Pasteurella haemolytica A1-Derived Leukotoxin and Endotoxin Induce Intracellular Calcium Elevation in Bovine Alveolar Macrophages by Different Signaling Pathways

ABSTRACT Leukotoxin and endotoxin derived from Pasteurella haemolytica serotype 1 are the primary virulence factors contributing to the pathogenesis of lung injury in bovine pneumonic pasteurellosis. Activation of bovine alveolar macrophages with endotoxin or leukotoxin results in the induction of cytokine gene expression, with different kinetics (H. S. Yoo, S. K. Maheswaran, G. Lin, E. L. Townsend, and T. R. Ames, Infect. Immun. 63:381–388, 1995; H. S. Yoo, B. S. Rajagopal, S. K. Maheswaran, and T. R. Ames, Microb. Pathog. 18:237–252, 1995). Furthermore, extracellular Ca2+ is required for leukotoxin-induced cytokine gene expression. However, the involvement of Ca2+ in endotoxin effects and the precise signaling mechanisms in the regulation of intracellular Ca2+ by leukotoxin and endotoxin are not known. In fura-2-acetoxymethyl ester-loaded alveolar macrophages, intracellular Ca2+regulation by leukotoxin and endotoxin was studied by video fluorescence microscopy. Leukotoxin induced a sustained elevation of intracellular Ca2+ in a concentration-dependent fashion by influx of extracellular Ca2+ through voltage-gated channels. In the presence of fetal bovine serum, endotoxin elevated intracellular Ca2+ even in the absence of extracellular Ca2+. Leukotoxin-induced intracellular Ca2+elevation was inhibited by pertussis toxin, inhibitors of phospholipases A2 and C, and the arachidonic acid analog 5,8,11,14-eicosatetraynoic acid. Intracellular Ca2+elevation by endotoxin was inhibited by inhibitors of phospholipase C and protein tyrosine kinase, but not by pertussis toxin, or the arachidonic acid analog. To the best of our knowledge, this is the first report of Ca2+ signaling by leukotoxin through a G-protein-coupled mechanism involving activation of phospholipases A2 and C and release of arachidonic acid in bovine alveolar macrophages. Ca2+ signaling by endotoxin, on the other hand, involves activation of phospholipase C and requires tyrosine phosphorylation. The differences in the Ca2+ signaling mechanisms may underlie the reported temporal differences in gene expression during leukotoxin and endotoxin activation.

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Inhibition of the transcription factors NF-kappa B and AP-1 underlies loss of cytokine gene expression in rat alveolar macrophages treated with a diffusible product from the spores of Aspergillus fumigatus.

American Journal of Respiratory Cell and Molecular Biology ◽

10.1165/ajrcmb.15.1.8679226 ◽

1996 ◽

Vol 15 (1) ◽

pp. 88-96 ◽

Cited By ~ 28

Author(s):

W J Nicholson ◽

J Slight ◽

K Donaldson

Keyword(s):

Gene Expression ◽

Transcription Factors ◽

Aspergillus Fumigatus ◽

Alveolar Macrophages ◽

Cytokine Gene Expression ◽

Cytokine Gene ◽

Nf Kappa B

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Evaluation of cytokine gene expression in porcine spleen cells, peripheral blood mononuclear cells, and alveolar macrophages by competitive RT-PCR

FEMS Immunology & Medical Microbiology ◽

10.1111/j.1574-695x.2002.tb00612.x ◽

2002 ◽

Vol 34 (2) ◽

pp. 119-126 ◽

Cited By ~ 18

Author(s):

In-Soo Choi ◽

Ellen W Collisson ◽

Samuel K Maheswaran ◽

Han Sang Yoo

Keyword(s):

Gene Expression ◽

Peripheral Blood Mononuclear Cells ◽

Alveolar Macrophages ◽

Mononuclear Cells ◽

Cytokine Gene Expression ◽

Cytokine Gene ◽

Rt Pcr ◽

Spleen Cells ◽

Peripheral Blood Mononuclear ◽

Blood Mononuclear Cells

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Cytokine gene expression and prostaglandin production in head kidney leukocytes isolated from Atlantic cod (Gadus morhua) added different levels of arachidonic acid and eicosapentaenoic acid

Fish & Shellfish Immunology ◽

10.1016/j.fsi.2012.11.044 ◽

2013 ◽

Vol 34 (3) ◽

pp. 770-777 ◽

Cited By ~ 27

Author(s):

Miriam Furne ◽

Elisabeth Holen ◽

Pedro Araujo ◽

Kai Kristoffer Lie ◽

Mari Moren

Keyword(s):

Gene Expression ◽

Arachidonic Acid ◽

Eicosapentaenoic Acid ◽

Gadus Morhua ◽

Atlantic Cod ◽

Head Kidney ◽

Cytokine Gene Expression ◽

Cytokine Gene ◽

Prostaglandin Production ◽

Different Levels

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IL-1 beta and IL-6 gene expression in alveolar macrophages: modulation by extracellular matrices

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1992.262.5.l600 ◽

1992 ◽

Vol 262 (5) ◽

pp. L600-L605 ◽

Cited By ~ 4

Author(s):

Z. Xing ◽

M. Jordana ◽

J. Gauldie

Keyword(s):

Gene Expression ◽

Alveolar Macrophages ◽

Interleukin 1 ◽

Early Time ◽

Extracellular Matrices ◽

Cytokine Gene Expression ◽

Cytokine Gene ◽

Inflammatory Reactions ◽

Cell Source ◽

Extracellular Environment

Interleukin-1 (IL-1) and interleukin-6 (IL-6) are two cytokines involved in a variety of host inflammatory reactions. The alveolar macrophage (AM), a predominant cell source for IL-1 and IL-6, exists in a microenvironment in which there are abundant extracellular matrix (ECM) components, and it is likely that ECM may participate in the inflammatory response in the lung by modulating the effector activities of AMs. To investigate this hypothesis, we cultured rat AMs on different substrates including plastic, collagen, and airways fibroblast-derived ECM (fECM) and assessed IL-1 beta and IL-6 gene expression in these cells. Our study demonstrates that cytokine gene expression in AMs is affected by the conditions of culture. IL-1 gene expression is stimulated by adherence to plastic and exposure to endotoxin, whereas IL-6 mRNA is detectable only in the cells stimulated by endotoxin. Coating the plastic with collagen or fECM modifies cytokine gene expression. At early time points, collagen enhances gene expression. At later times (5 days), actin and cytokine gene expression are predominantly maintained in the endotoxin-stimulated cells cultured on fECM. These findings suggest an extracellular environment-directed mechanism of regulation of cytokine expression in alveolar macrophages.

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