Receptor activator NFkappaB-ligand and osteoprotegerin protein expression in human periapical cysts and granulomas.
OBJECTIVE
The purpose of this study was to determine the expression of receptor activator of NFkappaB ligand (RANKL) and osteoprotegerin (OPG) associated with bone destruction in periapical cysts and granulomas.


METHODS
Forty human dental chronic periapical lesions were collected after periapical surgery. The lesions collected were fixed in 10% buffered formalin and histologically processed. At least 2 sections of each specimen were stained with hematoxylin and eosin for microscopic diagnosis. After that, 10 human periapical granulomas and 10 cysts were selected for immunohistochemical analysis for RANKL, OPG, and CD68+.


RESULTS
Polymorphonuclear neutrophils, macrophages, endothelial cells, and lymphocytes were stained for RANKL and OPG in both lesions. Epithelial cells were also stained for RANKL and OPG in periapical cysts. Quantitative analysis was conducted and the results were expressed as a ratio of the number of immunostained cells over the total number of cells in the field (n = 100). The ratio of RANKL+/total cells was higher than OPG+/total cells in periapical granulomas (0.553 +/- 0.153 and 0.483 +/- 0.189, respectively; P < .0012; paired t test) and in cysts (0.519 +/- 0.09 and 0.339 +/- 0.117, respectively; P < .0001; paired t test). The ratios of OPG+/total cells (P < .0001; paired t test) and RANKL+/total cells (P < .0322; paired t test) were greater in granulomas than in cysts. However, the ratio RANKL+/OPG+ in granulomas (1.336 +/- 0.723) and cysts (1.404 +/- 0.385) was not significantly different. The ratio of CD68+/total cells was significantly higher in granulomas (0.381 +/- 0.040) than in cysts (0.307 +/- 0.068) (P < .0001; unpaired t test with Welch correction).


CONCLUSIONS
Taking into account the limitations of the experimental approach employed, our findings indicate the presence of RANKL and OPG in cysts and granulomas, strongly suggesting the involvement of these gene products in the development of periapical lesions.
Menezes
Renato
R
Department of Endodontics, Bauru Dental School, University of São Paulo, Bauru, Brazil.
Bramante
Clóvis Monteiro
CM
da Silva Paiva
Katiúcia Batista
KB
Letra
Ariadne
A
Carneiro
Everdan
E
Fernando Zambuzzi
Willian
W
Granjeiro
José Mauro
JM
D000293:Adolescent; D000328:Adult; D016301:Alveolar Bone Loss / Q000378:metabolism; D015703:Antigens, CD / Q000096:biosynthesis; D015214:Antigens, Differentiation, Myelomonocytic / Q000096:biosynthesis; D002352:Carrier Proteins / Q000096:biosynthesis*; D004847:Epithelial Cells / Q000378:metabolism; D006023:Glycoproteins / Q000096:biosynthesis*; D006801:Humans; D007124:Immunoenzyme Techniques; D008264:Macrophages / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D008875:Middle Aged; D053244:Osteoprotegerin; D010484:Periapical Granuloma / Q000378:metabolism*; D053245:RANK Ligand; D011842:Radicular Cyst / Q000378:metabolism*; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis*; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis*; D000097382:CD68 Molecule
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D002352:Carrier Proteins; D006023:Glycoproteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C067980:CD68 antigen, human; D000097382:CD68 Molecule; C505686:TNFRSF11A protein, human; C506030:TNFRSF11B protein, human; C505688:TNFSF11 protein, human