Corneodesmosin expression in psoriasis vulgaris differs from normal skin and other inflammatory skin disorders

Corneodesmosin (Cdsn) is a late differentiation epidermal glycoprotein puta tively involved in keratinocyte adhesion. The Cdsn gene lies within the sus ceptibility region on chromosome 6p21.3 (PSORS1) for psoriasis, a common ch ronic disfiguring skin disease. A particular allelic variant of Cdsn has a strong association with psoriasis. Therefore, genetically and biologically, Cdsn is a possible candidate gene for psoriasis susceptibility. To investi gate a potential role for Cdsn in psoriasis pathogenesis, protein expressio n studies were performed by quantitative immunohistochemistry on normal ski n, psoriatic skin (lesional and nonlesional), and other skin disorders usin g monoclonal antibodies (G36-19 and F28-27). In normal and nonlesional skin , Cdsn was expressed in stratum corneum and one or two layers of superficia l stratum granulosum. In lesional psoriasis, there was a significant increa se in Cdsn expression. which was observed in multiple layers of stratum spi nosum and in stratum corneum. The expression pattern varied from granular, cytoplasmic immunoreactivity to cell surface labeling with weakly immunorea ctive cytoplasm. In chronic atopic dermatitis, lichen planus, mycosis fungo ides, and pityriasis rubra pilaris, Cdsn immunoreactivity was confined to s tratum corneum and upper stratum granulosum with no stratum spinosum immuno reactivity. Immunoelectron microscopy of normal and lesional psoriatic skin demonstrated Cdsn release concomitant with involucrin incorporation into c ell envelopes and completed before mature envelope formation. Extracellular release of Cdsn occurred at a lower level of the epidermis in psoriasis th an normal skin. These protein expression studies provide evidence of altere d Cdsn expression in psoriasis consistent with a role of Cdsn in disease pa thogenesis. Further functional and genetic studies of Cdsn are justified to determine its role as a potential psoriasis-susceptibility factor.