China
Africa
Explore chapters and articles related to this topic
ABC Transporters, Organic Solute Carriers and Drug Metabolising Enzymes in Bile Duct Epithelial Cells
Published in Gianfranco Alpini, Domenico Alvaro, Marco Marzioni, Gene LeSage, Nicholas LaRusso, The Pathophysiology of Biliary Epithelia, 2020
The ileal apical sodium-dependent bile salt transporter ASBT is expressed in the apical domain of cholangiocytes. The ASBT gene is transcriptionally regulated by HNF1a and PPARa. PPARa is a member of the peroxisomal proliferator activator receptor family. Inflammation increases PPARγ and this may interfere with PPARa binding, resulting in a down-regulation of ASBT expression.56 This occurs in the ileum. Whether this also occurs in bile duct epithelium needs to be studied. Down-regulation of ASBT in cholangiocytes would decrease the intrahepatic cycling of bile salts and, as a consequence, reduce the bile acid flux through hepatocytes. This may be an adaptive response in liver disease but this would occur at the cost of reducing the bile acid-dependent bile flow.
Mitochondrial Dysfunction and Oxidative Stress in the Pathogenesis of Metabolic Syndrome
Published in Shamim I. Ahmad, Handbook of Mitochondrial Dysfunction, 2019
FA derivatives from lipolysis, lipogenesis or FA catabolism are ligands of PPARa. Free fatty acids, including long-chain polyunsaturated FAs (LCPUFAs) and n-3 LCPUFAs, bind and activate the PPAR signaling to regulate the transcription of a cluster of genes involved in lipid and lipoprotein metabolism, FA β-oxidation in tissues with high oxidative rates, such as heart, liver, and muscle. Substrates of acyl-CoA oxidase 1 (ACOX1), the first rate-limiting peroxisomal β-oxidation enzyme, may also serve as PPARα agonists. Hydrolysis of hepatic intracellular triglyceride also yields lipid ligands for PPARa83. A range of synthetic PPARα agonists, including gemfibrozil, fenofibrate and ciprofibrate, have been synthesized and used in the treatment of primary hypertriglyceridemia or complexed dyslipidaemia84 in clinical.
Respiratory System
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Tom P. McKevitt, David J. Lewis
With some orally delivered drugs, multifocal foamy macrophage aggregates appear scattered throughout the parenchyma. This effect, which often becomes more evident in the 2-year oncogenicity studies, has been seen in rats with peroxisome proliferator-activated receptor alpha (PPARα) agonists such as clofibrate and nafenopin, a PPARδ agonist, a p38 kinase inhibitor, and an iNOS inhibitor (Fringes et al. 1988a,b,c). These compounds do not have a cationic amphiphilic drug (CAD)-like structure; hence, the lesions were not consistent with PLO (discussed later). Similar changes were not seen in the corresponding mouse studies or the 9-month dog or nonhuman primate studies. The macrophages were not associated with any other inflammatory cell infiltration.
Protective effect of Qingluotongbi formula against Tripterygium wilfordii induced liver injury in mice by improving fatty acid β-oxidation and mitochondrial biosynthesis
Published in Pharmaceutical Biology, 2023
Jie Zhou, Ming Li, Zhichao Yu, Changqing Li, Lingling Zhou, Xueping Zhou
Transcriptional regulation is an important way to regulate metabolic processes (Desvergne et al. 2006). Peroxisome proliferator-activated receptor alpha (PPARα), a member of nuclear receptor superfamily, is the master regulator of energy metabolism and lipid catabolism in the liver (Kersten and Stienstra 2017). Previous studies showed that the suppression of PPARα is linked to the hepatotoxic mechanisms of Tripterygium glycosides tablets and Tripterygium wilfordii tablets, two preparations of TW (Dai et al. 2022). PPARα activation can alleviate triptolide-induced liver injury in mice (Hu et al. 2019). The transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) controls multiple hepatic metabolic pathways (Duan et al. 2022), and acts as a coactivator of PPARα to coordinately regulate the transcription of genes related to fatty acid oxidation and mitochondrial biogenesis (Vega et al. 2000). PPARα/PGC-1α pathway plays a central role in the regulation of cellular metabolism (Cheng et al. 2018). The activation of PPARα/PGC-1α can improve mitochondrial function (Kelly and Scarpulla 2004) and reduce lipotoxicity by enhancing lipid metabolism (Kim et al. 2022). We therefore speculate that the hepatic protective effect of QLT is probably related to the PPARα/PGC-1α pathway.
PPAR Receptors Expressed from Vectors Containing CMV Promoter Can Enhance Self-Transcription in the Presence of Fatty Acids from CLA-Enriched Egg Yolks—A Novel Method for Studies of PPAR Ligands
Published in Nutrition and Cancer, 2020
Aneta A. Koronowicz, Adam Master, Paula Banks, Ewelina Piasna-Słupecka, Dominik Domagała, Mariola Drozdowska, Teresa Leszczyńska
Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors belonging to the steroid hormone nuclear receptor superfamily. Initially, PPARs were first described as nuclear receptors for synthetic substances that induced the proliferation of peroxisomes. Shortly after, it was realized that many natural and synthetic substances act selectively through these receptors (1) and that in fact, PPARs encompass a group of three main protein isoforms PPARα, PPARβ/δ, and PPARγ (2) encoded by PPARA, PPARD, and PPARG genes. All these transcription factors are composed of four functional domains including an N-terminal A/B domain (AF1, containing activation function 1), a DNA-binding domain (DBD) containing two zinc fingers, a hinge domain, and a C-terminal ligand-binding domain (LBD, containing activation function 2, AF2). DBD of all PPAR isoforms can bind to the same peroxisome proliferator-activated receptor response element (PPRE) that are specific DNA sequences of the typical consensus core recognition motif AGGTCANAGGTCA (DR1), however, some non-canonical PPREs have been described (3). Apart from binding of ligands, PPAR LBD allows for heterodimerization with other nuclear receptors including retinoid X receptor (RXR) and this complex subsequently recruits corepressors or coactivators, to regulate the expression of target genes responding to receptors liganded by various small lipophilic ligands (4).
Targeting apoC-III and ANGPTL3 in the treatment of hypertriglyceridemia
Published in Expert Review of Cardiovascular Therapy, 2020
N.S. Nurmohamed, G.M. Dallinga – Thie, E.S.G. Stroes
In HTG, the treatment consists of two goals: reduce residual CVD risk and prevent acute pancreatitis; the latter is particularly important in severe HTG. During the last decades, multiple pharmacological strategies have been explored to effectively lower TG levels. Statins are the first choice of treatment to lower CVD risk in all hyperlipidemias, resulting in a reduction of plasma TG levels by 10–20% [20]. Fibrates currently are the most potent TG-lowering agents, achieving a TG lowering up to 50%, depending on baseline TG levels [20]. Large randomized clinical trials (RCT) have shown at best a modest effect of fibrates on CVD risk, evident in post hoc analyses of patients with elevated TG levels or when used without concomitant statin use [21–26]. Classic fibrates can also be associated with adverse effects regarding liver and renal function [27]. Currently, pemafibrate, a selective fibrate targeting peroxisome proliferator-activated receptor alpha (PPARα) with a more favorable side-effect profile, has entered a phase III outcomes study [28]. Its safety and efficacy was already extensively evaluated [29–32], whereas the PROMINENT trial will now provide results on CVD outcomes in primary prevention patients with diabetes [33].