Utility of spherical human liver microtissues for prediction of clinical drug-induced liver injury.

Drug-induced liver injury (DILI) continues to be a major source of clinical attrition, precautionary warnings, and post-market withdrawal of drugs. Accordingly, there is a need for more predictive tools to assess hepatotoxicity risk in drug discovery. Three-dimensional (3D) spheroid hepatic cultures have emerged as promising tools to assess mechanisms of hepatotoxicity, as they demonstrate enhanced liver phenotype, metabolic activity, and stability in culture not attainable with conventional two-dimensional hepatic models. Increased sensitivity of these models to drug-induced cytotoxicity has been demonstrated with relatively small panels of hepatotoxicants. However, a comprehensive evaluation of these models is lacking. Here, the predictive value of 3D human liver microtissues (hLiMT) to identify known hepatotoxicants using a panel of 110 drugs with and without clinical DILI has been assessed in comparison to plated two-dimensional primary human hepatocytes (PHH). Compounds were treated long-term (14 days) in hLiMT and acutely (2 days) in PHH to assess drug-induced cytotoxicity over an 8-point concentration range to generate IC50 values. Regardless of comparing IC50 values or exposure-corrected margin of safety values, hLiMT demonstrated increased sensitivity in identifying known hepatotoxicants than PHH, while specificity was consistent across both assays. In addition, hLiMT out performed PHH in correctly classifying hepatotoxicants from different pharmacological classes of molecules. The hLiMT demonstrated sufficient capability to warrant exploratory liver injury biomarker investigation (miR-122, HMGB1, α-GST) in the cell-culture media. Taken together, this study represents the most comprehensive evaluation of 3D spheroid hepatic cultures up to now and supports their utility for hepatotoxicity risk assessment in drug discovery

Reconstituting Autophagy Initiation from Purified Components

International audienceThe hallmark of macroautophagy is the de novo generation of a membrane structure that collects cytoplasmic material and delivers it to lysosomes for degradation. The nucleation of this precursor membrane, termed phagophore, involves the coordinated assembly of the Atg1-kinase complex and the recruitment of Atg9 vesicles. The latter represents one important membrane source in order to produce phagophores in vivo. We explain how the process of phagophore nucleation can be reconstituted from purified components in vitro. We describe the assembly of the ~500 kDa pentameric Atg1-kinase complex from its purified subunits. We also explain how Atg9-donor vesicles are generated in vitro to study the interaction of Atg9 and Atg1-kinase complexes by floatation experiments

The identification and analysis of phosphorylation sites on the Atg1 protein kinase

Autophagy is a conserved, degradative process that has been implicated in a number of human diseases and is a potential target for therapeutic intervention. It is therefore important that we develop a thorough understanding of the mechanisms regulating this trafficking pathway. The Atg1 protein kinase is a key element of this control as a number of signaling pathways target this enzyme and its associated protein partners. These studies have established that Atg1 activities are controlled, at least in part, by protein phosphorylation. To further this understanding, we used a combined mass spectrometry and molecular biology approach to identify and characterize additional sites of phosphorylation in the Saccharomyces cerevisiae Atg1. Fifteen candidate sites of phosphorylation were identified, including nine that had not been noted previously. Interestingly, our data suggest that the phosphorylation at one of these sites, Ser-34, is inhibitory for both Atg1 kinase activity and autophagy. This site is located within a glycine-rich loop that is highly conserved in protein kinases. Phosphorylation at this position in several cyclin-dependent kinases has also been shown to result in diminished enzymatic activity. In addition, these studies identified Ser-390 as the site of autophosphorylation responsible for the anomalous migration exhibited by Atg1 on SDS-polyacrylamide gels. Finally, a mutational analysis suggested that a number of the sites identified here are important for full autophagy activity in vivo. In all, these studies identified a number of potential sites of regulation within Atg1 and will serve as a framework for future work with this enzyme

The EU-ToxRisk method documentation, data processing and chemical testing pipeline for the regulatory use of new approach methods

Hazard assessment, based on new approach methods (NAM), requires the use of batteries of assays, where individual tests may be contributed by different laboratories. A unified strategy for such collaborative testing is presented. It details all procedures required to allow test information to be usable for integrated hazard assessment, strategic project decisions and/or for regulatory purposes. The EU-ToxRisk project developed a strategy to provide regulatorily valid data, and exemplified this using a panel of > 20 assays (with > 50 individual endpoints), each exposed to 19 well-known test compounds (e.g. rotenone, colchicine, mercury, paracetamol, rifampicine, paraquat, taxol). Examples of strategy implementation are provided for all aspects required to ensure data validity: (i) documentation of test methods in a publicly accessible database; (ii) deposition of standard operating procedures (SOP) at the European Union DB-ALM repository; (iii) test readiness scoring accoding to defined criteria; (iv) disclosure of the pipeline for data processing; (v) link of uncertainty measures and metadata to the data; (vi) definition of test chemicals, their handling and their behavior in test media; (vii) specification of the test purpose and overall evaluation plans. Moreover, data generation was exemplified by providing results from 25 reporter assays. A complete evaluation of the entire test battery will be described elsewhere. A major learning from the retrospective analysis of this large testing project was the need for thorough definitions of the above strategy aspects, ideally in form of a study pre-registration, to allow adequate interpretation of the data and to ensure overall scientific/toxicological validity.This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 681002

Efficacy and safety of canagliflozin over 52 weeks in patients with type 2 diabetes mellitus and chronic kidney disease.

Aim: This study evaluated the efficacy and safety of canagliflozin, a sodium glucose co-transporter 2 inhibitor, in patients with type 2 diabetes mellitus (T2DM) and within a subset of Stage 3 chronic kidney disease (CKD; estimated glomerular filtration rate [eGFR] ≥30 and <50 ml/min/1.73 m2). Methods: In this 52-week, randomized, double-blind, placebo-controlled study, patients (N=269; mean eGFR, 39.4 ml/min/1.73 m2) received canagliflozin 100 or 300 mg and placebo once daily. Efficacy endpoints included changes in glycated haemoglobin (HbA1c), fasting plasma glucose (FPG), body weight and systolic blood pressure (BP); adverse events (AEs) were also recorded. Results: At week 52, canagliflozin 100 and 300 mg reduced HbA1c compared with placebo (-0.19, -0.33 and 0.07%, respectively); placebo-subtracted differences (95% confidence interval) were -0.27% (-0.53, 0.001) and -0.41% (-0.68, -0.14). Canagliflozin also lowered FPG, body weight and BP versus placebo. Overall AE incidence was 85.6, 80.9, and 86.7% with canagliflozin 100 and 300 mg and placebo, respectively. Osmotic diuresis-related AEs were more common with both canagliflozin doses, and incidences of urinary tract infections and volume depletion-related AEs were higher with canagliflozin 300 mg versus placebo. Decreases in eGFR (-2.1, -4.0 and -1.6 ml/min/1.73 m2) were seen with canagliflozin 100 and 300 mg compared with placebo. Canagliflozin 100 and 300 mg provided median percent reductions in urine albumin to creatinine ratio versus placebo (-16.4, -28.0 and 19.7%). Conclusions: Canagliflozin improved glycaemic control and was generally well tolerated in patients with T2DM and within a subset of Stage 3 CKD over 52 weeks