Nonconcordant regulation of mitochondrial respiratory complexes in the kidneys of 5/6 nephrectomized mice.

Hyperglycemia induces nonconcordant regulation of renal mitochondrial respiratory complexes, increases oxidative stress, and causes diabetic nephropathy. Hypertension is a complication associated with diabetes and involves glomerular hyperfiltration, the effects of which on mitochondrial respiratory complexes are not well understood. To investigate the effect of glomerular hyperfiltration on renal mitochondrial respiratory complexes, we used the 5/6 nephrectomized BKS. Cg-Dock7m+/+Leprdb/J, Dock7m+/+Leprdb mice (db/m-5/6Nx mice) as a model for glomerular hyperfiltration. The BKS. Cg-Dock7m+/+Leprdb/J, +Leprdb/+Leprdb mice (db/db mice), a model for type 2 diabetes, was used as the positive control. We investigated the activities and protein levels of the mitochondrial complex, and the mitochondrial DNA and adenosine triphosphate content in the kidneys of these models. Blood chemistry and renal histopathological examination were performed for characterization of the disease. Both models showed expansion of the mesangial matrix of the glomeruli, which is indicative of glomerular hyperfiltration. The activities of complexes I and IV and the protein levels of complexes I and III were nonconcordant in db/m-5/6Nx mice. In conclusion, we demonstrated that nonconcordant regulation of mitochondrial complexes in db/m-5/6Nx mice involved with glomerular hyperfiltration. The progression and/or severity of nephropathy might be affected through a synergistic effect of mitochondrial dysfunction in hyperglycemia and glomerular hyperfiltration. J. Med. Invest. 64: 255-261, August, 2017.

In Vitro Drug-Induced Liver Injury Prediction: Criteria Optimization of Efflux Transporter IC50 and Physicochemical Properties.

Drug-induced liver injury (DILI) is a severe drug adverse response, which cannot always be reliably predicted in preclinical or clinical studies. Lack of observation of DILI during preclinical and clinical drug development has led to DILI being a leading cause of drug withdrawal from the market. As DILI is potentially fatal, pharmaceutical companies have been developing in vitro tools to screen for potential liver injury. Screens for physicochemical properties, mitochondrial function, and transport protein inhibition have all been employed to varying degrees of success. In vitro inhibition of the bile salt export pump (BSEP) has become a major risk factor for in vivo DILI predictions, yet discrepancies exist in which methods to use and the extent to which BSEP inhibition predicts clinical DILI. The presented work focuses on optimizing DILI predictions by comparing BSEP inhibition via the membrane vesicle assay and the hepatocyte-based BSEPcyte assay, as well as dual and triple liabilities. BSEP transport inhibition of taurcholic acids and glycocholic acids were similar for up to 29 drugs tested, in both the vesicle and hepatocyte-based assays. Positive and negative DILI predictions were optimized at a 50-µM cutoff value for 50 drugs using both NIH Livertox and PharmaPendium databases. Additionally, dual inhibition of BSEP and other efflux transporters (multidrug resistance-associated protein [MRP]2, MRP3, or MRP4) provided no observable predictive benefit compared with BSEP inhibition alone. Eighty-five percent of drugs with high molecular weight (>600 Da), high cLogP (>3), or a daily dose >100 mg and BSEP inhibition were associated with DILI. Triple liability of BSEP inhibition, high molecular weight, and high cLogP attained a 100% positive prediction rate.