Mucin 4 and matrix metalloproteinase 7 as novel salivary biomarkers for periodontitis

Abstract

Aim: Periodontitis is a chronic inflammatory disease, characterized by irreversible destruction of tooth-supporting tissue including alveolar bone. We recently reported mucin 4 (MUC4) and matrix metalloproteinase 7 (MMP7) as highly associated with periodontitis in gingival tissue biopsies. The aim of this study was to further investigate the levels of MUC4 and MMP7 in saliva and gingival crevicular fluid (GCF) samples of patients with periodontitis.

Materials and methods: Saliva and GCF samples were collected from periodontitis patients and healthy controls. The levels of MUC4, MMP7, and total protein concentrations were analysed using ELISA or Bradford assay.

Results: MUC4 levels were significantly lower in saliva and GCF from periodontitis patients relative to healthy controls. MMP7 levels were significantly higher in saliva and GCF from periodontitis patients. Multivariate analysis revealed that MUC4 was significantly associated with periodontitis after adjusting for age and smoking habits and, moreover, that the combination of MUC4 and MMP7 accurately discriminated periodontitis from healthy controls.

Conclusions: MUC4 and MMP7 may be utilized as possible novel biomarkers for periodontitis.

Keywords: gingival crevicular fluid; matrix metalloproteinase 7; mucin 4; periodontitis; saliva.

Figure 1

Salivary levels of mucin 4 (MUC4) and matrix metalloproteinase 7 (MMP7). Boxplots demonstrating the concentrations of (a) MUC4 (ng/ml), (b) MUC4/total protein concentrations (ng/mg), (c) MMP7 (ng/ml), and (d) MMP7/total protein concentrations (ng/mg) in saliva samples from periodontitis patients and healthy controls. *p < 0.05, **p < 0.01.

Figure 2

Levels of matrix metalloproteinase 8 (MMP8) in saliva samples. Boxplots demonstrating the concentrations of (a) MMP8 (ng/ml), and (b) MMP8/total protein concentrations (ng/mg) in saliva samples from patients with periodontitis and healthy controls. **p < 0.01.

Figure 3

Diagnostic power of mucin 4 (MUC4) and matrix metalloproteinase 7 (MMP7) by receiver operating characteristic curve (ROC curve). The ROC curve is based on a binary logistic regression model with periodontitis as dependent variable and MUC4/MMP7 levels related to the total protein concentrations, age, and smoking habits as independent variables.

Figure 4

Mucin 4 (MUC4) and matrix metalloproteinase 7 (MMP7) levels in gingival crevicular fluid (GCF) samples. Boxplots demonstrating the concentrations of (a) MUC4 (ng/ml), (b) MUC4/total protein concentrations (ng/mg), (c) MMP7 (ng/ml), and (d) MMP7/total protein concentrations (ng/mg) in GCF samples from periodontitis patients and healthy controls. *p < 0.05, **p < 0.01.