Low magnitude of tensile strain inhibits IL-1beta-dependent induction of pro-inflammatory cytokines and induces synthesis of IL-10 in human periodontal ligament cells in vitro.

Applied mechanical loading induces inflammation in the periodontal ligament (PDL). However, the mechanisms involved in bone deposition at tension sites in an inflammatory environment are not clear. Here, in an in vitro model system, we show that equibiaxial tensile strain of low magnitude (TENS) provokes potent anti-inflammatory signals in PDL cells. TENS inhibits IL-1beta-induced synthesis of IL-1beta, IL-6, and IL-8 by inhibiting their mRNA expression, and thus significantly suppresses the amplification of IL-1beta-induced inflammatory responses in PDL cells. Additionally, as an anti-inflammatory signal, TENS induces IL-10 synthesis in the presence and absence of IL-1beta. These observations are the first to demonstrate that TENS antagonizes IL-1beta actions on PDL cells by (i) inhibiting IL-1beta-induced transcriptional regulation of proinflammatory cytokines, and (ii) inducing synthesis of IL-10, which may post-transcriptionally suppress the synthesis of pro-inflammatory cytokines.