Prurigo is a common, but treatment-resistant,
skin disease characterized by persistent papules/nodules and severe
itching.
Prurigo occurs in association with various underlying diseases, such as diabetes,
chronic renal failure, and internal
malignancies.
Atopic dermatitis is occasionally complicated by
prurigo lesions. However, the pathology of
prurigo is completely undefined. We demonstrate that repeated intradermal administration of Ag to
IgE-transgenic mice causes persistent and pruritic papulonodular skin lesions mimicking
prurigo. Skin lesions were histopathologically characterized by irregular acanthosis and dermal cellular infiltrates comprising eosinophils, mononuclear cells, and basophils, with epidermal nerve fiber sprouting. In vivo depletion of basophils alleviated skin reactions, indicating that the
inflammation is basophil dependent. Unexpectedly, STAT6 signaling was unnecessary for skin lesion development if
IgE was present. Moreover, the absence of STAT6 signaling exacerbated the
inflammation, apparently as the result of impaired generation of an M2-type anti-inflammatory macrophage response. These results provide novel insights into the pathologic mechanisms underlying
prurigo. Although basophils are indispensable for
prurigo-like
inflammation, Th2 immunity mediated by STAT6 appears to play a protective role, and
therapies targeting Th2-type
cytokines may risk aggravating the
inflammation.