Background Adult onset Still's disease (AOSD) is an inflammatory disorder of unknown etiology, which is accompanied by increased levels of serum pro-inflammatory cytokine. Mesenchymal stem cells (MSCs) have immunomodulatory capacities and might be a promising therapeutic option in the treatment of refractory autoimmune diseases. Both cell-to-cell contact and the release of soluble factors mediate immune modulatory functions of MSCs.
Objectives We aimed to determine if MSCs could modulate serum cytokine level in patients with active untreated AOSD, either through paracrine secretion or via direct contacts with the MSCs.
Methods Human peripheral blood mononuclear cells (hPBMCs) from 6 patients with active AOSD were co-cultured for 72 hours with human MSCs (hMSCs at a ratio of 10 to 1). We compared the cytokine levels before and after direct or indirect (transwell cultures) exposition to activated mononuclear cells (LPS, 10ng/ml) or T cell-inducing conditions (anti-CD3 [5 μg/ml], anti-CD28 [5 μg/ml], recombinant human IL-2 [5 ng/ml]). Cytokine levels were detected by multiplex cytokine detection kit by flow cytometry, or ELISA with culture supernatant. In vitro platform for studying the effects of MSCs on individual cytokines, the Wilcoxon signed-rank test was employed for comparison of serum cytokine levels.
Results Treatment of mononuclear cells with hMSCs resulted in significant reduction of mean TNF-α level (mean 463.4 pg/ml vs 137.8 pg/ml, p<0.05) and IL-1 β (mean 1887.1 pg/ml vs 1127.9 pg/ml, p<0.05). When the hMSCs were present during the T-cell differentiation, there was a significant decrease in the mean secreted TNF-α (mean 10953.5 pg/ml vs 454.9 pg/ml, p<0.05), IFN-γ (mean 14301.0 pg/ml vs 5090.4 pg/ml, p<0.05) and sIL-2 receptor (mean 3550.8 pg/ml vs 2506.4 pg/ml, p<0.05). On the contrary, level of TGF-β was significantly increased (mean 4088.8 pg/ml vs 5104.8 pg/ml, p<0.05). But, there was a significant increase in the amount of IL-6 (mean 2215.5 pg/ml vs 25130.6 pg/ml, p<0.05) and IL-17 α (mean 1357.0 pg/ml vs 2453.6 pg/ml, p<0.05). Two chamber experiments also showed similar pattern of cytokine modulation.
Conclusions This preliminary experiment demonstrated that MSCs can modulate cyokine profiles of AOSD mononuclear cells by decreasing pro-inflammatory cytokines, and increasing anti-inflammatory cytokine such as TGF-β. However, up-regulation of IL-6 and IL-17 might be a hurdle to overvome in the clinical application of MSCs in AOSD patients.
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Disclosure of Interest None declared