title: Mesenchymal stem cells generate a CD4+CD25+Foxp3+ regulatory T cell population during the differentiation process of Th1 and Th17 cells.
abstract: BACKGROUND
  Mesenchymal stem cells (MSCs) are adult, multipotent, stem cells with immunomodulatory properties. The mechanisms involved in the capacity of MSCs to inhibit the proliferation of proinflammatory T lymphocytes, which appear responsible for causing autoimmune disease, have yet to be fully elucidated. One of the underlying mechanisms studied recently is the ability of MSCs to generate T regulatory (Treg) cells in vitro and in vivo from activated peripheral blood mononuclear cells (PBMC), T-CD4+ and also T-CD8(+) cells. In the present work we investigated the capacity of MSCs to generate Treg cells using T-CD4(+) cells induced to differentiate toward the proinflammatory Th1 and Th17 lineages.
  
  
  METHODS
  MSCs were obtained from mouse bone marrow and characterized according to their surface antigen expression and their multilineage differentiation potential. CD4(+) T cells isolated from mouse spleens were induced to differentiate into Th1 or Th17 cells and co-cultured with MSCs added at day 0, 2 or 4 of the differentiation processes. After six days, CD25, Foxp3, IL-17 and IFN-γ expression was assessed by flow cytometry and helios and neuropilin 1 mRNA levels were assessed by RT-qPCR. For the functional assays, the 'conditioned' subpopulation generated in the presence of MSCs was cultured with concanavalin A-activated CD4(+) T cells labeled with carboxyfluorescein succinimidyl ester. Finally, we used the encephalomyelitis autoimmune diseases (EAE) mouse model, in which mice were injected with MSCs at day 18 and 30 after immunization. At day 50, the mice were euthanized and draining lymph nodes were extracted for Th1, Th17 and Treg detection by flow cytometry.
  
  
  RESULTS
  MSCs were able to suppress the proliferation, activation and differentiation of CD4(+) T cells induced to differentiate into Th1 and Th17 cells. This substantial suppressive effect was associated with an increase of the percentage of functional induced CD4(+)CD25(+)Foxp3(+) regulatory T cells and IL-10 secretion. However, using mature Th1 or Th17 cells our results demonstrated that while MSCs suppress the proliferation and phenotype of mature Th1 and Th17 cells they did not generate Treg cells. Finally, we showed that the beneficial effect observed following MSC injection in an EAE mouse model was associated with the suppression of Th17 cells and an increase in the percentage of CD4(+)CD25(+)Foxp3(+) T lymphocytes when administrated at early stages of the disease.
  
  
  CONCLUSIONS
  This study demonstrated that MSCs contribute to the generation of an immunosuppressive environment via the inhibition of proinflammatory T cells and the induction of T cells with a regulatory phenotype. Together, these results might have important clinical implications for inflammatory and autoimmune diseases.
authors.forename: Patricia
authors.initials: P
authors.lastname: Luz-Crawford
authors.forename: Monica
authors.initials: M
authors.lastname: Kurte
authors.forename: Javiera
authors.initials: J
authors.lastname: Bravo-Alegría
authors.forename: Rafael
authors.initials: R
authors.lastname: Contreras
authors.forename: Estefania
authors.initials: E
authors.lastname: Nova-Lamperti
authors.forename: Gautier
authors.initials: G
authors.lastname: Tejedor
authors.forename: Danièle
authors.initials: D
authors.lastname: Noël
authors.forename: Christian
authors.initials: C
authors.lastname: Jorgensen
authors.forename: Fernando
authors.initials: F
authors.lastname: Figueroa
authors.forename: Farida
authors.initials: F
authors.lastname: Djouad
authors.forename: Flavio
authors.initials: F
authors.lastname: Carrión
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D015704:CD4 Antigens / Q000378:metabolism; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D018920:Coculture Techniques; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000628:therapy; D005260:Female; D051858:Forkhead Transcription Factors / Q000378:metabolism; D016753:Interleukin-10 / Q000378:metabolism; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D008213:Lymphocyte Activation; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D050378:T-Lymphocytes, Regulatory / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D018417:Th1 Cells / Q000166:cytology* / Q000276:immunology; D058504:Th17 Cells / Q000166:cytology* / Q000276:immunology
chemical_list: D015704:CD4 Antigens; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D053645:Interleukin-2 Receptor alpha Subunit; D016753:Interleukin-10