Dental Infection of Porphyromonas gingivalis Induces Preterm Birth in Mice.
Dental Infection of Porphyromonas gingivalis Induces Preterm Birth in Mice.
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DOI：
10.1371/journal.pone.0137249
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Takata T
中科院分区：
文献类型：
--
作者：
Ao M;Miyauchi M;Furusho H;Inubushi T;Kitagawa M;Nagasaki A;Sakamoto S;Kozai K;Takata T
流行病学研究揭示了牙齿感染与早产或低出生体重（PTB/LBW）之间的联系，但其潜在机制仍不清楚。理解相关机制的进展部分受到限制，因为缺乏模拟牙周炎条件下妊娠的慢性感染引起的 PTB/LBW 动物模型。我们的目的是建立慢性牙周炎小鼠模型，以研究牙周炎与 PTB/LBW 之间的联系。为了建立从牙齿感染开始的慢性炎症，我们通过手术打开小鼠（雌性，8周大）第一磨牙牙髓室，并直接感染w83菌株牙龈卟啉单胞菌（P.g），这是一种关键的牙周病原体。感染后 6 周开始交配，此时牙肉芽肿组织已发育并存活。是从拔出的牙根中培养出来的，牙根是 P.g. 的持久来源。记录P.g.感染小鼠和对照小鼠的妊娠天数（gd）和出生体重，并在gd 15时收集血清和胎盘组织以评估妊娠期间的全身和局部状况。 P.g. 牙齿感染显着增加循环中的 TNF-α（2.5 倍）、IL-17（2 倍）、IL-6（2 倍）和 IL-1β（2 倍）。 P.g.感染组的分娩时间为 gd 18.25，而未感染对照组 (NC) 组的分娩时间为 gd 20.45 (p < 0.01)，并且与对照组相比，幼仔表现出低出生体重 (p < 0.01)。 PG通过免疫组织化学和 PCR 定位于胎盘组织，并发现 P.g. 胎盘组织存在缺陷。受感染的小鼠包括胎膜早破、胎盘脱离、滋养层和内皮细胞的退行性改变，包括坏死区域。 PG感染导致胎盘组织中多形核白细胞 (PMNL) 和巨噬细胞的数量显着增加，这与促炎介质（包括 TNF-α 和 COX-2）的局部表达增加有关。 P.g. 中显示了进一步的胎盘组织损伤。感染小鼠的内皮细胞中 CD-31 减少，8OHdG（DNA 氧化损伤指标）表达增加，以及细胞凋亡标记 caspase-3 裂解。体外，P.g.脂多糖以 NF-κB 依赖性方式显着增加 HTR-8 滋养层细胞中 COX-2、IL-8 和 TNF-α 的表达。我们的新型小鼠模型支持之前的流行病学研究，表明牙齿感染是 PTB/LBW 的诱发因素。我们证明了受感染小鼠的 PTB 和 LBW、P.g 易位至胎盘组织、循环和局部促炎标记物增加以及 P.g 的能力。 LPS 在体外直接诱导滋养层细胞产生细胞因子。这些发现进一步强调了怀孕期间局部和全身感染和炎症的重要性，并表明怀孕前预防和/或消除牙齿感染（例如边缘或根尖周炎）可能对 PTB/LBW 产生有益影响。
Epidemiological studies have revealed a link between dental infection and preterm birth or low birth weight (PTB/LBW), however, the underlying mechanisms remain unclear. Progress in understanding the associated mechanisms has been limited in part by lack of an animal model for chronic infection-induced PTB/LBW, mimicking pregnancy under conditions of periodontitis. We aimed to establish a mouse model of chronic periodontitis in order to investigate the link between periodontitis and PTB/LBW. To establish chronic inflammation beginning with dental infection, we surgically opened mouse (female, 8 weeks old) 1st molar pulp chambers and directly infected with w83 strain Porphyromonas gingivalis (P.g.), a keystone periodontal pathogen. Mating was initiated at 6 wks post-infection, by which time dental granuloma tissue had developed and live P.g. was cultured from extracted tooth root, which serves as a persistent source of P.g. The gestational day (gd) and birth weight were recorded during for P.g.-infected and control mice, and serum and placental tissues were collected at gd 15 to evaluate the systemic and local conditions during pregnancy. Dental infection with P.g. significantly increased circulating TNF-α (2.5-fold), IL-17 (2-fold), IL-6 (2-fold) and IL-1β (2-fold). The P.g.-infected group delivered at gd 18.25 vs. gd 20.45 in the non-infected control (NC) group (p < 0.01), and pups exhibited LBW compared to controls (p < 0.01). P.g. was localized to placental tissues by immunohistochemistry and PCR, and defects in placental tissues of P.g. infected mice included premature rupture of membrane, placental detachment, degenerative changes in trophoblasts and endothelial cells, including necrotic areas. P.g. infection caused significantly increased numbers of polymorphonuclear leukocytes (PMNLs) and macrophages in placental tissues, associated with increased local expression of pro-inflammatory mediators including TNF-α and COX-2. Further placental tissue damage was indicated in P.g. infected mice by decreased CD-31 in endothelial cells, increased expression of 8OHdG, an indicator of oxidative DNA damage, and cleaved caspase-3, a marker of apoptosis. In vitro, P.g. lipopolysaccharide significantly increased expression of COX-2, IL-8 and TNF-α, in HTR-8 trophoblasts in an NF-κB-dependent fashion. Our novel mouse model supports previous epidemiological studies signifying dental infection as predisposing factor for PTB/LBW. We demonstrate PTB and LBW in infected mice, translocation of P.g to placental tissues, increased circulating and local pro-inflammatory markers, and the capability of P.g. LPS to directly induce cytokine production in trophoblasts, in vitro. These findings further underscore the importance of local and systemic infections and inflammation during pregnancy and suggest that prevention and/or elimination of dental infections such as marginal or periapical periodontitis before pregnancy may have a beneficial effect on PTB/LBW.