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

在特定病原细菌存在的情况下，粘膜对微生物区系的反应机制 物种(例如牙龈假单胞菌-PG)可以消除导致生物失调的宿主-微生物共生关系，并 炎症性疾病仍然没有完全被了解。我们开创性的R21研究表明，PG诱导 磷脂酶A2组IIA(PLA2-IIA)，其机制涉及Notch-1受体(N1R)的激活 PG牙龈痛，调节口腔上皮细胞(OECs)的抗微生物特性。这与中的一致 体内和临床证据支持PLA2-IIA的有效抗菌作用(ng/mL)。值得注意的，口头的 细菌对PLA2-IIA具有不同的抗菌活性。此外，牙周组织中的PLA2-IIA 在牙周病的发生和发展过程中，N1R的表达和活性都升高，这是 在非人类灵长类动物中并发口腔生物失调。与这些观察结果一致，新的初步报告 使用小鼠模型的研究显示，牙周组织中PLA2-IIA的表达和N1R的激活在早期就增加了 PG感染。值得注意的是，过表达PLA2-IIA(PLA2-IIA-TG)的转基因小鼠的口腔微生物群 细菌种类的丰度有显著差异(菌落数减少，菌落数增加 变形杆菌)与它们的野生型共笼窝产仔进行比较。PLA2-IIA-TG小鼠的口腔微生物失调 与牙龈细胞内感应相关基因(NOD2)表达的变化有关，经典 抗菌因子(S100A8/S100A9、hBD1)和M1/M2巨噬细胞趋化因子。N1R是一种关键的调节器 因此，PG在嗅鞘细胞中激活N1R的能力是一种令人兴奋的创新 观察。初步数据表明，OEC的其他功能/反应(细菌感知、细胞凋亡和 自噬)可能涉及PG诱导的N1R激活。根据这一证据，我们假设 牙龈上皮细胞表面的Noch-1/PLA2-IIA通路可能是一种创新和合理的机制，通过 哪些病原体，如PG，可以特异性地增强口腔生物失调、炎症和牙周病。至 为了验证这一假说，我们提出了三个具体的目标：(I)确定PLA2-IIA在PG诱导的 口腔生物失调、炎症和牙周病，(II)确定上皮细胞的作用 在PG诱导的PLA2-IIA和牙周炎中的Noch-1，以及(Iii)鉴定和验证口腔 PG通过Notch-1激活调节上皮固有反应。要解决这些问题 知识空白，我们将使用PG诱导的小鼠牙周炎口腔灌胃模型，无论有没有 自然的PLA2-IIA突变，PLA2-IIA-TG小鼠及其WT后代，上皮特异性N1R缺陷小鼠， 以及嗅鞘细胞培养，以验证这一途径在PG诱导的口腔生物失调和牙周病中的作用。 这些发现将使人们能够更好地理解特定的细胞和分子机制 受病原体调节，改变粘膜表面的微生物群落，并有助于证据 用于未来旨在确定N1R在口腔健康和其他疾病(如口腔癌症)中的作用的研究。

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).