MMP9 and systemic lupus erythematosus: In CNS lupus patients MMP-9 levels were significantly increased, both compared with cerebrally healthy SLE patients (240 ± 60 versus 100 ± 20 pg/ml; P < 0.05; Fig. 1) and compared with cerebrally healthy control individuals (240 ± 60 versus 0.28 ± 0.16 pg/ml; P = 0.0012).