Potential role of MRN-100, an iron-based compound, in upregulating production of cytokine IL-10 in human dendritic cells to promote an anti-inflammatory response in vitro

Abstract

The hydroferrate fluid MRN-100, an iron-based compound with potent antioxidant characteristics, was examined to identify its possible anti-inflammatory effects on human dendritic cells (DCs) in vitro. Human monocyte-derived DCs were treated with MRN-100 at two concentrations (50 and 100 μL/mL) for 24 h and then stimulated with or without lipopolysaccharides (LPS). The expression of DC maturation markers was assessed by flow cytometry and the production of cytokines was determined by enzyme-linked immunosorbent assay (ELISA). Functional assay was performed by co-culturing MRN-100-treated and untreated DCs with allogeneic naïve CD4+ T cells and assaying the T cells' cytokine production. Results show that treatment with MRN-100 significantly upregulated the co-stimulatory molecules CD80 and CD86 and increased human leukocyte antigen-DR (HLA-DR) though not significantly. MRN-100 treatment also significantly increased the production of the anti-inflammatory cytokine interleukin (IL)-10. On the other hand, MRN-100 significantly induced the secretion of pro-inflammatory cytokines such as IL-6 only at high concentrations. Furthermore, DCs pretreated with MRN-100 and either stimulated or not with LPS were able to prime CD4+ T cells to secrete significant amounts of IL-10 while inhibiting the secretion of pro-inflammatory cytokine tumor necrosis factor (TNF)-α. These results indicate that MRN-100 is a powerful anti-inflammatory agent that promotes the generation of an anti-inflammatory immune response in vitro. MRN-100 could be beneficial for treating patients with inflammatory diseases, including arthritis and type 1 diabetes, and its potential benefits should be examined in clinical trials.

Keywords: CD4+ T cells; MRN-100; anti-inflammatory; dendritic cells; hydroferrate fluid.

Figure 1.

Upregulation of co-stimulatory and maturation molecules CD80, CD86, and HLA-DR on MRN-100-treated DCs: (a) a representative cytofluorograph from one experiment; (b) the density of mean florescent intensity (MFI) of CD80, CD86, and HLA-DR in DCs post treatment with MRN-100. Data represent the mean ± SE of four experiments. Values are considered significant for P < 0.05 as compared to DCs alone.

Figure 2.

MRN-100 induces cytokine production by DCs. Results are expressed as mean ± SE from seven individual experiments; values are considered significant for P < 0.05 as compared to DCs alone.

Figure 3.

MRN-100 enhances cytokine secretion on LPS stimulation. Data represent the mean ± SE of 10 experiments; values are considered significant for P < 0.05 as compared to DCs alone.

Figure 4.

MRN-100-stimulated DCs activate CD4+ T cells to secrete a higher amount of IL-10. Results are expressed as mean ± SE from seven individual experiments; values are considered significant for P < 0.05 as compared to DC-CD4+ T cells alone.

Figure 5.

MRN-100-stimulated DCs prime CD4+ T cells to secrete IL-10 but not IFN-γ or TNF-α. Data represent the mean ± SE from five individual experiments; values are considered significant for P < 0.05.