Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement
The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.
IL-15 Expressed On RA Synovial Fibroblasts (RASFib) Induces Proliferation of CD4CD25 Regulatory T Cells (Treg) and Augments Their Suppressive Potency
Garcia-Carmona, Y., Benito-Miguel, M., Balsa, Alejandro, de Ayala, C.P., Martin-Mola, E., Miranda-Carus, M. E.
We previously described that fibroblast-like cells from the synovium of Rheumatoid Arthritis patients (RASFib) constitutively express intracellular and surface IL-15, that induces activation of cocultured T cells. The purpose of the present study was to examine the effect of RASFib IL-15 expression on the function of human CD4+CD25+ Treg cells
RASFib were obtained from synovectomy or arthroplasty specimens of RA patients. Total CD4+ T (TCD4T), CD4+CD25+ T reg and CD4+CD25- Teff cells were isolated from the peripheral blood of 30 healthy controls by Ficoll-Hypaque gradient, followed by magnetical sorting. Purity of the T cell populations was 99% by flow cytometry. Cocultures of RASFib and T cells were established in 96-well plates, in the presence or absence of IL-15 neutralizing agents. The function of Treg cells was assessed using two different approaches: A.The regulatory function of natural proportions of Treg cells was inferred by comparing the proliferative and cytokine responses of aCD3 stimulated total CD4+ versus CD25+ depleted CD4+ T cells, and B. The per cell potency of Treg was assessed in cocultures of isolated CD4+CD25+ Treg with CD4+CD25- Tresp, established at different Treg/Tresp ratios. Proliferation was determined by CFSE dilution and cytokine secretion was measured by ELISA of culture supernatants
RASFib, through their constitutive IL-15 expression, were able to induce the proliferation of human Tregs stimulated through their TCR, and at the same time potentiated their suppressive action on the cytokine secretion of CD4+CD25- responder T cells (Tresp). In parallel, constitutive RASFib IL-15 expression mediated an upregulated response of Tresp cells. Subsequently, total CD4+ T cells, containing natural proportions of Treg and Tresp, secreted an increased amount of pathogenic cytokines when cocultured with RASFib despite the presence of proliferating Treg with superior regulatory potency
RASFib IL-15 exerts a dual action on the equilibrium between Treg and Tresp cells, by potentiating the suppressive effect of Treg while augmenting the pro-inflammatory action of Tresp; the result is a shift of the Treg/Tresp balance towards a pro-inflammatory state. This alteration of the Treg/Tresp equilibrium is not observed in the presence of OASFib or dermal fibroblasts, that do not constitutively express surface IL-15
To cite this abstract, please use the following information:
Garcia-Carmona, Y., Benito-Miguel, M., Balsa, Alejandro, de Ayala, C.P., Martin-Mola, E., Miranda-Carus, M. E.; IL-15 Expressed On RA Synovial Fibroblasts (RASFib) Induces Proliferation of CD4CD25 Regulatory T Cells (Treg) and Augments Their Suppressive Potency [abstract]. Arthritis Rheum 2009;60 Suppl 10 :1073