A Refined Murine Model of Post-sepsis Cognitive Impairment for Investigating Mitochondrial Abnormalities and Human ApoE4 Gene Polymorphisms

摘要 脓毒症是一种由感染引发的危及生命的内科疾病，伴有严重的全身 发炎。现在，每年有170多万败血症幸存者出院，其中大部分 他们中的一些人报告说，由于相当长的长期功能障碍，称为慢性危重疾病，生活质量下降， 包括出院后的肌肉无力和认知障碍。我们之前开发了一种 临床相关的小鼠败血症-幸存者模型和类似ICU的复苏程序，使我们能够 评估脓毒症康复后的长期肌肉质量和功能。我们的研究表明 败血症-存活的小鼠表现出明显的骨骼肌无力。这些败血症幸存者的骨骼肌 小鼠也表现出严重的线粒体结构和功能缺陷。与肌肉功能障碍相反， 败血症幸存者的认知功能障碍知之甚少。尽管有几项已发表的研究使用 关于这个问题的实验动物模型，由于几个限制，他们的结果仍然没有定论；1)认知 应激性游泳迷宫试验评估损伤，脓毒症幸存者表现不佳 肌肉无力；2)外科脓毒症模型的使用，假性坏死和导致的全身 炎症；以及3)缺乏抗生素治疗和未确认败血症已痊愈，从而 专注于“败血症期间”而不是“败血症后”的功能障碍，都限制了当前的研究。重要的是，所有 这些限制在我们的上述脓毒症-幸存者小鼠模型中得到了解决，该模型证实了 从脓毒症中恢复，允许在脓毒症后有足够的时间(4周或更长)来研究长期影响，以及 无需外科手术以避免假性坏死和炎症。因此，我们精制的败血症- 存活的小鼠肌肉无力模型有可能成为研究后肌肉无力的合适动物模型。 脓毒症是一种长期的认知损害。我们的主要假设是，这种脓毒症-幸存者模型将表现出长期的- 术语认知障碍。我们还假设，ApoE4基因多态性，最常见的AD- 易感基因携带者在脓毒症中存活后发生认知功能障碍的风险更高。 此外，我们假设线粒体异常与败血症后的认知功能有关。 减损。为了检验这些假设，我们将追求两个具体目标。(1)检测野生型 小鼠在脓毒症后出现长期的认知障碍；以及(2)测试突变小鼠 携带人类载脂蛋白E4基因多态的人患认知障碍的风险更高 脓毒症后。

ABSTRACT Sepsis is an infection-initiated life-threatening medical condition accompanied by severe whole-body inflammation. Over 1.7 million sepsis survivors are now discharged from the hospital annually, and a majority of them report reduced quality of life due to considerable long-term dysfunction, called chronic critical illness, including muscle weakness and cognitive impairment after hospital discharge. We previously developed a clinically relevant murine sepsis-survivor model with an ICU-like resuscitation procedure that enables us to evaluate long-term muscle quality and function after recovery from sepsis. Our studies demonstrated that sepsis-survivor mice exhibit significant skeletal muscle weakness. Skeletal muscles from these sepsis-survivor mice also show profound mitochondrial structural and functional defects. In contrast to muscle dysfunction, little is known for cognitive dysfunction in sepsis survivors. Although there are several published studies using laboratory animal models for this issue, their results remain inconclusive due to several limitations; 1) cognitive impairment being assessed by stressful swimming maze tests which sepsis survivors perform poorly due to muscle weakness; 2) use of surgical sepsis models with artifactual necrosis and resulting systemic inflammation; and 3) the lack of antibiotics treatment and the lack of confirmation of sepsis recovery, thereby focusing on dysfunction “during sepsis” rather than “post-sepsis”, all limit current research. Importantly, all these limitations are resolved in our above-mentioned sepsis-survivor mouse model that confirms complete recovery from sepsis, allows sufficient duration (4 weeks or longer) after sepsis to study long term effects, and eliminates surgical procedures to avoid artifactual necrosis and inflammation. Thus, our well-refined sepsis- survivor mouse model for muscle weakness can potentially be an appropriate animal model to investigate post- sepsis long-term cognitive impairment. Our major hypothesis is that this sepsis-survivor model will exhibit long- term cognitive impairment. We also hypothesize that ApoE4 gene polymorphism, the most common AD- susceptible genotype, confers a higher risk of developing cognitive dysfunction after surviving sepsis. Additionally, we hypothesize that mitochondrial abnormalities are involved in such post-sepsis cognitive impairment. To test these hypotheses, two Specific Aims will be pursued. (1) To test whether wild type mice develop long-term cognitive impairment after sepsis; and (2) To test whether mutant mice carrying the human ApoE4 gene polymorphism have a higher risk of developing cognitive impairment after sepsis.