It is becoming clear that periodontitis is not only characterized by pathogenic infection, but even more so by a loss of immunological homeostasis. Strategies toward regenerating the periodontium without completely blocking immune responses against local and systemic infections would be ideal. Based on recent insights into regulatory T cell biology, and their absence in periodontitis, we hypothesize that the recruitment of regulatory T cells to the periodontium will resolve disease symptoms and promote a regenerative milieu. To this end, we have developed a preliminary controlled release formulation for the delivery of a regulatory T cell recruiting factor (CCL-22). In our periodontal disease mouse model, intra-periodontal pocket delivery of this formulation increased regulatory T cell migration to the periodontium and led to the amelioration of disease symptoms. To further understand the mechanisms for regulatory T cell (Treg) therapy in periodontitis and develop more clinically viable therapeutics, we purpose the following aims. Specific Aim I: Investigation into the therapeutic mechanisms of Treg recruiting formulations. Herein we will examine the kinetics of regulatory T cell migration to, and residence in, the periodontium based on our current therapeutic formulation, in an experimental model of murine periodontitis. Furthermore, we will track the expression of Treg-associated factors, pro- and anti-inflammatory mediators, as well as factors that lead to hard and soft tissue destruction, to observe how Treg presence influences their presentation in the periodontium. Finally, to test the regenerative properties of Treg-recruiting formulations, we will use a live animal imaging technique to measure alveolar bone levels before, and after, treatment. Specific Aim II: Rational design of CCL-22 microparticles engineered to autonomously produce complex release characteristics. Our data strongly suggests a therapeutic effect associated with our preliminary formulation of Treg recruiting (CCL-22) microparticles after multiple injections. To make a more clinically- desirable therapy, we propose to use new mathematical models to engineer two different formulations that produce precisely defined release behavior according to two hypothetical schedules of complex chemokine delivery. Specific Aim III: Examination of VIP as a potential mediator of CCL-22 secretion by native cells. Our preliminary data shows treatment with vasoactive intestinal peptide (VIP) up-regulates the expression of endogenous Treg recruiting chemokine CCL-22 in gingival tissues of mice. Because VIP is attractive from a product development standpoint, we will investigate the therapeutic potential of VIP both systemically and through long-lasting, controlled delivery to the periodontal pocket.