Conclusions
These data suggest that TGF-beta acts as a central mediator of acute lung injury through the alteration of several different molecular pathways.
Methods
cDNA microarray analyses were used to identify lung gene expression changes after nickel exposure. MAPPFinder analysis of the microarray data was used to determine significantly altered molecular pathways. TGF-beta1 protein in bronchoalveolar lavage fluid, as well as the effect of inhibition of TGF-beta, was assessed in nickel-exposed mice. The effect of TGF-beta on surfactant-associated protein B (Sftpb) promoter activity was measured in mouse lung epithelial cells. Measurements and main
Results
Genes that decreased the most after nickel exposure play important roles in lung fluid absorption or surfactant and phospholipid synthesis, and genes that increased the most were involved in TGF-beta signaling. MAPPFinder analysis further established TGF-beta signaling to be significantly altered. TGF-beta-inducible genes involved in the regulation of extracellular matrix function and fibrinolysis were significantly increased after nickel exposure, and TGF-beta1 protein was also increased in the lavage fluid. Pharmacologic inhibition of TGF-beta attenuated nickel-induced protein in bronchoalveolar lavage. In addition, treatment with TGF-beta1 dose-dependently repressed Sftpb promoter activity in vitro, and a novel TGF-beta-responsive region in the Sftpb promoter was identified. Conclusions: These data suggest that TGF-beta acts as a central mediator of acute lung injury through the alteration of several different molecular pathways.