Acute solvent exposure induced activation of cytochrome P4502E1 causes proximal tubular cell necrosis by oxidative stress

Abstract

Deliberate exposure to solvents has been associated with kidney disorders. However, the mechanism by which solvents induce renal damage after acute exposure has not been studied. Proximal tubular cell (LLC-PK1) cytotoxicity after exposure for 48 h to either 5 m m of p-xylene (XY) or toluene (TL) was compared to control (C) by cell viability (MTS assay), LDH release, DNA fragmentation, and malondialdehyde (MDA) release. CYP2E1 activity with or without a free radical scavenger (catalase-CT), or the CYP2E1 inhibitor disulfiram (DSF), was examined. Both p-xylene and toluene significantly reduced cell viability (XY 53.9 8±1.6 vs TL 54.8±0.9 vs C 102.7±2.1), increased CYP2E1 activity (m m/mg protein/min) (XY 3.6±0.5 vs TL 3.7±0.7 vs C 1.3±0.4) and MDA release (μ m/mg protein) (XY 29.1±3.9 vs TL 12.3±1.4 vs C 2.8±0.3). LDH was increased (XY 59.9±3.0 vs TL 27.6±0.5 vs C 8.4±1.2), but there was no significant change in DNA fragmentation (OD/mg protein) suggesting necrosis as the predominant mode of cell death. DSF significantly attenuated CYP2E1 activity (XY+DSF 1.4±0.9, TL+DSF 2.3±0.1), LDH release (XY+DSF 45.1±2.0, TL+DSF 13.0±0.2) and MDA release (XY+DSF 4.3±0.5, TL+CT 6.2±1.1). Moreover, CT attenuated LDH release (XY+CT 36.4±5.1, TL+DSF 15.6±0.5) and MDA release (XY+DSF 5.4±0.7, TL+DSF 6.6±1.3) in XY and TL treated cells. This study confirms the pivotal role of CYP2E1 in solvent-induced oxidative stress and necrosis in proximal tubular cells after exposure to solvent at 5 m m for 48 h.