Epigenetic Signature of Chronic Low Back Pain in Human T Cells

We performed genome-wide DNA methylation analysis of 850,000 CpG sites in women and men with chronic Low Back Pain (LBP) and pain free-controls. T cells were isolated (Discovery Cohort, n=32) and used to identify differentially methylated CpG sites, and gene ontologies and molecular pathways were identified.T cells were isolated (Discovery Cohort, n=32) and used to identify differentially methylated CpG sites, and gene ontologies and molecular pathways were identified. A polygenic DNA methylation score for LBP was generated in both women and men. Validation was performed in an independent cohort (Validation Cohort, n=63) of chronic LBP and healthy controls. Analysis with the Discovery Cohort revealed a total of 2,496 and 419 differentially methylated CpGs in women and men, respectively. The majority of these sites were hypo-methylated in women and enriched in genes with functions in the extracellular matrix, the immune system (i.e. cytokines) or in epigenetic processes. In men, we identified a unique chronic LBP DNA methylation signature characterized by significant enrichment for genes from the major histocompatibility complex. A sex-specific polygenic DNA methylation score was generated to evaluate the pain status of each individual and confirmed in The Validation Cohort using pyrosequencing. CD3+ T cells were isolated, DNA was isolating and bisulfite conversion was performed. DNA methylation profiles were generated using Illumina® 850 K bead arrays (Infinium MethylationEPIC Kit).