This mechanism explains for the anti-atherosclerotic effect of HDL 41 — However, the specific loading mechanism of miRNAs onto HDL and the biological significance of the process remain to be elucidated. Anti-inflammatory effects In addition to anti-atherosclerotic effects, HDL also has an anti-inflammatory role in macrophages and endothelial cells by inhibiting the expression of adhesion molecules 52 , Anti-thrombotic function HDL exerts vascular protective effects by upregulating endothelial nitric oxide synthase eNOs expression and maintaining the caveolae lipid environment, which eNOs are located in.
HDL can also lower APC protein and thrombomodulin to reduce the formation of thrombin in endothelial cells and exerts an anti-thrombotic effect by inhibiting endothelial cell apoptosis and activities of tissue factors and endothelial cells 55 , The dissociation rate of apolipoproteins that assemble HDL, is lower than that of CE that assembles HDL, and the variability of the dissociation rate is markedly higher than that of the association rate. At present, the mechanisms of apoAI uptake and degradation in the liver are yet to be fully elucidated.
ApoAI but not HDL it filtrated by glomerules and is then internalized and degraded in renal tubular epithelial cells. Cubulin is synthesized by distal renal tubular cells and is located on the apical surface. Cubulin has a high affinity for apoAI and mediates apoAI uptake and degradation by megalin HDL metabolism-associated transcription factors Liver X receptor LXR signaling pathway LXR is a type of ligand which is inducible by transcription factors and is a member of nuclear hormone receptor protein superfamily.
The most potent endogenous LXR agonists are 22 R -hydroxylated cholesterol, 24 S -hydroxylated cholesterol and 24,epoxy cholesterol. Peroxisome proliferator-activated receptor PPAR signaling pathway PPAR is a ligand-inducible transcription factor and belongs to the nuclear receptor family. PPAR and RXR combine to form a heterodimer, and the complex binds to a specific DNA sequence named peroxisome proliferators' response element of the target gene promoter, which can directly regulate the transcription of its downstream genes.
In conclusion, HDL are markedly heterogenous and intricate particles. J Clin Invest. Arterioscler Thromb Vasc Biol. J Lipid Res. Clin Chem. Pattern B has been associated by some with a higher risk for coronary heart disease. According to one study, sizes Tests to measure these LDL subtype patterns have been more expensive and not widely available, so the common lipid profile test is used more often.
As a result from free radical attack, both lipid and protein parts of LDL can be oxidized in the vascular wall. Besides the oxidative reactions taking place in vascular wall, oxidized lipids in LDL can also be derived from oxidized dietary lipids.
The study protocol was reviewed and approved by an institutional ethical review committee. Written informed consent was obtained from all the subjects before examination. In all, consecutive subjects, who were restricted to men and postmenopausal women over 20 years of age, were analyzed in the present study. All the subjects were histologically confirmed as having NAFLD based on the liver biopsy findings, and the diagnoses were further confirmed in accordance with the categories defined by Matteoni et al.
In the absence of exogenous free fatty acid, the radiolabeled cholesterol was recovered in both the LDL and the high density lipoprotein HDL regions. Incubation with oleic acid did not cause an increase in the total amount of radiolabeled lipid or protein secreted.
J Cardiol. At present, the mechanisms of apoAI uptake and degradation in the liver are yet to be fully elucidated.
The liver is a major source of the plasma lipoproteins; however, direct studies of the regulation of lipoprotein synthesis and secretion by human liver are lacking. Nat Chem Biol. Nat Genet.