Selective Immunomodulation of Inflammatory Pathways in Keratinocytes by the Janus Kinase (JAK) Inhibitor Tofacitinib: Implications for the Employment of JAK-Targeting Drugs in Psoriasis

Figure 3

Tofacitinib regulates proliferation, differentiation, and apoptosis of IFN-γ- and IL-22- but not TNF-α-treated keratinocytes. Proliferation of keratinocyte cultures untreated or treated with 5 μM tofacitinib, either in the presence or absence of IFN-γ, IL-22, or TNF-α, was analysed by Trypan blue exclusion test (a), which was performed after 48 h of culture. Data are expressed as total cell number ± SD. . (b) Keratin 1 (KRT1), loricrin, and p63 were analysed by WB by using protein lysates obtained from keratinocyte cultures grown at 100% confluency (0 d) or for additional four days (4 d), in the presence or absence of tofacitinib and IFN-γ or IL-22. Graphs show densitometric values ± SD of KRT1, loricrin, or p63. Data are expressed as densitometric units, expressed as fold induction (F.I.) of treated vs. untreated samples, which were given a value of 1. . (c) Apoptosis of cultured keratinocytes treated with 5 μM tofacitinib in the presence or absence of IFN-γ, IL-22, or the proapoptotic stimulus TNF-α for 48 h was examined by measuring Annexin (Ann V)/propidium iodide (PI) fluorescence through flow cytofluorimetry. A representative experiment of three performed with two different psoriatic keratinocyte strains is shown, with numbers indicating the percentage of PI⁺ (upper left), Ann V⁺ (lower right), PI/Ann V⁺ (upper right), or negative (lower left) cells.

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