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Periodontal disease (PD) is caused by microbial dysbiosis and accompanying adverse inflammatory responses. Due to its high incidence and association with various systemic diseases, disease-modifying treatments that modulate dysbiosis serve as promising therapeutic approaches. In this study, to simulate the pathophysiological situation, we established a “temporary ligature plus oral infection model” that incorporates a temporary silk ligature and oral infection with a cocktail of live Tannerella forsythia (Tf), Pophyromonas gingivalis (Pg), and Fusobacterium nucleatum (Fn) in mice and tested the efficacy of a new trivalent mucosal vaccine. It has been reported that Tf, a red complex pathogen, amplifies periodontitis severity by interacting with periodontopathic bacteria such as Pg and Fn. Here, we developed a recombinant mucosal vaccine targeting a surface-associated protein, BspA, of Tf by genetically combining truncated BspA with built-in adjuvant flagellin (FlaB). To simultaneously induce Tf-, Pg-, and Fn-specific immune responses, it was formulated as a trivalent mucosal vaccine containing Tf-FlaB-tBspA (BtB), Pg-Hgp44-FlaB (HB), and Fn-FlaB-tFomA (BtA). Intranasal immunization with the trivalent mucosal vaccine (BtB + HB + BtA) prevented alveolar bone loss and gingival proinflammatory cytokine production. Vaccinated mice exhibited significant induction of Tf-tBspA-, Pg-Hgp44-, and Fn-tFomA-specific IgG and IgA responses in the serum and saliva, respectively. The anti-sera and anti-saliva efficiently inhibited epithelial cell invasion by Tf and Pg and interfered with biofilm formation by Fn. The flagellin-adjuvanted trivalent mucosal vaccine offers a novel method for modulating dysbiotic bacteria associated with periodontitis. This approach leverages the adjuvant properties of flagellin to enhance the immune response, aiming to restore a balanced microbial environment and improve periodontal health.

Immune checkpoint inhibitors become a standard therapy for malignant melanoma. As immune checkpoint inhibitor monotherapies proved to have limited efficacy in significant portion of patients, it is envisaged that combination with other therapeutic modalities may improve clinical outcomes. We investigated the effect of combining photodynamic therapy (PDT) and TLR5 agonist flagellin-adjuvanted tumor-specific peptide vaccination (FlaB-Vax) on the promotion of PD-1 blockade-mediated melanoma suppression using a mouse B16-F10 implantation model. Using a bilateral mouse melanoma cancer model, we evaluated the potentiation of PD-1 blockade by the combination of peritumoral FlaB-Vax delivery and PDT tumor ablation. A photosensitizing agent, pheophorbide A (PhA), was used for laser-triggered photodynamic destruction of the primary tumor. The effect of combination therapy in conjunction with PD-1 blockade was evaluated for tumor growth and survival. The effector cytokines that promote the activation of CD8+ T cells and antigen-presenting cells in tumor tissue and tumor-draining lymph nodes (TDLNs) were also assayed. PDT and FlaB-Vax combination therapy induced efficacious systemic antitumor immune responses for local and abscopal tumor control, with a significant increase in tumor-infiltrating effector memory CD8+ T cells and systemic IFNγ secretion. The combination of PDT and FlaB-Vax also enhanced the infiltration of tumor antigen-reactive CD8+ T cells and the accumulation of migratory CXCL10-secreting CD103+ dendritic cells (DCs) presumably contributing to tumor antigen cross-presentation in the tumor microenvironment (TME). The CD8+ T-cell-dependent therapeutic benefits of PDT combined with FlaB-Vax was significantly enhanced by a PD-1-targeting checkpoint inhibitor therapy. Conclusively, the combination of FlaB-Vax with PDT-mediated tumor ablation would serve a safe and feasible combinatorial therapy for enhancing PD-1 blockade treatment of malignant melanoma.