Bone as a regulator and responder to acute inflammation throughout life

项目摘要--项目#2 我们最近发现成骨细胞来源的Lcn2抑制食欲。同时，Lcn2已知 作为一种急性时相反应蛋白，在细菌感染后，血清中的含量会大大增加。自.以来 Lcn2主要由成骨细胞表达，我们探讨了成骨细胞来源的Lcn2是否是早期感受器 和炎症的调节剂。在人口老龄化的背景下，这种反应特别令人感兴趣 免疫系统反应减弱，炎症更常见。我们的初步数据， 作为小鼠炎症反应的脂多糖(LPS)模型，表明 在炎症刺激后，脑源性信号迅速刺激成骨细胞分泌Lcn2。 发行量。成骨细胞释放Lcn2受谷氨酸的刺激，并受神经调节。这 随着年龄的增长，反应会减弱，并可能导致老年时的炎症易感性。流通中 Lcn2作用于血液和其他组织的关键免疫细胞，并调节它们的表型和随后的 控制内毒素血症、器官损伤和死亡率的功能。根据这些和其他初步数据，我们 假设骨骼是一个急性炎症敏感器官，它装载着拯救生命的抗 成骨细胞分泌Lcn2引起的炎症反应。为了检验这一假设，我们将 确定成骨细胞来源的Lcn2是建立先天免疫反应所必需的，使用年轻人和老年人 成骨细胞特异性Lcn2缺失的成年小鼠和内毒素、细菌感染和脓毒症模型； 失活成骨细胞中特异性的Grik5受体，并检测它是否阻止Lcn2在成骨细胞中的释放 炎症后血清并加重青壮年和老年小鼠的疾病；建立信号转导 由成骨细胞释放Lcn2的信号通路，起源于大脑，在青年时期和老年时期 老鼠。这些研究将定义骨骼作为急性炎症应激源和反应者的新功能，以及 描绘大脑如何通过骨骼和Lcn2来协调快速反应，以调节全身 随着年龄的增长而出现炎症。

Project Summary – Project #2 We have recently shown that osteoblast-derived LCN2 suppresses appetite. At the same time, LCN2 is known as an acute phase response protein that following bacterial infections is highly increased in the serum. Since Lcn2 is primarily expressed by osteoblasts, we explored, whether osteoblast-derived LCN2 is an early sensor and regulator of inflammation. This response is of particular interest within the context of the aging population in which immune system responses are weakened and inflammation more common. Our preliminary data, using as a model of inflammatory response lipopolysaccharides (LPS) administration in mice, indicate that following an inflammatory stimulus, brain-derived signals rapidly stimulate osteoblasts to secrete LCN2 in the circulation. Release of LCN2 from osteoblasts is stimulated by glutamate and is regulated neuronally. This response is compromised with aging and may contribute to inflammation susceptibility with old age. Circulating LCN2 acts on key immune cells of the blood and other tissues and modulates their phenotype and subsequent function to contain endotoxemia, organ damage, and mortality. Based on these and other preliminary data, we hypothesize that bone is an acute inflammation-sensing organ that mounts lifesaving anti- inflammatory responses through LCN2 secretion by osteoblasts. To examine this hypothesis we will establish that osteoblast-derived LCN2 is required for mounting innate immune response using young and old adult mice with osteoblast-specific deletion of Lcn2 and models of LPS and bacterial infection and sepsis; inactivate the Grik5 receptor specifically in osteoblasts and examine whether it prevents LCN2 release in the serum after inflammation and exacerbates disease in young adult and in aging mice; establish the signaling pathway that originates in the brain and signals the release of LCN2 by osteoblasts in young adult and in aging mice. These studies will define a new function of bone as an acute inflammatory stressor and responder and delineate how the brain orchestrates a rapid response through bone and LCN2 to regulate systemic inflammation with aging.