“Submandibular Injection of Indoleamine 2,3-Dioxygenase Galectin-3 Fusion Protein Inhibits and Prevents Periodontal Disease Progression Over 12 Weeks”

A major challenge in the treatment of chronic inflammatory diseases including periodontal diseases is the development of therapeutics to safely and specifically direct resolution of inflammation in a localized manner. Here we demonstrate the efficacy of a novel approach that addresses this unmet clinical need. Using an enzyme fusion protein of indoleamine 2,3-dioxygenase 1 (IDO) and galectin-3 (Gal3) with tissue-anchored and thus localized immunomodulatory properties, we prevented and halted progression of induced polymicrobial periodontal disease. Efficacy was achieved with repeated treatment with IDO-Gal3 and was measured by effects on mandibular bone loss, soft tissue inflammation and local T cell plasticity. Specifically, both prophylactic and therapeutic administration of IDO-Gal3 were effective in reducing vertical mandibular bone loss and loss of mandibular bone volume and bone thickness induced by chronic polymicrobial infection. The efficacy observed is at least in part due to localized regulation of innate immune mediators such as IL-1β, IL-6 and IL-8 as well as chemoattractants including IP-10, MCP-1 and MIP-1α, while enhancing the expression of immunoregulatory cytokines such as IL-10. In addition, IDO-Gal3 treatment suppressed the induction of pathogenic CD4+Th1, CD8+Tc1, CD4+Th1/Th17, and CD8+Tc1/Tc17, while promoting the induction of homeostatic CD4+Th17, CD8+Tc17 and CD4+Tregs. Importantly, the efficacy of prophylactically and therapeutically administered IDO-Gal-3 is not dependent on bacterial burden as there were no appreciable effects on bacterial burden following either method of administration. Lastly, therapeutic rather than prophylactic administration of IDO-Gal3 is most effective in preventing mandibular bone loss through more robust innate and adaptive immune modulation. Together these and our previously published data indicate that therapeutic administration of IDO-Gal3 addresses the clinical needs for adjunctive therapeutics to treat active and/or established periodontal diseases. ### Competing Interest Statement The authors have declared no competing interest.