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Intestinal remnant chylomicrons (CMs) are involved in cardiovascular residual risk and the atherogenic process. Microsomal triglyceride transfer protein (MTTP) catalyzes the assembly of lipids to apolipoprotein B48, generating CMs. Dysbiosis could alter this behavior. This study investigated the chemical composition of CMs and their associations with intestinal MTTP and gut fat depots in a diet-induced dysbiosis animal model. Male Wistar rats were fed either a standard diet (control, n=10) or a high-fat high-sucrose diet (HFSD, n=10) for 14 weeks. Measurements included serum glucose, lipid-lipoprotein profile, free fatty acids (FFAs), lipopolysaccharide (LPS) and the Compared to control, HFSD rats showed higher levels of LPS, triglycerides (TGs), non-high-density lipoprotein cholesterol (HDL-C) levels, TG/HDL-C ratio, FFAs, and the F/B ratio. HFSD CMs showed increased TG and phospholipids. TJ proteins levels were lower in the HFSD group, while histological scores showed no differences. CIF was increased in the HFSD group. No significant differences in apoB mRNA were found. MTTP expression was higher in the HFSD group, and directly correlated with CM-TG and inversely correlated with CIF. Our findings imply that gut TG content may constitute an important determinant of the secretion of TG-rich CMs, promoted by MTTP, with increased atherogenic potential. Show less

Given that lipoprotein lipase (LPL) activity assays are not standardized for clinical use, we aimed to define reference values applicable to our clinical setting and identify a cut-off point to help distinguish Familial Chylomicronemia Syndrome from Multifactorial Chylomicronemia Syndrome, particularly in patients with inconclusive genetic findings. We evaluated 28 patients with a history of TG levels above 880 mg/dL (10 mmol/L), and assessed their likelihood of FCS using the Moulin score. LPL activity was measured in post-heparin plasma using a radiometric assay. Thirty normotriglyceridemic controls were used to define reference values. Genetic testing for FCS canonical genes and lipid profile was performed in all sHTG patients. The reference value for LPL activity was 33.3 (18.7-70.3) mIU, with a cut-off of 8.42 mIU (25 % of the median of NTG) to distinguish FCS from MCS. Eighteen patients without genetic variants in canonical genes, a Moulin score <9 and LPL activity >25 % of NTG, were classified as MCS. Five genetic diagnosed FCS patients, with a Moulin score>10 presented LPL activity <25 % of NTG. Four patients with inconclusive genetic results and a Moulin score>10 were classified as FCS according to LPL activity. LPL activity in patients with sHTG could be useful for differentiating FCS and MCS, particularly in patients with ambiguous or negative genetic findings, highlighting the need for specialized laboratory support in diagnostics. Show less

Epicardial adipose tissue (EAT) contributes to coronary artery disease (CAD). EAT presents a specific lipidomic signature, showing increased ceramides and other proinflammatory lipids content. Besides, LPL (lipoprotein lipase) activity in EAT would contribute to its expansion, supplying fatty acids to the tissue. Our aim was to evaluate the relations between LPL activity, regulators of LPL, and ceramides in EAT from CAD patients. We studied patients undergoing coronary bypass graft (CAD, n=25) and patients without CAD (no CAD, n=14). EAT and subcutaneous AT (SAT) were obtained, tissue LPL activity and its regulator's expression (ANGPTL4, GPIHBP1 [glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1], and PPARγ [peroxisomal proliferator-activated receptor γ]) were assessed. Tissue lipidomes were evaluated by UHPLC-MS, in positive and negative ionization modes. LPL activity was higher in EAT from CAD ( The association between LPL activity, total ceramide, and the atherogenic ceramide ratios highlights the importance of the enzyme and these bioactive lipids contributing to the different metabolic profile of EAT in CAD. Show less

Epicardial adipose tissue (EAT) is a visceral AT, surrounding myocardium and coronary arteries. Its volume is higher in Type 2 diabetic (DM2) patients, associated with cardiovascular disease risk. Lipoprotein lipase (LPL) hydrolyses triglycerides (TG) from circulating lipoproteins, supplying fatty acids to AT, contributing to its expansion. We aimed to evaluate LPL expression and activity in EAT from DM2 and no DM2 patients, and its regulators ANGPTL4, GPIHBP1 and PPARγ levels, together with VLDLR expression and EAT LPL association with VLDL characteristics. We studied patients undergoing coronary by-pass graft (CABG) divided into CABG-DM2 (n = 21) and CABG-noDM2 (n = 29), and patients without CABG (No CABG, n = 30). During surgery, EAT and subcutaneous AT (SAT) were obtained, in which LPL activity, gene and protein expression, its regulators and VLDLR protein levels were determined. Isolated circulating VLDLs were characterized. EAT LPL activity was higher in CABG-DM2 compared to CABG-noDM2 and No CABG (p=0.002 and p<0.001) and in CABG-noDM2 compared to No CABG (p=0.02), without differences in its expression. ANGPTL4 levels were higher in EAT from No CABG compared to CABG-DM2 and CABG-noDM2 (p<0.001). GPIHBP1 levels were higher in EAT from CABG-DM2 and CABG-noDM2 compared to No CABG (p= 0.04). EAT from CABG-DM2 presented higher PPARγ levels than CABG-noDM2 and No CABG (p=0.02 and p=0.03). No differences were observed in VLDL composition between groups, although EAT LPL activity was inversely associated with VLDL-TG and TG/protein index (p<0.05). EAT LPL regulation would be mainly post-translational. The higher LPL activity in DM2 could be partly responsible for the increase in EAT volume. Show less

Lipoprotein lipase (LPL) and endothelial lipase (EL) are involved in lipoprotein metabolism. In insulin-resistance, their behavior is altered. Peroxisome proliferator-activated receptors (PPAR) and apoproteins (apo)CII and CIII could be partly responsible for these alterations. To evaluate this response, we assessed Lpl and Lipg expression, protein levels, and enzyme activity in adipose tissue (AT) and heart in an obesity model. Besides, we assessed the role of PPAR and apoC. Male Wistar rats were fed with standard diet (Control, n = 14) or high-fat diet (HFD, n = 14) for 14 weeks. Glucose and lipoprotein profiles were measured. Histological studies were performed in heart and epididymal AT. Lpl and Lipg were assessed by reverse transcription polymerase chain reaction (RT-qPCR), protein levels by Western Blot, and activities by radiometric assays. Cardiac and AT PPAR expression were measured by Western Blot and hepatic Apoc2 and Apoc3 mRNA by RT-qPCR. In HFD, fat deposits were observed in hearts, whereas AT presented a higher adipocyte size. In heart and AT, no differences were found in Lipg mRNA between groups, while AT Lpl mRNA and LPL protein were decreased in HFD, without differences in heart. In both tissues, EL protein levels and activity were increased and inversely associated with decreased LPL activity, being partially responsible for the atherogenic lipoprotein profile in HFD. PPARγ expression in AT was decreased in HFD, without differences in cardiac PPARδ expression and hepatic apoC mRNA. The increase in EL activity could be an alternative pathway for fatty acid release from lipoproteins and uptake in tissues with decreased LPL activity. In AT, PPARγ could be involved in enzyme regulation. Show less