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Zelek WM, Bevan RJ, Morgan BP. Targeting terminal pathway reduces brain complement activation, amyloid load and synapse loss, and improves cognition in a mouse model of dementia. Brain Behav Immun 2024; 118:355-363. [PMID: 38485063 DOI: 10.1016/j.bbi.2024.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 02/28/2024] [Accepted: 03/11/2024] [Indexed: 03/19/2024] Open
Abstract
Complement is dysregulated in the brain in Alzheimer's Disease and in mouse models of Alzheimer's disease. Each of the complement derived effectors, opsonins, anaphylatoxins and membrane attack complex (MAC), have been implicated as drivers of disease but their relative contributions remain unclarified. Here we have focussed on the MAC, a lytic and pro-inflammatory effector, in the AppNL-G-F mouse amyloidopathy model. To test the role of MAC, we back-crossed to generate AppNL-G-F mice deficient in C7, an essential MAC component. C7 deficiency ablated MAC formation, reduced synapse loss and amyloid load and improved cognition compared to complement-sufficient AppNL-G-F mice at 8-10 months age. Adding back C7 caused increased MAC formation in brain and an acute loss of synapses in C7-deficient AppNL-G-F mice. To explore whether C7 was a viable therapeutic target, a C7-blocking monoclonal antibody was administered systemically for one month in AppNL-G-F mice aged 8-9 months. Treatment reduced brain MAC and amyloid deposition, increased synapse density and improved cognitive performance compared to isotype control-treated AppNL-G-F mice. The findings implicate MAC as a driver of pathology and highlight the potential for complement inhibition at the level of MAC as a therapy in Alzheimer's disease.
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Affiliation(s)
- Wioleta M Zelek
- UK Dementia Research Institute Cardiff and Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, Wales CF14 4XN, United Kingdom.
| | - Ryan J Bevan
- UK Dementia Research Institute Cardiff and Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, Wales CF14 4XN, United Kingdom
| | - Bryan Paul Morgan
- UK Dementia Research Institute Cardiff and Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, Wales CF14 4XN, United Kingdom.
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Lekova E, Zelek WM, Gower D, Spitzfaden C, Osuch IH, John-Morris E, Stach L, Gormley D, Sanderson A, Bridges A, Wear ER, Petit-Frere S, Burden MN, Priest R, Wattam T, Kitchen SJ, Feeney M, Davis S, Morgan BP, Nichols EM. Discovery of functionally distinct anti-C7 monoclonal antibodies and stratification of anti-nicotinic AChR positive Myasthenia Gravis patients. Front Immunol 2022; 13:968206. [PMID: 36148231 PMCID: PMC9486540 DOI: 10.3389/fimmu.2022.968206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 07/19/2022] [Indexed: 11/13/2022] Open
Abstract
Myasthenia Gravis (MG) is mediated by autoantibodies against acetylcholine receptors that cause loss of the receptors in the neuromuscular junction. Eculizumab, a C5-inhibitor, is the only approved treatment for MG that mechanistically addresses complement-mediated loss of nicotinic acetylcholine receptors. It is an expensive drug and was approved despite missing the primary efficacy endpoint in the Phase 3 REGAIN study. There are two observations to highlight. Firstly, further C5 inhibitors are in clinical development, but other terminal pathway proteins, such as C7, have been relatively understudied as therapeutic targets, despite the potential for lower and less frequent dosing. Secondly, given the known heterogenous mechanisms of action of autoantibodies in MG, effective patient stratification in the REGAIN trial may have provided more favorable efficacy readouts. We investigated C7 as a target and assessed the in vitro function, binding epitopes and mechanism of action of three mAbs against C7. We found the mAbs were human, cynomolgus monkey and/or rat cross-reactive and each had a distinct, novel mechanism of C7 inhibition. TPP1820 was effective in preventing experimental MG in rats in both prophylactic and therapeutic dosing regimens. To enable identification of MG patients that are likely to respond to C7 inhibition, we developed a patient stratification assay and showed in a small cohort of MG patients (n=19) that 63% had significant complement activation and C7-dependent loss of AChRs in this in vitro set up. This study provides validation of C7 as a target for treatment of MG and provides a means of identifying patients likely to respond to anti-C7 therapy based on complement-activating properties of patient autoantibodies.
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Affiliation(s)
- Eleonora Lekova
- Immunology Research Unit, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Wioleta M. Zelek
- Division of Infection and Immunity and Dementia Research Institute, Systems Immunity Research Institute, School of Medicine, Cardiff University, Wales, United Kingdom
| | - David Gower
- Medicinal Science and Technology, Biopharm Discovery, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Claus Spitzfaden
- Medicines, Science and Technology, Protein Cellular and Structural Sciences (PCSS) Structural and Biophysical Sciences, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Isabelle H. Osuch
- Immunology Research Unit, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Elen John-Morris
- Immunology Research Unit, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Lasse Stach
- Medicinal Science and Technology, Biopharm Discovery, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Darren Gormley
- Immunology Research Unit, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Andrew Sanderson
- Medicines, Science and Technology, Protein Cellular and Structural Sciences (PCSS) Protein and Cellular Sciences, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Angela Bridges
- Medicines, Science and Technology, Protein Cellular and Structural Sciences (PCSS) Protein and Cellular Sciences, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Elizabeth R. Wear
- Immunology Research Unit, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Sebastien Petit-Frere
- Immunology Research Unit, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Michael N. Burden
- Medicinal Science and Technology, Biopharm Discovery, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Richard Priest
- Medicinal Science and Technology, Biopharm Discovery, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Trevor Wattam
- Medicinal Science and Technology, Biopharm Discovery, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Semra J. Kitchen
- Immunology Research Unit, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Maria Feeney
- Immunology Research Unit, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - Susannah Davis
- Medicinal Science and Technology, Biopharm Discovery, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
| | - B. Paul Morgan
- Division of Infection and Immunity and Dementia Research Institute, Systems Immunity Research Institute, School of Medicine, Cardiff University, Wales, United Kingdom
| | - Eva-Maria Nichols
- Immunology Research Unit, GlaxoSmithKline Research & Development (GSK R&D), Stevenage, United Kingdom
- *Correspondence: Eva-Maria Nichols,
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Terminal complement pathway activation drives synaptic loss in Alzheimer’s disease models. Acta Neuropathol Commun 2022; 10:99. [PMID: 35794654 PMCID: PMC9258209 DOI: 10.1186/s40478-022-01404-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/29/2022] [Indexed: 11/23/2022] Open
Abstract
Complement is involved in developmental synaptic pruning and pathological synapse loss in Alzheimer’s disease. It is posited that C1 binding initiates complement activation on synapses; C3 fragments then tag them for microglial phagocytosis. However, the precise mechanisms of complement-mediated synaptic loss remain unclear, and the role of the lytic membrane attack complex (MAC) is unexplored. We here address several knowledge gaps: (i) is complement activated through to MAC at the synapse? (ii) does MAC contribute to synaptic loss? (iii) can MAC inhibition prevent synaptic loss? Novel methods were developed and optimised to quantify C1q, C3 fragments and MAC in total and regional brain homogenates and synaptoneurosomes from WT and AppNL−G−F Alzheimer’s disease model mouse brains at 3, 6, 9 and 12 months of age. The impact on synapse loss of systemic treatment with a MAC blocking antibody and gene knockout of a MAC component was assessed in Alzheimer’s disease model mice. A significant increase in C1q, C3 fragments and MAC was observed in AppNL−G−F mice compared to controls, increasing with age and severity. Administration of anti-C7 antibody to AppNL−G−F mice modulated synapse loss, reflected by the density of dendritic spines in the vicinity of plaques. Constitutive knockout of C6 significantly reduced synapse loss in 3xTg-AD mice. We demonstrate that complement dysregulation occurs in Alzheimer’s disease mice involving the activation (C1q; C3b/iC3b) and terminal (MAC) pathways in brain areas associated with pathology. Inhibition or ablation of MAC formation reduced synapse loss in two Alzheimer’s disease mouse models, demonstrating that MAC formation is a driver of synapse loss. We suggest that MAC directly damages synapses, analogous to neuromuscular junction destruction in myasthenia gravis.
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