Mechanisms of Cell Death and Inflammation in Chemotherapy-Induced Oral Mucositis

项目摘要 口腔粘膜炎是癌症化疗最常见的并发症之一。由于其症状和 口腔粘膜炎可能会影响最佳癌症治疗的实施。口腔粘膜炎 主要是由于化疗药物对快速分裂的口腔上皮细胞的细胞毒性作用。然而，在这方面， 涉及粘膜损伤的特定细胞事件仍然不完全清楚，从而阻碍了对粘膜损伤的研究。 开发有效的治疗方法。细胞死亡和炎症是粘膜炎的标志。虽然DNA 损伤和细胞凋亡被认为是导致口腔粘膜炎的主要机制， 细胞死亡触发宿主衍生的损伤相关分子模式（DAMPS）的释放和激活 也可能涉及由常驻微生物引起的炎症反应。初步意见 在5-FU诱导口腔粘膜炎小鼠模型中，基底上皮细胞凋亡是早期反应， 但非凋亡形式的细胞死亡可能介导晚期组织损伤。因此，有必要评估 化疗诱导的口服给药期间细胞死亡途径和介质激活的时间进程 粘膜炎。在这里，我们将探讨这一假设，即凋亡介导的早期反应，而非凋亡 细胞死亡的形式和通过DAMP或生态失调微生物组的感测而激活的炎症有助于 晚期组织损伤我们将特别关注评估促凋亡介质PMAIP 1的作用， 发现其在化疗期间在人口腔粘膜中上调。我们还将测试信号是否 通过肿瘤坏死因子（TNF）-α和/或Toll样受体4（TLR 4）导致口腔黏膜损伤。水平 TNF-α在口腔粘膜炎期间增加，并与其严重程度相关。TLR 4，其传感DAMP， 在口腔粘膜中表达，并已显示介导下胃肠道粘膜炎，但其在口腔粘膜中的作用 口腔粘膜炎尚未评估。此外，口腔粘膜炎与微生物群生态失调有关， 致病菌的富集，这可能有助于在TLR依赖性或非依赖性免疫反应中放大组织损伤。 方式因此，在本建议中，我们将使用5-FU诱导的口腔粘膜炎小鼠模型来鉴定 组织损伤介质。在目标1中，我们将纵向表征导致细胞死亡的途径， 在5-FU诱导粘膜炎过程中的炎症损伤，并通过敲除菌株进行机械评价， 药理学抑制剂PMAIP 1、TNF-α和TLR 4作为病理生理学介质的贡献。在 目的2：我们将描述5-FU治疗期间口腔微生物组和微生物组织侵袭的生态失调变化。 诱发口腔粘膜炎。然后，我们将测试抗生素方案的效果，显示选择性或完全耗尽 口腔粘膜炎的过程中，并将评估是否转移的微生态群落调节 口腔粘膜炎严重程度。我们设想这些研究将指出关键的组织损伤介质和上皮微生物 调节粘膜炎病理生理学的相互作用，并将指导治疗的发展。

Project summary Oral mucositis is one of the most common comorbidities of cancer chemotherapy. Due to its symptoms and associated complications, oral mucositis can impact the delivery of optimal cancer treatment. Oral mucositis primarily results from the cytotoxic effect of chemotherapeutics on the rapidly dividing oral epithelium. However, the specific cellular events involved in mucosal injury remain incompletely understood, thereby hampering the development of effective treatments. Cell death and inflammation are hallmarks of mucositis. Although DNA damage and apoptosis have been considered the main mechanisms that lead to oral mucositis, lytic forms of cell death triggering the release of host-derived damage-associated molecular patterns (DAMPS) and activation of inflammatory responses by resident microbial commensals could also be involved. Preliminary observations in a mouse model of 5-FU-induced oral mucositis suggest apoptosis of basal epithelial cells is an early response, but non-apoptotic forms of cell death are likely to mediate late tissue injury. There is therefore a need to evaluate the temporal progression of cell death pathways and mediators activated during chemotherapy-induced oral mucositis. Here we will explore the hypothesis that apoptosis mediates early responses, while non-apoptotic forms of cell death and activation of inflammation by sensing of DAMPs or a dysbiotic microbiome contribute to late stages of tissue injury. We will specifically focus on evaluating the role of the pro-apoptotic mediator PMAIP1, which was found as upregulated in human oral mucosa during chemotherapy. We will also test if signaling through tumor necrosis factor (TNF)-α and/or Toll-like receptor 4 (TLR4) leads to oral mucosal injury. Levels of TNF-α increase during oral mucositis and are associated with its severity. TLR4, which senses DAMPs, is expressed in the oral mucosa and has been shown to mediate lower gastrointestinal mucositis, but its role in oral mucositis has not been evaluated. Furthermore, oral mucositis is associated with microbiome dysbiosis, with an enrichment of pathobionts, which could contribute to amplify tissue injury in a TLR-dependent or independent manner. Accordingly, in this proposal we will use our mouse model of 5-FU-induced oral mucositis to identify mediators of tissue injury. In Aim 1, we will longitudinally characterize pathways leading to cell death and inflammatory damage during 5-FU-induced mucositis and mechanistically evaluate via knockout strains and pharmacological inhibitors the contribution of PMAIP1, TNF-α and TLR4 as mediators of pathophysiology. In Aim 2 we will characterize dysbiotic changes in the oral microbiome and microbial tissue invasion during 5-FU- induced oral mucositis. We will then test the effect of antibiotic regimens, shown to selectively or totally deplete oral commensals, on the course of mucositis and will evaluate if transfer of a dysbiotic community modulates oral mucositis severity. We envision these studies will point to key tissue injury mediators and epithelial-microbe interactions that modulate mucositis pathophysiology and will guide the development of therapies.