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Published on: March 23, 2019
Spermidine enhances the survival of Streptococcus pyogenes M3 under oxidative stress
Rajashri Banerji1, Parvati Iyer1, Sunil D Saroj1
1Symbiosis School of Biological Sciences, Symbiosis International (Deemed University), Pune, Maharashtra, India.
Abstract:
Streptococcus pyogenes, a host-restricted gram-positive pathogen during infection, initially adheres to the epithelia of the nasopharynx and respiratory tract of the human host, followed by disseminating to other organs and evading the host immune system. Upon phagocytosis, S. pyogenes encounters oxidative stress inside the macrophages. The role of polyamines in regulating various physiological functions including stress resistance in bacteria has been reported widely. Since S. pyogenes lacks the machinery for the biosynthesis of polyamines, the study aimed to understand the role of extracellular polyamines in the survival of S. pyogenes under oxidative stress environments. S. pyogenes being a catalase-negative organism, we report that its survival within the macrophages and H2 O2 is enhanced by the presence of spermidine. The increased survival can be attributed to the upregulation of oxidative stress response genes such as sodM, npx, and mtsABC. In addition, spermidine influences the upregulation of virulence factors such as sagA, slo, and hasA. Also, spermidine leads to a decrease in hydrophobicity of the cell membrane and an increase in hyaluronic acid. This study suggests a role for extracellular spermidine in the survival of S. pyogenes under oxidative stress environments. Recognizing the factors that modulate S. pyogenes survival and virulence under stress will assist in understanding its interactions with the host.
Insights
Extracellular spermidine enhances Streptococcus pyogenes survival against oxidative stress, boosting virulence factor production. This finding aids in understanding pathogen-host interactions during infection.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Streptococcus pyogenes is a human pathogen that adheres to the nasopharynx and respiratory tract, disseminating to other organs.
- Upon phagocytosis, S. pyogenes faces oxidative stress within macrophages.
- S. pyogenes lacks endogenous polyamine biosynthesis, necessitating exogenous sources for physiological functions.
Purpose of the Study:
- To investigate the role of extracellular polyamines in S. pyogenes survival under oxidative stress.
- To determine how spermidine affects S. pyogenes resistance to oxidative environments, such as within macrophages and hydrogen peroxide (H₂O₂).
Main Methods:
- Exposure of S. pyogenes to oxidative stress (macrophages and H₂O₂) in the presence and absence of spermidine.
- Quantitative analysis of bacterial survival rates.
- Gene expression analysis using quantitative PCR to assess oxidative stress response and virulence genes.
- Measurement of cell membrane hydrophobicity and hyaluronic acid production.
Main Results:
- Spermidine significantly enhanced S. pyogenes survival in oxidative environments, including within macrophages and in the presence of H₂O₂.
- Upregulation of oxidative stress response genes (sodM, npx, mtsABC) and virulence factors (sagA, slo, hasA) was observed with spermidine treatment.
- Spermidine decreased cell membrane hydrophobicity and increased hyaluronic acid production.
Conclusions:
- Extracellular spermidine plays a crucial role in the survival of Streptococcus pyogenes under oxidative stress conditions.
- Spermidine enhances bacterial resistance by upregulating specific stress response genes and virulence factors.
- Understanding spermidine's influence is vital for comprehending S. pyogenes pathogenesis and host interactions.
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