Ulcerative dermatitis in C57BL/6 mice lacking stearoyl CoA desaturase 1.

Ulcerative dermatitis (UD) is a common cause of morbidity and euthanasia in mice with a C57BL/6 (B6) background. The purposes of the current study were to determine whether UD lesions could be reliably produced in B6 mice lacking stearoyl-CoA desaturase 1 (SCD1(-/-) mice), to ascertain whether the UD lesions in SCD1(-/-) mice were similar to those found in other B6 mice, and to characterize the cell invasion phenotype of Staphlococcus xylosus cultured from the lesions. S. xylosus isolates from the environment and human skin were used as controls. SCD1(-/-) (n = 8 per group) and nontransgenic B6 control mice (n = 22 mice pooled from 3 groups that received different concentrations of conjugated linoleic acid) were fed standard rodent chow or a semipurified diet (NIH AIN76A) for 4 wk. Samples from other B6 mice with UD (field cases; n = 7) also were submitted for histology and culture. All of the SCD1(-/-) mice developed UD lesions by 4 wk on NIH AIN76A. None of SCD1(-/-) fed standard rodent chow and none of the wildtype B6 mice fed NIH AIN76A developed UD. Supplementation with conjugated linoleic acid did not affect ulcerogenesis. UD lesions in SCD1(-/-) mice and field cases were grossly and histologically similar. S. xylosus was isolated from SCD1(-/-) mice with UD (71%) and field cases of UD (43%). These isolates were the most cell-invasive, followed by the environmental isolate, and finally the human skin isolate. Our results provide a basis for further pathologic and clinical study of UD.