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: 3123443
• 负责人: RODERICK E MCCALLUM
• 金额: $ 15.48万
• 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/3123443
• 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.

传染病是中国人发病和死亡的主要原因。 老年人口。例如，革兰氏阴性败血症可能会超过50% 老年人口。这尤其要归功于医疗水平的提高。 让个人寿命更长的技术，但具有讽刺意味的是， 他们继发感染的风险增加。有大量的 内毒素是革兰氏菌主要毒力决定因素的证据 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者。糖皮质激素 荷尔蒙已被证明调节肿瘤坏死因子的合成以及 影响靶细胞对它的反应。这项提议的重点 将对肿瘤坏死因子-糖皮质激素的年龄差异进行研究 脓毒症中的相互作用。初步研究结果显示， 衰老的C57BL/6NNia小鼠(24个月大)比年轻小鼠死亡早得多 (4-6月龄)或成熟(12月龄)小鼠 盲肠结扎穿刺术(CLP)引起的急性腹膜炎和脓毒症。我们 提示衰老小鼠对脓毒症的敏感性增加和 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要多20到30倍 在给成年小鼠注射大肠杆菌内毒素时，肿瘤坏死因子的作用要比成熟小鼠强。此外， 外源性糖皮质激素通常下调肿瘤坏死因子的产生 在内毒素衰老小鼠中未观察到。我们假设这扰乱了 糖皮质激素对肿瘤坏死因子基因表达的调节可能是 老年动物对败血症的敏感度增加。在拟议的研究中，我们 将确定糖皮质激素在年龄相关差异中的作用 内毒素小鼠产生肿瘤坏死因子。我们将使用糖皮质激素 拮抗剂RU486，用于体内实验，其中 将研究糖皮质激素受体对肿瘤坏死因子产生的阻断作用。 腹膜巨噬细胞将从年轻、成熟和衰老的人身上分离出来 地塞米松对肿瘤坏死因子影响的体外研究 综合。第二个目标是调查糖皮质激素是否发生了变化 在老年动物中，肿瘤坏死因子的产生是在肿瘤坏死因子基因水平上调节的。 我们将开发和利用携带肿瘤坏死因子：猫基因的转基因小鼠 体内糖皮质激素对肿瘤坏死因子基因影响的研究 表情。对于体外研究，各种肿瘤坏死因子：猫基因的构建 将被用来转染原代腹膜巨噬细胞以检测 糖皮质激素、RU486和放线菌素D对肿瘤坏死因子产生的影响我们的 长期目标是了解肿瘤坏死因子-糖皮质激素的相互作用，以便 老年哺乳动物对细菌败血症的敏感性增加可能是 通过更有效的治疗干预减少。