We have recently shown that IgG1 directed against antigens thought to be involved in the pathogenesis of rheumatoid arthritis harbor different glycan moieties on their Fc-tail, as compared with... Show moreWe have recently shown that IgG1 directed against antigens thought to be involved in the pathogenesis of rheumatoid arthritis harbor different glycan moieties on their Fc-tail, as compared with total sera IgG1. Given the crucial roles of Fc-linked N-glycans for the structure and biological activity of IgG, Fc-glycosylation of antibodies is receiving considerable interest. However, so far little is known about the signals and factors that could influence the composition of these carbohydrate structures on secreted IgG produced by B lymphocytes. Here we show that both "environmental" factors, such as all-trans retinoic acid (a natural metabolite of vitamin A), as well as factors stimulating the innate immune system (i.e. CpG oligodeoxynucleotide, a ligand for toll-like receptor 9) or coming from the adaptive immune system (i.e. interleukin-21, a T-cell derived cytokine) can modulate IgG1 Fc-glycosylation. These factors affect Fc-glycan profiles in different ways. CpG oligodeoxynucleotide and interleukin-21 increase Fc-linked galactosylation and reduce bisecting N-acetylglucosamine levels, whereas all-trans retinoic acid significantly decreases galactosylation and sialylation levels. Moreover, these effects appeared to be stable and specific for secreted IgG1 as no parallel changes of the corresponding glycans in the cellular glycan pool were observed. Interestingly, several other cytokines and molecules known to affect B-cell biology and antibody production did not have an impact on IgG1 Fc-coupled glycan profiles. Together, these data indicate that different stimuli received by B cells during their activation and differentiation can modulate the Fc-linked glycosylation of secreted IgG1 without affecting the general cellular glycosylation machinery. Our study, therefore, furthers our understanding of the regulation of IgG1 glycosylation at the cellular level. Molecular & Cellular Proteomics 10: 10.1074/mcp.M110.004655, 1-12, 2011. Show less
Wang, J.; Bax, M.; Balog, C.I.A.; Stavenhagen, K.; Koeleman, C.A.M.; Scherer, H.U.; ... ; Wuhrer, M. 2011
It is well established that naive cells can be converted by TGF-beta into CD4(+)CD25(+) regulatory T (Treg) cells with therapeutic potentials Likewise it is shown that all-trans retinoic acid (ATRA... Show moreIt is well established that naive cells can be converted by TGF-beta into CD4(+)CD25(+) regulatory T (Treg) cells with therapeutic potentials Likewise it is shown that all-trans retinoic acid (ATRA) can greatly enhance TGF-beta-induced Treg conversion a phenomenon which has mainly been studied in C57BL/6 mice Here we show that although purified naive cells are highly susceptible to Treg generation total CD4(+) T-cell populations from different mouse strains display significantly different sensitivities to TGF-beta/ATRA-induced Treg conversion The resistance of non-responder strains is associated with an enhanced production of IL-4 by memory T cells as well as an Increased sensitivity of naive T cells to the action of IL-4 Importantly neutralization of IL-4 overcomes the differences thereby enabling TGF-beta/ATRA to generate large numbers of functional Treg cells from total CD4(+) T cells in a consistent manner across different mouse strains Likewise blockade of IL-4 significantly enhances TGF-beta/ATRA-induced Treg conversion from human naive T cells in the presence of memory cells These results show that the inherent resistance of "non-responder mouse strains to Treg conversion induced by TGF-beta and ATRA can be reverted by neutralization of IL-4 and that Inhibiting the action of IL-4 is beneficial or even necessary for consistent inducible Treg generation (C) 2010 Elsevier Ltd All rights reserved Show less
It is well established that naive cells can be converted by TGF-β into CD4(+)CD25(+) regulatory T (Treg) cells with therapeutic potentials. Likewise, it is shown that all-trans retinoic acid (ATRA)... Show moreIt is well established that naive cells can be converted by TGF-β into CD4(+)CD25(+) regulatory T (Treg) cells with therapeutic potentials. Likewise, it is shown that all-trans retinoic acid (ATRA) can greatly enhance TGF-β-induced Treg conversion, a phenomenon which has mainly been studied in C57BL/6 mice. Here we show that, although purified naive cells are highly susceptible to Treg generation, total CD4(+) T-cell populations from different mouse strains display significantly different sensitivities to TGF-β/ATRA-induced Treg conversion. The resistance of "non-responder" strains is associated with an enhanced production of IL-4 by memory T cells as well as an increased sensitivity of naive T cells to the action of IL-4. Importantly, neutralization of IL-4 overcomes the differences, thereby enabling TGF-β/ATRA to generate large numbers of functional Treg cells from total CD4(+) T cells in a consistent manner across different mouse strains. Likewise, blockade of IL-4 significantly enhances TGF-β/ATRA-induced Treg conversion from human naive T cells in the presence of memory cells. These results show that the inherent resistance of "non-responder" mouse strains to Treg conversion induced by TGF-β and ATRA can be reverted by neutralization of IL-4 and that inhibiting the action of IL-4 is beneficial or even necessary for consistent inducible Treg generation. Show less
Scherer, H.U.; Woude, D. van der; Ioan-Facsinay, A.; Bannoudi, H. el; Trouw, L.A.; Wang, J.; ... ; Toes, R.E.M. 2010
Objective. Anti-citrullinated protein antibodies ( ACPA) exhibit unique specificity for rheumatoid arthritis. However, it is incompletely understood whether and how ACPA contribute to disease... Show moreObjective. Anti-citrullinated protein antibodies ( ACPA) exhibit unique specificity for rheumatoid arthritis. However, it is incompletely understood whether and how ACPA contribute to disease pathogenesis. The Fc part of human IgG carries 2 N-linked glycan moieties that are crucial for the structural stability of the antibody and that modulate both its binding affinity to Fc gamma receptors and its ability to activate complement. We undertook this study to analyze Fc glycosylation of IgG1 ACPA in serum and synovial fluid ( SF) in order to further characterize the immune response to citrullinated antigens. Methods. ACPA were isolated by affinity purification using cyclic citrullinated peptides as antigen. IgG1 Fc glycosylation was analyzed by mass spectrometry. ACPA IgG1 glycan profiles were compared with glycan profiles of total serum IgG1 obtained from 85 well-characterized patients. Glycan profiles of paired SF and serum samples were available from 11 additional patients. Results. Compared with the pool of serum IgG1, ACPA IgG1 lacked terminal sialic acid residues. In SF, ACPA were highly agalactosylated and lacked sialic acid residues, a feature that was not detected for total SF IgG1. Moreover, differential ACPA glycan profiles were detected in rheumatoid factor (RF)-positive and RF-negative patients. Conclusion. ACPA IgG1 exhibit a specific Fc-linked glycan profile that is distinct from that of total serum IgG1. Moreover, Fc glycosylation of ACPA differs markedly between SF and serum. Since Fc glycosylation directly affects the recruitment of Fc-mediated effector mechanisms, these data could further our understanding of the contribution of ACPA to disease pathogenesis. Show less
