title: Prevention of liver fibrosis by the purinoceptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate (PPADS).
abstract: BACKGROUND
  Hepatic stellate cells (HSC) are important mediators of liver fibrosis. HSC express purinergic receptors for extracellular ATP that induce fibrogenesis. Pyridoxal-phosphate-6-azophenyl-2', 4'-disulfonate (PPADS) is a highly bioavailable purinoceptor inhibitor. We sought to determine whether PPADS could prevent experimental liver fibrosis in rats.
  
  
  METHODS
  The effect of PPADS as an inhibitor of HSC purinoceptors was compared to the effect of suramin using confocal video microscopy. Rats were treated with CCl4, dimethylnitrosamine, or common bile duct ligation in the presence or absence of PPADS. Fibrosis in liver sections was assessed using Trichrome and Sirius red stains. In HSC isolated from experimental animals, proliferation was determined by bromodeoxyuridine uptake, apoptosis was determined using Annexin V flow cytometry, and transcription of alpha(1)-procollagen and fibronectin were determined using quantitative RT-PCR.
  
  
  RESULTS
  Both PPADS and suramin inhibited HSC purinoceptor activation, but PPADS had a more durable effect. PPADS completely blocked the development of cirrhosis due to CCl4 or dimethylnitrosamine but not due to bile duct ligation. PPADS inhibited HSC proliferation, but had no effect on HSC apoptosis. PPADS inhibited transcription of alpha(1)-procollagen and fibronectin by HSC.
  
  
  CONCLUSIONS
  Blockade of purinergic receptors is a novel approach to prevention of non- biliary liver fibrosis. The primary action of PPADS is to inhibit HSC proliferation and fibrogenesis. Future design of purinergic receptor inhibitors may be an effective pharmacologic treatment to prevent liver fibrosis.
authors.affiliation: Section of Digestive Diseases, Yale Liver Center, Yale University School of Medicine, New Haven, CT 06520, USA.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Dranoff
authors.forename: Emma A
authors.initials: EA
authors.lastname: Kruglov
authors.forename: Odaliz
authors.initials: O
authors.lastname: Abreu-Lanfranco
authors.forename: Trong
authors.initials: T
authors.lastname: Nguyen
authors.forename: Gaurav
authors.initials: G
authors.lastname: Arora
authors.forename: Gaurav
authors.initials: G
authors.lastname: Aurora
authors.forename: Dhanpat
authors.initials: D
authors.lastname: Jain
mesh_terms: D000818:Animals; D002252:Carbon Tetrachloride Poisoning; D004797:Enzyme-Linked Immunosorbent Assay; D008103:Liver Cirrhosis / Q000139:chemically induced / Q000517:prevention & control*; D008297:Male; D018613:Microscopy, Confocal; D058914:Purinergic Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D058914:Purinergic Antagonists; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate