Metabolic and other morbid complications in congenital generalized lipodystrophy type 4.

Morbidity and mortality rates in patients with autosomal recessive, congenital generalized lipodystrophy type 4 (CGL4), an ultra-rare disorder, remain unclear. We report on 30 females and 16 males from 10 countries with biallelic null variants in CAVIN1 gene (mean age, 12 years; range, 2 months to 41 years). Hypertriglyceridemia was seen in 79% (34/43), hepatic steatosis in 82% (27/33) but diabetes mellitus in only 21% (8/44). Myopathy with elevated serum creatine kinase levels (346-3325 IU/L) affected all of them (38/38). 39% had scoliosis (10/26) and 57% had atlantoaxial instability (8/14). Cardiac arrhythmias were detected in 57% (20/35) and 46% had ventricular tachycardia (16/35). Congenital pyloric stenosis was diagnosed in 39% (18/46), 9 had esophageal dysmotility and 19 had intestinal dysmotility. Four patients suffered from intestinal perforations. Seven patients died at mean age of 17 years (range: 2 months to 39 years). The cause of death in four patients was cardiac arrhythmia and sudden death, while others died of prematurity, gastrointestinal perforation, and infected foot ulcers leading to sepsis. Our study highlights high prevalence of myopathy, metabolic abnormalities, cardiac, and gastrointestinal problems in patients with CGL4. CGL4 patients are at high risk of early death mainly caused by cardiac arrhythmias.

Hemophagocyte morphology and hypertriglyceridemia correlate with diagnosis of hemophagocytic lymphohistiocytosis in patients with bone marrow hemophagocytes.

OBJECTIVES: To investigate laboratory and bone marrow findings that can help predict a diagnosis of hemophagocytic lymphohistiocytosis (HLH) for patients who have demonstrated hemophagocytes (HPCs) in the bone marrow. METHODS: A total of 57 cases from 48 patients with HPCs present on bone marrow examination were included. The numbers and morphologic characteristics of HPCs with ingested nucleated cells (nHPC) were counted. Pertinent medical history, relevant laboratory values, and flow cytometry data at the time of bone marrow biopsy were collected. RESULTS: A total of 24 patients fulfilled diagnostic criteria for HLH, and the remaining 24 patients did not. By using HLH-2004 cutoffs, only hypertriglyceridemia (≥265 mg/dL) was significantly associated with HLH diagnosis. The HLH cases more frequently had nHPC-ingesting granulocytic cells (gHPC) (75.9% vs 24.1%, P = .009). The percentage of gHPC to all nHPC was also significantly higher in HLH cases (median, 15.4% vs 0%; P = .0002). Both triglyceride level (area under the curve [AUC] = 0.88, P < .0001) and gHPC percentage (AUC = 0.81, P = .0005) were significant in predicting HLH diagnosis. Finally, no overt immunophenotypic abnormality was noted for 19 HLH cases with available flow cytometry data. CONCLUSIONS: The presence of hypertriglyceridemia and more frequent gHPC has predictive value for HLH diagnosis in patients with bone marrow HPC.

Genetic variation in apolipoprotein A-V in hypertriglyceridemia.

PURPOSE OF REVIEW: While biallelic rare APOA5 pathogenic loss-of-function (LOF) variants cause familial chylomicronemia syndrome, heterozygosity for such variants is associated with highly variable triglyceride phenotypes ranging from normal to severe hypertriglyceridemia, often in the same individual at different time points. Here we provide an updated overview of rare APOA5 variants in hypertriglyceridemia. RECENT FINDINGS: Currently, most variants in APOA5 that are considered to be pathogenic according to guidelines of the American College of Medical Genetics and Genomics are those resulting in premature termination codons. There are minimal high quality functional data on the impact of most rare APOA5 missense variants; many are considered as variants of unknown or uncertain significance. Furthermore, particular common polymorphisms of APOA5 , such as p.Ser19Trp and p.Gly185Cys in Caucasian and Asian populations, respectively, are statistically overrepresented in hypertriglyceridemia cohorts and are sometimes misattributed as being causal for chylomicronemia, when they are merely risk alleles for hypertriglyceridemia. SUMMARY: Both biallelic and monoallelic LOF variants in APOA5 are associated with severe hypertriglyceridemia, although the biochemical phenotype in the monoallelic state is highly variable and is often exacerbated by secondary factors. Currently, with few exceptions, the principal definitive mechanism for APOA5 pathogenicity is through premature truncation. The pathogenic mechanisms of most missense variants in APOA5 remain unclear and require additional functional experiments or family studies.

Prevalence of non-alcoholic fatty liver disease and liver fibrosis in a general population cohort from Argentina.

INTRODUCTION AND OBJECTIVES: South America is one of the regions with the highest rates of non-alcoholic fatty liver disease (NAFLD). This study aimed to assess the prevalence and severity of NAFLD in suburban Argentina. PATIENTS AND METHODS: The study involved a general community cohort of 993 subjects evaluated sequentially with a comprehensive lifestyle questionnaire, laboratory testing, abdominal ultrasound (US) and transient elastography with XL probe. NAFLD was diagnosed according to standard criteria. RESULTS: The prevalence of NAFLD by the US was 37.2% (326/875) overall, 50.3% in subjects with overweight/obesity, 58.6% with hypertriglyceridemia, 62.3% with diabetes/hyperglycemia and 72.1% with all three risk factors. Male gender (OR 1.42, 95% CI 1.03-1.47, p = 0.029), age (50-59 years: OR 1.98, 95 CI 1.16-3.39, p = 0.013 and ≥60 years: OR 1.86, 95% CI 1.13-3.09, p = 0.015), BMI (25-29: OR 2.87, 95% CI 1.86-4.51, p<0.001 and ≥30: OR 9.57, 95% CI 6.14-15.20, p<0.001), diabetes/hyperglycemia (OR 1.65, 95% CI 1.05-2.61, p = 0.029) and hypertriglyceridemia (OR 1.73, 95% CI 1.20-2.48, p = 0.002) were independent predictors of NAFLD. Among patients with steatosis, 22.2% (69/311) had ≥F2 fibrosis (overweight 25%, hypertriglyceridemia 32%, diabetes/hyperglycemia 34%). BMI (OR 5.22, 95% CI 2.64-11.74, p<0.001), diabetes/hyperglycemia (OR 2.12, 95% CI 1.05-4.29, p = 0.04) and hypertriglyceridemia (OR 1.94, 95% CI 1.03-3.68, p = 0.040) were independent predictors of liver fibrosis. CONCLUSIONS: This general population study from Argentina showed a high prevalence of NAFLD. Significant liver fibrosis was present in 22% of subjects with NAFLD. This information adds to the existing knowledge of NAFLD epidemiology in Latin America.

Loss of myeloid lipoprotein lipase exacerbates adipose tissue fibrosis with collagen VI deposition and hyperlipidemia in leptin-deficient obese mice.

During obesity, tissue macrophages increase in number and become proinflammatory, thereby contributing to metabolic dysfunction. Lipoprotein lipase (LPL), which hydrolyzes triglyceride in lipoproteins, is secreted by macrophages. However, the role of macrophage-derived LPL in adipose tissue remodeling and lipoprotein metabolism is largely unknown. To clarify these issues, we crossed leptin-deficient Lepob/ob mice with mice lacking the Lpl gene in myeloid cells (Lplm-/m-) to generate Lplm-/m-;Lepob/ob mice. We found the weight of perigonadal white adipose tissue (WAT) was increased in Lplm-/m-;Lepob/ob mice compared with Lepob/ob mice due to substantial accumulation of both adipose tissue macrophages and collagen that surrounded necrotic adipocytes. In the fibrotic epidydimal WAT of Lplm-/m-;Lepob/ob mice, we observed an increase in collagen VI and high mobility group box 1, while α-smooth muscle cell actin, a marker of myofibroblasts, was almost undetectable, suggesting that the adipocytes were the major source of the collagens. Furthermore, the adipose tissue macrophages from Lplm-/m-;Lepob/ob mice showed increased expression of genes related to fibrosis and inflammation. In addition, we determined Lplm-/m-;Lepob/ob mice were more hypertriglyceridemic than Lepob/ob mice. Lplm-/m-;Lepob/ob mice also showed slower weight gain than Lepob/ob mice, which was primarily due to reduced food intake. In conclusion, we discovered that the loss of myeloid Lpl led to extensive fibrosis of perigonadal WAT and hypertriglyceridemia. In addition to illustrating an important role of macrophage LPL in regulation of circulating triglyceride levels, these data show that macrophage LPL protects against fibrosis in obese adipose tissues.

A Clinical Case of a Homozygous Deletion in the APOA5 Gene with Severe Hypertriglyceridemia.

Background: Hypertriglyceridemia (HTG) is one of the most common forms of lipid metabolism disorders. The leading clinical manifestations are pancreatitis, atherosclerotic vascular lesions, and the formation of eruptive xanthomas. The most severe type of HTG is primary (or hereditary) hypertriglyceridemia, linked to pathogenic genetic variants in LPL, APOC2, LMF1, and APOA5 genes. Case: We present a clinical case of severe primary hypertriglyceridemia (TG level > 55 mmol/L in a 4-year-old boy) in a consanguineous family. The disease developed due to a previously undescribed homozygous deletion in the APOA5 gene (NM_052968: c.579_592delATACGCCGAGAGCC p.Tyr194Gly*68). We also evaluate the clinical significance of a genetic variant in the LPL gene (NM_000237.2: c.106G>A (rs1801177) p.Asp36Asn), which was previously described as a polymorphism. In one family, we also present a different clinical significance even in heterozygous carriers: from hypertriglyceridemia to normotriglyceridemia. We provide evidence that this heterogeneity has developed due to polymorphism in the LPL gene, which plays the role of an additional trigger. Conclusions: The homozygous deletion of the APOA5 gene is responsible for the severe hypertriglyceridemia, and another SNP in the LPL gene worsens the course of the disease.

Poloxamer 407 Induces Hypertriglyceridemia but Decreases Atherosclerosis in Ldlr-/- Mice.

BACKGROUND: Hypertriglyceridemia (HTG) increases the risk for atherosclerotic cardiovascular disease, but underlying mechanisms are incompletely understood. Circulating monocytes play an important role in atherogenesis by infiltrating arterial walls, where they differentiate into macrophages. We tested the hypothesis that HTG is mechanistically linked to atherogenesis by altering the monocyte phenotype and infiltration into atherosclerotic lesions in a model of diet-induced atherogenesis in Ldlr-/- mice. METHODS: HTG was induced in male Ldlr-/- mice, fed a Western, high-fat high-cholesterol diet, by daily injection of poloxamer 407 (P407), a lipoprotein lipase inhibitor, for seven weeks. Atherosclerosis, monocyte phenotypes, and monocyte migration into atherosclerotic lesions were determined by well-validated methods. RESULTS: Compared with the saline control, P407 injection in Ldlr-/- mice rapidly induced profound and persistent HTG, modestly elevated plasma cholesterol levels, and increased levels of triglyceride and cholesterol carried in very-low-density lipoprotein and low-density lipoprotein. Unexpectedly, mice receiving P407 versus saline control showed less atherosclerosis. Following induction of HTG by P407, CD36+ (also CD11c+), but not CD36- (CD11c-), monocytes showed early increases in lipid accumulation, but the number of CD36+ (not CD36-) monocytes was dramatically decreased afterwards in the circulation until the end of the test. Concurrently, CD36+ (CD11c+) monocyte migration into atherosclerotic lesions was also reduced in mice receiving P407 versus controls. CONCLUSIONS: P407 induced severe HTG, but reduced atherosclerosis, in Ldlr-/- mice, possibly because of profound reductions of circulating CD36+ (CD11c+) monocytes, leading to decreased monocyte migration into atherosclerotic lesions.

Heparin binding triggers human VLDL remodeling by circulating lipoprotein lipase: Relevance to VLDL functionality in health and disease.

Hydrolysis of VLDL triacylglycerol (TG) by lipoprotein lipase (LpL) is a major step in energy metabolism and VLDL-to-LDL maturation. Most functional LpL is anchored to the vascular endothelium, yet a small amount circulates on TG-rich lipoproteins. As circulating LpL has low catalytic activity, its role in VLDL remodeling is unclear. We use pre-heparin plasma and heparin-sepharose affinity chromatography to isolate VLDL fractions from normolipidemic, hypertriglyceridemic, or type-2 diabetic subjects. LpL is detected only in the heparin-bound fraction. Transient binding to heparin activates this VLDL-associated LpL, which hydrolyses TG, leading to gradual VLDL remodeling into IDL/LDL and HDL-size particles. The products and the timeframe of this remodeling closely resemble VLDL-to-LDL maturation in vivo. Importantly, the VLDL fraction that does not bind heparin is not remodeled. This relatively inert LpL-free VLDL is rich in TG and apoC-III, poor in apoE and apoC-II, shows impaired functionality as a substrate for the exogenous LpL or CETP, and likely has prolonged residence time in blood, which is expected to promote atherogenesis. This non-bound VLDL fraction increases in hypertriglyceridemia and in type-2 diabetes but decreases upon diabetes treatment that restores the glycemic control. In stark contrast, heparin binding by LDL increases in type-2 diabetes triggering pro-atherogenic LDL modifications. Therefore, the effects of heparin binding are associated negatively with atherogenesis for VLDL but positively for LDL. Collectively, the results reveal that binding to glycosaminoglycans initiates VLDL remodeling by circulating LpL, and suggest heparin binding as a marker of VLDL functionality and a readout for treatment of metabolic disorders.

LLF580, an FGF21 Analog, Reduces Triglycerides and Hepatic Fat in Obese Adults With Modest Hypertriglyceridemia.

PURPOSE: To evaluate the safety and potential efficacy of LLF580, a genetically engineered variant of human fibroblast growth factor-21, for triglyceride lowering, weight loss, and hepatic fat reduction. METHODS: A multicenter, double-blind, parallel design trial in obese, mildly hypertriglyceridemic adults randomized (1:1) to LLF580 300 mg or placebo subcutaneously every 4 weeks for 3 doses. RESULTS: Of 64 randomized study participants, 61 (mean ± SD: age 45 ± 11 years, 49% male, 80/15/5% Caucasian/African American/other, body mass index 36.1 ± 3.8 kg/m2) received LLF580 (n = 30) or placebo (n = 31) at 7 research sites in the United States. LLF580 lowered serum triglycerides by 54% (least square mean placebo adjusted change from baseline), total cholesterol 7%, low-density lipoprotein cholesterol 12%, and increased high-density lipoprotein cholesterol 36% compared with placebo (all P < 0.001) over 12 weeks. Substantial reduction of liver fat of 52% over placebo (P < 0.001) was also demonstrated in the setting of improved liver function tests including alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase, the composite enhanced liver fibrosis score, and N-terminal type III collagen propeptide (all P < 0.05). Insulin and C-peptide levels and insulin resistance by homeostatic model assessment for insulin resistance were all lower, and adiponectin higher with LLF580 treatment compared with placebo, whereas fasting glucose and glycated hemoglobin were unchanged. Reductions in biomarkers of bone formation without differences in markers of bone resorption were observed. LLF580 was generally safe and well tolerated, except for higher incidence of generally mild to moderate gastrointestinal adverse effects. CONCLUSIONS: In obese, mildly hypertriglyceridemic adults, LLF580 was generally safe and demonstrated beneficial effects on serum lipids, liver fat, and biomarkers of liver injury, suggesting it may be effective for treatment of select metabolic disorders including hypertriglyceridemia and nonalcoholic fatty liver disease. Assessments of longer term safety and efficacy are warranted. CLINICALTRIALS.GOV IDENTIFIER: NCT03466203.

Hexosaminidase A (HEXA) regulates hepatic sphingolipid and lipoprotein metabolism in mice.

Hexosaminidase A (HexA), a heterodimer consisting of HEXA and HEXB, converts the ganglioside sphingolipid GM2 to GM3 by removing a terminal N-acetyl-d-galactosamine. HexA enzyme deficiency in humans leads to GM2 accumulation in cells, particularly in neurons, and is associated with neurodegeneration. While HexA and sphingolipid metabolism have been extensively investigated in the context of neuronal lipid metabolism, little is known about the metabolic impact of HexA and ganglioside degradation in other tissues. Here, we focussed on the role of HexA in the liver, which is a major regulator of systemic lipid metabolism. We find that hepatic Hexa expression is induced by lipid availability and increased in the presence of hepatic steatosis, which is associated with increased hepatic GM3 content. To assess the impact of HEXA on hepatic lipid metabolism, we used an adeno-associated virus to overexpress HEXA in the livers of high-fat diet fed mice. HEXA overexpression was associated with increased hepatic GM3 content and increased expression of enzymes involved in the degradation of glycated sphingolipids, ultimately driving sphingomyelin accumulation in the liver. In addition, HEXA overexpression led to substantial proteome remodeling in cell surface lipid rafts, which was associated with increased VLDL processing and secretion, hypertriglyceridemia and ectopic lipid accumulation in peripheral tissues. This study established an important role of HEXA in modulating hepatic sphingolipid and lipoprotein metabolism.

Repetitive spikes of glucose and lipid induce senescence-like phenotypes of bone marrow stem cells through H3K27me3 demethylase-mediated epigenetic regulation.

Bone marrow-derived endothelial progenitor cells (EPCs) contribute to endothelial repair and angiogenesis. Reduced number of circulating EPCs is associated with future cardiovascular events. We tested whether dysregulated glucose and/or triglyceride (TG) metabolism has an impact on EPC homeostasis. The analysis of metabolic factors associated with circulating EPC number in humans revealed that postprandial hyperglycemia is negatively correlated with circulating EPC number, and this correlation appears to be further enhanced in the presence of postprandial hypertriglyceridemia (hTG). We therefore examined the effect of glucose/TG spikes on bone marrow lineage-sca-1+ c-kit+ (LSK) cells in mice, because primitive EPCs reside in bone marrow LSK fraction. Repetitive glucose + lipid (GL) spikes, but not glucose (G) or lipid (L) spikes alone, induced senescence-like phenotypes of LSK cells, and this phenomenon was reversible after cessation of GL spikes. G spikes and GL spikes differentially affected transcriptional program of LSK cell metabolism and differentiation. GL spikes upregulated a histone H3K27 demethylase JMJD3, and inhibition of JMJD3 eliminated GL spikes-induced LSK cell senescence-like phenotypes. These observations suggest that postprandial glucose/TG dysmetabolism modulate transcriptional regulation in LSK cells through H3K27 demethylase-mediated epigenetic regulation, leading to senescence-like phenotypes of LSK cells, reduced number of circulating EPCs, and development of atherosclerotic cardiovascular disease.NEW & NOTEWORTHY Combination of hyperglycemia and hypertriglyceridemia is associated with increased risk of atherosclerotic cardiovascular disease. We found that 1) hypertriglyceridemia may enhance the negative impact of hyperglycemia on circulating EPC number in humans and 2) metabolic stress induced by glucose + triglyceride spikes in mice results in senescence-like phenotypes of bone marrow stem/progenitor cells via H3K27me3 demethylase-mediated epigenetic regulation. These findings have important implications for understanding the pathogenesis of atherosclerotic cardiovascular disease in patients with T2DM.

Determinants of the postprandial triglyceride response to a high-fat meal in healthy overweight and obese adults.

BACKGROUND: Dyslipidemia is a feature of impaired metabolic health in conjunction with impaired glucose metabolism and central obesity. However, the contribution of factors to postprandial lipemia in healthy but metabolically at-risk adults is not well understood. We investigated the collective contribution of several physiologic and lifestyle factors to postprandial triglyceride (TG) response to a high-fat meal in healthy, overweight and obese adults. METHODS: Overweight and obese adults (n = 35) underwent a high-fat meal challenge with blood sampled at fasting and hourly in the 4-hour postprandial period after a breakfast containing 50 g fat. Incremental area under the curve (iAUC) and postprandial magnitude for TG were calculated and data analyzed using a linear model with physiologic and lifestyle characteristics as explanatory variables. Model reduction was used to assess which explanatory variables contributed most to the postprandial TG response. RESULTS: TG responses to a high-fat meal were variable between individuals, with approximately 57 % of participants exceeded the nonfasting threshold for hypertriglyceridemia. Visceral adiposity was the strongest predictor of TG iAUC (ß = 0.53, p = 0.01), followed by aerobic exercise frequency (ß = 0.31, p = 0.05), insulin resistance based on HOMA-IR (ß = 0.30, p = 0.04), and relative exercise intensity at which substrate utilization crossover occurred (ß = 0.05, p = 0.04). For postprandial TG magnitude, visceral adiposity was a strong predictor (ß = 0.43, p < 0.001) followed by aerobic exercise frequency (ß = 0.23, p = 0.01), and exercise intensity for substrate utilization crossover (ß = 0.53, p = 0.01). CONCLUSIONS: Postprandial TG responses to a high-fat meal was partially explained by several physiologic and lifestyle characteristics, including visceral adiposity, insulin resistance, aerobic exercise frequency, and relative substrate utilization crossover during exercise. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04128839 , Registered 16 October 2019 - Retrospectively registered.

Case Studies in Pediatric Lipid Disorders and Their Management.

CONTEXT: Identification of modifiable risk factors, including genetic and acquired disorders of lipid and lipoprotein metabolism, is increasingly recognized as an opportunity to prevent premature cardiovascular disease (CVD) in at-risk youth. Pediatric endocrinologists are at the forefront of this emerging public health concern and can be instrumental in beginning early interventions to prevent premature CVD-related events during adulthood. AIM: In this article, we use informative case presentations to provide practical approaches to the management of pediatric dyslipidemia. CASES: We present 3 scenarios that are commonly encountered in clinical practice: isolated elevation of low-density lipoprotein cholesterol (LDL-C), combined dyslipidemia, and severe hypertriglyceridemia. Treatment with statin is indicated when the LDL-C is ≥190 mg/dL (4.9 mmol/L) in children ≥10 years of age. For LDL-C levels between 130 and 189 mg/dL (3.4-4.89 mmol/L) despite dietary and lifestyle changes, the presence of additional risk factors and comorbid conditions would favor statin therapy. In the case of combined dyslipidemia, the primary treatment target is LDL-C ≤130 mg/dL (3.4 mmol/L) and the secondary target non-high-density lipoprotein cholesterol <145 mg/dL (3.7 mmol/L). If the triglyceride is ≥400 mg/dL (4.5 mmol/L), prescription omega-3 fatty acids and fibrates are considered. In the case of triglyceride >1000 mg/dL (11.3 mmol/L), dietary fat restriction remains the cornerstone of therapy, even though the landscape of medications is changing. CONCLUSION: Gene variants, acquired conditions, or both are responsible for dyslipidemia during childhood. Extreme elevations of triglycerides can lead to pancreatitis. Early identification and management of dyslipidemia and cardiovascular risk factors is extremely important.

A case of tamoxifen-induced hypertriglyceridemia monitoring the changes in lipoprotein fractions over time.

BACKGROUND: Tamoxifen, which is one of the selective estrogen receptor modulators (SERMs), can bring out life-threatening complication, e.g. hypertriglyceridemia-induced acute pancreatitis, although it is rare. We precisely report changes in lipoprotein metabolism before and after tamoxifen discontinuation because there have been few reports of it. CASE PRESENTATION: 47-year-old premenopausal woman with dyslipidemia, type 2 diabetes, nonalcoholic fatty liver disease and chronic kidney disease was prescribed tamoxifen as adjuvant therapy after operation of breast cancer. She experienced severe tamoxifen-induced hypertriglyceridemia several months after dosing tamoxifen. Before cessation of tamoxifen, lipoprotein fraction test revealed marked stagnation of VLDL and IDL metabolisms, resulting in severe hypertriglyceridemia (serum triglyceride level was 1881 mg/dL). Seven days after tamoxifen withdrawal, lipoprotein fraction test showed that the metabolisms of endogenous lipoproteins were changed drastically. CONCLUSIONS: From these results, we confirmed that tamoxifen certainly changes lipoprotein metabolism through suppression of post-heparin lipolytic activity. It is very important to evaluate the balance between benefit and risk before dosing tamoxifen and survey lipid profiles constantly during treatment to avoid life-threatening complication when prescription of tamoxifen is planned.

Familial hypertriglyceridemia: an entity with distinguishable features from other causes of hypertriglyceridemia.

BACKGROUND: Familial hypertriglyceridemia (FHTG) is a partially characterized primary dyslipidemia which is frequently confused with other forms hypertriglyceridemia. The aim of this work is to search for specific features that can help physicians recognize this disease. METHODS: This study included 84 FHTG cases, 728 subjects with common mild-to-moderate hypertriglyceridemia (CHTG) and 609 normotriglyceridemic controls. All subjects underwent genetic, clinical and biochemical assessments. A set of 53 single nucleotide polymorphisms (SNPs) previously associated with triglycerides levels, as well as 37 rare variants within the five main genes associated with hypertriglyceridemia (i.e. LPL, APOC2, APOA5, LMF1 and GPIHBP1) were analyzed. A panel of endocrine regulatory proteins associated with triglycerides homeostasis were compared between the FHTG and CHTG groups. RESULTS: Apolipoprotein B, fibroblast growth factor 21(FGF-21), angiopoietin-like proteins 3 (ANGPTL3) and apolipoprotein A-II concentrations, were independent components of a model to detect FHTG compared with CHTG (AUC 0.948, 95%CI 0.901-0.970, 98.5% sensitivity, 92.2% specificity, P < 0.001). The polygenic set of SNPs, accounted for 1.78% of the variance in triglyceride levels in FHTG and 6.73% in CHTG. CONCLUSIONS: The clinical and genetic differences observed between FHTG and CHTG supports the notion that FHTG is a unique entity, distinguishable from other causes of hypertriglyceridemia by the higher concentrations of insulin, FGF-21, ANGPTL3, apo A-II and lower levels of apo B. We propose the inclusion of these parameters as useful markers for differentiating FHTG from other causes of hypertriglyceridemia.

Pemafibrate decreases triglycerides and small, dense LDL, but increases LDL-C depending on baseline triglycerides and LDL-C in type 2 diabetes patients with hypertriglyceridemia: an observational study.

BACKGROUND: Pemafibrate, a selective PPARα modulator, has the beneficial effects on serum triglycerides (TGs) and very low density lipoprotein (VLDL), especially in patients with diabetes mellitus or metabolic syndrome. However, its effect on the low density lipoprotein cholesterol (LDL-C) levels is still undefined. LDL-C increased in some cases together with a decrease in TGs, and the profile of lipids, especially LDL-C, during pemafibrate administration was evaluated. METHODS: Pemafibrate was administered to type 2 diabetes patients with hypertriglyceridemia. Fifty-one type 2 diabetes patients (mean age 62 ± 13 years) with a high rate of hypertension and no renal insufficiency were analyzed. Pemafibrate 0.2 mg (0.1 mg twice daily) was administered, and serum lipids were monitored every 4-8 weeks from 8 weeks before administration to 24 weeks after administration. LDL-C was measured by the direct method. Lipoprotein fractions were measured by electrophoresis (polyacrylamide gel, PAG), and LDL-migration index (LDL-MI) was calculated to estimate small, dense LDL. RESULTS: Pemafibrate reduced serum TGs, midband and VLDL fractions by PAG. Pemafibrate increased LDL-C levels from baseline by 5.3% (- 3.8-19.1, IQR). Patients were divided into 2 groups: LDL-C increase of > 5.3% (group I, n = 25) and < 5.3% (group NI, n = 26) after pemafibrate. Compared to group NI, group I had lower LDL-C (2.53 [1.96-3.26] vs. 3.36 [3.05-3.72] mmol/L, P = 0.0009), higher TGs (3.71 [2.62-6.69] vs. 3.25 [2.64-3.80] mmol/L), lower LDL by PAG (34.2 [14.5, SD] vs. 46.4% [6.5], P = 0.0011), higher VLDL by PAG (28.2 [10.8] vs. 22.0% [5.2], P = 0.0234), and higher LDL-MI (0.421 [0.391-0.450] vs. 0.354 [0.341-0.396], P < 0.0001) at baseline. Pemafibrate decreased LDL-MI in group I, and the differences between the groups disappeared. These results showed contradictory effects of pemafibrate on LDL-C levels, and these effects were dependent on the baseline levels of LDL-C and TGs. CONCLUSIONS: Pemafibrate significantly reduced TGs, VLDL, midband, and small, dense LDL, but increased LDL-C in diabetes patients with higher baseline TGs and lower baseline LDL-C. Even if pre-dose LDL-C remains in the normal range, pemafibrate improves LDL composition and may reduce cardiovascular disease risk.

Apolipoprotein C-III and cardiovascular diseases: when genetics meet molecular pathologies.

Cardiovascular diseases (CVD) have overtaken infectious diseases and are currently the world's top killer. A quite strong linkage between this type of ailments and elevated plasma levels of triglycerides (TG) has been always noticed. Notably, this risk factor is mired in deep confusion, since its role in atherosclerosis is uncertain. One of the explanations that aim to decipher this persistent enigma was provided by apolipoprotein C-III (apoC-III), a small protein historically recognized as an important regulator of TG metabolism. Preeminently, hundreds of studies have been carried out in order to explore the APOC3 genetic background, as well as to establish a correlation between its variants and dyslipidemia-related disorders, pointing to an earnest predictive power for future outcomes. Among several polymorphisms reported within the APOC3, the SstI site in its 3'-untranslated region (3'-UTR) was the most consistently and robustly associated with an increased CVD risk. As more genetic data supporting its importance in cardiovascular events aggregate, it was declared, correspondingly, that apoC-III exerts various atherogenic effects, either by intervening in the function and catabolism of many lipoproteins, or by inducing endothelial inflammation and smooth muscle cells (SMC) proliferation. This review was designed to shed the light on the structural and functional aspects of the APOC3 gene, the existing association between its SstI polymorphism and CVD, and the specific molecular mechanisms that underlie apoC-III pathological implications. In addition, the translation of all these gathered knowledges into preventive and therapeutic benefits will be detailed too.

A Comprehensive Update on the Chylomicronemia Syndrome.

The chylomicronemia syndrome is characterized by severe hypertriglyceridemia and fasting chylomicronemia and predisposes affected individuals to acute pancreatitis. When due to very rare monogenic mutations in the genes encoding the enzyme, lipoprotein lipase, or its regulators, APOC2, APOA5, GPIHBP1, and LMF1, it is referred to as the familial chylomicronemia syndrome. Much more frequently, the chylomicronemia syndrome results from a cluster of minor genetic variants causing polygenic hypertriglyceridemia, which is exacerbated by conditions or medications which increase triglyceride levels beyond the saturation point of triglyceride removal systems. This situation is termed the multifactorial chylomicronemia syndrome. These aggravating factors include common conditions such as uncontrolled diabetes, overweight and obesity, alcohol excess, chronic kidney disease and pregnancy and several medications, including diuretics, non-selective beta blockers, estrogenic compounds, corticosteroids, protease inhibitors, immunosuppressives, antipsychotics, antidepressants, retinoids, L-asparaginase, and propofol. A third uncommon cause of the chylomicronemia syndrome is familial forms of partial lipodystrophy. Development of pancreatitis is the most feared complication of the chylomicronemia syndrome, but the risk of cardiovascular disease as well as non-alcoholic steatohepatitis is also increased. Treatment consists of dietary fat restriction and weight reduction combined with the use of triglyceride lowering medications such as fibrates, omega 3 fatty acids and niacin. Effective management of aggravating factors such as improving diabetes control, discontinuing alcohol and replacing or reducing the dose of medications that raise triglyceride levels is essential. Importantly, many if not most cases of the chylomicronemia syndrome can be prevented by effective identification of polygenic hypertriglyceridemia in people with conditions that increase its likelihood or before starting medications that may increase triglyceride levels. Several new pharmacotherapeutic agents are being tested that are likely to considerably improve treatment of hypertriglyceridemia in people at risk.

The association between triglycerides and ectopic fat obesity: An inverted U-shaped curve.

BACKGROUND: Ectopic fat obesity and triglycerides are risk factors for diabetes and multiple cardiovascular diseases. However, there have been limited studies on the association between triglycerides and ectopic fat obesity. The purpose of this study was to explore the association between triglycerides and ectopic fat obesity. METHODS AND RESULTS: In this cross-sectional study, we retrospectively analyzed 15464 adult participants recruited by Murakami Memorial Hospital (8430 men and 7034 women, average age of 43.71 ± 8.90). All patients were divided into two groups according to the threshold used to diagnose hypertriglyceridemia. The logistic regression model was used to analyze the association between triglycerides and the risk of ectopic fat obesity, and the generalized additive model was used to identify the nonlinear association. In this study population, the prevalence of ectopic fat obesity was 17.73%. After adjusting other covariables, triglycerides were positively correlated with the risk of ectopic fat obesity (OR: 1.54, 95% CI:1.41-1.69, P<0.0001). Through smooth curve fitting, we found that there was an inverted U-shaped curve association between triglycerides and ectopic fat obesity. This association remained unchanged even if the adjusted covariables were removed from the model, and the inflection point of the curve was 3.98. When triglyceride levels were ≤3.98, triglycerides were positively correlated with the risk of ectopic fat obesity (OR:1.784, 95% CI:1.611-1.975, P<0.0001). When triglyceride levels were >3.98 (right side of the inflection point), there was a negative correlation (OR:0.519, 95% CI:0.333-0.810, P = 0.0039). CONCLUSIONS: Our research showed that there is a significant association between triglycerides and ectopic fat obesity. This relation is not a simple linear relationship but instead an inverted U-shaped curve association.