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Experientia Supplementum (2012) 2021Alternative glycosylation of immunoglobulin G (IgG) affects its effector functions during the immune response. IgG glycosylation is altered in many diseases, but also...
Alternative glycosylation of immunoglobulin G (IgG) affects its effector functions during the immune response. IgG glycosylation is altered in many diseases, but also during a healthy life of an individual. Currently, there is limited knowledge of factors that alter IgG glycosylation in the healthy state and factors involved in specific IgG glycosylation patterns associated with pathophysiology. Genetic background plays an important role, but epigenetic mechanisms also contribute to the alteration of IgG glycosylation patterns in healthy life and in disease. It is known that the expression of many glycosyltransferases is regulated by DNA methylation and by microRNA (miRNA) molecules, but the involvement of other epigenetic mechanisms, such as histone modifications, in the regulation of glycosylation-related genes (glycogenes) is still poorly understood. Recent studies have identified several differentially methylated loci associated with IgG glycosylation, but the mechanisms involved in the formation of specific IgG glycosylation patterns remain poorly understood.
Topics: DNA Methylation; Epigenesis, Genetic; Epigenomics; Glycosylation; Immunoglobulin G
PubMed: 34687014
DOI: 10.1007/978-3-030-76912-3_9 -
BioMed Research International 2021We intended to reformulate an existing platelet-derived wound healing formula to target each phase of the healing wound with the appropriate phase-specific molecules. A...
We intended to reformulate an existing platelet-derived wound healing formula to target each phase of the healing wound with the appropriate phase-specific molecules. A decreased perfusion of the skin, often associated with conditions such as thalassemia, sickle cell disease, diabetes mellitus, and chronic vascular disease, is the most common etiology of cutaneous ulcers and chronic wounds. We had previously shown that a PDWHF topically applied to a chronic nonhealing ulcer of a -thalassemia homozygote stimulated and accelerated closure of the wound. The PDWHF was prepared from a pooled platelet concentrate of a matching blood group, consisting of a combination of platelet -granule-derived factors. Processing of the apheresis-pooled platelets yielded various amounts of proteins (3.36 g/mL ± 0.25 (SD) ( = 10)) by the better lysis buffer method. Immunoglobulin G was found to be the most abundant -granule-secreted protein. Equally broad quantities of the IgG (10.76 ± 12.66% (SD) ( = 10)) and IgG/albumin ratios (0.6 ± 0.4 (SD) ( = 10)) were quantified. We have developed a method using a reformulated lysis buffer followed by size exclusion chromatography and affinity chromatography to extract, identify, quantify, and purify IgG from activated platelets. IgG purification was confirmed by Western blot and flow cytometry. It was thought unlikely that the platelet IgG could be accounted for by adsorption of plasma protein, though the variable quantities could account for diversity in wound healing rates. The IgG could protect the wound even from subclinical infections and functionally advance healing. It may be useful in the management of skin ulcers in the early phase of wound healing.
Topics: Blood Platelets; Chromatography, Affinity; Complex Mixtures; Humans; Immunoglobulin G; Wound Healing
PubMed: 33575328
DOI: 10.1155/2021/4762657 -
Experientia Supplementum (2012) 2021Defining the genetic components that control glycosylation of the human immunoglobulin G (IgG) is an ongoing effort, which has so far been addressed by means of...
Defining the genetic components that control glycosylation of the human immunoglobulin G (IgG) is an ongoing effort, which has so far been addressed by means of heritability, linkage and genome-wide association studies (GWAS). Unlike the synthesis of proteins, N-glycosylation biosynthesis is not a template-driven process, but rather a complex process regulated by both genetic and environmental factors. Current heritability studies have shown that while up to 75% of the variation in levels of some IgG glycan traits can be explained by genetics, some glycan traits are completely defined by environmental influences. Advances in both high-throughput genotyping and glycan quantification methods have enabled genome-wide association studies that are increasingly used to estimate associations of millions of single-nucleotide polymorphisms and glycosylation traits. Using this method, 18 genomic regions have so far been robustly associated with IgG N-glycosylation, discovering associations with genes encoding glycosyltransferases, but also transcription factors, co-factors, membrane transporters and other genes with no apparent role in IgG glycosylation. Further computational analyses have shown that IgG glycosylation is likely to be regulated through the expression of glycosyltransferases, but have also for the first time suggested which transcription factors are involved in the process. Moreover, it was also shown that IgG glycosylation and inflammatory diseases share common underlying causal genetic variants, suggesting that studying genetic regulation of IgG glycosylation helps not only to better understand this complex process but can also contribute to understanding why glycans are changed in disease. However, further studies are needed to unravel whether changes in IgG glycosylation are causing these diseases or the changes in the glycome are caused by the disease.
Topics: Genome-Wide Association Study; Glycosylation; Glycosyltransferases; Humans; Immunoglobulin G; Polysaccharides
PubMed: 34687013
DOI: 10.1007/978-3-030-76912-3_8 -
Immunological Investigations May 2021The loss of tolerance to self-antigens is the unequivocal "red line" of autoimmunity: both development of autoreactive T and B cells and production of polyclonal... (Review)
Review
The loss of tolerance to self-antigens is the unequivocal "red line" of autoimmunity: both development of autoreactive T and B cells and production of polyclonal autoantibodies represent seminal keys to the pathogenesis of protean autoimmune diseases. Most of these autoantibodies are immunoglobulins G (IgG), functionally distinguished in four subclasses named IgG1, IgG2, IgG3, and IgG4, due to structural differences in the hinge and heavy chain constant regions. Different studies analyzed serum levels of IgG subclasses in the course of different disorders, showing that they might have a pathogenic role by regulating interactions among immunoglobulins, Fc-gamma receptors, and complement. To date, the mechanisms promoting different IgG subclasses distribution during the natural history of most autoimmune diseases remain somewhat unclear. Evidence from the medical literature shows that the serum IgG profile is peculiar for many autoimmune diseases, suggesting that different subclasses could be specific for the underlying driving autoantigens. A better knowledge of IgG subsets may probably help to elucidate their pathological task, but also to define their relevance for diagnostic purposes, patients' personalized management, and prognosis assessment.
Topics: Animals; Autoimmune Diseases; Humans; Immunoglobulin G
PubMed: 32522062
DOI: 10.1080/08820139.2020.1775643 -
Expert Review of Proteomics May 2016Glycosylation of immunoglobulin G (IgG) is important for its effector functions and was shown to be related to age, sex and disease status of an individual. Adding... (Review)
Review
INTRODUCTION
Glycosylation of immunoglobulin G (IgG) is important for its effector functions and was shown to be related to age, sex and disease status of an individual. Adding glycomic information to genome-wide association studies (GWAS) and large clinical trials is enabling insight into the functional relevance of changes in glycosylation, as well as molecular mechanisms behind these changes. Large-scale studies require sensitive, robust and affordable high-throughput methodologies for glycosylation analysis, which are currently available in only a limited number of laboratories.
AREAS COVERED
This review focuses on currently used high-throughput approaches for N-glycosylation analysis of IgG, as well as some recent advances in the areas of deglycosylation, trypsin digestion, labeling, purification, derivatization and automation of current workflows. Relevant literature was searched using the PubMed database. Expert commentary: Development, optimization and validation of robust, affordable and simple high-throughput glycosylation analysis methods is essential for discovery and validation of diagnostic and prognostic glycan biomarkers. Although significant advances in glycosylation analysis have been made in recent years, currently used protocols will have to be further optimized to enable subsequent analysis of glycosylation on all levels with the limited initial sample and in the minimal amount of time, which is still a challenging task.
Topics: Chromatography, High Pressure Liquid; Electrophoresis, Capillary; Glycomics; Glycosylation; High-Throughput Screening Assays; Humans; Immunoglobulin G; Mass Spectrometry; Proteomics
PubMed: 27043342
DOI: 10.1080/14789450.2016.1174584 -
The New England Journal of Medicine Feb 2012
Review
Topics: Autoimmune Diseases; Humans; Immunoglobulin G
PubMed: 22316447
DOI: 10.1056/NEJMra1104650 -
Immunology Letters Aug 2010Immune globulin preparations such as intravenous immunoglobulin (IVIG) and monoclonal antibodies are widely used in clinics as effective therapeutic agents for the... (Review)
Review
Immune globulin preparations such as intravenous immunoglobulin (IVIG) and monoclonal antibodies are widely used in clinics as effective therapeutic agents for the treatment of a number of autoimmune diseases, cancer, inflammations and other pathologies. Significant amounts of IgG aggregates have been found in the highly concentrated solutions of therapeutic immune proteins. The IgG self-aggregation that appears especially after prolonged storage increases the immunogenicity of the preparations and also modifies their physical properties, first of all producing the high viscosity. The attractive IgG-IgG interactions pose a significant problem for the clinical usage of the immune proteins. During last decades intensive studies of the IgG self-association were performed. The presence of IgG dimers was demonstrated in pooled preparations. These complexes are the result of idiotype-anti-idiotype interactions. In concentrated solutions of immune globulins and monoclonal antibodies self-associated IgG molecules formed a network, increasing the viscosity. The forces responsible for the IgG association are characteristic of the protein-protein interactions in general. The amino acid residues of the Fab and Fc portions participate in the IgG-IgG contacts. Recently contact residues were modified by the site-directed mutagenesis in order to decrease the formation of the IgG self-aggregates. The mutant IgG antibodies were characterized by enhanced stability as compared with the non-modified antibody molecules. Peptic pFc' fragment and the C(H)3 domain were shown to be capable of interacting with Fc regions, thus preventing IgG aggregation. In perspective both approaches could improve the formulation of immune globulin preparations. Removal of IgG aggregates could be achieved by chromatography on hydroxyapatite.
Topics: Antibodies, Monoclonal; Humans; Immunoglobulin G; Immunoglobulins, Intravenous; Protein Binding
PubMed: 20600325
DOI: 10.1016/j.imlet.2010.06.006 -
Glycobiology Mar 2020Therapeutic monoclonal antibodies (mAbs) are the fastest growing group of drugs with 11 new antibodies or antibody-drug conjugates approved by the Food and Drug... (Review)
Review
Therapeutic monoclonal antibodies (mAbs) are the fastest growing group of drugs with 11 new antibodies or antibody-drug conjugates approved by the Food and Drug Administration in 2018. Many mAbs require effector function for efficacy, including antibody-dependent cell-mediated cytotoxicity triggered following contact of an immunoglobulin G (IgG)-coated particle with activating crystallizable fragment (Fc) γ receptors (FcγRs) expressed by leukocytes. Interactions between IgG1 and the FcγRs require post-translational modification of the Fc with an asparagine-linked carbohydrate (N-glycan). Though the structure of IgG1 Fc and the role of Fc N-glycan composition on disease were known for decades, the underlying mechanism of how the N-glycan affected FcγR binding was not defined until recently. This review will describe the current understanding of how N-glycosylation impacts the structure and function of the IgG1 Fc and describe new techniques that are poised to provide the next critical breakthroughs.
Topics: Animals; Glycosylation; Humans; Immunoglobulin G; Polysaccharides
PubMed: 31822882
DOI: 10.1093/glycob/cwz068 -
Analytical and Bioanalytical Chemistry Jan 2015The size, heterogeneity, and biological production process of protein therapeutics like monoclonal antibodies create unique challenges for their analysis and regulation... (Review)
Review
The size, heterogeneity, and biological production process of protein therapeutics like monoclonal antibodies create unique challenges for their analysis and regulation compared with small molecules. Complete structural characterization of a molecule 1000-fold heavier than aspirin is no small feat. Biological post-translational modifications such as glycosylation further complicate their characterization and regulation. Even approved protein therapeutics are known to contain multiple structural variants in differing amounts. Structural modification occurs during production and storage as well as within patients after administration. Thus, the goals of manufacturers and regulators are to control and characterize this heterogeneity, not take on the impossible task of eliminating it. The aim of this review is to describe the structural heterogeneities known to occur with immunoglobulin G (IgG), note current detection and analytical strategies, establish their causes, and define their potential effects on the ultimate safety, purity, and potency of antibody therapeutics when known.
Topics: Animals; Glycosylation; Humans; Immunoglobulin G; Protein Processing, Post-Translational
PubMed: 25200070
DOI: 10.1007/s00216-014-8108-x -
Glycobiology Mar 2020IgG glycosylation is currently at the forefront of both immunology and glycobiology, likely due in part to the widespread and growing use of antibodies as drugs. For... (Review)
Review
IgG glycosylation is currently at the forefront of both immunology and glycobiology, likely due in part to the widespread and growing use of antibodies as drugs. For over four decades, it has been recognized that the conserved N-linked glycan on asparagine 297 found within the second Ig domain of the heavy chain (CH2) that helps to comprise Fc region of IgG plays a special role in IgG structure and function. Changes in galactosylation, fucosylation and sialylation are now well-established factors, which drive differential IgG function, ranging from inhibitory/anti-inflammatory to activating complement and promoting antibody-dependent cellular cytotoxicity. Thus, if we are to truly understand how to design and deploy antibody-based drugs with maximal efficacy and evaluate proper vaccine responses from a protective and functional perspective, a deep understanding of IgG glycosylation is essential. This article is intended to provide a comprehensive review of the IgG glycosylation field and the impact glycans have on IgG function, beginning with the earliest findings over 40 years ago, in order to provide a robust foundation for moving forward.
Topics: Animals; Glycosylation; History, 20th Century; History, 21st Century; Humans; Immunoglobulin G; Polysaccharides
PubMed: 31504525
DOI: 10.1093/glycob/cwz065