Son Ga-Yeon, Bak Eun-Jung, Kim Ji-Hye, Lee Dong Eun, Kang Si-Mook, Lee So Yun, Choi Lin, Sun Ji Su, Kim Seul Ki, Park Wonse, Kim Baek Il, Yoo Yun-Jung, Chang Inik, Shin Dong Min
Department of Oral Biology, Yonsei University College of Dentistry, Seoul, Republic of Korea.
BK21 PLUS Project, Yonsei University College of Dentistry, Seoul, Republic of Korea.
PLoS One. 2016 Dec 28;11(12):e0167713. doi: 10.1371/journal.pone.0167713. eCollection 2016.
Periodontitis is a very common oral inflammatory disease that results in the destruction of supporting connective and osseous tissues of the teeth. Although the exact etiology is still unclear, Gram-negative bacteria, especially Porphyromonas gingivalis in subgingival pockets are thought to be one of the major etiologic agents of periodontitis. Endothelin (ET) is a family of three 21-amino acid peptides, ET-1, -2, and -3, that activate G protein-coupled receptors, ETA and ETB. Endothelin is involved in the occurrence and progression of various inflammatory diseases. Previous reports have shown that ET-1 and its receptors, ETA and ETB are expressed in the periodontal tissues and, that ET-1 levels in gingival crevicular fluid are increased in periodontitis patients. Moreover, P. gingivalis infection has been shown to induce the production of ET-1 along with other inflammatory cytokines. Despite these studies, however, the functional significance of endothelin in periodontitis is still largely unknown. In this study, we explored the cellular and molecular mechanisms of ET-1 action in periodontitis using human gingival epithelial cells (HGECs). ET-1 and ETA, but not ETB, were abundantly expressed in HGECs. Stimulation of HGECs with P. gingivalis or P. gingivalis lipopolysaccharide increased the expression of ET-1 and ETA suggesting the activation of the endothelin signaling pathway. Production of inflammatory cytokines, IL-1β, TNFα, and IL-6, was significantly enhanced by exogenous ET-1 treatment, and this effect depended on the mitogen-activated protein kinases via intracellular Ca2+ increase, which resulted from the activation of the phospholipase C/inositol 1,4,5-trisphosphate pathway. The inhibition of the endothelin receptor-mediated signaling pathway with the dual receptor inhibitor, bosentan, partially ameliorated alveolar bone loss and immune cell infiltration. These results suggest that endothelin plays an important role in P. gingivalis-mediated periodontitis. Thus, endothelin antagonism may be a potential therapeutic approach for periodontitis treatment.
牙周炎是一种非常常见的口腔炎症性疾病，会导致牙齿支持性结缔组织和骨组织的破坏。尽管确切病因仍不清楚，但革兰氏阴性菌，尤其是龈下袋中的牙龈卟啉单胞菌被认为是牙周炎的主要病因之一。内皮素（ET）是由三种21个氨基酸的肽组成的家族，即ET-1、-2和-3，它们激活G蛋白偶联受体ETA和ETB。内皮素参与各种炎症性疾病的发生和发展。先前的报道表明，ET-1及其受体ETA和ETB在牙周组织中表达，并且牙周炎患者龈沟液中的ET-1水平升高。此外，牙龈卟啉单胞菌感染已被证明会诱导ET-1以及其他炎症细胞因子的产生。然而，尽管有这些研究，内皮素在牙周炎中的功能意义仍然很大程度上未知。在本研究中，我们使用人牙龈上皮细胞（HGECs）探索了ET-1在牙周炎中的细胞和分子作用机制。ET-1和ETA在HGECs中大量表达，但ETB不表达。用牙龈卟啉单胞菌或牙龈卟啉单胞菌脂多糖刺激HGECs会增加ET-1和ETA的表达，提示内皮素信号通路被激活。外源性ET-1处理显著增强了炎症细胞因子IL-1β、TNFα和IL-6的产生，并且这种作用通过细胞内Ca2+增加依赖于丝裂原活化蛋白激酶，这是由磷脂酶C/肌醇1,4,5-三磷酸途径的激活导致的。用双重受体抑制剂波生坦抑制内皮素受体介导的信号通路可部分改善牙槽骨丧失和免疫细胞浸润。这些结果表明内皮素在牙龈卟啉单胞菌介导的牙周炎中起重要作用。因此，内皮素拮抗作用可能是牙周炎治疗潜在的治疗方法。
