dose response relationship

This study aimed to determine the dose-response relationship between the levels of statin exposure and the incidence of Alzheimer's disease (AD). We included 119,013 Korean adults (≥ 60 years old) using a database from the Korean National Health Insurance Service (2002-2013). Statin exposure was treated as a time-varying variable. Incidence of AD was defined by the first claim code for AD with anti-Alzheimer drugs. AD occurred in 9467 cases during a median 7.2 years of follow-up. Overall, statin use was not associated with an increased risk of AD incidence [adjusted hazard ratio (aHR) = 1.04; 95% confidence interval (CI) = 0.99-1.10]. When examined by level of statin exposure, statin prescription < 540 days during a 2-year window time was associated with a higher risk for incidence of AD compared to statin non-use. However, days of prescription ≥ 540 and cumulative defined daily dose ≥ 540 of statin were associated with decreased risk of AD [aHR (95% CI) = 0.87 (0.80-0.95) and 0.79 (0.68-0.92), respectively]. Our findings indicate that less persistent statin use is associated with increased risk of AD, whereas persistent and adherent statin use is associated with decreased risk of AD.

Comprehensive Evaluation of the 5XFAD Mouse Model for Preclinical Testing Applications: A MODEL-AD Study

The ability to investigate therapeutic interventions in animal models of neurodegenerative diseases depends on extensive characterization of the model(s) being used. There are numerous models that have been generated to study Alzheimer's disease (AD) and the underlying pathogenesis of the disease. While transgenic models have been instrumental in understanding AD mechanisms and risk factors, they are limited in the degree of characteristics displayed in comparison with AD in humans, and the full spectrum of AD effects has yet to be recapitulated in a single mouse model. The Model Organism Development and Evaluation for Late-Onset Alzheimer's Disease (MODEL-AD) consortium was assembled by the National Institute on Aging (NIA) to develop more robust animal models of AD with increased relevance to human disease, standardize the characterization of AD mouse models, improve preclinical testing in animals, and establish clinically relevant AD biomarkers, among other aims toward enhancing the translational value of AD models in clinical drug design and treatment development. Here we have conducted a detailed characterization of the 5XFAD mouse, including transcriptomics, electroencephalogram, in vivo imaging, biochemical characterization, and behavioral assessments. The data from this study is publicly available through the AD Knowledge Portal.

Comprehensive Evaluation of the 5XFAD Mouse Model for Preclinical Testing Applications: A MODEL-AD Study

The ability to investigate therapeutic interventions in animal models of neurodegenerative diseases depends on extensive characterization of the model(s) being used. There are numerous models that have been generated to study Alzheimer's disease (AD) and the underlying pathogenesis of the disease. While transgenic models have been instrumental in understanding AD mechanisms and risk factors, they are limited in the degree of characteristics displayed in comparison with AD in humans, and the full spectrum of AD effects has yet to be recapitulated in a single mouse model. The Model Organism Development and Evaluation for Late-Onset Alzheimer's Disease (MODEL-AD) consortium was assembled by the National Institute on Aging (NIA) to develop more robust animal models of AD with increased relevance to human disease, standardize the characterization of AD mouse models, improve preclinical testing in animals, and establish clinically relevant AD biomarkers, among other aims toward enhancing the translational value of AD models in clinical drug design and treatment development. Here we have conducted a detailed characterization of the 5XFAD mouse, including transcriptomics, electroencephalogram, in vivo imaging, biochemical characterization, and behavioral assessments. The data from this study is publicly available through the AD Knowledge Portal.

Cholesterol Metabolism in Neurodegenerative Diseases: Molecular Mechanisms and Therapeutic Targets

Cholesterol is an indispensable component of the cell membrane and plays vital roles in critical physiological processes. Brain cholesterol accounts for a large portion of total cholesterol in the human body, and its content must be tightly regulated to ensure normal brain function. Disorders of cholesterol metabolism in the brain are linked to neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and other atypical cognitive deficits that arise at old age. However, the specific role of cholesterol metabolism disorder in the pathogenesis of neurodegenerative diseases has not been fully elucidated. Statins that are a class of lipid-lowering drugs have been reported to have a positive effect on neurodegenerative diseases. Herein, we reviewed the physiological and pathological conditions of cholesterol metabolism and discussed the possible mechanisms of cholesterol metabolism and statin therapy in neurodegenerative diseases.

Plasma Lipids as Biomarkers for Alzheimer's Disease: A Systematic Review

Alzheimer's disease (AD) is caused by several risk factors leading to dementia. It's diagnosis usually depends on clinical presentation and certain biomarkers in the cerebrospinal fluid (CSF). The brain has a high content of cholesterol and the metabolism of cholesterol in the brain can be associated with beta-amyloid plaques formation, which is seen in Alzheimer's disease. Given these implications, we studied if plasma lipid levels can vary in Alzheimer's disease and if these can be used as biomarkers to diagnose and predict the progression of Alzheimer's disease. Certain mutations in the brain cholesterol transport receptors and proteins and their association with Alzheimer's were also studied. This systematic review abides by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We searched multiple databases, such as Pubmed, Google Scholar, Pubmed central, ScienceDirect, Web of Science, and Medline with the help of keywords like Alzheimer's disease, cognitive impairment, plasma lipid biomarkers, cholesterol, brain cholesterol metabolism separately and in combination with each other. We collected 49 quality appraised articles on the association between plasma lipids and Alzheimer's disease and the genetic mutations in alleles related to cholesterol metabolism and Alzheimer's disease by applying the inclusion and exclusion criteria. Based on the finding of the studies reviewed, we found an association between plasma lipids, polymorphisms in genes associated with cholesterol transport, and Alzheimer's disease. Increased serum low-density lipoprotein (LDL-C), triglycerides (TG), total cholesterol (TC), sphingolipids, 24S hydroxycholesterol (24S-HC), 27O hydroxycholesterol (27O-HC) was associated with Alzheimer's. Decreased high-density lipoprotein (HDL-C) and phospholipids were noticed. Genetic mutations in apolipoprotein E (ApoE), apolipoprotein B (ApoB), apolipoprotein A (ApoA), ATP binding cassette transporter 1 (ABCA1), ATP binding cassette transporter 7 (ABCA7), amyloid precursor protein (APP), cytochrome P450 family 46 subfamilies A member 1 (CYP46A1), presenilin 1 (PSEN1), presenilin 2 (PSEN2) are also associated with increased risk of Alzheimer's disease. This study found an association between plasma lipids and Alzheimer's, proving that plasma lipids can be used as biomarkers for early diagnosis of Alzheimer's disease. It may also help predict the prognosis and stage the disease severity. Further studies are needed to find out the exact mechanism behind these changes.

Cerebrovascular Changes and Neurodegeneration Related to Hyperlipidemia: Characteristics of the Human ApoB-100 Transgenic Mice

Serum lipid levels are closely related to the structure and function of blood vessels. Chronic hyperlipidemia may lead to damage in both the cardio- and the cerebrovascular systems. Vascular dysfunctions, including impairments of the blood-brain barrier, are known to be associated with neurodegenerative diseases. A growing number of evidence suggests that cardiovascular risk factors, such as hyperlipidemia, may increase the likelihood of developing dementia. Due to differences in lipoprotein metabolism, wild-type mice are protected against diet-induced hypercholesterolemia, and their serum lipid profile is different from that observed in humans. Therefore, several transgenic mouse models have been established to study the role of different apolipoproteins and their receptors in lipid metabolism, as well as the complications related to pathological lipoprotein levels. This mini-review focused on a transgenic mouse model overexpressing an apolipoprotein, the human ApoB-100. We discussed literature data and current advancements on the understanding of ApoB-100 induced cardio- and cerebrovascular lesions in order to demonstrate the involvement of this type of apolipoprotein in a wide range of pathologies, and a link between hyperlipidemia and neurodegeneration.

Association of serum Apolipoprotein B with cerebrospinal fluid biomarkers of Alzheimer's pathology

Objective

To examine whether apolipoprotein B (ApoB), apolipoprotein A‐1 (ApoA1), or their ratio (ApoB/A1) were associated with early changes in cerebrospinal fluid (CSF) biomarkers of Alzheimer’s disease (AD) pathology in elderly adults with subjective cognitive decline (SCD).

Methods

This study included 507 objective cognitive normal participants from the Chinese Alzheimer’s Biomarker and LifestylE (CABLE) database including 288 cognitive normal participants (CN) and 219 SCD. Multiple linear regression models were used to examine the associations of apolipoproteins with CSF AD biomarkers.

Results

Compared with control group, SCD participants with significant AD biological characteristics had lower ApoB levels (P = 0.0461). In total participants, lower level of serum ApoB was associated with decreases in CSF Aβ42 (P = 0.0015) and Aβ42/40 (P = 0.0081) as well as increases in CSF p‐tau/Aβ42 (P < 0.0001) and t‐tau/Aβ42 (P = 0.0013), independent of APOEɛ4 status. In further subgroup analysis, these associations were more significant in SCD participants (ApoB × Diagnose: P < 0.05). In addition, lower levels of ApoB were also found associated with increases in p‐tau in the SCD subgroup (P = 0.0263). Furthermore, these protective associations were more significant in the overweight participants (ApoB × weight: P < 0.05). Results showed no association between ApoA1 and CSF biomarkers.

Interpretation

This study is the first to find protective associations of serum ApoB with CSF AD core biomarkers, especially in SCD individuals. It indicated that ApoB may be a potential biomarker for preclinical AD and may play different roles in different stages of AD.

Blood-Based Biomarkers for Predictive Diagnosis of Cognitive Impairment in a Pakistani Population

Numerous studies have identified an association between age-related cognitive impairment (CI) and oxidative damage, accumulation of metals, amyloid levels, tau, and deranged lipid profile. There is a concerted effort to establish the reliability of these blood-based biomarkers for predictive diagnosis of CI and its progression. We assessed the serum levels of high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, total cholesterol, selected metals (Cu, Al, Zn, Pb, Mn, Cad), and total-tau and amyloid beta-42 protein in mild (n = 71), moderate (n = 86) and severe (n = 25) cognitively impaired patients and compared them with age-matched healthy controls (n = 90) from Pakistan. We found that a decrease in HDL cholesterol (correlation coefficient r = 0.467) and amyloid beta-42 (r = 0.451) were associated with increased severity of CI. On the other hand, an increase in cholesterol ratio (r = -0.562), LDL cholesterol (r = -0.428), triglycerides, and total-tau (r = -0.443) were associated with increased severity of CI. Increases in cholesterol ratio showed the strongest association and correlated with increases in tau concentration (r = 0.368), and increased triglycerides were associated with decreased amyloid beta-42 (r = -0.345). Increased Cu levels showed the strongest association with tau increase and increased Zn and Pb levels showed the strongest association with reduced amyloid beta-42 levels. Receiver Operating Characteristic (ROC) showed the cutoff values of blood metals (Al, Pb, Cu, Cad, Zn, and Mn), total-tau, and amyloid beta-42 with sensitivity and specificity. Our data show for the first time that blood lipids, metals (particularly Cu, Zn, Pb, and Al), serum amyloid-beta-42/tau proteins modulate each other's levels and can be collectively used as a predictive marker for CI.

Acidifying Endolysosomes Prevented Low-Density Lipoprotein-Induced Amyloidogenesis

Cholesterol dyshomeostasis has been linked to the pathogenesis of sporadic Alzheimer's disease (AD). In furthering the understanding of mechanisms by which increased levels of circulating cholesterol augments the risk of developing sporadic AD, others and we have reported that low-density lipoprotein (LDL) enters brain parenchyma by disrupting the blood-brain barrier and that endolysosome de-acidification plays a role in LDL-induced amyloidogenesis in neurons. Here, we tested the hypothesis that endolysosome de-acidification was central to amyloid-β (Aβ) generation and that acidifying endolysosomes protects against LDL-induced increases in Aβ levels in neurons. We demonstrated that LDL, but not HDL, de-acidified endolysosomes and increased intraneuronal and secreted levels of Aβ. ML-SA1, an agonist of endolysosome-resident TRPML1 channels, acidified endolysosomes, and TRPML1 knockdown attenuated ML-SA1-induced endolysosome acidification. ML-SA1 blocked LDL-induced increases in intraneuronal and secreted levels of Aβ as well as Aβ accumulation in endolysosomes, prevented BACE1 accumulation in endolysosomes, and decreased BACE1 activity levels. LDL downregulated TRPML1 protein levels, and TRPML1 knockdown worsens LDL-induced increases in Aβ. Our findings suggest that endolysosome acidification by activating TRPML1 may represent a protective strategy against sporadic AD.

Lipids and Alzheimer's Disease

Lipids, as the basic component of cell membranes, play an important role in human health as well as brain function. The brain is highly enriched in lipids, and disruption of lipid homeostasis is related to neurologic disorders as well as neurodegenerative diseases such as Alzheimer’s disease (AD). Aging is associated with changes in lipid composition. Alterations of fatty acids at the level of lipid rafts and cerebral lipid peroxidation were found in the early stage of AD. Genetic and environmental factors such as apolipoprotein and lipid transporter carrying status and dietary lipid content are associated with AD. Insight into the connection between lipids and AD is crucial to unraveling the metabolic aspects of this puzzling disease. Recent advances in lipid analytical methodology have led us to gain an in-depth understanding on lipids. As a result, lipidomics have becoming a hot topic of investigation in AD, in order to find biomarkers for disease prediction, diagnosis, and prevention, with the ultimate goal of discovering novel therapeutics.

Low-Density Lipoprotein Cholesterol and Alzheimer's Disease: A Systematic Review and Meta-Analysis

Objective: To assess the association between low-density lipoprotein cholesterol (LDL-c) and risk of Alzheimer's disease (AD). Methods: Embase, Pubmed, and Web of Science were searched until June 2019. Standard mean difference (SMD) with 95% confidence intervals (CI) was estimated using random-effects models. Results: Our meta-analysis of 26 studies revealed higher levels of LDL-c in AD than that of non-dementia controls (SMD = 0.35, 95% CI 0.12-0.58, p < 0.01). The meta-regression analysis on confounders showed that age (p < 0.01, Adj R-squared = 92.41%) and cardiovascular disease (p = 0.01, Adj R-squared = 85.21%), but not the body mass index, education, smoking, hypertension and diabetes mellitus, exerted an impact on the relationship between LDL-c and risk of ICH. Further subgroup analysis of age showed LDL-c levels in AD patients aged 60-70 were higher than that of non-dementia (60 ≤ age < 70: SMD = 0.80, 95% CI 0.23-1.37, p < 0.01); but no association between the SMD of AD in LDL-c and age over 70 was noted across the studies (70 ≤ age < 77: SMD = -0.02, 95% CI -0.39~0.34, p = 9.0; 77 ≤ age < 80: SMD = 0.15, 95% CI -0.17~0.47, p = 0.35; ≥80: SMD = 0.53, 95% CI -0.04~1.11, p = 0.07). The concentrations of LDL-c during the quintile interval of 3~4 were positively associated with AD (121 ≤ concentration < 137: SMD = 0.98, 95% CI 0.13~1.82, p = 0.02; ≥137: SMD = 0.62, 95% CI 0.18~1.06, p < 0.01); whereas there was no correlation between AD and LDL-c within the quintile interval of 1~2 (103.9 ≤ concentration < 112: SMD = 0.08, 95% CI -0.20~0.35, p = 0.59; 112 ≤ concentration < 121: SMD = -0.26, 95% CI -0.58~0.06, p = 0.11). Conclusions: Elevated concentration of LDL-c (>121 mg/dl) may be a potential risk factor for AD. This association is strong in patients aged 60-70 years, but vanishes with advancing age.

Elevated serum TC and LDL-C levels in Alzheimer's disease and mild cognitive impairment: A meta-analysis study

Serum lipid levels such as triglyceride and cholesterol has been reported to play an important role in the pathophysiological process of Alzheimer disease (AD) and mild cognitive impairment (MCI). However, it still remains controversial in different studies. Here, we performed a meta-analysis to assess the importance of serum levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) in AD and MCI patients. PubMed, China National Knowledge Infrastructure (CNKI) system database were used to identify 17 studies (10 AD-only + 4 MCI-only + 3 shared AD/MCI), including 2333 cases and 3615 healthy controls (HC). We found that compared with HC, both the serum TC levels [SMD = 0.58; 95%CI (0.25, 0.90); P = 0.001) and the serum LDL-C levels [SMD = 0.7780; 95%CI (0.3940, 1.1521); P = 0.000] were higher in cognitive impairment population (including AD and MCI) than those in HC, respectively. Furthermore, we analyzed the serum TC and LDL-C levels in AD and MCI patients. We found that the serum TC levels [SMD = 0.76; 95% CI (0.13, 1.40); P = 0.019]1 and the LDL-C levels [SMD = 1.40; 95% CI (0.70, 2.10; P = 0.000] were increased in AD patients. In the MCI patients, the serum TC levels [SMD = 0.30; 95%CI (0.01, 0.59); P = 0.041] had a significantly upward trend, while the LDL-C levels had no significant change, compared with HC subjects. However, there is no significant changes in HDL-C and TG levels in AD or MCI patients. Therefore, our results suggested that the elevated TC and LDL-C levels may be a potential risk factor for cognitive impairment.

Emerging roles for high-density lipoproteins in neurodegenerative disorders

Lipoproteins are the complexes of different lipids and proteins, which are devoted to the transport and clearance of lipids or lipid-related molecules in the circulation. Lipoproteins have been found to play a crucial role in brain function and may influence myelination process. Among lipoproteins, high-density lipoproteins (HDLs) and their major protein component, apoA-I, are directly involved in cholesterol efflux in the brain. It has been suggested that inadequate or dysfunctional brain HDLs may contribute to cerebrovascular dysfunctions, neurodegeneration, or neurovascular instability. HDL deficiency could also promote cognitive decline through impacting on atherosclerotic risk. The focus of this review is to discuss knowledge on HDL dysregulation in neurological disorders. A better understanding on how changes in cellular HDL and apolipoprotein homeostasis affect central nervous system function may provide promising novel avenues for the treatment of specific HDL-related neurological disorders.

Development of AD-Like Pathology in Skeletal Muscle

Effective therapeutic strategy against Alzheimer's disease (AD) requires early detection of AD; however, clinical diagnosis of Alzheimer's disease (AD) is not precise and a definitive diagnosis of AD is only possible via postmortem examination for AD pathological hallmarks including senile plaques composed of Aβ and neuro fibrillary tangles composed of phosphorylated tau. Although a variety of biomarker has been developed and used in clinical setting, none of them robustly predicts subsequent clinical course of AD. Thus, it is essential to identify new biomarkers that may facilitate the diagnosis of early stages of AD, prediction of subsequent clinical course, and development of new therapeutic strategies. Given that pathological hallmarks of AD including Aβaccumulation and the presence of phosphorylated tau are also detected in peripheral tissues, AD is considered a systemic disease. Without the protection of blood-brain barrier, systemic factors can affect peripheral tissues much earlier than neurons in brain. Here, we will discuss the development of AD-like pathology in skeletal muscle and the potential use of skeletal muscle biopsy (examination for Aβaccumulation and phosphorylated tau) as a biomarker for AD.

The gender- and age- dependent relationships between serum lipids and cognitive impairment: a cross-sectional study in a rural area of Xi'an, China

Background

Serum lipids [total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and triglyceride (TG)] are risk factors for stroke, but the relationships between serum lipids and cognitive impairment have not been verified completely. In this study, we studied the relationships between serum lipids and cognitive impairment and explored whether gender and age had effects on the relationships.

Methods

In this cross-sectional study, we collected serum lipids and cognitive function information from 1762 participants (aged 40–85). Univariate analysis, multivariate analysis, and both gender- and age-based stratified multivariate analysis were used.

Results

In the entire sample set, there was no significant correlation between serum lipid parameters (TC, LDL-C, HDL-C and TG) and cognitive impairment. In both gender- and age-based stratified multivariate analysis, high serum TC was positively associated with cognitive impairment in the elderly (> 55) male participants (OR = 4.404, 95% CI = 1.264–15.344, p = 0.02), and high serum LDL-C was positively correlated with cognitive impairment in the elderly female subjects (OR = 2.496, 95% CI = 1.057–5.896, p = 0.037), while high serum TG was negatively associated with cognitive impairment in the middle-aged (≤ 55) male participants (OR = 0.157, 95% CI = 0.051–0.484, p = 0.001).

Conclusions

The relationships between serum lipids and cognitive impairment are gender- and age- dependent, with high serum TC and LDL-C may be risk factors of cognitive impairment in the elderly male and female subjects respectively, while high serum TG may be protector of cognitive impairment in the middle-aged male participants.

Cerebrovascular Pathology in Hypertriglyceridemic APOB-100 Transgenic Mice

Hypertriglyceridemia is not only a serious risk factor in the development of cardiovascular diseases, but it is linked to neurodegeneration, too. Previously, we generated transgenic mice overexpressing the human APOB-100 protein, a mouse model of human atherosclerosis. In this model we observed high plasma levels of triglycerides, oxidative stress, tau hyperphosphorylation, synaptic dysfunction, cognitive impairment, increased neural apoptosis and neurodegeneration. Neurovascular dysfunction is recognized as a key factor in the development of neurodegenerative diseases, but the cellular and molecular events linking cerebrovascular pathology and neurodegeneration are not fully understood. Our aim was to study cerebrovascular changes in APOB-100 transgenic mice. We described the kinetics of the development of chronic hypertriglyceridemia in the transgenic animals. Increased blood-brain barrier permeability was found in the hippocampus of APOB-100 transgenic mice which was accompanied by structural changes. Using transmission electron microscopy, we detected changes in the brain capillary endothelial tight junction structure and edematous swelling of astrocyte endfeet. In brain microvessels isolated from APOB-100 transgenic animals increased Lox-1, Aqp4, and decreased Meox-2, Mfsd2a, Abcb1a, Lrp2, Glut-1, Nos2, Nos3, Vim, and in transgenic brains reduced Cdh2 and Gfap-σ gene expressions were measured using quantitative real-time PCR. We confirmed the decreased P-glycoprotein (ABCB1) and vimentin expression related to the neurovascular unit by immunostaining in transgenic brain sections using confocal microscopy. We conclude that in chronic hypertriglyceridemic APOB-100 transgenic mice both functional and morphological cerebrovascular pathology can be observed, and this animal model could be a useful tool to study the link between cerebrovascular pathology and neurodegeneration.

Decreased plasma C-reactive protein levels in APOE ε4 allele carriers

Objective

Apolipoprotein E (APOE) ε4 allele is a well‐established risk factor in Alzheimer's disease (AD). Here, we assessed the effects of APOE polymorphism on cardiovascular, metabolic, and inflammation‐related parameters in population‐based cohorts.

Methods

Association of cardiovascular, metabolic, and inflammation‐related parameters with the APOE polymorphism in a large Finnish Metabolic Syndrome in Men (METSIM) cohort and Finnish Geriatric Intervention study to prevent cognitive impairment and disability (FINGER) were investigated. Brain‐specific effects were addressed in postmortem brain samples.

Results

Individuals carrying the APOE ε4 allele displayed significantly elevated serum/plasma LDL cholesterol and apolipoprotein B levels. APOE ε3ε4 and ε4ε4 significantly associated with lower levels of plasma high‐sensitivity C‐reactive protein (hs‐CRP). Plasma amyloid‐β 42 (Aβ42) and reduced hs‐CRP levels showed an association independently of the APOE status.

Interpretation

These data suggest that the APOE ε4 allele associates with lower levels of hs‐CRP in individuals without dementia. Moreover, Aβ42 may encompass anti‐inflammatory effects reflected by reduced hs‐CRP levels.

Influences of Pinpoint Plantar Long-Wavelength Infrared Light Irradiation (Stress-Free Therapy) on Chorioretinal Hemodynamics, Atherosclerosis Factors, and Vascular Endothelial Growth Factor

Background

We previously reported that pinpoint plantar long-wavelength infrared light irradiation (stress-free therapy; SFT) is useful for alleviating insulin resistance and improving intracranial blood flow in patients with type 2 diabetes mellitus. This study was undertaken to evaluate the influences of SFT on chorioretinal hemodynamics (retinal artery and vein blood flows) as well as atherosclerosis-related factors (TG, LDL-C) and VEGF in patients with dyslipidemia.

Methods

Four patients with dyslipidemia received 15-minute irradiation with a stress-free apparatus (far-infrared wavelength, 30 mW). Using laser speckle flowgraphy, associations of chorioretinal blood flow with peripheral atherosclerosis-inducing factors/VEGF levels before and after irradiation were analyzed.

Results

Chorioretinal blood flow increased, while TG/LDL-C levels decreased, after irradiation. VEGF tended to rise in cases with pre-irradiation baseline levels at the lower limit but tended to decrease in cases in which baseline levels had exceeded the normal range.

Conclusion

SFT was suggested to enhance chorioretinal circulation and to normalize VEGF, thereby possibly contributing to amelioration of atherosclerosis-inducing factors. Abnormalities in chorioretinal hemodynamics are known to be highly involved in the pathophysiology of diabetic retinopathy and age-related macular degeneration, and anti-VEGF antibody has been used for treating these conditions. The necessity of risk management, involving chorioretinal blood flow, has been pointed out when dealing with central retinal vein occlusion, diabetes mellitus, ischemic cerebral/cardiac disease, dementia and so on. SFT is therefore a potential complementary medical strategy which can be expected to contribute to normalization of chorioretinal blood flow and atherosclerosis-inducing factors/VEGF levels, and thereby to the prevention of lifestyle-related chronic diseases.

TG haplotype in the LRP8 is associated with myocardial infarction in south Indian population

Myocardial infarction (MI) is a complex multifactorial cardiovascular disease. India experiences a much greater burden of MI, also suggesting an experimental increase of this burden in the future. The absolute reasons for MI are context dependent and differ with different geographical settings. Several reports indicate that SNPs that are associated with certain diseases in other populations may not be associated with Indian population. It is, therefore, important to validate the association of SNPs. Low density lipoprotein receptor related protein 8 (LRP8) gene plays central role in human lipoprotein metabolism as it facilitates the clearance of bad cholesterol LDL, VLDL from plasma and is reported to be associated with MI in the western population. However, this gene has not been studied in the South Indian population. We aim to test the role of the LRP8 gene variants correlating with the lipid profile in MI patients in South Indian population. We sequenced regions of SNPs rs10788952, rs7546246, rs2297660 and rs5174 of LRP8 in 100 MI patients and 100 age-matched controls. Our result revealed a total of 4 variations. None of the SNPs were significantly associated with MI (p>0.973). Interestingly, haplotype based association analysis showed TG and CG of rs10788952 and rs7546246 significantly associated with MI (p<0.01 and p<0.00005) and in particular, haplotype TG was positively correlated with the risk of MI, as this increased the LDL and total cholesterol level in MI patients in south Indians. Our results suggest that haplotype TG is a risk factor for MI in South Indian population.

Electronegative Low-Density Lipoprotein L5 Impairs Viability and NGF-Induced Neuronal Differentiation of PC12 Cells via LOX-1

There have been striking associations of cardiovascular diseases (e.g., atherosclerosis) and hypercholesterolemia with increased risk of neurodegeneration including Alzheimer's disease (AD). Low-density lipoprotein (LDL), a cardiovascular risk factor, plays a crucial role in AD pathogenesis; further, L5, a human plasma LDL fraction with high electronegativity, may be a factor contributing to AD-type dementia. Although L5 contributing to atherosclerosis progression has been studied, its role in inducing neurodegeneration remains unclear. Here, PC12 cell culture was used for treatments with human LDLs (L1, L5, or oxLDL), and subsequently cell viability and nerve growth factor (NGF)-induced neuronal differentiation were assessed. We identified L5 as a neurotoxic LDL, as demonstrated by decreased cell viability in a time- and concentration-dependent manner. Contrarily, L1 had no such effect. L5 caused cell damage by inducing ATM/H2AX-associated DNA breakage as well as by activating apoptosis via lectin-like oxidized LDL receptor-1 (LOX-1) signaling to p53 and ensuring cleavage of caspase-3. Additionally, sublethal L5 long-termly inhibited neurite outgrowth in NGF-treated PC12 cells, as evidenced by downregulation of early growth response factor-1 and neurofilament-M. This inhibitory effect was mediated via an interaction between L5 and LOX-1 to suppress NGF-induced activation of PI3k/Akt cascade, but not NGF receptor TrkA and downstream MAPK pathways. Together, our data suggest that L5 creates a neurotoxic stress via LOX-1 in PC12 cells, thereby leading to impairment of viability and NGF-induced differentiation. Atherogenic L5 likely contributes to neurodegenerative disorders.

Alzheimer's Disease Risk Genes and Lipid Regulators

Brain lipid homeostasis plays an important role in Alzheimer's disease (AD) and other neurodegenerative disorders. Aggregation of amyloid-β peptide is one of the major events in AD. The complex interplay between lipids and amyloid-β accumulation has been intensively investigated. The proportions of lipid components including phospholipids, sphingolipids, and cholesterol are roughly similar across different brain regions under physiological conditions. However, disruption of brain lipid homeostasis has been described in AD and implicated in disease pathogenesis. Moreover, studies suggest that analysis of lipid composition in plasma and cerebrospinal fluid could improve our understanding of the disease development and progression, which could potentially serve as disease biomarkers and prognostic indicators for AD therapies. Here, we summarize the functional roles of AD risk genes and lipid regulators that modulate brain lipid homeostasis including different lipid species, lipid complexes, and lipid transporters, particularly their effects on amyloid processing, clearance, and aggregation, as well as neuro-toxicities that contribute to AD pathogenesis.