The Expression of Interferon Regulatory Factor 8 in Human Periapical Lesions.

INTRODUCTION: Interferon regulatory factor 8 (IRF8) is a critical transcription factor in innate immune responses that regulates the development and function of myeloid cells. Human periapical lesions are caused by endodontic microbial infections. However, the presence of IRF8 in human periapical lesions remains elusive. This study aims to explore the expression of IRF8 in human periapical lesions and the possible association of IRF8 with macrophages, nuclear factor kappa B (NF-κB) signaling, and the autophagy process.

METHODS: Thirty-nine human periapical tissues, including healthy control tissues (n = 15), radicular cysts (RCs, n = 11), and periapical granulomas (PG, n = 13), were examined. Tissues were fixed in paraformaldehyde and analyzed. The inflammatory infiltrates of lesions were evaluated by hematoxylin-eosin, and the expression of IRF8 was analyzed by immunohistochemistry. Double immunofluorescence assessment was performed to colocalize IRF8 with CD68, NF-κB p65, and LC3B.

RESULTS: The expression of IRF8 was significantly higher in RCs and PGs than in the healthy control group, but no significant difference was found between RCs and PGs. There were significantly more IRF8-CD68 double-positive cells in RCs and PGs than in the healthy control group, but no significant difference was observed between RCs and PGs. Double-labeling analysis of IRF8 with NF-κB and LC3B indicated that IRF8 expression is associated with NF-κB signaling and the autophagy process during periapical lesions.

CONCLUSIONS: IRF8 could be observed and might possibly be involved in macrophages in the development of periapical lesions.