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Zheng X, Wan J, Tan G. The mechanisms of NLRP3 inflammasome/pyroptosis activation and their role in diabetic retinopathy. Front Immunol 2023; 14:1151185. [PMID: 37180116 PMCID: PMC10167027 DOI: 10.3389/fimmu.2023.1151185] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 04/11/2023] [Indexed: 05/15/2023] Open
Abstract
In the working-age population worldwide, diabetic retinopathy (DR), a prevalent complication of diabetes, is the main cause of vision impairment. Chronic low-grade inflammation plays an essential role in DR development. Recently, concerning the pathogenesis of DR, the Nod-Like Receptor Family Pyrin Domain Containing 3 (NLRP3) inflammasome in retinal cells has been determined as a causal factor. In the diabetic eye, the NLRP3 inflammasome is activated by several pathways (such as ROS and ATP). The activation of NPRP3 leads to the secretion of inflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18), and leads to pyroptosis, a rapid inflammatory form of lytic programmed cell death (PCD). Cells that undergo pyroptosis swell and rapture, releasing more inflammatory factors and accelerating DR progression. This review focuses on the mechanisms that activate NLRP3 inflammasome and pyroptosis leading to DR. The present research highlighted some inhibitors of NLRP3/pyroptosis pathways and novel therapeutic measures concerning DR treatment.
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Affiliation(s)
- Xiaoqin Zheng
- Department of Ophthalmology, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Jia Wan
- Department of Orthopedics, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Gang Tan
- Department of Ophthalmology, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, Hunan, China
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Lambuk L, Suhaimi NAA, Sadikan MZ, Jafri AJA, Ahmad S, Nasir NAA, Uskoković V, Kadir R, Mohamud R. Nanoparticles for the treatment of glaucoma-associated neuroinflammation. EYE AND VISION 2022; 9:26. [PMID: 35778750 PMCID: PMC9250254 DOI: 10.1186/s40662-022-00298-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 06/09/2022] [Indexed: 12/03/2022]
Abstract
Recently, a considerable amount of literature has emerged around the theme of neuroinflammation linked to neurodegeneration. Glaucoma is a neurodegenerative disease characterized by visual impairment. Understanding the complex neuroinflammatory processes underlying retinal ganglion cell loss has the potential to improve conventional therapeutic approaches in glaucoma. Due to the presence of multiple barriers that a systemically administered drug has to cross to reach the intraocular space, ocular drug delivery has always been a challenge. Nowadays, studies are focused on improving the current therapies for glaucoma by utilizing nanoparticles as the modes of drug transport across the ocular anatomical and physiological barriers. This review offers some important insights on the therapeutic advancements made in this direction, focusing on the use of nanoparticles loaded with anti-inflammatory and neuroprotective agents in the treatment of glaucoma. The prospect of these novel therapies is discussed in relation to the current therapies to alleviate inflammation in glaucoma, which are being reviewed as well, along with the detailed molecular and cellular mechanisms governing the onset and the progression of the disease.
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Peng B, Xu C, Wang S, Zhang Y, Li W. The Role of Connexin Hemichannels in Inflammatory Diseases. BIOLOGY 2022; 11:biology11020237. [PMID: 35205103 PMCID: PMC8869213 DOI: 10.3390/biology11020237] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 01/28/2022] [Accepted: 02/01/2022] [Indexed: 02/04/2023]
Abstract
The connexin protein family consists of approximately 20 members, and is well recognized as the structural unit of the gap junction channels that perforate the plasma membranes of coupled cells and, thereby, mediate intercellular communication. Gap junctions are assembled by two preexisting hemichannels on the membranes of apposing cells. Non-junctional connexin hemichannels (CxHC) provide a conduit between the cell interior and the extracellular milieu, and are believed to be in a protectively closed state under physiological conditions. The development and characterization of the peptide mimetics of the amino acid sequences of connexins have resulted in the development of a panel of blockers with a higher selectivity for CxHC, which have become important tools for defining the role of CxHC in various biological processes. It is increasingly clear that CxHC can be induced to open by pathogen-associated molecular patterns. The opening of CxHC facilitates the release of damage-associated molecular patterns, a class of endogenous molecules that are critical for the pathogenesis of inflammatory diseases. The blockade of CxHC leads to attenuated inflammation, reduced tissue injury and improved organ function in human and animal models of about thirty inflammatory diseases and disorders. These findings demonstrate that CxHC may contribute to the intensification of inflammation, and serve as a common target in the treatments of various inflammatory diseases. In this review, we provide an update on the progress in the understanding of CxHC, with a focus on the role of these channels in inflammatory diseases.
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Affiliation(s)
| | | | | | - Yijie Zhang
- Correspondence: (Y.Z.); (W.L.); Tel.: +86-13903782431 (Y.Z.); +86-17839250252 (W.L.)
| | - Wei Li
- Correspondence: (Y.Z.); (W.L.); Tel.: +86-13903782431 (Y.Z.); +86-17839250252 (W.L.)
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Mugisho OO, Green CR. The NLRP3 inflammasome in age-related eye disease: Evidence-based connexin hemichannel therapeutics. Exp Eye Res 2021; 215:108911. [PMID: 34958779 DOI: 10.1016/j.exer.2021.108911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/25/2021] [Accepted: 12/21/2021] [Indexed: 12/21/2022]
Abstract
The inflammasome pathway is a fundamental component of the innate immune system, playing a key role especially in chronic age-related eye diseases (AREDs). The inflammasome is of particular interest because it is a common disease pathway that once instigated, can amplify and perpetuate itself leading to chronic inflammation. With aging, it becomes more difficult to shut down inflammation after an insult but the common pathway means that a shared solution may be feasible that could be effective across multiple disease indications. This review focusses on the NLRP3 inflammasome, the most studied and characterized inflammasome in the eye. It describes the two-step signalling required for NLRP3 inflammasome complex activation, and provides evidence for its role in AREDs. In the final section, the article gives an overview of potential NLRP3 inflammasome targeting therapies, before presenting evidence for connexin hemichannel regulators as upstream blockers of inflammasome activation. These have shown therapeutic efficacy in multiple ocular disease models.
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Affiliation(s)
- Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
| | - Colin R Green
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
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Retamal MA, Fernandez-Olivares A, Stehberg J. Over-activated hemichannels: A possible therapeutic target for human diseases. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166232. [PMID: 34363932 DOI: 10.1016/j.bbadis.2021.166232] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/21/2021] [Accepted: 07/26/2021] [Indexed: 12/14/2022]
Abstract
In our body, all the cells are constantly sharing chemical and electrical information with other cells. This intercellular communication allows them to respond in a concerted way to changes in the extracellular milieu. Connexins are transmembrane proteins that have the particularity of forming two types of channels; hemichannels and gap junction channels. Under normal conditions, hemichannels allow the controlled release of signaling molecules to the extracellular milieu. However, under certain pathological conditions, over-activated hemichannels can induce and/or exacerbate symptoms. In the last decade, great efforts have been put into developing new tools that can modulate these over-activated hemichannels. Small molecules, antibodies and mimetic peptides have shown a potential for the treatment of human diseases. In this review, we summarize recent findings in the field of hemichannel modulation via specific tools, and how these tools could improve patient outcome in certain pathological conditions.
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Affiliation(s)
- Mauricio A Retamal
- Universidad del Desarrollo, Programa de Comunicación Celular en Cáncer, Santiago, Chile; Universidad del Desarrollo, Centro de Fisiología Celular e Integrativa, Santiago, Chile.
| | | | - Jimmy Stehberg
- Laboratorio de Neurobiología, Instituto de Ciencias Biomédicas, Facultad de medicina y Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
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Wang J, Bai T, Wang N, Li H, Guo X. Neuroprotective potential of imatinib in global ischemia-reperfusion-induced cerebral injury: possible role of Janus-activated kinase 2/signal transducer and activator of transcription 3 and connexin 43. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2020; 24:11-18. [PMID: 31908570 PMCID: PMC6940502 DOI: 10.4196/kjpp.2020.24.1.11] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 06/18/2019] [Accepted: 06/20/2019] [Indexed: 12/20/2022]
Abstract
The present study was aimed to explore the neuroprotective role of imatinib in global ischemia-reperfusion-induced cerebral injury along with possible mechanisms. Global ischemia was induced in mice by bilateral carotid artery occlusion for 20 min, which was followed by reperfusion for 24 h by restoring the blood flow to the brain. The extent of cerebral injury was assessed after 24 h of global ischemia by measuring the locomotor activity (actophotometer test), motor coordination (inclined beam walking test), neurological severity score, learning and memory (object recognition test) and cerebral infarction (triphenyl tetrazolium chloride stain). Ischemia-reperfusion injury produced significant cerebral infarction, impaired the behavioral parameters and decreased the expression of connexin 43 and phosphorylated signal transducer and activator of transcription 3 (p-STAT3) in the brain. A single dose administration of imatinib (20 and 40 mg/kg) attenuated ischemia-reperfusion-induced behavioral deficits and the extent of cerebral infarction along with the restoration of connexin 43 and p-STAT3 levels. However, administration of AG490, a selective Janus-activated kinase 2 (JAK2)/STAT3 inhibitor, abolished the neuroprotective actions of imatinib and decreased the expression of connexin 43 and p-STAT3. It is concluded that imatinib has the potential of attenuating global ischemia-reperfusion-induced cerebral injury, which may be possibly attributed to activation of JAK2/STAT3 signaling pathway along with the increase in the expression of connexin 43.
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Affiliation(s)
- Jieying Wang
- Department of Pediatrics, Shaanxi Provincial People's Hospital, The Affiliated Hospital of Xi'an Medical University, The Third Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710068, Shaanxi, China
| | - Taomin Bai
- Department of Pediatrics, Shaanxi Provincial People's Hospital, The Affiliated Hospital of Xi'an Medical University, The Third Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710068, Shaanxi, China
| | - Nana Wang
- Central Laboratory, Shaanxi Provincial People's Hospital, The Affiliated Hospital of Xi'an Medical University, The Third Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710068, Shaanxi, China
| | - Hongyan Li
- Department of Pediatrics, Shaanxi Provincial People's Hospital, The Affiliated Hospital of Xi'an Medical University, The Third Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710068, Shaanxi, China
| | - Xiangyang Guo
- Department of Pediatrics, Shaanxi Provincial People's Hospital, The Affiliated Hospital of Xi'an Medical University, The Third Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710068, Shaanxi, China.,Department of Neurology, Xijing Hospital, Air Force Medical University, Xi'an 710032, Shaanxi, China
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Caufriez A, Böck D, Martin C, Ballet S, Vinken M. Peptide-based targeting of connexins and pannexins for therapeutic purposes. Expert Opin Drug Discov 2020; 15:1213-1222. [PMID: 32539572 DOI: 10.1080/17460441.2020.1773787] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
INTRODUCTION Connexin and pannexin (hemi)channels play an important role in paracrine and autocrine signaling pathways. The opening of these cellular pores is linked to a wide range of diseases. Therefore, pharmacological closing of connexin and pannexin (hemi)channels seems a promising therapeutic strategy. However, the currently available inhibitors cope with recurring problems concerning selectivity, specificity, stability and/or solubility. AREAS COVERED A number of peptides that mimic specific regions in the native sequence of connexins and pannexins have the potential to overcome some of these hurdles. In this paper, an overview is provided on these peptide-based inhibitors of connexin and pannexin (hemi)channels for therapeutic purposes. The authors also provide the reader with their expert perspectives on the future of these peptide-based inhibitors. EXPERT OPINION Peptide mimetics can become valuable tools in the treatment of connexin-related and pannexin-related diseases. This can be made possible provided that available peptides are optimized, and new peptide mimetics are designed based on knowledge of the mechanisms underlying the gating control of connexin and pannexin (hemi)channels.
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Affiliation(s)
- Anne Caufriez
- Department of in Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , 1090, Brussels, Belgium
| | - Denise Böck
- Department of in Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , 1090, Brussels, Belgium
| | - Charlotte Martin
- Department of Organic Chemistry, Vrije Universiteit Brussel , 1050, Brussels, Belgium
| | - Steven Ballet
- Department of Organic Chemistry, Vrije Universiteit Brussel , 1050, Brussels, Belgium
| | - Mathieu Vinken
- Department of in Vitro Toxicology and Dermato-Cosmetology, Vrije Universiteit Brussel , 1090, Brussels, Belgium
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Mat Nor MN, Rupenthal ID, Green CR, Acosta ML. Connexin Hemichannel Block Using Orally Delivered Tonabersat Improves Outcomes in Animal Models of Retinal Disease. Neurotherapeutics 2020; 17:371-387. [PMID: 31637594 PMCID: PMC7007471 DOI: 10.1007/s13311-019-00786-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Increased Connexin43 hemichannel opening is associated with inflammasome pathway activation and inflammation in a range of pathologies including ocular disorders, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). In this study, the effect on retinal function and morphology of clinically safe doses of orally delivered tonabersat, a small molecule connexin hemichannel blocker, was investigated in the light-damaged retina animal model of dry AMD and in a spontaneous rat model of DR. Clinical parameters (fundus imaging, optical coherence tomography (OCT), and electroretinography) and inflammatory markers (immunohistochemistry for Iba-1 microglial marker, astrocyte marker glial fibrillary acidic protein, and Connexin43 protein expression) were assessed. Tonabersat treatment reduced inflammation in the retina in parallel with preservation of retinal photoreceptor function when assessed up to 3 months post light damage in the dry AMD model. In the DR model, clinical signs, including the presence of aneurysms confirmed using Evans blue dye perfusion, were reduced after daily tonabersat treatment for 2 weeks. Inflammation was also reduced and retinal electrical function restored. Tonabersat regulates assembly of the inflammasome (NLRP3) through Connexin43 hemichannel block, with the potential to reduce inflammation, restore vascular integrity and improve anatomical along with some functional outcomes in retinal disease.
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Affiliation(s)
- Mohd Nasir Mat Nor
- School of Optometry and Vision Science and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
- Faculty of Medicine, University of Sultan Zainal Abidin, Kuala Terengganu, Malaysia
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
- Department of Ophthalmology and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Monica L Acosta
- School of Optometry and Vision Science and New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.
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Mugisho OO, Rupenthal ID, Paquet-Durand F, Acosta ML, Green CR. Targeting connexin hemichannels to control the inflammasome: the correlation between connexin43 and NLRP3 expression in chronic eye disease. Expert Opin Ther Targets 2019; 23:855-863. [PMID: 31554417 DOI: 10.1080/14728222.2019.1673368] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Introduction: Chronic inflammatory diseases, including retinal diseases that are a major cause of vision loss, are associated with activation of the nucleotide-binding domain and leucine-rich repeat containing (NLR) protein-3 (NLRP3) inflammasome pathway. In chronic disease, the inflammasome becomes self-perpetuating, indicating a common pathway in such diseases irrespective of underlying etiology, and implying a shared solution is feasible. Connexin43 hemichannels correlate directly with NLRP3 inflammasome complex assembly (shown here in models of retinal disease). Connexin43 hemichannel-mediated ATP release is proposed to be the principal activator signal for inflammasome complex assembly in primary signal-sensitized cells. Connexin hemichannel block on its own is sufficient to inhibit the inflammasome pathway. Areas covered: We introduce chronic retinal disease, discuss available preclinical models and examine findings from these models regarding the targeting of connexin43 hemichannels and its effects on the inflammasome. Expert opinion: In over 25 animal disease models, connexin hemichannel regulation has shown therapeutic benefit, and one oral connexin hemichannel blocker, tonabersat (Xiflam), is Phase II ready with safety evidence in over 1000 patients. Regulating the connexin hemichannel provides a means to move quickly into clinical trials designed to ameliorate the progression of devastating chronic diseases of the eye, but also elsewhere in the body.
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Affiliation(s)
- Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland , New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland , New Zealand
| | - Francois Paquet-Durand
- Cell Death Mechanisms Lab, Institute for Ophthalmic Research, University of Tübingen , Tübingen , Germany
| | - Monica L Acosta
- School of Optometry and Vision Science and the New Zealand National Eye Centre, University of Auckland , Auckland , New Zealand
| | - Colin R Green
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland , Auckland , New Zealand
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Hernández-Guerra M, Hadjihambi A, Jalan R. Gap junctions in liver disease: Implications for pathogenesis and therapy. J Hepatol 2019; 70:759-772. [PMID: 30599172 DOI: 10.1016/j.jhep.2018.12.023] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Revised: 12/03/2018] [Accepted: 12/12/2018] [Indexed: 02/07/2023]
Abstract
In the normal liver, cells interact closely through gap junctions. By providing a pathway for the trafficking of low molecular mass molecules, these channels contribute to tissue homeostasis and maintenance of hepatic function. Thus, dysfunction of gap junctions affects a wide variety of liver processes, such as differentiation, cell death, inflammation and fibrosis. In fact, dysfunctional gap junctions have been implicated, for more than a decade, in cholestatic disease, hepatic cancer and cirrhosis. Additionally, in recent years there is an increasing body of evidence that these channels are also involved in other relevant and prevalent liver pathological processes, such as non-alcoholic fatty liver disease, acute liver injury and portal hypertension. In parallel to these new clinical implications the available data include controversial observations. Thus, a comprehensive overview is required to better understand the functional complexity of these pores. This paper will review the most recent knowledge concerning gap junction dysfunction, with a special focus on the role of these channels in the pathogenesis of relevant clinical entities and on potential therapeutic targets that are amenable to modification by drugs.
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Affiliation(s)
| | | | - Rajiv Jalan
- UCL Institute for Liver and Digestive Health, Royal Free Medical School, London, UK
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Mugisho OO, Green CR, Zhang J, Acosta ML, Rupenthal ID. Connexin43 hemichannels: A potential drug target for the treatment of diabetic retinopathy. Drug Discov Today 2019; 24:1627-1636. [PMID: 30690195 DOI: 10.1016/j.drudis.2019.01.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 01/17/2019] [Accepted: 01/17/2019] [Indexed: 02/07/2023]
Abstract
Diabetic retinopathy (DR) is a chronic vascular disease of the retina that causes vision loss in patients with type 1 and type 2 diabetes, and is associated with vascular dysfunction and occlusion, retinal oedema, haemorrhage and inadequate growth of new blood vessels. Current DR therapies primarily target downstream, later-stage vascular defects with a significant proportion of diabetic macular oedema patients being non-responders. Moreover, other evidence suggests that prolonged use of therapies targeting vascular endothelial growth factor (VEGF) might be associated with increased onset of geographic atrophy and retinal ganglion cell death. It is therefore highly desirable to prevent the onset of DR or arrest its progression at a stage preceding the appearance of more-advanced pathology by targeting upstream disease mechanisms. Connexin43 hemichannels play a part in the pathogenesis of chronic inflammatory diseases, including inflammasome pathway activation; and hemichannel block has been shown to alleviate vascular leak and inflammation. This review discusses the inflammatory changes occurring in DR as well as current therapies and their limitations. It then focuses on the role of connexin43 in DR, providing evidence for the utility of connexin43 hemichannel blockers as novel therapeutics for DR treatment.
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Affiliation(s)
- Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Jie Zhang
- Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Monica L Acosta
- School of Optometry and Vision Science and the New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology and the New Zealand National Eye Centre, University of Auckland, New Zealand.
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Connexin43 hemichannel block protects against the development of diabetic retinopathy signs in a mouse model of the disease. J Mol Med (Berl) 2018; 97:215-229. [DOI: 10.1007/s00109-018-1727-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 11/25/2018] [Accepted: 11/30/2018] [Indexed: 12/22/2022]
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Therapeutic Targeting of Connexin Channels: New Views and Challenges. Trends Mol Med 2018; 24:1036-1053. [PMID: 30424929 DOI: 10.1016/j.molmed.2018.10.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/09/2018] [Accepted: 10/11/2018] [Indexed: 12/22/2022]
Abstract
Connexins, in particular connexin 43 (Cx43), function as gap junction channels (GJCs) and hemichannels (HCs). Only recently, specific tools have been developed to study their pleiotropic functions. Based on various protein interaction sites, distinct connexin-mimetic peptides have been established that enable discrimination between the function of HCs and GJCs. Although the precise mechanism of action of most of these peptides is still a matter of debate, an increasing number of studies report on important effects of those compounds in disease models. In this review, we summarize the structure, life cycle, and the most important physiological and pathological functions of both connexin GJCs and HCs. We provide a critical overview on the use of connexin-targeting peptides, in particular targeting Cx43, with a special focus on the remaining questions and hurdles to be taken in the research field of connexin channels.
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Abstract
The connexin family of channel-forming proteins is present in every tissue type in the human anatomy. Connexins are best known for forming clustered intercellular channels, structurally known as gap junctions, where they serve to exchange members of the metabolome between adjacent cells. In their single-membrane hemichannel form, connexins can act as conduits for the passage of small molecules in autocrine and paracrine signalling. Here, we review the roles of connexins in health and disease, focusing on the potential of connexins as therapeutic targets in acquired and inherited diseases as well as wound repair, while highlighting the associated clinical challenges.
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Mugisho OO, Green CR, Kho DT, Zhang J, Graham ES, Acosta ML, Rupenthal ID. The inflammasome pathway is amplified and perpetuated in an autocrine manner through connexin43 hemichannel mediated ATP release. Biochim Biophys Acta Gen Subj 2018; 1862:385-393. [DOI: 10.1016/j.bbagen.2017.11.015] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/30/2017] [Accepted: 11/16/2017] [Indexed: 12/20/2022]
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16
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Ziaei M, Greene C, Green CR. Wound healing in the eye: Therapeutic prospects. Adv Drug Deliv Rev 2018; 126:162-176. [PMID: 29355667 DOI: 10.1016/j.addr.2018.01.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 10/06/2017] [Accepted: 01/10/2018] [Indexed: 02/07/2023]
Abstract
In order to maintain a smooth optical surface the corneal epithelium has to continuously renew itself so as to maintain its function as a barrier to fluctuating external surroundings and various environmental insults. After trauma, the cornea typically re-epithelializes promptly thereby minimizing the risk of infection, opacification or perforation. A persistent epithelial defect (PED) is usually referred to as a non-healing epithelial lesion after approximately two weeks of treatment with standard therapies to no avail. They occur following exposure to toxic agents, mechanical injury, and ocular surface infections and are associated with significant clinical morbidity in patients, resulting in discomfort or visual loss. In the case of deeper corneal injury and corneal pathology the wound healing cascade can also extend to the corneal stroma, the layer below the epithelium. Although significant progress has been made in recent years, pharmaco-therapeutic agents that promote corneal healing remain limited. This article serves as a review of current standard therapies, recently introduced alternative therapies gaining in popularity, and a look into the newest developments into ocular wound healing.
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Willebrords J, Maes M, Crespo Yanguas S, Vinken M. Inhibitors of connexin and pannexin channels as potential therapeutics. Pharmacol Ther 2017; 180:144-160. [PMID: 28720428 PMCID: PMC5802387 DOI: 10.1016/j.pharmthera.2017.07.001] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
While gap junctions support the exchange of a number of molecules between neighboring cells, connexin hemichannels provide communication between the cytosol and the extracellular environment of an individual cell. The latter equally holds true for channels composed of pannexin proteins, which display an architecture reminiscent of connexin hemichannels. In physiological conditions, gap junctions are usually open, while connexin hemichannels and, to a lesser extent, pannexin channels are typically closed, yet they can be activated by a number of pathological triggers. Several agents are available to inhibit channels built up by connexin and pannexin proteins, including alcoholic substances, glycyrrhetinic acid, anesthetics and fatty acids. These compounds not always strictly distinguish between gap junctions, connexin hemichannels and pannexin channels, and may have effects on other targets as well. An exception lies with mimetic peptides, which reproduce specific amino acid sequences in connexin or pannexin primary protein structure. In this paper, a state-of-the-art overview is provided on inhibitors of cellular channels consisting of connexins and pannexins with specific focus on their mode-of-action and therapeutic potential.
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Affiliation(s)
- Joost Willebrords
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
| | - Michaël Maes
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
| | - Sara Crespo Yanguas
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium
| | - Mathieu Vinken
- Department of In Vitro Toxicology and Dermato-cosmetology, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, Brussels, Belgium.
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Mugisho OO, Green CR, Zhang J, Binz N, Acosta ML, Rakoczy E, Rupenthal ID. Immunohistochemical Characterization of Connexin43 Expression in a Mouse Model of Diabetic Retinopathy and in Human Donor Retinas. Int J Mol Sci 2017; 18:ijms18122567. [PMID: 29186067 PMCID: PMC5751170 DOI: 10.3390/ijms18122567] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 11/21/2017] [Accepted: 11/24/2017] [Indexed: 12/25/2022] Open
Abstract
Diabetic retinopathy (DR) develops due to hyperglycemia and inflammation-induced vascular disruptions in the retina with connexin43 expression patterns in the disease still debated. Here, the effects of hyperglycemia and inflammation on connexin43 expression in vitro in a mouse model of DR and in human donor tissues were evaluated. Primary human retinal microvascular endothelial cells (hRMECs) were exposed to high glucose (HG; 25 mM) or pro-inflammatory cytokines IL-1β and TNF-α (10 ng/mL each) or both before assessing connexin43 expression. Additionally, connexin43, glial fibrillary acidic protein (GFAP), and plasmalemma vesicular associated protein (PLVAP) were labeled in wild-type (C57BL/6), Akita (diabetic), and Akimba (DR) mouse retinas. Finally, connexin43 and GFAP expression in donor retinas with confirmed DR was compared to age-matched controls. Co-application of HG and cytokines increased connexin43 expression in hRMECs in line with results seen in mice, with no significant difference in connexin43 or GFAP expression in Akita but higher expression in Akimba compared to wild-type mice. On PLVAP-positive vessels, connexin43 was higher in Akimba but unchanged in Akita compared to wild-type mice. Connexin43 expression appeared higher in donor retinas with confirmed DR compared to age-matched controls, similar to the distribution seen in Akimba mice and correlating with the in vitro results. Although connexin43 expression seems reduced in diabetes, hyperglycemia and inflammation present in the pathology of DR seem to increase connexin43 expression, suggesting a causal role of connexin43 channels in the disease progression.
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Affiliation(s)
- Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
- School of Optometry and Vision Science, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
| | - Colin R Green
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
| | - Jie Zhang
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
| | - Nicolette Binz
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth 6009, Western Australia, Australia.
| | - Monica L Acosta
- School of Optometry and Vision Science, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
| | - Elizabeth Rakoczy
- Centre for Ophthalmology and Visual Science, University of Western Australia, Perth 6009, Western Australia, Australia.
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland 1142, New Zealand.
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19
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Ribeiro-Rodrigues TM, Martins-Marques T, Morel S, Kwak BR, Girão H. Role of connexin 43 in different forms of intercellular communication - gap junctions, extracellular vesicles and tunnelling nanotubes. J Cell Sci 2017; 130:3619-3630. [PMID: 29025971 DOI: 10.1242/jcs.200667] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Communication is important to ensure the correct and efficient flow of information, which is required to sustain active social networks. A fine-tuned communication between cells is vital to maintain the homeostasis and function of multicellular or unicellular organisms in a community environment. Although there are different levels of complexity, intercellular communication, in prokaryotes to mammalians, can occur through secreted molecules (either soluble or encapsulated in vesicles), tubular structures connecting close cells or intercellular channels that link the cytoplasm of adjacent cells. In mammals, these different types of communication serve different purposes, may involve distinct factors and are mediated by extracellular vesicles, tunnelling nanotubes or gap junctions. Recent studies have shown that connexin 43 (Cx43, also known as GJA1), a transmembrane protein initially described as a gap junction protein, participates in all these forms of communication; this emphasizes the concept of adopting strategies to maximize the potential of available resources by reutilizing the same factor in different scenarios. In this Review, we provide an overview of the most recent advances regarding the role of Cx43 in intercellular communication mediated by extracellular vesicles, tunnelling nanotubes and gap junctions.
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Affiliation(s)
- Teresa M Ribeiro-Rodrigues
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-548 Coimbra, Portugal.,CNC.IBILI, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Tânia Martins-Marques
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-548 Coimbra, Portugal.,CNC.IBILI, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Sandrine Morel
- Dept. of Pathology and Immunology, and Dept. of Medical Specialties - Cardiology, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
| | - Brenda R Kwak
- Dept. of Pathology and Immunology, and Dept. of Medical Specialties - Cardiology, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
| | - Henrique Girão
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Azinhaga de Sta Comba, 3000-548 Coimbra, Portugal .,CNC.IBILI, University of Coimbra, 3000-548 Coimbra, Portugal
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20
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Leybaert L, Lampe PD, Dhein S, Kwak BR, Ferdinandy P, Beyer EC, Laird DW, Naus CC, Green CR, Schulz R. Connexins in Cardiovascular and Neurovascular Health and Disease: Pharmacological Implications. Pharmacol Rev 2017; 69:396-478. [PMID: 28931622 PMCID: PMC5612248 DOI: 10.1124/pr.115.012062] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Connexins are ubiquitous channel forming proteins that assemble as plasma membrane hemichannels and as intercellular gap junction channels that directly connect cells. In the heart, gap junction channels electrically connect myocytes and specialized conductive tissues to coordinate the atrial and ventricular contraction/relaxation cycles and pump function. In blood vessels, these channels facilitate long-distance endothelial cell communication, synchronize smooth muscle cell contraction, and support endothelial-smooth muscle cell communication. In the central nervous system they form cellular syncytia and coordinate neural function. Gap junction channels are normally open and hemichannels are normally closed, but pathologic conditions may restrict gap junction communication and promote hemichannel opening, thereby disturbing a delicate cellular communication balance. Until recently, most connexin-targeting agents exhibited little specificity and several off-target effects. Recent work with peptide-based approaches has demonstrated improved specificity and opened avenues for a more rational approach toward independently modulating the function of gap junctions and hemichannels. We here review the role of connexins and their channels in cardiovascular and neurovascular health and disease, focusing on crucial regulatory aspects and identification of potential targets to modify their function. We conclude that peptide-based investigations have raised several new opportunities for interfering with connexins and their channels that may soon allow preservation of gap junction communication, inhibition of hemichannel opening, and mitigation of inflammatory signaling.
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Affiliation(s)
- Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Paul D Lampe
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Stefan Dhein
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Brenda R Kwak
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Peter Ferdinandy
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Eric C Beyer
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Dale W Laird
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Christian C Naus
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Colin R Green
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
| | - Rainer Schulz
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium (L.L.); Translational Research Program, Fred Hutchinson Cancer Research Center, Seattle, Washington (P.D.L.); Institute for Pharmacology, University of Leipzig, Leipzig, Germany (S.D.); Department of Pathology and Immunology, Department of Medical Specialization-Cardiology, University of Geneva, Geneva, Switzerland (B.R.K.); Department of Pharmacology and Pharmacotherapy, Semmelweis University, Budapest, Hungary (P.F.); Pharmahungary Group, Szeged, Hungary (P.F.); Department of Pediatrics, University of Chicago, Chicago, Illinois (E.C.B.); Department of Anatomy and Cell Biology, University of Western Ontario, Dental Science Building, London, Ontario, Canada (D.W.L.); Cellular and Physiological Sciences, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada (C.C.N.); Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand (C.R.G.); and Physiologisches Institut, Justus-Liebig-Universität Giessen, Giessen, Germany (R.S.)
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21
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Mao Y, Nguyen T, Tonkin RS, Lees JG, Warren C, O'Carroll SJ, Nicholson LFB, Green CR, Moalem-Taylor G, Gorrie CA. Characterisation of Peptide5 systemic administration for treating traumatic spinal cord injured rats. Exp Brain Res 2017; 235:3033-3048. [PMID: 28725925 DOI: 10.1007/s00221-017-5023-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/03/2017] [Indexed: 11/27/2022]
Abstract
Systemic administration of a Connexin43 mimetic peptide, Peptide5, has been shown to reduce secondary tissue damage and improve functional recovery after spinal cord injury (SCI). This study investigated safety measures and potential off-target effects of Peptide5 systemic administration. Rats were subjected to a mild contusion SCI using the New York University impactor. One cohort was injected intraperitoneally with a single dose of fluorescently labelled Peptide5 and euthanised at 2 or 4 h post-injury for peptide distribution analysis. A second cohort received intraperitoneal injections of Peptide5 or a scrambled peptide and was culled at 8 or 24 h post-injury for the analysis of connexin proteins and systemic cytokine profile. We found that Peptide5 did not cross the blood-spinal cord barrier in control animals, but reached the lesion area in the spinal cord-injured animals without entering non-injured tissue. There was no evidence that the systemic administration of Peptide5 modulates Connexin43 protein expression or hemichannel closure in the heart and lung tissue of SCI animals. The expression levels of other major connexin proteins including Connexin30 in astrocytes, Connexin36 in neurons and Connexin47 in oligodendrocytes were also unaltered by systemic delivery of Peptide5 in either the injured or non-injured spinal cords. In addition, systemic delivery of Peptide5 had no significant effect on the plasma levels of cytokines, chemokines or growth factors. These data indicate that the systemic delivery of Peptide5 is unlikely to cause any off-target or adverse effects and may thus be a safe treatment option for traumatic SCI.
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Affiliation(s)
- Yilin Mao
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Tara Nguyen
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Ryan S Tonkin
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Justin G Lees
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Caitlyn Warren
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Simon J O'Carroll
- Department of Anatomy and Medical Imaging and The Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Louise F B Nicholson
- Department of Anatomy and Medical Imaging and The Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Colin R Green
- Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Gila Moalem-Taylor
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Catherine A Gorrie
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia.
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22
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Roy S, Jiang JX, Li AF, Kim D. Connexin channel and its role in diabetic retinopathy. Prog Retin Eye Res 2017; 61:35-59. [PMID: 28602949 DOI: 10.1016/j.preteyeres.2017.06.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 05/30/2017] [Accepted: 06/02/2017] [Indexed: 12/18/2022]
Abstract
Diabetic retinopathy is the leading cause of blindness in the working age population. Unfortunately, there is no cure for this devastating ocular complication. The early stage of diabetic retinopathy is characterized by the loss of various cell types in the retina, namely endothelial cells and pericytes. As the disease progresses, vascular leakage, a clinical hallmark of diabetic retinopathy, becomes evident and may eventually lead to diabetic macular edema, the most common cause of vision loss in diabetic retinopathy. Substantial evidence indicates that the disruption of connexin-mediated cellular communication plays a critical role in the pathogenesis of diabetic retinopathy. Yet, it is unclear how altered communication via connexin channel mediated cell-to-cell and cell-to-extracellular microenvironment is linked to the development of diabetic retinopathy. Recent observations suggest the possibility that connexin hemichannels may play a role in the pathogenesis of diabetic retinopathy by allowing communication between cells and the microenvironment. Interestingly, recent studies suggest that connexin channels may be involved in regulating retinal vascular permeability. These cellular events are coordinated at least in part via connexin-mediated intercellular communication and the maintenance of retinal vascular homeostasis. This review highlights the effect of high glucose and diabetic condition on connexin channels and their impact on the development of diabetic retinopathy.
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Affiliation(s)
- Sayon Roy
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States.
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - An-Fei Li
- Department of Ophthalmology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan
| | - Dongjoon Kim
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States
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23
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Wu D, Wang J, Wang H, Ji A, Li Y. Protective roles of bioactive peptides during ischemia-reperfusion injury: From bench to bedside. Life Sci 2017; 180:83-92. [PMID: 28527782 DOI: 10.1016/j.lfs.2017.05.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 05/09/2017] [Accepted: 05/10/2017] [Indexed: 12/14/2022]
Abstract
Ischemia-reperfusion (I/R) is a well-known pathological condition which may lead to disability and mortality. I/R injury remains an unresolved and complicated situation in a number of clinical conditions, such as cardiac arrest with successful reanimation, as well as ischemic events in brain and heart. Peptides have many attractive advantages which make them suitable candidate drugs in treating I/R injury, such as low toxicity and immunogenicity, good solubility property, distinct tissue distribution pattern, and favorable pharmacokinetic profile. An increasing number of studies indicate that peptides could protect against I/R injury in many different organs and tissues. Peptides also face several therapeutic challenges that limit their clinical application. In this review, we present the mechanisms of action of peptides in reducing I/R injury, as well as further discuss modification strategies to improve the functional properties of bioactive peptides.
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Affiliation(s)
- Dongdong Wu
- Henan University School of Basic Medical Sciences, Kaifeng 475004, Henan, China; Institute of Environmental Medicine, Henan University, Kaifeng 475004, Henan, China
| | - Jun Wang
- Henan University School of Basic Medical Sciences, Kaifeng 475004, Henan, China; Institute of Environmental Medicine, Henan University, Kaifeng 475004, Henan, China
| | - Honggang Wang
- Henan University School of Basic Medical Sciences, Kaifeng 475004, Henan, China; Institute of Environmental Medicine, Henan University, Kaifeng 475004, Henan, China
| | - Ailing Ji
- Henan University School of Basic Medical Sciences, Kaifeng 475004, Henan, China; Institute of Environmental Medicine, Henan University, Kaifeng 475004, Henan, China.
| | - Yanzhang Li
- Henan University School of Basic Medical Sciences, Kaifeng 475004, Henan, China; Institute of Environmental Medicine, Henan University, Kaifeng 475004, Henan, China.
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24
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Kim Y, Davidson JO, Green CR, Nicholson LFB, O'Carroll SJ, Zhang J. Connexins and Pannexins in cerebral ischemia. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:224-236. [PMID: 28347700 DOI: 10.1016/j.bbamem.2017.03.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/24/2017] [Accepted: 03/22/2017] [Indexed: 12/12/2022]
Abstract
A common cause of mortality and long-term adult disability, cerebral ischemia or brain ischemia imposes a significant health and financial burden on communities worldwide. Cerebral ischemia is a condition that arises from a sudden loss of blood flow and consequent failure to meet the high metabolic demands of the brain. The lack of blood flow initiates a sequelae of cell death mechanisms, including the activation of the inflammatory pathway, which can ultimately result in irreversible brain tissue damage. In particular, Connexins and Pannexins are non-selective channels with a large pore that have shown to play time-dependent roles in the perpetuation of ischaemic injury. This review highlights the roles of Connexin and Pannexin channels in cell death mechanisms as a promising therapeutic target in cerebral ischemia, and in particular connexin hemichannels which may contribute most of the ATP release as a result of ischemia as well as during reperfusion. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
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Affiliation(s)
- Yeri Kim
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland
| | - Joanne O Davidson
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland
| | - Colin R Green
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland
| | - Louise F B Nicholson
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland
| | - Simon J O'Carroll
- Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland
| | - Jie Zhang
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland.
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25
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Nguyen CTO, Hui F, Charng J, Velaedan S, van Koeverden AK, Lim JKH, He Z, Wong VHY, Vingrys AJ, Bui BV, Ivarsson M. Retinal biomarkers provide "insight" into cortical pharmacology and disease. Pharmacol Ther 2017; 175:151-177. [PMID: 28174096 DOI: 10.1016/j.pharmthera.2017.02.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The retina is an easily accessible out-pouching of the central nervous system (CNS) and thus lends itself to being a biomarker of the brain. More specifically, the presence of neuronal, vascular and blood-neural barrier parallels in the eye and brain coupled with fast and inexpensive methods to quantify retinal changes make ocular biomarkers an attractive option. This includes its utility as a biomarker for a number of cerebrovascular diseases as well as a drug pharmacology and safety biomarker for the CNS. It is a rapidly emerging field, with some areas well established, such as stroke risk and multiple sclerosis, whereas others are still in development (Alzheimer's, Parkinson's, psychological disease and cortical diabetic dysfunction). The current applications and future potential of retinal biomarkers, including potential ways to improve their sensitivity and specificity are discussed. This review summarises the existing literature and provides a perspective on the strength of current retinal biomarkers and their future potential.
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Affiliation(s)
- Christine T O Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia.
| | - Flora Hui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Jason Charng
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Shajan Velaedan
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Anna K van Koeverden
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Jeremiah K H Lim
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Zheng He
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Algis J Vingrys
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Magnus Ivarsson
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, 3010, Victoria, Australia
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26
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Mao Y, Tonkin RS, Nguyen T, O'Carroll SJ, Nicholson LFB, Green CR, Moalem-Taylor G, Gorrie CA. Systemic Administration of Connexin43 Mimetic Peptide Improves Functional Recovery after Traumatic Spinal Cord Injury in Adult Rats. J Neurotrauma 2017; 34:707-719. [DOI: 10.1089/neu.2016.4625] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Yilin Mao
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Ryan S. Tonkin
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Tara Nguyen
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, New South Wales, Australia
| | - Simon J. O'Carroll
- Department of Anatomy and Medical Imaging and the Centre for Brain Research, University of Auckland, Grafton, Auckland, New Zealand
| | - Louise F. B. Nicholson
- Department of Anatomy and Medical Imaging and the Centre for Brain Research, University of Auckland, Grafton, Auckland, New Zealand
| | - Colin R. Green
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland, Grafton, Auckland, New Zealand
| | - Gila Moalem-Taylor
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia
| | - Catherine A. Gorrie
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, Sydney, New South Wales, Australia
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27
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Willebrords J, Crespo Yanguas S, Maes M, Decrock E, Wang N, Leybaert L, Kwak BR, Green CR, Cogliati B, Vinken M. Connexins and their channels in inflammation. Crit Rev Biochem Mol Biol 2016; 51:413-439. [PMID: 27387655 PMCID: PMC5584657 DOI: 10.1080/10409238.2016.1204980] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Inflammation may be caused by a variety of factors and is a hallmark of a plethora of acute and chronic diseases. The purpose of inflammation is to eliminate the initial cell injury trigger, to clear out dead cells from damaged tissue and to initiate tissue regeneration. Despite the wealth of knowledge regarding the involvement of cellular communication in inflammation, studies on the role of connexin-based channels in this process have only begun to emerge in the last few years. In this paper, a state-of-the-art overview of the effects of inflammation on connexin signaling is provided. Vice versa, the involvement of connexins and their channels in inflammation will be discussed by relying on studies that use a variety of experimental tools, such as genetically modified animals, small interfering RNA and connexin-based channel blockers. A better understanding of the importance of connexin signaling in inflammation may open up towards clinical perspectives.
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Affiliation(s)
- Joost Willebrords
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
| | - Sara Crespo Yanguas
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
| | - Michaël Maes
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology Group, Ghent
University, De Pintelaan 185, 9000 Ghent, Belgium; Elke Decrock: Tel: +32 9 332 39
73, Nan Wang: Tel: +32 9 332 39 38, Luc Leybaert: Tel: +32 9 332 33 66
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology Group, Ghent
University, De Pintelaan 185, 9000 Ghent, Belgium; Elke Decrock: Tel: +32 9 332 39
73, Nan Wang: Tel: +32 9 332 39 38, Luc Leybaert: Tel: +32 9 332 33 66
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology Group, Ghent
University, De Pintelaan 185, 9000 Ghent, Belgium; Elke Decrock: Tel: +32 9 332 39
73, Nan Wang: Tel: +32 9 332 39 38, Luc Leybaert: Tel: +32 9 332 33 66
| | - Brenda R. Kwak
- Department of Pathology and Immunology and Division of Cardiology,
University of Geneva, Rue Michel-Servet 1, CH-1211 Geneva, Switzerland; Brenda R.
Kwak: Tel: +41 22 379 57 37
| | - Colin R. Green
- Department of Ophthalmology and New Zealand National Eye Centre,
University of Auckland, New Zealand; Colin R. Green: Tel: +64 9 923 61 35
| | - Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal
Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva 87,
05508-270 São Paulo, Brazil; Bruno Cogliati: Tel: +55 11 30 91 12 00
| | - Mathieu Vinken
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
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28
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Becker DL, Phillips AR, Duft BJ, Kim Y, Green CR. Translating connexin biology into therapeutics. Semin Cell Dev Biol 2015; 50:49-58. [PMID: 26688335 DOI: 10.1016/j.semcdb.2015.12.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 12/07/2015] [Indexed: 12/26/2022]
Abstract
It is 45 years since gap junctions were first described. Universities face increasing commercial pressures and declining federal funding, with governments and funding foundations showing greater interest in gaining return on their investments. This review outlines approaches taken to translate gap junction research to clinical application and the challenges faced. The need for commercialisation is discussed and key concepts behind research patenting briefly described. Connexin channel roles in disease and injury are also discussed, as is identification of the connexin hemichannel as a therapeutic target which appears to play a role in both the start and perpetuation of the inflammasome pathway. Furthermore connexin hemichannel opening results in vascular dieback in acute injury and chronic disease. Translation to human indications is illustrated from the perspective of one connexin biotechnology company, CoDa Therapeutics, Inc.
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Affiliation(s)
- David L Becker
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | | | | | - Yeri Kim
- Department of Ophthalmology and New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology and New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, New Zealand.
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