title: Homogentisate 1-2-Dioxygenase Downregulation in the Chronic Persistence of Pseudomonas aeruginosa Australian Epidemic Strain-1 in the CF Lung.
abstract: Some Pseudomonas aeruginosa strains including Australian Epidemic Strain-1 (AES-1 or AUS-01) cause persistent chronic infection in cystic fibrosis (CF) patients, with greater morbidity and mortality. Factors conferring persistence are largely unknown. Previously we analysed the transcriptomes of AES-1 grown in Luria broth, nematode growth medium for Caenorhabditis elegans assay (both aerobic) and artificial sputum medium (mainly hypoxic). Transcriptional comparisons included chronic AES-1 strains against PAO1 and acute AES-1 (AES-1R) against its chronic isogen (AES-1M), isolated 10.5 years apart from a CF patient and not eradicated in the meantime. Prominent amongst genes downregulated in AES-1M in all comparisons was homogentisate-1-2-dioxygenase (hmgA); an oxygen-dependent gene known to be mutationally deactivated in many chronic infection strains of P. aeruginosa. To investigate if hmgA downregulation and deactivation gave similar virulence persistence profiles, a hmgA mutant made in UCBPP-PA14 utilising RedS-recombinase and AES-1M were assessed in the C. elegans virulence assay, and the C57BL/6 mouse for pulmonary colonisation and TNF-α response. In C. elegans, hmgA deactivation resulted in significantly increased PA14 virulence while hmgA downregulation reduced AES-1M virulence. AES-1M was significantly more persistent in mouse lung and showed a significant increase in TNF-α (p<0.0001), sustained even with no detectable bacteria. PA14ΔhmgA did not show increased TNF-α. This study suggests that hmgA may have a role in P. aeruginosa persistence in chronic infection and the results provide a starting point for clarifying the role of hmgA in chronic AES-1.
authors.affiliation: Bacterial Pathogens in Cystic Fibrosis Group, Department of Infectious Diseases and Immunology, Central Clinical School, The University of Sydney, Sydney, Australia; School of Molecular Biosciences, The University of Sydney, Sydney, Australia.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Harmer
authors.affiliation: Bacterial Pathogens in Cystic Fibrosis Group, Department of Infectious Diseases and Immunology, Central Clinical School, The University of Sydney, Sydney, Australia.
authors.forename: Matthew
authors.initials: M
authors.lastname: Wynn
authors.affiliation: Microbial Pathogenesis and Immunity Group, Department of Infectious Diseases and Immunology, Central Clinical School, The University of Sydney, Sydney, Australia.
authors.forename: Rachel
authors.initials: R
authors.lastname: Pinto
authors.affiliation: School of Molecular Biosciences, The University of Sydney, Sydney, Australia.
authors.forename: Stuart
authors.initials: S
authors.lastname: Cordwell
authors.affiliation: Bacterial Pathogens in Cystic Fibrosis Group, Department of Infectious Diseases and Immunology, Central Clinical School, The University of Sydney, Sydney, Australia.
authors.forename: Barbara R
authors.initials: BR
authors.lastname: Rose
authors.affiliation: Bacterial Pathogens in Cystic Fibrosis Group, Department of Infectious Diseases and Immunology, Central Clinical School, The University of Sydney, Sydney, Australia.
authors.forename: Colin
authors.initials: C
authors.lastname: Harbour
authors.affiliation: Microbial Pathogenesis and Immunity Group, Department of Infectious Diseases and Immunology, Central Clinical School, The University of Sydney, Sydney, Australia.
authors.forename: James A
authors.initials: JA
authors.lastname: Triccas
authors.affiliation: Bacterial Pathogens in Cystic Fibrosis Group, Department of Infectious Diseases and Immunology, Central Clinical School, The University of Sydney, Sydney, Australia.
authors.forename: Jim
authors.initials: J
authors.lastname: Manos
mesh_terms: D000818:Animals; D001315:Australia; D001426:Bacterial Proteins / Q000378:metabolism; D017173:Caenorhabditis elegans / Q000382:microbiology; D003550:Cystic Fibrosis / Q000382:microbiology*; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000187:drug effects; D058872:Epidemics; D005260:Female; D005434:Flow Cytometry; D005838:Genotype; D050560:Homogentisate 1,2-Dioxygenase / Q000378:metabolism*; D016130:Immunophenotyping; D008168:Lung / Q000382:microbiology* / Q000473:pathology; D008810:Mice, Inbred C57BL; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D011552:Pseudomonas Infections / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology* / Q000472:pathogenicity; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D014409:Tumor Necrosis Factor-alpha; D050560:Homogentisate 1,2-Dioxygenase