ABSTRACT: Top-down quantitative analysis of Apolipoprotein A1 from two sets of participants reveals differential proteoform expression in high or low HDL efflux capacity groups.
Project description:Specific mutations in Apolipoprotein A-I (ApoA-I) of high-density lipoprotein (HDL) are responsible for a late-onset systemic amyloidosis. Carriers do not exhibit increased cardiovascular disease risk despite reduced levels of ApoA-I/ HDL-cholesterol. To explain this paradox, we show that the HDL particle profile of L75P and L174S patients presents a higher relative abundance of the 8.4 nm vs 9.6 nm particles, and that serum from patients, as well as reconstituted 8.4 and 9.6 nm HDL particles (rHDL), possess increased capacity to catalyze cholesterol efflux from macrophages. Synchrotron radiation circular dichroism and hydrogen-deuterium exchange revealed that the variants in 8.4 nm rHDL have altered secondary structure composition and display a more flexible binding to lipids compared to their native counterpart. The reduced HDL-cholesterol levels of patients carrying ApoA-I amyloidogenic variants are thus balanced by higher proportion of small, dense HDL particles and better cholesterol efflux due to altered, region-specific protein structure dynamics.
Project description:Background: High-density lipoprotein (HDL)-cholesterol is inversely correlated with cardiovascular risk, but increasing its circulating concentration is insufficient to prevent adverse cardiovascular outcomes. Instead, the emerging paradigm is on increasing the function of HDL and its major protein constituent, apolipoprotein A-I (apoA-I) to increase reverse cholesterol transport. Objective: To investigate the effect of apoA-I [human] (CSL112) infusion on HDL protein composition, and provide further insights into the mechanism of action of CSL112 administered post-acute myocardial infarction (AMI). Methods: A mass spectrometry (MS)-based proteomic approach was used to evaluate changes in HDL protein composition in patients (n=50) from the AEGIS-I (ApoA-I Event Reducing in Ischemic Syndromes I) study who received either placebo or CSL112 post-AMI. HDL was immuno-isolated from patient plasma using anti-apoA-I antibodies. Cholesterol esterification rate (CER) was measured to determine lecithin-cholesterol acyl transferase (LCAT) activity. Cholesterol efflux capacity (CEC) and hepatocyte uptake were assessed using patient serum in ex vivo cell-based assays. Results: CSL112 induced extensive rearrangement of HDL proteins at 4 hours post-infusion. Levels of apolipoproteins A2, B, C, and E, as well as the acute phase proteins serum amyloid A1 and A4 were significantly reduced. By contrast, apoA-I, apoM, and LCAT significantly increased. Elevated apoA-I and LCAT levels on HDL were associated with an increase in CEC, plasma HDL-C levels, and CER in CSL112-treated patients. Furthermore, enhanced CEC was strongly associated with cholesterol uptake by hepatic cells (r=0.95 p<0.001). Conclusions: CSL112 altered HDL composition and increased HDL functionality by promoting multiple steps of the reverse cholesterol transport pathway. Clinical trial registration: URL: https://clinicaltrials.gov. Unique identifier: NCT02108262
Project description:Apolipoprotein (Apo) E4 is a key genetic risk factor for Alzheimer’s disease (AD). In the central nervous system, ApoE-containing high-density lipoprotein (HDL)-like particles transport glial cholesterol to neurons, playing a crucial role in neuronal membrane remodeling and maintenance of the myelin sheath. Despite this, the impact of HDL-like cholesterol trafficking on AD pathogenesis is not yet fully understood.The objective was to examine cholesterol transport via HDL-like particles in cerebrospinal fluid (CSF) of AD patients compared to control individuals. Additionally, we explored the ability of ApoE4-containing HDL to regulate the cholesterol efflux pathway in astrocytoma cells and facilitate cholesterol delivery to neurons.Mass spectrometry (MS) was used for a detailed analysis of the HDL-like proteome in AD patients and controls.
Project description:Hyperinsulinaemic androgen excess (HIAE) in prepubertal and pubertal girls usually precedes a broader pathological phenotype in adulthood that is associated with anovulatory infertility, metabolic syndrome and type 2 diabetes. The metabolic derangements that determine these long-term health risks remain to be clarified. Here we use NMR and MS-based metabolomics to show that serum levels of methionine sulfoxide in HIAE girls are an indicator of the degree of oxidation of methionine-148 residue in apolipoprotein-A1. Oxidation of apo-A1 in methionine-148, in turn, leads to an impaired maturation of high-density lipoproteins (HDL) that is reflected in a decline of large HDL particles. Notably, such metabolic alterations occur in the absence of impaired glucose tolerance, hyperglycemia and hypertriglyceridemia, and were partially restored after 18 months of treatment with a low-dose combination of pioglitazone, metformin and flutamide.
Project description:Seven health subjects took fish oil supplements (1.125 mg DHA and 875 mg EPA) for 30 days.Prior to supplementation, at 30 day of supplementation and after a 30 day washout period patient plasma was collected. From subject plasma HDL was isolated using a two step ultracentrifugation procced. The isolated HDL was then used in cholesterol efflux assay, anti-inflammatory capacity assay, proteomics and lipidomics.
Project description:We quantified differential microRNA (miRNA) expression in human coronary artery cells treated with native HDL, reconstituted HDL, lipid-free apolipoprotein A-I, small unilamellar vesicles, or PBS control. These data were used to determine whichmiRNAs are regulated by native HDL compared to components of HDL and categorize data based on shared sets of miRNAs and distinct sets of miRNAs regulated by each component. Each group had a n=5 and gene expression changes for each condition were compared to control PBS-treat HCAECs
Project description:We quantified differential microRNA (miRNA) expression in human coronary artery cells treated with native HDL, reconstituted HDL, lipid-free apolipoprotein A-I, small unilamellar vesicles, or PBS control. These data were used to determine whichmiRNAs are regulated by native HDL compared to components of HDL and categorize data based on shared sets of miRNAs and distinct sets of miRNAs regulated by each component.
Project description:We quantified differential gene (mRNA) expression in human coronary artery cells treated with native HDL, reconstituted HDL, lipid-free apolipoprotein A-I, small unilamellar vesicles, or PBS control. These data were used to determine which genes are regulated by native HDL compared to components of HDL and categorize data based on shared sets of genes and distinct sets of genes regulated by each component. Each group had a n=5 and gene expression changes for each condition were compared to control PBS-treated HCAECs
Project description:We quantified differential gene (mRNA) expression in human coronary artery cells treated with native HDL, reconstituted HDL, lipid-free apolipoprotein A-I, small unilamellar vesicles, or PBS control. These data were used to determine which genes are regulated by native HDL compared to components of HDL and categorize data based on shared sets of genes and distinct sets of genes regulated by each component.
Project description:Background: High density lipoprotein (HDL) protects the artery wall by removing cholesterol from lipid-laden macrophages. However, recent evidence suggests that it might also inhibit atherogenesis by combating inflammation. Methods and Results: To identify potential anti-inflammatory mechanisms, we challenged macrophages with lipopolysaccharide (LPS), an inflammatory microbial ligand for Toll-like receptor 4 (TLR4). HDL inhibited the expression of 33% (301 of 911) of the genes normally induced by LPS, microarray analysis revealed. One of its major targets was the type I interferon response pathway, a family of potent viral immunoregulators controlled by TLR4 and the TRAM/TRIF signaling pathway. Unexpectedly, HDL’s ability to inhibit gene expression was independent of cellular cholesterol stores. Moreover, it was unaffected by downregulation of two ATP-binding cassette transporters, ABCA1 and ABCG1, that promote cholesterol efflux. To examine the pathway’s potential in vivo relevance, we used mice deficient in apolipoprotein (apo) A-I, HDL’s major protein. After infection with Salmonella (a Gram-negative bacterium that expresses LPS), apoA-I–deficient mice had 6-fold higher plasma levels of interferon-beta-a key regulator of the type I interferon response than did wild-type mice. Conclusions: HDL inhibits a subset of LPS-stimulated macrophage genes that regulate the type I interferon response, and its action is independent of sterol metabolism. These findings raise the possibility that regulation of macrophage genes by HDL might link innate immunity and cardioprotection. 12 arrays, 3 experimental groups, mMncN (no treatment), mMncL (LPS treated, exposed for 4 h to serum-free medium or serum-free medium supplemented with 100 ng/mL of LPS), and mMwtL (HDL treated, Macrophages were treated for 4 h with serum-free medium or serum-free medium supplemented with 50 mg/mL of HDL, washed twice with PBS).