Protease-activated receptors and their role in IL-6 and NF-IL-6 expression in human gingival fibroblasts

• Published in: Journal of periodontal research Vol. 33; no. 4; pp. 205 - 211
• Main Authors: Hou, L., Ravenall, S., Macey, M. G., Harriott, P., Kapas, S., Howells, G. L.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-05-1998; Blackwell
• Subjects: Biological and medical sciences; Blood Coagulation - physiology; Blotting, Northern; CCAAT-Enhancer-Binding Proteins; Dentistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - physiology; Facial bones, jaws, teeth, parodontium: diseases, semeiology; Fibroblasts - cytology; Fibroblasts - metabolism; Flow Cytometry; Gene Expression Regulation; Gingiva - cytology; Gingiva - metabolism; human gingival fibroblasts; Humans; IL-6; Inflammation Mediators - physiology; Interleukin-6 - genetics; Interleukin-6 - physiology; Ligands; Medical sciences; NF-IL-6; Non tumoral diseases; Nuclear Proteins - genetics; Nuclear Proteins - physiology; Otorhinolaryngology. Stomatology; Peptide Fragments - physiology; Periodontal Diseases - etiology; Periodontitis - etiology; protease-activated receptors; Receptor, PAR-1; Receptor, PAR-2; Receptors, Cell Surface - physiology; Receptors, Thrombin - physiology; Recombinant Proteins; RNA, Messenger - analysis; RNA, Messenger - genetics; Thrombin - physiology; Transcription Factors - genetics; Transcription Factors - physiology; Human; Cell culture; Flow cytometry; Enzyme; Stomatology; Pathogenesis; Cytokine; Activation; Inflammation; In vitro; Interleukin 6; Northern blotting; Peptidases; Periodontal disease; Thrombin(drug); Periodontitis; Hydrolases; Molecular biology; Transcription factor; Gingiva; Fibroblast; Biological receptor
• ISSN: 0022-3484; 1600-0765
• DOI: 10.1111/j.1600-0765.1998.tb02192.x

The serine protease thrombin is formed at sites of coagulation and inflammation and has been shown to have important proinflammatory cellular effects relevant to the pathogenesis of periodontal disease. Thrombin acts via specific cell surface receptors termed protease‐activated receptor‐1 (PAR‐1) and PAR‐3, which have a distinctive method of activation. Proteolytic cleavage of the extracellular domain by thrombin reveals a hidden amino terminus which then acts as a “tethered ligand”. A short synthetic peptide (SFLLRN) can also mimic the tethered ligand and activate PAR‐1 but not PAR‐3. Also, a trypsin‐sensitive receptor termed PAR‐2 has been described which is activated by the PAR‐1 activating peptide SFLLRN. Here we show conclusively by flow cytometric and Northern blot analysis that human gingival fibroblasts (HGF) express PAR‐1 but not PAR‐2. In functional studies we also show that thrombin and SFLLRN stimulated increased expression of mRNA encoding nuclear transcription factor NF‐IL‐6 and IL‐6 in vitro. At optimal concentrations, thrombin (10−7 M) induced 7.6±0.01 ng/ml immunoactive IL‐6 and PAR‐1 activating peptide (5 × 10−5 M) induced 2.2 ± 0.2 ng/ml (mean ± standard error of mean). A proteolytically inactive recombinant thrombin (serine 195 to alanine) was without activity. These data show that HGF express PAR‐1 and suggest that PAR‐1 activation stimulates increased NF‐IL‐6 and IL‐6 gene expression and IL‐6 secretion by HGF in vitro. Whether HGF express PAR‐3 is unknown, but the fact that SFLLRN was not a complete replacement for thrombin raises the possibility that HGF may express additional thrombin receptors. These findings add weight to the importance of the cytokine‐like role played by thrombin and raise the possibility that protease‐activated receptors may play a role in the pathogenesis of inflammatory periodontal disease.