P. gingivalis Effect on Periodontal Mesenchymal Stem Cell

项目摘要 这项R16资助申请旨在研究牙周组织细胞凋亡的分子机制。 间充质干细胞（MSC）暴露于牙龈卟啉单胞菌（Pg）诱导。牙周炎是一种 由牙周微生物组的生态失调引起的炎性骨吸收损伤。严重的病理性 牙周炎的表现是结缔组织和牙槽骨的不可逆损失，这部分地导致 从成纤维细胞和成骨细胞的调节性细胞死亡中。已经确定牙周成纤维细胞和 成骨细胞由存在于牙周组织中的间充质干细胞（MSC）分化而来。但据 很大程度上不清楚牙周组织中的MSC是否也可以受到调节性细胞死亡的影响， 再生潜力。因此，拟议研究的长期目标是了解分子 牙周炎中结缔组织和牙槽骨再生迟缓的机制 靶向GMSC中诱导的调节性细胞死亡，导致开发治疗性预防 战略 我们的初步数据表明，关键的口腔病原体牙龈卟啉单胞菌（Pg），而不是其他牙周 细菌，可引起牙周MSC的非典型细胞死亡，但不是上皮细胞，其特征在于， 细胞外释放去致密的染色质内容物。新的研究表明，只有中性粒细胞 巨噬细胞通过释放去致密的染色质内容物（DNA，组蛋白和HMGB 1）死亡， 响应于采用 TLR配体。这种现象被称为“神经细胞外陷阱死亡 已知“NETosis”会引起多种疾病的炎症，包括败血症、癌症和自身免疫性疾病。 疾病我们在此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，THP 1细胞（人单核细胞系）暴露于SECosis产品可提高THP 1细胞（人单核细胞系）的增殖。 与单独的Pg或单独的GMSC相比，IL-1β的产生，表明Pg的促炎潜力。 SECosis。已经确定，真核生物酶肽基精氨酸脱亚胺酶（PAD）在引发细胞凋亡中起作用。 通过组蛋白H3瓜氨酸酶解缠结染色质。有趣的是，据描述， 牙周细菌，只有Pg产生PAD。我们显示用（PAD）敲除的Pg刺激GMSC， 减少THP 1诱导IL-1β，表明Pg-PAD可能参与诱导细胞外 释放去致密的染色质内容物。将在以下目标中评估这一假设：（目标1） 明确Pg的性质及Pg-PAD在SECosis诱导中的作用。（目的2）阐明 SECosis介导的单核细胞产生IL-1β的分子机制。这项研究将阐明 Pg在GMSC中特异性诱导的调节性细胞死亡中的作用，反过来阻碍再生潜力 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.