J. Vet. Sci. 2017; 18(1): 17-23  
Expression of von Willebrand factor, pulmonary intravascular macrophages, and Toll-like receptors in lungs of septic foals
Jacqueline M. E. Harrison1, Leah M. Quanstrom1, Alex R. Robinson1, Bruce Wobeser2, Stacy L. Anderson1, Baljit Singh1,*
1Department of Veterinary Biomedical Sciences Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada
2Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK S7N 5B4, Canada
Correspondence to: Baljit Singh
Tel: +1-306-966-7068; Fax: +1-306-966-7478; E-mail: baljit.singh1@ucalgary.ca
Received: January 19, 2016; Revised: March 2, 2016; Accepted: May 12, 2016; Published online: March 30, 2017.
Sepsis causes significant mortality in neonatal foals; however, there is little data describing the cellular and molecular pathways of lung inflammation in septic foals. This study was conducted to characterize lung inflammation in septic foals. Lung tissue sections from control (n = 6) and septic (n = 17) foals were compared using histology and immunohistology. Blinded pathologic scoring of hematoxylin and eosin stained samples revealed increased features of lung inflammation such as thickened alveolar septa and sequestered inflammatory cells in septic foals. Septic foal lungs showed increased expression of von Willebrand factor in blood vessels, demonstrating vascular inflammation. Use of MAC387 antibody to detect calprotectin as a reflection of mononuclear cell infiltration revealed a significant increase in their numbers in alveolar septa of lungs from septic foals compared to those from control foals. The mononuclear cells appeared to be mature macrophages and were located in the septal capillaries, suggesting they were pulmonary intravascular macrophages (PIMs). Finally, lungs from septic foals showed increased expression of Toll-like receptor 4 and 9 in mononuclear cells relative to the control. Taken together, this study is the first to show the expression of inflammatory molecules and an increase in PIMs in lungs from foals that died from sepsis.
Keywords: Toll-like receptor 4 and 9, horses, immunohistochemistry, pulmonary intravascular macrophage, von Willebrand factor

© 2017 The Korean Society of Veterinary Science.