Detection of RANKL and OPG in chronic periradicular periodontitis

This study examined the cellular sources of RANKL in mononuclear cells infiltrating the lesion of periradicular periodontitis, including B and T lympho- cytes and monocytes. Also, mRNA expression of RANKL and OPG was compared between periradicular tissues of patients with chronic periradicular periodontitis and normal healthy periradicular tissues sampled from extracted wisdom teeth. Immunofluorescent confocal microscopy analysis shows that T and B lymphocytes, as well as monocytes, express RANKL. Results from quantitative RT-PCR indi- cated that the expression ratio of RANKL mRNA over that of OPG mRNA was a more critical determinant of disease pathogenesis than the titers of either RANKL mRNA or OPG mRNA detected in the sampled tissues, strongly suggesting that the balance between RANKL and OPG is pertinent in periradicular bone pathology. In conclusion, RANKL is expressed by lymphocytes as well as monocytes and the balance of RANKL/OPG expression could also be a determinant of pathogenic bone resorption in chronic periradicular periodontitis.