Perturbation of Metabolic Pathways Associated with Exposure of Human Renal Proximal Tubular Cells to Nephrotoxic Pollutants and Drugs.

Mammalian kidneys, although exposed to a diverse array of environmental pollutants and commonly used drugs that are dose-limited by nephrotoxicity, have a significant but limited capacity for repair and regeneration. Primary cultures of human proximal tubular (hPT) cells were used to investigate the cellular response to exposures to one of two environmental toxicants (mercuric chloride [HgCl2] or S-(1,2-dichlorovinyl)-L-cysteine [DCVC; key metabolite of trichloroethylene] or one of three nephrotoxic drugs (cisplatin [CDDP], polymyxin B [PmxB], tenofovir disoproxil fumarate [TDF]) at concentrations that cause no to modest cellular injury. Cellular phenotype was first characterized by measuring protein expression of key drug metabolism enzymes and plasma membrane transporters. To enable identification of biomarkers when the hPT cells are still capable of repair and regeneration, release of Kidney Injury Molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) from exposed hPT cells was determined. Results validated that for each of the 3 concentrations of the 5 toxicants or drugs tested at the 3 time points, there was either no significant pattern of or modest cellular injury. Untargeted metabolomics was conducted to identify high resolution mass spectrometry features representing metabolites that differ after exposures. Pathway analysis was then conducted to map these metabolites into altered pathways. Prostaglandin metabolism from arachidonate, multiple fatty acid metabolism pathways, several amino acid metabolism pathways, and pentose phosphate and related vitamin metabolism pathways were the most common pathways altered by all 5 chemicals. Detection of these altered pathways can be used as indicators to identify renal injury and promote repair.