Mining Of Hub Immune-related LncRNAs In Coronary Artery Disease And Multi-omics Integration Analysis Of Characteristics Of Immune Molecules In Ischemic Cardiomyopathy

Coronary artery disease（CAD）is the most common type of cardiovascular diseases,and its pathological basis is atherosclerosis.Studies have shown that the dysregulation of long noncoding RNAs（lncRNAs）is closely related to the occurrence and progression of CAD.But until now,the knowledge of their physiological or pathological functional mechanisms in CAD is very limited.Ischemic cardiomyopathy（ICM）is regarded as a special type or advanced stage of CAD.Its pathological basis is that atherosclerosis lesions cause long-term myocardial ischemia and hypoxia,as well as myocardial cell reduction,necrosis and diffuse myocardial fibrosis.A large number of preclinical studies have shown that immunomodulatory therapy can reduce inflammatory indicators and myocardial infarction size,and prevent adverse ventricular remodeling.But in clinical studies,the therapeutic effect is not ideal or invalid,and there is no clear answer to this question at present.In this study,we first constructed an immune-related lncRNA-mRNA weighted gene co-expression network to systematically analyze immune-related lncRNAs in CAD.Subsequently,LINC01480 and AL359237.1 were identified as key immune lncRNAs in CAD by least absolute shrinkage and selection operator（LASSO）logistic regression and random forest-recursive feature elimination（RF-RFE）algorithms.In addition,the 93 CAD samples could be divided into two clusters according to the expression values of LINC01480 and AL359237.1 by consensus clustering analysis.By performing gene set enrichment analysis（GSEA）,we found that the patients in cluster 2 might be more likely to show clinical symptoms.Notably,we found that LINC01480 was also highly expressed in ICM left ventricular tissue samples.Immune cell infiltration analysis and gene set variation analysis（GSVA）further showed that LINC01480 might mediate the differentiation of M0macrophages into M2 macrophages,and inhibit the insulin signaling pathway and mTOR signaling pathway to slow the process of ICM.In order to explore the expression characteristics of immune molecules in ICM,we performed a multi-omics integrated analysis on 1793 immune genes from the ImmPort database.First,GSE5406 and GSE57338 had been merged and then for differentially expressed analysis.When|log₂（FC）|>0.5,adj.p.value<0.01 was used to select the differentially expressed mRNAs,we have got 28 differentially expressed immune mRNAs;subsequently,differential expression analysis was performed on ICM-related proteomics data.When the screening threshold was set at adj.p.value<0.05,19 differential immune proteins were identified.Meanwhile,we constructed a protein-metabolite regulatory network,which might help us to understand the immune mechanism of ICM from a metabolic perspective.In order to further screen the key immune molecules in ICM,LASSO logistic regression and RF-RFE algorithms were used again to analyze the 28 immune mRNAs,which jointly identified 7 candidate key immune mRNAs.Subsequently,six external datasets were introduced to further verify the expression trend of these seven molecules and we identified four key immune mRNAs（NPPA,OGN,LTBP2 and PTN）.By the analysis of ICM-related single cell sequencing data,we found that NPPA could be derived from all cell types,while OGN,LTBP2,and PTN were only transcribed by fibroblasts.In addition,the proteome expression profile of ICM showed that the protein and mRNAs expression trends of OGN and LTBP2 in ICM samples were consistent,and both of them were up-regulated.In addition,western blotting（WB）and immunohistochemical（IHC）analysis using independent heart samples showed that the protein and mRNA expressions of PTN were also consistent,both of which were up-regulated.In conclusion,our study laid a foundation for further exploration of the mechanism of immune dysfunction and the role of key immune lncRNAs in CAD.In addition,our study also provides some insights for further understanding the inflammatory mechanism in ICM and designing the multi-targeted drugs for immunomodulatory therapy.