A Multifunctional β‐Defensin‐3 Mimetic Peptide Modulates Host–Biofilm Interactions and Reduces Bone Loss in Periodontitis

AIM: This study evaluated the potential of a beta-defensin-3 mimetic peptide (BDMP), a synthetic cell-penetrating peptide with antimicrobial and immunomodulatory properties, as an adjunctive therapeutic approach for periodontitis. METHODS: BDMP was formulated in a hydroxyethyl cellulose (HEC) gel and assessed for binding affinity, release kinetics, and ability to penetrate cells and gingival tissues. Anti-inflammatory and osteoclast-related signaling pathways were examined in vitro using RAW264.7 macrophages stimulated with lipopolysaccharide (LPS). Effects on osteogenic recovery were evaluated in periodontal ligament stem cells (PDLSCs) under inflammatory conditions. Antimicrobial activity against multispecies biofilms was analyzed by confocal microscopy. In a ligature-induced experimental periodontitis model in beagle dogs, BDMP gel was compared with a subgingival instrumentation (SI)-only (standard-of-care) control, and minocycline gel was included as an active adjunctive comparator. Clinical parameters, inflammatory markers, microbial load, radiographs, micro-CT images, and histology were evaluated. RESULTS: In vitro, BDMP reduced histone deacetylase 5 (HDAC5) phosphorylation and attenuated downstream NF-κB-associated inflammatory signaling without altering upstream kinase activity. BDMP decreased osteoclast differentiation, reduced inflammatory cytokine transcription, and partially restored osteogenic capacity in LPS-stimulated PDLSCs. BDMP also demonstrated broad-spectrum antimicrobial activity and disrupted mature multispecies biofilms. In vivo, BDMP resulted in greater reductions in gingival inflammation, bleeding, IL-1β levels, and oral spirochetes over 12 weeks compared with the SI-only control. Radiographic images provided qualitative support for reduced bone loss, which was corroborated by micro-CT and histology, indicating attenuation of alveolar bone resorption. When compared with the combination of SI and minocycline arm, BDMP showed comparable or greater improvements in several inflammatory and microbiological parameters. CONCLUSION: BDMP exhibited sustained antimicrobial and anti-inflammatory activity and attenuated bone loss in a beagle periodontitis model when used alongside standard SI therapy. These findings support BDMP as a promising adjunctive therapeutic candidate for managing periodontal inflammation and biofilm-associated disease, although further studies are needed to confirm long-term safety and to define its mechanistic contributions to periodontal tissue preservation.