TNF and periodontitis: IL‐6 and IL‐8 are both associated with periodontitis.[61] Together with molecules such as LPS or TNFα, IL‐6 is activating the inflammatory response in endothelial cells.[62] PDLCs have been reported in previous studies to express IL‐6 and IL‐8 upon bacterial challenge,[63] indicating that the PDLCs in our study is also likely to contribute to the upregulation of these inflammatory cytokines to initiate the innate immune response.