Figure 4. Increased inflammatory response to UV light and imiquimod in mice after targeted deletion of HDAC 8 or HDAC9.

(A) MAP2K3 expression in human inflammatory skin disorders. Bar plots of Z scores (Y-axis) for skin taken from human healthy controls and lesional skin taken from patients with UV radiation, psoriasis, AD, and Acne Vulgaris were analyzed. Data were obtained from a public data set (GEO accession no. GDS2381, GSE13355, GDS968, and GDS2478). (Student’s t-test, two-sided). (B) Ifnb1 and Tslp gene expression in the skin of K14-Cre Hdac8 ^fl/fl and K14-Cre Hdac9 ^fl/fl mice or controls as measured by qPCR 24 hours after UVB exposure (200 mJ/cm2). (N=3; one-way ANOVA). (C) Ifnb1 gene expression in the skin of controls, K14-Cre Hdac9 ^fl/fl and double knockout K14-Cre Hdac8/9 ^fl/fl 24 hours after UV radiation. (N=3; one-way ANOVA). (D) Ifnb1 gene expression (N=3; one-way ANOVA) and ear swelling response after 7 days of topical imiquimod application to controls, K14-Cre Hdac9 ^fl/fl and double knockout K14-Cre Hdac8/9 ^fl/fl mice. (controls N=3, K14-Cre Hdac9 ^fl/fl mice N=3 and double knockout K14-Cre Hdac8/9 ^fl/fl mice N=4; one-way ANOVA). (E) Flow cytometry analysis of CD86 expression in LCs isolated from the skin 24 hours after UVB exposure or after 7 days of IMQ application. Representative flow cytometry plots are shown to the left and the mean fluorescence intensity of CD86 is shown to the right. (UV radiation experiment (N=3); one-way ANOVA, IMQ application experiment (N=4); Student’s t-test) (F,G) Flow cytometry analysis of cells gated from CD45⁺TCRβ1⁺ cells in the skin 24 hours after UVB exposure. Representative flow cytometry plots are shown as the number of CD4⁺ or CD8⁺ T-cells in the skin is shown to the right (N=3; Student’s t-test). (H,I) Flow cytometry analysis of CD45⁺TCRβ1⁺ cells in the skin 24 hours after the final IMQ application on day 7. Representative flow cytometry plots are shown in (H), and the number of CD4⁺ or CD8⁺ cells in the skin is shown in (I) (N=4; Student’s t-test).The results are expressed as the mean ± standard deviation (SD). Each dot represents an individual mouse. *, P < 0.05. Data are representative of three independent experiments.