TGF-ß signalling defect is linked to low CD39 expression on regulatory T cells and methotrexate resistance in rheumatoid arthritis.

Rheumatoid arthritis (RA) is an autoimmune arthropathy characterized by chronic articular inflammation. Methotrexate (MTX) remains the first-line therapy for RA and its anti-inflammatory effect is associated with the maintenance of high levels of extracellular adenosine (ADO). Nonetheless, up to 40% of RA patients are resistant to MTX treatment and this is linked to a reduction of CD39 expression, an ectoenzyme involved in the generation of extracellular ADO by ATP metabolism, on circulating regulatory T cells (Tregs). However, the mechanism mediating the reduction of CD39 expression on Tregs is unknown. Here we demonstrated that the impairment in TGF-ß signalling lead to the reduction of CD39 expression on Tregs that accounts for MTX resistance. TGF-ß increases CD39 expression on Tregs via the activation of TGFBRII/TGFBRI, SMAD2 and the transcription factor CREB, which is activated in a p38-dependent manner and induces CD39 expression by promoting ENTPD1 gene transcription. Importantly, unresponsive patients to MTX (UR-MTX) show reduced expression of TGFBR2 and CREB1 and decreased levels of p-SMAD2 and p-CREB in Tregs compared to MTX-responsive patients (R-MTX). Furthermore, RA patients carrying at least one mutant allele for rs1431131 (AT or AA) of the TGFBR2 gene are significantly (p = 0.0006) associated with UR-MTX. Therefore, we have uncovered a molecular mechanism for the reduced CD39 expression on Tregs, and revealed potential targets for therapeutic intervention for MTX resistance.

Bone marrow mesenchymal stromal cells isolated from multiple sclerosis patients have distinct gene expression profile and decreased suppressive function compared with healthy counterparts.

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system, due to an immune reaction against myelin proteins. Multipotent mesenchymal stromal cells (MSCs) present immunosuppressive effects and have been used for the treatment of autoimmune diseases. In our study, gene expression profile and in vitro immunomodulatory function tests were used to compare bone marrow-derived MSCs obtained from MS patients, at pre- and postautologous hematopoietic stem cell transplantation (AHSCT) with those from healthy donors. Patient MSCs comparatively exhibited i) senescence in culture; ii) similar osteogenic and adipogenic differentiation potential; iii) decreased expression of CD105, CD73, CD44, and HLA-A/B/C molecules; iv) distinct transcription at pre-AHSCT compared with control MSCs, yielding 618 differentially expressed genes, including the downregulation of TGFB1 and HGF genes and modulation of the FGF and HGF signaling pathways; v) reduced antiproliferative effects when pre-AHSCT MSCs were cocultured with allogeneic T-lymphocytes; vi) decreased secretion of IL-10 and TGF-ß in supernatants of both cocultures (pre- and post-AHSCT MSCs); and vii) similar percentages of regulatory cells recovered after MSC cocultures. The transcriptional profile of patient MSCs isolated 6 months posttransplantation was closer to pre-AHSCT samples than from healthy MSCs. Considering that patient MSCs exhibited phenotypic changes, distinct transcriptional profile and functional defects implicated in MSC immunomodulatory and immunosuppressive activity, we suggest that further MS clinical studies should be conducted using allogeneic bone marrow MSCs derived from healthy donors. We also demonstrated that treatment of MS patients with AHSCT does not reverse the transcriptional and functional alterations observed in patient MSCs.