The serum concentration of TIMP-1, an inhibitor of MMP-9, was also higher in SSc patients than in healthy controls (157.1 ± 13.2 ng/ml versus 77.7 ± 12.5 ng/ml, P < 0.001), but SSc patients had higher MMP-9/TIMP-1 ratios than healthy controls (233.0 ± 27.1 versus 69.5 ± 24.3, P < 0.001). Here, MMP9 is linked to systemic sclerosis.