Showing papers in "Toxicologic Pathology in 2020"

Predatory Journals: What They Are and How to Avoid Them.

Abstract: Predatory journals-also called fraudulent, deceptive, or pseudo-journals-are publications that claim to be legitimate scholarly journals but misrepresent their publishing practices. Some common forms of predatory publishing practices include falsely claiming to provide peer review, hiding information about article processing charges, misrepresenting members of the journal's editorial board, and other violations of copyright or scholarly ethics. Because of their increasing prevalence, this article aims to provide helpful information for authors on how to identify and avoid predatory journals.

A Comparative Review of Chemotherapy-Induced Peripheral Neuropathy in In Vivo and In Vitro Models:

Abstract: Chemotherapy-induced peripheral neuropathy (CIPN) is an adverse effect caused by several classes of widely used anticancer therapeutics. Chemotherapy-induced peripheral neuropathy frequently leads to dose reduction or discontinuation of chemotherapy regimens, and CIPN symptoms can persist long after completion of chemotherapy and severely diminish the quality of life of patients. Differences in the clinical presentation of CIPN by widely diverse classifications of anticancer agents have spawned multiple mechanistic hypotheses that seek to explain the pathogenesis of CIPN. Despite its clinical relevance, common occurrence, and extensive investigation, the pathophysiology of CIPN remains unclear. Furthermore, there is no unequivocal gold standard for the prevention and treatment of CIPN. Herein, we review in vivo and in vitro models of CIPN with a focus on histopathological changes and morphological features aimed at understanding the pathophysiology of CIPN and identify gaps requiring deeper exploration. An elucidation of the underlying mechanisms of CIPN is imperative to identify potential targets and approaches for prevention and treatment.

Society of Toxicologic Pathology Digital Pathology and Image Analysis Special Interest Group Article*: Opinion on the Application of Artificial Intelligence and Machine Learning to Digital Toxicologic Pathology:

Abstract: Toxicologic pathology is transitioning from analog to digital methods. This transition seems inevitable due to a host of ongoing social and medical technological forces. Of these, artificial intell...

Assessment of the Mode of Action Underlying the Effects of GenX in Mouse Liver and Implications for Assessing Human Health Risks

Abstract: GenX is an alternative to environmentally persistent long-chain perfluoroalkyl and polyfluoroalkyl substances. Mice exposed to GenX exhibit liver hypertrophy, elevated peroxisomal enzyme activity, ...

Functional Anatomy of the Sensory Nervous System: Updates From the Neuroscience Bench:

Abstract: The simple tripartite classification of sensory neurons as A-beta, A-delta, and C fibers fails to convey the complexity of the neurons that encode stimuli as diverse as the texture of a surface, the location of a pinprick, or the direction of hair movement as a breeze moves across the skin. It has also proven to be inadequate when investigating the molecular mechanisms underlying pain, which can encompass any combination of chemical, tactile, and thermal modalities. Beginning with a brief overview of visceral and sensory neuroanatomy, this review expands upon sensory innervation of the skin as a prime example of the heterogeneity and complexity of the somatosensory nervous system. Neuroscientists have characterized defining features of over 15 subtypes of sensory neurons that innervate the skin of the mouse. This has enabled the study of cell-specific mechanisms of pain, which suggests that diverse sensory neuron subtypes may have distinct susceptibilities to toxic injury and different roles in pathologic mechanisms underlying altered sensation. Leveraging this growing body of knowledge for preclinical trials and models of neurotoxicity can vastly improve our understanding of peripheral nervous system dysfunction, advancing the fields of toxicologic pathology and neuropathology alike.

Review of Current Vaccine Development Strategies to Prevent Coronavirus Disease 2019 (COVID-19).

Abstract: The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) outbreak that started in Wuhan, China, in 2019 resulted in a pandemic not seen for a century, and there is an urgent need to develop safe and efficacious vaccines. The scientific community has made tremendous efforts to understand the disease, and unparalleled efforts are ongoing to develop vaccines and treatments. Toxicologists and pathologists are involved in these efforts to test the efficacy and safety of vaccine candidates. Presently, there are several SARS-CoV-2 vaccines in clinical trials, and the pace of vaccine development has been highly accelerated to meet the urgent need. By 2021, efficacy and safety data from clinical trials are expected, and potentially a vaccine will be available for those most at risk. This review focuses on the ongoing SARS-CoV-2 vaccine development efforts with emphasis on the nonclinical safety assessment and discusses emerging preliminary data from nonclinical and clinical studies. It also provides a brief overview on vaccines for other coronaviruses, since experience gained from these can be useful in the development of SARS-CoV-2 vaccines. This review will also explain why, despite this unprecedented pace of vaccine development, rigorous standards are in place to ensure nonclinical and clinical safety and efficacy. [Box: see text].

Intraepidermal Nerve Fiber Analysis in Human Patients and Animal Models of Peripheral Neuropathy: A Comparative Review

Abstract: Analysis of intraepidermal nerve fibers (IENFs) in skin biopsy samples has become a standard clinical tool for diagnosing peripheral neuropathies in human patients. Compared to sural nerve biopsy, skin biopsy is safer, less invasive, and can be performed repeatedly to facilitate longitudinal assessment. Intraepidermal nerve fiber analysis is also more sensitive than conventional nerve histology or electrophysiological tests for detecting damage to small-diameter sensory nerve fibers. The techniques used for IENF analysis in humans have been adapted for large and small animal models and successfully used in studies of diabetic neuropathy, chemotherapy-induced peripheral neuropathy, HIV-associated sensory neuropathy, among others. Although IENF analysis has yet to become a routine end point in nonclinical safety testing, it has the potential to serve as a highly relevant indicator of sensory nerve fiber status in neurotoxicity studies, as well as development of neuroprotective and neuroregenerative therapies. Recently, there is also interest in the evaluation of IENF via skin biopsy as a biomarker of small fiber neuropathy in the regulatory setting. This article provides an overview of the anatomic and pathophysiologic principles behind IENF analysis, its use as a diagnostic tool in humans, and applications in animal models with focus on comparative methodology and considerations for study design.

Toxic Peripheral Neuropathies: Agents and Mechanisms.

Abstract: Toxic peripheral neuropathies are an important form of acquired polyneuropathy produced by a variety of xenobiotics and different exposure scenarios. Delineating the mechanisms of neurotoxicants and determining the degenerative biological pathways triggered by peripheral neurotoxicants will facilitate the development of sensitive and specific biochemical-based methods for identifying neurotoxicants, designing therapeutic interventions, and developing structure-activity relationships for predicting potential neurotoxicants. This review presents an overview of the general concepts of toxic peripheral neuropathies with the goal of providing insight into why certain agents target the peripheral nervous system and produce their associated lesions. Experimental data and the main hypotheses for the mechanisms of selected agents that produce neuronopathies, axonopathies, or myelinopathies including covalent or noncovalent modifications, compromised energy or protein biosynthesis, and oxidative injury and disruption of ionic gradients across membranes are presented. The relevance of signaling between the main components of peripheral nerve, that is, glia, neuronal perikaryon, and axon, as a target for neurotoxicants and the contribution of active programmed degenerative pathways to the lesions observed in toxic peripheral neuropathies is also discussed.

Animal Models of Peripheral Pain: Biology Review and Application for Drug Discovery.

Abstract: Pain is a complex constellation of cognitive, unpleasant sensory, and emotional experiences that primarily serves as a survival mechanism. Pain arises in the peripheral nervous system and pain sign...

Atlas of Normal Microanatomy, Procedural and Processing Artifacts, Common Background Findings, and Neurotoxic Lesions in the Peripheral Nervous System of Laboratory Animals.

Abstract: The ability to differentiate among normal structures, procedural and processing artifacts, spontaneous background changes, and test article-related effects in the peripheral nervous system (PNS) is essential for interpreting microscopic features of ganglia and nerves evaluated in animal species commonly used in toxicity studies evaluating regulated products and chemicals. This atlas provides images of findings that may be encountered in ganglia and nerves of animal species commonly used in product discovery and development. Most atlas images are of tissues from control animals that were processed using routine methods (ie, immersion fixation in neutral-buffered 10% formalin, embedding in paraffin, sectioning at 5 µm, and staining with hematoxylin and eosin) since these preparations are traditionally applied to study materials produced during most animal toxicity studies. A few images are of tissues processed using special procedures (ie, immersion or perfusion fixation using methanol-free 4% formaldehyde, postfixation in glutaraldehyde and osmium, embedding in hard plastic resin, sectioning at 1 µm, and staining with toluidine blue), since these preparations promote better stabilization of lipids and thus optimal resolution of myelin sheaths. Together, this compilation provides a useful resource for discriminating among normal structures, procedure- and processing-related artifacts, incidental background changes, and treatment-induced findings that may be seen in PNS tissues of laboratory animals.

Utilization of a Deep Learning Algorithm for Microscope-Based Fatty Vacuole Quantification in a Fatty Liver Model in Mice.

Abstract: Quantification of fatty vacuoles in the liver, with differentiation from lumina of liver blood vessels and bile ducts, is an example where the traditional semiquantitative pathology assessment can be enhanced with artificial intelligence (AI) algorithms. Using glass slides of mice liver as a model for nonalcoholic fatty liver disease, a deep learning AI algorithm was developed. This algorithm uses a segmentation framework for vacuole quantification and can be deployed to analyze live histopathology fields during the microscope-based pathology assessment. We compared the manual semiquantitative microscope-based assessment with the quantitative output of the deep learning algorithm. The deep learning algorithm was able to recognize and quantify the percent of fatty vacuoles, exhibiting a strong and significant correlation (r = 0.87, P < .001) between the semiquantitative and quantitative assessment methods. The use of deep learning algorithms for difficult quantifications within the microscope-based pathology assessment can help improve outputs of toxicologic pathology workflows.

Essential References for Structural Analysis of the Peripheral Nervous System for Pathologists and Toxicologists.

Abstract: Toxicologic neuropathology for the peripheral nervous system (PNS) is a vital but often underappreciated element of basic translational research and safety assessment. Evaluation of the PNS may be ...

Proliferative and Nonproliferative Lesions of the Rat and Mouse Central and Peripheral Nervous Systems: New and Revised INHAND Terms.

Abstract: Harmonization of diagnostic terminology used during the histopathologic analysis of rodent tissue sections from nonclinical toxicity studies will improve the consistency of data sets produced by laboratories located around the world. The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a cooperative enterprise of 4 major societies of toxicologic pathology to develop a globally accepted standard vocabulary for proliferative and nonproliferative lesions in rodents. A prior manuscript (Toxicol Pathol 2012;40[4 Suppl]:87S-157S) defined multiple diagnostic terms for toxicant-induced lesions, common spontaneous and age-related changes, and principal confounding artifacts in the rat and mouse central nervous system (CNS) and peripheral nervous system (PNS). The current article defines 9 new diagnostic terms and updates 2 previous terms for findings in the rodent CNS and PNS, the need for which has become evident in the years since the publication of the initial INHAND nomenclature for findings in rodent neural tissues. The nomenclature presented in this document is also available electronically on the Internet at the goRENI website (http://www.goreni.org/).

Carcinogenicity Assessment of Daprodustat (GSK1278863), a Hypoxia-Inducible Factor (HIF)-Prolyl Hydroxylase Inhibitor:

Abstract: Daprodustat (GSK1278863) is a hypoxia-inducible factor (HIF)-prolyl hydroxylase (PHD) inhibitor in development for treatment of anemia of chronic kidney disease. Daprodustat's biological activity simulates components of the natural response to hypoxia; inhibition of PHDs results in HIF stabilization and modulation of HIF-controlled gene products, including erythropoietin. The carcinogenic potential of daprodustat was evaluated in 2-year carcinogenicity studies in Sprague-Dawley rats and CD-1 mice, where once-daily doses were administered. The mouse study also included evaluation of daprodustat's 3 major circulating human metabolites. There were no neoplastic findings that were considered treatment related in either study. Exaggerated pharmacology resulted in significantly increased red cell mass and subsequent multiorgan congestion and secondary non-neoplastic effects in both species, similar to those observed in chronic toxicity studies. In rats, these included aortic thrombosis and an exacerbation of spontaneous rodent cardiomyopathy, which contributed to a statistically significant decrease in survival in high-dose males (group terminated in week 94). Survival was not impacted in mice at any dose. Systemic exposures (area under the plasma concentration-time curve) to daprodustat at the high doses in rats and mice exceed predicted maximal human clinical exposure by ≥143-fold. These results suggest that daprodustat and metabolites do not pose a carcinogenic risk at clinical doses.

Scientific and Regulatory Policy Committee Points to Consider*: Approaches to the Conduct and Interpretation of Vaccine Safety Studies for Clinical and Anatomic Pathologists.

Abstract: The design and execution of toxicology studies supporting vaccine development have some unique considerations relative to those supporting traditional small molecules and biologics. A working group of the Society of Toxicologic Pathology Scientific and Regulatory Policy Committee conducted a review of the scientific, technical, and regulatory considerations for veterinary pathologists and toxicologists related to the design and evaluation of regulatory toxicology studies supporting vaccine clinical trials. Much of the information in this document focuses on the development of prophylactic vaccines for infectious agents. Many of these considerations also apply to therapeutic vaccine development (such as vaccines directed against cancer epitopes); important differences will be identified in various sections as appropriate. The topics addressed in this Points to Consider article include regulatory guidelines for nonclinical vaccine studies, study design (including species selection), technical considerations in dosing and injection site collection, study end point evaluation, and data interpretation. The intent of this publication is to share learnings related to nonclinical studies to support vaccine development to help others as they move into this therapeutic area. [Box: see text].

Recent Advancements and Applications of Human Immune System Mice in Preclinical Immuno-Oncology.

Abstract: Significant advances in immunotherapies have resulted in the increasing need of predictive preclinical models to improve immunotherapeutic drug development, treatment combination, and to prevent or...

Common Structural Lesions of the Peripheral Nervous System.

Abstract: This review illustrates common lesions of peripheral nerve myelinated fibers that occur in toxic neuropathy. These distinctive structural changes help to define the site of toxicant activity and thus predict the course of neurotoxic disease and recovery. Neuronopathy is the condition where the primary injury is directed to the neuronal cell body giving rise to a peripheral nerve axon. Axonopathy occurs when the axon is the primary target, and myelinopathy develops where the Schwann cell and/or myelin sheath is the primary target; these conditions can be discriminated early during the course of nerve fiber degeneration, but reciprocal influences between axon and myelin result in degeneration of both structures late in the disease.

Autophagy of Sensory Neurons in the Trigeminal and Dorsal Root Ganglia of Cynomolgus Monkeys (Macaca fascicularis).

Abstract: Although necrosis and apoptosis are uncommon, autophagy of sensory neurons (ASN) in trigeminal and dorsal root ganglia is a very common, spontaneous finding in cynomolgus monkeys (Macaca fascicularis). Data from one author's (Butt) laboratory showed 12 of 22 studies (year range 2017 to 2019) that included the evaluation of sensory ganglia from cynomolgus monkeys had at least one control animal with ASN. Autophagy of sensory neurons is characterized by a distinct cell membrane, cytoplasm filled with autolysosomes, disintegrated nuclear membrane, and/or globules of degraded chromatin. Since these changes are consistent with autophagy and indicate an irreversible state, a diagnosis of autophagy is preferred instead of necrosis or degeneration. Sensory ganglia are not commonly evaluated in nonclinical toxicology investigations so many pathologists may be unaware of this common change. Especially due to the typically small group size of monkey studies, the observation of this change in sensory ganglia may lead to a faulty interpretation that this change is due to the test article. This article describes the light microscopic and ultrastructural characteristics of neuronal autophagy in trigeminal and dorsal root ganglia and provides historical control data of the incidence of this change in cynomolgus monkeys.

Sampling and Evaluating the Peripheral Nervous System.

Abstract: Many preclinical investigations limit the evaluation of the peripheral nervous system (PNS) to paraffin-embedded sections/hematoxylin and eosin-stained sections of the sciatic nerve. This limitation ignores several key mechanisms of toxicity and anatomic differences that may interfere with an accurate assessment of test article effects on the neurons/neurites peripheral to the brain and spinal cord. Ganglion neurons may be exposed to higher concentrations of the test article as compared to neurons in the brain or spinal cord due to differences in capillary permeability. Many peripheral neuropathies are length-dependent, meaning distal nerves may show morphological changes before they are evident in the mid-sciatic nerve. Paraffin-embedded nerves are not optimal to assess myelin changes, notably those leading to demyelination. Differentiating between axonal or myelin degeneration may not be possible from the examination of paraffin-embedded sections. A sampling strategy more consistent with known mechanisms of toxicity, atraumatic harvest of tissues, optimized fixation, and the use of resin and paraffin-embedded sections will greatly enhance the pathologist's ability to observe and characterize effects in the PNS.

The Science and Art of Nerve Fiber Teasing for Myelinated Nerves: Methodology and Interpretation.

Abstract: Nerve fiber teasing is a sensitive technique utilized in diagnostic neuropathology practice, laboratory research, and animal toxicity studies for characterizing changes in single myelinated nerve fibers over extended distances. In animal toxicity studies, a nerve portion (approximately 10 mm in length) is stained with Sudan black for 24 to 48 hours and then transferred into a drop of viscous medium (eg, glycerin) mounted on an adhesive-coated glass slide, positioning it such that the proximodistal orientation is known. Individual fibers are removed using fine forceps while the sample is viewed under a stereomicroscope. In general, lesions can be identified during teasing, but more detailed characterization and photodocumentation is undertaken once nerve fibers have been dried and coverslipped. Nerve fiber teasing is particularly useful for distinguishing early stages of axonal degeneration (which presents as ovoid fiber fragments in the midinternodal region) from segmental demyelination (which presents as loss of original myelin segments and their replacement by thinner, shorter segments in the absence of axonal damage). The slow, laborious nature of nerve fiber teasing dictates that the technique will be employed on a few samples as an auxiliary method to better define the pathogenesis of nerve lesions first identified by conventional histopathologic assessment.

Evaluation of 10 Urinary Biomarkers for Renal Safety With 5 Nephrotoxicants in Nonhuman Primates.

Abstract: To date, there has been very little published data evaluating the performance of novel urinary kidney biomarkers in nonhuman primates (NHPs). To assess the biomarker performance and characterize the corresponding histomorphologic patterns of tubular renal injury in the NHP, several studies were conducted using mechanistically diverse nephrotoxicants including cefpirome, cisplatin, naproxen, cyclosporine, and a combination of gentamicin with everninomicin. An evaluation of 10 urinary biomarkers (albumin, clusterin, cystatin C, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, liver-type fatty acid-binding protein, N-acetyl-β-D-glucosaminidase, osteopontin, retinol binding protein 4 and total protein) was performed on urine collected from these studies. Each of these 5 treatments resulted in kidney proximal tubule injury of various severities. Histomorphologic features observed following treatment were generally consistent with analogous drug-induced changes in humans described in the literature. Most of the analyzed biomarkers were able to detect the injury earlier and with greater sensitivity than blood urea nitrogen and serum creatinine. Across all studies, KIM-1 and clusterin showed the highest overall performance. Differences in the patterns of biomarker responsiveness were noted among certain studies that may be informing tubular injury severity and recovery potential, underlying histopathologic processes, and prognosis. These findings demonstrate the utility of urinary kidney translational safety biomarkers in NHPs and provide additional supporting evidence for translating these biomarkers for use in clinical trial settings to further ensure patient safety.

Ovarian Toxicity Assessment in Histopathological Images Using Deep Learning

Abstract: As ovarian toxicity is often a safety concern for cancer therapeutics, identification of ovarian pathology is important in early stages of preclinical drug development, particularly when the intended patient population include women of child-bearing potential. Microscopic evaluation by pathologists of hematoxylin and eosin (H&E)-stained tissues is the current gold standard for the assessment of organs in toxicity studies. However, digital pathology and advanced image analysis are being explored with greater frequency and broader applicability to tissue evaluations in toxicologic pathology. Our objective in this work was to develop an automated method that rapidly enumerates rat ovarian corpora lutea on standard H&E-stained slides with comparable accuracy to the gold standard assessment by a pathologist. Herein, we describe an algorithm generated by a deep learning network and tested on 5 rat toxicity studies, which included studies that both had and had not previously been diagnosed with effects on number of ovarian corpora lutea. Our algorithm could not only enumerate corpora lutea accurately in all studies but also revealed distinct trends for studies with and without reproductive toxicity. Our method could be a widely applied tool to aid analysis in general toxicity studies.

Neuroprotein Targets of γ-Diketone Metabolites of Aliphatic and Aromatic Solvents That Induce Central–Peripheral Axonopathy:

Abstract: Peripheral neuropathy associated with chronic occupational and deliberate overexposure to neurotoxic organic solvents results from axonal degeneration in the central and peripheral nervous system. Human and experimental studies show that axonopathy is triggered by the action of neuroprotein-reactive γ-diketone metabolites formed from exposure to certain aliphatic solvents (n-hexane, 2-hexanone) and aromatic compounds (1,2-diethylbenzene, 1,2-4-triethylbenzene, 6-acetyl-1,1,4,4-tetramethyl-7-ethyl-1,2,3,4-tetralin). Neuroprotein susceptibility is related primarily to their differential content of lysine, the ∊-amino group of which is targeted by γ-diketones. Specific neuroprotein targets have been identified, and the sequence of molecular mechanisms leading to axonal pathology has been illuminated. While occupational n-hexane neuropathy continues to be reported, lessons learned from its experimental study may have relevance to other causes of peripheral neuropathy, including those associated with aging and diabetes mellitus.

Effects of Delgocitinib Ointment 0.5% on the Normal Mouse Skin and Epidermal Tight Junction Proteins in Comparison With Topical Corticosteroids.

Abstract: Delgocitinib ointment 0.5% is the world's first topical Janus kinase inhibitor product and was approved for treatment of atopic dermatitis (AD) in Japan. Although topical corticosteroids (TCSs) have been the mainstay of pharmacotherapy in AD over the past decades, long-term use of TCSs causes skin atrophy and alteration of the epidermal tight junction (TJ) leading to epidermal barrier dysfunction. In this study, delgocitinib ointment 0.5% or representative TCSs of different potencies were applied dermally once daily to the ear pinna of normal ICR mice for 14 days, and ear pinna thickness, histopathology, and immunohistochemistry for epidermal TJ proteins claudin-1 and -4 were evaluated. All the TCSs caused decreases in ear pinna thickness with epidermal thinning, sebaceous gland atrophy, and atrophy/decreased number of the subcutaneous adipocytes and decreased immunohistochemical staining intensity for epidermal claudins. In contrast, delgocitinib ointment 0.5% did not cause any of those changes. In conclusion, once daily topical delgocitinib ointment 0.5% for 14 days did not cause skin atrophy or decreased immunohistochemical staining of epidermal claudins, which are common safety concerns associated with TCSs. These characteristics suggest that delgocitinib ointment 0.5% has an improved safety profile over currently available TCS therapies particular for the long-term AD treatment.

Methods Optimization for Routine Sciatic Nerve Processing in General Toxicity Studies

Abstract: Recent "best practice" recommendations for peripheral nervous system sampling and processing provide guidance regarding nerve preparation for animal toxicity studies. This study explored the impact of delayed fixation, type of fixative, processing cycle times, starting ethanol concentration, and water bath temperature to improve nerve preservation in routinely prepared (paraffin-embedded, hematoxylin and eosin [H&E]-stained) sections. Sciatic nerves from adult Wistar rats (diameter, 1.04 ± 0.1 mm) and young domestic pigs (diameter 5.9 ± 1.2 mm) fixed at necropsy ("0" hours) or 3, 6, 12, or 24 hours after death were immersed in neutral-buffered 10% formalin containing 1.2% methanol (NBF) or methanol-free 4% formaldehyde (MFF) at room temperature. After fixation for 24 hours (rat) or 48 hours (pig), specimens were processed into paraffin, and ∼5-μm-thick sections were flattened on water baths set at 35°C, 40°C, or 45°C before H&E staining. Large-diameter nerves (pig) required longer processing cycles to ensure sufficient paraffin infiltration. For both small-diameter (rat) and large-diameter nerves, structural integrity was optimal if fixation by NBF or MFF occurred within 3 hours and the initial ethanol concentration for tissue processing was lowered to 50%. At all time points, structural preservation of nerve fibers was acceptable using NBF but was better with MFF. Use of a water bath at 35°C reduced processing-related nerve fiber separation within sections.

Urinary Kidney Biomarker Panel Detects Preclinical Antisense Oligonucleotide-Induced Tubular Toxicity.

Abstract: Sensitive kidney safety assessment is important for successful drug development in both preclinical and clinical stages. The Food and Drug Administration recently qualified a composite measure of 6 urine creatinine-normalized biomarkers, such as clusterin, cystatin C, kidney injury molecule 1 (KIM-1), N-acetyl-β-d-glucosaminidase, neutrophil gelatinase-associated lipocalin (NGAL), and osteopontin, for monitoring kidney toxicity in early clinical trials. The qualification was based on small molecule drugs in humans, and the full panel has not been assessed in other species or for other drug modalities. This study evaluated the effects on these biomarkers for a constrained ethyl antisense oligonucleotide (tool ASO) with demonstrated kidney toxicity in mice compared to a control ASO of the same chemistry. Dosing 50 mg/kg of the tool ASO resulted in mild proximal tubular pathology and elevations in KIM-1, clusterin, NGAL, and cystatin C. A lower dose resulted in milder histopathology and lower biomarker increases. Unexpectedly, the control ASO induced mild elevations in KIM-1, NGAL, and cystatin C, despite the lack of pathology. Both KIM-1 and clusterin were most closely associated with kidney pathology and increased with the severity of injury. Altogether, our data suggest that a biomarker panel is a sensitive tool for the detection of preclinical ASO-induced kidney pathology.

Use of Nerve Conduction Assessments to Evaluate Drug-Induced Peripheral Neuropathy in Nonclinical Species-A Brief Review

Abstract: The peripheral nervous system (PNS) is subject to a wide range of structural and functional insults including direct damage to axons, loss of myelin, and progressive deficits in saltatory conduction. Drugs that damage the PNS often result in neuropathies that impact the structure and function of targeted nerves. In most cases, both sensory and motor neurons are affected with damage initially evident in the distal extremities. Drug-induced neuropathies are potentially reversible following cessation of treatment, but early stages of neuropathy can be subclinical and asymptomatic making diagnosis difficult. Nerve biopsy is highly validated and provides definitive evidence of nerve injury and corresponding severity; however, it is limited in some respects and electrophysiological measures can complement histopathological assessments and provide a functional measure of potential toxicity. In a drug development setting, nerve conduction assessments are valuable to monitor nerve function longitudinally if nerve damage is suspected or confirmed, and importantly, can be used to monitor progression and/or recovery of a drug-induced neuropathy. This review will summarize the methodology used in nerve conduction assessments as well as discuss data interpretation and considerations for use in nonclinical species. Finally, the use of nerve conduction assessments in nonclinical drug development is discussed.

Case Report: Canine Strain– and Study Condition–Dependent Formation of Renaut Bodies in Sciatic Nerves of Beagle Dogs:

Abstract: Two beagle dog strains were used in a 14-day intrathecal infusion study for a small molecule test article. A moderate number of Renaut bodies (RBs) were observed in the sciatic nerves of control and test article-treated adult animals as early as 1 day after test article infusion (ie, 5 days after catheter implantation in the lumbar cistern). In most cases, the sciatic nerve was affected unilaterally, apparently in association with extended lateral recumbency on one side. The lighter beagle strain (Marshall), and especially the females (which weighed less than age-matched Marshall males), developed more RBs. In contrast, neither females nor males of the larger strain (Harlan) developed any nerve lesions. These data support the hypothesis that RBs develop following mechanical stress to sciatic nerves, suggest that this change may develop fairly quickly following an insult, and demonstrate that different dog strains exhibit strain-specific nerve changes.

Stereology of the Peripheral Nervous System.

Abstract: Qualitative histopathology has been the gold standard for evaluation of morphological tissue changes in all organ systems, including the peripheral nervous system. However, the human eye is not sensitive enough to detect small changes in quantity or size. Peripheral nervous system toxicity can manifest as subtle changes in neuron size, neuron number, axon size, number of myelinated or unmyelinated axons, or number of nerve fibers. Detection of these changes may be beyond the sensitivity of the human eye alone, necessitating quantitative approaches in some cases. Although 2-dimensional (2D) histomorphometry can provide additional information and is more sensitive than qualitative evaluation alone, the results are not always representative of the entire tissue and assumptions about the tissue can lead to bias, or inaccuracies, in the data. Design-based stereology provides 3D estimates of number, volume, surface area, or length, and stereological principles can be applied to peripheral nervous system tissues to obtain accurate and precise estimates, such as neuron number and size, axon number, and total intraepidermal nerve fiber length. This review describes practical stereological approaches to 3 compartments of the peripheral nervous system: ganglia, peripheral nerves, and intraepidermal nerve fibers.

Local Tolerance and Biodegradability of a Novel Artificial Dura Mater Graft Following Implantation Onto a Dural Defect in Rabbits

Abstract: Dura mater defects are a common problem following neurosurgery. Dural grafts are used to repair these defects; among them are biodegradable polymeric synthetic grafts. ArtiFascia is a novel synthetic and fibrous Dural graft, composed of poly(l-lactic-co-caprolactone acid) (PLCL) and poly(d-lactic-co-caprolactone acid). In this study, the biodegradability and local tolerance of ArtiFascia was evaluated in rabbits and compared with a bovine collagen matrix as a reference control. ArtiFascia implantation resulted in the formation of neo-dura at the site of implantation and recovery of the dural damage and the calvaria bone above. The implanted graft was completely absorbed after 12 months and the remaining macrophages were morphologically consistent with the anti-inflammatory M2-like phenotype, which contributes to tissue healing and are not pro-inflammatory. The site of the drilled skull bone had a continuous smooth surface, without exuberant tissue or inflammation and a newly formed trabecular bone formation indicated the healing process of the bone. These results support the local tolerability and biodegradability of ArtiFascia when used as a dural graft in rabbits. This study suggests that PLCL-based grafts including ArtiFascia are safe and effective to repair Rabbit Dura.