title: Characterization of acid and non-acid glycosphingolipids of porcine heart valve cusps as potential immune targets in biological heart valve grafts.
abstract: BACKGROUND
  Although xenotransplantation of vascularized organs/cells has not yet reached the clinic, glutaraldehyde-treated bioprosthetic heart valves (BHV), derived from porcine or bovine tissues, are today used for clinical replacement of diseased heart valves. However, the durability of these valve cusps is limited partly due to the onset of immune responses to the grafts. The xenoantigen-determinant Galα3Gal- and corresponding anti-Gal antibodies have been postulated to in part contribute to BHV damage. However, the presence of other non-Gal carbohydrate antigen determinants as well as the immune response to these non-Gal antigens and the inflammatory response generated by their interaction with the immune system has not been studied. In this study, we have isolated and structurally characterized both non-acid and acid glycosphingolipids from naïve porcine aortic and pulmonary valve cusps.
  
  
  METHODS
  Total non-acid and acid glycosphingolipids were isolated from porcine aortic and pulmonalis valve cusps of 20 animals. Glycosphingolipid components were structurally characterized by thin-layer chromatography, liquid chromatography-mass spectrometry and binding of monoclonal antibodies and lectins.
  
  
  RESULTS
  The non-acid glycosphingolipids were characterized as globotetraosylceramide, H-type 2 pentaosylceramide, fucosyl-gangliotetraosylceramide, and Galα3neolactotetraosylceramide. The acid glycosphingolipid fractions had both sulfatide and gangliosides (GM3, GM2, GM1, fucosyl-GM1, GD3 and GD1a), and all gangliosides contained N-acetyl-neuraminic acid. Significantly, the N-glycolyl-neuraminic acid (NeuGc) variant, a major component in many pig organs and to which humans can develop antibodies, was not detected among the gangliosides.
  
  
  CONCLUSIONS
  Pig valve cusps contain several complex lipid-bound carbohydrate structures that may be targets for the human immune system. Notable, the NeuGc determinant was absent in the cusp gangliosides. This work forms a platform for further characterizing the antibody reactivity of patients with porcine-derived BHV.
authors.affiliation: Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
authors.forename: Angela
authors.initials: A
authors.lastname: Barone
authors.forename: John
authors.initials: J
authors.lastname: Benktander
authors.forename: Susann
authors.initials: S
authors.lastname: Teneberg
authors.forename: Michael E
authors.initials: ME
authors.lastname: Breimer
mesh_terms: D020384:Acidic Glycosphingolipids / Q000494:pharmacology*; D000818:Animals; D001705:Bioprosthesis; D006350:Heart Valve Prosthesis; D006351:Heart Valves / Q000601:surgery*; D009438:Neuraminic Acids / Q000494:pharmacology; D016377:Organ Transplantation / Q000379:methods; D013552:Swine; D014183:Transplantation, Heterologous
chemical_list: D020384:Acidic Glycosphingolipids; D009438:Neuraminic Acids
keywords: carbohydrate antigens; glycosphingolipid characterization; immune recognition of bioprosthetic heart valves; mass spectrometry; porcine heart valves