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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 .