Healthy Nonhuman Primates Research Articles

Oral ambroxol increases brain glucocerebrosidase activity in a nonhuman primate.

Mutations in the glucocerebrosidase 1 (GBA1) gene are related to both Parkinson disease (PD) and Gaucher disease (GD). In both cases, the condition is associated with deficiency of glucocerebrosidase (GCase), the enzyme encoded by GBA1. Ambroxol is a small molecule chaperone that has been shown in mice to cross the blood‐brain barrier, increase GCase activity and reduce alpha‐synuclein protein levels. In this study, we analyze the effect of ambroxol treatment on GCase activity in healthy nonhuman primates. We show that daily administration of ambroxol results in increased brain GCase activity. Our work further indicates that ambroxol should be investigated as a novel therapy for both PD and neuronopathic GD in humans.

Modeling Hepatocellular Toxicity of Enavatuzumab, a Humanized Anti-TweakR Antibody

In a Phase 1 clinical study, treatment with enavatuzumab, a humanized monoclonal antibody to TweakR, resulted in liver toxicity in a subset of patients. The objective of this current study was to evaluate the ability of preclinical studies to predict liver toxicity in humans. Enavatuzumab was evaluated in cynomolgus monkeys, where serum liver enzyme and cytokine levels were measured and histopathology of the liver was performed. TweakR expression was evaluated by immunohistochemistry in healthy human liver and in liver tissues from cancer patients. Enavatuzumab was also evaluated in vitro for its impact on human hepatocytes when cultured both alone and with immune cells. Enavatuzumab-treated cynomolgus monkeys exhibited liver enzyme elevations only at the highest dose level (100 mg/kg) and few cytokines were elevated after dosing. Bile duct hyperplasia was observed in the liver but appeared to be partially reversible. Compared with healthy liver, liver tissues from cancer patients exhibited marked elevation of TweakR expression, which was associated with immune cell infiltration. Enavatuzumab treatment of cultured hepatocytes, both in the presence and absence of immune cells resulted in increased cytokine release, but only in the co-cultures were liver enzymes elevated. These results suggest that due to differences in liver architecture between healthy humans and cancer patients, studies in healthy non-human primates may underestimate the potential for liver toxicity in human cancer patients. The use of additional in vitro assays in conjunction with in vivo studies may better predict the potential impact of a therapeutic agent on the liver in clinical studies.

Robust modulation of arousal regulation, performance, and frontostriatal activity through central thalamic deep brain stimulation in healthy nonhuman primates.

The central thalamus (CT) is a key component of the brain-wide network underlying arousal regulation and sensory-motor integration during wakefulness in the mammalian brain. Dysfunction of the CT, typically a result of severe brain injury (SBI), leads to long-lasting impairments in arousal regulation and subsequent deficits in cognition. Central thalamic deep brain stimulation (CT-DBS) is proposed as a therapy to reestablish and maintain arousal regulation to improve cognition in select SBI patients. However, a mechanistic understanding of CT-DBS and an optimal method of implementing this promising therapy are unknown. Here we demonstrate in two healthy nonhuman primates (NHPs), Macaca mulatta, that location-specific CT-DBS improves performance in visuomotor tasks and is associated with physiological effects consistent with enhancement of endogenous arousal. Specifically, CT-DBS within the lateral wing of the central lateral nucleus and the surrounding medial dorsal thalamic tegmental tract (DTTm) produces a rapid and robust modulation of performance and arousal, as measured by neuronal activity in the frontal cortex and striatum. Notably, the most robust and reliable behavioral and physiological responses resulted when we implemented a novel method of CT-DBS that orients and shapes the electric field within the DTTm using spatially separated DBS leads. Collectively, our results demonstrate that selective activation within the DTTm of the CT robustly regulates endogenous arousal and enhances cognitive performance in the intact NHP; these findings provide insights into the mechanism of CT-DBS and further support the development of CT-DBS as a therapy for reestablishing arousal regulation to support cognition in SBI patients.

Abstract CT049: Phase I/Ib study of the novel CD20-targeted immunotoxin MT-3724 in relapsed/refractory non-Hodgkin's B-cell lymphoma

Abstract Background Anti-CD20 monoclonal antibody (MAb) therapy is widely employed in the treatment of non-Hodgkin's B-cell lymphoma (NHL), but most patients eventually become refractory to CD20 MAb(s). MT-3724 is a recombinant fusion protein consisting of a CD20 binding variable fragment (scFv) fused to the ribosomal inhibitory protein Shiga-like toxin-I A1 subunit (SLT-I A1). Upon its scFv binding to surface CD20, SLT-I A1 forces MT-3724 internalization and irreversibly inactivates cell ribosomes triggering cell death. MT-3724 specifically binds and kills CD20+ malignant human B-cells in vitro and non-human primate (NHP) B-cells in vivo. In healthy NHPs 6 intravenous (IV) doses of MT-3724 were given over 12 days (d) at doses of 50, 150, and 450 mcg/kg with no deaths or effects on serum chemistry. Given the preclinical activity and novel mechanism of action, a Phase I/Ib study of MT-3724 was initiated. Methods MT-3724 is being tested in a first-in-human (FIH), open label, dose escalation study (3 + 3 design) in sequential cohorts of 5, 10, 20 and 50 mcg/kg/dose. Eligible subjects who previously responded to a CD20 MAb containing therapy followed by relapse/recurrence of NHL receive 6 doses by 2 hour IV infusions over the first 12 d of a 28 d cycle (first cycle). With continued safety, tolerability and lack of tumor progression, subjects may receive additional 6-dose cycles (21 d cycles) with tumor assessments after cycles 2, 4 and 5. Dose escalation is based on < 33% dose limiting toxicities (DLTs) observed during the first 28 d cycle. Results Twelve evaluable relapsed/refractory (R/R) NHL subjects have completed at least the first cycle in the 5, 10, 20 or 50 mcg/kg/dose cohort: 6 women/6 men; mean age 66.2 years (range 34-78). In these subjects who have received multiple approved and experimental treatments prior to enrollment, there have been no DLTs or infusion related reactions. With the exception of one Grade 4 isolated neutropenia lasting < 7 days which was possibly attributed to MT-3724 there have been no Grade 3 or 4 adverse events or serious adverse events attributed to MT-3724. In the 5 mcg/kg/dose cohort, one subject with transformed diffuse large B-cell lymphoma (tDLBCL) completed 5 cycles achieving a partial response (PR) post cycle 2 which was sustained through cycle 5; a second subject with tDLBCL had a mixed response. All three subjects treated in the 10 mcg/kg/dose cohort achieved stable disease (SD) with tumor regression. One subject with mixed DLBCL/follicular lymphoma in the 20 mcg/kg/dose cohort achieved a PR that further deepened to minimal residual disease and will undergo allo-SCT. All patients with high levels (>1,000 ng/mL) of circulating CD20 MAb developed progressive disease. Pharmacokinetic data suggest receptor saturation has not yet been reached at the 20 mcg/kg dose. Conclusions MT-3724 up to 50 mcg/kg/dose has been well tolerated for up to 5 cycles in this FIH study in heavily pre-treated patients with R/R NHL. Treatment in the 100 mcg/kg cohort has commenced with continuing dose ascension planned. Because of the shared epitope and the significantly higher doses and longer half-lives of CD20 MAbs relative to MT-3724, recent exposure to these Mabs is likely to inhibit MT-3724 activity. There is early evidence of clinical activity (2 PRs, 1 mixed response, 3 SDs with tumor regression), all observed in patients without recent CD20 MAb exposure. Citation Format: Michelle A. Fanale, Paul A. Hamlin, Catherine S. Diefenbach, Steven I. Park, David J. Valacer, Jack P. Higgins, Anas Younes. Phase I/Ib study of the novel CD20-targeted immunotoxin MT-3724 in relapsed/refractory non-Hodgkin's B-cell lymphoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT049.

Quantitative MRI biomarkers to characterize regional left ventricular perfusion and function in nonhuman primates during dobutamine-induced stress: A reproducibility and reliability study.

To identify reproducible and reliable noninvasive regional imaging biomarkers of cardiac function and perfusion at rest and under stress in healthy nonhuman primates (NHPs) that may be used in the future for the early characterization of preclinical heart failure models, to evaluate therapy, and for clinical translation. Seven naive cynomolgus macaques underwent test-retest 3T cardiac MRI tagging and dual-bolus perfusion experiments. Regional cardiac function biomarkers, such as peak circumferential strain (CS), average diastolic strain-rate (DSR), contractile reserve (CR), diastolic reserve, peak torsion, and torsion reserve were quantified. Further, regional myocardial blood flow (MBF), myocardial perfusion reserve (MPR), and myocardial perfusion reserve-to-contractile reserve (MPR/CR) were also derived. Inter- and intraobserver reproducibility and test-retest reliability analyses were conducted using the reliability and generalizability coefficients including correlation coefficient (CC) and intraclass correlation coefficient (ICC). Overall, peak CS, DSR, and MBF are robust biomarkers at both rest and stress with moderate-good inter- and intraobserver reproducibility and test-retest reliability. At rest: intra-/interobserver reproducibility (CC): peak CS (0.81/0.81), DSR (0.81/0.81), MBF (0.72/0.57), peak torsion (0.79/0.79); test-retest reliability: (CC/ICC): peak CS (0.62/0.75), DSR (0.24/0.55), MBF (0.66/0.62), and peak torsion (0.79/0.78). Under stress: intra-/interobserver reproducibility (CC): peak CS (0.61/0.60), DSR (0.50/0.50), MBF (0.63/0.61), MPR (0.43/0.43), and peak torsion (0.38/0.38); test-retest reliability: (CC/ICC): peak CS (0.58/0.58), DSR (0.24/0.43), MBF (0.58/0.58), MPR (0.43/0.38), and peak torsion (0.38/0.38). We demonstrated the feasibility of using cardiac MRI to characterize left ventricular functional and perfusion responses to stress in an NHP species, and specific robust biomarkers such as peak CS, DSR, MBF, diastolic reserve, and MPR have been identified for clinical translation and drug research. 1 J. Magn. Reson. Imaging 2017;45:556-569.

Phase I/Ib Study of the Novel Immunotoxin MT-3724 in Relapsed/Refractory Non-Hodgkin's B-Cell Lymphoma (NHL)

BackgroundCD20 is selectively expressed on the surface of early pre-B-cells, remains throughout B-cell development, and is then lost from plasma cells. Because CD20 is present on the majority of B-cell lymphomas, anti-CD20 monoclonal antibody (MAb) therapy is widely employed in the treatment of NHL. However a majority of NHL patients eventually become refractory to CD20 MAb(s). Resistance mechanisms may include increased MAb catabolism, initial or post treatment selection of low CD20 expressing tumor cells, trogocytosis of surface CD20, failure of MAb effector mechanisms and/or impaired patient immune cell function.MT-3724 is a recombinant fusion protein consisting of a CD20 binding variable fragment (scFv) fused to the enzymatically active Shiga-like toxin-I A1 subunit (SLT-I A1). SLT-I A1 is an N-glycosidase that catalytically inactivates 60S ribosomal subunits causing inhibition of protein synthesis. Upon its scFv binding to cell surface CD20 in vitro, SLT-I A1 forces MT-3724 internalization which then routes in a predictable fashion to the cytosol and irreversibly inactivates the cell ribosomes triggering cell death. MT-3724 has been shown to specifically bind and kill CD20+ malignant human B-cells in vitro and non-human primate (NHP) B-cells in vivo. MT-3724 was tested for safety in healthy NHPs: 6 intravenous (IV) doses of MT-3724 were given over 12 days at doses of 50, 150, and 450 mcg/kg. There were no deaths or effects on serum chemistries in the NHP studies. The major observed toxicity (inappetence) resolved within 48 hours of last dose. There was a significant, dose-dependent NHP B-cell depletion by Day 3 at all doses. Given the preclinical activity and mechanism of action, a Phase I/Ib study of MT-3724 was initiated in NHL.MethodsMT-3724 is being tested for safety and tolerability in a first-in-human, open label, ascending dose study (3 + 3 design) in sequential cohorts of 5, 10, 20 and 50 mcg/kg/dose. Eligible subjects who previously responded to a CD20 MAb containing therapy followed by relapse/recurrence of NHL receive 6 doses by 2 hour IV infusions over the first 12 days of a 28 day cycle (first cycle). With continued safety, tolerability and lack of tumor progression, subjects may receive up to 4 additional 6-dose cycles (21 days) with tumor assessments after cycles 2, 4 and 5. Dose escalation is based on < 33% dose limiting toxicities (DLTs) observed during the first 28 day cycle.ResultsThree NHL subjects (2 transformed DLBCL, 1 FL) have completed at least one cycle in the 5 mcg/kg/dose cohort with no protocol DLTs or infusion related reactions and are evaluable for safety. Non-DLTs included grade (Gr) 2-3 transient hyperglycemic episodes related to pre-infusion corticosteroid therapy (n=1); transient Gr 4 neutropenia, possibly related to MT-3724 during cycle 1, week 4 (n=1); Gr 4 hypercalcemia and acute kidney injury with Gr 3 hypophosphatemia during cycle 1, week 4 due to leukemic disease progression (n=1). Subject 1 completed 5 cycles of therapy, with a partial response achieved post cycle 2 sustained through cycle 5; Subject 3 had a mixed response (both subjects had transformed DLBCL). Three subjects have now initiated treatment in the 10 mcg/kg/dose cohort with updated data to be presented at the meeting.ConclusionsMT-3724 at 5 mcg/kg/dose has been safely administered for up to 5 cycles in this first-in-human study in relapsed/refractory NHL subjects. Treatment with the 10 mcg/kg cohort has commenced with continuing dose ascension planned. There is early evidence of clinical activity. DisclosuresDiefenbach:Gilead: Equity Ownership, Research Funding, Speakers Bureau; Jannsen Oncology: Consultancy; Idera: Consultancy; Immunogen: Consultancy; Incyte: Research Funding; Genentech: Research Funding; Celgene: Consultancy; Molecular Templates: Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding. Valacer:Molecular Templates: Employment. Higgins:Molecular Templates: Employment. Fanale:Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Research Funding; Infinity: Membership on an entity's Board of Directors or advisory committees; Spectrum: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Honoraria, Research Funding; Genentech: Research Funding; Medimmune: Research Funding; Novartis: Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Molecular Templates: Research Funding; ADC Therapeutics: Research Funding; Onyx: Research Funding; Gilead: Research Funding.

A preliminary study of dopamine D2/3 receptor availability and social status in healthy and cocaine dependent humans imaged with [11C](+)PHNO

BackgroundPrevious work in healthy non-human primates and humans has shown that social status correlates positively with dopamine 2/3 receptor (D2/3R) availability imaged with antagonist radioligands and positron emission tomography (PET). Further work in non-human primates suggests that this relationship is disrupted by chronic cocaine administration. This exploratory study examined the relationship between social status and D2/3R availability in healthy (HH) and cocaine dependent (CD) humans using the D3-preferring, agonist radioligand, [11C](+)PHNO. MethodsSixteen HH and sixteen CD individuals completed the Barratt Simplified Measure of Social Status (BSMSS) and underwent [11C](+)PHNO scanning to measure regional brain D2/3R binding potentials (BPND). Correlations between BPND and BSMSS scores were then assessed within each group. ResultsWithin HH and CD groups, inverse associations between BSMSS score and BPND were observed in the substantia nigra/ventral tegmental area (SN/VTA) and the ventral striatum, and for the CD group alone, the amygdala. After adjusting for body mass index and age, negative correlations remained significant in the SN/VTA for HH and in the amygdala for CD subjects. ConclusionThese preliminary data utilizing a dopamine agonist tracer demonstrate, for the first time, an inverse association between social status and D2/3R availability in the D3R rich extrastriatal regions of HH and CD humans.

Characteristics of Spontaneous Square-Wave Jerks in the Healthy Macaque Monkey during Visual Fixation

Saccadic intrusions (SIs), predominantly horizontal saccades that interrupt accurate fixation, include square-wave jerks (SWJs; the most common type of SI), which consist of an initial saccade away from the fixation target followed, after a short delay, by a return saccade that brings the eye back onto target. SWJs are present in most human subjects, but are prominent by their increased frequency and size in certain parkinsonian disorders and in recessive, hereditary spinocerebellar ataxias. SWJs have been also documented in monkeys with tectal and cerebellar etiologies, but no studies to date have investigated the occurrence of SWJs in healthy nonhuman primates. Here we set out to determine the characteristics of SWJs in healthy rhesus macaques (Macaca mulatta) during attempted fixation of a small visual target. Our results indicate that SWJs are common in healthy nonhuman primates. We moreover found primate SWJs to share many characteristics with human SWJs, including the relationship between the size of a saccade and its likelihood to be part of a SWJ. One main discrepancy between monkey and human SWJs was that monkey SWJs tended to be more vertical than horizontal, whereas human SWJs have a strong horizontal preference. Yet, our combined data indicate that primate and human SWJs play a similar role in fixation correction, suggesting that they share a comparable coupling mechanism at the oculomotor generation level. These findings constrain the potential brain areas and mechanisms underlying the generation of fixational saccades in human and nonhuman primates.

Factors affecting urine reagent strip blood results in dogs and nonhuman primates and interpretation of urinalysis in preclinical toxicology studies: a Multi-Institution Contract Research Organization and BioPharmaceutical Company Perspective.

Urinalysis data in preclinical toxicology studies can be influenced by preanalytic and analytic factors which have the potential to confound interpretation. There is a paucity of information regarding positive reagent strip urinary blood reactions in healthy nonhuman primates (NHP) and Beagle dogs used in preclinical toxicology studies. The objectives were (1) to establish historical control data for reagent strip urinary blood reactions in healthy NHP and Beagle dogs, (2) to determine the incidence of positive urinary blood reactions during predose and dosing phases, and (3) to determine if collection practice was a relevant parameter. Historical control data from 2 institutions in the biopharmaceutical industry were retrospectively analyzed for reagent strip urinary blood reactions in healthy NHP and Beagles. The incidence of positive results between the 2 institutions with different urine collection practices and between males and females was compared. The incidence of positive urinary blood reactions in NHP was comparable between institutions (≤14% in males; ≤33% in females), while the incidence of positive urinary blood reactions in Beagles was more variable (≤77% in males; ≤69% in females), and higher in females during the dosing phase. Positive urinary blood results that could potentially be misinterpreted as toxicologically relevant were identified in healthy NHP and Beagles during predose and dosing phases. Different incidences of positive results between the 2 institutions were likely related to collection practices. Strategies to reduce feces and food contamination of collected urine samples should help minimize false-positive urinary blood reactions.

Longitudinal Characterization of Escherichia coli in Healthy Captive Non-Human Primates.

The gastrointestinal (GI) tracts of non-human primates (NHPs) are well known to harbor Escherichia coli, a known commensal of human beings and animals. While E. coli is a normal inhabitant of the mammalian gut, it also exists in a number of pathogenic forms or pathotypes, including those with predisposition for the GI tract as well as the urogenital tract. Diarrhea in captive NHPs has long been a problem in both zoo settings and research colonies, including the Como Zoo. It is an animal welfare concern, as well as a public health concern. E. coli has not been extensively studied; therefore, a study was performed during the summer of 2009 in collaboration with a zoo in Saint Paul, MN, which was previously experiencing an increased incidence and severity of diarrhea among their NHP collection. Fresh fecal samples were collected weekly from each member of the primate collection, between June and August of 2009, and E. coli were isolated. A total of 33 individuals were included in the study, representing eight species. E. coli isolates were examined for their genetic relatedness, phylogenetic relationships, plasmid replicon types, virulence gene profiles, and antimicrobial susceptibility profiles. A number of isolates were identified containing virulence genes commonly found in several different E. coli pathotypes, and there was evidence of clonal transmission of isolates between animals and over time. Overall, the manifestation of chronic diarrhea in the Como Zoo primate collection is a complex problem whose solution will require regular screening for microbial agents and consideration of environmental causes. This study provides some insight toward the sharing of enteric bacteria between such animals.

Subthalamic nucleus deep brain stimulation induces motor network BOLD activation: use of a high precision MRI guided stereotactic system for nonhuman primates.

Functional magnetic resonance imaging (fMRI) is a powerful method for identifying in vivo network activation evoked by deep brain stimulation (DBS). Identify the global neural circuitry effect of subthalamic nucleus (STN) DBS in nonhuman primates (NHP). An in-house developed MR image-guided stereotactic targeting system delivered a mini-DBS stimulating electrode, and blood oxygenation level-dependent (BOLD) activation during STN DBS in healthy NHP was measured by combining fMRI with a normalized functional activation map and general linear modeling. STN DBS significantly increased BOLD activation in the sensorimotor cortex, supplementary motor area, caudate nucleus, pedunculopontine nucleus, cingulate, insular cortex, and cerebellum (FDR < 0.001). Our results demonstrate that STN DBS evokes neural network grouping within the motor network and the basal ganglia. Taken together, these data highlight the importance and specificity of neural circuitry activation patterns and functional connectivity.

The nonhuman primate as a model for type 2 diabetes

Although rodent models provide insight into the mechanisms underlying type 2 diabetes mellitus (T2DM), they are limited in their translatability to humans. The nonhuman primate (NHP) shares important metabolic similarities with the human, making it an ideal model for the investigation of type 2 diabetes and use in preclinical trials. This review highlights the key contributions in the field over the last year using the NHP model. The NHP has not only provided novel insight into the normal and pathological processes that occur within the islet, but has also allowed for the preclinical testing of novel pharmaceutical targets for obesity and T2DM. Particularly, administration of fibroblast growth factor-21 in the NHP resulted in weight loss and improvements in metabolic health, supporting rodent studies and recent clinical trials. In addition, the NHP was used to demonstrate that a novel melanocortin-4 receptor agonist did not cause adverse cardiovascular effects. Finally, this model has been used to provide evidence that glucagon-like peptide-1-based therapies do not induce pancreatitis in the healthy NHP. The insight gained from studies using the NHP model has allowed for a better understanding of the processes driving T2DM and has promoted the development of well tolerated and effective treatments.

Type 2 diabetes critically redefined for nonhuman primates (854.9)

Nonhuman primates (NHPs) naturally develop type 2 diabetes (T2DM) with extraordinary concomitance to T2DM in humans. In order to determine valid criteria for the onset of T2DM in NHPs, a colony of 326 adult NHPs (232 male and 94 female; rhesus monkeys, Macaca mulatta) was studied prospectively, including fasting plasma glucose (FPG), glucose tolerance, HbA1c, insulin, lipid profiles, β‐cell function and insulin sensitivity. A subset of 105 metabolically healthy NHPs was used to establish normal/baseline fasting levels, with normal FPG, 57.3±6.6 mg/dl comparable to ~85 mg/dl in humans and normal HbA1c level, 4.2±0.3 comparable to ~5.5 in humans, thus, 37% and 27% lower than for humans. 112 monkeys developed diabetes while under study and showed the necessity of redefining the onset of T2DM for rhesus, specifically at a fasting glucose of 100 mg/dl or 5.6 mmol/l. Monkeys with a fasting glucose &gt;70 mg/dl were in the progression toward diabetes, and 80‐99 mg/dl was redefined as prediabetes, a level that coincided with sharp changes in β‐cell responses to glucose, and in fasting insulin levels. HbA1c was highly correlated with fasting glucose (r=0.852, p&lt;0.001), with a T2DM diagnostic level of &gt; 5.5% for rhesus. NHPs provide the optimal animal model for studies of the in vivo and molecular pathophysiology of T2DM, and these new diagnostic criteria are essential to improved translation to humans.

Seasonal H3N2 influenza A virus fails to enhance Staphylococcus aureus co-infection in a non-human primate respiratory tract infection model

Staphylococcus aureus community-acquired pneumonia is often associated with influenza or an influenza-like syndrome. Morbidity and mortality due to methicillin-resistant S. aureus (MRSA) or influenza and pneumonia, which includes bacterial co-infection, are among the top causes of death by infectious diseases in the United States. We developed a non-lethal influenza A virus (IAV) (H3N2)/S. aureus co-infection model in cynomolgus macaques (Macaca fascicularis) to test the hypothesis that seasonal IAV infection predisposes non-human primates to severe S. aureus pneumonia. Infection and disease progression were monitored by clinical assessment of animal health; analysis of blood chemistry, nasal swabs, and X-rays; and gross pathology and histopathology of lungs from infected animals. Seasonal IAV infection in healthy cynomolgus macaques caused mild pneumonia, but unexpectedly, did not predispose these animals to subsequent severe infection with the community-associated MRSA clone USA300. We conclude that in our co-infection model, seasonal IAV infection alone is not sufficient to promote severe S. aureus pneumonia in otherwise healthy non-human primates. The implication of these findings is that comorbidity factors in addition to IAV infection are required to predispose individuals to secondary S. aureus pneumonia.

Exclusive antagonism of the α4β7 integrin by vedolizumab confirms the gut-selectivity of this pathway in primates

Biological therapies that antagonize specific molecules have demonstrated efficacy in inflammatory bowel diseases, but infections resulting from systemic immunosuppression underscore the need for safer therapies. The objective of this investigation was to determine if antagonism of the α(4) β(7) integrin would exclusively yield gut-selective antiinflammatory activity in primates. A series of experiments were conducted to investigate potential intra- and extraintestinal effects in healthy nonhuman primates dosed repeatedly with the α(4) β(7) -exclusive antagonist vedolizumab (former versions: MLN0002, MLN02, LDP-02) for 4, 13, and 26 weeks. No adverse clinical effects of vedolizumab were observed in healthy cynomolgus monkeys up to the highest doses tested (100 mg/kg). Histomorphologic analyses indicated a reduction in the frequency of leukocytes in gastrointestinal tissue, but not other organs. A significant (P < 0.05) decrease in the frequency of β 7+ lymphocytes in gastrointestinal tissues corresponded to a significant (P < 0.05) increase in α(4) β 7+ memory helper T lymphocytes in peripheral blood. This elevation was specific to α(4) β 7+ memory helper T lymphocytes; levels of other leukocyte subsets remained unaffected. Systemic opportunistic infections were not observed, and vedolizumab did not inhibit adaptive or innate immune responses systemically. These data demonstrate that blocking the α(4) β(7) integrin exclusively yields gut-selective antiinflammatory activity in primates.

Antiparkinsonian Mechanism of Electroconvulsive Therapy in MPTP-Lesioned Non-Human Primates

Background: Electroconvulsive therapy (ECT), an effective treatment for depression, also improves motor symptomatology in Parkinson’s disease (PD). We have previously demonstrated that ECT stimulates dopamine (DA) function in the striatum of healthy non-human primates, suggesting that DA may contribute to antidepressant effects. Objective: We investigated the potential role of DA mechanisms in the amelioration of PD symptoms following a clinical course of ECT. Methods: We treated non-human primates rendered mildly bilaterally or unilaterally parkinsonian with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), with a course of 6 ECT treatments. Using positron emission tomography, animals were scanned at baseline and at various time points after ECT with tracers of the DA system. Data were analyzed using the Logan reference tissue model and statistics were performed using orthogonal polynomial contrasts. Results: There was no change in binding of the DA transporter tracer in the lesioned striata after ECT as opposed to what we measured in the striatum of healthy animals. Raclopride binding to the D_2/3 receptors was unaffected in all groups. However, there were increases in vesicular monoamine transporter type 2 and D₁ receptor binding in the MPTP-lesioned striata after ECT, returning towards baseline by 6 weeks. Conclusion: We suggest that the effects of ECT in PD may proceed from a mechanism similar to that in healthy animals but with a blunted dopaminergic response, likely due to the significant loss of striatal DA terminals. The safety of ECT, its mild side effects and its stimulatory effects of the DA system may thus make it an attractive adjunct to antiparkinsonian treatment.

Capsid-specific T-cell Responses to Natural Infections With Adeno-associated Viruses in Humans Differ From Those of Nonhuman Primates

Hepatic adeno-associated virus serotype 2 (AAV2)-mediated gene transfer failed to achieve sustained transgene product expression in human subjects. We formulated the hypothesis that rejection of AAV-transduced hepatocytes is caused by AAV capsid-specific CD8(+) T cells that become reactivated upon gene transfer. Although this hypothesis was compatible with clinical data, which showed a rise in circulating AAV capsid-specific T cells following injection of AAV vectors, it did not explain that AAV vectors achieved long-term transgene expression in rhesus macaques, which are naturally infected with AAV serotypes closely related to those of humans. To address this apparent contradiction, we tested human and rhesus macaque samples for AAV capsid-specific T cells by intracellular cytokine staining combined with staining for T-cell subset and differentiation markers. This highly sensitive method, which could provide a tool to monitor adverse T-cell responses in gene transfer trials, showed that AAV capsid-specific CD8(+) and CD4(+) T cells can be detected in blood of naturally infected humans and rhesus macaques. They are present at higher frequencies in rhesus macaques. Furthermore, T cells from humans and rhesus macaques exhibit striking differences in their differentiation status and in their functions, which may explain the disparate duration of AAV-mediated gene transfer in these two species.

Optimization and Validation of a Visual Integration Test for Schizophrenia Research

The Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia initiative highlighted a contour integration test as a promising index of visual integration impairment because of its well-established psychometric properties; its prior validation in healthy adults, patients, and nonhuman primates; and its potential sensitivity to treatment effects. In this multisite study, our goals were to validate the task on the largest subject sample to date, clarify the task conditions and number of trials that best discriminate patients from controls, and determine whether this discrimination can occur in standard clinical trial settings. For our task, subjects briefly observed a field of disconnected, oriented elements and attempted to decide whether a subset of those elements formed a leftward- or rightward-pointing shape. Difficulty depended on the amount of orientational jitter that was added to the shape's elements. Two versions of this Jittered Orientation Visual Integration task (JOVI) were examined. Study 1 did not reveal between-group differences in threshold (ie, the jitter magnitude needed to reach a performance level of ∼80%), but this likely owed to the wide sampling distribution of jitter levels and resulting floor/ceiling effects in many conditions. Study 2 incorporated a narrower range of difficulty levels and revealed lower thresholds (worse performance) among patients (p < .001). This group difference remained even when only the first half of the trials was analyzed (p = .001). Thus, the JOVI-2 provides a brief, sensitive measure of visual integration deficits in schizophrenia. Neural implications and potential future applications of the JOVI are discussed.

The Third Branch of the Main Trunk of the Left Coronary Artery in Cercopithecus aethiops sabaeus. Is the Nonhuman Primate Model Appropriate?

The aim of this study was to investigate the morphometry of branching patterns of the main trunk of the left coronary artery (MT of LCA) in nonhuman primates, and comment on the current nomenclature. The biometric study was performed using stereomicroscopic dissection of hearts of healthy and fertile nonhuman primates (Cercopithecus aethiops sabaeus) of both sexes. Our results reveal that the MT of LCA terminates in a bifurcation into the anterior interventricular branch (AIB) and the circumflex branch (CB) (74.6%), trifurcation into the AIB, CB, and diagonal branch (DB) (23.6%), or occasionally quadrifurcation into the AIB, CB, and two DBs (1.8%). This is similar to the case in humans. Furthermore, two morphological aspects of the DB spatial distribution, in addition to its branching pattern, resemble the DB in humans. Myocardial bridges observed over the DB in the Cercopithecus aethiops heart further contribute to the similarity with humans. The resemblance of the DB and its branches to their human counterparts make them a suitable model for experimental study on coronary circulation.

Vitamin K Deficiency From Long-Term Warfarin Anticoagulation Does Not Alter Skeletal Status in Male Rhesus Monkeys

Vitamin K (K) inadequacy may cause bone loss. Thus, K deficiency induced by anticoagulants (e.g., warfarin) may be an osteoporosis risk factor. The skeletal impact of long-term warfarin anticoagulation was evaluated in male monkeys. No effect on BMD or bone markers of skeletal turnover was observed. This study suggests that warfarin-induced K deficiency does not have skeletal effects. The skeletal role of vitamin K (K) remains unclear. It is reasonable that a potential role of vitamin K in bone health could be elucidated by study of patients receiving oral anticoagulants that act to produce vitamin K deficiency. However, some, but not all, reports find K deficiency induced by warfarin (W) anticoagulation to be associated with low bone mass. Additionally, epidemiologic studies have found W use to be associated with either increased or no change in fracture risk. Such divergent results may imply that human studies are compromised by the physical illnesses for which W was prescribed. To remove this potential confounder, we prospectively assessed skeletal status during long-term W anticoagulation of healthy nonhuman primates. Twenty adult (age, 7.4-17.9 yr, mean, 11.7 yr) male rhesus monkeys (Macaca mulatta) were randomized to daily W treatment or control groups. Bone mass of the total body, lumbar spine, and distal and central radius was determined by DXA at baseline and after 3, 6, 9, 12, 18, 24, and 30 mo of W treatment. Serum chemistries, urinary calcium excretion, bone-specific alkaline phosphatase, and total and percent unbound osteocalcin were measured at the same time-points. Prothrombin time and international normalized ratio (INR) were monitored monthly. Serum 25-hydroxyvitamin D was measured at the time of study conclusion. W treatment produced skeletal K deficiency documented by elevation of circulating undercarboxylated osteocalcin (8.3% W versus 0.4% control, p<0.0001) but did not alter serum markers of skeletal turnover, urinary calcium excretion, or BMD. In male rhesus monkeys, long-term W anticoagulation does not alter serum markers of bone turnover or BMD. Long-term W therapy does not have adverse skeletal consequences in primates with high intakes of calcium and vitamin D.