Enrichment of Triglyceride-Rich Lipoproteins with Apolipoprotein C-I Is Positively Associated with Their Delayed Plasma Clearance Independently of Other Transferable Apolipoproteins in Postmenopausal Overweight and Obese Women.

Background: The role of plasma apolipoprotein (apo) C-I in cardiometabolic risk in humans is unclear. However, in vitro studies showed a dual role for apoC-I, both protective and harmful, depending on the carrier lipoprotein.Objective: We tested the hypothesis that triglyceride (TG)-rich lipoprotein (TRL) apoC-I, not total or HDL apoC-I, is associated with delayed postprandial plasma clearance of TRLs, independently of apoC-II, apoC-III, and apoE.Methods: This cross-sectional study examines the plasma clearance of a 13C-triolein-labeled high-fat meal (68% fat energy) in 20 postmenopausal overweight and obese women [body mass index (in kg/m2) ≥27; aged 45-74 y] as the increment change in area under the 6-h postprandial curves (iAUC6h) of TRL parameters. Lipoproteins were fractionated by fast-protein LC. Transferable apolipoproteins were measured by ELISA. TRL enrichment with apolipoproteins was calculated by dividing their TRL concentrations by TRL apoB. The effects of human apoC-I and apoC-III on the hydrolysis and storage of 3H-triolein-labeled TRLs were tested in 3T3-L1 adipocytes.Results: TRL apoC-I was positively associated with plasma apo B-48 and total and non-HDL TGs, cholesterol, and apoB (r = 0.52-0.97) and negatively with HDL cholesterol (r = -0.52) and LDL diameter (r = -0.91) (P < 0.05). Total and HDL apoC-I were correlated only with total (r = 0.62) and HDL (r = 0.75) cholesterol. Women with high fasting TRL enrichment with apoC-I (99-365 µmol apoC-I/µmol apoB), but not apoC-II, apoC-III, or apoE, had higher iAUC6h for TGs (+195%), 13C-TGs (+319%), and apo B-48 (+186%) than those with low enrichment (14-97 µmol apoC-I/µmol apoB). The 4-h postprandial increase in TRL apoC-I was associated with a 4-h increase in TRL TGs and iAUC6h for TGs, 13C-TGs, and apo B-48 (r = 0.74-0.86, P < 0.001), independently of 4-h changes in TRL apoB, apoC-II, apoC-III, or apoE. ApoC-I and apoC-III inhibited 3H-TRL clearance by adipocytes by >75% (P < 0.001).Conclusions: TRL enrichment with apoC-I is positively associated with postprandial hypertriglyceridemia and remnant accumulation in postmenopausal overweight and obese women, independently of apoC-II, apoC-III, or apoE, which may be due to inhibiting TRL clearance by adipocytes. Reducing TRL apoC-I may ameliorate delayed postprandial plasma clearance of TRLs and associated risks in humans.

Hypolipidemic Activity of Cassia tora Seeds in Hyperlipidemic Rats.

The hypolipidemic activity of Cassia tora (Chakvat, Chakunda) (Family: Caesalpiniaceae) seeds extract have been studied in two models of hyperlipidemia in rats. In an acute model, hyperlipidemia was induced by injecting a single dose of Triton WR-1339 (400 mg/kg, b.w.) intraperitonially in rats. Feeding with C. tora seed extract at the dose of 500 mg/kg, b.w. exerted significant lipid lowering effect as assessed by the reversal of plasma levels of total cholesterol, phospholipids, triglyceride and reactivation of post heparin lipolytic activity. In the chronic model, hyperlipidemia was induced by feeding with cholesterol rich-HFD in rats. The treatment with seeds extract of C. tora (500 mg/kg, b.w.) simultaneously for 15 days also caused lowering of lipid levels in plasma and liver following reactivation of plasma post heparin lipolytic activity and hepatic lipoprotein lipase activity in animals. The hypolipidemic activity of C. tora seeds was compared with a standard drug guggulipid (200 mg/kg, b.w.) in both models.

Simple and rapid real-time monitoring of LPL activity in vitro.

Since elevated plasma triglycerides are an independent risk factor for cardiovascular diseases, lipoprotein lipase (LPL) is an interesting target for drug development. However, investigation of LPL remains challenging, as most of the commercially available assays are limited to the determination of LPL activity. Thus, we focused on the evaluation of a simple in vitro real-time fluorescence assay for the measurement of LPL activity that can be combined with additional cell or molecular biological assays in the same cell sample. Our procedure allows for a more comprehensive characterization of potential regulatory compounds targeting the LPL system. The presented assay procedure provides several advantages over currently available commercial in vitro LPL activity assays:1.12-well cell culture plate design for the simultaneous investigation of up to three different compounds of interest (including all assay controls).2.24 h real-time acquisition of LPL activity for the identification of the optimal time point for further measurements.3.Measurement of LPL activity can be supplemented by additional cell or molecular biological assays in the same cell sample.

Clinical and functional studies of two novel variants in the LPL gene in subjects with severe hypertriglyceridemia.

BACKGROUND: Two novel variants (p.Arg270Gly and p.Asp308Glyfs*3) in the LPL gene have recently been identified in subjects with hypertriglyceridemia (HTG). In this study, we investigated clinical and genetic features of their families and examined the functional significance of these two variants in vitro. METHODS: Clinical and genetic data were collected. Site-directed mutagenesis and transient expression in cld cells were performed. Lipoprotein lipase (LPL) mass and activity were measured. RESULTS: In vitro studies showed that LPL mass and activity in the media of cells transfected with the p.Arg270Gly variant were significantly reduced. In the cell lysates, however, LPL mass was preserved but LPL activity was reduced, suggesting that the LPL defect was in the secretion and activity. For the p.Asp308Glyfs*3 variant, LPL mass in the cell lysate was relatively preserved compared to that of the wild-type, while LPL mass in the media was decreased albeit not significantly. LPL activities in the cell lysate and in the media of cells transfected with this variant were significantly reduced, suggesting that the p.Asp308Glyfs*3 variant might affect the activity, and possibly, secretion of LPL. CONCLUSIONS: These novel variants in the LPL gene were likely pathogenic with the defect in secretion and/or activity.

Molecular basis of the familial chylomicronemia syndrome in patients from the National Dyslipidemia Registry of the Spanish Atherosclerosis Society.

BACKGROUND: Familial chylomicronemia syndrome (FCS) is an extremely rare lipoprotein disorder caused by mutations in at least 5 genes of the lipoprotein lipase (LPL) complex. OBJECTIVE: This work shows the molecular analysis of patients diagnosed with FCS, who attended the Spanish Arteriosclerosis Society lipid units and were included in the National Dyslipidemia Registry. METHODS: Among the 238 patients registered with severe hypertriglyceridemia (fasting triglycerides >1000 mg/dL), 26 were diagnosed with FCS as they had confirmed postheparin plasma LPL activity deficiency and/or homozygosity for loss-of-function mutations in LPL, GPIHBP1, APOC2, LMF1, or Apolipoprotein A5 (APOA5). RESULTS: Among the 26 FCS cases, 23 had mutations in the homozygous state: 19 in LPL and 4 in the GPIHBP1 gene. The molecular analysis revealed 3 novel mutations: 2 in LPL, in 2 unrelated patients (c.312delA; p.Asp105Thrfs*66 and c.629A>G; p.His210Arg), and 1 in GPHIBP1 in a third patient (c.502delC; p.Leu168Serfs*83). These 3 patients had confirmed lack of LPL activity. Three additional patients with confirmed LPL activity deficiency were heterozygous carriers of mutations in the genes analyzed. Among these, we found 2 novel mutations in APOA5 (c.50-1G>A and c.326_327insC; p.Tyr110Leufs*158). CONCLUSION: We have identified 5 novel pathogenic mutations: 2 in LPL, 1 in GPIHBP1, and 2 in the APOA5 gene. The genetic defaults accounting for the LPL activity deficiency of 23 of them have been clearly identified and 3 patients, who harbored mutations in heterozygosity, were diagnosed based on LPL activity deficiency, which raises the question of the involvement of new genes in the manifestation of FCS.

Characterization of two novel pathogenic variants at compound heterozygous status in lipase maturation factor 1 gene causing severe hypertriglyceridemia.

BACKGROUND: Severe hypertriglyceridemia is a rare disease characterized by triglyceride levels higher than 1000 mg/dL (11.3 mmol/L) and acute pancreatitis. The disease is caused by pathogenic variants in genes encoding lipoprotein lipase (LPL), apolipoprotein A5, apolipoprotein C2, glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1, and lipase maturation factor 1 (LMF1). OBJECTIVE: We aim to identify the genetic cause of severe hypertriglyceridemia and characterize the new variants in a patient with severe hypertriglyceridemia. METHODS: The proband was a male showing severe hypertriglyceridemia (triglycerides 1416 mg/dL, 16.0 mmol/L); proband's relatives were also screened. Genetic screening included direct sequencing of the above genes and identification of large rearrangements in the LPL gene. Functional characterization of mutant LMF1 variants was performed by complementing LPL maturation in transfected LMF1-deficient mouse fibroblasts. RESULTS: The proband and his affected brother were compound heterozygotes for variants in the LMF1 gene never identified as causative of severe hypertriglyceridemia c.[157delC;1351C>T];[410C>T], p.[(Arg53Glyfs*5)];[(Ser137Leu)]. Functional analysis demonstrated that the p.(Arg53Glyfs*5) truncation completely abolished and the p.(Ser137Leu) missense variant dramatically diminished the lipase maturation activity of LMF1. CONCLUSIONS: In addition to a novel truncating variant, we describe for the first time a missense variant functionally demonstrated affecting the lipase maturation function of LMF1. This is the first case in which compound heterozygous variants in LMF1 were functionally demonstrated as causative of severe hypertriglyceridemia.

Reduced LPL and subcutaneous lipid storage capacity are associated with metabolic syndrome in postmenopausal women with obesity.

OBJECTIVES: This study examines the hypothesis that lower adipose tissue lipoprotein lipase (LPL) activity and a limited capacity for subcutaneous adipocyte expansion will be associated with metabolic syndrome (MSyn) in postmenopausal women who are overweight and obese. METHODS: Women (N = 150; age 60 ± 1 year; BMI: 31.5 ± 0.3 kg m-2; mean ± standard errors of the means [SEM]) with and without MSyn had dual-energy X-ray absorptiometry scans for total body fat, CT scans for visceral and subcutaneous abdominal adipose tissue areas, lipid and glucose metabolic profiles, and abdominal and gluteal fat aspirations for subcutaneous fat cell weight (FCW; N = 150) and LPL activity (N = 100). RESULTS: Women with MSyn had similar total body fat, but 15% larger abdominal and 11% larger gluteal FCWs and more visceral fat (179 ± 7 vs. 134 ± 6 cm2) than women without MSyn (P's < 0.05). Abdominal LPL activity was 13% (P = 0.18) lower in women with than without MSyn and correlated with abdominal FCW (r = 0.49, P < 0.01) only in those without MSyn. Visceral fat and abdominal and gluteal FCWs correlated with MSyn components, and subcutaneous adipose tissue correlated with abdominal FCW (r = 0.43, P < 0.01) and LPL activity (r = 0.18, P < 0.05), independent of total body fat. CONCLUSIONS: These results show that women with MSyn have lower LPL activity, limited capacity for subcutaneous adipocyte lipid storage and greater ectopic fat accumulation in viscera than women without MSyn of comparable obesity. This suggests that the development of novel therapies that would enhance adipocyte expandability might prevent the accumulation of ectopic fat and reduce the risk for MSyn in postmenopausal women with obesity.

Design and synthesis of novel indole-chalcone fibrates as lipid lowering agents.

A series of novel indole-chalcone fibrates were synthesized and their hypolipidemic activity was evaluated in triton WR-1339 induced hyperlipidemic rat model. Preliminary studies indicated that the hybrids 19, 24 and 29 exhibited potent in vitro antioxidant and significant in vivo antidyslipidemic effects. Our results suggest that these new hybrid architectures may serve as promising leads for the development of next generation lipid lowering agents.

Synthesis of new andrographolide derivatives and evaluation of their antidyslipidemic, LDL-oxidation and antioxidant activity.

Andrographis paniculata, native to Taiwan, Mainland China and India, is a medicinal herb, which possesses various biological activities including anti-atherosclerosis. Andrographolide (1) has been identified as one of the active constituents against atherosclerosis. In continuation of our drug discovery program we synthesized few novel derivatives of 1 to improve their antidyslipidemic, LDL-oxidation and antioxidant activity. The tosylated derivative 7 has been turned out to be more potent than the parent compound and comparable activity with marketed antidyslipidemic drugs.