CORRELATION OF GENE EXPRESSION OF MAIN INFLAMMATORY CITOKINS AND THE SEVERITY OF CHRONIC PERIODONTITIS

The understanding of the pathogenesis of periodontitis makes various progresses in the last decades. Today it is well known that the synthesis of high levels of pro-inflammatory mediators from gingival tissues in response to periodontal pathogens results in destruction of soft and hard periodontal tissues and clinical expression of periodontal disease. The occurrence of increased IL-6, IL-1β, TNFα and PGE2 levels in GCF or gingival tissue is capable to indicate risk of progression of destruction in specific periodontal site. Detection of gene expression of numerous major cytokines in high levels in gingival tissues and crevicular fluid may be indicator for activity of periodontitis and provides the rationale for the additional periodontal therapy. The current conception of the pathogenesis of periodontitis suggests that additional host modulation approach may inhibit the production of pro-inflammatory mediators in periodontal tissues and thus may enhance the treatment result.


INTRODUCTION:
The current conception of the pathogenesis of periodontal diseases suggests that periodontitis is an inflammatory disease of bacterial origin that results in the progressive destruction of the supportive periodontal tissues.Although bacteria are necessary for the initiation of periodontal disease, the immune-inflammatory response that develops in periodontal tissues in response to the presence of plaque bacteria is of high importance and results in destruction of periodontium and clinical signs of periodontitis [1 -8].There are literature data for a higher level of gene expression of the major pro-inflammatory cytokines at higher severity of chronic periodontitis and current progression of destruction [2, 4, 5, 9 -13].Therefore, the current literature focuses on producing as a result of the local inflammatory response cytokines such as part of an imbalance between macro-organism and pathogenic bacteria from the dental biofilm [8, 10, 11, 14 -18].As a result of bacterial infection different host cells such as keratinocytes, endothelial cells, fibroblasts, macrophages, and other express multiple cytokines such as interleukin 1-alpha, interleukin 1beta, interleukin-6 and tumor necrosis factor-alpha.During inflammation gingival fibroblasts are stimulated by cyto-kines released to synthesize cytokines themselves, and also MMPs (matrix metalloproteinases), and PGE2 (prostaglandin E2) that additionally cause tissue damage and stimulate bone resorption.[19,20].

Aim:
Evaluation of the gene expression of IL-6, IL-1β and TNF-α as well as PGE2 in the gingival tissues in relation with severity of chronic periodontitis.

MATERIALS AND METHODS:
Two groups of patients with chronic periodontitis were enrolled in this study -20 patients examined for gene expression of IL-1β and PGE2 and 20 patient tested for gene expression of IL-6 and TNF-α.The patient gingival tissue was investigated using TaqMan Real-Time PCR (Progene lab.).The gingival samples were taken from sites in contact to deep periodontal pockets.

RESULTS:
Significant differences were established according to the gene expression of IL-6 and TNF in relation with deeper periodontal pockets and severe attachment loss (P < 0.05) in patients with chronic periodontitis.The similar results are obtained for IL-1β and PGE2.[Table 1. and Table 2.] Significant differences were established according to the gene expression (marked as dCt) of IL-6 between samples taken from the gingiva in conjunction of pockets ≤ 4 mm and periodontal pockets with depth > 6 mm), as well as of TNFα in two deeper probing depths (4 -6 mm / > 6 mm).[Fig.1. and Fig. 2.] As regards to severity of disease gene expression of TNF (dCt 4-6 mm) shows significant differences.In patients with a higher severity of disease dCt increased (i.e.lower gene expression).[Fig.3] Changes in gene expression of IL-1β and PGE2 demonstrated in Fig. 4 and Fig. 5. show a reduction of the gene expression of the major cytokines associated with periodontitis with healing as a result of elimination of inflammation and a reduction of the pockets.

CONCLUSION:
The results of this study suggest for existing correlation of chronic periodontitis severity and the gene expression of main factors associated with destructive host response http://dx.doi.org/10.5272/jimab.2014203.563Journal of IMAB ISSN: 1312-773X http://www.journal-imab-bg.org

Fig. 4 and
Fig. 4 and Fig. 5. Changes in IL-1β and PGE2 levels in patients with Aulin® therapy added to periodontal treatment.

Table 2 .
Comparison of gene expressions relative to the disease severity.

Table 1 .
Comparative analysis of gene expression in samples taken from different depths, expressed as dCt (Ct (gene -Ct (reference gene -ACTB))) of IL6 and TNF.