PROJECT SUMMARY/ABSTRACT Aggressive forms of periodontitis associated with Aggregatibacter actinomycetemcomitans (Aa) are often difficult to treat with traditional means (scaling and root planing, in combination with systemic antibiotics). During infection, Aa produces a leukotoxin (LtxA) that kills host immune cells, thus reducing the host’s ability to clear the infection. Although an association between LtxA expression levels and pathogenicity of Aa has been well documented, particularly in adolescent patients, and the mechanisms by which LtxA kills host cells have been well studied, few new treatment options have been developed in recent years. We propose that LtxA represents an ideal therapeutic target that could be exploited to develop next generation therapeutics for Aa infections in juveniles. The long-term goal of the PI is to develop LtxA-focused therapeutics for the treatment of Aa. The overall objective of this project is to construct a liposome-based, LtxA-responsive antibiotic delivery vehicle to treat Aa infections. The general hypothesis is that LtxA will enable antibiotic release only in the presence of pathogenic (LtxA- expressing) strains of Aa. The general hypothesis will be tested via the following specific aims: (1) Optimize liposome composition to promote LtxA adsorption and LtxA-mediated disruption and (2) Determine the therapeutic liposome concentrations necessary to enhance host cell survival. In Aim 1, we will optimize the composition of the liposome to enhance LtxA-mediated antibiotic release and LtxA adsorption. In Aim 2, we will test the effect of the liposomes on host cell survival in a co-culture model of infection. At the successful completion of the proposed research, the expected outcome is a novel therapeutic option to treat Aa infections in adolescents. The innovation of the proposed work lies in its use of LtxA as a therapeutic target, as well as the development of a controlled antibiotic delivery vehicle for the treatment of aggressive periodontitis. These results will provide a strong basis for the future development of LtxA-focused therapeutics, which is expected to have a significant impact on the clinical treatment of Aa-associated infections in juveniles by providing additional, non- surgical options. This research aligns with NIDCR’s mission to improve oral health through its development of a new treatment for periodontal infections.

PROJECT NARRATIVE This project aims to develop a novel antibiotic delivery vehicle to enable the controlled delivery of antibiotics to treat aggressive periodontal infections in adolescents. Current treatment options are often ineffective, necessitating multiple treatments to clear the infection. The outcome of this work will be a novel non-surgical therapeutic to enhance current treatment options.