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Cliff CL, Squires PE, Hills CE. Tonabersat suppresses priming/activation of the NOD-like receptor protein-3 (NLRP3) inflammasome and decreases renal tubular epithelial-to-macrophage crosstalk in a model of diabetic kidney disease. Cell Commun Signal 2024; 22:351. [PMID: 38970061 PMCID: PMC11225428 DOI: 10.1186/s12964-024-01728-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 06/26/2024] [Indexed: 07/07/2024] Open
Abstract
BACKGROUND Accompanied by activation of the NOD-like receptor protein 3 (NLRP3) inflammasome, aberrant connexin 43 (Cx43) hemichannel-mediated ATP release is situated upstream of inflammasome assembly and inflammation and contributes to multiple secondary complications of diabetes and associated cardiometabolic comorbidities. Evidence suggests there may be a link between Cx43 hemichannel activity and inflammation in the diabetic kidney. The consequences of blocking tubular Cx43 hemichannel-mediated ATP release in priming/activation of the NLRP3 inflammasome in a model of diabetic kidney disease (DKD) was investigated. We examined downstream markers of inflammation and the proinflammatory and chemoattractant role of the tubular secretome on macrophage recruitment and activation. METHODS Analysis of human transcriptomic data from the Nephroseq repository correlated gene expression to renal function in DKD. Primary human renal proximal tubule epithelial cells (RPTECs) and monocyte-derived macrophages (MDMs) were cultured in high glucose and inflammatory cytokines as a model of DKD to assess Cx43 hemichannel activity, NLRP3 inflammasome activation and epithelial-to-macrophage paracrine-mediated crosstalk. Tonabersat assessed a role for Cx43 hemichannels. RESULTS Transcriptomic analysis from renal biopsies of patients with DKD showed that increased Cx43 and NLRP3 expression correlated with declining glomerular filtration rate (GFR) and increased proteinuria. In vitro, Tonabersat blocked glucose/cytokine-dependant increases in Cx43 hemichannel-mediated ATP release and reduced expression of inflammatory markers and NLRP3 inflammasome activation in RPTECs. We observed a reciprocal relationship in which NLRP3 activity exacerbated increased Cx43 expression and hemichannel-mediated ATP release, events driven by nuclear factor kappa-B (NFκB)-mediated priming and Cx43 hemichannel opening, changes blocked by Tonabersat. Conditioned media (CM) from RPTECs treated with high glucose/cytokines increased expression of inflammatory markers in MDMs, an effect reduced when macrophages were pre-treated with Tonabersat. Co-culture using conditioned media from Tonabersat-treated RPTECs dampened macrophage inflammatory marker expression and reduced macrophage migration. CONCLUSION Using a model of DKD, we report for the first time that high glucose and inflammatory cytokines trigger aberrant Cx43 hemichannel activity, events that instigate NLRP3-induced inflammation in RPTECs and epithelial-to-macrophage crosstalk. Recapitulating observations previously reported in diabetic retinopathy, these data suggest that Cx43 hemichannel blockers (i.e., Tonabersat) may dampen multi-system damage observed in secondary complications of diabetes.
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Affiliation(s)
- C L Cliff
- Joseph Banks Laboratories, School of Life and Environmental Sciences, University of Lincoln, Lincoln, LN6 7DL, UK
| | - P E Squires
- Joseph Banks Laboratories, School of Life and Environmental Sciences, University of Lincoln, Lincoln, LN6 7DL, UK
| | - C E Hills
- Joseph Banks Laboratories, School of Life and Environmental Sciences, University of Lincoln, Lincoln, LN6 7DL, UK.
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Yasarbas SS, Inal E, Yildirim MA, Dubrac S, Lamartine J, Mese G. Connexins in epidermal health and diseases: insights into their mutations, implications, and therapeutic solutions. Front Physiol 2024; 15:1346971. [PMID: 38827992 PMCID: PMC11140265 DOI: 10.3389/fphys.2024.1346971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 04/15/2024] [Indexed: 06/05/2024] Open
Abstract
The epidermis, the outermost layer of the skin, serves as a protective barrier against external factors. Epidermal differentiation, a tightly regulated process essential for epidermal homeostasis, epidermal barrier formation and skin integrity maintenance, is orchestrated by several players, including signaling molecules, calcium gradient and junctional complexes such as gap junctions (GJs). GJ proteins, known as connexins facilitate cell-to-cell communication between adjacent keratinocytes. Connexins can function as either hemichannels or GJs, depending on their interaction with other connexons from neighboring keratinocytes. These channels enable the transport of metabolites, cAMP, microRNAs, and ions, including Ca2+, across cell membranes. At least ten distinct connexins are expressed within the epidermis and mutations in at least five of them has been linked to various skin disorders. Connexin mutations may cause aberrant channel activity by altering their synthesis, their gating properties, their intracellular trafficking, and the assembly of hemichannels and GJ channels. In addition to mutations, connexin expression is dysregulated in other skin conditions including psoriasis, chronic wound and skin cancers, indicating the crucial role of connexins in skin homeostasis. Current treatment options for conditions with mutant or altered connexins are limited and primarily focus on symptom management. Several therapeutics, including non-peptide chemicals, antibodies, mimetic peptides and allele-specific small interfering RNAs are promising in treating connexin-related skin disorders. Since connexins play crucial roles in maintaining epidermal homeostasis as shown with linkage to a range of skin disorders and cancer, further investigations are warranted to decipher the molecular and cellular alterations within cells due to mutations or altered expression, leading to abnormal proliferation and differentiation. This would also help characterize the roles of each isoform in skin homeostasis, in addition to the development of innovative therapeutic interventions. This review highlights the critical functions of connexins in the epidermis and the association between connexins and skin disorders, and discusses potential therapeutic options.
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Affiliation(s)
- S. Suheda Yasarbas
- Izmir Institute of Technology, Faculty of Science, Department of Molecular Biology and Genetics, Izmir, Turkiye
| | - Ece Inal
- Izmir Institute of Technology, Faculty of Science, Department of Molecular Biology and Genetics, Izmir, Turkiye
| | - M. Azra Yildirim
- Izmir Institute of Technology, Faculty of Science, Department of Molecular Biology and Genetics, Izmir, Turkiye
| | - Sandrine Dubrac
- Department of Dermatology, Venereology and Allergology, Medical University of Innsbruck, Innsbruck, Austria
| | - Jérôme Lamartine
- Skin Functional Integrity Group, Laboratory for Tissue Biology and Therapeutics Engineering (LBTI) CNRS UMR5305, University of Lyon, Lyon, France
| | - Gulistan Mese
- Izmir Institute of Technology, Faculty of Science, Department of Molecular Biology and Genetics, Izmir, Turkiye
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Okolo CA, Maran JJ, Watts A, Maripillan J, Harkiolaki M, Martínez AD, Green CR, Mugisho OO. Correlative light and X-ray tomography jointly unveil the critical role of connexin43 channels on inflammation-induced cellular ultrastructural alterations. Heliyon 2024; 10:e27888. [PMID: 38560181 PMCID: PMC10979075 DOI: 10.1016/j.heliyon.2024.e27888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 03/06/2024] [Accepted: 03/07/2024] [Indexed: 04/04/2024] Open
Abstract
Non-junctional connexin43 (Cx43) plasma membrane hemichannels have been implicated in several inflammatory diseases, particularly playing a role in ATP release that triggers activation of the inflammasome. Therapies targeting the blocking of the hemichannels to prevent the pathological release or uptake of ions and signalling molecules through its pores are of therapeutic interest. To date, there is no close-to-native, high-definition documentation of the impact of Cx43 hemichannel-mediated inflammation on cellular ultrastructure, neither is there a robust account of the ultrastructural changes that occur following treatment with selective Cx43 hemichannel blockers such as Xentry-Gap19 (XG19). A combination of same-sample correlative high-resolution three-dimensional fluorescence microscopy and soft X-ray tomography at cryogenic temperatures, enabled in the identification of novel 3D molecular interactions within the cellular milieu when comparing behaviour in healthy states and during the early onset or late stages under inflammatory conditions. Notably, our findings suggest that XG19 blockage of connexin hemichannels under pro-inflammatory conditions may be crucial in preventing the direct degradation of connexosomes by lysosomes, without affecting connexin protein translation and trafficking. We also delineated fine and gross cellular phenotypes, characteristic of inflammatory insult or road-to-recovery from inflammation, where XG19 could indirectly prevent and reverse inflammatory cytokine-induced mitochondrial swelling and cellular hypertrophy through its action on Cx43 hemichannels. Our findings suggest that XG19 might have prophylactic and therapeutic effects on the inflammatory response, in line with functional studies.
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Affiliation(s)
- Chidinma Adanna Okolo
- Beamline B24, Life Sciences Division, Diamond Light Source, Didcot, Oxfordshire, United Kingdom
| | - Jack Jonathan Maran
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Amy Watts
- Beamline B24, Life Sciences Division, Diamond Light Source, Didcot, Oxfordshire, United Kingdom
| | - Jaime Maripillan
- Centro Interdisciplinario de Neurociencias de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
| | - Maria Harkiolaki
- Beamline B24, Life Sciences Division, Diamond Light Source, Didcot, Oxfordshire, United Kingdom
| | - Agustín D. Martínez
- Centro Interdisciplinario de Neurociencias de Valparaíso (CINV), Universidad de Valparaíso, Valparaíso, Chile
| | - Colin R. Green
- Department of Ophthalmology, University of Auckland, New Zealand
| | - Odunayo Omolola Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, New Zealand
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Yang L, Li Z, Fang J. Scutellarin Alleviates Diabetic Retinopathy via the Suppression of Nucleotide-Binding Oligomerization Domain (NOD)-Like Receptor Pyrin Domain Containing Protein 3 Inflammasome Activation. Curr Eye Res 2024; 49:180-187. [PMID: 38014534 DOI: 10.1080/02713683.2023.2273777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 10/17/2023] [Indexed: 11/29/2023]
Abstract
PURPOSE Diabetic retinopathy, a prevalent complication of diabetes, represents the leading cause of vision loss and blindness among middle-aged and elderly populations. Recent research has demonstrated the ameliorating effects of scutellarin on diabetes-associated complications such as diabetic retinopathy and type 2 diabetic cardiomyopathy. However, investigations into its protective impact and underlying mechanisms on diabetic retinopathy are scant. This study aims to explore the therapeutic potential of scutellarin in diabetic retinopathy treatment. METHODS Diabetic retinopathy was induced in rats through intraperitoneal injections of streptozotocin (STZ, 60 mg/kg) administered daily for three consecutive days. Following this, diabetic retinopathy rats received daily intragastric administration of scutellarin (40 mg/kg) for 42 days. RESULTS Our findings suggest that scutellarin alleviates histological damage in the retinal tissues of streptozotocin-challenged rats. Furthermore, scutellarin effectively enhances total retinal thickness and increases the number of ganglion cell layer (GCL) cells in the retinal tissues of streptozotocin-treated rats. Scutellarin also demonstrated anti-inflammatory and antioxidant effects in the retinal tissues of STZ-induced rats, as indicated by reduced levels of tumor necrosis factor-α, interleukin-1β, and interleukin-6, and elevated levels of glutathione peroxidase, superoxide dismutase, and catalase. Additionally, scutellarin effectively inhibited the expression of NOD-like receptor pyrin domain containing protein 3 inflammasome-related markers in the retinal tissues of streptozotocin-administered rats. CONCLUSIONS Collectively, our results indicate that scutellarin significantly reduces streptozotocin-induced retinal inflammation, an effect that may be partially attributed to the suppression of NLRP3 inflammasome activation.
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Affiliation(s)
- Lina Yang
- Department of Ophthalmology, Xinchang County People's Hospital, Shaoxing, China
| | - Zheming Li
- College of Pharmacy, Hangzhou Medical College, Hangzhou, China
| | - Jian Fang
- Department of Ophthalmology, Xinchang County People's Hospital, Shaoxing, China
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Kwakowsky A, Chawdhary B, de Souza A, Meyer E, Kaye AH, Green CR, Stylli SS, Danesh-Meyer H. Tonabersat Significantly Reduces Disease Progression in an Experimental Mouse Model of Multiple Sclerosis. Int J Mol Sci 2023; 24:17454. [PMID: 38139284 PMCID: PMC10744318 DOI: 10.3390/ijms242417454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 12/11/2023] [Accepted: 12/11/2023] [Indexed: 12/24/2023] Open
Abstract
Multiple sclerosis (MS) is a neurodegenerative disease marked by chronic neuroinflammation thought to be mediated by the inflammasome pathway. Connexin 43 (Cx43) hemichannels contribute to the activation of the inflammasome through the release of adenosine triphosphate (ATP) inflammasome activation signals. The objective of the study was to evaluate if the Cx43 hemichannel blocker, tonabersat, is effective in modulating the inflammatory response and reducing disability in the myelin oligodendrocyte glycoprotein 35-55-induced experimental autoimmune encephalomyelitis (MOG35-55 EAE) model of MS. Here, we show that the Cx43 hemichannel blocking drug, tonabersat, significantly reduced expression of neuroinflammatory markers for microglial activation (ionized calcium-binding adapter molecule 1 (Iba1)) and astrogliosis (glial fibrillary acidic protein (GFAP)) while preserving myelin basic protein (MBP) expression levels in the corpus callosum, motor cortex, and striatum regions of the brain in MOG35-55 EAE mice. Reduced NOD-like receptor protein 3 (NLRP3) inflammasome complex assembly and Caspase-1 activation confirmed the drug's mode of action. MOG35-55 EAE mice showed clinical signs of MS, but MOG35-55 EAE mice treated with tonabersat retained behavior closer to normal. These data suggest that clinical trial phase IIb-ready tonabersat may merit further investigation as a promising candidate for MS treatment.
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Affiliation(s)
- Andrea Kwakowsky
- Department of Anatomy and Medical Imaging, Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland 1023, New Zealand; (B.C.); (A.d.S.); (E.M.)
- Pharmacology and Therapeutics, Galway Neuroscience Centre, School of Medicine, Ollscoil na Gaillimhe—University of Galway, H91 W5P7 Galway, Ireland
| | - Bhavya Chawdhary
- Department of Anatomy and Medical Imaging, Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland 1023, New Zealand; (B.C.); (A.d.S.); (E.M.)
- Department of Opthalmology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand; (C.R.G.); (H.D.-M.)
| | - Antonio de Souza
- Department of Anatomy and Medical Imaging, Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland 1023, New Zealand; (B.C.); (A.d.S.); (E.M.)
- Department of Opthalmology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand; (C.R.G.); (H.D.-M.)
| | - Emily Meyer
- Department of Anatomy and Medical Imaging, Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Auckland 1023, New Zealand; (B.C.); (A.d.S.); (E.M.)
- Department of Opthalmology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand; (C.R.G.); (H.D.-M.)
| | - Andrew H. Kaye
- Department of Surgery, University of Melbourne, Melbourne, VIC 3010, Australia; (A.H.K.); (S.S.S.)
- Department of Neurosurgery, Hadassah Hebrew University Hospital, Jerusalem 91120, Israel
| | - Colin R. Green
- Department of Opthalmology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand; (C.R.G.); (H.D.-M.)
| | - Stanley S. Stylli
- Department of Surgery, University of Melbourne, Melbourne, VIC 3010, Australia; (A.H.K.); (S.S.S.)
- Department of Neurosurgery, The Royal Melbourne Hospital, Parkville, VIC 3052, Australia
| | - Helen Danesh-Meyer
- Department of Opthalmology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand; (C.R.G.); (H.D.-M.)
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6
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Li Y, Acosta FM, Jiang JX. Gap Junctions or Hemichannel-Dependent and Independent Roles of Connexins in Fibrosis, Epithelial-Mesenchymal Transitions, and Wound Healing. Biomolecules 2023; 13:1796. [PMID: 38136665 PMCID: PMC10742173 DOI: 10.3390/biom13121796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/09/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Fibrosis initially appears as a normal response to damage, where activated fibroblasts produce large amounts of the extracellular matrix (ECM) during the wound healing process to assist in the repair of injured tissue. However, the excessive accumulation of the ECM, unresolved by remodeling mechanisms, leads to organ dysfunction. Connexins, a family of transmembrane channel proteins, are widely recognized for their major roles in fibrosis, the epithelial-mesenchymal transition (EMT), and wound healing. Efforts have been made in recent years to identify novel mediators and targets for this regulation. Connexins form gap junctions and hemichannels, mediating communications between neighboring cells and inside and outside of cells, respectively. Recent evidence suggests that connexins, beyond forming channels, possess channel-independent functions in fibrosis, the EMT, and wound healing. One crucial channel-independent function is their role as the primary functional component for cell adhesion. Other channel-independent functions of connexins involve their roles in mitochondria and exosomes. This review summarizes the latest advances in the channel-dependent and independent roles of connexins in fibrosis, the EMT, and wound healing, with a particular focus on eye diseases, emphasizing their potential as novel, promising therapeutic targets.
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Affiliation(s)
- Yuting Li
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; (Y.L.); (F.M.A.)
- Department of Pathology, Basic Medical School, Ningxia Medical University, Yinchuan 750004, China
| | - Francisca M. Acosta
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; (Y.L.); (F.M.A.)
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA; (Y.L.); (F.M.A.)
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7
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Muniyandi A, Hartman GD, Song Y, Mijit M, Kelley MR, Corson TW. Beyond VEGF: Targeting Inflammation and Other Pathways for Treatment of Retinal Disease. J Pharmacol Exp Ther 2023; 386:15-25. [PMID: 37142441 PMCID: PMC10289243 DOI: 10.1124/jpet.122.001563] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 03/17/2023] [Accepted: 04/03/2023] [Indexed: 05/06/2023] Open
Abstract
Neovascular eye diseases include conditions such as retinopathy of prematurity, proliferative diabetic retinopathy, and neovascular age-related macular degeneration. Together, they are a major cause of vision loss and blindness worldwide. The current therapeutic mainstay for these diseases is intravitreal injections of biologics targeting vascular endothelial growth factor (VEGF) signaling. Lack of universal response to these anti-VEGF agents coupled with the challenging delivery method underscore a need for new therapeutic targets and agents. In particular, proteins that mediate both inflammatory and proangiogenic signaling are appealing targets for new therapeutic development. Here, we review agents currently in clinical trials and highlight some promising targets in preclinical and early clinical development, focusing on the redox-regulatory transcriptional activator APE1/Ref-1, the bioactive lipid modulator soluble epoxide hydrolase, the transcription factor RUNX1, and others. Small molecules targeting each of these proteins show promise for blocking neovascularization and inflammation. The affected signaling pathways illustrate the potential of new antiangiogenic strategies for posterior ocular disease. SIGNIFICANCE STATEMENT: Discovery and therapeutic targeting of new angiogenesis mediators is necessary to improve treatment of blinding eye diseases like retinopathy of prematurity, diabetic retinopathy, and neovascular age-related macular degeneration. Novel targets undergoing evaluation and drug discovery work include proteins important for both angiogenesis and inflammation signaling, including APE1/Ref-1, soluble epoxide hydrolase, RUNX1, and others.
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Affiliation(s)
- Anbukkarasi Muniyandi
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute (A.M., G.D.H., Y.S., M.R.K., T.W.C.), Department of Pediatrics, Herman B Wells Center for Pediatric Research (M.M., M.R.K.), Stark Neurosciences Research Institute (G.D.H., T.W.C.), Departments of Pharmacology and Toxicology (M.R.K., T.W.C.) and Biochemistry and Molecular Biology (M.R.K., T.W.C.), and Melvin and Bren Simon Comprehensive Cancer Center (M.R.K., T.W.C.), Indiana University School of Medicine, Indianapolis, Indiana
| | - Gabriella D Hartman
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute (A.M., G.D.H., Y.S., M.R.K., T.W.C.), Department of Pediatrics, Herman B Wells Center for Pediatric Research (M.M., M.R.K.), Stark Neurosciences Research Institute (G.D.H., T.W.C.), Departments of Pharmacology and Toxicology (M.R.K., T.W.C.) and Biochemistry and Molecular Biology (M.R.K., T.W.C.), and Melvin and Bren Simon Comprehensive Cancer Center (M.R.K., T.W.C.), Indiana University School of Medicine, Indianapolis, Indiana
| | - Yang Song
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute (A.M., G.D.H., Y.S., M.R.K., T.W.C.), Department of Pediatrics, Herman B Wells Center for Pediatric Research (M.M., M.R.K.), Stark Neurosciences Research Institute (G.D.H., T.W.C.), Departments of Pharmacology and Toxicology (M.R.K., T.W.C.) and Biochemistry and Molecular Biology (M.R.K., T.W.C.), and Melvin and Bren Simon Comprehensive Cancer Center (M.R.K., T.W.C.), Indiana University School of Medicine, Indianapolis, Indiana
| | - Mahmut Mijit
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute (A.M., G.D.H., Y.S., M.R.K., T.W.C.), Department of Pediatrics, Herman B Wells Center for Pediatric Research (M.M., M.R.K.), Stark Neurosciences Research Institute (G.D.H., T.W.C.), Departments of Pharmacology and Toxicology (M.R.K., T.W.C.) and Biochemistry and Molecular Biology (M.R.K., T.W.C.), and Melvin and Bren Simon Comprehensive Cancer Center (M.R.K., T.W.C.), Indiana University School of Medicine, Indianapolis, Indiana
| | - Mark R Kelley
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute (A.M., G.D.H., Y.S., M.R.K., T.W.C.), Department of Pediatrics, Herman B Wells Center for Pediatric Research (M.M., M.R.K.), Stark Neurosciences Research Institute (G.D.H., T.W.C.), Departments of Pharmacology and Toxicology (M.R.K., T.W.C.) and Biochemistry and Molecular Biology (M.R.K., T.W.C.), and Melvin and Bren Simon Comprehensive Cancer Center (M.R.K., T.W.C.), Indiana University School of Medicine, Indianapolis, Indiana
| | - Timothy W Corson
- Department of Ophthalmology, Eugene and Marilyn Glick Eye Institute (A.M., G.D.H., Y.S., M.R.K., T.W.C.), Department of Pediatrics, Herman B Wells Center for Pediatric Research (M.M., M.R.K.), Stark Neurosciences Research Institute (G.D.H., T.W.C.), Departments of Pharmacology and Toxicology (M.R.K., T.W.C.) and Biochemistry and Molecular Biology (M.R.K., T.W.C.), and Melvin and Bren Simon Comprehensive Cancer Center (M.R.K., T.W.C.), Indiana University School of Medicine, Indianapolis, Indiana
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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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9
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Yang Y, Jiang G, Huang R, Liu Y, Chang X, Fu S. Targeting the NLRP3 inflammasome in diabetic retinopathy: From Pathogenesis to Therapeutic Strategies. Biochem Pharmacol 2023; 212:115569. [PMID: 37100255 DOI: 10.1016/j.bcp.2023.115569] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/16/2023] [Accepted: 04/18/2023] [Indexed: 04/28/2023]
Abstract
Diabetic retinopathy (DR) is a common diabetic microvascular complication and the main cause of vision loss in working-aged people. The NLRP3 inflammasome is a cytosolic multimeric complex that plays a significant role in innate immunity. After sensing injury, the NLRP3 inflammasome induces inflammatory mediator secretion and triggers a form of inflammatory cell death known as pyroptosis. Studies over the past five years have shown increased expression of NLRP3 and related inflammatory mediators in vitreous samples from DR patients at different clinical stages. Many NLRP3-targeted inhibitors have shown great antiangiogenic and anti-inflammatory effects in diabetes mellitus models, suggesting that the NLRP3 inflammasome is involved in the progression of DR. This review covers the molecular mechanisms of NLRP3 inflammasome activation. Furthermore, we discuss the implications of the NLRP3 inflammasome in DR, including the induction of pyroptosis and inflammation and the promotion of microangiopathy and retinal neurodegeneration. We also summarize the research progress on targeting the NLRP3 inflammasome in DR therapeutics with the expectation of providing new insights into DR progression and treatment.
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Affiliation(s)
- Yuxuan Yang
- The First Clinical Medical College, Lanzhou University, Lanzhou, The People's Republic of China, 730000
| | - Gengchen Jiang
- The First Clinical Medical College, Lanzhou University, Lanzhou, The People's Republic of China, 730000
| | - Runchun Huang
- The First Clinical Medical College, Lanzhou University, Lanzhou, The People's Republic of China, 730000
| | - Yi Liu
- The First Clinical Medical College, Lanzhou University, Lanzhou, The People's Republic of China, 730000
| | - Xingyu Chang
- The First Clinical Medical College, Lanzhou University, Lanzhou, The People's Republic of China, 730000
| | - Songbo Fu
- Department of Endocrinology, First Hospital of Lanzhou University, Lanzhou, Gansu, The People's Republic of China, 730000; Gansu Province Clinical Research Center for Endocrine Disease, Gansu, The People's Republic of China, 730000.
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10
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Saha B, Roy A, Beltramo E, Sahoo OS. Stem cells and diabetic retinopathy: From models to treatment. Mol Biol Rep 2023; 50:4517-4526. [PMID: 36842153 DOI: 10.1007/s11033-023-08337-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 02/15/2023] [Indexed: 02/27/2023]
Abstract
Diabetic retinopathy is a common yet complex microvascular disease, caused as a complication of diabetes mellitus. Associated with hyperglycemia and subsequent metabolic abnormalities, advanced stages of the disease lead to fibrosis, subsequent visual impairment and blindness. Though clinical postmortems, animal and cell models provide information about the progression and prognosis of diabetic retinopathy, its underlying pathophysiology still needs a better understanding. In addition to it, the loss of pericytes, immature retinal angiogenesis and neuronal apoptosis portray the disease treatment to be challenging. Indulged with cell loss of both vascular and neuronal type cells, novel therapies like cell replacement strategies by various types of stem cells have been sightseen as a possible treatment of the disease. This review provides insight into the pathophysiology of diabetic retinopathy, current models used in modelling the disease, as well as the varied aspects of stem cells in generating three-dimensional retinal models. Further outlook on stem cell therapy and the future directions of stem cell treatment in diabetic retinopathy have also been contemplated.
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Affiliation(s)
- Bihan Saha
- National Institute of Technology Durgapur, Durgapur, 713209, West Bengal, India
| | - Akshita Roy
- Autonomous State Medical College, Fatehpur, 212601, Uttar Pradesh, India
| | - Elena Beltramo
- Department of Medical Sciences, University of Turin, 10124, Turin, Italy
| | - Om Saswat Sahoo
- National Institute of Technology Durgapur, Durgapur, 713209, West Bengal, India.
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11
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Mugisho OO, Aryal J, Shome A, Lyon H, Acosta ML, Green CR, Rupenthal ID. Orally Delivered Connexin43 Hemichannel Blocker, Tonabersat, Inhibits Vascular Breakdown and Inflammasome Activation in a Mouse Model of Diabetic Retinopathy. Int J Mol Sci 2023; 24:3876. [PMID: 36835288 PMCID: PMC9961562 DOI: 10.3390/ijms24043876] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Diabetic retinopathy (DR), a microvascular complication of diabetes, is associated with pronounced inflammation arising from the activation of a nucleotide-binding and oligomerization domain-like receptor (NLR) protein 3 (NLRP3) inflammasome. Cell culture models have shown that a connexin43 hemichannel blocker can prevent inflammasome activation in DR. The aim of this study was to evaluate the ocular safety and efficacy of tonabersat, an orally bioavailable connexin43 hemichannel blocker, to protect against DR signs in an inflammatory non-obese diabetic (NOD) DR mouse model. For retina safety studies, tonabersat was applied to retinal pigment epithelial (ARPE-19) cells or given orally to control NOD mice in the absence of any other stimuli. For efficacy studies, either tonabersat or a vehicle was given orally to the inflammatory NOD mouse model two hours before an intravitreal injection of pro-inflammatory cytokines, interleukin-1 beta, and tumour necrosis factor-alpha. Fundus and optical coherence tomography images were acquired at the baseline as well as at 2- and 7-day timepoints to assess microvascular abnormalities and sub-retinal fluid accumulation. Retinal inflammation and inflammasome activation were also assessed using immunohistochemistry. Tonabersat did not have any effect on ARPE-19 cells or control NOD mouse retinas in the absence of other stimuli. However, the tonabersat treatment in the inflammatory NOD mice significantly reduced macrovascular abnormalities, hyperreflective foci, sub-retinal fluid accumulation, vascular leak, inflammation, and inflammasome activation. These findings suggest that tonabersat may be a safe and effective treatment for DR.
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Affiliation(s)
- Odunayo O. Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Jyoti Aryal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Avik Shome
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Heather Lyon
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
| | - Monica L. Acosta
- School of Optometry and Vision Science, University of Auckland, Auckland 1023, New Zealand;
| | - Colin R. Green
- Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand
| | - Ilva D. Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, University of Auckland, Auckland 1023, New Zealand; (O.O.M.); (J.A.); (A.S.); (H.L.); (I.D.R.)
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12
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Kiełbowski K, Bakinowska E, Pawlik A. The Potential Role of Connexins in the Pathogenesis of Atherosclerosis. Int J Mol Sci 2023; 24:ijms24032600. [PMID: 36768920 PMCID: PMC9916887 DOI: 10.3390/ijms24032600] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/29/2022] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
Connexins (Cx) are members of a protein family which enable extracellular and intercellular communication through hemichannels and gap junctions (GJ), respectively. Cx take part in transporting important cell-cell messengers such as 3',5'-cyclic adenosine monophosphate (cAMP), adenosine triphosphate (ATP), and inositol 1,4,5-trisphosphate (IP3), among others. Therefore, they play a significant role in regulating cell homeostasis, proliferation, and differentiation. Alterations in Cx distribution, degradation, and post-translational modifications have been correlated with cancers, as well as cardiovascular and neurological diseases. Depending on the isoform, Cx have been shown either to promote or suppress the development of atherosclerosis, a progressive inflammatory disease affecting large and medium-sized arteries. Cx might contribute to the progression of the disease by enhancing endothelial dysfunction, monocyte recruitment, vascular smooth muscle cell (VSMC) activation, or by inhibiting VSMC autophagy. Inhibition or modulation of the expression of specific isoforms could suppress atherosclerotic plaque formation and diminish pro-inflammatory conditions. A better understanding of the complexity of atherosclerosis pathophysiology linked with Cx could result in developing novel therapeutic strategies. This review aims to present the role of Cx in the pathogenesis of atherosclerosis and discusses whether they can become novel therapeutic targets.
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13
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Yue T, Shi Y, Luo S, Weng J, Wu Y, Zheng X. The role of inflammation in immune system of diabetic retinopathy: Molecular mechanisms, pathogenetic role and therapeutic implications. Front Immunol 2022; 13:1055087. [PMID: 36582230 PMCID: PMC9792618 DOI: 10.3389/fimmu.2022.1055087] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/25/2022] [Indexed: 12/15/2022] Open
Abstract
Diabetic retinopathy is one of the most common complications of diabetes mellitus and the leading cause of low vision and blindness worldwide. Mounting evidence demonstrates that inflammation is a key mechanism driving diabetes-associated retinal disturbance, yet the pathophysiological process and molecular mechanisms of inflammation underlying diabetic retinopathy are not fully understood. Cytokines, chemokines, and adhesion molecules interact with each other to form a complex molecular network that propagates the inflammatory and pathological cascade of diabetic retinopathy. Therefore, it is important to understand and elucidate inflammation-related mechanisms behind diabetic retinopathy progression. Here, we review the current understanding of the pathology and pathogenesis of inflammation in diabetic retinopathy. In addition, we also summarize the relevant clinical trials to further suggest inflammation-targeted therapeutics for prevention and management of diabetic retinopathy.
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Affiliation(s)
- Tong Yue
- Department of Endocrinology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Yu Shi
- Department of Endocrinology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Sihui Luo
- Department of Endocrinology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Jianping Weng
- Department of Endocrinology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China
| | - Yali Wu
- Department of Ophthalmology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China,*Correspondence: Yali Wu, ; Xueying Zheng,
| | - Xueying Zheng
- Department of Endocrinology, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui, China,*Correspondence: Yali Wu, ; Xueying Zheng,
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14
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Characterization of NLRP3 Inflammasome Activation in the Onset of Diabetic Retinopathy. Int J Mol Sci 2022; 23:ijms232214471. [PMID: 36430950 PMCID: PMC9697159 DOI: 10.3390/ijms232214471] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 11/23/2022] Open
Abstract
The aim of this study was to characterize the role of nucleotide-binding oligomerization domain- (NOD-) like receptor (NLR) protein 3 (NLRP3) inflammasome activation in the onset of diabetic retinopathy (DR) using retina and vitreous from donors without diabetes mellitus (CTL), with diabetes mellitus alone (DM), and with DR. Retinal expression of glial fibrillary acidic protein (GFAP) and ionized calcium-binding adapter molecule 1 (Iba-1), the key markers of retinal inflammation, connexin43 (Cx43) which is involved in upstream inflammasome regulation, as well as NLRP3 and cleaved caspase-1, the main markers of inflammasome activation, were evaluated using immunohistochemistry and Western blotting. Vitreous interleukin (IL)-1β and IL-18, biomarkers of the activated inflammasome, were measured using a Luminex multiplex assay. Results showed a significant increase in the number and size of Iba-1+ cells and NLRP3 expression in DM, while a significant increase in GFAP, Cx43, cleaved caspase-1 and vitreous IL-18, as well as a further increase in Iba-1 and NLRP3 was found in DR. This suggests that the inflammasome is already primed in DM before its activation in DR. Furthermore, IL-18 may act as the major effector of inflammasome activation in DR while nuclear translocation of cleaved caspase-1 may play a role in gene transcription contributing to DR onset.
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15
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Zhao H, Kong H, Wang W, Chen T, Zhang Y, Zhu J, Feng D, Cui Y. High Glucose Aggravates Retinal Endothelial Cell Dysfunction by Activating the RhoA/ROCK1/pMLC/Connexin43 Signaling Pathway. Invest Ophthalmol Vis Sci 2022; 63:22. [PMID: 35881407 PMCID: PMC9339693 DOI: 10.1167/iovs.63.8.22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose This research aims to explore the mechanism underlying the relationship between RhoA/ROCK signaling and Connexin43 (Cx43) in retinal endothelial cell dysfunction and to evaluate the protective effect of ROCK inhibitors against retinal endothelial cell dysfunction in diabetic retinopathy (DR) models. Methods TUNEL staining, hematoxylin and eosin staining, a retinal digestion assay, and Evans blue assay were conducted to explore the effect of fasudil in alleviating retinal dysfunction induced by DR. ELISA, the CCK-8 assay, and flow cytometry were conducted to study inflammation, viability, and apoptosis of mouse retinal microvascular endothelial cells treated with high glucose and ROCK inhibitors. The qRT–PCR and Western blotting were used to evaluate the expression of RhoA, ROCK1, ROCK2, MLC, pMLC, and Cx43. Co-immunoprecipitation was used to verify the interaction between pMLC and Cx43. Immunofluorescence and scrape-loading and dye transfer were used to evaluate the expression and function of Cx43. Results Marked endothelial cell dysfunction resulting from the activation of RhoA/ROCK1 signaling was found in in vivo and in vitro models of DR. Via interaction with pMLC, which is downstream of RhoA/ROCK1, a significant downregulation of Cx43 was observed in retinal endothelial cells. Treatment with ROCK inhibitors ameliorated retinal endothelial dysfunction in vitro. The ROCK inhibitor, fasudil, significantly alleviated retinal dysfunction as shown by a decrease of retinal acellular capillaries, an improvement of vascular permeability, and a reduction of cell apoptosis in vivo. Conclusions Our study highlights a novel mechanism that high glucose could activate RhoA/ROCK1/pMLC signaling, which targets the expression and localization of Cx43 and is responsible for cell viability, apoptosis, and inflammation, resulting in retinal endothelial cell injury. ROCK inhibitors markedly ameliorate endothelial cell dysfunction, suggesting their therapeutic potential for diabetic retinopathy.
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Affiliation(s)
- Hongran Zhao
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China.,School of Medicine, Shandong University, Jinan, Shandong Province, China.,NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, Jinan, Shandong Province, China.,Laboratory of Basic Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong Province, China
| | - Hui Kong
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China.,Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China.,NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, Jinan, Shandong Province, China
| | - Wenjuan Wang
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China
| | - Tianran Chen
- School of Medicine, Shandong University, Jinan, Shandong Province, China
| | - Yuting Zhang
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China
| | - Jing Zhu
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China
| | - Dandan Feng
- Department of Cardiology, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong, China
| | - Yan Cui
- Department of Ophthalmology, Qilu Hospital of Shandong University, Shandong University, Jinan, Shandong Province, China
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16
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McDouall A, Zhou KQ, Bennet L, Green CR, Gunn AJ, Davidson JO. Connexins, Pannexins and Gap Junctions in Perinatal Brain Injury. Biomedicines 2022; 10:biomedicines10061445. [PMID: 35740466 PMCID: PMC9220888 DOI: 10.3390/biomedicines10061445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 06/15/2022] [Accepted: 06/15/2022] [Indexed: 11/18/2022] Open
Abstract
Perinatal brain injury secondary to hypoxia-ischemia and/or infection/inflammation remains a major cause of disability. Therapeutic hypothermia significantly improves outcomes, but in randomized controlled trials nearly half of infants still died or survived with disability, showing that additional interventions are needed. There is growing evidence that brain injury spreads over time from injured to previously uninjured regions of the brain. At least in part, this spread is related to opening of connexin hemichannels and pannexin channels, both of which are large conductance membrane channels found in many brain cells. Opening of these membrane channels releases adenosine triphosphate (ATP), and other neuroactive molecules, into the extracellular space. ATP has an important role in normal signaling, but pathologically can trigger the assembly of the multi-protein inflammasome complex. The inflammasome complex promotes activation of inflammatory caspases, and release of inflammatory cytokines. Overall, the connexin hemichannel appears to play a primary role in propagation of injury and chronic disease, and connexin hemichannel blockade has been shown to be neuroprotective in multiple animal models. Thus, there is potential for some blockers of connexin or pannexin channels to be developed into targeted interventions that could be used in conjunction with or separate to therapeutic hypothermia.
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Affiliation(s)
- Alice McDouall
- U1 Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand; (A.M.); (K.Q.Z.); (L.B.); (A.J.G.)
| | - Kelly Q. Zhou
- U1 Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand; (A.M.); (K.Q.Z.); (L.B.); (A.J.G.)
| | - Laura Bennet
- U1 Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand; (A.M.); (K.Q.Z.); (L.B.); (A.J.G.)
| | - Colin R. Green
- Department of Ophthalmology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand;
| | - Alistair J. Gunn
- U1 Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand; (A.M.); (K.Q.Z.); (L.B.); (A.J.G.)
| | - Joanne O. Davidson
- U1 Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1023, New Zealand; (A.M.); (K.Q.Z.); (L.B.); (A.J.G.)
- Correspondence:
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17
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Cliff CL, Williams BM, Chadjichristos CE, Mouritzen U, Squires PE, Hills CE. Connexin 43: A Target for the Treatment of Inflammation in Secondary Complications of the Kidney and Eye in Diabetes. Int J Mol Sci 2022; 23:600. [PMID: 35054783 PMCID: PMC8776095 DOI: 10.3390/ijms23020600] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/03/2022] [Accepted: 01/04/2022] [Indexed: 02/06/2023] Open
Abstract
Of increasing prevalence, diabetes is characterised by elevated blood glucose and chronic inflammation that precedes the onset of multiple secondary complications, including those of the kidney and the eye. As the leading cause of end stage renal disease and blindness in the working population, more than ever is there a demand to develop clinical interventions which can both delay and prevent disease progression. Connexins are membrane bound proteins that can form pores (hemichannels) in the cell membrane. Gated by cellular stress and injury, they open under pathophysiological conditions and in doing so release 'danger signals' including adenosine triphosphate into the extracellular environment. Linked to sterile inflammation via activation of the nod-like receptor protein 3 inflammasome, targeting aberrant hemichannel activity and the release of these danger signals has met with favourable outcomes in multiple models of disease, including secondary complications of diabetes. In this review, we provide a comprehensive update on those studies which document a role for aberrant connexin hemichannel activity in the pathogenesis of both diabetic eye and kidney disease, ahead of evaluating the efficacy of blocking connexin-43 specific hemichannels in these target tissues on tissue health and function.
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Affiliation(s)
- Chelsy L. Cliff
- Joseph Banks Laboratories, School of Life, Sciences University of Lincoln, Lincoln LN6 7DL, UK; (C.L.C.); (B.M.W.); (P.E.S.)
| | - Bethany M. Williams
- Joseph Banks Laboratories, School of Life, Sciences University of Lincoln, Lincoln LN6 7DL, UK; (C.L.C.); (B.M.W.); (P.E.S.)
| | - Christos E. Chadjichristos
- National Institutes for Health and Medical Research, UMR-S1155, Batiment Recherche, Tenon Hospital, 4 Rue de la Chine, 75020 Paris, France;
| | - Ulrik Mouritzen
- Ciana Therapeutics, Ole Maaloes Vej 3, 2200 Copenhagen N, Denmark;
| | - Paul E. Squires
- Joseph Banks Laboratories, School of Life, Sciences University of Lincoln, Lincoln LN6 7DL, UK; (C.L.C.); (B.M.W.); (P.E.S.)
| | - Claire E. Hills
- Joseph Banks Laboratories, School of Life, Sciences University of Lincoln, Lincoln LN6 7DL, UK; (C.L.C.); (B.M.W.); (P.E.S.)
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18
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Ge K, Wang Y, Li P, Li M, Zhang W, Dan H, Hu X, Zhou J, Yang Q, Wang J, Song Z. Down-expression of the NLRP3 inflammasome delays the progression of diabetic retinopathy. Microvasc Res 2022; 139:104265. [PMID: 34662588 DOI: 10.1016/j.mvr.2021.104265] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/02/2021] [Accepted: 10/12/2021] [Indexed: 12/29/2022]
Abstract
The investigation aimed to evaluate the effects of Mcc950, an inhibitor of the NLRP3 inflammasome, on diabetic retinopathy (DR) mice. The general physiological condition of each group of mice was recorded. Retinal blood vessels were stained for observation of the density of blood vessels, and retinas were used for further morphological examination and fluorescent staining after the intravitreal injection of Mcc950. Mcc950 partially reversed hyperglycemia-induced vascular damage and had reduced histological changes compared to DR mice. IL-1β production in mice retinas in the diabetic model (DM) group increased, but pretreatment with Mcc950 significantly reversed these changes. Additionally, Mcc950 engineered reduced FITC dextran extravasation and vascular leakage. Therefore, it played an apparent protective role in DR and could be a new treatment strategy for DR.
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Affiliation(s)
- Keke Ge
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Henan Eye Hospital, Zhengzhou 450003, Henan, China
| | - Yatao Wang
- Lanzhou University, The First Hospital of Lanzhou University, Lanzhou 730000, Gansu, China
| | - Pan Li
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Henan Eye Hospital, Zhengzhou 450003, Henan, China
| | - Miao Li
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital and Zhengzhou University People's Hospital, Zhengzhou 450003, Henan, China
| | - Wenhua Zhang
- Henan University People's Hospital, Henan Provincial People's Hospital, Henan Eye Hospital, Zhengzhou 450003, Henan, China
| | - Handong Dan
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital and Zhengzhou University People's Hospital, Zhengzhou 450003, Henan, China
| | - Xumeng Hu
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Henan Eye Hospital, Zhengzhou 450003, Henan, China
| | - Jiamu Zhou
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Henan Eye Hospital, Zhengzhou 450003, Henan, China
| | - Qixiang Yang
- Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Henan Eye Hospital, Zhengzhou 450003, Henan, China
| | - Jiaojiao Wang
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital and Zhengzhou University People's Hospital, Zhengzhou 450003, Henan, China.
| | - Zongming Song
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital and Zhengzhou University People's Hospital, Zhengzhou 450003, Henan, China.
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19
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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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20
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Zhang Y, Jiao Y, Li X, Gao S, Zhou N, Duan J, Zhang M. Pyroptosis: A New Insight Into Eye Disease Therapy. Front Pharmacol 2021; 12:797110. [PMID: 34925047 PMCID: PMC8678479 DOI: 10.3389/fphar.2021.797110] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/15/2021] [Indexed: 02/05/2023] Open
Abstract
Pyroptosis is a lytic form of programmed cell death mediated by gasdermins (GSDMs) with pore-forming activity in response to certain exogenous and endogenous stimuli. The inflammasomes are intracellular multiprotein complexes consisting of pattern recognition receptors, an adaptor protein ASC (apoptosis speck-like protein), and caspase-1 and cause autocatalytic activation of caspase-1, which cleaves gasdermin D (GSDMD), inducing pyroptosis accompanied by cytokine release. In recent years, the pathogenic roles of inflammasomes and pyroptosis in multiple eye diseases, including keratitis, dry eyes, cataracts, glaucoma, uveitis, age-related macular degeneration, and diabetic retinopathy, have been continuously confirmed. Inhibiting inflammasome activation and abnormal pyroptosis in eyes generally attenuates inflammation and benefits prognosis. Therefore, insight into the pathogenesis underlying pyroptosis and inflammasome development in various types of eye diseases may provide new therapeutic strategies for ocular disorders. Inhibitors of pyroptosis, such as NLRP3, caspase-1, and GSDMD inhibitors, have been proven to be effective in many eye diseases. The purpose of this article is to illuminate the mechanism underlying inflammasome activation and pyroptosis and emphasize its crucial role in various ocular disorders. In addition, we review the application of pyroptosis modulators in eye diseases.
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Affiliation(s)
- Yun Zhang
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China.,Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, China
| | - Yan Jiao
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
| | - Xun Li
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China.,Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, China
| | - Sheng Gao
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China.,Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, China
| | - Nenghua Zhou
- Key Laboratory of Drug Targeting and Drug Delivery System of Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu, China
| | - Jianan Duan
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China.,Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, China
| | - Meixia Zhang
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China.,Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, China
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Tittarelli A. Connexin channels modulation in pathophysiology and treatment of immune and inflammatory disorders. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166258. [PMID: 34450245 DOI: 10.1016/j.bbadis.2021.166258] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/28/2021] [Accepted: 08/19/2021] [Indexed: 12/16/2022]
Abstract
Connexin-mediated intercellular communication mechanisms include bidirectional cell-to-cell coupling by gap junctions and release/influx of molecules by hemichannels. These intercellular communications have relevant roles in numerous immune system activities. Here, we review the current knowledge about the function of connexin channels, mainly those formed by connexin-43, on immunity and inflammation. Focusing on those evidence that support the design and development of therapeutic tools to modulate connexin expression and/or channel activities with treatment potential for infections, wounds, cancer, and other inflammatory conditions.
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Affiliation(s)
- Andrés Tittarelli
- Programa Institucional de Fomento a la Investigación, Desarrollo e Innovación, Universidad Tecnológica Metropolitana, Santiago 8940577, Chile.
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22
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Lyon H, Yin N, Rupenthal ID, Green CR, Mugisho OO. Blocking connexin43 hemichannels prevents TGF-β2 upregulation and epithelial-mesenchymal transition in retinal pigment epithelial cells. Cell Biol Int 2021; 46:323-330. [PMID: 34719065 DOI: 10.1002/cbin.11718] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/10/2021] [Accepted: 10/23/2021] [Indexed: 12/14/2022]
Abstract
Epithelial-mesenchymal transition (EMT) occurs when polarised epithelial cells change to a mesenchymal phenotype. EMT plays a role in several chronic conditions, including ocular diseases with retinal pigment epithelium (RPE) EMT associated with retinal diseases such as diabetic retinopathy (DR). Here, EMT results in breakdown of the blood-retinal barrier (BRB) leading to sub-retinal fluid deposition and retinal detachment. Previous studies have shown that blocking connexin43 (Cx43) hemichannels can protect against RPE BRB breakdown, but the underlying mechanism is unknown. To determine whether open Cx43 hemichannels may enable EMT of RPE cells and thus result in BRB breakdown, ARPE-19 cells were either challenged with high glucose plus the inflammatory cytokines IL-1β and TNF-α (HG + Cyt) to simulate DR or treated with the Cx43 hemichannel blocker tonabersat alongside the HG + Cyt challenge. HG + Cyt induced a morphological change in RPE cells to a fibroblastic phenotype with a corresponding decrease in epithelial zonular occludens-1 and an increase in the fibroblastic marker α-SMA. The HG + Cyt challenge also induced loss of transepithelial electrical resistance while increasing dye passage between RPE cells. All of these changes were significantly reduced with tonabersat treatment, which also prevented HG + Cyt-induced transforming growth factor-β2 (TGF-β2) release. In conclusion, Cx43 hemichannel block with tonabersat attenuated both TGF-β2 release and RPE EMT under disease-mimicking conditions, offering the potential to ameliorate the progression of EMT-associated retinal diseases.
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Affiliation(s)
- Heather Lyon
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Naibo Yin
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Odunayo O Mugisho
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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23
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Collagen I Modifies Connexin-43 Hemichannel Activity via Integrin α2β1 Binding in TGFβ1-Evoked Renal Tubular Epithelial Cells. Int J Mol Sci 2021; 22:ijms22073644. [PMID: 33807408 PMCID: PMC8038016 DOI: 10.3390/ijms22073644] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/23/2021] [Accepted: 03/30/2021] [Indexed: 02/07/2023] Open
Abstract
Chronic Kidney Disease (CKD) is associated with sustained inflammation and progressive fibrosis, changes that have been linked to altered connexin hemichannel-mediated release of adenosine triphosphate (ATP). Kidney fibrosis develops in response to increased deposition of extracellular matrix (ECM), and up-regulation of collagen I is an early marker of renal disease. With ECM remodeling known to promote a loss of epithelial stability, in the current study we used a clonal human kidney (HK2) model of proximal tubular epithelial cells to determine if collagen I modulates changes in cell function, via connexin-43 (Cx43) hemichannel ATP release. HK2 cells were cultured on collagen I and treated with the beta 1 isoform of the pro-fibrotic cytokine transforming growth factor (TGFβ1) ± the Cx43 mimetic Peptide 5 and/or an anti-integrin α2β1 neutralizing antibody. Phase microscopy and immunocytochemistry observed changes in cell morphology and cytoskeletal reorganization, whilst immunoblotting and ELISA identified changes in protein expression and secretion. Carboxyfluorescein dye uptake and biosensing measured hemichannel activity and ATP release. A Cytoselect extracellular matrix adhesion assay assessed changes in cell-substrate interactions. Collagen I and TGFβ1 synergistically evoked increased hemichannel activity and ATP release. This was paralleled by changes to markers of tubular injury, partly mediated by integrin α2β1/integrin-like kinase signaling. The co-incubation of the hemichannel blocker Peptide 5, reduced collagen I/TGFβ1 induced alterations and inhibited a positive feedforward loop between Cx43/ATP release/collagen I. This study highlights a role for collagen I in regulating connexin-mediated hemichannel activity through integrin α2β1 signaling, ahead of establishing Peptide 5 as a potential intervention.
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González-Casanova J, Schmachtenberg O, Martínez AD, Sanchez HA, Harcha PA, Rojas-Gomez D. An Update on Connexin Gap Junction and Hemichannels in Diabetic Retinopathy. Int J Mol Sci 2021; 22:ijms22063194. [PMID: 33801118 PMCID: PMC8004116 DOI: 10.3390/ijms22063194] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 03/06/2021] [Accepted: 03/10/2021] [Indexed: 01/10/2023] Open
Abstract
Diabetic retinopathy (DR) is one of the main causes of vision loss in the working age population. It is characterized by a progressive deterioration of the retinal microvasculature, caused by long-term metabolic alterations inherent to diabetes, leading to a progressive loss of retinal integrity and function. The mammalian retina presents an orderly layered structure that executes initial but complex visual processing and analysis. Gap junction channels (GJC) forming electrical synapses are present in each retinal layer and contribute to the communication between different cell types. In addition, connexin hemichannels (HCs) have emerged as relevant players that influence diverse physiological and pathological processes in the retina. This article highlights the impact of diabetic conditions on GJC and HCs physiology and their involvement in DR pathogenesis. Microvascular damage and concomitant loss of endothelial cells and pericytes are related to alterations in gap junction intercellular communication (GJIC) and decreased connexin 43 (Cx43) expression. On the other hand, it has been shown that the expression and activity of HCs are upregulated in DR, becoming a key element in the establishment of proinflammatory conditions that emerge during hyperglycemia. Hence, novel connexin HCs blockers or drugs to enhance GJIC are promising tools for the development of pharmacological interventions for diabetic retinopathy, and initial in vitro and in vivo studies have shown favorable results in this regard.
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Affiliation(s)
- Jorge González-Casanova
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago 8910060, Chile;
| | - Oliver Schmachtenberg
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Biología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile;
| | - Agustín D. Martínez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (A.D.M.); (H.A.S.); (P.A.H.)
| | - Helmuth A. Sanchez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (A.D.M.); (H.A.S.); (P.A.H.)
| | - Paloma A. Harcha
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2360102, Chile; (A.D.M.); (H.A.S.); (P.A.H.)
| | - Diana Rojas-Gomez
- Escuela de Nutrición y Dietética, Facultad de Medicina, Universidad Andres Bello, Santiago 8370146, Chile
- Correspondence: ; Tel.: +56-2-26618559
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