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Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae
Published on: January 17, 2014
Immunomodulatory effects of vitamin D on innate and adaptive immune responses to Streptococcus pneumoniae
Marie Olliver1, Laura Spelmink, Jeffni Hiew
1Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
Background:
Streptococcus pneumoniae forms part of the normal nasopharyngeal flora but can also cause a broad spectrum of inflammatory diseases. Vitamin D has potent effects on human immunity, including induction of antimicrobial peptides and suppression of T-cell proliferation, but its ability to modulate the immune response to pneumococci is unknown.
Methods:
Monocyte-derived dendritic cells (DCs) were stimulated with pneumococcal peptidoglycan (PGN) in the presence or absence of vitamin D. Expression of maturation markers, cytokines, pattern recognition receptors, and antimicrobial peptides were measured with flow cytometry, enzyme-linked immunosorbent assay and quantitative polymerase chain reaction. Stimulated DCs were cocultured with autologous T-helper cells, and concentrations of T-helper (Th) 1-, Th17-, and regulatory T-cell-related cytokines were measured with enzyme-linked immunosorbent assay.
Results:
Vitamin D enhanced DC maturation and expression of the migration marker C-C chemokine receptor type 7 (CCR7) in PGN-stimulated cells. It also enhanced expression of key pattern recognition receptors (Toll-like receptor 2, Nucleotide-binding oligomerization domain-containing protein 2 [Nod2]) and induced a synergistic up-regulation of the inflammatory mediator IL-1β and the β-defensin Human Beta Defensin 3 (hBD-3). Furthermore, vitamin D skewed the DC-mediated T-helper response to PGN from an inflammatory Th1/Th17 phenotype toward a regulatory T-cell phenotype.
Conclusion:
Vitamin D modulates key elements of innate immunity while dampening adaptive immune responses in DCs after pneumococcal challenge, which may have implications for prevention and treatment of pneumococcus-induced inflammation.
Insights
Vitamin D enhances dendritic cell maturation and immune responses to Streptococcus pneumoniae. It shifts T-helper cells from an inflammatory to a regulatory phenotype, potentially aiding in pneumococcus-induced inflammation management.
Area of Science:
- Immunology
- Microbiology
- Nutritional Science
Background:
- Streptococcus pneumoniae is a common bacterium that can cause various inflammatory diseases.
- Vitamin D is known to influence human immunity, but its role in modulating the immune response to pneumococci was unclear.
Purpose of the Study:
- To investigate how vitamin D affects the immune response of dendritic cells (DCs) to Streptococcus pneumoniae.
Main Methods:
- Dendritic cells were stimulated with pneumococcal peptidoglycan (PGN) with or without vitamin D.
- Key immune markers, cytokines, and T-helper cell responses were analyzed using various laboratory techniques.
Main Results:
- Vitamin D enhanced DC maturation and expression of migration markers (CCR7).
- It increased pattern recognition receptors (TLR2, Nod2), IL-1β, and Human Beta Defensin 3 (hBD-3).
- Vitamin D promoted a shift from inflammatory Th1/Th17 to regulatory T-cell responses.
Conclusions:
- Vitamin D modulates innate immunity and dampens adaptive immune responses in DCs following pneumococcal challenge.
- These findings suggest potential roles for vitamin D in preventing and treating pneumococcus-induced inflammation.
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