Atopic dermatitis (AD) is a chronic, inflammatory, pruritic form of dermatosis with heterogeneous manifestations that can substantially affect patients' quality of life. AD has a complex pathogenesis, making treatment challenging for dermatologists. The Janus kinase (JAK)–signal transducer and activator of transcription (STAT) pathway plays a central role in modulating multiple immune axes involved in the immunopathogenesis of AD. In particular, Th2 cytokines, including interleukin (IL)-4, IL-5, IL-13, IL-31, and thymic stromal lymphopoietin, which contribute to the symptoms of chronic inflammation and pruritus in AD, are mediated by JAK–STAT signal transduction. Furthermore, JAK–STAT is involved in the regulation of the epidermal barrier and the modulation of peripheral nerves related to the transduction of pruritus. Targeting the JAK–STAT pathway may attenuate these signals and show clinical efficacy through the suppression of various immune pathways associated with AD. Topical and oral JAK inhibitors with variable selectivity have emerged as promising therapeutic options for AD. Notably, topical ruxolitinib, oral upadacitinib, and oral abrocitinib were approved by the U.S. Food and Drug Administration for treating patients with AD. Accordingly, the present study reviewed the role of JAK–STAT pathways in the pathogenesis of AD and explored updated applications of JAK inhibitors in treating AD.

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Background Vaccination has been promoted to control viral transmission in response to the coronavirus disease 2019 (COVID-19) pandemic. Cases of new-onset or exacerbation of psoriasis, an immune-mediated inflammatory disease, were reported following COVID-19 vaccination. However, a comprehensive review examining the association between COVID-19 vaccination and the occurrence or exacerbation of psoriasis has yet to be performed. Objective The aim of this systematic review is to investigate the demographics, clinical variables, and outcomes associated with psoriasis following COVID-19 vaccination. Methods A systematic literature search was conducted using the PubMed, Embase, Web of Science, and Cochrane databases from database inception to April 25, 2022. The review included studies with relevant terms, including ‘psoriasis,’ ‘psoriasis vulgaris,’ ‘guttate psoriasis,’ ‘pustular psoriasis,’ ‘palmoplantar pustulosis,’ ‘psoriatic erythroderma,’ ‘psoriatic arthritis,’ ‘COVID-19,’ and ‘vaccine.’ We included all studies reporting at least one patient who developed new-onset psoriasis or experienced a psoriasis flare following at least one dose of any COVID-19 vaccine. A flare was defined as the worsening of disease conditions after vaccination according to the study by Gregoire et al. The appraisal tool described by Murad et al. was used to assess the quality of case reports and series, whereas the National Institute of Health quality assessment tool was used to assess observational studies. Results The initial search yielded 367 results, including 7 studies reporting new-onset psoriasis, 32 studies reporting psoriasis flares, and 4 studies reporting both. The most commonly observed psoriasis subtype was plaque-type psoriasis. mRNA vaccines, including those produced by Moderna and BioNTech/Pfizer, were frequently associated with subsequent psoriasis episodes. First, second, and third vaccine doses were associated with psoriasis incidents, with the second dose most frequently associated with psoriasis flares. Delayed onset was observed, ranging from 2 to 21 days in the new-onset group and from 1 to 90 days in the flare group. Most patients experienced favorable outcomes, with improvement or resolution occurring within 3 days to 4 months. Conclusions Both new-onset psoriasis and psoriasis flares were reported as cutaneous adverse events following COVID-19 vaccination. Psoriatic patients may require regular follow-up before and after COVID-19 vaccination. Trial Registration Review registration number PROSPERO database: CRD42022304157. Supplementary Information The online version contains supplementary material available at 10.1007/s40257-022-00721-z.