| 1. |
- Albert, Heike, et al.
(author)
-
In vivo enzymatic modulation of IgG glycosylation inhibits autoimmune disease in an IgG subclass-dependent manner
- 2008
-
In: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 105:39, s. 15005-15009
-
Journal article (peer-reviewed)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.
|
|
| 2. |
- Allhorn, Maria, et al.
(author)
-
EndoS from Streptococcus pyogenes is hydrolyzed by the cysteine proteinase SpeB and requires glutamic acid 235 and tryptophans for IgG glycan-hydrolyzing activity
- 2008
-
In: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 8:1
-
Journal article (peer-reviewed)abstract
- ABSTRACT: BACKGROUND: The endoglycosidase EndoS and the cysteine proteinase SpeB from the human pathogen Streptococcus pyogenes are functionally related in that they both hydrolyze IgG leading to impairment of opsonizing antibodies and thus enhance bacterial survival in human blood. In this study, we further investigated the relationship between EndoS and SpeB by examining their in vitro temporal production and stability and activity of EndoS. Furthermore, theoretical structure modeling of EndoS combined with site-directed mutagenesis and chemical blocking of amino acids was used to identify amino acids required for the IgG glycan-hydrolyzing activity of EndoS. RESULTS: We could show that during growth in vitro S. pyogenes secretes the IgG glycan-hydrolyzing endoglycosidase EndoS prior to the cysteine proteinase SpeB. Upon maturation SpeB hydrolyzes EndoS that then loses its IgG glycan-hydrolyzing activity. Sequence analysis and structural homology modeling of EndoS provided a basis for further analysis of the prerequisites for IgG glycan-hydrolysis. Site-directed mutagenesis and chemical modification of amino acids revealed that glutamic acid 235 is an essential catalytic residue, and that tryptophan residues, but not the abundant lysine or the single cysteine residues, are important for EndoS activity. CONCLUSIONS: We present novel information about the amino acid requirements for IgG glycan-hydrolyzing activity of the immunomodulating enzyme EndoS. Furthermore, we show that the cysteine proteinase SpeB processes/degrades EndoS and thus emphasize the importance of the SpeB as a degrading/processing enzyme of proteins from the bacterium itself.
|
|
| 3. |
|
|
| 4. |
- Allhorn, Maria, et al.
(author)
-
Human IgG/FcgammaR Interactions Are Modulated by Streptococcal IgG Glycan Hydrolysis.
- 2008
-
In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 3:1
-
Journal article (peer-reviewed)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.
|
|
| 5. |
- Allhorn, Maria, et al.
(author)
-
Sugar-free antibodies--the bacterial solution to autoimmunity?
- 2009
-
In: Annals of the New York Academy of Sciences. - : Wiley. - 0077-8923. ; 1173, s. 664-669
-
Journal article (peer-reviewed)abstract
- The enzyme EndoS from Streptococcus pyogenes is an immunomodulatory molecule hydrolyzing the conserved glycans in the effector part of immunoglobulin G (IgG). EndoS is remarkably specific for IgG, and hydrolysis has profound effects on IgG effector functions. EndoS pretreatment of IgG, or direct administration to animals with experimental antibody-mediated autoimmune diseases, inhibits development of disease or cures animals from established disease. The properties of EndoS make it a unique experimental tool and an attractive alternative to current therapies of conditions involving pathogenic antibodies. This review describes the discovery of EndoS, the effects of EndoS on IgG effector functions in vitro and in vivo, the biotechnological potential of EndoS, and the outcomes of EndoS treatment in animal models of autoimmunity.
|
|
| 6. |
-
Bacterial Sensing and Signaling
- 2009
-
Editorial collection (other academic/artistic)abstract
- One of the keys to the development of novel anti-infective strategies. Over the last fifteen years it has become increasingly obvious that bacteria are not as simple and solitary as once believed. Rather, an accumulating body of work shows that bacteria are highly complicated and social organisms, constantly sensing their surroundings and altering both their environments and behaviors to ensure survival. Direct communication between bacteria turns out to be quite common, as are coordinated intra- and interspecies responses that include the formation of highly sophisticated microbial communities. In fact, threats to bacterial survival from assaults ranging from nutrient deprivation and oxygen depletion to the defenses of eukaryotic hosts are all managed through the integration of a dizzying array of complex sensory and communication systems with the appropriate bacterial behaviors. This volume provides an update of the current knowledge in the expanding field of bacterial sensing and signaling, highlighting its most important and interesting aspects. In twelve state-of-the-art articles, respected international experts address topics such as quorum sensing and secondary messengers, chemotaxis and magnetoaerotaxis, two-component phosphotransferase systems, bacterial virulence mechanisms, thermoregulation, and more. The final chapter represents a unique description of the tools available to manipulate many of the sensing and signaling systems described in this volume. Bacterial Sensing and Signaling is recommended reading for students, scientists and clinicians with interests in microbiology, immunology, ecology, biotechnology and a range of other disciplines.
|
|
| 7. |
- Chartier, Clement, et al.
(author)
-
Analysis of Smokeless Spray Combustion in a Heavy-Duty Diesel Engine by Combined Simultaneous Optical Diagnostics
- 2009
-
In: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2009-01-1353
-
Journal article (other academic/artistic)abstract
- A heavy-duty diesel engine operating case producing no engine-out smoke was studied using combined simultaneous optical diagnostics. The case was close to a typical low-load modern diesel operating point without EGR. Parallels were drawn to the conceptual model by Dec and results from high-pressure combustion vessels. Optical results revealed that no soot was present in the upstream part of the jet cross-section. Soot was only observed in the recirculation zones close to the bowl perimeter. This indicated very slow soot formation and was explained by a significantly higher air entrainment rate than in Dec's study. The local fuel-air equivalence ratio, Φ, at the lift-off length was estimated to be 40% of the value in Dec's study. The lower Φ in the jet produced a different Φ-T history, explaining the soot results. The increased air entrainment rate was mainly due to smaller nozzle holes and increased TDC density. Furthermore, increased injection pressure was believed to reduce the residence time in the jet, thus reducing the soot formation. OH was detected at the periphery of the jet, upstream of the location where fuel started to react on the jet centerline. The OH region extended relatively far into the jet, further supporting the conclusion of a less fuel-rich jet in the current case. Partially oxidized fuel (POF) was found at the center of the jet, downstream of the lift-off position. This indicated that the temperature needed to start chemical reactions inside the jet had not been obtained at the lift-off position. The high-temperature reaction zone at the periphery thus added heat over a distance before POF was observed on the centerline.
|
|
| 8. |
- Collin, Mattias, et al.
(author)
-
Constitutive expression of the antibacterial CXC chemokine GCP-2/CXCL6 by epithelial cells of the male reproductive tract.
- 2008
-
In: Journal of Reproductive Immunology. - : Elsevier BV. - 1872-7603 .- 0165-0378. ; 79, s. 37-43
-
Journal article (peer-reviewed)abstract
- The reproductive tract is continuously challenged by potential pathogens present in the environment. Therefore, robust host defense mechanisms are essential both for the health of the individual and for fertilization. Antibiotic innate immunity peptides possess broad antimicrobial activity. Recently, we found that the CXC chemokine, granulocyte chemotactic protein (GCP)-2/CXCL6, possesses antibacterial activity. In the present study, we investigated, therefore, the presence of GCP-2/CXCL6 in the human male reproductive system. GCP-2/CXCL6 was detected at 19nM (mean; range: 5-47nM; n=14) in seminal plasma of fertile donors, i.e. at levels more than 100 times higher than those previously reported for the related chemokine IL-8/CXCL8. No GCP-2/CXCL6 could be detected in blood plasma of healthy donors, indicating local production in the male reproductive tract. In vasectomized donors, significantly lower levels of GCP-2/CXCL6 were found (mean: 3nM; range 2-7nM; n=7), demonstrating that the testis and epididymis contribute significantly to the GCP-2/CXCL6 content of seminal plasma. Strong expression of GCP-2/CXCL6 was found in the epithelium of the testis, epididymis and seminal vesicles, while the prostate epithelium showed weak expression, as determined by immunohistochemistry. A biological function is suggested, viz. at concentrations of the order of those found in seminal plasma, GCP-2/CXCL6 has antibacterial activity against the urogenital pathogen Neisseria gonorrhoeae. GCP-2/CXCL6 in seminal plasma may play roles in both host defense of the male urogenital tract and during fertilization.
|
|
| 9. |
- Collin, Mattias, et al.
(author)
-
Contributions to Microbiology : Foreword
- 2009
-
In: Bacterial Sensing and Signaling. - Basel : KARGER. - 1662-291X .- 1420-9519. - 9783805591324 - 9783805591331 ; 16
-
Book chapter (other academic/artistic)
|
|
| 10. |
- Collin, Mattias, et al.
(author)
-
IgG glycan hydrolysis by a bacterial enzyme as a therapy against autoimmune conditions.
- 2008
-
In: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 105:11, s. 4265-4270
-
Journal article (peer-reviewed)abstract
- EndoS from Streptococcus pyogenes efficiently hydrolyzes the functionally important and conserved N-linked glycan of IgG in human blood. Repeated i.v. administration of EndoS in rabbits completely hydrolyzes the glycans of the whole IgG pool, despite the generation of anti-EndoS antibodies. EndoS administration had no apparent effects on the health of the animals. EndoS hydrolysis of the IgG glycan has profound effects on IgG effector functions, such as complement activation and Fc receptor binding, suggesting that the enzyme could be used as an immunomodulatory therapeutic agent against IgG-mediated diseases. We demonstrate here that EndoS indeed has a protective effect in a mouse model of lethal IgG-driven immune (or idiopathic) thrombocytopenic purpura. EndoS pretreatment of pathogenic antibodies inhibits the development of disease, and the enzyme also rescues mice from already established disease when severe thrombocytopenia and s.c. bleeding have developed. These results identify EndoS as a potential therapeutic agent against diseases where pathogenic IgG antibodies are important and further emphasize antibody glycans as possible targets in future therapies against antibody-mediated autoimmune conditions.
|
|
