Anja Lux | Friedrich-Alexander-Universität Erlangen-Nürnberg (original) (raw)

Papers by Anja Lux

Research paper thumbnail of Fra1 controls rheumatoid factor autoantibody production by bone marrow plasma cells and the development of autoimmune bone loss

Journal of Bone and Mineral Research

Next to proinflammatory cytokines, autoimmunity has been identified as a key trigger for osteocla... more Next to proinflammatory cytokines, autoimmunity has been identified as a key trigger for osteoclast activation and bone loss. IgG‐rheumatoid factor (IgG‐RF) immune complexes, which are present in patients with rheumatoid arthritis, were shown to boost osteoclast differentiation. To date, the regulation of IgG‐RF production in the absence of inflammatory triggers is unknown. Herein, we describe Fra1 as a key checkpoint that controls IgG‐RF production by plasma cells and regulates autoimmune‐mediated bone loss. Fra1 deficiency in B cells (Fra1ΔBcell) led to increased IgG1‐producing bone marrow plasma cells, enhanced IgG‐RF production, and increased bone loss associated with elevated osteoclast numbers after immunization. The effect of IgG‐RF on osteoclasts in vitro and on osteoclasts associated with bone loss in vivo was dependent on FcγR, especially FcγR3. Furthermore, immunization of WT mice with T‐cell‐dependent antigens induced a significant and robust decrease in Fra1 expression in bone marrow B cells, which was followed by increased IgG1 production and the induction of osteoclast‐mediated bone loss. Overall, these data identify Fra1 as a key mediator of IgG‐RF production and autoimmune‐mediated bone loss. © 2019 American Society for Bone and Mineral Research.

Research paper thumbnail of Fc RIV deletion reveals its central role for IgG2a and IgG2b activity in vivo

Proceedings of The National Academy of Sciences, 2010

Cellular Fcγ receptors are essential for IgG-dependent effector functions in vivo. There is convi... more Cellular Fcγ receptors are essential for IgG-dependent effector functions in vivo. There is convincing evidence that selective activating Fcγ receptors are responsible for the activity of individual IgG subclasses. Thus, IgG1 activity is absent in FcγRIII-deficient mice, and several studies suggest that the activity of the most potent IgG subclasses, IgG2a and IgG2b, might be dependent on either individual or a combination of activating FcγRs. To study the role of individual activating FcγRs for IgG subclass activity, we generated an FcγRIV-deficient mouse and showed that a variety of IgG2a-and IgG2b-dependent effector functions are impaired in the absence of this activating Fc receptor in models of autoimmunity and antibodydependent cellular cytotoxicity.

Research paper thumbnail of Complement-Dependent Activity of CD20-Specific IgG Correlates With Bivalent Antigen Binding and C1q Binding Strength

Frontiers in Immunology

Monoclonal antibodies directed against the CD20 surface antigen on B cells are widely used in the... more Monoclonal antibodies directed against the CD20 surface antigen on B cells are widely used in the therapy of B cell malignancies. Upon administration, the antibodies bind to CD20 expressing B cells and induce their depletion via cell- and complement-dependent cytotoxicity or by induction of direct cell killing. The three antibodies currently most often used in the clinic are Rituximab (RTX), Ofatumumab (OFA) and Obinutuzumab (OBI). Even though these antibodies are all of the human IgG1 subclass, they have previously been described to vary considerably in the effector functions involved in therapeutic B cell depletion, especially in regards to complement activation. Whereas OFA is known to strongly induce complement-dependent cytotoxicity, OBI is described to be far less efficient. In contrast, the role of complement in RTX-induced B cell depletion is still under debate. Some of this dissent might come from the use of different in vitro systems for characterization of antibody effect...

Research paper thumbnail of Impact of Plasma Membrane Domains on IgG Fc Receptor Function

Research paper thumbnail of The Immunological Organ Environment Dictates the Molecular and Cellular Pathways of Cytotoxic Antibody Activity

Research paper thumbnail of Author response: Human Fcγ-receptor IIb modulates pathogen-specific versus self-reactive antibody responses in lyme arthritis

Research paper thumbnail of Human Fcγ-receptor IIb modulates pathogen-specific versus self-reactive antibody responses in lyme arthritis

eLife

Pathogen-specific antibody responses need to be tightly regulated to generate protective but limi... more Pathogen-specific antibody responses need to be tightly regulated to generate protective but limit self-reactive immune responses. While loss of humoral tolerance has been associated with microbial infections, the pathways involved in balancing protective versus autoreactive antibody responses in humans are incompletely understood. Studies in classical mouse model systems have provided evidence that balancing of immune responses through inhibitory receptors is an important quality control checkpoint. Genetic differences between inbred mouse models and the outbred human population and allelic receptor variants not present in mice; however, argue for caution when directly translating these findings to the human system. By studying Borrelia burgdorferi infection in humanized mice reconstituted with human hematopoietic stem cells from donors homozygous for a functional or a non-functional FcγRIIb allele, we show that the human inhibitory FcγRIIb is a critical checkpoint balancing protec...

Research paper thumbnail of Expression Profiling and Glycan Engineering of IgG Subclass 1–4 in Nicotiana benthamiana

Frontiers in Bioengineering and Biotechnology

Research paper thumbnail of Dissecting FcγR Regulation Through a Multivalent Binding Model

Many immune receptors transduce activation across the plasma membrane through their clustering. W... more Many immune receptors transduce activation across the plasma membrane through their clustering. With Fcγ receptors, this clustering is driven by binding to antibodies of differing affinities that are in turn bound to multivalent antigen. As a consequence of this activation mechanism, accounting for and rationally manipulating IgG effector function is complicated by, among other factors, differing affinities between FcγR species and changes in the valency of antigen binding. In this study, we show that a model of multivalent receptor-ligand binding can effectively account for the contribution of IgG-FcγR affinity and immune complex valency. This model in turn enables us to make specific predictions about the effect of immune complexes of defined composition. In total, these results enable both rational immune complex design for a desired IgG effector function and the deconvolution of effector function by immune complexes.Summary pointsAvidity most prominently modulates low-affinity F...

Research paper thumbnail of Dissecting FcγR Regulation through a Multivalent Binding Model

Cell Systems

Highlights d Avidity most prominently modulates low-affinity FcgRimmune complex binding d A multi... more Highlights d Avidity most prominently modulates low-affinity FcgRimmune complex binding d A multivalent binding model can quantitatively predict FcgRimmune complex binding d Immune complex valency affects FcgR multimerization more than binding d A binding model predicts the outcome of in vivo FcgR-driven effector function

Research paper thumbnail of Detection of Experimental and Clinical Immune Complexes by Measuring SHIP-1 Recruitment to the Inhibitory FcγRIIB

Journal of immunology (Baltimore, Md. : 1950), Jan 19, 2018

Fc γ receptors (FcγR) are involved in multiple aspects of immune cell regulation, are central to ... more Fc γ receptors (FcγR) are involved in multiple aspects of immune cell regulation, are central to the success of mAb therapeutics, and underpin the pathology of several autoimmune diseases. However, reliable assays capable of accurately measuring FcγR interactions with their physiological ligands, IgG immune complexes (IC), are limited. A method to study and detect IC interactions with FcγRs was therefore developed. This method, designed to model the signaling pathway of the inhibitory FcγRIIB (CD32B), used NanoLuc Binary Interaction Technology to measure recruitment of the Src homology 2 domain-containing inositol phosphatase 1 to the ITIM of this receptor. Such recruitment required prior cross-linking of an ITAM-containing activatory receptor, and evoked luciferase activity in discrete clusters at the cell surface, recapitulating the known biology of CD32B signaling. The assay detected varying forms of experimental IC, including heat-aggregated IgG, rituximab-anti-idiotype complexe...

Research paper thumbnail of Corrigendum: IgG Fc domains that bind C1q but not effector Fcγ receptors delineate the importance of complement-mediated effector functions

Nature Immunology

In the version of this article initially published, the top middle portion of Figure 4a was incor... more In the version of this article initially published, the top middle portion of Figure 4a was incorrect. The MHC and TCR should be on the left, and the B7 and CD28 should be on the right (diagrams and labels for both). The error has been corrected in the HTML and PDF versions of the article.

Research paper thumbnail of IgG subclass and vaccination stimulus determine changes in antigen specific antibody glycosylation in mice

European Journal of Immunology

Immunoglobulin G (IgG) glycosylation can modulate antibody effector functions. Depending on the p... more Immunoglobulin G (IgG) glycosylation can modulate antibody effector functions. Depending on the precise composition of the sugar moiety attached to individual IgG glycovariants either pro-or anti-inflammatory effector pathways can be initiated via differential binding to type I or type II Fc-receptors. However, an in depth understanding of how individual IgG subclasses are glycosylated during the steady state and how their glycosylation pattern changes during vaccination is missing. To monitor IgG subclass glycosylation during the steady state and upon vaccination of mice with different T-cell dependent and independent antigens, tryptic digests of serum, and antigen-specific IgG preparations were analyzed by reversed phase-liquid chromatography-mass spectrometry. We show that there is a remarkable difference with respect to how individual IgG subclasses are glycosylated during the steady state. More importantly, upon T-cell dependent and independent vaccinations, individual antigen-specific IgG subclasses reacted differently with respect to changes in individual glycoforms, suggesting that the IgG subclass itself is a major determinant of restricting or allowing alterations in specific IgG glycovariants.

Research paper thumbnail of Human lymphoid organ dendritic cell identity is predominantly dictated by ontogeny, not tissue microenvironment

Science immunology, Jan 16, 2016

In mice, conventional and plasmacytoid dendritic cells (DCs) derive from separate hematopoietic p... more In mice, conventional and plasmacytoid dendritic cells (DCs) derive from separate hematopoietic precursors before they migrate to peripheral tissues. Moreover, two classes of conventional DCs (cDC1 and cDC2 DCs) and one class of plasmacytoid DCs (pDCs) have been shown to be transcriptionally and functionally distinct entities. In humans, these three DC subtypes can be identified using the cell surface markers CD1c (cDC2), CD141 (cDC1), and CD303 (pDCs), albeit it remains elusive whether DC functionality is mainly determined by ontogeny or the tissue microenvironment. By phenotypic and transcriptional profiling of these three DC subtypes in different human tissues derived from a large number of human individuals, we demonstrate that DC subpopulations in organs of the lymphohematopoietic system (spleen, thymus, and blood) are strongly defined by ontogeny rather than by signals from the microenvironment. In contrast, DC subsets derived from human lung or skin differed substantially, st...

Research paper thumbnail of Regulation of autoantibody activity by the IL-23–TH17 axis determines the onset of autoimmune disease

Nature Immunology, 2016

The checkpoints and mechanisms that contribute to autoantibody-driven disease are as yet incomple... more The checkpoints and mechanisms that contribute to autoantibody-driven disease are as yet incompletely understood. Here we identified the axis of interleukin 23 (IL-23) and the TH17 subset of helper T cells as a decisive factor that controlled the intrinsic inflammatory activity of autoantibodies and triggered the clinical onset of autoimmune arthritis. By instructing B cells in an IL-22- and IL-21-dependent manner, TH17 cells regulated the expression of β-galactoside α2,6-sialyltransferase 1 in newly differentiating antibody-producing cells and determined the glycosylation profile and activity of immunoglobulin G (IgG) produced by the plasma cells that subsequently emerged. Asymptomatic humans with rheumatoid arthritis (RA)-specific autoantibodies showed identical changes in the activity and glycosylation of autoreactive IgG antibodies before shifting to the inflammatory phase of RA; thus, our results identify an IL-23-TH17 cell-dependent pathway that controls autoantibody activity and unmasks a preexisting breach in immunotolerance.

Research paper thumbnail of The role of Fc? receptors in murine autoimmune thrombocytopenia

Research paper thumbnail of The Kaposi's Sarcoma-associated Herpesvirus-encoded vlRF-3 Inhibits Cellular IRF-5

The Journal of Biological Chemistry, 2009

Research paper thumbnail of A Monosaccharide Residue Is Sufficient to Maintain Mouse and Human IgG Subclass Activity and Directs IgG Effector Functions to Cellular Fc Receptors

Cell Reports, 2015

Immunoglobulin G (IgG) glycosylation modulates antibody activity and represents a major source of... more Immunoglobulin G (IgG) glycosylation modulates antibody activity and represents a major source of heterogeneity within antibody preparations. Depending on their glycosylation pattern, individual IgG glycovariants present in recombinant antibody preparations may trigger effects ranging from enhanced pro-inflammatory activity to increased anti-inflammatory activity. In contrast, reduction of IgG glycosylation beyond the central mannose core is generally believed to result in impaired IgG activity. However, this study reveals that a mono- or disaccharide structure consisting of one N-acetylglucosamine with or without a branching fucose residue is sufficient to retain the activity of the most active human and mouse IgG subclasses in vivo and further directs antibody activity to cellular Fcγ receptors. Notably, the activity of minimally glycosylated antibodies is not predicted by in vitro assays based on a monomeric antibody-Fcγ-receptor interaction analysis, whereas in vitro assay systems using immune complexes are more suitable to predict IgG activity in vivo.

Research paper thumbnail of Pathways Responsible for Human Autoantibody and Therapeutic Intravenous IgG Activity in Humanized Mice

Cell Reports, 2015

Immunoglobulin G (IgG) antibodies are major drivers of autoimmune pathology, but they are also us... more Immunoglobulin G (IgG) antibodies are major drivers of autoimmune pathology, but they are also used in the form of intravenous IgG (IVIg) therapy to suppress autoantibody activity. To identify the pathways underlying human autoantibody and IVIg activity, we established a humanized mouse model of an autoantibody-dependent autoimmune disease responding to treatment with IVIg preparations. We show that the human IgG subclass strongly impacts autoantibody activity and that the Fc-receptor genotype of the human donor immune system further modulates autoantibody activity. Human mononuclear phagocytes were responsible for autoantibody activity, and IVIg therapy was able to suppress disease pathology in an Fc-fragment-dependent manner. While highly sialylated IgG glycovariants were essential for IVIg activity, it was independent of the Fc-receptor genotype and did not result in a general block of activating or the neonatal Fc-receptor. These findings may help in the development of strategies to block autoantibody and enhance therapeutic IVIg activity in humans.

Research paper thumbnail of Impact of differential glycosylation on IgG activity

Advances in experimental medicine and biology, 2011

Immunoglobulin G (IgG) molecules are glycoproteins with dual functionality. While participating i... more Immunoglobulin G (IgG) molecules are glycoproteins with dual functionality. While participating in the destruction of virally infected cells or healthy tissues during autoimmune disease, IgG antibodies are also used as a therapeutic agent to suppress IgG-triggered autoimmune disease and inflammation. Research of recent years has put the IgG-associated sugar moiety in the spotlight for regulating these opposing activities. This review will focus on how certain IgG glycovariants impact different IgG-dependent effector functions and how this knowledge might be used to further improve the therapeutic effectiveness of this class of molecules.

Research paper thumbnail of Fra1 controls rheumatoid factor autoantibody production by bone marrow plasma cells and the development of autoimmune bone loss

Journal of Bone and Mineral Research

Next to proinflammatory cytokines, autoimmunity has been identified as a key trigger for osteocla... more Next to proinflammatory cytokines, autoimmunity has been identified as a key trigger for osteoclast activation and bone loss. IgG‐rheumatoid factor (IgG‐RF) immune complexes, which are present in patients with rheumatoid arthritis, were shown to boost osteoclast differentiation. To date, the regulation of IgG‐RF production in the absence of inflammatory triggers is unknown. Herein, we describe Fra1 as a key checkpoint that controls IgG‐RF production by plasma cells and regulates autoimmune‐mediated bone loss. Fra1 deficiency in B cells (Fra1ΔBcell) led to increased IgG1‐producing bone marrow plasma cells, enhanced IgG‐RF production, and increased bone loss associated with elevated osteoclast numbers after immunization. The effect of IgG‐RF on osteoclasts in vitro and on osteoclasts associated with bone loss in vivo was dependent on FcγR, especially FcγR3. Furthermore, immunization of WT mice with T‐cell‐dependent antigens induced a significant and robust decrease in Fra1 expression in bone marrow B cells, which was followed by increased IgG1 production and the induction of osteoclast‐mediated bone loss. Overall, these data identify Fra1 as a key mediator of IgG‐RF production and autoimmune‐mediated bone loss. © 2019 American Society for Bone and Mineral Research.

Research paper thumbnail of Fc RIV deletion reveals its central role for IgG2a and IgG2b activity in vivo

Proceedings of The National Academy of Sciences, 2010

Cellular Fcγ receptors are essential for IgG-dependent effector functions in vivo. There is convi... more Cellular Fcγ receptors are essential for IgG-dependent effector functions in vivo. There is convincing evidence that selective activating Fcγ receptors are responsible for the activity of individual IgG subclasses. Thus, IgG1 activity is absent in FcγRIII-deficient mice, and several studies suggest that the activity of the most potent IgG subclasses, IgG2a and IgG2b, might be dependent on either individual or a combination of activating FcγRs. To study the role of individual activating FcγRs for IgG subclass activity, we generated an FcγRIV-deficient mouse and showed that a variety of IgG2a-and IgG2b-dependent effector functions are impaired in the absence of this activating Fc receptor in models of autoimmunity and antibodydependent cellular cytotoxicity.

Research paper thumbnail of Complement-Dependent Activity of CD20-Specific IgG Correlates With Bivalent Antigen Binding and C1q Binding Strength

Frontiers in Immunology

Monoclonal antibodies directed against the CD20 surface antigen on B cells are widely used in the... more Monoclonal antibodies directed against the CD20 surface antigen on B cells are widely used in the therapy of B cell malignancies. Upon administration, the antibodies bind to CD20 expressing B cells and induce their depletion via cell- and complement-dependent cytotoxicity or by induction of direct cell killing. The three antibodies currently most often used in the clinic are Rituximab (RTX), Ofatumumab (OFA) and Obinutuzumab (OBI). Even though these antibodies are all of the human IgG1 subclass, they have previously been described to vary considerably in the effector functions involved in therapeutic B cell depletion, especially in regards to complement activation. Whereas OFA is known to strongly induce complement-dependent cytotoxicity, OBI is described to be far less efficient. In contrast, the role of complement in RTX-induced B cell depletion is still under debate. Some of this dissent might come from the use of different in vitro systems for characterization of antibody effect...

Research paper thumbnail of Impact of Plasma Membrane Domains on IgG Fc Receptor Function

Research paper thumbnail of The Immunological Organ Environment Dictates the Molecular and Cellular Pathways of Cytotoxic Antibody Activity

Research paper thumbnail of Author response: Human Fcγ-receptor IIb modulates pathogen-specific versus self-reactive antibody responses in lyme arthritis

Research paper thumbnail of Human Fcγ-receptor IIb modulates pathogen-specific versus self-reactive antibody responses in lyme arthritis

eLife

Pathogen-specific antibody responses need to be tightly regulated to generate protective but limi... more Pathogen-specific antibody responses need to be tightly regulated to generate protective but limit self-reactive immune responses. While loss of humoral tolerance has been associated with microbial infections, the pathways involved in balancing protective versus autoreactive antibody responses in humans are incompletely understood. Studies in classical mouse model systems have provided evidence that balancing of immune responses through inhibitory receptors is an important quality control checkpoint. Genetic differences between inbred mouse models and the outbred human population and allelic receptor variants not present in mice; however, argue for caution when directly translating these findings to the human system. By studying Borrelia burgdorferi infection in humanized mice reconstituted with human hematopoietic stem cells from donors homozygous for a functional or a non-functional FcγRIIb allele, we show that the human inhibitory FcγRIIb is a critical checkpoint balancing protec...

Research paper thumbnail of Expression Profiling and Glycan Engineering of IgG Subclass 1–4 in Nicotiana benthamiana

Frontiers in Bioengineering and Biotechnology

Research paper thumbnail of Dissecting FcγR Regulation Through a Multivalent Binding Model

Many immune receptors transduce activation across the plasma membrane through their clustering. W... more Many immune receptors transduce activation across the plasma membrane through their clustering. With Fcγ receptors, this clustering is driven by binding to antibodies of differing affinities that are in turn bound to multivalent antigen. As a consequence of this activation mechanism, accounting for and rationally manipulating IgG effector function is complicated by, among other factors, differing affinities between FcγR species and changes in the valency of antigen binding. In this study, we show that a model of multivalent receptor-ligand binding can effectively account for the contribution of IgG-FcγR affinity and immune complex valency. This model in turn enables us to make specific predictions about the effect of immune complexes of defined composition. In total, these results enable both rational immune complex design for a desired IgG effector function and the deconvolution of effector function by immune complexes.Summary pointsAvidity most prominently modulates low-affinity F...

Research paper thumbnail of Dissecting FcγR Regulation through a Multivalent Binding Model

Cell Systems

Highlights d Avidity most prominently modulates low-affinity FcgRimmune complex binding d A multi... more Highlights d Avidity most prominently modulates low-affinity FcgRimmune complex binding d A multivalent binding model can quantitatively predict FcgRimmune complex binding d Immune complex valency affects FcgR multimerization more than binding d A binding model predicts the outcome of in vivo FcgR-driven effector function

Research paper thumbnail of Detection of Experimental and Clinical Immune Complexes by Measuring SHIP-1 Recruitment to the Inhibitory FcγRIIB

Journal of immunology (Baltimore, Md. : 1950), Jan 19, 2018

Fc γ receptors (FcγR) are involved in multiple aspects of immune cell regulation, are central to ... more Fc γ receptors (FcγR) are involved in multiple aspects of immune cell regulation, are central to the success of mAb therapeutics, and underpin the pathology of several autoimmune diseases. However, reliable assays capable of accurately measuring FcγR interactions with their physiological ligands, IgG immune complexes (IC), are limited. A method to study and detect IC interactions with FcγRs was therefore developed. This method, designed to model the signaling pathway of the inhibitory FcγRIIB (CD32B), used NanoLuc Binary Interaction Technology to measure recruitment of the Src homology 2 domain-containing inositol phosphatase 1 to the ITIM of this receptor. Such recruitment required prior cross-linking of an ITAM-containing activatory receptor, and evoked luciferase activity in discrete clusters at the cell surface, recapitulating the known biology of CD32B signaling. The assay detected varying forms of experimental IC, including heat-aggregated IgG, rituximab-anti-idiotype complexe...

Research paper thumbnail of Corrigendum: IgG Fc domains that bind C1q but not effector Fcγ receptors delineate the importance of complement-mediated effector functions

Nature Immunology

In the version of this article initially published, the top middle portion of Figure 4a was incor... more In the version of this article initially published, the top middle portion of Figure 4a was incorrect. The MHC and TCR should be on the left, and the B7 and CD28 should be on the right (diagrams and labels for both). The error has been corrected in the HTML and PDF versions of the article.

Research paper thumbnail of IgG subclass and vaccination stimulus determine changes in antigen specific antibody glycosylation in mice

European Journal of Immunology

Immunoglobulin G (IgG) glycosylation can modulate antibody effector functions. Depending on the p... more Immunoglobulin G (IgG) glycosylation can modulate antibody effector functions. Depending on the precise composition of the sugar moiety attached to individual IgG glycovariants either pro-or anti-inflammatory effector pathways can be initiated via differential binding to type I or type II Fc-receptors. However, an in depth understanding of how individual IgG subclasses are glycosylated during the steady state and how their glycosylation pattern changes during vaccination is missing. To monitor IgG subclass glycosylation during the steady state and upon vaccination of mice with different T-cell dependent and independent antigens, tryptic digests of serum, and antigen-specific IgG preparations were analyzed by reversed phase-liquid chromatography-mass spectrometry. We show that there is a remarkable difference with respect to how individual IgG subclasses are glycosylated during the steady state. More importantly, upon T-cell dependent and independent vaccinations, individual antigen-specific IgG subclasses reacted differently with respect to changes in individual glycoforms, suggesting that the IgG subclass itself is a major determinant of restricting or allowing alterations in specific IgG glycovariants.

Research paper thumbnail of Human lymphoid organ dendritic cell identity is predominantly dictated by ontogeny, not tissue microenvironment

Science immunology, Jan 16, 2016

In mice, conventional and plasmacytoid dendritic cells (DCs) derive from separate hematopoietic p... more In mice, conventional and plasmacytoid dendritic cells (DCs) derive from separate hematopoietic precursors before they migrate to peripheral tissues. Moreover, two classes of conventional DCs (cDC1 and cDC2 DCs) and one class of plasmacytoid DCs (pDCs) have been shown to be transcriptionally and functionally distinct entities. In humans, these three DC subtypes can be identified using the cell surface markers CD1c (cDC2), CD141 (cDC1), and CD303 (pDCs), albeit it remains elusive whether DC functionality is mainly determined by ontogeny or the tissue microenvironment. By phenotypic and transcriptional profiling of these three DC subtypes in different human tissues derived from a large number of human individuals, we demonstrate that DC subpopulations in organs of the lymphohematopoietic system (spleen, thymus, and blood) are strongly defined by ontogeny rather than by signals from the microenvironment. In contrast, DC subsets derived from human lung or skin differed substantially, st...

Research paper thumbnail of Regulation of autoantibody activity by the IL-23–TH17 axis determines the onset of autoimmune disease

Nature Immunology, 2016

The checkpoints and mechanisms that contribute to autoantibody-driven disease are as yet incomple... more The checkpoints and mechanisms that contribute to autoantibody-driven disease are as yet incompletely understood. Here we identified the axis of interleukin 23 (IL-23) and the TH17 subset of helper T cells as a decisive factor that controlled the intrinsic inflammatory activity of autoantibodies and triggered the clinical onset of autoimmune arthritis. By instructing B cells in an IL-22- and IL-21-dependent manner, TH17 cells regulated the expression of β-galactoside α2,6-sialyltransferase 1 in newly differentiating antibody-producing cells and determined the glycosylation profile and activity of immunoglobulin G (IgG) produced by the plasma cells that subsequently emerged. Asymptomatic humans with rheumatoid arthritis (RA)-specific autoantibodies showed identical changes in the activity and glycosylation of autoreactive IgG antibodies before shifting to the inflammatory phase of RA; thus, our results identify an IL-23-TH17 cell-dependent pathway that controls autoantibody activity and unmasks a preexisting breach in immunotolerance.

Research paper thumbnail of The role of Fc? receptors in murine autoimmune thrombocytopenia

Research paper thumbnail of The Kaposi's Sarcoma-associated Herpesvirus-encoded vlRF-3 Inhibits Cellular IRF-5

The Journal of Biological Chemistry, 2009

Research paper thumbnail of A Monosaccharide Residue Is Sufficient to Maintain Mouse and Human IgG Subclass Activity and Directs IgG Effector Functions to Cellular Fc Receptors

Cell Reports, 2015

Immunoglobulin G (IgG) glycosylation modulates antibody activity and represents a major source of... more Immunoglobulin G (IgG) glycosylation modulates antibody activity and represents a major source of heterogeneity within antibody preparations. Depending on their glycosylation pattern, individual IgG glycovariants present in recombinant antibody preparations may trigger effects ranging from enhanced pro-inflammatory activity to increased anti-inflammatory activity. In contrast, reduction of IgG glycosylation beyond the central mannose core is generally believed to result in impaired IgG activity. However, this study reveals that a mono- or disaccharide structure consisting of one N-acetylglucosamine with or without a branching fucose residue is sufficient to retain the activity of the most active human and mouse IgG subclasses in vivo and further directs antibody activity to cellular Fcγ receptors. Notably, the activity of minimally glycosylated antibodies is not predicted by in vitro assays based on a monomeric antibody-Fcγ-receptor interaction analysis, whereas in vitro assay systems using immune complexes are more suitable to predict IgG activity in vivo.

Research paper thumbnail of Pathways Responsible for Human Autoantibody and Therapeutic Intravenous IgG Activity in Humanized Mice

Cell Reports, 2015

Immunoglobulin G (IgG) antibodies are major drivers of autoimmune pathology, but they are also us... more Immunoglobulin G (IgG) antibodies are major drivers of autoimmune pathology, but they are also used in the form of intravenous IgG (IVIg) therapy to suppress autoantibody activity. To identify the pathways underlying human autoantibody and IVIg activity, we established a humanized mouse model of an autoantibody-dependent autoimmune disease responding to treatment with IVIg preparations. We show that the human IgG subclass strongly impacts autoantibody activity and that the Fc-receptor genotype of the human donor immune system further modulates autoantibody activity. Human mononuclear phagocytes were responsible for autoantibody activity, and IVIg therapy was able to suppress disease pathology in an Fc-fragment-dependent manner. While highly sialylated IgG glycovariants were essential for IVIg activity, it was independent of the Fc-receptor genotype and did not result in a general block of activating or the neonatal Fc-receptor. These findings may help in the development of strategies to block autoantibody and enhance therapeutic IVIg activity in humans.

Research paper thumbnail of Impact of differential glycosylation on IgG activity

Advances in experimental medicine and biology, 2011

Immunoglobulin G (IgG) molecules are glycoproteins with dual functionality. While participating i... more Immunoglobulin G (IgG) molecules are glycoproteins with dual functionality. While participating in the destruction of virally infected cells or healthy tissues during autoimmune disease, IgG antibodies are also used as a therapeutic agent to suppress IgG-triggered autoimmune disease and inflammation. Research of recent years has put the IgG-associated sugar moiety in the spotlight for regulating these opposing activities. This review will focus on how certain IgG glycovariants impact different IgG-dependent effector functions and how this knowledge might be used to further improve the therapeutic effectiveness of this class of molecules.