系统性红斑狼疮患者外周血B细胞脂筏表达变化及地塞米松对其的影响

Expression of lipid raft in peripheral B cell from SLE patients and effect of dexamethasone on its expression

目的探讨系统性红斑狼疮(SLE)患者外周血B淋巴细胞脂筏表达及糖皮质激素对其的影响。方法用霍乱毒素B亚单位(CTB)对B细胞脂筏染色,采用流式细胞仪检测SLE患者(SLE组)及健康对照者(健康对照组)外周血B细胞亚型(CD5)及脂筏的表达。分离B细胞,地塞米松(DEX)干预培养活动期SLE患者B细胞1h,流式细胞仪及共聚焦显微镜检测B细胞脂筏及其调控蛋白F-actin。同时记录受试患者的临床资料。结果 SLE组外周血B细胞脂筏表达较健康对照组明显增高,活动期SLE组高于缓解期SLE组(P均<0.01)。与健康对照组对比,CD5^+B细胞比例未见异常,但SLE组CD5^+B细胞脂筏表达增多。活动期SLE患者脂筏呈荧光强度增加及异常聚集,F-actin表达下调。同时,B细胞脂筏表达率与狼疮活动积分(SLEDAI)呈正相关。地塞米松干预后,B细胞脂筏表达率及荧光强度均明显下降(P均<0.05),伴随着F-actin表达的增加。结论脂筏异常表达和分布可能对B细胞过度活化具有重要作用,糖皮质激素对活动期SLE B细胞脂筏的表达存在一定的下调作用。

Objective To determine the expression of lipid rafts （LRs） of the peripheral B lymphocytes in patients with SLE, and investigate the effect of dexamethasone on LRs expression. Methods Peripheral blood mononuclear cells （PBMCs） were obtained from 22 active and 11 inactive SLE patients, and 11 female healthy volunteers. B lymphocytes were isolated by positive selection from PBMCs. Membrane staining for LRs was achieved with FITC - conjugated cholera toxin B （CTB）. CD5＋ B cells was evaluated by flow cytometry. The level and distribution of LRs were studied by flow cytometry and confocal microscopy. In an in vitro examination, the effect of dexamethasone （DEX） on LRs in B lym- phocytes from SLE was analyzed. Analysis of enumeration data was performed using ANOVA or paired - samples T test. Correlation was examined by Pearson correlation test. Results The number of CTB - binding lipid rafts in B cell from SLE patients was significantly higher than that in B cell from healthy controls （P 〈0. 01 ）. Although there was no signifi- cant difference in expression of CD5 in B cells between SLE patients and healthy controls, a higher percentage of B cell and increased expression of LRs in CD5＋ B cell were observed in SLE patients. Confocal microscopy revealed that the MFI of LRs in B cell from patients with SLE was increased and the MFI of F - actin was reduced. The LRs was found to be irregularly distributed and had more clusters. The number of CTB - binding LRs in B cell from SLE patients was significantly correlated with the SLEDAI score （R = 0. 435, P = 0. 008）. Furthermore, in vitro results showed that DEX treatment reduced the expression of LRs in B cell from SLE patients. Conclusion Aberrant expression and distribution of lipid raft may play an important role in activation of B lymphocytes in SLE, and modulation of LRs may play a role in the treatment of SLE.