A prominent lack of IgG1-Fc fucosylation of platelet alloantibodies in pregnancy

Therapeutic monoclonal antibodies (mAbs) have high efficacy in treating TNF α‐related immunological diseases. Other than neutralizing TNF α, these IgG1 antibodies exert Fc receptor‐mediated effector functions such as the complement‐dependent cytotoxicity (CDC) and antibody‐dependent cell cytotoxicity (ADCC). The crystallizable fragment (Fc) of these IgG1 contains a single glycosylation site at Asn 297/300 that is essential for the CDC and ADCC. Glycosylated antibodies lacking core fucosylation showed an improved ADCC. However, no structural data are available concerning the ligand‐binding interaction of these mAbs used in TNF α‐related diseases and the role of the fucosylation. We therefore used comparative modeling for generating complete 3D mAb models that include the antigen‐binding fragment (Fab) portions of infliximab, complexed with TNF α (4G3Y.pdb), the Fc region of the human IGHG1 fucosylated (3SGJ) and afucosylated (3SGK) complexed with the Fc receptor subtype Fcγ RIIIA, and the Fc region of a murine immunoglobulin (1IGT). After few thousand steps of energy minimization on the resulting 3D mAb models, minimized final models were used to quantify interactions occurring between Fcγ RIIIA and the fucosylated/afucosylated Fc fragments. While fucosylation does not affect Fab‐TNF α interactions, we found that in the absence of fucosylation the Fc–mAb domain and Fcγ RIIIA are closer and new strong interactions are established between G129 of the receptor and S301 of the Chimera 2 Fc mAb; new polar interactions are also established between the Chimera 2 Fc residues Y299, N300, and S301 and the Fcγ RIIIA residues K128, G129, R130, and R155. These data help to explain the reduced ADCC observed in the fucosylated mAbs suggesting the specific AA residues involved in binding interactions.

show abstract

“…2014; Kapur et al. 2014). This may have impact on the evaluation of therapeutic equivalence of anti‐TNF antibodies.…”

Section: Discussionmentioning

confidence: 99%

“…2003; Kapur et al. 2014). For example, the anti‐CD20 mAbs ofatumumab and rituximab display different levels of B‐cell depletion due to altered fucosylation levels.…”

Section: Introductionmentioning

confidence: 99%

Molecular modeling of antibodies for the treatment of TNFα‐related immunological diseases

Pierri

Bossis

Punzi

et al. 2016

Pharmacology Res & Perspec

View full text Add to dashboard Cite

show abstract

Section: Introductionmentioning

confidence: 90%

“…Recently we found that at least some of this discrepancy is due to differences in the functional quality of these antibodies, determined by its Fc glycosylation, in particular the level of core fucosylation. 13 However, the data indicated that additional cofactors may also be involved.Here we identified C-reactive protein (CRP), a member of the pentraxin family of highly conserved calcium-dependent ligand-binding proteins, to amplify IgG-mediated platelet destruction. CRP is composed of 5 identical, nonglycosylated 206 amino acids protomers forming a noncovalently linked annular symmetrical pentamer.…”

mentioning

confidence: 90%

“…For phagocytosis, platelets were labeled with pHrodo as described in the supplemental Methods, a pH-sensitive fluorescent dye only emitting a fluorescent signal at acid pH. 13 Equal volumes of 2.0 3 10 6 /mL PMN and 1.0 3 10 8 /mL platelets were mixed in a total volume of 100 mL in 1.4-mL U-bottom tubes (Micronic, Lelystad, The Netherlands), for 20 minutes in a shaking incubator at 37°C. Respiratory burst experiments were carried out in exactly the same way only using unlabeled platelets and with dihydrorhodamine 123 (Invitrogen, Molecular Probes, Eugene, OR) added to PMN before mixing with platelets, at a final concentration of 1 mM.…”

Section: Phagocytosis and Respiratory Burst Assaysmentioning

confidence: 99%

See 1 more Smart Citation

C-reactive protein enhances IgG-mediated phagocyte responses and thrombocytopenia

Kapur

Heitink‐Pollé

Porcelijn

et al. 2015

Blood

Self Cite

View full text Add to dashboard Cite

Key Points• CRP enhances IgG-mediated respiratory burst and phagocytosis of platelets in vitro and their clearance in vivo.• CRP levels are increased in ITP patients and correlate with platelet counts and bleeding severity and predict time to recovery.Immune-mediated platelet destruction is most frequently caused by allo-or autoantibodies via Fcg receptor-dependent phagocytosis. Disease severity can be predicted neither by antibody isotype nor by titer, indicating that other factors play a role. Here we show that the acute phase protein C-reactive protein (CRP), a ligand for Fc receptors on phagocytes, enhances antibody-mediated platelet destruction by human phagocytes in vitro and in vivo in mice. Without antiplatelet antibodies, CRP was found to be inert toward platelets, but it bound to phosphorylcholine exposed after oxidation triggered by antiplatelet antibodies, thereby enhancing platelet phagocytosis. CRP levels were significantly elevated in patients with allo-and autoantibody-mediated thrombocytopenias compared with healthy controls. Within a week, intravenous immunoglobulin treatment in children with newly diagnosed immune thrombocytopenia led to significant decrease of CRP levels, increased platelet numbers, and clinically decreased bleeding severity. Furthermore, the higher the level of CRP at diagnosis, the longer it took before stable platelet counts were reached. These data suggest that CRP amplifies antibody-mediated platelet destruction and may in part explain the aggravation of thrombocytopenia on infections. Hence, targeting CRP could offer new therapeutic opportunities for these patients. (Blood. 2015;125(11): 1793-1802 IntroductionFetal or neonatal alloimmune thrombocytopenia (FNAIT) and immune thrombocytopenia (ITP) are both antibody-mediated disorders in which platelets are destroyed mainly through activating immunoglobulin (IgG) Fc receptors on phagocytes in the spleen and liver, eventually resulting in thrombocytopenia. 1 In childhood, ITP is characterized by a typical history of acute development of purpura and bruising in an otherwise healthy child, caused by development of platelet autoantibodies, with an incidence of ;5 in 100 000 children.2 Most children with newly diagnosed ITP will not suffer from serious bleeding and will recover within 12 months. In ;60% of ITP, there is a history of a prior infection. [1][2][3] FNAIT is a potentially destructive disease in pregnancies, with intracerebral hemorrhage (ICH) of the fetus or neonate as the most feared complication, resulting in perinatal death in 1% to 7% or in severe neurological impairments in 14% to 26% of affected pregnancies. [4][5][6][7] FNAIT is caused by maternal IgG platelet alloantibodies, in whites mainly directed against human platelet antigen (HPA)-1a (85%), that cross the placenta and destroy the platelets of the fetus or newborn. Immunization against HPA-1a occurs in ;1:450 random pregnancies. [8][9][10] Although platelet decrement is related to antibody titer in FNAIT, 8,11,12 this correlation is not strict, as cas...

show abstract

Natural killer cell activation by respiratory syncytial virus‐specific antibodies is decreased in infants with severe respiratory infections and correlates with Fc‐glycosylation

et al. 2020

Self Cite

View full text Add to dashboard Cite

Objectives Respiratory syncytial virus (RSV) is a major cause of severe lower respiratory tract infections in infants, and there is no vaccine available. In early life, the most important contributors to protection against infectious diseases are the innate immune response and maternal antibodies. However, antibody‐mediated protection against RSV disease is incompletely understood, as both antibody levels and neutralisation capacity correlate poorly with protection. Since antibodies also mediate natural killer (NK) cell activation, we investigated whether this functionality correlates with RSV disease. Methods We performed an observational case–control study including infants hospitalised for RSV infection, hernia surgery or RSV‐negative respiratory viral infections. We determined RSV antigen‐specific antibody levels in plasma using a multiplex immunoassay. Subsequently, we measured the capacity of these antibodies to activate NK cells. Finally, we assessed Fc‐glycosylation of the RSV‐specific antibodies by mass spectrometry. Results We found that RSV‐specific maternal antibodies activate NK cells in vitro. While concentrations of RSV‐specific antibodies did not differ between cases and controls, antibodies from infants hospitalised for severe respiratory infections (RSV and/or other) induced significantly less NK cell interferon‐γ production than those from uninfected controls. Furthermore, NK cell activation correlated with Fc‐fucosylation of RSV‐specific antibodies, but their glycosylation status did not significantly differ between cases and controls. Conclusion Our results suggest that Fc‐dependent antibody function and quality, exemplified by NK cell activation and glycosylation, contribute to protection against severe RSV disease and warrant further studies to evaluate the potential of using these properties to evaluate and improve the efficacy of novel vaccines.

show abstract

A prominent lack of IgG1-Fc fucosylation of platelet alloantibodies in pregnancy

Abstract: Key Points Antibodies causing FNAIT have decreased Fc fucosylation, unlike in refractory thrombocytopenia. Decreased Fc fucose increases affinity to FcγRIIIa/b, enhances platelet phagocytosis, and correlates with increased disease severity.

Cited by 192 publications

References 50 publications

Molecular modeling of antibodies for the treatment of TNFα‐related immunological diseases

Molecular modeling of antibodies for the treatment of TNFα‐related immunological diseases

C-reactive protein enhances IgG-mediated phagocyte responses and thrombocytopenia

Natural killer cell activation by respiratory syncytial virus‐specific antibodies is decreased in infants with severe respiratory infections and correlates with Fc‐glycosylation

Contact Info

Product

Resources

About