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

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.

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.

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.

Reduced differentiation of intestinal epithelial cells in wasting marmoset syndrome

Wasting marmoset syndrome (WMS) is a serious disease in captive common marmoset (Callithrix jacchus) colonies. Because of the high mortality rates, elucidation of the underlying mechanisms is essential. In this study, we compared the histopathology, the number of each epithelial cell in the jejunum and colon, and the expression patterns of some molecular markers between healthy and WMS-affected marmosets. Atrophy of villi in the jejunum and mononuclear cell infiltration in the lamina propria were observed in the intestinal tract of WMS-affected marmosets. Although the numbers of transient amplifying cells and tuft cells were increased, the number of goblet cells was obviously decreased in the jejunum and colon of WMS-affected marmosets compared to healthy marmosets. In addition, the number of enterocytes in the jejunum was decreased in WMS animals. There was no apparent difference in the numbers of stem cells, enteroendocrine cells, or Paneth cells. The expression of β-catenin and Tcf7l2 was increased in WMS, and the co-existence of β-catenin and Tcf7l2/Cyclin D1 was observed around the crypts in WMS-affected marmosets. These findings suggest that cell proliferation continues, but cell differentiation is halted in the intestinal tract due to the enhanced β-catenin/Tcf7l2/Cyclin D1signaling pathway in WMS, which results in malfunction of the villus and mucosa.

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.

Serum Cobalamin and Folate Concentrations in Common Marmosets (Callithrix jacchus) with Chronic Lymphocytic Enteritis

Serum cobalamin and folate concentrations can serve as surrogate markers of gastrointestinal disease in dogs and cats, where they can have diagnostic, therapeutic, and prognostic implications. Chronic disease of the gastrointestinal tract, particularly chronic lymphocytic enteritis (CLE), occurs frequently in captive common marmosets. The aims of this study were to validate a commercially available assay for measuring serum cobalamin and folate concentrations in common marmosets, to establish reference intervals for these analytes in healthy marmosets, and to measure serum concentrations in common marmosets with CLE. The commercial assay was linear, accurate, precise, and reproducible for the measurement of serum cobalamin and folate concentrations in common marmosets. In healthy marmosets, the serum cobalamin concentration ranged from 322 to 2642 pg/mL (n = 35) and serum folate concentration from 54.8 to 786.4 ng/mL (n = 37). Low serum folate concentrations were moderately sensitive (greater than 70%) for CLE, and low serum cobalamin concentrations were moderately (greater than 70%) specific for CLE. Both serum cobalamin and folate concentrations were relatively unchanged in marmosets during 120 to 220 d. Serum cobalamin and folate concentrations were stable for approximately 7 y when samples were stored at -80 °C. Additional studies are warranted to further study the clinical implications of low serum cobalamin and folate concentrations in common marmosets.

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.

Larger cages with housing unit environment enrichment improve the welfare of marmosets

The provision of adequate space for laboratory animals is essential not only for good welfare but accurate studies. For example, housing conditions for primates used in biomedical research may negatively affect welfare and thus the reliability of findings. In common marmosets (Callithrix jacchus), an appropriate cage size enables a socially harmonious family environment and optimizes reproductive potential. In this study, we investigated the effects of cage size on body weight (BW), behavior, and nursing succession in the common marmoset. Large cages (LCs) with environment enrichment led to an increase in BW while small cages (SCs) caused stereotypic behaviors that were not observed in LCs. In addition, the BW of infants increased with aging in LCs. Our findings indicate that the welfare of marmosets was enhanced by living in LCs. Research on non-human primates is essential for understanding the human brain and developing knowledge-based strategies for the diagnosis and treatment of psychiatric and neurological disorders. Thus, the present findings are important because they indicate that different cages may influence emotional and behavioral phenotypes.

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.