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Schwann cells (SCs) support peripheral nerves under homeostatic conditions, independent of myelination, and contribute to damage in prediabetic peripheral neuropathy (PN). Here, we used single‐cell RNA sequencing to characterize the transcriptional profiles and intercellular communication of SCs in the nerve microenvironment using the high‐fat diet‐fed mouse, which mimics human prediabetes and neuropathy. We identified four major SC clusters, myelinating, nonmyelinating, immature, and repair in healthy and neuropathic nerves, in addition to a distinct cluster of nerve macrophages. Myelinating SCs acquired a unique transcriptional profile, beyond myelination, in response to metabolic stress. Mapping SC intercellular communication identified a shift in communication, centered on immune response and trophic support pathways, which primarily impacted nonmyelinating SCs. Validation analyses revealed that neuropathic SCs become pro‐inflammatory and insulin resistant under prediabetic conditions. Overall, our study offers a unique resource for interrogating SC function, communication, and signaling in nerve pathophysiology to help inform SC‐specific therapies. [ABSTRACT FROM AUTHOR]

Background: Obesity and metabolic dysfunction (Metabolic Syndrome, prediabetes, and diabetes) increase the risk of later life cognitive impairment, including dementias such as Alzheimer's Disease1‐3. One common etiology that might underly this increased risk is immune system dysregulation and inflammation4, 5. Specifically, microglial dependent mechanisms are thought to play an important role in pathology6‐8. However, the precise immune and inflammatory mechanisms promoting cognitive decline secondary to obesity and metabolic dysfunction are unclear. Method: BL6 male mice were fed 60% HFD (high fat diet) or 10% SD (standard diet) for 1 year. Body weight and glucose tolerance were assessed longitudinally. Cognition was repeatedly evaluated using Morris water maze, social recognition, and puzzle box. At study termination, mice were given either an intraperitoneal injection of lipopolysaccharide as an immune challenge or saline as a control. Activation of hippocampal microglia was assessed via immunohistochemistry (IHC) and analysis of microglial morphology. Changes in brain gene expression were measured via spatial transcriptomics using the 10X Visium platform. Result: HFD feeding caused increased weight, impaired glucose tolerance, and cognitive deficits which persisted throughout the study period. Body weight in particular was predictive of cognitive changes, especially for later time points. In response to immune challenge, hippocampal microglia in SD mice had a normal morphological response indicative of activation. However, microglia of HFD mice had no change in their morphology in response to lipopolysaccharide injection. Additionally, changes in morphology significantly correlated with cognition and indicated that a higher percentage of activated hippocampal microglia is associated with a worse cognitive phenotype. Spatial transcriptomics analysis showed changes in gene expression in multiple brain regions of HFD mice, including the hippocampus, many of which were related to neurodegenerative and inflammatory pathways. Conclusion: These data support that HFD feeding causes an early and persistent cognitive impairment, which is associated with obesity. Our data also confirm a role for microglia in HFD‐induced cognitive impairment. Indeed, microglial and transcriptomic data strongly indicate a role for inflammation and inflammatory pathways in HFD‐induced cognitive impairment. [ABSTRACT FROM AUTHOR]

Drug‐induced peripheral neuropathy is a side effect of a variety of therapeutic agents that can affect therapeutic adherence and lead to regimen modifications, impacting patient quality of life. The molecular mechanisms involved in the development of this condition have yet to be completely described in the literature. We used a computational network pharmacology approach to explore the Connectivity Map, a large collection of transcriptional profiles from drug perturbation experiments to identify common genes affected by peripheral neuropathy‐inducing drugs. Consensus profiles for 98 of these drugs were used to construct a drug–gene perturbation network. We identified 27 genes significantly associated with neuropathy‐inducing drugs. These genes may have a potential role in the action of neuropathy‐inducing drugs. Our results suggest that molecular mechanisms, including alterations in mitochondrial function, microtubule and cytoskeleton function, ion channels, transcriptional regulation including epigenetic mechanisms, signal transduction, and wound healing, may play a critical role in drug‐induced peripheral neuropathy. [ABSTRACT FROM AUTHOR]

Drug‐induced cardiomyopathy contributes to drug attrition. We compared two pipelines of predictive modeling: (1) applying elastic net (EN) to differentially expressed genes (DEGs) of drugs; (2) applying integer linear programming (ILP) to construct each drug's signaling pathway starting from its targets to downstream proteins, to transcription factors, and to its DEGs in human cardiomyocytes, and then subjecting the genes/proteins in the drugs' signaling networks to EN regression. We classified 31 drugs with availability of DEGs into 13 toxic and 18 nontoxic drugs based on a clinical cardiomyopathy incidence cutoff of 0.1%. The ILP‐augmented modeling increased prediction accuracy from 79% to 88% (sensitivity: 88%; specificity: 89%) under leave‐one‐out cross validation. The ILP‐constructed signaling networks of drugs were better predictors than DEGs. Per literature, the microRNAs that reportedly regulate expression of our six top predictors are of diagnostic value for natural heart failure or doxorubicin‐induced cardiomyopathy. This translational predictive modeling might uncover potential biomarkers. [ABSTRACT FROM AUTHOR]

Treating insulin resistance with pioglitazone normalizes renal function and improves small nerve fibre function and architecture; however, it does not affect large myelinated nerve fibre function in mouse models of type 2 diabetes (T2 DM), indicating that pioglitazone affects the body in a tissue-specific manner. To identify distinct molecular pathways regulating diabetic peripheral neuropathy ( DPN) and nephropathy ( DN), as well those affected by pioglitazone, we assessed DPN and DN gene transcript expression in control and diabetic mice with or without pioglitazone treatment. Differential expression analysis and self-organizing maps were then used in parallel to analyse transcriptome data. Differential expression analysis showed that gene expression promoting cell death and the inflammatory response was reversed in the kidney glomeruli but unchanged or exacerbated in sciatic nerve by pioglitazone. Self-organizing map analysis revealed that mitochondrial dysfunction was normalized in kidney and nerve by treatment; however, conserved pathways were opposite in their directionality of regulation. Collectively, our data suggest inflammation may drive large fibre dysfunction, while mitochondrial dysfunction may drive small fibre dysfunction in T2 DM. Moreover, targeting both of these pathways is likely to improve DN. This study supports growing evidence that systemic metabolic changes in T2 DM are associated with distinct tissue-specific metabolic reprogramming in kidney and nerve and that these changes play a critical role in DN and small fibre DPN pathogenesis. These data also highlight the potential dangers of a 'one size fits all' approach to T2 DM therapeutics, as the same drug may simultaneously alleviate one complication while exacerbating another. [ABSTRACT FROM AUTHOR]

Genotoxicity potential is a critical component of any comprehensive toxicological profile. Compounds that induce DNA or chromosomal damage often activate p53, a transcription factor essential to cell cycle regulation. Thus, within the US Tox21 Program, we screened a library of ∼10,000 (∼8,300 unique) environmental compounds and drugs for activation of the p53-signaling pathway using a quantitative high-throughput screening assay employing HCT-116 cells (p53+/+) containing a stably integrated β-lactamase reporter gene under control of the p53 response element (p53RE). Cells were exposed (-S9) for 16 hr at 15 concentrations (generally 1.2 nM to 92 μM) three times, independently. Excluding compounds that failed analytical chemistry analysis or were suspected of inducing assay interference, 365 (4.7%) of 7,849 unique compounds were concluded to activate p53. As part of an in-depth characterization of our results, we first compared them with results from traditional in vitro genotoxicity assays (bacterial mutation, chromosomal aberration); ∼15% of known, direct-acting genotoxicants in our library activated the p53RE. Mining the Comparative Toxicogenomics Database revealed that these p53 actives were significantly associated with increased expression of p53 downstream genes involved in DNA damage responses. Furthermore, 53 chemical substructures associated with genotoxicity were enriched in certain classes of p53 actives, for example, anthracyclines (antineoplastics) and vinca alkaloids (tubulin disruptors). Interestingly, the tubulin disruptors manifested unusual nonmonotonic concentration response curves suggesting activity through a unique p53 regulatory mechanism. Through the analysis of our results, we aim to define a role for this assay as one component of a comprehensive toxicological characterization of large compound libraries. Environ. Mol. Mutagen. 58:494-507, 2017. © 2017 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: The US Toxicology Testing in the 21st Century (Tox21) program was established to develop more efficient and human‐relevant toxicity assessment methods. The Tox21 program screens >10,000 chemicals using quantitative high‐throughput screening (qHTS) of assays that measure effects on toxicity pathways. To date, more than 70 assays have yielded >12 million concentration‐response curves. The patterns of activity across assays can be used to define similarity between chemicals. Assuming chemicals with similar activity profiles have similar toxicological properties, we may infer toxicological properties based on its neighbourhood. One approach to inference is chemical/biological annotation enrichment analysis. Here, we present Tox21 Enricher, a web‐based chemical annotation enrichment tool for the Tox21 toxicity screening platform. Tox21 Enricher identifies over‐represented chemical/biological annotations among lists of chemicals (neighbourhoods), facilitating the identification of the toxicological properties and mechanisms in the chemical set. [ABSTRACT FROM AUTHOR]

Objective The US Food and Drug Administration-approved trial, 'A Phase 1, Open-Label, First-in-Human, Feasibility and Safety Study of Human Spinal Cord-Derived Neural Stem Cell Transplantation for the Treatment of Amyotrophic Lateral Sclerosis, Protocol Number: NS2008-1,' is complete. Our overall objective was to assess the safety and feasibility of stem cell transplantation into lumbar and/or cervical spinal cord regions in amyotrophic lateral sclerosis (ALS) subjects. Methods Preliminary results have been reported on the initial trial cohort of 12 ALS subjects. Here, we describe the safety and functional outcome monitoring results for the final trial cohort, consisting of 6 ALS subjects receiving 5 unilateral cervical intraspinal neural stem cell injections. Three of these subjects previously received 10 total bilateral lumbar injections as part of the earlier trial cohort. All injections utilized a novel spinal-mounted stabilization and injection device to deliver 100,000 neural stem cells per injection, for a dosing range up to 1.5 million cells. Subject assessments included detailed pre- and postsurgical neurological outcome measures. Results The cervical injection procedure was well tolerated and disease progression did not accelerate in any subject, verifying the safety and feasibility of cervical and dual-targeting approaches. Analyses on outcome data revealed preliminary insight into potential windows of stem cell biological activity and identified clinical assessment measures that closely correlate with ALS Functional Rating Scale-Revised scores, a standard assessment for ALS clinical trials. Interpretation This is the first report of cervical and dual-targeted intraspinal transplantation of neural stem cells in ALS subjects. This approach is feasible and well-tolerated, supporting future trial phases examining therapeutic dosing and efficacy. Ann Neurol 2014;75:363-373 [ABSTRACT FROM AUTHOR]

Over the past 20 years, stem cell technologies have become an increasingly attractive option to investigate and treat neurodegenerative diseases. In the current review, we discuss the process of extending basic stem cell research into translational therapies for patients suffering from neurodegenerative diseases. We begin with a discussion of the burden of these diseases on society, emphasizing the need for increased attention toward advancing stem cell therapies. We then explain the various types of stem cells utilized in neurodegenerative disease research, and outline important issues to consider in the transition of stem cell therapy from bench to bedside. Finally, we detail the current progress regarding the applications of stem cell therapies to specific neurodegenerative diseases, focusing on Parkinson disease, Huntington disease, Alzheimer disease, amyotrophic lateral sclerosis, and spinal muscular atrophy. With a greater understanding of the capacity of stem cell technologies, there is growing public hope that stem cell therapies will continue to progress into realistic and efficacious treatments for neurodegenerative diseases. Ann Neurol 2011;70: 353-361. [ABSTRACT FROM AUTHOR]