D-2-Hydroxyglutarate and L-2-Hydroxyglutarate Inhibit IL-12 Secretion by Human Monocyte-Derived Dendritic Cells.

Ines Ugele,Katrin Peter,Jakob Boesch,Eva Gottfried,Marina Kreutz,Kathrin Renner,Peter Oefner,Christina Bruss,Zugey Cárdenas-Conejo,Katja Dettmer,Monika Wehrstein,Katrin Singer,Kathrin Hammon

doi:10.3390/ijms20030742

Abstract

Mutations in isocitrate dehydrogenase (IDH) or a reduced expression of L-2-hydroxyglutarate (HG)-dehydrogenase result in accumulation of D-2-HG or L-2-HG, respectively, in tumor tissues. D-2-HG and L-2-HG have been shown to affect T-cell differentiation and activation; however, effects on human myeloid cells have not been investigated so far. In this study we analyzed the impact of D-2-HG and L-2-HG on activation and maturation of human monocyte-derived dendritic cells (DCs). 2-HG was taken up by DCs and had no impact on cell viability but diminished CD83 expression after Lipopolysaccharides (LPS) stimulation. Furthermore, D-2-HG and L-2-HG significantly reduced IL-12 secretion but had no impact on other cytokines such as IL-6, IL-10 or TNF. Gene expression analyses of the IL-12 subunits p35/IL-12A and p40/IL-12B in DCs revealed decreased expression of both subunits. Signaling pathways involved in LPS-induced cytokine expression (NFkB, Akt, p38) were not altered by D-2-HG. However, 2-HG reprogrammed LPS-induced metabolic changes in DCs and increased oxygen consumption. Addition of the ATP synthase inhibitor oligomycin to DC cultures increased IL-12 secretion and was able to partially revert the effect of 2-HG. Our data show that both enantiomers of 2-HG can limit activation of DCs in the tumor environment.

Highlights

Point mutations in IDH1 and IDH2 are detected in different types of malignancies such as glioma and glioblastoma [1,2,3], acute myeloid leukemia (AML), and head and neck squamous cell carcinoma (HNSCC)
Immature dendritic cells (DCs) were stimulated with 100 ng/mL Lipopolysaccharides (LPS) and treated with 10 mM D-2-HG or L-enantiomer of 2-HG (L-2-HG) for 1 h or 24 h, respectively
In different tumor entities 2-HG accumulation is associated with worse prognosis and recent data suggest a negative correlation between 2-HG levels in gliomas and the anti-tumor immune response [21,31]

Summary

Introduction

Point mutations in IDH1 and IDH2 are detected in different types of malignancies such as glioma and glioblastoma [1,2,3], acute myeloid leukemia (AML), and head and neck squamous cell carcinoma (HNSCC). Increased levels of 2-HG in tumor tissues have been described in tumor entities lacking IDH mutations. In renal cell carcinoma [7], the L-enantiomer of 2-HG (L-2-HG) accumulates based on reduced expression of L-2-HG dehydrogenase, the enzyme which normally degrades L-2-HG. In both cancer entities, 2-HG accumulation is associated with worse prognosis

Methods

Results

Conclusion