Figure 6. CDK4/6 and EZH2 inhibition prevents IMQ- and IL-36–mediated psoriasis-like skin lesions in vivo.

(A) Ear thickness measurements during topical treatment of mice with IMQ with or without abemaciclib (Abe; 10 μL of a 2% solution) or the EZH2 inhibitor CPI-169 (CPI, 10 μL of a 5% solution). n = 6 mice per group ± SEM. (B) H&E staining of untreated (Ctrl), IMQ-, IMQ and Abe–, or IMQ and CPI–treated ears. Scale bars: 100 μm. (C) Phospho-RB (pRB) and H3K27me3 staining after 6 days of treatment validated effective CDK4/6 and EZH2 inhibition, respectively. Scale bars: 40 μm. (D) Infiltrating immune cells in mouse ears at day 6 of treatment were quantified as follows: Neutrophils: CD45⁺, CD11b⁺, Ly6G⁺; macrophages: CD45⁺, CD11b⁺, F4/80⁺; T cells: CD45⁺, CD3⁺, and αβ-TCR⁺ or γδ-TCR⁺. n = 3 mice per group ± SEM. (E) Flow cytometry analysis of IMQ-treated or IMQ and CPI-169–treated mouse ears at day 6. (F) Protein levels in untreated (Ctrl) and treated mouse skin tissue at day 6. (G) Ear thickness of IL-36α–treated mice at day 5. Ears of mice were daily treated by intradermal injections with 1 μg IL-36α. Control mice received injections with PBS. Additionally, mice received topical treatment with ethanol as control (Veh), 2% abemaciclib (Abe), or 5% CPI-169 (CPI). n = 6 mice per group ± SEM. (H) H&E staining of PBS- or IL-36α–treated ears at day 5. Scale bars: 100 μm. (I) Immunoblot analysis of IκBζ, EZH2 phosphorylation (pEZH2 T345) and STAT3 activation (pSTAT3 Y705) in treated mouse skin tissue at day 5. pRB and H3K27me3 were analyzed as positive controls for drug action. Significance was calculated using a 1-way ANOVA for multiple groups and a 2-tailed Student’s t test for comparing 2 groups: *P < 0.05; **P < 0.01; ***P < 0.001.