布鲁氏菌感染患者血清sPD-L2水平与Th亚群的相关性

Correlation between serum sPD-L2 levels and Th subpopulations in Brucella infection

目的研究布鲁氏菌感染患者外周血可溶性程序性死亡蛋白1配体2(soluble Programmed cell death ligand2,sPD-L2)的水平及与辅助性T细胞(Helper T cell,Th)亚群的相关性。方法收集2019—2021年新疆维吾尔自治区人民医院83例布鲁氏菌病患者资料,其中急性期37例、慢性期46例;健康对照(Healthy Control,HC)组为50例同期健康体检者。采用流式细胞术和实时荧光定量PCR(qRT-PCR)检测三组外周血Th1、Th2细胞占CD4+T细胞百分比和相关转录因子T-bet、GATA-3的mRNA水平。流式液相多重蛋白定量(CBA)技术检测三组样本血清中细胞因子sPDL2、IFN-γ、IL-4的表达含量。结果急性期布鲁氏菌病组Th1细胞百分比、T-bet mRNA和IFN-γ水平分别为(45.33±4.96)%、(1.91±0.41)pg/mL和(74.42±13.95)pg/mL,高于慢性期布鲁氏菌病组的(21.78±4.42)%、(0.65±0.24)pg/mL和(10.64±3.04)pg/mL及HC组的(28.87±6.67)%、(1.12±0.25)pg/mL和(7.48±2.92)pg/mL,差异有统计学意义(F=193.417,181.583,950.410,P<0.05);急性期布鲁氏菌病组Th2细胞百分比、GATA-3 mRNA和IL-4水平分别为(40.61±9.32)%、(1.02±0.23)pg/mL和(2.08±0.50)pg/mL,低于慢性期布鲁氏菌病组的(59.80±10.09)%、(1.50±0.44)pg/mL和(8.76±2.06)pg/mL及HC组的(46.06±8.84)%、(1.18±0.28)pg/mL和(2.70±0.75)pg/mL,差异有统计学意义(F=47.282,22.771,344.938,P<0.05);急性期、慢性期布鲁氏菌病组和HC组sPD-L2分别为(156.77±24.69)pg/mL、(110.99±29.44)pg/mL和(91.61±11.44)pg/mL,急性期布鲁氏菌病组明显升高,差异有统计学意义(P<0.05)。经相关性分析显示sPD-L2水平与Th1细胞百分比和IFN-γ水平呈正相关(r=0.540,0.692,P<0.01)、与Th2细胞百分比和IL-4水平呈负相关(r=-0.565,-0.528,P<0.01)。结论布鲁氏菌病急性期sPD-L2水平显著增高,慢性布鲁氏菌病患者中免疫应答由Th1向Th2倾斜可能为sPD-L2表达下降,降低Th2的抑制作用,导致布鲁氏菌无法完全清除从而发生免疫逃逸;布鲁氏菌可能通过sPD-L2影响Th1向Th2转化而发挥负性调控作用,导致机体不易清除布鲁氏菌从而进入慢性期。

Objective To investigate the expression level of soluble Programmed cell death ligand2(sPD-L2)in the peripheral blood of patients with Brucella infection and their correlation with helper T cells(Th)subsets.Methods Data from eighty-three patients with confirmed Brucella infection,including 37 patients with acute phase Brucella infection and 46 patients with chronic phase Brucella infection,collected from the People's Hospital of Xinjiang Uygur Autonomous Region between January 2019 and December 2021,were analyzed.Fifty healthy individuals undergoing regular medical check-ups during the same period were included as the Healthy Control(HC)group.Flow cytometry was used to detect the percentage of Th1 and Th2 cells as CD4+T cells in the peripheral blood of the three groups of samples.Quantitative real-time fluorescence PCR(qRT-PCR)was performed to measure the mRNA expression levels of Th1 and Th2 cell-associated transcription factors T-bet and GATA-3 in the peripheral blood of the three samples.The expression levels of cytokines sPD-L2,IFN-γ,and IL-4 in the serum of the three groups of samples were measured by the cytometric bead array(CBA)technique.Results Th1 cells in the acute phase brucellosis infection group(45.33±4.96)%,mRNA expression levels of T-bet(1.91±0.41),and IFN-γexpression levels(74.42±13.95)pg/mL were significantly higher in the acute phase Brucella disease group compared to the chronic phase group(21.78±4.42)%,(0.65±0.24),and(10.64±3.04)pg/mL,as well as the HC group(28.87±6.67)%,(1.12±0.25),and(7.48±2.92)pg/mL,respectively(P<0.05).Th2 cells(59.80±10.09)%,GATA-3 mRNA expression level(1.50±0.44),and IL-4 level(8.76±2.06)pg/mL were significantly higher in the chronic phase brucellosis infection group compared to the acute phase brucellosis patient group(40.61±9.32)%,(1.02±0.23),and(2.08±0.50)pg/mL,as well as the HC group(46.06±8.84)%,(1.18±0.28),and(2.70±0.75)pg/mL,respectively(P<0.05).Compared to the HC group(91.61±11.44)pg/mL,the sPDL2 levels were significantly higher in the acute phase brucellosis patient group(156.77±24.69)pg/mL and slightly higher in the chronic phase brucellosis patient group(110.99±29.44)pg/mL,with a statistically significant difference between the acute and chronic phase brucellosis patient groups(P<0.05).Correlation analysis of the brucellosis patient group showed that sPD-L2 levels were positively correlated with the percentage of Th1 cells(r=0.540,P<0.01)and the levels of IFN-γ(r=0.692,P<0.01),and negatively correlated with the percentage of Th2 cells(r=-0.565,P<0.01)and the levels of IL-4(r=-0.528,P<0.01).Conclusions In patients with acute brucellosis,sPD-L2 levels are significantly increased,which may resist brucellosis by promoting Th1 cells to secrete more pro-inflammatory factors to defend against Brucella infection.In chronic Brucella disease patients,the tilting of immune response types from Th1 to Th2 may be due to a decrease in sPD-L2 expression,which reduces the inhibitory effect of Th2,leading to incomplete clearance of Brucella and thus immune escape.Brucella may affect the conversion of Th1 to Th2 through the sPD-L2 pathway,exerting negative regulatory effects and resulting in difficulty in complete Brucella clearance,thus turning into a chronic phase.