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IL-15 Negatively Regulates Curdlan-Induced IL-23 Production by Human Monocyte-Derived Dendritic Cells and Subsequent Th17 Response

Ahmet Eken, Zehra Okus, Serife Erdem, Zehra Busra Azizoglu, Yesim Haliloglu, Ayten Bicer, Tugba Nur Gur, Ebru Yilmaz, Musa Karakukcu, Hamiyet Donmez Altuntas, Halit Canatan

North Clin Istanb. 2019 Oct 24;6(4):379-387.

PMID: 31909384

Abstract:

Objective:
In this study, we aimed to assess the effects of long- and short-term IL-15 cytokine exposure of human monocyte-derived curdlan-matured dendritic cells (DCs) on the production of Th17 cell-polarizing cytokine IL-23 and subsequent Th17 cell activation.
Methods:
Peripheral blood mononuclear cells (PBMCs) were purified using Ficoll-Paque from healthy donors. Monocytes were magnetically selected using CD14 Miltenyi beads and differentiated into DCs with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4 for five days in the presence or absence of IL-15 (100ng/ml) for long-term exposure experiments. Then, DCs were matured with peptidoglycan (PGN), or curdlan for 24 hours. For short-term exposure experiments, IL-15 was added only during maturation of DCs. Then, DCs were characterized concerning the expression of MHC II and costimulatory molecules, production of cytokine subunits IL-23p19, IL-12p40, IL-12p35 and cytokine IL-23 via flow cytometry or real-time qPCR or ELISA. Finally, the phosphorylation of signaling molecules after curdlan stimulation was assessed using phospho-flow assays.
Results:
IL-15 exposure suppressed IL-23 production by DCs. As a result, IL-15-exposed DCs suppressed IL-17 production by allogeneic T cells. Importantly, we observed a reduction in the surface Dectin-1 receptor levels by IL-15-exposed DCs. In line with these observations, curdlan stimulation resulted in reduced phosphorylation of ERK1/2, NF-kB p65 and AKT by human DCs exposed to IL-15 compared with controls. These results may explain why IL-15-exposed DCs produce less IL-23 after maturation with curdlan, which is a ligand of Dectin-1.
Conclusion:
Short- or long-term exposure to IL-15 of human DCs during their differentiation or maturation programs DCs against Th17 cell polarization, which suggests that IL-15 availability may affect CD4+ T cell-mediated protective immunity to fungal infections.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
IAR4248651 IL-12p40 human IL-12p40 human Price
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