Control of Pseudomonas aeruginosa Quorum Sensing and Alginate

铜绿假单胞菌群体感应和藻酸盐的控制

• 批准号: 8240832
• 负责人: Michael John Schurr
• 金额: $ 19.82万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8240832
• 关键词: Acute; Alginates; Alleles; Antibiotic Resistance; Burn injury; Chromosomes; Chronic; Cyanides; Cystic Fibrosis; Data; Development; Gene Activation; Genes; Genetic Transcription; Goals; Growth; Immune; Immune system; In Vitro; Individual; Infection; Lung; Maintenance; Mediating; Microbial Biofilms; Modeling; Morbidity - disease rate; Mus; Natural Immunity; Organism; Outcome; Pathogenesis; Pathway interactions; Patients; Phosphorylation; Pilum; Preventive; Property; Pseudomonas; Pseudomonas aeruginosa; Publishing; Pyocyanine; Rattus; Regulatory Pathway; Regulon; Repression; Research; Role; Septicemia; Signal Transduction; Staging; System; Testing; Therapeutic; Therapeutic Intervention; Transplant Recipients; Transplantation; Virulence; Virulence Factors; Work; base; cell motility; cystic fibrosis patients; improved; innovation; mortality; mucoid; novel strategies; pathogen; quorum sensing; response; rhamnolipid; therapeutic target

DESCRIPTION (provided by applicant): Pseudomonas aeruginosa is a ubiquitous, opportunistic pathogen primarily infecting individuals with a compromised immune system, including transplant patients; severe burn patients, and those with cystic fibrosis (CF). In the context of CF, P. aeruginosa establishes a chronic condition whose morbidity and mortality results from lung damage. Due to the uncanny antibiotic resistance, CF patients infected with Pseudomonas often have chronic infections with limited therapeutic options. Therefore, for improved efficacy in treatment, a basic understanding of the pathogenic mechanisms utilized by this organism needs to be examined for possible therapeutic targets. While a majority of previous studies have focused on the initial stages of colonization and infection, we propose a new approach in searching for treatments. Mounting evidence indicates that a biofilm mode of growth is most likely involved in P. aeruginosa pathogenesis. Many virulence factors are produced by P. aeruginosa under this growth condition including alginate, rhamnolipids, type IV pili and cyanide. Others and we have discovered that a response regulator AlgR, controls all of these virulence factors. We discovered that AlgR is required for biofilm formation and that it represses the Rhl quorum sensing system in a biofilm. We have most recently created an algR allele that is constitutively active, algRD54E. PAO1 harboring algRD54E on the chromosome is defective in biofilm formation and does not produce pyocyanin. Our data show two new roles for AlgR: (i) AlgR is able to repress and activate genes when it is constitutively "on" and; (ii) AlgR is controlling the Rhl quorum sensing system of P. aeruginosa. The proposed research is innovative because we are examining the role of quorum sensing in mucoid P.a.. The proposed research is also innovative because we are determining the mechanism for a transcriptional regulator that regulates five different virulence factors and can activate transcription when it is either phosphorylated or unphosphorylated. The hypothesis to be tested is: AlgR controls the Rhl quorum sensing system in mucoid P.a., thus allowing the organism to persist in chronic infections. We will test this hypothesis with two specific aims: 1) We will determine the mechanism of AlgR control on the Rhl QS system in in vitro P.a. biofilm formation and 2) We will determine the mechanism of AlgR control on the Rhl QS system in P.a. virulence. PUBLIC HEALTH RELEVANCE: Pseudomonas aeruginosa (P.a.) is an opportunistic pathogen primarily infecting immune compromised individuals, including transplant, severe burn, and cystic fibrosis (CF) patients. CF patients infected with Pseudomonas often have limited therapeutic options due to natural and selected antibiotic resistance of this organism. Our recent published research indicates that the regulatory system used to control alginate also controls a larger signaling system (the quorum sensing system) that stimulates many virulence determinants in P.a.. We will examine the effects of this regulatory cascade in a rat lung infection model. We anticipate that results from this work will decrease P.a. virulence and potentially aid in treatment of P.a. chronic infections.

描述（由申请人提供）：铜绿假单胞菌是一种普遍存在的机会性病原体，主要感染免疫系统受损的个体，包括移植患者；严重烧伤患者和囊性纤维化（CF）患者。在CF的背景下，铜绿假单胞菌建立了一种慢性疾病，其发病率和死亡率的结果是肺损伤。由于不可思议的抗生素耐药性，感染假单胞菌的CF患者通常有慢性感染，治疗选择有限。因此，为了提高治疗效果，需要对该生物利用的致病机制有一个基本的了解，以寻找可能的治疗靶点。虽然以前的大多数研究都集中在定植和感染的初始阶段，但我们提出了一种寻找治疗方法的新方法。越来越多的证据表明，一种生物膜模式的生长最有可能参与铜绿假单胞菌的发病机制。P. aeruginosa在这种生长条件下产生许多毒力因子，包括海藻酸盐、鼠李糖脂、IV型菌毛和氰化物。我们发现了一个反应调节因子AlgR，控制着所有这些毒力因子。我们发现AlgR是生物膜形成所必需的，并且它抑制生物膜中的Rhl群体感应系统。我们最近创建了一个具有组成活性的algR等位基因algRD54E。染色体上携带algRD54E的PAO1在生物膜形成中存在缺陷，不产生pyocyanin。我们的数据显示了AlgR的两个新作用：(i) AlgR能够抑制和激活基因，当它构成“开启”和；（ii） AlgR控制着铜绿假单胞菌的Rhl群体感应系统。提出的研究是创新的，因为我们正在研究群体感应在黏液P.a中的作用。拟议的研究也具有创新性，因为我们正在确定一种转录调节剂的机制，该机制调节五种不同的毒力因子，并且可以在磷酸化或未磷酸化时激活转录。待验证的假设是：AlgR控制黏液P.a中的Rhl群体感应系统，从而使生物体在慢性感染中持续存在。我们将从两个方面验证这一假设：1)在体外P.a.生物膜形成过程中，我们将确定AlgR对Rhl QS系统的控制机制；2)在P.a.毒力过程中，我们将确定AlgR对Rhl QS系统的控制机制。