The mitochondrial fission protein Drp1 in liver is required to mitigate NASH and prevents the activation of the mitochondrial ISR

[Objective]: The mitochondrial fission protein Drp1 was proposed to promote NAFLD, as inhibition of hepatocyte Drp1 early in life prevents liver steatosis induced by high-fat diet in mice. However, whether Drp1-knockdown in older mice can reverse established NASH is unknown. [Methods]: N-acetylgalactosamine-siRNA conjugates, an FDA approved method to deliver siRNA selectively to hepatocytes, were used to knockdown hepatocyte-Drp1 in mice (NAG-Drp1si). NASH was induced in C57BL/6NTac mice by Gubra-Amylin-NASH diet (D09100310, 40% fat, 22% fructose and 2% cholesterol) and treatment with NAG-Drp1si was started at week 24 of diet. Circulating transaminases, liver histology, gene expression of fibrosis and inflammation markers, and hydroxyproline synthesis determined NASH severity. Liver NEFA and triglycerides were quantified by GC/MS. Mitochondrial function was determined by respirometry. Western blots of Oma1, Opa1, p-eIf2α, as well as transcriptional analyses of Atf4-regulated genes determined ISR engagement. [Results]: NAG-Drp1si treatment decreased body weight and induced liver inflammation in adult healthy mice. Increased hepatic Gdf15 production was the major contributor to body-weight loss caused by NAG-Drp1si treatment, as Gdf15 receptor deletion (Gfral KO) prevented the decrease in food intake and mitigated weight loss. NAG-Drp1si activated the Atf4-controlled integrated stress response (ISR) to increase hepatic Gdf15 expression. NAG-Drp1si in healthy mice caused ER stress and activated the mitochondrial protease Oma1, which are the ER and mitochondrial triggers that activate the Atf4-controlled ISR. Remarkably, induction of NASH was not sufficient to activate Oma1 in liver. However, NAG-Drp1si treatment was sufficient to activate Oma1 in adult mice with NASH, as well as exacerbating NASH-induced ER stress. Consequently, NAG-Drp1si treatment in mice with NASH led to higher ISR activation, exacerbated inflammation, fibrosis and necrosis. [Conclusion]: Drp1 mitigates NASH by decreasing ER stress, preventing Oma1 activation and ISR exacerbation. The elevation in Gdf15 actions induced by NAG-Drp1si might represent an adaptive response decreasing the nutrient load to liver when mitochondria are misfunctional. Our study argues against blocking Drp1 in hepatocytes to combat NASH.M.L. and O.S.S. are funded by Janssen Research and Development, LLC, ICD #M3229099 – 846328. O.S.S. is funded by R01 DK099618-05; R01 CA232056-01; R21AG060456-01; R21 AG063373-01

Suppression of Insulin-Like Growth Factor Acid-Labile Subunit Expression—A Novel Mechanism for Deoxynivalenol-Induced Growth Retardation

Consumption of deoxynivalenol (DON), a trichothecene mycotoxin commonly detected in cereal-based foods, causes impaired growth in many animal species. While growth retardation is used as a basis for regulating DON levels in human food, the underlying mechanisms remain poorly understood. Oral exposure of mice to DON rapidly induces multiorgan expression of proinflammatory cytokines, and this is followed by upregulation of several suppressors of cytokine signaling (SOCS), some of which are capable of impairing growth hormone (GH) signaling. The purpose of this study was to test the hypothesis that impairment of the GH axis precedes DON-induced growth retardation in the mouse. Subchronic dietary exposure of young (4-week old) mice to DON (20 ppm) over a period of 2–8 weeks was found to (1) impair weight gain, (2) result in a steady-state plasma DON concentration (40–60 ng/ml), (3) downregulate hepatic insulin-like growth factor acid-labile subunit (IGFALS) mRNA expression, and (4) reduce circulating insulin-like growth factor 1 (IGF1) and IGFALS levels. Acute oral exposure to DON at 0.5–12.5 mg/kg body weight (bw) markedly suppressed hepatic IGFALS mRNA levels within 2 h in a dose-dependent fashion, whereas 0.1 mg/kg bw was without effect. DON-induced IGFALS mRNA upregulation occurred both with and without exogenous GH treatment. These latter effects co-occurred with robust hepatic suppressors of cytokine signaling 3 upregulation. Taken together, these data suggest that oral DON exposure perturbs GH axis by suppressing two clinically relevant growth-related proteins, IGFALS and IGF1. Both have potential to serve as biomarkers of effect in populations exposed to this common foodborne mycotoxin

Morphological characterization of canine retrobulbar lymphoma

This report characterized seven cases of canine retrobulbar lymphoma that have been diagnosed during 2008 to 2014 by immunophenotyping of CD3 and Pax5. Classification of lymphoma were performed according to the revised WHO guidelines. Four retrobulbar lymphomas were of T-cell origin, while the others were of B-cell. Out of 7 cases, four subtypes were diagnosed in this study; T-cell-rich large B-cell lymphoma (3/7), T-cell lymphoblastic lymphoma (2/7), peripheral T-cell lymphoma (1/7), and cutaneous nonepitheliotropic lymphoma (1/7). T-cell-rich large B-cell lymphoma was found to be the most frequent subtype found

Chemistry-Based Modeling on Phenotype-Based Drug-Induced Liver Injury Annotation : From Public to Proprietary Data

Funding Information: This work was funded by Janssen Pharmaceutica (LiToTIC Janssen, 310254) and supported by the Academy of Finland (Flagship programme: Finnish Center for Artificial Intelligence FCAI), ELISE Networks of Excellence Centres (EU Horizon:2020 grant agreement 951847), and UKRI Turing AI World-Leading Researcher 521 Fellowship (EP/W002973/1). We also acknowledge Johnson & Johnson, who funded the work in providing the data set and computational resources and Aalto Science-IT Project from Computer Science IT. The table of Contents (TOC) figure was created with BioRender.com. | openaire: EC/H2020/951847/EU//ELISEDrug-induced liver injury (DILI) is an important safety concern and a major reason to remove a drug from the market. Advancements in recent machine learning methods have led to a wide range of in silico models for DILI predictive methods based on molecule chemical structures (fingerprints). Existing publicly available DILI data sets used for model building are based on the interpretation of drug labels or patient case reports, resulting in a typical binary clinical DILI annotation. We developed a novel phenotype-based annotation to process hepatotoxicity information extracted from repeated dose in vivo preclinical toxicology studies using INHAND annotation to provide a more informative and reliable data set for machine learning algorithms. This work resulted in a data set of 430 unique compounds covering diverse liver pathology findings which were utilized to develop multiple DILI prediction models trained on the publicly available data (TG-GATEs) using the compound’s fingerprint. We demonstrate that the TG-GATEs compounds DILI labels can be predicted well and how the differences between TG-GATEs and the external test compounds (Johnson & Johnson) impact the model generalization performance.Peer reviewe

Kinetics of Satratoxin G Tissue Distribution and Excretion Following Intranasal Exposure in the Mouse

Intranasal exposure of mice to satratoxin G (SG), a macrocyclic trichothecene produced by the indoor air mold Stachybotrys chartarum, selectively induces apoptosis in olfactory sensory neurons (OSNs) of the nose and brain. The purpose of this study was to measure the kinetics of distribution and clearance of SG in the mouse. Following intranasal instillation of female C57B16 mice with SG (500 μg/kg bw), the toxin was detectable from 5 to 60 min in blood and plasma, with the highest concentrations, 30 and 19 ng/ml, respectively, being observed at 5 min. SG clearance from plasma was rapid and followed single-compartment kinetics (t1/2 = 20 min) and differed markedly from that of other tissues. SG concentrations were maximal at 15–30 min in nasal turbinates (480 ng/g), kidney (280 ng/g), lung (250 ng/g), spleen (200 ng/g), liver (140 ng/g), thymus (90 ng/g), heart (70 ng/g), olfactory bulb (14 ng/g), and brain (3 ng/g). The half-lives of SG in the nasal turbinate and thymus were 7.6 and 10.1 h, respectively, whereas in other organs, these ranged from 2.3 to 4.4 h. SG was detectable in feces and urine, but cumulative excretion over 5 days via these routes accounted for less than 0.3% of the total dose administered. Taken together, SG was rapidly taken up from the nose, distributed to tissues involved in respiratory, immune, and neuronal function, and subsequently cleared. However, a significant amount of the toxin was retained in the nasal turbinate, which might contribute to SG’s capacity to evoke OSN death