P. gingivalis Effect on Periodontal Mesenchymal Stem Cell

项目摘要 这项R16拨款申请建议研究牙周细胞凋亡的分子机制。 牙龈卟啉单胞菌诱导间充质干细胞的实验研究牙周炎是一种 牙周微生物群失调引起的炎症性骨吸收损害。危急的病理学 牙周炎的表现是结缔组织和牙槽骨不可逆转的丧失，这在一定程度上是 通过调节成纤维细胞和成骨细胞的细胞死亡。众所周知，牙周成纤维细胞和 成骨细胞是从牙周组织中的间充质干细胞分化而来的。然而，它是 牙周组织中的间充质干细胞是否也会受到调节细胞死亡和减少的影响，目前尚不清楚 再生潜力。因此，这项拟议研究的长期目标是了解分子 黄连素抑制牙周炎结缔组织和牙槽骨再生的机制 针对GMSCs诱导的受调控的细胞死亡，导致治疗性预防的发展 策略。 我们的初步数据表明，Keystone口腔病原体P.gigivalis(PG)，而不是其他牙周组织 细菌可导致牙周MSCs的非典型细胞死亡，但不会导致上皮细胞死亡，其特征是 胞外释放去凝集的染色质内容。新出现的研究表明，只有中性粒细胞 巨噬细胞通过释放去凝集的染色质内容(DNA、组蛋白和HMGB1)而死亡 对刺激的反应 TLR配体。这种现象被称为“中性粒细胞胞外陷阱死亡” 众所周知，“网膜炎”可引起多种疾病的炎症，包括败血症、癌症和自身免疫性疾病。 疾病。我们在这里首次将这种干细胞称为细胞外染色质释放死亡(SECosis)。 根据我们的结果，将THP1细胞(人单核细胞系)暴露于SECosis产品会增加 IL-1β的产生与PG单独或GMSCs单独培养相比，提示其促炎潜能 塞科西斯。已证实，真核生物中的一种肽基精氨酸脱亚氨酶(PAD)在诱导细胞凋亡中起作用。 组蛋白H3瓜氨酸化，使染色质解结。有趣的是，据描述，在 牙周细菌，只有PG才能产生PAD。我们展示了(PAD)敲除PG对GMSCs的刺激作用 THP1IL-1β诱导减弱提示PG-PAD可能参与细胞外的诱导 释放去浓缩的染色质内容物。这一假设将在以下目标中进行评估：(Aim1)到 确定PG的性质，以及PG-Pad在SECosis诱导中的作用。(AIM2)澄清 SECOSIS介导单核细胞产生IL-1β的分子机制这项研究将阐明 PG在GMSCs特异性诱导的细胞死亡调控中的作用，进而抑制其再生潜能 牙周组织。

Project Summary This R16 grant application proposes to investigate the molecular mechanism underlying apoptosis of periodontal mesenchymal stem cells (MSCs) induced by exposure to Porphyromanas gingivalis (Pg). Periodontitis is an inflammatory bone resorption lesion caused by dysbiosis of the periodontal microbiome. A critical pathologic manifestation of periodontitis is the irreversible loss of connective tissue and alveolar bone which, in part, results from the regulated cell death of fibroblasts and osteoblasts. It is well established that periodontal fibroblasts and osteoblasts are differentiated from mesenchymal stem cells (MSCs) present in the periodontium. However, it is largely unknown whether MSCs in periodontal tissue can also be affected by regulated cell death and diminish the regenerative potential. Therefore, the long-term goal of the proposed study is to understand the molecular mechanism underlying the retarded regeneration of connective tissue and alveolar bone in periodontitis by targeting the regulated cell death induced in GMSCs, leading to the development of a therapeutic prevention strategy. Our preliminary data indicate that the keystone oral pathogen P. gingivalis (Pg), but not other periodontal bacteria, can cause atypical cell death of periodontal MSCs, but not epithelial cells, as characterized by the extracellular release of decondensed chromatin contents. Emerging studies have revealed that only neutrophils and macrophages die via the release of decondensed chromatin contents (DNA, Histone and HMGB1) in response to stimulation with TLR ligands. This phenomenon termed as “Neutrophil Extracellular Trap Death [=osis] (NETosis)” is known to elicit inflammation in several diseases, including sepsis, cancer, and autoimmune diseases. We herein for the first time termed such Stem cell Extracellular Chromatin release Death (SECosis). According to our results, exposure of THP1 cells (human monocytic cell line) to SECosis products elevated the production of IL-1β compared to that of Pg alone or GMSCs alone, suggesting the proinflammatory potential of SECosis. It is established that a eukaryote enzyme peptidyl arginine deiminase (PAD) plays a role in eliciting the NETosis by Histone H3 citrullination that untangles the chromatin. Interestingly is described that among the periodontal bacteria, only Pg produces PAD. We showed Stimulation of GMSCs with (PAD)-knockout Pg diminished induction of IL-1β from THP1 indicating that Pg-PAD may be engaged in the induction of extracellular release of decondensed chromatin contents. This hypothesis will be assessed in the following Aims: (Aim1) To establish the property of Pg, and the role of Pg-PAD, in the induction of SECosis. (Aim2) To elucidate the molecular mechanism underlying the SECosis-mediated IL-1β production by monocytes. This study will elucidate role of Pg in the regulated cell death specifically induced in GMSCs, in turn retarding the regenerative potential of periodontal tissue.