Abstract: Objective To study the expression of Toll-like receptor 2 (TLR2) and TLR4 in psoriatic lesions and the possible role of these receptors in the pathogenesis of psoriasis.Methods Expression of TLR2 and TLR4 was measured in 16 specimens from lesions of guttate psoriasis,13 from chronic plaque psoriasis and 10 from normal skin.The existence of TLR2 and TLR4 was located by immunochemistry in keratinocytes and vascular endothelial cells of dermis.Results TLR2 was expressed on basal layer and prickle cell layer of epidermis in all 16 specimens of guttate psoriasis and 13 of chronic plaque psoriasis.The weak expression of TLR2 was found only in the basal layer of normal epidermis.TLR4 was strongly expressed on entire epidermis in guttate psoriasis and chronic plaque psoriasis.Dermal vascular endothelial cells also expressed TLR2 and TLR4 in psoriatic lesions rather than normal skin.Conclusions TLR2 and TLR4 are expressed in both acute guttate psoriasis and chronic plaque psoriasis in different pattern.Expression of TLR4 seems stronger in epidermis than TLR2 does while they show the similar expression in dermal vascular endothelial cells.These findings indicate a close relationship between psoriasis and innate immune reaction to infections.TLR2 and TLR4 might play an important role in the formation of psoriasis.

Key words: Psoriasis, TLR2, TLR4