The use of glucocorticoids in marmoset wasting syndrome

Validation of Body Condition Scoring as a Screening Test for Low Body Condition and Obesity in Common Marmosets ( Callithrix jacchus )

Assessing body weight is common practice for monitoring health in common marmosets ( Callithrix jacchus ). Body composition analysis via quantitative magnetic resonance (QMR) is a more in-depth assessment allowing measurements of lean and fat mass, but it is expensive and remains unavailable to most. Alternatively, body condition scoring (BCS) is an instrument-free method for visually inspecting and palpating lean and fat tissue. Animals are rated for lean and fat mass abundance, using an ordinal scale with species-specific descriptions as reference. However, modified BCS systems developed for other species are being used, because no BCS system has been fully validated for marmosets. The accuracy of BCS in identifying marmosets with poor body condition or obesity remains unknown. We assessed an adapted BCS for marmosets (n=68, 2-16 years). Objectives were to 1) determine whether BCS predicts body weight and body composition, and 2) evaluate the performance of BCS as a screening test for low body condition and obesity in marmosets, in comparison to QMR body composition analysis. BCS predicted body weight and body composition ( F (15, 166)=7.51, Wilks' Λ=0.240, p <0.001), and was better at predicting low lean mass and obesity, than at predicting low adiposity. Marmosets with low BCS had higher odds of low lean mass ( B =3.37, (95% CI, 0.95-5.78), OR=29.0, p =0.006). Marmosets with excessively high BCS had higher odds of obesity ( B =2.72, (95% CI, 1.07-4.38), OR=15.23, p =0.001). The accuracy of BCS suggests it can serve as an instrument-free method to screen for low body condition (79.4%-91.2%) and obesity (77.9%) in marmosets.

Research highlights

We evaluated body condition scoring (BCS) as a screening tool for detecting low body condition and obesity in marmosets by comparing it to diagnoses based on quantitative magnetic resonance, the gold-standard method for body composition analysis.BCS was more accurate at detecting low lean mass and obesity than low adiposity, with marmosets having low BCS showing higher odds of low lean mass and those with excessively high BCS having higher odds of obesity.Results suggest that BCS can serve as an instrument-free method to screen for low body condition and obesity in marmosets, enabling early detection of health decline and guiding the need for further diagnostic testing and treatment.

Recent Advances in the Etiology, Diagnosis, and Treatment of Marmoset Wasting Syndrome

One of the primary challenges encountered in managing captive callitrichids is a group of gastrointestinal disorders that are collectively known as Marmoset Wasting Syndrome (MWS). Unfortunately, MWS is still not well understood. It is suggested that MWS has a multifactorial etiology; stress, infection, malnutrition, malabsorption, and enteritis or colitis may be associated with MWS. Usually, animals demonstrate more than one of the following clinical signs: progressive weight loss, alopecia, chronic diarrhea, muscle atrophy, hypoproteinemia, and anemia. Recent advances in diagnostics, mostly noninvasive fecal and urine tests, yielded promising results. Good treatment results have been achieved with the administration of glucocorticoids and tranexamic acid, although no cure has been found yet. Probiotics and gel diets also demonstrated to be potentially useful. However, once animals are affected by MWS, treatments eventually become ineffective, and animals will inevitably require euthanasia to prevent further suffering. Preventative measures should be aimed at reducing stress and optimizing housing, husbandry, and diets. More research is warranted to elucidate the pathogenesis of MWS in captive callitrichids and to refine diagnostic and treatment methods.

Review of Environmental and Health Factors Impacting Captive Common Marmoset Welfare in the Biomedical Research Setting

As a small-bodied neotropical nonhuman primate species, common marmosets have unique requirements for adequate husbandry and veterinary care to ensure proper maintenance and to promote good animal welfare in a biomedical research setting. Environmental conditions, as well as medical and research-related manipulations, can impact marmoset welfare. Research focus areas, including basic neuroscience, transgenics, and aging, involve additional implications for marmoset welfare. This manuscript provides a comprehensive review of factors that should be considered and mitigated as needed by clinical and research staff working with marmosets in biomedical research facilities to optimize the welfare of captive marmosets.

The Common Marmoset-Biomedical Research Animal Model Applications and Common Spontaneous Diseases

Marmosets are becoming more utilized in biomedical research due to multiple advantages including (1) a nonhuman primate of a smaller size with less cost for housing, (2) physiologic similarities to humans, (3) translatable hepatic metabolism, (4) higher numbers of litters per year, (5) genome is sequenced, molecular reagents are available, (6) immunologically similar to humans, (7) transgenic marmosets with germline transmission have been produced, and (8) are naturally occurring hematopoietic chimeras. With more use of marmosets, disease surveillance over a wide range of ages of marmosets has been performed. This has led to a better understanding of the disease management of spontaneous diseases that can occur in colonies. Knowledge of clinical signs and histologic lesions can assist in maximizing the colony's health, allowing for improved outcomes in translational studies within biomedical research. Here, we describe some basic husbandry, biology, common spontaneous diseases, and animal model applications for the common marmoset in biomedical research.

Feasibility of combined upper and lower gastrointestinal endoscopic biopsy in the common marmoset (Callithrix jacchus) to evaluate gastrointestinal diseases

BACKGROUND

Chronic gastroenteropathies, including gluten sensitivity and marmoset wasting syndrome, frequently occur in captive colonies of common marmosets (Callithrix jacchus). Early identification and diagnosis of affected animals are desirable. Endoscopic examination of the colon in marmosets is described, but the small intestine can harbor significant mucosal lesions not representing those in the colon. Evaluating the small intestine currently requires invasive surgical biopsies due to the small patient size, carrying a risk of severe complications.

METHODS

Endoscopic intubation and multisite biopsy of the duodenum/proximal jejunum are demonstrated in 10 marmosets under general anesthesia.

RESULTS

Esophagogastroduodenoscopy with colonoscopy efficiently aid in examining the gastrointestinal tract and obtaining an antemortem histologic diagnosis in marmosets with chronic gastrointestinal signs.

CONCLUSIONS

This minimally invasive technique is feasible in marmosets. Future investigations into the pathogenesis of chronic gastroenteropathies will benefit from these data, leading to improved animal welfare and better individual and colony health management.

Analysis of gut microbiome profiles in common marmosets (Callithrix jacchus) in health and intestinal disease

Chronic gastrointestinal (GI) diseases are the most common diseases in captive common marmosets. To understand the role of the microbiome in GI diseases, we characterized the gut microbiome of 91 healthy marmosets (303 samples) and 59 marmosets diagnosed with inflammatory bowel disease (IBD) (200 samples). Healthy marmosets exhibited "humanized," Bacteroidetes-dominant microbiomes. After up to 2 years of standardized diet, housing and husbandry, marmoset microbiomes could be classified into four distinct marmoset sources based on Prevotella and Bacteroides levels. Using a random forest (RF) model, marmosets were classified by source with an accuracy of 93% with 100% sensitivity and 95% specificity using abundance data from 4 Prevotellaceae amplicon sequence variants (ASVs), as well as single ASVs from Coprobacter, Parabacteroides, Paraprevotella, Phascolarctobacterium, Oribacterium and Fusobacterium. A single dysbiotic IBD state was not found across all marmoset sources, but IBD was associated with lower alpha diversity and a lower Bacteroides:Prevotella copri ratio within each source. IBD was highest in a Prevotella-dominant cohort, and consistent with Prevotella-linked diseases, pro-inflammatory genes in the jejunum were upregulated. RF analysis of serum biomarkers identified serum calcium, hemoglobin and red blood cell (RBC) counts as potential biomarkers for marmoset IBD. This study characterizes the microbiome of healthy captive common marmosets and demonstrates that source-specific microbiomes can be retained despite standardized diets and husbandry practices. Marmosets with IBD had decreased alpha diversity and a shift in the ratio of Bacteroides:Prevotella copri compared to healthy marmosets.

Immunohistochemical Characterization of a Duodenal Adenocarcinoma with Pulmonary, Hepatic and Parapatellar Metastases in a Common Marmoset (Callithrixjacchus)

An 11-year-old male common marmoset (Callithrix jacchus) presented with chronic, progressive weight loss and diarrhoea. Response to treatment with nutritional supplementation, antibiotics and immunosuppressants was modest and transient, and the animal was humanely euthanized. At necropsy, the proximal 8 cm of small intestine was diffusely pale with transmural thickening. The lungs contained coalescing tan, firm nodules measuring up to 4 mm in diameter. Histological examination revealed infiltrative mucinous adenocarcinoma of the duodenum with extensive metastases to the lungs, liver and left parapatellar adipose tissue. The mucinous matrix secreted by the primary and metastatic lesions was strongly periodic acid-Schiff positive. Warthin Starry staining for spirochaetes was negative. Pancytokeratin expression was attenuated in the primary tumour as well as in the metastases, which correlated to a poorly differentiated phenotype. To the authors' knowledge, this is the first report of a proximal duodenal adenocarcinoma with extensive metastatic disease in a common marmoset.

Changes in the faecal microbiome of pied tamarins (Saguinus bicolor) associated with chronic, recurrent diarrhoea and weight loss

Background

Chronic recurrent diarrhoea and weight loss is a common problem in captive callitrichids. These symptoms are common clinical features of marmoset wasting syndrome (MWS), a chronic enteric inflammation of unknown aetiology associated with mortality in captive marmosets. The unknown aetiology of the condition presents problems for conservation projects where affected colonies present higher mortality and lower birth rates. Since a role for the microbiome has been established in chronic enteric inflammation of other species it is possible that the intestinal microbiome undergoes similar changes during MWS.

Results

The faecal microbiome of pied tamarins (Saguinus bicolor) at Jersey Zoo was determined using 16S rRNA gene amplicon sequencing to compare the composition of the faecal microbiome of tamarins affected by chronic recurrent diarrhoea and weight loss with unaffected individuals. Affected individuals had a higher relative abundance of amplicon sequence variants assigned to Lactobacillus and Helicobacter jaachi while unaffected individuals had a higher relative abundance of some Lachnospiraceae and Ruminococcaceae.

Conclusions

Although Helicobacter has been shown to reside in healthy wild and captive marmosets and tamarins and appears to form part of the normal microbiota, the results of this study raise the prospect that certain species of Helicobacter may be associated with chronic, recurrent diarrhoea in captive callitrichids. The presence of Lactobacillus may also play a role in the development of MWS. Since depletion of Lachnospiraceae and Ruminococcaceae have been linked to chronic gastrointestinal inflammation in humans, this feature of the microbiome of affected tamarins provides another avenue of further research in the pathogenesis of MWS.

Supplementary Information

The online version contains supplementary material available at (doi:10.1186/s42523-020-00062-4).

Clinical Management of Gastrointestinal Disease in the Common Marmoset (Callithrix jacchus)

Gastrointestinal disease is a frequently encountered problem among captive common marmoset (Callithrix jacchus) colonies. Management can be challenging due to the number of etiologies responsible for gastrointestinal disease in this species, limitations on diagnostic capabilities, and lack of effective treatments. Understanding commonly described GI diseases in the captive marmoset can provide insight on the impact these diseases have on research studies and aid in the development of appropriate management strategies. A review of commonly encountered GI disease processes as well as routinely implicated causes of GI disease in the common marmoset are provided. Current strategies in clinical management of GI disease in the common marmoset, including approaches to colony health, diagnostic testing, and commonly employed treatments are discussed.

The profile of lipid metabolites in urine of marmoset wasting syndrome

Marmoset wasting syndrome (MWS) is clinically characterized by progressive weight loss. Although morbidity and mortality of MWS are relatively high in captive marmosets, its causes remain unknown. Lipid mediators are bioactive metabolites which are produced from polyunsaturated fatty acids, such as arachidonic acid (AA) and eicosapentaenoic acid. These lipid metabolites regulate a wide range of inflammatory responses and they are excreted into the urine. As urinary lipid profiles reflect systemic inflammatory conditions, we comprehensively measured the levels of 141 types of lipid metabolites in the urines obtained from healthy common marmoset (Callithrix jacchus) (N = 7) or marmosets with MWS (N = 7). We found that 41 types of metabolites were detected in all urine samples of both groups. Among them, AA-derived metabolites accounted for 63% (26/41 types) of all detected metabolites. Notably, the levels of AA-derived prostaglandin (PG) E2, PGF2α, thromboxane (TX) B2 and F2-isoprostanes significantly increased in the urine samples of marmosets with MWS. In this study, we found some urinary lipid metabolites which may be involved in the development of MWS. Although the cause of MWS remains unclear, our findings may provide some insight into understanding the mechanisms of development of MWS.

Novel gastrointestinal disease in common marmosets characterised by duodenal dilation: a clinical and pathological study

Common marmosets (Callithrix jacchus) are frequently used for biomedical research but gastrointestinal diseases have been major health problems to maintain captive marmosets. We have diagnosed a novel gastrointestinal disease in marmosets, as which we propose to call ‘marmoset duodenal dilation syndrome’; this disease is characterised by proximal duodenal obstruction and dilation. This study aimed to reveal the clinical and pathological findings of this syndrome and establish appropriate diagnostic imaging methods. Animals with the syndrome comprised 21.9% of the necropsy cases at the Central Institute for Experimental Animals in Kawasaki, Japan. The syndrome is characterised by clinical signs included vomiting, bloating, and weight loss. Grossly, all diseased animals exhibited significant dilation of the descending part of the duodenum, which contained a mixture of gas and fluid. The duodenal dilations were definitively diagnosed by contrast radiography. Moreover, a combination of plain radiography and ultrasonography was found to be a viable screening method for diagnosing duodenal dilation. The animals with duodenal dilation characteristically showed adhesions between the descending duodenum and ascending colon with chronic peritonitis. The cause of marmoset duodenal dilation syndrome remains unknown, but was likely multifactorial, including peritoneal adhesion, chronic ulcer, and feeding conditions in this study.

Measurement of the α1-proteinase inhibitor (α1-antitrypsin) of common marmoset and intestinal protein loss in wasting syndrome

Although wasting marmoset syndrome (WMS) is one of the biggest problems facing captive marmoset colonies, the mechanisms underlying its pathogenesis remain unclear. In our clinical experience, it is difficult to cure WMS-affected marmosets with severe hypoalbuminemia. Thus, the mechanisms underlying hypoalbuminemia in WMS must be understood. In the present study, we investigated whether intestinal protein loss, a known reason for hypoalbuminemia, occurs in this disease. Fecal α1-proteinase inhibitor (α1-PI, also known as α1-antitrypsin) has been used to diagnose intestinal protein loss in other species. To develop an assay system for this protein, marmoset α1-PI was purified from plasma and antibodies against it were developed using the purified protein. Using the antibodies, a sandwich enzyme-linked immunosorbent assay (ELISA) to measure marmoset α1-PI was developed, and its detection sensitivity for fecal samples was ∼20-fold higher than that of a commercial kit for human α1-PI. From this ELISA, the reference intervals for serum and feces of healthy marmosets were 0.87-1.85 mg/ml and 0.53-395.58 μg/g, respectively. The average concentrations of α1-PI in serum and feces of seven WMS-affected marmosets were 1.17 mg/ml and 1357.58 μg/g, respectively. Although there were no significant differences in the serum concentrations between healthy and WMS-affected marmosets, the fecal concentrations were significantly higher in WMS-affected marmosets than in healthy individuals, suggesting that intestinal protein loss occurs in WMS. Intestinal protein loss of WMS-affected marmosets was significantly attenuated with treatment, suggesting that it is one of the mechanisms involved in the hypoalbuminemia observed in WMS.

Fecal Concentrations of N-methylhistamine in Common Marmosets (Callithrix jacchus)

Chronic lymphocytic enteritis (CLE) is a frequent disease in common marmosets. However, no diagnostic test for early detection of CLE is available. Mast cells have an important role in gastrointestinal disease. The purpose of this study was to measure fecal concentrations of N-methylhistamine (NMH), a breakdown product of histamine metabolism, in common marmosets. A previously established NMH gas chromatography-mass spectrometry assay for canine feces and urine was used, and partial validation was performed. The reference intervals (n = 30) established for fecal NMH concentrations in common marmoset were 118.2 ng/g or less for a single fecal sample, 121.7 ng/g or less for the 3-d mean, and less than or equal to 167.5 ng/g for the 3-d maximum. Considerable day-to-day variation was observed in fecal NMH concentrations; the mean %CV was 42.2% (minimum, 7.1%; maximum, 141.4%). Fecal NMH concentrations were measured in 14 marmosets for which necropsy reports were available; 7 of the 8 marmosets with CLE and the 1 animal with lymphoma and ulcerative enteritis had increased fecal NMH concentrations. Increased fecal NMH concentrations may serve as a potential marker for CLE; however, further studies exploring the role of mast cells in marmosets with CLE are needed.

Colonic inflammation affects myenteric alpha-synuclein in nonhuman primates

Background: Parkinson's disease (PD) patients frequently present gastrointestinal (GI) dysfunction that, in many cases, predates the onset of motor symptoms. In PD, the presynaptic protein alpha-synuclein (α-syn) undergoes pathological changes, including phosphorylation and aggregation leading to the formation of Lewy bodies, which can be found in neurons of the enteric nervous system (ENS). Inflammation has been proposed as a possible trigger of α-syn pathology. Interestingly, patients with inflammatory bowel disease and irritable bowel syndrome, conditions associated with GI inflammation, are at higher risk of developing PD. Captive common marmosets (Callithrix jacchus) develop colitis, providing a natural platform to assess the relationship between α-syn pathology and GI inflammation. Materials and Methods: Sections of proximal colon from marmosets with colitis (n=5; 5.3±2.3 years old; 4 male) and normal controls (n=5; 4.1±1.6 years old; 1 male) were immunostained against protein gene product 9.5 (PGP9.5), human leukocyte antigen DR (HLA-DR), cluster of differentiation 3 (CD3), cluster of differentiation 20 (CD20), glial fibrillary acidic protein (GFAP), 8-hydroxy-2'-deoxyguanosine (8-OHdG), α-syn, and serine 129 phosphorylated α-syn (p-α-syn). Immunoreactivity of each staining in the myenteric plexus was quantified using NIH ImageJ software. Results: Marmosets with colitis had significantly increased expression of inflammatory markers (HLA-DR, p<0.02; CD3, p<0.008), oxidative stress (8-OHdG, p<0.05), and p-α-syn (p<0.02) and decreased expression of α-syn (p<0.04) in the colonic myenteric ganglia compared to normal, healthy controls. Conclusion: Colonic inflammation is associated with changes in α-syn expression and phosphorylation in the myenteric plexus of common marmosets. Future evaluation of the vagus nerve and brain of animals with colitis will be key to assess the contribution of colitis-induced ENS α-syn pathology to PD-like pathology in the brain.

Tranexamic Acid and Supportive Measures to Treat Wasting Marmoset Syndrome

Wasting marmoset syndrome (WMS) has high incidence and mortality rates and is one of the most important problems in captive common marmoset (Callithrix jacchus) colonies. Despite several reports on WMS, little information is available regarding its reliable treatment. We previously reported that marmosets with WMS had high serum levels of matrix metalloproteinase 9 (MMP9). MMP9 is thought to be a key enzyme in the pathogenesis of inflammatory bowel disease, the main disease state of WMS, and is activated by plasmin, a fibrinolytic factor. In a previous study, treating mice with an antibody to inhibit plasmin prevented the progression of inflammatory bowel disease. Here we examined the efficacy of tranexamic acid, a commonly used plasmin inhibitor, for the treatment of WMS, with supportive measures including amino acid and iron formulations. Six colony marmosets with WMS received tranexamic acid therapy with supportive measures for 8 wk. The body weight, Hct, and serum albumin levels of these 6 marmosets were increased and serum MMP9 levels decreased after this regimen. Therefore, tranexamic acid therapy may be a new and useful treatment for WMS.

Serum matrix metalloproteinase 9 (MMP9) as a biochemical marker for wasting marmoset syndrome

Use of the common marmoset (Callithrix jacchus) as a non-human primate experimental animal has increased in recent years. Although wasting marmoset syndrome (WMS) is one of the biggest problems in captive marmoset colonies, the molecular mechanisms, biochemical markers for accurate diagnosis and a reliable treatment remain unknown. In this study, as a first step to finding biochemical marker(s) for the accurate diagnosis of WMS, we conducted blood cell counts, including hematocrit, hemoglobin and platelets, and examined serum chemistry values, including albumin, calcium and levels of serum matrix metalloproteinase 9 (MMP9), using a colony of marmosets with and without weight loss. MMP9 is thought to be an enzyme responsible for the degradation of extracellular matrix components and participates in the pathogenesis of inflammatory conditions, such as human and murine inflammatory bowel disease, which, like WMS, are characterized histologically by inflammatory cell infiltrations in the intestines. The values of hematocrit and hemoglobin and levels of serum albumin and calcium in the WMS group were significantly decreased versus the control group. The platelet values and serum MMP9 concentrations were increased significantly in the WMS group compared with the control group. MMP9 could be a new and useful marker for the diagnosis of WMS in addition to hematocrit, hemoglobin, serum albumin and calcium. Our results also indicate that MMP9 could be a useful molecular candidate for treatment.