Mechanisms of host-pathogen interaction between the bovine endometrium and the cholesterol dependent cytolysin of Trueperella pyogenes

牛子宫内膜与化脓性真杆菌溶细胞素相互作用的机制奶牛在分娩后常患子宫细菌性疾病。我们将发现最重要的细菌是如何破坏子宫细胞的，以及细胞是如何反应的。研究结果将指导新疗法的发展。奶牛很重要，因为它们为人类提供牛奶。牛奶的产量取决于奶牛的生育能力，因为如果没有小牛，就没有牛奶。奶牛每年需要产一头小牛来维持产奶量，所以它们必须在产犊后3个月左右怀孕。然而，奶牛中的一种常见疾病威胁着这一过程。奶牛产犊后特别容易受到子宫感染。每年几乎有一半的奶牛患上子宫细菌感染，导致生殖道排出大量脓液，给动物带来痛苦和折磨。这种疾病还会减少产奶量并导致不孕。不幸的是，在过去的四十年里，治疗方法几乎没有变化，也不是特别有效，许多动物仍然无法生育。子宫疾病每年花费欧盟乳业14亿欧元用于治疗、减少产奶量和更换不育动物。农民们饲养额外的动物来代替不育的奶牛，但这些额外的动物也对环境造成了破坏性影响。额外的动物意味着对土地和水资源的更大压力，以及温室气体的增加。因此，迫切需要提高对子宫疾病的治疗。有几种细菌会引起子宫疾病，但只有化脓性真芽孢杆菌——字面意思是“脓液制造者”——的存在与疾病的严重程度、组织损伤和不孕症始终相关。有许多临床研究测试经验性治疗子宫疾病，但很少成功。我们的想法是从问题的“另一端”开始，找出将化脓性真芽孢菌与疾病联系起来的机制。我们所有的产自患病子宫的化脓性真芽杆菌菌株都会产生一种叫做溶血素的毒素。感染人体不同组织的其他致病细菌也会产生类似的毒素。这些毒素被吸引到细胞膜上的胆固醇区域，在那里形成洞，杀死细胞。在初步工作中，我们已经确定溶血素也杀死子宫内膜细胞。研究目的我们的研究目的是了解子宫细胞对溶血素的反应；性激素或新陈代谢如何影响对毒素的反应；以及细胞如何检测溶血素并防御它。研究首先，我们将测试子宫中每种类型的细胞对溶血素的敏感性——毒素杀死细胞的浓度以及细胞对较低浓度的反应。为了帮助这些实验，我们有纯的溶血素，抗溶血素的抗体，并对我们的化脓性T.菌株进行基因操作以去除产生溶血素的能力。我们在收集和使用子宫细胞方面有多年的经验，最近开发了一种在实验室中研究完整子宫组织的新方法。为了进一步了解疾病的机制，我们将研究调节子宫内膜功能的激素和代谢如何也可能改变溶血素与细胞之间的相互作用。最后，我们将确定细胞用来检测或识别溶血素的机制，以及它们保护自己免受毒素侵害的方式。我们感到鼓舞的是，我们可以向前迈出一大步，因为在初步工作中，我们意外发现了某些保护子宫内膜细胞不受溶血素影响的药物。我们的研究将为合理设计限制或预防牛子宫疾病的新疗法提供一个平台。

Mechanisms of interaction between the bovine endometrium and the cytolysin of Trueperella pyogenesDairy cows commonly suffer bacterial disease of the uterus after parturition. We will find out how the most important bacteria damage the cells of the uterus and how the cells respond. The results will direct the development of new treatments.IMPORTANCEDairy cows are important as they supply milk for human consumption. Production of milk depends on the fertility of the cow, because if there is no calf, there is no milk. Cows need to produce a calf each year to maintain milk production, so they must conceive about 3 months after calving. However, a common disease among dairy cows threatens this process. Dairy cows are particularly susceptible to infection of the uterus after calving. Every year almost half of all dairy cows develop a bacterial infection of the uterus, resulting in the discharge of copious amounts of pus from the genital tract, and causing the animal pain and suffering. The disease also reduces milk yields and causes infertility. Unfortunately, treatments have changed little in the last forty years and are not particularly effective, with many animals remaining infertile. Uterine disease costs the EU dairy industry 1.4 billion Euro each year for treatment, reduced milk yields and replacement of infertile animals. Farmers keep extra animals to replace infertile cows but these extra animals also have a damaging effect on the environment. Extra animals mean more strain on land and water resources, and increased production of greenhouse gases. So, there is an urgent need to improve the treatment of uterine disease.CONTEXTSeveral bacteria cause uterine disease, but only the presence of Trueperella pyogenes - literally "the pus producer" - is consistently associated with the severity of disease, tissue damage and infertility. There have been many clinical studies testing empirical treatments for uterine disease but with little success. Our idea is to start at the "other end" of the problem and find out the mechanisms linking Trueperella pyogenes with disease. All our strains of Trueperella pyogenes from the diseased uterus produce a toxin called pyolysin. Other disease-causing bacteria that infect different tissues in the human body produce similar toxins. These toxins are attracted to areas of cholesterol in the cell membrane where they form holes, which kills the cells. In preliminary work we have established that pyolysin also kills endometrial cells.RESEARCH AIMSOur research aims are to find out how the cells of the uterus respond to pyolysin; how sex hormones or metabolism affect the response to the toxin; and how cells detect pyolysin and defend themselves against it.THE RESEARCHFirst we will test how sensitive each of the cell types in the uterus is to pyolysin - what concentration of the toxin kills the cells and how the cells respond to lower concentrations. To aid in these experiments we have pure pyolysin, antibodies against pyolysin, and genetically manipulated on of our strains of T. pyogenes to remove the ability to produce pyolysin. We have many years of experience in collecting and using the cells from the uterus, and recently developed a new method of studying intact uterine tissue in the laboratory. To further understand the mechanisms of disease, we will work out how the hormones and metabolism that regulate endometrial function may also modify the interaction between pyolysin and cells. Finally, we will identify the mechanisms used by cells to detect or recognise pyolysin, and the ways in which they defend themselves against the toxin. We are encouraged that we can make a major step forward because, during preliminary work, we made an unexpected discovery of certain drugs that protect endometrial cells against pyolysin.IMPACT OF THE RESEARCHOur research will provide a platform for the rational design of new treatments to limit or prevent uterine disease in cattle.