The equine alveolar macrophage: Functional and phenotypic comparisons with peritoneal macrophages

Alveolar macrophages (AMs) constitute the first line of defence in the lung of all species, playing a crucial role in the regulation of immune responses to inhaled pathogens. A detailed understanding of the function and phenotype of AMs is a necessary pre-requisite to both elucidating their role in...

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Bibliographic Details
Published in:Veterinary immunology and immunopathology 2013-10, Vol.155 (4), p.219-228
Main Authors: Karagianni, Anna E., Kapetanovic, Ronan, McGorum, Bruce C., Hume, David A., Pirie, Scott R.
Format: Article
Language:English
Subjects:
Animals
bacterial colonization
enzyme-linked immunosorbent assay
Flow Cytometry - veterinary
gene expression
Horse
horses
Horses - immunology
immune response
Immunity
Immunity, Innate - immunology
Immunology
Immunophenotyping - veterinary
Indoleamine-Pyrrole 2,3,-Dioxygenase - genetics
Indoleamine-Pyrrole 2,3,-Dioxygenase - immunology
Interleukin-10 - genetics
Interleukin-10 - immunology
interleukins
Life Sciences
Lung - cytology
Lung - immunology
Lungs
Macrophage
macrophages
Macrophages, Alveolar - cytology
Macrophages, Alveolar - immunology
Macrophages, Peritoneal - cytology
Macrophages, Peritoneal - immunology
messenger RNA
Microbiology and Parasitology
Nitrates - analysis
Nitrates - immunology
Peritoneal cavity
Phenotype
polyinosinic-polycytidylic acid
quantitative polymerase chain reaction
Research Paper
respiratory system
respiratory tract diseases
Reverse Transcriptase Polymerase Chain Reaction - veterinary
RNA - chemistry
RNA - genetics
Salmonella
Tumor Necrosis Factor-alpha - genetics
Tumor Necrosis Factor-alpha - immunology
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Summary:Alveolar macrophages (AMs) constitute the first line of defence in the lung of all species, playing a crucial role in the regulation of immune responses to inhaled pathogens. A detailed understanding of the function and phenotype of AMs is a necessary pre-requisite to both elucidating their role in preventing opportunistic bacterial colonisation of the lower respiratory tract and developing appropriate preventative strategies. The purpose of the study was to characterise this important innate immune cell at the tissue level by making functional and phenotypic comparisons with peritoneal macrophages (PMs). We hypothesised that the tissue of origin determines a unique phenotype of AMs, which may constitute an appropriate therapeutic target for certain equine respiratory diseases. Macrophages isolated from the lung and the peritoneal cavity of 9 horses were stimulated with various toll like receptor (TLR) ligands and the production of nitrite, tumour necrosis factor alpha (TNFα), interleukin (IL) 10 and indoleamine 2,3-dioxygenase (IDO) were measured by the Griess reaction and enzyme linked immunosorbent assay (ELISA) and/or quantitative polymerase chain reaction, respectively. Cells were also compared on the basis of phagocytic-capacity and the expression of several cell surface markers. AMs, but not PMs, demonstrated increased TNFα release following stimulation with LPS, polyinosinic polycytidylic acid (Poly IC) and heat-killed Salmonella typhinurium and increased TNFα and IDO mRNA expression when stimulated with LPS. AMs showed high expression of the specific macrophage markers cluster of differentiation (CD) 14, CD163 and TLR4, whereas PMs showed high expression of TLR4 only. AMs, but not PMs, demonstrated efficient phagocytic activity. Our results demonstrate that AMs are more active than PMs when stimulated with various pro-inflammatory ligands, thus supporting the importance of the local microenvironment in the activation status of the macrophage. This information provides a valuable knowledge base on which to improve our understanding of the role of macrophages and their microenvironment in equine innate immunity.
ISSN:0165-2427
1873-2534
0165-2427
DOI:10.1016/j.vetimm.2013.07.003