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Hammadi S, Tzoumas N, Ferrara M, Meschede IP, Lo K, Harris C, Lako M, Steel DH. Bruch's Membrane: A Key Consideration with Complement-Based Therapies for Age-Related Macular Degeneration. J Clin Med 2023; 12:2870. [PMID: 37109207 PMCID: PMC10145879 DOI: 10.3390/jcm12082870] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/29/2023] [Accepted: 04/03/2023] [Indexed: 04/29/2023] Open
Abstract
The complement system is crucial for immune surveillance, providing the body's first line of defence against pathogens. However, an imbalance in its regulators can lead to inappropriate overactivation, resulting in diseases such as age-related macular degeneration (AMD), a leading cause of irreversible blindness globally affecting around 200 million people. Complement activation in AMD is believed to begin in the choriocapillaris, but it also plays a critical role in the subretinal and retinal pigment epithelium (RPE) spaces. Bruch's membrane (BrM) acts as a barrier between the retina/RPE and choroid, hindering complement protein diffusion. This impediment increases with age and AMD, leading to compartmentalisation of complement activation. In this review, we comprehensively examine the structure and function of BrM, including its age-related changes visible through in vivo imaging, and the consequences of complement dysfunction on AMD pathogenesis. We also explore the potential and limitations of various delivery routes (systemic, intravitreal, subretinal, and suprachoroidal) for safe and effective delivery of conventional and gene therapy-based complement inhibitors to treat AMD. Further research is needed to understand the diffusion of complement proteins across BrM and optimise therapeutic delivery to the retina.
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Affiliation(s)
- Sarah Hammadi
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Nikolaos Tzoumas
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Sunderland Eye Infirmary, Queen Alexandra Rd., Sunderland SR2 9H, UK
| | | | - Ingrid Porpino Meschede
- Gyroscope Therapeutics Limited, a Novartis Company, Rolling Stock Yard, 6th Floor, 188 York Way, London N7 9AS, UK
| | - Katharina Lo
- Gyroscope Therapeutics Limited, a Novartis Company, Rolling Stock Yard, 6th Floor, 188 York Way, London N7 9AS, UK
| | - Claire Harris
- Gyroscope Therapeutics Limited, a Novartis Company, Rolling Stock Yard, 6th Floor, 188 York Way, London N7 9AS, UK
- Clinical and Translational Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Majlinda Lako
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - David H. Steel
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Sunderland Eye Infirmary, Queen Alexandra Rd., Sunderland SR2 9H, UK
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Dreismann AK, Hallam TM, Tam LC, Nguyen CV, Hughes JP, Ellis S, Harris CL. Gene targeting as a therapeutic avenue in diseases mediated by the complement alternative pathway. Immunol Rev 2023; 313:402-419. [PMID: 36369963 PMCID: PMC10099504 DOI: 10.1111/imr.13149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The complement alternative pathway (AP) is implicated in numerous diseases affecting many organs, ranging from the rare hematological disease paroxysmal nocturnal hemoglobinuria (PNH), to the common blinding disease age-related macular degeneration (AMD). Critically, the AP amplifies any activating trigger driving a downstream inflammatory response; thus, components of the pathway have become targets for drugs of varying modality. Recent validation from clinical trials using drug modalities such as inhibitory antibodies has paved the path for gene targeting of the AP or downstream effectors. Gene targeting in the complement field currently focuses on supplementation or suppression of complement regulators in AMD and PNH, largely because the eye and liver are highly amenable to drug delivery through local (eye) or systemic (liver) routes. Targeting the liver could facilitate treatment of numerous diseases as this organ generates most of the systemic complement pool. This review explains key concepts of RNA and DNA targeting and discusses assets in clinical development for the treatment of diseases driven by the alternative pathway, including the RNA-targeting therapeutics ALN-CC5, ARO-C3, and IONIS-FB-LRX, and the gene therapies GT005 and HMR59. These therapies are but the spearhead of potential drug candidates that might revolutionize the field in coming years.
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Kumar-Singh R. The role of complement membrane attack complex in dry and wet AMD - From hypothesis to clinical trials. Exp Eye Res 2019; 184:266-277. [PMID: 31082363 DOI: 10.1016/j.exer.2019.05.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 05/06/2019] [Accepted: 05/09/2019] [Indexed: 12/12/2022]
Abstract
Data from human dry and wet age-related macular degeneration (AMD) eyes support the hypothesis that constant 'tickover' of the alternative complement pathway results in chronic deposition of the complement membrane attack complex (MAC) on the choriocapillaris and the retinal pigment epithelium (RPE). Sub-lytic levels of MAC lead to cell signaling associated with tissue remodeling and the production of cytokines and inflammatory molecules. Lytic levels of MAC lead to cell death. CD59 is a naturally occurring inhibitor of the assembly of MAC. CD59 may thus be therapeutically efficacious against the pathophysiology of dry and wet AMD. The first gene therapy clinical trial for geographic atrophy - the advanced form of dry AMD has recently completed recruitment. This trial is studying the safety and tolerability of expressing CD59 from an adeno-associated virus (AAV) vector injected once into the vitreous. A second clinical trial assessing the efficacy of CD59 in wet AMD patients is also under way. Herein, the evidence for the role of MAC in the pathophysiology of dry as well as wet AMD and the scientific rationale underlying the use of AAV- delivered CD59 for the treatment of dry and wet AMD is discussed.
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Affiliation(s)
- Rajendra Kumar-Singh
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA.
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Zeng S, Wen KK, Workalemahu G, Sohn EH, Wu M, Chirco KR, Flamme-Wiese MJ, Liu X, Stone EM, Tucker BA, Mullins RF. Imidazole Compounds for Protecting Choroidal Endothelial Cells from Complement Injury. Sci Rep 2018; 8:13387. [PMID: 30190604 PMCID: PMC6127142 DOI: 10.1038/s41598-018-31846-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 08/28/2018] [Indexed: 02/06/2023] Open
Abstract
Age-related macular degeneration (AMD) is a common, blinding disease associated with increased complement system activity. Eyes with AMD show elevated accumulation of the membrane attack complex (MAC) in the choriocapillaris and degeneration of macular choriocapillaris endothelial cells (ECs). Thus, one could reasonably conclude that the endothelial cell death that occurs in AMD is due to injury by the MAC. We therefore sought to identify strategies for protecting ECs against MAC lysis. RF/6A endothelial cells were pre-incubated with a library of FDA-approved small molecules, followed by incubation with complement intact human serum quantification of cell death. Two closely related molecules identified in the screen, econazole nitrate and miconazole nitrate, were followed in validation and mechanistic studies. Both compounds reduced lysis of choroidal ECs treated with complement-intact serum, across a range of doses from 1 to 100 µM. Cell rescue was confirmed in mouse primary choroidal ECs. Both exosome release and cell surface roughness (assessed using a Holomonitor system) were reduced by drug pretreatment in RF/6A cells, whereas endosome formation increased with both drugs, consistent with imidazole-mediated alterations of cell surface dynamics. The results in the current study provide further proof of principle that small molecules can protect choroidal ECs from MAC-induced cell death and suggest that FDA approved compounds may be beneficial in reducing vascular loss and progression of AMD.
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Affiliation(s)
- Shemin Zeng
- The University of Iowa Institute for Vision Research, Iowa City, USA.,University of Iowa Department of Ophthalmology and Visual Sciences, Iowa City, USA
| | - Kuo-Kuang Wen
- University of Iowa Department of Biochemistry, Iowa City, USA
| | - Grefachew Workalemahu
- The University of Iowa Institute for Vision Research, Iowa City, USA.,University of Iowa Department of Ophthalmology and Visual Sciences, Iowa City, USA
| | - Elliott H Sohn
- The University of Iowa Institute for Vision Research, Iowa City, USA.,University of Iowa Department of Ophthalmology and Visual Sciences, Iowa City, USA
| | - Meng Wu
- University of Iowa Department of Biochemistry, Iowa City, USA
| | - Kathleen R Chirco
- The University of Iowa Institute for Vision Research, Iowa City, USA.,University of Iowa Department of Ophthalmology and Visual Sciences, Iowa City, USA
| | - Miles J Flamme-Wiese
- The University of Iowa Institute for Vision Research, Iowa City, USA.,University of Iowa Department of Ophthalmology and Visual Sciences, Iowa City, USA
| | - Xiuying Liu
- The University of Iowa Institute for Vision Research, Iowa City, USA.,University of Iowa Department of Ophthalmology and Visual Sciences, Iowa City, USA
| | - Edwin M Stone
- The University of Iowa Institute for Vision Research, Iowa City, USA.,University of Iowa Department of Ophthalmology and Visual Sciences, Iowa City, USA
| | - Budd A Tucker
- The University of Iowa Institute for Vision Research, Iowa City, USA.,University of Iowa Department of Ophthalmology and Visual Sciences, Iowa City, USA
| | - Robert F Mullins
- The University of Iowa Institute for Vision Research, Iowa City, USA. .,University of Iowa Department of Ophthalmology and Visual Sciences, Iowa City, USA.
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Abou-El-Hassan H, Zaraket H. Viral-derived complement inhibitors: current status and potential role in immunomodulation. Exp Biol Med (Maywood) 2016; 242:397-410. [PMID: 27798122 DOI: 10.1177/1535370216675772] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The complement system is one of the body's major innate immune defense mechanisms in vertebrates. Its function is to detect foreign bodies and promote their elimination through opsonisation or lysis. Complement proteins play an important role in the immunopathogenesis of several disorders. However, excessive complement activation does not confer more protection but instead leads to several autoimmune and inflammatory diseases. With inappropriate activation of the complement system, activated complement proteins and glycoproteins may damage both healthy and diseased tissues. Development of complement inhibitors represents an effective approach in controlling dysregulated complement activity and reducing disease severity, yet few studies have investigated the nature and role of novel complement inhibitory proteins of viral origin. Viral complement inhibitors have important implications in understanding the importance of complement inhibition and their role as a promising novel therapeutic approach in diseases caused by dysregulated complement function. In this review, we discuss the role and importance of complement inhibitors derived from several viruses in the scope of human inflammatory and autoimmune diseases.
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Affiliation(s)
- Hadi Abou-El-Hassan
- 1 Faculty of Medicine, American University of Beirut Medical Center, Beirut, Lebanon.,2 Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Hassan Zaraket
- 2 Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,3 Department of Experimental Pathology, Immunology, and Microbiology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
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