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Lung: Pulmonary acariasis. Gross findings show small yellow or pale green nodules in the lungs. Microscopically, characteristic findings such as dilatation of the bronchial or bronchiolar lumen, thickening of the bronchial wall and inflammatory cell infiltration around the bronchus, lymphoid hyperplasia and brown pigment deposition strongly suggest pulmonary acariasis even if there is no acarid.
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The purpose of our publication is to widely communicate pictures of spontaneous findings occurring in cynomolgus monkeys. Focal lymphoplasmacytic infiltration is commonly seen in the general organs. The frequency and severity of these lesions may be influenced by the administration of drugs with an effect on the immune system. Lymphoplasmacytic inf...
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... fascicularis), as a test system, since, due to their close phylogenetic relationship with humans, primates are often the only relevant animal species for assessing the safety of targeted drugs [1,2]. However, in some cases, clinically healthy monkeys have some background pathology changes [3,4] which develop either before administration of the drug or during the experiment and, in turn, when identified in a histological examination, may affect the accuracy of the results of an evaluation of toxicity studies. The correct interpretation of pathomorphological abnormalities is of utmost importance, since, in some cases, it can affect the general conclusion on a safety study of a drug and the characteristics of its toxicological profile. ...
... Samples of the studied organs were fixed in a 10% neutral buffered formalin, dehydrated through a series of alcohol solutions with increasing concentrations and cytosols, and embedded in paraffin HISTAMIX (BioVitrum, Russia). [3][4] μm sections prepared on a Rotary Microtome Microm HM355S (Thermo Scientific) were stained with eosin and hematoxylin using a standard technique, as well as Perls's staining was used to detect hemosiderin. We also used polarizing microscopy to confirm the presence of exogenous pigment in the lungs. ...
... The detected changes in the myocardium were not related to the age and place of origin of primates. The detected small infiltrates and small foci of fibrosis are also described by some authors [4]. Predominant background lesions in the kidneys were minimal interstitial lymphoplasmacytic infiltrate, located mainly in the cortex (Figure 3), less often in the medulla, in 26.4% of the study animals. ...
Histological samples of organs obtained from 72 (35 male and 37 female) cynomolgus monkeys (M. fascicularis) from negative control groups in 12 toxicological studies were analyzed retrospectively. The most common processes where focal accumulations of exogenous pigment were found in 76.4% of animals in the lungs, non-atrophic chronic gastritis, which was observed in 37.4% of animals, focal chronic quiescent colitis was noted in 36.1% of cases, infiltrate in the liver were observed in 33.3% of animals, focal chronic quiescent gastritis was identified in 30.5% of animals, lymphoplasmacytic infiltrates in the kidneys were found in 26.4% of animals. Identification and accumulation of information on background pathology findings in primates from control groups are essential since these data allow differentiating spontaneous pathology from abnormalities associated with administration of a drug test, to correctly interpret the results of toxicology studies.
... It is unknown whether these very minor changes in the WEVEE VRP-vaccinated NHPs were related to the virus exposure or were incidental findings. Perivascular inflammatory cell infiltrates have been reported to occur rarely as incidental findings in cynomolgus macaques [13,14]. Lymphoid organs (spleen, tonsils, or lymph nodes) of all control and vaccinated macaques had lymphoid hyperplasia, attributed to immune stimulation induced by aerosol exposure to the virus. ...
The purpose of this study was to evaluate the effects of the route of administration on the immunogenicity and efficacy of a combined western, eastern, and Venezuelan equine encephalitis (WEVEE) virus-like replicon particle (VRP) vaccine in cynomolgus macaques. The vaccine consisted of equal amounts of WEEV, EEEV, and VEEV VRPs. Thirty-three animals were randomly assigned to five treatment or control groups. Animals were vaccinated with two doses of WEVEE VRPs or the control 28 days apart. Blood was collected 28 days following primary vaccination and 21 days following boost vaccination for analysis of the immune response to the WEVEE VRP vaccine. NHPs were challenged by aerosol 28 or 29 days following second vaccination with WEEV CBA87. Vaccination with two doses of WEVEE VRP was immunogenic and resulted in neutralizing antibody responses specific for VEEV, EEEV and WEEV. None of the vaccinated animals met euthanasia criteria following aerosol exposure to WEEV CBA87. However, one NHP control (total of 11 controls) met euthanasia criteria after infection with WEEV CBA87. Statistically significant differences in median fever hours were noted in control NHPs compared to vaccinated NHPs, providing a quantitative measure of infection and efficacy of the vaccine against a WEEV challenge. Alterations in lymphocytes, monocytes, and neutrophils were observed. Lymphopenia was observed in control NHPs.
... While both ZIKV RNA and infectious virus were frequently detected within the seminal vesicle, no significant microscopic lesions were noted in this tissue in ZIKV-inoculated animals. There was variably severe mineralization of secretory product; however, this was also present in control tissues and is a very common, clinically insignificant background lesion in the seminal vesicle of sexually mature macaques [25]. ...
... Epididymitis in primates has several documented etiologies, including sexually transmitted or ascending urinary bacterial or fungal infections, trauma/obstruction and, less commonly, viral infection as caused by orthorubulaviruses (mumps), adenoviruses, or enteroviruses [63]. Prostatic periglandular and/or perivascular lymphocytic infiltrates are common, clinically insignificant background findings in macaques, however, the presence of neutrophilic inflammation and necrotic debris, as seen here, are not [25]. As noted for epididymitis, ascending bacterial infection associated with recurrent urinary tract infection is the most frequently reported cause of prostatitis in humans [64]. ...
Zika virus (ZIKV) is unique among mosquito-borne flaviviruses in that it is also vertically and sexually transmitted by humans. The male reproductive tract is thought to be a ZIKV reservoir; however, the reported magnitude and duration of viral persistence in male genital tissues vary widely in humans and non-human primate models. ZIKV tissue and cellular tropism and potential effects on male fertility also remain unclear. The objective of this study was to resolve these questions by analyzing archived genital tissues from 51 ZIKV-inoculated male macaques and correlating data on plasma viral kinetics, tissue tropism, and ZIKV-induced pathological changes in the reproductive tract. We hypothesized that ZIKV would persist in the male macaque genital tract for longer than there was detectable viremia, where it would localize to germ and epithelial cells and associate with lesions. We detected ZIKV RNA and infectious virus in testis, epididymis, seminal vesicle, and prostate gland. In contrast to prepubertal males, sexually mature macaques were significantly more likely to harbor persistent ZIKV RNA or infectious virus somewhere in the genital tract, with detection as late as 60 days post-inoculation. ZIKV RNA localized primarily to testicular stem cells/sperm precursors and epithelial cells, including Sertoli cells, epididymal duct epithelium, and glandular epithelia of the seminal vesicle and prostate gland. ZIKV infection was associated with microscopic evidence of inflammation in the epididymis and prostate gland of sexually mature males, pathologies that were absent in uninfected controls, which could have significant effects on male fertility. The findings from this study increase our understanding of persistent ZIKV infection which can inform risk of sexual transmission during assisted reproductive therapies as well as potential impacts on male fertility.
... The most commonly used term or qualifier to describe the inflammatory infiltrates was by far "mononuclear" although other qualifiers, such as "lymphoplasmacytic" or "lymphocytic," were occasionally used, particularly in those organs with a propensity to developing lymphoid aggregates or follicles, such as the salivary glands, lacrimal glands, or the uvea of the eye. The nature and morphological presentation of mononuclear inflammatory cell infiltrates was as previously described 15,22,24,25 and consisted of interstitial accumulations of mainly lymphocytes and plasma cells in varying proportions, with occasional histiocytes, and associated with negligible or no evidence of injury to parenchymal tissues. The latter characteristic feature (absence of substantial tissue injury) was the key differentiating feature between inflammatory infiltrates and inflammation. ...
To investigate the influence of geographical origin, age, and sex on toxicologically relevant spontaneous histopathology findings in cynomolgus macaques ( Macaca fascicularis), we performed a comparative analysis of historical control data (HCD) from 13 test sites that included 3351 animals (1645 females and 1706 males) sourced from Mauritius, China, Vietnam, and Cambodia, aged from 2 to 9.5 years, and from 446 toxicology studies evaluated between 2016 and 2021. The most common findings were mononuclear infiltrates in the kidney, liver, brain, and lung, which showed highest incidences in Mauritian macaques, and heart, salivary glands, and gastrointestinal tract (GIT), which showed highest incidences of mononuclear infiltrates in mainland Asian macaques. Developmental and degenerative findings were more common in Mauritian macaques, while lymphoid hyperplasia and lung pigment showed higher incidences in Asian macaques. Various sex and age-related differences were also present. Despite origin-related differences, the similarities in the nature and distribution of background lesions indicate that macaques from all geographical regions are suitable for toxicity testing and show comparable lesion spectrum. However, in a toxicity study, it is strongly recommended to use animals from a single geographical origin and to follow published guidelines when using HCD to evaluate and interpretate commonly diagnosed spontaneous lesions.
... 14 Similar inclusions have also been described as a background finding in other species and are believed to be due to the uptake of plasma proteins, secondary to hemodynamic and hypoxic changes occurring at the time of euthanasia. [15][16][17][18] Decreased platelets and fibrinogen and increased PT and APTT and D-dimers suggested a consumptive coagulopathy, although no sinusoidal fibrin plugs were observed. The animals that were euthanized did not exhibit signs of shock, despite marked increases in liver enzymes and development of coagulopathy, suggesting that the coagulopathy was likely a secondary manifestation of liver tissue injury, with endothelial damage and release of tissue components activating the coagulation cascade. ...
Recombinant adeno-associated viruses (AAVs) have emerged as promising vectors for human gene therapy, but some variants have induced severe toxicity in Rhesus monkeys and piglets following high dose intravenous (IV) administration. To characterize biodistribution, transduction and toxicity amongst common preclinical species, an AAV9 neurotropic variant expressing the survival motor neuron-1 (SMN-1) transgene (AAV-PHP.B-CBh-SMN1) was administered by IV bolus injection to Wistar Han rats and cynomolgus monkeys at doses of 2x1013, 5x1013, or 1x1014 vg/kg. A dose-dependent degeneration/necrosis of neurons without clinical manifestations occurred in dorsal root ganglia (DRGs) and sympathetic thoracic ganglia in rats, while liver injury was not observed in rats. In monkeys, one male at 5x1013 vg/kg was found dead on Day 4. Clinical pathology data on Days 3 and/or 4 at all doses suggested liver dysfunction and coagulation disorders, which led to study termination. Histologic evaluation of the liver in monkeys showed hepatocyte degeneration and necrosis without inflammatory cell infiltrates or intravascular thrombi suggesting that hepatocyte injury is a direct effect of the vector following hepatocyte transduction. In situ hybridization (ISH) demonstrated a dose-dependent expression of SMN1 transgene mRNA in the cytoplasm and DNA in the nucleus of periportal to panlobular hepatocytes, while qPCR confirmed the dose-dependent presence of SMN1 transgene mRNA and DNA in monkeys. Monkeys produced a much greater amount of transgene mRNA compared with rats. In DRGs, neuronal degeneration/necrosis and accompanying findings were observed in monkeys as early as 4 days after test article administration. The present results show sensory neuron toxicity following IV delivery of AAV vectors at high doses with an early onset in Macaca fascicularis and after one month in rats, and suggest adding the autonomic system in the watch-list for preclinical and clinical studies. Our data also suggest that the rat may be useful for evaluating the potential DRG toxicity of AAV vectors, while acute hepatic toxicity associated with coagulation disorders appears to be highly species-dependent.
... Affected animals present weight loss, diarrhea and malabsorption. Common sites of amyloid deposition in NHP include spleen, lymph nodes, kidney, liver, pancreatic islets and lamina propria or submucosa of the small intestine; especially in aged macaques, often due to chronic enterocolitis or other inflammatory conditions [10][11][12] . Lymphoma 3 x * Terminology with diagnostic criteria and/or comments described below. ...
... • The epithelial lining is usually surrounded by a layer of fibrous connective tissue of varying thickness. • Squamous plaques can be found alone or near squamous cysts 6,11,[61][62][63] . ...
... Comments: Mononuclear cell infiltrates (lymphocytes, plasma cells, macrophages) are not uncommon in the pituitary in cynomolgus monkeys in toxicity studies. They are generally seen focally or multifocally in the pars intermedia or pars nervosa 11 . As for other locations in the body, their incidence and severity can be increased compared to controls after administration of immunostimulating compounds such as proinflammatory oligonucleotides 104 . ...
The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions Project (www.toxpath.org/inhand.asp) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in most tissues and organs from the nonhuman primate used in nonclinical safety studies. Some of the lesions are illustrated by color photomicrographs. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions as well as lesions induced by exposure to test materials. Relevant infectious and parasitic lesions are included as well. A widely accepted and utilized international harmonization of nomenclature for lesions in laboratory animals will provide a common language among regulatory and scientific research organizations in different countries and increase and enrich international exchanges of information among toxicologists and pathologists.
... A lengthy description covering all the potential background lesions in NHPs is beyond the intent of this review. We refer readers to the excellent extensive reviews on this topic, including: Simmons 2016, 9 Sato et al 2012, 10 Chamanza et al 2010, 11 Kaspareit et al 2006, 12 David et al 2009, 13 ...
... However, tamarins particularly have been informative in ulcerative colitis/colon cancer, 65 inflammatory bowel disease, 66 and Crohn's disease 67 studies. The cotton-top tamarin (S. oedipus) Cortical cell vacuolation 11 Pigment 11 Adrenohepatic fusion/adhesion 11 Accessory adrenocortical tissue 10 Nodular hyperplasia of cortical cells 10 Decreased lipid in cortical cells 10 Mineralization of corticomedullary junction 10 Inflammatory cell foci 10 Thyroid gland Ectopic thymus/salivary gland 11 Cystic/ultimobranchial cysts 11 Dilated/cystic follicles 10 Lymphocytic thyroiditis 10 Focal C-cell hyperplasia 10 Macrophage infiltration in follicle 10 Hydropic degeneration of follicle cells 10 Fatty infiltration 10 Parathyroid gland Ectopic thymus 11 Congenital cysts 11 Fatty infiltration 10 Increased oxyphil cells 10 Focal hypertrophy of chief cells 10 Inflammatory cell foci 10 Pituitary gland Inflammatory cell foci 11 Cysts 11 Focal anterior pituitary cell hypertrophy 10 Pancreas (endocrine) Hypertrophy, islets 10 Angiectasia in islets 10 Hemorrhage in islets 10 Fibrosis in islets 10 Amyloidosis in islets 10 ...
... However, tamarins particularly have been informative in ulcerative colitis/colon cancer, 65 inflammatory bowel disease, 66 and Crohn's disease 67 studies. The cotton-top tamarin (S. oedipus) Cortical cell vacuolation 11 Pigment 11 Adrenohepatic fusion/adhesion 11 Accessory adrenocortical tissue 10 Nodular hyperplasia of cortical cells 10 Decreased lipid in cortical cells 10 Mineralization of corticomedullary junction 10 Inflammatory cell foci 10 Thyroid gland Ectopic thymus/salivary gland 11 Cystic/ultimobranchial cysts 11 Dilated/cystic follicles 10 Lymphocytic thyroiditis 10 Focal C-cell hyperplasia 10 Macrophage infiltration in follicle 10 Hydropic degeneration of follicle cells 10 Fatty infiltration 10 Parathyroid gland Ectopic thymus 11 Congenital cysts 11 Fatty infiltration 10 Increased oxyphil cells 10 Focal hypertrophy of chief cells 10 Inflammatory cell foci 10 Pituitary gland Inflammatory cell foci 11 Cysts 11 Focal anterior pituitary cell hypertrophy 10 Pancreas (endocrine) Hypertrophy, islets 10 Angiectasia in islets 10 Hemorrhage in islets 10 Fibrosis in islets 10 Amyloidosis in islets 10 ...
Biomedical research involving animal models continues to provide important insights into disease pathogenesis and treatment of diseases that impact human health. In particular, nonhuman primates (NHPs) have been used extensively in translational research due to their phylogenetic proximity to humans and similarities to disease pathogenesis and treatment responses as assessed in clinical trials. Microscopic changes in tissues remain a significant endpoint in studies involving these models. Spontaneous, expected (ie, incidental or background) histopathologic changes are commonly encountered and influenced by species, genetic variations, age, and geographical origin of animals, including exposure to infectious or parasitic agents. Often, the background findings confound study-related changes, because numbers of NHPs used in research are limited by animal welfare and other considerations. Moreover, background findings in NHPs can be exacerbated by experimental conditions such as treatment with xenobiotics (eg, infectious morphological changes related to immunosuppressive therapy). This review and summary of research-relevant conditions and pathology in rhesus and cynomolgus macaques, baboons, African green monkeys, common marmosets, tamarins, and squirrel and owl monkeys aims to improve the interpretation and validity of NHP studies.
... The lesions were morphologically similar to spontaneous arteritis reported in cynomolgus monkeys. 36,37 Cynomolgus monkeys have a high incidence of spontaneous IC formation compared to humans. 38,39 Immune complex disease was not observed in a 6-month study at the same doses. ...
Safety assessment of biological drugs has its challenges due to the multiple new different modalities, for example, antibody-drug conjugates, bispecifics, nanobodies, fusion proteins and advanced therapy medicinal products (ATMPs), their different pharmacokinetic and pharmacodynamic properties, and their ability to trigger immunogenicity and toxicity. In the public and in the pharmaceutical industry, there is a strong and general desire to reduce the number of animals used in research and development of drugs and in particular reducing the use of nonhuman primates. Important discussions and activities are ongoing investigating the smarter designs of early research and dose range finding studies, reuse of animals, and replacing animal experiments with in vitro studies. Other important challenges include absence of a relevant species and design of studies and developing genetically modified animals for special investigative toxicology studies. Then, the learnings and challenges from the development of the first ATMPs are available providing valuable insights in the development path for these new potentially transformative treatments. Finally, development of strategies for assessment of immunogenicity and prediction of translation of immunogenicity and associated findings to the clinic. On this, the eighth meeting for the European BioSafe members, these challenges served as the basis for the presentations and discussions during the meeting. This article serves as the workshop report reviewing the presentations and discussions at the meeting.
... Mononuclear cell infiltrates in the liver have been reported as a common background finding in NHPs. 37 We detected capsular and subcapsular fibrosis only in the third liver biopsy samples in all animals, although the fibrosis was not significant and may have been the result of previous liver biopsy procedures, similar to what we have observed in non-nuclease AAV vector-treated NHPs that were subjected to consecutive liver biopsies (L.W. and J.M.W., unpublished data). In summary, the AAV-delivered meganuclease resulted in transient expression of meganuclease in the liver and long-lasting editing effects without major safety concerns. ...
Gene disruption via programmable, sequence-specific nucleases represents a promising gene therapy strategy in which the reduction of specific protein levels provides a therapeutic benefit. Proprotein convertase subtilisin/kexin type 9 (PCSK9), an antagonist of the low-density lipoprotein (LDL) receptor, is a suitable target for nuclease-mediated gene disruption as an approach to treat hypercholesterolemia. We sought to determine the long-term durability and safety of PCSK9 knockdown in non-human primate (NHP) liver by adeno-associated virus (AAV)-delivered meganuclease following our initial report on the feasibility of this strategy. Six previously treated NHPs and additional NHPs administered AAV-meganuclease in combination with corticosteroid treatment or an alternative AAV serotype were monitored for a period of up to three years. The treated NHPs exhibited a sustained reduction in circulating PCSK9 and LDL-c through the course of the study concomitant with stable gene editing of the PCSK9 locus. Low frequency off-target editing remained stable and no obvious adverse changes in histopathology of the liver were detected. We demonstrate similar on-target nuclease activity in primary human hepatocytes using a chimeric liver-humanized mouse model. These studies demonstrate that targeted in vivo gene disruption exerts a lasting therapeutic effect and provide pivotal data for safety considerations which support clinical translation.
... There have been several published reports on neoplastic findings in untreated cynomolgus monkeys used in toxicity studies testing pharmaceutical candidates (Chamanza et al., -Gaillot et al., 2006;Ito et al., 1992;Johnson et al., 2018;Kozlosky et al., 2015;Sato et al., 2012;Shimoi et al., 1998). In these reports, neoplastic findings have been infrequent. ...
Two young cynomolgus macaques (Macaca fascicularis) given a small molecule kinase inhibitor (SCIO-120) via nasogastric intubation gavage, once-daily for 21 days at 400 mg/kg/day, developed an unusual epithelial proliferative process in the renal parenchyma. Morphological and immunohistochemical characterization of the lesions confirmed an invasive malignant epithelial neoplasm (carcinoma). A similar renal neoplasm was seen in a third macaque after a 14-day exposure to a second kinase inhibitor in the same chemical series (SCIO-974). Despite remarkably short latency periods, exposure to these kinase inhibitors was likely causally associated with the induction of the renal tumors, as renal carcinomas are exceedingly rare spontaneously in macaques. Both SCIO-120 and SCIO-974 were designed as potent TGFβR1 inhibitors (IC50s 37 nM and 39 nM, respectively). SCIO-120 and SCIO-974 inhibited additional kinases, most notably closely related ALK4 (IC50=34 nM and 20 nM, respectively), c-jun n-terminal kinase 3 (JNK3, IC50=10 nM and 20 nM, respectively), and Fms related tyrosine kinase 1 (29 nM and 76 nM, respectively). TGFβR1 has been specifically implicated in epithelial proliferative disorders, including neoplasia. Neither SCIO-120 nor SCIO-974 was genotoxic based on bacterial reverse mutation and/or clastogenicity screening assays. The rapid appearance of renal carcinomas in primates following short-term treatment with non-genotoxic kinase inhibitors is remarkable and suggests that the compounds had noteworthy tumor-enhancing effects, hypothetically linked to their TGFβR1 inhibition activity. These observations have implications for mechanisms of carcinogenesis and TGFβR1 biology.
