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A novel family of type VI-secreted toxins affecting Rho GTPases, actin dynamics and inflammation

影响 Rho GTP 酶、肌动蛋白动力学和炎症的 VI 型分泌毒素的新家族

基本信息

批准号：
MR/P022480/1
负责人：
Miguel Valvano
金额：
$ 45.31万
依托单位：
Queen's University Belfast
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=MR%2FP022480%2F1
关键词：
novel family type VI secreted

项目摘要

To be successful, pathogens must overcome humoral and cellular innate immune barriers. Host innate immune cells (e.g. macrophages) engulf and trap bacteria in membrane-bound vesicles known as phagosomes. Engulfed pathogens, however, disarm macrophages and counteract immunity by deploying proteins (effectors) that subvert key cellular pathways. The host cell cytoskeleton's critical role in both detection of bacterial pathogens and mobilization of antibacterial responses is an emerging theme in infection biology. Indeed, pathogen-induced disorganization of the actin network is a remarkable anti-host strategy, also perceived by macrophages as a danger signal driving inflammation and cell death. However, the actin network in the context of chronic diseases that impair macrophage functions (e.g. cystic fibrosis, diabetes, chronic obstructive pulmonary disease) has not been explored. We and others discovered that cystic fibrosis (CF) gene-defective macrophages fail to clear engulfed bacteria and play a central role in maintaining the chronic inflammation state associated with disease. Based on the CF model, we hypothesize that intracellular pathogens engulfed by macrophages, combined with an underlying chronic defect, induce disorganization of the actin network that leads to a highly proinflammatory state.We will examine this hypothesis using the intracellular opportunistic pathogen Burkholderia cenocepacia, which infects 2-10% of CF patients worldwide, rapidly accelerating their clinical decay. Unlike other CF pathogens, Burkholderia cenocepacia does not reside in biofilms in the lungs of patients but primarily within macrophages. We established Burkholderia cenocepacia as a model organism for cellular microbiology. Specifically, a Burkholderia cenocepacia type VI-secretion system (T6SS-Bc) disrupts the actin network and elicits pyroptosis in macrophages (cell death with exaggerated proinflammatory responses). These phenotypes depend on TecA ("T6SS effector protein affecting cytoskeletal Architecture"), a novel toxin recently discovered in our laboratory that inactivates Rho GTPases. This landmark discovery underpins the proposed study combining cellular and molecular microbiology approaches to investigate how intracellular Burkholderia cenocepacia manipulates the macrophages' actin network. We will address 3 questions:(i)How TecA is secreted by the T6SS-Bc?(ii)How defective actin polymerization is sensed by the Pyrin inflammasome?(iii) What is the status of the Pyrin inflammasome in Burkholderia cenocepacia infected CF gene-defective human peripheral monocytes?Understanding how opportunistic pathogens modulate the macrophages' actin network to drive inflammation will enable the discovery of new checkpoints for controlling dysregulated inflammation secondary to bacterial infection, which could be targeted to develop novel therapies to treat patients with chronic, underlying immune disorders.

为了成功，病原体必须克服体液和细胞先天免疫屏障。宿主先天免疫细胞（例如巨噬细胞）吞噬并捕获被称为吞噬体的膜结合囊泡中的细菌。然而，吞噬的病原体通过部署破坏关键细胞通路的蛋白质（效应器）来解除巨噬细胞的武装并抵消免疫力。宿主细胞骨架在细菌病原体的检测和抗菌反应的动员中的关键作用是感染生物学中的新兴主题。事实上，病原体诱导的肌动蛋白网络的解体是一种显着的抗宿主策略，也被巨噬细胞视为驱动炎症和细胞死亡的危险信号。然而，在损害巨噬细胞功能的慢性疾病（例如囊性纤维化、糖尿病、慢性阻塞性肺病）的背景下的肌动蛋白网络尚未被探索。我们和其他人发现，囊性纤维化（CF）基因缺陷的巨噬细胞无法清除吞噬的细菌，并在维持与疾病相关的慢性炎症状态中发挥核心作用。基于CF模型，我们假设被巨噬细胞吞噬的细胞内病原体，结合潜在的慢性缺陷，诱导肌动蛋白网络的解体，导致高度的促炎状态。我们将使用细胞内机会致病菌新洋葱伯克霍尔德菌来检验这一假设，该病原体感染全球2-10%的CF患者，迅速加速其临床衰变。与其他CF病原体不同，新洋葱伯克霍尔德菌不存在于患者肺部的生物膜中，而是主要存在于巨噬细胞中。我们建立了新洋葱伯克霍尔德菌作为细胞微生物学的模式生物。具体而言，新洋葱伯克霍尔德氏菌VI型分泌系统（T6 SS-Bc）破坏肌动蛋白网络，并导致巨噬细胞中的焦亡（细胞死亡伴过度的促炎反应）。这些表型依赖于TecA（“影响细胞骨架结构的T6 SS效应蛋白”），这是我们实验室最近发现的一种新型毒素，可使Rho GTP酶失活。这一具有里程碑意义的发现支持了结合细胞和分子微生物学方法来研究细胞内Burkholderia cenocepacia如何操纵巨噬细胞肌动蛋白网络的拟议研究。我们将解决3个问题：（i）T6 SS-Bc如何分泌TecA？（ii）Pyrin炎性小体如何感知有缺陷的肌动蛋白聚合？(iii)新洋葱伯克霍尔德菌感染CF基因缺陷的人外周血单核细胞中Pyrin炎性小体的状态如何？了解机会性病原体如何调节巨噬细胞的肌动蛋白网络以驱动炎症将能够发现新的检查点，用于控制继发于细菌感染的失调炎症，这可以有针对性地开发新的疗法来治疗慢性潜在免疫疾病患者。

项目成果

期刊论文数量（8）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Bacterial conversion of a host weapon into a nutritional signal.

DOI：
10.1016/j.jbc.2022.102600
发表时间：
2022-11
期刊：
JOURNAL OF BIOLOGICAL CHEMISTRY
影响因子：
4.8
作者：
Valvano, Miguel A.
通讯作者：
Valvano, Miguel A.

Defining chaperone-usher fimbriae repertoire in Serratia marcescens.

定义粘质沙雷氏菌中的伴侣引座菌毛。

DOI：
10.1016/j.micpath.2021.104857
发表时间：
2021
期刊：
Microbial pathogenesis
影响因子：
3.8
作者：
González-Montalvo MA
通讯作者：
González-Montalvo MA

Exploring the Topology of Cytoplasmic Membrane Proteins Involved in Lipopolysaccharide Biosynthesis by in Silico and Biochemical Analyses.

通过计算机模拟和生化分析探索参与脂多糖生物合成的细胞质膜蛋白的拓扑结构。

DOI：
10.1007/978-1-0716-2581-1_5
发表时间：
2022
期刊：
Methods in molecular biology (Clifton, N.J.)
影响因子：
0
作者：
Monjarás Feria J
通讯作者：
Monjarás Feria J

Interferon-gamma-activated macrophages infected with Burkholderia cenocepacia process and present bacterial antigens to T-cells by class I and II major histocompatibility complex molecules.

DOI：
10.1080/22221751.2020.1818632
发表时间：
2020-12
期刊：
Emerging microbes & infections
影响因子：
13.2
作者：
Rosales-Reyes R;Garza-Villafuerte P;Vences-Vences D;Aubert DF;Aca-Teutle R;Ortiz-Navarrete VF;Bonifaz LC;Carrero-Sánchez JC;Olivos-García A;Valvano MA;Santos-Preciado JI
通讯作者：
Santos-Preciado JI

An Overview of Anti-Eukaryotic T6SS Effectors.