Salivary levels of matrix metalloproteinase (MMP)-9 and tissue inhibitor of matrix metalloproteinase (TIMP)-1: A pilot study about the relationship with periodontal status and MMP-9−1562C/T gene promoter polymorphism

ObjectiveChronic periodontitis (CP) has been linked with an imbalance in the MMP-9/TIMP-1 ratio. A reasonable biologic explanation for this link is that the MMP-9 transcriptional activity can be modulated by MMP-9−1562C/T gene promoter polymorphism contributing to periodontal breakdown. This study aimed to assess the relationship between salivary MMP-9/TIMP-1 balance, MMP-9−1562C/T genotype and periodontal clinical status.DesignSixty-nine CP subjects and 54 healthy controls (HC) were selected. Periodontal status was assessed by criteria based on probing depth, clinical attachment level, extent, and severity of periodontal breakdown. Salivary levels of MMP-9 and TIMP-1 were analysed using ELISA and MMP-9−1562C/T genotype using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The association between salivary levels of MMP-9, TIMP-1 and MMP-9/TIMP-1 ratio with CP was assessed individually and adjusted for confounding using a binary logistic regression model.ResultsSignificantly higher levels of both markers and their ratios were detected in the CP group in comparison to healthy controls. Synchronously, weak-to-moderate positive significant correlations between salivary biomarkers and clinical parameters were observed. After binary logistic regression analysis, salivary levels of MMP-9 > 20 ng mL−1, TIMP-1 > 64 ng mL−1 as well as MMP-9/TIMP-1 ratio >1 were independently associated with CP. Nevertheless, the MMP-9−1562C/T gene promoter polymorphism was not associated with the different degrees of chronic periodontitis and did not have influence on the salivary levels of biomarkers.ConclusionThe findings when considered within the limitations of this study may indicate that although a dominant expression of MMP-9 over TIMP-1 in saliva might reflect the periodontal clinical status, the functional polymorphisms in the promoter of the MMP-9−1562C/T gene from the Colombian population are not linked neither with significant salivary MMP-9 variations in these individuals nor periodontal clinical status.