title: Inflammation-Induced Expression and Secretion of MicroRNA 122 Leads to Reduced Blood Levels of Kidney-Derived Erythropoietin and Anemia.
abstract: Anemia is associated commonly with acute and chronic inflammation, but the mechanisms of their interaction are not clear. We investigated whether microRNA 122 (MIR122), which is generated in the liver and is secreted into the blood, is involved in the development of anemia associated with inflammation.
  
  
  
  We characterized the primary transcript of the human liver-specific MIR122 using Northern blot, quantitative real-time polymerase chain reaction, and 3' and 5' rapid amplification of cDNA ends analyses. We studied regulation of MIR122 in human hepatocellular carcinoma cell lines (Huh7 and HepG2) as well as in C57BL/6 and mice with disruption of the tumor necrosis factor (Tnf) gene. Liver tissues were collected and analyzed by bioluminescence imaging or immunofluorescence. Inflammation in mice was induced by lipopolysaccharide (LPS) or by cerulein injections. Mice were given 4 successive injections of LPS, leading to inflammation-induced anemia. Steatohepatitis was induced with a choline-deficient, high-fat diet. Hemolytic anemia was stimulated by phenylhydrazine injection. MIR122 was inhibited in mice by tail-vein injection of an oligonucleotide antagonist of MIR122. MicroRNA and messenger RNA levels were determined by quantitative real-time polymerase chain reaction.
  
  
  
  The primary transcript of MIR122 spanned 5 kb, comprising 3 exons; the third encodes MIR122. Within the MIR122 promoter region we identified a nuclear factor-κB binding site and showed that RELA (NF-κB p65 subunit), as well as activators of NF-κB (TNF and LPS), increased promoter activity of MIR122. Administration of LPS to mice induced secretion of MIR122 into blood, which required TNF. Secreted MIR122 reached the kidney and reduced expression of erythropoietin (Epo), which we identified as a MIR122 target gene. Injection of mice with an oligonucleotide antagonist of MIR122 increased blood levels of EPO, reticulocytes, and hemoglobin. We found an inverse relationship between blood levels of MIR122 and EPO in mice with acute pancreatitis or steatohepatitis, and also in patients with acute inflammation.
  
  
  
  In mice, we found that LPS-induced inflammation increases blood levels of MIR122, which reduces expression of Epo in the kidney; this is a mechanism of inflammation-induced anemia. Strategies to block MIR122 in patients with inflammation could reduce the development or progression of anemia.
authors.affiliation: The Goldyne Savad Institute of Gene and Cell Therapy, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel.
authors.forename: Mila
authors.initials: M
authors.lastname: Rivkin
authors.affiliation: The Goldyne Savad Institute of Gene and Cell Therapy, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel.
authors.forename: Alina
authors.initials: A
authors.lastname: Simerzin
authors.affiliation: The Goldyne Savad Institute of Gene and Cell Therapy, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel.
authors.forename: Elina
authors.initials: E
authors.lastname: Zorde-Khvalevsky
authors.affiliation: The Goldyne Savad Institute of Gene and Cell Therapy, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel.
authors.forename: Chofit
authors.initials: C
authors.lastname: Chai
authors.affiliation: Department of Surgery, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel.
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Yuval
authors.affiliation: The Goldyne Savad Institute of Gene and Cell Therapy, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel.
authors.forename: Nofar
authors.initials: N
authors.lastname: Rosenberg
authors.affiliation: The Goldyne Savad Institute of Gene and Cell Therapy, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel.
authors.forename: Rona
authors.initials: R
authors.lastname: Harari-Steinfeld
authors.affiliation: Department of Nephrology, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel.
authors.forename: Ronen
authors.initials: R
authors.lastname: Schneider
authors.affiliation: Department of Pathology, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel.
authors.forename: Gail
authors.initials: G
authors.lastname: Amir
authors.affiliation: Department of Developmental Biology and Cancer Research, Hebrew University, Hadassah Medical School, Jerusalem, Israel.
authors.forename: Reba
authors.initials: R
authors.lastname: Condiotti
authors.affiliation: Institute for Virology, Technische Universität München and Helmholtz Zentrum München, Munich, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Heikenwalder
authors.affiliation: Institute of Surgical Pathology, University Zurich, Zurich, Switzerland.
authors.forename: Achim
authors.initials: A
authors.lastname: Weber
authors.affiliation: Department of Gastroenterology and Hepatology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schramm
authors.affiliation: Department of Gastroenterology and Hepatology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Wege
authors.affiliation: Department of Gastroenterology and Hepatology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Kluwe
authors.affiliation: The Goldyne Savad Institute of Gene and Cell Therapy, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel. Electronic address: eithang@hadassah.org.il.
authors.forename: Eithan
authors.initials: E
authors.lastname: Galun
authors.affiliation: The Goldyne Savad Institute of Gene and Cell Therapy, Hadassah Hebrew University Hospital, Ein Karem, Jerusalem, Israel.
authors.forename: Hilla
authors.initials: H
authors.lastname: Giladi
mesh_terms: D000740:Anemia / Q000209:etiology* / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D015152:Blotting, Northern; D004921:Erythropoietin / Q000097:blood*; D005260:Female; D056945:Hep G2 Cells; D006801:Humans; D007249:Inflammation / Q000150:complications* / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D015415:Biomarkers; C554270:EPO protein, human; C531907:MIRN122 microRNA, human; D035683:MicroRNAs; C544354:Mirn122 microRNA, mouse; D004921:Erythropoietin
keywords: Microbiome; Mouse Model; NASH; Red Blood Cells