Project description:One of the hallmarks of Pseudomonas aeruginosa cystic fibrosis (CF) infection is very high-cell-density (HCD) replication in the lung, allowing this bacterium to induce virulence controlled by HCD quorum-sensing systems. However, the nutrient sources sustaining HCD replication in this chronic infection is largely unknown. Hence, understanding the nutrient factors contributing to HCD in the CF lung will yield new insights into the 'metabolic pathogenicity' and potential treatment of CF infections caused by P. aeruginosa. Herein, we performed microarray studies of P. aeruginosa directly isolated from the CF lung to demonstrate its metabolic capability and virulence in vivo. Our in vivo microarray data, confirmed by real-time reverse-transcription-PCR, indicated P. aeruginosa expressed several genes for virulence, drug-resistance, and utilization of multiple nutrient sources (lung surfactant lipids and amino acids) contributing to HCD replication. The data also indicates deregulation of several pathways, suggesting in vivo evolution by deregulation of a large portion of the transcriptome during chronic CF infection. To our knowledge, this is the first in vivo transcriptome of P. aeruginosa in a natural CF infection, and it indicates several important aspects of pathogenesis, drug-resistance, and nutrient-utilization never before observed in vivo. Experiment Overall Design: The purpose of the experiment was to observe which genes are upregulated in P. aeruginosa during chronic CF lung infection as compared to PAO1. All in vitro studies were grown in 1x M9 minimal media supplemented with 20 mM citrate and grown to mid-log phase prior to RNA isolation. The in vivo RNA was isolated directly from CF sputum samples after TRIzol treatment. Each in vitro sample (both for PAO1 and the CF sputum pool isolate) were processed individually and in triplicate. Two in vivo isolations from sputum were conducted from the same patient but two different sputum samples. After isolation of total RNA, samples were processed for microarrays (i.e. cDNA synthesis, fragmentation, labeling, etc) as recommended by Affymetrix, and processed on the GeneChip as recommended by Affymetrix.

Project description:Cystic Fibrosis lung disease progresses by a combination of accelerated airways inflammation and bacterial colonization and infection. Airways inflammation in CF is predominantly neutrophilic and complicates airway clearance therapies through cellular debris, excessive DNA, excessive and viscous mucous, and high concentrations of neutrophils,Il-8 and related cytokines liberated along the NFkB signaling pathway. We conducted a single site, randomized, double blind, placebo-controlled, proof-of-concept trial in which we evaluated the effects of 28 days of two dose levels (0.05 mg and 0.10 mg daily) of an older cardiac glycoside, digitoxin, as compared with placebo, on inflammatory markers in induced sputum obtained from 24 subjects with mild to moderate CF lung disease. Nasal epithelial cells from 23 subjects were analyzed for microarray analysis. CF patients 18 to 45 years old, any genotype combination, were eligible. The primary objective was to measure the effects of digitoxin on IL-8 and neutrophil counts in induced sputum. Secondary objectives were to measure: 1) the pharmacokinetics of digitoxin in serum in stable CF patients, 2) safety indices, including ECG changes and sputum microbiology, in stable CF patients, 3) the effect of digitoxin on gene expression in nasal epithelial cells of stable CF patients and 4) quality of life scores using the CFQ-R©. As expected, it took several weeks to achieve a detectable serum level of digitoxin in CF. Digitoxin showed a trend towards reduction in sputum free neutrophil elastase and neutrophil counts, but was not associated with a reduction in sputum Il-8. Digitoxin did not dampen sputum inflammation as measured by primary and secondary outcome measures over the 28 day study period. However the patient groups receiving placebo and 50 micro gram digitoxin daily fell into similar patterns which were distinctly different from the patient group taking 100 micro gram digitoxin. The mRNAs encoding chemokine/cytokine or cell surface receptors in immune cells were decreased in nasal epithelial cells at the higher dose, leading to pathway mediated reductions in Il-8, Il-6, lung epithelial inflammation, neutrophil recruitment and mucus hypersecretion. It is possible that a longer treatment period would be necessary to detect a meaningful, dose- dependent change in sputum indices of inflammation in CF. Importantly, there were no safety issues over the course of the study

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Human lung metagenome

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