Pasteurella haemolytica leukotoxin and endotoxin induced cytokine gene expression in bovine alveolar macrophages requires NF-kappaB activation and calcium elevation.
In bovine alveolar macrophages (BAMs), exposure to leukotoxin (Lkt) and endotoxin (LPS) from Pasteurella haemolytica results in expression of inflammatory cytokine genes and intracellular calcium ([Ca2+]i) elevation. Leukotoxin from P. haemolytica interacts only with leukocytes and platelets from ruminant species. Upregulation of cytokine genes in different cells by LPS involves activation of the transcription factor NF-kappaB (NF-kappaB), resulting in its translocation from the cytoplasm to the nucleus. Using immunocytochemical staining and confocal imaging, we studied whether NF-kappaB activation represents a common mechanism for the expression of multiple cytokine genes in BAMs (Lkt-susceptible cells) stimulated with Lkt and LPS. Bovine pulmonary artery endothelial cells and porcine alveolar macrophages were used as nonsusceptible cells. The role of Ca2+ and tyrosine kinases in NF-kappaB activation and inflammatory cytokine gene expression was studied, since an inhibitor of tyrosine kinases attenuates LPS-induced [Ca2+]i elevation in BAMs. The results are summarized as follows: (a) Lkt induced NF-kappaB activation and [Ca2+]i elevation only in BAMs, while LPS effects were demonstrable in all cell types; (b) chelation of [Ca2+]i blocked NF-kappaB activation and IL-1beta, TNFalpha, and IL-8 mRNA expression; and (c) tyrosine kinase inhibitor herbimycin A blocked expression of all three cytokine genes in BAMs stimulated with Lkt, while only the expression of IL-1beta was blocked in BAMs stimulated with LPS. We conclude that cytokine gene expression in BAMs requires NF-kappaB activation and [Ca2+]i elevation, and Lkt effects exhibit cell type- and species specificity.
Hsuan
S L
SL
Department of Veterinary PathoBiology, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USA.
Kannan
M S
MS
Jeyaseelan
S
S
Prakash
Y S
YS
Malazdrewich
C
C
Abrahamsen
M S
MS
Sieck
G C
GC
Maheswaran
S K
SK
D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics*; D003603:Cytotoxins / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D005098:Exotoxins / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D007375:Interleukin-1 / Q000235:genetics; D016209:Interleukin-8 / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016676:Macrophages, Alveolar / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D016978:Mannheimia haemolytica / Q000502:physiology*; D016328:NF-kappa B / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D013552:Swine; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D001427:Bacterial Toxins; D016207:Cytokines; D003603:Cytotoxins; D005098:Exotoxins; D007375:Interleukin-1; D016209:Interleukin-8; D008070:Lipopolysaccharides; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; C018579:leukotoxin; D011505:Protein-Tyrosine Kinases; D002118:Calcium