Publications

Antibodies play a critical role in linking the adaptive immune response to the innate immune system. In humans, antibodies are categorized into five classes, IgG, IgM, IgA, IgE, and IgD, based on constant region sequence, structure, and tropism. In serum, IgG is the most abundant antibody, comprising 75% of antibodies in circulation, followed by IgA at 15%, IgM at 10%, and IgD and IgE are the least abundant. All human antibody classes are post-translationally modified by sugars through glycosylation. The resulting glycans take on many divergent structures and can be attached in N-linked and O-linked glycans, and are distinct by antibody class, and by position on each antibody. Many of these glycan structures on antibodies are capped by sialic acid. It is well established that the composition of the N-linked glycans on IgG exert a profound influence on its effector functions. However, recent studies have described the influence of glycans, particularly sialic acid for other antibody classes. Here, we discuss the role of glycosylation, with a focus on terminal sialylation, in the biology and function across all antibody classes. Sialylation has been shown to influence not only IgG, but IgE, IgM, and IgA biology, making it an important and unappreciated regulator of antibody function.

Generation of high-affinity IgG is essential for defense against infections and cancer, which is the intended consequence of many vaccines, but can cause autoimmune and inflammatory diseases when inappropriately directed against self. The interplay of T follicular helper (T_FH) cells and T follicular regulatory (T_FR) cells is critical for the production of high-affinity IgG of a specific subclass. In this study, we sought to improve Ag-specific IgG responses with two interventions intended to transiently diminish T_FR cell influence. First, adult mice were administered an antibiotic mixture (ABX) for an extended period to deplete the immunoregulatory intestinal microbiota. This intriguingly increased T_FH cell and reduced T_FR cell numbers. 2,4,6-Trinitrophenyl hapten conjugated to keyhole limpet hemocyanin immunization resulted in higher affinity 2,4,6-trinitrophenyl hapten–specific IgG1 in ABX mice compared with controls. In a model of IgG-driven inflammatory nephritis, ABX mice had significantly worse nephritis accompanied by higher affinity Ag-specific IgG2b and enriched T_FH cells compared with controls. Second, we sought to functionally manipulate T_FH and T_FR cells, which both express the checkpoint inhibitory molecule, PD-1, by administration of anti–PD-1 during immunization. This intervention enhanced the affinity of Ag-specific IgG of the appropriate subclass and increased in T_FH cells following 2,4,6-trinitrophenyl hapten conjugated to keyhole limpet hemocyanin immunization and nephritis induction. These results suggest that altering T_FH and T_FR cell ratios during immunization is an appealing strategy to qualitatively improve Ag- and subclass-specific IgG responses.

Approximately one-third of the world’s population suffers from allergies¹. Allergen exposure crosslinks mast cell- and basophil-bound immunoglobulin E (IgE), triggering the release of inflammatory mediators, including histamine². Although IgE is absolutely required for allergies, it is not understood why total and allergen-specific IgE concentrations do not reproducibly correlate with allergic disease^3-5. It is well-established that glycosylation of IgG dictates its effector function and has disease-specific patterns. However, whether IgE glycans differ in disease states or impact biological activity is completely unknown⁶. We therefore unbiasedly examined glycosylation patterns of total IgE from peanut-allergic and non-atopic individuals. This revealed an increase in sialic acid content on total IgE from peanut-allergic individuals compared to non-atopic subjects. Sialic acid removal from IgE attenuated effector cell degranulation and anaphylaxis in multiple functional models of allergic disease. Therapeutic interventions, including sialic acid removal from cell-bound IgE with a FcεRI targeted-neuraminidase, or administration of asialylated IgE, markedly reduced anaphylaxis. Together, these results establish IgE glycosylation, and specifically sialylation, as an important regulator of allergic disease.

Massachusetts General Hospital. “New insight into allergies could improve diagnosis and treatment.” ScienceDaily. ScienceDaily, 20 May 2020. Link to the article
FARE BLOG. Molecule Identified in Study May Influence Allergies and Reaction Symptoms Findings from a FARE Investigator may aid the search for food allergy treatments and improved diagnostic tests. Link to the article
The Journal of Allergy and Clinical Immunology. News Beyond Our Pages. Marc E. Rothenberg, MD, PhD ∗ Jean Bousquet, MD ∗ DOI:https://doi.org/10.1016/j.jaci.2020.07.014. Link to the article

Self-reactive IgGs contribute to the pathology of autoimmune diseases, including systemic lupus erythematosus and rheumatoid arthritis. Paradoxically, IgGs are used to treat inflammatory diseases in the form of high-dose intravenous immunoglobulin (IVIG). Distinct glycoforms on the IgG crystallizable fragment (Fc) dictate these divergent functions. IgG anti-inflammatory activity is attributed to sialylation of the Fc glycan. We therefore sought to convert endogenous IgG to anti-inflammatory mediators in vivo by engineering solubilized glycosyltransferases that attach galactose or sialic acid. When both enzymes were administered in a prophylactic or therapeutic fashion, autoimmune inflammation was markedly attenuated in vivo. The enzymes worked through a similar pathway to IVIG, requiring DC-SIGN, STAT6 signaling, and FcγRIIB. Importantly, sialylation was highly specific to pathogenic IgG at the site of inflammation, driven by local platelet release of nucleotide-sugar donors. These results underscore the therapeutic potential of glycoengineering in vivo.

Massachusetts General Hospital. “Anti-inflammatory antibodies may treat autoimmune disease: Enzyme treatment converts autoantibodies into anti-inflammatory antibodies in animal models of two autoimmune diseases.” ScienceDaily. ScienceDaily, 21 December 2017. Link to the article
GEN: Genetic Engineering & Biotechnology News
“Technique Converts Harmful Autoantibodies into Anti-Inflammatory Antibodies In Vivo.” Link to the article
Nature reviews rheumatology volume 14, page121(2018). Research Highlight.
“Glycoengineering has therapeutic potential”Link to the article

Immunoglobulin ε (IgE) antibodies are the primary mediators of allergic diseases, which affect more than 1 in 10 individuals worldwide. IgE specific for innocuous environmental antigens, or allergens, binds and sensitizes tissue-resident mast cells expressing the high-affinity IgE receptor, FcεRI. Subsequent allergen exposure cross-links mast cell-bound IgE, resulting in the release of inflammatory mediators and initiation of the allergic cascade. It is well established that precise glycosylation patterns exert profound effects on the biological activity of IgG. However, the contribution of glycosylation to IgE biology is less clear. Here, we demonstrate an absolute requirement for IgE glycosylation in allergic reactions. The obligatory glycan was mapped to a single N-linked oligomannose structure in the constant domain 3 (Cε3) of IgE, at asparagine-394 (N394) in human IgE and N384 in mouse. Genetic disruption of the site or enzymatic removal of the oligomannose glycan altered IgE secondary structure and abrogated IgE binding to FcεRI, rendering IgE incapable of eliciting mast cell degranulation, thereby preventing anaphylaxis. These results underscore an unappreciated and essential requirement of glycosylation in IgE biology.

Stuti Mehta, D Alexander Cronkite, Megha Basavappa, Tahnee L Saunders, Fatemeh Adiliaghdam, Hajera Amatullah, Sara A Morrison, Jose D Pagan, Robert M Anthony, Pierre Tonnerre, Georg M Lauer, James C Lee, Sreehaas Digumarthi, Lorena Pantano, Shannan J Ho Sui, Fei Ji, Ruslan Sadreyev, Chan Zhou, Alan C Mullen, Vinod Kumar, Yang Li, Cisca Wijmenga, Ramnik J Xavier, Terry K Means, & Kate L Jeffrey. Sci Immunol. 2017 Mar 3. doi: 10.1126/sciimmunol.aag3160. https://pubmed.ncbi.nlm.nih.gov/28783698/

Featured Publications

Sialylation as an Important Regulator of Antibody Functionality

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Modulating T Follicular Cells In Vivo Enhances Antigen-Specific Humoral Immunity

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Sialylation of immunoglobulin E is a determinant of allergic pathogenicity

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Media Coverage

Engineered Sialylation of Pathogenic Antibodies In Vivo Attenuates Autoimmune Disease.

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Media Coverage

A single glycan on IgE is indispensable for initiation of anaphylaxis.

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Media Coverage

Other Anthony Publications and Collaborations

Lung injury induces a polarized immune response by self antigen-specific Foxp3+ regulatory T cells

Epigenetic reader SP140 loss of function drives Crohn’s disease due to uncontrolled macrophage topoisomerases

IgE Glycosylation in Health and Disease

Cis interaction between sialylated FcγRIIA and the αI-domain of Mac-1 limits antibody-mediated neutrophil recruitment

Modulation of Inflammatory Arthritis in Mice by Gut Microbiota Through Mucosal Inflammation and Autoantibody Generation

Maintenance of macrophage transcriptional programs and intestinal homeostasis by epigenetic reader SP140

In vivo imaging reveals a tumor-associated macrophage-mediated resistance pathway in anti-PD-1 therapy

Dual action of neurokinin-1 antagonists on Mas-related GPCRs

IgE/FcεRI-Mediated Antigen Cross-Presentation by Dendritic Cells Enhances Anti-Tumor Immune Responses

Acute inflammation primes myeloid effector cells for anti-inflammatory STAT6 signaling

Intravenous gammaglobulin suppresses inflammation through a novel Th2 pathway.

Identification of a receptor required for the anti-inflammatory activity of IVIG

Recapitulation of IVIG Anti-Inflammatory Activity with a Recombinant IgG Fc

Agalactosylated IgG antibodies depend on cellular Fc receptors for in vivo activity