抗内毒素药物的研究进展

临床常见的革兰氏阴性菌所致的疾病如感染性休克、败血症、多器官功能性衰竭等都与内毒素密切盯关。抗内毒素药物能够直接中和及清除内毒素,无论在体外去除污染的内毒素,还是用于内毒素介导的疾病的治疗,均具有实用价值。本文综述了近年来抗内毒素药物多粘菌素B九肽、类脂A结构拮抗及内源性多肽类的研究进展,并展望了抗内毒素药的发展前景。     

抗菌药物诱导内毒素的产生及抗内毒素药物的研究进展

内毒素是革兰阴性菌的主要致病成分,抗菌药物在杀/抑菌的同时会诱导内毒素的产生,增加了疾病的治疗难度。体外实验、动物实验证实,抗菌药物诱导内毒素的产生与多种因素有关,提示在临床选用抗菌药物时应对药敏实验结果及其诱导内毒素释放的特性进行综合考虑。抗内毒素药物的研究近年取得了一些成效,其中中药制剂也显示了很好的抗内毒素作用,相信这类药物会有广阔的发展前景。     

细菌内毒素与抗内毒素治疗

综述了有关细菌内毒素的分子结构及其特征、识别机制、生物学效应及抗内毒素治疗的研究进展     

板蓝根抗内毒素研究

目的：探讨板蓝根抗细菌内毒素作用,方法：分别用细菌内毒素检查法,热原检查法,对内毒素致小鼠毒性保护力,对内毒素致鼠巨噬细胞释放炎性因子抑制作用及内毒素定量检测等方法,比较板蓝根不同提取部位化学成分及药材抗内毒素强度,结果：板蓝根氯仿提取的中的F022抗内毒素作用最强,其中F02207可作为板蓝抗内毒素药物的活性指标成分,结论：F022是板蓝根抗内毒素新药研究的物质基础。     

抗菌药物诱导内毒素释放及抗内毒素药物研究进展

不同种类抗菌药物诱导内毒素释放情形不同。主要作用于青霉素结合蛋白(PBP)的抗菌药物有β 内酰胺类，可杀灭菌体而释放大量内毒素(LPS)，而非作用于PBP的抗菌药物有氨基苷类、喹诺酮类、大环内酯类，使细菌释放内毒素较少。在保证有效杀菌的前提下，选择致内毒素释放较少的抗菌药物，并合用抗内毒素药物对减轻机体损伤及预防多脏器功能衰竭的发生可能有益。     

人参抗内毒素作用研究

内毒素有很强的细胞毒作用，引起发热，白细胞骤降及内毒素血症等，最终可内毒素休克死亡。本研究以内毒素致鲎试剂凝固法和家兔升温法检测了人参提取液对内毒素结构的直接破坏作用，通过兔和小白鼠检测了人参抗内毒素致热，抗白细胞骤降和抗体休克死亡作用。结果表明，人参提取液对内毒素结构的直接破坏作用不明显，但对其引发的致热，白细胞骤降及休克死亡有较强的拮抗和防护效果。认为人参抗内毒素作用是“适应原”样中药通过对机     

中医中药对内毒素致热的解热作用

内毒素具有许多生物活性，引起一系列严重疾病。本文报道了中医中药对内毒素致热的解热机理。这对掌握机体发热、了解病情发展、合理应用药物、提高治疗效果有一定作用。     

抗内毒素抗体治疗严重烧伤内毒素血症29例

目的 研究抗内毒素抗体与抗生素对严重烧伤并发症——内毒素血症的治疗作用。方法29例患者随机分为拮抗内毒素治疗组和常规治疗组。并在烧伤后不同时相点测定了血浆内毒素、血清TNF、血浆IL-6和血浆IL-8的含量。结果抗生素和抗内毒素抗体治疗可明显减少患者血中内毒素水平（P〈0.05），同时降低IL-6，IL-8和TNF血中含量，而单用抗生素治疗对降低血中内毒素水平作用不明显。结论选择合适的抗生素配合抗内毒素抗体的早期应用，是治疗烧伤后内毒素血症及其并发症的有效方法。     

内毒素血症病机及中西医结合治疗研究进展

内毒素血症是现代医学面临的一个常见而复杂的难题。内毒素是革兰阴性菌的主要成分,抗菌药物在杀菌的同时会诱导内毒素的产生,增加治疗难度。中药制剂显示出了很好的抗内毒素作用,中西医结合比单纯西医治疗效果要好,常见的疗法有清热解毒、活血化瘀、通腑下泻、益气养阴。     

斑马鱼内毒素炎症模型建立及中药抗内毒素炎症研究

革兰阴性菌外膜结构成分脂多糖(LPS)即内毒素,是其主要致病因子,具有广泛而复杂的生物学效应,可直接或间接引起机体发热、代谢改变、免疫功能紊乱,多器官功能损害、休克乃至死亡等许多病理生理过程。这些效应主要是通过LPS与细胞表面的受体结合,激活细胞内信号转导系统,促进细胞因子及炎症介质的大量合成与释放,导致机体失控性炎症反应。在现代医学对由内毒素触发全身炎症反应综合征的治疗仍然一筹莫展的今天,不断有中药、复方或其所含成分被证明对受内毒素攻击的动物有保护作用,我们先期的研究结果亦证明中医经典复方凉膈散具有良好的抗内毒素炎症活性,从中药寻找抗内毒素治疗措施呈现良好的前景,抗内毒素中药活性筛选成为关注的热点。然而,对于中药或复方来说,由于成分复杂,影响因素众多,限制了细胞筛选体系和分子筛选体系的应用,特别是在以有效部位、提取物甚至水煎剂为研究对象时则更加困难。若用哺乳动物模型进行大规模筛选,则费时、费力、费物资,代价难以承受。利用斑马鱼模型来筛选药物已成为发现候选药物的主要技术。近年来,转基因、诱导突变和反义morpholino knockdown等技术的使用,结合活体成像技术,使斑马鱼成为研究人类炎症免疫疾病相关的病理生理学及在活体内进行高通量药物筛选的良好模式生物。近年在国家自然科学基金资助下,开展了斑马鱼内毒素炎症模型构建及基于该模型的中药抗内毒素炎症活性筛选研究。采用LPS卵黄囊注射诱导成功建立斑马鱼内毒素炎症模型。以LPS诱导的中性粒细胞及巨噬细胞的迁移聚集、斑马鱼死亡率和生存时间可作为评价抗内毒素炎症活性参考指标。利用斑马鱼内毒素炎症模型开展了凉膈散方提取物(不同极性提取部位)抗内毒素活性筛选,凉膈散方中单味中药提取物(不同极性提取部位)抗内毒素活性筛选及凉膈散方所含活性单体抗内毒素活性筛选。研究证明该模型用于中药抗内毒素活性评价是可行的。鉴于有效成分组方是创新中药研发的新形式、新方法,我们利用斑马鱼内毒素炎症模型开展了抗内毒素中药有效成分组方的配伍与配比研究,获得优化配方并申请专利保护。利用LPS诱导的马鱼内毒素炎症模型,建立适宜于不同层次(中药单体成分、单味中药及复方不同提取部位或组分)中药形式抗内毒素活性筛选方法,为抗内毒素中药筛选提供一个介于体外初筛与哺乳动物验证之间的快速、低成本和活体筛选新方法,具有良好的应用前景。     

以Lipid A为靶点拮抗内毒素中药的筛选

目的利用生物传感器跟踪技术从抗炎中药中筛选出具有拮抗内毒素的中药,为进一步对中药拮抗内毒素活性成分的分离纯化提供实验依据。方法将革兰阴性细菌的脂质A(Lipid A)包被于生物传感器的非衍生板建立靶点,跟踪测定赤芍、大黄、黄芩等78种中药的水提物和醇提物与Lipid A的结合活性,再将筛选出的中药去鞣质后与定量的内毒素(LPS,20、50ng·ml-1)37℃孵育30min后,测定孵育后的样品与Lipid A的结合情况,以评价样品内的活性物质含量。结果在所筛选的78种中药中有12种中药的水提物与Lipid A具有较高的亲和活性,在这12种中药中有6种中药的醇提物与Lipid A也具有较高的亲和活性;通过对所筛选出的12种中药的水提物去除鞣质后与LPS的消耗实验,发现所筛选出的12种中药均含有除鞣质以外的与lipid A具有特异性结合的物质,并且12种中药中能与Lipid A发生特异性结合作用的活性物质含量存在较大的差异。结论生物传感器跟踪技术是一种快速、准确、有效的筛选平台,筛选出的12种中药均含有非鞣质类能与lipid A发生特异性结合作用的物质,为进一步对12种中药抗内毒素有效部位或单体的分离提供了重要的实验依据。     

大籽獐牙菜的抗内毒素作用

目的:研究大籽獐牙菜对内毒素的拮抗作用。方法:通过观察大籽獐牙菜提取物对内毒素攻击小鼠的死亡率的影响及体外抗内毒素作用。结果:大籽獐牙菜提取物能提高内毒素攻击小鼠的生存率,延长平均存活时间。大籽獐牙菜溶液的浓度对抗内毒素作用强度的影响较大,当大籽獐牙菜浓度大于0.062 5g.mL-1(稀释度在1∶16)时对内毒素有明显的破坏作用,但当浓度稀释至0.031 2 g.mL-1(稀释度在1∶32)时,抗内毒素的作用明显减弱或消失。结论:大籽獐牙菜具有很好的抗内毒素作用。     

梗阻性黄疸治疗前后内毒素、IL-6和IL-8水平的比较

目的观察梗阻性黄疸患者术前抗内毒素治疗对内毒素（endotoxin）、白细胞介素6（IL-6）、白细胞介素8（IL-8）的影响.方法50例梗阻性黄疸患者分三组,在术前分别给予一般手术治疗（OJ组）,口服胆盐（OJT1组）和静脉注射抗内毒素抗体（OJT2组）观察血浆内毒素（ET）、IL-6及IL-8含量变化.结果三组术前ET、IL-6和IL-8水平差异不显著;OJT1组和OJT2组用药后血浆ET水平均显著下降,明显低于OJ组（P＜0.01）,术后进一步降低;IL-6在术后14d显著降低（P＜0.01）,IL-8在术后7 d降低（P＜0.05）.结论术前应用胆盐和抗内毒素抗体可有效降低梗阻性黄疸患者围手术期血浆ET、IL-6及IL-8水平.     

Endotoxin neutralizing peptides

Neutralization and sequestration of bacterial lipopolysaccharide which plays a key role in gram-negative sepsis is required to block the progression of sepsis at early stages in addition to destroying bacteria. Many of the host defense peptides which have antimicrobial activity are also able to bind to and neutralize LPS, however, these two activities do not necessarily correlate. Due to its toxicity application of polymyxin B as the prototype of LPS neutralizing peptide is limited to topical applications and extracorporeal removal of endotoxin. Development of novel endotoxin neutralizing peptides without the toxicity of polymyxin B have been based on the natural host defense peptides, fragments of LPS binding proteins and engineered peptides. Neutralization of LPS can be achieved through several different peptide fold motifs, which are reviewed in this article. Endogenous host defense peptides, fragments of endotoxin-binding proteins and synthetic anti-endotoxin peptides fold into alpha-helical, beta-hairpin, extended and compact conformations without regular secondary structure. In animal models many of the peptides have demonstrated good in vitro and in vivo endotoxin neutralizing activity but up to now none of the peptides has been approved for clinical application with an anti-endotoxin indication. Recent developments include preparation of novel types of endotoxin neutralizing compounds such as peptides modified by lipophilic moieties and non-peptidic molecules, particularly lipopolyamines and on the other hand additional medical applications such as extracorporeal endotoxin removal, targeting to inflammation sites or endotoxoid based vaccines.     

生物传感器技术在筛选赤芍中抗内毒素有效成分的应用研究

目的 :应用生物传感器技术优选赤芍中抗内毒素有效成分的提取方法。方法 :将内毒素包被于生物传感器的疏水样品池中 ,测定赤芍3种方法提取物与内毒素的亲合力及其与内毒素混合孵育后内毒素亲合力的变化。结果 :水浸法提取物与内毒素具有较高的亲合力 ,以1∶40稀释后能够中和78 1 %的内毒素。结论 :赤芍水浸法能够提取到更多的抗内毒素有效成分 ,测定结果与鲎试剂法一致 ;与传统的鲎试剂法比较 ,生物传感器技术具有快速、高效、直观、无干扰等优点。     

血必净体外拮抗内毒素的作用

目的了解血必净在体外有无拮抗内毒素的作用。方法将不同浓度的血必净和标准内毒素混合后进行水浴加热,利用鲎试验（显色基质法）检测混合液中的内毒素含量。结果随着血必净浓度的增加,与阳性对照组相比,内毒素含量略有上升,但差异无统计学意义（P〉0．05）。而随着水浴时间的延长,各实验组内毒素水平均呈现下降趋势,其差异无统计学意义（P〉0．05）。结论血必净在体外无直接拮抗内毒素的作用。     

白蔹生品与炮制品体外抗内毒素作用的比较研究

目的 对白蔹生品与炮制品进行初步对比研究分析,拟筛选出白蔹体外对内毒素拮抗作用强的样品。方法 利用鲎试剂与内毒素产生凝集反应的原理,采用一系列不同浓度样品破坏凝集反应,以初步筛选白蔹体外抗内毒素的作用。结果 白蔹炮制品在浓度为1∶2 000时,体外仍有抗内毒素作用。结论 经炮制后白蔹的体外抗内毒素作用强于白蔹生品。     

Section Review: Endotoxaemia and novel therapies for the treatment of sepsis:Pulmonary-Allergy,Dermatological, Gastrointestinal & Arthritis

Numerous agents have been developed with specific binding and inhibitory activity against endotoxin which have all shown promise in preclinical evaluations through the protection of animals against endotoxin challenge. The results of the clinical trials of agents published to date have not met the expectations generated by the results of the pre-clinical studies. A concept not reflected in animal models is that Gram-negative sepsis is a heterogeneous entity: not all patients are either bacteraemic or endotoxaemic. Sub-groups of patients that could be recognised prospectively using newer methods may not respond equally to anti-endotoxin agents. The future success of these therapeutic modalities will probably depend on our ability to identify and target the therapies to those patients who will benefit most, possibly through the application of an assay for endotoxaemia.     

Towards Clinical Applications of Anti-endotoxin Antibodies; A Re-appraisal of the Disconnect

Endotoxin is a potent mediator of a broad range of patho-physiological effects in humans. It is present in all Gram negative (GN) bacteria. It would be expected that anti-endotoxin therapies, whether antibody based or not, would have an important adjuvant therapeutic role along with antibiotics and other supportive therapies for GN infections. Indeed there is an extensive literature relating to both pre-clinical and clinical studies of anti-endotoxin antibodies. However, the extent of disconnect between the generally successful pre-clinical studies versus the failures of the numerous large clinical trials of antibody based and other anti-endotoxin therapies is under-appreciated and unexplained. Seeking a reconciliation of this disconnect is not an abstract academic question as clinical trials of interventions to reduce levels of endotoxemia levels are ongoing. The aim of this review is to examine new insights into the complex relationship between endotoxemia and sepsis in an attempt to bridge this disconnect. Several new factors to consider in this reappraisal include the frequency and types of GN bacteremia and the underlying mortality risk in the various study populations. For a range of reasons, endotoxemia can no longer be considered as a single entity. There are old clinical trials which warrant a re-appraisal in light of these recent advances in the understanding of the structure-function relationship of endotoxin. Fundamentally however, the disconnect not only remains, it has enlarged.     

Role of endogenous endotoxin on tumor necrosis factor-hypersensitivity caused by D-galactosamine challenge

We examined the role of endotoxin in the mechanism of recombinant human tumor necrosis factor (rhTNF)-hypersensitivity caused by D-galactosamine (GalN). We used polymyxin B, an antibiotic with anti-endotoxin activity, to determine the participation of endogenous endotoxin. The glycogen and blood glucose level of rhTNF (1 x 10(4) units/mouse, i.v.)-injected mice was lower at 7 h post-intoxication than that in the control. Administration of rhTNF to GalN (700 mg/kg, i.p.)-treated mice resulted in lower levels of glycogen and blood glucose than those in animals treated with rhTNF alone. In mice pretreated with polymxin B (20 mg/kg, i.p.), the level at 7 h after rhTNF/GalN-injection was markedly increased compared to that in mice treated with rhTNF/GalN alone. The injection of a low endotoxin dose (0.1 mg/kg, i.p.) markedly decreased the rectal temperature in mice treated with rhTNF (5 x 10(3) units/mouse, i.v.) and GalN, and none of these animals survived after treatment for 18 h. These findings suggest that endogenously produced endotoxin may contribute to the extent of rhTNF-hypersensitivity caused by GalN.