sHLA-G调控MSCs治疗SLE的疗效及其机制研究

Recently, some studies have shown that soluble human histocompatibility leukocyte antigen-G (soluble HLA-G), which is remarkable lower in the serum of systemic lupus erythematosus (SLE) patients compared with that in healthy controls, exhibits strong immunosuppressive properties and is able to induce the differentiation of T regulatory cells (Treg). Other studies have found that mesenchymal stem cells (MSCs) secret sHLA-G. sHLA-G is proved to be involved in MSCs-mediated immunoreguratory, although the mechanisms have remained obscure. From 2007, allogeneic MSCs transplantation has been used in the treatment in refractory and severe SLE patients in our centre. We have found that serum levels of sHLA-G increase significantly after transplantation in some tested patients, which is positively correlated to the improvement of SLEDAI scores and serological parameters. Meanwhile, we also have discovered that the numbers of Treg increase significantly in those patients after transplantation. No one knows if there are some exact links among these phenomena. We hypothesize that sHLA-G secreted by the infused MSCs regulates T cell differentiation and increases numbers, even immunosuppressive function of Treg, which utmately improves disease activity by treating ongoing autoimmunity and maintaining immune homeostasis. Therefore, the aim of this study is to test the hypothesis. Furthermore, we aim to elucidate the mechanism of MSCs transplantation in SLE treatment and provide theoretical basis for the broader application of MSCs transplantation in the treatment of lupus.

近年来国内外的研究表明可溶性主要组织相容性人类白细胞抗原G（soluble HLA-G, sHLA-G）是一个较强的免疫抑制分子，它可抑制T细胞的增殖，诱导T细胞凋亡并促进T细胞分化为调节性T细胞（Treg）。系统性红斑狼疮（SLE）患者的血清sHLA-G水平明显低于正常人。最近研究发现间充质干细胞（MSCs）可分泌sHLA-G。我们使用MSCs移植SLE患者，发现移植后患者血清内sHLA-G水平明显升高，并与移植疗效呈正相关，且MSCs移植后Treg数目亦明显增多，但其中的关联及机制不清楚。本研究将探讨sHLA-G分子、MSCs、Treg细胞三者的关系，进一步阐明sHLA-G在MSCs调节免疫功能中的作用机制，为临床进行MSCs移植治疗SLE提供有力的理论依据。

近年来国内外的研究表明可溶性主要组织相容性人类白细胞抗原G（soluble HLA-G, sHLA-G）是一个较强的免疫抑制分子，它可抑制T细胞的增殖，诱导T细胞凋亡并促进T细胞分化为调节性T细胞（Treg）。最近研究发现间充质干细胞（MSCs）可分泌sHLA-G。我们使用MSCs移植SLE患者，发现移植后患者血清内sHLA-G水平明显升高，并与移植疗效呈正相关，且MSCs移植后Treg数目亦明显增多，但其中的关联及机制不清楚。本研究为此探讨了sHLA-G分子、MSCs、Treg细胞三者的关系。我们留取了80例狼疮患者和31例正常对照的血清，ELISA法的结果发现SLE患者的血清sHLA-G水平明显高于正常人(21.76ng/mL ± 1.206 VS 16.84ng/mL ± 1.656)，而SLE患者骨髓MSCs分泌的sHLA-G也明显升高。我们留取了14例狼疮患者和23例正常对照的外周血，流式细胞仪检测。我们的结果显示，狼疮患者外周血T细胞和B细胞ILT2的表达较正常对照组降低。我们选取难治性SLE患者，经静脉输入脐带来源的MSCs（2×106/kg），收集2ml外周静脉血，以ELISA法测定血清sHLA-G水平。我们发现，移植24小时后、移植后一月血清sHLA-G水平显著升高。将狼疮患者的外周血单核细胞与脐带来源的MSC以10:1共培养，发现共培养组sHLA-G水平明显升高。且Treg细胞数显著升高，而加入sHLA-G的抗体后，Treg细胞的比例下调。将1×106 个P3代BM-MSCs尾静脉注射小鼠，我们发现：(1)、BM-MSCs移植治疗后11w，治疗组小鼠血清Qa-2浓度(444.72±58.96pg/ml)显著高于未治疗组(311.02±56.35pg/ml)及正常对照组(289.90±101.60pg/ml)，差异有统计学意义；未治疗组小鼠血清Qa-2浓度略高于正常对照组，差异无统计学意义。(2)、未治疗组小鼠血清中抗dsDNA抗体滴度（125.69±28.38 IU/ml）显著高于BM-MSCs移植治疗组（56.93±17.13 IU/ml）；未治疗组小鼠血清ANA滴度（4244.10±54.90U/ml）显著高于BM-MSCs移植治疗组（307.84±52.23U/ml）。