Increase in the ratio of matrix metalloproteinase-9 to tissue inhibitor of metalloproteinase-1 in saliva from patients with primary Sjögren's syndrome.

Background: To investigate the ratio of matrix metalloproteinase (MMP) to tissue inhibitor of metalloproteinase (TIMP) in primary Sjögren's syndrome (PSS), patients and healthy subjects MMP-2, 9 and TIMP-1, 2 levels were measured in saliva.

Methods: Stimulated whole-mixed saliva was collected from 32 patients and 26 healthy subjects. MMP-2, 9 and TIMP-1, 2 levels were measured using enzyme-linked immunosorbent assay (ELISA) and the sandwich enzyme immunoassay (sandwich EIA). Zymography and reverse zymography were used to identify MMPs and TIMPs.

Results: MMP-9 (gelatinase-B) level in saliva was significantly increased in the patients. MMP-9 (ng/ml): patients 231.02 +/- 151.77 (mean +/- S.D.), healthy subjects 145.87 +/- 111.65 (p < 0.05). MMP-2 levels were not detected with this system kit in either healthy subjects or patients. The differences in TIMPs were only trends and not statistically significant (p > 0.05). Accordingly, MMP-9/TIMP-1 was greatly increased in the patients (2.60 +/- 1.18) than in the healthy subjects (1.28 +/- 1.11) (p < 0.01).

Conclusion: This study found that MMP-9/TIMP-1 and MMP-9 levels in the saliva were significantly higher in pSS patients than those in healthy subjects. Our results indicate that the increase in MMP-9/TIMP-1, rather than the increase in MMP-9, in pSS patients' saliva is strongly involved in destruction of glandular and salivary duct tissues.