Question: What is the importance of Janus Kinases in dermatology?

Context:
Tofacitinib, an oral Janus kinase inhibitor, is being investigated as a treatment for moderate-to-severe chronic plaque psoriasis
Taken together, our results provided new evidence for the effectiveness of EGCG in vitiligo treatment and supported JAK2 as a molecular target for vitiligo medicine development.
Notably, three patients treated with oral ruxolitinib, an inhibitor of JAK1 and JAK2, achieved near-complete hair regrowth within 5 months of treatment, suggesting the potential clinical utility of JAK inhibition in human AA.
Jaks have recently gained significant attention as therapeutic targets in inflammation and autoimmunity, and several Jak inhibitory small molecules have been developed. 
Efficacy and safety data suggest that some of these oral Jak inhibitors as well as their topical formulations may soon enter the daily clinical practice for treating patients with psoriasis, lupus erythematosus or other inflammatory skin diseases. 
Janus kinase 3 (Jak3) is a nonreceptor tyrosine kinase essential for signaling via cytokine receptors that comprise the common gamma-chain (gammac), i.e., the receptors for IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21.
Systemically administered pharmacological inhibitors of Janus kinase (JAK) family protein tyrosine kinases, downstream effectors of the IFN-γ and γc cytokine receptors, eliminated the IFN signature and prevented the development of AA, while topical administration promoted hair regrowth and reversed established disease
Tofacitinib is an oral Janus kinase inhibitor being investigated for psoriasis.We sought to report longer-term tofacitinib efficacy and safety in patients with moderate to severe psoriasis.Data from 2 identical phase-III studies, Oral-treatment Psoriasis Trial Pivotal 1 and 2, were pooled with data from these patients in an ongoing open-label long-term extension study.
Plaque psoriasis is a chronic and often debilitating skin disorder and proinflammatory cytokines are known to play a key role in the disease process.To evaluate the safety and efficacy of baricitinib, an oral Janus kinase (JAK) 1/JAK2 inhibitor, in patients with moderate-to-severe psoriasis in a randomized, double-blind, placebo-controlled, dose-ranging phase 2b study.Patients were randomized (n = 271) to receive placebo or oral baricitinib at 2, 4, 8 or 10 mg once daily for 12 weeks (Part A).
Oclacitinib (Apoquel(®) ) inhibits the function of a variety of pro-inflammatory, pro-allergic and pruritogenic cytokines that are dependent on Janus kinase enzyme activity.
the Janus kinase/signal transducer and activator of transcription (JAK-STAT) cytokine signalling mechanism in disease pathogenesis. This signalling pathway is involved in haematopoiesis and immune development. Mutations in genes regulating JAK-STAT signalling can cause common inflammatory disorders and myeloproliferative disorders. JAK and STAT inhibitors are new management tools for disorders such as myelofibrosis and rheumatoid arthritis. Evidence suggests that the cytokine components of the JAK-STAT pathways play a crucial role in common skin disorders, including psoriasis and atopic dermatitis
Tofacitinib is an oral Janus kinase inhibitor that improves clinical measures of psoriasis

Answer: Janus Kinase (JAK) is active in many skin diseases and recent evidence show that inhibitors of JAK kinase could be used to treat vitiligo, psoriasis, lupus, alopecia areata and other inflammatory skin diseases.
Tofacitinib, an oral Janus kinase inhibitor, is being investigated as a treatment for moderate-to-severe chronic plaque psoriasis