JAK2 and dermatitis: Baricitinib is an oral reversible and selective Janus kinase (JAK) 1/JAK2 inhibitor that inhibits pro-inflammatory factors such as thymus interstitium lymphoblastopoietin (42), IL-4, IL-5, IL-13, IL-22 and IL-31 in the pathogenesis of AD (43) (44) (45).Compared with placebo, use of Baricitinib at a 4 mg equivalent dose resulted in clinically significant and statistically significant improvements in disease range and clinical markers of skin inflammation at 16 weeks.