Gene Co-expression And Meta-analysis Of Human Coronary Artery Disease Identified A Novel Mechanism Of Macrophage Activation Through Lncrna SPANXA2-OT1/mir-338/ IL-8 Triad

Background: Coronary artery disease (CAD) remains the leading cause of mortality worldwide. Although long noncoding RNAs (lncRNAs) do not translate into protein, they interact with DNA, RNA, miRNA, and proteins. lncRNAs thus are interesting therapeutic targets. lncRNAs act as miRNA sponges by sequestering miRNA molecules, which in turn suppress miRNA activity, resulting in consequent increases in the levels of miRNA target genes. But how lncRNAs regulate the pathology of CAD via miRNA sponge formation, however, remain incompletely understood. Methods: We performed gene-expression meta-analysis to identify differentially expressed lncRNAs, miRNA and mRNAs in CAD using a comprehensive 4-part analysis pipeline (Fig A). We performed the weighted gene co-expression network analysis (WGCNA) by analyzing GSE40231 dataset to confirm highly correlated lncRNAs and its coding gene partners. Using human primary macrophages we conducted in vitro validation of the candidate coding-noncoding RNA regulatory triad. Results: Our computational analysis led to 2332 mRNAs, 159 miRNAs and 515 lncRNAs that were significantly higher or lower in human CAD patients as compared to control. WGCNA identified 26 lncRNA-mRNA co-expression modules (Fig B and C). Network prioritization of top co-expression modules identified the lncRNA, SPANXA-OT1, as a potential key candidate. In human primary macrophages, luciferase assay established that SPANXA2-OT1 binds to miR-338 through its miRNA response elements (Fig D-F). Gain-of-function and loss-of-function experiments revealed that SPANXA2-OT1 and miR-338 regulates the expression of proinflammatory genes, e.g., IL-8 , that may contribute to the pathophysiology of CAD (Fig G and H). Conclusion: Our results indicate that the lncRNA, SPANXA2-OT1 , binding to miR-338 plays an important role in IL-8-mediated inflammation and may provide molecular basis for the identification of novel therapeutic targets for CAD.