DNA methylation signature of chronic low-grade inflammation and its role in cardio-respiratory diseases

<title>Abstract</title> We performed a trans-ethnic Epigenome Wide Association study on 22,774 individuals to describe the DNA methylation signature of chronic low-grade inflammation as measured by C-Reactive protein (CRP). We found 1,511 independent differentially methylated loci associated with CRP. These CpG sites showed correlation structures across chromosomes, and were primarily situated in euchromatin, depleted in CpG islands and enriched in transcription factor binding sites and genomic enhancer regions. Mendelian randomisation analysis suggests altered CpG methylation is a consequence of increased blood CRP levels. Mediation analysis revealed obesity and smoking as important underlying driving factors for changed CpG methylation. Finally, we found that a fully activated CpG signature, meaning that if all novel discovered CpGs would either be fully methylated or unmethylated depending on their CRP associated direction of effect, the risk of myocardial infarction would be increased by 20.3%, risk of T2D by 11.3% and the risk of COPD by 5.6%.