title: Viable "Haemophilus somnus" induces myosin light-chain kinase-dependent decrease in brain endothelial cell monolayer resistance.
abstract: "Haemophilus somnus" causes thrombotic meningoencephalitis in cattle. Our laboratory has previously reported that H. somnus has the ability to adhere to, but not invade, bovine brain endothelial cells (BBEC) in vitro. The goal of this study was to determine if H. somnus alters brain endothelial cell monolayer integrity in vitro, in a manner that would be expected to contribute to inflammation of the central nervous system (CNS). Monolayer integrity was monitored by measuring transendothelial electrical resistance (TEER) and albumin flux. BBEC incubated with H. somnus underwent rapid cytoskeletal rearrangement, significant increases in albumin flux, and reductions in TEER. Decreased monolayer TEER was preceded by phosphorylation of the myosin regulatory light chain and was partially dependent on tumor necrosis factor alpha and myosin light-chain kinase but not interleukin-1beta. Neither heat-killed H. somnus, formalin-fixed H. somnus, nor purified lipooligosaccharide altered monolayer integrity within a 2-h incubation period, whereas conditioned medium from H. somnus-treated BBEC caused a modest reduction in TEER. The data from this study support the hypothesis that viable H. somnus alters integrity of the blood-brain barrier by promoting contraction of BBEC and increasing paracellular permeability of the CNS vasculature.
authors.affiliation: Department of Pathobiological Sciences, School of Veterinary Medicine, 2015 Linden Drive, Madison, WI 53706, USA.
authors.forename: E
authors.initials: E
authors.lastname: Behling-Kelly
authors.forename: David
authors.initials: D
authors.lastname: McClenahan
authors.forename: K S
authors.initials: KS
authors.lastname: Kim
authors.forename: C J
authors.initials: CJ
authors.lastname: Czuprynski
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000201:enzymology* / Q000276:immunology / Q000382:microbiology; D002417:Cattle; D002461:Cell Line, Transformed; D002463:Cell Membrane Permeability / Q000502:physiology*; D042783:Endothelial Cells / Q000201:enzymology* / Q000276:immunology / Q000382:microbiology*; D004730:Endothelium, Vascular / Q000201:enzymology / Q000276:immunology / Q000382:microbiology; D044138:Haemophilus somnus / Q000276:immunology / Q000502:physiology*; D007375:Interleukin-1 / Q000502:physiology; D009219:Myosin-Light-Chain Kinase / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
chemical_list: D007375:Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D009219:Myosin-Light-Chain Kinase