Matrix metalloproteinase 9 as a marker of disease activity in multiple sclerosis

Matrix metalloproteinase 9 (MMP9) levels in serum and cerebrospinal fluid (CSF) are known to be elevated in patients with multiple sclerosis; these patients also have lower than normal levels of tissue inhibitor of metalloproteinase 1 (TIMP1), an inhibitor of MMP9. The MMP9:TIMP1 ratio has been proposed as a biomarker of multiple sclerosis activity. Fainardi et al. measured MMP9 activity and TIMP1 levels in 61 consecutive patients with multiple sclerosis; patients with other neurological disorders acted as controls. The results suggest that high CSF levels of active MMP9 are selectively associated with multiple sclerosis, while high serum MMP9 is also found in other inflammatory neuro logical disorders. CSF and serum ratios of active MMP9 to TIMP1 are an important indicator of disease activity, with high CSF levels of active MMP9 associated with more-severe disease