High-density Lipoprotein Protein Research Articles

Metabolic labeling unveils alterations in the turnover of HDL-associated proteins during diabetes progression in mice.

Several aspects of diabetes pathophysiology and complications result from hyperglycemia-induced alterations in the structure and function of plasma proteins. Furthermore, insulin has a significant influence on protein metabolism by affecting both the synthesis and degradation of proteins in various tissues. To understand the role of progressive hyperglycemia on plasma proteins, in this study, we measured the turnover rates of high-density lipoprotein (HDL)-associated proteins in control (chow diet), prediabetic [a high-fat diet (HFD) for 8 wk] or diabetic [HFD for 8 wk with low-dose streptozotocin (HFD + STZ) in weeks 5-8 of HFD] C57BL/6J mice using heavy water (2H2O)-based metabolic labeling approach. Compared with control mice, HFD and HFD + STZ mice showed elevations of fasting plasma glucose levels in the prediabetic and diabetic range, respectively. Furthermore, the HFD and HFD + STZ mice showed increased hepatic triglyceride (TG) levels, total plasma cholesterol, and plasma TGs. The kinetics of 40 proteins were quantified using the proteome dynamics method, which revealed an increase in the fractional synthesis rate (FSR) of HDL-associated proteins in the prediabetic mice compared with control mice, and a decrease in FSR in the diabetic mice. The pathway analysis revealed that proteins with altered turnover rates were involved in acute-phase response, lipid metabolism, and coagulation. In conclusion, prediabetes and diabetes have distinct effects on the turnover rates of HDL proteins. These findings suggest that an early dysregulation of the HDL proteome dynamics can provide mechanistic insights into the changes in protein levels in these conditions.NEW & NOTEWORTHY This study is the first to examine the role of gradual hyperglycemia during diabetes disease progression on HDL-associated protein dynamics in the prediabetes and diabetic mice. Our results show that the fractional synthesis rate of HDL-associated proteins increased in the prediabetic mice whereas it decreased in the diabetic mice compared with control mice. These kinetic changes can help to elucidate the mechanism of altered protein levels and HDL dysfunction during diabetes disease progression.

Associations of HDL subclasses and lipid content with complement proteins over the menopause transition: The SWAN HDL ancillary study: HDL and complement proteins in women

The menopause transition (MT) could trigger low-grade chronic inflammation which may modify high-density lipoproteins (HDL) and lead to additional inflammatory responses contributing to atherosclerosis development. To test whether complement proteins C3 and C4 increase around the final menstrual period (FMP), and whether changes in HDL subclasses and lipid content associate with C3 and C4 levels over time in midlife women. The study included 471 women (at baseline: age 50.2(2.7) years; 87.3% pre or peri-menopausal) who had nuclear magnetic resonance spectroscopy HDL subclasses, lipid content, and C3 and C4 measured up to 5 times over the MT. Adjusted annual changes in C3 and C4 varied by time segments relative to FMP with significant increases, steeper for C3, only observed within 1 year before to 2 years after the FMP. Greater decreases in large HDL particles (HDL-P), HDL size, and HDL-phospholipids, and greater increases in small HDL-P and HDL-Triglycerides were associated with higher C3 and C4 over time, although associations with C4 were weaker than those with C3. Complement proteins C3 and C4 significantly rise around menopause with C3 showing the steepest rise. Changes in HDL subclasses, overall size, and lipid content, over the MT may play a role in modulating inflammation responses known to be related to atherosclerosis. These results raise the possibility that novel therapeutic agents focusing on HDL might contribute to CVD protection by modulating inflammation.

Abstract 498: HDL Containing Specific Proteins Blunts The Association With Cholesterol Efflux Capacity: Observations From The Dallas Heart Study

Cholesterol efflux (CE) is a major athero-protective function of high density lipoproteins (HDL). HDL is a heterogeneous mixture of lipoproteins that contain apoA1, the prime protein of HDL, and may contain one or more of >200 other proteins. These other proteins cluster on subpopulations of HDL particles to form HDL subspecies. It is not entirely clear by simply measuring individual protein abundances what drives HDL function. We aimed to study the differential association of 7 HDL subspecies defined by presence or absence of a functional protein with extreme and persistent cholesterol efflux capacity (CEC). From ~3000 individuals in the multi-ethnic population-based DHS (Dallas Heart Study) cohort, people at the bottom 10% and top 90% of CEC were reassessed after 15 years resulting in 36 participants with extreme persistent high or low CEC for the present study. HDL with and without 7 individual proteins potentially relevant to HDL function were quantified using ELISA. Differences in association with CEC between HDL subspecies that contain or lack a defining protein were examined by heterogeneity test. In the low CEC group, HDL lacking apolipoprotein C3 (apoC3), complement C3, apoE (apolipoprotein E) and PLMG (plasminogen) were each associated positively with CEC while HDL subspecies containing these proteins were not positively associated with CEC. (Pearson correlation coefficient range 0.55369 to 0.66562 vs -0.08432 to -0.25198; p <0.05 for heterogeneity). In the high CEC group, no significant heterogeneity was found in association with CEC between HDL subspecies that contain or lack the same proteins. In people with extreme and persistent low CEC, HDL subspecies containing apoC3, complement C3, apoE and PLMG blunt the overall positive association between HDL and CEC. Our findings suggest that CEC of HDL in individuals with persistent and extreme low CEC is determined by the presence/absence of apoC3, complement C3, apoE and PLMG in HDL subspecies. Future studies involving manipulation of these proteins in HDL to investigate the effect on CE will provide deeper insight into functional speciation of HDL. This knowledge can be further applied to define biomarkers for altered CE in atherosclerotic cardiovascular diseases (ASCVD).

Pathophysiology of Venous Thromboembolism: Putative role of HDL

IntroductionIn 2019, cardiovascular disease (CVD) was the main reason of all global deaths (32%) and out of these deaths, 85% were due to heart attack and stroke alone. Venous thromboembolism (VTE), which is the third leading cause of CVD, has a very high incidence rate in Indian Population. Data suggest that thromboembolic disorders are due to multiple genetic and environmental variables and hence considered as a complex multifactorial trait. High Density Lipoprotein (HDL) has attracted a great deal of interest in recent years because of its implications in the prevention of various CVD. Various data suggests the relation between HDL and the expression of coagulation/fibrinolytic factors among the patients of CVD. Protein content of HDL is largely responsible for antioxidant mechanism by metabolizing lipid hydro peroxides and preventing their accumulation. Association of venous thrombosis and dyslipidemia has been investigated in several clinical studies, but results are inconsistent. Therefore, we sought to identify the role of HDL in pathophysiology of VTE in both human and animal studies.MethodologyDVT was detected in male patients using color Doppler followed by D‐Dimer and Prothrombin Fragment 1+2 (PF1+2) levels to confirm thrombus formation. HDL associated proteins, endothelial adhesion molecules, thrombotic molecules, inflammatory molecules and oxidized lipoprotein levels were measured. For animal study, a complete stasis animal model was standardized to generate thrombus formation in the SD rats. Thrombus length/weight was measured along with D‐Dimer & PF 1+2 levels. HDL was isolated from plasma and was used in kinetic reaction of LDL oxidation. Progression of LDL oxidation was measured through DCFH‐method. All experimental procedures were performed in accordance to ethical guidelines.Major FindingsA well written consent was taken from all the participants before conducting human study. High levels of D‐Dimer and PF 1+2 in DVT patients as well as IVC ligated group confirmed thrombosis. HDL associated molecules were found to be significantly lower, whereas adhesion molecules, inflammatory molecules, and thrombotic molecules were significantly higher in both DVT patients and IVC ligated group. Oxidized lipoproteins and the lipooxygenase enzymes responsible for lipoprotein oxidation were found significantly higher. Isolated HDL used in LDL oxidation kinetics reaction found to be non‐functional in preventing LDL oxidation. P‐value of <0.05 was used as significance for all the tests.Conclusion & DiscussionLow levels of HDL proteins along with high levels of adhesion molecules, thrombotic markers and inflammatory molecules indicate the suppression of HDL activity. High lipooxygenase enzymes and oxidized lipoprotein levels support the hypothesis of dysfunctional HDL. HDL isolated from the ligated group was unable to prevent the LDL oxidation which clarifies that HDL loses its functionality in case of VTE. Furthermore, finding of this study will also help in understanding the pathophysiology of VTE which might give an insight in prevention/early diagnosis of the disease.

Anti Diabetic Activity of Methanolic and Chloroform Extracts of Solanum seaforthianum In Alloxan Induced Diabetes Rats

Diabetes mellitus is a syndrome characterized by elevated glucose levels, polyurea, polydipsia and weakness due to insufficient entry of available glucose into the cells of the body. There are many allopathic drugs available to manage diabetes such as Sulfonylureas, biguanides, gliptins etc., but associated with hypoglycemia, sweating, dizziness, confusion, hunger, weight gain on long term usage and tolerance will be developed which are further treated using multiple drugs. According to our ancient system of medicine there are many medicinal plants available to treat diabetes with the same potency of allopathic drugs. Natural products are considered to be an effective alternative for the treatment and management of diabetes, because of higher efficacy which initiated the present study of anti diabetic activity of Solanum seaforthianum in an alloxan induced diabetes male albino rat. Diabetes was successfully induced with the help of alloxan at a dose of 120 mg/kg body weight and the animals which are possessing the glucose levels more than 250 mg/dL included in the study. Diabetic induced rats were treated with methanolic and chloroform extracts (200 and 400 mg/kg/kg body weight) of Solanum seaforthianum for 10 days. The collected blood samples on 1st, 4th, 7th, and 10th day were used to determine serum biochemical parameters such as cholesterol, triglycerides, low-density lipoprotein (LDL), high-density lipoprotein (HDL) cholesterol, urea, creatinine and total protein. Results: The treatment with extracts of Solanum seaforthianum significantly reduced the elevated blood glucose levels and reversed other altered parameters of Cholesterol, Triglycerides, HDL, LDL, Urea, Creatinine and Total Protein. Among the two extracts of Solanum seaforthianum chloroform extract has shown comparatively significant (p<0.001) anti diabetic activity in alloxan induced diabetes in albino rats.
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Longitudinal Analysis of the Effect of an Acute Coronary Syndrome on the Proteome of High-Density Lipoprotein

The vasoprotective functions of high density-lipoproteins (HDLs) are lost in patients following an acute coronary syndrome (ACS). The changes in HDL proteins that may be responsible for this loss of function were evaluated longitudinally.

Effects of Dietary Catechin Uncaria gambir Extract on Growth Performance, Carcass Characteristics, Plasma Lipids, Antioxidant Activity and Nutrient Digestibility in Broiler Chickens

This study aimed to determine the effect of adding catechin gambir extract (Uncaria gambir Roxb) (CGE) on growth performance, carcass characteristics, blood plasma constituents, antioxidant activity, and nutrient digestibility in broiler chickens. 160 chicks were allocated to receive four treatment diets adding CGE was 0, 0.1, 0.2, and 0.3g/kg in basal diets with four replications. Bodyweight and feed intake were recorded to calculate growth performance. Digestibility measurements were carried out at the age of 31-40 days, and at 40 days, blood samples were taken to determine the total protein levels of cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL), and Malondialdehyde (MDA). Then these chickens are slaughtered to determine the percentage of viscera and muscles. Adding CGE to basal diets linearly (P<0.05) increased body weight gain and improved the feed conversion ratio of broiler grower, finisher, and the overall age of 1-40 days. The effect of GCE on carcass characteristics significantly (P<0.05) increased the percentage of thigh and drumstick and decreased abdominal fat. CGE linearly reduced total cholesterol and LDL while increased HDL and total protein in blood plasma. The MDA concentration linearly decreased in serum and broiler meat aged 40 days. In addition, CGE increased (P<0.05) the digestibility of crude protein and decreased fat digestibility in the diet. Adding 0.3g/kg CGE to the basal diet can be a feed additive to produce better performance and broiler meat.

Sodium salicylate rewires hepatic metabolic pathways in obesity and attenuates IL-1β secretion from adipose tissue: The implications for obesity-impaired reverse cholesterol transport

IntroductionHigh-fat diet (HFD)-induced obesity impairs clearance of cholesterol through the Reverse Cholesterol Transport (RCT) pathway, with downregulation in hepatic expression of cholesterol and bile acid transporters, namely ABCG5/8 and ABCB11, and reduced high-density lipoprotein (HDL) cholesterol efflux capacity (CEC). In the current study, we hypothesized that the development of hepatosteatosis, secondary to adipose-tissue dysfunction, contributes to obesity-impaired RCT and that such effects could be mitigated using the anti-inflammatory drug sodium salicylate (NaS). Materials and methodsC57BL/6J mice, fed HFD ± NaS or low-fat diet (LFD) for 24 weeks, underwent glucose and insulin tolerance testing. The 3H-cholesterol movement from macrophage-to-feces was assessed in vivo. HDL-CEC was determined ex vivo. Cytokine secretion from adipose-derived stromal vascular fraction (SVF) cells was measured ex vivo. Liver and HDL proteins were determined by mass spectrometry and analyzed using Ingenuity Pathway Analysis. ResultsNaS delayed HFD-induced weight gain, abrogated priming of pro-IL-1β in SVFs, attenuated insulin resistance, and prevented steatohepatitis (ectopic fat accumulation in the liver). Prevention of hepatosteatosis coincided with increased expression of PPAR-alpha/beta-oxidation proteins with NaS and reduced expression of LXR/RXR-induced proteins including apolipoproteins. The latter effects were mirrored within the HDL proteome in circulation. Despite remarkable protection shown against steatosis, HFD-induced hypercholesterolemia and repression of the liver-to-bile cholesterol transporter, ABCG5/8, could not be rescued with NaS. Discussions and conclusionsThe cardiometabolic health benefits of NaS may be attributed to the reprogramming of hepatic metabolic pathways to increase fatty acid utilization in the settings of nutritional overabundance. Reduced hepatic cholesterol levels, coupled with reduced LXR/RXR-induced proteins, may underlie the lack of rescue of ABCG5/8 expression with NaS. This remarkable protection against HFD-induced hepatosteatosis did not translate to improvements in cholesterol homeostasis.

CRISPR/dCas9 Transcriptional Activation of Endogenous Apolipoprotein AI and Paraoxonase 1 in Enterocytes Alleviates Endothelial Cell Dysfunction

Atherosclerosis is the main cause of cardiovascular diseases with high prevalence worldwide. A promising therapeutic strategy to reverse atherosclerotic process is to improve the athero-protective potential of high-density lipoproteins (HDL). Since the small intestine is a source of HDL, we aimed to activate transcription of the endogenous HDL major proteins, apolipoprotein AI (ApoAI) and paraoxonase 1 (PON1), in enterocytes, and to evaluate their potential to correct the pro-inflammatory status of endothelial cells (EC). Caco-2 enterocytes were transfected with CRISPR activation plasmids targeting ApoAI or PON1, and their gene and protein expression were measured in cells and conditioned medium (CM). ATP binding cassette A1 and G8 transporters (ABCA1, ABCG8), scavenger receptor BI (SR-BI), and transcription regulators peroxisome proliferator-activated receptor γ (PPARγ), liver X receptors (LXRs), and sirtuin-1 (SIRT1) were assessed. Anti-inflammatory effects of CM from transfected enterocytes were estimated through its ability to inhibit tumor necrosis factor α (TNFα) activation of EC. Transcriptional activation of ApoAI or PON1 in enterocytes induces: (i) increase of their gene and protein expression, and secretion in CM; (ii) stimulation of ABCA1/G8 and SR-BI; (iii) upregulation of PPARγ, LXRs, and SIRT1. CM from transfected enterocytes attenuated the TNFα-induced inflammatory and oxidative stress in EC, by decreasing TNF receptor 1, monocyte chemoattractant protein-1, and p22phox. In conclusion, transcriptional activation of endogenous ApoAI or PON1 in enterocytes by CRISPR/dCas9 system is a realistic approach to stimulate biogenesis and function of major HDL proteins which can regulate cholesterol efflux transporters and reduce the inflammatory stress in activated EC.

Lipid-Based Nutrient Supplementation Increases High-Density Lipoprotein (HDL) Cholesterol Efflux Capacity and Is Associated with Changes in the HDL Glycoproteome in Children.

Prenatal plus postnatal small-quantity lipid-based nutrient supplements (SQ-LNS) improved child growth at 18 months in the International Lipid-Based Nutrient Supplements DYAD trial in Ghana. In this secondary outcome analysis, we determined whether SQ-LNS versus prenatal iron and folic acid (IFA) supplementation improves the cholesterol efflux capacity (CEC) of high-density lipoprotein (HDL) particles and alters their lipidomic, proteomic, or glycoproteomic composition in a subset of 80 children at 18 months of age. HDL CEC was higher among children in the SQ-LNS versus IFA group (20.9 ± 4.1 vs 19.4 ± 3.3%; one-tailed p = 0.038). There were no differences in HDL lipidomic or proteomic composition between groups. Twelve glycopeptides out of the 163 analyzed were significantly altered by SQ-LNS, but none of the group differences remained significant after correction for multiple testing. Exploratory analysis showed that 6 out of the 33 HDL-associated proteins monitored differed in glycopeptide enrichment between intervention groups, and 6 out of the 163 glycopeptides were correlated with CEC. We conclude that prenatal plus postnatal SQ-LNS may modify HDL protein glycoprofiles and improve the CEC of HDL particles in children, which may have implications for subsequent child health outcomes. This trial was registered at clinicaltrials.gov as NCT00970866.

Effects of curcumol on liver function and fibrosis in rats of nonalcoholic fatty liver disease and its mechanism

Objective: To investigate the effects and mechanism of curcumol (CC) on liver function and fibrosis in rats of nonalcoholic fatty liver disease (NAFLD). Methods: The rat models of nonalcoholic steatohepatitis (NASH) combined with liver fibrosis were constructed by high-fat diet. Sixty SD rats were randomly divided into blank control group, model group (NASH), NASH + Compound Biejiarangan Troche (CBT) group (positive control group), and NASH + CC groups (25, 50, 100 mg/kg) , 10 rats in each group. The percentage of liver to body weight, and the levels of high density lipoprotein (HDL), triglyceride (TG), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured. The liver fibrosis was observed by HE staining. The expressions of α-smooth muscle actin (α-SMA) and positive staining of nuclear factor κB p65 (NF-κB p65) were detected by immunohistochemistry. The expression levels of α-SMA, matrix metalloproteinase-1 (MMP-1), tissue inhibitor of metalloproteinase-1 (TIMP-1) and toll-like receptor-4 (TLR4), transforming growth factor-activated kinase-1 (TAK1), NF-κB p65 and vascular cell adhesion molecule-1 (VCAM-1) were detected by Western blot. The expression levels of interleukin (IL-6, IL-10, IL-1β) and tumor necrosis factor-α (TNF-α) were detected by enzyme linked immunosorbent assay (ELISA). Results: Compared with blank control group, the contents of HDL and IL-10 and the expression level of MMP-1 protein were decreased in model group significantly (P＜0.05), while the levels of TG, ALT and AST, the positive rate of P65, α-SMA, TIMP-1, TLR4, TAK1, NF-κB p65, VCAM-1, IL-6, TNF-α and IL-1β were increased significantly (P＜0.05). Compared with model group, the levels of HDL, IL-10 and MMP-1 protein were significantly increased after treatment with CBT and CC (P＜0.05), while the levels of TG, ALT, and AST, the positive rate of P65, α-SMA, TIMP-1, TLR4, TAK1, NF-κB p65, VCAM-1, IL-6, TNF-α and IL-1β were decreased significantly (P＜0.05). The improvement in model+high- concentration CC group was the most significant, and which in all concentration groups was lower than that in model+CBT group (P＜0.05). Conclusion: CC can reduce inflammation response and improve liver function by regulating TLR4, TAK1 and NF-κB/p65 signaling pathway, and thus alleviating liver fibrosis, showing concentration-dependence within certain range.

HDL proteome remodeling associates with COVID-19 severity

BackgroundBesides the well-accepted role in lipid metabolism, high-density lipoprotein (HDL) also seems to participate in host immune response against infectious diseases.Objective: We used a quantitative proteomic approach to test the hypothesis that alterations in HDL proteome associate with severity of Coronavirus disease 2019 (COVID-19).MethodsBased on clinical criteria, subjects (n=41) diagnosed with COVID-19 were divided into two groups: a group of subjects presenting mild symptoms and a second group displaying severe symptoms and requiring hospitalization. Using a proteomic approach, we quantified the levels of 29 proteins in HDL particles derived from these subjects.ResultsWe showed that the levels of serum amyloid A 1 and 2 (SAA1 and SAA2, respectively), pulmonary surfactant-associated protein B (SFTPB), apolipoprotein F (APOF), and inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4) were increased by more than 50% in hospitalized patients, independently of sex, HDL-C or triglycerides when comparing with subjects presenting only mild symptoms. Altered HDL proteins were able to classify COVID-19 subjects according to the severity of the disease (error rate 4.9%). Moreover, apolipoprotein M (APOM) in HDL was inversely associated with odds of death due to COVID-19 complications (odds ratio [OR] per 1-SD increase in APOM was 0.27, with 95% confidence interval [CI] of 0.07 to 0.72, P=0.007).ConclusionOur results point to a profound inflammatory remodeling of HDL proteome tracking with severity of COVID-19 infection. They also raise the possibility that HDL particles could play an important role in infectious diseases.

The Promise of Apolipoprotein AI-Based Therapy

Apolipoprotein A-I (ApoAI) is an anti-atherosclerotic protein that promotes cholesterol efflux from tissues to the liver for excretion [1]. ApoAI is the main structural and functional protein of High- Density Lipoproteins (HDL), representing ~70% of total HDL proteins [2,3]. Circulating apoAI protein is an amphipathic protein (28kDa) comprising eight alpha-helical domains of 22 amino acids and two repeats of 11 amino acids [4]. Consequently, ApoAI binds avidly to lipids and readily moves between lipoprotein particles; however, ~5-10% of human plasma ApoAI exists in a free state (lipoprotein-unbound) [5]. ApoAI protein is more than a structural scaffold that maintains lipid packaging, as it plays an important role in the transport of cellular cholesterol from the artery wall to the liver for catabolism [6-8]. Antioxidant and anti-inflammatory properties were also attributed to apoAI [9,10]. In addition, a protective role of apoAI against cancer was proposed [11]. ApoAI is synthesized mainly in the liver and small intestine and there are a lot of regulatory elements and transcription factors that control apoAI gene expression, as reviewed in [12]. Treatment with BPA (bisphenol A), one of the most widespread environmental chemicals, downregulates ApoAI gene expression, aggravating the atherosclerotic plaques in LDLR-/- mice [13]. Interestingly, the ratio of HDL-cholesterol to apoAI protein levels is an indicator of the risk of the cardiovascular disorder [14]. Lack of ApoAI augmented atherosclerosis in various hypercholesterolemic mice, such as mice expressing human apoB or ApoAI-/-/LDLR-/- mice [15,16]. In humans, familial ApoAI deficiency is associated with premature coronary heart disease [17]. Interestingly, low levels of apoAI and atherogenic dyslipidemia were found in obese individuals, but increases in apoAI levels and enhancements of cholesterol efflux capacity of HDL were reported at three months after bariatric surgery [18]. Considering the anti-atherogenic properties of apoAI, various apoAI-based therapies were proposed for reduction of atherogenesis: i) overexpression of ApoAI, ii) infusions of ApoAI protein, ApoAI mimetic peptides, or ApoAI-containing HDL [19-21], iii) oral small molecules that stimulate ApoAI production [22]. Overexpression of ApoAI reduced atherogenesis in apoE-/- or LDLR-/- atherosclerotic mice [23-31]. Infusions of ApoAI mimetic peptides led to the regression of aortic valve stenosis in rabbits [32]. Liver-directed adenoviral gene transfer of ApoAI resulted in the regression of preexisting atheroma in LDLR-/- mice [33]. Undoubtedly, local delivery of apoAI protein to the vascular wall represents a more efficient apoAIbased therapy than its systemic delivery. Remarkably, transduction of vascular endothelial cells with ApoAI expressing adenovirus reduced inflammation and protected against atherosclerosis in hyperlipidemic rabbits [34,35]. The oral drug RVX-208 significantly increased apoAI production in monkeys but presented disappointing efficacy in a phase II trial [36]. Notwithstanding there are good results obtained in studies using animal models, several apoAI-based clinical trials failed to regress atherosclerotic plaques in humans [37,38]. Despite tremendous advances regarding the understanding of apoAI, the promise of apoAI-based therapy awaits new studies and trials.

Malondialdehyde-modified HDL particles elicit a specific IgG response in abdominal aortic aneurysm

High Density Lipoprotein (HDL) plays a protective role in abdominal aortic aneurysm (AAA); however, recent findings suggest that oxidative modifications could lead to dysfunctional HDL in AAA. This study aimed at testing the effect of oxidized HDL on aortic lesions and humoral immune responses in a mouse model of AAA induced by elastase, and evaluating whether antibodies against modified HDL can be found in AAA patients.HDL particles were oxidized with malondialdehyde (HDL-MDA) and the changes were studied by biochemical and proteomics approaches. Experimental AAA was induced in mice by elastase perfusion and then mice were treated with HDL-MDA, HDL or vehicle for 14 days. Aortic lesions were studied by histomorphometric analysis. Levels of anti-HDL-MDA IgG antibodies were measured by an in-house immunoassay in the mouse model, in human tissue-supernatants and in plasma samples from the VIVA cohort.HDL oxidation with MDA was confirmed by enhanced susceptibility to diene formation. Proteomics demonstrated the presence of MDA adducts on Lysine residues of HDL proteins, mainly ApoA-I. MDA-modification of HDL abrogated the protective effect of HDL on cultured endothelial cells as well as on AAA dilation in mice. Exposure to HDL-MDA elicited an anti-HDL-MDA IgG response in mice. Anti-HDL-MDA were also detected in tissue-conditioned media from AAA patients, mainly in intraluminal thrombus. Higher plasma levels of anti-HDL-MDA IgG antibodies were found in AAA patients compared to controls. Anti-HDL-MDA levels were associated with smoking and were independent predictors of overall mortality in AAA patients. Overall, MDA-oxidized HDL trigger a specific humoral immune response in mice. Besides, antibodies against HDL-MDA can be detected in tissue and plasma of AAA patients, suggesting its potential use as surrogate stable biomarkers of oxidative stress in AAA.

High-Density Lipoproteins in Kidney Disease.

Decades of epidemiological studies have established the strong inverse relationship between high-density lipoprotein (HDL)-cholesterol concentration and cardiovascular disease. Recent evidence suggests that HDL particle functions, including anti-inflammatory and antioxidant functions, and cholesterol efflux capacity may be more strongly associated with cardiovascular disease protection than HDL cholesterol concentration. These HDL functions are also relevant in non-cardiovascular diseases, including acute and chronic kidney disease. This review examines our current understanding of the kidneys’ role in HDL metabolism and homeostasis, and the effect of kidney disease on HDL composition and functionality. Additionally, the roles of HDL particles, proteins, and small RNA cargo on kidney cell function and on the development and progression of both acute and chronic kidney disease are examined. The effect of HDL protein modification by reactive dicarbonyls, including malondialdehyde and isolevuglandin, which form adducts with apolipoprotein A-I and impair proper HDL function in kidney disease, is also explored. Finally, the potential to develop targeted therapies that increase HDL concentration or functionality to improve acute or chronic kidney disease outcomes is discussed.

Myeloperoxidase-induced modification of HDL by isolevuglandins inhibits paraoxonase-1 activity

Reduced activity of paraoxonase 1 (PON1), a high-density lipoprotein (HDL)-associated enzyme, has been implicated in the development of atherosclerosis. Post-translational modifications of PON1 may represent important mechanisms leading to reduced PON1 activity. Under atherosclerotic conditions, myeloperoxidase (MPO) is known to associate with HDL. MPO generates the oxidants hypochlorous acid and nitrogen dioxide, which can lead to post-translational modification of PON1, including tyrosine modifications that inhibit PON1 activity. Nitrogen dioxide also drives lipid peroxidation, leading to the formation of reactive lipid dicarbonyls such as malondialdehyde and isolevuglandins, which modify HDL and could inhibit PON1 activity. Because isolevuglandins are more reactive than malondialdehyde, we used in vitro models containing HDL, PON1, and MPO to test the hypothesis that IsoLG formation by MPO and its subsequent modification of HDL contributes to MPO-mediated reductions in PON1 activity. Incubation of MPO with HDL led to modification of HDL proteins, including PON1, by IsoLG. Incubation of HDL with IsoLG reduced PON1 lactonase and antiperoxidation activities. IsoLG modification of recombinant PON1 markedly inhibited its activity, while irreversible IsoLG modification of HDL before adding recombinant PON1 only slightly inhibited the ability of HDL to enhance the catalytic activity of recombinant PON1. Together, these studies support the notion that association of MPO with HDL leads to lower PON1 activity in part via IsoLG-mediated modification of PON1, so that IsoLG modification of PON1 could contribute to increased risk for atherosclerosis, and blocking this modification might prove beneficial to reduce atherosclerosis.

THE PROTEOME OF HIGH DENSITY LIPOPROTEIN CHANGES THROUGHOUT GESTATION IN HEALTHY PREGNANCY AND DIFFERS BETWEEN HEALTHY PREGNANCY AND PREECLAMPSIA IN THE THIRD TRIMESTER

Objective: High-density lipoprotein (HDL) has well-established anti-atherosclerotic properties in the non-pregnant population. HDL may have a potential role in protecting maternal vascular function during pregnancy that fails to occur in preeclampsia. HDL function is determined by its protein and lipid composition. This study aimed to examine protein composition of HDL at different gestations throughout healthy pregnancy and to compare HDL proteome in the third trimester of healthy pregnancy and preeclampsia. Design and method: HDL was isolated from two cohorts of n = 10 healthy pregnant women at 8 different timepoints throughout pregnancy; pre-pregnancy, week 4.6, week 6.1, week 8.4, (cohort 1) and week 15, week 25, week 35 and 3 months post-natal (cohort 2), and from healthy pregnant (n = 10) and preeclampsia (n = 6) women at the third trimester. The proteome of HDL was measured by nano liquid chromatography coupled to tandem mass spectrometry (nLC-MS/MS). Results: There were 16 proteins in HDL that showed significant differences throughout healthy pregnancy which were apolipoprotein A-IV, apolipoprotein C-II, apolipoprotein C-III, apolipoprotein C-IV, apolipoprotein F, apolipoprotein L-I, angiotensinogen, alpha-1-acid glycoprotein 2, alpha-1-antitrypsin, cathelicidin antimicrobial peptide, fibrinogen alpha chain, fibrinogen beta chain, prenylcysteine oxidase 1, serum amyloid a-I, serum paraoxonase/lactonase 3 and vitronectin. In preeclampsia, HDL apolipoprotein A-I was lower than healthy pregnancy, while HDL alpha-1-antitrypsin, pigment epithelium-derived factor and vitamin D-binding protein were higher. Conclusions: There were significant differences in the protein composition of HDL during pregnancy and between healthy pregnancy and preeclampsia in the third trimester. These compositional differences may be involved in HDL function and may indicate HDL's role in vascular protection in pregnancy.

Plasma high density lipoproteins phospholipds as an indirect indicator of their cholesterol efflux capacity — new suspected atherosclerosis risk factor

High density lipoproteins (HDL) are a unique natural structure, protecting the body from the development of atherosclerotic vascular lesions and cardiovascular diseases due to this ability to remove cholesterol from cells. Plasma HDL level estimated by their cholesterol content, is a common lipid parameter, and its decrease is considered as an established atherosclerosis risk factor. However, a number of studies have shown the absence of positive clinical effects after drug-induced increase in HDL cholesterol. There is increasing evidence that not only HDL concentration, but also HDL properties, considered in this review are important. Many studies showed the decrease of HDL cholesterol efflux capacity in patients with coronary heart diseases and its association with disease severity. Some authors consider a decrease of this HDL capacity as a new additional risk factor of atherosclerosis. The review summarizes existing information on various protein and lipid components of HDL with a primary emphasis on the HDL. Special attention is paid to correlation between the HDL cholesterol efflux capacity and HDL phospholipids and the ratio "phospholipids/free cholesterol". The accumulated information indicates importance of evaluation in the HDL fraction not only in terms of their cholesterol, but also phospholipids. In addition to the traditionally used lipid criteria, this would provide more comprehensive information about the activity of the reverse cholesterol transport process in the body and could contribute to the targeted correction of the detected disorders.

Hydrogen influences HDL-associated enzymes and reduces oxidized phospholipids levels in rats fed with a high-fat diet

AimsOxidized phospholipids (OxPLs) are formed as a result of oxidative stress, which potentially mediate multiple pathological effects. We aimed to evaluate the effects of hydrogen (H2) on OxPLs in vivo and the underlying mechanism. Main methodsRats were randomly assigned to three groups: control group fed with a chow diet, model group fed with a high-fat diet, and H2-treated group fed with a high-fat diet and treated by 4% H2 inhalation for ten weeks. OxPLs in liver and plasma were analyzed by liquid chromatography–mass spectrometry. High-density lipoprotein (HDL) was separated by ultracentrifugation. A proteomic analysis was performed to reveal the alternation of HDL protein composition and he antioxidant capacity of HDL was tested by low-density lipoprotein oxidation experiment. Furthermore, the activity or expression of HDL-associated enzymes were evaluated. Key findingsInhalation of 4% H2 decreased the accumulation of OxPLs in rats. In vitro tests revealed that the different concentrations of H2 did not inhibit the formation of OxPLs mediated by non-enzymatic oxidation. H2 inhalation altered the components and enhanced the anti-oxidative capacity of HDL in rats fed with a high-fat diet. Further experiments showed that H2 significantly regulated the activity of lipoprotein-associated phospholipase A2, paraoxonase-1, and the expression of lecithin:cholesterol acyltransferase. SignificanceOur findings revealed that H2 may reduce the OxPLs levels through its influence on HDL-associated enzymes that can act on OxPLs, suggesting that H2 can be used in alleviating diseases related to lipid peroxidation due to oxidative stress.

Apolipoprotein mimetics in cancer.

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.