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Bora K, Kushwah N, Maurya M, Pavlovich MC, Wang Z, Chen J. Assessment of Inner Blood-Retinal Barrier: Animal Models and Methods. Cells 2023; 12:2443. [PMID: 37887287 PMCID: PMC10605292 DOI: 10.3390/cells12202443] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 10/07/2023] [Accepted: 10/08/2023] [Indexed: 10/28/2023] Open
Abstract
Proper functioning of the neural retina relies on the unique retinal environment regulated by the blood-retinal barrier (BRB), which restricts the passage of solutes, fluids, and toxic substances. BRB impairment occurs in many retinal vascular diseases and the breakdown of BRB significantly contributes to disease pathology. Understanding the different molecular constituents and signaling pathways involved in BRB development and maintenance is therefore crucial in developing treatment modalities. This review summarizes the major molecular signaling pathways involved in inner BRB (iBRB) formation and maintenance, and representative animal models of eye diseases with retinal vascular leakage. Studies on Wnt/β-catenin signaling are highlighted, which is critical for retinal and brain vascular angiogenesis and barriergenesis. Moreover, multiple in vivo and in vitro methods for the detection and analysis of vascular leakage are described, along with their advantages and limitations. These pre-clinical animal models and methods for assessing iBRB provide valuable experimental tools in delineating the molecular mechanisms of retinal vascular diseases and evaluating therapeutic drugs.
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Affiliation(s)
| | | | | | | | | | - Jing Chen
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
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2
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Rai V, Moellmer R, Agrawal DK. Role of fibroblast plasticity and heterogeneity in modulating angiogenesis and healing in the diabetic foot ulcer. Mol Biol Rep 2023; 50:1913-1929. [PMID: 36528662 DOI: 10.1007/s11033-022-08107-4] [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: 08/15/2022] [Accepted: 11/09/2022] [Indexed: 12/23/2022]
Abstract
Chronic diabetic foot ulcers (DFUs) are an important clinical issue faced by clinicians despite the advanced treatment strategies consisting of wound debridement, off-loading, medication, wound dressings, and keeping the ulcer clean. Non-healing DFUs are associated with the risk of amputation, increased morbidity and mortality, and economic stress. Neo-angiogenesis and granulation tissue formation are necessary for physiological DFU healing and acute inflammation play a key role in healing. However, chronic inflammation in association with diabetic complications holds the ulcer in the inflammatory phase without progressing to the resolution phase contributing to non-healing. Fibroblasts acquiring myofibroblasts phenotype contribute to granulation tissue formation and angiogenesis. However, recent studies suggest the presence of five subtypes of fibroblast population and of changing density in non-healing DFUs. Further, the association of fibroblast plasticity and heterogeneity with wound healing suggests that the switch in fibroblast phenotype may affect wound healing. The fibroblast phenotype shift and altered function may be due to the presence of chronic inflammation or a diabetic wound microenvironment. This review focuses on the role of fibroblast plasticity and heterogeneity, the effect of hyperglycemia and inflammatory cytokines on fibroblasts, and the interaction of fibroblasts with other cells in diabetic wound microenvironment in the perspective of DFU healing. Next, we summarize secretory, angiogenic, and angiostatic phenotypes of fibroblast which have been discussed in other organ systems but not in relation to DFUs followed by the perspective on the role of their phenotypes in promoting angiogenesis in DFUs.
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Affiliation(s)
- Vikrant Rai
- Department of Translational Research, Western University of Health Sciences, 91766, Pomona, CA, USA.
| | - Rebecca Moellmer
- College of Podiatric Medicine, Western University of Health Sciences, 91766, Pomona, CA, USA
| | - Devendra K Agrawal
- Department of Translational Research, Western University of Health Sciences, 91766, Pomona, CA, USA
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3
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Yap J, Irei J, Lozano-Gerona J, Vanapruks S, Bishop T, Boisvert WA. Macrophages in cardiac remodelling after myocardial infarction. Nat Rev Cardiol 2023; 20:373-385. [PMID: 36627513 DOI: 10.1038/s41569-022-00823-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/25/2022] [Indexed: 01/12/2023]
Abstract
Myocardial infarction (MI), as a result of thrombosis or vascular occlusion, is the most prevalent cause of morbidity and mortality among all cardiovascular diseases. The devastating consequences of MI are compounded by the complexities of cellular functions involved in the initiation and resolution of early-onset inflammation and the longer-term effects related to scar formation. The resultant tissue damage can occur as early as 1 h after MI and activates inflammatory signalling pathways to elicit an immune response. Macrophages are one of the most active cell types during all stages after MI, including the cardioprotective, inflammatory and tissue repair phases. In this Review, we describe the phenotypes of cardiac macrophage involved in MI and their cardioprotective functions. A specific subset of macrophages called resident cardiac macrophages (RCMs) are derived from yolk sac progenitor cells and are maintained as a self-renewing population, although their numbers decrease with age. We explore sophisticated sequencing techniques that demonstrate the cardioprotective properties of this cardiac macrophage phenotype. Furthermore, we discuss the interactions between cardiac macrophages and other important cell types involved in the pathology and resolution of inflammation after MI. We summarize new and promising therapeutic approaches that target macrophage-mediated inflammation and the cardioprotective properties of RCMs after MI. Finally, we discuss future directions for the study of RCMs in MI and cardiovascular health in general.
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Affiliation(s)
- Jonathan Yap
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Jason Irei
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Javier Lozano-Gerona
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Selena Vanapruks
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - Tianmai Bishop
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA
| | - William A Boisvert
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI, USA.
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4
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Shosha E, Fouda AY, Lemtalsi T, Haigh S, Fulton D, Ibrahim A, Al-Shabrawey M, Caldwell RW, Caldwell RB. Endothelial arginase 2 mediates retinal ischemia/reperfusion injury by inducing mitochondrial dysfunction. Mol Metab 2021; 53:101273. [PMID: 34139341 PMCID: PMC8274341 DOI: 10.1016/j.molmet.2021.101273] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 06/05/2021] [Accepted: 06/11/2021] [Indexed: 12/19/2022] Open
Abstract
Objective Retinal ischemic disease is a major cause of vision loss. Current treatment options are limited to late-stage diseases, and the molecular mechanisms of the initial insult are not fully understood. We have previously shown that the deletion of the mitochondrial arginase isoform, arginase 2 (A2), limits neurovascular injury in models of ischemic retinopathy. Here, we investigated the involvement of A2-mediated alterations in mitochondrial dynamics and function in the pathology. Methods We used wild-type (WT), global A2 knockout (A2KO-) mice, cell-specific A2 knockout mice subjected to retinal ischemia/reperfusion (I/R), and bovine retinal endothelial cells (BRECs) subjected to an oxygen-glucose deprivation/reperfusion (OGD/R) insult. We used western blotting to measure levels of cell stress and death markers and the mitochondrial fragmentation protein, dynamin related protein 1 (Drp1). We also used live cell mitochondrial labeling and Seahorse XF analysis to evaluate mitochondrial fragmentation and function, respectively. Results We found that the global deletion of A2 limited the I/R-induced disruption of retinal layers, fundus abnormalities, and albumin extravasation. The specific deletion of A2 in endothelial cells was protective against I/R-induced neurodegeneration. The OGD/R insult in BRECs increased A2 expression and induced cell stress and cell death, along with decreased mitochondrial respiration, increased Drp1 expression, and mitochondrial fragmentation. The overexpression of A2 in BREC also decreased mitochondrial respiration, promoted increases in the expression of Drp1, mitochondrial fragmentation, and cell stress and resulted in decreased cell survival. In contrast, the overexpression of the cytosolic isoform, arginase 1 (A1), did not affect these parameters. Conclusions This study is the first to show that A2 in endothelial cells mediates retinal ischemic injury through a mechanism involving alterations in mitochondrial dynamics and function. Ischemic retinopathy is a common feature of blinding eye disease. Arginase 2 overexpression in endothelial cells induces mitochondrial dysfunction. Endothelial-specific arginase 2 deletion improves neuronal survival after ischemia. Endothelial cell arginase 2 plays a crucial role in ischemic retinal injury.
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Affiliation(s)
- Esraa Shosha
- Vascular Biology Center, Augusta University, Augusta, GA, USA; Department of Clinical Pharmacy, Faculty of Pharmacy, Cairo University, Cairo, Egypt; Vision Discovery Institute, Augusta University, Augusta, GA, USA; Charlie Norwood VA Medical Center, Augusta, GA, USA
| | - Abdelrahman Y Fouda
- Vascular Biology Center, Augusta University, Augusta, GA, USA; Department of Clinical Pharmacy, Faculty of Pharmacy, Cairo University, Cairo, Egypt; Vision Discovery Institute, Augusta University, Augusta, GA, USA; Charlie Norwood VA Medical Center, Augusta, GA, USA
| | - Tahira Lemtalsi
- Vascular Biology Center, Augusta University, Augusta, GA, USA; Vision Discovery Institute, Augusta University, Augusta, GA, USA; Charlie Norwood VA Medical Center, Augusta, GA, USA
| | - Stephen Haigh
- Vascular Biology Center, Augusta University, Augusta, GA, USA
| | - David Fulton
- Vascular Biology Center, Augusta University, Augusta, GA, USA
| | - Ahmed Ibrahim
- Vision Discovery Institute, Augusta University, Augusta, GA, USA; Wayne State University, Department of Ophthalmology, Visual, and Anatomical Sciences, Department of Pharmacology, Detroit, MI, USA; Department of Biochemistry, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Mohamed Al-Shabrawey
- Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Oral Biology, Dental College of Georgia, Augusta, GA, USA
| | - R William Caldwell
- Vision Discovery Institute, Augusta University, Augusta, GA, USA; Department of Pharmacology and Toxicology, Augusta University, Augusta, GA, USA
| | - Ruth B Caldwell
- Vascular Biology Center, Augusta University, Augusta, GA, USA; Vision Discovery Institute, Augusta University, Augusta, GA, USA; Charlie Norwood VA Medical Center, Augusta, GA, USA.
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5
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The innate immune system in diabetic retinopathy. Prog Retin Eye Res 2021; 84:100940. [PMID: 33429059 DOI: 10.1016/j.preteyeres.2021.100940] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/24/2020] [Accepted: 01/03/2021] [Indexed: 12/20/2022]
Abstract
The prevalence of diabetes has been rising steadily in the past half-century, along with the burden of its associated complications, including diabetic retinopathy (DR). DR is currently the most common cause of vision loss in working-age adults in the United States. Historically, DR has been diagnosed and classified clinically based on what is visible by fundoscopy; that is vasculature alterations. However, recent technological advances have confirmed pathology of the neuroretina prior to any detectable vascular changes. These, coupled with molecular studies, and the positive impact of anti-inflammatory therapeutics in DR patients have highlighted the central involvement of the innate immune system. Reminiscent of the systemic impact of diabetes, immune dysregulation has become increasingly identified as a key element of the pathophysiology of DR by interfering with normal homeostatic systems. This review uses the growing body of literature across various model systems to demonstrate the clear involvement of all three pillars of the immune system: immune-competent cells, mediators, and the complement system. It also demonstrates how the relative contribution of each of these requires more extensive analysis, including in human tissues over the continuum of disease progression. Finally, although this review demonstrates how the complex interactions of the immune system pose many more questions than answers, the intimately connected nature of the three pillars of the immune system may also point to possible new targets to reverse or even halt reverse retinopathy.
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6
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Role of Arginase 2 in Murine Retinopathy Associated with Western Diet-Induced Obesity. J Clin Med 2020; 9:jcm9020317. [PMID: 31979105 PMCID: PMC7073940 DOI: 10.3390/jcm9020317] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 01/08/2020] [Accepted: 01/18/2020] [Indexed: 12/19/2022] Open
Abstract
Western diet-induced obesity is linked to the development of metabolic dysfunctions, including type 2 diabetes and complications that include retinopathy, a leading cause of blindness. Aberrant activation of the inflammasome cascade leads to the progression of obesity-induced pathologies. Our lab showed the critical role of arginase 2 (A2), the mitochondrial isoform of this ureahydrolase, in obesity-induced metabolic dysfunction and inflammation. A2 deletion also has been shown to be protective against retinal inflammation in models of ischemic retinopathy and multiple sclerosis. We investigated the effect of A2 deletion on western diet-induced retinopathy. Wild-type mice fed a high-fat, high-sucrose western diet for 16 weeks exhibited elevated retinal expression of A2, markers of the inflammasome pathway, oxidative stress, and activation of microglia/macrophages. Western diet feeding induced exaggerated retinal light responses without affecting visual acuity or retinal morphology. These effects were reduced or absent in mice with global A2 deletion. Exposure of retinal endothelial cells to palmitate and high glucose, a mimic of the obese state, increased expression of A2 and inflammatory mediators and induced cell death. These effects, except for A2, were prevented by pretreatment with an arginase inhibitor. Collectively, our study demonstrated a substantial role of A2 in early manifestations of diabetic retinopathy.
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7
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Shosha E, Xu Z, Narayanan SP, Lemtalsi T, Fouda AY, Rojas M, Xing J, Fulton D, Caldwell RW, Caldwell RB. Mechanisms of Diabetes-Induced Endothelial Cell Senescence: Role of Arginase 1. Int J Mol Sci 2018; 19:ijms19041215. [PMID: 29673160 PMCID: PMC5979610 DOI: 10.3390/ijms19041215] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 04/13/2018] [Accepted: 04/14/2018] [Indexed: 12/17/2022] Open
Abstract
We have recently found that diabetes-induced premature senescence of retinal endothelial cells is accompanied by NOX2-NADPH oxidase-induced increases in the ureohydrolase enzyme arginase 1 (A1). Here, we used genetic strategies to determine the specific involvement of A1 in diabetes-induced endothelial cell senescence. We used A1 knockout mice and wild type mice that were rendered diabetic with streptozotocin and retinal endothelial cells (ECs) exposed to high glucose or transduced with adenovirus to overexpress A1 for these experiments. ABH [2(S)-Amino-6-boronohexanoic acid] was used to inhibit arginase activity. We used Western blotting, immunolabeling, quantitative PCR, and senescence associated β-galactosidase (SA β-Gal) activity to evaluate senescence. Analyses of retinal tissue extracts from diabetic mice showed significant increases in mRNA expression of the senescence-related proteins p16INK4a, p21, and p53 when compared with non-diabetic mice. SA β-Gal activity and p16INK4a immunoreactivity were also increased in retinal vessels from diabetic mice. A1 gene deletion or pharmacological inhibition protected against the induction of premature senescence. A1 overexpression or high glucose treatment increased SA β-Gal activity in cultured ECs. These results demonstrate that A1 is critically involved in diabetes-induced senescence of retinal ECs. Inhibition of arginase activity may therefore be an effective therapeutic strategy to alleviate diabetic retinopathy by preventing premature senescence.
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Affiliation(s)
- Esraa Shosha
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
- Charlie Norwood VA Medical Center, Augusta, GA 30904, USA.
| | - Zhimin Xu
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
- Charlie Norwood VA Medical Center, Augusta, GA 30904, USA.
| | - S Priya Narayanan
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
- Charlie Norwood VA Medical Center, Augusta, GA 30904, USA.
- Department of Occupational Therapy, College of Allied Health Sciences, Augusta University, Augusta, GA 30912, USA.
| | - Tahira Lemtalsi
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
- Charlie Norwood VA Medical Center, Augusta, GA 30904, USA.
| | - Abdelrahman Y Fouda
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
- Charlie Norwood VA Medical Center, Augusta, GA 30904, USA.
| | - Modesto Rojas
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
- Charlie Norwood VA Medical Center, Augusta, GA 30904, USA.
| | - Ji Xing
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
| | - David Fulton
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
| | - R William Caldwell
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
| | - Ruth B Caldwell
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA 30912, USA.
- Charlie Norwood VA Medical Center, Augusta, GA 30904, USA.
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8
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Rojas M, Lemtalsi T, Toque HA, Xu Z, Fulton D, Caldwell RW, Caldwell RB. NOX2-Induced Activation of Arginase and Diabetes-Induced Retinal Endothelial Cell Senescence. Antioxidants (Basel) 2017; 6:antiox6020043. [PMID: 28617308 PMCID: PMC5488023 DOI: 10.3390/antiox6020043] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 05/30/2017] [Accepted: 06/09/2017] [Indexed: 12/19/2022] Open
Abstract
Increases in reactive oxygen species (ROS) and decreases in nitric oxide (NO) have been linked to vascular dysfunction during diabetic retinopathy (DR). Diabetes can reduce NO by increasing ROS and by increasing activity of arginase, which competes with nitric oxide synthase (NOS) for their commons substrate l-arginine. Increased ROS and decreased NO can cause premature endothelial cell (EC) senescence leading to defective vascular repair. We have previously demonstrated the involvement of NADPH oxidase 2 (NOX2)-derived ROS, decreased NO and overactive arginase in DR. Here, we investigated their impact on diabetes-induced EC senescence. Studies using diabetic mice and retinal ECs treated with high glucose or H2O2 showed that increases in ROS formation, elevated arginase expression and activity, and decreased NO formation led to premature EC senescence. NOX2 blockade or arginase inhibition prevented these effects. EC senescence was also increased by inhibition of NOS activity and this was prevented by treatment with a NO donor. These results indicate that diabetes/high glucose-induced activation of arginase and decreases in NO bioavailability accelerate EC senescence. NOX2-generated ROS contribute importantly to this process. Blockade of NOX2 or arginase represents a strategy to prevent diabetes-induced premature EC senescence by preserving NO bioavailability.
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Affiliation(s)
- Modesto Rojas
- Vascular Biology Center, Augusta University, 1459 Laney Walker Boulevard, Augusta, GA 30912-2500, USA.
- VA Medical Center, One Freedom Way, Augusta, GA 30904-6285, USA.
| | - Tahira Lemtalsi
- Vascular Biology Center, Augusta University, 1459 Laney Walker Boulevard, Augusta, GA 30912-2500, USA.
- VA Medical Center, One Freedom Way, Augusta, GA 30904-6285, USA.
| | - Haroldo A Toque
- Department of Pharmacology & Toxicology, Augusta University, 1459 Laney Walker, Boulevard, Augusta, GA 30912-2500, USA.
| | - Zhimin Xu
- Vascular Biology Center, Augusta University, 1459 Laney Walker Boulevard, Augusta, GA 30912-2500, USA.
- VA Medical Center, One Freedom Way, Augusta, GA 30904-6285, USA.
| | - David Fulton
- Vascular Biology Center, Augusta University, 1459 Laney Walker Boulevard, Augusta, GA 30912-2500, USA.
- Department of Pharmacology & Toxicology, Augusta University, 1459 Laney Walker, Boulevard, Augusta, GA 30912-2500, USA.
| | - Robert William Caldwell
- Department of Pharmacology & Toxicology, Augusta University, 1459 Laney Walker, Boulevard, Augusta, GA 30912-2500, USA.
| | - Ruth B Caldwell
- Vascular Biology Center, Augusta University, 1459 Laney Walker Boulevard, Augusta, GA 30912-2500, USA.
- VA Medical Center, One Freedom Way, Augusta, GA 30904-6285, USA.
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Tappeiner C, Maurer E, Sallin P, Bise T, Enzmann V, Tschopp M. Inhibition of the TGFβ Pathway Enhances Retinal Regeneration in Adult Zebrafish. PLoS One 2016; 11:e0167073. [PMID: 27880821 PMCID: PMC5120850 DOI: 10.1371/journal.pone.0167073] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/08/2016] [Indexed: 12/21/2022] Open
Abstract
In contrast to the mammalian retina, the zebrafish retina exhibits the potential for lifelong retinal neurogenesis and regeneration even after severe damage. Previous studies have shown that the transforming growth factor beta (TGFβ) signaling pathway is activated during the regeneration of different tissues in the zebrafish and is needed for regeneration in the heart and the fin. In this study, we have investigated the role of the TGFβ pathway in the N-methyl-N-nitrosourea (MNU)-induced chemical model of rod photoreceptor de- and regeneration in adult zebrafish. Immunohistochemical staining for phosphorylated Smad3 was elevated during retinal regeneration, and phosphorylated Smad3 co-localized with proliferating cell nuclear antigen and glutamine synthetase, indicating TGFβ pathway activation in proliferating Müller glia. Inhibiting the TGFβ signaling pathway using a small molecule inhibitor (SB431542) resulted in accelerated recovery from retinal degeneration. Accordingly, we observed increased cell proliferation in the outer nuclear layer at days 3 to 8 after MNU treatment. In contrast to the observations in the heart and the fin, the inhibition of the TGFβ signaling pathway resulted in increased proliferation after the induction of retinal degeneration. A better understanding of the underlying pathways with the possibility to boost retinal regeneration in adult zebrafish may potentially help to stimulate such proliferation also in other species.
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Affiliation(s)
- Christoph Tappeiner
- Department of Ophthalmology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - Ellinor Maurer
- Department of Ophthalmology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - Pauline Sallin
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Thomas Bise
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Volker Enzmann
- Department of Ophthalmology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - Markus Tschopp
- Department of Ophthalmology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
- Department of Ophthalmology, University Hospital of Basel, Basel, Switzerland
- * E-mail:
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10
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High glucose alters retinal astrocytes phenotype through increased production of inflammatory cytokines and oxidative stress. PLoS One 2014; 9:e103148. [PMID: 25068294 PMCID: PMC4113377 DOI: 10.1371/journal.pone.0103148] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 06/26/2014] [Indexed: 01/05/2023] Open
Abstract
Astrocytes are macroglial cells that have a crucial role in development of the retinal vasculature and maintenance of the blood-retina-barrier (BRB). Diabetes affects the physiology and function of retinal vascular cells including astrocytes (AC) leading to breakdown of BRB. However, the detailed cellular mechanisms leading to retinal AC dysfunction under high glucose conditions remain unclear. Here we show that high glucose conditions did not induce the apoptosis of retinal AC, but instead increased their rate of DNA synthesis and adhesion to extracellular matrix proteins. These alterations were associated with changes in intracellular signaling pathways involved in cell survival, migration and proliferation. High glucose conditions also affected the expression of inflammatory cytokines in retinal AC, activated NF-κB, and prevented their network formation on Matrigel. In addition, we showed that the attenuation of retinal AC migration under high glucose conditions, and capillary morphogenesis of retinal endothelial cells on Matrigel, was mediated through increased oxidative stress. Antioxidant proteins including heme oxygenase-1 and peroxiredoxin-2 levels were also increased in retinal AC under high glucose conditions through nuclear localization of transcription factor nuclear factor-erythroid 2-related factor-2. Together our results demonstrated that high glucose conditions alter the function of retinal AC by increased production of inflammatory cytokines and oxidative stress with significant impact on their proliferation, adhesion, and migration.
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11
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Yafai Y, Iandiev I, Lange J, Unterlauft JD, Wiedemann P, Bringmann A, Reichenbach A, Eichler W. Müller glial cells inhibit proliferation of retinal endothelial cells via TGF-β2 and Smad signaling. Glia 2014; 62:1476-85. [DOI: 10.1002/glia.22694] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 04/30/2014] [Accepted: 05/02/2014] [Indexed: 12/20/2022]
Affiliation(s)
- Yousef Yafai
- Department of Ophthalmology and Eye Hospital; University of Leipzig; Leipzig Germany
| | - Ianors Iandiev
- Department of Ophthalmology and Eye Hospital; University of Leipzig; Leipzig Germany
| | - Johannes Lange
- Norwegian Centre for Movement Disorders; Stavanger University Hospital; Stavanger Norway
| | - Jan Darius Unterlauft
- Department of Ophthalmology and Eye Hospital; University of Leipzig; Leipzig Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital; University of Leipzig; Leipzig Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital; University of Leipzig; Leipzig Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig; Leipzig Germany
| | - Wolfram Eichler
- Department of Ophthalmology and Eye Hospital; University of Leipzig; Leipzig Germany
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12
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Inflammatory mechanisms of idiopathic epiretinal membrane formation. Mediators Inflamm 2013; 2013:192582. [PMID: 24324293 PMCID: PMC3844245 DOI: 10.1155/2013/192582] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 10/11/2013] [Indexed: 02/01/2023] Open
Abstract
The pathogenesis of idiopathic epiretinal membranes (iERMs), a common pathology found in retina clinics, still eludes researchers to date. Ultrastructural studies of iERMs in the past have failed to identify the cells of origin due to the striking morphologic changes of cells involved via transdifferentiation. Thus, immunohistochemical techniques that stain for the cytostructural components of cells have confirmed the importance of glial cells and hyalocytes in iERM formation. The cellular constituents of iERMs are thought to consist of glial cells, fibroblasts, hyalocytes, etc. that, in concert with cytokines and growth factors present in the vitreous, lead to iERM formation. Recently, research has focused on the role of the posterior hyaloid in iERM formation and contraction, particularly the process of anomalous PVD as it relates to iERM formation. Recent advances in proteomics techniques have also elucidated the growth factors and cytokines involved in iERM formation, most notably nerve growth factor, glial cell line-derived growth factor, and transforming growth factor β1.
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13
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Basic fibroblast growth factor contributes to a shift in the angioregulatory activity of retinal glial (Müller) cells. PLoS One 2013; 8:e68773. [PMID: 23861940 PMCID: PMC3701643 DOI: 10.1371/journal.pone.0068773] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Accepted: 06/05/2013] [Indexed: 01/13/2023] Open
Abstract
Basic fibroblast growth factor (bFGF) is a pleiotropic cytokine with pro-angiogenic and neurotrophic effects. The angioregulatory role of this molecule may become especially significant in retinal neovascularization, which is a hallmark of a number of ischemic eye diseases. This study was undertaken to reveal expression characteristics of bFGF, produced by retinal glial (Müller) cells, and to determine conditions under which glial bFGF may stimulate the proliferation of retinal microvascular endothelial cells. Immunofluorescence labeling detected bFGF in Müller cells of the rat retina and in acutely isolated Müller cells with bFGF levels, which increased after ischemia-reperfusion in postischemic retinas. In patients with proliferative diabetic retinopathy or myopia, the immunoreactivity of bFGF co-localized to glial fibrillary acidic protein (GFAP)-positive cells in surgically excised retinal tissues. RT-PCR and ELISA analyses indicated that cultured Müller cells produce bFGF, which is elevated under hypoxia or oxidative stress, as well as under stimulation with various growth factors and cytokines, including pro-inflammatory factors. When retinal endothelial cells were cultured in the presence of media from hypoxia (0.2%)-conditioned Müller cells, a distinct picture of endothelial cell proliferation emerged. Media from 24-h cultured Müller cells inhibited proliferation, whereas 72-h conditioned media elicited a stimulatory effect. BFGF-neutralizing antibodies suppressed the enhanced endothelial cell proliferation to a similar extent as anti-VEGF antibodies. Furthermore, phosphorylation of extracellular signal-regulated kinases (ERK−1/−2) in retinal endothelial cells was increased when the cells were cultured in 72-h conditioned media, while neutralizing bFGF attenuated the activation of this signaling pathway. These data provide evidence that retinal (glial) Müller cells are major sources of bFGF in the ischemic retina. Müller cells under physiological conditions or transient hypoxia seem to provide an anti-angiogenic environment, but long-lasting hypoxia causes the release of bFGF, which might significantly co-stimulate neovascularization in the retina.
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Reichenbach A, Bringmann A. New functions of Müller cells. Glia 2013; 61:651-78. [PMID: 23440929 DOI: 10.1002/glia.22477] [Citation(s) in RCA: 450] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 01/10/2012] [Indexed: 12/12/2022]
Abstract
Müller cells, the major type of glial cells in the retina, are responsible for the homeostatic and metabolic support of retinal neurons. By mediating transcellular ion, water, and bicarbonate transport, Müller cells control the composition of the extracellular space fluid. Müller cells provide trophic and anti-oxidative support of photoreceptors and neurons and regulate the tightness of the blood-retinal barrier. By the uptake of glutamate, Müller cells are more directly involved in the regulation of the synaptic activity in the inner retina. This review gives a survey of recently discoved new functions of Müller cells. Müller cells are living optical fibers that guide light through the inner retinal tissue. Thereby they enhance the signal/noise ratio by minimizing intraretinal light scattering and conserve the spatial distribution of light patterns in the propagating image. Müller cells act as soft, compliant embedding for neurons, protecting them in case of mechanical trauma, and also as soft substrate required for neurite growth and neuronal plasticity. Müller cells release neuroactive signaling molecules which modulate neuronal activity, are implicated in the mediation of neurovascular coupling, and mediate the homeostasis of the extracellular space volume under hypoosmotic conditions which are a characteristic of intense neuronal activity. Under pathological conditions, a subset of Müller cells may differentiate to neural progenitor/stem cells which regenerate lost photoreceptors and neurons. Increasing knowledge of Müller cell function and responses in the normal and diseased retina will have great impact for the development of new therapeutic approaches for retinal diseases.
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Affiliation(s)
- Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany.
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15
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Blockade of VEGF-induced GSK/β-catenin signaling, uPAR expression and increased permeability by dominant negative p38α. Exp Eye Res 2012; 100:101-8. [PMID: 22564969 DOI: 10.1016/j.exer.2012.03.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 02/11/2012] [Accepted: 03/21/2012] [Indexed: 11/23/2022]
Abstract
The goal of this study was to define the role of p38alpha MAP kinase in VEGF-induced vascular permeability increase. Activation of p38 is correlated with increased permeability in endothelial cells treated with VEGF or high glucose and in retinas of diabetic animal models. We have shown previously that p38 inhibitors preserve endothelial barrier function and block VEGF-induced GSK/beta-catenin signaling. Here, we present data demonstrating that adenoviral vector delivery of a dominant negative p38alpha mutant blocks this signaling pathway and preserves barrier function. This p38alpha mutant was altered on its ATP-binding site, which eliminates its kinase activity. Bovine retinal endothelial (BRE) cells were transduced with recombinant adenovirus containing the p38alpha mutants or empty vector. Successful transduction was confirmed by expression of GFP and p38 increase. Blockade of p38 activity by p38alpha mutant was demonstrated by inhibition of VEGF-induced phosphorylation of a p38 target, MAP kinase activated protein kinase 2 (MK-2). The mutant also prevented VEGF-induced GSK phosphorylation and beta-catenin cytosolic accumulation and nuclear translocation as shown by cell fractionation and Western blotting. Quantitative real-time PCR demonstrated that this mutant inhibited VEGF-induced uPAR gene expression. Importantly, this same mutant also strongly abrogated VEGF-induced endothelial barrier breakdown as determined by measuring transcellular electrical resistance and tracer flux through endothelial cell monolayer. This study indicates a critical role of p38alpha in VEGF-induced permeability and offers a new strategy for developing potent and specific therapies for treatment of retinal diseases associated with vascular barrier dysfunction.
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16
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Beck K, Schachtrup C. Vascular damage in the central nervous system: a multifaceted role for vascular-derived TGF-β. Cell Tissue Res 2011; 347:187-201. [PMID: 21850492 DOI: 10.1007/s00441-011-1228-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 07/22/2011] [Indexed: 01/16/2023]
Abstract
The brain function depends on a continuous supply of blood. The blood-brain barrier (BBB), which is formed by vascular cells and glia, separates components of the circulating blood from neurons and maintains the precisely regulated brain milieu required for proper neuronal function. A compromised BBB alters the transport of molecules between the blood and brain and has been associated with or shown to precede neurodegenerative disease. Blood components immediately leak into the brain after mechanical damage or as a consequence of a compromised BBB in brain disease changing the extracellular environment at sites of vascular damage. It is intriguing how blood-derived components alter the cellular and molecular constituents of the neurovascular interface after BBB opening. We recently identified an unexpected role for the blood protein fibrinogen, which is deposited in the nervous system promptly after vascular damage, as an initial scar inducer by promoting the availability of active TGF-β. Fibrinogen-bound latent TGF-β interacts with astrocytes, leading to active TGF-β formation and activation of the TGF-β/Smad signaling pathway. Here, we discuss the pleiotropic effects of potentially vascular-derived TGF-β on cells at the neurovascular interface and we speculate how these biological effects might contribute to degeneration and regeneration processes. Summarizing the effects of the components derived from the brain vascular system on nervous system regeneration might support the development of new therapeutic approaches.
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Affiliation(s)
- Kristina Beck
- Centre of Chronic Immunodeficiency, University Medical Centre Freiburg and University of Freiburg, 79106 Freiburg, Germany
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17
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Yang J, Duh EJ, Caldwell RB, Behzadian MA. Antipermeability function of PEDF involves blockade of the MAP kinase/GSK/beta-catenin signaling pathway and uPAR expression. Invest Ophthalmol Vis Sci 2010; 51:3273-80. [PMID: 20089873 DOI: 10.1167/iovs.08-2878] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Pigment epithelium-derived factor (PEDF) is a potent inhibitor of vascular endothelial growth factor (VEGF)-induced endothelial permeability. The goal of this study was to understand the mechanism by which PEDF blocks VEGF-induced increases in vascular permeability. METHODS The paracellular permeability of bovine retinal endothelial (BRE) cells was measured by assaying transendothelial cell electrical resistance and tracer flux. Western blot analysis was used to show phosphorylation of VEGFR2, MAP kinases, and glycogen synthase kinase 3 (GSK3)-beta. Confocal imaging and Western blot analysis were used to determine subcellular distribution of beta-catenin. Real-time RT-PCR and Western blot analysis were used to quantify urokinase plasminogen activator receptor (uPAR) expression. RESULTS PEDF blocked VEGF-induced phosphorylation of extracellular signal-regulated kinase (ERK), p38 MAP kinase, the p38 substrate MAP kinase-activated protein kinase-2 (MAPKAPK-2), and GSK3-beta, but it had no effect on the phosphorylation of VEGFR2. In addition, the VEGF-induced transcriptional activation of beta-catenin and uPAR expression were blocked by PEDF and by inhibitors of p38 and MEK. Finally, the VEGF-induced increase in permeability was blocked by both PEDF and the same kinase inhibitors. CONCLUSIONS The data suggest that p38 MAP kinase and ERK act upstream of GSK/beta-catenin in VEGF-induced activation of the uPA/uPAR system and that PEDF-mediated inhibition of the VEGF-induced increase in vascular permeability involves blockade of this pathway. These findings are important for developing precise and potent therapies for treatment of diseases characterized by vascular barrier dysfunction.
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Bringmann A, Iandiev I, Pannicke T, Wurm A, Hollborn M, Wiedemann P, Osborne NN, Reichenbach A. Cellular signaling and factors involved in Müller cell gliosis: neuroprotective and detrimental effects. Prog Retin Eye Res 2009; 28:423-51. [PMID: 19660572 DOI: 10.1016/j.preteyeres.2009.07.001] [Citation(s) in RCA: 486] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Müller cells are active players in normal retinal function and in virtually all forms of retinal injury and disease. Reactive Müller cells protect the tissue from further damage and preserve tissue function by the release of antioxidants and neurotrophic factors, and may contribute to retinal regeneration by the generation of neural progenitor/stem cells. However, Müller cell gliosis can also contribute to neurodegeneration and impedes regenerative processes in the retinal tissue by the formation of glial scars. This article provides an overview of the neuroprotective and detrimental effects of Müller cell gliosis, with accounts on the cellular signal transduction mechanisms and factors which are implicated in Müller cell-mediated neuroprotection, immunomodulation, regulation of Müller cell proliferation, upregulation of intermediate filaments, glial scar formation, and the generation of neural progenitor/stem cells. A proper understanding of the signaling mechanisms implicated in gliotic alterations of Müller cells is essential for the development of efficient therapeutic strategies that increase the supportive/protective and decrease the destructive roles of gliosis.
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Affiliation(s)
- Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Liebigstrasse 10-14, D-04103 Leipzig, Germany.
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Bringmann A, Wiedemann P. Involvement of Müller glial cells in epiretinal membrane formation. Graefes Arch Clin Exp Ophthalmol 2009; 247:865-83. [PMID: 19415318 DOI: 10.1007/s00417-009-1082-x] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 02/10/2009] [Accepted: 04/06/2009] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Proliferative retinopathies are considered to represent maladapted retinal wound repair processes driven by growth factor- and cytokine-induced overstimulation of proliferation, migration, extracellular matrix production and contraction of retinal cells. The formation of neovascular membranes represents an attempt to reoxygenize non-perfused retinal areas. Müller glial cells play a crucial role in the pathogenesis of proliferative retinopathies. This review summarizes the present knowledge regarding the role of Müller cells in periretinal membrane formation, especially in the early steps of epiretinal membrane formation, which involve an interaction of inflammatory and glial cells, and gives a survey of the factors which are suggested to be implicated in the induction of Müller cell gliosis and proliferation. CONCLUSIONS Alterations in the membrane conductance of Müller cells suggest that Müller cells may alter their phenotype into progenitor-like cells in the course of proliferative retinopathies; transdifferentiated Müller cells may have great impact for the development of new cell-based therapies.
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Affiliation(s)
- Andreas Bringmann
- Department of Ophthalmology, Faculty of Medicine, University of Leipzig, Eye Hospital, Leipzig, Germany.
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20
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Al-Shabrawey M, Bartoli M, El-Remessy AB, Ma G, Matragoon S, Lemtalsi T, Caldwell RW, Caldwell RB. Role of NADPH oxidase and Stat3 in statin-mediated protection against diabetic retinopathy. Invest Ophthalmol Vis Sci 2008; 49:3231-8. [PMID: 18378570 PMCID: PMC2819293 DOI: 10.1167/iovs.08-1754] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
PURPOSE Inhibitors of 3-hydroxy-3-methylglutaryl CoA reductase (statins) reduce signs of diabetic retinopathy in diabetic patients and animals. Indirect clinical evidence supports the actions of statins in improving cardiovascular function, but the mechanisms of their protective actions in the retina are not understood. Prior studies have implicated oxidative stress and NADPH oxidase-mediated activation of signal transducer and activator of transcription 3 (STAT3) in diabetes-induced increases in expression of vascular endothelial growth factor (VEGF) and intercellular adhesion molecule (ICAM)-1 and breakdown of the blood-retinal barrier (BRB). Because statins are known to be potent antioxidants, the hypothesis for the current study was that the protective effects of statins in preventing diabetic retinopathy involve blockade of diabetes-induced activation of NADPH oxidase and STAT3. METHODS The hypothesis was tested by experiments in which rats with streptozotocin (STZ)-induced diabetes and retinal endothelial cells maintained in high-glucose medium were treated with simvastatin. Blood-retinal barrier (BRB) function was assayed by determining extravasation of albumin. Oxidative stress was assayed by measuring lipid peroxidation, protein nitration of tyrosine, dihydroethidine oxidation, and chemiluminescence. Immunoprobe techniques were used to determine the levels of NADPH oxidase subunit expression and STAT3 activation. RESULTS These studies showed that simvastatin blocks diabetes or high-glucose-induced increases in VEGF and ICAM-1 and preserves the BRB by a process involving blockade of diabetes/high-glucose-induced activation of STAT3 and NADPH oxidase. Statin treatment also prevents diabetes-induced increases in expression of the NADPH oxidase catalytic and subunit NOX2. CONCLUSIONS These results suggest that simvastatin protects against the early signs of diabetic retinopathy by preventing NADPH oxidase-mediated activation of STAT3.
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Affiliation(s)
| | - Manuela Bartoli
- Vascular Biology Center, Medical College of Georgia, Augusta, Georgia
| | - Azza B. El-Remessy
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, Georgia
| | - Guochuan Ma
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, Georgia
| | - Suraporn Matragoon
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, Georgia
| | - Tahira Lemtalsi
- Vascular Biology Center, Medical College of Georgia, Augusta, Georgia
| | - R. William Caldwell
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, Georgia
| | - Ruth B. Caldwell
- Vascular Biology Center, Medical College of Georgia, Augusta, Georgia
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Siddharthan V, V. Kim Y, Liu S, Kim KS. Human astrocytes/astrocyte-conditioned medium and shear stress enhance the barrier properties of human brain microvascular endothelial cells. Brain Res 2007; 1147:39-50. [PMID: 17368578 PMCID: PMC2691862 DOI: 10.1016/j.brainres.2007.02.029] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Revised: 01/12/2007] [Accepted: 02/02/2007] [Indexed: 11/20/2022]
Abstract
The blood-brain barrier (BBB) is a structural and functional barrier that regulates the passage of molecules into and out of the brain to maintain the neural microenvironment. We have previously developed the in vitro BBB model with human brain microvascular endothelial cells (HBMEC). However, in vivo HBMEC are shown to interact with astrocytes and also exposed to shear stress through blood flow. In an attempt to develop the BBB model to mimic the in vivo condition we constructed the flow-based in vitro BBB model using HBMEC and human fetal astrocytes (HFA). We also examined the effect of astrocyte-conditioned medium (ACM) in lieu of HFA to study the role of secreted factor(s) on the BBB properties. The tightness of HBMEC monolayer was assessed by the permeability of dextran and propidium iodide as well as by measuring the transendothelial electrical resistance (TEER). We showed that the HBMEC permeability was reduced and TEER was increased by non-contact, co-cultivation with HFA and ACM. The exposure of HBMEC to shear stress also exhibited decreased permeability. Moreover, HFA/ACM and shear flow exhibited additive effect of decreasing the permeability of HBMEC monolayer. In addition, we showed that the HBMEC expression of ZO-1 (tight junction protein) was increased by co-cultivation with ACM and in response to shear stress. These findings suggest that the non-contact co-cultivation with HFA helps maintain the barrier properties of HBMEC by secreting factor(s) into the medium. Our in vitro flow model system with the cells of human origin should be useful for studying the interactions between endothelial cells, glial cells, and secreted factor(s) as well as the role of shear stress in the barrier property of HBMEC.
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Affiliation(s)
- Venkatraman Siddharthan
- Division of Pediatric Infectious Diseases, Johns Hopkins University, School of Medicine, Baltimore, MD 21287
| | - Yuri V. Kim
- Division of Pediatric Infectious Diseases, Johns Hopkins University, School of Medicine, Baltimore, MD 21287
| | - Suyi Liu
- World Precision Instruments Inc., 175 Sarasota Center Blvd, Sarasota FL 34240 U.S.A
| | - Kwang Sik Kim
- Correspondence: Prof. Kwang Sik Kim, Division of Pediatric Infectious Diseases, Johns Hopkins University, School of Medicine, 600 North Wolfe Street, Park 256, Baltimore, MD 21287. , Phone: 410-614-3917, Fax: 410-614-1491
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22
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Tsanou E, Ioachim E, Stefaniotou M, Gorezis S, Charalabopoulos K, Bagli H, Peschos D, Psilas K, Agnantis NJ. Immunohistochemical study of angiogenesis and proliferative activity in epiretinal membranes. Int J Clin Pract 2005; 59:1157-61. [PMID: 16178982 DOI: 10.1111/j.1368-5031.2005.00573.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Formation of epiretinal membranes (ERMs) is a serious complication of retinal diseases, the most important being proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). In this study, our goal was to (i) calculate the microvessel density (MVD), (ii) evaluate vascular endothelial growth factor (VEGF) expression and (iii) correlate angiogenesis with the proliferative activity as expressed by the expression of Ki67 marker, in both membrane types. We performed immunohistochemistry in 14 PVR and eight PDR membranes, using antibodies against CD34, VEGF, Ki67 and glial fibrillary acidic protein. PDR membranes presented higher average count of microvessels compared with PVR membranes (p = 0.0015). No differences were observed concerning VEGF expression (p = 0.1). The expression of Ki67 was not correlated with microvessel number or VEGF expression. Our study confirms the presence of vascularisation in PDR membranes, as well as the presence of VEGF even in avascular PVR membranes, suggesting that immunoreactivity for VEGF may not be accompanied by angiogenesis.
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Affiliation(s)
- E Tsanou
- Department of Pathology-Cytology, Medical School, University of Ioannina, Ioannina, Greece
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23
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Behzadian MA, Windsor LJ, Ghaly N, Liou G, Tsai NT, Caldwell RB. VEGF-induced paracellular permeability in cultured endothelial cells involves urokinase and its receptor. FASEB J 2003; 17:752-4. [PMID: 12594181 DOI: 10.1096/fj.02-0484fje] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Vascular endothelial growth factor/vascular permeability factor (VEGF) has been implicated in blood/tissue barrier dysfunctions associated with pathological angiogenesis, but the mechanisms of VEGF-induced permeability increase are poorly understood. Here, the role of VEGF-induced extracellular proteolytic activities on the endothelial cell permeability increase is evaluated. Confluent monolayers of bovine retinal microvascular endothelial (BRE) cells grown on porous membrane were treated with VEGF or urokinase plasminogen activator (uPA), and permeability changes were analyzed. uPA-induced permeability was rapid and sustained, but VEGF-induced permeability showed a biphasic pattern: a rapid and transient phase (1-2 h) followed by delayed and sustained phase (6-24 h). The delayed, but not the early phase of VEGF-induced permeability, was blocked by anti-uPA or anti-uPAR (uPA receptor) antibodies and was accompanied by reduced transendothelial electrical resistance, indicating the paracellular route of permeability. Confocal microscopy and Western blotting showed that VEGF treatment increased free cytosolic beta-catenin, which was followed by beta-catenin nuclear translocation, upregulation of uPAR, and downregulation of occludin. Membrane-bound occludin was released immediately after uPA treatment, but with a long delay after VEGF treatment, suggesting a requirement for uPAR gene expression. In conclusion, VEGF induces a sustained paracellular permeability in capillary endothelial cells that is mediated by activation of the uPA/uPAR system.
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MESH Headings
- Animals
- Cattle
- Cell Membrane Permeability/drug effects
- Cells, Cultured
- Cytoskeletal Proteins/pharmacokinetics
- Endothelial Growth Factors/pharmacology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Gene Expression Regulation/drug effects
- Intercellular Signaling Peptides and Proteins/pharmacology
- Lymphokines/pharmacology
- Membrane Proteins/pharmacokinetics
- Microscopy, Confocal
- Occludin
- RNA, Messenger/drug effects
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Receptors, Urokinase Plasminogen Activator
- Trans-Activators/pharmacokinetics
- Urokinase-Type Plasminogen Activator/metabolism
- Vascular Endothelial Growth Factor A
- Vascular Endothelial Growth Factors
- beta Catenin
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Affiliation(s)
- M Ali Behzadian
- Vascular Biology Center, Department of Pharmacology & Toxicology, Medical College of Georgia, 1120 15th Street, Augusta, Georgia 30912, USA.
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Song HS, Son MJ, Lee YM, Kim WJ, Lee SW, Kim CW, Kim KW. Oxygen tension regulates the maturation of the blood-brain barrier. Biochem Biophys Res Commun 2002; 290:325-31. [PMID: 11779173 DOI: 10.1006/bbrc.2001.6205] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The oxygen tension during the development of vascular systems influences vascular vessel formation through regulating angiogenesis. We studied the effect of hypoxia/reoxygenation (H/R) to explain its role in concert with astrocytes involvement in the development of the blood-brain barrier (BBB). On the basis of the fact that the disappearance of hypoxic regions and the decreased expression of vascular endothelial growth factor (VEGF) were observed by immunohistochemistry in a development-dependent manner in rat cerebral cortex, we examined the effects of astrocytes on the BBB-like properties of ECV304 cells by exposing astrocytes to H/R. Conditioned medium of reoxygenated astrocytes inhibited [(3)H]thymidine incorporation and tube formation of ECV 304 cells. When astrocytes were exposed to reoxygenation, the expression of VEGF was reduced, whereas the expression of angiopoietin-1 and thrombospondin-1 was enhanced. Moreover, [(3)H]sucrose permeability assay revealed that astrocytes enhance the barrier function of ECV 304 cells in coculture model within 5 h of reoxygenation. Correspondingly, the occludin expression of ECV 304 cells was slightly increased by the conditioned medium of reoxygenated astrocytes. In conclusion, our study suggests that reoxygenation of astrocytes may act as a significant driving force for the maturation of the BBB during brain development through oxygen-regulated gene(s).
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Affiliation(s)
- Hyun Seok Song
- Department of Molecular Biology, Pusan National University, Pusan, Korea
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25
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Abstract
Astroglia are interposed between the cerebral vasculature and neurons, where they may mediate the transfer of substances from the circulation to neurons and couple changes in neuronal activity to changes in cerebral blood flow. The retina is a particularly advantageous model system for studying glial-vascular interactions in situ. Confocal microscopy and three-dimensional image reconstruction were used to study the anatomical relationships between glia and the surface vasculature in retinas acutely isolated from adult pigmented rats. Retinas were immunostained using antibodies directed against the basal lamina surrounding the vasculature as well as antibodies directed against glial fibrillary acidic protein. Surface vessels of all calibers were contacted by the processes of astrocytes. The vitreal surfaces of the large retinal vessels were covered by a meshwork of immunoreactive astrocyte processes of a variety of shapes, whereas the scleral surfaces of the vessels were supported by thick bundles of astrocyte processes. In addition, glial cells were filled intracellularly with the gap junction-permeable tracers Lucifer yellow and Neurobiotin. Intracellular fills clearly demonstrated the presence of astrocytes with somata that were closely apposed to the large retinal vessels. Tracer-filled astrocytes displayed a variety and complexity of shapes that was not apparent in immunostained material. Gap junctional coupling was stronger between astrocytes adjacent to the same artery than between periarterial astrocytes and astrocytes located away from arteries. Significantly fewer Müller cells were labeled when Neurobiotin was injected into astrocytes associated with arteries than when Neurobiotin was injected into astrocytes that were distant from arteries.
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Affiliation(s)
- K R Zahs
- Department of Physiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
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26
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Kaesemeyer WH, Ogonowski AA, Jin L, Caldwell RB, Caldwell RW. Endothelial nitric oxide synthase is a site of superoxide synthesis in endothelial cells treated with glyceryl trinitrate. Br J Pharmacol 2000; 131:1019-23. [PMID: 11053225 PMCID: PMC1572421 DOI: 10.1038/sj.bjp.0703665] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Tolerance to glyceryl trinitrate (GTN) involves superoxide (O(2)(*-)) production by endothelial cells. Nitric oxide synthase (NOS) produces O(2)(*-) when L-arginine (L-arg) is limited. The purpose of this study was to test the hypothesis that GTN stimulates NOS to increase O(2)(*-) synthesis in endothelial cells when L-arg is limited. Production of O(2)(*-) by bovine aortic endothelial cells (BAEC, passages 3 - 5) was determined by spectrophotometrically measuring superoxide dismutase-inhibited reduction of ferricytochrome C to ferrocytochrome C. Cells were incubated in buffer without L-arg. O(2)(*-) production was measured using BAEC either untreated or treated with L-NAME or L-arg alone or following treatment with GTN (10(-9) to 10(-6) M) for 30 min or DPTA NONOate (10(-7) and 10(-6) M) alone or with GTN or DPTA NONOate after pretreatment with nitro-L-arginine methyl ester (L-NAME), L-arg or their inactive enantiomers, D-NAME or D-arg (all 5 x 10(-4) M) (n=6 - 7/group). L-NAME alone produced a 69% reduction in O(2)(*-) levels. Treatment with L-arg alone had no effect. Cells treated with GTN alone exhibited an increase in O(2)(*-). This effect was prevented by pretreatment with either L-NAME or L-arg, and was unaffected by D-NAME or D-arg. We observed a dose-response relationship in O(2)(*-) production to GTN over a range of 10(-9) to 10(-7) M. The NO donor, DPTA-NONOate, unlike GTN, did not have a significant effect on O(2)(*-) production. In conclusion, endothelial NOS is a site of O(2)(*-) synthesis in endothelial cells activated by GTN.
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Affiliation(s)
- W H Kaesemeyer
- Department of Pharmacology and Toxicology, Medical College of Georgia, Laney-Walker Boulevard, Augusta, Georgia, GA 30912, USA
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27
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Bartoli M, Gu X, Tsai NT, Venema RC, Brooks SE, Marrero MB, Caldwell RB. Vascular endothelial growth factor activates STAT proteins in aortic endothelial cells. J Biol Chem 2000; 275:33189-92. [PMID: 10961983 DOI: 10.1074/jbc.c000318200] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vascular endothelial growth factor (VEGF) intracellular signaling in endothelial cells is initiated by the activation of distinct tyrosine kinase receptors, VEGFR1 (Flt-1) and VEGFR2 (Flk-1/KDR). Because the tyrosine kinase-dependent transcription factors known as STAT (signal transducers and activators of transcription) proteins are important modulators of cell growth responses induced by other growth factor receptors, we have determined the effects VEGF of on STAT activation in BAEC (bovine aortic endothelial cells). Here, we show that VEGF induces tyrosine phosphorylation and nuclear translocation of STAT1 and STAT6. VEGF also stimulates STAT3 tyrosine phosphorylation, but nuclear translocation does not occur. We found that placenta growth factor, which selectively activates VEGFR1, has no effect on the STATs. However, upon VEGF stimulation, STAT1 associates with the VEGFR2 in a tyrosine kinase-dependent manner, indicating that VEGF-induced STAT1 activation is mediated primarily by VEGFR2. Thus, our study shows for the first time that VEGF activates the STAT pathway through VEGFR2. Because the growth-promoting activity of VEGF depends upon VEGFR2 activation, these findings suggest a role for the STATs in the regulation of gene expression associated with the angiogenic effects of VEGF.
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Affiliation(s)
- M Bartoli
- Vascular Biology Center, Medical College of Georgia, Augusta, Georgia 30912-2500, USA
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28
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Abou-Mohamed GA, Huang J, Oldham CD, Taylor TA, Jin L, Caldwell RB, May SW, Caldwell RW. Vascular and endothelial actions of inhibitors of substance P amidation. J Cardiovasc Pharmacol 2000; 35:871-80. [PMID: 10836720 DOI: 10.1097/00005344-200006000-00007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Formation of mature active neuropeptides such as substance P (SP) from their glycine extended precursors entails alpha-amidation of peptide precursors by the sequential enzymatic action of peptidylglycine alpha-monooxygenase (PAM) and peptidylamidoglycolate lyase (PGL). We reported that these two enzymes that can produce mature active neuropeptides are present in cultured bovine aortic endothelial cells (BAECs). We hypothesize that alpha-amidation of peptides occurs in endothelial cells and that these peptides are critically involved in the overall regulation of cardiovascular function. In this study, this hypothesis was tested using specific amidation inhibitors to determine their effects on the actions of SP and its glycine-extended precursor (SP-Gly). We have found that SP and SP-Gly are equipotent in stimulating nitric oxide (NO) release by BAECs. At 10(-5) M, the specific inhibitors of PAM (4-phenyl-3-butenoic acid; PBA) and PGL (5-acetamido-2,4-diketo-6-phenyl-hexanoic acid and its methyl ester) reduced NO basal release by 40, 34, and 45%, respectively. They also reduced the production of NO induced by SP-Gly by 63, 68, and 69%, respectively, but had no effect on NO production in response to either SP or acetylcholine. SP and SP-Gly also were equipotent in relaxing rat aortic segments. The vasorelaxation to SP-Gly was endothelium dependent and inhibited by the NOS antagonist L-nitroarginine methyl ester (L-NAME), but it was not affected by inhibition of prostaglandin synthesis. Inhibitors of both PAM and PGL significantly reduced the vasorelaxing actions of SP-Gly, whereas responses to SP were not affected. A cumulative infusion of PBA into the femoral artery of rabbits, at final concentrations of 2.4, 24, and 240 microM for 20 min each, increased the vascular resistance (VR), indicating the tonic production of vasodilating amidated peptide(s). This effect was maximum at 60 min after infusion (20.5 +/- 4.7 vs. 8.2 +/- 0.7 mm Hg/ml/min; p < 0.05). These results suggest that endothelial cells can produce mature SP from its SP-Gly precursor and that a product of peptide alpha-amidation tonically stimulates endothelial cell NO release to control vascular tone.
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Affiliation(s)
- G A Abou-Mohamed
- Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta 30912, USA
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29
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Buchanan CD, Mahesh VB, Brann DW. Estrogen-astrocyte-luteinizing hormone-releasing hormone signaling: a role for transforming growth factor-beta(1). Biol Reprod 2000; 62:1710-21. [PMID: 10819775 DOI: 10.1095/biolreprod62.6.1710] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The purpose of this study was to identify factors from astrocytes that can regulate LHRH neurosecretion. Exposure of LHRH-secreting (GT1-7) cells to conditioned media (CM) from C6 glial cells and hypothalamic astrocytes (HA) stimulated LHRH release. Assays of C6 and HA CM revealed that transforming growth factor-beta(1) (TGF-beta(1)) and 3alpha-hydroxy-5alpha-pregnane-20-one (3alpha, 5alpha-THP), both known LHRH secretagogues, were present in CM and their levels increased in parallel to the LHRH-releasing activity of CM. In contrast, TGF-alpha was undetectable in C6 or HA CM. Ultrafiltration to remove peptides with molecular weights >10 kDa virtually abolished the LHRH-releasing ability of the HA CM. Furthermore, immunoneutralization with a panspecific THF-beta antibody dose-dependently attenuated the LHRH-releasing activity of the CM. Rat hypothalamus and GT1-7 cells were demonstrated to express TGF-beta receptors as well as furin, an enzyme that converts latent TGF-beta(1) to active TGF-beta(1). Estrogen receptor-alpha and ER-beta mRNA and protein were also demonstrated in HAs by reverse transcription-polymerase chain reaction and double immunofluorescence, and treatment with 17beta-estradiol (17beta-E(2)) increased both active and latent TGF-beta(1) levels in HA CM. The effect of 17beta-E(2) was completely blocked by the ER antagonist ICI8280. As a whole, these studies provide evidence of a previously undescribed 17beta-E(2)-TGF-beta(1)-LHRH signaling pathway.
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Affiliation(s)
- C D Buchanan
- Department of Physiology & Endocrinology, School of Medicine, Medical College of Georgia, Augusta, Georgia 30912-3000, USA
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30
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He H, Venema VJ, Gu X, Venema RC, Marrero MB, Caldwell RB. Vascular endothelial growth factor signals endothelial cell production of nitric oxide and prostacyclin through flk-1/KDR activation of c-Src. J Biol Chem 1999; 274:25130-5. [PMID: 10455194 DOI: 10.1074/jbc.274.35.25130] [Citation(s) in RCA: 369] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vascular endothelial growth factor (VEGF) is a potent endothelial cell-specific mitogen that promotes angiogenesis, vascular hyperpermeability, and vasodilation by autocrine mechanisms involving nitric oxide (NO) and prostacyclin (PGI(2)) production. These experiments used immunoprecipitation and immunoassay procedures to characterize the signaling pathways by which VEGF induces NO and PGI(2) formation in cultured endothelial cells. The data showed that VEGF stimulates complex formation of the flk-1/kinase-insert domain-containing receptor (KDR) VEGF receptor with c-Src and that Src activation is required for VEGF induction of phospholipase C gamma1 activation and inositol 1,4,5-trisphosphate formation. Reporter cell assays showed that VEGF promotes a approximately 50-fold increase in NO formation, which peaks at 5-20 min. This effect is mediated by a signaling cascade initiated by flk-1/KDR activation of c-Src, leading to phospholipase C gamma1 activation, inositol 1,4,5-trisphosphate formation, release of [Ca(2+)](i) and nitric oxide synthase activation. Immunoassays of VEGF-induced 6-keto prostaglandin F(1alpha) formation as an indicator of PGI(2) production revealed a 3-4-fold increase that peaked at 45-60 min. The PGI(2) signaling pathway follows the NO pathway through release of [Ca(2+)](i), but diverges prior to NOS activation and also requires activation of mitogen-activated protein kinase. These results suggest that NO and PGI(2) function in parallel in mediating the effects of VEGF.
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Affiliation(s)
- H He
- Vascular Biology Center, The Medical College of Georgia, Augusta, Georgia 30912-2500, USA
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31
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Wolburg H, Liebner S, Reichenbach A, Gerhardt H. The pecten oculi of the chicken: a model system for vascular differentiation and barrier maturation. INTERNATIONAL REVIEW OF CYTOLOGY 1999; 187:111-59. [PMID: 10212979 DOI: 10.1016/s0074-7696(08)62417-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The pecten oculi is a convolute of blood vessels in the vitreous body of the avian eye. This structure is well known for more than a century, but its functions are still a matter of controversies. One of these functions must be the formation of a blood-retina barrier because there is no diffusion barrier for blood-borne compounds available between the pecten and the retina. Surprisingly, the blood-retina barrier characteristics of this organ have not been studied so far, although the pecten oculi may constitute a fascinating model of vascular differentiation and barrier maturation: Pectinate endothelial cells grow by angiogenesis from the ophthalmotemporal artery into the pecten primordium and consecutively gain barrier properties. The pectinate pigmented cells arise during development from retinal pigment epithelial cells and subsequently lose barrier properties. These inverse transdifferentiation processes may be triggered by the peculiar microenvironment in the vitreous body. In addition, the question is discussed whether the avascularity of the avian retina may be due to the specific metabolic activity of the pecten.
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Affiliation(s)
- H Wolburg
- Institute of Pathology, University of Tübingen, Germany
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32
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Feng Y, Venema VJ, Venema RC, Tsai N, Caldwell RB. VEGF induces nuclear translocation of Flk-1/KDR, endothelial nitric oxide synthase, and caveolin-1 in vascular endothelial cells. Biochem Biophys Res Commun 1999; 256:192-7. [PMID: 10066445 DOI: 10.1006/bbrc.1998.9790] [Citation(s) in RCA: 168] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
VEGF increases endothelial cell permeability and growth by a process requiring NOS activity. Because eNOS activity is regulated by its interaction with the caveolar structural protein caveolin-1, we analyzed VEGF effects on structural interactions between eNOS, caveolin-1 and the VEGF receptor Flk-1/KDR. Confocal immunolocalization analysis of the subcellular distribution of Flk-1/KDR, caveolin-1 and eNOS showed that VEGF stimulated the translocation of all three proteins into the nucleus. This result was confirmed by cell fractionation and immunoblotting studies showing that levels of all three proteins within the caveolar compartment declined progressively after 30 and 60 min of VEGF treatment. The pattern was reversed for nuclear fractions. Protein levels were lowest in the control cultures, but increased progressively after 30 and 60 min of treatment. Nuclear translocation of eNOS and Flk-1/KDR within caveolae may represent a mechanism for targeting NO production to the nuclear compartment where it could influence transcription factor activation.
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Affiliation(s)
- Y Feng
- The Vascular Biology Center, The Medical College of Georgia, Augusta, Georgia, 30912, USA
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33
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Behzadian MA, Wang XL, Shabrawey M, Caldwell RB. Effects of hypoxia on glial cell expression of angiogenesis-regulating factors VEGF and TGF-? Glia 1998. [DOI: 10.1002/(sici)1098-1136(199810)24:2<216::aid-glia6>3.0.co;2-1] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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34
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Vinores SA, Chan CC, Vinores MA, Matteson DM, Chen YS, Klein DA, Shi A, Ozaki H, Campochiaro PA. Increased vascular endothelial growth factor (VEGF) and transforming growth factor beta (TGFbeta) in experimental autoimmune uveoretinitis: upregulation of VEGF without neovascularization. J Neuroimmunol 1998; 89:43-50. [PMID: 9726824 DOI: 10.1016/s0165-5728(98)00075-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Experimental autoimmune uveoretinitis (EAU) was induced in Lewis rats and B10.A mice by immunization with S-antigen (S-Ag) to study the potential roles of vascular endothelial growth factor (VEGF) and the beta1 and beta2 isoforms of transforming growth factor (TGFbeta1 and TGFbeta2) during the progression of the disease. VEGF has been implicated as an angiogenic factor in ischemic retinopathies; however, Lewis rats developing EAU have high levels of VEGF in the retina, but no neovascularization. In the present study, immunohistochemical staining for VEGF, TGFbeta1 and TGFbeta2 was performed on the retinas of Lewis rats developing EAU or with oxygen-induced ischemic retinopathy. In rats immunized with S-antigen, a marked upregulation of VEGF was immunohistochemically visualized from the inner nuclear layer to the inner limiting membrane prior to blood-retinal barrier (BRB) failure and lymphocytic infiltration. VEGF is normally induced by hypoxia and its induction leads to neovascularization. Coincident with the increase in VEGF, there was increased immunoreactivity for TGFbeta1 and TGFbeta2 within the same layers of the retina. In contrast, rats with ischemic retinopathy and retinal neovascularization showed only a modest increase in VEGF immunoreactivity, which is largely confined to retinal ganglion cells and inner retinal vessels, and little or no increase in TGFbeta1 or TGFbeta2. In addition, in mice developing EAU, which does not have an abrupt onset as it does in rats and may involve neovascularization, a comparable upregulation of VEGF in the inner retina to that seen in rats developing EAU occurs with no increase in TGFbeta1 or TGFbeta2. Since TGFbeta can inhibit endothelial cell proliferation, it is likely that an increase in TGFbeta may prevent VEGF from exerting its endothelial growth activity in the rat EAU model, but VEGF may be operative in inducing BRB failure. These data suggest that there is a complex interaction among growth factors in the retina and that retinal neovascularization may require an imbalance between stimulatory and inhibitory factors.
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Affiliation(s)
- S A Vinores
- The Wilmer Ophthalmologic Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287-9289, USA
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35
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Vincent VA, Tilders FJ, Van Dam AM. Production, regulation and role of nitric oxide in glial cells. Mediators Inflamm 1998; 7:239-55. [PMID: 9792334 PMCID: PMC1781853 DOI: 10.1080/09629359890929] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Affiliation(s)
- V A Vincent
- Research Institute Neurosciences Free University, Medical Faculty, Department of Pharmacology, Amsterdam, The Netherlands
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36
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Oldham CD, Li C, Feng J, Scott RO, Wang WZ, Moore AB, Girard PR, Huang J, Caldwell RB, Caldwell RW, May SW. Amidative peptide processing and vascular function. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:C1908-14. [PMID: 9435496 DOI: 10.1152/ajpcell.1997.273.6.c1908] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Substance P (SP), an amidated peptide present in many sensory nerves, is known to affect cardiovascular function, and exogenously supplied SP has been shown to activate nitric oxide synthase (NOS) in endothelial cells. We now report that SP-Gly, the glycine-extended biosynthetic precursor of SP (which is enzymatically processed to the mature amidated SP), causes relaxation of rat aortic strips with an efficacy and potency comparable to that of SP itself. Pretreatment of the aortic strips with 4-phenyl-3-butenoic acid (PBA), an irreversible amidating enzyme inactivator, results in marked inhibition of the vasodilation activity induced by SP-Gly but not of that induced by SP itself. Isolated endothelial cell basal NOS activity is also decreased by pretreatment with PBA, with no evidence of cell death or direct action of PBA on NOS activity. Both bifunctional and monofunctional forms of amidating enzymes are present in endothelial cells, as evidenced by affinity chromatography and Western blot analysis. These results provide evidence for a link between amidative peptide processing, NOS activation in endothelial cells, and vasodilation and suggest that a product of amidative processing provides intrinsic basal activation of NOS in endothelial cells.
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MESH Headings
- Amino Acid Sequence
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/physiology
- Cattle
- Cells, Cultured
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/enzymology
- Endothelium, Vascular/physiology
- In Vitro Techniques
- Kinetics
- Male
- Mixed Function Oxygenases/metabolism
- Molecular Sequence Data
- Multienzyme Complexes
- Muscle Relaxation/drug effects
- Muscle Relaxation/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Nitric Oxide Synthase/metabolism
- Peptide Fragments/chemical synthesis
- Peptide Fragments/pharmacology
- Rats
- Rats, Sprague-Dawley
- Substance P/analogs & derivatives
- Substance P/chemistry
- Substance P/pharmacology
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Affiliation(s)
- C D Oldham
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta 30332, USA
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37
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El Hafny B, Chappey O, Piciotti M, Debray M, Boval B, Roux F. Modulation of P-glycoprotein activity by glial factors and retinoic acid in an immortalized rat brain microvessel endothelial cell line. Neurosci Lett 1997; 236:107-11. [PMID: 9404823 DOI: 10.1016/s0304-3940(97)00679-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
P-glycoprotein (P-gp), a product of the multidrug-resistant (mdr) genes, is expressed in the endothelial cells of the blood-brain barrier (BBB). Effects of glial factors and retinoic acid (RA) on P-gp activity and level were investigated in the immortalized rat brain endothelial cell line RBE4, which expressed immunodetectable P-gp associated with a decrease in accumulation of the P-gp substrates, vinblastine and colchicine. When RBE4 cells were cultured either in the presence of C6-conditioned medium or on C6- or astrocyte-extracellular matrix, intracellular vinblastine and colchicine concentrations were decreased. When the cells were treated with RA, increases in P-gp activities were correlated with increases in P-gp levels. Effects of simultaneous treatments with glial factors and RA were studied in RBE4 cells cultured on astrocyte-extracellular matrix and were shown to be additive on P-gp activity and level. RBE4 cells may serve as a useful in vitro model for basic research on P-gp regulation at the level of the BBB.
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Affiliation(s)
- B El Hafny
- INSERM U 26, Unité de Neuro-Pharmaco-Nutrition, Hôpital Fernand Widal, Paris, France
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38
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Chen YS, Hackett SF, Schoenfeld CL, Vinores MA, Vinores SA, Campochiaro PA. Localisation of vascular endothelial growth factor and its receptors to cells of vascular and avascular epiretinal membranes. Br J Ophthalmol 1997; 81:919-26. [PMID: 9486038 PMCID: PMC1722016 DOI: 10.1136/bjo.81.10.919] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
AIMS/BACKGROUND Epiretinal membranes (ERMs) arise from a variety of causes or, in some cases, for unknown reasons. Once established, ERMs tend to progress, becoming more extensive and exerting increasing traction along the inner surface of the retina. One possible cause for their progression is the production of growth factors by cells within ERMs that may provide autocrine or paracrine stimulation. Platelet derived growth factor (PDGF) and its receptors have been localised to cells of ERMs and may play such a role. In this study, comparative data were sought for several other growth factors that have been implicated in ERM formation. METHODS Immunohistochemical staining of ERMs was done for PDGF-A, PDGF-B, basic fibroblast growth factor (bFGF), three isoforms of transforming growth factor beta (TGF-beta), and vascular endothelial growth factor (VEGF) and its receptors, flt-1 and flk-1/KDR. Expression of flt-1 and flk-1/KDR was examined in cultured retinal pigmented epithelial (RPE) cells and retinal glia from postmortem eyes by immunohistochemistry and by reverse transcription coupled to polymerase chain reaction (RT-PCR). RESULTS Staining was most intense and most frequently observed for VEGF and PDGF-A, both in vascular and avascular ERMs. The majority of cells stained for VEGF in nine of 11 (81.8%) diabetic ERMs and in 14 of 24 (58.3%) proliferative vitreoretinopathy ERMs. The receptors for VEGF, flt-1, and flk-1/KDR were also identified on cells in ERMs and on cultured RPE cells. By RT-PCR, mRNA for flt-1 was identified in RPE cells and retinal glia, and mRNA for flk-1/KDR was identified in RPE cells. CONCLUSIONS These data show that VEGF and its receptors are localised to both vascular and avascular ERMs and suggest that VEGF, like PDGF-A, may be an autocrine and paracrine stimulator that may contribute to progression of vascular and avascular ERMs.
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Affiliation(s)
- Y S Chen
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287-9277, USA
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