Pulmonary Biomarkers Based on Alterations in Protein Expression Following Exposure to Arsenic

Environmental exposure to arsenic (As) results in multiple adverse effects in the lung. Our objective is to identify potential pulmonary protein biomarkers in the lung lining fluid of mice chronically exposed to low dose arsenic and to validate these protein changes in human populations exposed to arsenic. Mice were administered 10 or 50 ppb of arsenic (sodium arsenite) in their drinking water for 4 weeks. Proteins in the lung lining fluid were identified using 2-D gel electrophoresis (N=3) or multidimensional protein identification technology (MUDPIT) (N=2) coupled with mass spectrometry (MS). Lung induced-sputum samples were collected from 57 individuals (tap water As ranged from ~5 ppb to 20 ppb). Protein levels in sputum were determined by ELISA and arsenic species were analyzed in first morning void urine. Proteins whose expression in mouse lung lining fluid was consistently altered by arsenic included: glutathione-S-transferase omega-1, contraspin, apolipoprotein A-I and A-IV, enolase-1, peroxiredoxin-6 and receptor for advanced glycation end products (RAGE). Validation of the putative biomarkers was carried out by evaluating arsenic-induced alterations in RAGE in humans. Regression analysis demonstrated a significant negative correlation (p=0.016) between sputum levels of RAGE and total urinary inorganic arsenic, similar to results seen in our animal model. We conclude that combinations of proteomic analyses of animal models followed by specific analysis of human samples provide an unbiased determination of important, previously unidentified putative biomarkers that may be related to human disease. This research was funded in part by NIH grants P30ES006694 and P42ES004940 and by USEPA grant R832095.