| 1. |
- Bahnan, Wael, et al.
(författare)
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Spike-Dependent Opsonization Indicates Both Dose-Dependent Inhibition of Phagocytosis and That Non-Neutralizing Antibodies Can Confer Protection to SARS-CoV-2
- 2022
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Spike-specific antibodies are central to effective COVID19 immunity. Research efforts have focused on antibodies that neutralize the ACE2-Spike interaction but not on non-neutralizing antibodies. Antibody-dependent phagocytosis is an immune mechanism enhanced by opsonization, where typically, more bound antibodies trigger a stronger phagocyte response. Here, we show that Spike-specific antibodies, dependent on concentration, can either enhance or reduce Spike-bead phagocytosis by monocytes independently of the antibody neutralization potential. Surprisingly, we find that both convalescent patient plasma and patient-derived monoclonal antibodies lead to maximum opsonization already at low levels of bound antibodies and is reduced as antibody binding to Spike protein increases. Moreover, we show that this Spike-dependent modulation of opsonization correlate with the outcome in an experimental SARS-CoV-2 infection model. These results suggest that the levels of anti-Spike antibodies could influence monocyte-mediated immune functions and propose that non-neutralizing antibodies could confer protection to SARS-CoV-2 infection by mediating phagocytosis.
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| 2. |
- Glesner, Jill, et al.
(författare)
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A Human IgE Antibody Binding Site on Der p 2 for the Design of a Recombinant Allergen for Immunotherapy
- 2019
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Ingår i: Journal of immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 203:9, s. 2545-2556
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Tidskriftsartikel (refereegranskat)abstract
- Der p 2 is one of the most important allergens from the house dust mite Dermatophagoides pteronyssinus Identification of human IgE Ab binding epitopes can be used for rational design of allergens with reduced IgE reactivity for therapy. Antigenic analysis of Der p 2 was performed by site-directed mutagenesis based on the x-ray crystal structure of the allergen in complex with a Fab from the murine IgG mAb 7A1 that binds an epitope overlapping with human IgE binding sites. Conformational changes upon Ab binding were confirmed by nuclear magnetic resonance using a 7A1-single-chain variable fragment. In addition, a human IgE Ab construct that interferes with mAb 7A1 binding was isolated from a combinatorial phage-display library constructed from a mite-allergic patient and expressed as two recombinant forms (single-chain Fab in Pichia pastoris and Fab in Escherichia coli). These two IgE Ab constructs and the mAb 7A1 failed to recognize two Der p 2 epitope double mutants designed to abolish the allergen-Ab interaction while preserving the fold necessary to bind Abs at other sites of the allergen surface. A 10-100-fold reduction in binding of IgE from allergic subjects to the mutants additionally showed that the residues mutated were involved in IgE Ab binding. In summary, mutagenesis of a Der p 2 epitope defined by x-ray crystallography revealed an IgE Ab binding site that will be considered for the design of hypoallergens for immunotherapy.
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| 3. |
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| 4. |
- Hoh, Ramona A., et al.
(författare)
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Clonal evolution and stereotyped sequences of human IgE lineages in aeroallergen-specific immunotherapy
- 2023
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Ingår i: Journal of Allergy and Clinical Immunology. - : Elsevier BV. - 0091-6749. ; 152:1, s. 214-229
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Tidskriftsartikel (refereegranskat)abstract
- Background: Allergic disease reflects specific inflammatory processes initiated by interaction between allergen and allergen-specific IgE. Specific immunotherapy (SIT) is an effective long-term treatment option, but the mechanisms by which SIT provides desensitization are not well understood. Objective: Our aim was to characterize IgE sequences expressed by allergen-specific B cells over a 3-year longitudinal study of patients with aeroallergies who were undergoing SIT. Methods: Allergen-specific IgE–expressing clones were identified by using combinatorial single-chain variable fragment libraries and tracked in PBMCs and nasal biopsy samples over a 3-year period with antibody gene repertoire sequencing. The characteristics of private IgE-expressing clones were compared with those of stereotyped or “public” IgE responses to the grass pollen allergen Phleum pratense (Phl p) 2. Result: Members of the same allergen-specific IgE lineages were observed in nasal biopsy samples and blood, and lineages detected at baseline persisted in blood and nasal biopsy samples after 3 years of SIT, including B cells that express IgE. Evidence of progressive class switch recombination to IgG subclasses was observed after 3 years of SIT. A common stereotyped Phl p 2–specific antibody heavy chain sequence was detected in multiple donors. The amino acid residues enriched in IgE-stereotyped sequences from seropositive donors were analyzed with machine learning and k-mer motif discovery. Stereotyped IgE sequences had lower overall rates of somatic hypermutation and antigen selection than did single-chain variable fragment–derived allergen-specific sequences or IgE sequences of unknown specificity. Conclusion: Longitudinal tracking of rare circulating and tissue-resident allergen-specific IgE+ clones demonstrates persistence of allergen-specific IgE+ clones, progressive class switch recombination to IgG subtypes, and distinct maturation of a stereotyped Phl p 2 clonotype.
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| 5. |
- Izadi, Arman, et al.
(författare)
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Protective non-neutralizing mAbs Ab94 and Ab81 retain high-affinity and potent Fc-mediated function against SARS-CoV-2 variants from Omicron to XBB1.5
- 2023
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Antibodies play a central role in the immune defense against SARS-CoV-2. Strong evidence has shown that non-neutralizing antibodies (nnAbs) are important for anti-SARS-Cov-2 immunity through Fc-mediated effector functions. These nnAbs bind to epitopes that could be less subjected to mutations in the emerging variants. When protective, such nnAbs would constitute a more promising alternative to neutralizing mAbs (nAbs). Here, we show that six nnAbs retain binding to Omicron, while two nAbs do not. Furthermore, two of our nnAbs, which are protective in vivo, retained binding to XBB, XBB.1.5, and BQ.1.1. They appear to bind to conserved epitopes on the N-terminal and receptor binding domain (RBD), respectively. As a proof of concept, we show that these protective non-neutralizing antibodies retain potent Fc-mediated opsonic function against BQ.1.1 and XBB. We also show that the Fc-mediated function is further enhanced by expressing the antibodies in the IgG3 subclass and combining them into a dual antibody cocktail. Our work suggests that opsonizing nnAbs could be a viable strategy for anti-SARS-CoV-2 mAb therapies against current and future SARS-CoV-2 variants.
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| 6. |
- Izadi, Arman, et al.
(författare)
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Subclass-switched anti-Spike IgG3 oligoclonal cocktails strongly enhance Fc-mediated opsonization
- 2023
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Ingår i: Proceedings of the National Academy of Sciences. - 1091-6490. ; 120:15
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Tidskriftsartikel (refereegranskat)abstract
- Antibodies play a central role in the immune defense against SARS-CoV-2. Emerging evidence has shown that nonneutralizing antibodies are important for immune defense through Fc-mediated effector functions. Antibody subclass is known to affect downstream Fc function. However, whether the antibody subclass plays a role in anti-SARS-CoV-2 immunity remains unclear. Here, we subclass-switched eight human IgG1 anti-spike monoclonal antibodies (mAbs) to the IgG3 subclass by exchanging their constant domains. The IgG3 mAbs exhibited altered avidities to the spike protein and more potent Fc-mediated phagocytosis and complement activation than their IgG1 counterparts. Moreover, combining mAbs into oligoclonal cocktails led to enhanced Fc- and complement receptor-mediated phagocytosis, superior to even the most potent single IgG3 mAb when compared at equivalent concentrations. Finally, in an in vivo model, we show that opsonic mAbs of both subclasses can be protective against a SARS-CoV-2 infection, despite the antibodies being nonneutralizing. Our results suggest that opsonic IgG3 oligoclonal cocktails are a promising idea to explore for therapy against SARS-CoV-2, its emerging variants, and potentially other viruses.
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| 7. |
- Izadi, Arman, et al.
(författare)
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The hinge-engineered IgG1-IgG3 hybrid subclass IgGh47 potently enhances Fc-mediated function of anti-streptococcal and SARS-CoV-2 antibodies
- 2024
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Ingår i: Nature Communications. - 2041-1723. ; 15, s. 1-22
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pyogenes can cause invasive disease with high mortality despite adequate antibiotic treatments. To address this unmet need, we have previously generated an opsonic IgG1 monoclonal antibody, Ab25, targeting the bacterial M protein. Here, we engineer the IgG2-4 subclasses of Ab25. Despite having reduced binding, the IgG3 version promotes stronger phagocytosis of bacteria. Using atomic simulations, we show that IgG3’s Fc tail has extensive movement in 3D space due to its extended hinge region, possibly facilitating interactions with immune cells. We replaced the hinge of IgG1 with four different IgG3-hinge segment subclasses, IgGhxx. Hinge-engineering does not diminish binding as with IgG3 but enhances opsonic function, where a 47 amino acid hinge is comparable to IgG3 in function. IgGh47 shows improved protection against S. pyogenes in a systemic infection mouse model, suggesting that IgGh47 has promise as a preclinical therapeutic candidate. Importantly, the enhanced opsonic function of IgGh47 is generalizable to diverse S. pyogenes strains from clinical isolates. We generated IgGh47 versions of anti-SARS-CoV-2 mAbs to broaden the biological applicability, and these also exhibit strongly enhanced opsonic function compared to the IgG1 subclass. The improved function of the IgGh47 subclass in two distant biological systems provides new insights into antibody function.
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| 8. |
- Thalén, Niklas, et al.
(författare)
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Mammalian cell surface display system for conformational epitope determination of SARS-CoV-2 neutralizing antibodies
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Cell surface display of recombinant proteins for epitope mapping has become a powerful tool for biotechnology and biomedical applications. One critical aspect for identifying the full and correct epitope is to present the correctly folded and post-translationally modified protein antigen on the cell surface for true epitope-paratope interaction. Being the gold standard for production of complex proteins, Chinese hamster ovarian cells are here used for a mammalian cell display system. Additionally, to enable a fast workflow for alanine substitution of a large panel of clones, a web-based design tool and automated cloning process was established. A proof-of-concept is presented with the aligned epitope of the crystal structure for the CR3022 antibody with our mammalian cell display determined epitope. Furthermore, three additional antibody epitopes against SARS-CoV-2 RBD are presented. This study presents a detailed view of epitope-paratope interactions, which is of great importance for future clinical interventions against SARS-CoV-2.
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