Apolipoprotein A-II is a key regulatory factor of HDL metabolism as appears from studies with transgenic animals and clinical outcomes

RNA Sequencing of Whole Blood in Premature Coronary Artery Disease: Identification of Novel Biomarkers and Involvement of T Cell Imbalance

Serum biomarkers were explored based on the peripheral blood gene expression profiles of premature coronary artery disease (PCAD). RNA sequencing (RNA-Seq) was used to detect PCAD-specific differentially expressed genes (DEGs). Quantitative real-time polymerase chain reaction (RT-PCR) was used to validate the most significant DEGs, and enzyme-linked immunosorbent assay (ELISA) was utilized to quantify the effect on corresponding serum proteins. Fifty-nine PCAD-specific DEGs were identified. Functional analysis showed positive regulation of T cell-mediated cytotoxicity, regulation of T cell-mediated immunity, and the regulation of alpha-beta T cell proliferation which were enriched in PCAD. RT-PCR validated the significant difference in the expression of BAG6, MUC5B, and APOA2 between PCAD and late-onset coronary artery disease (LCAD) patients. ELISA validation showed serum MUC5B increased dramatically in PCAD when compared to LCAD. Our study found T cells contribute to the occurrence of PCAD, and the inflammatory factor MUC5B may be a novel serum marker in PCAD patients.

Effect of hyperlipidemia on the outcome of in vitro fertilization in non-obese patients with polycystic ovary syndrome

Introduction

It is little known whether hyperlipidemia alone has adverse effects on the outcome of in vitro fertilization (IVF) in patients with polycystic ovarian syndrome (PCOS).

Methods

The PCOS patients with body mass index (BMI) < 30 kg/m2 were performed IVF or intracytoplasmic sperm injection treatment, including 208 fresh cycles and 127 frozen embryo transfer (FET) cycles. All the patients were divided into hyperlipidemia and control groups, and embryo quality and pregnancy outcomes between the two groups were compared.

Results

In the fresh cycles, total gonadotropin dosage in the control group was significantly lower than that in the hyperlipidemia group, and serum estradiol levels on trigger day were reversed (P < 0.05). The embryo fragment score was positively correlated with serum low-density lipoprotein level (r = 0.06, P < 0.05) and negatively with serum high-density lipoprotein (HDL) and lipoprotein A levels (r = -0.489 and -0.085, P < 0.01). Logistic regression analysis found that HDL was beneficial for clinical pregnancy (OR = 0.355, 95% CI: 0.135-0.938, P < 0.05). In the FET cycles, there were no differences in pulse index, systolic/diastolic ratio and serum estradiol and progesterone levels between the two groups, but resistance index in the hyperlipidemia group was significantly higher than that in the control group (P < 0.05).

Conclusion

Hyperlipidemia may increase the dosage of gonadotropin and have adverse effect on the embryo quality, endometrial receptivity, and clinical outcomes of lean PCOS patients. It is recommended that the non-obese patients with hyperlipidemia and PCOS perform lipid-lowering treatment before undergoing embryo transfer.

HDL-apoA-II Is Strongly Associated with 1-Year Mortality in Acute Heart Failure Patients

The prognostic value of the subset of high-density lipoprotein (HDL) particles containing apolipoprotein (apo)A-II (HDL-apoA-II) in acute heart failure (AHF) remains unexplored. In this study, baseline serum levels of HDL-apoA-II (total and subfractions 1−4) were measured in 315 AHF patients using NMR spectroscopy. The mean patient age was 74.2 ± 10.5 years, 136 (43.2%) were female, 288 (91.4%) had a history of cardiomyopathy, 298 (94.6%) presented as New York Heart Association class 4, and 118 (37.5%) patients died within 1 year after hospitalization for AHF. Multivariable Cox regression analyses, adjusted for age and sex as well as other clinical and laboratory parameters associated with 1-year mortality in the univariable analyses, revealed a significant inverse association of HDL-apoA-II (hazard ratio (HR) 0.67 per 1 standard deviation (1 SD) increase, 95% confidence interval (CI) 0.47−0.94, p = 0.020), HDL2-apoA-II (HR 0.72 per 1 SD increase, 95% CI 0.54−0.95, p = 0.019), and HDL3-apoA-II (HR 0.59 per 1 SD increase, 95% CI 0.43−0.80, p < 0.001) with 1-year mortality. We conclude that low baseline HDL-apoA-II, HDL2-apoA-II, and HDL3-apoA-II serum levels are associated with increased 1-year mortality in AHF patients and may thus be of prognostic value in AHF.

Apolipoprotein A-II, a Player in Multiple Processes and Diseases

Apolipoprotein A-II (apoA-II) is the second most abundant apolipoprotein in high-density lipoprotein (HDL) particles, playing an important role in lipid metabolism. Human and murine apoA-II proteins have dissimilar properties, partially because human apoA-II is dimeric whereas the murine homolog is a monomer, suggesting that the role of apoA-II may be quite different in humans and mice. As a component of HDL, apoA-II influences lipid metabolism, being directly or indirectly involved in vascular diseases. Clinical and epidemiological studies resulted in conflicting findings regarding the proatherogenic or atheroprotective role of apoA-II. Human apoA-II deficiency has little influence on lipoprotein levels with no obvious clinical consequences, while murine apoA-II deficiency causes HDL deficit in mice. In humans, an increased plasma apoA-II concentration causes hypertriglyceridemia and lowers HDL levels. This dyslipidemia leads to glucose intolerance, and the ensuing high blood glucose enhances apoA-II transcription, generating a vicious circle that may cause type 2 diabetes (T2D). ApoA-II is also used as a biomarker in various diseases, such as pancreatic cancer. Herein, we provide a review of the most recent findings regarding the roles of apoA-II and its functions in various physiological processes and disease states, such as cardiovascular disease, cancer, amyloidosis, hepatitis, insulin resistance, obesity, and T2D.

Dynamic protein structures in normal function and pathologic misfolding in systemic amyloidosis

Dynamic and disordered regions in native proteins are often critical for their function, particularly in ligand binding and signaling. In certain proteins, however, such regions can contribute to misfolding and pathologic deposition as amyloid fibrils in vivo. For example, dynamic and disordered regions can promote amyloid formation by destabilizing the native structure, by directly triggering the aggregation, by promoting protein condensation, or by acting as sites of early proteolytic cleavage that favor a release of aggregation-prone fragments or facilitate fibril maturation. At the same time, enhanced dynamics in the native protein state accelerates proteolytic degradation that counteracts amyloid accumulation in vivo. Therefore, the functional need for dynamic protein regions must be balanced against their inherently labile nature. How exactly this balance is achieved and how is it shifted upon amyloidogenic mutations or post-translational modifications? To illustrate possible scenarios, here we review the beneficial and pathologic roles of dynamic and disordered regions in the native states of three families of human plasma proteins that form amyloid precursors in systemic amyloidoses: immunoglobulin light chain, apolipoproteins, and serum amyloid A. Analysis of structure, stability and local dynamics of these diverse proteins and their amyloidogenic variants exemplifies how disordered/dynamic regions can provide a functional advantage as well as an Achilles heel in pathologic amyloid formation.

Phytochemical‑rich herbal formula ATG‑125 protects against sucrose‑induced gastrocnemius muscle atrophy by rescuing Akt signaling and improving mitochondrial dysfunction in young adult mice

The antioxidant capability of herbal remedies has attracted widespread attention, but their molecular mechanisms in a muscle atrophy model have not been explored. The aim of the present study was to compare the bioactivity of sucrose challenged mice following treatment with ATG‑125. Here, through a combination of transcriptomic and biomedical analysis, herbal formula ATG‑125, a phytochemical‑rich formula, was identified as a protective factor against muscle atrophy in sucrose challenged mice. Gene ontology (GO) identified differentially expressed genes that were primarily enriched in the 'negative regulation of proteolysis', 'cellular amino acid metabolic process', 'lipoprotein particle' and 'cell cycle', all of which were associated with the ATG‑125‑mediated prevention of muscle atrophy, particularly with regard to mitochondrial biogenesis. In skeletal muscle, a set of mitochondrial‑related genes, including angiopoietin‑like 4, nicotinamide riboside kinase 2 (Nmrk2), pyruvate dehydrogenase lipoamide kinase isozyme 4, Asc‑type amino acid transporter 1 and mitochondrial uncoupling protein 3 (Ucp3) were markedly upregulated following ATG‑125 intervention. An increase in Nmrk2 and Ucp3 expression were noted after ATG‑125 treatment, in parallel with upregulation of the 'nicotinate and nicotinamide metabolism' pathway, as determined using the Kyoto Encyclopedia of Genes and Genomes (KEGG). Furthermore, KEGG pathway analysis revealed the downregulation of 'complement and coagulation cascades', 'cholesterol metabolism', 'biosynthesis of amino acids' and 'PPAR signaling pathway', which were associated with the downregulation of serine (or cysteine) peptidase inhibitor clade A member (Serpina)3, Serpina1b, Serpina1d, Serpina1e, apolipoprotein (Apo)a1 and Apoa2, all of which were cardiovascular and diabetes‑associated risk factors and were regulated by ATG‑125. In addition, ATG‑125 treatment resulted in downregulated mRNA expression levels of ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 2, troponin‑I1, troponin‑C1 and troponin‑T1 in young adult gastrocnemius muscle compared with the sucrose group. Nuclear factor‑κB‑hypoxia inducible factor‑1α‑TGFβ receptor type‑II‑vascular endothelial growth factor staining indicated that ATG‑125 decreased sucrose‑induced chronic inflammation. ATG‑125 was sufficient to prevent muscle atrophy, and this protective effect may be mediated through upregulation of AKT phosphorylation, upregulating the insulin growth factor‑1R‑insulin receptor substrate‑PI3K‑AKT pathway, which in turn resulted in a forkhead box O‑dependent decrease in protein degradation pathways, including regulation of atrogin1 and E3 ubiquitin‑protein ligase TRIM63. Peroxisome‑proliferator activated receptor γ coactivator 1α (PGC1α) was decreased in young adult mice challenged with sucrose. ATG‑125 treatment significantly increased PGC1α and significantly increased UCP‑1,2,3 expression levels, which suggested ATG‑125 poised the mitochondria for uncoupling of respiration. This effect is consistent with the increased SIRT1 levels and may explain an increase in mitochondria biogenesis. Taken together, the present study showed that ATG‑125, as an integrator of protein synthesis and degradative pathways, prevented muscle wasting.

Atherosclerotic cardiovascular disease in hyperalphalipoproteinemia due to LIPG variants

BACKGROUND

High density lipoprotein cholesterol (HDL-C) concentration correlates inversely with atherosclerotic cardiovascular disease (ASCVD) risk and is included in risk calculations. Endothelial lipase (EL) is a phospholipase that remodels HDL. Deficiency of EL due to mutations in its gene, LIPG, is associated with hyperalphalipoproteinemia. The effects of EL on HDL function and ASCVD risk remain poorly understood.

OBJECTIVES

To determine whether hyperalphalipoproteinemia due to EL deficiency is protective against ASCVD.

METHODS

We identified LIPG variants amongst patients with severe hyperalphalipoproteinemia (HDL-C >2.5 mmol/L) attending a referral lipid clinic in the Western Cape Province of South Africa. We analysed the clinical and biochemical phenotypes amongst primary hyperalphalipoproteinemia cases (males HDL-C >1.6 mmol/L; females HDL-C >1.8 mmol/L) due to LIPG variants, and the distribution of variants in normal and hyperalphalipoproteinemia ranges of HDL-C.

RESULTS

1007 patients with HDL-C concentration ranging from 1.2 to 4.5 mmol/L were included. Seventeen females had primary hyperalphalipoproteinemia. Vascular disease was prominent, but not associated with HDL-C concentration, LDL-C concentration or carotid artery intima media thickness. Two novel and three known LIPG variants were identified in severe hyperalphalipoproteinemia. Four additional variants were identified in the extended cohort. Two common variants appeared normally distributed across the HDL-C concentration range, while six less-common variants were found only at higher HDL-C concentrations. One rare variant had a moderate effect.

CONCLUSION

Hyperalphalipoproteinemia due to LIPG variants is commoner in females and may not protect against ASCVD. Use of current risk calculations may be inappropriate in patients with hyperalphalipoproteinemia due to EL deficiency. Our study cautions targeting EL to reduce risk.

Apolipoprotein A2 Isoforms in Relation to the Risk of Myocardial Infarction: A Nested Case-Control Analysis in the JPHC Study

AIM

The fact that low concentrations of high-density lipoprotein cholesterol are associated with the risk of cardiovascular disease is well known, but high-density lipoprotein metabolism has not been fully understood. Apolipoprotein A2 (ApoA2) is the second-most dominant apolipoprotein of high-density lipoprotein. We tested the hypothesis that ApoA2 isoforms are inversely associated with myocardial infarction.

METHODS

We measured the plasma levels of three ApoA2 isoforms (ApoA2-ATQ/ATQ, ApoA2-ATQ/AT, ApoA2-AT/AT) in nested case-control study samples of 1:2 from the Japan Public Health-Center-based Study (JPHC Study): 106 myocardial infarction incidence cases and 212 controls.

RESULTS

ApoA2-AT/AT was inversely associated with risk of myocardial infarction, in a matched model (OR, 2.78; 95% CI, 1.26-6.09 for lowest compared with the highest quartile), but its association was attenuated after adjustment for smoking only (OR=2.13; 95% CI, 0.91-4.97) or drinking only (OR=2.11; 0.91-4.89), and the multivariable OR was 1.20 (95% CI, 0.41-3.57). Neither ApoA2-ATQ/ATQ nor ApoA2-ATQ/AT was associated with the risk of myocardial infarction.

CONCLUSIONS

Our nested case-control study did not show a significant association of ApoA2 isoforms with a risk of myocardial infarction.

Generation of Gene-Knockout Mongolian Gerbils via CRISPR/Cas9 System

The Mongolian gerbil (Meriones unguiculatus), a well-known "multifunctional" experimental animal, plays a crucial role in the research of hearing, cerebrovascular diseases and Helicobacter pylori infection. Although the whole-genome sequencing of Mongolian gerbils has been recently completed, lack of valid gene-editing systems for gerbils largely limited the further usage of Mongolian gerbils in biomedical research. Here, efficient targeted mutagenesis in Mongolian gerbils was successfully conducted by pronuclear injection with Cas9 protein and single-guide RNAs (sgRNAs) targeting Cystatin C (Cst3) or Apolipoprotein A-II (Apoa2). We found that 22 h after human chorionic gonadotropin (hCG) injection, zygote microinjection was conducted, and the injected zygotes were transferred into the pseudopregnant gerbils, which were induced by injecting equine chorionic gonadotropin (eCG) and hCG at a 70 h interval and being caged with ligated male gerbils. We successfully obtained Cst3 and Apoa2 gene knockout gerbils with the knockout efficiencies of 55 and 30.9%, respectively. No off-target effects were detected in all knockout gerbils and the mutations can be germline-transmitted. The absence of CST3 protein was observed in the tissues of homozygous Cst3 knockout (Cst3-KO) gerbils. Interestingly, we found that disruption of the Cst3 gene led to more severe brain damage and neurological deficits after unilateral carotid artery ligation, thereby indicating that the gene modifications happened at both genetic and functional levels. In conclusion, we successfully generated a CRISPR/Cas9 system based genome editing platform for Mongolian gerbils, which provided a foundation for obtaining other genetically modified gerbil models for biomedical research.

Effect of the Fat Eaten at Breakfast on Lipid Metabolism: A Crossover Trial in Women with Cardiovascular Risk

Recent studies point out that not only the daily intake of energy and nutrients but the time of day when they are ingested notably regulates lipid metabolism and cardiovascular risk (CVR). Therefore, the aim of the study was to assess if the type of fat ingested at breakfast can modify lipid metabolism in women with CVR. A randomized, crossover clinical trial was performed. Sixty volunteers were randomly assigned to a (A) polyunsaturated fatty acid (PUFA)-rich breakfast, (B) saturated fatty acid (SFA)-rich breakfast, or (C) monounsaturated fatty acid (MUFA)-rich breakfast. Plasma lipoprotein and apolipoprotein subfractions were determined. Our data showed that the PUFA-rich breakfast decreased lipoprotein (a) (Lp(a)), very low-density lipoproteins (VLDL), and intermediate-density lipoproteins (IDL), and increased high-density lipoproteins (HDL). A similar trend was observed for the MUFA-rich breakfast, whereas the SFA-rich breakfast, although it decreased VLDL, also increased IDL and reduced HDL. The PUFA-rich breakfast also decreased β-lipoproteins and apolipoprotein-B. In summary, varying the type of fat eaten at breakfast is enough to significantly modify the lipid metabolism of women with CVR, which can be of great relevance to establish new therapeutic strategies for the treatment of these subjects.

Association between blood lipid level and embryo quality during in vitro fertilization

The aim of this study was to investigate the relationship between blood lipid level and the parameters of embryo morphology of in vitro fertilization (IVF).A total of 488 patients undergoing conventional IVF were divided into pregnant (n = 286) and nonpregnant (n = 202) groups. Levels of triglycerides (TG), total cholesterol (TC), high-density lipoproteins (HDL), low-density lipoprotein (LDL), lipoprotein (a), lipoprotein (b), and embryo outcomes were studied. Spearman correlation was performed to analyze the correlation between blood lipid levels and embryo quality in pregnant group.The normal fertilization rate and number of good quality embryos were higher than nonpregnant group (P < .05). TG, TC, and LDL levels were negatively correlated with number of normal fertilized oocytes, while TG, TC, and Lp(b) were negatively correlated with number of good quality embryos. TG level was negatively correlated with number of oocytes and cleavage embryos while HDL and Lp(a) were positively correlated with number of oocytes, normal fertilized oocytes and cleavage embryos (P < .05).TG, TC, LDL, and Lp(b) levels had negative correlation with embryo quality, while HDL and Lp(a) had positive correlation with the embryo quality. Our present findings showed blood lipid levels may provide certain reference for the prediction of IVF pregnancy outcome.

A More Oxidized Plasma Albumin Redox State and Lower Plasma HDL Particle Number Reflect Low-Protein Diet Ingestion in Adult Rats

BACKGROUND

Plasma albumin (ALB) redox state reflects protein nutritional status, but how it differs from other protein nutrition biomarkers remains to be fully elucidated.

OBJECTIVE

This study aimed to delineate the characteristics of plasma ALB redox state as a protein nutrition biomarker.

METHODS

Adult male Wistar rats were maintained on an AIN-93 M [14% casein, control (CT)] diet or an AIN-93 M-based 5% casein [low protein (LP)] diet ad libitum for 4 wk. Plasma samples were repeatedly obtained from the same rats at weeks 0-4, ALB redox state was determined by HPLC, and the concentrations of conventional protein nutrition biomarkers, ALB and transthyretin (TTR), were compared between the groups by Student t test. Body mass, relative muscle masses, plasma proteome, and plasma lipids at week 4 were also compared.

RESULTS

Plasma ALB redox state shifted to a more oxidized state in the LP diet group compared with the CT diet group at weeks 1-4. The LP diet group also showed significantly lower plasma ALB concentrations at weeks 1 and 2 (13% and 11% lower, respectively) and significantly lower TTR concentration at week 1 (21% lower) compared with the CT diet group, but these concentrations did not differ significantly at weeks 3 and 4. After 4 wk, body mass and relative soleus and gastrocnemius muscle masses did not differ, but the relative plantaris muscle mass tended to be 4% lower (1.75 compared with 1.68 g/kg body mass) in the LP diet group compared with the CT group (P = 0.06). The LP diet group also had a significantly lower HDL particle number than the CT group (30% lower).

CONCLUSIONS

A more oxidized plasma ALB redox state and lower plasma HDL particle number reflect LP diet ingestion in adult rats, which did not exhibit changes of plasma ALB and TTR concentrations.

Apolipoprotein serum levels related to metabolic syndrome in patients with schizophrenia

BACKGROUND

Schizophrenia is associated with a lowered life expectancy due to cardiovascular disease. This is, at least in part, related to an increased vulnerability to the development of metabolic syndrome (MetS) in patients with schizophrenia. The dysregulation of apolipoproteins (Apos) may also play a role in the pathogenesis of schizophrenia via their effect on cerebral cholesterol processing.

AIM

The aim of this study was to investigate serum Apos A1, C3, E, A2 and C2 concentration in schizophrenia patients with or without MetS in comparison to healthy donors.

METHODS

After obtaining informed consent, 53 patients with a diagnosis of paranoid schizophrenia according to ICD-10 criteria (F20) were included. Patients were divided into two groups with (N = 26) and without (N = 27) MetS according to the criteria of the International Diabetes Federation. The control group included 20 mentally and physically healthy subjects. Serum Apos A1, A2, C2, C3 and E were measured using xMAP technology (Luminex).

RESULTS

Serum ApoA1 was significantly decreased in patients with schizophrenia compared to healthy subjects (p = 0.002); ApoA2 was lower in patients without MetS in comparison to patients with MetS (p = 0.017) and the levels of ApoC3 and ApoC2 were increased in patients with schizophrenia with MetS in comparison with the control group and also with patients without MetS. No other significant differences were established concerning the other assayed apolipoproteins.

CONCLUSIONS

In line with literature data the results of our study suggest that while disturbances in ApoA1 level may play a role in the pathogenesis of schizophrenia, ApoA2, ApoC2, ApoC3 and ApoE may be primarily related to metabolic imbalance.

The important role of apolipoprotein A-II in ezetimibe driven reduction of high cholesterol diet-induced atherosclerosis

BACKGROUND AND AIMS

It has been well established that ezetimibe blocks cholesterol absorption to prevent the negative effects of a high-fat diet in atherosclerosis. However, the exact mechanism is unknown. Here we use a transgenic zebrafish, which expresses different fluorescent proteins on either endothelial cells or granulocytes and macrophages, to explore the specific mechanism of ezetimibe and its role in reducing atherosclerosis-related hypercholesteremia.

METHODS

Zebrafish larvae were exposed to a control diet, high cholesterol diet (HCD) or a HCD with ezetimibe treatment. Both the control diet and high cholesterol diet were mixed with red or green fluorophore labeled cholesteryl ester to trace lipid distribution. Isobaric tags were used for relative and absolute quantification to examine protein expression profiles of zebrafish larvae in the different treatment groups. To knock down Apo A-II and investigate the role of Apo A-II in the anti-atherosclerotic function of ezetimibe, we used morpholinos to target zebrafish Apoa2 mRNA. To confirm ezetimibe regulatory role on Apo A-II expression, siRNA against HNF4, PPARα, and SREBP1 were transfected into HepG2 cells.

RESULTS

The results show that ezetimibe increased the expression of Apo A-II but failed to reduce vascular lipid accumulation and macrophage recruitment induced by the HCD diet when Apo A-II was knocked down. Finally, we found that ezetimibe increased the expression of Apo A-II through HNF4 and PPARα transcriptional factors.

CONCLUSIONS

Our data indicates that ezetimibe may not only prevents atherosclerosis by inhibiting cholesterol absorption in the intestine, but also by increasing the expression of Apo A-II in hepatocytes, thereby enhancing reverse cholesterol transport and removing excess cholesterol from the periphery.

Plasmapheresis for Spur Cell Anemia in a Patient with Alcoholic Liver Cirrhosis

Background

Spur cell anemia (SCA) is a cause of hemolytic anemia in patients with alcoholic liver cirrhosis. Because dyslipidemia is related to the development of spur cells, SCA was previously treated with plasmapheresis.

Case Report

A 52-year-old Japanese man with SCA associated with alcoholic liver cirrhosis (Child-Pugh C) underwent two rounds of plasmapheresis. Clinical features and serum lipid concentrations were compared before and after plasmapheresis. Although indirect hyperbilirubinemia and SCA persisted after plasmapheresis, reticulocyte counts significantly decreased from 22.4% to 4.5%, and Hb levels improved without red cell transfusions. Analysis of lipids showed that total and free cholesterol, HDL cholesterol, phospholipid, and apo-AI concentrations, all of which were reduced before plasmapheresis, had improved after treatment, while LDL cholesterol, lipoprotein (a), and apo-AII concentrations, which were also reduced before plasmapheresis, remained unchanged.

Conclusions

Despite plasmapheresis partially ameliorating the degree of hemolysis, the persistence of SCA may have been linked with the lack of improvement in certain types of lipid metabolism.

Cholesterol signaling in single cells: lessons from STAR and sm-FISH

Cholesterol is an important regulator of cell signaling, both through direct impacts on cell membranes and through oxy-metabolites that activate specific receptors (steroids, hydroxy-cholesterols, bile acids). Cholesterol moves slowly through and between cell membranes with the assistance of specific binding proteins and transfer processes. The prototype cholesterol regulator is the Steroidogenesis Acute Regulatory (STAR), which moves cholesterol into mitochondria, where steroid synthesis is initiated by cytochrome P450 11A1 in multiple endocrine cell types. CYP27A1 generates hydroxyl cholesterol metabolites that activate LXR nuclear receptors to control cholesterol homeostatic and transport mechanisms. LXR regulation of cholesterol transport and storage as cholesterol ester droplets is shared by both steroid-producing cells and macrophage. This cholesterol signaling is crucial to brain neuron regulation by astrocytes and microglial macrophage, mediated by ApoE and sensitive to disruption by β-amyloid plaques. sm-FISH delivers appreciable insights into signaling in single cells, by resolving single RNA molecules as mRNA and by quantifying pre-mRNA at gene loci. sm-FISH has been applied to problems in physiology, embryo development and cancer biology, where single cell features have critical impacts. sm-FISH identifies novel features of STAR transcription in adrenal and testis cells, including asymmetric expression at individual gene loci, delayed splicing and 1:1 association of mRNA with mitochondria. This may represent a functional unit for the translation-dependent cholesterol transfer directed by STAR, which integrates into mitochondrial fusion dynamics. Similar cholesterol dynamics repeat with different players in the cycling of cholesterol between astrocytes and neurons in the brain, which may be abnormal in neurodegenerative diseases.

Apolipoprotein A-II induces acute-phase response associated AA amyloidosis in mice through conformational changes of plasma lipoprotein structure

During acute-phase response (APR), there is a dramatic increase in serum amyloid A (SAA) in plasma high density lipoproteins (HDL). Elevated SAA leads to reactive AA amyloidosis in animals and humans. Herein, we employed apolipoprotein A-II (ApoA-II) deficient (Apoa2 ^-/- ) and transgenic (Apoa2Tg) mice to investigate the potential roles of ApoA-II in lipoprotein particle formation and progression of AA amyloidosis during APR. AA amyloid deposition was suppressed in Apoa2 ^-/- mice compared with wild type (WT) mice. During APR, Apoa2 ^-/- mice exhibited significant suppression of serum SAA levels and hepatic Saa1 and Saa2 mRNA levels. Pathological investigation showed Apoa2 ^-/- mice had less tissue damage and less inflammatory cell infiltration during APR. Total lipoproteins were markedly decreased in Apoa2 ^-/- mice, while the ratio of HDL to low density lipoprotein (LDL) was also decreased. Both WT and Apoa2 ^-/- mice showed increases in LDL and very large HDL during APR. SAA was distributed more widely in lipoprotein particles ranging from chylomicrons to very small HDL in Apoa2 ^-/- mice. Our observations uncovered the critical roles of ApoA-II in inflammation, serum lipoprotein stability and AA amyloidosis morbidity, and prompt consideration of therapies for AA and other amyloidoses, whose precursor proteins are associated with circulating HDL particles.

Consumption of Amaranth Induces the Accumulation of the Antioxidant Protein Paraoxonase/Arylesterase 1 and Modulates Dipeptidyl Peptidase IV Activity in Plasma of Streptozotocin-Induced Hyperglycemic Rats

BACKGROUND/AIM

Amaranth is a source of several bioactive compounds, among which peptides with inhibitory activity upon dipeptidyl peptidase IV (DPP-IV) have been reported. However, there is no information about the action of amaranth DPP-IV-inhibitory peptides using in vivo models. The aim of this work was to evaluate the effect of amaranth consumption on plasma and kidney DPP-IV activity as well the changes in plasma proteome profile of streptozotocin (STZ)-induced hyperglycemic rats.

METHODS

Rats were fed for 12 weeks with a diet containing 20% popped amaranth grain. Kidneys and blood samples were collected for lipid profile, DPP-IV activity and expression, and proteomic analysis.

RESULTS

Total cholesterol and DPP-IV activity in plasma was increased in hyperglycemic rats, but this effect was reverted by amaranth consumption. Triacylglycerols were increased in the hyperglycemic group fed amaranth, and the highest levels of high-density lipoproteins were also observed in this group. These data correlated with the accumulation of apolipoprotein A-II in plasma. Accumulation of the antioxidant protein paraoxonase/arylesterase 1 in STZ-induced hyperglycemic rats was observed when amaranth was supplied in the diet.

CONCLUSION

This study provides new insights into the molecular mechanisms by which amaranth exerts its beneficial health action in a hyperglycemic state.

Transcriptional and post-translational changes in the brain of mice deficient in cholesterol removal mediated by cytochrome P450 46A1 (CYP46A1)

Cytochrome P450 46A1 (CYP46A1) converts cholesterol to 24-hydroxycholesterol and thereby controls the major pathways of cholesterol removal from the brain. Cyp46a1-/- mice have a reduction in the rate of cholesterol biosynthesis in the brain and significant impairments to memory and learning. To gain insights into the mechanisms underlying Cyp46a1-/- phenotype, we used Cyp46a1-/- mice and quantified their brain sterol levels and the expression of the genes pertinent to cholesterol homeostasis. We also compared the Cyp46a1-/- and wild type brains for protein phosphorylation and ubiquitination. The data obtained enable the following inferences. First, there seems to be a compensatory upregulation in the Cyp46a1-/- brain of the pathways of cholesterol storage and CYP46A1-independent removal. Second, transcriptional regulation of the brain cholesterol biosynthesis via sterol regulatory element binding transcription factors is not significantly activated in the Cyp46a1-/- brain to explain a compensatory decrease in cholesterol biosynthesis. Third, some of the liver X receptor target genes (Abca1) are paradoxically upregulated in the Cyp46a1-/- brain, possibly due to a reduced activation of the small GTPases RAB8, CDC42, and RAC as a result of a reduced phosphorylation of RAB3IP and PAK1. Fourth, the phosphorylation of many other proteins (a total of 146) is altered in the Cyp46a1-/- brain, including microtubule associated and neurofilament proteins (the MAP and NEF families) along with proteins related to synaptic vesicles and synaptic neurotransmission (e.g., SLCs, SHANKs, and BSN). Fifth, the extent of protein ubiquitination is increased in the Cyp46a1-/- brain, and the affected proteins pertain to ubiquitination (UBE2N), cognition (STX1B and ATP1A2), cytoskeleton function (TUBA1A and YWHAZ), and energy production (ATP1A2 and ALDOA). The present study demonstrates the diverse potential effects of CYP46A1 deficiency on brain functions and identifies important proteins that could be affected by this deficiency.

Dysfunctional high-density lipoproteins have distinct composition, diminished anti-inflammatory potential and discriminate acute coronary syndrome from stable coronary artery disease patients

There is a stringent need to find means for risk stratification of coronary artery diseases (CAD) patients. We aimed at identifying alterations of plasma high-density lipoproteins (HDL) components and their validation as dysfunctional HDL that could discriminate between acute coronary syndrome (ACS) and stable angina (SA) patients. HDL₂ and HDL₃ were isolated from CAD patients’ plasma and healthy subjects. ApolipoproteinAI (apoAI), apoAII, apoCIII, malondialdehyde (MDA), myeloperoxidase (MPO), ceruloplasmin and paraoxonase1 (PON1) were assessed. The anti-inflammatory potential of HDL subfractions was tested by evaluating the secreted inflammatory molecules of tumor necrosis factor α-activated endothelial cells (EC) upon co-incubation with HDL₂ or HDL_3. We found in ACS versus SA patients: 40% increased MPO, MDA, apoCIII in HDL₂ and HDL₃, 35% augmented apoAII in HDL₂, and in HDL₃ increased ceruloplasmin, decreased apoAII (40%) and PON1 protein and activity (15% and 25%). Co-incubation of activated EC with HDL₂ or HDL₃ from CAD patients induced significantly increased levels of secreted inflammatory molecules, 15–20% more for ACS versus SA. In conclusion, the assessed panel of markers correlates with the reduced anti-inflammatory potential of HDL subfractions isolated from ACS and SA patients (mostly for HDL₃ from ACS) and can discriminate between these two groups of CAD patients.

The effect of weight loss on HDL subfractions and LCAT activity in two genotypes of APOA-II -265T>C polymorphism

Background

People may have different responses to the same environmental changes. It has been reported that genome variations may be responsible for these differences. Also, HDL subfractions may be influenced by different genetic variations. The aim of the present study was to determine gene-diet interactions and to evaluate the influence of weight loss on HDL subfractions between two genotypes of -265 T>C APOA-II polymorphism.

Methods

In the present study, 56 overweight and obese patients with type 2 diabetes mellitus were selected from 697 genotype-specified subjects. After matching for gender, age and BMI at the beginning of the study, an equal number of patients remained on each genotype of APOA-II (TT/TC and CC group). After a 6-week calorie restriction program, 44 patients completed the study. Serum HDL subfractions, including HDL2 and HDL3 and LCAT activity, were compared between the two genotypes and, before and after the intervention, were separated in each genotype.

Results

Serum concentration of HDL and its subfractions decreased significantly due to the weight loss. A comparison of the mean changes between the genotypes showed that HDL3 significantly decreased in the CC genotype while, in the TT/TC group, the serum concentration of HDL2 was significantly reduced. However, the increase of LCAT activity was not significant among the two genotypes.

Conclusion

A comparison of mean changes of variables within two genotype groups showed that C homozygote carriers lead to a general shift toward larger size HDL subfractions and T allele carriers shift toward smaller size HDL subfractions after weight loss.

Effects of gender, age and menopausal status on serum apolipoprotein concentrations

OBJECTIVE

To undertake a comprehensive evaluation of apolipoprotein risk markers for cardiovascular disease (CVD) according to gender, age and menopausal status.

DESIGN

Cross-sectional analysis of independent associations of gender, age and menopause with serum apolipoproteins.

PARTICIPANTS

Apparently healthy Caucasian premenopausal (n = 109) and postmenopausal (n = 252) women not taking oral contraceptives or hormone replacement, and Caucasian men (n = 307).

MEASUREMENTS

Serum apolipoprotein (apo) B, A-I and A-II concentrations were measured, plus serum total cholesterol, low-density and high-density lipoprotein cholesterol (LDL-C and HDL-C, respectively), triglycerides, cholesterol in HDL subfractions and the apoB/apoA-I, LDL-C/apoB, HDL-C/apoA-I and HDL-C/apoA-II ratios. Analyses were undertaken with and without standardization for confounding characteristics and in 5-year age ranges.

RESULTS

Overall, apoB concentrations were highest in men but in women rose with age and menopause to converge, in the age range of 50-55 years, with concentrations in men. The LDL-C/apoB ratio was generally higher in women than in men. ApoA-I concentrations were highest in postmenopausal women and lowest in men (standardized median (IQR) 144 (130, 158) vs 119 (108, 132) g/l, respectively, P < 0·001). ApoA-II concentrations were also highest in postmenopausal women but were lowest in premenopausal women (40·3 (37·5, 44·5) vs 32·9 (30·5, 35·7) g/l, respectively, P < 0·001). Nevertheless, postmenopausal women had HDL-C/apoA-I and HDL-C/apoA-II ratios approaching the lowest ratios, which were seen in men.

CONCLUSIONS

Consistent with adverse effects on CVD risk, male gender, ageing in women and menopause were associated with increased apoB concentrations, and menopause and male gender were associated with a decreased cholesterol content of HDL particles.

Triglyceride increase in the core of high-density lipoproteins augments apolipoprotein dissociation from the surface: Potential implications for treatment of apolipoprotein deposition diseases

Lipids in the body are transported via lipoproteins that are nanoparticles comprised of lipids and amphipathic proteins termed apolipoproteins. This family of lipid surface-binding proteins is over-represented in human amyloid diseases. In particular, all major proteins of high-density lipoproteins (HDL), including apoA-I, apoA-II and serum amyloid A, can cause systemic amyloidoses in humans upon protein mutations, post-translational modifications or overproduction. Here, we begin to explore how the HDL lipid composition influences amyloid deposition by apoA-I and related proteins. First, we summarize the evidence that, in contrast to lipoproteins that are stabilized by kinetic barriers, free apolipoproteins are labile to misfolding and proteolysis. Next, we report original biochemical and biophysical studies showing that increase in triglyceride content in the core of plasma or reconstituted HDL destabilizes the lipoprotein assembly, making it more labile to various perturbations (oxidation, thermal and chemical denaturation and enzymatic hydrolysis), and promotes apoA-I release in a lipid-poor/free aggregation-prone form. Together, the results suggest that decreasing plasma levels of triglycerides will shift the dynamic equilibrium from the lipid-poor/free (labile) to the HDL-bound (protected) apolipoprotein state, thereby decreasing the generation of the protein precursor of amyloid. This prompts us to propose that triglyceride-lowering therapies may provide a promising strategy to alleviate amyloid diseases caused by the deposition of HDL proteins.

ApoA-II HDL Catabolism and Its Relationships With the Kinetics of ApoA-I HDL and of VLDL1, in Abdominal Obesity

We study the associations between apoA-II fractional catabolic rate (FCR) and the kinetics of VLDL subspecies and apoA-I and show that, in abdominally obese individuals, apoA-II FCR is positively and independently associated with both apoA-I FCR and VLDL1-TG indirect FCR.

Proteomic Changes in Chicken Plasma Induced by Salmonella typhimurium Lipopolysaccharides

Lipopolysaccharides (LPS) are cell wall components of Gram-negative bacteria that produce inflammation and sickness in higher animals. The objective was to identify plasma proteomic changes in an avian model of inflammation. Chickens were treated with either saline or LPS, and blood was collected at 24 hours postinjection. The pooled plasma samples were depleted of high-abundant proteins and analyzed by matrix-assisted laser desorption ionization (MALDI)-time-of-flight mass spectrometry and liquid chromatography–tandem mass spectrometry (LC–MS/MS). MALDI analyses showed an increase in fibrinogen beta-derived peptide and a decrease in apolipoprotein-AII-derived peptide in LPS samples. Label-free quantitation of LC–MS/MS spectra revealed an increase in the levels of α1-acid glycoprotein, a chemokine CCLI10, and cathelicidin-2, but a decrease in an interferon-stimulated gene-12-2 protein in the LPS group. These differentially expressed proteins are associated with immunomodulation, cytokine changes, and defense mechanisms, which may be useful as candidate biomarkers of infection and inflammation.

HDL functionality in reverse cholesterol transport--Challenges in translating data emerging from mouse models to human disease

Whereas LDL-derived cholesterol accumulates in atherosclerotic lesions, HDL particles are thought to facilitate removal of cholesterol from the lesions back to the liver thereby promoting its fecal excretion from the body. Because generation of cholesterol-loaded macrophages is inherent to atherogenesis, studies on the mechanisms stimulating the release of cholesterol from these cells and its ultimate excretion into feces are crucial to learn how to prevent lesion development or even induce lesion regression. Modulation of this key anti-atherogenic pathway, known as the macrophage-specific reverse cholesterol transport, has been extensively studied in several mouse models with the ultimate aim of applying the emerging knowledge to humans. The present review provides a detailed comparison and critical analysis of the various steps of reverse cholesterol transport in mouse and man. We attempt to translate this in vivo complex scenario into practical concepts, which could serve as valuable tools when developing novel HDL-targeted therapies.

APOA II genotypes frequency and their interaction with saturated fatty acids consumption on lipid profile of patients with type 2 diabetes

BACKGROUND & AIM

Several studies have suggested that APOA II-265T/C polymorphism affect lipid profile. The aim of this study was to investigate the effect of -265T/C APOA II polymorphism and saturated fatty acids (SFA) intake interaction on lipid profile in diabetic population who are at risk for lipid disorders.

METHODS

In this cross sectional study, 697 type 2 diabetic patients participated. Food consumption data were collected using validated semi-quantitative FFQ during the last year. Realtime-PCR was used to determine APOA II-265T/C genotypes. The interaction between the genotypes and SFA intake with lipid profile was tested using analysis of covariance (ANCOVA).

RESULTS

According to APOA II-265T/C (rs5082) genotype distribution results, CC genotype with a frequency of 12.9% and TC with that of 47.7% showed the lowest and highest frequency in our population, respectively. CC genotype subjects had significantly lower total cholesterol, triglyceride, Cholesterol/HDL-c ratio and non-HDL cholesterol than T allele carriers (p = 0.009, p = 0.02, p = 0.02 and p = 0.002, respectively). The interaction between genotype and SFA intake contributed to significant higher levels of LDL-c and LDL/HDL in CCs (p = 0.05 and p = 0.01), suggesting vulnerability of these individuals to high intake of SFA in the diet.

CONCLUSION

APOA II polymorphism may influence the saturated fatty acid intake required to prevent dyslipidemia in the type 2 diabetic population.

Impact of Virgin Olive Oil and Phenol-Enriched Virgin Olive Oils on the HDL Proteome in Hypercholesterolemic Subjects: A Double Blind, Randomized, Controlled, Cross-Over Clinical Trial (VOHF Study)

The effects of olive oil phenolic compounds (PCs) on HDL proteome, with respect to new aspects of cardioprotective properties, are still unknown. The aim of this study was to assess the impact on the HDL protein cargo of the intake of virgin olive oil (VOO) and two functional VOOs, enriched with their own PCs (FVOO) or complemented with thyme PCs (FVOOT), in hypercholesterolemic subjects. Eligible volunteers were recruited from the IMIM-Hospital del Mar Medical Research Institute (Spain) from April 2012 to September 2012. Thirty-three hypercholesterolemic participants (total cholesterol >200mg/dL; 19 men and 14 women; aged 35 to 80 years) were randomized in the double-blind, controlled, cross-over VOHF clinical trial. The subjects received for 3 weeks 25 mL/day of: VOO, FVOO, or FVOOT. Using a quantitative proteomics approach, 127 HDL-associated proteins were identified. Among these, 15 were commonly differently expressed after the three VOO interventions compared to baseline, with specific changes observed for each intervention. The 15 common proteins were mainly involved in the following pathways: LXR/RXR activation, acute phase response, and atherosclerosis. The three VOOs were well tolerated by all participants. Consumption of VOO, or phenol-enriched VOOs, has an impact on the HDL proteome in a cardioprotective mode by up-regulating proteins related to cholesterol homeostasis, protection against oxidation and blood coagulation while down-regulating proteins implicated in acute-phase response, lipid transport, and immune response. The common observed protein expression modifications after the three VOOs indicate a major matrix effect.

An experimental study on amelioration of dyslipidemia-induced atherosclesis by Clematichinenoside through regulating Peroxisome proliferator-activated receptor-α mediated apolipoprotein A-I, A-II and C-III

Prevention or amelioration the prevalence of atherosclerosis has been an effective strategy in the management of cardiovascular diseases. The aim of the study was to scrutinize the effect of Clematichinenoside (AR) on dyslipidemia-induced atherosclerosis and explore its capability on expression of Peroxisome proliferator-activated receptor-α (PPAR-alpha), apolipoprotein A-I (APOA1) and A-II (APOA2), and suppression of apolipoprotein C-III (APOC3) genes and proteins. In the present study, we investigated atherosclerosis effect of AR using a combination of high-fat diet and balloon injury model in rabbits. The levels of biochemical indicators were evaluated in plasma, liver and HepG2 cells using immunoassay technology. In order to expose the underlying mechanism, we evaluated the regulation of PPAR-alpha, APOA1, APOA2 and APOC3 expressions by AR, and we further evaluated the interactions between them after transfection with shRNA (shPPAR-alpha) and, the action of PPAR-alpha in HepG2 cells. We could find that AR markedly promoted the PPAR-alpha transfer from cytoplasm to nucleus which resulted in the alteration of APOA1, APOA2 and APOC3 expressions in HepG2 cells. Moreover, AR significantly reduced total cholesterol, triglycerides and low-density lipoprotein cholesterol (LDL-C) levels, and elevated high-density lipoprotein cholesterol (HDL-C) level, which play an important role in dyslipidemia-induced atherosclerosis. In conclusion, AR ameliorated atherosclerosis via the regulation of hepatic lipid metabolism, and AR also contributed to the activation of PPAR-alpha, APOA1, APOA2 and APOC3. Therefore, AR could be a potential therapeutic agent in the treatment of atherosclerosis.

Amyloid-Forming Properties of Human Apolipoproteins: Sequence Analyses and Structural Insights

Apolipoproteins are protein constituents of lipoproteins that transport cholesterol and fat in circulation and are central to cardiovascular health and disease. Soluble apolipoproteins can transiently dissociate from the lipoprotein surface in a labile free form that can misfold, potentially leading to amyloid disease. Misfolding of apoA-I, apoA-II, and serum amyloid A (SAA) causes systemic amyloidoses, apoE4 is a critical risk factor in Alzheimer's disease, and apolipoprotein misfolding is also implicated in cardiovascular disease. To explain why apolipoproteins are over-represented in amyloidoses, it was proposed that the amphipathic α-helices, which form the lipid surface-binding motif in this protein family, have high amyloid-forming propensity. Here, we use 12 sequence-based bioinformatics approaches to assess amyloid-forming potential of human apolipoproteins and to identify segments that are likely to initiate β-aggregation. Mapping such segments on the available atomic structures of apolipoproteins helps explain why some of them readily form amyloid while others do not. Our analysis shows that nearly all amyloidogenic segments: (i) are largely hydrophobic, (ii) are located in the lipid-binding amphipathic α-helices in the native structures of soluble apolipoproteins, (iii) are predicted in both native α-helices and β-sheets in the insoluble apoB, and (iv) are predicted to form parallel in-register β-sheet in amyloid. Most of these predictions have been verified experimentally for apoC-II, apoA-I, apoA-II and SAA. Surprisingly, the rank order of the amino acid sequence propensity to form amyloid (apoB>apoA-II>apoC-II≥apoA-I, apoC-III, SAA, apoC-I>apoA-IV, apoA-V, apoE) does not correlate with the proteins' involvement in amyloidosis. Rather, it correlates directly with the strength of the protein-lipid association, which increases with increasing protein hydrophobicity. Therefore, the lipid surface-binding function and the amyloid-forming propensity are both rooted in apolipoproteins' hydrophobicity, suggesting that functional constraints make it difficult to completely eliminate pathogenic apolipoprotein misfolding. We propose that apolipoproteins have evolved protective mechanisms against misfolding, such as the sequestration of the amyloidogenic segments via the native protein-lipid and protein-protein interactions involving amphipathic α-helices and, in case of apoB, β-sheets.

Hot spots in apolipoprotein A-II misfolding and amyloidosis in mice and men

ApoA-II is the second-major protein of high-density lipoproteins. C-terminal extension in human apoA-II or point substitutions in murine apoA-II cause amyloidosis. The molecular mechanism of apolipoprotein misfolding, from the native predominantly α-helical conformation to cross-β-sheet in amyloid, is unknown. We used 12 sequence-based prediction algorithms to identify two ten-residue segments in apoA-II that probably initiate β-aggregation. Previous studies of apoA-II fragments experimentally verify this prediction. Together, experimental and bioinformatics studies explain why the C-terminal extension in human apoA-II causes amyloidosis and why, unlike murine apoA-II, human apoA-II normally does not cause amyloidosis despite its unusually high sequence propensity for β-aggregation.