AGING AND TNF-GLUCOCORTICOID INTERACTIONS IN SEPSIS

脓毒症中的衰老和 TNF-糖皮质激素相互作用

• 批准号: 2052733
• 负责人: RODERICK E MCCALLUM
• 金额: $ 16.53万
• 依托单位: TEXAS A&M UNIVERSITY HEALTH SCIENCE CTR
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-09-30 至 1997-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2052733
• 关键词: aging; dexamethasone; gene expression; genetically modified animals; glucocorticoids; hormone receptor; hormone regulation /control mechanism; inhibitor /antagonist; laboratory mouse; macrophage; physical chemical interaction; tissue /cell culture; transfection; tumor necrosis factor alpha

Infectious diseases are a major cause of morbidity and mortality in the elderly population. For example, Gram negative sepsis may exceed 50% in the aged population. This is due particularly to improved medical technology that allows individuals to live longer, yet ironically, places them at increased risk to secondary infection. There is substantial evidence implicating endotoxin as a major virulence determinant in Gram negative septicemia. Cytokines, particularly tumor necrosis factor, (TNF), appear to be major effectors of endotoxic reactions. Glucocorticoid hormones have been shown to regulate the synthesis of TNF as well as influence the response of target cells to it. The focus of this proposed study will be on age associated differences in TNF-glucocorticoid interaction in sepsis. Results of preliminary studies revealed that senescent C57BL/6NNia mice (24 months old) died much earlier than young (4-6 months old) or mature (12 months old) mice after the induction of acute peritonitis and sepsis by cecal ligation and puncture (CLP). We propose that the increased sensitivity of senescent mice to sepsis and endotoxemia is related to the interaction of glucocorticoid hormones with tumor necrosis factor. Senescent animals produced 20 to 30-fold more serum TNF than mature mice when administered E.coli endotoxin. Furthermore, the usual down-regulation of TNF production by exogenous glucocorticoids was not observed in endotoxic senescent mice. WE HYPOTHESIZE THAT DISRUPTED GLUCOCORTICOID REGULATION OF TNF GENE EXPRESSION MAY UNDERLIE THE INCREASED SENSITIVITY OF AGED ANIMALS TO SEPSIS. In the proposed study we will define the role of glucocorticoids in age associated differences in TNF production by endotoxic mice. We will utilize the glucocorticoid antagonist, RU486, for in vivo experiments in which the effect of glucocorticoid receptor blockade on TNF production will be examined. Peritoneal macrophages will be isolated from young, mature and senescent mice for in vitro studies of the influence of dexamethasone on TNF synthesis. A second Aim is to investigate if altered glucocorticoid regulation of TNF production in aged animals occurs at the TNF gene level. We will develop and utilize transgenic mice carrying a TNF:CAT gene construct to study the influence of glucocorticoids in vivo on TNF gene expression. For in vitro studies, a variety of TNF:CAT gene constructs will be used to transfect primary peritoneal macrophages to examine the effect of glucocorticoids, RU486 and actinomycin D on TNF production. Our long term goal is to understand TNF-glucocorticoid interactions so that the increased sensitivity of aged mammals to bacterial sepsis can be reduced through more effective therapeutic intervention.

传染病是世界上发病和死亡的主要原因， 老年人口。例如，革兰氏阴性脓毒症可能超过50%， 老年人口。这主要是由于医疗条件的改善。 技术，使个人寿命更长，但具有讽刺意味的是，地方， 增加了二次感染的风险。有大量 提示内毒素是革兰氏菌主要毒力决定因子的证据 阴性败血症。细胞因子，特别是肿瘤坏死因子（TNF）， 似乎是内毒素反应的主要效应物。糖皮质 激素已经显示出调节TNF的合成以及 影响靶细胞对它的反应。本文提出的重点是 研究将是关于年龄相关的TNF-糖皮质激素的差异 败血症中的相互作用。 初步研究结果显示， 衰老的C57 BL/6 NNia小鼠（24月龄）比年轻的死亡早得多 (4-6月龄）或成熟（12月龄）小鼠， 盲肠结扎穿孔（CLP）引起的急性腹膜炎和脓毒症。我们 提出衰老小鼠对败血症的敏感性增加， 内毒素血症与糖皮质激素与 肿瘤坏死因子衰老的动物产生的血清是衰老的动物的20到30倍 当给予大肠杆菌内毒素时，TNF比成熟小鼠高。而且 外源性糖皮质激素通常下调TNF的产生， 在内毒素衰老小鼠中未观察到。 我们假设 糖皮质激素对TNF基因表达的调节可能是肿瘤细胞凋亡的基础。 老年动物对脓毒症的敏感性增加。在拟议的研究中，我们 将定义糖皮质激素在年龄相关差异中的作用， 内毒素小鼠的TNF产生。我们会用糖皮质激素 拮抗剂，RU 486，用于体内实验，其中的影响 将检查糖皮质激素受体阻断对TNF产生的影响。 腹腔巨噬细胞将从年轻、成熟和衰老的 用于地塞米松对TNF影响的体外研究的小鼠 合成.第二个目的是研究糖皮质激素的改变是否 老年动物中TNF产生的调节发生在TNF基因水平。 我们将开发和利用携带TNF：CAT基因的转基因小鼠 糖皮质激素对TNF基因影响的体内研究 表情对于体外研究，使用多种TNF：CAT基因构建体， 将被用于检测原发性腹腔巨噬细胞，以检查 糖皮质激素、RU 486和放线菌素D对TNF产生影响。我们 长期目标是了解TNF-糖皮质激素的相互作用， 老年哺乳动物对细菌性脓毒症的敏感性增加， 通过更有效的治疗干预减少。