Identifying Collagenase (MMP-1, -8, -13) Expression and Correlation with Periodontitis Progression Using the Rat Model

Collagenase (MMP-1, -8, and -13) is one of the groups of the matrix metalloproteinases (MMPs) that is responsible for the breakdown of collagen, particularly type-I collagen, which is found in profusion in the extracellular matrix (ECM). It is essential to understand the role of a group of biomarkers in the progression of periodontal disease. This study aims to evaluate the expression of MMP-1, -8, and -13 combined in the periodontitis progression induced by wire ligation and Enterococcus faecalis inoculation using the rat model. Twelve rats were allocated uniformly between the control group 0-day, experimental group 7- and 14-days. Orthodontic wire (0.2 mm) was placed between the proximal space of the right upper first and second molar tooth area and 0.5 μl of 1.5 ´ 108 cfu/ml. Rats in the experimental groups received an injection of E. faecalis suspension into their gingival sulcus. After the respective induction time, the rats were euthanised. Gingival tissue and maxillary jaw samples were obtained from all rats for quantitative real-time PCR and histological examination. The results showed a significant increase in mRNA expression within the tissue samples from the gingiva of MMP-1 (p < 0.05), -8 (p < 0.01), and -13 (p < 0.01) in 7 days as compared to the control. The MMP-8 expression levels were also significantly reduced (p < 0.05). Histological analysis showed a higher inflammatory cell infiltration and the presence of osteoclast in the 7 days, which was reduced in the 14 days. MMP-1, -8, and -13 levels were positively correlated with the presence of inflammatory cells. Therefore, identifying a group of collagenases might be a useful biomarker to detect the progression of periodontitis.