Curcumin attenuates poly(I:C)-induced immune and inflammatory responses in mouse macrophages by inhibiting TLR3/TBK1/IFNB cascade

Abstract

This study suggested that the involvement of TLR3/TBK1/IFN-β in the underlying mechanism of curcumin alleviation of virus-like infections. • Poly(I:C) mimicked viral infection is specifically recognized by TLR3 to induce innate immune and inflammatory response. • Curcumin alleviates virus-like infection through the mitigation of TLR3/TBK1/INF-β. • Potential anti-viral effects of curcumin was investigated by transcriptomics and multiple molecular biological approaches. Curcumin is widely used in dietary supplements due to its beneficial effects on inflammatory and immune pathways. To better understand the action of curcumin during viral infection, its effect on stimulation of RAW264.7 macrophages with polyinosinic-polycytidylic acid (poly(I:C)) was evaluated by deep sequencing transcriptome, followed by RT-qPCR, western blotting and ELISA validations. The transcriptomics results showed that 157 differentially expressed genes are in association with the activity of curcumin on the cellular response to poly(I:C) stimulation. Gene Ontology and KEGG enrichment analysis uncovered the involvement of TLRs, in particular TLR3, in curcumin’s effect on poly(I:C)-induced immune and inflammatory responses. RT-qPCR results showed that curcumin (2.5, 5, 10 μM) significantly down-regulated the mRNA expression of Tlr3, Irf-7, Ifnb1, Il-6, Tnfα, and Il1bf in a dose-dependent manner. Significant down-regulation of curcumin (5 M) on protein or phosphorylated protein expressions of TLR3 (p < 0.05), TBK1 (P < 0.005), IRF3 (P < 0.0005), IRF7 (p < 0.0005), IFN-β (P < 0.0005),TNF-α (P < 0.0001) and IL6 (P < 0.0001) were also observed in western blotting or ELISA results. Taken together, these results indicated that down-regulation on TLR3/TBK1/IFN-β cascade may involve in the underlying mechanism of curcumin alleviating virus-like infections. The findings from our study contribute to a better understanding of the action of curcumin during viral infection, suggesting the potential of curcumin preparations to support a healthy immune system.