Promjena glikozilacije immunoglobulina G tijekom starenja

In this thesis, glycosylation of immunoglobulin G (IgG) was examined in 5818 individuals ranging in age from 16 to 100 years from five different populations – four European populations and a Han Chinese population by using ultra performance liquid chromatography (UPLC) in order to provide a comprehensive overview of changes in IgG glycosylation through lifetime. The results demonstrated that glycan profiles change in a similar way through lifetime across all examined populations. Nearly all IgG glycans were significantly associated with age. Sex differences in age-related changes in IgG glycosylation were observed. The combination of several IgG glycans was able to explain from 30 to 58% of variance in chronological age, with the remaining variance in the glycans attributed to physiological parameters. Analysis of IgG glycosylation in nearly 600 mice from the Collaborative Cross cohort ranging in age from 20 to 80 weeks showed that, generally, only the level of IgG glycan with alpha-1,3-galactose changed with age.U ovom doktorskom radu analizirana je glikozilacija imunoglobulina G (IgG) kod 5818 osoba starosti od 16 do 100 godina iz pet različitih populacija – četiri europske populacije i populacije Han Kineza, koristeći tekućinsku kromatografiju vrlo visoke djelotvornosti (UPLC), kako bi se pružio detaljan pregled promjena u glikozilaciji IgG-a tijekom starenja. Rezultati su pokazali da se glikanski profili tijekom starenja mijenjaju na sličan način u svim istraživanim populacijama. Gotovo svi IgG glikani pokazali su se povezanima s dobi. Uočene su razlike između spolova u promjenama koje se događaju s glikozilacijom IgG-a tijekom starenja. Kombinacijom nekoliko IgG glikana bilo je moguće objasniti od 30 do 58% varijacije u kronološkoj dobi, a ostatak varijacije u glikanima pripisan je fiziološkim parametrima. Analiza glikozilacije IgG-a kod gotovo 600 miševa starosti od 20 do 80 tjedana iz Collaborative Cross populacije miševa pokazala je da se, sveobuhvatno gledajući, samo razina IgG glikana koji sadrži alfa-1,3 vezanu galaktozu promijenila s dobi

Promjena glikozilacije immunoglobulina G tijekom starenja

In this thesis, glycosylation of immunoglobulin G (IgG) was examined in 5818 individuals ranging in age from 16 to 100 years from five different populations – four European populations and a Han Chinese population by using ultra performance liquid chromatography (UPLC) in order to provide a comprehensive overview of changes in IgG glycosylation through lifetime. The results demonstrated that glycan profiles change in a similar way through lifetime across all examined populations. Nearly all IgG glycans were significantly associated with age. Sex differences in age-related changes in IgG glycosylation were observed. The combination of several IgG glycans was able to explain from 30 to 58% of variance in chronological age, with the remaining variance in the glycans attributed to physiological parameters. Analysis of IgG glycosylation in nearly 600 mice from the Collaborative Cross cohort ranging in age from 20 to 80 weeks showed that, generally, only the level of IgG glycan with alpha-1,3-galactose changed with age.U ovom doktorskom radu analizirana je glikozilacija imunoglobulina G (IgG) kod 5818 osoba starosti od 16 do 100 godina iz pet različitih populacija – četiri europske populacije i populacije Han Kineza, koristeći tekućinsku kromatografiju vrlo visoke djelotvornosti (UPLC), kako bi se pružio detaljan pregled promjena u glikozilaciji IgG-a tijekom starenja. Rezultati su pokazali da se glikanski profili tijekom starenja mijenjaju na sličan način u svim istraživanim populacijama. Gotovo svi IgG glikani pokazali su se povezanima s dobi. Uočene su razlike između spolova u promjenama koje se događaju s glikozilacijom IgG-a tijekom starenja. Kombinacijom nekoliko IgG glikana bilo je moguće objasniti od 30 do 58% varijacije u kronološkoj dobi, a ostatak varijacije u glikanima pripisan je fiziološkim parametrima. Analiza glikozilacije IgG-a kod gotovo 600 miševa starosti od 20 do 80 tjedana iz Collaborative Cross populacije miševa pokazala je da se, sveobuhvatno gledajući, samo razina IgG glikana koji sadrži alfa-1,3 vezanu galaktozu promijenila s dobi

Promjena glikozilacije immunoglobulina G tijekom starenja

In this thesis, glycosylation of immunoglobulin G (IgG) was examined in 5818 individuals ranging in age from 16 to 100 years from five different populations – four European populations and a Han Chinese population by using ultra performance liquid chromatography (UPLC) in order to provide a comprehensive overview of changes in IgG glycosylation through lifetime. The results demonstrated that glycan profiles change in a similar way through lifetime across all examined populations. Nearly all IgG glycans were significantly associated with age. Sex differences in age-related changes in IgG glycosylation were observed. The combination of several IgG glycans was able to explain from 30 to 58% of variance in chronological age, with the remaining variance in the glycans attributed to physiological parameters. Analysis of IgG glycosylation in nearly 600 mice from the Collaborative Cross cohort ranging in age from 20 to 80 weeks showed that, generally, only the level of IgG glycan with alpha-1,3-galactose changed with age.U ovom doktorskom radu analizirana je glikozilacija imunoglobulina G (IgG) kod 5818 osoba starosti od 16 do 100 godina iz pet različitih populacija – četiri europske populacije i populacije Han Kineza, koristeći tekućinsku kromatografiju vrlo visoke djelotvornosti (UPLC), kako bi se pružio detaljan pregled promjena u glikozilaciji IgG-a tijekom starenja. Rezultati su pokazali da se glikanski profili tijekom starenja mijenjaju na sličan način u svim istraživanim populacijama. Gotovo svi IgG glikani pokazali su se povezanima s dobi. Uočene su razlike između spolova u promjenama koje se događaju s glikozilacijom IgG-a tijekom starenja. Kombinacijom nekoliko IgG glikana bilo je moguće objasniti od 30 do 58% varijacije u kronološkoj dobi, a ostatak varijacije u glikanima pripisan je fiziološkim parametrima. Analiza glikozilacije IgG-a kod gotovo 600 miševa starosti od 20 do 80 tjedana iz Collaborative Cross populacije miševa pokazala je da se, sveobuhvatno gledajući, samo razina IgG glikana koji sadrži alfa-1,3 vezanu galaktozu promijenila s dobi

Minimal B Cell Extrinsic IgG Glycan Modifications of Pro- and Anti-Inflammatory IgG Preparations in vivo

Select residues in the biantennary sugar moiety attached to the fragment crystallizable of immunoglobulin G (IgG) antibodies can modulate IgG effector functions. Thus, afucosylated IgG glycovariants have enhanced cytotoxic activity, whereas IgG glycovariants rich in terminal sialic acid residues can trigger anti-inflammatory effects. More recent evidence suggests that terminal α2,6 linked sialic acids can be attached to antibodies post IgG secretion. These findings raise concerns for the use of therapeutic antibodies as they may change their glycosylation status in the patient and hence affect their activity. To investigate to what extent B cell extrinsic sialylation processes modify therapeutic IgG preparations in vivo, we analyzed changes in human intravenous IgG (IVIg) sialylation upon injection in mice deficient in B cells or in mice lacking the sialyltransferase 1, which catalyzes the addition of α2,6 linked sialic acid residues. By performing a time course of IgG glycan analysis with HILIC-UPLC-FLR (plus MS) and xCGE-LIF our study suggests that therapeutic IgG glycosylation is stable upon injection in vivo. Only a very small fraction of IgG molecules acquired sialic acid structures predominantly in the Fab- but not the Fc-portion upon injection in vivo, suggesting that therapeutic antibody glycosylation will remain stable upon injection in vivo

The Association Between Glycosylation of Immunoglobulin G and Hypertension:A Multiple Ethnic Cross-Sectional Study

More than half of all known proteins, and almost all membrane and extra-cellular proteins have oligosaccharide structures or glycans attached to them. Defects in glycosylation pathways are directly involved in at least 30 severe human diseases. A multiple center cross-sectional study (China, Croatia, and Scotland) was carried out to investigate the possible association between hypertension and IgG glycosylation. A hydrophilic interaction chromatography of fluorescently labeled glycans was used to analyze N-glycans attached to IgG in plasma samples from a total of 4757 individuals of Chinese Han, Croatian, and Scottish ethnicity. Five glycans (IgG with digalactosylated glycans) significantly differed in participants with prehypertension or hypertension compared to those with normal blood pressure, while additional 17 glycan traits were only significantly differed in participants with hypertension compared to those of normal blood pressure. These glycans were also significant correlated with systolic blood pressure (SBP) or diastolic blood pressure (DBP). The present study demonstrated for the 1st time an association between hypertension and IgG glycome composition. These findings suggest that the individual variation in N-glycosylation of IgG contributes to pathogenesis of hypertension, presumably via its effect on pro-and/or anti-inflammatory pathways. © Copyright 2016 Wolters Kluwer Health, Inc. All rights reserved

Association of systemic lupus erythematosus associates with decreased immunosuppressive potential of the IgG glycome

Objective: Glycans attached to the Fc portion of IgG are important modulators of IgG effector functions. Interindividual differences in IgG glycome composition are large and they associate strongly with different inflammatory and autoimmune diseases. IKZF1, HLA–DQ2A/B, and BACH2 genetic loci that affect IgG glycome composition show pleiotropy with systemic lupus erythematosus (SLE), indicating a potentially causative role of aberrant IgG glycosylation in SLE. We undertook this large multicenter case–control study to determine whether SLE is associated with altered IgG glycosylation. Methods: Using ultra-performance liquid chromatography analysis of released glycans, we analyzed the composition of the IgG glycome in 261 SLE patients and 247 matched controls of Latin American Mestizo origin (the discovery cohort) and in 2 independent replication cohorts of different ethnicity (108 SLE patients and 193 controls from Trinidad, and 106 SLE patients and 105 controls from China). Results: Multiple statistically significant differences in IgG glycome composition were observed between patients and controls. The most significant changes included decreased galactosylation and sialylation of IgG (which regulate proinflammatory and antiinflammatory actions of IgG) as well as decreased core fucose and increased bisecting N-acetylglucosamine (which affect antibody-dependent cell-mediated cytotoxicity). Conclusion: The IgG glycome in SLE patients is significantly altered in a way that decreases immunosuppressive action of circulating immunoglobulins. The magnitude of observed changes is associated with the intensity of the disease, indicating that aberrant IgG glycome composition or changes in IgG glycosylation may be an important molecular mechanism in SLE

Glycosylation of immunoglobulin G is regulated by a large network of genes pleiotropic with inflammatory diseases

Effector functions of immunoglobulin G (IgG) are regulated by the composition of a glycan moiety, thus affecting activity of the immune system. Aberrant glycosylation of IgG has been observed in many diseases, but little is understood about the underlying mechanisms. We performed a genome-wide association study of IgG N-glycosylation (N = 8090) and, using a data-driven network approach, suggested how associated loci form a functional network. We confirmed in vitro that knockdown of IKZF1 decreases the expression of fucosyltransferase FUT8, resulting in increased levels of fucosylated glycans, and suggest that RUNX1 and RUNX3, together with SMARCB1, regulate expression of glycosyltransferase MGAT3. We also show that variants affecting the expression of genes involved in the regulation of glycoenzymes colocalize with variants affecting risk for inflammatory diseases. This study provides new evidence that variation in key transcription factors coupled with regulatory variation in glycogenes modifies IgG glycosylation and has influence on inflammatory diseases

IgG glycosylation and DNA methylation are interconnected with smoking

Background: Glycosylation is one of the most common post-translation modifications with large influences on protein structure and function. The effector function of immunoglobulin G (IgG) alters between pro- and anti-inflammatory, based on its glycosylation. IgG glycan synthesis is highly complex and dynamic. Methods: With the use of two different analytical methods for assessing IgG glycosylation, we aim to elucidate the link between DNA methylation and glycosylation of IgG by means of epigenome-wide association studies. In total, 3000 individuals from 4 cohorts were analyzed. Results: The overlap of the results from the two glycan measurement panels yielded DNA methylation of 7 CpG-sites on 5 genomic locations to be associated with IgG glycosylation: cg25189904 (chr.1, GNG12); cg05951221, cg21566642 and cg01940273 (chr.2, ALPPL2); cg05575921 (chr.5, AHRR); cg06126421 (6p21.33); and cg03636183 (chr.19, F2RL3). Mediation analyses with respect to smoking revealed that the effect of smoking on IgG glycosylation may be at least partially mediated via DNA methylation levels at these 7 CpG-sites. Conclusion: Our results suggest the presence of an indirect link between DNA methylation and IgG glycosylation that may in part capture environmental exposures. General significance: An epigenome-wide analysis conducted in four population-based cohorts revealed an association between DNA methylation and IgG glycosylation patterns. Presumably, DNA methylation mediates the effect of smoking on IgG glycosylation

Inflammatory bowel disease associates with proinflammatory potential of the immunoglobulin g glycome

BACKGROUND: Glycobiology is an underexplored research area in inflammatory bowel disease (IBD), and glycans are relevant to many etiological mechanisms described in IBD. Alterations in N-glycans attached to the immunoglobulin G (IgG) Fc fragment can affect molecular structure and immunological function. Recent genome-wide association studies reveal pleiotropy between IBD and IgG glycosylation. This study aims to explore IgG glycan changes in ulcerative colitis (UC) and Crohn's disease (CD). METHODS: IgG glycome composition in patients with UC (n = 507), CD (n = 287), and controls (n = 320) was analyzed by ultra performance liquid chromatography. RESULTS: Statistically significant differences in IgG glycome composition between patients with UC or CD, compared with controls, were observed. Both UC and CD were associated with significantly decreased IgG galactosylation (digalactosylation, UC: odds ratio [OR] = 0.71; 95% confidence interval [CI], 0.5–0.9; P = 0.01; CD: OR = 0.41; CI, 0.3–0.6; P = 1.4 × 10(−9)) and significant decrease in the proportion of sialylated structures in CD (OR = 0.46, CI, 0.3–0.6, P = 8.4 × 10(−8)). Logistic regression models incorporating measured IgG glycan traits were able to distinguish UC and CD from controls (UC: P = 2.13 × 10(−6) and CD: P = 2.20 × 10(−16)), with receiver–operator characteristic curves demonstrating better performance of the CD model (area under curve [AUC] = 0.77) over the UC model (AUC = 0.72) (P = 0.026). The ratio of the presence to absence of bisecting GlcNAc in monogalactosylated structures was increased in patients with UC undergoing colectomy compared with no colectomy (FDR-adjusted, P = 0.05). CONCLUSIONS: The observed differences indicate significantly increased inflammatory potential of IgG in IBD. Changes in IgG glycosylation may contribute to IBD pathogenesis and could alter monoclonal antibody therapeutic efficacy. IgG glycan profiles have translational potential as IBD biomarkers

Fc-Linked IgG N-Glycosylation in FcγR Knock-Out Mice

Immunoglobulin G (IgG) is the most abundant immunoglobulin isotype in the blood and is involved in the pathogenesis and progression of various diseases. Glycosylation of the IgG fragment crystallizable (Fc) region is shown to vary in different physiological and pathological states. Fc N-glycan composition can alter the effector functions of IgG by modulating its affinity for ligands, such as Fcγ receptors (FcγRs). However, it is not known whether IgG glycosylation is affected by the available repertoire of FcγRs, and if the Fc-linked N-glycome can compensate for modulation of the IgG–FcγR interaction. To explore this, we examined the subclass-specific Fc IgG glycoprofiles of healthy male and female FcγR knock-out mice on C57BL/6 and BALB/c backgrounds. We observed slight changes in IgG Fc N-glycan profiles in different knock-outs; however, it seems that the strain background and sex have a stronger effect on N-glycosylation of IgG Fc regions than the FcγR repertoire