Lactoferrin causes IgA and IgG2b isotype switching through betaglycan binding and activation of canonical TGF-β signaling
| Autor: | Pyeung-Hyeun Kim, Bo-Ra Jin, Jeong-Min Lee, Young-Saeng Jang, Woan-Sub Kim, Goo-Young Seo, Hekap Kim, H. Y. Seo, Sun-Jin Kim, Ki Jong Rhee, Seok-Rae Park, Hye-Ju Han |
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| Rok vydání: | 2015 |
| Předmět: |
Immunology
Plasma protein binding Biology Mice Immune system Adjuvants Immunologic Transforming Growth Factor beta Immunity medicine Animals Immunology and Allergy Smad3 Protein Receptor Immunity Mucosal B-Lymphocytes Lamina propria Lactoferrin Immunoglobulin Class Switching Molecular biology Immunoglobulin A medicine.anatomical_structure Immunoglobulin class switching Immunoglobulin G Antibody Formation biology.protein Proteoglycans Receptors Transforming Growth Factor beta Protein Binding Signal Transduction Transforming growth factor |
| Zdroj: | Mucosal Immunology. 8:906-917 |
| ISSN: | 1933-0219 |
| Popis: | Lactoferrin (LF), a pleiotropic iron-binding glycoprotein, is known to modulate the humoral immune response. However, its exact role in Ig synthesis has yet to be elucidated. In this study, we investigated the effect of LF on Ig production by mouse B cells and its underlying mechanisms. LF, like transforming growth factor (TGF)-β1, stimulated B cells to produce IgA and IgG2b, while downregulating other isotypes. Using limiting dilution analysis, LF was shown to increase the frequency of IgA-secreting B-cell clones. This was paralleled by an increase in Ig germ-line α (GLα) transcripts, indicating that LF plays a role as an IgA switch factor. Interestingly, LF directly interacted with betaglycan (TGF-β receptor III, TβRIII) and in turn induced phosphorylation of TβRI and Smad3 through formation of the TβRIII/TβRII/TβRI complex, leading to IgA isotype switching. Peroral administration of LF increased intestinal/serum IgA production as well as number of IgA plasma cells in lamina propria. Finally, we found that LF has an adjuvant activity when nontoxigenic Salmonella typhimurium was inoculated perorally, conferring protection against intragastrical infection of toxigenic S. typhimurium. These results suggest that LF has an important effect on the mucosal/systemic IgA response and can contribute to protection against intestinal pathogens. |
| Databáze: | OpenAIRE |
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