Potential Role of Cytosolic RNA Sensor as an Inhibitor for Keratinocyte Differentiation in the Pathogenesis of Psoriasis.

Background: Psoriasis is a chronic inflammatory skin disease. The etiology of psoriasis is not fully understood, but the genetic background is considered to be the most important factor. To date, many psoriasis-related genes have been discovered, but the role of many important genes has not been well understood.

Objective: The purpose of this study is to uncover possible roles of in psoriasis.

Methods: Expression of MDA5 was investigated using immunohistochemistry. Then, was overexpressed in keratinocytes using a recombinant adenovirus.

Results: As a result of immunohistochemical staining, the expression of was significantly increased in the epidermis of psoriasis compared to normal skin. Similarly, the expression of was increased in imiquimod-induced psoriasiform dermatitis model. In cultured keratinocytes, toll-like receptor 3 agonist poly(I:C) induced expression of at both mRNA and protein levels. When was overexpressed using a recombinant adenovirus, poly(I:C)-induced cytokine expression was significantly increased. Finally, overexpression significantly inhibited calcium-induced differentiation of keratinocytes.

Conclusion: These results suggest that MDA5 increases in psoriasis and negatively regulates keratinocyte differentiation.