| 1. |
- Albert, Heike, et al.
(författare)
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In vivo enzymatic modulation of IgG glycosylation inhibits autoimmune disease in an IgG subclass-dependent manner
- 2008
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 105:39, s. 15005-15009
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Tidskriftsartikel (refereegranskat)abstract
- IgG antibodies are potent inducers of proinflammatory responses. During autoimmune diseases such as arthritis and systemic lupus erythematosus, IgG autoantibodies are responsible for the chronic inflammation and destruction of healthy tissues by cross-linking Fc receptors on innate immune effector cells. The sugar moiety attached to the asparagine-297 residue in the constant domain of the antibody is critical for the overall structure and function of the molecule. Removal of this sugar domain leads to the loss of the proinflammatory activity, suggesting that in vivo modulation of antibody glycosylation might be a strategy to interfere with autoimmune processes. In this work, we investigated whether removal of the majority of the IgG-associated sugar domain by endoglycosidase S (EndoS) from Streptococcus pyogenes is able to interfere with autoimmune inflammation. We demonstrate that EndoS injection efficiently removes the IgG-associated sugar domain in vivo and interferes with autoantibody-mediated proinflammatory processes in a variety of autoimmune models. Importantly, however, we observed a differential impact of EndoS-mediated sugar side chain hydrolysis on IgG activity depending on the individual IgG subclass.
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| 2. |
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| 3. |
- Allhorn, Maria, et al.
(författare)
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Human IgG/FcgammaR Interactions Are Modulated by Streptococcal IgG Glycan Hydrolysis.
- 2008
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The human pathogen Streptococcus pyogenes produces an endoglycosidase, EndoS that hydrolyzes the chitobiose core of the asparagine-linked glycan on the heavy chain of human IgG. IgG-binding to Fc gamma receptors (FcgammaR) on leukocytes triggers effector functions including phagocytosis, oxidative burst and the release of inflammatory mediators. The interactions between FcgammaR and the Fc domain of IgG depend on the IgG glycosylation state. METHODOLOGY/PRINCIPAL FINDINGS: Here we show for the first time that EndoS hydrolyzes the heavy chain glycan of all four human IgG subclasses (IgG1-4), in purified form and in a plasma environment. An inactive form of EndoS, obtained by site-directed mutagenesis, binds IgG with high affinity, in contrast to wild type EndoS that only transiently interacts with IgG, as shown by Slot-blotting and surface plasmon resonance technology. Furthermore, EndoS hydrolysis of the IgG glycan influences the binding of IgG to immobilized soluble FcgammaR and to an erythroleukemic cell line, K562, expressing FcgammaRIIa. Incubation of whole blood with EndoS results in a dramatic decrease of IgG binding to activated monocytes as analyzed by flow cytometry. Moreover, the IgG bound to K562 cells dissociates when cells are treated with EndoS. Likewise, IgG bound to immobilized FcgammaRIIa and subsequently treated with EndoS, dissociates from the receptor as analyzed by surface plasmon resonance and Western blot. CONCLUSIONS/SIGNIFICANCE: We provide novel information about bacterial enzymatic modulation of the IgG/FcgammaR interaction that emphasizes the importance of glycosylation for antibody effector functions. Moreover, EndoS could be used as a biochemical tool for specific IgG N-glycan hydrolysis and IgG purification/detection, or as a potential immunosuppressing agent for treatment of antibody-mediated pathological processes.
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| 4. |
- Kutty Selva, Nandakumar, et al.
(författare)
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Endoglycosidase treatment abrogates IgG arthritogenicity: Importance of IgG glycosylation in arthritis.
- 2007
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Ingår i: European Journal of Immunology. - Weinheim : Wiley. - 1521-4141 .- 0014-2980. ; 37:10, s. 2973-2982
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Tidskriftsartikel (refereegranskat)abstract
- The glycosylation status of IgG has been implicated in the pathology of rheumatoid arthritis. Earlier, we reported the identification of a novel secreted endo-beta-N-acetylglucosaminidase (EndoS), secreted by Streptococcus pyogenes that specifically hydrolyzes the beta-1,4-di-N-acetylchitobiose core of the asparagine-linked glycan of human IgG. Here, we analyzed the arthritogenicity of EndoS-treated collagen type II (CII) -specific mouse mAb in vivo. Endoglycosidase treatment of the antibodies inhibited the induction of arthritis in (BALB/c x B10.Q) F1 mice and induced a milder arthritis in B10.RIII mice as compared with the severe arthritis induced by non-treated antibodies. Furthermore, EndoS treatment did not affect the binding of IgG to CII and their ability to activate complement, but it resulted in reduced IgG binding to Fc gamma R and disturbed the formation of stable immune complexes. Hence, the asparagine-linked glycan on IgG plays a crucial role in the development of arthritis.
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