HO-1 and VEGF gene expressions are time dependant during exposure to welding fumes

Hemeoxygenase-1 (HO-1) is a defensive enzyme against oxidative stress. Vascular epithelial growth factor (VEGF) is a potent cytokine which promotes angiogenesis. We used induced sputum (IS) technology to study HO-1 and VEGF expressions in neutrophilic inflammation in asymptomatic welders. Aircraft plant employees were divided into three groups: Welders 1 (n=30) had short-term exposure to aluminum/iron, Welders 2 (n=16) had long-term exposure to cadmium/chromium/iron/nickel, and controls (n=27 non-exposed individuals). Participants underwent pulmonary function tests (PFTs), IS, differential cell counts, and determination of particle size distribution in IS samples. HO-1 and VEGF gene expressions were analyzed by real-time polymerase chain reaction, and protein levels were measured by bilirubin reductase-dependant reaction and ELISA, respectively. All subjects had normal PFTs. Welders 2 had neutrophilic inflammation and higher percentages of particles between 2-5 micron than the other groups. HO-1 inversely correlated with VEGF gene expression: HO-1 was significantly higher and VEGF was significantly lower in the Welders 1 group than in the other groups. There was a correlation between HO-1 expression and protein activity (r=0.33, P=0.05). Particulate matters significantly influenced HO-1 and VEGF gene expressions, caused neutrophilic inflammation and promoted oxidative stress in welders with long-term exposure.