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Characterization of different Streptococcus pneumoniae strains and their interactions with pooled human bronchoalveolar lavage fluid

Behi Åkesson, Emanuel (2023) MOBN03 20222
Degree Projects in Molecular Biology
Popular Abstract
Pneumonia is a common infectious disease of the lungs. When the lung tissue becomes inflamed, it can lead to symptoms such as cough, fever, and difficulty breathing. The most common cause of pneumonia is the bacterial species Streptococcus pneumoniae, also known as pneumococcus. This species is sometimes found in cultures from the nose or throat, without causing disease. If the immune system is weakened or if the bacteria spread to the lungs, it can cause severe infections. Streptococcus pneumoniae has different genetic strains and serotypes based on its capsule. A large variety of these are in circulation in the human population as clinical strains. A handful of strains have been commonly studied in laboratory settings for research. After... (More)
Pneumonia is a common infectious disease of the lungs. When the lung tissue becomes inflamed, it can lead to symptoms such as cough, fever, and difficulty breathing. The most common cause of pneumonia is the bacterial species Streptococcus pneumoniae, also known as pneumococcus. This species is sometimes found in cultures from the nose or throat, without causing disease. If the immune system is weakened or if the bacteria spread to the lungs, it can cause severe infections. Streptococcus pneumoniae has different genetic strains and serotypes based on its capsule. A large variety of these are in circulation in the human population as clinical strains. A handful of strains have been commonly studied in laboratory settings for research. After adaptation to this environment, these strains may differ in terms of the proteins they produce and their ability to cause disease. The aim of this thesis was to investigate which proteins different bacterial strains produce, and how they interact with host proteins in human lung samples.

Quantitative proteomics mass spectrometry methods were used to investigate the protein dynamics and interactions between different S. pneumoniae strains and liquid samples from the human respiratory tract. First, different laboratory and clinical strains of S. pneumonia were cultured and the proteins were extracted. These proteins were then identified and quantified by mass spectrometry, and the proteins expressed by the clinical strains were compared to the laboratory strains. Based on our results, 35 proteins were expressed at a higher abundance in the clinical strains as compared to the laboratory strains.

To further investigate the interactions between the bacterial strains and host proteins in the human lung, bronchoalveolar lavage fluid (BAL fluid) was used. The BAL fluid contains various proteins and molecules present in the human lung, and the composition may vary between healthy donors and individuals with an infection. Here, we incubated each strain in BAL fluid and used trypsin as an enzyme to release surface-exposed bacterial proteins together with bacteria-bound host proteins. These host and bacterial proteins were then identified and quantified by mass spectrometry. By doing so, we were able to investigate whether any specific proteins in the lung fluid bound to the bacteria. The results of the study showed that different strains of S. pneumoniae express other proteins and bind to different proteins in the lung fluid. These interactions can affect the course of the disease and the degree of inflammation in the lungs. By understanding these protein dynamics, we can gain insights that can help develop more targeted treatments and vaccines against pneumococcal pneumonia.

The research contributes to our overall knowledge of the pathogenicity of the bacterium and its interaction with the host organism. (Less)
Please use this url to cite or link to this publication:
author
Behi Åkesson, Emanuel
supervisor
organization
course
MOBN03 20222
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
9136035
date added to LUP
2023-09-01 15:52:29
date last changed
2023-09-01 15:52:29
@misc{9136035,
  author       = {{Behi Åkesson, Emanuel}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Characterization of different Streptococcus pneumoniae strains and their interactions with pooled human bronchoalveolar lavage fluid}},
  year         = {{2023}},
}