Concordance between Thioacetamide-Induced Liver Injury in Rat and Human In Vitro Gene Expression Data

The immense resources required and the ethical concerns for animal-based toxicological studies have driven the development of in vitro and in silico approaches. Recently, we validated our approach in which the expression of a set of genes is uniquely associated with an organ-injury phenotype (injury module), by using thioacetamide, a known liver toxicant. Here, we sought to explore whether RNA-seq data obtained from human cells (in vitro) treated with thioacetamide-S-oxide (a toxic intermediate metabolite) would correlate across species with the injury responses found in rat cells (in vitro) after exposure to this metabolite as well as in rats exposed to thioacetamide (in vivo). We treated two human cell types with thioacetamide-S-oxide (primary hepatocytes with 0 (vehicle), 0.125 (low dose), or 0.25 (high dose) mM, and renal tubular epithelial cells with 0 (vehicle), 0.25 (low dose), or 1.00 (high dose) mM) and collected RNA-seq data 9 or 24 h after treatment. We found that the liver-injury modules significantly altered in human hepatocytes 24 h after high-dose treatment involved cellular infiltration and bile duct proliferation, which are linked to fibrosis. For high-dose treatments, our modular approach predicted the rat in vivo and in vitro results from human in vitro RNA-seq data with Pearson correlation coefficients of 0.60 and 0.63, respectively, which was not observed for individual genes or KEGG pathways.

An early developmental vertebrate model for nanomaterial safety: bridging cell-based and mammalian toxicity assessment

AIM

With the rise in production of nanoparticles (NPs) for an ever-increasing number of applications, there is an urgent need to efficiently assess their potential toxicity. We propose a NP hazard assessment protocol that combines mammalian cytotoxicity data with embryonic vertebrate abnormality scoring to determine an overall toxicity index.

RESULTS

We observed that, after exposure to a range of NPs, Xenopus phenotypic scoring showed a strong correlation with cell based in vitro assays. Magnetite-cored NPs, negative for toxicity in vitro and Xenopus, were further confirmed as nontoxic in mice.

CONCLUSION

The results highlight the potential of Xenopus embryo analysis as a fast screening approach for toxicity assessment of NPs, which could be introduced for the routine testing of nanomaterials.

In Vitro Tests for Aerosol Deposition. IV: Simulating Variations in Human Breath Profiles for Realistic DPI Testing

BACKGROUND

The amount of drug aerosol from an inhaler that can pass through an in vitro model of the mouth and throat (MT) during a realistic breath or inhalation flow rate vs. time profile (IP) is designated the total lung dose in vitro, or TLDin vitro. This article describes a clinical study that enabled us to recommend a general method of selecting IPs for use with powder inhalers of known airflow resistance (R) provided subjects followed written instructions either alone or in combination with formal training.

METHODS

In a drug-free clinical trial, inhaler-naïve, nonsmoking healthy adult human volunteers were screened for normal pulmonary function. IPs were collected from each volunteer inhaling through different air flow resistances after different levels of training. IPs were analyzed to determine the distribution of inhalation variables across the population and their dependence on training and airflow resistance.

RESULTS

Equations for IP simulation are presented that describe the data including confidence limits at each resistance and training condition. Realistic IPs at upper (90%), median (50%), and lower (10%) confidence limits were functions of R and training. Peak inspiratory flow rates (PIFR) were inversely proportional to R so that if R was assigned, values for PIFR could be calculated. The time of PIFR, TPIFR, and the total inhaled volume (V) were unrelated to R, but dependent on training. Once R was assigned for a powder inhaler to be tested, a range of simulated IPs could be generated for the different training scenarios. Values for flow rate acceleration and depth of inspiration could also be varied within the population limits of TPIFR and V.

CONCLUSIONS

The use of simulated IPs, in concert with realistic in vitro testing, should improve the DPI design process and the confidence with which clinical testing may be initiated for a chosen device.