IntroductionThe different distribution of T cells among activation/differentiation stages in immune disorders may condition the outcome of mesenchymal stromal cell (MSC)-based therapies. Indeed, the effect of MSCs in the different functional compartments of T cells is not completely elucidated.MethodsWe investigated the effect of human bone marrow MSCs on naturally occurring peripheral blood functional compartments of CD4+ and CD8+ T cells: naive, central memory, effector memory, and effector compartments. For that, mononuclear cells (MNCs) stimulated with phorbol myristate acetate (PMA) plus ionomycin were cultured in the absence/presence of MSCs. The percentage of cells expressing tumor necrosis factor-alpha (TNF-α), interferon gamma (IFNγ), and interleukin-2 (IL-2), IL-17, IL-9, and IL-6 and the amount of cytokine produced were assessed by flow cytometry. mRNA levels of IL-4, IL-10, transforming growth factor-beta (TGF-β), and cytotoxic T-lymphocyte-associated protein 4 (CTLA4) in purified CD4+ and CD8+ T cells, and phenotypic and mRNA expression changes induced by PMA + ionomycin stimulation in MSCs, were also evaluated.ResultsMSCs induced the reduction of the percentage of CD4+ and CD8+ T cells producing TNF-α, IFNγ, and IL-2 in all functional compartments, except for naive IFNγ+CD4+ T cells. This inhibitory effect differentially affected CD4+ and CD8+ T cells as well as the T-cell functional compartments; remarkably, different cytokines showed distinct patterns of inhibition regarding both the percentage of producing cells and the amount of cytokine produced. Likewise, the percentages of IL-17+, IL-17+TNF-α+, and IL-9+ within CD4+ and CD8+ T cells and of IL-6+CD4+ T cells were decreased in MNC-MSC co-cultures. MSCs decreased IL-10 and increased IL-4 mRNA expression in stimulated CD4+ and CD8+ T cells, whereas TGF-β was reduced in CD8+ and augmented in CD4+ T cells, with no changes for CTLA4. Finally, PMA + ionomycin stimulation did not induce significant alterations on MSCs phenotype but did increase indoleamine-2,3-dioxygenase (IDO), inducible costimulatory ligand (ICOSL), IL-1β, IL-8, and TNF-α mRNA expression.ConclusionsOverall, our study showed that MSCs differentially regulate the functional compartments of CD4+ and CD8+ T cells, which may differentially impact their therapeutic effect in immune disorders. Furthermore, the influence of MSCs on IL-9 expression can open new possibilities for MSC-based therapy in allergic diseases.Electronic supplementary materialThe online version of this article (doi:10.1186/scrt537) contains supplementary material, which is available to authorized users.

The immunosuppressive properties of mesenchymal stromal/stem cells (MSC) rendered them an attractive therapeutic approach for immune disorders and an increasing body of evidence demonstrated their clinical value. However, the influence of MSC on the function of specific immune cell populations, namely, monocyte subpopulations, is not well elucidated. Here, we investigated the influence of human bone marrow MSC on the cytokine and chemokine expression by peripheral blood classical, intermediate and nonclassical monocytes, and myeloid dendritic cells (mDC), stimulated with lipopolysaccharide plus interferon (IFN)γ. We found that MSC effectively inhibit tumor necrosis factor- (TNF-) α and macrophage inflammatory protein- (MIP-) 1β protein expression in monocytes and mDC, without suppressing CCR7 and CD83 protein expression. Interestingly, mDC exhibited the highest degree of inhibition, for both TNF-α and MIP-1β, whereas the reduction of TNF-α expression was less marked for nonclassical monocytes. Similarly, MSC decreased mRNA levels of interleukin- (IL-) 1β and IL-6 in classical monocytes, CCL3, CCL5, CXCL9, and CXCL10 in classical and nonclassical monocytes, and IL-1β and CXCL10 in mDC. MSC do not impair the expression of maturation markers in monocytes and mDC under our experimental conditions; nevertheless, they hamper the proinflammatory function of monocytes and mDC, which may impede the development of inflammatory immune responses.

Rheumatoid arthritis (RA) is a Th1/Th17‐mediated autoimmune disease whose current treatment, consisting in the blockage of inflammatory cytokines by disease‐modifying antirheumatic drugs, is not effective for all patients. The therapeutic potential of mesenchymal stromal/stem cells' (MSCs) immunomodulatory properties is being explored in RA. Here, we investigate the effect of human bone marrow (BM)‐MSCs on the expression of cytokines involved in RA physiopathology by the distinct functional compartments of CD4+ and CD8+ T cells from RA patients. Peripheral blood mononuclear cells from healthy individuals (n = 6) and RA patients (n = 12) were stimulated with phorbol myristate acetate plus ionomycin and cultured in the presence/absence of BM‐MSCs. The expression of (interleukin) IL‐2, tumor necrosis factor alpha (TNF‐α), and interferon‐gamma (IFN‐γ) was evaluated in naive, central memory, effector memory, and effector CD4+ and CD8+ T cells, whereas IL‐6, IL‐9, and IL‐17 expression was measured in total CD4+ and CD8+ T cells. mRNA expression of IL‐4, IL‐10, transforming growth factor beta (TGF‐β), cytotoxic T‐lymphocyte‐associated antigen 4, and/or forkhead box P3 was quantified in fluorescence‐activated cell sorting‐purified CD4+ T cells, CD8+ T cells, and CD4+ Treg. BM‐MSCs inhibited the production of TNF‐α, IL‐17, IL‐6, IL‐2, IFN‐γ, and IL‐9 by T cells from RA patients, mainly by reducing the percentage of cells producing cytokines. This inhibitory effect was transversal to all T cell subsets analyzed. At mRNA level, BM‐MSCs increased expression of IL‐10 and TGF‐β by CD4+ and CD8+ T cells. BM‐MSCs displayed a striking inhibitory action over T cells from RA patients, reducing the expression of cytokines involved in RA physiopathology. Remarkably, BM‐MSC‐derived immunomodulation affected either naive, effector, and memory T cells.

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Rheumatoid arthritis (RA) is a disabling autoimmune disease whose treatment is ineffective for one-third of patients. Thus, the immunomodulatory potential of mesenchymal stromal/stem cells (MSCs) makes MSC-based therapy a promising approach to RA. This study aimed to explore the immunomodulatory action of human bone marrow (BM)-MSCs on myeloid dendritic cells (mDCs) and monocytes, especially on cytokines/chemokines involved in RA physiopathology. For that, LPS plus IFNγ-stimulated peripheral blood mononuclear cells from RA patients (n = 12) and healthy individuals (n = 6) were co-cultured with allogeneic BM-MSCs. TNF-α, CD83, CCR7 and MIP-1β protein levels were assessed in mDCs, classical, intermediate, and non-classical monocytes. mRNA expression of other cytokines/chemokines was also evaluated. BM-MSCs effectively reduced TNF-α, CD83, CCR7 and MIP-1β protein levels in mDCs and all monocyte subsets, in RA patients. The inhibition of TNF-α production was mainly achieved by the reduction of the percentage of cellsproducing this cytokine. BM-MSCs exhibited a remarkable suppressive action over antigen-presenting cells from RA patients, potentially affecting their ability to stimulate the immune adaptive response at different levels, by hampering their migration to the lymph node and the production of proinflammatory cytokines and chemokines. Accordingly, MSC-based therapies can be a valuable approach for RA treatment, especially for non-responder patients.

Background and objectives Rheumatoid arthritis (RA) is a chronic inflammatory disease characterised by autoimmune activation leading to local and systemic consequences. Self-reactive T cells play a decisive role in the initiation and maintenance of the disease process. This disease course has been deeply modified by disease-modifying anti-rheumatic drugs that block pro-inflammatory cytokines, but still more than 1/3 of patients do not respond adequately to treatment. To overcome this limitation, mesenchymal stromal cells (MSC) based therapies have been recently explored. MSC are a population of adult non-hematopoietic stem cells with the ability to immunomodulate different cells of the immune system. The aim of this study was to verify the immunomodulatory activity of bone marrow (BM)-derived MSC on peripheral blood helper (Th) and cytotoxic T cells (Tc), distributed among their different functional compartments (naïve, central memory, effector memory and effector) from RA patients and healthy individuals. Materials and methods To this purpose we preformed co-cultures with mononuclear cells and BM-MSC from 12 RA patients and 8 controls during 20 h in a ratio of 2:1 (MNC:BM-MSC). Then, T cells were activated with PMA and ionomycin for 4 h to induce cytokine production by T cells. The frequency of Th and Tc cells producing cytokines (IL-2, IFN-γ, TNF-α, IL-6, IL-17 and IL-9) among the different functional compartments was measured by flow cytometry. Moreover, IL-4, IL-10, TGF-β and CTLA-4 mRNA expression was assessed after cell sorting of CD4+ and CD8+ T cells. Results BM-MSC clearly induced a decrease in the frequency of CD4+ and CD8+ T cells producing pro-inflammatory cytokines (for all the cytokines analysed) in all functional compartments and in both groups under study. However, the intensity of inhibition varied with the cytokine and the T cell functional compartment. Regarding the mRNA expression, in the presence of BM-MSC, we observed an increase of IL-4, IL-10, TGF-β and CTLA-4 in purified CD4+ T cells for both groups, although in a lower extent in RA patients. Likewise, BM-MSC induced an augment of mRNA levels of the abovementioned molecules in CD8+ T cells, although a more pronounced mRNA expression was observed in RA patients, excepting for IL-4, which expression decreased in both groups. Conclusions Our data show that BM-MSC effectively inhibit pro-inflammatory cytokines production by Th and Tc in all functional compartments and increase the mRNA expression of anti-inflammatory molecules in both T cell subpopulations. These results support their potential utility in the treatment of autoimmune diseases.

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