Molecular cloning and characterization of equine Toll-like receptor 9.
Abstract: Innate immunity relies on a series of germline-encoded pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs), to detect conserved microbial components. TLR9 is typically expressed intracellularly in immune cells such as dendritic cells and recognizes unmethylated bacterial or viral cytosine-phosphate-guanine DNA (CpG-DNA). To investigate innate immune responses through TLR9 signaling pathway in horses, we cloned and characterized equine TLR9. Protein sequence analysis shows that equine TLR9 has a typically conserved cytosolic Toll/interleukin-1 receptor (TIR) domain, three leucine-rich repeat (LRR) motifs, with greater than 82% identity to human, monkey, bovine, canine, feline, porcine and ovine orthologs. Equine TLR9 mRNA expression was characterized for spleen, lymph node, and peripheral blood leukocyte samples. Flow cytometric analysis of equine TLR9 expression using a cross-reactive TLR9 mAb identified high constitutive expression of equine TLR9 in PMNs, CD4(+) and CD8(+) T-lymphocytes as well as other leukocytes; similar to human TLR9 expression. The conservation of equine TLR9 and high expression profile in leukocytes suggests that equine TLR9 is a frequent target for unmethylated CpG-DNA, an essential mechanism for the activation of innate immunity.
Publication Date: 2008-03-22 PubMed ID: 18462806DOI: 10.1016/j.vetimm.2008.03.005Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The researchers have investigated the functioning of the innate immune system in horses by cloning and characterizing a protein called Toll-like receptor 9 (TLR9). This protein plays a key role in the immune system by recognizing certain components of harmful bacteria and viruses, leading to an immune response.
Objective of the Research
- The main aim of this research was to investigate the innate immune responses in horses through the TLR9 signaling pathway. This was carried out by the cloning and characterization of equine TLR9, a protein that forms a crucial part of the immune response in horses.
Characteristics of TLR9
- TLR9 is typically expressed inside immune cells, such as dendritic cells. It identifies unmethylated bacterial or viral DNA, a common part of many harmful microbes. It is part of a broader group of proteins known as germline-encoded pattern recognition receptors (PRRs).
- Through a protein sequence analysis, it was demonstrated that equine TLR9 contains a typically conserved cytosolic Toll/interleukin-1 receptor (TIR) domain and three leucine-rich repeat (LRR) motifs. It showed more than 82% identity to TLR9 in humans, monkeys, cows, dogs, cats, pigs, and sheep.
Expression of Equine TLR9 mRNA
- Equine TLR9 mRNA expression was measured in the spleen, lymph node, and peripheral blood leukocyte samples from horses.
- An analysis of equine TLR9 expression using flow cytometry and a cross-reactive TLR9 mAb showed that the protein is highly expressed in PMNs, CD4(+) and CD8(+) T-lymphocytes as well as other leukocytes. This pattern of expression is similar to TLR9 expression in humans.
Implications for Innate Immunity
- The high degree of conservation of equine TLR9, together with its high expression profile in immune cells, suggests that it likely often interacts with unmethylated CpG-DNA, leading to activation of innate immunity.
- In effect, the researchers suggest that equine TLR9 plays an important role in the horse’s immune response to harmful bacteria and viruses.
Cite This Article
APA
Zhang YW, Davis EG, Blecha F, Wilkerson MJ.
(2008).
Molecular cloning and characterization of equine Toll-like receptor 9.
Vet Immunol Immunopathol, 124(3-4), 209-219.
https://doi.org/10.1016/j.vetimm.2008.03.005 Publication
Researcher Affiliations
- Department of Anatomy and Physiology, Kansas State University, College of Veterinary Medicine, Manhattan, KS 66506, USA. yzhang@vet.ksu.edu
MeSH Terms
- Animals
- Cloning, Molecular
- Flow Cytometry / veterinary
- Horses / genetics
- Horses / immunology
- Immunity, Innate / immunology
- Phylogeny
- RNA / chemistry
- RNA / genetics
- Random Amplified Polymorphic DNA Technique / veterinary
- Reverse Transcriptase Polymerase Chain Reaction / veterinary
- Sequence Analysis, DNA / veterinary
- Toll-Like Receptor 9 / genetics
- Toll-Like Receptor 9 / immunology
Citations
This article has been cited 4 times.- Tarlinton RE, Alder L, Moreton J, Maboni G, Emes RD, Tötemeyer S. RNA expression of TLR10 in normal equine tissues. BMC Res Notes 2016 Jul 19;9:353.
- Figueiredo MM, Amorim IF, Pinto AJ, Barbosa VS, Pinheiro Lde J, Deoti B, Faria AM, Tafuri WL. Expression of Toll-like receptors 2 and 9 in cells of dog jejunum and colon naturally infected with Leishmania infantum. BMC Immunol 2013 May 14;14:22.
- Werners AH, Bryant CE. Pattern recognition receptors in equine endotoxaemia and sepsis. Equine Vet J 2012 Jul;44(4):490-8.
- Schneberger D, Lewis D, Caldwell S, Singh B. Expression of toll-like receptor 9 in lungs of pigs, dogs and cattle. Int J Exp Pathol 2011 Feb;92(1):1-7.
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