Figure 6.
Limited effect of deficiency of TNF, IL-1, or macrophage depletion on cutaneous disease development in the caspase-8–null skin. (A) Gross appearance of TNF−/−Casp-8F/+K5-Cre and TNF−/−Casp-8F/−K5-Cre mice at different ages. (Arrows point to skin lesions at P7 and P30.) There is progressive hyperkeratosis, scaliness, and hair loss, with ulceration in some cases (middle). (B) Survival curves for colonies of Casp-8F/−K5-Cre (green; 62 mice), IL1α−/−IL1β−/−Casp-8F/−K5-Cre (yellow; 55 mice), TNF−/−Casp-8F/−K5-Cre (red; 37 mice), and IL1α−/−IL1β−/−TNF−/−Casp-8F/−K5-Cre mice (blue; 42 mice). (C) Microscopic features of late-stage disease in a TNF−/−Casp-8F/−K5-Cre mouse at P60. There is diffuse epidermal hyperplasia, dermal fibrosis, adnexal loss, and accumulation of melanocytes and melanophages (pigmentary incontinence). H&E; Bar, 100 µm. (D) Microscopic appearance of the skin of IL1α−/−IL1β−/−TNF−/−Casp-8F/+K5-Cre and IL1α−/−IL1β−/−TNF−/−Casp-8F/−K5-Cre mice at P7. H&E; Bars, 100 µm. (E) Macrophage content (anti-F4/80 staining, left) and microscopic appearance (H&E, right) of the skin of Casp-8F/−K5-Cre mice injected with control liposomes (top) and clodronate-containing liposomes (bottom) at P5. Bars, 100 µM. (F) Effect of macrophage depletion on gene expression changes in the Casp-8F/−K5-Cre epidermis. To deplete dermal macrophages, mice were injected subcutaneously every other day, starting at P0, with clodronate-loaded liposomes or PBS-loaded liposomes (control). RNA was isolated from the epidermis at P5 and analyzed for expression of CSF1, a macrophage marker (left), and of four inflammation markers found to be increased in Casp-8F/−K5-Cre mice (right). Mean values ± SD for three experimental/control mice pairs are shown. The data presented in A, C, D, E, and F are representative of analyses of 10, 4, 7, 15, and 5 mice, respectively. The data in E and F are the results of three independent experiments in both cases.