We previously reported that Treponema denticola, a periodontal pathogen, suppressed the expression of human ${eta}$-defensins (HBDs) and IL-8 in human gingival epithelial cells. To clarify the receptor(s) involved in the suppression of HBD-2, immortalized gingival epithelial (HOK-16B) cells were infected with live or heat-killed T. denticola for 24 h, and the expression of HBD-2 was examined by real-time RT-PCR. Live T. denticola, but not heat-killed bacteria, suppressed the expression of HBD-2 about 40%. Time courses of suppression revealed that T. denticola suppressed HBD-2 expression only at late time points, which was accompanied with the suppression of TNF${alpha}$ production. Neutralization of TNF${alpha}$ with an antibody abrogated the suppressive effect of T. denticola on HBD-2. Accordingly, heat-killed T. denticola did not suppress TNF${alpha}$ production. Knock-down of toll-like receptor (TLR) 2 via RNA interference reversed the suppressive effect of T. denticola on the expression of HBD-3, but not on the production of TNF${alpha}$. Collectively, T. denticola suppresses the expression of HBD-2 in gingival epithelial cells by inhibiting the TLR2 axis and TNF${alpha}$ production, which may contribute to the pathogenesis of periodontitis by T. denticola.