Bovine platelets activated by Haemophilus somnus and its LOS induce apoptosis in bovine endothelial cells

• Published in: Microbial pathogenesis Vol. 38; no. 1; pp. 23 - 32
• Main Authors: Kuckleburg, Christopher J., Sylte, Matt J., Inzana, Thomas J., Corbeil, Lynette B., Darien, Benjamin J., Czuprynski, Charles J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier India Pvt Ltd 2005; Elsevier
• Subjects: animal pathogenic bacteria; Animals; Apoptosis; Bacteriology; Benzimidazoles - metabolism; Biological and medical sciences; blood platelets; Blood Platelets - chemistry; Blood Platelets - physiology; Caspase 3; Caspases - analysis; Cattle; CD40 Ligand - analysis; Cells, Cultured; Endothelial cell; endothelial cells; Endothelial Cells - cytology; Endothelial Cells - physiology; Fas Ligand Protein; FasL; Fundamental and applied biological sciences. Psychology; Haemophilus somnus; Haemophilus somnus - chemistry; Haemophilus somnus - pathogenicity; infection; lipooligosaccharides; Lipopolysaccharides - isolation & purification; Lipopolysaccharides - toxicity; LOS; Membrane Glycoproteins - analysis; Microbiology; Miscellaneous; P-Selectin - analysis; Platelet; Platelet Activation; Platelet Aggregation; LOS; Platelet; Endothelial cell; Haemophilus somnus; FasL; Apoptosis; Fas ligand; Bovine; Microbiology; Cytokine; Pasteurellaceae; Vertebrata; Mammalia; Cell death; Bacteria; Artiodactyla; Veterinary; Ungulata
• ISSN: 0882-4010; 1096-1208
• DOI: 10.1016/j.micpath.2004.10.006

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.