Levels of Selected Matrix Metalloproteinases, Their Inhibitors in Saliva, and Oral Status in Juvenile Idiopathic Arthritis Patients vs. Healthy Controls

Matrix metalloproteinases (MMPs) are a group of calcium-dependent zinc-containing proteinases acting both physiologically and in pathological conditions. The aim of this study was to evaluate the concentration of MMP-2, MMP-8, and MMP-9 and their inhibitors TIMP-1 and TIMP-2 of unstimulated whole saliva (UWS) in correlation with the oral health in juvenile idiopathic arthritis (JIA) children.

Despite a comparable clinical oral status of affected and unaffected children, in the JIA patients, a statistically significantly increased level of MMP-9 was found. In reference to the periodontal status, the role of MMPs increased in children with permanent dentition, whereas in reference to dental caries, the period of mixed dentition (MD) was critical.

The study population comprised 34 JIA patients and 34 age- and sex-matched controls (C). They were divided into two groups: with mixed dentition (MD) and with permanent dentition (PD). Dental caries (DMFT/dmft), unstimulated salivary flow rate (SF), and gingival inflammation (Gingival Index (GI) and Papilla Bleeding Index (PBI)) and oral hygiene (Simplified Oral Hygiene Index (OHI-S)) indices were evaluated. Saliva samples were tested with the enzyme-linked immunosorbent assay (ELISA) for MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2. Data were statistically analysed with the Mann-Whitney U test and Spearman's rank correlation (p < 0.05).

There were no differences in dental hygiene or dental and periodontal status between the JIA and C groups. The MMP-9 concentration was higher in the whole JIA group compared with C (p=0.005) and JIA MD groups (p=0.038). A positive correlation of MMP-2 with the OHI-S index and a negative correlation of MMP-2 with SF were found in JIA. MMP-9 and its tissue inhibitor TIMP-1 had a positive mean correlation with the GI. A high correlation of MMP-8 with the number of decayed teeth (D) in JIA MD patients (p=0.037) was revealed. In the JIA-PD patients, there was a positive correlation of MMP-2, -8, and -9 levels with gingival inflammation indices and a negative correlation of MMP-2 and 8 with the SF. Conclusions: Despite a comparable clinical oral status of affected and unaffected children, in the JIA patients, a statistically significantly increased level of MMP-9 was found. In reference to the periodontal status, the role of MMPs increased in children with permanent dentition, whereas in reference to dental caries, the period of mixed dentition (MD) was critical.