Circulating Total and Active Metalloproteinase-9 and Tissue Inhibitor of Metalloproteinases-1 in Patients with Systemic Lupus Erythomatosus

We investigated the serum concentration of total metalloproteinase-9 (tMPP-9), active MMP-9 (aMMP-9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in a group of 41 patients with SLE and 20 healthy controls. Serum levels of tMMP-9 and TIMP-1 were assessed by an enzyme-linked immunosorbent assay (ELISA) and aMMP-9 by fluorometric assay. The tMMP-9 level was lower in SLE patients (mean 262 ng/mL) than in healthy volunteers (mean 325 ng/mL) (P = .048). Similarly, aMMP-9 level was lower in SLE patients (mean 121 ng/mL) than in control group (mean 169 ng/mL) (P = .0355) and lower in active SLE (mean 54 ng/mL) than in inactive disease (mean 99 ng/mL) (P = .033). TIMP-1 level was also lower in SLE patients (mean 181 ng/mL) than in control group (mean 233 ng/mL) (P = .004). In SLE patients, a positive correlation was found between tMMP-9 and aMMP-9 (ρ = 0.568; P = .001). We also found a positive correlation of tMMP-9 and TIMP-1 with VEGF concentrations (ρ = 0.450, P = .005 and ρ = 0.387; P = .018, resp). tMMP-9, aMMP-9, and TIMP-1 serum levels are lower in SLE patients than in healthy control group.