2023-10-27 14:21:36
New Study Reveals How Antibodies Influence Nasal Microbiome
Researchers at the University of Tübingen have discovered new insights into the relationship between antibodies and the nasal microbiome. The study, led by Rob van Dalen, explored the role of secretory immunoglobulin A (sIgA) in influencing the number and composition of bacteria in the nose.
The nose serves as a gateway for bacteria and viruses from the air we breathe. To combat these pathogens, beneficial bacteria and our immune system collaborate in the mucous membrane of the nose. The researchers found that a higher level of sIgA is associated with a lower quantity of bacteria. Each individual’s antibody reactions to bacteria were observed to vary, suggesting a personalized response.
The nasal microbiome significantly impacts our health, affecting susceptibility to allergies and respiratory diseases. Helpful microorganisms and our immune system work together to ward off harmful germs. sIgA is an antibody variant that binds to bacteria and renders them harmless. This antibody is found not only in nasal secretions but also in saliva, sweat, intestinal fluid, tears, and breast milk. However, its specific influence on the nasal microbiome had remained unclear until now.
The team analyzed nasal swabs from 50 healthy individuals, measuring the sIgA levels and bacterial communities. They also examined the molecular interactions between the antibodies and bacteria. The researchers discovered that the amount of sIgA secreted into the nasal mucosa varied greatly among individuals. Additionally, a negative correlation was observed between sIgA levels and bacterial density. Subjects with lower sIgA levels had significantly more bacteria in their noses. However, the diversity of bacterial species was not affected by sIgA levels.
Furthermore, the study found that different individuals showed varying reactions between their nasal bacteria and sIgA. While certain bacteria triggered a strong immune response in some individuals, they remained unaffected in others. This suggests that the immune reaction depends on factors such as genetics and local conditions in the nose.
The researchers also identified the presence of Staphylococcus aureus in the nasal microbiome of eight test subjects. While this bacterium is usually harmless, it can cause life-threatening infections under certain circumstances. The variant methicillin-resistant Staphylococcus aureus (MRSA), which is resistant to many antibiotics, is particularly concerning in hospital settings. To understand the interactions between S. aureus and the immune system, the researchers investigated how sIgA binds to the bacterium’s surface at a molecular level.
A specific interaction was discovered between sIgA and a surface protein of S. aureus called staphylococcal protein A (SpA). This protein has been previously linked to the bacterium’s resistance against various human antibodies. Manipulating the binding between SpA and sIgA could potentially enhance the immune response against S. aureus, offering new treatment possibilities.
The findings of this study hold potential for developing new treatment methods as well as vaccines administered through the nasal mucosa. Current nasal vaccines include flu vaccines for children and young people, and research is underway for nasal vaccines against Covid-19. However, further research is needed before the published results can be applied in clinical practice.
As our understanding of the antibody response to bacteria in the nasal microbiome improves, it opens up opportunities for regulating these microbial systems and developing effective treatments.
Source: Rob van Dalen (University of Tübingen) et al., Microbiome, doi: 10.1186/s40168-023-01675-y]
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