Treatment of Periodontitis by Homing M2 Macrophages

牙周炎(PD)是第二种最常见的口腔疾病，在美国约有一半的成年人(6500万)受到影响 美国。牙周炎导致牙齿脱落，并已牵涉到几个严重的发病机制 系统性疾病，包括糖尿病、心血管疾病和早产。牙周炎是一种慢性疾病。 炎症性疾病，由牙菌斑和牙石中的细菌感染引发；但实际疾病 症状是由宿主对这些病原体的免疫反应引起的。目前的标准治疗是 清除斑块和结石以减少细菌负荷；然而，目前还没有治疗方法 帕金森病的免疫成分。因此，许多研究小组已经开始开发技术来规范 增强免疫反应，减少炎症。我们集团一直专注于招募和两极分化M2 巨噬细胞作为牙周炎治疗的新途径。在我们之前的研究中，我们成功地阻止了 局部诱导M2巨噬细胞在小鼠牙周炎模型中的牙槽骨丢失。M2巨噬细胞 牙周注射C-C基序趋化因子2(CCL2)释放PLGA微粒(MPS)引起的极化 纸巾。结果表明，通过局部递送CCL2诱导M2巨噬细胞确实减少 牙周炎的炎症和骨丢失。拟议的研究将进一步探索阿司匹林的治疗潜力。 CCL2对M2巨噬细胞的诱导，并阐明了这一过程的机制。我们 假设CCL2在维持牙周免疫动态平衡中起关键作用，并且它的外源性 传递，或基因消融，将通过牙周破裂，修复和修复改变帕金森病的过程 微生物区系失调。巨噬细胞在肿瘤的破坏性和建设性阶段都发挥着重要的作用。 通过调节它们极化成M1(促炎症/促破坏)的能力来进行炎症反应 或M2(抗炎/修复)巨噬细胞。我们的假设得到了我们最近研究的有力支持 体内数据显示，局部递送CCL2将诱导巨噬细胞和单核细胞分化为 M2表型，从而减少牙周炎性骨丢失和牙周起始 修理。为了验证这一假设，我们提出了以下具体目标：1)将CCL2 MPS作为一种干预性测试 和修复性牙周治疗；2)研究牙周表型、牙周破裂和修复 CCL2基因敲除小鼠(CCL2-KO)；3)进行单细胞RNA测序(ScRNA-Seq)，以获得in- CCL2的作用、与其他免疫的关联、影响和相互作用的深度机制数据 细胞。我们预计，从PLGA MPS中释放的CCL2将抑制进一步的骨丢失，促进骨修复 小鼠牙周炎模型。我们还预计CCL2-KO小鼠和ScRNA-Seq分析将提供关键数据 为了解CCL2的S免疫调节作用的潜在机制。总而言之，我们认为M2 CCL2诱导炎症牙周组织中的巨噬细胞可能是治疗PD的一种新的、有前途的策略。

Periodontitis (PD) is the second most common oral disease, affecting about half of adults (65 millions) in the United States. Periodontitis causes tooth loss and has been implicated in the pathogenesis of several serious systemic diseases including diabetes, cardiovascular diseases, and premature birth. Periodontitis is a chronic inflammatory disease, triggered by bacterial infection present in dental plaques and calculus; but actual disease manifestations are caused by host immune response to these pathogens. Current standard treatment is debridement of plaques and calculus to reduce the bacterial load; however, there are no therapies that address the immune component of PD. Thus, many research groups have started developing technologies to regulate the immune response and reduce inflammation. Our group has focused on recruiting and polarizing M2 macrophage as novel approaches for therapy of periodontitis. In our previous study, we successfully prevented alveolar bone loss by locally inducing M2 macrophages in mouse periodontitis models. M2 macrophages were polarized by injecting C-C motif chemokine 2 (CCL2) releasing PLGA microparticles (MPs) into periodontal tissues. The results indicated that inducing M2 macrophages by local delivery of CCL2 indeed reduces inflammation and bone loss in periodontitis. The proposed study will explore further the therapeutic potential of M2 macrophage induction by CCL2 as well as shed light on the mechanism underlying this process. We hypothesize that CCL2 plays a key role in maintaining periodontal immune homeostasis, and that its exogenous delivery, or genetic ablation, would modify the course of PD through periodontal breakdown, repair and microbiota dysbiosis. Macrophages play an important role in both the destructive and constructive phases of the inflammatory response by modulating their ability to polarize into either M1 (pro-inflammatory/pro-destructive) or M2 (anti-inflammatory/pro-reparative) macrophages. Our hypothesis is strongly supported by our recent in vivo data showing that the local delivery of CCL2 will induce differentiation of macrophages and monocytes to an M2 phenotype, thus leading to decreased periodontal inflammatory bone loss and initiation of periodontal repair. To test this hypothesis, we propose the following specific aims: 1) To test CCL2 MPs as an interventional and reparative periodontal therapy; 2) To study the periodontal phenotype, periodontal breakdown and repair in CCL2-knockout mice (CCL2-KO); and 3) To perform Single cell RNA sequencing (ScRNA-Seq) to acquire in- depth mechanistic data about the role of CCL2, its association, effect on and interactions with other immune cells. We anticipate that CCL2 released from PLGA MPs will inhibit further bone loss and promote repair in the mouse periodontitis model. We also expect that CCL2-KO mice and ScRNA-Seq analysis will provide data critical to understanding underlying mechanisms of CCL2’s immunoregulatory effects. In sum, we believe that M2 macrophage induction by CCL2 in inflamed periodontium could be a novel, promising strategy for treating PD.