Fig. 2.

Induction of HO-1 by CDDO and 15d-PGJ₂ is peroxisome proliferator-activated receptor-γ (PPARγ) independent. A: primary human lung fibroblasts were pretreated with 5 μM GW9662 for 4 h or left untreated and were then treated with 1 μM CDDO for 24 h. HO-1 expression was determined by Western blot and evaluated by densitometry normalized to GAPDH. RE, relative expression of HO-1 normalized to GAPDH with untreated cells = 1. B: lung fibroblast cultures were infected with a lentiviral vector that coexpresses GFP and a dominant negative PPARγ (LV-PPARγ-DN) or the GFP-expressing vector only (LV-Empty). Twenty-four hours after infection, the media was changed, and CDDO (1 μM), 15d-PGJ₂ (5 μM), or rosiglitazone (20 μM) was added. After a further 24 h, the cells were harvested, and HO-1 expression was determined by Western blot. PPARγ overexpression is demonstrated in cells infected with LV-PPARγ-DN using an antibody to PPARγ (Abcam). Endogenous PPARγ expression is detected in cells infected with the control virus upon longer exposure. RE, relative expression of HO-1 normalized to GAPDH with untreated cells = 1. Results shown are representative of 2 independent experiments, each performed on duplicate wells.