Spontaneous glomerular mesangial lesions in common marmoset monkeys (Callithrix jacchus): A benign non-progressive glomerulopathy

Background: Common marmosets are known to develop an IgM glomerulopathy, which has been linked with 'wasting marmoset' syndrome. This study investigated renal pathology in a colony of marmosets, with and without weight loss. Methods: Renal histology, immunofluorescence, and electron microscopy were performed on marmosets euthanized for research or for weight loss. Serum and urine biochemistry were measured during life and at euthanasia. Results: Histology from 25 adult marmosets (19 research and 6 weight loss) showed mesangial expansion in the majority of glomeruli. Mesangial changes correlated with electron-dense deposits and IgM deposition by immunofluorescence; negligible other pathology was seen. Glomerular basement membrane thickness appeared increased compared to reported human measurements. Low-grade proteinuria was present in all animals, but did not progress. Renal function was normal in all animals. Conclusions: Marmosets develop a glomerulopathy characterized by mesangial expansion, IgM deposition, and proteinuria. This is a benign occurrence and not specifically associated with weight loss.