Acute effects of selected hepatotoxic agents on polyribosomes and protein synthesis in the livers of rats fed purified diets containing hepatocarcinogens

Predicting direct hepatocyte toxicity in humans by combining high-throughput imaging of HepaRG cells and machine learning-based phenotypic profiling

Accurate prediction of drug- and chemical-induced hepatotoxicity remains to be a problem for pharmaceutical companies as well as other industries and regulators. The goal of the current study was to develop an in vitro/in silico method for the rapid and accurate prediction of drug- and chemical-induced hepatocyte injury in humans. HepaRG cells were employed for high-throughput imaging in combination with phenotypic profiling. A reference set of 69 drugs and chemicals was screened at a range of 7 concentrations, and the cellular response values were used for training a supervised classifier and for determining assay performance by using tenfold cross-validation. The results showed that the best performing phenotypic features were related to nuclear translocation of RELA (RELA proto-oncogene, NF-kB subunit; also known as NF-kappa B p65), DNA organization, and the F-actin cytoskeleton. Using a subset of 30 phenotypic features, direct hepatocyte toxicity in humans could be predicted with a test sensitivity, specificity and balanced accuracy of 73%, 92%, and 83%, respectively. The method was applied to another set of 26 drugs and chemicals with unclear annotation and their hepatocyte toxicity in humans was predicted. The results also revealed that the identified discriminative phenotypic changes were related to cell death and cellular senescence. Whereas cell death-related endpoints are widely applied in in vitro toxicology, cellular senescence-related endpoints are not, although cellular senescence can be induced by various drugs and other small molecule compounds and plays an important role in liver injury and disease. These findings show how phenotypic profiling can reveal unexpected chemical-induced mechanisms in toxicology.

Effect of tryptophan on toxic cirrhosis induced by intermittent carbon tetrachloride intoxication in the rat

The effects of the administration of tryptophan on toxic cirrhosis induced by intermittent carbon tetrachloride (CCl4) intoxication in the rat were investigated. Rats received CCl4 (0.45 ml/100 g body wt ip) twice weekly for 10-14 weeks. Tryptophan (30 mg/100 g body wt) by stomach tube was administered 1 hr before killing. Tryptophan improved hepatic polyribosomal aggregation and [14C]leucine incorporation into protein in vitro of control rats as well as long-term CCl4-treated rats that had developed toxic cirrhosis. However, the effects were more marked in control than in experimental rats. Tryptophan administration induced an increase in labeled nuclear RNA release in vitro and a decrease in labeled tryptophan binding to nuclear protein in vitro of livers of rats receiving long-term CCl4 and of control rats. The results indicate that the stimulatory effects of a single administration of tryptophan in toxic cirrhotic livers are similar to, but somewhat less than, those which occur in livers of normal, control rats.