肿瘤坏死因子α介导银屑病脂肪酸去饱和酶2低表达

Tumor necrosis factorα-mediated low expression of fatty acid desaturase 2 in psoriasis

目的探讨脂肪酸去饱和酶2(FADS2)在银屑病皮损中的表达变化及其影响因素。方法通过Gene Expression Omnibus(GEO)数据集GDS4602统计分析银屑病患者皮损FADS2的表达变化。取5只咪喹莫特诱导的C57BL/6小鼠银屑病模型背部皮肤,并取收集于上海市皮肤病医院的人正常对照皮肤和银屑病患者英夫利西单抗治疗前及10周后的皮损组织标本各4份以及司库奇尤单抗治疗前及12周后的皮损组织标本各3份,免疫组化染色检测表皮中FADS2的表达。体外培养的人永生化角质形成细胞HaCaT用50 ng/ml肿瘤坏死因子α(TNF-α)刺激0、6、12或24 h,用200 ng/ml白细胞介素17A(IL-17A)刺激0、6、12 h;用TNF-α单独或联合NF-κB通路抑制剂BAY 11-7082(5μmol/L)刺激6 h。处理完成后,实时荧光定量PCR(qPCR)、Western印迹法分别检测FADS2 mRNA和蛋白的相对表达量。采用单因素方差分析法和t检验进行统计分析。结果GDS4602统计结果显示,与人正常皮肤对照组FADS2基因表达水平(2.035±1.226)相比,银屑病皮损(0.656±0.475)及非皮损(1.503±1.062)组织中显著降低,F值分别为55.17、3.07,P值分别<0.001、=0.012,并且皮损处显著低于非皮损处(F=26.27,P<0.001)。Western印迹和免疫组化染色显示,与正常对照组小鼠皮肤FADS2蛋白表达(灰度值比值:1.000;荧光强度:30.720±6.850)相比,咪喹莫特组小鼠皮损表达显著降低(灰度值比值:0.463±0.172,t=7.00,P=0.002;荧光强度:21.840±3.125,t=3.15,P=0.035)。银屑病患者使用英夫利西单抗治疗10周后,皮损中FADS2蛋白表达(43.775±3.342)较未治疗时(27.950±1.218)显著升高(t=-6.95,P=0.006);而使用司库奇尤单抗治疗12周后的银屑病患者皮损处FADS2蛋白表达(28.667±3.402)与治疗前(31.933±2.987)比较没有显著升高(t=2.72,P=0.113)。qPCR显示,与HaCaT细胞TNF-α0 h组相比,TNF-α6 h组、12 h组FADS2 mRNA相对表达量显著降低(P值分别为0.002、0.003);与IL-17A 0 h组相比,IL-17A 6 h组、12 h组相对表达量变化无统计学意义(P值分别为0.849、0.961)。与HaCaT细胞对照组(正常培养基培养,1.000)相比,TNF-α6 h组FADS2 mRNA相对表达量显著降低(0.682±0.132,t=4.82,P=0.017);与TNF-α6 h组相比,TNF-α+BAY 11-70826 h组显著升高(1.541±0.525,t=-3.58,P=0.037)。Western印迹显示,与HaCaT细胞TNF-α0 h组相比,TNF-α 24 h组FADS2蛋白相对表达量降低(F=6.24,P=0.013)。结论FADS2在银屑病皮损中表达下降,其表达下调可能与TNF-α有关。

Objective To investigate the expression of fatty acid desaturase 2(FADS2)in psoriatic skin lesions,as well as its regulatory factors.Methods FADS2 expression in psoriatic skin lesions was analyzed by using the dataset GDS4602 in Gene Expression Omnibus(GEO)database.Skin tissues were obtained from the back of 5 C57BL/6 mouse models of imiquimod-induced psoriasis,normal skin of 4 patients without psoriasis or other immune skin diseases,lesions of 4 patients with psoriasis before and after 10-week treatment with infliximab,as well as lesions of 3 patients with psoriasis before and after 12-week treatment with secukinumab in Shanghai Skin Disease Hospital.FADS2 expression was determined by both immunohistochemical staining and Western blot analysis in the epidermis of mouse skin tissues,and by immunohistochemical staining in that of human skin tissues.In vitro cultured human immortalized keratinocytes(HaCaT)were divided into several groups to be treated with 50 ng/ml tumor necrosis factor-α(TNF-α)alone for 0,6,12 and 24 hours respectively,200 ng/ml interleukin-17A(IL-17A)alone for 0,6 and 12 hours respectively,or treated with 50 ng/ml TNF-α and 5μmol/L BAY 11-7082(a nuclear factor-κB pathway inhibitor)for 6 hours(TNF-α+BAY 11-70826 h group),and the cells receiving normal culture served as the control group.After the above treatment,real-time fluorescence-based quantitative PCR(qPCR)and Western blot analysis were conducted to determine the mRNA and protein expression of FADS2 respectively.Statistical analysis was carried out by using one-way analysis of variance and t test.Results Analysis of the dataset GDS4602 showed that the FADS2 mRNA expression was significantly lower in the lesional and non-lesional skin tissues from the patients with psoriasis(0.656±0.475,1.503±1.062,respectively)than in the normal skin tissues(2.035±1.226;F=55.17,3.07,P<0.001,=0.012,respectively),and was significantly lower in the lesional skin tissues than in the non-lesional skin tissues from the patients with psoriasis(F=26.27,P<0.001).Western blot analysis and immunohistochemical staining both showed significantly decreased FADS2 protein expression in the mouse skin tissues in the imiquimod group(gray-value ratio:0.463±0.172;fluorescence intensity:21.840±3.125)compared with the normal control group(gray-value ratio:1.000,t=7.00,P=0.002;fluorescence intensity:30.720±6.850,t=3.15,P=0.035).Compared with the skin lesions before treatment,the FADS2 protein expression significantly increased in the skin lesions from the patients with psoriasis after 10-week treatment with infliximab(43.775±3.342 vs.27.950±1.218,t=-6.95,P=0.006),but was not significantly changed in the skin lesions from the patients with psoriasis after 12-week treatment with secukinumab(28.667±3.402 vs.31.933±2.987,t=2.72,P=0.113).qPCR revealed that the FADS2 mRNA expression significantly decreased in HaCaT cells in the TNF-α 6 h group and TNF-α 12 h group compared with the TNF-α 0 h group(P=0.002,0.003,respectively),while there was no significant change in the FADS2 mRNA expression in the IL-17A 6 h group and IL-17A 12 h group compared with the IL-17A 0 h group(P=0.849,0.961,respectively).The FADS2 mRNA expression significantly decreased in HaCaT cells in the TNF-α 6 h group(0.682±0.132)compared with the control group(1.000,t=4.82,P=0.017),but significantly increased in the TNF-α+BAY 11-70826 h group(1.541±0.525)compared with the TNF-α 6 h group(t=-3.58,P=0.037).Western blot analysis revealed significantly decreased FADS2 protein expression in HaCaT cells in the TNF-α24 h group compared with the TNF-α 0 h group(F=6.24,P=0.013).Conclusion FADS2 expression was downregulated in psoriatic lesions,which may be related to TNF-α.