2026 Volume 68 Issue 3 Pages 138-146
Objective: To determine whether the antifibrinolytic agents, tranexamic acid (TXA) and ε-aminocaproic acid (EACA), affect Porphyromonas gingivalis adherence, invasion, and infection of gingival epithelial cells as well as downstream inflammatory responses in vitro, and to assess the involvement of host receptor pathways (TLR-4 and caspase-4).
Methods: Human oral keratinocytes (hOK) were challenged with Porphyromonas gingivalis ATCC 33277. For gene expression and protein analyses, hOK were infected at an MOI of 10 for 6 h in the presence or absence of TXA or EACA (1, 10, 100 mM). Infection assays employed CFSE-labeled Porphyromonas gingivalis at an MOI of 500 for 2 h. Attachment/internalization was evaluated by fluorescence microscopy and flow cytometry. Gene expressions of IL-1β and IL-6 were quantified by qRT-PCR (TaqMan assays). Protein levels of TLR-4 and caspase-4 were compared by Western blot analyses. The functional roles of TLR-4 and caspase-4 were assessed using siRNA knockdown. The antibacterial activities of TXA and EACA were determined by MIC agar dilution. Experiments were performed in triplicate; ANOVA with Tukey's post hoc test was used for the statistical analysis (p < 0.05, p < 0.01, p < 0.001).
Results: TXA and EACA at 10 mM significantly reduced Porphyromonas gingivalis attachment and apparent internalization to hOK. Accordingly, infection-induced IL-1β and IL-6 mRNA expressions were suppressed in the TXA/EACA-treated cells. TXA/EACA treatment resulted in no significant change of the total TLR-4 protein, whereas it prevented the infection-associated decrease in caspase-4. siRNA knockdown of caspase-4 reduced infection-induced IL-1β and IL-6 expressions, whereas siTLR-4 had limited effect. MIC testing indicated no bactericidal activity at the experimental concentrations (MICs: TXA ≥254.6 mM, EACA ≥304.9 mM).
Conclusions: TXA and EACA inhibit Porphyromonas gingivalis infection of gingival epithelial cells and suppress the induction of IL-1β and IL-6. These antifibrinolytic agents have the potential to prevent excessive immune responses by blocking the entry of pathogens into epithelial cells, which may explain the clinically observed improvements in bleeding and inflammation. Furthermore, these findings suggest a potential prophylactic and therapeutic role of TXA/EACA in suppressing the onset and progression of periodontitis.
