title: Serum ubiquitin levels in patients with nonalcoholic steatohepatitis.
abstract: OBJECTIVE
  Nonalcoholic steatohepatitis is increasingly recognized as the most common liver disease in patients with elevated liver enzymes. In the pathophysiology of nonalcoholic steatohepatitis, the first step is the lipid accumulation in the liver causing steatosis, the second step involves the endotoxins, cytokines and environmental toxins causing oxidative stress and lipid peroxidation, in time leading to steatohepatitis. Ubiquitin is a molecular chaperone that plays a major role in the degradation of intracellular proteins. Ubiquitin proteasome system is also considered as a cellular defense mechanism that removes damaged proteins generated by oxidative stress. In order to search for the role of ubiquitin in the pathogenesis of nonalcoholic steatohepatitis, serum levels of ubiquitin were studied in patients with nonalcoholic steatohepatitis for the first time in the literature, to our knowledge.
  
  
  METHODS
  Eighteen patients with biopsy proven nonalcoholic steatohepatitis diagnosis (13 males and 5 females with a mean age of 41) and 16 healthy volunteers as a control group (11 males and 5 females, with a mean age of 38) were included in the study. Serum ubiquitin levels were studied by ELISA method.
  
  
  RESULTS
  The mean serum ubiquitin level (14.13 +/- 1.46 micrograms/mL) in patients with nonalcoholic steatohepatitis was significantly elevated compared to that of the control group (7.66 +/- 0.40 micrograms/mL) (p < 0.001). No correlation was found among serum ubiquitin levels and hepatic steatosis, inflammation and fibrosis.
  
  
  CONCLUSIONS
  Increased serum ubiquitin levels may show that the ubiquitin proteasome pathway actively participates in defending against oxidative stress in nonalcoholic steatohepatitis. Serum ubiquitin concentration may be a marker predicting the intracellular cytoprotective response against oxidative stress rather than the degree of liver damage in pathogenesis of nonalcoholic steatohepatitis. Ubiquitin proteasome system based therapies may have a place in the treatment of patients with nonalcoholic steatohepatitis in the future.
authors.affiliation: Department of Internal Medicine, Division of Gastroenterology, University of Gaziantep, Gaziantep, Turkey. mcsavas@gantep.edu.tr
authors.forename: M Cemil
authors.initials: MC
authors.lastname: Savas
authors.forename: Mehmet
authors.initials: M
authors.lastname: Koruk
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Pirim
authors.forename: Omer
authors.initials: O
authors.lastname: Yilmaz
authors.forename: Metin
authors.initials: M
authors.lastname: Karakok
authors.forename: Seyithan
authors.initials: S
authors.lastname: Taysi
authors.forename: Arif
authors.initials: A
authors.lastname: Yilmaz
mesh_terms: D000328:Adult; D004797:Enzyme-Linked Immunosorbent Assay; D005234:Fatty Liver / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D015227:Lipid Peroxidation / Q000502:physiology; D008099:Liver / Q000473:pathology / Q000503:physiopathology; D008111:Liver Function Tests; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology; D012307:Risk Factors; D025801:Ubiquitin / Q000097:blood*
chemical_list: D025801:Ubiquitin