Effects of Amelogenin on Antigen Presentation by Macrophages

Objectives: Amelogenin is a major protein in enamel matrix derivative used commonly for periodontal tissue regenerative treatment. We have previously shown that amelogenin temporarily up-regulates inflammatory responses before polarizing macrophages toward M2 phenotype and could contribute to the early resolution of inflammation in periodontal tissue. However, effects of amelogenin on antigen presentation are still unclear. The ability of antigen presentation is one of the originally function in macrophages and important for the resolution of inflammation. Our objective is to investigate effects of amelogenin on antigen presentation and its mechanisms.
Methods: We used human acute monocytic leukemia (THP-1). The cells were differentiated to macrophages and then stimulated by amelogenin(10 μg/ml) for 24 hours. To examine the expressions of surface molecules on macrophages, we used flow cytometry (FACS verse). Antibodies were HLA-ABC, HLA-DR, CD80 and CD86. The ability of phagocytosis was assessed using Phagocytosis Assay Kit IgG FITC.
Results: CD80 expression was higher in macrophages stimulated by amelogenin. However, there is no difference between other markers (HLA-ABC, HLA-DR andCD86). Moreover, amelogenin did not affect the phagocytosis ability in macrophages.
Conclusions: We demonstrated that amelogenin increases the expression of CD80 which is crucial for antigen presentation and T cell activation. In this study, we deduced that amelogenin temporarily up-regulates the expression of CD80 in macrophages, which leads to the early resolution of inflammation in periodontal tissue through the interaction between macrophages and T cells. It is a just first step of our study to have shown effects of amelogenin on antigen presentation by macrophages. Further detailed analysis of mechanisms by amelogenin is needed in the future. Therefore, our data might lead to novel findings for periodontal tissue regeneration.