Interaction of polymicrobial biofilms with human immune cells

多种微生物生物膜与人体免疫细胞的相互作用

• 批准号: 2089928
• 金额: --
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2089928
• 关键词: Interaction; polymicrobial; biofilms; human; immune

Multidrug resistance is causing redundancy of entire classes of antibiotics and making the end of the "antibiotic era", in which common infections and minor injuries can kill, a real possibility. The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and enterobacteriaceae) are resistant to the biocidal action of antibiotics and there is an urgent need for the development of new antimicrobial options underpinned by a better understanding of the pathogenicity of ESKAPE organisms.P. aeruginosa (PA) is a highly versatile environmental organism. PA flourishes in the hospital setting where it causes serious infections in immunocompromised and burn patients. PA infection is especially troublesome in Cystic Fibrosis (CF) patients where it is a major determinant of the irreversible loss of lung function and mortality. Breach of immune defences enables PA to cause intractable infections due to its intrinsic resistance to antibiotics and ability to form biofilms. Transition from planktonic to sessile growth and biofilm development are central to PA pathogenesis. There is an urgent need to better understand how the switch to a biofilm life style contributes to PA virulence and how immune cells detect and respond to these structures. PA biofilms consist of an extracellular matrix containing two main carbohydrate polymers, Psl and Pel. Our recent results show that three major carbohydrate-binding (lectin) receptors expressed by immune cells, DC-SIGN (CD209), the mannose receptor (MR, CD206) and Dectin-2, interact with PA biofilms. Binding is calcium-dependent, inhibited by relevant sugars, and observed in biofilms formed by PAO1 and clinical isolates. DC-SIGN, MR and Dectin-2 ligands within biofilms showed differential distribution. Human monocyte-derived dendritic cells (huDCs) incubated with wells containing Psl+/Pel+, Psl+/Pel- and Psl-/Pel+ biofilms alongside wells containing bacteria non capable of biofilm formation Psl-/Pel- selectively produce IL-1B (4 and 18 h) and IL-23 (only 4 h) in response to biofilm-containing wells, with biofilms containing more Psl tending to induce less IL 23. Further, specific blockage of lectin receptors in huDCs alters their response to PA biofilms. These results suggest that biofilms do not just provide an effective barrier against immune attack but could also modulate immune cell activation in the context of PA infection through engagement of lectin receptors. Many infections, such as pulmonary infections occurring in patients with CF, are polymicrobial in nature. Most children with CF are initially colonised with S. aureus in their airways. With time S. aureus is commonly replaced with PA, resulting in a period of co-infection. S. aureus can produce a multilayered biofilm embedded within a glycocalyx or slime layer. The glycocalix contains a polysaccharide antigen named polysaccharide intercellular antigen (PIA). PIA is composed of B-1,6-linked N-acetylglucosamine residues (80-85%) and an anionic fraction with a lower content of non-N-acetylated D-glucosaminyl residues that contains phosphate and ester-linked succinate (15-20%). No receptors for PIA have been described to date. We hypothesise that mixed biofilms formed by PA and S. aureus will display altered carbohydrate production leading to differential engagement of lectin receptors and differential activation of human immune cells. The specific aims of this project are (i) to investigate how PA and S. aureus mixed biofilms influence the activation of human immune cells (ii) and determine the contribution of lectin receptors to these responses.

多重耐药性正在导致整个抗生素类别的冗余，并使“抗生素时代”结束，在这个时代，普通感染和轻微伤害都可能导致死亡，这是一个真实的可能性。ESKAPE病原体（屎肠球菌、金黄色葡萄球菌、肺炎克雷伯氏菌、鲍曼不动杆菌、铜绿假单胞菌和肠杆菌科）对抗生素的杀菌作用具有抗性，并且迫切需要开发新的抗菌剂选择以更好地理解ESKAPE微生物的致病性为基础。PA在医院环境中传播，在免疫功能低下和烧伤患者中引起严重感染。PA感染在囊性纤维化（CF）患者中尤其麻烦，其中PA感染是肺功能不可逆丧失和死亡率的主要决定因素。由于PA对抗生素的内在抗性和形成生物膜的能力，免疫防御的破坏使PA能够引起难治性感染。从无张力到固着生长和生物膜发育的转变是PA发病机制的核心。迫切需要更好地了解生物膜生活方式的转变如何有助于PA毒力以及免疫细胞如何检测和响应这些结构。PA生物膜由含有两种主要碳水化合物聚合物Psl和Pel的细胞外基质组成。我们最近的研究结果表明，免疫细胞表达的三种主要的碳水化合物结合（凝集素）受体，DC-SIGN（CD 209），甘露糖受体（MR，CD 206）和Dectin-2，与PA生物膜相互作用。结合是钙依赖性的，受相关糖的抑制，并在PAO 1和临床分离株形成的生物膜中观察到。DC-SIGN、MR和Dectin-2配体在生物膜中的分布存在差异。与含有Psl+/Pel+、Psl+/Pel-和Psl-/Pel+生物膜的威尔斯孔以及含有不能形成生物膜的细菌Psl-/Pel-的威尔斯孔一起孵育的人单核细胞衍生的树突细胞（huDC）响应于含有生物膜的威尔斯孔选择性地产生IL-1B（4和18小时）和IL-23（仅4小时），其中含有更多Psl的生物膜倾向于诱导更少的IL 23。此外，huDC中凝集素受体的特异性阻断改变了它们对PA生物膜的响应。这些结果表明，生物膜不仅提供了对抗免疫攻击的有效屏障，而且还可以通过与凝集素受体的结合来调节PA感染背景下的免疫细胞活化。许多感染，如CF患者发生的肺部感染，本质上是多微生物感染。大多数患有CF的儿童最初被S.金黄色葡萄球菌时间S。金黄色葡萄球菌通常被PA替代，导致一段时间的合并感染。S.金黄色葡萄球菌可产生嵌入糖萼或粘液层内的多层生物膜。糖杯含有称为多糖细胞间抗原（PIA）的多糖抗原。PIA由B-1，6-连接的N-乙酰葡糖胺残基（80-85%）和含有磷酸盐和酯连接的琥珀酸盐的非N-乙酰化D-葡糖胺基残基含量较低的阴离子级分（15-20%）组成。迄今为止还没有描述PIA的受体。我们推测PA和S.金黄色葡萄球菌将显示改变的碳水化合物产生，导致凝集素受体的差异接合和人免疫细胞的差异活化。本项目的具体目标是：（i）研究PA和S。金黄色葡萄球菌混合生物膜影响人免疫细胞的活化（II）并决定凝集素受体对这些应答的贡献。