Gingival Toll-like receptor and cytokine messenger RNA levels in equine periodontitis and oral health.
BACKGROUND
Equine periodontitis is a common and painful condition. However, the disease often goes unnoticed by owners and is thus a major welfare concern. The aetiopathogenesis of the condition remains poorly understood and has been investigated in few studies. The innate immune system is known to play an important role in human periodontitis, but its role in equine periodontitis has not been examined.


OBJECTIVE
To quantify the messenger (m)RNA levels of Toll-like receptors (TLRs) and cytokines in gingival tissue from orally healthy horses and those affected by periodontitis.


METHODS
Observational study.


METHODS
Gingival tissue samples were taken post-mortem from 13 horses with no clinical signs of oral disease and 20 horses with periodontitis. mRNA levels of TLR2, TLR4 and TLR9 and cytokines interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α), IL-4, IL-6, IL-10, IL-12, IL-17 and interferon-γ (IFN-γ) were determined using quantitative real-time PCR. The statistical significance of results was assessed using appropriate t tests.


RESULTS
mRNA levels of all TLRs and cytokines were upregulated in equine periodontitis. Significant increases in mRNA levels of TLR2, TLR9, IL-4, IL-10, IL-12 (P≤0.05) and IFN-γ (P≤0.01) were observed for both unweighted and age-weighted analyses of diseased gingival tissue samples compared with healthy gingival samples. In comparisons of samples of periodontitis lesions with healthy gingival control samples from the same horse, significant increases in mRNA levels of TLR4, TLR9, IL-10, IFN-γ (P≤0.05), TLR2, IL-1β and IL-12p35 (P≤0.01) were observed.


CONCLUSIONS
This study has provided an initial insight into the involvement of the immune system in equine periodontitis. Increased mRNA levels of TLR2, TLR4 and TLR9 indicate substantial microbial challenge in diseased gingival tissue. A mixed Th1/Th2/Th17 cytokine response is produced in equine periodontitis. Further studies are required to more fully characterise the role of the innate immune system in this disease.
Infection and Immunity Research Group, Dental School, University of Glasgow, UK.
R
R
Kennedy
Infection and Immunity Research Group, Dental School, University of Glasgow, UK.
D F
DF
Lappin
Division of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies and Roslin Institute, University of Edinburgh, UK.
P M
PM
Dixon
School of Veterinary Medicine, University of Glasgow, UK.
D
D
Bennett
Infection and Immunity Research Group, Dental School, University of Glasgow, UK.
M P
MP
Riggio
D000818:Animals; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D006734:Horse Diseases / Q000378:metabolism*; D006736:Horses; D008297:Male; D010518:Periodontitis / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism*
D016207:Cytokines; D012333:RNA, Messenger; D051193:Toll-Like Receptors
Toll-like receptors; bacteria; cytokines; horse; periodontitis