Adapting a quantitative systems toxicology model of mitochondrial dysfunction in liver to kidney

Authors: Tallapaka SB, Gebremichael Y, Siler SQ, Howell BA, Woodhead JL
Conference: ACoP
Keywords: Acute kidney injury (AKI), kidney, liver, mitochondrial dysfunction, oxidative stress, Quantitative Systems Toxicology (QST)
Software: RENAsym®
Division: DILIsym Services

Abstract

Objective: Kidney, as a major excretory organ, is exposed to high levels of drugs and their  metabolites. Therefore, kidney toxicity is an important part of drug safety assessment in  clinical trials. RENAsymTM is a quantitative systems toxicology (QST) model of drug induced  acute kidney injury (AKI) currently under development. In its current  form, the model includes representations of proximal tubule cell (PTC)  lifecycle, bioenergetics, cellular injury and death pathways. Our objective is to develop a  mechanistic mathematical model of mitochondrial dysfunction in proximal tubule cells to predict  drug induced AKI.

Methods: We adapted the mitochondrial dysfunction model existing in DILIsym®, a QST  model of drug induced liver injury, by modifying the equations to accommodate the  physiological differences between kidney and liver. Changes made in order to translate  the model to the kidney include (but are not limited to) eliminating de novo  lipogenesis and glycogen storage, refining PTC bioenergetics, and changing  mitochondrial substrate utilization. For example, glucose oxidation was removed during  homeostasis as little glucose oxidation was observed in rat proximal convoluted  tubules. We then simulated gentamicin as an exemplar compound to qualitatively validate  the model. Gentamicin in vitro mitochondrial toxicity was measured in HepG2 cells and  converted to RENAsymTM parameters using MITOsym®. Parameters for oxidative stress and kidney exposure were obtained from literature.

Results: Simulations predicted significant toxicity in rats (100 mg/kg QD dosing) and  humans (3mg/kg QD dosing) within 24h. Oxidative stress was predicted to be the major  mechanism of toxicity in both species. Mild mitochondrial signals were predicted in rats and none  in humans.

Conclusions: A mitochondrial dysfunction model originally constructed for the  liver has been adapted to the kidney and reasonably predicts gentamicin-induced AKI.  Simulations show that gentamicin induced oxidative stress causes more toxicity than mitochondrial dysfunction.

By Shailendra B. Tallapaka, YeshitilaGebremichael, Scott Q. Siler, Brett A. Howell, Jeffrey L. Woodhead

Tenth Annual American Conference on Pharmacometrics (ACoP) Annual Meeting: October 19-22, 2019, Orlando, FL