Absent in Melanoma 2 (AIM2) Expressed in Human Dental Pulp Mediates IL-1β Secretion in Response to Cytoplasmic DNA

The inflammasome has been determined to play an important role in inflammatory diseases in recent years. Absent in melanoma 2 (AIM2), an inflammasome that recognizes cytoplasmic DNA, has recently been identified as a critical regulator of immune responses. In this study, we explored whether AIM2 was expressed in human dental pulp and defined the role of AIM2 in regulating interleukin (IL)-1β secretion. We demonstrated that AIM2 was only detected in the odontoblast layer of healthy dental pulp, whereas strong expression was observed in inflamed dental pulp. Stimulation with interferon gamma (IFN-γ) and cytoplasmic DNA significantly activated the AIM2 inflammasome and increased IL-1β secretion in human dental pulp cells (HDPCs) in a time- and dose-dependent manner. Moreover, the knockdown of AIM2 downregulated both cleaved-caspase-1 expression and IL-1β release in HDPCs. These results suggest that AIM2 expressed in human dental pulp plays an important role in the immune defense by activating the inflammasome signaling pathway.