Fig. 5

MMP-2 and MMP-9 protein levels (a, b) and activities (c, d) in BALF and lung tissues. Mice were intratracheally instilled with 50 µg per mouse of Nano-Ni, or with either partially passivated (Nano-Ni–P) or carbon-coated (Nano-Ni–C) nickel nanoparticles with same molar concentration of Ni as Nano-Ni. Control mice were instilled with physiological saline. BALF and lung tissues were collected from mice at day 3 post-exposure. a, b MMP-2 and MMP-9 protein levels in the BALF determined by Mouse MMP-2 or MMP-9 PicoKine™ ELISA Kit. Data are shown as mean ± SE (n = 5). *p < 0.05 vs. Control; ^#p < 0.05 vs. Nano-Ni group. c, d Gelatinolytic activity of MMP-2 and MMP-9 in the BALF (c) and lung tissue homogenates (d) determined by gelatin zymography assay