Co-culture Models of Pseudomonas aeruginosa Biofilms Grown on Live Human Airway Cells
Summary
This paper describes different methods of growing Pseudomonas aeruginosa biofilms on cultured human airway epithelial cells. These protocols can be adapted to study different aspects of biofilm formation, including visualization of the biofilm, staining of the biofilm, measuring the colony forming units (CFU) of the biofilm, and studying biofilm cytotoxicity.
Abstract
Bacterial biofilms have been associated with a number of different human diseases, but biofilm development has generally been studied on non-living surfaces. In this paper, we describe protocols for forming Pseudomonas aeruginosa biofilms on human airway epithelial cells (CFBE cells) grown in culture. In the first method (termed the Static Co-culture Biofilm Model), P. aeruginosa is incubated with CFBE cells grown as confluent monolayers on standard tissue culture plates. Although the bacterium is quite toxic to epithelial cells, the addition of arginine delays the destruction of the monolayer long enough for biofilms to form on the CFBE cells. The second method (termed the Flow Cell Co-culture Biofilm Model), involves adaptation of a biofilm flow cell apparatus, which is often used in biofilm research, to accommodate a glass coverslip supporting a confluent monolayer of CFBE cells. This monolayer is inoculated with P. aeruginosa and a peristaltic pump then flows fresh medium across the cells. In both systems, bacterial biofilms form within 6-8 hours after inoculation. Visualization of the biofilm is enhanced by the use of P. aeruginosa strains constitutively expressing green fluorescent protein (GFP). The Static and Flow Cell Co-culture Biofilm assays are model systems for early P. aeruginosa infection of the Cystic Fibrosis (CF) lung, and these techniques allow different aspects of P. aeruginosa biofilm formation and virulence to be studied, including biofilm cytotoxicity, measurement of biofilm CFU, and staining and visualizing the biofilm.
Protocol
Discussion
Biofilms are communities of bacteria that form in response to environmental stimuli. These environmental signals lead to global regulatory changes within each bacterium, resulting in binding to a surface, aggregation, production of exopolysaccharides, and other phenotypes such as increased antibiotic resistance10. Over the last couple of decades, much evidence has supported the hypothesis that biofilms play a large role in the pathogenesis of chronic infections. For instance, it is well accepted that P. ae…
Disclosures
The authors have nothing to disclose.
Acknowledgements
We would like to thank G. O Toole for guidance and suggestions in developing these models. This work was supported by the Cystic Fibrosis Foundation (ANDERS06F0 to G.G.A., STANTO07RO and STANTO08GA to B.A.S.), the National Institutes of Health (T32A107363 to G.G.A. and R01-HL074175 to B.A.S.), and the National Center for Research Resources Centers for Biomedical Research Excellence (COBRE P20-RR018787 to B.A.S.).
Materials
| Material Name | Type | Company | Catalogue Number | Comment |
|---|---|---|---|---|
| FCS2 (Focht Live-Cell) chamber | Bioptechs, Butler, PA | 060319131616 | ||
| FCS2 chamber controller | Bioptechs, Butler, PA | 060319-2-0303 | ||
| 40 mm glass coverslips | Bioptechs, Butler, PA | PH 40-1313-0319 | ||
| MEM | Mediatech, Manassass, VA | #10-010-CV | ||
| MEM without phenol red | Mediatech, Manassass, VA | Mediatech, Manassass, VA |
References
- Anderson, G. G., Moreau-Marquis, S., Stanton, B. A., O’Toole, G. A. In vitro analysis of tobramycin-treated Pseudomonas aeruginosa biofilms on cystic fibrosis-derived airway epithelial cells. Infect Immun. 76, 1423-1433 (2008).
- Bruscia, E. Isolation of CF cell lines corrected at DeltaF508-CFTR locus by SFHR-mediated targeting. Gene Ther. 9, 683-685 (2002).
- Cozens, A. L. CFTR expression and chloride secretion in polarized immortal human bronchial epithelial cells. Am J Respir Cell Mol Biol. 10, 38-47 (1994).
- Hentchel-Franks, K. Activation of airway cl- secretion in human subjects by adenosine. Am J Respir Cell Mol Biol. 31, 140-146 (2004).
- Moreau-Marquis, S. The DeltaF508-CFTR mutation results in increased biofilm formation by Pseudomonas aeruginosa by increasing iron availability. Am J Physiol Lung Cell Mol Physiol. 295, 25-37 (2008).
- Kuchma, S. L., Connolly, J. P., O’Toole, G. A. A three-component regulatory system regulates biofilm maturation and type III secretion in Pseudomonas aeruginosa. J Bacteriol. 187, (2005).
- Heydorn, A. Experimental reproducibility in flow-chamber biofilms. Microbiology. 146 (Pt 10), 2409-2415 (2000).
- Heydorn, A. Quantification of biofilm structures by the novel computer program COMSTAT. Microbiology. 146 (Pt 10), 2395-2407 (2000).
- Anderson, G. G., Yahr, T. L., Lovewell, R. R., O’Toole, G. A. The Pseudomonas aeruginosa magnesium transporter MgtE inhibits transcription of the type III secretion system. Infect Immun. 78, (2010).
- Costerton, J. W. Overview of microbial biofilms. J Ind Microbiol. 15, 137-140 (1995).
- Hoiby, N., Frederiksen, B., Pressler, T. Eradication of early Pseudomonas aeruginosa infection. J Cyst Fibros. 4, 49-54 (2005).
- Ko, Y. H., Pedersen, P. L. Cystic fibrosis: a brief look at some highlights of a decade of research focused on elucidating and correcting the molecular basis of the disease. J Bioenerg Biomembr. 33, 513-521 (2001).
- Gibson, R. L., Burns, J. L., Ramsey, B. W. Pathophysiology and management of pulmonary infections in cystic fibrosis. Am J Respir Crit Care Med. 168, 918-951 (2003).
- Furukawa, S., Kuchma, S. L., O’Toole, G. A. Keeping their options open: acute versus persistent infections. J Bacteriol. 188, 1211-1217 (2006).
- Merritt, J. H., Kadouri, D. E., O’Toole, G. A. Growing and analyzing static biofilms. Curr Protoc Microbiol. Chapter 1, Unit 1B 1-Unit 1B 1 (2005).
- O’Toole, G. A., Kolter, R. Initiation of biofilm formation in Pseudomonas fluorescens WCS365 proceeds via multiple, convergent signalling pathways: a genetic analysis. Mol Microbiol. 28, 449-461 (1998).
- Gomez, M. I., Prince, A. Opportunistic infections in lung disease: Pseudomonas infections in cystic fibrosis. Curr Opin Pharmacol. 7, 244-251 (2007).
