Comparison of Renal Amyloid and Hyaline Glomerulopathy in B6C3F1 Mice: An NTP Retrospective Study

Research-Relevant Conditions and Pathology of Laboratory Mice, Rats, Gerbils, Guinea Pigs, Hamsters, Naked Mole Rats, and Rabbits

Animals are valuable resources in biomedical research in investigations of biological processes, disease pathogenesis, therapeutic interventions, safety, toxicity, and carcinogenicity. Interpretation of data from animals requires knowledge not only of the processes or diseases (pathophysiology) under study but also recognition of spontaneous conditions and background lesions (pathology) that can influence or confound the study results. Species, strain/stock, sex, age, anatomy, physiology, spontaneous diseases (noninfectious and infectious), and neoplasia impact experimental results and interpretation as well as animal welfare. This review and the references selected aim to provide a pathology resource for researchers, pathologists, and veterinary personnel who strive to achieve research rigor and validity and must understand the spectrum of "normal" and expected conditions to accurately identify research-relevant experimental phenotypes as well as unusual illness, pathology, or other conditions that can compromise studies involving laboratory mice, rats, gerbils, guinea pigs, hamsters, naked mole rats, and rabbits.

Spontaneous hyaline glomerulopathy in a young Slc:ICR mouse

Hyaline glomerulopathy is a type of glomerular lesion that occurs in aging mice. Spontaneous hyaline glomerulopathy is rare in young mice. Here, we report spontaneous hyaline glomerulopathy in a young adult (15-week-old) ICR mouse. Necropsy revealed discoloration and roughness of the kidney surface. Microscopically, diffuse glomerular lesions were prominent. Amorphous, eosinophilic materials were deposited globally in the glomeruli. The mesangial region was expanded; however, the mesangial cells showed no proliferation. Thickening of the Bowman’s capsule with proliferation of parietal epithelial cells was observed. Glomerular deposits were strongly positive for anti-IgM, anti-IgG, and periodic acid-Schiff stain and were stained red by Masson’s trichrome stain. The deposits were negative for anti C3 and stained negatively with Congo red stain. Periodic acid methenamine silver and electron microscopy revealed glomerular deposits limited to intraglomerular capillaries. Based on the histological features, we diagnosed this lesion as hyaline glomerulopathy. This case could improve our understanding of spontaneous lesions in toxicological and pharmacological studies.

Pathology of Diseases of Geriatric Exotic Mammals

The review covers select disease conditions most frequently described in aging rodents (rats, mice, hamsters, guinea pigs), rabbits, and ferrets. The conditions are categorized by general organ systems, infectious diseases, and neoplasms. Two data systems, the Veterinary Medical Teaching Hospital and Comparative Pathology Laboratory at the University of California, Davis and Zoo/Exotic Pathology Service, Citrus Heights, California were used in the determining disease conditions to describe.

FEMA GRAS assessment of natural flavor complexes: Mint, buchu, dill and caraway derived flavoring ingredients

In 2015, the Expert Panel of the Flavor and Extract Manufacturers Association (FEMA) initiated a re-evaluation of the safety of over 250 natural flavor complexes (NFCs) used as flavor ingredients. NFC flavor materials include a variety of essential oils and botanical extracts. The re-evaluation of NFCs is conducted based on a constituent-based procedure outlined in 2005 and updated in 2018 that evaluates the safety of NFCs for their intended use as flavor ingredients. This procedure is applied in the re-evaluation of the generally recognized as safe (GRAS) status of NFCs with constituent profiles that are dominated by alicyclic ketones such as menthone and carvone, secondary alcohols such as menthol and carveol, and related compounds. The FEMA Expert Panel affirmed the GRAS status of Peppermint Oil (FEMA 2848), Spearmint Oil (FEMA 3032), Spearmint Extract (FEMA 3031), Cornmint Oil (FEMA 4219), Erospicata Oil (FEMA 4777), Curly Mint Oil (FEMA 4778), Pennyroyal Oil (FEMA 2839), Buchu Leaves Oil (FEMA 2169), Caraway Oil (FEMA 2238) and Dill Oil (FEMA 2383) and determined FEMA GRAS status for Buchu Leaves Extract (FEMA 4923), Peppermint Oil, Terpeneless (FEMA 4924) and Spearmint Oil, Terpeneless (FEMA 4925).

Drug-induced Glomerulonephritis: The Spectre of Biotherapeutic and Antisense Oligonucleotide Immune Activation in the Kidney

Prevalence of immune-mediated glomerulonephritis has increased in preclinical toxicity studies, with more frequent use of biotherapeutic agents (especially antigenic humanized molecules) and antisense oligonucleotide (ASO) therapies. Immune complex disease affects a small number of study monkeys, often correlates with antidrug antibody (ADA) titers, and occurs at a dose that favors immune complex formation or impedes clearance. While preclinical glomerulonephritis often fails to correlate with evidence of glomerular or vascular injury in human clinical trials and is not considered predictive, additional animal investigative immunohistochemical work may be performed to substantiate evidence for immune complex pathogenesis. While ADA is most commonly encountered as a predisposing factor with biotherapeutic agents, complement activation may occur without circulating complexes, and other mechanisms of non-ADA immune-mediated glomerulonephritis have been observed including nonendogenous immune aggregates and immunoregulatory pharmacology. Although glomerulonephritis associated with oligonucleotide therapies has been noted occasionally in preclinical studies and more rarely with human patients, pathophysiologic mechanisms involved appear to be different between species and preclinical cases are not considered predictive for humans. ADA is not involved in oligonucleotide-associated cases, and complement fixation plays a more important role in monkeys. Recent screening of ASOs for proinflammatory activity appears to have decreased glomerulonephritis incidence preclinically.