A short symmetric antimicrobial peptide with enhanced resistance to gingipain-mediated degradation in Porphyromonas gingivalis

초록

Periodontitis is a widespread chronic inflammatory disease driven by biofilm-forming oral bacteria. Porphyromonas gingivalis, a proteolytic anaerobe that secretes gingipains, plays a central role in disease progression by disrupting host defense mechanisms. Although mechanical debridement and antibiotic therapy are standard treatments, they are often ineffective against biofilm-associated bacteria and may contribute to antimicrobial resistance. Antimicrobial peptides (AMPs) have emerged as promising alternatives; however, their application in the oral cavity is frequently limited by proteolytic degradation. Here, we rationally designed short, symmetric AMPs with enhanced resistance to gingipain-mediated proteolysis and evaluated their antimicrobial and antibiofilm activities. Among these, APP3 demonstrated potent antimicrobial activity (MIC = 4-8 mu M) against P. gingivalis, Fusobacterium nucleatum, and Streptococcus gordonii, while exhibiting minimal cytotoxicity and hemolysis. APP3 retained antimicrobial activity following exposure to gingipain-containing P. gingivalis culture supernatants. Furthermore, APP3 effectively inhibited mono- and dual-species biofilms involving P. gingivalis and F. nucleatum, accompanied by downregulation of genes associated with adhesion and biofilm maturation. Structural analyses revealed that APP3 adopts an alpha-helical conformation in membrane-mimicking environments and exerts antibacterial activity through membrane disruption. Collectively, these findings identify APP3 as a protease-resistant and selective AMP, demonstrating a structure-based strategy for targeting gingipain-associated pathogenic mechanisms relevant to periodontitis.

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