Mechanisms of IL-12 Synthesis by Human Dendritic Cells Treated with the Chemical Sensitizer NiSO4

Universud, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche S 749 and 996, Faculté de Pharmacie, Châtenay-Malabry, France.
The Journal of Immunology (Impact Factor: 4.92). 07/2010; 185(1):89-98. DOI: 10.4049/jimmunol.0901992
Source: PubMed


Allergic contact dermatitis, caused by metallic ions, is a T cell-mediated inflammatory skin disease. IL-12 is a 70-kDa heterodimeric protein composed of IL-12p40 and IL-12p35, playing a major role in the generation of allergen-specific T cell responses. Dendritic cells (DCs) are APCs involved in the induction of primary immune responses, as they possess the ability to stimulate naive T cells. In this study, we address the question whether the sensitizer nickel sulfate (NiSO(4)) itself or in synergy with other signals can induce the secretion of IL-12p70 in human monocyte-derived DCs (Mo-DCs). We found that IL-12p40 was produced by Mo-DC in response to NiSO(4) stimulation. Addition of IFN-gamma concomitantly to NiSO(4) leads to IL-12p70 synthesis. NiSO(4) treatment leads to the activation of MAPK, NF-kappaB pathways, and IFN regulatory factor 1 (IRF-1). We investigated the role of these signaling pathways in IL-12 production using known pharmacological inhibitors of MAPK and NF-kappaB pathways and RNA interference-mediated silencing of IRF-1. Our results showed that p38 MAPK, NF-kappaB, and IRF-1 were involved in IL-12p40 production induced by NiSO(4). Moreover, IRF-1 silencing nearly totally abrogated IL-12p40 and IL-12p70 production provoked by NiSO(4) and IFN-gamma. In response to NiSO(4), we observed that STAT-1 was phosphorylated on both serine and tyrosine residues and participated to NiSO(4)-induced IRF-1 activation. N-acetylcysteine abolished STAT-1 phosphorylation, suggesting that STAT-1 activation may be dependent on NiSO(4)-induced alteration of the redox status of the cell. These results indicate that p38 MAPK, NF-kappaB, and IRF-1 are activated by NiSO(4) in Mo-DC and cooperate for IL-12 production.

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    • "The biological effects of Ni2+ ions have been studied in several distinct cell types such as monocytes [26] [27] [28] [29], dendritic cells [30] [31], endothelial cells [28], [32] and epithelial cells [33] [34]. Although most of these studies demonstrated enhanced secretion of soluble factors or expression of cell adhesion molecules, inhibitory effects have also been demonstrated in different experimental settings [26] [27]. "
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    ABSTRACT: The spontaneous IL-8 secretion observed in OSCC is partially dependent on the disregulated activity of transcription factor NF-κB. Nickel compounds are well established human carcinogens, however, little is known about the influence of nickel on the spontaneous secretion of IL-8 in oral squamous cell carcinoma (OSCC) cells. The aim of the present study was to investigate whether Ni(2+) ions can influence on IL-8 secretion by OSCC. The IL-8 secretion was measured by ELISA. The expression of IL-8 mRNA was examined by real-time PCR. The NF-κB activity was measured by luciferase assay. The phosphorylation status and nuclear localization of NF-κB subunits were examined by Western blotting or Transfactor kit and immunofluorescence staining, respectively. The interaction of NF-κB p50 subunit and Ni(2+) ions was examined by Ni(2+)-column pull down assay. The site-directed mutagenesis was used to generate a series of p50 mutants. Scratch motility assay was used to monitor the cell mobility. Our results demonstrated that, on the contrary to our expectations, Ni(2+) ions inhibited the spontaneous secretion of IL-8. As IL-8 reduction was observed in a transcriptional level, we performed the luciferase assay and the data indicated that Ni(2+) ions reduced the NF-κB activity. Measurement of p50 subunit in the nucleus and the immunofluorescence staining revealed that the inhibitory effect of Ni(2+) ions was attributed to the prevention of p50 subunit accumulation to the nucleus. By Ni(2+)-column pull down assay, Ni(2+) ions were shown to interact directly with His cluster in the N-terminus of p50 subunit. The inhibitory effect of Ni(2+) ions was reverted in the transfectant expressing the His cluster-deleted p50 mutant. Moreover, Ni(2+) ions inhibited the OSCC mobility in a dose dependent fashion. Taken together, inhibition of NF-κB activity by Ni(2+) ion might be a novel therapeutic strategy for the treatment of oral cancer.
    Preview · Article · Jul 2013 · PLoS ONE
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    • "This work was recently extended to other metallic haptens, namely CoCl 2 and K 2 Cr 2 O 7 and the results demonstrated that nickel and CoCl 2 , but not K 2 Cr 2 O 7 , activate the NF-kB transcription factor in DC derived from CD34 + cord blood cells (Antonios et al., 2009). Furthermore, p38 MAPK, NF-kB and IRF-1 were involved in nickel-induced IL-12p40 production in human monocyte-derived DC (Antonios et al., 2010). Taken together, these data indicate that although some sensitisers activate the NF-kB transcription factor and are probably responsible for some phenotypic modifications observed in DC, other sensitisers failed to activate this signalling pathway. "
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