DOWN-REGULATION OF TRANSFORMING-GROWTH-FACTOR-BETA-RECEPTOR-I AND TRANSFORMING-GROWTH-FACTOR-BETA-RECEPTOR-II IS SEEN IN LESIONAL BUT NOT NON-LESIONAL PSORIATIC EPIDERMIS

Transforming growth factor-beta s (TGF-beta s) are a family of growth factors with inhibitory effects on epithelial cell proliferation. Thei r effects are mediated by two interacting receptors, of which type I ( T beta R-I) mediates signal transduction after interaction with type I I (T beta R-II) carrying the TGF-beta ligand, We have studied the expr ession of T beta R-I and T beta R-II in psoriatic and normal human ski n by using polyclonal rabbit antisera and immunohistochemistry. Immuno histochemical analysis revealed an intense immunoreactivity for both r eceptors in the basal and often also suprabasal layer of normal and no n-lesional psoriatic epidermis, In contrast, all psoriatic lesions stu died lacked detectable immunoreactivity of either receptor in the epid ermis. The results suggest that lack of TGF-beta-mediated growth inhib ition by down-regulation of TGF-beta receptor expression may play an i mportant part in the pathogenesis of psoriasis.