1
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Du Y, Yan B. Ocular immune privilege and retinal pigment epithelial cells. J Leukoc Biol 2023; 113:288-304. [PMID: 36805720 DOI: 10.1093/jleuko/qiac016] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Indexed: 02/04/2023] Open
Abstract
The ocular tissue microenvironment is immune-privileged and uses multiple immunosuppressive mechanisms to prevent the induction of inflammation. The retinal pigment epithelium plays an essential role in ocular immune privilege. In addition to serving as a blood barrier separating the fenestrated choriocapillaris from the retina, the retinal pigment epithelium is a source of immunosuppressive cytokines and membrane-bound negative regulators that modulate the activity of immune cells within the retina. This article reviews the current understanding of how retinal pigment epithelium cells mediate immune regulation, focusing on the changes under pathologic conditions.
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Affiliation(s)
- Yuxiang Du
- Institute of Precision Medicine, Jining Medical University, No. 133, Hehua Road, Taibaihu New District, Jining, Shandong 272067, People's Republic of China
| | - Bo Yan
- Institute of Precision Medicine, Jining Medical University, No. 133, Hehua Road, Taibaihu New District, Jining, Shandong 272067, People's Republic of China
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2
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Amato R, Catalani E, Dal Monte M, Cammalleri M, Cervia D, Casini G. Morpho-functional analysis of the early changes induced in retinal ganglion cells by the onset of diabetic retinopathy: The effects of a neuroprotective strategy. Pharmacol Res 2022; 185:106516. [DOI: 10.1016/j.phrs.2022.106516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/05/2022] [Accepted: 10/14/2022] [Indexed: 10/31/2022]
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3
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Pöstyéni E, Ganczer A, Kovács-Valasek A, Gabriel R. Relevance of Peptide Homeostasis in Metabolic Retinal Degenerative Disorders: Curative Potential in Genetically Modified Mice. Front Pharmacol 2022; 12:808315. [PMID: 35095518 PMCID: PMC8793341 DOI: 10.3389/fphar.2021.808315] [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: 11/03/2021] [Accepted: 12/20/2021] [Indexed: 11/19/2022] Open
Abstract
The mammalian retina contains approximately 30 neuropeptides that are synthetized by different neuronal cell populations, glia, and the pigmented epithelium. The presence of these neuropeptides leaves a mark on normal retinal molecular processes and physiology, and they are also crucial in fighting various pathologies (e.g., diabetic retinopathy, ischemia, age-related pathologies, glaucoma) because of their protective abilities. Retinal pathologies of different origin (metabolic, genetic) are extensively investigated by genetically manipulated in vivo mouse models that help us gain a better understanding of the molecular background of these pathomechanisms. These models offer opportunities to manipulate gene expression in different cell types to help reveal their roles in the preservation of retinal health or identify malfunction during diseases. In order to assess the current status of transgenic technologies available, we have conducted a literature survey focused on retinal disorders of metabolic origin, zooming in on the role of retinal neuropeptides in diabetic retinopathy and ischemia. First, we identified those neuropeptides that are most relevant to retinal pathologies in humans and the two clinically most relevant models, mice and rats. Then we continued our analysis with metabolic disorders, examining neuropeptide-related pathways leading to systemic or cellular damage and rescue. Last but not least, we reviewed the available literature on genetically modified mouse strains to understand how the manipulation of a single element of any given pathway (e.g., signal molecules, receptors, intracellular signaling pathways) could lead either to the worsening of disease conditions or, more frequently, to substantial improvements in retinal health. Most attention was given to studies which reported successful intervention against specific disorders. For these experiments, a detailed evaluation will be given and the possible role of converging intracellular pathways will be discussed. Using these converging intracellular pathways, curative effects of peptides could potentially be utilized in fighting metabolic retinal disorders.
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Affiliation(s)
- Etelka Pöstyéni
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
| | - Alma Ganczer
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary.,János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
| | - Andrea Kovács-Valasek
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
| | - Robert Gabriel
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary.,János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
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4
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Catalani E, Bongiorni S, Taddei AR, Mezzetti M, Silvestri F, Coazzoli M, Zecchini S, Giovarelli M, Perrotta C, De Palma C, Clementi E, Ceci M, Prantera G, Cervia D. Defects of full-length dystrophin trigger retinal neuron damage and synapse alterations by disrupting functional autophagy. Cell Mol Life Sci 2020; 78:1615-1636. [PMID: 32749504 PMCID: PMC7904721 DOI: 10.1007/s00018-020-03598-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 06/10/2020] [Accepted: 07/09/2020] [Indexed: 02/06/2023]
Abstract
Dystrophin (dys) mutations predispose Duchenne muscular disease (DMD) patients to brain and retinal complications. Although different dys variants, including long dys products, are expressed in the retina, their function is largely unknown. We investigated the putative role of full-length dystrophin in the homeostasis of neuro-retina and its impact on synapsis stabilization and cell fate. Retinas of mdx mice, the most used DMD model which does not express the 427-KDa dys protein (Dp427), showed overlapped cell death and impaired autophagy. Apoptotic neurons in the outer plexiform/inner nuclear layer and the ganglion cell layer had an impaired autophagy with accumulated autophagosomes. The autophagy dysfunction localized at photoreceptor axonal terminals and bipolar, amacrine, and ganglion cells. The absence of Dp427 does not cause a severe phenotype but alters the neuronal architecture, compromising mainly the pre-synaptic photoreceptor terminals and their post-synaptic sites. The analysis of two dystrophic mutants of the fruit fly Drosophila melanogaster, the homozygous DysE17 and DysEP3397, lacking functional large-isoforms of dystrophin-like protein, revealed rhabdomere degeneration. Structural damages were evident in the internal network of retina/lamina where photoreceptors make the first synapse. Both accumulated autophagosomes and apoptotic features were detected and the visual system was functionally impaired. The reactivation of the autophagosome turnover by rapamycin prevented neuronal cell death and structural changes of mutant flies and, of interest, sustained autophagy ameliorated their response to light. Overall, these findings indicate that functional full-length dystrophin is required for synapsis stabilization and neuronal survival of the retina, allowing also proper autophagy as a prerequisite for physiological cell fate and visual properties.
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Affiliation(s)
- Elisabetta Catalani
- Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Silvia Bongiorni
- Department of Ecological and Biological Sciences (DEB), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Anna Rita Taddei
- Section of Electron Microscopy, Great Equipment Center, Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Marta Mezzetti
- Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Federica Silvestri
- Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Marco Coazzoli
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy
| | - Silvia Zecchini
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy
| | - Matteo Giovarelli
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy
| | - Cristiana Perrotta
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy
| | - Clara De Palma
- Department of Medical Biotechnology and Translational Medicine (BioMeTra), Università degli Studi di Milano, via Luigi Vanvitelli 32, 20129 , Milano, Italy
| | - Emilio Clementi
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy
- Unit of Clinical Pharmacology, University Hospital "Luigi Sacco"-ASST Fatebenefratelli Sacco, via G.B. Grassi 74, 20157, Milano, Italy
- Scientific Institute IRCCS "Eugenio Medea", via Don Luigi Monza 20, 23842, Bosisio Parini (LC), Italy
| | - Marcello Ceci
- Department of Ecological and Biological Sciences (DEB), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Giorgio Prantera
- Department of Ecological and Biological Sciences (DEB), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Davide Cervia
- Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy.
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy.
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5
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Rossino MG, Dal Monte M, Casini G. Relationships Between Neurodegeneration and Vascular Damage in Diabetic Retinopathy. Front Neurosci 2019; 13:1172. [PMID: 31787868 PMCID: PMC6856056 DOI: 10.3389/fnins.2019.01172] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/16/2019] [Indexed: 12/15/2022] Open
Abstract
Diabetic retinopathy (DR) is a common complication of diabetes and constitutes a major cause of vision impairment and blindness in the world. DR has long been described exclusively as a microvascular disease of the eye. However, in recent years, a growing interest has been focused on the contribution of neuroretinal degeneration to the pathogenesis of the disease, and there are observations suggesting that neuronal death in the early phases of DR may favor the development of microvascular abnormalities, followed by the full manifestation of the disease. However, the mediators that are involved in the crosslink between neurodegeneration and vascular changes have not yet been identified. According to our hypothesis, vascular endothelial growth factor (VEGF) could probably be the most important connecting link between the death of retinal neurons and the occurrence of microvascular lesions. Indeed, VEGF is known to play important neuroprotective actions; therefore, in the early phases of DR, it may be released in response to neuronal suffering, and it would act as a double-edged weapon inducing both neuroprotective and vasoactive effects. If this hypothesis is correct, then any retinal stress causing neuronal damage should be accompanied by VEGF upregulation and by vascular changes. Similarly, any compound with neuroprotective properties should also induce VEGF downregulation and amelioration of the vascular lesions. In this review, we searched for a correlation between neurodegeneration and vasculopathy in animal models of retinal diseases, examining the effects of different neuroprotective substances, ranging from nutraceuticals to antioxidants to neuropeptides and others and showing that reducing neuronal suffering also prevents overexpression of VEGF and vascular complications. Taken together, the reviewed evidence highlights the crucial role played by mediators such as VEGF in the relationship between retinal neuronal damage and vascular alterations and suggests that the use of neuroprotective substances could be an efficient strategy to prevent the onset or to retard the development of DR.
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Affiliation(s)
| | - Massimo Dal Monte
- Department of Biology, University of Pisa, Pisa, Italy.,Interdepartmental Research Center Nutrafood "Nutraceuticals and Food for Health", University of Pisa, Pisa, Italy
| | - Giovanni Casini
- Department of Biology, University of Pisa, Pisa, Italy.,Interdepartmental Research Center Nutrafood "Nutraceuticals and Food for Health", University of Pisa, Pisa, Italy
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6
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Neuroprotective Peptides in Retinal Disease. J Clin Med 2019; 8:jcm8081146. [PMID: 31374938 PMCID: PMC6722704 DOI: 10.3390/jcm8081146] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 07/26/2019] [Accepted: 07/31/2019] [Indexed: 02/07/2023] Open
Abstract
In the pathogenesis of many disorders, neuronal death plays a key role. It is now assumed that neurodegeneration is caused by multiple and somewhat converging/overlapping death mechanisms, and that neurons are sensitive to unique death styles. In this respect, major advances in the knowledge of different types, mechanisms, and roles of neurodegeneration are crucial to restore the neuronal functions involved in neuroprotection. Several novel concepts have emerged recently, suggesting that the modulation of the neuropeptide system may provide an entirely new set of pharmacological approaches. Neuropeptides and their receptors are expressed widely in mammalian retinas, where they exert neuromodulatory functions including the processing of visual information. In multiple models of retinal diseases, different peptidergic substances play neuroprotective actions. Herein, we describe the novel advances on the protective roles of neuropeptides in the retina. In particular, we focus on the mechanisms by which peptides affect neuronal death/survival and the vascular lesions commonly associated with retinal neurodegenerative pathologies. The goal is to highlight the therapeutic potential of neuropeptide systems as neuroprotectants in retinal diseases.
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7
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Molecular and Cellular Mechanisms Underlying Somatostatin-Based Signaling in Two Model Neural Networks, the Retina and the Hippocampus. Int J Mol Sci 2019; 20:ijms20102506. [PMID: 31117258 PMCID: PMC6566141 DOI: 10.3390/ijms20102506] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 05/16/2019] [Accepted: 05/20/2019] [Indexed: 02/06/2023] Open
Abstract
Neural inhibition plays a key role in determining the specific computational tasks of different brain circuitries. This functional "braking" activity is provided by inhibitory interneurons that use different neurochemicals for signaling. One of these substances, somatostatin, is found in several neural networks, raising questions about the significance of its widespread occurrence and usage. Here, we address this issue by analyzing the somatostatinergic system in two regions of the central nervous system: the retina and the hippocampus. By comparing the available information on these structures, we identify common motifs in the action of somatostatin that may explain its involvement in such diverse circuitries. The emerging concept is that somatostatin-based signaling, through conserved molecular and cellular mechanisms, allows neural networks to operate correctly.
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8
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Lehman JM, Hoeksema MD, Staub J, Qian J, Harris B, Callison JC, Miao J, Shi C, Eisenberg R, Chen H, Chen SC, Massion PP. Somatostatin receptor 2 signaling promotes growth and tumor survival in small-cell lung cancer. Int J Cancer 2018; 144:1104-1114. [PMID: 30152518 DOI: 10.1002/ijc.31771] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 06/18/2018] [Accepted: 06/25/2018] [Indexed: 12/12/2022]
Abstract
Somatostatin receptor 2 (SSTR2) is overexpressed in a majority of neuroendocrine neoplasms, including small-cell lung carcinomas (SCLCs). SSTR2 was previously considered an inhibitory receptor on cell growth, but its agonists had poor clinical responses in multiple clinical trials. The role of this receptor as a potential therapeutic target in lung cancer merits further investigation. We evaluated the expression of SSTR2 in a cohort of 96 primary tumors from patients with SCLC and found 48% expressed SSTR2. Correlation analysis in both CCLE and an SCLC RNAseq cohort confirmed high-level expression and identified an association between NEUROD1 and SSTR2. There was a significant association with SSTR2 expression profile and poor clinical outcome. We tested whether SSTR2 expression might contribute to tumor progression through activation of downstream signaling pathways, using in vitro and in vivo systems and downregulated SSTR2 expression in lung cancer cells by shRNA. SSTR2 downregulation led to increased apoptosis and dramatically decreased tumor growth in vitro and in vivo in multiple cell lines with decreased AMPKα phosphorylation and increased oxidative metabolism. These results demonstrate a role for SSTR2 signaling in SCLC and suggest that SSTR2 is a poor prognostic biomarker in SCLC and potential future therapeutic signaling target.
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Affiliation(s)
- Jonathan M Lehman
- Division of Medical Oncology, Vanderbilt Ingram Cancer Center, Nashville, TN.,Cancer Early Detection and Prevention Initiative, Vanderbilt Ingram Cancer Center, Nashville, TN.,Veterans Affairs, Tennessee Valley Healthcare System, Nashville Campus, Nashville, TN
| | - Megan D Hoeksema
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt Ingram Cancer Center, Nashville, TN.,Cancer Early Detection and Prevention Initiative, Vanderbilt Ingram Cancer Center, Nashville, TN
| | - Jeremy Staub
- Division of Medical Oncology, Vanderbilt Ingram Cancer Center, Nashville, TN
| | - Jun Qian
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt Ingram Cancer Center, Nashville, TN.,Cancer Early Detection and Prevention Initiative, Vanderbilt Ingram Cancer Center, Nashville, TN
| | - Bradford Harris
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt Ingram Cancer Center, Nashville, TN
| | - J Clay Callison
- University of Tennessee Graduate School of Medicine, Tennessee Valley Healthcare System, Nashville Campus, Nashville, TN
| | - Jennifer Miao
- Vanderbilt University School of Medicine, Tennessee Valley Healthcare System, Nashville Campus, Nashville, TN
| | - Chanjuan Shi
- Department of Pathology, Microbiology and Immunology, Tennessee Valley Healthcare System, Nashville Campus, Nashville, TN
| | - Rosana Eisenberg
- Department of Pathology, Microbiology and Immunology, Tennessee Valley Healthcare System, Nashville Campus, Nashville, TN
| | - Heidi Chen
- Vanderbilt University Department of Biostatistics, Tennessee Valley Healthcare System, Nashville Campus, Nashville, TN
| | - Sheau-Chiann Chen
- Vanderbilt University Department of Biostatistics, Tennessee Valley Healthcare System, Nashville Campus, Nashville, TN
| | - Pierre P Massion
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt Ingram Cancer Center, Nashville, TN.,Cancer Early Detection and Prevention Initiative, Vanderbilt Ingram Cancer Center, Nashville, TN.,Veterans Affairs, Tennessee Valley Healthcare System, Nashville Campus, Nashville, TN
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9
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Choi MR, Chun JW, Kwak SM, Bang SH, Jin YB, Lee Y, Kim HN, Chang KT, Chai YG, Lee SR, Kim DJ. Effects of acute and chronic methamphetamine administration on cynomolgus monkey hippocampus structure and cellular transcriptome. Toxicol Appl Pharmacol 2018; 355:68-79. [DOI: 10.1016/j.taap.2018.05.031] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 05/21/2018] [Accepted: 05/22/2018] [Indexed: 12/13/2022]
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10
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Amato R, Dal Monte M, Lulli M, Raffa V, Casini G. Nanoparticle-Mediated Delivery of Neuroprotective Substances for the Treatment of Diabetic Retinopathy. Curr Neuropharmacol 2018; 16:993-1003. [PMID: 28714394 PMCID: PMC6120116 DOI: 10.2174/1570159x15666170717115654] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 05/04/2017] [Accepted: 07/14/2017] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Diabetic retinopathy (DR) is a major complication of diabetes, characterized by extensive vascular pathology leading to vision loss. Neuronal suffering and death are also present in the diabetic retina as a result of different molecular mechanisms that are compromised or modified in response to high glucose. The aim of this paper is to highlight recent data indicating that neurodegeneration is likely to play a primary role in the development of DR and that strategies based on nanomedicine may be exploited to deliver neuroprotection to the retina. METHODS An extensive analysis of the publications dealing with the role of neuroprotection in DR and with nanoparticle-mediated drug delivery to the retina has been conducted using PubMed, with particular attention to the most recent papers. RESULTS There are important limitations related to possible systemic side effects of neuroprotective substances and to drug bioavailability in the retina such as, for instance, the amount of drug reaching the retina, the need of keeping to a minimum the number of administrations (especially, for example, in the case of intraocular injections) and the need of assuring a long-lasting, graded intraocular drug delivery. In recent years, a variety of investigations have been aimed at the exploitation of approaches of nanomedicine to enhance the pharmacokinetics and pharmacodynamic activity of intraocularly delivered drugs. In particular, we provide some preliminary results that we have obtained about the feasibility of delivering magnetic nanoparticles functionalized with a neuroprotectant to mouse eyes through intraocular injections. CONCLUSION We propose that nanoparticles functionalized with neuroprotective substances may be used to protect the diabetic retina, thus causing an impact in the design of future pharmacologic treatments for DR.
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Affiliation(s)
| | | | | | | | - Giovanni Casini
- Address correspondence to this author at the Department of Biology, University of Pisa, via S. Zeno 31, I-56127 Pisa, Italy; Tel: ++39-050-2211423; E-mail:
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11
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Cammalleri M, Locri F, Catalani E, Filippi L, Cervia D, Dal Monte M, Bagnoli P. The Beta Adrenergic Receptor Blocker Propranolol Counteracts Retinal Dysfunction in a Mouse Model of Oxygen Induced Retinopathy: Restoring the Balance between Apoptosis and Autophagy. Front Cell Neurosci 2017; 11:395. [PMID: 29375312 PMCID: PMC5770647 DOI: 10.3389/fncel.2017.00395] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 11/28/2017] [Indexed: 12/29/2022] Open
Abstract
In a mouse model of oxygen induced retinopathy (OIR), beta adrenergic receptor (BAR) blockade has been shown to recover hypoxia-associated retinal damages. Although the adrenergic signaling is an important regulator of apoptotic and autophagic processes, the role of BARs in retinal cell death remains to be elucidated. The present study was aimed at investigating whether ameliorative effects of BAR blockers may occur through their coordinated action on apoptosis and autophagy. To this aim, retinas from control and OIR mice untreated or treated with propranolol, a non-selective BAR1/2 blocker, were characterized in terms of expression and localization of apoptosis and autophagy markers. The effects of propranolol on autophagy signaling were also evaluated and specific autophagy modulators were used to get functional information on the autophagic effects of BAR antagonism. Finally, propranolol effects on neurodegenerative processes were associated to an electrophysiological investigation of retinal function by recording electroretinogram (ERG). We found that retinas of OIR mice are characterized by increased apoptosis and decreased autophagy, while propranolol reduces apoptosis and stimulates autophagy. In particular, propranolol triggers autophagosome formation in bipolar, amacrine and ganglion cells that are committed to die by apoptosis in response to hypoxia. Also our data argue that propranolol, through the inhibition of the Akt-mammalian target of rapamycin pathway, activates autophagy which decreases retinal cell death. At the functional level, propranolol recovers dysfunctional ERG by recovering the amplitude of a- and b-waves, and oscillatory potentials, thus indicating an efficient restoring of retinal transduction. Overall, our results demonstrate that BAR1/2 are key regulators of retinal apoptosis/autophagy, and that BAR1/2 blockade leads to autophagy-mediated neuroprotection. Reinstating the balance between apoptotic and autophagic machines may therefore be viewed as a future goal in the treatment of retinopathies.
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Affiliation(s)
| | - Filippo Locri
- Department of Biology, University of Pisa, Pisa, Italy
| | - Elisabetta Catalani
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Luca Filippi
- Neonatal Intensive Care Unit, Medical Surgical Fetal-Neonatal Department, Meyer University Children's Hospital, Florence, Italy
| | - Davide Cervia
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, Viterbo, Italy
| | | | - Paola Bagnoli
- Department of Biology, University of Pisa, Pisa, Italy
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12
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Rai U, Thrimawithana TR, Dharmadana D, Valery C, Young SA. Release kinetics of somatostatin from self-assembled nanostructured hydrogels. Biopolymers 2017; 110. [PMID: 29127701 DOI: 10.1002/bip.23085] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 10/16/2017] [Accepted: 10/24/2017] [Indexed: 11/09/2022]
Abstract
Somatostatin-14 is a native neuropeptide with widespread functions in the body. Self-assembly of somatostatin-14 into amyloid-like nanofibrils has been previously demonstrated in aqueous media. We here hypothesize that the somatostatin nanofibrils can form a stable depot that release monomers in a controlled manner. This study aims to investigate if somatostatin monomers are released from physical hydrogels formed in water and in the presence of electrolytes. The release kinetics of the somatostatin monomers is investigated for the first time. This is correlated with the rheological properties of the hydrogels formed. We demonstrate that at the concentrations tested, there is release of somatostatin monomers from the hydrogels following a novel hybrid model of zero-order and first-order release. In the presence of electrolytes, somatostatin hydrogels demonstrated higher elastic moduli (G') which correlates to the narrower and higher density of nanofibrils observed with TEM. The presence of electrolytes resulted in a slower release of the somatostatin monomers and in a lower cumulative percentage released over 48 hrs. It is questionable that the concentrations released will be therapeutically effective. However, self-assembled somatostatin hydrogels have the potential to act as a depot for ocular drug delivery.
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Affiliation(s)
- Uma Rai
- Discipline of Pharmacy, School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, 3083, Australia
| | - Thilini R Thrimawithana
- Discipline of Pharmacy, School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, 3083, Australia
| | - Durga Dharmadana
- Discipline of Pharmaceutical Sciences, School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, 3083, Australia
| | - Celine Valery
- Discipline of Pharmaceutical Sciences, School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, 3083, Australia
| | - Simon A Young
- Discipline of Pharmacy, School of Health and Biomedical Sciences, RMIT University, Bundoora, Victoria, 3083, Australia
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13
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Amato R, Catalani E, Dal Monte M, Cammalleri M, Di Renzo I, Perrotta C, Cervia D, Casini G. Autophagy-mediated neuroprotection induced by octreotide in an ex vivo model of early diabetic retinopathy. Pharmacol Res 2017; 128:167-178. [PMID: 28970178 DOI: 10.1016/j.phrs.2017.09.022] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/21/2017] [Accepted: 09/28/2017] [Indexed: 12/18/2022]
Abstract
Neuronal injury plays a major role in diabetic retinopathy (DR). Our hypothesis was that the balance between neuronal death and survival may depend on a similar equilibrium between apoptosis and autophagy and that a neuroprotectant may act by influencing this equilibrium. Ex vivo mouse retinal explants were treated with high glucose (HG) for 10days and the somatostatin analog octreotide (OCT) was used as a neuroprotectant. Chloroquine (CQ) was used as an autophagy inhibitor. Apoptotic and autophagic markers were evaluated using western blot and immunohistochemistry. HG-treated explants displayed a significant increase of apoptosis paralleled by a significant decrease of the autophagic flux, which was likely to be due to increased activity of the autophagy regulator mTOR (mammalian target of rapamycin). Treatment with OCT rescued HG-treated retinal explants from apoptosis and determined an increase of autophagic activity with concomitant mTOR inhibition. Blocking the autophagic flux with CQ completely abolished the anti-apoptotic effect of OCT. Immunohistochemical observations showed that OCT-induced autophagy is localized to populations of bipolar and amacrine cells and to ganglion cells. These observations revealed the antithetic role of apoptosis and autophagy, highlighting their equilibrium from which neuronal survival is likely to depend. These data suggest the crucial role covered by autophagy, which could be considered as a molecular target for DR neuroprotective treatment strategies.
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Affiliation(s)
- Rosario Amato
- Department of Biology, University of Pisa, Pisa, Italy
| | - Elisabetta Catalani
- Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), University of Tuscia, Viterbo, Italy
| | - Massimo Dal Monte
- Department of Biology, University of Pisa, Pisa, Italy; Interdepartmental Research Center Nutrafood "Nutraceuticals and Food for Health", University of Pisa, Pisa, Italy
| | | | - Ilaria Di Renzo
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), University of Milano, Milano, Italy
| | - Cristiana Perrotta
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), University of Milano, Milano, Italy
| | - Davide Cervia
- Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), University of Tuscia, Viterbo, Italy.
| | - Giovanni Casini
- Department of Biology, University of Pisa, Pisa, Italy; Interdepartmental Research Center Nutrafood "Nutraceuticals and Food for Health", University of Pisa, Pisa, Italy.
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Wood MB, Rios D, Williams IR. TNF-α augments RANKL-dependent intestinal M cell differentiation in enteroid cultures. Am J Physiol Cell Physiol 2016; 311:C498-507. [PMID: 27413168 PMCID: PMC5129760 DOI: 10.1152/ajpcell.00108.2016] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 07/12/2016] [Indexed: 01/13/2023]
Abstract
Microfold (M) cells are phagocytic intestinal epithelial cells in the follicle-associated epithelium of Peyer's patches that transport particulate antigens from the gut lumen into the subepithelial dome. Differentiation of M cells from epithelial stem cells in intestinal crypts requires the cytokine receptor activator of NF-κB ligand (RANKL) and the transcription factor Spi-B. We used three-dimensional enteroid cultures established with small intestinal crypts from mice as a model system to investigate signaling pathways involved in M cell differentiation and the influence of other cytokines on RANKL-induced M cell differentiation. Addition of RANKL to enteroids induced expression of multiple M cell-associated genes, including Spib, Ccl9 [chemokine (C-C motif) ligand 9], Tnfaip2 (TNF-α-induced protein 2), Anxa5 (annexin A5), and Marcksl1 (myristoylated alanine-rich protein kinase C substrate) in 1 day. The mature M cell marker glycoprotein 2 (Gp2) was strongly induced by 3 days and expressed by 11% of cells in enteroids. The noncanonical NF-κB pathway was required for RANKL-induced M cell differentiation in enteroids, as addition of RANKL to enteroids from mice with a null mutation in the mitogen-activated protein kinase kinase kinase 14 (Map3k14) gene encoding NF-κB-inducing kinase failed to induce M cell-associated genes. While the cytokine TNF-α alone had little, if any, effect on expression of M cell-associated genes, addition of TNF-α to RANKL consistently resulted in three- to sixfold higher levels of multiple M cell-associated genes than RANKL alone. One contributing mechanism is the rapid induction by TNF-α of Relb and Nfkb2 (NF-κB subunit 2), genes encoding the two subunits of the noncanonical NF-κB heterodimer. We conclude that endogenous activators of canonical NF-κB signaling present in the gut-associated lymphoid tissue microenvironment, including TNF-α, can play a supportive role in the RANKL-dependent differentiation of M cells in the follicle-associated epithelium.
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Affiliation(s)
- Megan B Wood
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Daniel Rios
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Ifor R Williams
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia
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15
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Hernández C, Dal Monte M, Simó R, Casini G. Neuroprotection as a Therapeutic Target for Diabetic Retinopathy. J Diabetes Res 2016; 2016:9508541. [PMID: 27123463 PMCID: PMC4830713 DOI: 10.1155/2016/9508541] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/29/2016] [Accepted: 03/16/2016] [Indexed: 02/07/2023] Open
Abstract
Diabetic retinopathy (DR) is a multifactorial progressive disease of the retina and a leading cause of vision loss. DR has long been regarded as a vascular disorder, although neuronal death and visual impairment appear before vascular lesions, suggesting an important role played by neurodegeneration in DR and the appropriateness of neuroprotective strategies. Upregulation of vascular endothelial growth factor (VEGF), the main target of current therapies, is likely to be one of the first responses to retinal hyperglycemic stress and VEGF may represent an important survival factor in early phases of DR. Of central importance for clinical trials is the detection of retinal neurodegeneration in the clinical setting, and spectral domain optical coherence tomography seems the most indicated technique. Many substances have been tested in animal studies for their neuroprotective properties and for possible use in humans. Perhaps, the most intriguing perspective is the use of endogenous neuroprotective substances or nutraceuticals. Together, the data point to the central role of neurodegeneration in the pathogenesis of DR and indicate neuroprotection as an effective strategy for treating this disease. However, clinical trials to determine not only the effectiveness and safety but also the compliance of a noninvasive route of drug administration are needed.
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Affiliation(s)
- Cristina Hernández
- CIBERDEM (CIBER de Diabetes y Enfermedades Metabolicas Asociadas) and Diabetes and Metabolism Research Unit, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autonoma de Barcelona, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
- *Cristina Hernández: and
| | - Massimo Dal Monte
- Department of Biology, University of Pisa, Via San Zeno 31, 56127 Pisa, Italy
- Interdepartmental Research Center Nutrafood “Nutraceuticals and Food for Health”, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy
| | - Rafael Simó
- CIBERDEM (CIBER de Diabetes y Enfermedades Metabolicas Asociadas) and Diabetes and Metabolism Research Unit, Vall d'Hebron Institut de Recerca (VHIR), Universitat Autonoma de Barcelona, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain
| | - Giovanni Casini
- Department of Biology, University of Pisa, Via San Zeno 31, 56127 Pisa, Italy
- Interdepartmental Research Center Nutrafood “Nutraceuticals and Food for Health”, University of Pisa, Via del Borghetto 80, 56124 Pisa, Italy
- *Giovanni Casini:
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16
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Lange N, Unger FT, Schöppler M, Pursche K, Juhl H, David KA. Identification and Validation of a Potential Marker of Tissue Quality Using Gene Expression Analysis of Human Colorectal Tissue. PLoS One 2015; 10:e0133987. [PMID: 26222051 PMCID: PMC4519187 DOI: 10.1371/journal.pone.0133987] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 07/05/2015] [Indexed: 11/18/2022] Open
Abstract
Correlative studies have identified numerous biomarkers that are individualizing therapy across many medical specialties, including oncology. Accurate interpretation of these studies requires the collection of tissue samples of sufficient quality. Tissue quality can be measured by changes in levels of gene expression and can be influenced by many factors including pre-analytical conditions, ischemic effects and the surgical collection procedure itself. However, as yet there are no reliable biomarkers of tissue quality at researchers' disposal. The aim of the current study was to identify genes with expression patterns that fluctuated reproducibly in response to typical post-surgical stress (ischemia) in order to identify a specific marker of tissue quality. All tissue samples were obtained from patients with primary colorectal carcinoma (CRC) (N = 40) either via colonoscopy prior to surgery, or by surgical resection. Surgically resected tissue samples were divided into three groups and subjected to cold ischemia for 10, 20 or 45 minutes. Normal colorectal tissue and CRC tissue was analyzed using microarray and quantitative real-time PCR (qPCR). Comparing changes in gene expression between pre- and post-surgical tissue using microarray analysis identified a list of potential tissue quality biomarkers and this list was validated using qPCR. Results revealed that post-operative ischemia significantly alters gene expression in normal and CRC tissue samples. Both microarray analysis and qPCR revealed regulator of G-protein signaling 1 (RGS1) as a potential marker of CRC tissue quality and eukaryotic translation elongation factor 1 alpha 1 (EEF1A1) as a potential reference gene of post-operative tissue quality. Larger studies with additional time points and endpoints will be needed to confirm these results.
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17
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Perrotta C, De Palma C, Clementi E, Cervia D. Hormones and immunity in cancer: are thyroid hormones endocrine players in the microglia/glioma cross-talk? Front Cell Neurosci 2015; 9:236. [PMID: 26157361 PMCID: PMC4477169 DOI: 10.3389/fncel.2015.00236] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 06/11/2015] [Indexed: 11/16/2022] Open
Abstract
Accumulating evidence indicates that the endocrine and immune systems engage in complex cross-talks in which a prominent role is played by thyroid hormones (THs). The increase of resident vs. monocyte recruited macrophages was shown to be an important effector of the TH 3,3′,5′-Triiodo-L-thyronine (T3)-induced protection against inflammation and a key role of T3 in inhibiting the differentiation of peripheral monocytes into macrophages was observed. Herein, we report on the role of T3 as a modulator of microglia, the specialized macrophages of the central nervous system (CNS). Mounting evidence supports a role of microglia and macrophages in the growth and invasion of malignant glioma. In this respect, we unveil the putative involvement of T3 in the microglia/glioma cell communication. Since THs are known to cross the blood-brain barrier, we suggest that T3 not only exerts a direct modulation of brain cancer cell itself but also indirectly promotes glioma growth through a modulation of microglia. Our observations expand available information on the role of TH system in glioma and its microenvironment and highlight the endocrine modulation of microglia as an important target for future therapeutic development of glioma treatments.
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Affiliation(s)
- Cristiana Perrotta
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Unit of Clinical Pharmacology, National Research Council-Institute of Neuroscience, University Hospital "Luigi Sacco", Università di Milano Milano, Italy
| | - Clara De Palma
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Unit of Clinical Pharmacology, National Research Council-Institute of Neuroscience, University Hospital "Luigi Sacco", Università di Milano Milano, Italy
| | - Emilio Clementi
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Unit of Clinical Pharmacology, National Research Council-Institute of Neuroscience, University Hospital "Luigi Sacco", Università di Milano Milano, Italy ; Scientific Institute IRCCS Eugenio Medea Bosisio Parini, Italy
| | - Davide Cervia
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Unit of Clinical Pharmacology, National Research Council-Institute of Neuroscience, University Hospital "Luigi Sacco", Università di Milano Milano, Italy ; Department for Innovation in Biological, Agro-food and Forest Systems (DIBAF), Università della Tuscia, Largo dell'Università snc Viterbo, Italy
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18
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Therapeutic uses of somatostatin and its analogues: Current view and potential applications. Pharmacol Ther 2015; 152:98-110. [PMID: 25956467 DOI: 10.1016/j.pharmthera.2015.05.007] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 04/28/2015] [Indexed: 01/22/2023]
Abstract
Somatostatin is an endogeneous cyclic tetradecapeptide hormone that exerts multiple biological activities via five ubiquitously distributed receptor subtypes. Classified as a broad inhibitory neuropeptide, somatostatin has anti-secretory, anti-proliferative and anti-angiogenic effects. The clinical use of native somatostatin is limited by a very short half-life (1 to 3min) and the broad spectrum of biological responses. Thus stable, receptor-selective agonists have been developed. The majority of these somatostatin therapeutic agonists bind strongly to two of the five receptor subtypes, although recently an agonist of wider affinity has been introduced. Somatostatin agonists are established in the treatment of acromegaly with recently approved indications in the therapy of neuroendocrine tumours. Potential therapeutic uses for somatostatin analogues include diabetic complications like retinopathy, nephropathy and obesity, due to inhibition of IGF-1, VEGF together with insulin secretion and effects upon the renin-angiotensin-aldosterone system. Wider uses in anti-neoplastic therapy may also be considered and recent studies have further revealed anti-inflammatory and anti-nociceptive effects. This review provides a comprehensive, current view of the biological functions of somatostatin and potential therapeutic uses, informed by the wide range of pharmacological advances reported since the last published review in 2004 by P. Dasgupta. The pharmacology of somatostatin receptors is explained, the current uses of somatostatin agonists are discussed, and the potential future of therapeutic applications is explored.
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19
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The β-adrenergic system as a possible new target for pharmacologic treatment of neovascular retinal diseases. Prog Retin Eye Res 2014; 42:103-29. [DOI: 10.1016/j.preteyeres.2014.06.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/30/2014] [Accepted: 06/05/2014] [Indexed: 12/31/2022]
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20
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Hernández C, Simó-Servat O, Simó R. Somatostatin and diabetic retinopathy: current concepts and new therapeutic perspectives. Endocrine 2014; 46:209-14. [PMID: 24627166 DOI: 10.1007/s12020-014-0232-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 02/28/2014] [Indexed: 12/15/2022]
Abstract
Somatostatin (SST) is abundantly produced by the human retina, and the main source is the retinal pigment epithelium (RPE). SST exerts relevant functions in the retina (neuromodulation, angiostatic, and anti-permeability actions) by interacting with SST receptors (SSTR) that are also expressed in the retina. In the diabetic retina, a downregulation of SST production does exist. In this article, we give an overview of the mechanisms by which this deficit of SST participates in the main pathogenic mechanisms involved in diabetic retinopathy (DR): neurodegeneration, neovascularization, and vascular leakage. In view of the relevant SST functions in the retina and the reduction of SST production in the diabetic eye, SST replacement has been proposed as a new target for treatment of DR. This could be implemented by intravitreous injections of SST analogs or gene therapy, but this is an aggressive route for the early stages of DR. Since topical administration of SST has been effective in preventing retinal neurodegeneration in STZ-induced diabetic rats, it seems reasonable to test this new approach in humans. In this regard, the results of the ongoing clinical trial EUROCONDOR will provide useful information. In conclusion, SST is a natural neuroprotective and antiangiogenic factor synthesized by the retina which is downregulated in the diabetic eye and, therefore, its replacement seems a rational approach for treating DR. However, clinical trials will be needed to establish the exact position of targeting SST in the treatment of this disabling complication of diabetes.
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Affiliation(s)
- Cristina Hernández
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Pg. Vall d'Hebron 119-129.08035, Barcelona, Spain
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21
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D'Alessandro A, Cervia D, Catalani E, Gevi F, Zolla L, Casini G. Protective effects of the neuropeptides PACAP, substance P and the somatostatin analogue octreotide in retinal ischemia: a metabolomic analysis. MOLECULAR BIOSYSTEMS 2014; 10:1290-304. [PMID: 24514073 DOI: 10.1039/c3mb70362b] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ischemia is a primary cause of neuronal death in retinal diseases and the somatostatin subtype receptor 2 agonist octreotide (OCT) is known to decrease ischemia-induced retinal cell death. Using a recently optimized ex vivo mouse model of retinal ischemia, we tested the anti-ischemic potential of two additional neuropeptides, pituitary adenylate cyclase activating peptide (PACAP) and substance P (SP), and monitored the major changes occurring at the metabolic level. Metabolomics analyses were performed via fast HPLC online using a microTOF-Q MS instrument, a workflow that is increasingly becoming the gold standard in the field of metabolomics. The metabolomic approach allowed detection of the most significant alterations induced in the retina by ischemia and of the significance of the protective effects exerted by OCT, PACAP or SP. All treatments were shown to reduce ischemia-induced cell death, vascular endothelial growth factor over-expression and glutamate release. The metabolomic analysis showed that OCT and, to a lesser extent, also PACAP or SP, were able to counteract the ischemia-induced oxidative stress and to promote, with various efficacies, (i) decreased accumulation of glutamate and normalization of glutathione homeostasis; (ii) reduced build-up of α-ketoglutarate, which might serve as a substrate for the enhanced biosynthesis of glutamate in response to ischemia; (iii) reduced accumulation of peroxidized lipids and inflammatory mediators; (iv) the normalization of glycolytic fluxes and thus preventing the over-accumulation of lactate or either promoting the down-regulation of the glyoxalate anti-oxidant system; (v) a reduced metabolic shift from glycolysis towards the PPP or either a blockade at the non-oxidative phase of the PPP; and (vi) tuning down of purine metabolism. In addition, OCT seemed to stimulate nitric oxide production. None of the treatments was able to restore ATP production, although ATP reservoirs were partly replenished by OCT, PACAP or SP. These data indicate that, in addition to that of somatostatin, peptidergic systems such as those of PACAP and SP deserve attention in view of peptide-based therapies to treat ischemic retinal disorders.
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Affiliation(s)
- Angelo D'Alessandro
- Dipartimento di Scienze Ecologiche e Biologiche, Università della Tuscia, L.go dell'Università snc, I-01100 Viterbo, Italy.
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22
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Cazzato D, Assi E, Moscheni C, Brunelli S, De Palma C, Cervia D, Perrotta C, Clementi E. Nitric oxide drives embryonic myogenesis in chicken through the upregulation of myogenic differentiation factors. Exp Cell Res 2014; 320:269-80. [DOI: 10.1016/j.yexcr.2013.11.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 11/08/2013] [Accepted: 11/09/2013] [Indexed: 12/22/2022]
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23
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Szabadfi K, Pinter E, Reglodi D, Gabriel R. Neuropeptides, trophic factors, and other substances providing morphofunctional and metabolic protection in experimental models of diabetic retinopathy. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 311:1-121. [PMID: 24952915 DOI: 10.1016/b978-0-12-800179-0.00001-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Vision is the most important sensory modality for many species, including humans. Damage to the retina results in vision loss or even blindness. One of the most serious complications of diabetes, a disease that has seen a worldwide increase in prevalence, is diabetic retinopathy. This condition stems from consequences of pathological metabolism and develops in 75% of patients with type 1 and 50% with type 2 diabetes. The development of novel protective drugs is essential. In this review we provide a description of the disease and conclude that type 1 diabetes and type 2 diabetes lead to the same retinopathy. We evaluate existing experimental models and recent developments in finding effective compounds against this disorder. In our opinion, the best models are the long-term streptozotocin-induced diabetes and Otsuka Long-Evans Tokushima Fatty and spontaneously diabetic Torii rats, while the most promising substances are topically administered somatostatin and pigment epithelium-derived factor analogs, antivasculogenic substances, and systemic antioxidants. Future drug development should focus on these.
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Affiliation(s)
- Krisztina Szabadfi
- Department of Experimental Zoology and Neurobiology, University of Pecs, Pecs, Hungary; Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary.
| | - Erika Pinter
- Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary; Department of Pharmacology and Pharmacotherapy, University of Pecs, Pecs, Hungary
| | - Dora Reglodi
- Department of Anatomy, PTE MTA Lendulet-PACAP Research Team, University of Pecs, Pecs, Hungary
| | - Robert Gabriel
- Department of Experimental Zoology and Neurobiology, University of Pecs, Pecs, Hungary; Janos Szentagothai Research Center, University of Pecs, Pecs, Hungary
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24
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Perrotta C, Buldorini M, Assi E, Cazzato D, De Palma C, Clementi E, Cervia D. The thyroid hormone triiodothyronine controls macrophage maturation and functions: protective role during inflammation. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 184:230-47. [PMID: 24215914 DOI: 10.1016/j.ajpath.2013.10.006] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/17/2013] [Accepted: 10/04/2013] [Indexed: 12/17/2022]
Abstract
The endocrine system participates in regulating macrophage maturation, although little is known about the modulating role of the thyroid hormones. In vitro results demonstrate a negative role of one such hormone, triiodothyronine (T3), in triggering the differentiation of bone marrow-derived monocytes into unpolarized macrophages. T3-induced macrophages displayed a classically activated (M1) signature. A T3-induced M1-priming effect was also observed on polarized macrophages because T3 reverses alternatively activated (M2) activation, whereas it enhances that of M1 cells. In vivo, circulating T3 increased the content of the resident macrophages in the peritoneal cavity, whereas it reduced the content of the recruited monocyte-derived cells. Of interest, T3 significantly protected mice against endotoxemia induced by lipopolysaccharide i.p. injection; in these damaged animals, decreased T3 levels increased the recruited (potentially damaging) cells, whereas restoring T3 levels decreased recruited and increased resident (potentially beneficial) cells. These data suggest that the anti-inflammatory effect of T3 is coupled to the modulation of peritoneal macrophage content, in a context not fully explained by the M1/M2 framework. Thyroid hormone receptor expression analysis and the use of different thyroid hormone receptor antagonists suggest thyroid hormone receptor β1 as the major player mediating T3 effects on macrophages. The novel homeostatic link between thyroid hormones and the pathophysiological role of macrophages opens new perspectives on the interactions between the endocrine and immune systems.
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Affiliation(s)
- Cristiana Perrotta
- Unit of Clinical Pharmacology, Department of Biomedical and Clinical Sciences, National Research Council Institute of Neuroscience, Luigi Sacco University Hospital, University of Milan, Milan, Italy
| | | | - Emma Assi
- Unit of Clinical Pharmacology, Department of Biomedical and Clinical Sciences, National Research Council Institute of Neuroscience, Luigi Sacco University Hospital, University of Milan, Milan, Italy
| | | | - Clara De Palma
- Unit of Clinical Pharmacology, Department of Biomedical and Clinical Sciences, National Research Council Institute of Neuroscience, Luigi Sacco University Hospital, University of Milan, Milan, Italy
| | - Emilio Clementi
- Unit of Clinical Pharmacology, Department of Biomedical and Clinical Sciences, National Research Council Institute of Neuroscience, Luigi Sacco University Hospital, University of Milan, Milan, Italy; E. Medea Scientific Institute, Bosisio Parini, Italy.
| | - Davide Cervia
- Unit of Clinical Pharmacology, Department of Biomedical and Clinical Sciences, National Research Council Institute of Neuroscience, Luigi Sacco University Hospital, University of Milan, Milan, Italy; Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, Viterbo, Italy.
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25
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Gábriel R. Neuropeptides and diabetic retinopathy. Br J Clin Pharmacol 2013; 75:1189-201. [PMID: 23043302 DOI: 10.1111/bcp.12003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 10/02/2012] [Indexed: 12/21/2022] Open
Abstract
Diabetic retinopathy, a common complication of diabetes, develops in 75% of patients with type 1 and 50% of patients with type 2 diabetes, progressing to legal blindness in about 5%. In the recent years, considerable efforts have been put into finding treatments for this condition. It has been discovered that peptidergic mechanisms (neuropeptides and their analogues, activating a diverse array of signal transduction pathways through their multiple receptors) are potentially important for consideration in drug development strategies. A considerable amount of knowledge has been accumulated over the last three decades on human retinal neuropeptides and those elements in the pathomechanisms of diabetic retinopathy which might be related to peptidergic signal transduction. Here, human retinal neuropeptides and their receptors are reviewed, along with the theories relevant to the pathogenesis of diabetic retinopathy both in humans and in experimental models. By collating this information, the curative potential of certain neupeptides and their analogues/antagonists can also be discussed, along with the existing clinical treatments of diabetic retinopathy. The most promising peptidergic pathways for which treatment strategies may be developed at present are stimulation of the somatostatin-related pathway and the pituitary adenylyl cyclase-activating polypeptide-related pathway or inhibition of angiotensinergic mechanisms. These approaches may result in the inhibition of vascular endothelial growth factor production and neuronal apoptosis; therefore, both the optical quality of the image and the processing capability of the neural circuit in the retina may be saved.
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Affiliation(s)
- Robert Gábriel
- Department of Experimental Zoology and Neurobiology, University of Pécs, H-7621, Pécs, Hungary.
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26
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Cervia D, Casini G. The Neuropeptide Systems and their Potential Role in the Treatment of Mammalian Retinal Ischemia: A Developing Story. Curr Neuropharmacol 2013; 11:95-101. [PMID: 23814541 PMCID: PMC3580795 DOI: 10.2174/157015913804999423] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 07/30/2012] [Accepted: 08/09/2012] [Indexed: 12/23/2022] Open
Abstract
The multiplicity of peptidergic receptors and of the transduction pathways they activate offers the possibility of important advances in the development of specific drugs for clinical treatment of central nervous system disorders. Among them, retinal ischemia is a common clinical entity and, due to relatively ineffective treatment, remains a common cause of visual impairment and blindness. Ischemia is a primary cause of neuronal death, and it can be considered as a sort of final common pathway in retinal diseases leading to irreversible morphological damage and vision loss. Neuropeptides and their receptors are widely expressed in mammalian retinas, where they exert multifaceted functions both during development and in the mature animal. In particular, in recent years somatostatin and pituitary adenylate cyclase activating peptide have been reported to be highly protective against retinal cell death caused by ischemia, while data on opioid peptides, angiotensin II, and other peptides have also been published. This review provides a rationale for harnessing the peptidergic receptors as a potential target against retinal neuronal damages which occur during ischemic retinopathies.
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Affiliation(s)
- D Cervia
- Department for Innovation in Biological, Agro-food and Forest systems (DIBAF), University of Tuscia, Viterbo, Italy
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27
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Grigoriev VV, Petrova LN, Gabrelian AV, Zamoyski VL, Serkova TP, Bachurin SO. Effect of somatostatin on presynaptic and postsynaptic glutamate receptors and postsynaptic GABA receptors in the neurons of rat brain. Bull Exp Biol Med 2013; 154:10-2. [PMID: 23330078 DOI: 10.1007/s10517-012-1862-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We studied the effect of somatostatin on presinaptic NMDA receptors and postsinaptic GABA, NMDA, and AMPA receptors in rat brain. It was shown that somatostatin inhibits NMDA-induced (45)Ca(2+) uptake into synaptosomes isolated from rat brain cortex (IC50=2.8×10(-11) M). Somatostatin potentiates AMPA receptors and inhibits hippocampal NMDA receptors in the entire range of examined concentrations (10(-14)-10(-7) M); it also potentiates or inhibits GABA receptor currents in a concentration-dependent manner. Our results suggest that somatostatin modulates the function of ionotropic glutamate and GABA receptors and is involved in cognitive and neurodegenerative processes in the mammalian brain.
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Affiliation(s)
- V V Grigoriev
- Laboratory of Neurochemistry, Institute of Physiologically Active Substances, Russian Academy Sciences, Chernogolovka, Moscow Region, Russia.
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28
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Afanador L, Mexhitaj I, Diaz C, Ordonez D, Baker L, Angulo JA. The role of the neuropeptide somatostatin on methamphetamine and glutamate-induced neurotoxicity in the striatum of mice. Brain Res 2013; 1510:38-47. [PMID: 23524190 DOI: 10.1016/j.brainres.2013.03.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 01/23/2013] [Accepted: 03/06/2013] [Indexed: 12/12/2022]
Abstract
A large body of evidence shows that methamphetamine (METH) causes sustained damage to the brain in animal models and human METH users. In chronic users there are indications of cognitive and motor deficits. Striatal neuropeptides are in a position to modulate the neurochemical effects of METH and consequently striatal neural damage. Somatostatin (SST) is an intrinsic striatal neuropeptide that has been shown to inhibit glutamate transmission; glutamate is integral to METH toxicity and contributes to nitric oxide (NO) synthesis. We hypothesize that SST will protect from METH by inhibition of NO synthesis and thus reducing oxidative stress. To this end, the SST analogue octreotide (OCT) was microinjected into the striatum prior to a systemic injection of METH (30mg/kg). We then assessed 3-nitrotyrosine (3-NT), an indirect index of NO production, tyrosine hydroxylase (TH) protein levels (dopamine terminal marker) and Fluoro-Jade C positive cells (degenerating cells). The SST agonist OCT dose dependently attenuated the METH-induced accumulation of striatal 3-NT. Moreover, pretreatment with OCT effectively mitigated cell death but failed to protect dopamine terminals. Next we co-infused OCT and NMDA and measured 3-NT and Fluoro-Jade C staining. Treatment with OCT had no effect on these parameters. The data demonstrate that SST attenuates the METH-induced production of NO protecting the striatum from the METH-induced cell loss. However, SST failed to prevent the toxicity of the dopamine terminals suggesting that pre- and post-synaptic striatal damage occur via independent mechanisms.
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Affiliation(s)
- Lauriaselle Afanador
- Department of Biological Sciences, Hunter College of the City University of New York, 695 Park Avenue, NY 10065, USA
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Cervia D, Catalani E, Belardinelli MC, Perrotta C, Picchietti S, Alimenti C, Casini G, Fausto AM, Vallesi A. The protein pheromone Er-1 of the ciliate Euplotes raikovi stimulates human T-cell activity: Involvement of interleukin-2 system. Exp Cell Res 2013; 319:56-67. [DOI: 10.1016/j.yexcr.2012.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 10/12/2012] [Accepted: 10/13/2012] [Indexed: 12/24/2022]
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Kokona D, Mastrodimou N, Pediaditakis I, Charalampopoulos I, Schmid HA, Thermos K. Pasireotide (SOM230) protects the retina in animal models of ischemia induced retinopathies. Exp Eye Res 2012; 103:90-8. [PMID: 22960304 DOI: 10.1016/j.exer.2012.08.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 07/31/2012] [Accepted: 08/11/2012] [Indexed: 11/15/2022]
Abstract
The neuropeptide somatostatin and selective analogs for the sst(2/5) receptor subtypes provided neuroprotection against retinal chemical ischemia ex vivo and AMPA [(RS)-α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid hydrobromide] induced retinal toxicity in vivo, when employed in micromolar concentrations (Mastrodimou et al., 2005; Kiagiadaki and Thermos, 2008). The aim of the present study was to investigate the neuroprotective properties of a new metabolically stable agent pasireotide (SOM230) in the above mentioned retinal models of ischemia. Adult Sprague Dawley (250-350 g) rats were employed. For the ex vivo experiments, retinal eye cups were incubated with PBS or the chemical ischemia mixture [iodoacetic acid (5 mM)/sodium cyanide (25 mM)] in the absence or presence of SOM230 (10(-7)-10(-5) M) alone or in the presence of the sst(2) antagonist CYN-154806 (10(-7) or 10(-5) M). In the in vivo model, the animals received intravitreally: PBS (50 mM), AMPA (42 nmol/eye) or AMPA (42 nmol) in combination with SOM230 (10(-7)-10(-5) M). Immunohistochemistry studies using antisera against bNOS, a marker for brain/neuronal NOS containing amacrine cells, protein kinase C (PKC) a marker for rod bipolar cells, and TUNEL studies in conjunction with FACS analysis were employed to examine retinal cell loss and protection. Chemical ischemia led to a loss of bNOS and PKC immunoreactivity which was reversed by SOM230. Partial and full protection of bNOS and PKC immunoreactive neurons, respectively, was observed even at the low concentration of 10(-7) M. The neuroprotective actions of SOM230 (10(-7) or 10(-5) M) were reversed by CYN-154806 (10(-7) or 10(-5) M, respectively). Similarly, SOM230 (10(-7), 10(-6), 10(-5) M) provided neuroprotection in the in vivo model. The dose of 10(-7) M prevented the loss of the bNOS cells and provided almost full protection. These data were substantiated by TUNEL staining and fluorescence-activated cell sorting (FACS) analysis. SOM230 appears very efficacious in its neuroprotective properties in both models of retinal ischemia affording neuroprotection at the concentration or dose of 100 nM. These data suggest that SOM230 might represent a useful pharmacological compound for the treatment of retinal disease.
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Affiliation(s)
- D Kokona
- Laboratory of Pharmacology, Department of Basic Sciences, Faculty of Medicine, University of Crete, Heraklion 71110, Crete, Greece
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Abstract
Retinal ischemia is a common clinical entity and, due to relatively ineffective treatment, remains a common cause of visual impairment and blindness. Generally, ischemic syndromes are initially characterized by low homeostatic responses which, with time, induce injury to the tissue due to cell loss by apoptosis. In this respect, retinal ischemia is a primary cause of neuronal death. It can be considered as a sort of final common pathway in retinal diseases and results in irreversible morphological and functional changes. This review summarizes the recent knowledge on the effects of ischemia in retinal tissue and points out experimental strategies/models performed to gain better comprehension of retinal ischemia diseases. In particular, the nature of the mechanisms leading to neuronal damage (i.e., excess of glutamate release, oxidative stress and inflammation) will be outlined as well as the potential and most intriguing retinoprotective approaches and the possible therapeutic use of naturally occurring molecules such as neuropeptides. There is a general agreement that a better understanding of the fundamental pathophysiology of retinal ischemia will lead to better management and improved clinical outcome. In this respect, to contrast this pathological state, specific pharmacological strategies need to be developed aimed at the many putative cascades generated during ischemia.
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Protective role of somatostatin receptor 2 against retinal degeneration in response to hypoxia. Naunyn Schmiedebergs Arch Pharmacol 2012; 385:481-94. [DOI: 10.1007/s00210-012-0735-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 01/25/2012] [Indexed: 12/20/2022]
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Cervia D, Catalani E, Dal Monte M, Casini G. Vascular endothelial growth factor in the ischemic retina and its regulation by somatostatin. J Neurochem 2012; 120:818-29. [DOI: 10.1111/j.1471-4159.2011.07622.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Waterson RE, Thompson CG, Mabe NW, Kaur K, Talbot JN, Neubig RR, Rorabaugh BR. Gα(i2)-mediated protection from ischaemic injury is modulated by endogenous RGS proteins in the mouse heart. Cardiovasc Res 2011; 91:45-52. [PMID: 21349876 PMCID: PMC3112020 DOI: 10.1093/cvr/cvr054] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Revised: 01/31/2011] [Accepted: 02/18/2011] [Indexed: 01/01/2023] Open
Abstract
AIMS Regulator of G protein signalling (RGS) proteins act as molecular 'off switches' that terminate G protein signalling by catalyzing the hydrolysis of Gα-bound GTP to GDP. Many different Gα(i)-coupled receptors have been implicated in the cardioprotective effects of ischaemic preconditioning. However, the role of RGS proteins in modulating cardioprotection has not been previously investigated. We used mice that were homozygous (GS/GS) or heterozygous (GS/+) for a mutation in Gα(i2) rendering it RGS-insensitive (G184S) to determine whether interactions between endogenous RGS proteins and Gα(i2) modulate Gα(i)-mediated protection from ischaemic injury. METHODS AND RESULTS Langendorff-perfused mouse hearts were subjected to 30 min global ischaemia and 2 h reperfusion. Infarcts in GS/GS (14.5% of area at risk) and GS/+ (22.6% of AAR) hearts were significantly smaller than those of +/+ hearts (37.2% of AAR) and recovery of contractile function was significantly enhanced in GS/GS and GS/+ hearts compared with +/+ hearts. The cardioprotective phenotype was not reversed by wortmannin or U0126 but was reversed by 5-hydroxydecanoic acid and HMR 1098, indicating that RGS-insensitive Gα(i2) protects the heart through a mechanism that requires functional ATP-dependent potassium channels but does not require acute activation of extracellular-regulated kinase or Akt signalling pathways. CONCLUSIONS This is the first study to demonstrate that Gα(i2)-mediated cardioprotection is suppressed by RGS proteins. These data suggest that RGS proteins may provide novel therapeutic targets to protect the heart from ischaemic injury.
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Affiliation(s)
- Rachael E. Waterson
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, 525 South Main Street, Ada, OH 45810, USA
| | - Corbin G. Thompson
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, 525 South Main Street, Ada, OH 45810, USA
| | - Nathaniel W. Mabe
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, 525 South Main Street, Ada, OH 45810, USA
| | - Kuljeet Kaur
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jeffery N. Talbot
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, 525 South Main Street, Ada, OH 45810, USA
| | - Richard R. Neubig
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Boyd R. Rorabaugh
- Department of Pharmaceutical and Biomedical Sciences, Raabe College of Pharmacy, Ohio Northern University, 525 South Main Street, Ada, OH 45810, USA
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Cammalleri M, Martini D, Ristori C, Timperio AM, Bagnoli P. Vascular endothelial growth factor up-regulation in the mouse hippocampus and its role in the control of epileptiform activity. Eur J Neurosci 2010; 33:482-98. [DOI: 10.1111/j.1460-9568.2010.07529.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Cammalleri M, Martini D, Timperio AM, Bagnoli P. Functional effects of somatostatin receptor 1 activation on synaptic transmission in the mouse hippocampus. J Neurochem 2009; 111:1466-77. [PMID: 19811607 DOI: 10.1111/j.1471-4159.2009.06423.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Somatostatin-14 (SRIF) co-localizes with GABA in the hippocampus and regulates neuronal excitability. A role of SRIF in the control of hippocampal activity has been proposed, although the exact contribution of each SRIF receptor (sst(1)-sst(5)) in mediating SRIF action requires some clarification. We used hippocampal slices of wild-type and sst(1) knockout (KO) mice and selective pharmacological tools to provide conclusive evidence for a role of sst(1) in mediating SRIF inhibition of synaptic transmission. With single- and double-label immunohistochemistry, we determined the distribution of sst(1) in hippocampal slices and we quantified sst(1) colocalization with SRIF. With electrophysiology, we found that sst(1) activation with CH-275 inhibited both the NMDA- and the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-mediated responses. Results from sst(1) KO slices confirmed the specificity of CH-275 effects; sst(1) activation did not affect the inhibitory transmission which was in contrast increased by sst(4) activation with L-803,087 in both wild-type and sst(1) KO slices. The AMPA-mediated responses were increased by L-803,087. Functional interaction between sst(1) and sst(4) is suggested by the finding that their combined activation prevented the CH-275-induced inhibition of AMPA transmission. The involvement of pre-synaptic mechanisms in mediating inhibitory effects of sst(1) on excitatory transmission was demonstrated by the finding that CH-275 (i) increased the paired-pulse facilitation ratio, (ii) did not influence the AMPA depolarization in the presence of tetrodotoxin, and (iii) inhibited glutamate release induced by epileptiform treatment. We conclude that SRIF control of excitatory transmission through an action at sst(1) may represent an important contribution to the regulation of hippocampal activity.
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Affiliation(s)
- Maurizio Cammalleri
- Department of Biology, Unit of General Physiology, University of Pisa, Pisa, Italy
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Jian K, Barhoumi R, Ko ML, Ko GYP. Inhibitory effect of somatostatin-14 on L-type voltage-gated calcium channels in cultured cone photoreceptors requires intracellular calcium. J Neurophysiol 2009; 102:1801-10. [PMID: 19605612 DOI: 10.1152/jn.00354.2009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The inhibitory effects of somatostatin have been well documented for many physiological processes. The action of somatostatin is through G-protein-coupled receptor-mediated second-messenger signaling, which in turn affects other downstream targets including ion channels. In the retina, somatostatin is released from a specific class of amacrine cells. Here we report that there was a circadian phase-dependent effect of somatostatin-14 (SS14) on the L-type voltage-gated calcium channels (L-VGCCs) in cultured chicken cone photoreceptors, and our study reveals that this process is dependent on intracellular calcium stores. Application of 500 nM SS14 for 2 h caused a decrease in L-VGCC currents only during the subjective night but not the subjective day. We then explored the cellular mechanisms underlying the circadian phase-dependent effect of SS14. The inhibitory effect of SS14 on L-VGCCs was mediated through the pertussis-toxin-sensitive G-protein-dependent somatostatin receptor 2 (sst2). Activation of sst2 by SS14 further activated downstream signaling involving phospholipase C and intracellular calcium stores. Mobilization of intracellular Ca2+ was required for somatostatin induced inhibition of photoreceptor L-VGCCs, suggesting that somatostatin plays an important role in the modulation of photoreceptor physiology.
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Affiliation(s)
- Kuihuan Jian
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, 4458 TAMU, College Station, TX 77843-4458, USA
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