Role of Complement in Commensal Microbiota Actions Regulating Sketal Maturation

摘要 共生微生物区系对调节青春期后骨骼的骨免疫过程起关键作用 发展。我们的研究表明，共生肠道微生物区系抑制成骨细胞骨- 形成细胞并增强破骨细胞的骨吸收能力，这会损害骨量的积累。然而， 在整个生命周期中，识别共生微生物群对骨骼影响的机制尚不清楚。 骨免疫学研究表明，骨髓中的免疫细胞调节骨骼 造型/改建。尽管知道共生肠道微生物区系会引导与宿主的串扰 免疫，免疫机制研究阐明了共生肠道微生物区系的免疫调节作用 骨骼成熟度尚不清楚。研究人员博士后研究工作的初步发现表明 共生微生物群-宿主相互作用刺激补体信号对系统分解代谢产生影响 健康和疾病中成熟的骨骼。 补体信号保护宿主免受感染并调节免疫反应，强调 补体在维持与共生微生物区系的动态平衡关系中的作用。我们的 初步数据表明，共生微生物区系上调循环补体 过敏毒素C3a，它也与炎症性肠病的发病机制有关。补体受体 C3aR在成骨细胞和破骨细胞上都有表达，这意味着C3a可能是一种关键的调节因子。 健康和疾病对成熟骨骼的共生微生物区系效应。将解决三个具体目标 利用在成骨细胞和破骨细胞中同时缺失C3aR的转基因小鼠进行关键的体内和体外研究 健康和葡聚糖硫酸钠(DSS)诱导的结肠炎。这三个目标将调查总体 C3a的共生肠道微生物区系上调调节C3aR源性骨骼成熟的假说 在一生中的健康和疾病方面。目标1将阐明共生肠道微生物区系在 C3aR介导的成骨细胞在正常和炎症条件下骨骼成熟和恶化中的作用 大便情况。目的2将研究共生肠道微生物区系对C3aR-破骨细胞生成信号的作用 健康和疾病中成熟和老化的骨骼。目标3将确定益生菌给药是否 在青春期后骨骼发育过程中调节C3a/C3aR信号。阐明两者之间的关系 C3/C3aR信号、肠道微生物区系和骨骼将为治疗干预提供机会 优化年轻服役人员的骨量积累，防止骨骼老化 退伍军人。 这项研究试图定义调节峰值骨量增加的骨免疫学过程 耐受年龄相关和/或疾病相关的骨骼退化。这些研究将创新性地使用 骨细胞特异性C3aR基因敲除模型研究微生物区系衍生的补体信号转导效应 骨骼成熟。值得注意的是，这项工作建议在骨量增加高峰期进行益生菌干预。 为了确定共生微生物区系对补体C3a/C3aR在整个骨骼中的作用 寿命。此外，这项提议将在新的专门知识和职业领域提供扎实的职业发展 申请人过渡到独立退伍军人管理局调查员所需的工具。这将会实现的 通过CDA提供的建议课程作业、实践培训、网络和指导经验- 2机制。

Abstract Commensal microbiota critically regulates osteoimmune processes mediating post-pubertal skeletal development. Our studies have shown that the commensal gut microbiota suppresses osteoblastic bone- forming cells and enhances osteoclastic bone-resorbing cells, which impairs bone mass accrual. However, mechanisms discerning commensal microbiota effects on bone across the lifespan are unclear. The study of osteoimmunology has shown that immune cells in the bone marrow regulate bone modeling/remodeling. Despite knowledge that the commensal gut microbiota directs crosstalk with host immunity, immune mechanistic studies elucidating the commensal gut microbiota immunomodulatory effects on skeletal maturation are unclear. Preliminary findings from the investigator’s postdoctoral research work suggest that commensal microbiota-host interactions stimulate complement signaling to have system catabolic effects in the maturing skeleton in health and disease. Complement signaling protects the host from infection and modulates the immune response, highlighting the role of complement in maintaining a homeostatic relationship with the commensal microbiota. Our preliminary data demonstrated that the commensal microbiota upregulates circulating complement anaphylatoxin C3a, which has also been implicated in inflammatory bowel pathogenesis. Complement receptor C3aR is expressed on both osteoblasts and osteoclasts, implying that C3a may be a critical regulator of commensal microbiota effects on the maturing skeleton in health and disease. Three specific aims will address critical in vivo and in vitro studies utilizing transgenic mice deleting C3aR in both osteoblasts and osteoclasts in health and under dextran sodium sulfate (DSS)-induced colitis. These three aims will investigate the overall hypothesis that the commensal gut microbiota upregulation of C3a regulates C3aR derived skeletal maturation in health and disease throughout the lifespan. Aim 1 will elucidate the role of commensal gut microbiota on C3aR-mediated osteoblastogenesis in skeletal maturation and deterioration under normal and inflammatory bowel conditions. Aim 2 will examine commensal gut microbiota actions on C3aR-osteoclastogenic signaling in the maturing and aging skeleton in health and disease. Aim 3 will determine whether probiotic administration regulates C3a/C3aR signaling during post-pubertal skeletal development. Elucidating the relationship between C3/C3aR signaling, the gut microbiota, and bone will provide opportunities for therapeutic interventions to optimize bone mass accrual in young service members and protect against skeletal deterioration in aging Veterans. This research seeks to define osteoimmunological processes regulating peak bone mass accrual to withstand either age-related and/or disease-related skeletal deterioration. These studies will innovatively use bone cells specific C3aR knockdown models to determine microbiota derived complement signaling effects on skeletal maturation. Notably, this work proposes probiotic interventions during a peak bone mass accrual window to define the role of the commensal microbiota on complement C3a/C3aR on the skeleton throughout the lifespan. Additionally, this proposal will provide solid career development in new areas of expertise and career tools necessary for the applicant's transition to an independent VA investigator. This will be accomplished through proposed coursework, hands-on training, networking, and mentoring experiences provided by the CDA- 2 mechanism.