Pseudomonas aeruginosa biofilm and planktonic bacteria display different virulence mechanisms when co-cultured with human A549 lung cells using the Calgary Biofilm Device co-culture system

dc.contributor.authorBowler, Laura
dc.contributor.examiningcommitteeZhanel, George (Medical Microbiology) Embree, Joanne (Medical Microbiology) Mookherjee, Neeloffer (Internal Medicine) Hancock, Robert (University of British Columbia)en_US
dc.contributor.supervisorBall, T. Blake (Medical Microbiology) Saward, Laura (Medical Microbiology)en_US
dc.date.accessioned2016-04-25T14:53:42Z
dc.date.available2016-04-25T14:53:42Z
dc.date.issued2014en_US
dc.date.issued2012en_US
dc.degree.disciplineMedical Microbiologyen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractCystic Fibrosis (CF) is the most common hereditary genetic disorder among Caucasians. Pseudomonas aeruginosa is a major cause of morbidity in cystic fibrosis patients. Chronic infection with P. aeruginosa eventually occurs and is associated with a switch to biofilm formation of the bacteria. The symptoms and pathology of acute and chronic P. aeruginosa infections differ greatly. The first line of defense within the lung is the physical barrier of the lung epithelia. The examination of established biofilm interactions with lung epithelia is difficult. Here, I use the Calgary Biofilm Device co-culture system to conduct the concurrent analysis of established biofilms and planktonic bacteria with A549 lung cells. Comparison of P. aeruginosa biofilm and planktonic bacteria’s effects on A549 lung cells showed that planktonic bacteria caused more A549 cell rounding and death, while biofilm stimulated more IL-8 release by epithelial cells. Biofilm was shown to secrete significantly more Pseudomonal Elastase than planktonic, causing A549 morphological changes and loss of tight junctions. The antimicrobial peptide LL-37 was shown to differentially affect biofilm and planktonic bacteria. LL-37 caused a decrease in twitching of planktonic bacteria and exposure to LL-37 for 48 hours resulted in a decrease in elastase secretion likely due to down-regulated type 2 secretion. When established biofilms were compared with newly adherent biofilms, young biofilms were shown to have characteristics similar to both planktonic bacteria and mature biofilms. From this data we can follow the pattern of bacterial virulence as P. aeruginosa transitions from the planktonic mode of growth to the eventual mature biofilm that is associated with chronic infection. In conclusion, this study provides the foundation for a co-culture system that can be used to study the host-pathogen interactions of mammalian epithelia with established P. aeruginosa biofilms. The future adaptations of this model will better represent the in vivo characteristics of chronic lung infection to delineate ongoing virulence mechanisms of the bacteria causing host cell stimulation and damage.en_US
dc.description.noteMay 2016en_US
dc.identifier.citationBowler, L. L., G. G. Zhanel, T. B. Ball, and L. L. Saward. 2012. Mature Pseudomonas aeruginosa biofilms prevail compared to young biofilms in the presence of ceftazidime. Antimicrobial Agents and Chemotherapy 56:4976-4979.en_US
dc.identifier.citationBowler, L. L., T. B. Ball, and L. L. Saward. 2014. A novel in vitro co-culture system allows the concurrent analysis of mature biofilm and planktonic bacteria with human lung epithelia. Journal of Microbiological Methods 101:49-55.en_US
dc.identifier.urihttp://hdl.handle.net/1993/31262
dc.language.isoengen_US
dc.publisherAmerican Society for Microbiologyen_US
dc.publisherElsevieren_US
dc.rightsopen accessen_US
dc.subjectBiofilmen_US
dc.subjectA549 lung epitheliaen_US
dc.subjectCo-cultureen_US
dc.subjectCystic Fibrosisen_US
dc.titlePseudomonas aeruginosa biofilm and planktonic bacteria display different virulence mechanisms when co-cultured with human A549 lung cells using the Calgary Biofilm Device co-culture systemen_US
dc.typedoctoral thesisen_US
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