Effect of Inflammation on Expression of Ki67, BCL-2 in odontogenic Kertocyst

Odontogenic keratocyst is a developmental odontogenic cyst. However, inflammation has been reported in the connective tissue layer of this cyst. On the other hand, Ki67 is a proliferation marker while, BCL-2 protein is an anti-apoptotic marker. The aim of this study was to evaluate the effect of inflammation on expression of ki67 and BCL-2 in odontogenic keratocyst. This retrospective descriptive analytic study was conducted with 20 cases of OKC. Specimens were divided into two groups of inflamed (n=10) and none-inflamed OKC. Two sections of 3µm, and 5µm were dissected from each specimen. This step was followed by Hematoxylin and Eosin staining first and then immunohistochemistry staining was performed using monoclonal antibody for Ki67 and BCL-2. Number of nucleus and cytoplasm of immunostained epithelial cells with Ki67 and BCL-2 in 1000 serial epithelial cells were considered as the labeling index (LI). Inflammatory infiltration density was recorded for each HPF by looking at the depth of adjacent basement membrane. The average inflammatory score and average labeling index were calculated for further comparison. Data was evaluated using Roc curve and student T-test analysis. The mean Ki67 labeling index in all linings of inflamed and non-inflamed OKC was (19.8 ± 0.88%), (17.9 ± 1.03%) respectively. The mean BCL-2 labeling index in all linings of inflamed and non-inflamed OKC was (36.06 ± 1.09%), (37.2 ± 0.75%) respectively. The Ki67 and BCL-2 labeling index demonstrated significant differences between inflamed and non-inflamed OKC (P<0.05). The HPF in inflamed cyst, showed an increase in Ki67 expression and decrease in BCL-2 expression when compared with non-inflamed HPF (P<0.001). Moderate and severe inflammation can affect the overall proliferation activity of OKC epithelium. An increase in Ki67 expression and decrease in BCL-2 expression can be observed in inflamed OKC especially adjacent to basement membrane.