The role of the alpha7 nicotinic receptor in regulating the Pophyromonas gingivalis-induced expression of interleukin-8 by oral keratinocytes

RK Dentistry

Zoheir, Noha ; Nile, Christopher

University:University of Glasgow

Department:School of Medicine, Dentistry & Nursing

关键词: alpha7 nicotinic receptor, cholinergic anti-inflammatory pathway, immune response, Periodontal disease,Porphyromonas gingivalis;   

Others  :  http://theses.gla.ac.uk/5086/7/2013ZoheirMSc.pdf

来源: University of Glasgow

【 摘 要 】

There is increasing evidence for a role of acetylcholine in modulating the inflammatory response. This has been demonstrated to occur predominantly via the ‘cholinergic anti-inflammatory pathway’ and mediated by the α7 nicotinic acetylcholine receptor (α7nAChR). Therefore, there is now an abundance of in vitro and in vivo evidence that suggest pharmacologically target the α7nAChR is a potential anti-inflammatory therapy to treat chronic inflammatory diseases. The role of acetylcholine and the α7nAChR in modulating the periodontal immune response is at present unknown. However, as nu-merous cells within the periodontium express the α7nAChR it is interesting to speculate that targeting this receptor may modulate the periodontal immune response. Therefore, his study aims to investigate the effects of the α7nAChR on the periodontal pathogen (P. gingivalis) induced expression of Interleukin-8 (IL-8) by oral keratinocytes. Expression of the α7nAChR mRNA was demonstrated to be upregulated in diseased periodontal tissue. In line with previous studies, oral keratinocytes were found to ex-press the α7nAChR using PCR. The acetylcholine mimic; Carbachol when used in high concentrations was found to inhibit dead P. gingivalis induced IL-8 expression by OKF6-TERT2 cells in vitro. The expression of IL-8 was investigated at both the protein level by ELISA and the transcriptional level by real time PCR. In contrast, the specific α7nAChR agonist (PHA 543613 hydrochloride) when used at pharmacological concen-trations potently inhibited expression of IL-8 by OKF6-TERT2 cells cultured with a live P. gingivalis biofilm. This was again determined using ELISA and real time PCR. A membrane integrity assay confirmed that the agonist exhibited no toxic effects on the cells. The inhibition of IL-8 expression was found to be mediated at the transcriptional level. Indeed, using a Fast Activated Cell-based ELISA (FACE) NF-κB p65 Profiler Kit activation of the α7nAChR inhibited the phosphorylation of the NF-κB p65 subunit at Serine 468 and serine 536. Therefore, it can be hypothesised that targeting the α7nAChR leads to inhibition of NF-κB p65 subunit translocation into the nucleus and thus downregulated IL-8 transcription.These data suggest that the α7nAChR plays a role in regulating the pathogen induced immune response at epithelial surfaces. As dysregulated immunity is a hallmark of peri-odontal disease it is interesting to speculate that pharmacologically targeting the α7nAChR may offer a novel immune-modulatory therapy.