Fig. 7

Effects of antioxidants on the induction of matrix metalloproteinase (MMP) mRNA levels. Beas2B (a–h) and SAE (i and j) cells were incubated first with medium (C), 15 mM n-acetylcysteine (NAC) adjusted to pH 7.0 for 3 h, or dimethylthiourea (DMTU) (30 mM) for 1 h and then treated with or without dust extract (0.25 %) (DE) for 3 h. Levels of MMP mRNAs were determined by qRT-PCR. Data shown are means ± SE (n = 3 for NAC and N = 3 for DMTU). Levels of each mRNA in control cells were arbitrarily considered as 100, and relative levels in treated cells are shown. *P < 0.05; **P < 0.01