Characterization Of Dendritic Cell Subpopulations In Human Gingiva

Objectives: Periodontitis is a chronic multi-factorial infectious disease. Although bacterial plaque is considered to be the main etiologic factor, it is thought that periodontal destruction is caused by an excessive immune response developed against periodontal bacteria. Dendritic cells have an important role in orchestrating the immune response following infection. Recently, it has been shown in mice that Langerhans cells (LCs) play a protective role during periodontitis, while activation of plasmacytoid DCs (pDCs) results in the activation of pro-inflammatory pathways. Although the heterogeneity of murine DC populations in the gingiva has been well documented, little is known about these subpopulations in the human gingiva. The aim of our study is to charachterize the DC subpopulations in the human gingiva in periodontal patients and healthy subjects.
Methods: Gingival samples were collected from chronic periodontitis patients and healthy subjects at the Department of Periodontology and the Department of Oral Maxillofacial Surgery, Hadassah Ein-Karem. The samples were processed and stained with specific antibodies for the different subpopulations of gingival DCs and analyzed using flow cytometry. The different cytokines that are related to the different DC subpopulations were also analyzed using real-time PCR.
Results: We established a novel strategy to identify the different subpopulations of gingival DCs and the prevalence of five different DC subpopulations were compared between the study groups. The prevalence of LCs was significantly decreased in patients with chronic periodontitis, while the prevalence of pDCs was significantly increased. We also showed that smoking reduces the prevalence of LCs in the gingival tissues. Upon studying different cytokines, inflammatory cytokines related to DCs such as IL-1β, INF-α, and RANKL were elevated in patients with chronic periodontitis, whilst anti-inflammatory cytokines such as IL-10 and OPG were reduced.
Conclusions: Our study establishes a new method to characterize human gingival DCs. By analyzing the prevalence of each DC subpopulation together with cytokines levels in patients with chronic periodontitis compared to healthy subjects we spot the light on the possible role of each subpopulation in the process of inflammation and hence the pathogenesis of periodontitis.