Cutaneous inflammatory disorder in integrin alphaE (CD103)-deficient mice.

The integrin alpha(E)beta(7) is thought to play an important role in the localization of mucosal, but not of cutaneous T lymphocytes. Thus, it was surprising that 89% of adult alpha(E)(-/-) mice on the 129/Sv x BALB/c background developed inflammatory skin lesions without an apparent infectious etiology. Skin inflammation correlated with alpha(E) deficiency in mice with a mixed 129/Sv x BALB/c background, but not in mice further backcrossed to BALB/c and housed in a second animal facility. These studies suggested that alpha(E) deficiency, in combination with other genetic and/or environmental factors, is involved in lesion development. The lesions were infiltrated by CD4(+) T cells and neutrophils, and associated with increased expression of inflammatory cytokines. Furthermore, skin inflammation resulted from transfer of unfractionated alpha(E)(-/-) splenocytes into scid/scid mice, but not from transfer of wild-type splenocytes, suggesting that the lesions resulted from immune dysregulation. We also studied the role of alpha(E)beta(7) in a murine model of hyperproliferative inflammatory skin disorders that is induced by transfer of minor histocompatibility-mismatched CD4(+)/CD45RB(high) T cells into scid/scid mice under specific environmental conditions. Under housing conditions that were permissive for lesion development, transfer of alpha(E)-deficient CD4(+)/CD45RB(high) T cells significantly exacerbated the cutaneous lesions as compared with lesions observed in mice reconstituted with wild-type donor cells. These experiments suggested that alpha(E)-expressing cells play an important role during the course of cutaneous inflammation. In addition, they suggest that alpha(E)beta(7) deficiency, in combination with other genetic or environmental factors, is a risk factor for inflammatory skin disease.