Cutaneous and Gastrointestinal Dysbiosis in Immunodeficient Mice

Abstract

The health of immunodeficient rodent strains used for tumor modeling is often challenged by increased susceptibility to overgrowth of organisms which are not normally pathogenic in immunocompetent mice. Herein, we describe spontaneously occurring skin and gastrointestinal lesions in a cohort of immunodeficient mice. In the current case series, NOD‐SCID‐gamma and athymic nude mice presented clinically moribund with thickened, scaly, erythematous cutaneous lesions covering the head, neck, and trunk. Examination of hematoxylin and eosin (H&E) stained sections revealed marked acanthosis and orthokeratotic hyperkeratosis with large numbers of coccobacilli in the lamellar layers of keratin of epidermis in affected animals. Variable mild dermal inflammation was present. Gram‐positive pleomorphic rods were cultured from skin and identified as Corynebacterium bovis via qPCR. Staphylococcus xylosus was also cultured in a case that had abundant Gram‐positive cocci bacteria in the skin. C. bovis and S. xylosus have been associated with a “scaly skin” syndrome in immunodeficient mice. Acanthosis and hyperkeratosis with coccobacilli were also present in the keratinized portion of the stomach. Additionally, affected mice frequently had massive proliferation of segmented filamentous bacteria (SFB) in the small intestine. Impaired immune responses in immunodeficient strains may lead to a constellation of clinical signs and pathology which represent a form of dysbiosis. Investigation of dysbiosis in immunodeficient mice used in cancer research is important for maintaining the health of the colony and for accurate interpretation of research outcomes.Support or Funding InformationSupported by the NIH/NCI under award number P30CA016672 and the Research Animal Support Facility‐Houston.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.