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Paudyal B, Mwangi W, Rijal P, Schwartz JC, Noble A, Shaw A, Sealy JE, Bonnet-Di Placido M, Graham SP, Townsend A, Hammond JA, Tchilian E. Fc-Mediated Functions of Porcine IgG Subclasses. Front Immunol 2022; 13:903755. [PMID: 35757698 PMCID: PMC9218351 DOI: 10.3389/fimmu.2022.903755] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 04/29/2022] [Indexed: 11/13/2022] Open
Abstract
The pig is an important agricultural species and powerful biomedical model. We have established the pig, a large natural host animal for influenza with many physiological similarities to humans, as a robust model for testing the therapeutic potential of monoclonal antibodies. Antibodies provide protection through neutralization and recruitment of innate effector functions through the Fc domain. However very little is known about the Fc-mediated functions of porcine IgG subclasses. We have generated 8 subclasses of two porcine monoclonal anti influenza hemagglutinin antibodies. We characterized their ability to activate complement, trigger cytotoxicity and phagocytosis by immune cells and assayed their binding to monocytes, macrophages, and natural killer cells. We show that IgG1, IgG2a, IgG2b, IgG2c and IgG4 bind well to targeted cell types and mediate complement mediated cellular cytotoxicity (CDCC), antibody dependent cellular cytotoxicity (ADCC) and antibody mediated cell phagocytosis (ADCP). IgG5b and IgG5c exhibited weak binding and variable and poor functional activity. Immune complexes of porcine IgG3 did not show any Fc-mediated functions except for binding to monocytes and macrophages and weak binding to NK cells. Interestingly, functionally similar porcine IgG subclasses clustered together in the genome. These novel findings will enhance the utility of the pig model for investigation of therapeutic antibodies.
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Affiliation(s)
- Basudev Paudyal
- Host Responses, The Pirbright Institute, Woking, United Kingdom
| | - William Mwangi
- Host Responses, The Pirbright Institute, Woking, United Kingdom
| | - Pramila Rijal
- Medical Research Council (MRC) Human Immunology Unit, Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - John C Schwartz
- Host Responses, The Pirbright Institute, Woking, United Kingdom
| | - Alistair Noble
- Host Responses, The Pirbright Institute, Woking, United Kingdom
| | - Andrew Shaw
- Host Responses, The Pirbright Institute, Woking, United Kingdom
| | - Joshua E Sealy
- Host Responses, The Pirbright Institute, Woking, United Kingdom
| | | | - Simon P Graham
- Host Responses, The Pirbright Institute, Woking, United Kingdom
| | - Alain Townsend
- Medical Research Council (MRC) Human Immunology Unit, Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - John A Hammond
- Host Responses, The Pirbright Institute, Woking, United Kingdom
| | - Elma Tchilian
- Host Responses, The Pirbright Institute, Woking, United Kingdom
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Abstract
Neuromyelitis optica (NMO) is an autoimmune demyelinating disease associated with recurrent episodes of optic neuritis and transverse myelitis, often resulting in permanent blindness and/or paralysis. The discovery of autoantibodies (AQP4-IgG) that target aquaporin-4 (AQP4) has accelerated our understanding of the cellular mechanisms driving NMO pathogenesis. AQP4 is a bidirectional water channel expressed on the plasma membranes of astrocytes, retinal Müller cells, skeletal muscle, and some epithelial cells in kidney, lung and the gastrointestinal tract. AQP4 tetramers form regular supramolecular assemblies at the cell plasma membrane called orthogonal arrays of particles. The pathological features of NMO include perivascular deposition of immunoglobulin and activated complement, loss of astrocytic AQP4, inflammatory infiltration with granulocyte and macrophage accumulation, and demyelination with axon loss. Current evidence supports a causative role of AQP4-IgG in NMO, in which binding of AQP4-IgG to AQP4 orthogonal arrays on astrocytes initiates complement-dependent and antibody-dependent cell-mediated cytotoxicity and inflammation. Immunosuppression and plasma exchange are the mainstays of therapy for NMO optic neuritis. Novel therapeutics targeting specific steps in NMO pathogenesis are entering the development pipeline, including blockers of AQP4-IgG binding to AQP4 and inhibitors of granulocyte function. However, much work remains in understanding the unique susceptibility of the optic nerves in NMO, in developing animal models of NMO optic neuritis, and in improving therapies to preserve vision.
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Affiliation(s)
- Marc H Levin
- Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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