IL31 and Alzheimer disease: Consistent with this, we observed that DNCB-induced AD-like lesion mice showed abnormal immune responses of Th1 and Th2, whereas external application of PO extract effectively reversed the significant elevation of serum Ig E, skin His, Il-31 levels and mRNA levels of Il-4, Tslp, Tnf-α and Ifn-γ, thereby alleviating AD-like atopic lesions and pruritus.