The Immunoexpression And Clinical Significance Of Interleukin-21 And Receptor Activator Of Nuclear Factor κB Ligand In Human Periapical Granulomas And Radicular Cysts

Objective IL-21 has been defined as a key cytokine in regulation of innate and adaptive immunity; also has a role in osteoclastogenesis. This study aims to detect the expression of interleukin(IL-)-21 and RANKL in Radicular Cysts(RCs) and Periapical Granulomas(PGs) and evaluate the association of this cytokine with receptor activator of nuclear factor κB ligand(RANKL), also clinical and radiographic findings; investigate the relationship among them in periapical disease, speculate the role of IL-21 in periapical pathogenesis.Methods 55 human apical periodontitis lesions were consecutively obtained in Department of pathology after periapical surgery and tooth extraction in Oral and Maxillofacial Surgery of Anhui Medical University Affiliated Stomatological Hospital from December 2013 to June 2014. The histopathological nature of the specimens was determined after hematoxylin and eosin staining. Thirty-two periapical granulomas and 23 radicular cysts were selected as the experimental samples;also record lesions size and the occurrence of tenderness. 10 Healthy gingival tissues fromed patients who were referred to the Department of Oral Surgery for the extraction of impacted wisdom teeth were collected as normal control sample. We performed immunohistochemical staining to investigate the expression of IL-21 and RANKL in all the samples and subsequently analyzed by Image Pro Plus 6.0.Results IL-21- and RANKL-positive cells were detected in all periapical lesion tissues, but didn’t detect in normal tissues. In cyst group and granuloma group,the expression of IL-21 were 59.92±6.57 and 36.80±6.81;the expression of RANKL were 68.81±18.59 and 36.12±14.87. The t test disclosed a statistically significant higher expression of IL-21 and RANKL in RCs when compared to PGs(P <.001,P<.001). Spearman’s correlation analysis showed that IL-21 and RANKL were both positively correlated in cysts group and granulomas group; also closely related to lesions size(P<0.05). But no association of IL-21 expression with tenderness(P=0.14)was observed.Conclusions 1.Through immunohistochemical methods, it demonstrated that IL-21-positive cells existed in all periapical lesions,but did not detect in normal samples, indicating that IL-21 may participate in the progression of periapical lesions. 2. IL-21 and RANKL were both positively correlated in cysts group and granulomas group; also closely related to lesions size. A role in the exacerbation of chronic inflammation and bone resorption by inducing RANKL proteins is suspected.