Abstract: 【Abstract】 Objective To investigate the correlation between microRNA-125a（miR-125a） expression and inflammatory cytokine levels in skin lesions of patients with psoriasis vulgaris, and to evaluate the effect of miR-125a on the proliferation of a human immortalized keratinocyte cell line HaCaT. Methods Totally, lesional and adjacent non-lesional skin tissues were collected from 40 patients with psoriasis vulgaris in the Seventh People′s Hospital of Shenyang from 2017 to 2018, and real-time fluorescence-based quantitative reverse transcription PCR was performed to determine the expression of miR-125a in the skin tissues, as well as the mRNA expression of tumor necrosis factor-α （TNF-α）, interleukin-1β （IL-1β）, IL-6, and IL-17 in the lesional skin tissues. HaCaT cells were divided into 4 groups to be transfected with a miR-125a overexpression plasmid （miR-125a overexpression group）, an overexpression control plasmid （overexpression control group）, a miR-125a interference plasmid （miR-125a interference group） and an interference control plasmid （interference control group）, respectively. Cell counting kit-8 （CCK8） assay was performed to assess the proliferative ability of HaCaT cells in the groups at 0, 24, 48, 72 hours after transfection, and double-antibody sandwich enzyme-linked immunosorbent assay （ELISA） to detect the levels of TNF-α, IL-1β, IL-6 and IL-17 in the culture supernatant of HaCaT cells. Spearman rank correlation test was used for correlation analysis, and t test for the comparison of means between two groups. Results The relative expression of miR-125a was significantly lower in the lesional skin tissues （expressed as 2-ΔΔCt, 0.389 ± 0.354） than in the non-lesional skin tissues （1.106 ± 0.396, t = 7.717, P < 0.001） in patients with psoriasis vulgaris. The expression of miR-125a was negatively correlated with the mRNA expression of TNF-α, IL-1β and IL-17 in psoriatic lesions （r = -0.447, -0.424, -0.436, all P < 0.01）. Immediately and 24 hours after transfection with the plasmids, there was no significant difference in the cell proliferative ability between the miR-125a overexpression group and overexpression control group （t = 0.282, 1.445, respectively, both P > 0.05）, or between the miR-125a interference group and interference control group （t = 0.120, 1.543, respectively, both P > 0.05）. Forty-eight and 72 hours after the transfection, the cell proliferative ability was significantly lower in the miR-125a overexpression group than in the overexpression control group （t = 3.222, 4.563, respectively, both P < 0.05）, but significantly higher in the miR-125a interference group than in the interference control group （t = 3.036, 3.269, respectively, both P < 0.05）. In addition, the miR-125a overexpression group showed significantly decreased levels of TNF-α and IL-1β compared with the overexpression control group （t = 4.318, 3.813, respectively, both P < 0.05）. Conclusions MiR-125a is lowly expressed in skin lesions of patients with psoriasis vulgaris. MiR-125a can inhibit the proliferation of keratinocytes, and may play a protective role in the occurrence and development of psoriasis.

Key words: Psoriasis, MicroRNAs, Keratinocytes, Cell proliferation, Tumor necrosis factor-alpha, Interleukin-1beta, Interleukin-6, Interleukin-17