Figure 5. Aberrance in markers of epidermal differentiation during aging.

Changes in the epidermal differentiation program of the aging Inv-Cldn6-CΔ196 transgenic epidermis were evaluated by immunofluorescence and compared to their age-matched wild type counterparts (samples from 3-month-old mice are shown – left panel); their expression/localization in dermatitis-affected areas is also indicated (right panel). K14 was expressed throughout the basal and suprabasal compartments in the aging Inv-Cldn6-CΔ196 epidermis (A), while K15 remained restricted to basal cells (B). The zone of K1 expression was expanded in the 3-month-old transgenic epidermis (C); however, neither K6- (D) nor K17-positive (E) cells were observed. An expanded zone of expression, and improper packing, of involucrin (F) and filaggrin (G) suggested perturbations in terminal differentiation program of the aged Inv-Cldn6-CΔ196 epidermis. In the dermatitis-affected areas, K14 (H) expression was expanded far into the suprabasal compartment, while K15 was only sporadically observed (I). A punctate K1 localization was evident throughout the thickened suprabasal zone of the dermatitis-affected Inv-Cldn6-CΔ196 epidermis (J), and K6- (K) and K17-positive (L) basal and suprabasal cells were observed. In addition, involucrin (M) and filaggrin (N) expression compartments were also expanded, with obvious packing defects evident.