Oral Mucosa Barrier and Bisphosphonate-related Osteonecrosis of the Jaw

描述（由申请人提供）：双膦酸盐（BP）治疗已被证明可有效治疗骨内或骨转移的恶性肿瘤，分别包括多发性骨髓瘤和乳腺癌或前列腺癌。近年来，有许多病例报告了含氮BP治疗后的颌骨骨坏死（ONJ）。本项目的长期目标是确定BP相关ONJ的病理机制，并开发有效的预防和治疗手段。 ONJ几乎完全发生在口腔中，其中颌骨和口腔粘膜紧密接触。口腔粘膜具有独特的适应性免疫和先天性免疫。虽然口腔粘膜提供了最有效的屏障功能之一，但炎症/免疫反应的过度激活与口腔中的各种组织损伤有关。因此，我们推测BP治疗可能会异常激活口腔屏障组织的粘膜免疫，从而产生导致骨坏死的细胞毒性环境。屏障组织含有一组由T细胞、NK细胞、NKT细胞和/或Th 17细胞组成的淋巴细胞。活化的屏障组织淋巴细胞可以调节上皮完整性并协调炎症反应。在SA 1中，我们建议确定 参与ONJ病理机制的候选免疫效应细胞。最近，PI的团队开发了一种ONJ小鼠模型，该模型表现出一致的坏死颌骨，相当于人类疾病。本课题将ONJ小鼠模型与B/T细胞敲除（RAG 1-/-）小鼠以及B/T/NK细胞敲除（RAG 2/？(c)-/-）小鼠，其中将表征ONJ表型。在屏障组织淋巴细胞中，？T细胞是对应激诱导信号的第一反应。在这个项目中，我们分别研究的作用，口头？T细胞在ONJ病变的发展中使用？T细胞敲除（TCRD-/-）小鼠。 一个重要的问题仍然存在：BP治疗和口腔屏障免疫激活之间的独特联系是什么？通过骨吸收，BP被破骨细胞（OC）内化，并干扰甲羟戊酸途径，导致OC过早失活。啮齿动物ONJ病变的早期发作表现出一种不寻常的炎症细胞簇，与BP困扰的OC并列。这一观察结果使我们假设，BP困扰的OC是激活口腔屏障免疫效应细胞的应激信号的细胞来源，从而启动ONJ发病机制。在SA 2中，我们建议建立涉及BP吸收的CaP盘和人单核细胞衍生的OC的体外模型。将通过共培养系统差异评价BP-降解的OC对人口腔淋巴细胞或外周血淋巴细胞的影响。 本课题的研究结果为口腔黏膜屏障免疫效应细胞的研究开辟了新的途径，为口腔黏膜炎的治疗提供了依据。

DESCRIPTION (provided by applicant): Bisphosphonate (BP) treatment has been shown to be effective in the management of malignant neoplasms that reside in or metastasize to bone, including multiple myeloma and breast or prostate cancer, respectively. In the recent years, there have been a number of cases reporting osteonecrosis of the jaw (ONJ) subsequent to nitrogen-containing BP treatment. The long-term objective of this project is to determine the pathological mechanism of BP associated-ONJ and to develop effective means for prevention and treatment. ONJ occurs nearly exclusively in the oral cavity, where jawbone and oral mucosa interface at a close proximity. Oral mucosa is equipped with the unique subset of adaptive and innate immunity. While oral mucosa provides one of the most effective barrier functions, over-activation of inflammatory/immune reactions has been linked to various tissue damages in the oral cavity. Therefore, we postulate that BP treatment may abnormally activate the mucosal immunity of oral barrier tissue resulting in generating a cytotoxic environment leading to osteonecrosis. The barrier tissues contain a set of lymphocytes composed of ¿¿ T cells, NK cells, NKT cells and/or Th17 cells. Activated barrier tissue lymphocytes can regulate the epithelial integrity and orchestrate inflammatory reactions. In SA1, we propose to identify the candidate immune effector cells involved in the pathological mechanism of ONJ. Recently, PI's team developed a mouse model of ONJ, which exhibited consistent necrotic jawbones, equivalent to the human disease. In this project, the mouse ONJ model will be combined with B/T cell knockout (RAG1-/-) mice as well as B/T/NK cell knockout (RAG2/?(c)-/-) mice, in which the ONJ phenotype will be characterized. Among the barrier tissue lymphocytes, ?¿ T cells present the first respondent to stress-induced signals. In this project, we separately examine the role of oral ?¿ T cells in the development of ONJ lesions using ?¿ T cell-knockout (TCRD-/-) mice. An important question still remains: what is the unique link between BP treatment and the activation of oral barrier immunity? Through bone resorption, BP is internalized by osteoclasts (OCs) and interferes the mevalonate pathway leading to premature inactivation of OCs. The early onset of rodent ONJ lesions demonstrated an unusual cluster of inflammatory cells juxtaposing BP-distressed OCs. This observation has led us to hypothesize that BP-distressed OCs are the cellular source of stress signals activating oral barrier immune effector cells and thus initiating ONJ pathogenesis. In SA2, we propose to establish an in vitro model involving BP-absorbed CaP disc and human monocyte-derived OCs. The effect of BP-distressed OCs on human oral lymphocytes or peripheral blood lymphocytes will be differentially evaluated by co-culture system. The outcome of this project may open a new avenue of investigations on oral mucosa barrier immune effector cells and previously unexplored stress signaling mechanisms of the pharmacologically manipulated OCs and provide the basis for therapeutic strategy of ONJ.