Adaptive immune response to lipoproteins of Staphylococcus aureus in healthy subjects
Chi Hai Vu1, Julia Kolata1,2, Sebastian Stentzel1
1Institute of Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany.
Abstract:
Staphylococcus aureus is a frequent commensal but also a dangerous pathogen, causing many forms of infection ranging from mild to life-threatening conditions. Among its virulence factors are lipoproteins, which are anchored in the bacterial cell membrane. Lipoproteins perform various functions in colonization, immune evasion, and immunomodulation. These proteins are potent activators of innate immune receptors termed Toll-like receptors 2 and 6. This study addressed the specific B-cell and T-cell responses directed to lipoproteins in human S. aureus carriers and non-carriers. 2D immune proteomics and ELISA approaches revealed that titers of antibodies (IgG) binding to S. aureus lipoproteins were very low. Proliferation assays and cytokine profiling data showed only subtle responses of T cells; some lipoproteins did not elicit proliferation. Hence, the robust activation of the innate immune system by S. aureus lipoproteins does not translate into a strong adaptive immune response. Reasons for this may include inaccessibility of lipoproteins for B cells as well as ineffective processing and presentation of the antigens to T cells.
Insights
Staphylococcus aureus lipoproteins strongly activate innate immunity but elicit weak adaptive immune responses. This suggests lipoproteins may be hidden or poorly presented to B and T cells, hindering adaptive immunity.
Area of Science:
- Microbiology
- Immunology
- Bacterial Pathogenesis
Background:
- Staphylococcus aureus is a common bacterium that can cause serious infections.
- Bacterial lipoproteins are key virulence factors involved in immune evasion and modulation.
- Lipoproteins activate innate immune receptors like Toll-like receptors 2 and 6.
Purpose of the Study:
- To investigate B-cell and T-cell responses to Staphylococcus aureus lipoproteins.
- To compare immune responses in human S. aureus carriers and non-carriers.
Main Methods:
- Two-dimensional (2D) immune proteomics
- Enzyme-linked immunosorbent assay (ELISA)
- T-cell proliferation assays
- Cytokine profiling
Main Results:
- Antibody (IgG) titers against S. aureus lipoproteins were low in humans.
- T-cell responses were subtle, with some lipoproteins failing to induce proliferation.
- Innate immune activation by lipoproteins did not correlate with a strong adaptive immune response.
Conclusions:
- S. aureus lipoproteins, despite activating innate immunity, do not trigger robust adaptive immunity.
- Potential reasons include poor accessibility for B cells and inefficient antigen presentation to T cells.
- This disconnect may impact host defense strategies against S. aureus infections.
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