Abstract: 【Abstract】 Objective To determine the expression of Sprouty in skin lesions of patients with psoriasis vulgaris, and to investigate its correlation with the severity of psoriasis. Methods From May 2018 to November 2018, 15 lesional skin samples and 10 normal skin samples were collected from patients with psoriasis vulgaris and healthy controls respectively in Dermatology Hospital of Southern Medical University. Immunohistochemical study was performed to determine the distribution of Sprouty1, 2 and 4 proteins in psoriatic lesions and normal skin tissues, Western blot analysis to determine the protein expression of Sprouty1, 2 and 4, reverse transcription （RT）-PCR to measure the mRNA expression of Sprouty1, 2 and 4. Pearson correlation analysis was used to analyze the correlation between Sprouty protein expression and psoriasis area and severity index （PASI） scores. Results Immunohistochemical study showed that Sprouty1, 2 and 4 were all expressed in psoriatic lesions and normal skin tissues. Sprouty1 was strongly expressed in the cell membrane and cytoplasm of granular layer cells in the control group, but slightly expressed in the cell membrane of granular layer cells in the psoriasis group. Sprouty4 was more strongly expressed in the psoriasis group than in the control group, and Sprouty2 was slightly expressed in both the 2 groups. RT-PCR and Western blot analysis showed that Sprouty1 mRNA and protein were both expressed in the psoriasis group and control group, and significantly lower in the psoriasis group （0.844 ± 0.169, 0.148 ± 0.141 respectively） than in the control group （0.972 ± 0.105, 0.413 ± 0.108 respectively, both P < 0.05）; the Sprouty1 protein expression was negatively correlated with the PASI score in the psoriasis group （r = -0.628, P = 0.012）. The psoriasis group showed significantly increased protein and mRNA expression of Sprouty4 （1.306 ± 0.283, 1.727 ± 1.017 respectively） compared with the control group （0.584 ± 0.304, 0.714 ± 0.615, t = 6.063, 2.814, respectively, both P < 0.05）, and the Sprouty4 protein expression was positively correlated with the PASI score in the psoriasis group （r = 0.812, P < 0.001）. The Sprouty2 protein and mRNA were slightly expressed in the 2 groups, and no significant difference was observed between the 2 groups （both P > 0.05）; there was no significant correlation between the Sprouty2 protein expression and PASI score（r = 0.436, P = 0.104）. Conclusion The protein expression of Sprouty1 and 4 in the psoriatic lesions is correlated with the PASI score, suggesting that Sprouty1 and 4 are related to the occurrence of psoriasis.

Key words: Psoriasis, Extracellular signal-regulated MAP kinases, Sprouty, Disease severity