Diphenyldifluoroketone EF24 Suppresses Pro-inflammatory Interleukin-1 receptor 1 and Toll-like Receptor 4 in lipopolysaccharide-stimulated dendritic cells

Unresolved and prolonged inflammation is a pathological basis of many disorders such as cancer and multiple organ failure in shock. Interleukin-1 receptor (IL-1R) superfamily consists of IL-1R1 and pathogen pattern recognition receptor toll-like receptor-4 (TLR4) which, upon ligand binding, initiate pro-inflammatory signaling. The study objective was to investigate the effect of a diphenyldifluoroketone EF24 on the expression of IL-1R1 and TLR4 in lipopolysaccharide (LPS)-stimulated dendritic cells (DCs). Immortalized murine bone marrow-derived JAWS II dendritic cells (DC) were challenged with LPS (100 ng/ml) for 4 h. The LPS-stimulated DCs were treated with 10 μM of EF24 for 1 h. The expression levels of IL-1R1 and TLR4 were monitored by RT-PCR, immunoblotting, and confocal microscopy. The effect of EF24 on the viability and cell cycle of DCs was examined by lactate dehydrogenase assay and flow cytometry, respectively. EF24 treatment suppressed the LPS-induced TLR4 and IL-1R1 expression in DCs. However, the expression levels of IL-1RA and IL-1R2 were not influenced by either LPS or EF24 treatments. These effects of EF24 were associated with a decrease in LPS-induced expression of phospho-NF-kB p65, indicative of its role in the transcriptional control of IL-1R superfamily members. We did not find any significant effect of EF24 on the proliferation or cell cycle of DCs. The results suggest that EF24 influences IL-1R superfamily signaling pathway in ways that could have salutary effects in inflammation. The pluripotent anti-inflammatory actions of EF24 warrant further investigation of EF24 in inflammatory conditions of systemic nature.