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INVESTIGATIVE REPORT ActaDV ActaDV Advances in dermatology and venereology Acta Dermato-Venereologica
Tofacitinib Represses the Janus Kinase-Signal Transducer and Activators of Transcription Signalling Pathway in Keratinocytes
Ankit SRIVASTAVA 1, Mona STÅHLE 1, 2, Andor PIVARCSI 1 and Enikö SONKOLY 1, 2
1
Department of Medicine, Dermatology and Venereology Unit, Karolinska Institutet, and 2 Unit of Dermatology, Karolinska University Hospital, Stockholm, Sweden
Tofacitinib is a Janus kinase( JAK) inhibitor, which has shown efficacy in treating psoriasis. The mode of action of tofacitinib is not completely understood but it has been thought to be mediated by the inhibition of CD4 + T-cell activation. Here, we investigated whether the molecular targets of tofacitinib are expressed in keratinocytes, and whether tofacitinib can modulate the activity of the JAK / Signal Transducer and Activators of Transcription( STAT)-pathway in keratinocytes. Transcriptomic profiling of human keratinocytes treated with IL-22 in combination with tofacitinib revealed that tofacitinib could prevent the majority of IL-22-mediated gene expression changes. Pathway analysis of tofacitinib-regulated genes in keratinocytes revealed enrichment of genes involved in the JAK / STAT signalling pathway. Quantitative real-time-PCR confirmed the upregulation of S100A7 and downregulation of EGR1 expression by IL-22, which was prevented by tofacitinib pre-treatment. These results indicate a direct effect of tofacinitib on keratinocytes, which can have relevance for systemic as well as for topical treatment of psoriasis with tofacitinib.
Key words: JAK-STAT( Janus kinase-signal transducer and activators of transcription); tofacitinib; keratinocyte; psoriasis; cytokines.
Accepted May 4, 2018; Epub ahead of print May 8, 2018 Acta Derm Venereol 2018; 98: 772 – 775.
Corr: Enikö Sonkoly, Dermatology and Venereology Unit, Department of Medicine Solna, Karolinska Institutet, CMM L8:02, SE-17176 Stockholm, Sweden. E-mail: eniko. sonkoly @ ki. se.
Psoriasis is a chronic immune-mediated skin disease that affects 2 – 3 % of the population worldwide( 1). The Janus kinase / signal transducer and activators of transcription( JAK / STAT) pathway is central in the pathogenesis of psoriasis( 2), as evidenced by genetic association of STAT3 with psoriasis( 3), and the essential role of STAT3 in psoriasis-related cytokine signalling pathways( interleukins [ IL ]-6, IL-10, IL-20, IL-22, and IL-23), and in differentiation of Th17 cells, a key cell type in psoriasis( 3, 4). Tofacitinib( CP-690,550), a potent inhibitor of JAK1 and JAK3, and to some extent to JAK2 and tyrosine kinase 2( Tyk2), is an immunomodulatory drug to treat inflammatory diseases including psoriasis( 2). In clinical trials, tofacitinib has shown efficacy for plaque psoriasis both as an oral formulation in two phase
SIGNIFICANCE
Psoriasis is the most common chronic inflammatory skin disease in adults. Tofacitinib is an immunomodulating drug that has shown effect for the treatment of psoriasis in clinical trials. The mode of action through which tofacitinib exerts its effects is not fully understood. Previous studies reported that the effects of tofacitinib are mediated by the inhibition of T-cell activation. In this study we found that tofacitinib can efficiently repress inflammatory pathways in skin cells( keratinocytes), indicating that the effect of topical or oral tofacitinib treatment can partially be mediated via keratinocytes in addition to immune cells.
III trials, and as an ointment formulation in a phase II trial( 2). The primary mode of action of tofacitinib has been thought to be the modulation of JAK-STAT signalling in T cells, which is involved in IL-23 signalling, Th17 differentiation and CD4 + T-cell activation. However, in addition to T cells, JAK / STAT signalling is also active in the epidermis of psoriasis lesions( 2, 4), and the importance of epidermal JAK / STAT signalling is supported by the psoriasis-like skin phenotype in a mouse model with keratinocyte-specific overexpression of STAT3( 5). Thus, tofacitinib may also regulate cytokine signalling in keratinocytes. The aim of this study was to test the hypothesis that tofacitinib has direct effects on cytokine signalling in keratinocytes.
METHODS Cell culture and treatments
Human primary keratinocytes from adult skin were obtained from Thermo Fisher Scientific( Stockholm, Sweden) and cultured in Epilife medium( Thermo Fisher Scientific). IL-22( 20 ng / ml, R & D systems, Minneapolis, Minnesota, USA) and tofacitinib( 0.6 µ M, Pfizer, Stockholm, Sweden) were used to treat primary keratinocytes. Dimethyl sulphoxide was used as a vehicle control for tofacitinib. Four-mm punch biopsies were collected from healthy volunteers( n = 5), non-lesional and lesional skin of patients( n = 6) diagnosed with chronic plaque psoriasis, and epidermal CD45 – cells( mainly keratinocytes) were isolated as described previously( 6). Peripheral blood mononuclear cells( PBMCs) were isolated from blood, by using Ficoll( GE Healthcare, Stockholm, Sweden) density separation. The collection of human samples was performed according to the principles of the Declaration of Helsinki and all subjects provided written informed consent. doi: 10.2340 / 00015555-2960 Acta Derm Venereol 2018; 98: 772 – 775
This is an open access article under the CC BY-NC license. www. medicaljournals. se / acta Journal Compilation © 2018 Acta Dermato-Venereologica.