Echinococcus granulosus cyst fluid inhibits inflammatory responses through inducing histone demethylase KDM5B in macrophages

Background Echinococcus granulosus cyst fluid (EgCF) weakens macrophage inflammatory responses, thereby enabling the parasite to evade the immune system. However, the role of histone modification in this process remains to be explored.Methods The levels of IL-6, TNF-α, IL-10, H3K4me3, and KDM5B were detected using quantitative real-time PCR, ELISA, and Western blotting. The enrichment of H3K4me3 and KDM5B at the promoter of inflammatory factors was detected by chromatin immunoprecipitation.Results Based on EgCF-stimulated macrophage models, we found that EgCF significantly inhibited mRNA expression and protein secretion of IL-6 and TNF-α and upregulated mRNA expression of IL-10 under the influence of TLR4. EgCF lowered the level of H3K4me3 and promoted the transcription and protein stability of histone demethylase KDM5B. Chromatin immunoprecipitation analysis revealed that EgCF suppressed the enrichment of H3K4me3 modification at the promoters of TNF-α and IL-6 and downregulated their expression in macrophages. Additionally, the inhibition of KDM5B activity by CPI-455 weakened the anti-inflammatory effect of EgCF.Conclusion sOur findings demonstrate a novel mechanism through which EgCF promotes KDM5B expression and inhibits the enrichment of H3K4me3 at the promoters of inflammatory cytokines to suppress the inflammatory response.Graphical Abstract

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