Ubiquinol decreases monocytic expression and DNA methylation of the pro-inflammatory chemokine ligand 2 gene in humans

Abstract

Background: Coenzyme Q₁₀ is an essential cofactor in the respiratory chain and serves in its reduced form, ubiquinol, as a potent antioxidant. Studies in vitro and in vivo provide evidence that ubiquinol reduces inflammatory processes via gene expression. Here we investigate the putative link between expression and DNA methylation of ubiquinol sensitive genes in monocytes obtained from human volunteers supplemented with 150 mg/ day ubiquinol for 14 days.

Findings: Ubiquinol decreases the expression of the pro-inflammatory chemokine (C-X-C motif) ligand 2 gene (CXCL2) more than 10-fold. Bisulfite-/ MALDI-TOF-based analysis of regulatory regions of the CXCL2 gene identified six adjacent CpG islands which showed a 3.4-fold decrease of methylation status after ubiquinol supplementation. This effect seems to be rather gene specific, because ubiquinol reduced the expression of two other pro-inflammatory genes (PMAIP1, MMD) without changing the methylation pattern of the respective gene.

Conclusion: In conclusion, ubiquinol decreases monocytic expression and DNA methylation of the pro-inflammatory CXCL2 gene in humans. Current Controlled Trials ISRCTN26780329.

Figure 1

Position of amplicons within the analysed genomic region (A) and methylation status of CpG islands (B-E) of the human CXCL2 gene. A, The genomic region of the CXCL2 gene is located from −365 to +450 relative to the gene start. This refers to position 74964548–74965362 of the NCBI’s human genome build 37.1. The gene is shown in its transcripted orientation and locates on the sense strand of chromosome 4. Colors illustrate position of the gene (blue), mRNA (green), region for amplicon design (orange), amplicons (yellow) and annotated (Ensembl) regulatory region (pink). B-E, Colored dots indicate the methylation ratio (%) at each analyzed CpG-unit within each amplicon. Samples are indicated as H-1 to H-5 (time point T₀) and H-1_1 to H-5_1 (T₁₄). Base count (upper ruler scale) and CpG-site numbering (lower ruler scale) refers to the analyzed strand in 5’→3’ orientation of the analyzed amplicon sequence. Sample “nc_001” represents the reaction negative control (water) and “con42” a control DNA.

Figure 2

Methylation status of CpG islands of the CXCL2 gene in monocytes of human volunteers before (T₀) and after (T₁₄) a 14 day supplementation period with ubiquinol. The extent of methylation (%, mean ± SD) of CpG islands 33, 39–44 and 45 within amplicon 2 of the CXCL2 gene (see Figure 1C) is shown.