Characterizing The Role Of Macrophage Polarization In Non-Surgical Periodontal Therapy in Humans

Periodontal pathogens alter the host immune response by perturbing expression of pro- and anti-inflammatory milieu. Inflammatory microenvironment in periodontal disease is largely governed by infiltration of myeloid cells. Periodontal therapy results in reduction of bacterial load that may instigate a pro-resolution environment favoring M2 Mφ polarization. Our previous studies demonstrated that human macrophages (Mφ) respond to live periopathogens, P. gingivalis (Pg) or A. actinomycetecomitans (Aa) and their LPS by polarizing towards the pro-inflammatory M1 phenotype. While studies have evaluated differences in M1 and M2 Mφ profiles or their markers in healthy versus periodontally diseased gingival tissues, to our knowledge there has been no longitudinal study evaluating the influence of periodontal therapy on Mφ polarization. In this study, we correlated clinical parameters and periopathogen load in human gingival biopsies after non-surgical periodontal therapy. Using well characterized markers for M1, M2 Mφ polarization, we found a decrease in the levels of M1 Mφ markers and the converse increase in M2 Mφ polarization markers in gingival biopsy samples obtained post-therapeutically which correlated with clinical improvement. Priming of Mφ within the gingival tissues is a well controlled axis and has considerable consequences for how Mφ detect, phagocytose and kill bacteria, and participate in tissue repair.