Table 2 Alterations in promoter methylation of selected genes in the gingival tissue from patients with periodontitis
Gene promoter | Study authors | Number of participants (healthy individuals: patients with periodontitis) | Outcome |
|---|---|---|---|
Genes associated with tissue responses | |||
 IFNG | Zhang et al. [75] | 23:12 (+ 12 participants with experimentally induced gingivitis) | ↓ (no difference between experimentally induced gingivitis and healthy subjects) |
Viana et al. [76] | 16:18 | ─ | |
Asa’ad et al. [77] | 10:10 (methylation was also assessed 2 and 8 weeks post-therapy) | ─ (no change in the course of periodontal therapy) | |
 IL6 | Barros and Offenbacher [78] | 10:10 | ↑ |
Kobayashi et al. [79] | 30:30 | ─ | |
Stefani et al. [80] | 21:21 | ─ | |
 IL10 | Viana et al. [76] | 16:18 | ─ |
 IL17 | Barros and Offenbacher [78] | 10:10 | ↑ |
 IL17C | Schulz et al. [89] | 10:15 (aggressive periodontitis patients) | ↓ |
 CXCL3 | Barros and Offenbacher [78] | 10:10 | ↑ |
Schulz et al. [89] | 10:15 (aggressive periodontitis patients) | ─ | |
 CXCL5 | Barros and Offenbacher [78] | 10:10 | ↑ |
Schulz et al. [89] | 10:15 (aggressive periodontitis patients) | ─ | |
 IL8 | Barros and Offenbacher [78] | 10:10 | ↓ |
Oliveira et al. [81] | 41:70 (periodontitis group divided into 30 smokers and 40 non-smokers) | ─ (no difference between smokers and non-smokers) | |
 CXCL10 | Barros and Offenbacher [78] | 10:10 | ↑ |
 CCL25 | Schulz et al. [89] | 10:15 (aggressive periodontitis patients) | ↓ |
 TNF | Zhang et al. [82] | 17:18 (+ 11 participants with experimentally induced gingivitis) | ↑ (no difference between experimentally induced gingivitis and healthy subjects) |
Asa’ad et al. [77] | 10:10 (methylation was also assessed 2- and 8-weeks after therapy) | ─ (no change in the course of periodontal therapy) | |
 PTGS2 (COX2) | Zhang et al. [84] | 6:10 | ↑ |
Loo et al. [85] | 108:110 (comparison between blood samples from healthy donors and gingival tissue biopsies from patients with periodontitis) | ↑ | |
Asa’ad et al. [77]; | 10:10 (methylation was also assessed 2- and 8-weeks after therapy) | ↑ (periodontal treatment reduced the methylation status to the levels observed in healthy subjects) | |
Genes coding for receptors, signaling molecules and transcription factors of inflammation-related pathways | |||
 TLR2 | de Faria Amormino et al. [86] | 20:20 | ↑ |
De Oliveira et al. [83]; | 11:23 (periodontitis group was divided into 11 smokers and 12 non-smokers) | ─ (inconclusive results: mosaic of methylated and unmethylated DNA. Site-specific (restriction enzyme-specific) trend toward increased methylation in periodontitis non-smokers) | |
Barros and Offenbacher [78] | 10:10 | ─ (strong trend toward decreased methylation in patients with periodontitis, which did not reach statistical significance) | |
 TLR4 | De Oliveira et al. [83]; | 11:23 (periodontitis group was divided into 11 smokers and 12 non-smokers) | ─ (no difference between smokers and non-smokers) |
 IL4R | Barros and Offenbacher [78] | 10:10 | ↓ |
Schulz et al. [89] | 10:15 (aggressive periodontitis patients) | ─ | |
 IL6ST | Barros and Offenbacher [78] | 10:10 | ↑ |
Schulz et al. [89] | 10:15 (aggressive periodontitis patients) | ─ | |
 TNFRSF18 | Barros and Offenbacher [78] | 10:10 | ↑ |
 STAT5A | Barros and Offenbacher [78] | 10:10 | ↓ |
Azevedo et al. [87] | 20:20 | ↓ | |
 TYK2 | Barros and Offenbacher [78] | 10:10 | ─ |
Schulz et al. [89] | 10:15 (aggressive periodontitis patients) | ─ | |
 SOCS1 | Planello et al. [146] | 44:46 | ↓ |
 SOCS3 | Barros and Offenbacher [78] | 10:10 | ↑ |
 RUNX | Barros and Offenbacher [78] | 10:10 | ↑ |
 GATA3 | Barros and Offenbacher [78] | 10:10 | ↑ |
Schulz et al. [89] | 10:15 (aggressive periodontitis patients) | ─ | |