Investigation On Expression Of Smad7, Smurf1 And Smurf2 In Psoriatic Lesions

Background: Psoriasis vulgaris is a common chronic, relapsing, and inflammatory skin disorder basically characterized by hyperproliferation of the keratinocytes and local infiltration of inflammatory cells in histopathology. Different cytokines are involved in the pathophysiological process of psoriasis vulgaris. Not only the participation of cytokines in promoting inflammation and/or stimulating the proliferation of keratinocyte, such as IL-1, IL-6, IL-8, IFN-γand TNF-α, but also the involvement of TGF-βin suppressing immune response and inhibiting the proliferation of keratinocyte has been found in psoriasis vulgaris.In addition to changed serum concentration of TGF-β1 in patients with psoriasis vulgaris and down-regulated TGF-βin psoriatic lesions, decreased expression or loss of TGF-βreceptor I and II in the psoriatic epidermis were also observed, suggesting that a blocked TGF-βsignaling pathway is involved to some extent in pathogenesis of psoriasis. Smad family members are major intracellular mediators and regulators of TGF-βsignaling from its membrane receptors to nucleus. Among Smads, Smad7 is an important inhibitor of TGF-βsignaling. One of the functions of Smad7 is that Smad7 can recruit Smad ubiquitination regulatory factor 1 and 2 (Smurf1 and Smurf2) for degradation of TGF-βreceptor protein. So far, the mechanism for decreased expression or loss of TGF-βreceptors and expression level of Smad7 and Smurfs remains unknown.Objective:To investigate expression and distribution of Smad7, Smurf1 and Smurf2 in psoriatic lesions for an insight into the blockade of TGF-βsignaling pathway in psoriatic lesions.Methods:Expression of Smad7, Smurf1 and Smurf2 mRNA was analyzed in psoriatic lesions and control normal skin using reverse transcript-polymerase chain reaction (RT-PCR) techniques. SP immunohistochemistry was used to detect the distribution and expression of Smad7, Smurf1 and Smurf2 proteins in psoriatic lesions and control normal skin specimens.