Antiviral innate immune response in periodontal tissue : part I detection of antiviral proteins

Abstract

Periodontitis is a common chronic bacterial inflammatory disease in oral cavity. It affects tooth supporting structure-periodontium and may cause tooth loss. Several recent studies have documented a role of viruses in the development and progression of periodontitis but little that we know about the host immune response to viruses. In this study, we explored the innate antiviral proteins (secretory leukocyte protease inhibitor (SLPI), protein kinase R (PKR), oligoadenylate synthetase (OAS), and myxovirus resistance A (MxA)) in periodontal tissues, comparing between periodontitis and healthy (n=5 in each group). By real-time reverse transcription-polymerase chain reaction, we found expression of SLPI, PKR, OAS, and MxA in periodontitis as well as in healthy tissues and there were no significant differences between the two groups. MxA protein involves in antiviral activity against both RNA and DNA virus, we then focused on the protein expression of MxA in gingival epithelium and compare its expressions between periodontitis (n=7) and healthy (n=9). By immunostaining, healthy tissues showed a higher score of MxA in epithelial layer than those in periodontitis. Of particular interest, we could obtain one complete biopsy of the oral, sulcular and junctional epithelium from healthy tissue. Very strong MxA expression was observed in gingival sulcus area, the strategic location in close proximity to dental plaque biofilms. The significance of this finding needs to be explored. Since MxA is known to be induced by type I interferon, we further examined the presence of this cytokine in periodontal tissues by real-time reverse transcription-polymerase chain reaction. Interestingly, negligible expression of type I interferon was detected, indicating that other mediators or molecules may involve in MxA induction in healthy tissues. In conclusion, this study is the first to report detection of mRNA expression of variety of antiviral proteins (SLPI, PKR, OAS, and MxA) in both periodontitis and healthy tissues. Expression of these proteins in healthy periodontal tissues, especially MxA in gingival sulcus, suggesting effective antiviral innate immunity in the oral cavity. Future research is required for better understanding of the mechanisms and signaling pathway of these antiviral proteins in healthy and periodontitis.