Histological variation of early stage atherosclerotic lesions in baboons after prolonged challenge with high-cholesterol, high-fat diet.

INTRODUCTION: The baboon is a well-characterized model of human early stage atherosclerosis. However, histological and morphological changes involved in atherogenesis in baboons are not known. Previously, we challenged baboons with a high-cholesterol, high-fat diet for two years and observed fatty streak and plaque lesions in iliac arteries (RCIA). METHODS: We evaluated histological and morphological changes of baboon arterial lesions and control arteries. In addition, we evaluated the vascular expression of CD68 and SMαA markers with progression of atherosclerosis. RESULTS: We observed changes that correlated with extent of atherosclerosis, including increased maximum intimal thickness. We demonstrated at molecular level the infiltration of smooth muscle cells and macrophages into the intimal layer. Further, we observed histological and morphological discordancy between the affected and adjacent areas of the same RCIA. CONCLUSION: Atherogenesis in baboons is accompanied by histological, morphological, and molecular changes, as in humans, providing insights to evaluate the mechanisms underlying early stage atherosclerosis in target tissues.

Cutaneous epitheliotropic lymphoma in a baboon (Papio spp.): A case report and a brief literature review.

Cutaneous epitheliotropic lymphoma (CEL) has not been reported in non-human primates. We report the first case of CEL in a 9-year-old baboon. The phenotype of the neoplastic cells in this baboon is similar to CEL in humans (CD3+, CD4+, CD8-) and different from dogs (CD3+, CD4-, CD8+).

Duodenal adipose tissue is associated with obesity in baboons (Papio sp): a novel site of ectopic fat deposition in non-human primates.

AIMS: Ectopic fat is a recognized contributor to insulin resistance and metabolic dysfunction, while the role of fat deposition inside intestinal wall tissue remains understudied. We undertook this study to directly quantify and localize intramural fat deposition in duodenal tissue and determine its association with adiposity. METHODS: Duodenal tissues were collected from aged (21.2 ± 1.3 years, 19.5 ± 3.1 kg, n = 39) female baboons (Papio sp.). Fasted blood was collected for metabolic profiling and abdominal circumference (AC) measurements were taken. Primary tissue samples were collected at the major duodenal papilla at necropsy: one full cross section was processed for hematoxylin and eosin staining and evaluated; a second full cross section was processed for direct chemical lipid analysis on which percentage duodenal fat content was calculated. RESULTS: Duodenal fat content obtained by direct tissue quantification showed considerable variability (11.95 ± 6.93%) and was correlated with AC (r = 0.60, p < 0.001), weight (r = 0.38, p = 0.02), leptin (r = 0.63, p < 0.001), adiponectin (r = - 0.32, p < 0.05), and triglyceride (r = 0.41, p = 0.01). The relationship between duodenal fat content and leptin remained after adjusting for body weight and abdominal circumference. Intramural adipocytes were found in duodenal sections from all animals and were localized to the submucosa. Consistent with the variation in tissue fat content, the submucosal adipocytes were non-uniformly distributed in clusters of varying size. Duodenal adipocytes were larger in obese vs. lean animals (106.9 vs. 66.7 µm2, p = 0.02). CONCLUSIONS: Fat accumulation inside the duodenal wall is strongly associated with adiposity and adiposity related circulating biomarkers in baboons. Duodenal tissue fat represents a novel and potentially metabolically active site of ectopic fat deposition.

Multiple endocrine neoplasia-like syndrome in 24 baboons (Papio spp.).

Multiple endocrine neoplasia (MEN) has not been reported in baboons, but this condition is well described in humans. An internal database was searched for all cases of concurrent endocrine hyperplasia and neoplasia in baboons. Twenty-four baboons (Papio spp.) with concurrent endocrine hyperplasia and neoplasia were identified. Twenty-one baboons had lesions in two endocrine organs, two baboons had lesions in three organs, and one baboon had lesions in four organs. Ten baboons aligned with the MEN1 classification; 14 baboons did not match any current human MEN classification. We report 24 cases of MEN-like syndrome in baboons. MEN1-like lesions accounted for nearly half (41%) of the affected animals. Genetic analysis of baboons with MEN-like syndrome could further elucidate the mechanisms of MEN and support the use of baboons as animal models for human MEN.

Coccidioidomycosis in Nonhuman Primates: Pathologic and Clinical Findings.

Coccidioidomycosis in nonhuman primates has been sporadically reported in the literature. This study describes 22 cases of coccidioidomycosis in nonhuman primates within an endemic region, and 79 cases of coccidioidomycosis from the veterinary literature are also reviewed. The 22 cases included baboons ( n = 10), macaques ( n = 9), and chimpanzees ( n = 3). The majority died or were euthanized following episodes of dyspnea, lethargy, or neurologic and locomotion abnormalities. The lungs were most frequently involved followed by the vertebral column and abdominal organs. Microscopic examination revealed granulomatous inflammation accompanied by fungal spherules variably undergoing endosporulation. Baboons represented a large number of cases presented here and had a unique presentation with lesions in bone or thoracic organs, but none had both intrathoracic and extrathoracic lesions. Although noted in 3 cases in the literature, cutaneous infections were not observed among the 22 contemporaneous cases. Similarly, subclinical infections were only rarely observed (2 cases). This case series and review of the literature illustrates that coccidioidomycosis in nonhuman primates reflects human disease with a varied spectrum of presentations from localized lesions to disseminated disease.

Diet-induced early-stage atherosclerosis in baboons: Lipoproteins, atherogenesis, and arterial compliance.

BACKGROUND: The purpose of this study was to determine whether dietary manipulation can reliably induce early-stage atherosclerosis and clinically relevant changes in vascular function in an established, well-characterized non-human primate model. METHODS: We fed 112 baboons a high-cholesterol, high-fat challenge diet for two years. We assayed circulating biomarkers of cardiovascular disease (CVD) risk, at 0, 7, and 104 weeks into the challenge; assessed arterial compliance noninvasively at 104 weeks; and measured atherosclerotic lesions in three major arteries at necropsy. RESULTS: We observed evidence of atherosclerosis in all but one baboon fed the two-year challenge diet. CVD risk biomarkers, the prevalence, size, and complexity of arterial lesions, plus consequent arterial stiffness, were increased in comparison with dietary control animals. CONCLUSIONS: Feeding baboons a high-cholesterol, high-fat diet for two years reliably induces atherosclerosis, with risk factor profiles, arterial lesions, and changes in vascular function also seen in humans.

Cytomegaloviral hypophysitis in a simian immunodeficiency virus-infected rhesus macaque (Macacca mulatta).

Rhesus macaques experimentally infected with Simian Immunodeficiency Virus (SIV) experience immunosuppression and often opportunistic infection. Among the most common opportunistic infections are rhesus cytomegalovirus (RhCMV), a ubiquitous betaherpesvirus that undergoes continuous low-level replication in immunocompetent monkeys. Upon SIV-mediated immunodeficiency, RhCMV reactivates and results in lesions in numerous organ systems including the nervous and reproductive systems. We report the first case of cytomegaloviral hypophysitis in a SIV-immunocompromised rhesus macaque.

Natural pathology of the captive chimpanzee (Pan troglodytes): A 35-year review.

We present the spontaneous pathological lesions identified as a result of necropsy or biopsy for 245 chimpanzees (Pan troglodytes) over a 35-year period. A review of the pathology database was performed for all diagnoses on chimpanzees from 1980 to 2014. All morphologic diagnoses, associated system, organ, etiology, and demographic information were reviewed and analyzed. Cardiomyopathy was the most frequent lesion observed followed by hemosiderosis, hyperplasia, nematodiasis, edema, and hemorrhage. The most frequently affected systems were the gastrointestinal, cardiovascular, urogenital, respiratory, and lymphatic/hematopoietic systems. The most common etiology was undetermined, followed by degenerative, physiologic, neoplastic, parasitic, and bacterial. Perinatal and infant animals were mostly affected by physiologic etiologies and chimpanzee-induced trauma. Bacterial and physiologic etiologies were more common in juvenile animals. Degenerative and physiologic (and neoplastic in geriatric animals) etiologies predominated in adult, middle aged, and geriatric chimpanzees.

Natural mortality and cause of death analysis of the captive chimpanzee (Pan troglodytes): A 35-year review.

We present the spontaneous causes of mortality for 137 chimpanzees (Pan troglodytes) over a 35-year period. A record review of the pathology database was performed and a primary cause of mortality was determined for each chimpanzee. The most common causes of mortality were as follows: cardiomyopathy (40% of all mortalities), stillbirth/abortion, acute myocardial necrosis, chimpanzee-induced trauma, amyloidosis, and pneumonia. Five morphologic diagnoses accounted for 61% of mortalities: cardiomyopathy, hemorrhage, acute myocardial necrosis, amyloidosis, and pneumonia. The most common etiologies were degenerative, undetermined, bacterial, traumatic, and neoplastic. The cardiovascular system was most frequently involved, followed by the gastrointestinal, respiratory, and multisystemic diseases. Degenerative diseases were the primary etiological cause of mortality of the adult captive chimpanzee population. Chimpanzee-induced trauma was the major etiological cause of mortality among the perinatal and infant population. This information should be a useful resource for veterinarians and researchers working with chimpanzees.

Spontaneous mediastinal myeloid sarcoma in a common marmoset (Callithrix jacchus) and review of the veterinary literature.

BACKGROUND: Myeloid sarcoma is a rare manifestation of myeloproliferative disorder defined as an extramedullary mass composed of myeloid precursor cells. A 9-month old, female, common marmoset (Callithrix jacchus) had increased respiratory effort. METHODS: A complete necropsy with histology and immunohistochemistry was performed. RESULTS: The thymus was replaced by a firm, gray-tan mass with a faint green tint, filling over 50% of the thoracic cavity. Sheets of granulocytes, lymphoid cells, nucleated erythrocytes, megakaryocytes, and hematopoietic precursors of indeterminate cell lineage replaced the thymus, perithymic connective tissue, mediastinal adipose tissues, epicardium, and much of the myocardium. The cells demonstrated diffuse strong cytoplasmic immunoreactivity for lysozyme, and strong, multifocal membranous immunoreactivity for CD117. CONCLUSION: We report the first case of a myeloid sarcoma in a common marmoset (C. jacchus), similar to reported human cases of mediastinal myeloid sarcoma, and present a review of myeloproliferative diseases from the veterinary literature.

Pauci-immune glomerulonephritis in a captive chimpanzee (Pan troglodytes), and a review of spontaneous cases in animals.

BACKGROUND: Crescentic glomeruli are the hallmark finding in rapidly progressive glomerulonephritis (RPGN) and are characterized by disruption and proliferation of the glomerular capsule and an influx of cells into Bowman's space. Pauci-immune-type RPGN is identified by a lack of immunoglobulins and immune complexes in the glomerular basement membrane. METHODS: Complete necropsy and histology were performed on the affected chimpanzee. Electron microscopy was performed on kidney sections. A search of the literature was performed to identify spontaneous RPGN in animals. RESULTS: We report a case of crescentic glomerulonephritis of the pauci-immune-type in a hepatitis C virus-infected 28-year-old male chimpanzee (Pan troglodytes) who was humanely euthanized for a cardiac-related decline in health. CONCLUSION: To our knowledge, this is the first report describing pauci-immune crescentic glomerulonephritis in a non-human primate.

An efficient model of human endometriosis by induced unopposed estrogenicity in baboons.

Endometriosis is a chronic estrogen-dependent disease that occurs in approximately 10% of reproductive age women. Baboons offer a clear benefit for studying the initiation and progression of endometriosis since baboon is very close to humans phylogenetically. Progestins are used in the treatment of endometriosis. The therapeutic window of progestins depends on the ratio of its affinity towards progesterone receptor agonism verses antagonism. The present study is to determine the role of pure antiprogestin in baboon endometriosis. We hypothesize that pure antiprogestin will induce unopposed estrogenicity and spontaneous endometriosis in baboons. The rate of endometrial invasion and attachment through modeled peritoneum in the presence and absence of progesterone and antiprogestin was evaluated in this study. A baboon model of endometriosis induced by unopposed estrogenicity using progesterone receptor antagonist (EC304) was used in this study. We observed EC304 has induced unopposed estrogenicity that deregulated proteins involved in attachment, invasion, cell growth, and steroid hormone receptors in this model. Our data suggest that depleting progesterone levels in the endometrium will increase estrogen hyper-responsiveness that leads to increased endometriotic lesion progression in the baboon (Papio anubis) model. This study reports a refined model of human endometriosis in baboons that could potentially be used to develop new diagnostic and therapeutic strategies for the benefit of women suffering from endometriosis.

Osteosarcoma in Baboons (Papio spp).

Bone neoplasms in baboons (Papio spp) are rare, with only one confirmed case of osteosarcoma previously described in the literature. Over a 12-y period, 6 baboons at a national primate research center presented with naturally occurring osteosarcoma; 3 lesions affected the appendicular skeleton, and the remaining 3 were in the head (skull and mandible). The 6 cases presented were identified in members of a large outdoor-housed breeding colony. The subjects were not genetically related or exposed to the same research conditions. Diagnoses were made based on the presentation and radiographic findings, with histologic confirmation.

Particle-to-PFU ratio of Ebola virus influences disease course and survival in cynomolgus macaques.

UNLABELLED: This study addresses the role of Ebola virus (EBOV) specific infectivity in virulence. Filoviruses are highly lethal, enveloped, single-stranded negative-sense RNA viruses that can cause hemorrhagic fever. No approved vaccines or therapies exist for filovirus infections, and infectious virus must be handled in maximum containment. Efficacy testing of countermeasures, in addition to investigations of pathogenicity and immune response, often requires a well-characterized animal model. For EBOV, an obstacle in performing accurate disease modeling is a poor understanding of what constitutes an infectious dose in animal models. One well-recognized consequence of viral passage in cell culture is a change in specific infectivity, often measured as a particle-to-PFU ratio. Here, we report that serial passages of EBOV in cell culture resulted in a decrease in particle-to-PFU ratio. Notably, this correlated with decreased potency in a lethal cynomolgus macaque (Macaca fascicularis) model of infection; animals were infected with the same viral dose as determined by plaque assay, but animals that received more virus particles exhibited increased disease. This suggests that some particles are unable to form a plaque in a cell culture assay but are able to result in lethal disease in vivo. These results have a significant impact on how future studies are designed to model EBOV disease and test countermeasures. IMPORTANCE: Ebola virus (EBOV) can cause severe hemorrhagic disease with a high case-fatality rate, and there are no approved vaccines or therapies. Specific infectivity can be considered the total number of viral particles per PFU, and its impact on disease is poorly understood. In stocks of most mammalian viruses, there are particles that are unable to complete an infectious cycle or unable to cause cell pathology in cultured cells. We asked if these particles cause disease in nonhuman primates by infecting monkeys with equal infectious doses of genetically identical stocks possessing either high or low specific infectivities. Interestingly, some particles that did not yield plaques in cell culture assays were able to result in lethal disease in vivo. Furthermore, the number of PFU needed to induce lethal disease in animals was very low. Our results have a significant impact on how future studies are designed to model EBOV disease and test countermeasures.

Chronic continuous exenatide infusion does not cause pancreatic inflammation and ductal hyperplasia in non-human primates.

In this study, we aimed to evaluate the effects of exenatide (EXE) treatment on exocrine pancreas of nonhuman primates. To this end, 52 baboons (Papio hamadryas) underwent partial pancreatectomy, followed by continuous infusion of EXE or saline (SAL) for 14 weeks. Histological analysis, immunohistochemistry, Computer Assisted Stereology Toolbox morphometry, and immunofluorescence staining were performed at baseline and after treatment. The EXE treatment did not induce pancreatitis, parenchymal or periductal inflammatory cell accumulation, ductal hyperplasia, or dysplastic lesions/pancreatic intraepithelial neoplasia. At study end, Ki-67-positive (proliferating) acinar cell number did not change, compared with baseline, in either group. Ki-67-positive ductal cells increased after EXE treatment (P = 0.04). However, the change in Ki-67-positive ductal cell number did not differ significantly between the EXE and SAL groups (P = 0.13). M-30-positive (apoptotic) acinar and ductal cell number did not change after SAL or EXE treatment. No changes in ductal density and volume were observed after EXE or SAL. Interestingly, by triple-immunofluorescence staining, we detected c-kit (a marker of cell transdifferentiation) positive ductal cells co-expressing insulin in ducts only in the EXE group at study end, suggesting that EXE may promote the differentiation of ductal cells toward a ß-cell phenotype. In conclusion, 14 weeks of EXE treatment did not exert any negative effect on exocrine pancreas, by inducing either pancreatic inflammation or hyperplasia/dysplasia in nonhuman primates.

Analysis of prostate-specific antigen transcripts in chimpanzees, cynomolgus monkeys, baboons, and African green monkeys.

The function of prostate-specific antigen (PSA) is to liquefy the semen coagulum so that the released sperm can fuse with the ovum. Fifteen spliced variants of the PSA gene have been reported in humans, but little is known about alternative splicing in nonhuman primates. Positive selection has been reported in sex- and reproductive-related genes from sea urchins to Drosophila to humans; however, there are few studies of adaptive evolution of the PSA gene. Here, using polymerase chain reaction (PCR) product cloning and sequencing, we study PSA transcript variant heterogeneity in the prostates of chimpanzees (Pan troglodytes), cynomolgus monkeys (Macaca fascicularis), baboons (Papio hamadryas anubis), and African green monkeys (Chlorocebus aethiops). Six PSA variants were identified in the chimpanzee prostate, but only two variants were found in cynomolgus monkeys, baboons, and African green monkeys. In the chimpanzee the full-length transcript is expressed at the same magnitude as the transcripts that retain intron 3. We have found previously unidentified splice variants of the PSA gene, some of which might be linked to disease conditions. Selection on the PSA gene was studied in 11 primate species by computational methods using the sequences reported here for African green monkey, cynomolgus monkey, baboon, and chimpanzee and other sequences available in public databases. A codon-based analysis (dN/dS) of the PSA gene identified potential adaptive evolution at five residue sites (Arg45, Lys70, Gln144, Pro189, and Thr203).

Correlation between presence of Trypanosoma cruzi DNA in heart tissue of baboons and cynomolgus monkeys, and lymphocytic myocarditis.

Trypanosoma cruzi, the causative agent of Chagas' disease, preferentially infects cardiac and digestive tissues. Baboons living in Texas (Papio hamadryas) and cynomolgus monkeys (Macaca fascicularis) have been reported to be infected naturally with T. cruzi. In this study, we retrospectively reviewed cases of animals that were diagnosed with lymphocytic myocarditis and used a polymerase chain reaction (PCR)-based method (S36/S35 primer set) to amplify T. cruzi DNA from archived frozen and formalin-fixed paraffin-embedded (FFPE) cardiac tissues. We show that the PCR method is applicable in archived frozen and FFPE tissues and the sensitivity is in the femtogram range. A positive correlation between PCR positivity and lymphocytic myocarditis in both baboons and cynomolgus monkeys is shown. We also show epicarditis as a common finding in animals infected with T. cruzi.

Mortality in captive baboons (Papio spp.): a-23-year study.

BACKGROUND: We report the causes of mortality for 4350 captive baboons that died or were euthanized due to natural causes during a 23 year period at the Southwest National Primate Research Center. METHODS: Necropsy records were retrieved and reviewed to determine a primary cause of death or indication for euthanasia. Data was evaluated for morphological diagnosis, organ system, and etiology. RESULTS: The 20 most common morphologic diagnoses accounted for 76% of the cases, including stillborn (10.8%); colitis (8.6%); hemorrhage (8.4%); ulcer (5.2%); seizures (4.7%); pneumonia (4.2%); inanition (4.1%); dermatitis (3.8%); spondylosis (3.3%); and amyloidosis (3.0%). The digestive system was most frequently involved (21.3%), followed by the urogenital (20.3%), cardiovascular (12.2%), and multisystem disease (10.3%). An etiology was not identified in approximately one-third of cases. The most common etiologies were trauma (14.8%), degenerative (9.5%), viral (8.7%), and neoplastic/proliferative (7.0%). CONCLUSION: This information should be useful for individuals working with baboons.

Establishment of a neonatal rhesus macaque model to study Mycobacterium tuberculosis infection.

Mycobacterium tuberculosis (Mtb) is the causative agent of human tuberculosis (TB) with an estimated 8.8 million new TB cases and 1.4 million deaths annually. Tuberculosis is the leading cause of death in AIDS patients worldwide but very little is known about early TB infection or TB/HIV co-infection in infants. A clinically relevant newborn animal model to study TB infection is urgently needed. We have successfully established an aerosol newborn/infant model in neonatal nonhuman primates (NHPs) that mimics clinical and bacteriological characteristics of Mtb infection as seen in human newborns/infants. Further, this model will allow the establishment of a TB coinfection model of pediatric AIDS. Aerosol versus intra broncho-alveolar Mtb infection was studied. Interestingly, 42 days post infection specific lesions were detected suggestive of the classic Ghon focus in human children. Concurrently, specific cellular immune responses developed 4-6 weeks after Mtb infection. Using the enzyme-linked immunospot (ELISPOT) assays, we found that IL-12 production correlated with early Mtb infection lesions seen by routine thoracic radiographs. Overall, this work represents the first example of early Mtb infection of newborn macaques. This study gives us a unique opportunity to further characterize immunopathogenesis and establish a TB/SIV co-infection model for pediatric AIDS.