Abstract
BackgroundProtease-activated receptors (PARs) are G-protein-coupled receptors with an active role in mediating inflammation, pain and other functions. The oral pathogen Porphyromonas gingivalis (P. gingivalis) secretes proteases that activate PARs. The aim of this study was to elucidate the role of PARs in the pathogenesis of chronic periodontitis by expression analysis of PARs in human gingival epithelial cells (GECs) before and after P. gingivalis supernatants treatment.MethodsGECs were isolated from healthy human gingival tissue samples. The expression of PARs in GECs was determined by reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry. The effect of P. gingivalis proteases was investigated by quantitative real-time reverse transcription polymerase chain reaction (QRT-PCR) and flow cytometry.ResultsPAR-1, PAR-2, and PAR-3 were expressed in GECs. PAR-4 was not found by both RT-PCR and flow cytometry. Analysis of gene expression using QRT-PCR showed an up-regulation of PAR-2 mRNA in comparison to the untreated control cells (P < 0.05). In contrast, the mRNA expressions of PAR-1 and PAR-3 were significantly down-regulated (P > 0.05) in response to P. gingivalis supernatant compared to that in unstimulated control cells. This effect was abrogated by the protease inhibitor TLCK (P < 0.05). The results of flow cytometry indicated PARs protein levels consistent with mRNA levels in the results of QRT-PCR.ConclusionsOur study shows that PAR-1, PAR-2 and PAR-3 are expressed in GECs. P. gingivalis proteases play a role in the regulation of innate immune responses in GECs. GECs use PARs to recognize P. gingivalis and mediate cell responses involved in innate immunity.
Highlights
Protease-activated receptors (PARs) are G-protein-coupled receptors with an active role in mediating inflammation, pain and other functions
reverse transcription-polymerase chain reaction (RT-PCR) analysis of PARs in gingival epithelial cells (GECs) RT-PCR analysis of RNA extracted from GECs revealed the presence of PAR-1, PAR-2 and PAR-3 mRNA (Fig. 1)
The result shows that PAR-1, PAR-2 and PAR-3 are expressed in GECs, but PAR-4 is not
Summary
Protease-activated receptors (PARs) are G-protein-coupled receptors with an active role in mediating inflammation, pain and other functions. The oral pathogen Porphyromonas gingivalis (P. gingivalis) secretes proteases that activate PARs. The aim of this study was to elucidate the role of PARs in the pathogenesis of chronic periodontitis by expression analysis of PARs in human gingival epithelial cells (GECs) before and after P. gingivalis supernatants treatment. The activation of PARs occurs by a unique mechanism that involved specific proteolytic cleavage of the N-terminal extracellular sequence by a protease This cleavage unmasks a new N-terminal sequence, Zhang et al BMC Oral Health (2015) 15:128. Human gingival epithelial cells (GECs), which are key factors of innate immunity, play an important role in maintaining the physical barrier between the host and the environment and actively participate in tissue innate immunity [10, 11] by expressing certain receptors that are involved in the host immune response. PARs are known to be expressed in the epithelium of gingiva and have been implicated in the pathogenesis of periodontitis [15,16,17,18]
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