Unknown,Transcriptomics,Genomics,Proteomics

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Ex vivo transcriptional profiling reveals a common set of genes important for the adaptation of Pseudomonas aeruginosa to chronically infected host sites

ABSTRACT: The opportunistic bacterium Pseudomonas aeruginosa is a major nosocomial pathogen causing both devastating acute and chronic persistent infections. During the course of an infection, P. aeruginosa rapidly adapts to the specific conditions within the host. In the present study, we aimed at the identification of genes that are highly expressed during biofilm infections such as in chronically infected lungs of patients with cystic fibrosis (CF), burn wounds and subcutaneous mouse tumours. We found a common subset of differentially regulated genes in all three in vivo habitats and evaluated whether their inactivation impacts on the bacterial capability to form biofilms in vitro and to establish biofilm-associated infections in a murine model. Additive effects on biofilm formation and host colonization were discovered by the combined inactivation of several highly expressed genes. However, even combined inactivation was not sufficient to abolish the establishment of an infection completely. These findings can be interpreted as evidence that either redundant traits encode functions that are essential for in vivo survival and chronic biofilm infections and/or bacterial adaptation is considerably achieved independently of transcription levels. Supplemental screens, will have to be applied in order to identify the minimal set of key genes essential for the establishment of chronic infectious diseases. Ex-vivo samples were collected from burn wound, cystic fibrosis patients mucous and mice tumor and stabilized for the RNA extraction. Recovered clinical strains were cultivated in rich medium control conditions untill the early stationary phase and RNA was extracted. The murine tumors were infected with burn wound isolated strains

ORGANISM(S): Pseudomonas aeruginosa

SUBMITTER: Piotr Bielecki

PROVIDER: E-GEOD-25945 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Ex vivo transcriptional profiling reveals a common set of genes important for the adaptation of Pseudomonas aeruginosa to chronically infected host sites.

Bielecki Piotr P Komor Uliana U Bielecka Agata A Müsken Mathias M Puchałka Jacek J Pletz Mathias W MW Ballmann Manfred M Martins dos Santos Vítor A P VA Weiss Siegfried S Häussler Susanne S

Environmental microbiology 20121112 2

The opportunistic bacterium Pseudomonas aeruginosa is a major nosocomial pathogen causing both devastating acute and chronic persistent infections. During the course of an infection, P. aeruginosa rapidly adapts to the specific conditions within the host. In the present study, we aimed at the identification of genes that are highly expressed during biofilm infections such as in chronically infected lungs of patients with cystic fibrosis (CF), burn wounds and subcutaneous mouse tumours. We found ...[more]

PMID: 23145907

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Project description:Bacterial infections of wounds are associated with poor healing and worse scarring. We sought to identify transcriptomic patterns associated with impaired healing of wounds infected with Klebsiella pneumoniae (K.p.) or Pseudomonas aeruginosa (P.a.) using a rabbit ear wound model. Wounds created on post-operative day (POD) 0 were infected on POD3, within the inflammatory phase of healing. On POD4 the infected wounds were harvested for microarray/transcriptome analysis. Other wounds with 24-hour infections were treated with topical antibiotic to promote biofilm formation and harvested on POD6 or POD12. On POD4 before antibiotic treatment, both wounds contained elevated transcripts that enriched predominantly into inflammation/infection-response pathways and functions characteristic of infiltrating leukocytes. But there were 5-fold more elevated transcripts in P.a.- than K.p.-infected wounds. Additionally, unique to P.a.-infected wounds, was a minor network of inflammation/infection-response molecules with predicted upstream regulation predominated by type I interferons. Also on POD4, Dnr-transcripts of both wounds were enriched into stress-response pathways such as EIF2 signaling. But there were 8-fold more Dnr-transcripts in P.a.- than K.p.-infected wounds, and many more of them enriched in the function, cell death, suggesting that resident dermal cells of P.a.-infected wounds failed to survive a more destructive P.a. infection. On POD6, following two days of antibiotic treatment, the biofilm-colonized wounds expressed magnitudes fewer inflammation and stress-response transcripts. However, a single regulatory network of P.a.-infected wounds was found to consist of Upr-transcripts enriching immune/infection-response functions predicted to be regulated by type I interferons, which was similar to the network unique to P.a.-infected wounds on POD4. On POD12, genes expressed by K.p.-infected wounds suggesting healing, while for P.a.-infected wounds they suggested stalled healing. The similarities and differences between the wound responses to these infections further define the molecular foundations of healing impaired by infections. Rabbit ear Wounds created on post-operative day (POD) 0 were infected with Klebsiella pneumoniae (K.p.) or Pseudomonas aeruginosa (P.a.) on POD3 and harvested on POD4 for RNA extraction. Other wounds with 24-hour infections were treated with topical antibiotic to promote biofilm formation and harvested on POD6 or POD12.

Project description:The airways of cystic fibrosis patients are chronically colonized by a diverse range of microbial pathogens, the composition of which changes throughout life Alteration to the pulmonary environment caused by inter-microbial interactions and pathogen-host interactions influence the type of microbes that can engage in sustained infection. The opportunistic bacterial pathogen Pseudomonas aeruginosa is the primary cause of morbidity and mortality amongst individuals with cystic fibrosis and it is estimated that 60 – 80 % of cystic fibrosis patients experience chronic P. aeruginosa infection by the age of 20 years Aspergillus fumigatus is the most prevalent fungal pathogen isolated from cystic fibrosis airways, affecting up to 58% of patients. It is the causative agent of allergic bronchopulmonary aspergillosis (ABPA), a hypersensitivity disorder resulting from the inhalation of fungal conidia. Although co-colonization of the cystic fibrosis airways by P. aeruginosa and A. fumigatus is rare (3.1 – 15.8 %) disease prognosis is poor when both are present. However, sequential infection is more common. It has recently been suggested that A. fumigatus is more prevalent in juvenile cystic fibrosis patients that has been initially reported due to inconsistencies in the culture methods used to detect A. fumigatus. Despite the prevalence and persistence of A. fumigatus, P. aeruginosa predominates as the primary pathogen in the cystic fibrosis lung, suggesting that interactions with other pathogens such as A. fumigatus may influence the pathogenicity of P. aeruginosa by altering its virulence. We report here an investigation of the effect of culturing P. aeruginosa in the presence of A. fumigatus by measuring differences in growth rate and the overall proteome of the bacteria. It was hypothesized that A. fumigatus creates an environment that promotes a metabolic-driven increase in P. aeruginosa that results in it outcompeting the fungus. The molecular basis of this increased proliferation was investigated further using Label-free quantitative (LFQ) proteomics to characterise the proteome changes in P. aeruginosa when exposed to the supernatant of i) A. fumigatus alone ii) the supernatant of an A. fumigatus/P. aeruginosa co-culture and iii) P. aeruginosa alone. LFQ proteomics involves the simultaneous identification and quantification of thousands of proteins (the ultimate determinants of phenotype) from a single sample has recently been employed to characterise the P. aeruginosa proteome in response to iron limiting conditions, resolving how how the bacteria survives and proliferates in such environments.

Dataset Information

Ex vivo transcriptional profiling reveals a common set of genes important for the adaptation of Pseudomonas aeruginosa to chronically infected host sites

Publications

Ex vivo transcriptional profiling reveals a common set of genes important for the adaptation of Pseudomonas aeruginosa to chronically infected host sites.

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