MMPs, TIMPs and BMP-4 in medial rectus muscle obtained from intermittent exotropia patients and their clinical correlations

Abstract

Background: To measure the amounts of matrix metalloproteinase (MMP)-2, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1, TIMP-2 and bone morphogenetic protein (BMP)-4 in medial rectus muscle (MR) tissue obtained from intermittent exotropia (IXT) patients and to investigate the correlation between each protein amount and the clinical features of IXT including angles of deviation, age at surgery, duration of IXT and postoperative recurrence. Methods: The protein amounts were measured by enzyme-linked immunosorbent assay (ELISA) in MR collected during surgery for 78 IXT patients. Results: The mean amount of MMP-2 per mm of resected MR was 0.86 ng, of MMP-9, 2.72 ng, of TIMP-1, 1.99 ng, of TIMP-2, 0.92 ng and of BMP-4, 0.82 pg. MMP-2 showed a positive correlation with angle of deviation at distance and at near, age at surgery and duration of IXT (p = 0.000, p = 0.000, p = 0.000, p = 0.022, respectively, Spearman's rank correlation analysis). MMP-9 showed a positive correlation with angle of deviation at distance and at near (p = 0.001, p = 0.024) and BMP-4 showed a positive correlation with angle of deviation at distance (p = 0.012). TIMP-1 showed a negative correlation with angle of deviation at distance and at near (p = 0.003, p = 0.000). Conclusion: In IXT patients, MMPs and BMP-4 tended to increase and TIMPs to decrease with increasing angle of deviation, greater age at surgery and longer duration of IXT.