Figure 9. Luteolin inhibits ROS production, but not the release of MMP-9 from IC-stimulated leukocytes.

(A) Leukocytes (3×10⁷/ml) were pre-incubated with luteolin in different concentrations or vehicle alone and stimulated with rabbit ICs consisting of 5 µg recombinant BP180/CXVII/well and 100 µl of 50-fold diluted rabbit serum. ROS production was measured over a period of 60 min. Data are represented as mean ± SD; p<0.05. (B) 3×10⁷/ml leukocytes were stimulated with rabbit ICs consisting of 5 µg recombinant BP180/CXVII/well and 100 µl of 50-fold diluted rabbit serum for 3 h at 37°C. MMP-9 activation was evaluated by zymography in 50-fold diluted supernatants of these cultures of cells stimulated with BP180/CXVII (lane 1), BP180/CXVII-specific rabbit IgG (lane 2), ICs (lane 3), ICs with 1000, 500 and 200 µg/ml Luteolin (lanes 4, 5, and 6 respectively). (C) Luteolin inhibits dermal-epidermal separation in cryosection assays ex vivo. Frozen murine skin sections were incubated with pre-immune rabbit serum or BP180/CXVII-specific rabbit serum. Significantly less dermal-epidermal separation was observed in sections treated with 500 µg/ml luteolin compared with those treated with vehicle alone (magnification, ×400).