title: Effects of lipopolysaccharide and Mannheimia haemolytica leukotoxin on bovine lung microvascular endothelial cells and alveolar epithelial cells.
abstract: Bovine respiratory disease resulting from infection with Mannheimia haemolytica commonly results in extensive vascular leakage into the alveoli. M. haemolytica produces two substances, lipopolysaccharide (LPS) and leukotoxin (LKT), that are known to be important in inducing some of the pathological changes. In the present study, we examined bovine pulmonary epithelial (BPE) cell and bovine lung microvascular endothelial cell monolayer permeability, as measured by trans-well endothelial and epithelial cell electrical resistance (TEER), after incubation with LPS, LKT, or LPS-activated neutrophils. Endothelial cell monolayers exposed to LPS exhibited significant decreases in TEER that corresponded with increased levels of proinflammatory cytokines, apoptosis, and morphological changes. In contrast, BPE cells exposed to LPS increased the levels of production of inflammatory cytokines but displayed no changes in TEER, apoptosis, or visible morphological changes. Both cell types appeared to express relatively equal levels of the LPS ligand Toll-like receptor 4. However, TEER in BPE cell monolayers was decreased when the cells were incubated with LPS-activated neutrophils. Although the incubation of BPE cells with LKT decreased TEER, this was not reduced by the incubation of LKT with a neutralizing antibody and was reversed when LKT was preincubated with the LPS-neutralizing compound polymyxin B. Because BPE cells did not express the LKT receptor CD11a/CD18, we infer that contaminating LPS was responsible for the decreased TEER. In conclusion, LPS triggered changes in endothelial cells that would be consistent with vascular leakage, but neither LPS nor LKT caused similar changes in epithelial cells, unless neutrophils were also present.
authors.affiliation: Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. mcclenahan@svm.vetmed.wisc.edu
authors.forename: David
authors.initials: D
authors.lastname: McClenahan
authors.forename: Katrina
authors.initials: K
authors.lastname: Hellenbrand
authors.forename: Dhammika
authors.initials: D
authors.lastname: Atapattu
authors.forename: Nicole
authors.initials: N
authors.lastname: Aulik
authors.forename: David
authors.initials: D
authors.lastname: Carlton
authors.forename: Arvinder
authors.initials: A
authors.lastname: Kapur
authors.forename: Charles
authors.initials: C
authors.lastname: Czuprynski
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000633:toxicity*; D002417:Cattle; D002460:Cell Line; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000382:microbiology*; D004847:Epithelial Cells / Q000382:microbiology*; D005098:Exotoxins / Q000633:toxicity*; D008070:Lipopolysaccharides / Q000633:toxicity*; D008168:Lung / Q000166:cytology / Q000382:microbiology*; D016978:Mannheimia haemolytica / Q000502:physiology*; D009504:Neutrophils / Q000473:pathology
chemical_list: D001427:Bacterial Toxins; D005098:Exotoxins; D008070:Lipopolysaccharides; C018579:leukotoxin