ETHANOL AND OSTEOBLASTOGENESIS: ROLES OF IL-1 AND TNF

描述（由申请人提供）：流行病学数据表明，过量饮酒可能导致美国经济每年在骨骼病理学方面损失20亿美元。酒精性骨病患者骨形成明显受损。酒精可能通过增加细胞因子的分泌间接改变骨代谢，这些细胞因子是绝经后骨质疏松症的关键因素。已经证明，细胞因子通过增加骨吸收和减少骨形成来介导由于雌激素缺乏引起的骨丢失。此外，临床研究表明，细胞因子在酒精诱导的肝病中过量产生。 牵张成骨（DO）是一种延长骨的临床和实验程序，已用于分离和研究慢性乙醇暴露对膜内（直接成骨细胞生成）骨形成的影响，该骨形成组织良好，在空间上与吸收过程不同。 先前的工作表明，大鼠（肠内营养模型）中的慢性乙醇暴露降低胫骨弯曲强度，抑制DO期间的骨形成，并增加肝脏和DO间隙中肿瘤坏死因子α（TNF）的表达。此外，在DO期间用TNF拮抗剂治疗可防止乙醇引起的骨质疏松，而在DO期间用TNF治疗对照大鼠可抑制骨形成。初步结果，结合一种新的小鼠DO模型与液体乙醇输送，表明慢性乙醇暴露降低胫骨强度和抑制骨形成过程中DO。在该鼠模型中，类似于大鼠，在DO期间TNF拮抗剂治疗保护骨形成，外源性TNF抑制骨形成。 本研究的具体目的是确定1）TNF作用的下游介质，2）细胞色素p450 2 E1（CYP 2 E1）的作用和3）活性氧（ROS）在乙醇诱导TNF中的作用。工作假设是乙醇诱导CYP 2 E1增加ROS，诱导TNF，其结合到特定受体并触发抑制骨形成的信号转导途径。 本研究的长期目标是支持未来在以乙醇或细胞因子过量为风险因素的患者的骨科手术中进行药理学和/或营养干预。

DESCRIPTION (provided by applicant): Epidemiological data suggest that excessive alcohol consumption may cost the US economy $2 billion annually in skeletal pathology. Patients with alcoholic bone disease display marked impairment in bone formation. Alcohol may alter bone metabolism indirectly by elevating the secretion of cytokines shown to be critical factors in postmenopausal osteoporosis. It has been demonstrated that cytokines mediate bone loss due to estrogen deficiency by increasing bone resorption and decreasing bone formation. Furthermore, clinical studies show that cytokines are over-produced in alcohol-induced liver disease. Distraction osteogenesis (DO) is a clinical and experimental procedure for lengthening bones that has been used to isolate and study the effects of chronic ethanol exposure on intramembranous (direct osteoblastogenesis) bone formation, which is well organized and spatially distinct from resorptive processes. Previous work demonstrates that chronic ethanol exposure in the rat (enteral nutrition model) decreases tibial bending strength, inhibits bone formation during DO, and increases the expression of Tumor Necrosis Factor alpha (TNF) in the liver and DO gap. Further, treatment with TNF antagonists during DO prevents osteoinhibiton by ethanol, while treatment of control rats with TNF during DO inhibits bone formation. Preliminary results, combining a novel murine DO model with liquid ethanol delivery, demonstrate that chronic ethanol exposure decreases tibial strength and inhibits bone formation during DO. In this murine model, analogous to the rat, TNF antagonist treatment during DO protects bone formation and exogenous TNF inhibits bone formation. The Specific Aims of this project are to determine 1) the downstream mediators of TNF actions, 2) the roles of cytochrome p450 2E1 (CYP2E1) and 3) the role of reactive oxygen species (ROS) in ethanol's induction of TNF. The working hypotheses are that ethanol induction of CYP2E1 increases ROS, inducing TNF, which binds to a specific receptor and triggers signal transduction pathways that inhibit bone formation. The long term goals of this research are to support future pharmacological and/or nutritional interventions in orthopaedic procedures in patients with ethanol or cytokine excess as risk factors.