Early targeted DNA methylation profiling of CD04+/CD08+ T cells reveals pathogenic mechanisms in different stages of impaired glucose homeostasis Cardiovascular Diabetology

Abstract Background: Despite current intensive treatments, hyperglycemic patients have an unfavorable prognosis due to severe CHD and development of complications. The interplay between hyperglycemia and systemic inflammation can modify patterns of gene expression mainly affecting DNA methylation in promoter regions and, thus, endothelial damage. However, DNA methylome of CD04+ and CD08+ T cells, which play a relevant role in endothelial dysfunction has not been studied, especially during increasing hyperglycemia.Purpose: To identify differentially methylated regions (DRMs) in CD04 + and CD08 + T cells by comparing healthy subjects (HS) to Pre-Diab and type 2 (T2D) patients. This approach would investigate possible biomarkers useful to identify vascular damage already at Pre-Diab state.Methods: In this pilot study, we enrolled a subgroup of patients from our ongoing PIRAMIDE clinical trial (NCT03792607) including a total of 14 individuals classified in HS (n=2), Pre-Diab (n=6), and T2D (n=6). The DMRs were identified by using the reduced representation bisulfite sequencing platform (RRBS) which captures the majority of promoters and CpG islands. Big data analysis was performed by using the R package and ChromHMM algorithms.Results: Most of the total DMRs (30-35%) were in the promoter regions in increasing hyperglycemia vs HS. A global analysis of DMR-related genes overlapping between Pre-Diab and T2D patients showed a prevalence of DNA hypermethylation in both T cells. Interestingly, the secreted protein acidic and cysteine rich (SPARC) gene was annotated to the most hypomethylated-DMR in Pre-Diab and its methylation level gradually decreased in T2D patients.Conclusions: Preliminary data indicated that hypomethylation of the SPARC promoter may be a useful biomarker of vascular complications in Pre-Diab patients with a possible role for primary prevention. However, larger multicenter trials are needed to validate our epigenetic data in the clinical arena.