The role of Toll‐like receptors in periodontitis

Abstract

Periodontitis is a common infectious disease. Recent studies have indicated that the progression of periodontitis may be regulated by interactions between host immunity and periodontopathic bacteria. Although periodontopathic bacteria can destroy periodontal tissue, a dysfunctional host immune response triggered by the bacteria can lead to more severe and persistent destruction. Toll-like receptors (TLRs), a type of pattern recognition receptor (PRR) that recognizes pathogens, have been implicated in host innate immune responses to periodontopathic bacteria and in the activation of adaptive immunity. TLR-targeted drugs may hold promise to treat periodontal disease. This review summarizes recent studies on the role of TLRs in periodontitis and discusses areas needing further research. We believe TLRs may be an effective biomarker for the prevention, diagnosis, and treatment of periodontitis in the near future.

C5aR1 interacts with TLR2 in osteoblasts and stimulates the osteoclast‐inducing chemokine CXCL10

“…The role of complement in bone development and regeneration after traumatic injury has been reviewed . Fewer data are available on the impact of TLRs on bone, still, they have been ascribed a clear impact on inflammation and bone resorption in an infectious microenvironment, for example in periodontitis . Of note, C5aR1 is also crucial for the development of periodontal disease, which is frequently accompanied by bone loss and subsequent tooth loss .…”

“…3,4 Fewer data are available on the impact of TLRs on bone, still, they have been ascribed a clear impact on inflammation and bone resorption in an infectious microenvironment, for example in periodontitis. 48,49 Of note, C5aR1 is also crucial for the development of periodontal disease, which is frequently accompanied by bone loss and subsequent tooth loss. 10,11,50 Pharmacological inhibition of C5aR1 reduces periodontal inflammation and can reverse an already established disease.…”

Necroptosis in the periodontal homeostasis: Signals emanating from dying cells

“…Death of both resident cells and immune cells during periodontitis progress has long been recognized; however, its role in periodontal diseases progress has seldom been addressed (Song, Zhang et al., ; Song, Zhou, Yang, Liu, & Shao, ). Putative periodontal pathogens, such as Treponema denticola, P. gingivalis, and Tannerella forsythia , elicited the release of adenosine triphosphate (ATP), uric acid, HSP60, and HMGB1 from defense cells, indicating the presence of cell death in periodontal tissue (Jun, Jung, & Choi, ).…”

Synergistic effects triggered by simultaneous Toll‐like receptor‐2 and ‐3 activation in human periodontal ligament stem cells

“…Ten different TLRs have been discovered in humans so far, differing in their ligands, localization, structure, and partially in signaling pathways . Several members of the TLR family are supposed to be involved in the recognition of bacterial and viral components in periodontal disease . TLR‐2 is located on the cell surface and recognizes various PAMPs including lipoproteins, peptidoglycans, and lipoteichoic acids.…”

“…TLRs play an important role in both periodontal health maintenance and periodontitis progression . The contribution of TLR‐2 and TLR‐4 to periodontal disease is investigated at most.…”