title: Inhibition of allergic airway responses by heparin derived oligosaccharides: identification of a tetrasaccharide sequence.
abstract: BACKGROUND
  Previous studies showed that heparin's anti-allergic activity is molecular weight dependent and resides in oligosaccharide fractions of <2500 daltons.
  
  
  OBJECTIVE
  To investigate the structural sequence of heparin's anti-allergic domain, we used nitrous acid depolymerization of porcine heparin to prepare an oligosaccharide, and then fractionated it into disaccharide, tetrasaccharide, hexasaccharide, and octasaccharide fractions. The anti-allergic activity of each oligosaccharide fraction was tested in allergic sheep.
  
  
  METHODS
  Allergic sheep without (acute responder) and with late airway responses (LAR; dual responder) were challenged with Ascaris suum antigen with and without inhaled oligosaccharide pretreatment and the effects on specific lung resistance and airway hyperresponsiveness (AHR) to carbachol determined. Additional inflammatory cell recruitment studies were performed in immunized ovalbumin-challenged BALB/C mice with and without treatment.
  
  
  RESULTS
  The inhaled tetrasaccharide fraction was the minimal effective chain length to show anti-allergic activity. This fraction showed activity in both groups of sheep; it was also effective in inhibiting LAR and AHR, when administered after the antigen challenge. Tetrasaccharide failed to modify the bronchoconstrictor responses to airway smooth muscle agonists (histamine, carbachol and LTD4), and had no effect on antigen-induced histamine release in bronchoalveolar lavage fluid in sheep. In mice, inhaled tetrasaccharide also attenuated the ovalbumin-induced peribronchial inflammatory response and eosinophil influx in the bronchoalveolar lavage fluid. Chemical analysis identified the active structure to be a pentasulfated tetrasaccharide ([IdoU2S (1→4)GlcNS6S (1→4) IdoU2S (1→4) AMan-6S]) which lacked anti-coagulant activity.
  
  
  CONCLUSIONS
  These results demonstrate that heparin tetrasaccharide possesses potent anti-allergic and anti-inflammatory properties, and that the domains responsible for anti-allergic and anti-coagulant activity are distinctly different.
authors.affiliation: Department of Research, Mount Sinai Medical Center, Miami Beach, Florida, USA. abraham@msmc.com.
authors.forename: Tahir
authors.initials: T
authors.lastname: Ahmed
authors.forename: Gregory
authors.initials: G
authors.lastname: Smith
authors.forename: Iontcho
authors.initials: I
authors.lastname: Vlahov
authors.forename: William M
authors.initials: WM
authors.lastname: Abraham
mesh_terms: D000818:Animals; D018927:Anti-Asthmatic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000627:therapeutic use*; D000925:Anticoagulants / Q000737:chemistry*; D000947:Antigens, Helminth; D017165:Ascaris suum; D001249:Asthma / Q000188:drug therapy*; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D002217:Carbachol; D002240:Carbohydrate Sequence; D005260:Female; D006493:Heparin / Q000737:chemistry*; D006632:Histamine; D006636:Histamine Release; D017998:Leukotriene D4; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis / Q000737:chemistry / Q000627:therapeutic use*; D012756:Sheep
chemical_list: D018927:Anti-Asthmatic Agents; D000925:Anticoagulants; D000947:Antigens, Helminth; D009844:Oligosaccharides; D017998:Leukotriene D4; D006632:Histamine; D002217:Carbachol; D006493:Heparin