title: Endocannabinoid receptor CB2 in nonalcoholic fatty liver disease.
abstract: OBJECTIVE
  Fatty infiltration and fibrosis are major issues in chronic liver disease. Recent reports suggest a role for the endocannabinoid system in these processes.
  
  
  OBJECTIVE
  To characterize localization and expression of CB2 in normal liver and nonalcoholic fatty liver.
  
  
  METHODS
  We studied 64 liver biopsies: eight were considered normal; 56 had a diagnosis of nonalcoholic fatty liver disease (NAFLD); 32 with nonalcoholic steatosis and 24 nonalcoholic steatohepatitis (NASH). CB2 immunolocalization was studied in 38 samples in paraffin blocks using immunohistochemistry, and a computerized semiquantitative analysis was carried out. CB2 mRNA expression was assessed through RT-PCR in 26 frozen liver samples and the ratio CB2/beta-actin was used to evaluate differences between groups. Statistical analysis was performed with central tendency measures and the Mann-Whitney U-test. We considered as significant differences those with a P-value <0.05.
  
  
  RESULTS
  Neither parenchymal nor nonparenchymal cells in normal liver tissue react towards anti-CB2 antibodies. All the samples from patients with steatosis and nonalcoholic steatohepatitis showed hepatocellular immunoreactivity. Cholangiocytes were positive only in the NAFLD group. Normal liver tissue showed a normalized CB2/beta-actin ratio of 0.001+/-0.01, steatosis 6.52+/-17.3 (P=0.05 vs normal) and NASH 6.49+/-12.2 (P=0.06 vs normal and P=0.6 vs steatosis).
  
  
  CONCLUSIONS
  CB2 receptors are expressed by hepatocytes in nonalcoholic fatty liver disease but not in normal liver.
authors.affiliation: Department of Biomedical Research, Gastroenterology & Liver Unit, Puente de Piedra 150, Col. Toriello Guerra, Mexico City, Mexico. nmendez@medicasur.org.mx
authors.forename: N
authors.initials: N
authors.lastname: Mendez-Sanchez
authors.forename: D
authors.initials: D
authors.lastname: Zamora-Valdes
authors.forename: R
authors.initials: R
authors.lastname: Pichardo-Bahena
authors.forename: B
authors.initials: B
authors.lastname: Barredo-Prieto
authors.forename: G
authors.initials: G
authors.lastname: Ponciano-Rodriguez
authors.forename: L
authors.initials: L
authors.lastname: Bermejo-Martínez
authors.forename: N C
authors.initials: NC
authors.lastname: Chavez-Tapia
authors.forename: H A
authors.initials: HA
authors.lastname: Baptista-González
authors.forename: M
authors.initials: M
authors.lastname: Uribe
mesh_terms: D005234:Fatty Liver / Q000378:metabolism* / Q000473:pathology; D006505:Hepatitis / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008099:Liver / Q000378:metabolism / Q000473:pathology; D011446:Prospective Studies; D012333:RNA, Messenger / Q000378:metabolism; D043885:Receptor, Cannabinoid, CB2 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014018:Tissue Distribution
chemical_list: D012333:RNA, Messenger; D043885:Receptor, Cannabinoid, CB2