Project Summary Our goal is to develop a first-in-class inhibitor of P. gingivalis colonization of oral biofilms as a treatment for periodontitis. Severe periodontitis affects more than 11% of the world's population, resulting in billions of dollars of direct and indirect costs to society, and is associated with a number of chronic conditions including autoimmune, cardiovascular, respiratory, and neurodegenerative diseases1, 2, 4, 5, 7-9. P. gingivalis is considered a causative species in periodontitis that can function to shape the overall microbial community leading to dysbiosis and tissue damage10-13. Clinical research has confirmed that initial P. gingivalis colonization occurs outside the subgingival pocket14-16. P. gingivalis adheres efficiently to supragingival bacteria such as commensal streptococci17-19. This adherence modulates the pathogenic potential of P. gingivalis and drives colonization20-22. Thus, inhibiting the adherence of P. gingivalis to supragingival bacteria represents an excellent approach to reducing and preventing periodontitis. Our project team originally discovered that initial colonization of the oral cavity by P. gingivalis is mediated by the minor fimbrial antigen (Mfa1) of P. gingivalis binding to the surface antigen I/II of Streptococcus gordonii17, 23-25. Subsequently, we identified a domain in antigen I/II essential to this binding26, 27. A synthetic peptide derived from this region, designated BAR, functions as a potent inhibitor of P. gingivalis adherence and formation of biofilms26, 27. In addition, BAR demonstrates inhibition of P. gingivalis virulence by preventing colonization and subsequent alveolar bone loss in mouse models of severe periodontitis20. More recently, we have generated a lead small molecule mimetic of the BAR peptide (called PG95) to target P. gingivalis in periodontitis. PG95 inhibits P. gingivalis colonization of biofilms and prevents bone loss in mouse models of periodontitis, while showing no toxicity to human cells. The assessment of PG95 using in vitro biofilm models and the mouse model of periodontitis has yielded clear potential as a treatment of periodontitis. Based on these results, our goal is to develop a PG95 mouth rinse for the treatment and prevention of periodontitis. This application is designed to develop quality control assays, define a formulation that is transferable to human clinical trials, determine stability in serum and saliva, and demonstrate safety. The specific aims are to: 1) synthesize PG95, develop a potency assay, and demonstrate efficacy in in vitro biofilm models, 2) define an optimal formulation and determine in vitro PK for PG95, and 3) determine the maximum tolerated dose (MTD) of PG95 following oral administration in mice. Completion of these studies will further support the advancement of PG95 towards clinical development.