Plasma Lecithin:cholesterol Acyltransferase Research Articles

Lecithin-cholesterol acyltransferase and paraoxonase-1 levels in atherosclerotic cardiovascular disease patients in Nigeria.

Recent evidence has linked changes in plasma lecithin-cholesterol acyltransferase (LCAT) and paraoxonase-1 (PON-1) levels with increased risk for development of premature atherosclerotic cardiovascular disease (ASCVD) in different populations. However, studies on this in Nigeria and sub-Saharan Africa are scarce. This study assessed the association between reduced plasma LCAT and PON-1 levels and an increased risk of ASCVD, and their potential as biomarkers for ASCVD. Atherosclerotic cardiovascular disease patients and healthy controls were randomly selected for this cross-sectional case-control study from the Lagos State University Teaching Hospital, Ikeja, Lagos, Nigeria, between March 2022 and March 2023. Plasma LCAT and PON-1 were determined by sandwich enzyme-linked immunosorbent assay, while the lipid profile was measured by spectrophotometry. A total of 153 ASCVD patients (mean age: 52.92 ± 10.24 years) and 50 healthy controls (mean age: 46.96 ± 11.05 years) were included in the analyses. Stastistically significant increases were observed in the mean body weight, hip circumference, waist circumference, waist-to-hip ratio, body mass index, diastolic and systolic blood pressure (all p ≤ 0.001), and pulse rate (p = 0.003) compared to the control values. Statistically significant increases were also observed in the mean plasma total cholesterol, triglycerides, low-density lipoprotein cholesterol, and non-high-density lipoprotein cholesterol (all p ≤ 0.001). In contrast, the mean plasma high-density lipoprotein cholesterol, LCAT, and PON-1 (p ≤ 0.001) were notably reduced compared to the control values. The present study provides supportive evidence that changes in plasma LCAT and PON-1 could predispose individuals to risk of premature ASCVD. Plasma LCAT and PON-1 may serve as independent markers or complement other established cardiovascular disease markers to discriminate the risk of ASCVD when it is unclear.

Seasonal Factors Are Associated with Activities of Enzymes Involved in High-Density Lipoprotein Metabolism among Pregnant Females in Ghana

BackgroundSmall-quantity lipid-based nutrient supplements (SQ-LNS) during pregnancy and postnatally were previously shown to improve high-density lipoprotein (HDL) cholesterol efflux capacity (CEC) and length in the children of supplemented mothers at 18 mo of age in the International Lipid-Based Nutrient Supplements (iLiNS) DYAD trial in Ghana. However, the effects of SQ-LNS on maternal HDL functionality during pregnancy are unknown. ObjectiveThe goal of this cross-sectional, secondary outcome analysis was to compare HDL function in mothers supplemented with SQ-LNS vs. iron and folic acid (IFA) during gestation. MethodsHDL CEC and the activities of 3 HDL-associated enzymes were analyzed in archived plasma samples (N = 197) from a subsample of females at 36 weeks of gestation enrolled in the iLiNS-DYAD trial in Ghana. Correlations between HDL function and birth outcomes, inflammatory markers C-reactive protein (CRP) and alpha-1-acid glycoprotein (AGP), and the effects of season were explored to determine the influence of these factors on HDL function in this cohort of pregnant females. ResultsThere were no statistically significant differences in HDL CEC, plasma lecithin-cholesterol acyltransferase (LCAT) activity, cholesteryl ester transfer protein (CETP) activity, or phospholipid transfer protein (PLTP) activity between mothers supplemented with SQ-LNS compared with IFA control, and no statistically significant relationships between maternal HDL function and childbirth outcomes. LCAT activity was negatively correlated with plasma AGP (R = -0.19, P = 0.007) and CRP (R = -0.28, P < 0.001), CETP and LCAT activity were higher during the dry season compared to the wet season, and PLTP activity was higher in the wet season compared to the dry season. ConclusionsMothers in Ghana supplemented with SQ-LNS compared with IFA during gestation did not have measurable differences in HDL functionality, and maternal HDL function was not associated with childbirth outcomes. However, seasonal factors and markers of inflammation were associated with HDL function, indicating that these factors had a stronger influence on HDL functionality than SQ-LNS supplementation during pregnancy. Clinical Trial Registry numberThe study was registered as NCT00970866. https://clinicaltrials.gov/study/NCT00970866

Influence of lecithin cholesterol acyltransferase alteration during different pathophysiologic conditions: A 45years bibliometrics analysis.

Background: Lecithin cholesterol acyltransferase (LCAT) is an important enzyme responsible for free cholesterol (FC) esterification, which is critical for high density lipoprotein (HDL) maturation and the completion of the reverse cholesterol transport (RCT) process. Plasma LCAT activity and concentration showed various patterns under different physiological and pathological conditions. Research on LCAT has grown rapidly over the past 50 years, but there are no bibliometric studies summarizing this field as a whole. This study aimed to use the bibliometric analysis to demonstrate the trends in LCAT publications, thus offering a brief perspective with regard to future developments in this field. Methods: We used the Web of Science Core Collection to retrieve LCAT-related studies published from 1975 to 2020. The data were further analyzed in the number of studies, the journal which published the most LCAT-related studies, co-authorship network, co-country network, co-institute network, co-reference and the keywords burst by CiteSpace V 5.7. Results: 2584 publications contained 55,311 references were used to analyzed. The number of included articles fluctuated in each year. We found that Journal of lipid research published the most LCAT-related studies. Among all the authors who work on LCAT, they tend to collaborate with a relatively stable group of collaborators to generate several major authors clusters which Albers, J. published the most studies (n = 53). The United States of America contributed the greatest proportion (n = 1036) of LCAT-related studies. The LCAT-related studies have been focused on the vascular disease, lecithin-cholesterol acyltransferase reaction, phospholipid, cholesterol efflux, chronic kidney disease, milk fever, nephrotic syndrome, platelet-activating factor acetylhydrolase, reconstituted lpa-i, reverse cholesterol transport. Four main research frontiers in terms of burst strength for LCAT-related studies including "transgenic mice", "oxidative stress", "risk", and "cholesterol metabolism "need more attention. Conclusion: This is the first study that demonstrated the trends and future development in LCAT publications. Further studies should focus on the accurate metabolic process of LCAT dependent or independent of RCT using metabolic marker tracking techniques. It was also well worth to further studying the possibility that LCAT may qualify as a biomarker for risk prediction and clinical treatment.

Plasma Lecithin-Cholesterol Acyltransferase Activity in Pregnant Women Enrolled in the iLiNS-DYAD Trial in Ghana

ObjectivesThe International Lipid-Based Nutrient Supplement (iLiNS) Project developed small-quantity lipid-based nutrient supplements (SQ-LNS) for mothers and their children with the goal of reducing malnutrition. The aim of this secondary outcome analysis is to investigate the effects of SQ-LNS on the activity of plasma lecithin-cholesterol acyltransferase (LCAT), a key enzyme involved in the remodeling of high-density lipoprotein (HDL) particles, which increases their cholesterol carrying capacity.MethodsPlasma samples from a subset of 197 out of 1320 women at 36-wk gestation enrolled in the iLiNS-DYAD trial in Ghana were analyzed. In the main cohort, women were enrolled during the second trimester (≤ 20 wk gestation) and randomly assigned to receive SQ-LNS, iron and folic acid (IFA), or a multiple micronutrient supplement. Women in this subset received either SQ-LNS or IFA. Plasma LCAT activity was measured using a commercial fluorometric kit and the non-transformed data was compared by Wilcoxon test (mean ± SD). LCAT activity is expressed as a ratio (390 nm/470 nm), where greater ratio indicates higher enzyme activity. We also explored whether LCAT activity differed by enrollment season (Dry, November–April; Wet, May-October) or was associated with biomarkers of inflammation.ResultsThere was no significant difference in LCAT activity between the SQ-LNS and IFA groups (1.44 ± 0.17 vs. 1.41 ± 0.14, P = 0.24). Women enrolled during the wet season had higher LCAT activity than women enrolled during the dry season (1.47 ± 0.15 vs. 1.37 ± 0.14, P < 0.001), with no differences between intervention groups stratified by season (P > 0.05). LCAT activity was negatively correlated with inflammatory biomarkers α1-acid glycoprotein (R = −0.19, P = 0.007) and C-reactive protein (R = −0.28, P < 0.001) measured at 36-wk gestation.ConclusionsPlasma LCAT activity, as a measure of HDL maturation and cholesterol carrying capacity, is more sensitive to factors mediated by seasonal variation (e.g., infection, inflammation) than by nutrient supplementation in this cohort of women in Ghana. These findings confirm a previously established link between HDL and inflammation.Funding SourcesThis project was supported by Bill & Melinda Gates Foundation grant (OPP124589) to the University of California, Davis.

Pterostilbene Inhibits Dyslipidemia-Induced Activation of Progenitor Adipose Gene Under High-Fat Diet and Radiation Stressor

Repeated exposure to ionizing radiation has been reported to increase the risk of chronic metabolic disorders such as systemic hyperlipidemia and intracellular lipid accumulation that might lead to diabetes-induced heart disease. The purpose of this study was to investigate the effect of pterostilbene on high-fat diet rats suffering from ionizing radiation-induced hyperlipidemia. High-fat diet rats showed an increase in body weight and body fat compared with rats fed with normal chow. Pterostilbene and Orlistat treatments resulted in lower body weight and body fat gain, insulin resistance, reduced lipid peroxidation with attenuated liver enzyme levels, and regulated lipogenesis-related genes in the HFD + IR rat group. Regulation of Peroxisome proliferator-activated receptor-γ (PPAR-γ) mRNA enhanced paraoxonase-1 (PON-1) and arylesterase (AE) activities and inhibited that of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA). It also increased the activities of plasma lecithin-cholesterol acyltransferase (LCAT) and lipoprotein lipase (LPL). Pterostilbene and Orlistat also corrected the alterations of serum leptin and adiponectin levels in lipidemic rats. Such findings provide evidence that Pterostilbene and Orlistat can act as normolipidemic agents that possess lipid-lowering effects and potential as a radioprotector.

Low Plasma Lecithin: Cholesterol Acyltransferase (LCAT) Concentration Predicts Chronic Kidney Disease.

Low high-density lipoprotein-cholesterol (HDL-c) is the most remarkable lipid trait both in mild-to-moderate chronic kidney disease (CKD) patients as well as in advanced renal disease stages, and we have previously shown that reduced lecithin:cholesterol acyltransferase (LCAT) concentration is a major determinant of the low HDL phenotype. In the present study, we test the hypothesis that reduced LCAT concentration in CKD contributes to the progression of renal damage. The study includes two cohorts of subjects selected from the PLIC study: a cohort of 164 patients with CKD (NefroPLIC cohort) and a cohort of 164 subjects selected from the PLIC participants with a basal estimated glomerular filtration rate (eGFR) > 60 mL/min/1.73 m2 (PLIC cohort). When the NefroPLIC patients were categorized according to the LCAT concentration, patients in the 1st tertile showed the highest event rate at follow-up with an event hazard ratio significantly higher compared to the 3rd LCAT tertile. Moreover, in the PLIC cohort, subjects in the 1st LCAT tertile showed a significantly faster impairment of kidney function compared to subjects in the 3rd LCAT tertile. Serum from subjects in the 1st LCAT tertile promoted a higher reactive oxygen species (ROS) production in renal cells compared to serum from subjects in the third LCAT tertile, and this effect was contrasted by pre-incubation with recombinant human LCAT (rhLCAT). The present study shows that reduced plasma LCAT concentration predicts CKD progression over time in patients with renal dysfunction, and, even more striking, it predicts the impairment of kidney function in the general population.

ApoE and apoC-III-defined HDL subtypes: a descriptive study of their lecithin cholesterol acyl transferase and cholesteryl ester transfer protein content and activity

BackgroundThe functionality of high-density lipoproteins (HDL) is a better cardiovascular risk predictor than HDL concentrations. One of the key elements of HDL functionality is its apolipoprotein composition. Lecithin-cholesterol acyl transferase (LCAT) and cholesterol-ester transfer protein (CETP) are enzymes involved in HDL-mediated reverse cholesterol transport. This study assessed the concentration and activity of LCAT and CETP in HDL subspecies defined by their content of apolipoproteins E (apoE) and C-III (apoC-III) in humans.MethodsEighteen adults (ten women and eight men, mean age 55.6, BMI 26.9 Kg/m2, HbA1c 5.4%) were studied. HDL from each participant were isolated and divided into four subspecies containing respectively: No apoE and no apoC-III (E-C-), apoE but not apoC-III (E + C-), apoC-III but no apoE (E-C+) and both apoE and apoC-III (E + C+). The concentration and enzymatic activity of LCAT and CETP were measured within each HDL subspecies using immunoenzymatic and fluorometric methods. Additionally, the size distribution of HDL in each apolipoprotein-defined fraction was determined using non-denaturing electrophoresis and anti-apoA-I western blotting.ResultsHDL without apoE or apoC-III was the predominant HDL subtype. The size distribution of HDL was very similar in all the four apolipoprotein-defined subtypes. LCAT was most abundant in E-C- HDL (3.58 mg/mL, 59.6% of plasma LCAT mass), while HDL with apoE or apoC-III had much less LCAT (19.8, 12.2 and 8.37% of plasma LCAT respectively for E + C-, E-C+ and E + C+). LCAT mass was lower in E + C- HDL relative to E-C- HDL, but LCAT activity was similar in both fractions, signaling a greater activity-to-mass ratio associated with the presence of apoE. Both CETP mass and CETP activity showed only slight variations across HDL subspecies. There was an inverse correlation between plasma LCAT activity and concentrations of both E-C+ pre-beta HDL (r = − 0.55, P = 0.017) and E-C- alpha 1 HDL (r = − 0.49, P = 0.041). Conversely, there was a direct correlation between plasma CETP activity and concentrations of E-C+ alpha 1 HDL (r = 0.52, P = 0.025).ConclusionsThe presence of apoE in small HDL is correlated with increased LCAT activity and esterification of plasma cholesterol. These results favor an interpretation that LCAT and apoE interact to enhance anti-atherogenic pathways of HDL.

LCAT protects against Lipoprotein-X formation in a murine model of drug-induced intrahepatic cholestasis.

Familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) is a rare genetic disease characterized by low HDL‐C levels, low plasma cholesterol esterification, and the formation of Lipoprotein‐X (Lp‐X), an abnormal cholesterol‐rich lipoprotein particle. LCAT deficiency causes corneal opacities, normochromic normocytic anemia, and progressive renal disease due to Lp‐X deposition in the glomeruli. Recombinant LCAT is being investigated as a potential therapy for this disorder. Several hepatic disorders, namely primary biliary cirrhosis, primary sclerosing cholangitis, cholestatic liver disease, and chronic alcoholism also develop Lp‐X, which may contribute to the complications of these disorders. We aimed to test the hypothesis that an increase in plasma LCAT could prevent the formation of Lp‐X in other diseases besides FLD. We generated a murine model of intrahepatic cholestasis in LCAT‐deficient (KO), wild type (WT), and LCAT‐transgenic (Tg) mice by gavaging mice with alpha‐naphthylisothiocyanate (ANIT), a drug well known to induce intrahepatic cholestasis. Three days after the treatment, all mice developed hyperbilirubinemia and elevated liver function markers (ALT, AST, Alkaline Phosphatase). The presence of high levels of LCAT in the LCAT‐Tg mice, however, prevented the formation of Lp‐X and other plasma lipid abnormalities in WT and LCAT‐KO mice. In addition, we demonstrated that multiple injections of recombinant human LCAT can prevent significant accumulation of Lp‐X after ANIT treatment in WT mice. In summary, LCAT can protect against the formation of Lp‐X in a murine model of cholestasis and thus recombinant LCAT could be a potential therapy to prevent the formation of Lp‐X in other diseases besides FLD.

Auricular concha eletroacupuncture modulates lipid-lipoprotein metabolism in rats submitted to cold stress

ObjectiveTo explore whether auricular concha eletroacupuncture (ACEA) is effective in regulating lipid-lipoprotein metabolism in rats submitted to cold stress. MethodsThirty-six adult male Sprague–Dawley rats were placed in four groups(9 rats in each group), the rats in three groups of which were submitted to cold stress for fourteen days, the last one of which was a control group. After the cold stress process, in those three groups, the rats of one group were with no treatment (stress only), two were treated with either ACEA or auricular margin eletroacupuncture (AMEA) repeated for fourteen days. On the 14th day, all the rats were sacrificed after all experimental procedure for blood sampling. Blood glucose, triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels were tested by using the collected serum. Plasma lecithin-cholesterol acyltransferase (LCAT) was measured with ELISA kit. ResultsACEA down-regulated the TG level (P < 0.05) and LDL-C level (P < 0.05), and up-regulated HDL-C level (P < 0.05) and LACT level (P < 0.05). AMEA did not regulate the bio-markers. ConclusionACEA played an important role in regulating lipid-lipoprotein metabolism in rats submitted to cold stress.

Recombinant LCAT (Lecithin:Cholesterol Acyltransferase) Rescues Defective HDL (High-Density Lipoprotein)-Mediated Endothelial Protection in Acute Coronary Syndrome.

Objective- Aim of this study was to evaluate changes in LCAT (lecithin:cholesterol acyltransferase) concentration and activity in patients with an acute coronary syndrome, to investigate if these changes are related to the compromised capacity of HDL (high-density lipoprotein) to promote endothelial nitric oxide (NO) production, and to assess if rhLCAT (recombinant human LCAT) can rescue the defective vasoprotective HDL function. Approach and Results- Thirty ST-segment-elevation myocardial infarction (STEMI) patients were enrolled, and plasma was collected at hospital admission, 48 and 72 hours thereafter, at hospital discharge, and at 30-day follow-up. Plasma LCAT concentration and activity were measured and related to the capacity of HDL to promote NO production in cultured endothelial cells. In vitro studies were performed in which STEMI patients' plasma was added with rhLCAT and HDL vasoprotective activity assessed by measuring NO production in endothelial cells. The plasma concentration of the LCAT enzyme significantly decreases during STEMI with a parallel significant reduction in LCAT activity. HDL isolated from STEMI patients progressively lose the capacity to promote NO production by endothelial cells, and the reduction is related to decreased LCAT concentration. In vitro incubation of STEMI patients' plasma with rhLCAT restores HDL ability to promote endothelial NO production, possibly related to significant modification in HDL phospholipid classes. Conclusions- Impairment of cholesterol esterification may be a major factor in the HDL dysfunction observed during acute coronary syndrome. rhLCAT is able to restore HDL-mediated NO production in vitro, suggesting LCAT as potential therapeutic target for restoring HDL functionality in acute coronary syndrome.

Cholesteryl ester transfer protein (CETP), HDL capacity of receiving cholesterol and status of inflammatory cytokines in patients with severe heart failure

BackgroundHeart failure (HF) courses with chronic inflammatory process and alterations in lipid metabolism may aggravate the disease. The aim was to test whether the severity of HF, using brain natriuretic peptide (BNP) as a marker, is associated with alterations in functional aspects of HDL, such as lipid transfer, cholesterol ester transfer protein (CETP) and lecithin-cholesterol acyltransferase (LCAT) concentration.MethodsTwenty-five HF patients in NYHA class I/II and 23 in class III/IV were enrolled. Plasma lipids, apolipoproteins, CETP, LCAT, oxidized-LDL (oxLDL) and paraoxonase-1 (PON-1) activity were determined. Lipid transfer from a donor artificial nanoparticle to HDL was measured by in vitro assay.ResultsTotal cholesterol (p = 0.049), LDL-C (p = 0.023), non-HDL-C (p = 0.029) and CETP, that promotes lipid transfer among lipoproteins (p = 0.013), were lower in III/IV than in I/II group. Triglycerides, HDL-C, apo A-I, apo B, oxLDL, LCAT, enzyme that catalyzes serum cholesterol esterification, PON-1 activity, and in vitro transfers of cholesterol, triglycerides and phospholipids to HDL, important steps in HDL metabolism, were equal. IL-8 was higher in III/IV (p = 0.025), but TNFα, IL-1β, IL-6 and MCP-1 were equal. BNP was negatively correlated with CETP (r = − 0.294; p = 0.042) and positively correlated with IL-8 (r = 0.299; p = 0.039).ConclusionsOur results disclosed the relationship between CETP levels and HF severity, by comparing two HF groups and by correlation analysis. Lower CETP levels may be a marker of HF aggravation and possibly of worse prognosis. Practical applications of this initial finding, as the issue whether CETP could be protective against HF aggravation, should be explored in larger experimental and clinical studies.

Elevated level of lecithin:cholesterol acyltransferase (LCAT) is associated with reduced coronary atheroma burden

Background and aimsLecithin:cholesterol acyltransferase (LCAT), a key enzyme in high-density lipoprotein (HDL) metabolism and reverse cholesterol transport (RCT), has been associated with atheroprotection. However, its relation to plaque characteristics has not been confirmed to date. We aimed to determine the relationship between plasma LCAT mass concentration and plaque burden in a multi-center imaging study. MethodsTwo hundred sixty-seven patients with angiographically proven coronary artery disease (CAD) underwent intravascular ultrasonography (IVUS) imaging. Ninety-six patients without CAD served as controls for biochemistry assessments. ResultsPlasma LCAT mass concentration was higher in CAD patients as compared to controls (8.94 ± 2.51 μg/mL vs. 7.89 ± 2.99 μg/mL, p = 0.003), while cholesterol esterification rate (CER) was downregulated (253.6 ± 83.9 μM/2 h vs. 315.3 ± 115.0 μM/2 h, p<0.0001). Both parameters correlated inversely with total atheroma volume (r = −0.14, p = 0.027 and r = −0.14, p = 0.024, respectively), while only LCAT mass was found to be a significant predictor of atheroma volume (β-coefficient −0.18, p = 0.0047) when tested in a stepwise linear regression model against known CAD risk factors as predictor variables. Accordingly, patients with LCAT mass in the highest quartile had significantly less atheroma burden than those in the lower quartiles (39.7 ± 10.7% vs. 45.4 ± 10.4%, p = 0.0014 for highest vs. lowest quartile of LCAT mass). ConclusionsPlasma LCAT mass concentration is upregulated in CAD patients and inversely related to plaque volume, suggesting atheroprotective effects. LCAT mass concentration outperformed LCAT activity in risk prediction models for atheroma burden, suggesting that LCAT mass is a key variable in atheroprotection. Further studies assessing LCAT as a therapeutic target in cardiovascular disease are warranted.

Plasma lecithin:cholesterol acyltransferase and phospholipid transfer protein activity independently associate with nonalcoholic fatty liver disease.

Nonalcoholic fatty liver disease (NAFLD) is a highly prevalent condition which contributes to atherogenic apolipoprotein B dyslipoproteinemias. Lecithin:cholesterol acyltransferase (LCAT) and phospholipid transfer protein (PLTP) are both synthesized by the liver and are important in lipid metabolism. Here, we interrogated the impact of NAFLD on plasma LCAT and PLTP activities. Plasma LCAT activity (exogenous substrate assay) and PLTP activity (phospholipid vesicles-HDL assay) were determined in 348 subjects (279 men; 81 subjects with type 2 diabetes (T2DM); 123 with metabolic syndrome (MetS)). A Fatty Liver Index (FLI) ≥60 was used as a proxy of NAFLD. Insulin resistance was determined by homoeostasis model assessment (HOMA-IR). A total of 147 participants had an FLI ≥60 coinciding with T2DM and MetS (P<0.001 for each). Plasma LCAT activity and PLTP activity were on average 12% and 5% higher, respectively, in subjects with an FLI≥60 (P<0.001 for each). In age- and sex-adjusted partial linear regression analysis, LCAT activity and PLTP activity were positively related to various obesity measures and HOMA-IR (P<0.001 for each). In multivariable linear regression analyses adjusted for age and sex, LCAT activity was associated with an FLI≥60 independent of T2DM and MetS, the waist/hip ratio, or HOMA-IR (β=0.307 to 0.366, P<0001 for all models). PLTP activity was also associated with an FLI≥60 independent of these variables (β=0.151 to 0223, P=0.013 to 0.001). NAFLD, as inferred from an FLI≥60, confers higher plasma LCAT and to a lesser extent PLTP activity, even when taking account of T2DM, MetS, central obesity and insulin resistance.

Niemann-Pick C1-deficient mice lacking sterol O-acyltransferase 2 have less hepatic cholesterol entrapment and improved liver function.

Cholesteryl esters are generated at multiple sites in the body by sterol O-acyltransferase (SOAT) 1 or SOAT2 in various cell types and lecithin cholesterol acyltransferase in plasma. Esterified cholesterol and triacylglycerol contained in lipoproteins cleared from the circulation via receptor-mediated or bulk-phase endocytosis are hydrolyzed by lysosomal acid lipase within the late endosomal/lysosomal (E/L) compartment. Then, through the successive actions of Niemann-Pick C (NPC) 2 and NPC 1, unesterified cholesterol (UC) is exported from the E/L compartment to the cytosol. Mutations in either NPC1 or NPC2 lead to continuing entrapment of UC in all organs, resulting in multisystem disease, which includes hepatic dysfunction and in some cases liver failure. These studies investigated primarily whether elimination of SOAT2 in NPC1-deficient mice impacted hepatic UC sequestration, inflammation, and transaminase activities. Measurements were made in 7-wk-old mice fed a low-cholesterol chow diet or one enriched with cholesterol starting 2 wk before study. In the chow-fed mice, NPC1:SOAT2 double knockouts, compared with their littermates lacking only NPC1, had 20% less liver mass, 28% lower hepatic UC concentrations, and plasma alanine aminotransferase and aspartate aminotransferase activities that were decreased by 48% and 36%, respectively. mRNA expression levels for several markers of inflammation were all significantly lower in the NPC1 mutants lacking SOAT2. The existence of a new class of potent and selective SOAT2 inhibitors provides an opportunity for exploring if suppression of this enzyme could potentially become an adjunctive therapy for liver disease in NPC1 deficiency. NEW & NOTEWORTHY In Niemann-Pick type C1 (NPC1) disease, the entrapment of unesterified cholesterol (UC) in the endosomal/lysosomal compartment of all cells causes multiorgan disease, including neurodegeneration, pulmonary dysfunction, and liver failure. Some of this sequestered UC entered cells initially in the esterified form. When sterol O-acyltransferase 2, a cholesterol esterifying enzyme present in enterocytes and hepatocytes, is eliminated in NPC1-deficient mice, there is a reduction in their hepatomegaly, hepatic UC content, and cellular injury.

Semi-synthetic thymoquinone analogs: new prototypes as potential antihyperlipidemics in irradiated rats.

Thymoquinone (TQ), has been reported to possess strong antihyperlipidemic properties. However, a variety of serious side effects has been reported for TQ. The present study aimed to evaluate the potential antihyperlipidemic activity of newly synthesized TQ analogs. first, novel TQ derivatives were studied against radiation-induced dyslipidemia in male rats. Second, the most promising sulfur derivatives (4-7), were further tested to elucidate their possible mechanism(s) of actions. Results showed that they possess Hydroxymethyl Glutaryl-Co A reductase inhibitory activity, as well as stimulatory effects on the activities of each of plasma Lecithin-Cholesterol Acyltransferase and lipoprotein lipase enzymes. TQ derivatives (4-7), could be considered as promising agents in pathologies implicating impaired lipid metabolism, preclinical evaluation is warranted. [Formula: see text].

Agonistic Human Antibodies Binding to Lecithin-Cholesterol Acyltransferase Modulate High Density Lipoprotein Metabolism

Drug discovery opportunities where loss-of-function alleles of a target gene link to a disease-relevant phenotype often require an agonism approach to up-regulate or re-establish the activity of the target gene. Antibody therapy is increasingly recognized as a favored drug modality due to multiple desirable pharmacological properties. However, agonistic antibodies that enhance the activities of the target enzymes are rarely developed because the discovery of agonistic antibodies remains elusive. Here we report an innovative scheme of discovery and characterization of human antibodies capable of binding to and agonizing a circulating enzyme lecithin cholesterol acyltransferase (LCAT). Utilizing a modified human LCAT protein with enhanced enzymatic activity as an immunogen, we generated fully human monoclonal antibodies using the XenoMouseTM platform. One of the resultant agonistic antibodies, 27C3, binds to and substantially enhances the activity of LCAT from humans and cynomolgus macaques. X-ray crystallographic analysis of the 2.45 Å LCAT-27C3 complex shows that 27C3 binding does not induce notable structural changes in LCAT. A single administration of 27C3 to cynomolgus monkeys led to a rapid increase of plasma LCAT enzymatic activity and a 35% increase of the high density lipoprotein cholesterol that was observed up to 32 days after 27C3 administration. Thus, this novel scheme of immunization in conjunction with high throughput screening may represent an effective strategy for discovering agonistic antibodies against other enzyme targets. 27C3 and other agonistic human anti-human LCAT monoclonal antibodies described herein hold potential for therapeutic development for the treatment of dyslipidemia and cardiovascular disease.

Familial lecithin:cholesterol acyltransferase deficiency: First-in-human treatment with enzyme replacement

Humans with familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) have extremely low or undetectable high-density lipoprotein cholesterol (HDL-C) levels and by early adulthood develop many manifestations of the disorder, including corneal opacities, anemia, and renal disease. To determine if infusions of recombinant human LCAT (rhLCAT) could reverse the anemia, halt progression of renal disease, and normalize HDL in FLD. rhLCAT (ACP-501) was infused intravenously over 1 hour on 3 occasions in a dose optimization phase (0.3, 3.0, and 9.0 mg/kg), then 3.0 or 9.0 mg/kg every 1 to 2 weeks for 7 months in a maintenance phase. Plasma lipoproteins, lipids, LCAT levels, and several measures of renal function and other clinical labs were monitored. LCAT concentration peaked at the end of each infusion and decreased to near baseline over 7 days. Renal function generally stabilized or improved and the anemia improved. After infusion, HDL-C rapidly increased, peaking near normal in 8 to 12 hours; analysis of HDL particles by various methods all revealed rapid sequential disappearance of preβ-HDL and small α-4 HDL and appearance of normal α-HDL. Low-density lipoprotein cholesterol increased more slowly than HDL-C. Of note, triglyceride routinely decreased after meals after infusion, in contrast to the usual postprandial increase in the absence of rhLCAT infusion. rhLCAT infusions were well tolerated in this first-in-human study in FLD; the anemia improved, as did most parameters related to renal function in spite of advanced disease. Plasma lipids transiently normalized, and there was rapid sequential conversion of small preβ-HDL particles to mature spherical α-HDL particles.

9. AAV-Mediated Gene Transfer as a Therapeutic Approach for Familial LCAT Deficiency

Lecithin Cholesterol Acyltransferase (LCAT) is a plasma enzyme secreted by the liver and responsible for esterification of free cholesterol to cholesteryl ester in the blood compartment. Familial LCAT deficiency (FLD) is an autosomal recessive disorder caused by loss-of-function mutations of the LCAT gene and is characterized by extremely low levels of high density lipoprotein cholesterol (HDL-C), anemia, corneal opacities, and chronic progressive renal disease leading to end-stage kidney disease as early as the third decade of life. Currently, there is no specific treatment for FLD. The fact that patients with even very low levels of plasma LCAT activity do not develop kidney disease make FLD an attractive candidate for liver-directed gene therapy with adeno-associated viral (AAV) vectors. LCAT is activated by apolipoprotein A-I (apoA-I) and this interaction is highly species specific. Therefore, LCAT KO mice were crossed with human apoA-I transgenic (hApoAITg) mice in order to facilitate experiments involving expression of human LCAT. LCAT KO/hApoAI transgenic mice received a single IP injection of AAV8 encoding human LCAT in a dose range of 5e10 GC/kg to 5e11 GC/kg. HDL-C increased in a dose-dependent fashion, from 32 mg/dL in the control group to 103 mg/dL at the dose of 1.5e11 GC/kg and 473 mg/dL at the dose of 5e11 GC/kg. Plasma% cholesterol ester, a sensitive indicator of LCAT activity, was normalized at the low dose of 1.5e11 GC/kg. Thus, we demonstrate that low doses of AAV8-hLCAT provide stable expression of the LCAT enzyme and correct dyslipidemia in a ‘humanized’ mouse model of LCAT deficiency. Studies designed to demonstrate prevention of kidney disease in this mouse model are ongoing. These proof-of-concept studies provide a foundation for further development of AAV-based gene therapy for familial LCAT deficiency.

Rice protein regulates HDL metabolism-related gene expression and enzyme activity in adult rats

To elucidate whether rice protein possess a vital function in regulating high density lipoprotein (HDL) metabolism, the effects of rice protein (RP) on HDL metabolism-related gene expressions and enzyme activities were investigated in adult rats. Compared with casein, lipid contents in plasma and liver were effectively reduced by RP-feeding, accompanying significant increased ratio of HDL to cholesterol or triglyceride. RP increased mRNA levels of lecithin-cholesterol acyltransferase, adenosine triphosphate-binding cassette transporter A1, scavenger receptor class B type I and liver X receptor α, as compared to casein. Hepatic activities of lipoprotein lipase and hepatic lipase were significantly stimulated by RP, whereas no significant difference of plasma lecithin-cholesterol acyltransferase activity was found in RP with respect to casein. Results demonstrated that rice protein could effectively regulate HDL metabolism through modifying the HDL metabolism-related gene expression levels and lipolytic enzyme activities, which involved with a hypocholesterolemic action during the adult period.

Acquired lecithin:cholesterol acyltransferase deficiency as a major factor in lowering plasma HDL levels in chronic kidney disease.

It has been suggested that a low plasma high-density lipoprotein cholesterol (HDL-C) level contributes to the high cardiovascular disease risk of patients with chronic kidney disease (CKD), especially those undergoing haemodialysis (HD). The present study was conducted to gain further understanding of the mechanism(s) responsible for the low HDL-C levels in patients with CKD and to separate the impact of HD from that of the underlying CKD. Plasma lipids and lipoproteins, HDL subclasses and various cholesterol esterification parameters were measured in a total of 248 patients with CKD, 198 of whom were undergoing HD treatment and 40 healthy subjects. Chronic kidney disease was found to be associated with highly significant reductions in plasma HDL-C, unesterified cholesterol, apolipoprotein (apo)A-I, apoA-II and LpA-I:A-II levels in both CKD cohorts (with and without HD treatment). The cholesterol esterification process was markedly impaired, as indicated by reductions in plasma lecithin:cholesterol acyltransferase (LCAT) concentration and activity and cholesterol esterification rate, and by an increase in the plasma preβ-HDL content. HD treatment was associated with a further lowering of HDL levels and impaired plasma cholesterol esterification. The plasma HDL-C level was highly significantly correlated with LCAT concentration (R=0.438, P<0.001), LCAT activity (R=0.243, P<0.001) and cholesterol esterification rate (R=0.149, P=0.031). Highly significant correlations were also found between plasma LCAT concentration and levels of apoA-I (R=0.432, P<0.001), apoA-II (R=0.275, P<0.001), LpA-I (R= 0.326, P<0.001) and LpA-I:A-II (R=0.346, P< 0.001). Acquired LCAT deficiency is a major cause of low plasma HDL levels in patients with CKD, thus LCAT is an attractive target for therapeutic intervention to reverse dyslipidaemia, and possibly lower the cardiovascular disease risk in these patients.