title: The interrelationship between bile acid and vitamin A homeostasis.
abstract: Vitamin A is a fat-soluble vitamin important for vision, reproduction, embryonic development, cell differentiation, epithelial barrier function and adequate immune responses. Efficient absorption of dietary vitamin A depends on the fat-solubilizing properties of bile acids. Bile acids are synthesized in the liver and maintained in an enterohepatic circulation. The liver is also the main storage site for vitamin A in the mammalian body, where an intimate collaboration between hepatocytes and hepatic stellate cells leads to the accumulation of retinyl esters in large cytoplasmic lipid droplet hepatic stellate cells. Chronic liver diseases are often characterized by disturbed bile acid and vitamin A homeostasis, where bile production is impaired and hepatic stellate cells lose their vitamin A in a transdifferentiation process to myofibroblasts, cells that produce excessive extracellular matrix proteins leading to fibrosis. Chronic liver diseases thus may lead to vitamin A deficiency. Recent data reveal an intricate crosstalk between vitamin A metabolites and bile acids, in part via the Retinoic Acid Receptor (RAR), Retinoid X Receptor (RXR) and the Farnesoid X Receptor (FXR), in maintaining vitamin A and bile acid homeostasis. Here, we provide an overview of the various levels of "communication" between vitamin A metabolites and bile acids and its relevance for the treatment of chronic liver diseases.
authors.affiliation: Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Institute of Molecular biology & Bio-technology, Bahauddin Zakariya University, Multan, Pakistan. Electronic address: a.saeed@umcg.nl.
authors.forename: Ali
authors.initials: A
authors.lastname: Saeed
authors.affiliation: Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. Electronic address: mhoekstra80@gmail.com.
authors.forename: Mark
authors.initials: M
authors.lastname: Hoekstra
authors.affiliation: Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. Electronic address: martijn.hoeke@hvhl.nl.
authors.forename: Martijn Oscar
authors.initials: MO
authors.lastname: Hoeke
authors.affiliation: Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Laboratory Medicine, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. Electronic address: j.heegsma@umcg.nl.
authors.forename: Janette
authors.initials: J
authors.lastname: Heegsma
authors.affiliation: Department of Gastroenterology and Hepatology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. Electronic address: k.n.faber@umcg.nl.
authors.forename: Klaas Nico
authors.initials: KN
authors.lastname: Faber
mesh_terms: D001647:Bile Acids and Salts / Q000096:biosynthesis / Q000378:metabolism*; D006706:Homeostasis; D006801:Humans; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008107:Liver Diseases / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D047490:Retinoid X Receptor alpha / Q000378:metabolism; D014801:Vitamin A / Q000378:metabolism*; D014802:Vitamin A Deficiency / Q000150:complications / Q000378:metabolism / Q000473:pathology; D000099150:Receptor, Farnesoid X-Activated
chemical_list: D001647:Bile Acids and Salts; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D047490:Retinoid X Receptor alpha; D014801:Vitamin A; D000099150:Receptor, Farnesoid X-Activated
keywords: Bile acid; Liver disease; Nuclear receptor; Therapy; Vitamin A