The increased expression of suppressors of cytokine signaling (SOCS) proteins in periodontitis was recently reported [[45]]. Both SOCS-1 and SOCS-3 are able to inhibit MxA expression [[46]]. In conclusion, this study demonstrates that α-defensins, antimicrobial peptides constitutively expressed in healthy periodontal tissue, induce expression of a classical antiviral protein, MxA, in gingival epithelium. Strong MxA activity at the strategic gingival sulcus, in close proximity to microbial

plaque, may serve as one of the important innate tools in maintaining periodontal homeostasis. We believe that our findings warrant further research into the physiological role of α-defensin-induced MxA in the antiviral response of the periodontal tissue. Antimicrobial peptides: human α-defensin-1, -2, and -3, human β-defensin-1, -2, and -3, and LL-37 PLX-4720 were obtained from Innovagen (Lund, Sweden). IFN-α and neutralizing antibodies against IFN-α and IFN-β were

purchased from PBL Biomedical Laboratory (Piscataway, NJ, USA). Neutralizing antibody against α-defensins was obtained from Hycult biotech (Uden, The Netherlands). Polymorphprep was purchased from Axis-Shield PoC AS (Oslo, Norway). Tissue specimens were collected from patients (one biopsy Roscovitine per one patient) at Periodontal Clinic and Department of Oral Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University. The ethical approval by the ethics committee of Faculty of Dentistry, Chulalongkorn University and informed consent of all participating

subjects were obtained before operation. Healthy periodontal tissue samples were collected from sites with clinically healthy gingiva (no gingival inflammation, probing depth < 4 mm, and no radiographic bone loss) during crown-lengthening procedure for prosthetic reasons. Severe periodontitis tissue samples were collected from sites of extracted teeth with hopeless prognosis (inflamed gingiva, probing depth > 6 mm, and bone loss 3-mercaptopyruvate sulfurtransferase > 60% of the root). Periodontal tissue specimens used for immunostaining, real-time quantitative RT-PCR, and in vitro cultures were derived from different donors. The primary HGECs, derived from healthy periodontal tissue, were obtained following established procedure [[9]]. In brief, the excised tissues were immediately washed with Dulbecco’s phosphate buffered saline and digested in 0.2% dispase for 24 h at 4°C. The separated epithelial layer was washed, minced, and cultured in a serum-free keratinocyte growth medium (Clonetics, Walkersville, MD, USA) supplemented with human recombinant epidermal growth factor, hydrocortisone, bovine insulin, bovine pituitary extract, gentamicin sulfate, amphotericin B, and 0.15 mM CaCl2. The HGEC cultures at passage two to four were used throughout the study. Total RNA from periodontal tissue samples and HGECs were isolated by using an RNeasy Mini kit from Qiagen (Hilden, Germany).