Correlation of the expression of tumor necrosis factor-alpha in chronic periapical lesions with the expression of bacterial chaperonin 60

Background/Aim. Chronic microbial infections of the root canal are a common issue. This process very often causes an immune reaction in the root canal system that re-sults in forming of chronic periapical lesions (PLs). The aim of this study was to determine the quantitative expres-sion of the bacterial heat shock protein (HSP), chaperonin 60 (cpn60), and the pro-inflammatory and anti- inflammatory cytokines in periapical tissue obtained from individuals with chronic PLs and to determine if there is a correlation between the expression of the bacterial HSP and the expression of these cytokines.Methods. The study was performed on 18 PLs and 6 control samples of healthy periapical tissue, taken at the Department of Dentistry, Faculty of Medicine, University of Pristina/Kosovska Mi-trovica. The levels of messenger ribonucleic acid (mRNA) expression of pro- and anti-inflammatory cytokines and bacterial HSP were determined by quantitative real-time polymerase chain reaction (RT-PCR) and quantified by comparing to the internal control gene for glyceraldehyde 3-phosphate dehydrogenase (GAPDH).Results. Analysis revealed significantly higher mRNA levels of tumor necro-sis factor-alpha (TNF-a) and cpn60 in the tissue of PLs compared with normal periapical tissue (p < 0.05). Contra-ry to these results, the mRNA expression of anti- inflammatory interleukin-10 (IL-10) was significantly higher in the samples of normal periapical tissue compared with the mRNA levels of this cytokine in the tissue of PLs (p < 0.001). Expression of cpn60 is in strong correlation with TNF-a expression in PLs.Conclusion. cpn60 released from bacteria in periapical tissue could be a strong stimulator of inflammatory response and one of the important players in the pathogenesis of PLs.