By mapping the periodontitis-related known genes in DisGeNET database to the atherosclerosis-GSE23746 dataset, one group of periodontitis-known genes, including Apolipoprotein L1 (APOL1), C-C Motif Chemokine Ligand 2 (CCL2), and Interferon Stimulated Exonuclease Gene 20 (ISG20), while the other group of periodontitis-known genes, including High Mobility Group Box 1 (HMBG1), CCL5, and MMP8 were downregulated, in the PBMs of atherosclerosis-GSE23746 dataset (Figure 3(a)). Here, CCL2 is linked to periodontitis.