MiRNA-6870-3p Regulates Lipopolysaccharide Induced Epicardial Adipose Tissue Inflammatory Genes via Targeting Tollip-Mediated JNK and NF-κB Signaling in Coronary Artery Disease

MiR-6870-3p acts as a crucial regulator of gene expression at the posttranscriptional level and participates in immune responses. However, the roles of miR-6870-3p and its target genes and their underlying mechanisms in the inflammatory responses of epicardial adipose tissues (EATs) are unknown.MiRNA microarray was used to collect the miRNA expression profiles of EATs from five patients with coronary artery disease (CAD) and four individuals without CAD (n-CAD). Quantitative real-time polymerase chain reaction (qRT-PCR) was applied to examine the expression of miR-6870-3p in the EATs. The mRNA and protein expression levels of Tollip and the key genes of the Toll-like receptor 4 (TLR4) signaling pathway were examined by qRT-PCR and Western blot analysis. The levels of inflammatory factors in the cell supernatant were measured by enzyme-linked immunosorbent assay (ELISA). We used a dual-luciferase reporter assay to validate the target gene of miR-6870-3p. The protein expression levels of c-Jun N-terminal kinase (JNK) and nuclear factor kappa B (NF-κB) were measured by Western blot analysis.Our results showed that miR-6870-3p was higher in the CAD EATs than in the n-CAD EATs. MiR-6870-3p was positively correlated with TLR4, interleukin (IL)-6, JNK, NF-κB (p65), and tumor necrosis factor (TNF)-α in the CAD EAT samples. Lipopolysaccharide (LPS) treatment upregulated the miR-6870-3p expression and downregulated the Tollip expression in the macrophages. When the macrophages were stimulated with LPS, MiR-6870-3p upregulation also aggravated the production of proinflammatory cytokines. The result of the luciferase reporter assays confirmed that miR-6870-3p directly targets Tollip. Moreover, miR-6870-3p upregulation in the macrophages resulted in the activation of the JNK/NF-κB pathway.Our study showed that miR-6870-3p regulates human EAT inflammation by targeting the Tollip-mediated JNK and NF-κB signaling pathways.