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Background: Apoprotein A-I (ApoA-I) and Apoprotein B (ApoB) have emerged as novel cardiovascular risk biomarkers influenced by feeding behavior. Hypothalamic appetite peptides regulate feeding behavior and impact lipoprotein levels, which effects vary in different weight states. This study explores the intricate relationship between body mass index (BMI), hypothalamic appetite peptides, and apolipoproteins with emphasis on the moderating role of body weight in the association between neuropeptide Y (NPY), ghrelin, orexin A (OXA), oxytocin in cerebrospinal fluid (CSF) and peripheral ApoA-I and ApoB. Methods: In this cross-sectional study, we included participants with a mean age of 31.77 ± 10.25 years, categorized into a normal weight (NW) (n = 73) and an overweight/obese (OW/OB) (n = 117) group based on BMI. NPY, ghrelin, OXA, and oxytocin levels in CSF were measured. Results: In the NW group, peripheral ApoA-I levels were higher, while ApoB levels were lower than in the OW/OB group (all p < 0.05). CSF NPY exhibited a positive correlation with peripheral ApoA-I in the NW group (r = 0.39, p = 0.001). Notably, participants with higher CSF NPY levels had higher peripheral ApoA-I levels in the NW group and lower peripheral ApoA-I levels in the OW/OB group, showing the significant moderating effect of BMI on this association (R2 = 0.144, β=-0.54, p < 0.001). The correlation between ghrelin, OXA and oxytocin in CSF and peripheral ApoB in both groups exhibited opposing trends (Ghrelin: r = -0.03 and r = 0.04; OXA: r = 0.23 and r=-0.01; Oxytocin: r=-0.09 and r = 0.04). Conclusion: This study provides hitherto undocumented evidence that BMI moderates the relationship between CSF NPY and peripheral ApoA-I levels. It also reveals the protective role of NPY in the NW population, contrasting with its risk factor role in the OW/OB population, which was associated with the at-risk for cardiovascular disease. [ABSTRACT FROM AUTHOR]

Background and purpose: Ischemic stroke (IS) is classified into clinical subtypes and likely influenced by various lipid components. Nevertheless, the roles of apolipoprotein A-I (apoA-I), apolipoprotein B (apoB), and apoB/apoA-I ratio in different IS subtypes remain underexplored. This study aimed to investigate the differential distribution of plasma apoA-I and apoB levels among IS subtypes and to evaluate the predictive value of the apoB/apoA-I ratio in assessing IS subtypes and disease severity. Methods: In this study, 406 IS patients were categorized into three IS-subtypes based on clinical manifestations and imaging assessment, including intracranial atherosclerosis-related IS patients (ICAS, n = 193), extracranial atherosclerosisrelated IS patients (ECAS, n = 111), and small artery occlusion-related IS patients (SAO, n = 102). Plasma apoA-I and apoB levels were measured upon hospital admission. Random forest (RF) models were performed to assess predictive values of these apolipoproteins apoB, apoA-I and their ratio in assessing IS subtype stratification and disease severity. Results: Serum apoA-I levels were significantly lower in ICAS compared to ECAS and SAO patients (p < 0.0001), while apoB levels were higher in ICAS patients (p < 0.0001). The apoB/apoA-I ratio was significantly higher in ICAS compared to ECAS and SAO patients (p < 0.0001). Correlation analyses found a significant correlation between the apoB/apoA-I ratio and conventional lipid components. Additionally, RF models and plots of variable importance and distribution of minimal depth revealed that the apoB/apoA-I ratio played the most influential predictor in predicting IS subtypes and stenosis severity. Conclusion: Our study shows the differential distribution of apoA-I and apoB IS subtypes and reveals the significance of the apoB/apoA-I ratio in assessing IS subtypes and arterial stenosis severity. Further studies are warranted to validate these findings and enhance their clinical applicability. [ABSTRACT FROM AUTHOR]

Background: Abnormal lipid levels have been associated with cancer incidence and progression. However, limited studies have investigated the relationship between apolipoprotein A-I (ApoA-I) and colorectal cancer (CRC). This study assessed the significance of ApoA-I levels in progression-free survival (PFS) and overall survival (OS) of patients with CRC. Methods: Survival curves were compared using Kaplan-Meier analysis, while the predictive values of various lipid indicators in CRC prognosis were evaluated based on receiver operating characteristic curves. The factors influencing PFS and OS in patients with CRC were analyzed using Cox proportional hazards regression models. Finally, the relationship between ApoA-I level and disease recurrence was investigated through logistic regression analysis. The optimal Apo-I level was determined through maximally selected rank statistics. Results: Using the optimal ApoA-I cutoff value (0.9 g/L), the 1,270 patients with CRCwere categorized into low (< 0.9 g/L, 275 cases) and high (=0.9 g/L, 995 cases) ApoA-I groups. Compared with other lipid indicators, ApoA-I demonstrated superior predictive accuracy. The high ApoA-I group exhibited significantly higher survival rates than the low ApoA-I group (PFS, 64.8% vs. 45.2%, P < 0.001; OS, 66.1% vs. 48.6%, P < 0.001). Each one-standard-deviation increase in ApoA-I level was related to a 12.0% decrease in PFS risk (hazard ratio [HR] 0.880; 95% confidence interval [CI], 0.801-0.968; P = 0.009) and an 11.2% decrease in OS risk (HR 0.888; 95%CI, 0.806-0.978; P = 0.015). Logistic regression analysis revealed that patients with low ApoA-I had a 32.5% increased risk of disease recurrence (odds ratio [OR] 0.675; 95%CI, 0.481-0.946; P = 0.0225) compared with those with high ApoA-I. PFS/OS nomograms based on ApoA-I demonstrated excellent prognostic prediction accuracy. Conclusions: Serum ApoA-I level may be a valuable and non-invasive tool for predicting PFS and OS in patients with CRC. [ABSTRACT FROM AUTHOR]

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The AEGIS-II trial hypothesized that CSL112, an intravenous formulation of human apoA-I, would lower the risk of plaque disruption, decreasing the risk of recurrent events such as myocardial infarction (MI) among high-risk patients with MI. This exploratory analysis evaluates the effect of CSL112 therapy on the incidence of cardiovascular (CV) death and recurrent MI. The AEGIS-II trial was an international, multicenter, randomized, double-blind, placebo-controlled trial that randomized 18,219 high-risk acute MI patients to 4 weekly infusions of apoA-I (6 g CSL112) or placebo. The incidence of the composite of CV death and type 1 MI was 11% to 16% lower in the CSL112 group over the study period (HR: 0.84; 95% CI: 0.7-1.0; P = 0.056 at day 90; HR: 0.86; 95% CI: 0.74-0.99; P = 0.048 at day 180; and HR: 0.89; 95% CI: 0.79-1.01; P = 0.07 at day 365). Similarly, the incidence of CV death or any MI was numerically lower in CSL112-treated patients throughout the follow-up period (HR: 0.92; 95% CI: 0.80-1.05 at day 90, HR: 0.89; 95% CI: 0.79-0.996 at day 180, HR: 0.91; 95% CI: 0.83-1.01 at day 365). The effect of CSL112 treatment on MI was predominantly observed for type 1 MI and type 4b (MI due to stent thrombosis). Although CSL112 did not significantly reduce the occurrence of the primary study endpoints, patients treated with CSL112 infusions had numerically lower rates of CV death and MI, type-1 MI, and stent thrombosis–related MI compared with placebo. These findings could suggest a role of apoA-I in reducing subsequent plaque disruption events via enhanced cholesterol efflux. Further prospective data would be needed to confirm these observations. [Display omitted] [ABSTRACT FROM AUTHOR]

Despite extensive use of intravitreal anti-vascular endothelial growth factor (anti-VEGF) biologics for over a decade, neovascular age-related macular degeneration (nAMD) or choroidal neovascularization (CNV) continues to be a major cause of irreversible vision loss in developed countries. Many nAMD patients demonstrate persistent disease activity or experience declining responses over time despite anti-VEGF treatment. The underlying mechanisms of anti-VEGF resistance are poorly understood, and no effective treatment strategies are available to date. Here we review evidence from animal models and clinical studies that supports the roles of neovascular remodeling and arteriolar CNV formation in anti-VEGF resistance. Cholesterol dysregulation, inflammation, and ensuing macrophage activation are critically involved in arteriolar CNV formation and anti-VEGF resistance. Combination therapy by neutralizing VEGF and enhancing cholesterol removal from macrophages is a promising strategy to combat anti-VEGF resistance in CNV. [ABSTRACT FROM AUTHOR]

In this study, we advance our exploration of Apolipoprotein A-I (apoA-I) peptide analogs (APAs) for their application in nanodisc (ND) assembly, focusing on the dynamic conformational characteristics and the potential for drug delivery. We explore APA-ND interactions with an emphasis on curcumin encapsulation, utilizing molecular dynamic simulations and in vitro assessments to evaluate the efficacy of various APA-ND formulations as drug carriers. The methodological approach involved the generation of three unique apoA-I α-11/3 helical mimics, resulting in fifteen distinct APAs. Their structural integrity was rigorously assessed using ColabFold-AF2, with particular attention to pLDDT and pTM scores. Extensive molecular dynamics simulations, covering 1.7 μs across 17 ND systems, were conducted to investigate the influence of APA sequence variations on ND stability and interactions. This study reveals that the composition of APAs, notably the presence of Proline, Serine, and Tryptophan, significantly impacts ND stability and morphology. Oligomeric APAs, in particular, demonstrated superior stability and distinct interaction patterns compared to their monomeric counterparts. Additionally, hydrodynamic diameter measurements over eight weeks indicated sequence-dependent stability, highlighting the potential of specific APA configurations for sustained colloidal stability. In vitro study successfully encapsulated curcumin in [AA]3/DMPC ND formulations, revealing concentration-dependent stability and interaction dynamics. The findings underscore the remarkable capability of APA-NDs to maintain structural integrity and efficient drug encapsulation, positioning them as a promising platform for drug delivery. The study concludes by emphasizing the tunability and versatility of APA-NDs in drug formulation, potentially revolutionizing nanomedicine by enabling customized APA sequences and ND properties for targeted drug delivery. [ABSTRACT FROM AUTHOR]

As the ability to collect profiling data in metabolomics increases substantially with the advances in Liquid Chromatography–Mass Spectrometry (LC-MS) instruments, it is urgent to develop new and powerful data analysis approaches to match the big data collected and to extract as much meaningful information as possible from tens of thousands of molecular features. Here, we applied weighted gene co-expression network analysis (WGCNA), an algorithm popularly used in microarray or RNA sequencing, to plasma metabolomic data and demonstrated several advantages of WGCNA over conventional statistical approaches such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). By using WGCNA, a large number of molecular features were clustered into a few modules to reduce the dimension of a dataset, the impact of phenotypic traits such as diet type and genotype on the plasma metabolome was evaluated quantitatively, and hub metabolites were found based on the network graph. Our work revealed that WGCNA is a very powerful tool to decipher, interpret, and visualize metabolomic datasets. [ABSTRACT FROM AUTHOR]

Many policosanols from different sources, such as sugar cane and rice bran, have been marketed worldwide to improve blood lipid profiles. But so far, no comparative study has commenced elucidating the effect of different policosanols to improve the blood lipid profile and other beneficial effects. This study compared the efficacy of four different policosanols, including one sugar cane wax alcohol from Cuba (Raydel®) and three policosanols from China (Xi'an Natural sugar cane, Xi'an Realin sugar cane, and Shaanxi rice bran), to treat dyslipidemia in hyperlipidemic zebrafish. After 12 weeks of consumption of each policosanol (final 0.1% in diet, wt/wt) and a high-cholesterol diet (HCD, final 4%, wt/wt), the Raydel policosanol group and the Xi'an Natural policosanol group showed the highest survivability, of approximately 81%. In contrast, the Xi'an Realin policosanol and the Shaanxi policosanol groups showed 57% and 67% survivability, respectively. Among the five HCD groups, the Raydel policosanol group showed the lowest serum total cholesterol (TC, p < 0.001 versus HCD control) and triglyceride (p < 0.001 versus HCD control), with the highest percentage of high-density lipoproteins-cholesterol in TC. The Raydel policosanol group also showed the lowest serum aspartate aminotransferase and alanine aminotransferase levels, with the least infiltration of inflammatory cells and interleukin-6 production in hepatocytes with a marked reduction in reactive oxygen species (ROS) production and fatty liver changes. In the ovary, the Raydel policosanol group also showed the highest content of mature vitellogenic oocytes with the lowest production of reactive oxygen species and cellular apoptosis in ovarian cells. In the testes, the Raydel policosanol group also showed the healthiest morphology for spermatogenesis, with the lowest interstitial area and reactive oxygen species production in testicular cells. Conclusively, among the tested policosanols, Cuba (Raydel®) policosanol exhibited a comparatively better effect in maintaining zebrafish body weight, survivability, blood lipid profile, hepatic function biomarkers, fatty liver changes, ROS generation, inflammation, and restoration of the cell morphology in ovaries and testes affected by the HCD consumption. [ABSTRACT FROM AUTHOR]

A specific feature of dyslipidemia in pregnancy is increased high-density lipoprotein (HDL) cholesterol concentration, which is probably associated with maternal endothelium protection. However, preeclampsia is most often associated with low HDL cholesterol, and the mechanisms behind this change are scarcely explored. We aimed to investigate changes in HDL metabolism in risky pregnancies and those complicated by late-onset preeclampsia. We analyze cholesterol synthesis (cholesterol precursors: desmosterol, 7-dehydrocholesterol, and lathosterol) and absorption markers (phytosterols: campesterol and β-sitosterol) within HDL particles (NCSHDL), the activities of principal modulators of HDL cholesterol's content, and major HDL functional proteins levels in mid and late pregnancy. On the basis of the pregnancy outcome, participants were classified into the risk group (RG) (70 women) and the preeclampsia group (PG) (20 women). HDL cholesterol was lower in PG in the second trimester compared to RG (p < 0.05) and followed by lower levels of cholesterol absorption markers (p < 0.001 for campesterolHDL and p < 0.05 for β-sitosterolHDL). Lowering of HDL cholesterol between trimesters in RG (p < 0.05) was accompanied by a decrease in HDL phytosterol content (p < 0.001), apolipoprotein A-I (apoA-I) concentration (p < 0.05), and paraoxonase 1 (PON1) (p < 0.001), lecithin–cholesterol acyltransferase (LCAT) (p < 0.05), and cholesterol ester transfer protein (CETP) activities (p < 0.05). These longitudinal changes were absent in PG. Development of late-onset preeclampsia is preceded by the appearance of lower HDL cholesterol and NCSHDL in the second trimester. We propose that reduced capacity for intestinal HDL synthesis, decreased LCAT activity, and impaired capacity for HDL-mediated cholesterol efflux could be the contributing mechanisms resulting in lower HDL cholesterol. [ABSTRACT FROM AUTHOR]

Tangier disease (TD) is a rare autosomal recessive disorder caused by a variant in the ABCA1 gene, characterized by significantly reduced levels of plasma high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-1 (ApoA-I). TD typically leads to accumulation of cholesterol in the peripheral tissues and early coronary disease but with highly variable clinical expression. Herein, we describe a case study of a 59-year-old male patient with features typical of TD, in whom a likely pathogenic variant in the ABCA1 gene was identified by whole-exome sequencing (WES), identified for the first time as homozygous (NM_005502.4: c.4799A>G (p. His1600Arg)). In silico analysis including MutationTaster and DANN score were used to predict the pathogenicity of the variant and a protein model generated by SWISS-MODEL was built to determine how the homozygous variant detected in our patient may change the protein structure and impact on its function. This case study describes a homozygous variant of the ABCA1 gene, which is responsible for a severe form of TD and underlines the importance of using bioinformatics and genomics for linking genotype to phenotype and better understanding and accounting for the functional impact of genetic variations. [ABSTRACT FROM AUTHOR]

Policosanols from various sources, such as sugar cane, rice bran, and insects, have been marketed to prevent dyslipidemia, diabetes, and hypertension by increasing the blood high-density lipoproteins cholesterol (HDL-C) levels. On the other hand, there has been no study on how each policosanol influences the quality of HDL particles and their functionality. Reconstituted high-density lipoproteins (rHDLs) with apolipoprotein (apo) A-I and each policosanol were synthesized using the sodium cholate dialysis method to compare the policosanols in lipoprotein metabolism. Each rHDL was compared regarding the particle size and shape, antioxidant activity, and anti-inflammatory activity in vitro and in zebrafish embryos. This study compared four policosanols including one policosanol from Cuba (Raydel® policosanol) and three policosanols from China (Xi'an Natural sugar cane, Xi'an Realin sugar cane, and Shaanxi rice bran). The synthesis of rHDLs with various policosanols (PCO) from Cuba or China using a molar ratio of 95:5:1:1 with palmitoyloleoyl phosphatidylcholine (POPC): free cholesterol (FC): apoA-I:PCO (wt:wt) showed that rHDL containing Cuban policosanol (rHDL-1) showed the largest particle size and the most distinct particle shape. The rHDL-1 showed a 23% larger particle diameter and increased apoA-I molecular weight with a 1.9 nm blue shift of the maximum wavelength fluorescence than rHDL alone (rHDL-0). Other rHDLs containing Chinese policosanols (rHDL-2, rHDL-3, and rHDL-4) showed similar particle sizes with an rHDL-0 and 1.1–1.3 nm blue shift of wavelength maximum fluorescence (WMF). Among all rHDLs, the rHDL-1 showed the strongest antioxidant ability to inhibit cupric ion-mediated LDL oxidation. The rHDL-1-treated LDL showed the most distinct band intensity and particle morphology compared with the other rHDLs. The rHDL-1 also exerted the highest anti-glycation activity to inhibit the fructose-mediated glycation of human HDL2 with the protection of apoA-I from proteolytic degradation. At the same time, other rHDLs showed a loss of anti-glycation activity with severe degradation. A microinjection of each rHDL alone showed that rHDL-1 had the highest survivability of approximately 85 ± 3%, with the fastest developmental speed and morphology. In contrast, rHDL-3 showed the lowest survivability, around 71 ± 5%, with the slowest developmental speed. A microinjection of carboxymethyllysine (CML), a pro-inflammatory advanced glycated end product, into zebrafish embryos resulted in severe embryo death of approximately 30 ± 3% and developmental defects with the slowest developmental speed. On the other hand, the phosphate buffered saline (PBS)-injected embryo showed 83 ± 3% survivability. A co-injection of CML and each rHDL into adult zebrafish showed that rHDL-1 (Cuban policosanol) induced the highest survivability, around 85 ± 3%, while rHDL-0 showed 67 ± 7% survivability. In addition, rHDL-2, rHDL-3, and rHDL-4 showed 67 ± 5%, 62 ± 37, and 71 ± 6% survivability, respectively, with a slower developmental speed and morphology. In conclusion, Cuban policosanol showed the strongest ability to form rHDLs with the most distinct morphology and the largest size. The rHDL-containing Cuban policosanol (rHDL-1) showed the strongest antioxidant ability against LDL oxidation, anti-glycation activity to protect apoA-I from degradation, and the highest anti-inflammatory activity to protect embryo death under the presence of CML. [ABSTRACT FROM AUTHOR]

Combined endurance and dynamic-resistance exercise has important anti-inflammatory effects, altering vascular endothelial function, and helping to prevent and treat aging-related metabolic syndrome (MS). We studied changes in 40 elderly women aged ≥ 65 years (control group (no MS), n = 20, mean age: 68.23 ± 2.56 years; MS group, n = 19, mean age: 71.42 ± 5.87 years; one left). The exercise program comprised dynamic-resistance training using elastic bands, three times weekly, for six months. We analyzed body composition, blood pressure, physical fitness, and MS-related blood variables including ApoA-I, antioxidant factors, and inflammatory markers. After the program, the MS group showed significant reductions in waist-hip ratio, waist circumference, diastolic blood pressure, blood insulin, and HOMA-IR, and a significant increase in HSP70 (p < 0.05). Both groups showed significant increases in ApoA-I levels, ApoA-I/HDL-C ratio, SOD2, IL-4, and IL-5 levels (p < 0.05). Active-resistance training-induced changes in ApoA-I were significantly positively correlated with changes in HDL-C and HSP70, and significantly negatively correlated with changes in triglycerides, C-reactive protein, and TNF-α (p < 0.05). Active-resistance training qualitatively altered HDL, mostly by altering ApoA-I levels, relieving vascular inflammation, and improving antioxidant function. This provides evidence that dynamic-resistance exercise can improve physical fitness and MS risk factors in elderly women. [ABSTRACT FROM AUTHOR]

Viral infections can promote cytokine storm and multiorgan failure in individuals with an underlying immunosuppression or specific genetic background. Hyperinflammatory states, including critical forms of COVID-19, are characterized by a remodeling of the lipid profile including a dramatic decrease of the serum levels of apolipoprotein-A-I (ApoA-I), a protein known for its capacity to reduce systemic and lung inflammation, modulate innate and adaptive immunity, and prevent endothelial dysfunction and blood coagulation. In this study, four immunocompromised patients with severe COVID-19 cytokine storm that progressed despite standard-of-care therapy [Omicron (n = 3) and Delta (n = 1) variants] received 2- 4 infusions (10mg/kg) of CER-001, an ApoA-I-containing HDL mimetic. Injections were well-tolerated with no serious adverse events. Three patients treated while not on mechanical ventilation had early clinical and biological improvement (oxygen withdrawal and correction of hematological and inflammatory parameters, including serum levels of interleukin-8) and were discharged from the hospital 3-4 days after CER-001 infusions. In the fourth patient who received CER-001 after orotracheal intubation for acute respiratory distress syndrome, infusions were followed by transient respiratory improvement before secondary worsening related to ventilation-associated pneumonia. This pilot uncontrolled exploratory compassionate study provides initial safety and proof-of-concept data from patients with a COVID-19 cytokine storm receiving ApoA-I. Further randomized controlled trial evaluation is now required to ascertain whether ApoA-I has any beneficial effects on patients with a COVID-19 cytokine storm. [ABSTRACT FROM AUTHOR]

Apolipoprotein A-I (apoA-I), the main protein component of High-Density Lipoprotein (HDL), is modified in plasma and the arterial wall by various enzymes. Myeloperoxidase (MPO), a leukocyte-derived peroxidase, is highly expressed during inflammation and associates with HDL reducing its functionality and contributing to atherosclerosis. In the present study we sought to explore further the effect of MPO on HDL structure and functionality in vivo using adenovirus-mediated gene transfer of human MPO combined with human apoA-I forms containing substitutions at MPO-sensitive sites or wild type apoA-I. We found that overexpression of MPO in mice significantly increased plasma apoA-I and HDL levels without affecting the expression of genes involved in HDL biogenesis or catabolism in the liver. Overexpression of MPO in the liver reduced the expression of pro-inflammatory genes and increased or did not affect the expression of anti-inflammatory genes suggesting that MPO had no toxic effects in this organ. In the plasma of mice overexpressing MPO, no significant alterations in HDL size or electrophoretic mobility was observed with the exception of mice expressing apoA-I (M148A) which showed enriched pre-β relative to α HDL particles, suggesting that the apoA-I (M148A) mutation may interfere with HDL remodelling. Overexpression of MPO was associated with reduced anti-oxidant capacity of HDL particles in all mice. Interestingly, HDL particles bearing apoA-I (Y192A) showed enhanced ABCA1-dependent cholesterol efflux from macrophages which was not affected by MPO and these mice had reduced levels of LDL-c. These findings provide new insights on the role of specific amino acid residues of apoA-I in HDL structure and function following modification by MPO. This knowledge may facilitate the development of novel therapies based on improved HDL forms for patients with chronic diseases that are characterized by dysfunctional HDL. • Τhe effect of MPO on HDL structure and functions was investigated in vivo using adenovirus mediated gene transfer. • Overexpression of MPO increased apoA-I and HDL-c levels in mice expressing human apoA-I. • Mice expressing apoA-I (Y192) has lower LDL-c levels in plasma. • HDL with apoA-I (Y192A) mutation had enhanced ABCA1-dependent cholesterol efflux in macrophages which was unaffected by MPO. • apoA-I mutants with improved functionality could be exploited for novel apoA-I based therapies of patients with CVD. [ABSTRACT FROM AUTHOR]

Cholesterol efflux is the first and rate-limiting step of reverse cholesterol transport (RCT) from peripheric cells to the liver. The involvement of high-density lipoprotein (HDL) in RCT determines the atheroprotective properties of HDL. Cholesterol efflux from different membrane pools includes both passive and energy-dependent processes. The first type of route consists of cholesterol desorption from the cell membrane into the unstirred layer adjacent to the cell surface and diffusion in the water phase. Moreover, the selective uptake and facilitated diffusion of cholesterol and cholesteryl ester molecules through the hydrophobic tunnel in the scavenger receptor BI molecule does not require energy consumption. The second type of route includes active cholesterol export by the ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1). Several cholesterol acceptors specifically bind cholesterol and phospholipid molecules, and cholesterol binding to the albumin molecule, which acts as a shuttle, significantly increases cholesterol movement between acceptors and red blood cells, thus functioning as a sink for cholesterol. Cholesterol and phospholipid molecules effluxed from macrophages by ABCA1 are accepted exclusively by the lipid-free apolipoprotein apoA-I, which is the major protein moiety of HDL, whereas those effluxed by ABCG1 are accepted by HDL. ABCA1- and ABCG1-mediated cholesterol transport, together with cholesterol diffusion, largely determine cholesterol turnover at the physiological level of intracellular cholesterol. However, at cholesterol overload, ABCA1-mediated efflux prevails over other routes. The exchange of apoA-I between lipid-free and lipid-associated states and the synergism of nascent and mature HDL contribute to cholesterol efflux efficiency. Moreover, extracellular cholesterol deposits and microvesicles may be involved in RCT. [ABSTRACT FROM AUTHOR]

Background: Despite use of drug-eluting stents (DES), in-stent restenosis (ISR) continues adversely affecting clinical outcomes of patients undergoing percutaneous coronary intervention (PCI). Apolipoprotein A-I (apoA-I) has athero-protective effects. However, there is a paucity of clinical data regarding the association between apoA-I and ISR. We sought to investigate whether serum apoA-I is related to ISR after DES-based PCI.Methods: In this retrospective case control study, 604 consecutive patients who underwent DES implantation before were enrolled. Patients who underwent repeat angiography within 12 months were included in the early ISR study (n = 205), while those beyond 12 months were included in the late ISR study (n = 399). ISR was defined as the presence of > 50% diameter stenosis at the stent site or at its edges. Clinical characteristics were compared between ISR and non-ISR patients in the early and late ISR study, respectively, after adjusting for confounding factors by multivariate logistic regression, stratified analysis, and propensity score matching. The predictive value was assessed by univariate and multivariate logistic regression analysis, receiver operating characteristic (ROC) curve analysis, and quartile analysis.Results: In the early ISR study, 8.8% (18 of 205) patients developed ISR. Serum apoA-I in the ISR group was lower than that in the non-ISR group (1.1 ± 0.26 vs. 1.24 ± 0.23, P < 0.05). On multivariate logistic regression analysis, apoA-I was an independent risk factor for early ISR. Incidence of early ISR showed negative correlation with apoA-I and could be predicted by the combined use of apoA-I and glycosylated hemoglobin (HbA1c) level. In the late ISR study, 21.8% (87 of 399) patients developed ISR. On subgroup analysis, late ISR showed negative correlation with apoA-I irrespective of intensive lipid lowering; on multivariate logistic regression analysis, apoA-I was also an independent risk factor for late ISR. In patients with intensive lipid lowering, combined use of apoA-I, stenting time, and diabetes predicted the incidence of late ISR.Conclusions: ApoA-I was an independent risk factor for ISR, and showed a negative correlation with ISR after DES-based PCI. Combined use of apoA-I and clinical indicators may better predict the incidence of ISR under certain circumstances. [ABSTRACT FROM AUTHOR]

Chronic obstructive pulmonary disease (COPD) is a widespread disease associated with high rates of disability and mortality. COPD is characterized by chronic inflammation in the bronchi as well as systemic inflammation, which contributes significantly to the clinically heterogeneous course of the disease. Lipid metabolism disorders are common in COPD, being a part of its pathogenesis. High-density lipoproteins (HDLs) are not only involved in lipid metabolism, but are also part of the organism's immune and antioxidant defense. In addition, HDL is a versatile transport system for endogenous regulatory agents and is also involved in the removal of exogenous substances such as lipopolysaccharide. These functions, as well as information about lipoprotein metabolism disorders in COPD, allow a broader assessment of their role in the pathogenesis of heterogeneous and comorbid course of the disease. [ABSTRACT FROM AUTHOR]

A higher concentration of apolipoprotein A-I (ApoA-I) is associated with increased high density lipoprotein functionality and reverse cholesterol transport (RCT). A promising strategy to prevent cardiovascular diseases is therefore to improve RCT by increasing de novo ApoA-I production. Since experimental animal models have suggested effects of amino acids on hepatic lipoprotein metabolism, we here examined the effects of different amino acids on hepatic ApoA-I production. Human hepatocytes (HepG2) were exposed to six individual amino acids for 48 h. ApoA-I transcription and secreted pro-ApoA-I protein concentrations were analyzed using quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assays (ELISA), respectively. Additionally, CPT1 and KEAP1 mRNA expression, peroxisome proliferator-activated receptor alpha (PPARα) transactivation, and mechanistic target of rapamycin complex 1 (mTORC1) phosphorylation were determined. Leucine, glutamic acid, and tryptophan increased ApoA-I and CPT1 mRNA expression. Tryptophan also strongly increased PPARα transactivation. Glutamine, proline, and histidine increased pro-ApoA-I protein concentrations but mTORC1 phosphorylation remained unchanged regardless of the amino acid provided. In conclusion, individual amino acids have different effects on ApoA-I mRNA expression and pro-ApoA-I production which can partially be explained by specific effects on PPARα transactivation, while mTORC1 phosphorylation remained unaffected. [ABSTRACT FROM AUTHOR]

The maintenance of cellular cholesterol homeostasis is essential for normal cell function and viability. Excessive cholesterol accumulation is detrimental to cells and serves as the molecular basis of many diseases, such as atherosclerosis, Alzheimer's disease, and diabetes mellitus. The peripheral cells do not have the ability to degrade cholesterol. Cholesterol efflux is therefore the only pathway to eliminate excessive cholesterol from these cells. This process is predominantly mediated by ATP-binding cassette transporter A1 (ABCA1), an integral membrane protein. ABCA1 is known to transfer intracellular free cholesterol and phospholipids to apolipoprotein A-I (apoA-I) for generating nascent high-density lipoprotein (nHDL) particles. nHDL can accept more free cholesterol from peripheral cells. Free cholesterol is then converted to cholesteryl ester by lecithin:cholesterol acyltransferase to form mature HDL. HDL-bound cholesterol enters the liver for biliary secretion and fecal excretion. Although how cholesterol is transported by ABCA1 to apoA-I remains incompletely understood, nine models have been proposed to explain this effect. In this review, we focus on the current view of the mechanisms underlying ABCA1-mediated cholesterol efflux to provide an important framework for future investigation and lipid-lowering therapy. [ABSTRACT FROM AUTHOR]

Apolipoprotein A‐I (apoA‐I) has a key function in the reverse cholesterol transport. However, aggregation of apoA‐I single point mutants can lead to hereditary amyloid pathology. Although several studies have tackled the biophysical and structural consequences introduced by these mutations, there is little information addressing the relationship between the evolutionary and structural features that contribute to the amyloid behavior of apoA‐I. We combined evolutionary studies, in silico mutagenesis and molecular dynamics (MD) simulations to provide a comprehensive analysis of the conservation and pathogenic role of the aggregation‐prone regions (APRs) present in apoA‐I. Sequence analysis demonstrated that among the four amyloidogenic regions described for human apoA‐I, only two (APR1 and APR4) are evolutionary conserved across different species of Sarcopterygii. Moreover, stability analysis carried out with the FoldX engine showed that APR1 contributes to the marginal stability of apoA‐I. Structural properties of full‐length apoA‐I models suggest that aggregation is avoided by placing APRs into highly packed and rigid portions of its native fold. Compared to silent variants extracted from the gnomAD database, the thermodynamic and pathogenic impact of amyloid mutations showed evidence of a higher destabilizing effect. MD simulations of the amyloid variant G26R evidenced the partial unfolding of the alpha‐helix bundle with the concomitant exposure of APR1 to the solvent, suggesting an insight into the early steps involved in its aggregation. Our findings highlight APR1 as a relevant component for apoA‐I structural integrity and emphasize a destabilizing effect of amyloid variants that leads to the exposure of this region. [ABSTRACT FROM AUTHOR]

High-density lipoproteins (HDLs) are complex, heterogenous lipoprotein particles, consisting of a large family of apolipoproteins, formed in subspecies of distinct shapes, sizes, and functions and are synthesized in both the brain and the periphery. HDL apolipoproteins are important determinants of Alzheimer's disease (AD) pathology and vascular dementia, having both central and peripheral effects on brain amyloid-beta (Aβ) accumulation and vascular functions, however, the extent to which HDL particles (HLD-P) can exchange their protein and lipid components between the central nervous system (CNS) and the systemic circulation remains unclear. In this review, we delineate how HDL's structure and composition enable exchange between the brain, cerebrospinal fluid (CSF) compartment, and vascular cells that ultimately affect brain amyloid metabolism and atherosclerosis. Accordingly, we then elucidate how modifications of HDL-P have diagnostic and therapeutic potential for brain vascular and neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Peptides have many advantages over traditional therapeutics, including small molecules and other biologics, because of their low toxicity and immunogenicity, while still exhibiting efficacy. This review discusses the benefits and mechanism of action of apolipoprotein mimetic peptides in tumor biology and their potential utility in treating various cancers. Among lipoproteins in the circulation, high-density lipoprotein (HDL) and its constituents including apolipoprotein A-I (apoA-I; the predominant protein in HDL), apoJ, and apoE, harbor anti-tumorigenic activities. Peptides that mimic apoA-I function have been developed through molecular mimicry of the amphipathic α-helices of apoA-I. Oral apoA-I mimetic peptides remodel HDL, promote cholesterol efflux, sequester oxidized lipids, and activate anti-inflammatory processes. ApoA-I and apoJ mimetic peptides ameliorate various metrics of cancer progression and have demonstrated efficacy in preclinical models in the inhibition of ovarian, colon, breast, and metastatic lung cancers. Apolipoprotein mimetic peptides are poorly absorbed when administered orally and rapidly degraded when injected into the circulation. The small intestine is the major site of action for apoA-I mimetic peptides and recent studies suggest that modulation of immune cells in the lamina propria of the small intestine is, in part, a potential mechanism of action. Finally, several recent studies underscore the use of reconstituted HDL as target-specific nanoparticles carrying poorly soluble or unstable therapeutics to tumors even across the blood-brain barrier. Preclinical studies suggest that these versatile recombinant lipoprotein based nanoparticles and apolipoprotein mimetics can serve as safe, novel drug delivery, and therapeutic agents for the treatment of a number of cancers. [ABSTRACT FROM AUTHOR]

A variety of rodents have been used as experimental animals in metabolic studies of plasma lipids and lipoproteins. These studies have included understanding the functional role of apolipoprotein A‐I, the major protein on the surface of HDL. Reviewing the genomic database for entries for rodent apoA‐I genes, it was discovered that the naked mole‐rat (Heterocephalus glaber) gene encoded a protein with a cysteine at residue 28. Previously, two cases have been reported in which human heterozygotes had apoA‐I with cysteine at residues 173 (apoA‐I Milano) or at 151 (apoA‐I Paris). Interestingly, both groups, in spite of having low levels of HDL and moderately elevated plasma triacylglycerols, had no evidence of cardiovascular disease. Moreover, the presence of the cysteine enabled the apoA‐I to form both homodimers and heterodimers. Prior to this report, no other mammalian apoA‐I has been found with a cysteine in its sequence. In addition, the encoded naked mole‐rat protein had different amino acids at sites that were conserved in all other mammals. These differences resulted in naked mole‐rat apoA‐I having an unexpected neutral pI value, whereas other mammalian apoA‐I have negative pI values. To verify these sequence differences and to determine if the N‐terminal location of C28 precluded dimer formation, we conducted mass spectrometry analyses of apoA‐I and other proteins associated with HDL. Consistent with the genomic data, our analyses confirmed the presence of C28 and the formation of a homodimer. Analysis of plasma lipids surprisingly revealed a profile similar to the human heterozygotes. [ABSTRACT FROM AUTHOR]

Apolipoprotein (apo) A‐I, the major structural protein of high‐density lipoprotein (HDL), is present in human and mouse cerebrospinal fluid (CSF) despite its lack of expression in brain cells. To identify the origin of apoA‐I in CSF, we generated intestine‐specific and liver‐specific Apoa1 knockout mice (Apoa1ΔInt and Apoa1Δliv mice, respectively). Lipoprotein profiles of Apoa1ΔInt and Apoa1ΔLiv mice resembled those of control littermates, whereas knockout of Apoa1 in both intestine and liver (Apoa1ΔIntΔLiv) resulted in a 60‐percent decrease in HDL‐cholesterol levels, thus strongly mimicking the Apoa1−/− mice. Immunoassays revealed that mouse apoA‐I was not present in the CSF of the Apoa1ΔIntΔLiv mice. Furthermore, apoA‐I levels in CSF were highly correlated with plasma spherical HDL levels, which were regulated by ABCA1 and LCAT. Collectively, these results suggest that apoA‐I protein in CSF originates in liver and small intestine and is taken up from the plasma. [ABSTRACT FROM AUTHOR]

Background: Alzheimer's disease (AD) is an inflammatory neurodegenerative disease that may be associated with prior bacterial infections. Microbial "old friends" can suppress exaggerated inflammation in response to disease-causing infections or increase clearance of pathogens such as Mycobacterium tuberculosis, which causes tuberculosis (TB). One such "old friend" is Mycobacterium vaccae NCTC 11659, a soil-derived bacterium that has been proposed either as a vaccine for prevention of TB, or as immunotherapy for the treatment of TB when used alongside first line anti-TB drug treatment.Objective: The goal of this study was to use a hypothesis generating approach to explore the effects of M. vaccae on physiological changes in the plasma and cerebrospinal fluid (CSF).Methods: Liquid chromatography-tandem mass spectrometry-based proteomics were performed in plasma and CSF of adult male rats after immunization with a heat-killed preparation of M. vaccae NCTC 11659 or borate-buffered saline vehicle. Gene enrichment analysis and analysis of protein-protein interactions were performed to integrate physiological network changes in plasma and CSF. We used RT-qPCR to assess immune and metabolic gene expression changes in the hippocampus.Results: In both plasma and CSF, immunization with M. vaccae increased proteins associated with immune activation and downregulated proteins corresponding to lipid (including phospholipid and cholesterol) metabolism. Immunization with M. vaccae also increased hippocampal expression of interleukin-4 (IL-4) mRNA, implicating anti-inflammatory effects in the central nervous system.Conclusion: M. vaccae alters host immune activity and lipid metabolism. These data are consistent with the hypothesis that microbe-host interactions may protect against possible infection-induced, inflammation-related cognitive impairments. [ABSTRACT FROM AUTHOR]

High-density lipoprotein cholesterol (HDL-C) levels are reduced in patients with chronic liver disease and inversely correlate with disease severity. During acute conditions such as sepsis, HDL-C levels decrease rapidly and HDL particles undergo profound changes in their composition and function. We aimed to determine whether indices of HDL quantity and quality associate with progression and survival in patients with advanced liver disease. HDL-related biomarkers were studied in 508 patients with compensated or decompensated cirrhosis (including acute-on-chronic liver failure [ACLF]) and 40 age- and gender-matched controls. Specifically, we studied levels of HDL-C, its subclasses HDL2-C and HDL3-C, and apolipoprotein A1 (apoA-I), as well as HDL cholesterol efflux capacity as a metric of HDL functionality. Baseline levels of HDL-C and apoA-I were significantly lower in patients with stable cirrhosis compared to controls and were further decreased in patients with acute decompensation (AD) and ACLF. In stable cirrhosis (n = 228), both HDL-C and apoA-I predicted the development of liver-related complications independently of model for end-stage liver disease (MELD) score. In patients with AD, with or without ACLF (n = 280), both HDL-C and apoA-I were MELD-independent predictors of 90-day mortality. On ROC analysis, both HDL-C and apoA-I had high diagnostic accuracy for 90-day mortality in patients with AD (AUROCs of 0.79 and 0.80, respectively, similar to that of MELD 0.81). On Kaplan-Meier analysis, HDL-C <17 mg/dl and apoA-I <50 mg/dl indicated poor short-term survival. The prognostic accuracy of HDL-C was validated in a large external validation cohort of 985 patients with portal hypertension due to advanced chronic liver disease (AUROCs HDL-C: 0.81 vs. MELD: 0.77). HDL-related biomarkers are robust predictors of disease progression and survival in chronic liver failure. People who suffer from cirrhosis (scarring of the liver) have low levels of cholesterol carried by high-density lipoproteins (HDL-C). These alterations are connected to inflammation, which is a problem in severe liver disease. Herein, we show that reduced levels of HDL-C and apolipoprotein A-I (apoA-I, the main protein carried by HDL) are closely linked to the severity of liver failure, its complications and survival. Both HDL-C and apoA-I can be easily measured in clinical laboratories and are as good as currently used prognostic scores calculated from several laboratory values by complex formulas. • HDL levels are profoundly decreased in chronic liver failure. • HDL-related biomarkers (HDL-C, apoA-I) are robust predictors of disease progression and survival. • The prognostic value of single HDL-related biomarkers is very similar to that of the composite scores. • HDL-related biomarkers correlated inversely with markers of inflammation. [ABSTRACT FROM AUTHOR]

• ApoA-I is generally considered to be synthesized in the liver (hepatocytes) and small intestine (enterocytes). • Computer analysis of ApoA-I has shown that ApoA-I may be released in monocyte-macrophage cells. • ApoA-I expression has been detected in monocytes and macrophages. • Endogenous ApoA-I in macrophages has anti-inflammatory and cholesterol efflux effects. ApoA-I is a major protein component of high-density lipoprotein (HDL) that is widely known for regulating cholesterol trafficking and inflammatory and immune responses and for protecting against atherosclerosis. ApoA-I is generally considered to be synthesized in the liver (hepatocytes) and small intestine (enterocytes). However, computer analysis of ApoA-I has shown that the ApoA-I gene may be expressed in not only hepatocytes and enterocytes but also monocyte-macrophage cells, dendritic cells (DCs) and T cells. ApoA-I expression has been detected in THP-1 monocytes and macrophages, peripheral blood mononuclear cells (PBMCs) from postmenopausal women, human PBMC-derived monocytes and macrophages, mouse peritoneal macrophages, etc. Endogenous ApoA-I in macrophages has anti-inflammatory and cholesterol efflux effects. However, our understanding of the detailed roles of macrophage-synthesized ApoA-I is still at an early stage and very limited. More experiments are needed to elucidate the exact roles of endogenous ApoA-I in macrophages. Several lines of evidence indicate that recombinant exogenous human ApoA-I in mouse macrophages increases cholesterol efflux and thus reduces atherosclerosis development. Considering the antiatherogenic effect of exogenous ApoA-I overexpression in mouse macrophages, better understanding the role and mechanisms underlying macrophage-synthesized ApoA-I in atherosclerosis will enable macrophage-synthesized ApoA-I therapy to open new avenues for reducing the risk of atherosclerosis. [ABSTRACT FROM AUTHOR]

The strong inverse relationship between low levels of high-density lipoproteins (HDLs) and atherosclerotic cardiovascular disease (CVD) led to the designation of HDL as the "good" cholesterol. The atheroprotection is thought to reflect HDL's capacity to efflux cholesterol from macrophages, followed by interaction with other lipoproteins in the plasma, processing by the liver and excretion into bile. However, pharmacologic increases in HDL-C levels have not led to expected clinical benefits, giving rise to the concept of dysfunctional HDL, in which increases in serum HDL-C are not beneficial due to lost or altered HDL functions and transition to "bad" HDL. It is now understood that the cholesterol in HDL, measured by HDL-C, is neither a marker nor the mediator of HDL function, including cholesterol efflux capacity. It is also understood that besides cholesterol efflux, HDL functionality encompasses many other potentially beneficial functions, including antioxidant, anti-inflammatory, antithrombotic, anti-apoptotic, and vascular protective effects that may be critical protective pathways for various cells, including those in the kidney parenchyma. This review highlights advances in our understanding of the role kidneys play in HDL metabolism, including the effects on levels, composition, and functionality of HDL particles, particularly the main HDL protein, apolipoprotein AI (apoAI). We suggest that normal apoAI/HDL in the glomerular filtrate provides beneficial effects, including lymphangiogenesis, that promote resorption of renal interstitial fluid and biological particles. In contrast, dysfunctional apoAI/HDL activates detrimental pathways in tubular epithelial cells and lymphatics that lead to interstitial accumulation of fluid and harmful particles that promote progressive kidney damage. [ABSTRACT FROM AUTHOR]

Apolipoprotein A-I (apoA-I), the main protein constituent of HDLs, increases insulin synthesis and insulin secretion in pancreatic β cells. ApoA-I also accepts cholesterol that effluxes from cells expressing ATP-binding cassette transporter A1 (ABCA1) and ATP-binding cassette transporter G1 (ABCG1). Mice with conditional deletion of ABCA1 and ABCG1 in β cells [β-double knockout (DKO) mice] have increased islet cholesterol levels and reduced glucose-stimulated insulin secretion (GSIS). The project asks whether metabolic pathways are dysregulated in β-DKO mouse islets and whether this can be corrected, and GSIS improved, by treatment with apoA-I. β-DKO mice were treated with apoA-I or PBS, and islets were isolated for determination of GSIS. Total RNA was extracted from β-DKO and control mouse islets for microarray analysis. Metabolic pathways were interrogated by functional enrichment analysis. ApoA-I treatment improved GSIS in β-DKO but not control mouse islets. Plasma lipid and lipoprotein levels and islet cholesterol levels were also unaffected by treatment with apoA-I. Cholesterol metabolism, glucose metabolism, and inflammation pathways were dysregulated in β-DKO mouse islets. This was not corrected by treatment with apoA-I. In summary, apoA-I treatment improves GSIS by a cholesterol-independent mechanism, but it does not correct metabolic dysregulation in β-DKO mouse islets.--Hou, L., Tang, S., Wu, B. J., Ong, K.-L., Westerterp, M., Barter, P. J., Cochran, B. J., Tabet, F., Rye, K.-A. Apolipoprotein A-I improves pancreatic β-cell function independent of the ATP-binding cassette transporters ABCA1 and ABCG1. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: Finding new treatment alternatives for individuals with diabetes with severe insulin resistance is highly desired. To identify novel mechanisms that improve glucose uptake in skeletal muscle, independently from insulin levels and signalling, we have explored the therapeutic potential of a short peptide sequence, RG54, derived from apolipoprotein A-I (ApoA-I). Methods: INS-1E rat clonal beta cells, C2C12 rat muscle myotubes and J774 mouse macrophages were used to study the impact of RG54 peptide on glucose-stimulated insulin secretion, glucose uptake and cholesterol efflux, respectively. GTTs were carried out on diet-induced insulin-resistant and Leprdb diabetic mouse models treated with RG54 peptide, and the impact of RG54 peptide on atherosclerosis was evaluated in Apoe−/− mice. Control mice received ApoA-I protein, liraglutide or NaCl. Results: The synthetic RG54 peptide induced glucose uptake in cultured muscle myotubes by a similar amount as insulin, and also primed pancreatic beta cells for improved glucose-stimulated insulin secretion. The findings were verified in diet-induced insulin-resistant and Leprdb diabetic mice, jointly confirming the physiological effect. The RG54 peptide also efficiently catalysed cholesterol efflux from macrophages and prevented the formation of atherosclerotic plaques in Apoe−/− mice. Conclusions/interpretation: The RG54 peptide exhibits good prospects for providing glucose control and reducing the risk of cardiovascular disease in individuals with severe insulin resistance. [ABSTRACT FROM AUTHOR]

Macrophages are core cellular elements of both early and advanced atherosclerosis. They take up modified lipoproteins and become lipid-loaded foam cells and secrete factors that influence other cell types in the artery wall involved in atherogenesis. Apoproteins E, AI, and SAA are all found on HDL which can enter the artery wall. In addition, apoE is synthesized by macrophages. These three apoproteins can promote cholesterol efflux from lipid-loaded macrophages and have other functions that modulate macrophage biology. Mimetic peptides based on the sequence or structure of these apoproteins replicate some of these properties and are potential therapeutic agents for the treatment of atherosclerosis to reduce cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Much evidence suggests a protective role of high-density lipoprotein (HDL) and its major apolipoprotein apoA-I, in Alzheimer's disease (AD). The biogenesis of nascent HDL derived from a first lipidation of apoA-I, which is synthesized by the liver and intestine but not in the brain, in a process mediated by ABCA1. The maturation of nascent HDL in mature spherical HDL is due to a subsequent lipidation step, LCAT-mediated cholesterol esterification, and the change of apoA-I conformation. Therefore, different subclasses of apoA-I-HDL simultaneously exist in the blood circulation. Here, we investigated if and how the lipidation state affects the ability of apoA-I-HDL to target and modulate the cerebral β-amyloid (Aβ) content from the periphery, that is thus far unclear. In particular, different subclasses of HDL, each with different apoA-I lipidation state, were purified from human plasma and their ability to cross the blood-brain barrier (BBB), to interact with Aβ aggregates, and to affect Aβ efflux across the BBB was assessed in vitro using a transwell system. The results showed that discoidal HDL displayed a superior capability to promote Aβ efflux in vitro (9 × 10-5 cm/min), when compared to apoA-I in other lipidation states. In particular, no effect on Aβ efflux was detected when apoA-I was in mature spherical HDL, suggesting that apoA-I conformation, and lipidation could play a role in Aβ clearance from the brain. Finally, when apoA-I folded its structure in discoidal HDL, rather than in spherical ones, it was able to cross the BBB in vitro and strongly destabilize the conformation of Aβ fibrils by decreasing the order of the fibril structure (-24%) and the β-sheet content (-14%). These data suggest that the extent of apoA-I lipidation, and consequently its conformation, may represent crucial features that could exert their protective role in AD pathogenesis. [ABSTRACT FROM AUTHOR]

Cerebral amyloid angiopathy (CAA) is a common cause of lobar intracerebral hemorrhage (ICH) in elderly individuals and it is the result of the cerebrovascular deposition of beta-amyloid (Aβ) protein. CAA is frequently found in patients with Alzheimer's disease (AD), although it has an independent contribution to the cognitive deterioration associated with age. Specific apolipoproteins (Apo) have been associated with Aβ fibrillization and clearance from the brain. In this regard, in the present study, we analyzed the brain levels of ApoE, ApoA-I, and ApoJ/clusterin in autopsy brains from 20 post-mortem cases with CAA type I, CAA type II, with parenchymal Aβ deposits or without Aβ deposits. Our objective was to find a possible differential pattern of apolipoproteins distribution in the brain depending on the CAA pathological presentation. The protein expression levels were adjusted by the APOE genotype of the patients included in the study. We found that ApoE and ApoJ were abundantly present in meningeal, cortical, and capillary vessels of the brains with vascular Aβ accumulation. ApoE and ApoJ also deposited extracellularly in the parenchyma, especially in cases presenting Aβ diffuse and neuritic parenchymal deposits. In contrast, ApoA-I staining was only relevant in capillary walls in CAA type I cases. On the other hand, ICH was the principal cause of death among CAA patients in our cohort. We found that CAA patients with ICH more commonly had APOEε2 compared with CAA patients without ICH. In addition, patients who suffered an ICH presented higher vascular ApoE levels in brain. However, higher ApoE presence in cortical arteries was the only independent predictor of suffering an ICH in our cohort after adjusting by age and APOE genotype. In conclusion, while ApoE and ApoJ appear to be involved in both vascular and parenchymal Aβ pathology, ApoA-I seems to be mainly associated with CAA, especially in CAA type I pathology. We consider that our study helps to molecularly characterize the distribution subtypes of Aβ deposition within the brain. [ABSTRACT FROM AUTHOR]

ATP-binding cassette transporter A1 (ABCA1) is critical for the generation of nascent high-density lipoprotein (HDL) and plays important roles in cholesterol homeostasis. ABCA1 has two large extracellular domains (ECDs), which may interact directly with apolipoprotein A-I (apoA-I). However, the molecular mechanisms underlying HDL formation and the importance of ABCA1-apoA-I interactions in HDL formation remain unclear. We investigated the ABCA1-apoA-I interaction in photo-activated crosslinking experiments using sulfo-SBED-labeled apoA-I. ApoA-I bound to cells expressing ABCA1, but not to untransfected cells or cells expressing non-functional ABCA1. Binding was inhibited by sulfo-SBED-labeled apoA-I, and crosslinking of sulfo-SBED-labeled apoA-I with ABCA1 was inhibited by non-labeled apoA-I, suggesting that sulfo-SBED-labeled apoA-I specifically binds and crosslinks with functional ABCA1. Proteolytic digestion of crosslinked ABCA1 revealed that apoA-I bound the N-terminal half of ABCA1, and that the first ECD of ABCA1 is an apoA-I binding site. Abbreviations: ABC: ATP-binding cassette; apoA-I: apolipoprotein A-I; ATP: adenosine triphosphate; CHAPS: 3-(3-cholamidepropyl)dimethylammonio-1- propanesulphonate; DTT: dithiothreitol; ECD: extra cellular domain; EDTA: ethylenediaminetetraacetic acid; GFP: green fluorescent protein; HA: hemagglutinin; HDL: high density lipoprotein; HEK: human embryonic kidney; HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; sulfo-SBED: (sulfosuccinimidyl-2-[6-(biotinamido)-2-(p-azidobenzamido)hexanoamido] ethyl-1,3ʹ-dithiopropionate; NHS-ester, N-hydroxysuccinimide-ester [ABSTRACT FROM AUTHOR]

Highlights • New nanoparticles using human apoA-I and well-characterized apoA-I mimetic peptide 4F with POPC in the absence of chemical detergents. • Presence of 4F in nanoparticles potentially enhances biological activities of human apoAI:lipid nanoparticles. • New nanoparticles are stable to oxidative process. • ApoA-I-4F:POPC nanoparticles potentially ameliorate lipid-mediated disorders more effectively than apoA-I:POPC nanodiscs. Abstract High density lipoprotein (HDL) is prone to modification by the oxidizing and chlorinating agent hypochlorite anion (OCl−). Oxidation of apolipoprotein (apo) A-I, the major protein in HDL, reduces ABCA-1 mediated cholesterol efflux and other protective responses to HDL. The apoA-I mimetic peptide 4F has been shown to undergo oxidation; however, the ability of the peptide to mediate cholesterol efflux remains intact. Here, we show that 4F protects apoA-I from hypochlorite-mediated oxidation. Mass spectral analysis of apoA-I shows that tyrosine residues that are prone to hypochlorite-mediated chlorination are protected in the presence of 4F. Furthermore, 4F enhances the cholesterol efflux ability of apoA-I to a greater extent than either 4F or apoA-I alone, even after hypochlorite oxidation. These observations suggest that apoA-I in lipid complexes may be protected by the presence of 4F, resulting in the preservation of its anti-inflammatory and anti-atherogenic properties. These studies also form the basis for the future studies of nanoparticles possessing both apoA-I and 4F. [ABSTRACT FROM AUTHOR]

ABCA1, ABCG1 transporters, and SR-B1 receptor are the major proteins involved in cholesterol efflux from cells. We superposed in silico the location of putative cholesterol (Chol)-binding motifs CRAC/CARC and CCM in human ABCA1, ABCG1, and SR-B1 with (1) transmembrane protein topology, (2) a profile of structural order of protein, and (3) with an influence of single amino acid substitutions on protein structure and function. ABCA1, ABCG1, and SR-B1 molecules contain 50, 19, and 13 Chol-binding motifs, respectively, that are localized either in membrane helices, or at membrane-water interface, or in water-exposed protein regions. Arginine residues in motifs that coincide with molecular recognition features within intrinsically disordered regions of the transporters are suggested to be important in cholesterol binding; cholesterol-arginine interaction may result in the induction of local order in protein structure. Chol-binding motifs in membrane helices may immobilize cholesterol, while motifs at membrane-water interface may be involved into the efflux of "active" cholesterol. Cholesterol may interfere with ATP binding in both nucleotide-binding domains of ABCA1 structure. For ABCA1 and ABCG1, but not for SR-B1, the presence of mirror code as a CARC-CRAC vector couple in the C-terminal helices controlling protein-cholesterol interactions in the outer and inner membrane leaflets was evidenced. We propose the role of Chol-binding motifs with different immersion in membrane in transport of different cholesterol pools by ABCA1 and ABCG1. [ABSTRACT FROM AUTHOR]

The heterogeneity and content of human plasma high‐density lipoprotein (HDL) related to their atheroprotective properties determined by various molecular and cellular mechanisms still remain to be completely clarified. For 29 atherosclerosis‐free male subjects, we studied the relationship of plasma lipid levels and the content of apolipoprotein A‐I (apoA‐I)‐containing HDL with preβ‐electrophoretic mobility, the efficiency of BODIPY‐cholesterol efflux from RAW 264.7 macrophages to apolipoprotein B (apoB)‐deficient plasma, and the expression level of 22 genes related to HDL metabolism in mononuclear cells. A significant decrease in the absolute content of apoA‐I in preβ‐HDL was found in subjects with hypoalphalipoproteinemia compared with the subjects with hyperalphalipoproteinemia. The preβ‐to‐α‐ratio of the apoA‐I content was constant within the HDL‐cholesterol (HDL‐C) range 0.59 to 2.24 mM. However, this ratio was significantly increased with an increase in the plasma triacylglycerol (TAG) content from 0.59 to 3.42 mM. A correlation of the level of preβ‐HDL with the basal and ABCA1‐mediated efflux of cholesterol is shown. The transcript levels for six HDL‐metabolizing genes (LDLR, LCAT, ABCA1, SCARB1, ZDHHC8, and BMP1) were decreased, while the transcript level of APOA1 gene was increased in mononuclear cells of subjects with hyperalphalipoproteinemia as compared with subjects with hypoalphalipoproteinemia. A reduction of the intracellular cholesterol level and inhibition of the expression of cholesterol transporters by nascent HDL in mononuclear cells from subjects with hyperalphalipoproteinemia are suggested. Hyperalphalipoproteinemia can be a driving force of the decreased flux of cholesteryl ester to the liver and the increased TAG hydrolysis. The atheroprotective effect of preβ‐HDL in hypertriglyceridemia is proposed. [ABSTRACT FROM AUTHOR]

Prolonged hyperglycemia in poorly controlled diabetes leads to an increase in reactive glucose metabolites that covalently modify proteins by non-enzymatic glycation reactions. Apolipoprotein A-I (apoA-I) of high-density lipoprotein (HDL) is one of the proteins that becomes glycated in hyperglycemia. The impact of glycation on apoA-I protein structure and function in lipid and glucose metabolism were investigated. ApoA-I was chemically glycated by two different glucose metabolites (methylglyoxal and glycolaldehyde). Synchrotron radiation and conventional circular dichroism spectroscopy were used to study apoA-I structure and stability. The ability to bind lipids was measured by lipid-clearance assay and native gel analysis, and cholesterol efflux was measured by using lipid-laden J774 macrophages. Diet induced obese mice with established insulin resistance, L6 rat and C2C12 mouse myocytes, as well as INS-1E rat insulinoma cells, were used to determine in vivo and in vitro glucose uptake and insulin secretion. Site-specific, covalent modifications of apoA-I (lysines or arginines) led to altered protein structure, reduced lipid binding capability and a reduced ability to catalyze cholesterol efflux from macrophages, partly in a modification-specific manner. The stimulatory effects of apoA-I on the in vivo glucose clearance were negatively affected when apoA-I was modified with methylglyoxal, but not with glycolaldehyde. The in vitro data showed that both glucose uptake in muscle cells and insulin secretion from beta cells were affected. Taken together, glycation modifications impair the apoA-I protein functionality in lipid and glucose metabolism, which is expected to have implications for diabetes patients with poorly controlled blood glucose. [ABSTRACT FROM AUTHOR]

Specific mutations in APOA1 gene lead to systemic, hereditary amyloidoses. In ApoA-I related amyloidosis involving the heart, amyloid deposits are mainly constituted by the 93-residue N-terminal region of the protein, here indicated as [1-93]ApoA-I. Oxidative stress is known to be an enhancing factor for protein aggregation. In healthy conditions, humans are able to counteract the formation and the effects of oxidative molecules. However, aging and atmospheric pollution increase the concentration of oxidative agents, such as metal ions. As the main effect of iron deregulation is proposed to be an increase in oxidative stress, we analysed the effects of iron on [1-93]ApoA-I aggregation. By using different biochemical approaches, we demonstrated that Fe(II) is able to reduce the formation of [1-93]ApoA-I fibrillar species, probably by stabilizing its monomeric form, whereas Fe(III) shows a positive effect on polypeptide fibrillogenesis. We hypothesize that, in healthy conditions, Fe(III) is reduced by the organism to Fe(II), thus inhibiting amyloid formation, whereas during ageing such protective mechanisms decline, thus exposing the organism to higher oxidative stress levels, which are also related to an increase in Fe(III). This alteration could contribute to the pathogenesis of amyloidosis. [ABSTRACT FROM AUTHOR]

There has been no information about the correlations between body weight distribution and lipoprotein metabolism in terms of high-density lipoproteins-cholesterol (HDL-C) and cholesteryl ester transfer protein (CETP). In this study, we analyzed the quantity and quality of HDL correlations in young women (21.5 ± 1.2-years-old) with a slim (n = 21, 46.2 ± 3.8 kg) or plump (n = 30, 54.6 ± 4.4 kg) body weight. Body weight was inversely correlated with the percentage of HDL-C in total cholesterol (TC). The plump group showed 40% higher body fat (26 ± 3 %) and 86% more visceral fat mass (VFM, 1.3 ± 0.3 kg) than the slim group, which showed 18 ± 2% body fat and 0.7 ± 0.2 kg of VFM. Additionally, the plump group showed 20% higher TC, 58% higher triglyceride (TG), and 12% lower HDL-C levels in serum. The slim group showed 34% higher apoA-I but 15% lower CETP content in serum compared to the plump group. The slim group showed a 13% increase in particle size and 1.9-fold increase in particle number with enhanced cholesterol efflux activity. Although the plump group was within a normal body mass index (BMI) range, its lipid profile and lipoprotein properties were distinctly different from those of the slim group in terms of CETP mass and activity, HDL functionality, and HDL particle size. [ABSTRACT FROM AUTHOR]

High-density lipoproteins augment hypoxia-induced angiogenesis by inducing the key angiogenic vascular endothelial growth factor A (VEGFA) and total protein levels of its receptor 2 (VEGFR2). The activation/phosphorylation of VEGFR2 is critical for mediating downstream, angiogenic signaling events. This study aimed to determine whether reconstituted high-density lipoprotein (rHDL) activates VEGFR2 phosphorylation and the downstream signaling events and the importance of VEGFR2 in the proangiogenic effects of rHDL in hypoxia. In vitro, rHDL increased VEGFR2 activation and enhanced phosphorylation of downstream, angiogenic signaling proteins ERK1/2 and p38 MAPK in hypoxia. Incubation with a VEGFR2-neutralizing antibody attenuated rHDL-induced phosphorylation of VEGFR2, ERK1/2, p38 MAPK, and tubule formation. In a murine model of ischemia-driven neovascularization, rHDL infusions enhanced blood perfusion and augmented capillary and arteriolar density. Infusion of a VEGFR2-neutralizing antibody ablated those proangiogenic effects of rHDL. Circulating Sca1+/CXCR4+ angiogenic progenitor cell levels, important for neovascularization in response to ischemia, were higher in rHDL-infused mice 3 d after ischemic induction, but that did not occur in mice that also received the VEGFR2-neutralizing antibody. In summary, VEGFR2 has a key role in the proangiogenic effects of rHDL in hypoxia/ischemia. These findings have therapeutic implications for angiogenic diseases associated with an impaired response to tissue ischemia. [ABSTRACT FROM AUTHOR]

Coronary artery disease, the leading cause of death in the developed and developing countries, is prevalent in diabetes mellitus with 68% cardiovascular disease (CVD)-related mortality. Epidemiological studies suggested inverse correlation between HDL and CVD occurrence. Therefore, low HDL concentration observed in diabetic patients compared to non-diabetic individuals was thought to be one of the primary causes of increased risks of CVD. Efforts to raise HDL level via CETP inhibitors, Torcetrapib and Dalcetrapib, turned out to be disappointing in outcome studies despite substantial increases in HDL-C, suggesting that factors beyond HDL concentration may be responsible for the increased risks of CVD. Therefore, recent studies have focused more on HDL function than on HDL levels. The metabolic environment in diabetes mellitus condition such as hyperglycemia-induced advanced glycation end products, oxidative stress, and inflammation promote HDL dysfunction leading to greater risks of CVD. This review discusses dysfunctional HDL as one of the mechanisms of increased CVD risks in diabetes mellitus through adversely affecting components that support HDL function in cholesterol efflux and LDL oxidation. The dampening of reverse cholesterol transport, a key process that removes cholesterol from lipid-laden macrophages in the arterial wall, leads to increased risks of CVD in diabetic patients. Therapeutic approaches to keep diabetes under control may benefit patients from developing CVD. [ABSTRACT FROM AUTHOR]

Apolipoprotein A-I (ApoA-I) is a lipoprotein involved in a variety of physiological and pathological processes. However, the immunomodulatory functions of ApoA-I in fish are not well understood. In this study, ApoA-I from Nile tilapia (Oreochromis niloticus) (On-ApoA-I) was identified, and its function in bacterial infection was investigated. The open reading frame of On-ApoA-I is 792 bp, which codes for a protein containing 263 amino acids. On-ApoA-I shared over 60% sequence similarity with other teleost fish and more than 20% with mammalian ApoA-I. On-ApoA-I was found to be highly expressed in the liver and significantly induced during Streptococcus agalactiae infection by qRT‒PCR analysis. Furthermore, in vivo studies revealed that recombinant On-ApoA-I protein could suppress inflammation and apoptosis and improve the likelihood of surviving bacterial infection. Additionally, On-ApoA-I showed in vitro antimicrobial properties against Gram-positive and Gram-negative bacteria. These findings offer a theoretical basis for further investigations into the role of ApoA-I in fish immunology. • Apolipoprotein A-I (ApoA-I) was identified from Nile Tilapia (Oreochromis niloticus). • ApoA-I was induced during bacterial infection. • ApoA-I protects tilapia against S. agalactiae infection in vivo. [ABSTRACT FROM AUTHOR]

Genetic studies have linked age-related macular degeneration (AMD) to genes involved in high-density lipoprotein (HDL) metabolism, including ATP-binding cassette transporter A1 ( ABCA1 ). The retinal pigment epithelium (RPE) handles large amounts of lipids, among others cholesterol, partially derived from internalized photoreceptor outer segments (OS) and lipids physiologically accumulate in the aging eye. To analyze the potential function of ABCA1 in the eye, we measured cholesterol efflux, the first step of HDL generation, in RPE cells. We show the expression of selected genes related to HDL metabolism in mouse and human eyecups as well as in ARPE-19 and human primary RPE cells. Immunofluorescence staining revealed localization of ABCA1 on both sides of polarized RPE cells. This was functionally confirmed by directional efflux to apolipoprotein AI (ApoA-I) of 3 H-labeled cholesterol given to the cells via serum or via OS. ABCA1 expression and activity was modulated using a liver-X-receptor (LXR) agonist and an ABCA1 neutralizing antibody, demonstrating that the efflux was ABCA1-dependent. We concluded that the ABCA1-mediated lipid efflux pathway, and hence HDL biosynthesis, is functional in RPE cells towards both the basal (choroidal) and apical (subretinal) space. Impaired activity of the pathway might cause age-related perturbations of lipid homeostasis in the outer retina and thus may contribute to disease development and/or progression. [ABSTRACT FROM AUTHOR]

Beyond the crucial role of apolipoprotein A-I (ApoA-I) on peripheral cholesterol metabolism, this apolipoprotein has also been implicated in beta amyloid (Aβ)–related neuropathologies. ApoA-I-Milano (M) is a mutated variant, which showed increased vasoprotective properties compared to ApoA-I-wild type in models of atherosclerosis and cardiovascular damage. We speculated that ApoA-I-M may also protect Aβ-affected vasculature and reverse some of the pathological features associated with Alzheimer's disease (AD). For this purpose, we produced and characterized human recombinant ApoA-I-wild type and ApoA-I-M proteins. Both of them were able to avoid the aggregation of Aβ in vitro, even though recombinant ApoA-I-M was significantly more effective in protecting endothelial cells from Aβ(1–42)-toxicity. Next, we determined the effect of chronic intravenous administration of rApoA-I-M in the APP23-transgenic mouse model of AD. We found reduced cerebral Aβ levels in mice that received rApoA-I-M, which were accompanied by a lower expression of astrocyte and microglia neuroinflammatory markers. Our results suggest an applicability of this molecule as a therapeutic candidate for protecting the brain in AD. [ABSTRACT FROM AUTHOR]

Background: We recently reported distinct nature of high-density lipoproteins (HDL) subgroup particles with apolipoprotein (apo) A-I but not apoA-II (LpAI) and HDL having both (LpAI:AII) based on the data from 314 Japanese. While plasma HDL level almost exclusively depends on concentration of LpAI having 3 to 4 apoA-I molecules, LpAI:AII appeared with almost constant concentration regardless of plasma HDL levels having stable structure with two apoA-I and one disulfide-dimeric apoA-II molecules (Sci. Rep. 6; 31,532, 2016). The aim of this study is further characterization of LpAI:AII with respect to its role in atherogenesis. Methods: Association of LpAI, LpAI:AII and other HDL parameters with apoB-lipoprotein parameters was analyzed among the cohort data above. Results: ApoA-I in LpAI negatively correlated with the apoB-lipoprotein parameters such as apoB, triglyceride, nonHDL-cholesterol, and nonHDL-cholesterol + triglyceride, which are apparently reflected in the relations of the total HDL parameters to apoB-lipoproteins. In contrast, apoA-I in LpAI:AII and apoA-II positively correlated to the apoB-lipoprotein parameters even within their small range of variation. These relationships are independent of sex, but may slightly be influenced by the activity-related CETP mutations. Conclusions: The study suggested that LpAI:AII is an atherogenic indicator rather than antiatherogenic. These sub-fractions of HDL are to be evaluated separately for estimating atherogenic risk of the patients. [ABSTRACT FROM AUTHOR]

The human cathelicidin peptide LL-37 has antimicrobial and anti-biofilm functions, but LL-37 may also damage the host by triggering inflammation and exerting a cytotoxic effect, thereby reducing host cell viability. Human plasma mitigates LL-37-induced host cell cytotoxicity but the underlying mechanisms are not completely understood. Apolipoprotein A-I (ApoA-I) is a plasma protein endowed with atheroprotective effects. Here, we investigate the interaction between ApoA-I and LL-37 by biochemical techniques, and furthermore assess if ApoA-I protects against LL-37-evoked cytotoxicity in human umbilical vein endothelial cells (HUVEC). Our results demonstrated that ApoA-I effectively binds LL-37. The binding of ApoA-I to LL-37 resulted in a structural rearrangement of the protein, but this interaction did not cause lower ApoA-I stability. Recombinant ApoA-I protected against LL-37-induced cytotoxicity in HUVEC and endogenous ApoA-I knockdown in HepG2 cells made the cells more sensitive to LL-37-evoked cytotoxicity. We conclude that ApoA-I physically interacts with LL-37 and antagonizes LL-37-induced down-regulation of endothelial cell viability suggesting that this mechanism counteracts endothelial cell dysfunction. [ABSTRACT FROM AUTHOR]