title: Proteomic identification of IPSE/alpha-1 as a major hepatotoxin secreted by Schistosoma mansoni eggs.
abstract: BACKGROUND
  Eggs deposited in the liver of the mammalian host by the blood fluke parasite, Schistosoma mansoni, normally drive a T-helper-2 (Th2)-mediated granulomatous response in immune-competent mice. By contrast, in mice deprived of T-cells and incapable of producing granulomata, egg-secreted proteins (ESP) induce acute hepatic injury and death. Previous work has shown that one such ESP, the T2 ribonuclease known as omega-1, is hepatotoxic in vivo in that specific antisera to omega-1 prevent hepatocyte damage.
  
  
  RESULTS
  Using an in vitro culture system employing mouse primary hepatocytes and alanine transaminase (ALT) activity as a marker of heptocyte injury, we demonstrated that S. mansoni eggs, egg-secreted proteins (ESP), soluble-egg antigen (SEA), and omega-1 are directly hepatotoxic and in a dose-dependent manner. Depletion of omega-1 using a monoclonal antibody abolished the toxicity of pure omega-1 and diminished the toxicity in ESP and SEA by 47 and 33%, respectively. Anion exchange chromatography of ESP yielded one predominant hepatotoxic fraction. Proteomics of that fraction identified the presence of IPSE/alpha-1 (IL-4 inducing principle from S. mansoni eggs), a known activator of basophils and inducer of Th2-type responses. Pure recombinant IPSE/alpha-1 also displayed a dose-dependent hepatotoxicity in vitro. Monoclonal antibody depletion of IPSE/alpha-1 abolished the latter's toxicity and diminished the total toxicity of ESP and SEA by 32 and 35%, respectively. Combined depletion of omega-1 and IPSE/alpha-1 diminished hepatotoxicity of ESP and SEA by 60 and 58% respectively.
  
  
  CONCLUSIONS
  We identified IPSE/alpha-1 as a novel hepatotoxin and conclude that both IPSE/alpha-1 and omega-1 account for the majority of the hepatotoxicity secreted by S. mansoni eggs.
authors: The Colorectal Research Center, Department of Surgery, King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia. mabdulla@ksu.edu.sa
authors: Maha-Hamadien
authors: MH
authors: Abdulla
authors: Kee-Chong
authors: KC
authors: Lim
authors: James H
authors: JH
authors: McKerrow
authors: Conor R
authors: CR
authors: Caffrey
mesh_terms: D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D002478:Cells, Cultured; D004527:Egg Proteins / Q000032:analysis* / Q000633:toxicity*; D015801:Helminth Proteins / Q000032:analysis* / Q000633:toxicity*; D022781:Hepatocytes / Q000187:drug effects* / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D020543:Proteome / Q000032:analysis*; D012550:Schistosoma mansoni / Q000737:chemistry* / Q000472:pathogenicity*
chemical_list: D004527:Egg Proteins; D015801:Helminth Proteins; C474807:IPSE protein, Schistosoma mansoni; D020543:Proteome; D000410:Alanine Transaminase