ISSN: 2148-4902 | E-ISSN: 2536-4553
IL-15 negatively regulates curdlan-induced IL-23 production by human monocyte-derived dendritic cells and subsequent Th17 response [North Clin Istanb]
North Clin Istanb. 2019; 6(4): 379-387 | DOI: 10.14744/nci.2019.38802

IL-15 negatively regulates curdlan-induced IL-23 production by human monocyte-derived dendritic cells and subsequent Th17 response

Ahmet Eken1, Zehra Okuş1, Şerife Erdem1, Zehra Büşra Azizoğlu1, Yeşim Haliloğlu1, Ayten Biçer1, Tuğba Nur Gür1, Ebru Yilmaz2, Musa Karakukcu2, Hamiyet Donmez Altuntas1, Halit Canatan1
1Department of Medical Biology, Erciyes University Faculty of Medicine, Betül-Ziya Eren Genome and Stem Cell Center (GENKOK), Kayseri, Turkey
2Department of Pediatric Hematology-Oncology, Erciyes University Faculty of Medicine, Kayseri, Turkey

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

Keywords: Dendritic cell, IL-15; Th17; IL-23.

Ahmet Eken, Zehra Okuş, Şerife Erdem, Zehra Büşra Azizoğlu, Yeşim Haliloğlu, Ayten Biçer, Tuğba Nur Gür, Ebru Yilmaz, Musa Karakukcu, Hamiyet Donmez Altuntas, Halit Canatan. IL-15 negatively regulates curdlan-induced IL-23 production by human monocyte-derived dendritic cells and subsequent Th17 response. North Clin Istanb. 2019; 6(4): 379-387

Corresponding Author: Ahmet Eken

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