Cutaneous Arsenical Exposure Induces Distinct Metabolic Transcriptional Alterations of Kidney Cells

Abstract

Arsenicals are deadly chemical warfare agents that primarily cause death through systemic capillary fluid leakage and hypovolemic shock. Arsenical exposure is also known to cause acute kidney injury, a condition that contributes to arsenical-associated death due to the necessity of the kidney in maintaining whole-body fluid homeostasis. Because of the global health risk that arsenicals pose, a nuanced understanding of how arsenical exposure can lead to kidney injury is needed. We used a nontargeted transcriptional approach to evaluate the effects of cutaneous exposure to phenylarsine oxide, a common arsenical, in a murine model. Here we identified an upregulation of metabolic pathways such as fatty acid oxidation, fatty acid biosynthesis, and peroxisome proliferator-activated receptor (PPAR)-α signaling in proximal tubule epithelial cell and endothelial cell clusters. We also revealed highly upregulated genes such as Zbtb16, Cyp4a14, and Pdk4, which are involved in metabolism and metabolic switching and may serve as future therapeutic targets. The ability of arsenicals to inhibit enzymes such as pyruvate dehydrogenase has been previously described in vitro. This, along with our own data, led us to conclude that arsenical-induced acute kidney injury may be due to a metabolic impairment in proximal tubule and endothelial cells and that ameliorating these metabolic effects may lead to the development of life-saving therapies. SIGNIFICANCE STATEMENT: In this study, we demonstrate that cutaneous arsenical exposure leads to a transcriptional shift enhancing fatty acid metabolism in kidney cells, indicating that metabolic alterations might mechanistically link topical arsenical exposure to acute kidney injury. Targeting metabolic pathways may generate promising novel therapeutic approaches in combating arsenical-induced acute kidney injury.

Fig. 1.

Single nuclei RNA sequencing cluster identification: validation of successfully integrated single nuclei RNA sequencing data of 12 mice into a combined data set, grouped according to the individual mice used in the study (A). Combined UMAP showing cluster identities of kidney parenchymal cell types and one immune cell population (B). A dot plot showing expression of known gene transcripts and the proportion of cells expressing them for the identification of kidney and immune cell types (C).

Fig. 2.

KEGG-enriched pathways in proximal tubule cell and endothelial cell clusters: enrichment analysis of the Kyoto Encyclopedia of Genes and Genomes database pathways at 6 and 24 hours in the PT1 cluster (A), PT2 cluster (B), PT3 cluster (C), EC1 cluster (D), and EC2 cluster (E). False discovery rate (FDR) was <0.05 for all pathways shown.

Fig. 3.

Fatty acid metabolic pathways: violin plots of specific fatty acid metabolic pathways of interest expressed in rank order density of member genes for each gene set, sorted by cluster identity and time points (blue = 6-hour vehicle, green = 24-hour vehicle, orange = 6-hour PAO, red = 24-hour PAO). Boxplots show medians, lower quartile, and upper quartile distributions across all samples. Fatty acid β-oxidation (A), fatty acid biosynthesis (B), fatty acid ω-oxidation (C), fatty acid transporters (D), mitochondrial long chain fatty acid β-oxidation (E), and PPAR-α pathway (F). Significance is indicated by * (6-hour PAO vs. 6-hour vehicle P < 0.05) and # (6-hour PAO vs. 6-hour vehicle P < 0.05 and 24-hour PAO vs. 24-hour vehicle P < 0.05).

Fig. 4.

Theoretical pathologic process of PAO-induced AKI: a theoretical process by which phenylarsine oxide (PAO) may induce kidney injury through pyruvate dehydrogenase inhibition. Fatty acid metabolic process upregulation may be a compensatory response.