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Abstract
Group A Streptococcus (GAS) causes 700 million infections and accounts for half a million deaths per year. Biofilm formation has been implicated in both pharyngeal and dermal GAS infections. In vitro, plate-based assays have shown that several GAS M-types form biofilms, and multiple GAS virulence factors have been linked to biofilm formation. Although the contributions of these plate-based studies have been valuable, most have failed to mimic the host environment, with many studies utilising abiotic surfaces. GAS is a human specific pathogen, and colonisation and subsequent biofilm formation is likely facilitated by distinct interactions with host tissue surfaces. As such, a host cell-GAS model has been optimised to support and grow GAS biofilms of a variety of GAS M-types. Improvements and adjustments to the crystal violet biofilm biomass assay have also been tailored to reproducibly detect delicate GAS biofilms. We propose 72 h as an optimal growth period for yielding detectable biofilm biomass. GAS biofilms formed are robust and durable, and can be reproducibly assessed via staining/washing intensive assays such as crystal violet with the aid of methanol fixation prior to staining. Lastly, SEM imaging of GAS biofilms formed by this model revealed GAS cocci chains arranged into three-dimensional aggregated structures with EPS matrix material. Taken together, we outline an efficacious GAS biofilm pharyngeal cell model that can support long-term GAS biofilm formation, with biofilms formed closely resembling those seen in vivo.
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Affiliation(s)
- Heema K N Vyas
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.,School of Chemistry and Molecular Bioscience, Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia
| | - Jason D McArthur
- School of Chemistry and Molecular Bioscience, Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia
| | - Martina L Sanderson-Smith
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia. .,School of Chemistry and Molecular Bioscience, Molecular Horizons, University of Wollongong, Wollongong, NSW, Australia.
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Williams JG, Ly D, Geraghty NJ, McArthur JD, Vyas HKN, Gorman J, Tsatsaronis JA, Sluyter R, Sanderson-Smith ML. Streptococcus pyogenes M1T1 Variants Induce an Inflammatory Neutrophil Phenotype Including Activation of Inflammatory Caspases. Front Cell Infect Microbiol 2021; 10:596023. [PMID: 33585270 PMCID: PMC7876443 DOI: 10.3389/fcimb.2020.596023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 12/07/2020] [Indexed: 12/15/2022] Open
Abstract
Invasive infections due to group A Streptococcus (GAS) advance rapidly causing tissue degradation and unregulated inflammation. Neutrophils are the primary immune cells that respond to GAS. The neutrophil response to GAS was characterised in response to two M1T1 isolates; 5448 and animal passaged variant 5448AP. Co-incubation of neutrophils with 5448AP resulted in proliferation of GAS and lowered the production of reactive oxygen species when compared with 5448. Infection with both strains invoked neutrophil death, however apoptosis was reduced in response to 5448AP. Both strains induced neutrophil caspase-1 and caspase-4 expression in vitro, with inflammatory caspase activation detected in vitro and in vivo. GAS infections involving strains such as 5448AP that promote an inflammatory neutrophil phenotype may contribute to increased inflammation yet ineffective bacterial eradication, contributing to the severity of invasive GAS infections.
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Affiliation(s)
- Jonathan G. Williams
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Diane Ly
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Nicholas J. Geraghty
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Jason D. McArthur
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Heema K. N. Vyas
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Jody Gorman
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - James A. Tsatsaronis
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Ronald Sluyter
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Martina L. Sanderson-Smith
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
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Vyas HKN, Proctor EJ, McArthur J, Gorman J, Sanderson-Smith M. Current Understanding of Group A Streptococcal Biofilms. Curr Drug Targets 2020; 20:982-993. [PMID: 30947646 PMCID: PMC6700754 DOI: 10.2174/1389450120666190405095712] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 04/01/2019] [Accepted: 04/02/2019] [Indexed: 02/01/2023]
Abstract
Background: It has been proposed that GAS may form biofilms. Biofilms are microbial communities that aggregate on a surface, and exist within a self-produced matrix of extracellular polymeric substances. Biofilms offer bacteria an increased survival advantage, in which bacteria persist, and resist host immunity and antimicrobial treatment. The biofilm phenotype has long been recognized as a virulence mechanism for many Gram-positive and Gram-negative bacteria, however very little is known about the role of biofilms in GAS pathogenesis. Objective: This review provides an overview of the current knowledge of biofilms in GAS pathogenesis. This review assesses the evidence of GAS biofilm formation, the role of GAS virulence factors in GAS biofilm formation, modelling GAS biofilms, and discusses the polymicrobial nature of biofilms in the oropharynx in relation to GAS. Conclusion: Further study is needed to improve the current understanding of GAS as both a mono-species biofilm, and as a member of a polymicrobial biofilm. Improved modelling of GAS biofilm formation in settings closely mimicking in vivo conditions will ensure that biofilms generated in the lab closely reflect those occurring during clinical infection.
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Affiliation(s)
- Heema K N Vyas
- School of Chemistry and Molecular Bioscience, and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Emma-Jayne Proctor
- School of Chemistry and Molecular Bioscience, and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Jason McArthur
- School of Chemistry and Molecular Bioscience, and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Jody Gorman
- School of Chemistry and Molecular Bioscience, and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
| | - Martina Sanderson-Smith
- School of Chemistry and Molecular Bioscience, and Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, Australia
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