IL4 and Alzheimer disease: In AD (eczema), the skin's barrier defect is partly due to cytoskeletal‐junctional alterations: chronic Th2 inflammation (high IL‐4/IL‐13) downregulates key junction proteins (like claudin‐1) and loosens TJs, while repeated scratching triggers Ca++‐dependent actomyosin contraction in epidermal cells.