UCSF

Periodontal disease (PD) is a complex infection driven by a myriad of bacterial species interacting with host tissues, triggering the release of pro-inflammatory cytokines, chemokines, and tissue-remodeling enzymes like Matrix Metalloproteinases (MMP), culminating in periodontal tissue degradation. Despite clinical intervention, severe periodontitis patients exhibit a persistent pro-inflammatory state, perpetuating tissue destruction. Treponema denticola (T. denticola), an oral anaerobic bacteria, notably abundant in advanced lesions, harbors potent and abundantly expressed virulence factors, including the chymotrypsin-like protease complex (CTLP or dentilisin), implicated in various pathogenic activities like adhesion, ECM degradation, and MMP activation. Our research has shown elevated T. denticola DNA levels correlated with increased MMP2 mRNA expression. Short-term exposure of human periodontal ligament fibroblast cells (hPDL) to wild-type T. denticola bacteria led to prolonged upregulation of the MMP-2-MMP-14-TIMP-2 activation axis for up to 12 days in Vitro. Despite extensive protein-level studies, direct links between T. denticola protease activity and periodontal tissue destruction at transcriptional or epigenetic levels remain scarce. Chemically characterized as a tri-acylated lipoprotein, dentilisin more than likely engages with TLR2-dependent mechanisms. Thus, based on literature and current data from our laboratory, we hypothesize that T. denticola exploits dentilisin to activate a TLR2-dependent pathway, inducing the upregulation of tissue-destructive genes in hPDL cells. This work sheds light on the specific interactions between human periodontal ligament cells and T. denticola, elucidating the transcriptional drivers of periodontal disease chronicity using an array of molecular techniques and high-throughput sequencing methods, revealing potential therapeutic targets beyond antibiotics.