Mesenchymal stem cells promote the sustained expression of CD69 on activated T lymphocytes: roles of canonical and non‐canonical NF‐κB signalling

Felipe Saldanha‐Araujo,Julio C Voltarelli,Rodrigo A Panepucci,Patrícia V Palma,Rodrigo Haddad,Kelen C R Malmegrim De Farias,Amélia G Araujo,Dimas T Covas,Maristela D Orellana,Marco A Zago,Alessandra De Paula Alves Souza

doi:10.1111/j.1582-4934.2011.01391.x

Felipe Saldanha‐Araujo, Julio C Voltarelli + Show 9 more

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https://doi.org/10.1111/j.1582-4934.2011.01391.x

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Abstract

Mesenchymal stem cells (MSCs) are known to induce the conversion of activated T cells into regulatory T cells in vitro. The marker CD69 is a target of canonical nuclear factor kappa-B (NF-κB) signalling and is transiently expressed upon activation; however, stable CD69 expression defines cells with immunoregulatory properties. Given its enormous therapeutic potential, we explored the molecular mechanisms underlying the induction of regulatory cells by MSCs. Peripheral blood CD3+ T cells were activated and cultured in the presence or absence of MSCs. CD4+ cell mRNA expression was then characterized by microarray analysis. The drug BAY11-7082 (BAY) and a siRNA against v-rel reticuloendotheliosis viral oncogene homolog B (RELB) were used to explore the differential roles of canonical and non-canonical NF-κB signalling, respectively. Flow cytometry and real-time PCR were used for analyses. Genes with immunoregulatory functions, CD69 and non-canonical NF-κB subunits (RELB and NFKB2) were all expressed at higher levels in lymphocytes co-cultured with MSCs. The frequency of CD69+ cells among lymphocytes cultured alone progressively decreased after activation. In contrast, the frequency of CD69+ cells increased significantly following activation in lymphocytes co-cultured with MSCs. Inhibition of canonical NF-κB signalling by BAY immediately following activation blocked the induction of CD69; however, inhibition of canonical NF-κB signalling on the third day further induced the expression of CD69. Furthermore, late expression of CD69 was inhibited by RELB siRNA. These results indicate that the canonical NF-κB pathway controls the early expression of CD69 after activation; however, in an immunoregulatory context, late and sustained CD69 expression is promoted by the non-canonical pathway and is inhibited by canonical NF-κB signalling.

Highlights

Bone marrow stromal cells capable of transferring the microenvironment of hemopoietic tissues were first described by Friedenstein et al [1]
We explored the effects of Mesenchymal stem cells (MSCs) on activated T lymphocytes
MSCs were already known for their ability to induce classical CD4ϩCD25hiFOXP3ϩ Tregs [12, 27,28,29,30], this is the first report showing that MSCs promote the expression of CD69 in different T cell populations, including distinct regulatory subsets

Summary

Introduction

Bone marrow stromal cells capable of transferring the microenvironment of hemopoietic tissues were first described by Friedenstein et al [1]. These cells were later renamed MSCs [2] and were broadly defined as spindle-like plastic-adherent cells endowed with the potential to differentiate in vitro toward osteogenic, chondrogenic and adipogenic lineages [3]. We later demonstrated that these expandable spindle-like plastic-adherent cells could be obtained from virtually all adult and foetal human tissues [8]; this finding has been demonstrated in mice [9]. We demonstrated that MSCs were related to diverse known cell types, closely resembling pericytes and hepatic stellate cells and, to a lesser extent, their differentiated ‘more-restricted’ counterparts (smooth muscle cells and stellate myofibroblasts, respectively), as well as fibroblasts [8]

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