title: Bovine platelets activated by Haemophilus somnus and its LOS induce apoptosis in bovine endothelial cells.
abstract: Haemophilus somnus is a bacterial pathogen that causes respiratory disease and vasculitis in cattle. Thrombotic meningoencephalitis (TME) and other severe forms of H. somnus-mediated vascular disease are characterized histopathologically by vasculitis, thrombosis, and infiltration of polymorphonuclear cells. It has been reported previously that activated human platelets express CD40L, FasL and P-selectin (CD62P). We hypothesized that if these surface markers are up-regulated on bovine platelets after in vitro exposure to H. somnus and its lipooligosaccharide (LOS), they might contribute to endothelial cell damage. Using flow cytometry, we demonstrated low baseline expression of these molecules by bovine platelets and increased expression following in vitro stimulation with ADP, H. somnus or H. somnus LOS. H. somnus stimulated platelets were capable of causing apoptosis in endothelial cells as measured by Hoechst-33342 staining and caspase-3 activity. If these events occur in vivo, they might promote vascular damage and endothelial cell apoptosis, leading to the development of vasculitis and thrombosis that characterize bovine H. somnus infection.
authors.affiliation: Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Drive West, Madison, WI 53706, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Kuckleburg
authors.forename: Matt J
authors.initials: MJ
authors.lastname: Sylte
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Inzana
authors.forename: Lynette B
authors.initials: LB
authors.lastname: Corbeil
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Darien
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Czuprynski
mesh_terms: D000818:Animals; D017209:Apoptosis; D001562:Benzimidazoles / Q000378:metabolism; D001792:Blood Platelets / Q000737:chemistry / Q000502:physiology*; D023201:CD40 Ligand / Q000032:analysis; D053148:Caspase 3; D020169:Caspases / Q000032:analysis; D002417:Cattle; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology*; D053222:Fas Ligand Protein; D044138:Haemophilus somnus / Q000737:chemistry / Q000472:pathogenicity*; D008070:Lipopolysaccharides / Q000302:isolation & purification / Q000633:toxicity*; D008562:Membrane Glycoproteins / Q000032:analysis; D019007:P-Selectin / Q000032:analysis; D015539:Platelet Activation; D010974:Platelet Aggregation
chemical_list: D001562:Benzimidazoles; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D019007:P-Selectin; C023023:lipid-linked oligosaccharides; D023201:CD40 Ligand; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; C017807:bisbenzimide ethoxide trihydrochloride