 Methods: It will be conducted an open, prospective study with ten adult patients with moderate to severe AD on MTX for 24 weeks. Each participant is expected to attend 7 visits during 6 months of follow-up. In clinical healthy and injured skin, two assessments will be performed: 1 mRNA expression of IL-4, IL-10, IL-17A, IL-22, IL-31, oncostatin M receptor OSMR, alpha subunit IL-31 IL-31RA receptor, TNF-α, IFN-γ, TSLP, TARC and MDC by Real Time-PCR at the initial week and week 24; 2 expression of IL-31, IL-31RA, OSMR, TSLP and Ki67 by immunohistochemistry at the initial week and week 24. 