TLR2 Promoter Hypermethylation Creates Innate Immune Dysbiosis
TLR2 Promoter Hypermethylation Creates Innate Immune Dysbiosis
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DOI：
10.1177/0022034514557545
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发表时间：
2015-01-01
影响因子：
7.6
通讯作者：
Kinane, D. F.
中科院分区：
文献类型：
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作者：
Benakanakere, M.;Abdolhosseini, M.;Kinane, D. F.
牙周炎是一种常见的慢性炎症性疾病，由复杂的微生物生物膜引发，在全球范围内造成严重的健康和经济负担。牙龈卟啉单胞菌是维持慢性炎症性牙周炎的主要病原体。Toll样受体（TLR）通过识别病原体和维持组织稳态在牙周炎中起重要作用。TLR表达和下游信号传导的缺陷可能会降低宿主对病原体的先天防御，导致细菌持续存在和炎症加剧，这在疾病病理学中得到了更好的理解。在牙周炎的情况下，牙龈上皮细胞形成抵抗病原体的第一道防线。这些细胞中的先天性免疫失调与严重的疾病病理学有关。我们最近发现，在牙龈卟啉单胞菌刺激后，某些牙龈上皮细胞表达减弱的细胞因子信号传导，TLR2表达减弱。在对TLR2启动子CpG岛进行详细分析后，我们注意到在这种失调的细胞类型中存在较高的CpG甲基化。当用DNA甲基转移酶抑制剂处理这些细胞时，TLR2 mRNA和细胞因子表达显著增加。如果TLR2表达质粒在牙龈卟啉单胞菌刺激之前在功能失调的细胞中异位表达，则细胞因子表达增加，证实牙龈卟啉单胞菌介导的炎症反应中需要TLR2。我们设计了一种慢性体外感染模型来测试牙龈卟啉单胞菌是否可以在激动剂刺激后表达更高TLR 2的正常牙龈上皮细胞中诱导DNA甲基化。用牙龈卟啉单胞菌对正常上皮细胞的慢性治疗在细胞内引入了从头DNA甲基化。此外，在牙周炎口服灌胃模型中，在感染牙龈卟啉单胞菌的小鼠牙龈中观察到DNA甲基化增加。此外，从牙周炎患者获得的组织也表现出差异TLR2启动子甲基化，如亚硫酸氢盐DNA测序所揭示的。总之，TLR2的DNA甲基化可以调节宿主的先天防御机制，这可能会增加疾病的易感性。
Periodontitis is a common chronic inflammatory disease that is initiated by a complex microbial biofilm that poses significant health and financial burdens globally. Porphyromonas gingivalis is a predominant pathogen that maintains chronic inflammatory periodontitis. Toll-like receptors (TLRs) play an important role in periodontitis by recognizing pathogens and maintaining tissue homeostasis. Deficiencies in TLR expression and downstream signaling may reduce the host's innate defenses against pathogens, leading to bacterial persistence and exacerbated inflammation, which are now being better appreciated in disease pathologies. In the case of periodontitis, gingival epithelial cells form the first line of defense against pathogens. Innate immune dysregulation in these cells relates to severe disease pathology. We recently identified a blunted TLR2 expression in certain gingival epithelial cells expressing diminished cytokine signaling upon P. gingivalis stimulation. Upon detailed analysis of the TLR2 promoter CpG Island, we noted higher CpG methylation in this dysregulated cell type. When these cells were treated with DNA methyltransferase inhibitor, TLR2 mRNA and cytokine expression were significantly increased. If TLR2 expression plasmid was ectopically expressed in dysfunctional cells prior to P. gingivalis stimulation, the cytokine expression was increased, confirming the requirement of TLR2 in the P. gingivalis-mediated inflammatory response. We designed a chronic in vitro infection model to test if P. gingivalis can induce DNA methylation in normal gingival epithelial cells that express higher TLR2 upon agonist stimulation. Chronic treatment of normal epithelial cells with P. gingivalis introduced de novo DNA methylation within the cells. In addition, increased DNA methylation was observed in the gingiva of mice infected with P. gingivalis in a periodontitis oral gavage model. Moreover, tissues obtained from periodontitis patients also exhibited differential TLR2 promoter methylation, as revealed by bisulfite DNA sequencing. Taken together, DNA methylation of TLR2 can modulate host innate defense mechanisms that may confer increased disease susceptibility.