JAK2 and atopic eczema: Compared to conventional methotrexate (MTX), baricitinib can slow the progression of structural damage even in patients with moderate to high disease activity.[6] Recently, inhibition of IL-5 signaling via JAK2 has been reported to be effective in bronchial asthma and atopic dermatitis by suppressing eosinophil differentiation and proliferation.[7,8] Atopic diseases, including asthma and dermatitis, have been reported to be associated with autoimmune diseases such as RA.[9,10]