Innate immune response of human periodontal ligament fibroblasts via the Dectin-1/Syk pathway

A diverse microbiota including fungi exists in the subgingival sites of patients with chronic periodontitis. The cell wall of , the most abundant fungal species, contains β-glucan. Dectin-1 binds β-glucan and participates in fungal recognition. Human periodontal ligament fibroblasts (PDLFs) are present in the periodontal ligament and synthesize immunomodulatory cytokines that influence the local response to infections. However, the expression and role of Dectin-1 in PDLFs have not been explored. This study aimed to determine if PDLFs express Dectin-1 and induce innate immune responses through Dectin-1 and the signalling molecule Syk. The expression of Dectin-1 in PDLFs was determined by flow cytometry, western blotting and confocal microscopy. Real-time PCR and Western blotting were used to determine the immune response of PDLFs stimulated with β-glucan-rich zymosan and . Dectin-1 was constitutively expressed in PDLFs. Zymosan induced the expression of cytokines, including , and , and the chemokine . Zymosan also induced the expression of the antimicrobial peptide β-defensin-1 ( ). Further, the phosphorylation of Syk and NF-κB occurred upon Dectin-1 activation. Notably, heat-killed induced the expression of , , and , and this activation was suppressed by the Syk inhibitor, R406. These findings indicate that the Dectin-1/Syk pathway induces an innate immune response of PDLFs, which may facilitate the control of oral infections such as candidiasis and periodontitis.