title: MicroRNAs play a role in spontaneous recovery from acute liver failure.
abstract: Acute liver failure (ALF) represents a life-threatening situation characterized by sudden and massive liver cell death in the absence of preexisting liver disease. Although most patients require liver transplantation to prevent mortality, some recover spontaneously and show complete liver regeneration. Because of the rarity of this disease, the molecular mechanisms regulating liver regeneration in ALF patients remain largely unknown. In this study, we investigated the role of microRNAs (miRs) that have been implicated in liver injury and regeneration in sera from ALF patients (n = 63). Patients with spontaneous recovery from ALF showed significantly higher serum levels of miR-122, miR-21, and miR-221, compared to nonrecovered patients. In liver biopsies, miR-21 and miR-221 displayed a reciprocal expression pattern and were found at lower levels in the spontaneous survivors, whereas miR-122 was elevated in both serum and liver tissue of those patients. As compared to nonrecovered patients, liver tissue of spontaneous survivors revealed not only increased hepatocyte proliferation, but also a strong down-regulation of miRNA target genes that impair liver regeneration, including heme oxygenase-1, programmed cell death 4, and the cyclin-dependent kinase inhibitors p21, p27, and p57.
  
  
  CONCLUSIONS
  Our data suggest that miR-122, miR-21, and miR-221 are involved in liver regeneration and might contribute to spontaneous recovery from ALF. Prospective studies will show whether serological detection of those miRNAs might be of prognostic value to predict ALF outcome.
authors.affiliation: Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: John
authors.forename: Johannes
authors.initials: J
authors.lastname: Hadem
authors.forename: Till
authors.initials: T
authors.lastname: Krech
authors.forename: Kristin
authors.initials: K
authors.lastname: Wahl
authors.forename: Michael P
authors.initials: MP
authors.lastname: Manns
authors.forename: Steven
authors.initials: S
authors.lastname: Dooley
authors.forename: Sandor
authors.initials: S
authors.lastname: Batkai
authors.forename: Thomas
authors.initials: T
authors.lastname: Thum
authors.forename: Klaus
authors.initials: K
authors.lastname: Schulze-Osthoff
authors.forename: Heike
authors.initials: H
authors.lastname: Bantel
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D001706:Biopsy; D016022:Case-Control Studies; D049109:Cell Proliferation; D005260:Female; D022781:Hepatocytes / Q000473:pathology; D006801:Humans; D008099:Liver / Q000473:pathology; D017114:Liver Failure, Acute / Q000097:blood / Q000401:mortality / Q000503:physiopathology*; D008115:Liver Regeneration / Q000502:physiology*; D008297:Male; D035683:MicroRNAs / Q000097:blood / Q000502:physiology*; D008875:Middle Aged; D020127:Recovery of Function / Q000502:physiology*; D012680:Sensitivity and Specificity; D015996:Survival Rate
chemical_list: D015415:Biomarkers; D035683:MicroRNAs; C531907:MIRN122 microRNA, human; C524940:MIRN21 microRNA, human; C525709:MIR221, human