Fig. 2.

Aberrant DNA methylation induced in gastric mucosae by aging and active inflammation due to current infection. a Global difference of methylation levels (β values) between HP-negative young gastric mucosae (HP(−) young) and HP-negative old mucosae (HP(−) old) and between HP-negative young mucosae (HP(−) young) and HP-positive young mucosae (HP current young). Even after correction of contamination of leukocytes, a large number of blocks (44,461 and 51,078 blocks (16.5% and 18.9%)) were aberrantly hyper- or hypomethylated by inflammation. b Targeted deep bisulfite sequencing for the CGI/TSS200 regions of four genes. Yellow square, methylated CpG site; blue square, unmethylated CpG site. c Methylation changes by aging and inflammation. The horizontal axis shows methylation changes by aging and the vertical axis shows methylation changes by inflammation. Most genomic blocks hyper- or hypomethylated by inflammation were also hyper- or hypomethylated at low levels by aging. d Methylation changes by inflammation in the 141,892 blocks not methylated by aging (Δβ value < 0.02, inside dotted line in (c)). 9596 and 17,450 blocks (6.8% and 12.3%) were hyper- or hypomethylated in HP current young gastric mucosae