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Yamamoto Y, Akanuma SI, Kon H, Endo H, Kubo Y, Hosoya KI. Newly-established in vitro inner BRB spheroids to elucidate retinal Ang2-linked substance transfer. J Control Release 2022; 351:8-21. [PMID: 36122894 DOI: 10.1016/j.jconrel.2022.09.019] [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: 04/08/2022] [Revised: 09/09/2022] [Accepted: 09/11/2022] [Indexed: 10/31/2022]
Abstract
Conjugation of angiopep-2 (Ang2) with drugs/compounds is known to increase plasma membrane permeability across endothelial barriers. The inner blood-retinal barrier (BRB) regulates retinal drug distribution and is formed by retinal capillary endothelial cells, supported by Müller cells and retinal pericytes. To elucidate the potential of Ang2 conjugation in promoting retinal drug distribution after peripheral administration across the inner BRB, an in vivo administration study and in vitro transport experiments using newly developed multicellular inner BRB spheroids were performed. After intravenous administration of Ang2-linked green fluorescence protein (GFP-Ang2) in mice, GFP-derived signals were observed in the neural retina. In contrast, GFP-derived signals were not observed after intravenous GFP administration, suggesting the promotion of the retinal distribution of substances by Ang2 conjugation. To overcome the limitations of in vitro studies using cells cultured on dishes, inner BRB spheroids were established using conditionally immortalized rat retinal capillary endothelial cells, Müller cells, and retinal pericytes. Immunocytochemistry of marker molecules suggests that the central part of the spheroids is occupied by Müller cells, and encapsulated by retinal pericytes and capillary endothelial cells. Studies on the expression and functions of tight junctions suggest that tight junctions are formed on the surface of the inner BRB spheroids by retinal capillary endothelial cells. The functional expression of drug transporters, such as P-glycoprotein, was observed in the spheroids, implying that the inner side of the spheroids reflects the retinal side of the inner BRB. In the inner BRB spheroids, energy-dependent accumulation of GFP-Ang2 and Ang2-linked 5(6)-carboxyfluorescein (FAM-Ang2) was observed. Moreover, an endocytic inhibition study revealed that clathrin-dependent endocytosis/transcytosis was involved in the transcellular transport of Ang2-conjugated drugs/compounds across the inner BRB. Consequently, it is suggested that the Ang2 linkage is useful for promoting retinal drug distribution via clathrin-dependent transcytosis at the inner BRB.
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Affiliation(s)
- Yudai Yamamoto
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan
| | - Shin-Ichi Akanuma
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
| | - Hideki Kon
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan
| | - Hiroki Endo
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan
| | - Yoshiyuki Kubo
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan
| | - Ken-Ichi Hosoya
- Department of Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama 930-0194, Japan.
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Domouky AM, Samy WM, Rashad WA. Therapeutic effect of the mesenchymal stem cells on vigabatrin-induced retinopathy in adult male albino rat. Anat Cell Biol 2022; 55:217-228. [PMID: 35773221 PMCID: PMC9256488 DOI: 10.5115/acb.22.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 02/25/2022] [Accepted: 03/06/2022] [Indexed: 12/02/2022] Open
Abstract
Vigabatrin (VGB) is an effective antiepileptic drug used mainly to treat infantile spasms and refractory complex partial seizures. However, using VGB was restricted as it was known to cause retinal toxicity that appears as a severe peripheral visual field defect. Accordingly, this study was conducted to examine the histopathological and biochemical effects of VGB on the retina in adult male albino rats and assess the possible therapeutic role of mesenchymal stem cells (MSCs) against this potential toxicity. The rats were divided into three groups (control group, VGB group, and VGB/MSCs group), one week after 65 days of VGB treatment ±MSCs. The right eyeballs were prepared for histological and immunohistochemical examination, whereas the left eyeballs were prepared for real-time polymerase chain reaction analysis. Our results demonstrated that MSCs ameliorated retinal pathological changes and downregulated the expression of glial fibrillary acidic protein, vascular endothelial growth factor, and synaptophysin after VGB administration suggesting MSCs function and vascular modulating effect. Moreover, MSCs regulate retinal tissue gene expression of BAX, Bcl-2, BDNF, NGF, synapsin, interleukin (IL)-6, IL-1β, and occludin suggesting MSCs antiapoptotic and immunomodulating effect. In conclusion, MSCs administration could be a suitable therapeutic line to ameliorate VGB-induced retinopathy.
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Affiliation(s)
- Ayat Mahmoud Domouky
- Department of Human Anatomy & Embryology, Faculty of Medicine, Zagazig University, Zagazig, Zagazig, Egypt
| | - Walaa M Samy
- Department of Medical Biochemistry, Faculty of Medicine, Zagazig University, Zagazig, Egypt
| | - Walaa A Rashad
- Department of Human Anatomy & Embryology, Faculty of Medicine, Zagazig University, Zagazig, Zagazig, Egypt
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3
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Tajima K, Akanuma SI, Ohishi Y, Yoshida Y, Bauer B, Kubo Y, Inouye M, Hosoya KI. Freshly isolated retinal capillaries to determine efflux transporter function at the inner BRB. J Control Release 2022; 343:434-442. [DOI: 10.1016/j.jconrel.2022.01.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 01/11/2022] [Accepted: 01/22/2022] [Indexed: 11/26/2022]
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Sheskey SR, Antonetti DA, Rentería RC, Lin CM. Correlation of Retinal Structure and Visual Function Assessments in Mouse Diabetes Models. Invest Ophthalmol Vis Sci 2021; 62:20. [PMID: 34410299 PMCID: PMC8383928 DOI: 10.1167/iovs.62.10.20] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Purpose Diabetic retinopathy results in vision loss with changes to both retinal blood vessels and neural retina. Recent studies have revealed that animal models of diabetes demonstrate early loss of visual function. We explored the time course of retinal change in three different mouse models of diabetes in a longitudinal study using in vivo measures of retinal structure (optical coherence tomography [OCT]) and visual function (optomotor and pupillary responses). Methods OCT analysis of retinal microstructure, optokinetic response as a measure of visual acuity, and pupillary response to light stimulation were compared among the db/db, Ins2Akita, and streptozotocin (STZ)-induced mouse models of diabetes at 1.5, 3, 6, and 9 months of diabetes. Results The db/db, Ins2Akita, and STZ-induced models of diabetes all exhibited vision loss and retinal thinning as disease progressed. Both structural changes and functional measures were significantly correlated with the blood glucose levels. Despite this, vision loss and retinal thinning were not consistently correlated, except for the inner retinal layer thickness at 6 months of diabetes. Conclusions This longitudinal study compiled structural measures and functional outcome data for type 1 and 2 diabetes mouse models commonly used for diabetes studies and demonstrated an overall decline in retinal-related health in conjunction with weight change and blood glucose alterations. The relationship between the structural change and functional outcome could be correlative but is not necessarily causative, as retinal thinning was not sufficient to explain visual acuity decline.
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Affiliation(s)
- Sarah R Sheskey
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - David A Antonetti
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
| | - René C Rentería
- Department of Clinical and Applied Science Education, School of Osteopathic Medicine, University of the Incarnate Word, San Antonio, Texas, United States
| | - Cheng-Mao Lin
- Department of Ophthalmology and Visual Sciences, Kellogg Eye Center, University of Michigan, Ann Arbor, Michigan, United States
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5
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Villota SD, Toledo-Rodriguez M, Leach L. Compromised barrier integrity of human feto-placental vessels from gestational diabetic pregnancies is related to downregulation of occludin expression. Diabetologia 2021; 64:195-210. [PMID: 33001231 PMCID: PMC7716932 DOI: 10.1007/s00125-020-05290-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 08/18/2020] [Indexed: 12/16/2022]
Abstract
AIMS/HYPOTHESIS Reduced occupancy of junctional occludin is a feature of human placental vessels in the diabetic milieu. However, the functional consequence of this and whether this loss is due to differential expression of occludin splice variants is not known. Our study aimed to investigate the effects of gestational diabetes mellitus (GDM), and its treatment, on endothelial junctional integrity, gene and protein expression of occludin splice variants, and potential regulation of expression by microRNAs (miRNAs). METHODS Term placentas were obtained from normal pregnancies (n = 21), and pregnancies complicated by GDM where glucose levels were controlled by diet (n = 11) or metformin (n = 6). Gene and microRNA (miRNA) expression were determined by quantitative real-time PCR; protein expression by immunoblotting; endothelial junctional occupancy by fluorescence microscopy and systematic sampling; and paracellular leakage by perfusion of placental microvascular beds with 76 Mr dextran. Transfection studies of miRNAs that target OCLN were performed in HUVECs, and the trans-endothelial electrical resistance and tracer permeability of the HUVECs were measured. RESULTS All three predicted OCLN gene splice variants and two occludin protein isoforms were found in human placental samples. In placental samples from diet-controlled GDM (d-GDM) pregnancies we found a lower percentage of conduit vessels showing occludin immunoreactivity (12%, p < 0.01), decreased levels of the fully functional occludin isoform-A protein (29%), and differential gene expression of OCLN variant 2 (33% decrease), variant 3 (3.3-fold increase). These changes were not seen in samples from the group with metformin-controlled GDM. In d-GDM placentas, increased numbers of conduit microvessels demonstrated extravasation of 76 Mr dextran (2.0-fold). In d-GDM expression of one of the five potential miRNAs targeting OCLN, miR-181a-5p, expression was 2.1-fold that in normal pregnancies. Experimental overexpression of miR-181a-5p in HUVECs from normal pregnancies resulted in a highly significant downregulation of OCLN variant 1 (69%) and variant 2 (46%) gene expression, with decreased trans-endothelial resistance (78%) and increase in tracer permeability (1.3-fold). CONCLUSIONS/INTERPRETATION Downregulation of expression of OCLN variant 2 and the fully functional occludin isoform-A protein are a feature of placentas in d-GDM pregnancies. These may be behind the loss of junctional occludin and the increased extravasation of exogenous dextran observed. miR-181a-5p was in part responsible for the downregulation of occludin in placentas from d-GDM pregnancies. Induced overexpression of miR-181a-5p compromised the integrity of the endothelial barrier. Our data suggest that, despite good glucose control, the adoption of lifestyle changes alone during a GDM pregnancy may not be enough to prevent an alteration in the expression of occludin and the subsequent functional consequences in placentas and impaired vascular barrier function in offspring. Graphical abstract.
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Affiliation(s)
| | | | - Lopa Leach
- School of Life Sciences, University of Nottingham, Nottingham, UK.
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6
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Roy S, Kim D. Retinal capillary basement membrane thickening: Role in the pathogenesis of diabetic retinopathy. Prog Retin Eye Res 2020; 82:100903. [PMID: 32950677 DOI: 10.1016/j.preteyeres.2020.100903] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 09/08/2020] [Accepted: 09/15/2020] [Indexed: 02/07/2023]
Abstract
Vascular basement membrane (BM) thickening has been hailed over half a century as the most prominent histological lesion in diabetic microangiopathy, and represents an early ultrastructural change in diabetic retinopathy (DR). Although vascular complications of DR have been clinically well established, specific cellular and molecular mechanisms underlying dysfunction of small vessels are not well understood. In DR, small vessels develop insidiously as BM thickening occurs. Studies examining high resolution imaging data have established BM thickening as one of the foremost structural abnormalities of retinal capillaries. This fundamental structural change develops, at least in part, from excess accumulation of BM components. Although BM thickening is closely associated with the development of DR, its contributory role in the pathogenesis of DR is coming to light recently. DR develops over several years before clinical manifestations appear, and it is during this clinically silent period that hyperglycemia induces excess synthesis of BM components, contributes to vascular BM thickening, and promotes structural and functional lesions including cell death and vascular leakage in the diabetic retina. Studies using animal models show promising results in preventing BM thickening with subsequent beneficial effects. Several gene regulatory approaches are being developed to prevent excess synthesis of vascular BM components in an effort to reduce BM thickening. This review highlights current understanding of capillary BM thickening development, role of BM thickening in retinal vascular lesions, and strategies for preventing vascular BM thickening as a potential therapeutic strategy in alleviating characteristic lesions associated with DR.
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Affiliation(s)
- Sayon Roy
- Boston University School of Medicine, Boston, MA, USA.
| | - Dongjoon Kim
- Boston University School of Medicine, Boston, MA, USA
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Pran Babu SPS, White D, Corson TW. Ferrochelatase regulates retinal neovascularization. FASEB J 2020; 34:12419-12435. [PMID: 32716567 PMCID: PMC7726024 DOI: 10.1096/fj.202000964r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/01/2020] [Accepted: 07/06/2020] [Indexed: 01/18/2023]
Abstract
Ferrochelatase (FECH) is the terminal enzyme in heme biosynthesis. We previously showed that FECH is required for endothelial cell growth in vitro and choroidal neovascularization in vivo. But FECH has not been explored in retinal neovascularization, which underlies diseases like proliferative diabetic retinopathy and retinopathy of prematurity. Here, we investigated the inhibition of FECH using genetic and chemical approaches in the oxygen-induced retinopathy (OIR) mouse model. In OIR mice, FECH expression is upregulated and co-localized with neovascular tufts. Partial loss-of-function Fechm1Pas mutant mice showed reduced retinal neovascularization and endothelial cell proliferation in OIR. An intravitreal injection of the FECH inhibitor N-methyl protoporphyrin had similar effects. Griseofulvin is an antifungal drug that inhibits FECH as an off-target effect. Strikingly, intravitreal griseofulvin decreased both pathological tuft formation and areas of vasoobliteration compared to vehicle, suggesting potential as a FECH-targeting therapy. Ocular toxicity studies revealed that intravitreal injection of griseofulvin in adult mice does not disrupt retinal vasculature, function, or morphology. In sum, mutation and chemical inhibition of Fech reduces retinal neovascularization and promotes physiological angiogenesis, suggesting a dual effect on vascular repair upon FECH inhibition, without ocular toxicity. These findings suggest that FECH inhibitors could be repurposed to treat retinal neovascularization.
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Affiliation(s)
- Sardar Pasha Sheik Pran Babu
- Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Darcy White
- Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Timothy W. Corson
- Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Higashi Y, Sukhanov S, Shai SY, Danchuk S, Snarski P, Li Z, Hou X, Hamblin MH, Woods TC, Wang M, Wang D, Yu H, Korthuis RJ, Yoshida T, Delafontaine P. Endothelial deficiency of insulin-like growth factor-1 receptor reduces endothelial barrier function and promotes atherosclerosis in Apoe-deficient mice. Am J Physiol Heart Circ Physiol 2020; 319:H730-H743. [PMID: 32795184 DOI: 10.1152/ajpheart.00064.2020] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Insulin-like growth factor-1 (IGF-1) decreases atherosclerosis in apolipoprotein E (Apoe)-deficient mice when administered systemically. However, mechanisms for its atheroprotective effect are not fully understood. We generated endothelium-specific IGF-1 receptor (IGF1R)-deficient mice on an Apoe-deficient background to assess effects of IGF-1 on the endothelium in the context of hyperlipidemia-induced atherosclerosis. Endothelial deficiency of IGF1R promoted atherosclerotic burden, when animals were fed on a high-fat diet for 12 wk or normal chow for 12 mo. Under the normal chow feeding condition, the vascular relaxation response to acetylcholine was increased in the endothelial IGF1R-deficient aorta; however, feeding of a high-fat diet substantially attenuated the relaxation response, and there was no difference between endothelial IGF1R-deficient and control mice. The endothelium and its intercellular junctions provide a barrier function to the vasculature. In human aortic endothelial cells, IGF-1 upregulated occludin, claudin 5, VE-cadherin, JAM-A, and CD31 expression levels, and vice versa, specific IGF1R inhibitor, picropodophyllin, an IGF1R-neutralizing antibody (αIR3), or siRNA to IGF1R abolished the IGF-1 effects on junction and adherens proteins, suggesting that IGF-1 promoted endothelial barrier function. Moreover, endothelial transwell permeability assays indicated that inhibition of IGF-1 signaling elevated solute permeability through the monolayer of human aortic endothelial cells. In summary, endothelial IGF1R deficiency increases atherosclerosis, and IGF-1 positively regulates tight junction protein and adherens junction protein levels and endothelial barrier function. Our findings suggest that the elevation of the endothelial junction protein level is, at least in part, the mechanism for antiatherogenic effects of IGF-1.NEW & NOTEWORTHY Endothelial insulin-like growth factor-1 (IGF-1) receptor deficiency significantly elevated atherosclerotic burden in apolipoprotein E-deficient mice, mediated at least in part by downregulation of intercellular junction proteins and, thus, elevated endothelial permeability. This study revealed a novel role for IGF-1 in supporting endothelial barrier function. These findings suggest that IGF-1's ability to promote endothelial barrier function may offer a novel therapeutic strategy for vascular diseases such as atherosclerosis.
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Affiliation(s)
- Yusuke Higashi
- Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana
| | - Sergiy Sukhanov
- Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana
| | - Shaw-Yung Shai
- Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana
| | - Svitlana Danchuk
- Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana
| | - Patricia Snarski
- Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana
| | - Zhaohui Li
- Department of Radiology, University of Missouri School of Medicine, Columbia, Missouri
| | - Xuwei Hou
- Department of Medicine, University of Missouri School of Medicine, Columbia, Missouri
| | - Milton H Hamblin
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana
| | - T Cooper Woods
- Department of Physiology, Tulane University School of Medicine, New Orleans, Louisiana
| | - Meifang Wang
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri
| | - Derek Wang
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri
| | - Hong Yu
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri
| | - Ronald J Korthuis
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri
| | - Tadashi Yoshida
- Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana
| | - Patrice Delafontaine
- Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana
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Yu C, Yang K, Meng X, Cao B, Wang F. Downregulation of Long Noncoding RNA MIAT in the Retina of Diabetic Rats with Tail-vein Injection of Human Umbilical-cord Mesenchymal Stem Cells. Int J Med Sci 2020; 17:591-598. [PMID: 32210708 PMCID: PMC7085208 DOI: 10.7150/ijms.38078] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 01/15/2020] [Indexed: 12/28/2022] Open
Abstract
Diabetic retinopathy (DR) is the common and important cause for visual impairment and blindness in working-aged people. Microangiopathy and inflammatory reactions are the key components of DR. Recently, long non-coding RNA myocardial infarction-associated transcript (MIAT) has emerged as a vital player in regulation for inflammatory processes and microvascular dysfunction. Additionally, cell-based therapy provides a potential option for the treatment of DR. The anti-inflammatory effects and repair therapy of mesenchymal stem cells (MSCs) have been paid more attention. This study investigated the effects of human umbilical-cord mesenchymal stem cells (HUMSCs) injection on diabetic rat model. The results show that the level of MIAT is significantly decreased in the diabetic retina after the injection of HUMSCs. Moreover, HUMSCs can significantly decrease the expression of IL-1β and IL-6 mRNA; alleviate microvascular permeability, and upregulate Occludin expression. Studies have shown that MIAT knockdown could alleviate diabetes-induced inflammation responses and vascular leakage. Furthermore, our findings also showed that the expression of MIAT was positively correlated with the expression of IL-1β and IL-6. These results suggest that MIAT might play important regulatory roles in alleviating inflammatory reactions and microangiopathy inducing by DR after transplantation of HUMSCs.
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Affiliation(s)
- Chuan Yu
- Ophthalmology, Affiliated Hospital of Qingdao University, Qingdao 266500, Shandong Province, China
| | - Kun Yang
- Central Laboratory, Affiliated Hospital of Qingdao University, Qingdao 266500, Shandong Province, China
| | - Xuxia Meng
- Ophthalmology, Affiliated Hospital of Qingdao University, Qingdao 266500, Shandong Province, China
| | - Bowen Cao
- Center for Ophthalmology, Institute for Ophthalmic Research, University of Tuebingen, 72076, Tuebingen, Germany
| | - Fenglei Wang
- Ophthalmology, Affiliated Hospital of Qingdao University, Qingdao 266500, Shandong Province, China
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10
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Sahle FF, Kim S, Niloy KK, Tahia F, Fili CV, Cooper E, Hamilton DJ, Lowe TL. Nanotechnology in regenerative ophthalmology. Adv Drug Deliv Rev 2019; 148:290-307. [PMID: 31707052 PMCID: PMC7474549 DOI: 10.1016/j.addr.2019.10.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/29/2019] [Accepted: 10/30/2019] [Indexed: 12/18/2022]
Abstract
In recent years, regenerative medicine is gaining momentum and is giving hopes for restoring function of diseased, damaged, and aged tissues and organs and nanotechnology is serving as a catalyst. In the ophthalmology field, various types of allogenic and autologous stem cells have been investigated to treat some ocular diseases due to age-related macular degeneration, glaucoma, retinitis pigmentosa, diabetic retinopathy, and corneal and lens traumas. Nanomaterials have been utilized directly as nanoscaffolds for these stem cells to promote their adhesion, proliferation and differentiation or indirectly as vectors for various genes, tissue growth factors, cytokines and immunosuppressants to facilitate cell reprogramming or ocular tissue regeneration. In this review, we reviewed various nanomaterials used for retina, cornea, and lens regenerations, and discussed the current status and future perspectives of nanotechnology in tracking cells in the eye and personalized regenerative ophthalmology. The purpose of this review is to provide comprehensive and timely insights on the emerging field of nanotechnology for ocular tissue engineering and regeneration.
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Affiliation(s)
- Fitsum Feleke Sahle
- Department of Pharmaceutical Sciences, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Sangyoon Kim
- Department of Pharmaceutical Sciences, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Kumar Kulldeep Niloy
- Department of Pharmaceutical Sciences, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Faiza Tahia
- Department of Pharmaceutical Sciences, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Cameron V Fili
- Department of Comparative Medicine, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Emily Cooper
- Department of Pharmaceutical Sciences, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - David J Hamilton
- Department of Comparative Medicine, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA
| | - Tao L Lowe
- Department of Pharmaceutical Sciences, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA.
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11
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Li W, Ma N, Liu MX, Ye BJ, Li YJ, Hu HY, Tang YH. C1q/TNF-related protein-9 attenuates retinal inflammation and protects blood–retinal barrier in db/db mice. Eur J Pharmacol 2019; 853:289-298. [DOI: 10.1016/j.ejphar.2019.04.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 04/03/2019] [Accepted: 04/05/2019] [Indexed: 12/21/2022]
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12
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Liu L, Jiang Y, Steinle JJ. Epac1 and Glycyrrhizin Both Inhibit HMGB1 Levels to Reduce Diabetes-Induced Neuronal and Vascular Damage in the Mouse Retina. J Clin Med 2019; 8:jcm8060772. [PMID: 31159195 PMCID: PMC6616522 DOI: 10.3390/jcm8060772] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 05/23/2019] [Accepted: 05/27/2019] [Indexed: 12/25/2022] Open
Abstract
The role of high mobility group box 1 (HMGB1) in acute diabetic retinal damage has been demonstrated. We recently reported that glycyrrhizin, a HMGB1 inhibitor, protected the diabetic retina against neuronal, vascular, and permeability changes. In this study, we wanted to investigate the role of exchange protein for cAMP 1 (Epac1) on HMGB1 and the actions of glycyrrhizin. Using endothelial cell specific knockout mice for Epac1, we made some mice diabetic using streptozotocin, and treated some with glycyrrhizin for up to 6 months. We measured permeability, neuronal, and vascular changes in the Epac1 floxed and knockout mice. We also investigated whether Epac1 and glycyrrhizin work synergistically to reduce the retinal inflammatory mediators, tumor necrosis factor alpha (TNFα) and interleukin-1-beta (IL1β), as well as sirtuin 1 (SIRT1) levels. Epac1 and glycyrrhizin reduced inflammatory mediators with synergistic actions. Glycyrrhizin also increased SIRT1 levels in the Epac1 mice. Overall, these studies demonstrate that glycyrrhizin and Epac1 can work together to protect the retina. Finally, glycyrrhizin may regulate HMGB1 through increased SIRT1 actions.
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Affiliation(s)
- Li Liu
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Youde Jiang
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Jena J Steinle
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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Valle ML, Dworshak J, Sharma A, Ibrahim AS, Al-Shabrawey M, Sharma S. Inhibition of interleukin-6 trans-signaling prevents inflammation and endothelial barrier disruption in retinal endothelial cells. Exp Eye Res 2018; 178:27-36. [PMID: 30240585 DOI: 10.1016/j.exer.2018.09.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 07/20/2018] [Accepted: 09/17/2018] [Indexed: 12/27/2022]
Abstract
Vascular inflammation plays a critical role in the pathogenesis of diabetic retinopathy. Recently, Interleukin-6 (IL-6) trans-signaling via soluble IL-6 receptor (sIL-6R) has emerged as a prominent regulator of inflammation in endothelial cells. This study was designed to test the hypothesis that selective inhibition of the IL-6 trans-signaling pathway will attenuate inflammation and subsequent barrier disruption in retinal endothelial cells. Human retinal endothelial cells (HRECs) were exposed to IL-6 and sIL-6R to induce IL-6 trans-signaling and the commercially available compound sgp130Fc (soluble gp-130 fused chimera) was used to selectively inhibit IL-6 trans-signaling. IL-6 trans-signaling activation caused a significant increase in STAT3 phosphorylation, expression of adhesion molecules, ROS production and apoptosis in HRECs whereas a significant decrease in mitochondrial membrane potential and NO production was observed in IL-6 trans-signaling activated cells. These changes were not observed in cells pre-treated with sgp130Fc. IL-6 trans-signaling activation was sufficient to cause barrier disruption in endothelial monolayers and pre-treatment of HRECs with sgp130Fc, maintained endothelial barrier function similar to that of untreated cells. Thus, in conclusion, these results indicate that IL-6 trans-signaling is an important mediator of inflammation, apoptosis and barrier disruptive effects in the retinal endothelial cells and inhibition of the IL-6 trans-signaling pathway using sgp130-Fc attenuates vascular inflammation and endothelial barrier disruption.
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Affiliation(s)
- Maria L Valle
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Janine Dworshak
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Ashok Sharma
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA; Department of Population Health Sciences, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Ahmed S Ibrahim
- James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA; Department of Oral Biology and Anatomy, Dental College of Georgia, Augusta University, Augusta, GA, USA; Department of Biochemistry, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Mohamed Al-Shabrawey
- James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA; Department of Oral Biology and Anatomy, Dental College of Georgia, Augusta University, Augusta, GA, USA
| | - Shruti Sharma
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA; Department of Ophthalmology, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA; James & Jean Culver Vision Discovery Institute, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA.
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14
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Clermont A, Murugesan N, Zhou Q, Kita T, Robson PA, Rushbrooke LJ, Evans DM, Aiello LP, Feener EP. Plasma Kallikrein Mediates Vascular Endothelial Growth Factor-Induced Retinal Dysfunction and Thickening. Invest Ophthalmol Vis Sci 2017; 57:2390-9. [PMID: 27138737 PMCID: PMC4857835 DOI: 10.1167/iovs.15-18272] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Plasma kallikrein is a serine protease and circulating component of inflammation, which exerts clinically significant effects on vasogenic edema. This study examines the role of plasma kallikrein in VEGF-induced retinal edema. METHODS Intravitreal injections of VEGF and saline vehicle were performed in plasma prekallikrein-deficient (KLKB1-/-) and wild-type (WT) mice, and in both rats and mice receiving a selective plasma kallikrein inhibitor, VA999272. Retinal vascular permeability (RVP) and retinal thickness were measured by Evans blue permeation and optical coherence tomography, respectively. The retinal kallikrein kinin system was examined by Western blotting and immunohistochemistry. Retinal neovascularization was investigated in KLKB1-/- and WT mice subjected to oxygen-induced retinopathy. RESULTS Vascular endothelial growth factor-induced RVP and retinal thickening were reduced in KLKB1-/- mice by 68% and 47%, respectively, compared to VEGF responses in WT mice. Plasma kallikrein also contributes to TNFα-induced retinal thickening, which was reduced by 52% in KLKB1-/- mice. Systemic administration of VA999272 reduced VEGF-induced retinal thickening by 57% (P < 0.001) in mice and 53% (P < 0.001) in rats, compared to vehicle-treated controls. Intravitreal injection of VEGF in WT mice increased plasma prekallikrein in the retina, which was diffusely distributed throughout the inner and outer retinal layers. Avascular and neovascular areas induced by oxygen-induced retinopathy were similar in WT and KLKB1-/- mice. CONCLUSIONS Vascular endothelial growth factor increases extravasation of plasma kallikrein into the retina, and plasma kallikrein is required for the full effects of VEGF on RVP and retinal thickening in rodents. Systemic plasma kallikrein inhibition may provide a therapeutic opportunity to treat VEGF-induced retina edema.
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Affiliation(s)
- Allen Clermont
- Joslin Diabetes Center, Boston, Massachusetts, United States 2Beetham Eye Institute, Boston, Massachusetts, United States
| | | | - Qunfang Zhou
- Joslin Diabetes Center, Boston, Massachusetts, United States
| | - Takeshi Kita
- Joslin Diabetes Center, Boston, Massachusetts, United States
| | | | | | | | - Lloyd Paul Aiello
- Joslin Diabetes Center, Boston, Massachusetts, United States 2Beetham Eye Institute, Boston, Massachusetts, United States 4Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
| | - Edward P Feener
- Joslin Diabetes Center, Boston, Massachusetts, United States 5Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States
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15
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Acharya NK, Qi X, Goldwaser EL, Godsey GA, Wu H, Kosciuk MC, Freeman TA, Macphee CH, Wilensky RL, Venkataraman V, Nagele RG. Retinal pathology is associated with increased blood-retina barrier permeability in a diabetic and hypercholesterolaemic pig model: Beneficial effects of the LpPLA 2 inhibitor Darapladib. Diab Vasc Dis Res 2017; 14:200-213. [PMID: 28301218 DOI: 10.1177/1479164116683149] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Using a porcine model of diabetes mellitus and hypercholesterolaemia, we previously showed that diabetes mellitus and hypercholesterolaemia is associated with a chronic increase in blood-brain barrier permeability in the cerebral cortex, leading to selective binding of immunoglobulin G and deposition of amyloid-beta1-42 peptide in pyramidal neurons. Treatment with Darapladib (GlaxoSmithKline, SB480848), an inhibitor of lipoprotein-associated phospholipase-A2, alleviated these effects. Here, investigation of the effects of chronic diabetes mellitus and hypercholesterolaemia on the pig retina revealed a corresponding increased permeability of the blood-retina barrier coupled with a leak of plasma components into the retina, alterations in retinal architecture, selective IgG binding to neurons in the ganglion cell layer, thinning of retinal layers due to cell loss and increased glial fibrillary acidic protein expression in Müller cells, all of which were curtailed by treatment with Darapladib. These findings suggest that chronic diabetes mellitus and hypercholesterolaemia induces increased blood-retina barrier permeability that may be linked to altered expression of blood-retina barrier-associated tight junction proteins, claudin and occludin, leading to structural changes in the retina consistent with diabetic retinopathy. Additionally, results suggest that drugs with vascular anti-inflammatory properties, such as Darapladib, may have beneficial effects on eye diseases strongly linked to vascular abnormalities such as diabetic retinopathy and age-related macular degeneration.
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Affiliation(s)
- Nimish K Acharya
- 1 Biomarker Discovery Center, New Jersey Institute for Successful Aging, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
- 2 Department of Geriatrics and Gerontology, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
- 3 Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA
| | - Xin Qi
- 4 Thomas Jefferson University, Philadelphia, PA, USA
- 5 Department of Ophthalmology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Eric L Goldwaser
- 1 Biomarker Discovery Center, New Jersey Institute for Successful Aging, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
- 2 Department of Geriatrics and Gerontology, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
- 6 Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ, USA
| | - George A Godsey
- 2 Department of Geriatrics and Gerontology, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
- 6 Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ, USA
| | - Hao Wu
- 6 Graduate School of Biomedical Sciences, Rowan University, Stratford, NJ, USA
- 7 Department of Cell Biology, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
| | - Mary C Kosciuk
- 1 Biomarker Discovery Center, New Jersey Institute for Successful Aging, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
- 2 Department of Geriatrics and Gerontology, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
| | - Theresa A Freeman
- 8 Department of Orthopaedic Surgery, Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University
| | | | - Robert L Wilensky
- 10 Hospital of the University of Pennsylvania, Philadelphia, PA, USA
| | - Venkat Venkataraman
- 7 Department of Cell Biology, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
| | - Robert G Nagele
- 1 Biomarker Discovery Center, New Jersey Institute for Successful Aging, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
- 2 Department of Geriatrics and Gerontology, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
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16
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Liu WY, Tzeng TF, Liu IM. Zerumbone, a Bioactive Sesquiterpene, Ameliorates Diabetes-Induced Retinal Microvascular Damage through Inhibition of Phospho-p38 Mitogen-Activated Protein Kinase and Nuclear Factor-κB Pathways. Molecules 2016; 21:molecules21121708. [PMID: 27973425 PMCID: PMC6273957 DOI: 10.3390/molecules21121708] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/07/2016] [Accepted: 12/09/2016] [Indexed: 12/22/2022] Open
Abstract
Zerumbone ameliorates retinal damage by blocking advanced glycation end products and their receptor system in streptozotocin-diabetic rats. Because of the multiple factors involved in diabetic retinopathy (DR) etiology, the mechanisms of zerumbone that are mainly responsible for its ameliorative effect on DR need to be further clarified. In the present study, zerumbone (20 mg or 40 mg/kg) or fenofibric acid (100 mg/kg) was orally administered to diabetic rats by intragastric gavage once daily for three consecutive months. Zerumbone displayed similar characteristics to fenofibric acid in reducing retinal vascular permeability and leukostasis in diabetic rats. Fundus photographs showed that large retinal vessel diameters were decreased in zerumbone-treated diabetic rats. Zerumbone not only down-regulated the gene expression of retinal angiogenic parameters, but also reduced the expression of inflammatory cytokines and chemokines in the retina of diabetic rats. Moreover, zerumbone reduced the p38 MAPK phosphorylation and abrogated the nuclear translocation of NF-κB p65 in the retina of diabetic rats. In conclusion, treatment of diabetic rats with zerumbone attenuates the severity of retinal inflammation and angiogenesis, via inhibition of p38 MAPK and NF-κB signaling pathways. These benefits of zerumbone for DR appear to be linked to its antihyperglycemic and antihyperlipidemic effects.
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Affiliation(s)
- Wayne Young Liu
- Center for Basic Medical Science, Collage of Health Science, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan.
- Department of Urology, Jen-Ai Hospital, Taichung 41625, Taiwan.
| | - Thing-Fong Tzeng
- Department of Pharmacy and Master Program, Collage of Pharmacy and Health Care, Tajen University, Pingtung 90741, Taiwan.
| | - I-Min Liu
- Department of Pharmacy and Master Program, Collage of Pharmacy and Health Care, Tajen University, Pingtung 90741, Taiwan.
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17
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Tzeng TF, Liu WY, Liou SS, Hong TY, Liu IM. Antioxidant-Rich Extract from Plantaginis Semen Ameliorates Diabetic Retinal Injury in a Streptozotocin-Induced Diabetic Rat Model. Nutrients 2016; 8:nu8090572. [PMID: 27649243 PMCID: PMC5037557 DOI: 10.3390/nu8090572] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 02/06/2023] Open
Abstract
Plantaginis semen, the dried ripe seed of Plantago asiatica L. or Plantago depressa Willd. (Plantaginaceae), has been traditionally used to treat blurred vision in Asia. The aim of this work was to investigate the effect of plantaginis semen ethanol extract (PSEE) on the amelioration of diabetic retinopathy (DR) in streptozotocin (STZ)-diabetic rats. PSEE has abundant polyphenols with strong antioxidant activity. PSEE (100, 200 or 300 mg/kg) was oral administrated to the diabetic rats once daily consecutively for 8 weeks. Oral administration of PSEE resulted in significant reduction of hyperglycemia, the diameter of the retinal vessels, and retinal vascular permeability and leukostasis in diabetic rats. In addition, PSEE administration increased the activities of superoxidase dismutase (SOD) and catalase (CAT), and glutathione peroxidase (GSH) level in diabetic retinae. PSEE treatment inhibited the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1α (HIF-1α) and the phosphorylation of Akt without altering the Akt protein expression in diabetic retinae. PSEE not only down-regulated the gene expression of hypoxia-inducible factor-1α (TNF-α) and interleukin-1β (IL-1β), but also reduced ICAM-1 and VCAM-1 expression in diabetic retinae. Moreover, PSEE reduced the nuclear factor-κB (NF-κB) activation and corrected imbalance between histone deacetylases (HDAC) and histone acetyltransferases (HAT) activities in diabetic retinae. In conclusion, phenolic antioxidants extract from plantaginis semen has potential benefits in the prevention and/or progression of DR.
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Affiliation(s)
- Thing-Fong Tzeng
- Department of Pharmacy and Master Program, Collage of Pharmacy and Health Care, Tajen University, Pingtung County 90741, Taiwan.
| | - Wayne Young Liu
- Department of Urology, Jen-Ai Hospital, Taichung City 41625, Taiwan.
- Center for Basic Medical Science, Collage of Health Science, Central Taiwan University of Science and Technology, Taichung City 40601, Taiwan.
| | - Shorong-Shii Liou
- Department of Pharmacy and Master Program, Collage of Pharmacy and Health Care, Tajen University, Pingtung County 90741, Taiwan.
| | - Tang-Yao Hong
- Department of Biotechnology, Collage of Pharmacy and Health Care, Tajen University, Pingtung County 90741, Taiwan.
| | - I-Min Liu
- Department of Pharmacy and Master Program, Collage of Pharmacy and Health Care, Tajen University, Pingtung County 90741, Taiwan.
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18
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Paterniti I, Di Paola R, Campolo M, Siracusa R, Cordaro M, Bruschetta G, Tremolada G, Maestroni A, Bandello F, Esposito E, Zerbini G, Cuzzocrea S. Palmitoylethanolamide treatment reduces retinal inflammation in streptozotocin-induced diabetic rats. Eur J Pharmacol 2015; 769:313-23. [PMID: 26607470 DOI: 10.1016/j.ejphar.2015.11.035] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/05/2015] [Accepted: 11/18/2015] [Indexed: 01/19/2023]
Abstract
Although the pathogenesis of diabetic retinopathy (DR) is still insufficiently understood, new evidences indicate 'retinal inflammation' as an important player in the pathogenesis of the complication. Accordingly, common sets of upregulated inflammatory cytokines are found in serum, vitreous and aqueous samples obtained from subjects with DR, and these cytokines can have multiple interactions to impact the pathogenesis of the disease. Thus, based on previously published data, we investigated the effects of Palmitoylethanolamide (PEA), an endogenous lipid amide that belongs to the N-acyl-ethanolamines family, on DR in streptozotocin (STZ)-induced diabetic rats. PEA (10mg/kg) was administered orally daily starting 3 days after the iv administration of STZ. The rats were killed 15 and 60day later and eyes were enucleated to evaluate, through immunohistochemical analysis, the key inflammatory events involved in the breakdown of blood retinal barrier (BRB). Immunohistochemical analysis confirmed the presence of VEGF, ICAM-1, nitrotyrosine (a marker of peroxynitrite), and tight junctions in the retina of STZ-treated rats. Of interest, the extent of injury was significantly reduced after treatment with PEA. Altogether, this study provides the first evidence that PEA attenuates the degree of inflammation while preserving the blood-retinal barrier in rats with experimental DR.
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Affiliation(s)
- Irene Paterniti
- Department of Biological and Environmental Sciences, University of Messina, Italy
| | - Rosanna Di Paola
- Department of Biological and Environmental Sciences, University of Messina, Italy
| | - Michela Campolo
- Department of Biological and Environmental Sciences, University of Messina, Italy
| | - Rosalba Siracusa
- Department of Biological and Environmental Sciences, University of Messina, Italy
| | - Marika Cordaro
- Department of Biological and Environmental Sciences, University of Messina, Italy
| | - Giuseppe Bruschetta
- Department of Biological and Environmental Sciences, University of Messina, Italy
| | - Gemma Tremolada
- Department of Ophthalmology, Vita-Salute University, San Raffaele Scientific Institute, Milan, Italy
| | - Anna Maestroni
- Complications of Diabetes Unit, Division of Metabolic and Cardiovascular Sciences, San Raffaele Scientific Institute, Milan, Italy
| | - Francesco Bandello
- Department of Ophthalmology, Vita-Salute University, San Raffaele Scientific Institute, Milan, Italy
| | - Emanuela Esposito
- Department of Biological and Environmental Sciences, University of Messina, Italy
| | - Gianpaolo Zerbini
- Complications of Diabetes Unit, Division of Metabolic and Cardiovascular Sciences, San Raffaele Scientific Institute, Milan, Italy
| | - Salvatore Cuzzocrea
- Department of Biological and Environmental Sciences, University of Messina, Italy; Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, USA.
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19
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Dugel PU, Bandello F, Loewenstein A. Dexamethasone intravitreal implant in the treatment of diabetic macular edema. Clin Ophthalmol 2015. [PMID: 26213460 PMCID: PMC4509543 DOI: 10.2147/opth.s79948] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Diabetic macular edema (DME) resembles a chronic, low-grade inflammatory reaction, and is characterized by blood–retinal barrier (BRB) breakdown and retinal capillary leakage. Corticosteroids are of therapeutic benefit because of their anti-inflammatory, antiangiogenic, and BRB-stabilizing properties. Delivery modes include periocular and intravitreal (via pars plana) injection. To offset the short intravitreal half-life of corticosteroid solutions (~3 hours) and the need for frequent intravitreal injections, sustained-release intravitreal corticosteroid implants have been developed. Dexamethasone intravitreal implant provides retinal drug delivery for ≤6 months and recently has been approved for use in the treatment of DME. Pooled findings (n=1,048) from two large-scale, randomized Phase III trials indicated that dexamethasone intravitreal implant (0.35 mg and 0.7 mg) administered at ≥6-month intervals produced sustained improvements in best-corrected visual acuity (BCVA) and macular edema. Significantly more patients showed a ≥15-letter gain in BCVA at 3 years with dexamethasone intravitreal implant 0.35 mg and 0.7 mg than with sham injection (18.4% and 22.2% vs 12.0%). Anatomical assessments showed rapid and sustained reductions in macular edema and slowing of retinopathy progression. Phase II study findings suggest that dexamethasone intravitreal implant is effective in focal, cystoid, and diffuse DME, in vitrectomized eyes, and in combination with laser therapy. Ocular complications of dexamethasone intravitreal implant in Phase III trials included cataract-related events (66.0% in phakic patients), intraocular pressure elevation ≥25 mmHg (29.7%), conjunctival hemorrhage (23.5%), vitreous hemorrhage (10.0%), macular fibrosis (8.3%), conjunctival hyperemia (7.2%), eye pain (6.1%), vitreous detachment (5.8%), and dry eye (5.8%); injection-related complications (eg, retinal tear/detachment, vitreous loss, endophthalmitis) were infrequent (<2%). Dexamethasone intravitreal implant offers a viable treatment option for DME, especially in cases that are persistent or treatment (anti-vascular endothelial growth factor/laser) refractory.
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Affiliation(s)
- Pravin U Dugel
- Retinal Consultants of Arizona, Phoenix, AZ, Los Angeles, CA, USA ; Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Francesco Bandello
- Department of Ophthalmology, University Vita-Salute Scientific Institute San Raffaele, Milan, Italy
| | - Anat Loewenstein
- Department of Ophthalmology, Tel Aviv Medical Center and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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20
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Gandica Y, Schwarz T, Oliveira O, Travasso RDM. Hypoxia in vascular networks: a complex system approach to unravel the diabetic paradox. PLoS One 2014; 9:e113165. [PMID: 25409306 PMCID: PMC4237512 DOI: 10.1371/journal.pone.0113165] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 10/20/2014] [Indexed: 01/30/2023] Open
Abstract
In this work we model the extent of hypoxia in the diabetic retina as a function of the area affected by vessel disruption. We find two regimes that differ on the ratio between the area of disrupted vasculature and the area of tissue in hypoxia. In the first regime the hypoxia is localized in the vicinity of the vascular disruption, while in the second regime there is a generalized hypoxia in the affected tissue. The transition between these two regimes occurs when the tissue area affected by individual sites of vessel damage is on the order of the square of the characteristic irrigation length in the tissue (the maximum distance that an irrigated point in the tissue is from an existing vessel). We observe that very high levels of hypoxia are correlated with the rupture of larger vessels in the retina, and with smaller radii of individual sites of vessel damage. Based on this property of vascular networks, we propose a novel mechanism for the transition between the nonproliferative and the proliferative stages in diabetic retinopathy.
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Affiliation(s)
- Yérali Gandica
- Center for Computational Physics, Department of Physics, University of Coimbra, Coimbra, Portugal
| | - Tobias Schwarz
- Center for Computational Physics, Department of Physics, University of Coimbra, Coimbra, Portugal
- Heinz-Brandt-Schule, Berlin, Germany
| | - Orlando Oliveira
- Center for Computational Physics, Department of Physics, University of Coimbra, Coimbra, Portugal
| | - Rui D. M. Travasso
- Center for Computational Physics, Department of Physics, University of Coimbra, Coimbra, Portugal
- Center of Ophthalmology and Vision Sciences(COCV), Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Coimbra, Portugal
- * E-mail:
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21
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Sumagin R, Sarelius IH. Emerging understanding of roles for arterioles in inflammation. Microcirculation 2014; 20:679-92. [PMID: 23701383 DOI: 10.1111/micc.12068] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 05/20/2013] [Indexed: 12/20/2022]
Abstract
Arterioles, capillaries, and venules all actively change their cellular functions and phenotypes during inflammation in ways that are essential for maintenance of homeostasis and self-defense, and are also associated with many inflammatory disorders. ECs, together with pericytes and ECM proteins, can regulate blood flow, the coagulation cascade, fluid and solute exchange, and leukocyte trafficking. While capillary and venular functions in inflammation are well characterized, the arteriolar contribution to inflammation has only recently come into focus. Arterioles differ from venules in structure, EC morphology, shear environment, expression, and distribution of surface ligands; hence, regulation and function of arteriolar wall cells during inflammation may also be distinct from venules. Recent work indicates that in response to proinflammatory stimuli, arterioles alter barrier function, and support leukocyte and platelet interactions through upregulation of adhesion molecules. This suggests that in addition to their role in blood flow regulation, arterioles may also participate in inflammatory responses. In this review, we will discuss mechanisms that characterize arteriolar responses to proinflammatory stimuli. We will detail how distinct arteriolar features contribute to regulation of barrier function and leukocyte-EC interactions in inflammation, and further highlight the potential priming effects of arteriolar responses on venular function and progression of inflammatory responses.
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Affiliation(s)
- Ronen Sumagin
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York, USA
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22
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Zhou KK, Benyajati S, Le Y, Cheng R, Zhang W, Ma JX. Interruption of Wnt signaling in Müller cells ameliorates ischemia-induced retinal neovascularization. PLoS One 2014; 9:e108454. [PMID: 25271989 PMCID: PMC4182699 DOI: 10.1371/journal.pone.0108454] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 08/29/2014] [Indexed: 01/26/2023] Open
Abstract
Retinal Müller cells are major producers of inflammatory and angiogenic cytokines which contribute to diabetic retinopathy (DR). Over-activation of the Wnt/β-catenin pathway has been shown to play an important pathogenic role in DR. However, the roles of Müller cell-derived Wnt/β-catenin signaling in retinal neovascularization (NV) and DR remain undefined. In the present study, mice with conditional β-catenin knockout (KO) in Müller cells were generated and subjected to oxygen-induced retinopathy (OIR) and streptozotocin (STZ)-induced diabetes. Wnt signaling was evaluated by measuring levels of β-catenin and expression of its target genes using immunoblotting. Retinal vascular permeability was measured using Evans blue as a tracer. Retinal NV was visualized by angiography and quantified by counting pre-retinal nuclei. Retinal pericyte loss was evaluated using retinal trypsin digestion. Electroretinography was performed to examine visual function. No abnormalities were detected in the β-catenin KO mice under normal conditions. In OIR, retinal levels of β-catenin and VEGF were significantly lower in the β-catenin KO mice than in littermate controls. The KO mice also had decreased retinal NV and vascular leakage in the OIR model. In the STZ-induced diabetic model, disruption of β-catenin in Müller cells attenuated over-expression of inflammatory cytokines and ameliorated pericyte dropout in the retina. These findings suggest that Wnt signaling activation in Müller cells contributes to retinal NV, vascular leakage and inflammation and represents a potential therapeutic target for DR.
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Affiliation(s)
- Kelu Kevin Zhou
- Department of Physiology, Harold Hamm Diabetes Center, the University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Siribhinya Benyajati
- Department of Physiology, Harold Hamm Diabetes Center, the University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Yun Le
- Department of Medicine Endocrinology, Harold Hamm Diabetes Center, the University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Rui Cheng
- Department of Physiology, Harold Hamm Diabetes Center, the University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Wenbo Zhang
- Department of Ophthalmology and Visual Sciences, the University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jian-xing Ma
- Department of Physiology, Harold Hamm Diabetes Center, the University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
- * E-mail:
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23
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Quin GJ, Lyons B, Len ACL, Madigan MC, Gillies MC. Proteome changes induced by laser in diabetic retinopathy. Clin Exp Ophthalmol 2014; 43:180-7. [DOI: 10.1111/ceo.12372] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 06/14/2014] [Indexed: 12/01/2022]
Affiliation(s)
- Godfrey J Quin
- Save Sight Institute; Discipline of Clinical Ophthalmology; University of Sydney; Sydney New South Wales Australia
- Australian School of Advanced Medicine; Macquarie University; Sydney New South Wales Australia
| | - Brian Lyons
- Save Sight Institute; Discipline of Clinical Ophthalmology; University of Sydney; Sydney New South Wales Australia
| | - Alice CL Len
- Save Sight Institute; Discipline of Clinical Ophthalmology; University of Sydney; Sydney New South Wales Australia
| | - Michele C Madigan
- Save Sight Institute; Discipline of Clinical Ophthalmology; University of Sydney; Sydney New South Wales Australia
- School of Optometry and Vision Science; University of New South Wales; Sydney New South Wales Australia
| | - Mark C Gillies
- Save Sight Institute; Discipline of Clinical Ophthalmology; University of Sydney; Sydney New South Wales Australia
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Muthusamy A, Lin CM, Shanmugam S, Lindner HM, Abcouwer SF, Antonetti DA. Ischemia-reperfusion injury induces occludin phosphorylation/ubiquitination and retinal vascular permeability in a VEGFR-2-dependent manner. J Cereb Blood Flow Metab 2014; 34:522-31. [PMID: 24398936 PMCID: PMC3948134 DOI: 10.1038/jcbfm.2013.230] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 11/05/2013] [Accepted: 11/25/2013] [Indexed: 02/02/2023]
Abstract
Retinal ischemia-reperfusion (IR) induces neurodegenaration as well as blood-retinal barrier (BRB) breakdown causing vascular permeability. Whereas the neuronal death has been extensively studied, the molecular mechanisms related to BRB breakdown in IR injury remain poorly understood. In this study, we investigated the early changes in tight junctional (TJ) proteins in response to IR injury. Ischemia-reperfusion injury was induced in male rat retinas by increasing the intraocular pressure for 45 minutes followed by natural reperfusion. The results demonstrate that IR injury induced occludin Ser490 phosphorylation and ubiquitination within 15 minutes of reperfusion with subsequent vascular permeability. Immunohistochemical analysis revealed a rapid increase in occludin Ser490 phosphorylation and loss of Zonula occludens-1 (ZO-1) protein, particularly in arterioles. Ischemia-reperfusion injury also rapidly induced the activation and phosphorylation of vascular endothelial growth factor receptor-2 (VEGFR-2) at tyrosine 1175. Blocking vascular endothelial growth factor (VEGF) function by intravitreal injection of bevacizumab prevented VEGFR-2 activation, occludin phosphorylation, and vascular permeability. These studies suggest a novel mechanism of occludin Ser490 phosphorylation and ubiquitination downstream of VEGFR2 activation associated with early IR-induced vascular permeability.
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Affiliation(s)
- Arivalagan Muthusamy
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan, USA
| | - Cheng-Mao Lin
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan, USA
| | - Sumathi Shanmugam
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan, USA
| | - Heather M Lindner
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan, USA
| | - Steven F Abcouwer
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan, USA
| | - David A Antonetti
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan, USA
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Grazul-Bilska AT, Borowicz PP, Reynolds LP, Redmer DA. Vascular perfusion with fluorescent labeled lectin to study ovarian functions. Acta Histochem 2013; 115:893-8. [PMID: 23622682 DOI: 10.1016/j.acthis.2013.03.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 03/11/2013] [Accepted: 03/12/2013] [Indexed: 12/23/2022]
Abstract
The aim of this study was to optimize a method to visualize tissue vascularity by perfusing the local vascular bed with a fluorescently labeled lectin, combined with immunofluorescent labeling of selected vascular/tissue markers. Ovaries with the pedicle were obtained from adult non-pregnant ewes. Immediately after collection, the ovarian artery was perfused with phosphate buffered saline (PBS) to remove blood cells, followed by perfusion with PBS containing fluorescently labeled Griffonia (Bandeiraea) simplicifolia (BS1) lectin. Then, half of ovary was fixed in formalin and another half in Carnoy's fixative. BS1 was detected in blood vessels in ovaries fixed in formalin, but not in Carnoy's fixative. Formalin fixed tissue was used for immunofluorescence staining of two markers of tissue function and/or structure, Ki67 and smooth muscle cell actin (SMCA). Ki67 was detected in granulosa and theca cells, luteal and stromal tissue, and a portion of Ki67 staining was co-localized with blood vessels. SMCA was detected in pericytes within the capillary system, in blood vessels in all ovarian compartments, and in the stroma. Thus, blood vessel perfusion with fluorescently labeled lectin combined with immunohistochemistry, microscopy, and imaging techniques provide an excellent tool to study angiogenesis, vascular architecture, and organ structures and function in physiological and pathological conditions.
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Affiliation(s)
- Anna T Grazul-Bilska
- Department of Animal Sciences, North Dakota State University, Fargo, ND 58102, USA.
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Keil JM, Liu X, Antonetti DA. Glucocorticoid induction of occludin expression and endothelial barrier requires transcription factor p54 NONO. Invest Ophthalmol Vis Sci 2013; 54:4007-15. [PMID: 23640037 PMCID: PMC3681474 DOI: 10.1167/iovs.13-11980] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 04/26/2013] [Indexed: 12/31/2022] Open
Abstract
PURPOSE Glucocorticoids (GCs) effectively reduce retinal edema and induce vascular barrier properties but possess unwanted side effects. Understanding GC induction of barrier properties may lead to more effective and specific therapies. Previous work identified the occludin enhancer element (OEE) as a GC-responsive cis-element in the promoters of multiple junctional genes, including occludin, claudin-5, and cadherin-9. Here, we identify two OEE-binding factors and determine their contribution to GC induction of tight junction (TJ) gene expression and endothelial barrier properties. METHODS OEE-binding factors were isolated from human retinal endothelial cells (HREC) using DNA affinity purification followed by MALDI-TOF MS/MS. Chromatin immunoprecipitation (ChIP) assays determined in situ binding. siRNA was used to evaluate the role of trans-acting factors in transcription of TJ genes in response to GC stimulation. Paracellular permeability was determined by quantifying flux through a cell monolayer, whereas transendothelial electrical resistance (TER) was measured using the ECIS system. RESULTS MS/MS analysis of HREC nuclear extracts identified the heterodimer of transcription factors p54/NONO (p54) and polypyrimidine tract-binding protein-associated splicing factor (PSF) as OEE-binding factors, which was confirmed by ChIP assay from GC-treated endothelial cells and rat retina. siRNA knockdown of p54 demonstrated that this factor is necessary for GC induction of occludin and claudin-5 expression. Further, p54 knockdown ablated the pro-barrier effects of GC treatment. CONCLUSIONS p54 is essential for GC-mediated expression of occludin, claudin-5, and barrier induction, and the p54/PSF heterodimer may contribute to normal blood-retinal barrier (BRB) induction in vivo. Understanding the mechanism of GC induction of BRB properties may provide novel therapies for macular edema.
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Affiliation(s)
- Jason M Keil
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, Michigan, USA
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Gonçalves A, Ambrósio AF, Fernandes R. Regulation of claudins in blood-tissue barriers under physiological and pathological states. Tissue Barriers 2013; 1:e24782. [PMID: 24665399 PMCID: PMC3867514 DOI: 10.4161/tisb.24782] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 04/18/2013] [Accepted: 04/23/2013] [Indexed: 01/01/2023] Open
Abstract
Claudins are pivotal building blocks of tight junctions that form the paracellular barrier in epithelia and endothelia. In mammals, claudins are a 27-gene family that encodes tetraspan membrane proteins, playing a crucial role in the formation and integrity of tight junctions and regulate the barrier function. Claudin isoforms are expressed in a tissue- and/or developmental stage-dependent manner. A growing body of evidence indicates that pathological states characterized by neuroinflammation, such as Alzheimer disease, multiple sclerosis, diabetic retinopathy and retinopathy of prematurity share a common feature: the barrier breakdown. This review aims integrating and summarizing the most relevant and recent work developed in the field of claudins, with particular attention to their role in blood-brain and blood-retinal barriers, as well as describing their regulation in the aforementioned human diseases.
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Affiliation(s)
- Andreia Gonçalves
- Laboratory of Pharmacology and Experimental Therapeutics; IBILI - Institute for Biomedical Imaging and Life Sciences; Faculty of Medicine; University of Coimbra; Coimbra, Portugal
| | - António Francisco Ambrósio
- Centre of Ophthalmology and Vision Sciences; IBILI; Faculty of Medicine; University of Coimbra; Coimbra, Portugal ; AIBILI; Coimbra, Portugal
| | - Rosa Fernandes
- Laboratory of Pharmacology and Experimental Therapeutics; IBILI - Institute for Biomedical Imaging and Life Sciences; Faculty of Medicine; University of Coimbra; Coimbra, Portugal ; Centre of Ophthalmology and Vision Sciences; IBILI; Faculty of Medicine; University of Coimbra; Coimbra, Portugal
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Shin JY, Sohn J, Park KH. Chlorogenic acid decreases retinal vascular hyperpermeability in diabetic rat model. J Korean Med Sci 2013; 28:608-13. [PMID: 23579598 PMCID: PMC3617316 DOI: 10.3346/jkms.2013.28.4.608] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 02/15/2013] [Indexed: 11/20/2022] Open
Abstract
To evaluate the effect of chlorogenic acid (CGA), a polyphenol abundant in coffee, on retinal vascular leakage in the rat model of diabetic retinopathy, Sprague-Dawley rats were divided into four groups: controls, streptozotocin-induced diabetic rats, and diabetic rats treated with 10 and 20 mg/kg chlorogenic acid intraperitoneally daily for 14 days, respectively. Blood-retinal barrier (BRB) breakdown was evaluated using FITC-dextran. Vascular endothelial growth factor (VEGF) distribution and expression level was evaluated with immunohistochemistry and Western blot analysis. Expression of tight junction proteins, occludin and claudin-5, and zonula occludens protein, ZO-1 was also evaluated with immunohistochemistry and Western blot analysis. BRB breakdown and increased vascular leakage was found in diabetic rats, with increased VEGF expression and down-regulation of occludin, claudin-5, and ZO-1. CGA treatment effectively preserved the expression of occludin, and decreased VEGF levels, leading to less BRB breakdown and less vascular leakage. CGA may have a preventive role in BRB breakdown in diabetic retinopathy by preserving tight junction protein levels and low VEGF levels.
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Affiliation(s)
- Joo Young Shin
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea
| | | | - Kyu Hyung Park
- Department of Ophthalmology, Seoul National University Bundang Hospital, Seongnam, Korea
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Klaassen I, Van Noorden CJF, Schlingemann RO. Molecular basis of the inner blood-retinal barrier and its breakdown in diabetic macular edema and other pathological conditions. Prog Retin Eye Res 2013; 34:19-48. [PMID: 23416119 DOI: 10.1016/j.preteyeres.2013.02.001] [Citation(s) in RCA: 444] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 12/19/2012] [Accepted: 02/01/2013] [Indexed: 12/16/2022]
Abstract
Breakdown of the inner endothelial blood-retinal barrier (BRB), as occurs in diabetic retinopathy, age-related macular degeneration, retinal vein occlusions, uveitis and other chronic retinal diseases, results in vasogenic edema and neural tissue damage, causing loss of vision. The central mechanism of altered BRB function is a change in the permeability characteristics of retinal endothelial cells caused by elevated levels of growth factors, cytokines, advanced glycation end products, inflammation, hyperglycemia and loss of pericytes. Subsequently, paracellular but also transcellular transport across the retinal vascular wall increases via opening of endothelial intercellular junctions and qualitative and quantitative changes in endothelial caveolar transcellular transport, respectively. Functional changes in pericytes and astrocytes, as well as structural changes in the composition of the endothelial glycocalyx and the basal lamina around BRB endothelium further facilitate BRB leakage. As Starling's rules apply, active transcellular transport of plasma proteins by the BRB endothelial cells causing increased interstitial osmotic pressure is probably the main factor in the formation of macular edema. The understanding of the complex cellular and molecular processes involved in BRB leakage has grown rapidly in recent years. Although appropriate animal models for human conditions like diabetic macular edema are lacking, these insights have provided tools for rational design of drugs aimed at restoring the BRB as well as for design of effective transport of drugs across the BRB, to treat the chronic retinal diseases such as diabetic macular edema that affect the quality-of-life of millions of patients.
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Affiliation(s)
- Ingeborg Klaassen
- Ocular Angiogenesis Group, Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Bhattacharjee PS, Huq TS, Potter V, Young A, Davenport IR, Graves R, Mandal TK, Clement C, McFerrin HE, Muniruzzaman S, Ireland SK, Hill JM. High-glucose-induced endothelial cell injury is inhibited by a Peptide derived from human apolipoprotein E. PLoS One 2012; 7:e52152. [PMID: 23284911 PMCID: PMC3526597 DOI: 10.1371/journal.pone.0052152] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 11/08/2012] [Indexed: 11/17/2022] Open
Abstract
Although the importance of human apolipoprotein E (apoE) in vascular diseases has clearly been established, most of the research on apoE has focused on its role in cholesterol metabolism. In view of the observation that apoE and its functional domains impact extracellular matrix (ECM) remodeling, we hypothesized that apoE could also confer protection against ECM degradation by mechanisms independent of its role in cholesterol and lipoprotein transport. The ECM degrading enzyme, heparanase, is secreted by cells as pro-heparanase that is internalized through low-density lipoprotein (LDL) receptor-related protein-1 (LRP-1) to become enzymatically active. Both apoE and pro-heparanase bind the LRP-1. We further hypothesized that an apoE mimetic peptide (apoEdp) would inhibit the production of active heparanase by blocking LRP-1-mediated uptake of pro-heparanase and thereby decrease degradation of the ECM. To test this hypothesis, we induced the expression of heparanase by incubating human retinal endothelial cells (hRECs) with high glucose (30 mM) for 72 hours. We found that elevated expression of heparanase by high glucose was associated with increased shedding of heparan sulfate (ΔHS) and the tight junction protein occludin. Treatment of hRECs with 100 µM apoEdp in the presence of high glucose significantly reduced the expression of heparanase, shedding of ΔHS, and loss of occludin as detected by Western blot analysis. Either eye drop treatment of 1% apoEdp topically 4 times a day for 14 consecutive days or intraperitoneal injection (40 mg/kg) of apoEdp daily for 14 consecutive days in an in vivo mouse model of streptozotocin-induced diabetes inhibited the loss of tight junction proteins occludin and zona occludin- 1 (ZO-1). These findings imply a functional relationship between apoE and endothelial cell matrix because the deregulation of these molecules can be inhibited by a short peptide derived from the receptor-binding region of apoE. Thus, strategies targeting ECM-degrading enzymes could be therapeutically beneficial for treating diabetic retinopathy.
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Novel atypical PKC inhibitors prevent vascular endothelial growth factor-induced blood-retinal barrier dysfunction. Biochem J 2012; 446:455-67. [PMID: 22721706 DOI: 10.1042/bj20111961] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Pro-inflammatory cytokines and growth factors such as VEGF (vascular endothelial growth factor) contribute to the loss of the BRB (blood-retinal barrier) and subsequent macular oedema in various retinal pathologies. VEGF signalling requires PKCβ [conventional PKC (protein kinase C)] activity; however, PKCβ inhibition only partially prevents VEGF-induced endothelial permeability and does not affect pro-inflammatory cytokine-induced permeability, suggesting the involvement of alternative signalling pathways. In the present study, we provide evidence for the involvement of aPKC (atypical PKC) signalling in VEGF-induced endothelial permeability and identify a novel class of inhibitors of aPKC that prevent BRB breakdown in vivo. Genetic and pharmacological manipulations of aPKC isoforms were used to assess their contribution to endothelial permeability in culture. A chemical library was screened using an in vitro kinase assay to identify novel small-molecule inhibitors, and further medicinal chemistry was performed to delineate a novel pharmacophore. We demonstrate that aPKC isoforms are both sufficient and required for VEGF-induced endothelial permeability. Furthermore, these specific, potent, non-competitive, small-molecule inhibitors prevented VEGF-induced tight junction internalization and retinal endothelial permeability in response to VEGF in both primary culture and in rodent retina. The results of the present study suggest that aPKC inhibition with 2-amino-4-phenyl-thiophene derivatives may be developed to preserve the BRB in retinal diseases such as diabetic retinopathy or uveitis, and the BBB (blood-brain barrier) in the presence of brain tumours.
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INHIBITORY ACTIVITY OF RANIBIZUMAB, SORAFENIB, AND PAZOPANIB ON LIGHT-INDUCED OVEREXPRESSION OF PLATELET-DERIVED GROWTH FACTOR AND VASCULAR ENDOTHELIAL GROWTH FACTOR A AND THE VASCULAR ENDOTHELIAL GROWTH FACTOR A RECEPTORS 1 AND 2 AND NEUROPILIN 1 AND 2. Retina 2012; 32:1652-63. [DOI: 10.1097/iae.0b013e318240a558] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Wisniewska-Kruk J, Hoeben KA, Vogels IMC, Gaillard PJ, Van Noorden CJF, Schlingemann RO, Klaassen I. A novel co-culture model of the blood-retinal barrier based on primary retinal endothelial cells, pericytes and astrocytes. Exp Eye Res 2011; 96:181-90. [PMID: 22200486 DOI: 10.1016/j.exer.2011.12.003] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 11/11/2011] [Accepted: 12/03/2011] [Indexed: 12/13/2022]
Abstract
Loss of blood-retinal barrier (BRB) properties is an important feature in the pathology of diabetic macular edema (DME), but cellular mechanisms underlying BRB dysfunction are poorly understood. Therefore, we developed and characterized a novel in vitro BRB model, based on primary bovine retinal endothelial cells (BRECs). These cells were shown to maintain specific in vivo BRB properties by expressing high levels of the endothelial junction proteins occludin, claudin-5, VE-cadherin and ZO-1 at cell borders, and the specific pumps glucose transporter-1 (GLUT1) and efflux transporter P-glycoprotein (MDR1). To investigate the influence of pericytes and astrocytes on BRB maintenance in vitro, we compared five different co-culture BRB models, based on BRECs, bovine retinal pericytes (BRPCs) and rat glial cells. Co-cultures of BRECs with BRPCs and glial cells showed the highest trans-endothelial resistance (TEER) as well as decreased permeability of tracers after vascular endothelial growth factor (VEGF) stimulation, suggesting a major role for these cell types in maintaining barrier properties. To mimic the in vivo situation of DME, we stimulated BRECs with VEGF, which downregulated MDR1 and GLUT1 mRNA levels, transiently reduced expression levels of endothelial junctional proteins and altered their organization, increased the number of intercellular gaps in BRECs monolayers and influence the permeability of the model to differently-sized molecular tracers. Moreover, as has been shown in vivo, expression of plasmalemma vesicle-associated protein (PLVAP) was increased in endothelial cells in the presence of VEGF. This in vitro model is the first co-culture model of the BRB that mimicks in vivo VEGF-dependent changes occurring in DME.
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Frey T, Antonetti DA. Alterations to the blood-retinal barrier in diabetes: cytokines and reactive oxygen species. Antioxid Redox Signal 2011; 15:1271-84. [PMID: 21294655 DOI: 10.1089/ars.2011.3906] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Diabetic retinopathy (DR) is a leading cause of blindness in Western society. Since the prevalence of diabetes continues to increase dramatically, the impact of DR will only worsen unless new therapeutic options are developed. Recent data demonstrate that oxidative stress contributes to the pathology of DR and inhibition of oxidative stress reduces retinal vascular permeability. However, direct mechanisms by which oxidative stress alters the blood-retinal barrier (BRB) and increases vascular permeability remain to be elucidated. A large body of evidence demonstrates a clear role for altered expression of cytokines and growth factors in DR, resulting in increased vascular permeability, and the molecular mechanisms for these processes are beginning to emerge. The pathology of DR is likely a result of metabolic dysregulation contributing to both oxidative stress and cytokine production. This review will examine the evidence for oxidative stress, growth factors, and other cytokines in tight junction regulation and vascular permeability in DR.
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Affiliation(s)
- Tiffany Frey
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA
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Runkle EA, Sundstrom JM, Runkle KB, Liu X, Antonetti DA. Occludin localizes to centrosomes and modifies mitotic entry. J Biol Chem 2011; 286:30847-30858. [PMID: 21757728 DOI: 10.1074/jbc.m111.262857] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proper control of cell cycle progression and barrier function are essential processes to the maintenance of epithelial cell homeostasis. The contribution of tight junction proteins to barrier function is well established, whereas their contribution to cell cycle control is only beginning to be understood. Centrosomes are the principal microtubule organizing centers in eukaryotic cells and centrosome duplication and separation are linked to the cell cycle and mitotic entry. Here we demonstrate that occludin localizes with centrosomes in Madin-Darby canine kidney cells. Immunocytochemistry and biochemical fractionation studies reveal occludin localizes with centrosomes during interphase and occludin Ser-490 phosphorylation at centrosomes increases with mitotic entry. Stable expression of aspartic acid phosphomimetic (S490D) results in centrosomal localization of occludin and increases cell numbers. Furthermore, we provide evidence that occludin regulates centrosome separation and mitotic entry as the nonphosphorylatable alanine mutation (S490A) impedes centrosome separation, delays mitotic entry, and reduces proliferation. Collectively, these studies demonstrate a novel location and function for occludin in centrosome separation and mitosis.
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Affiliation(s)
- E Aaron Runkle
- Departments of Cellular and Molecular Physiology, Hershey, Pennsylvania 17033
| | - Jeffrey M Sundstrom
- Ophthalmology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033
| | - Kristin B Runkle
- Departments of Cellular and Molecular Physiology, Hershey, Pennsylvania 17033
| | - Xuwen Liu
- University of Michigan Kellogg Eye Center, Ann Arbor, Michigan 48105
| | - David A Antonetti
- University of Michigan Kellogg Eye Center, Ann Arbor, Michigan 48105.
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Huang H, Gandhi JK, Zhong X, Wei Y, Gong J, Duh EJ, Vinores SA. TNFalpha is required for late BRB breakdown in diabetic retinopathy, and its inhibition prevents leukostasis and protects vessels and neurons from apoptosis. Invest Ophthalmol Vis Sci 2011; 52:1336-44. [PMID: 21212173 DOI: 10.1167/iovs.10-5768] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
PURPOSE Blood-retinal barrier [BRB] breakdown, characteristic of diabetic retinopathy (DR), is believed to depend on inflammation and apoptosis. Retinal inflammation is almost completely suppressed in the absence of TNFα, which is also associated with apoptosis. This study was conducted to determine the role of TNFα in these diabetic complications. METHODS Diabetes was induced with streptozotocin in Tnfa knockout (KO) mice, to provide a chemical model of diabetes, and Tnfa (KO) mice were crossed with Ins2(Akita) mice to generate a genetic model, with both models being devoid of TNFα. The BRB was assessed at 1, 1.5, 3, and 6 months. Leukostasis was assessed using FITC-conjugated ConA to label leukocytes. Apoptosis was assessed with TUNEL and activated caspase-3 staining. PECAM1 identified endothelial cells, and SMA identified pericytes. RESULTS At 1 month of diabetes, the absence of TNFα had no effect on DR-associated BRB breakdown, even though it prevented retinal leukostasis, demonstrating that neither TNFα nor inflammation is essential for early BRB breakdown in DR in either model of diabetes. At 3 months of diabetes, BRB breakdown was significantly suppressed and at 6 months, it was completely prevented in the absence of TNFα in both models, showing that TNFα is essential for progressive BRB breakdown. DR-mediated apoptosis in the retina, which appears to involve endothelial cells, pericytes, and neurons, was inhibited in the absence of TNFα in both models. CONCLUSIONS Although neither TNFα nor inflammation is necessary for early BRB breakdown in DR, TNFα is critical for later complications and would be a good therapeutic target for the prevention of the progressive BRB breakdown, retinal leukostasis, and apoptosis associated with DR.
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Affiliation(s)
- Hu Huang
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA
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Lopez-Quintero SV, Ji XY, Antonetti DA, Tarbell JM. A three-pore model describes transport properties of bovine retinal endothelial cells in normal and elevated glucose. Invest Ophthalmol Vis Sci 2011; 52:1171-80. [PMID: 21357410 DOI: 10.1167/iovs.10-5971] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Changes in blood vessel barrier properties contribute to retinal edema in diabetic retinopathy (DR). However, limited data are available to describe the routes of transport for fluids and solutes across the inner blood-retinal barrier (iBRB). In this study, a three-pore model was developed to characterize such routes in normal and elevated glucose levels. METHODS Diffusive and apparent permeabilities to TAMRA (467 Da), dextran (70 kDa), and LDL (2000 kDa), as well as hydraulic conductivity, were measured across bovine retinal endothelial cell (BREC) monolayers after exposure to normal- and high-glucose media for 6 days. The data were used to develop a model of transport dynamics. Claudin 5 and eNOS Western blot analysis were used to measure changes in expression and phosphorylation. Immunolocalization of ZO-1 and VE-cadherin demonstrated organization of the junctional complex. Apoptosis was measured by TUNEL assay. RESULTS A three-pore model describes the fractional transport of water and molecular tracers across the retinal endothelial barrier. No change in permeability or hydraulic conductivity was observed after exposure to high glucose, whereas VEGF increased permeability in both normal- and high-glucose environments. The transport results were consistent with ZO-1 and VE-cadherin immunocytochemistry and expression of claudin-5, which were all unaltered by high glucose. CONCLUSIONS The data describe, for the first time, a model for transport of various size solutes and fluids across endothelial cells of the iBRB. Further, the results support the existence of an indirect pathway by which iBRB permeability is increased through the upregulation of retinal VEGF in response to hyperglycemia.
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Affiliation(s)
- Sandra V Lopez-Quintero
- Department of Biomedical Engineering, The City College of The City University of New York, New York, New York 10031, USA
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Barber AJ, Gardner TW, Abcouwer SF. The significance of vascular and neural apoptosis to the pathology of diabetic retinopathy. Invest Ophthalmol Vis Sci 2011; 52:1156-63. [PMID: 21357409 DOI: 10.1167/iovs.10-6293] [Citation(s) in RCA: 291] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The most striking features of diabetic retinopathy are the vascular abnormalities that are apparent by fundus examination. There is also strong evidence that diabetes causes apoptosis of neural and vascular cells in the retina. Thus, there is good reason to define diabetic retinopathy as a form of chronic neurovascular degeneration. In keeping with the gradual onset of retinopathy in humans, the rate of cell loss in the animal models is insidious, even in uncontrolled diabetes. This is not surprising given that a sustained high rate of cell loss without regeneration would soon lead to catastrophic tissue destruction. The consequences of ongoing cell death are difficult to detect, and even the quantification of cumulative cell loss requires painstaking histology and microscopy. This subtle cell loss raises the issue of the relevance of the phenomenon to the progression of diabetic retinopathy and the ultimate loss of vision. Neuronal function may be compromised in advance of apoptosis, contributing to an early deterioration of vision. Here we review some of the evidence supporting apoptotic cell death as a contributing mechanism of diabetic retinopathy, explore some of the potential causes, and discuss the potential links between apoptosis and loss of visual function in diabetic retinopathy.
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Affiliation(s)
- Alistair J Barber
- Department of Ophthalmology, Penn State Hershey Eye Center, Penn State Hershey College of Medicine, Hershey, Pennsylvania 17033, USA.
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Kernt M, Thiele S, Hirneiss C, Neubauer A, Lackerbauer C, Wolf A, Eibl K, Haritoglou C, Ulbig M, Kampik A. Zytoprotektive und antiangiogene Wirkung des Multikinaseinhibitors Sorafenib im retinalen Pigmentepithel. Ophthalmologe 2011; 108:445-51. [DOI: 10.1007/s00347-010-2304-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Runkle EA, Antonetti DA. The blood-retinal barrier: structure and functional significance. Methods Mol Biol 2011; 686:133-48. [PMID: 21082369 DOI: 10.1007/978-1-60761-938-3_5] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Formation and maintenance of the blood-retinal barrier is required for proper vision and loss of this barrier contributes to the pathology of a wide number of retinal diseases. The retina is responsible for converting visible light into the electrochemical signal interpreted by the brain as vision. Multiple cell types are required for this function, which are organized into eight distinct cell layers. These neural and glial cells gain metabolic support from a unique vascular structure that provides the necessary nutrients while minimizing interference with light sensing. In addition to the vascular contribution, the retina also possesses an epithelial barrier, the retinal pigment epithelium, which is located at the posterior of the eye and controls exchange of nutrients with the choroidal vessels. Together the vascular and epithelial components of the blood-retinal barrier maintain the specialized environment of the neural retina. Both the vascular endothelium and pigment epithelium possess a well-developed junctional complex that includes both adherens and tight junctions conferring a high degree of control of solute and fluid permeability. Understanding induction and regulation of the blood-retinal barrier will allow the development of therapies aimed at restoring the barrier when compromised in disease or allowing the specific transport of therapies across this barrier when needed. This chapter will highlight the anatomical structure of the blood-retinal barrier and explore the molecular structure of the tight junctions that provide the unique barrier properties of the blood--retinal barrier.
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Affiliation(s)
- E Aaron Runkle
- Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, USA
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Aveleira CA, Lin CM, Abcouwer SF, Ambrósio AF, Antonetti DA. TNF-α signals through PKCζ/NF-κB to alter the tight junction complex and increase retinal endothelial cell permeability. Diabetes 2010; 59:2872-82. [PMID: 20693346 PMCID: PMC2963546 DOI: 10.2337/db09-1606] [Citation(s) in RCA: 302] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Tumor necrosis factor-α (TNF-α) and interleukin-1 beta (IL-1β) are elevated in the vitreous of diabetic patients and in retinas of diabetic rats associated with increased retinal vascular permeability. However, the molecular mechanisms underlying retinal vascular permeability induced by these cytokines are poorly understood. In this study, the effects of IL-1β and TNF-α on retinal endothelial cell permeability were compared and the molecular mechanisms by which TNF-α increases cell permeability were elucidated. RESEARCH DESIGN AND METHODS Cytokine-induced retinal vascular permeability was measured in bovine retinal endothelial cells (BRECs) and rat retinas. Western blotting, quantitative real-time PCR, and immunocytochemistry were performed to determine tight junction protein expression and localization. RESULTS IL-1β and TNF-α increased BREC permeability, and TNF-α was more potent. TNF-α decreased the protein and mRNA content of the tight junction proteins ZO-1 and claudin-5 and altered the cellular localization of these tight junction proteins. Dexamethasone prevented TNF-α-induced cell permeability through glucocorticoid receptor transactivation and nuclear factor-kappaB (NF-κB) transrepression. Preventing NF-κB activation with an inhibitor κB kinase (IKK) chemical inhibitor or adenoviral overexpression of inhibitor κB alpha (IκBα) reduced TNF-α-stimulated permeability. Finally, inhibiting protein kinase C zeta (PKCζ) using both a peptide and a novel chemical inhibitor reduced NF-κB activation and completely prevented the alterations in the tight junction complex and cell permeability induced by TNF-α in cell culture and rat retinas. CONCLUSIONS These results suggest that PKCζ may provide a specific therapeutic target for the prevention of vascular permeability in retinal diseases characterized by elevated TNF-α, including diabetic retinopathy.
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Affiliation(s)
- Célia A Aveleira
- Centre of Ophthalmology and Vision Sciences, Institute of Biomedical Research in Light and Image, Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
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Leal EC, Martins J, Voabil P, Liberal J, Chiavaroli C, Bauer J, Cunha-Vaz J, Ambrósio AF. Calcium dobesilate inhibits the alterations in tight junction proteins and leukocyte adhesion to retinal endothelial cells induced by diabetes. Diabetes 2010; 59:2637-45. [PMID: 20627932 PMCID: PMC3279541 DOI: 10.2337/db09-1421] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE Calcium dobesilate (CaD) has been used in the treatment of diabetic retinopathy in the last decades, but its mechanisms of action are not elucidated. CaD is able to correct the excessive vascular permeability in the retina of diabetic patients and in experimental diabetes. We investigated the molecular and cellular mechanisms underlying the protective effects of CaD against the increase in blood-retinal barrier (BRB) permeability induced by diabetes. RESEARCH DESIGN AND METHODS Wistar rats were divided into three groups: controls, streptozotocin-induced diabetic rats, and diabetic rats treated with CaD. The BRB breakdown was evaluated using Evans blue. The content or distribution of tight junction proteins (occludin, claudin-5, and zonula occluden-1 [ZO-1]), intercellular adhesion molecule-1 (ICAM-1), and p38 mitogen-activated protein kinase (p38 MAPK) was evaluated by Western blotting and immunohistochemistry. Leukocyte adhesion was evaluated in retinal vessels and in vitro. Oxidative stress was evaluated by the detection of oxidized carbonyls and tyrosine nitration. NF-κB activation was measured by enzyme-linked immunosorbent assay. RESULTS Diabetes increased the BRB permeability and retinal thickness. Diabetes also decreased occludin and claudin-5 levels and altered the distribution of ZO-1 and occludin in retinal vessels. These changes were inhibited by CaD treatment. CaD also inhibited the increase in leukocyte adhesion to retinal vessels or endothelial cells and in ICAM-1 levels, induced by diabetes or elevated glucose. Moreover, CaD decreased oxidative stress and p38 MAPK and NF-κB activation caused by diabetes. CONCLUSIONS CaD prevents the BRB breakdown induced by diabetes, by restoring tight junction protein levels and organization and decreasing leukocyte adhesion to retinal vessels. The protective effects of CaD are likely to involve the inhibition of p38 MAPK and NF-κB activation, possibly through the inhibition of oxidative/nitrosative stress.
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Affiliation(s)
- Ermelindo C Leal
- Center of Ophthalmology and Vision Sciences, IBILI, Faculty of Medicine, University of Coimbra, Coimbra, Portugal.
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Wang J, Xu X, Elliott MH, Zhu M, Le YZ. Müller cell-derived VEGF is essential for diabetes-induced retinal inflammation and vascular leakage. Diabetes 2010; 59:2297-305. [PMID: 20530741 PMCID: PMC2927953 DOI: 10.2337/db09-1420] [Citation(s) in RCA: 283] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Vascular endothelial growth factor (VEGF-A or VEGF) is a major pathogenic factor and therapeutic target for diabetic retinopathy (DR). Since VEGF has been proposed as a survival factor for retinal neurons, defining the cellular origin of pathogenic VEGF is necessary for the effectiveness and safety of long-term anti-VEGF therapies for DR. To determine the significance of Müller cell-derived VEGF in DR, we disrupted VEGF in Müller cells with an inducible Cre/lox system and examined diabetes-induced retinal inflammation and vascular leakage in these conditional VEGF knockout (KO) mice. RESEARCH DESIGN AND METHODS Leukostasis was determined by counting the number of fluorescently labeled leukocytes inside retinal vasculature. Expression of biomarkers for retinal inflammation was assessed by immunoblotting of TNF-alpha, ICAM-1, and NF-kappaB. Vascular leakage was measured by immunoblotting of retinal albumin and fluorescent microscopic analysis of extravascular albumin. Diabetes-induced vascular alterations were examined by immunoblotting and immunohistochemistry for tight junctions, and by trypsin digestion assays for acellular capillaries. Retinal integrity was analyzed with morphologic and morphometric analyses. RESULTS Diabetic conditional VEGF KO mice exhibited significantly reduced leukostasis, expression of inflammatory biomarkers, depletion of tight junction proteins, numbers of acellular capillaries, and vascular leakage compared to diabetic control mice. CONCLUSIONS Müller cell-derived VEGF plays an essential and causative role in retinal inflammation, vascular lesions, and vascular leakage in DR. Therefore, Müller cells are a primary cellular target for proinflammatory signals that mediates retinal inflammation and vascular leakage in DR.
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Affiliation(s)
- Juanjuan Wang
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
- Department of Medicine Endocrinology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Harold Hamm Oklahoma Diabetes Center, University of Oklahoma, Oklahoma City, Oklahoma
| | - Xueliang Xu
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, China
| | - Michael H. Elliott
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Dean A. McGee Eye Institute, Oklahoma City, Oklahoma
| | - Meili Zhu
- Department of Medicine Endocrinology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Harold Hamm Oklahoma Diabetes Center, University of Oklahoma, Oklahoma City, Oklahoma
| | - Yun-Zheng Le
- Department of Medicine Endocrinology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Harold Hamm Oklahoma Diabetes Center, University of Oklahoma, Oklahoma City, Oklahoma
- Dean A. McGee Eye Institute, Oklahoma City, Oklahoma
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
- Corresponding author: Yun-Zheng Le,
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Powner MB, Gillies MC, Tretiach M, Scott A, Guymer RH, Hageman GS, Fruttiger M. Perifoveal müller cell depletion in a case of macular telangiectasia type 2. Ophthalmology 2010; 117:2407-16. [PMID: 20678804 DOI: 10.1016/j.ophtha.2010.04.001] [Citation(s) in RCA: 188] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 03/09/2010] [Accepted: 04/02/2010] [Indexed: 02/01/2023] Open
Abstract
PURPOSE To assess the histopathologic changes in a postmortem sample derived from an eye donor with macular telangiectasia (MacTel) type 2 to gain further insight into the cause of the disease. DESIGN Clinicopathological case report. PARTICIPANTS Postmortem tissue was collected from 5 different donors: 1 MacTel type 2 patient; 1 healthy control; 2 type 2 diabetic patients, 1 with retinopathy and 1 without retinopathy; and 1 patient with unilateral Coat's disease. METHODS Macular pigment distribution in the posterior part of freshly dissected eyes was documented by macrophotography. Paraffin sections from both the macular and peripheral regions were assessed using antigen retrieval and immunohistochemistry to study the distribution of cell-specific markers. Blood vessels were visualized with antibodies directed against collagen IV and claudin 5; glial cells with antibodies against glial fibrillary acidic protein (GFAP), vimentin, glutamine synthetase (GS), and retinaldehyde binding protein (RLBP1, also known as CRALBP); microglia with an antibody against allograft inflammatory factor 1 (also known as Iba1); and photoreceptors with antibodies against rhodopsin and opsin. Using anatomic landmarks, the sections then were matched with the macular pigment distribution and a fluorescein angiogram of the patient that was obtained before the patient's death. MAIN OUTCOME MEASURES Presence and distribution of macular pigment and cell-specific markers. RESULTS Macular pigment was absent in the macula. Furthermore, abnormally dilated capillaries were identified in a macular region that correlated spatially with regions of fluorescein leakage in an angiogram that was obtained 12 years before death. These telangiectatic vessels displayed a marked reduction of the basement membrane component collagen IV, indicating vascular pathologic features. The presence of GFAP was limited to retinal astrocytes, and no reactive Müller cells were identified. Importantly, reduced immunoreactivity with Müller cell markers (vimentin, GS, and RLBP1) in the macula was observed. The area that lacked Müller cells corresponded with the region of depleted macular pigment. CONCLUSIONS These findings suggest that macular Müller cell loss or dysfunction is a critical component of MacTel type 2, which may have implications for future treatment strategies.
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Affiliation(s)
- Michael B Powner
- MacTel Laboratory Research Group, Department of Cell Biology, UCL Institute of Ophthalmology, University College London, London, UK
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Propes B, Poon D, Do DV. Role of intraocular steroids for the treatment of diabetic macular edema. EXPERT REVIEW OF OPHTHALMOLOGY 2009. [DOI: 10.1586/eop.09.30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Zhang X, Bao S, Hambly BD, Gillies MC. Vascular endothelial growth factor-A: a multifunctional molecular player in diabetic retinopathy. Int J Biochem Cell Biol 2009; 41:2368-71. [PMID: 19646547 DOI: 10.1016/j.biocel.2009.07.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 07/18/2009] [Accepted: 07/21/2009] [Indexed: 01/08/2023]
Abstract
Vascular endothelial growth factor-A (VEGF-A), first described as "vascular permeability factor", is a critical molecule in the pathogenesis of diabetic retinopathy at several levels. Previous studies have outlined the importance of VEGF-A in mediating vascular pathology in both experimental models and clinical diabetic retinopathy, which are characterized by retinal vascular leakage, preretinal neovascularisation and neuronal degeneration. Paradoxically, recent reports have emphasized the potential neurotrophic effects of VEGF-A on the quiescent vasculature, as well as its direct and indirect protective effects on retinal neurons. VEGF-A has also been identified as an important signalling regulator in the normal central nervous system. Consequently, anti-VEGF therapy for diabetic retinopathy has become a controversal issue. This review outlines recently developed concepts relating to the role of VEGF-A in the pathogenesis of diabetic retinopathy, with particular emphasis on its implications for clinical practice.
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Affiliation(s)
- Xinyuan Zhang
- Retinal Therapeutics Research Group, Save Sight Institute, Department of Clinical Ophthalmology, The University of Sydney, Level 2, South Block, Sydney Eye Hospital, Macquarie St, Sydney, NSW 2000, Australia.
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Felinski EA, Antonetti DA. Glucocorticoid Regulation of Endothelial Cell Tight Junction Gene Expression: Novel Treatments for Diabetic Retinopathy. Curr Eye Res 2009; 30:949-57. [PMID: 16282129 DOI: 10.1080/02713680500263598] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Loss of blood-retinal barrier (BRB) integrity and vascular permeability characterizes diabetic retinopathy, and new therapies to reverse or prevent vascular permeability are needed to treat this debilitating disease. Glucocorticoids are currently under investigation for use as a local therapeutic treatment for diabetic retinopathy. This review examines the changes that occur to barrier properties in diabetic retinopathy and the potential to use glucocorticoids to restore vascular barrier properties in the retina. Glucocorticoids are useful in preserving the integrity of the blood-brain barrier in the treatment of brain tumors, and these steroids show similar effects on the retinal vasculature suggesting their potential usefulness in treating diabetic retinopathy. Recent progress has been made toward the goal of elucidating the precise mechanism underlying the protective effects of glucocorticoids on the retinal vasculature. Glucocorticoids may act by both suppressing inflammation and by directly affecting the endothelial cells by regulating phosphorylation, organization, and content of tight junction proteins. Further work will advance our understanding of glucocorticoid regulation of barrier properties allowing the ultimate goal of developing a specific and safe therapy to treat or prevent loss of the blood-neural barrier in a number of diseases, including brain tumors and diabetic retinopathy.
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Affiliation(s)
- Edward A Felinski
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA.
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Campbell M, Collery R, McEvoy A, Gardiner TA, Stitt AW, Brankin B. Involvement of MAPKs in Endostatin-Mediated Regulation of Blood-Retinal Barrier Function. Curr Eye Res 2009; 31:1033-45. [PMID: 17169842 DOI: 10.1080/02713680601013025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE This study aimed to evaluate the effects of endostatin on tight junction (TJ) integrity in retinal microvascular endothelial cells (RMECs) in vitro and in vivo. Moreover, it was hypothesized that endostatin-induced occludin upregulation regulated VEGF165-mediated increases in endothelial cell permeability and involved activation of the MAPK signaling cascade. Endostatin is a 20-kDa fragment of collagen XVIII that has been shown to be efficacious in the eye by preventing retinal neovascularization. Endostatin is a specific inhibitor of endothelial cell proliferation, migration, and angiogenesis and has been reported to reverse VEGF-mediated increases in vasopermeability and to promote integrity of the blood-retinal barrier (BRB). In order to determine the mechanism of endostatin action on BRB integrity, we have examined the effects of endostatin on a number of intracellular pathways implicated in endothelial cell physiology. METHODS C57/Bl6 mice were injected with VEGF165 and/or endostatin, and the distribution of occludin staining was determined using retinal flatmounts. Western blot analysis of RMECs treated with VEGF165 and/or endostatin was used to determine changes in occludin expression and p38 MAPK and extracellular regulated kinase (ERK1/ERK2 MAPK) activation, while FD-4 flux across the RMEC monolayer was used to determine changes in paracellular permeability. RESULTS Endostatin prevented the discontinuous pattern of occludin staining observed at the retinal blood vessels of mice administered an intraocular injection of VEGF165. It was shown that endostatin activated p38 MAPK 5 min after addition to RMECs and continued to do so for approximately 30 min. Endostatin was also shown to activate ERK1/ERK2 5 min after addition and continued to do so, albeit with less potency, up to and including 15 min after addition. Inhibition of p38 MAPK and ERK1/ERK2 prevented endostatin's ability to upregulate levels of occludin expression. Inhibition of these key signaling molecules was shown to prevent endostatin's ability to protect against VEGF165-mediated increases in paracellular permeability in vitro. However, it appears that p38 MAPK may play a more important role in VEGF-mediated permeability, as inhibition of ERK1/ERK2 will not prevent VEGF165-mediated permeability compared with control (untreated) cells or cells treated with both a p38 MAPK inhibitor and VEGF165. CONCLUSIONS Occludin is important for the maintenance of tight junction integrity in vivo. In a p38 MAPK and ERK1/ERK2 dependent manner, endostatin was shown to upregulate the levels of expression of the tight junction protein occludin. Inhibition of these key MAPK components may prevent endostatin's ability to decrease VEGF165-induced paracellular permeability.
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Affiliation(s)
- Matthew Campbell
- UCD School of Biomolecular Biomedical Sciences, Conway Institute, University College Dublin, Dublin, Ireland.
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Yu PK, Yu DY, Cringle SJ, Su EN. Endothelial F-actin Cytoskeleton in the Retinal Vasculature of Normal and Diabetic Rats. Curr Eye Res 2009; 30:279-90. [PMID: 16020258 DOI: 10.1080/02713680590923230] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
PURPOSE The purpose of this study was to characterize the endothelial (EC) F-actin cytoskeleton at different orders of the retinal microvasculature in the normal and diabetic rat and determine if changes in F-actin are associated with different stages of diabetes. METHODS The EC F-actin cytoskeleton distribution, nuclei shape, and capillary diameter in the retinal vasculature of rats after 5 and 28 weeks of streptozotocin (STZ)-induced diabetes were compared to those in age-matched controls. The eyes were enucleated, arterially perfused, and labeled for F-actin cytoskeleton and nuclei (YO-PRO-1) or microvascular leakage (FITC-dextran). Retinal whole mounts were then examined by confocal microscopy. RESULTS The EC F-actin distribution and nuclear size and shape were highly dependent on the location down the vascular tree. The retinal arterial system in the rat shows a high level of F-actin stress fibre (SF) staining. Peripheral border (PB) staining was present in the ECs of all vessels. Diffuse F-actin staining was observed in endothelial cytoplasm in capillaries, venules, and veins. EC nuclei became distinctly less elongated down the vascular tree. In diabetic rats at 5 weeks, at the capillary level the F-actin staining was more diffuse, and areas of F-actin loss were evident. Both dot-like and diffuse leakage was detected in retinal capillaries, and these leakage types were closely associated with the degree of F-actin changes. In diabetic rats at 28 weeks, there was an increased level of SF staining in the arterial system in addition to capillary F-actin changes. CONCLUSIONS The EC F-actin cytoskeleton and nuclei shape retinal microvasculature of the normal rat change with location along the vascular tree. In the early stages of diabetes, there are changes to the F-actin cytoskeleton that are clearly associated with microvascular leakage. F-actin distribution could indicate important structural changes in the pathogenesis of diabetic retinopathy.
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Affiliation(s)
- Paula K Yu
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Western Australia 6009
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Klaassen I, Hughes JM, Vogels IM, Schalkwijk CG, Van Noorden CJ, Schlingemann RO. Altered expression of genes related to blood–retina barrier disruption in streptozotocin-induced diabetes. Exp Eye Res 2009; 89:4-15. [DOI: 10.1016/j.exer.2009.01.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 10/31/2008] [Accepted: 01/12/2009] [Indexed: 11/28/2022]
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