Nitrogen Mustard Induces DNA Damage and Structural Changes in Mouse Skin Hair Follicles

Abstract

Nitrogen mustard (NM) is a potent skin vesicant. Evidence suggests that the pilosebaceous unit in the skin is a target for NM. To assess this, we analyzed changes in hair follicles and sebaceous glands in mouse skin following NM exposure. Dorsal skin of female CD-1 mice was exposed to 77 ng NM for 6 min, and harvested 1-5 d later. Control (CTL) skin contained sebaceous glands expressing fatty acid synthase (FAS), a marker for sebum production. Proliferating cell nuclear antigen (PCNA, marker of cellular division) and keratin-10 (K-10, marker of cellular differentiation) were expressed in the hair outer root sheath (ORS) and infundibulum of CTL skin. One d post NM, FAS, PCNA and K-10 expression was decreased in sebaceous glands, ORS, and infundibulum, respectively, while phospho-H2A.X, a marker for double strand DNA breaks, was evident in the ORS and basal epidermis. By 2 d, an eschar formed; there were reduced numbers of pilosebaceous units within the eschar and this was associated with increased expression of phospho-H2A.X in hyperplastic interfollicular epidermis (IFE). Three days post-NM, low levels of FAS, PCNA, and K-10 were expressed in the pilosebaceous units at the wound edge. By 4 d, small pilosebaceous units within the neo-epidermis expressed increased levels of FAS, PCNA and K-10, while decreased levels of phospho-H2A.X were observed within the IFE. By 5 d, wound healing was evident with increased FAS and K-10 expression in the sebaceous glands and infundibulum, respectively. PCNA was also increased in the ORS, while phospho-H2A.X was decreased. These data indicate that the pilosebaceous unit is an important target contributing to NM-induced skin injury. Support: NIH AR055073.