Role of Notch-1/PLA2-IIA in oral dysbiosis, inflammation, and periodontal disease

在特定病原菌存在下粘膜对微生物群的反应机制 种（例如牙龈卟啉单胞菌-Pg），可以消除宿主-微生物共生关系，导致生态失调， 炎症性疾病仍未完全了解。我们的开创性R21研究表明，Pg诱导的 磷脂酶A2 IIA组（PLA 2-IIA），在涉及通过以下途径激活Notch-1受体（N1 R）的机制中 牙龈卟啉菌蛋白酶，调节口腔上皮细胞（OECs）的抗菌特性。这与在 支持PLA 2-IIA的有效（ng/mL）抗微生物作用的体内和临床证据。值得注意的，口头 细菌物种对PLA 2-IIA表现出不同的抗菌敏感性。此外，牙龈PLA 2-IIA 在牙周病的发生和发展过程中，N1 R的表达和活化水平升高， 与非人类灵长类动物口腔生态失调同时发生。根据这些意见，初步 使用小鼠模型进行的研究表明， Pg感染。值得注意的是，过表达PLA 2-IIA（PLA 2-IIA-Tg）的转基因小鼠的口腔微生物组 在细菌种类的丰度方面表现出显著差异（厚壁菌门减少，厚壁菌门增加）。 变形菌门）与它们的野生型共笼同窝仔相比。PLA 2-IIA-Tg小鼠中的口服生态失调是 与参与细胞内传感（NOD 2）的基因的牙龈表达变化相关，经典的 抗微生物因子（S100 a8/S100 a9，hBD 1）和M1/M2巨噬细胞趋化因子。N1 R是一个关键的调制器 因此，Pg在OEC中激活N1 R的能力是一个令人兴奋和创新的研究。 观察.初步数据表明，其他OEC功能/反应（细菌传感，凋亡， 自噬）可能涉及Pg诱导的N1 R活化。基于这一证据，我们假设， Notch-1/PLA 2-IIA通路在牙龈上皮表面的表达可能是一个创新的和合理的机制， 其中Pg等病原体可以特异性地增强口腔生态失调、炎症和牙周病。到 为了验证这一假设，我们提出了三个具体的目标：（i）确定PLA 2-IIA在Pg诱导的细胞凋亡中的作用。 口腔生态失调，炎症和牙周病，（ii）确定上皮细胞的作用， Notch-1在Pg诱导的PLA 2-IIA和牙周炎中的作用，以及（iii）鉴定和验证口服 Pg通过Notch-1激活调节上皮固有反应。解决这些 知识的差距，我们将使用Pg诱导的牙周炎口服灌胃模型的小鼠品系，有或没有一个 天然PLA 2-IIA突变，PLA 2-IIA-Tg小鼠及其WT同窝仔，上皮特异性N1 R缺陷小鼠， 以及OEC培养，以验证该途径在Pg诱导的口腔生态失调和牙周病中的作用。 这些发现将使我们能够更好地理解细胞和分子机制， 由病原体调节，以改变粘膜表面的微生物群落， 用于未来的研究，旨在确定N1 R在口腔健康和其他疾病中的作用（例如，口腔癌）。

The mechanisms by which mucosal responses to the microbiota in the presence of specific pathogenic bacterial species (e.g. P. gingivalis-Pg), could abrogate the host-microbe symbiotic relationship leading to dysbiosis and inflammatory disease remain not fully understood. Our pioneering R21 studies demonstrated that Pg-induced phospholipase A2 group IIA (PLA2-IIA), in a mechanism that involves activation of Notch-1 receptor (N1R) by Pg gingipains, modulates the antimicrobial properties of oral epithelial cells (OECs). This is consistent with in vivo and clinical evidence supporting the potent (ng/mL) antimicrobial effects of PLA2-IIA. Noteworthy, oral bacterial species exhibited differential antimicrobial susceptibility to PLA2-IIA. Moreover, gingival PLA2-IIA expression and N1R activation were elevated during initiation and progression of periodontal disease, which was concurrent with oral dysbiosis in non-human primates. In agreement with these observations, new preliminary studies using mice models demonstrated increased gingival PLA2-IIA expression and N1R activation early after Pg infection. Remarkably, the oral microbiome of transgenic mice overexpressing PLA2-IIA (PLA2-IIA-Tg) exhibited significant differences in the abundance of bacterial species (decreased Firmicutes and increased Proteobacteria) compared to their wild type co-caged littermates. Oral dysbiosis in PLA2-IIA-Tg mice was associated with changes in the gingival expression of genes involved in intracellular sensing (NOD2), classical antimicrobial factors (S100a8/S100a9, hBD1), and M1/M2 macrophage chemokines. N1R is a critical modulator of mucosal immunity; therefore, the ability of Pg to activate N1R in OECs is an exciting and innovative observation. Preliminary data suggested that other OEC functions/responses (bacterial sensing, apoptosis, and autophagy) could involve Pg-induced N1R activation. Based on this evidence, we hypothesize that activation of Notch-1/PLA2-IIA pathway in gingival epithelial surfaces would be an innovative and plausible mechanism by which pathogens such as Pg could specifically enhance oral dysbiosis, inflammation and periodontal disease. To test this hypothesis, we propose three specific aims: (i) To determine the role of PLA2-IIA in Pg-induced oral dysbiosis, inflammation and periodontal disease, (ii) To determine the role of epithelial Notch-1 in Pg-induced PLA2-IIA and periodontitis, and (iii) To identify and validate oral epithelial innate responses modulated by Pg through Notch-1 activation. To address these knowledge gaps, we will use the Pg-induced periodontitis oral gavage model in mouse strains with or without a natural PLA2-IIA mutation, PLA2-IIA-Tg mice with their WT littermates, epithelial-specific N1R deficient mice, as well as OEC cultures to validate the role of this pathway in Pg-induced oral dysbiosis and periodontal disease. These findings will enable a better understanding of the cellular and molecular mechanisms that are specifically modulated by pathogens to alter microbial communities at mucosal surfaces as well as contribute to the evidence for future research designed to determine the role of N1R in oral health and other diseases (e.g., oral cancer).