Abstract: Objective To investigate the role of phosphorylated extracellular signal-regulated kinase （p-ERK）, mitogen-activated protein kinase （MAPK）/ERK kinase （MEK）, and nuclear factor-κB （NF-κB） in the pathogenesis of psoriasis vulgaris. Methods Immunohistochemistry and Western blot were used to detect the expression of p-MEK, p-ERK and p-NF-κB in tissue samples from 30 patients with psoriasis vulgaris and 15 normal human controls. The average optical density of immunostaining and relative grey scale of immuno-bloting were calculated. Results The average optical density of immunostaining for p-MEK, p-ERK and p-NF-κB was 0.36 ± 0.03, 0.36 ± 0.04 and 0.26 ± 0.04, respectively in lesion samples of psoriasis, significantly higher than that in normal control tissue （0.22 ± 0.02, 0.18 ± 0.03 and 0.16 ± 0.03, all P < 0.01）. A significant increase was also observed in the relative grey scale of p-MEK, p-ERK and p-NF-κB in psoriatic lesions compared with the normal controls （1.41 ± 0.14 vs 0.54 ± 0.10, 2.35 ± 0.34 vs 1.86 ± 0.12, 1.07 ± 0.15 vs 0.87 ± 0.08, all P < 0.01）. Conclusions The expressions of p-MEK, p-ERK and p-NF-κB are enhanced in lesions of psoriasis vulgaris, and the abnormal activation of upstream and downstream molecules in the MAPK signaling pathways might be involved in the pathogenesis of psoriasis.

Key words: psoriasis