title: Mesenchymal stem cells upregulate Treg cells via sHLA-G in SLE patients.
abstract: BACKGROUND
  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.
  
  
  OBJECTIVE
  To explore whether sHLA-G is involved in upregulating effects of MSCs on Treg, which contributes to therapeutic effects of MSCs transplantation in SLE.
  
  
  METHODS
  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-Faslprmice infused with phosphate buffer saline (PBS), and B6.MRL-Faslprmice 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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  Our results suggested that MSCs may alleviate SLE through upregulating Treg cells, which was partly dependent on sHLA-G.
authors.affiliation: Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China.
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.affiliation: Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liang
authors.affiliation: Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China.
authors.forename: Genhong
authors.initials: G
authors.lastname: Yao
authors.affiliation: Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China.
authors.forename: Bingyu
authors.initials: B
authors.lastname: Shi
authors.affiliation: Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China.
authors.forename: Zhuoya
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhao
authors.affiliation: Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China.
authors.forename: Huayong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Rheumatology and Immunology, The Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, PR China. Electronic address: lingyunsun@nju.edu.cn.
authors.forename: Lingyun
authors.initials: L
authors.lastname: Sun
mesh_terms: D000328:Adult; D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D005260:Female; D051858:Forkhead Transcription Factors / Q000378:metabolism; D059951:HLA-G Antigens / Q000378:metabolism*; D006801:Humans; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D008180:Lupus Erythematosus, Systemic / Q000276:immunology* / Q000628:therapy; D008297:Male; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D059951:HLA-G Antigens; D053645:Interleukin-2 Receptor alpha Subunit
keywords: Human leukocyte antigen-G; Mesenchymal stem cells; SLE; Treg