Benzalkonium Chloride-Induced Nephrotoxicity in 2D Cultures and a Human Kidney-on-a-Chip System

Benzalkonium chlorides (BACs) are antimicrobial compounds widely used across a variety of settings, and the COVID-19 pandemic has led to significantly increased usage of BAC-containing products. Previous studies in animals have shown that the kidney is the primary site of BAC accumulation, whereas the liver does not accumulate BACs, likely due to efficient hepatic cytochrome P450-mediated metabolism. Thus, we hypothesized that low BAC-metabolizing capacity contributes to the extent of BAC buildup in the kidney and promotes subsequent kidney injury. Using 2D-cultured proximal tubule epithelial cells (PTECs), we found that renal metabolism is insufficient to detoxify BACs. We then assessed BACs' nephrotoxicity using a novel 3D "kidney-on-a-chip" microphysiological system (MPS). The MPS was exposed to C₁₂- or C₁₄-BAC at 100 nM for 1 week. Transcriptomic analysis of the 3D-cultured PTECs reveals several significantly altered biochemical pathways following BAC exposure, including focal adhesion and cholesterol biosynthesis. Additional studies utilizing orthogonal techniques validated the phenotypic changes associated with some of the significantly altered pathways using 2D-cultured PTECs. Together, these findings demonstrate that the poor BAC-metabolizing capacity of PTECs contributes to the nephrotoxicity of BACs.