TGF-β1 Induces Accumulation of Dendritic Cells in the Odontoblast Layer

TGF-β1 released from dentin degraded by bacterial or iatrogenic agents is suspected to influence dental pulp response, including the modulation of cell migration. To determine the consequences of TGF-β1 action on pulp immune cells, we analyzed, by immunohistochemistry, the effect of transdentinally diffusing TGF-β1 on their localization in a human tooth slice culture model. TGF-β1 induced an accumulation of HLA-DR-positive cells in both odontoblast and subodontoblast layers of the stimulated zone. Together with HLA-DR, these cells co-expressed Factor XIIIa and CD68, two features of immature antigen-presenting dendritic cells (DC), as well as the TGF-β1 specific receptor TβRII. In contrast, no effect could be detected on the localization of either mature DC-LAMP-positive DC or of T- and B-lymphocytes. Analysis of these data suggests that TGF-β1 released from dentin degraded by bacterial or iatrogenic agents could be involved in the immune response of the dental pulp resulting from tooth injury.