| 1. |
- Ellinor, Patrick T., et al.
(författare)
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Meta-analysis identifies six new susceptibility loci for atrial fibrillation
- 2012
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 44:6, s. 88-670
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Tidskriftsartikel (refereegranskat)abstract
- Atrial fibrillation is a highly prevalent arrhythmia and a major risk factor for stroke, heart failure and death(1). We conducted a genome-wide association study (GWAS) in individuals of European ancestry, including 6,707 with and 52,426 without atrial fibrillation. Six new atrial fibrillation susceptibility loci were identified and replicated in an additional sample of individuals of European ancestry, including 5,381 subjects with and 10,030 subjects without atrial fibrillation (P < 5 x 10(-8)). Four of the loci identified in Europeans were further replicated in silico in a GWAS of Japanese individuals, including 843 individuals with and 3,350 individuals without atrial fibrillation. The identified loci implicate candidate genes that encode transcription factors related to cardiopulmonary development, cardiac-expressed ion channels and cell signaling molecules.
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| 2. |
- Garbe, Julia, et al.
(författare)
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EndoE from Enterococcus faecalis Hydrolyzes the Glycans of the Biofilm Inhibiting Protein Lactoferrin and Mediates Growth.
- 2014
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- Glycosidases are widespread among bacteria. The opportunistic human pathogen Enterococcus faecalis encodes several putative glycosidases but little is known about their functions. The identified endo-β-N-acetylglucosaminidase EndoE has activity on the N-linked glycans of the human immunoglobulin G (IgG). In this report we identified the human glycoprotein lactoferrin (hLF) as a new substrate for EndoE. Hydrolysis of the N-glycans from hLF was investigated using lectin blot, UHPLC and mass spectrometry, showing that EndoE releases major glycoforms from this protein. hLF was shown to inhibit biofilm formation of E. faecalis in vitro. Glycans of hLF influence the binding to E. faecalis, and EndoE-hydrolyzed hLF inhibits biofilm formation to lesser extent than intact hLF indicating that EndoE prevents the inhibition of biofilm. In addition, hLF binds to a surface-associated enolase of E. faecalis. Culture experiments showed that the activity of EndoE enables E. faecalis to use the glycans derived from lactoferrin as a carbon source indicating that they could be used as nutrients in vivo when no other preferred carbon source is available. This report adds important information about the enzymatic activity of EndoE from the commensal and opportunist E. faecalis. The activity on the human glycoprotein hLF, and the functional consequences with reduced inhibition of biofilm formation highlights both innate immunity functions of hLF and a bacterial mechanism to evade this innate immunity function. Taken together, our results underline the importance of glycans in the interplay between bacteria and the human host, with possible implications for both commensalism and opportunism.
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| 3. |
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| 4. |
- Mohanty, Tirthankar, et al.
(författare)
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A novel mechanism for NETosis provides antimicrobial defense at the oral mucosa.
- 2015
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 126:18, s. 2128-2137
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophils are essential for host defense at the oral mucosa and neutropenia or functional neutrophil defects lead to disordered oral homeostasis. We found that neutrophils from the oral mucosa harvested from morning saliva had undergone NETosis in vivo. The NETosis was mediated through intracellular signals elicited by binding of sialyl lewis(X) present on salival mucins to L-selectin on neutrophils. This led to rapid loss of nuclear membrane and intracellular release of granule proteins with subsequent NET release independent of elastase and NADPH-oxidase activation. The saliva-induced NETs were more DNase-resistant and had higher capacity to bind and kill bacteria than NETs induced by bacteria or by PMA. Furthermore, saliva/sialyl lewis(X) mediated signaling enhanced intracellular killing of bacteria by neutrophils. Saliva from patients with aphthous ulcers and Behçet's disease prone to oral ulcers, failed to induce NETosis, but for different reasons, demonstrating that disordered homeostasis in the oral cavity may result in deficient saliva-mediated NETosis.
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| 5. |
- Pipi, Elena, et al.
(författare)
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Multiple modes of action mediate the therapeutic effect of IVIg in experimental epidermolysis bullosa acquisita
- 2022
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Ingår i: Journal of Investigative Dermatology. - : Elsevier BV. - 1523-1747 .- 0022-202X. ; 142:6, s. 8-1564
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Tidskriftsartikel (refereegranskat)abstract
- Substitution of IgG in antibody deficiency or application of high-dose intravenous IgG (IVIg) in patients with autoimmunity are well-established treatments. Data on the mode of action of IVIg are, however, controversial and may differ for distinct diseases. In this study, we investigated the impact and molecular mechanism of high-dose IgG treatment in murine autoantibody-induced skin inflammation, namely, epidermolysis bullosa acquisita (EBA). EBA is caused by antibodies directed against type VII collagen (COL7) and is mediated by complement activation, release of reactive oxygen species, and proteases by myeloid cells. In murine experimental EBA the disease can be induced by injection of anti-COL7 IgG. Here, we substantiate that treatment with high-dose IgG improves clinical disease manifestation. Mechanistically, high-dose IgG reduced the amount of anti-COL7 in skin and sera, which is indicative for an FcRn-dependent mode-of-action. Furthermore, in a non-receptor-mediated fashion, high-dose IgG showed antioxidative properties by scavenging extracellular reactive oxygen species. High-dose IgG also impaired complement activation and served as substrate for proteases, both key events during EBA pathogenesis. Collectively, the non-receptor-mediated anti-inflammatory properties of high-dose IgG may explain the therapeutic benefit of IVIg treatment in skin autoimmunity.
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| 6. |
- Shadnezhad, Azadeh, et al.
(författare)
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EndoSd: an IgG glycan hydrolyzing enzyme in Streptococcus dysgalactiae subspecies dysgalactiae
- 2016
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Ingår i: Future Microbiology. - : Future Medicine Ltd. - 1746-0913 .- 1746-0921. ; 11:6, s. 721-736
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The aim of this study was to identify and characterize EndoS-like enzymes in Streptococcus dysgalactiae subspecies dysgalactiae (SDSD). Materials & methods: PCR, DNA sequencing, recombinant protein expression, lectin blot, ultra high performance liquid chromatography analysis and a chitinase assay were used to identify ndoS-like genes and characterize EndoSd. Results: EndoSd were found in four SDSD strains. EndoSd hydrolyzes the chitobiose core of the glycan on IgG. The amino acid sequence of EndoSd is 70% identical to EndoS in S. pyogenes, but it has a unique C-terminal sequence. EndoSd secretion is influenced by the carbohydrate composition of the growth medium. Conclusion: Our findings indicate that IgG glycan hydrolyzing activity is present in SDSD, and that the activity can be attributed to the here identified enzyme EndoSd.
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| 7. |
- Sjögren, Jonathan, et al.
(författare)
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Bacterial glycosidases in pathogenesis and glycoengineering.
- 2014
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Ingår i: Future Microbiology. - : Future Medicine Ltd. - 1746-0921 .- 1746-0913. ; 9:9, s. 1039-1051
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Forskningsöversikt (refereegranskat)abstract
- ABSTRACT Glycosylation is a common post-translational protein modification and many key proteins of the immune system are glycosylated. As the true experts of our immune system, pathogenic bacteria produce enzymes that can modify the carbohydrates (glycans) of the defense mechanisms in order to favor bacterial survival and persistence. At the intersection between bacterial pathogenesis and glycobiology, there is an increased interest in studying the bacterial enzymes that modify the protein glycosylation of their colonized or infected hosts. This is of great importance in order to fully understand bacterial pathogenesis, but it also presents itself as a valuable source for glycoengineering and glycoanalysis tools. This article highlights the role of bacterial glycosidases during infections, introduces the use of such enzymes as glycoengineering tools and discusses the potential of further studies in this emerging field.
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| 8. |
- Sjögren, Jonathan
(författare)
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Bacterial modulation of host glycosylation - in infection, biotechnology, and therapy
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A majority of the proteins of the immune system are glycosylated and the glycans of IgG are essential for its functionality. Bacteria display enzymes that modulate the glycans of the immune system to weaken the host defense and favor bacterial survival. In this thesis we aimed at exploring bacterial modulation of host glycosylation in infection and to evaluate the usefulness of bacterial enzymes in biotechnology and for therapeutic use. The role of IgG endoglycosidase EndoS in streptococcal virulence was evaluated in a murine model of invasive infection and we found significant contribution when heterologously expressed. We also discovered and characterized EndoS2, a novel enzyme specific and conserved in serotype M49 of streptococci, with enzymatic activity on the glycans of IgG and α1-acid glycoprotein. Enterococcal pathogenesis was studied, and we found that the endoglycosidase EndoE cleaved glycans of lactoferrin to reduce the antibacterial functions and to support bacterial growth. A glycoform specificity difference between EndoS and EndoS2 was observed, and we suggested a method for quantification of high-mannose glycans on therapeutic antibodies, a key quality attribute. Finally, we explored the importance of Fc glycosylation of IgE and showed that EndoS cleaved glycans of this immunoglobulin causing a reduction of the immune cell activation in vivo, a potential new therapeutic strategy for severe IgE mediated allergies. In this thesis we demonstrate that glycans are an integral part of the immune system, and that the study of bacterial effectors of glycosylation paves the way for a deeper understanding of infections, for novel tools supporting the biotech arena, and for new therapeutic strategies.
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| 9. |
- Sjögren, Jonathan, et al.
(författare)
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EndoS and EndoS2 hydrolyze Fc-glycans on therapeutic antibodies with different glycoform selectivity and can be used for rapid quantification of high-mannose glycans.
- 2015
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 25:10, s. 1053-1063
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Tidskriftsartikel (refereegranskat)abstract
- Enzymes that affect glycoproteins of the human immune system, and thereby modulate defense responses, are abundant among bacterial pathogens. Two endoglycosidases from the human pathogen Streptococcus pyogenes, EndoS and EndoS2, have recently been shown to hydrolyze N-linked glycans of human IgG. However, detailed characterization and comparison of the hydrolyzing activities have not been performed. In the present study we set out to characterize the enzymes by comparing the activities of EndoS and EndoS2 on a selection of therapeutic monoclonal antibodies (mAbs), cetuximab, adalimumab, panitumumab, and denosumab. By analyzing the glycans hydrolyzed by EndoS and EndoS2 from the antibodies using MALDI-TOF, we found that both enzymes cleaved complex glycans, and that EndoS2 hydrolyzed hybrid and oligomannose structures to a greater extent compared to EndoS. A comparison of UHPLC profiles of the glycan pool of cetuximab hydrolyzed with EndoS and EndoS2 showed that EndoS2 hydrolyzed hybrid and oligomannose glycans whereas these peaks were missing in the EndoS chromatogram. We utilized this difference in glycoform selectivity and developed a liquid chromatography separation method to quantify high-mannose content in the Fc fragments of the selected mAbs. We conclude that EndoS and EndoS2 hydrolyze different glycoforms from the Fc-glycosylation site on therapeutic mAbs, and that this can be used for rapid quantification of high-mannose content.
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| 10. |
- Sjögren, Jonathan, et al.
(författare)
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EndoS2 is a unique and conserved enzyme of serotype M49 group A Streptococcus that hydrolyses N-linked glycans on IgG and α1-acid glycoprotein
- 2013
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Ingår i: Biochemical Journal. - 0264-6021. ; 455:1, s. 107-118
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Tidskriftsartikel (refereegranskat)abstract
- Many bacteria have evolved ways to interact with glycosylation functions of the immune system of their hosts. Streptococcus pyogenes [GAS (group A Streptococcus)] secretes the enzyme EndoS that cleaves glycans on human IgG and impairs the effector functions of the antibody. The ndoS gene, encoding EndoS, has, until now, been thought to be conserved throughout the serotypes. However, in the present study, we identify EndoS2, an endoglycosidase in serotype M49 GAS strains. We characterized EndoS2 and the corresponding ndoS2 gene using sequencing, bioinformatics, phylogenetic analysis, recombinant expression and LC–MS analysis of glycosidic activity. This revealed that EndoS2 is present exclusively, and highly conserved, in serotype M49 of GAS and is only 37% identical with EndoS. EndoS2 showed endo-β-N-acetylglucosaminidase activity on all N-linked glycans of IgG and on biantennary and sialylated glycans of AGP (α1-acid glycoprotein). The enzyme was found to act only on native IgG and AGP and to be specific for free biantennary glycans with or without terminal sialylation. GAS M49 expression of EndoS2 was monitored in relation to carbohydrates present in the culture medium and was linked to the presence of sucrose. We conclude that EndoS2 is a unique endoglycosidase in serotype M49 and differs from EndoS of other GAS strains by targeting both IgG and AGP. EndoS2 expands the repertoire of GAS effectors that modify key glycosylated molecules of host defence.
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| 11. |
- Sjögren, Jonathan, et al.
(författare)
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Study of the IgG endoglycosidase EndoS in group A streptococcal phagocyte resistance and virulence
- 2011
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Ingår i: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: The secreted enzyme EndoS, an endoglycosidase from Streptococcus pyogenes, hydrolyzes the N-linked glycan of the constant region of immunoglobulin G (IgG) heavy chain and renders the antibody unable to interact with Fc receptors and elicit effector functions. In this study we couple targeted allelic replacement mutagenesis and heterologous expression to elucidate the contribution of EndoS to group A Streptococcus (GAS) phagocyte resistance and pathogenicity in vitro and in vivo. Results: Knocking out the EndoS gene in GAS M1T1 background revealed no significant differences in bacterial survival in immune cell killing assays or in a systemic mouse model of infection. However, exogenous addition and heterologous expression of EndoS was found to increase GAS resistance to killing by neutrophils and monocytes in vitro. Additionally, heterologous expression of EndoS in M49 GAS increased mouse virulence in vivo. Conclusions: We conclude that in a highly virulent M1T1 background, EndoS has no significant impact on GAS phagocyte resistance and pathogenicity. However, local accumulation or high levels of expression of EndoS in certain GAS strains may contribute to virulence.
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| 12. |
- Zeggini, Eleftheria, et al.
(författare)
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Meta-analysis of genome-wide association data and large-scale replication identifies additional susceptibility loci for type 2 diabetes
- 2008
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 40:5, s. 638-645
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Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association (GWA) studies have identified multiple loci at which common variants modestly but reproducibly influence risk of type 2 diabetes (T2D)(1-11). Established associations to common and rare variants explain only a small proportion of the heritability of T2D. As previously published analyses had limited power to identify variants with modest effects, we carried out meta-analysis of three T2D GWA scans comprising 10,128 individuals of European descent and similar to 2.2 million SNPs (directly genotyped and imputed), followed by replication testing in an independent sample with an effective sample size of up to 53,975. We detected at least six previously unknown loci with robust evidence for association, including the JAZF1 (P=5.0 x 10(-14)), CDC123-CAMK1D (P=1.2 x 10(-10)), TSPAN8-LGR5 (P=1.1 x 10(-9)), THADA (P=1.1 x 10(-9)), ADAMTS9 (P=1.2 x 10(-8)) and NOTCH2 (P=4.1 x 10(-8)) gene regions. Our results illustrate the value of large discovery and follow-up samples for gaining further insights into the inherited basis of T2D.
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