Figure 2: Aldara induces apoptosis and cytokine upregulation.

(a) Transmission electron microscopy of untreated skin of WT129 mice, and 12 h and 24 h after one topical Aldara application, respectively. The arrows indicate: (A) early-stage apoptotic pyknotic constricted nucleus, (B) intact mitochondria, (C) late-stage apoptotic pyknotic constricted nucleus and (D) residual body. Scale bar, 5 μm for × 3000 magnifications and 10 μm for × 7000 magnifications, respectively. (b) Quantification of epidermal TUNEL-positive cells 24 h after one topical Aldara application of the indicated mouse strains. Data are derived from following experimental groups: untreated C57BL/6 and TLR7-ko n=4, WT129 n=3, A129, n=2; treated C57BL/6, TLR7-ko, WT129 n=5, A129 n=4, and from 2–3 independent experiments, statistical significance displayed for counts of Aldara-treated samples compared with untreated samples of the same strain; error bars represent s.d. Display of fold increases in mRNA expression levels of various keratinocyte mitogens in Aldara-treated skin compared with untreated skin of levels of various keratinocytes mitogens (c), Il-1α (d) and G-csf (e) in the skin of WT129, A129, C57BL/6 and TLR7-ko mice (d,e) and C57BL/6 (c) assessed by qPCR 24 h after one topical Aldara treatment. n>4, 2–3 independent experiments, statistical significance displayed for ΔCT values of Aldara-treated compared with untreated samples of the same strain; *P<0.05, **P<0.01 and ***P<0.001 (unpaired Student’s t-test). FGF7, fibroblast growth factor 7; GM-CSF, granulocyte-macrophage colony-stimulating factor; HGF, hepatocyte growth factor; TGFα, transforming growth factor α.