OBJECTIVETo investigate the role of NADPH oxidase (Nox) in the oxidative stress injury of human dermal fibroblasts (HFbs).

METHODSAn oxidative stress injury model was established in HFbs by exposure to H(2)O(2). Normal HFbs and HFbs exposed to H(2)O(2) with and without pretreatment with NADPH oxidase inhibitor were tested for cell viability using MTT assay, and the intracellular reactive oxygen species (ROS) were determined with a DCFH-DA fluorescent probe. Western blotting was used to measure the protein expressions of membrane-bound subunit gp91phox of NADPH oxidase in the cells.

RESULTH(2)O(2) time- and concentration-dependently induced oxidative stress injury in the fibroblasts, causing a reduction of the cell viability to 40% after a 24-h exposure at 700 µmol/L (P<0.05) and an increase of ROS by 2 folds after a 2-h exposure at 700 µmol/L (P<0.05). Compared with the cells with oxidative stress injury, the cells with NADPH oxidase inhibitor pretreatment showed a 20% higher cell viability (P<0.05) and normal ROS level (P<0.05) following H(2)O(2) exposure. Western blotting demonstrated increased expression of gp91phox in the cells exposed to increasing H(2)O(2) concentrations, but gp91phox expression remained normal in cells pretreated with NADPH oxidase inhibitor.

CONCLUSIONH(2)O(2) can induce oxidative stress injury in the fibroblasts by affecting NADPH oxidase, especially its membrane-bound subunit gp91phox.