Modulation of innate defences in the neonatal gastrointestinal tract by colonizing neuropathogenic Escherichia coli

通过定植神经病原性大肠杆菌来调节新生儿胃肠道的先天防御

• 批准号: MR/K018396/1
• 负责人: Peter Taylor
• 金额: $ 47.61万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FK018396%2F1
• 关键词: Modulation; innate; defences; neonatal; gastrointestinal

Neonatal bacterial meningitis (NBM) contributes substantially to mortality and neurological disability worldwide. In developed countries, NBM affects approximately one in 3,000 newborn infants. Antibiotic therapy may not always be effective as the infection progresses very rapidly and antibiotic resistant bacteria are now more commonly found. The risks are far worse in developing countries and disease incidence is increasing due to higher survival rates of premature infants coupled with limited access to medicines. The incidence may be as high as six per 1,000 live births in regions in Africa and the disease carries significant mortality. Survivors often suffer severe consequences such as cerebral palsy, mental retardation, seizures, epilepsy and hearing impairment. Rates of neonatal sepsis, which is linked to NBM, are even higher. A strategy of prevention rather than treatment once the infection has occurred would have clear benefit but vaccination, often effective in controlling bacterial infections, cannot be employed to protect the newborn from NBM.One of the major causes of NBM is Escherichia coli. This bacterium produces a protective capsule, termed K1, and it can harmlessly colonize the mother's intestinal tract. Sometimes the infant acquires the bacterium from the mother during or shortly after birth. The K1 bacterium colonizes the gastrointestinal (GI) tract of the newborn infant and for reasons that are poorly understood may relocate to the blood and disseminate to other organs, including the brain. These potentially lethal infections tend to occur within the first four weeks of life. Key features of the human infection, particularly the strong age dependency, can be replicated in the experimental rat. Two-day-old (P2) rats are highly susceptible to infection after colonization whereas nine-day-old animals are completely resistant. I wish to understand the basis of this age dependency as this may provide a platform for novel preventative measures to protect the newborn infant. Recent work by my collaborator has established that the small intestine is protected by a thin layer of mucus and a high concentration of peptides that protect this region of the gut. In the colon, protection is primarily afforded by a very thick, structured layer of mucus. My group has very recently shown that in the younger (P2) neonates neither of the barriers to infection is well-formed. In addition, the incoming K1 colonizers appear to suppress maturation of the mucus layers and do not provoke secretion of the antibacterial peptides. These physical and chemical barriers keep bacteria at a safe distance from the gut wall; allowing them to get close to cell surfaces may support their relocation to the blood. We now wish to determine if these factors are responsible for the age dependency of the infection and to define key steps in the infection process. We will establish the site in the GI tract from which K1 bacteria escape into the circulation; this will be important in formulating strategies for preventing this relocation. The "defensin" peptides are produced by Paneth cells in the small intestines; these are present in only small numbers in the P2 rats. We will examine the role of these cells by assessing the impact of K1 colonization on peptide secretion and by chemically interfering with peptide secretion. We will track the development of the intestinal mucus layer over the first two weeks of life and determine how K1 colonization affects this maturation. If we can establish that circumvention of these barriers by K1 bacteria is the basis of susceptibility to infection, we will dose K1-colonized P2 rats with a protein, termed Tff2, which drives the assembly of the protective mucus barrier. If Tff2 can reduce or prevent infection in susceptible rat pups by promoting mucus layer maturation, it could be used as a new approach to the prevention of this disease.

新生儿细菌性脑膜炎（NBM）是世界范围内死亡率和神经功能障碍的主要原因。在发达国家，NBM影响大约每3，000名新生儿中的一名。抗生素治疗可能并不总是有效的，因为感染进展非常迅速，而且抗生素耐药细菌现在更常见。发展中国家的风险要严重得多，由于早产儿存活率较高，加上药物获取渠道有限，疾病发病率正在增加。在非洲一些地区，发病率可高达每1 000名活产6人，死亡率很高。幸存者往往遭受严重后果，如脑瘫、智力迟钝、癫痫发作、癫痫和听力障碍。与NBM相关的新生儿败血症的发病率甚至更高。一旦感染发生，预防而不是治疗策略将有明显的好处，但疫苗接种通常可以有效控制细菌感染，但不能用来保护新生儿免受NBM的侵害。NBM的主要原因之一是大肠杆菌。这种细菌产生一种保护性的胶囊，称为K1，它可以无害地定植在母亲的肠道。有时婴儿在出生期间或出生后不久从母亲那里获得细菌。K1细菌定植于新生儿的胃肠道（GI），由于尚不清楚的原因，可能会重新定位到血液中并传播到其他器官，包括大脑。这些潜在的致命感染往往发生在生命的前四周内。人类感染的关键特征，特别是强烈的年龄依赖性，可以在实验大鼠中复制。两日龄（P2）的大鼠在定植后对感染高度敏感，而九日龄的动物则完全具有抵抗力。我希望了解这种年龄依赖性的基础，因为这可能为保护新生儿的新预防措施提供一个平台。我的合作者最近的工作已经确定，小肠受到一层薄薄的粘液和高浓度的肽的保护，这些肽保护着肠道的这一区域。在结肠中，保护主要由非常厚的结构化粘液层提供。我的研究小组最近发现，在较年轻的（P2）新生儿中，两种感染屏障都没有形成。此外，进入的K1定殖体似乎抑制粘液层的成熟，并且不引起抗菌肽的分泌。这些物理和化学屏障使细菌与肠壁保持安全距离;允许它们接近细胞表面可能会支持它们重新定位到血液中。我们现在希望确定这些因素是否与感染的年龄依赖性有关，并确定感染过程中的关键步骤。我们将在胃肠道中确定K1细菌逃逸进入循环的部位;这对于制定预防这种迁移的策略至关重要。“防御素”肽由小肠中的潘氏细胞产生;这些肽在P2大鼠中仅少量存在。我们将通过评估K1定殖对肽分泌的影响和通过化学干扰肽分泌来检查这些细胞的作用。我们将跟踪生命最初两周内肠粘液层的发育，并确定K1定植如何影响这种成熟。如果我们能够确定K1细菌对这些屏障的规避是感染易感性的基础，我们将给K1定殖的P2大鼠注射一种名为Tff 2的蛋白质，该蛋白质驱动保护性粘液屏障的组装。如果Tff 2可以通过促进粘液层成熟来减少或预防易感大鼠幼仔的感染，那么它可以用作预防这种疾病的新方法。

项目成果

Genome-Wide Identification by Transposon Insertion Sequencing of Escherichia coli K1 Genes Essential for In Vitro Growth, Gastrointestinal Colonizing Capacity, and Survival in Serum.

• DOI: 10.1128/jb.00698-17
• 发表时间: 2018-04-01
• 期刊: Journal of bacteriology
• 影响因子: 3.2
• 作者: McCarthy AJ;Stabler RA;Taylor PW
• 通讯作者: Taylor PW

Impact of the Mk VI SkinSuit on skin microbiota of terrestrial volunteers and an International Space Station-bound astronaut.

• DOI: 10.1038/s41526-017-0029-5
• 发表时间: 2017
• 期刊: NPJ microgravity
• 影响因子: 5.1
• 作者: Stabler RA;Rosado H;Doyle R;Negus D;Carvil PA;Kristjánsson JG;Green DA;Franco-Cendejas R;Davies C;Mogensen A;Scott J;Taylor PW
• 通讯作者: Taylor PW

Pathoadaptive Mutations of Escherichia coli K1 in Experimental Neonatal Systemic Infection.

• DOI: 10.1371/journal.pone.0166793
• 发表时间: 2016
• 期刊: PloS one
• 影响因子: 3.7
• 作者: McCarthy AJ;Negus D;Martin P;Pechincha C;Oswald E;Stabler RA;Taylor PW
• 通讯作者: Taylor PW

Postnatal development of the small intestinal mucosa drives age-dependent, regio-selective susceptibility to Escherichia coli K1 infection.

• DOI: 10.1038/s41598-017-00123-w
• 发表时间: 2017-03-06
• 期刊: Scientific reports
• 影响因子: 4.6
• 作者: Birchenough GM;Dalgakiran F;Witcomb LA;Johansson ME;McCarthy AJ;Hansson GC;Taylor PW
• 通讯作者: Taylor PW

Loss of Trefoil Factor 2 Sensitizes Rat Pups to Systemic Infection with the Neonatal Pathogen Escherichia coli K1.

三叶因子 2 的缺失使幼鼠对新生儿病原体大肠杆菌 K1 的全身感染敏感。

• DOI: 10.1128/iai.00878-18
• 发表时间: 2019
• 期刊: Infection and immunity
• 影响因子: 3.1
• 作者: McCarthy AJ