Current practices in nutrition management and disease incidence of common marmosets (Callithrix jacchus)

BACKGROUND

A survey was developed to characterize disease incidence, common pathology lesions, environmental characteristics, and nutrition programs within captive research marmoset colonies.

METHODS

Seventeen research facilities completed the electronic survey.

RESULTS

Nutritional management programs varied amongst research institutions housing marmosets; eight primary base diets were reported. The most common clinical syndromes reported were gastrointestinal disease (i.e. inflammatory bowel disease like disease, chronic lymphocytic enteritis, chronic malabsorption, chronic diarrhea), metabolic bone disease or fracture, infectious diarrhea, and oral disease (tooth root abscesses, gingivitis, tooth root resorption). The five most common pathology morphologic diagnoses were colitis, nephropathy/nephritis, enteritis, chronic lymphoplasmacytic enteritis, and cholecystitis. Obesity was more common (average 20% of a reporting institution's population) than thin body condition (average 5%).

CONCLUSIONS

Through review of current practices, we aim to inspire development of evidence-based practices to standardize husbandry and nutrition practices for marmoset research colonies.

Metabolic Dysregulation in Hepacivirus Infection of Common Marmosets (Callithrix jacchus)

Chronic hepatitis C has been associated with metabolic syndrome that includes insulin resistance, hepatic steatosis and obesity. These metabolic aberrations are risk factors for disease severity and treatment outcome in infected patients. Experimental infection of marmosets with GBV-B serves as a tangible, small animal model for human HCV infection, and while virology and pathology are well described, a full investigation of clinical disease and the metabolic milieu is lacking. In this study six marmosets were infected intravenously with GBV-B and changes in hematologic, serum biochemical and plasma metabolic measures were investigated over the duration of infection. Infected animals exhibited signs of lymphocytopenia, but platelet and RBC counts were generally stable or even increased. Although most animals showed a transient decline in blood glucose, infection resulted in several fold increases in plasma insulin, glucagon and glucagon-like peptide 1 (GLP-1). All infected animals experienced transient weight loss within the first 28 days of infection, but also became hypertriglyceridemic and had up to 10-fold increases in adipocytokines such as resistin and plasminogen activator inhibitor 1 (PAI-1). In liver, moderate to severe cytoplasmic changes associated with steatotic changes was observed microscopically at 168 days post infection. Collectively, these results suggest that GBV-B infection is accompanied by hematologic, biochemical and metabolic abnormalities that could lead to obesity, diabetes, thrombosis and atherosclerosis^, even after virus has been cleared. Our findings mirror those found in HCV patients, suggesting that metabolic syndrome could be conserved among hepaciviruses, and both mechanistic and interventional studies for treating HCV-induced metabolic complications could be evaluated in this animal model.

Hyperhexosemia-Induced Retinal Vascular Pathology in a Novel Primate Model of Diabetic Retinopathy

The paucity of animal models exhibiting full pathology of diabetic retinopathy (DR) has impeded understanding of the pathogenesis of DR and the development of therapeutic interventions. Here, we investigated whether hyperhexosemic marmosets (Callithrix jacchus) develop characteristic retinal vascular lesions including macular edema (ME), a leading cause of vision loss in DR. Marmosets maintained on 30% galactose (gal)-rich diet for 2 years were monitored for retinal vascular permeability, development of ME, and morphological characteristics including acellular capillaries (AC) and pericyte loss (PL), vessel tortuosity, and capillary basement membrane (BM) thickness. Excess vascular permeability, increased number of AC and PL, vascular BM thickening, and increased vessel tortuosity were observed in the retinas of gal-fed marmosets. Optical coherence tomography (OCT) images revealed significant thickening of the retinal foveal and the juxtafoveal area, and histological analysis showed incipient microaneurysms in retinas of gal-fed marmosets. Findings from this study indicate that hyperhexosemia can trigger retinal vascular changes similar to those seen in human DR including ME and microaneurysms. The striking similarities between the marmoset retina and the human retina, and the exceptionally small size of the monkey, offer significant advantages to this primate model of DR.

The effects of an ActRIIb receptor Fc fusion protein ligand trap in juvenile simian immunodeficiency virus-infected rhesus macaques

There are no approved therapies for muscle wasting in children infected with human immunodeficiency virus (HIV), which portends poor disease outcomes. To determine whether a soluble ActRIIb receptor Fc fusion protein (ActRIIB.Fc), a ligand trap for TGF-β/activin family members including myostatin, can prevent or restore loss of lean body mass and body weight in simian immunodeficiency virus (SIV)-infected juvenile rhesus macaques (Macaca mulatta). Fourteen pair-housed, juvenile male rhesus macaques were inoculated with SIVmac239 and, 4 wk postinoculation (WPI) treated with intramuscular injections of 10 mg ⋅ kg(-1) ⋅ wk(-1) ActRIIB.Fc or saline placebo. Body weight, lean body mass, SIV titers, and somatometric measurements were assessed monthly for 16 wk. Age-matched SIV-infected rhesus macaques were injected with saline. Intervention groups did not differ at baseline. Gains in lean mass were significantly greater in the ActRIIB.Fc group than in the placebo group (P < 0.001). Administration of ActRIIB.Fc was associated with greater gains in body weight (P = 0.01) and upper arm circumference than placebo. Serum CD4(+) T-lymphocyte counts and SIV copy numbers did not differ between groups. Administration of ActRIIB.Fc was associated with higher muscle expression of myostatin than placebo. ActRIIB.Fc effectively blocked and reversed loss of body weight, lean mass, and fat mass in juvenile SIV-infected rhesus macaques.

High-performance metabolic profiling with dual chromatography-Fourier-transform mass spectrometry (DC-FTMS) for study of the exposome

Studies of gene-environment (G × E) interactions require effective characterization of all environmental exposures from conception to death, termed the exposome. The exposome includes environmental exposures that impact health. Improved metabolic profiling methods are needed to characterize these exposures for use in personalized medicine. In the present study, we compared the analytic capability of dual chromatography-Fourier-transform mass spectrometry (DC-FTMS) to previously used liquid chromatography-FTMS (LC-FTMS) analysis for high-throughput, top-down metabolic profiling. For DC-FTMS, we combined data from sequential LC-FTMS analyses using reverse phase (C18) chromatography and anion exchange (AE) chromatography. Each analysis was performed with electrospray ionization in the positive ion mode and detection from m/z 85 to 850. Run time for each column was 10 min with gradient elution; 10 µl extracts of plasma from humans and common marmosets were used for analysis. In comparison to analysis with the AE column alone, addition of the second LC-FTMS analysis with the C18 column increased m/z feature detection by 23-36%, yielding a total number of features up to 7,000 for individual samples. Approximately 50% of the m/z matched to known chemicals in metabolomic databases, and 23% of the m/z were common to analyses on both columns. Database matches included insecticides, herbicides, flame retardants, and plasticizers. Modularity clustering algorithms applied to MS-data showed the ability to detection clusters and ion interactions. DC-FTMS thus provides improved capability for high-performance metabolic profiling of the exposome and development of personalized medicine.

Alopecia in Rhesus macaques correlates with immunophenotypic alterations in dermal inflammatory infiltrates consistent with hypersensitivity etiology

BACKGROUND

Although alopecia is a commonly recognized problem affecting many captive Rhesus macaque colonies, there is no consensus as to the underlying etiology or appropriate course of management.

METHODS

We performed skin biopsies to assess underlying pathology in alopecic Rhesus macaques and performed immunohistochemical and metachromatic staining of these biopsies to assess the cellular infiltrates.

RESULTS

Alopecia is associated with superficial dermal perivascular mononuclear cell infiltrates and skin pathology consistent with chronic hypersensitivity dermatitis. The inflammation is primarily composed of CD4+ cells admixed with histiocytes and mast cells. Inflammation is correlated with degree of alopecia. Further analysis in different groups of macaques revealed that animals born outdoors or infected with lung mites had reduced dermal inflammatory cell infiltrates and a lower incidence of alopecia.

CONCLUSIONS

These findings support a hypothesis that an altered housing status resulting in decreased pathogen burden in Rhesus macaque colonies may contribute to dermal immunophenotypic alterations and subsequent development of dermatitis with resultant alopecia.

A diet high in saturated fat and cholesterol accelerates simian immunodeficiency virus disease progression

Several lines of evidence suggest that dietary fat and cholesterol may play a role in the pathogenesis of human immunodeficiency virus (HIV) infection and disease progression. We examined the effect that an atherogenic diet (AD) high in saturated fatty acids and cholesterol has on disease progression and systemic inflammation in the simian immunodeficiency virus (SIV)-infected macaque model of acquired immunodeficiency syndrome. Macaques fed an AD had significantly more rapid disease progression, resulting in an increased risk of SIV-related death compared with that in control macaques (hazard ratio, 5.4 [95% confidence interval, 1.7-17.0]; P<.001). Peak viral load was higher in the AD group compared with control values, but further statistically significant differences were not detected at viral set point. The baseline plasma interleukin-18 level after 6 months of the AD was predictive of disease progression. Our findings may have important implications for HIV-infected individuals, because they suggest that dietary changes and manipulation of lipid metabolism could offer potential benefits by slowing disease progression.