Chen Chen, Liang Jun, Yao Genhong, Chen Haifeng, Shi Bingyu, Zhang Zhuoya, Zhao Cheng, Zhang Huayong, Sun Lingyun
Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China.
Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China.
Int Immunopharmacol. 2017 Mar;44:234-241. doi: 10.1016/j.intimp.2017.01.024. Epub 2017 Jan 25.
Soluble human leukocyte antigen-G (sHLA-G) is a non-classical HLA class I molecule, exhibiting strong immunosuppressive properties by inducing the differentiation of T regulatory cells (Treg). Mesenchymal stem cells (MSCs) transplantation alleviates disease progression in systemic lupus erythematosus (SLE) patients. However, the underlying mechanisms are largely unknown.
To explore whether sHLA-G is involved in upregulating effects of MSCs on Treg, which contributes to therapeutic effects of MSCs transplantation in SLE.
The serum sHLA-G levels of SLE patients and healthy controls were detected by ELISA. The percentages of peripheral blood CD4+ILT2+, CD8+ILT2+, CD19+ILT2+ cells and Treg cells were examined by flow cytometry. Ten patients with active SLE, refractory to conventional therapies, were infused with umbilical cord derived MSCs (UC-MSCs) and serum sHLA-G was measured 24h and 1month after infusion. The mice were divided into three groups: C57BL/6 mice, B6.MRL-Fas mice infused with phosphate buffer saline (PBS), and B6.MRL-Fas mice infused with bone marrow MSCs (BM-MSCs). Then, the concentrations of serum Qa-2 were detected. Peripheral blood mononuclear cells (PBMCs) were isolated from SLE patients and co-cultured with UC-MSCs for 3days at different ratios (50:1, 10:1, and 2:1) with or without HLA-G antibody, and the frequencies of CD4+CD25+Foxp3+ T cells were then determined by flow cytometry.
The concentrations of serum sHLA-G were comparable between SLE patients and healthy controls. However, there was a negative correlation between sHLA-G levels and SLE disease activity index (SLEDAI) scores in active SLE patients (SLEDAI>4). We found that serum sHLA-G levels were negatively correlated with blood urea nitrogen, serum creatinine and 24-hour urine protein in SLE patients. The sHLA-G levels were significantly lower in SLE patients with renal involvement than those without renal involvement. The expression of ILT2 on CD4+ T cells from SLE patients decreased significantly compared to that of healthy controls. A positive correlation between the frequencies of Treg and CD4+ILT2+ T cells was found in SLE patients. The levels of sHLA-G increased 24h post UC-MSCs transplantation. The concentrations of Qa-2 in BM-MSCs transplanted mice were significantly higher than those of control group. In vitro studies showed that MSCs increased the frequency of Treg cells in SLE patients in a dose-dependent manner, which was partly abrogated by the anti-HLA-G antibody.
Our results suggested that MSCs may alleviate SLE through upregulating Treg cells, which was partly dependent on sHLA-G.
可溶性人类白细胞抗原-G（sHLA-G）是一种非经典的I类人类白细胞抗原分子，通过诱导调节性T细胞（Treg）分化表现出强大的免疫抑制特性。间充质干细胞（MSCs）移植可缓解系统性红斑狼疮（SLE）患者的疾病进展。然而，其潜在机制 largely unknown。
探讨sHLA-G是否参与MSCs对Treg的上调作用，这有助于MSCs移植治疗SLE的疗效。
采用酶联免疫吸附测定（ELISA）检测SLE患者和健康对照者血清sHLA-G水平。采用流式细胞术检测外周血CD4+ILT2+、CD8+ILT2+、CD19+ILT2+细胞及Treg细胞百分比。对10例常规治疗无效的活动性SLE患者输注脐带间充质干细胞（UC-MSCs），并于输注后24小时和1个月检测血清sHLA-G水平。将小鼠分为三组：C57BL/6小鼠、输注磷酸盐缓冲液（PBS）的B6.MRL-Fas小鼠和输注骨髓间充质干细胞（BM-MSCs）的B6.MRL-Fas小鼠。然后，检测血清Qa-2浓度。从SLE患者中分离外周血单个核细胞（PBMCs），与UC-MSCs以不同比例（50:1、10:Ⅰ和2:1）共培养3天，有或无HLA-G抗体，然后通过流式细胞术测定CD4+CD25+Foxp3+T细胞频率。
SLE患者和健康对照者血清sHLA-G浓度相当。然而，活动性SLE患者（SLEDAI>4）的sHLA-G水平与SLE疾病活动指数（SLEDAI）评分呈负相关。我们发现SLE患者血清sHLA-G水平与血尿素氮、血清肌酐和24小时尿蛋白呈负相关。有肾脏受累的SLE患者的sHLA-G水平显著低于无肾脏受累的患者。与健康对照者相比，SLE患者CD4+T细胞上ILT2的表达显著降低。在SLE患者中发现Treg频率与CD4+ILT2+T细胞之间呈正相关。UC-MSCs移植后24小时sHLA-G水平升高。BM-MSCs移植小鼠的Qa-2浓度显著高于对照组。体外研究表明，MSCs以剂量依赖的方式增加SLE患者Treg细胞频率，抗HLA-G抗体可部分消除这种增加。
我们的结果表明，MSCs可能通过上调Treg细胞来缓解SLE，这部分依赖于sHLA-G。
