Evaluating the suitability of precision-cut tissue slices to study bile acid-induced nephrotoxicity
Rianne van Dekken, Sandra M. Hansen, Rikke Nørregaard and Henricus A.M. Mutsaers
Department of Clinical Medicine, Aarhus University
Background: Chronic kidney disease (CKD) is characterized by progressive damage to the kidneys, leading to a gradual decline in kidney function over time. In 2017, 1.2 million deaths were caused by CKD, which is expected to rise to 2.2-4.0 million deaths by 2040. Currently, dialysis and kidney transplantation are the only treatment options for patients with end-stage renal disease, emphasizing the need for novel treatments. Recent studies suggest that elevated bile acid levels in the blood are a risk factor for CKD; however, the exact pathophysiological mechanism remains unclear. This study will evaluate the suitability of Precision-Cut Kidney Slices (PCKS) to study bile acid-induced nephrotoxicity. The PCKS model is a unique technique in the sense that each slice contains all cell types and components of the kidney in the original configuration, with intact cell-cell and cell-matrix interactions.
Methods: Using the Alabama R&D Tissue Slicer (formerly Krumdieck Tissue Slicer), mice PCKS (mPCKS) were prepared from kidneys harvested from C57BL/6 mice (n=5). Mice were anesthetized with 5% sevoflurane and sacrificed by cervical dislocation. mPCKS were cultured for 24H, 48H, and 72H. Afterwards, the gene expression of various bile acid receptors (FXR, PXR, VDR, CAR, TGR5, and S1PR2) was evaluated using RT-PCR. Gene levels were normalized and compared to the 0H control using one-way ANOVA.
Results: The results demonstrated that all tested bile acid receptors are expressed on gene level in mPCKS. The gene expression of FXR, PXR, VDR, and CAR significantly decreased more than 3,7-fold after 24H (P-value: <0.0011 for all receptors), after which expression levels remained stable up to 72H. The gene expression of TGR5 and S1PR2 significantly increased more than 5-fold after 24H, after which the expression levels increased consistently up to 72H (P-value: <0.0141). In addition, mPCKS remained viable during the whole incubation period, as illustrated by stable ATP levels.
Conclusion: These data indicate that the various components for bile acid signaling are present in mPCKS. Based on this we suggest that mPCKS can be used as a model for bile acid-induced nephrotoxicity.