title: [Mechanism of umbilical cord mesenchymal stem cells in the up-regulation of regulatory T cells by transforming growth factor β1 in systemic lupus erythematosus].
abstract: OBJECTIVE
  To explore the mechanism of umbilical cord mesenchymal stem cells (UC-MSC) in the up-regulation of peripheral regulatory T cells in patients with systemic lupus erythematosus (SLE).
  
  
  METHODS
  Peripheral blood mononuclear cells (PBMC) from 20 SLE patients and normal controls were co-cultured with UC-MSC at different ratios respectively for 72 hours. And the proportions of CD4+CD25+Foxp3+regulatory T cells were analyzed by flow cytometry. PBMC and sera from active SLE patients and normal controls were used to stimulate UC-MSC. The expressions of transforming growth factor β1 (TGF-β1) on UC-MSC were detected by real-time fluorescence quantitative polymerase chain reaction (real-time PCR). The supernatant level of TGF-β1 was determined by enzyme-linked immunosorbent assay (ELISA). And the TGF-β1 small interfering RNA (siRNA) was used to interfere with the TGF-β1 expression on UC-MSC and determine its effect on the regulation of SLE Treg cells. TGF-β1 inhibitor was added into the culture system of UC-MSC and PBMC from active SLE patients to observe its role on the up-regulation of Treg cells by UC-MSC.
  
  
  RESULTS
  UC-MSC could dose-dependently up-regulate the peripheral CD4+CD25+Foxp3+Treg proportion in SLE patients. And such an effect was not dependent on cell-cell contact. UC-MSC had no regulatory effect on Treg cells in normal controls. Compared with the non-stimulated and normal PBMC stimulated groups, PBMC from SLE patients significantly promoted TGF-β1 mRNA expression on UC-MSC (relative gene expression was 1.00 ± 0.09, 1.95 ± 0.62, 4.20 ± 2.34 respectively, both P < 0.05). The supernatant level of TGF-β1 was significantly elevated in the presence of SLE PBMC. Sera of SLE patients (5%) enhanced TGF-β1 mRNA expression on UC-MSC and it was significantly higher than fetal bovine serum cultured group (12.19 ± 4.49 vs 1.33 ± 0.06, P < 0.01) and normal individual sera cultured group (2.53 ± 0.72, P < 0.01). Additionally, TGF-β1 siRNA interfered UC-MSC failed to up-regulate Treg cells in SLE patients . Furthermore, TGF-β1 specific inhibitor SB431542 significantly inhibited the regulatory role of UC-MSC on Treg cells in SLE patients.
  
  
  CONCLUSIONS
  Immune microenvironment in SLE patients can significantly stimulate the TGF-β1 expression on UC-MSC and plays an important role in the up-regulation of Treg cells in patients.
authors.affiliation: Department of Rheumatology & Immunology, Drum Tower Clinical Medical School of Nanjing Medical University, Nanjing 210008, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Lu
authors.forename: Dan-dan
authors.initials: DD
authors.lastname: Wang
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.forename: Xiao-feng
authors.initials: XF
authors.lastname: Zeng
authors.forename: Ling-yun
authors.initials: LY
authors.lastname: Sun
mesh_terms: D016022:Case-Control Studies; D002478:Cells, Cultured; D018920:Coculture Techniques; D005434:Flow Cytometry; D006801:Humans; D007963:Leukocytes, Mononuclear; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D014470:Umbilical Cord / Q000166:cytology*; D015854:Up-Regulation
chemical_list: D053773:Transforming Growth Factor beta1