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Kim YJ, Lee MK, Kim U, Lee JM, Hsieh YS, Seol GH. Lavandula angustifolia Mill. inhibits high glucose and nicotine-induced Ca 2+ influx in microglia and neuron-like cells via two distinct mechanisms. Biomed Pharmacother 2024; 177:117062. [PMID: 38971009 DOI: 10.1016/j.biopha.2024.117062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 06/18/2024] [Accepted: 06/27/2024] [Indexed: 07/08/2024] Open
Abstract
Smoking remains a significant health problem in patients with type 2 diabetes mellitus. This study compared intracellular Ca2+ ([Ca2+]i) in microglia, neurons, and astrocytes in the presence of high glucose (HG) and nicotine and evaluated the effects of Lavandula angustifolia Mill. essential oil (LEO) on this process. [Ca2+]i concentrations were measured by monitoring the fluorescence of Fura-2 acetoxymethyl ester. Treatment with HG and nicotine significantly increased [Ca2+]i in both microglia and neurons through Ca2+ influx from extracellular sources. This increased Ca2+ influx in microglia, however, was significantly reduced by LEO, an effect partially inhibited by the Na+/Ca2+ exchanger (NCX) inhibitor Ni2+. Ca2+ influx in neuron-like cells pretreated with HG plus nicotine was also significantly decreased by LEO, an effect partially inhibited by the L-type Ca2+ channel blocker nifedipine and the T-type Ca2+ channel blocker mibefradil. LEO or a two-fold increase in the applied number of astrocytes attenuated Ca2+ influx caused by high glucose and nicotine in the mixed cells of the microglia, neuron-like cells and astrocytes. These findings suggest that LEO can regulate HG and nicotine-induced Ca2+ influx into microglia and neurons through two distinct mechanisms.
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Affiliation(s)
- Yoo Jin Kim
- Department of Basic Nursing Science, College of Nursing, Korea University, Seoul, Republic of Korea; BK21 FOUR Program of Transdisciplinary Major in Learning Health Systems, Graduate School, Korea University, Seoul, Republic of Korea
| | - Min Kyung Lee
- Department of Basic Nursing Science, College of Nursing, Korea University, Seoul, Republic of Korea
| | - Uihwan Kim
- Department of Basic Nursing Science, College of Nursing, Korea University, Seoul, Republic of Korea; BK21 FOUR Program of Transdisciplinary Major in Learning Health Systems, Graduate School, Korea University, Seoul, Republic of Korea
| | - Jeong-Min Lee
- Department KT&G Central Research Institute, Daejeon, Republic of Korea
| | - Yu Shan Hsieh
- Department of Nursing, School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan
| | - Geun Hee Seol
- Department of Basic Nursing Science, College of Nursing, Korea University, Seoul, Republic of Korea; BK21 FOUR Program of Transdisciplinary Major in Learning Health Systems, Graduate School, Korea University, Seoul, Republic of Korea.
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Lepiarz-Raba I, Gbadamosi I, Florea R, Paolicelli RC, Jawaid A. Metabolic regulation of microglial phagocytosis: Implications for Alzheimer's disease therapeutics. Transl Neurodegener 2023; 12:48. [PMID: 37908010 PMCID: PMC10617244 DOI: 10.1186/s40035-023-00382-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 10/23/2023] [Indexed: 11/02/2023] Open
Abstract
Microglia, the resident immune cells of the brain, are increasingly implicated in the regulation of brain health and disease. Microglia perform multiple functions in the central nervous system, including surveillance, phagocytosis and release of a variety of soluble factors. Importantly, a majority of their functions are closely related to changes in their metabolism. This natural inter-dependency between core microglial properties and metabolism offers a unique opportunity to modulate microglial activities via nutritional or metabolic interventions. In this review, we examine the existing scientific literature to synthesize the hypothesis that microglial phagocytosis of amyloid beta (Aβ) aggregates in Alzheimer's disease (AD) can be selectively enhanced via metabolic interventions. We first review the basics of microglial metabolism and the effects of common metabolites, such as glucose, lipids, ketone bodies, glutamine, pyruvate and lactate, on microglial inflammatory and phagocytic properties. Next, we examine the evidence for dysregulation of microglial metabolism in AD. This is followed by a review of in vivo studies on metabolic manipulation of microglial functions to ascertain their therapeutic potential in AD. Finally, we discuss the effects of metabolic factors on microglial phagocytosis of healthy synapses, a pathological process that also contributes to the progression of AD. We conclude by enlisting the current challenges that need to be addressed before strategies to harness microglial phagocytosis to clear pathological protein deposits in AD and other neurodegenerative disorders can be widely adopted.
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Affiliation(s)
- Izabela Lepiarz-Raba
- Laboratory for Translational Research in Neuropsychiatric Disorders (TREND), BRAINCITY: Center of Excellence for Neural Plasticity and Brain Disorders, Nencki Institute of Experimental Biology, Warsaw, Poland.
| | - Ismail Gbadamosi
- Laboratory for Translational Research in Neuropsychiatric Disorders (TREND), BRAINCITY: Center of Excellence for Neural Plasticity and Brain Disorders, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Roberta Florea
- Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | | | - Ali Jawaid
- Laboratory for Translational Research in Neuropsychiatric Disorders (TREND), BRAINCITY: Center of Excellence for Neural Plasticity and Brain Disorders, Nencki Institute of Experimental Biology, Warsaw, Poland.
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Padovani-Claudio DA, Ramos CJ, Capozzi ME, Penn JS. Elucidating glial responses to products of diabetes-associated systemic dyshomeostasis. Prog Retin Eye Res 2023; 94:101151. [PMID: 37028118 PMCID: PMC10683564 DOI: 10.1016/j.preteyeres.2022.101151] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 04/08/2023]
Abstract
Diabetic retinopathy (DR) is a leading cause of blindness in working age adults. DR has non-proliferative stages, characterized in part by retinal neuroinflammation and ischemia, and proliferative stages, characterized by retinal angiogenesis. Several systemic factors, including poor glycemic control, hypertension, and hyperlipidemia, increase the risk of DR progression to vision-threatening stages. Identification of cellular or molecular targets in early DR events could allow more prompt interventions pre-empting DR progression to vision-threatening stages. Glia mediate homeostasis and repair. They contribute to immune surveillance and defense, cytokine and growth factor production and secretion, ion and neurotransmitter balance, neuroprotection, and, potentially, regeneration. Therefore, it is likely that glia orchestrate events throughout the development and progression of retinopathy. Understanding glial responses to products of diabetes-associated systemic dyshomeostasis may reveal novel insights into the pathophysiology of DR and guide the development of novel therapies for this potentially blinding condition. In this article, first, we review normal glial functions and their putative roles in the development of DR. We then describe glial transcriptome alterations in response to systemic circulating factors that are upregulated in patients with diabetes and diabetes-related comorbidities; namely glucose in hyperglycemia, angiotensin II in hypertension, and the free fatty acid palmitic acid in hyperlipidemia. Finally, we discuss potential benefits and challenges associated with studying glia as targets of DR therapeutic interventions. In vitro stimulation of glia with glucose, angiotensin II and palmitic acid suggests that: 1) astrocytes may be more responsive than other glia to these products of systemic dyshomeostasis; 2) the effects of hyperglycemia on glia are likely to be largely osmotic; 3) fatty acid accumulation may compound DR pathophysiology by promoting predominantly proinflammatory and proangiogenic transcriptional alterations of macro and microglia; and 4) cell-targeted therapies may offer safer and more effective avenues for DR treatment as they may circumvent the complication of pleiotropism in retinal cell responses. Although several molecules previously implicated in DR pathophysiology are validated in this review, some less explored molecules emerge as potential therapeutic targets. Whereas much is known regarding glial cell activation, future studies characterizing the role of glia in DR and how their activation is regulated and sustained (independently or as part of retinal cell networks) may help elucidate mechanisms of DR pathogenesis and identify novel drug targets for this blinding disease.
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Affiliation(s)
- Dolly Ann Padovani-Claudio
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, B3321A Medical Center North, 1161 21st Avenue South, Nashville, TN, 37232-0011, USA.
| | - Carla J Ramos
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, AA1324 Medical Center North, 1161 21st Avenue South, Nashville, TN, 37232-0011, USA.
| | - Megan E Capozzi
- Duke Molecular Physiology Institute, Duke University School of Medicine, 300 North Duke Street, Durham, NC, 27701, USA.
| | - John S Penn
- Department of Ophthalmology and Visual Sciences, Vanderbilt University School of Medicine, B3307 Medical Center North, 1161 21st Avenue South, Nashville, TN, 37232-0011, USA.
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Vargas-Soria M, García-Alloza M, Corraliza-Gómez M. Effects of diabetes on microglial physiology: a systematic review of in vitro, preclinical and clinical studies. J Neuroinflammation 2023; 20:57. [PMID: 36869375 PMCID: PMC9983227 DOI: 10.1186/s12974-023-02740-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/16/2023] [Indexed: 03/05/2023] Open
Abstract
Diabetes mellitus is a heterogeneous chronic metabolic disorder characterized by the presence of hyperglycemia, commonly preceded by a prediabetic state. The excess of blood glucose can damage multiple organs, including the brain. In fact, cognitive decline and dementia are increasingly being recognized as important comorbidities of diabetes. Despite the largely consistent link between diabetes and dementia, the underlying causes of neurodegeneration in diabetic patients remain to be elucidated. A common factor for almost all neurological disorders is neuroinflammation, a complex inflammatory process in the central nervous system for the most part orchestrated by microglial cells, the main representatives of the immune system in the brain. In this context, our research question aimed to understand how diabetes affects brain and/or retinal microglia physiology. We conducted a systematic search in PubMed and Web of Science to identify research items addressing the effects of diabetes on microglial phenotypic modulation, including critical neuroinflammatory mediators and their pathways. The literature search yielded 1327 records, including 18 patents. Based on the title and abstracts, 830 papers were screened from which 250 primary research papers met the eligibility criteria (original research articles with patients or with a strict diabetes model without comorbidities, that included direct data about microglia in the brain or retina), and 17 additional research papers were included through forward and backward citations, resulting in a total of 267 primary research articles included in the scoping systematic review. We reviewed all primary publications investigating the effects of diabetes and/or its main pathophysiological traits on microglia, including in vitro studies, preclinical models of diabetes and clinical studies on diabetic patients. Although a strict classification of microglia remains elusive given their capacity to adapt to the environment and their morphological, ultrastructural and molecular dynamism, diabetes modulates microglial phenotypic states, triggering specific responses that include upregulation of activity markers (such as Iba1, CD11b, CD68, MHC-II and F4/80), morphological shift to amoeboid shape, secretion of a wide variety of cytokines and chemokines, metabolic reprogramming and generalized increase of oxidative stress. Pathways commonly activated by diabetes-related conditions include NF-κB, NLRP3 inflammasome, fractalkine/CX3CR1, MAPKs, AGEs/RAGE and Akt/mTOR. Altogether, the detailed portrait of complex interactions between diabetes and microglia physiology presented here can be regarded as an important starting point for future research focused on the microglia-metabolism interface.
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Affiliation(s)
- María Vargas-Soria
- Division of Physiology, School of Medicine, Universidad de Cadiz, Cadiz, Spain.,Instituto de Investigacion e Innovacion en Ciencias Biomedicas de la Provincia de Cadiz (INIBICA), Cadiz, Spain
| | - Mónica García-Alloza
- Division of Physiology, School of Medicine, Universidad de Cadiz, Cadiz, Spain.,Instituto de Investigacion e Innovacion en Ciencias Biomedicas de la Provincia de Cadiz (INIBICA), Cadiz, Spain
| | - Miriam Corraliza-Gómez
- Division of Physiology, School of Medicine, Universidad de Cadiz, Cadiz, Spain. .,Instituto de Investigacion e Innovacion en Ciencias Biomedicas de la Provincia de Cadiz (INIBICA), Cadiz, Spain.
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Contribution of hyperglycemia-induced changes in microglia to Alzheimer's disease pathology. Pharmacol Rep 2022; 74:832-846. [PMID: 36042131 DOI: 10.1007/s43440-022-00405-9] [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: 05/30/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 10/14/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative condition characterized by cognitive and functional impairments. The investigation of AD has focused on the formation of senile plaques, composed mainly by amyloid β (Aβ) peptide, and neurofibrillary tangles (NFTs) in the brain. Senile plaques and NFTs cause the excessive recruitment and activation of microglia, thus generating neuroinflammation and neuronal damage. Among the risk factors for the development of AD, diabetes has increasingly attracted attention. Hyperglycemia, the fundamental characteristic of diabetes, is involved in several mechanisms that give rise to microglial overactivation, resulting in neuronal damage and cognitive impairment. Indeed, various studies have identified the correlation between diabetes and AD. The aim of this review is to describe various mechanisms of the hyperglycemia-induced overactivation of microglia, which leads to neuroinflammation and neuronal damage and consequently contributes to the pathology of AD. The disruption of the regulation of microglial activity by hyperglycemia occurs through many mechanisms, including a greater production of reactive oxygen species (ROS) and glycation end products (AGEs), and a decrease in the elimination of Aβ. The future direction of research on the relation between hyperglycemia and AD is addressed, such as the importance of determining whether the hyperglycemia-induced harmful effects on microglial activity can be reversed or attenuated if blood glucose returns to a normal level.
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Dedert C, Mishra V, Aggarwal G, Nguyen AD, Xu F. Progranulin Preserves Autophagy Flux and Mitochondrial Function in Rat Cortical Neurons Under High Glucose Stress. Front Cell Neurosci 2022; 16:874258. [PMID: 35880011 PMCID: PMC9308004 DOI: 10.3389/fncel.2022.874258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 06/17/2022] [Indexed: 12/02/2022] Open
Abstract
Chronic hyperglycemia in type II diabetes results in impaired autophagy function, accumulation of protein aggregates, and neurodegeneration. However, little is known about how to preserve autophagy function under hyperglycemic conditions. In this study, we tested whether progranulin (PGRN), a neurotrophic factor required for proper lysosome function, can restore autophagy function in neurons under high-glucose stress. We cultured primary cortical neurons derived from E18 Sprague-Dawley rat pups to maturity at 10 days in vitro (DIV) before incubation in high glucose medium and PGRN for 24-72 h before testing for autophagy flux, protein turnover, and mitochondrial function. We found that although PGRN by itself did not upregulate autophagy, it attenuated impairments in autophagy seen under high-glucose conditions. Additionally, buildup of the autophagosome marker light chain 3B (LC3B) and lysosome marker lysosome-associated membrane protein 2A (LAMP2A) changed in both neurons and astrocytes, indicating a possible role for glia in autophagy flux. Protein turnover, assessed by remaining advanced glycation end-product levels after a 6-h incubation, was preserved with PGRN treatment. Mitochondrial activity differed by complex, although PGRN appeared to increase overall activity in high glucose. We also found that activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and glycogen synthase kinase 3β (GSK3β), kinases implicated in autophagy function, increased with PGRN treatment under stress. Together, our data suggest that PGRN prevents hyperglycemia-induced decreases in autophagy by increasing autophagy flux via increased ERK1/2 kinase activity in primary rat cortical neurons.
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Affiliation(s)
- Cass Dedert
- Department of Biology, College of Arts and Sciences, Saint Louis University, St. Louis, MO, United States
- Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University, St. Louis, MO, United States
| | - Vandana Mishra
- Department of Biology, College of Arts and Sciences, Saint Louis University, St. Louis, MO, United States
| | - Geetika Aggarwal
- Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University, St. Louis, MO, United States
- Department of Pharmacology and Physiology, School of Medicine, Saint Louis University, St. Louis, MO, United States
- Department of Internal Medicine, Division of Geriatric Medicine, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Andrew D. Nguyen
- Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University, St. Louis, MO, United States
- Department of Pharmacology and Physiology, School of Medicine, Saint Louis University, St. Louis, MO, United States
- Department of Internal Medicine, Division of Geriatric Medicine, School of Medicine, Saint Louis University, St. Louis, MO, United States
| | - Fenglian Xu
- Department of Biology, College of Arts and Sciences, Saint Louis University, St. Louis, MO, United States
- Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University, St. Louis, MO, United States
- Department of Pharmacology and Physiology, School of Medicine, Saint Louis University, St. Louis, MO, United States
- *Correspondence: Fenglian Xu,
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7
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Neuroprotection of dihydrotestosterone via suppression of the toll-like receptor 4/nuclear factor-kappa B signaling pathway in high glucose-induced BV-2 microglia inflammatory responses. Neuroreport 2021; 31:139-147. [PMID: 31876682 DOI: 10.1097/wnr.0000000000001385] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Hyperglycemia is considered to induce neuronal apoptosis via activating microglia inflammatory responses, thus involving in the development and progression of diabetic encephalopathy and neurodegenerative disorders. Increasing evidences suggest that androgen exerts neuroprotective functions including antiapoptosis, anti-inflammation and antioxidative stress. In this study, we investigate the anti-inflammatory role of dihydrotestosterone (DHT) in high glucose (HG)-induced neuroinflammatory response in BV-2 microglia. Our results revealed that DHT significantly inhibited HG-induced production of nitric oxide and prostaglandin E2 through suppressing the expression of corresponding regulatory enzymes - inducible NO synthase and cyclooxygenase-2. Also, DHT inhibited HG-induced expression of TNF-α and IL-1β. Moreover, DHT suppressed the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) signaling pathway. Furthermore, when SH-SY5Y neurons were cultured in HG-treated BV-2 microglial supernatant, DHT pretreatment significantly increased neuronal survival, indicating the neuroprotective role of DHT. Collectively, these results suggest that DHT could protect SH-SY5Y neurons from HG-mediated BV-2 microglia inflammatory damage through inhibiting TLR4/NF-κB signaling, suggesting that maintenance of androgen level in brain might have potential benefit in neurodegenerative diseases, especially in diabetes patients combined with cognitive disorders.
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Shahulhameed S, Swain S, Jana S, Chhablani J, Ali MJ, Pappuru RR, Tyagi M, Vishwakarma S, Sailaja N, Chakrabarti S, Giri L, Kaur I. A Robust Model System for Retinal Hypoxia: Live Imaging of Calcium Dynamics and Gene Expression Studies in Primary Human Mixed Retinal Culture. Front Neurosci 2020; 13:1445. [PMID: 32116486 PMCID: PMC7020445 DOI: 10.3389/fnins.2019.01445] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/24/2019] [Indexed: 01/24/2023] Open
Abstract
The detailed mechanisms underlying oxidative stress that leads to neuroinflammation and neurodegeneration in retinal vascular conditions, including diabetic retinopathy, retinopathy of prematurity etc., remain largely unexplored mainly due to a lack of suitable disease models that can simulate the inherent neuron-glia interactions in human retina. Specifically, establishment of a mixed retinal culture (MRC) containing both neuron and glial cell types remains a challenge due to different conditions required for their optimal growth and differentiation. Here, we establish a novel primary MRC model system containing neurons, astrocytes, Müller glia, and microglia from human donor retina that can be used to study the neuromodulatory effects of glial cells under the stress. The cell characterization based on immunostaining with individual cell type-specific markers and their presence in close vicinity to each other further underscores their utility for studying their cross talk. To the best of our knowledge, this is the first instance of an in vitro model obtained from human donor retina containing four major cell types. Next, we induce hypoxic stress to MRC to investigate if hypoxia activated neuroglia modulates altered gene expression for inflammatory, apoptotic, and angiogenic markers and Ca2+ transients by live cell imaging. Further, we performed k-means clustering of the Ca2+ responses to identify the modification of clustering pattern in stressed condition. Finally, we provide the evidence that the altered Ca2+ transient correlates to differential expression of genes shown to be involved in neuroinflammation, angiogenesis, and neurodegeneration under the hypoxic conditions as seen earlier in human cell lines and animal models of diabetic retinopathy. The major features of the hypoxic conditions in the proposed human MRC model included: increase in microglia activity, chemokine and cytokine expression, and percentage of cells having higher amplitude and frequency of Ca2+ transients. Thus, the proposed experimental system can potentially serve as an ideal in vitro model for studying the neuroinflammatory and neurodegenerative changes in the retina and identifying newer drug targets.
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Affiliation(s)
| | - Sarpras Swain
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad, India
| | - Soumya Jana
- Department of Electrical Engineering, Indian Institute of Technology, Hyderabad, India
| | - Jay Chhablani
- Medical Retina and Vitreoretinal Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Mohammad Javed Ali
- Govindram Seksaria Institute of Dacryology, LV Prasad Eye Institute, Hyderabad, India
| | - Rajeev R Pappuru
- Smt. Kanuri Santhamma Center for Vitreo Retinal Diseases, LV Prasad Eye Institute, Hyderabad, India
| | - Mudit Tyagi
- Smt. Kanuri Santhamma Center for Vitreo Retinal Diseases, LV Prasad Eye Institute, Hyderabad, India
| | - Sushma Vishwakarma
- Brien Holden Eye Research Centre, LV Prasad Eye Institute, Hyderabad, India
| | - Nanda Sailaja
- Department of Electrical Engineering, Indian Institute of Technology, Hyderabad, India
| | | | - Lopamudra Giri
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad, India
| | - Inderjeet Kaur
- Brien Holden Eye Research Centre, LV Prasad Eye Institute, Hyderabad, India
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Chang JYA, Yu F, Shi L, Ko ML, Ko GYP. Melatonin Affects Mitochondrial Fission/Fusion Dynamics in the Diabetic Retina. J Diabetes Res 2019; 2019:8463125. [PMID: 31098384 PMCID: PMC6487082 DOI: 10.1155/2019/8463125] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 01/14/2019] [Accepted: 02/10/2019] [Indexed: 02/07/2023] Open
Abstract
Mitochondrial fission and fusion are dependent on cellular nutritional states, and maintaining this dynamics is critical for the health of cells. Starvation triggers mitochondrial fusion to maintain bioenergetic efficiency, but during nutrient overloads (as with hyperglycemic conditions), fragmenting mitochondria is a way to store nutrients to avoid waste of energy. In addition to ATP production, mitochondria play an important role in buffering intracellular calcium (Ca2+). We found that in cultured 661W cells, a photoreceptor-derived cell line, hyperglycemic conditions triggered an increase of the expression of dynamin-related protein 1 (DRP1), a protein marker of mitochondrial fission, and a decrease of mitofusin 2 (MFN2), a protein for mitochondrial fusion. Further, these hyperglycemic cells also had decreased mitochondrial Ca2+ but increased cytosolic Ca2+. Treating these hyperglycemic cells with melatonin, a multifaceted antioxidant, averted hyperglycemia-altered mitochondrial fission-and-fusion dynamics and mitochondrial Ca2+ levels. To mimic how people most commonly take melatonin supplements, we gave melatonin to streptozotocin- (STZ-) induced type 1 diabetic mice by daily oral gavage and determined the effects of melatonin on diabetic eyes. We found that melatonin was not able to reverse the STZ-induced systemic hyperglycemic condition, but it prevented STZ-induced damage to the neural retina and retinal microvasculature. The beneficial effects of melatonin in the neural retina in part were through alleviating STZ-caused changes in mitochondrial dynamics and Ca2+ buffering.
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Affiliation(s)
- Janet Ya-An Chang
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
- Interdisciplinary Toxicology Program, Texas A&M University, College Station, Texas, USA
| | - Fei Yu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
| | - Liheng Shi
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
| | - Michael L. Ko
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
| | - Gladys Y.-P. Ko
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
- Interdisciplinary Toxicology Program, Texas A&M University, College Station, Texas, USA
- Texas A&M Institute of Neuroscience, Texas A&M University, College Station, Texas, USA
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10
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The Role of the P2X7 Receptor in Ocular Stresses: A Potential Therapeutic Target. Vision (Basel) 2017; 1:vision1020014. [PMID: 31740640 PMCID: PMC6835678 DOI: 10.3390/vision1020014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/10/2017] [Accepted: 05/14/2017] [Indexed: 01/30/2023] Open
Abstract
The P2X7 receptor is expressed in both anterior and posterior segments of the eyeball. In the ocular surface, the P2X7 receptor is activated in case of external aggressions: preservatives and surfactants induce the activation of P2X7 receptors, leading to either apoptosis, inflammation, or cell proliferation. In the retina, the key endogenous actors of age-related macular degeneration, diabetic retinopathy, and glaucoma act through P2X7 receptors’ activation and/or upregulation of P2X7 receptors’ expression. Different therapeutic strategies aimed at the P2X7 receptor exist. P2X7 receptor antagonists, such as divalent cations and Brilliant Blue G (BBG) could be used to target either the ocular surface or the retina, as long as polyunsaturated fatty acids may exert their effects through the disruption of plasma membrane lipid rafts or saffron that reduces the response evoked by P2X7 receptor stimulation. Treatments against P2X7 receptor activation are proposed by using either eye drops or food supplements.
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Elevated Glucose and Interleukin-1 β Differentially Affect Retinal Microglial Cell Proliferation. Mediators Inflamm 2017; 2017:4316316. [PMID: 28588350 PMCID: PMC5447273 DOI: 10.1155/2017/4316316] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 04/04/2017] [Indexed: 12/16/2022] Open
Abstract
Diabetic retinopathy is considered a neurovascular disorder, hyperglycemia being considered the main risk factor for this pathology. Diabetic retinopathy also presents features of a low-grade chronic inflammatory disease, including increased levels of cytokines in the retina, such as interleukin-1 beta (IL-1β). However, how high glucose and IL-1β affect the different retinal cell types remains to be clarified. In retinal neural cell cultures, we found that IL-1β and IL-1RI are present in microglia, macroglia, and neurons. Exposure of retinal neural cell cultures to high glucose upregulated both mRNA and protein levels of IL-1β. High glucose decreased microglial and macroglial cell proliferation, whereas IL-1β increased their proliferation. Interestingly, under high glucose condition, although the number of microglial cells decreased, they showed a less ramified morphology, suggesting a more activated state, as supported by the upregulation of the levels of ED-1, a marker of microglia activation. In conclusion, IL-1β might play a key role in diabetic retinopathy, affecting microglial and macroglial cells and ultimately contributing to neural changes observed in diabetic patients. Particularly, since IL-1β has an important role in retinal microglia activation and proliferation under diabetes, limiting IL-1β-triggered inflammatory processes may provide a new therapeutic strategy to prevent the progression of diabetic retinopathy.
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12
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Study of retinal alterations in a high fat diet-induced type ii diabetes rodent: Meriones shawi. Acta Histochem 2017; 119:1-9. [PMID: 27265809 DOI: 10.1016/j.acthis.2016.05.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 05/18/2016] [Accepted: 05/19/2016] [Indexed: 12/18/2022]
Abstract
Diabetic retinopathy is a common complication of type 2 diabetes and the leading cause of blindness in adults of working age. The aim of this work was to study the repercussions of high fat diet (HFD) induced diabetes on the retina of Meriones shawi (M.sh). Two groups of six M.sh each was studied. Group I was a normal control, fed with standard laboratory granules. In Group II, rodents received a HFD of enriched laboratory granules, for a period of 3 months. Body weight and plasma glucose were determined in the two groups. Retinal sections of the two groups were stained with the Hematoxylin-Eosin. Photoreceptors were identified by immunolabeling for rhodopsin (rods) and PNA (cones). Gliosis and microglial activation were identified by immunolabeling for GFAP and Iba-1. Labeling of calretinin and parvalbumin were also carried out to study the AII amacrine cells. Retinal layers thicknesses, gliosis, and specific neural cell populations were quantified by microscopy. The body weight (+77%) and plasma glucose (+108%) were significantly greater in the HFD rodents. Three months of HFD induced a significant loss of 38.77% of cone photoreceptors, as well as gliosis and an increase of 70.67% of microglial cells. Calcium homeostatic enzymes were depleted. This work shows that HFD in Meriones shawi induces a type II diabetes-like condition that causes loss of retinal neurons and photoreceptors, as well as gliosis. Meriones shawi could be a useful experimental animal model for this physiopathology particularly in the study of retinal neuro-glial alterations in Type II diabetes.
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Vujosevic S, Micera A, Bini S, Berton M, Esposito G, Midena E. Proteome analysis of retinal glia cells-related inflammatory cytokines in the aqueous humour of diabetic patients. Acta Ophthalmol 2016; 94:56-64. [PMID: 26268591 DOI: 10.1111/aos.12812] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 06/23/2015] [Indexed: 12/15/2022]
Abstract
PURPOSE Retinal glia cells (RGC) activation and release of inflammatory cytokines have been associated with development of diabetic retinopathy (DR). In this study, we evaluated by protein array the presence of aqueous humour (AH) cytokines secreted by RGC in patients with diabetes without DR and with mild DR. METHODS This is a cross-sectional, case-control study. Thirty-five subjects (diabetics and controls) underwent full ophthalmic examination and AH samples collection before cataract surgery at the Department of Ophthalmology University of Padova. AH samples were analysed for total protein concentration (Bradford method) and RGC-related inflammatory cytokines using glass chip protein arrays. RESULTS Twelve diabetic patients without DR, 11 diabetic patients with mild DR and 12 non-diabetic controls were included. There was no significant difference in total protein concentration among the 3 groups. Interleukin IL-1β, IL-3, interferon gamma (IFN-ɣ), (IFN-ɣ)-induced protein (IP)-10 and monocyte chemotactic protein (MCP)-2 were significantly increased in diabetics versus controls. IFN-ɣ, IL-1α, IL-3 and MCP-2 were significantly increased in diabetics without DR versus controls, whereas granulocyte-macrophage colony-stimulating factor (GM-CSF), IFN-ɣ, IL-10, IP-10, regulated and normal T cell expressed and secreted (RANTES), and soluble tumour necrosis factor receptor (sTNF-R)II were significantly increased in diabetics with mild DR versus controls. Macrophage inflammatory protein (MIP-1β), GMCSF, RANTES and sTNF-RII were significantly increased in diabetics with mild DR versus diabetics without DR (p < 0.05 at least for all). CONCLUSIONS Differences in expression profile of AH cytokines between diabetics, without and with mild DR, and controls have been documented. Retinal neuroinflammatory biomarkers of RGC activation evaluated in AH by protein array analysis could guide in detecting specific phenotypes with potential for personalized management.
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Affiliation(s)
- Stela Vujosevic
- Department of Ophthalmology; University of Padova; Padova Italy
| | | | - Silvia Bini
- Department of Ophthalmology; University of Padova; Padova Italy
| | - Marianna Berton
- Department of Ophthalmology; University of Padova; Padova Italy
| | | | - Edoardo Midena
- Department of Ophthalmology; University of Padova; Padova Italy
- Fondazione G. B. Bietti; IRCCS; Roma Italy
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Behl T, Kaur I, Kotwani A. Role of leukotrienes in diabetic retinopathy. Prostaglandins Other Lipid Mediat 2015; 122:1-9. [PMID: 26673555 DOI: 10.1016/j.prostaglandins.2015.12.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/19/2015] [Accepted: 12/03/2015] [Indexed: 12/25/2022]
Abstract
The pathophysiology of diabetic retinopathy is highly complex and encompasses the detrimental roles of numerous factors/mediators in inducing various molecular pathological alterations. Although the roles of many inflammatory mediators, involved in the progression of this complication, have been thoroughly researched and studied, the part played by leukotrienes remains widely neglected. This review focuses on leukotrienes-induced mediation and aggravation of the pathological pathways, such as inflammation, oxidative stress and retinal angiogenesis, responsible for exhibition of various characteristic events including leukostasis, macular edema, retinal neovascularization and vitreous hemorrhages, hence, marking the advent of diabetic retinopathy. Acknowledging these roles, it might be possible to potentially utilize leukotrienes antagonists for suppressing or reducing the intensity of the mentioned pathological alterations. Hence, leukotrienes antagonists may act as an effective adjuvant therapy either along with other developing novel therapies (such as anti-VEGF or anti-TNF-α therapy), or with the established conventional laser photocoagulation treatment, to provide additional symptomatic relief or, possibly prevent the progression of diabetic retinopathy.
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Affiliation(s)
- Tapan Behl
- Department of Pharmacology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India.
| | - Ishneet Kaur
- Department of Pharmacy, Chandigarh College of Pharmacy, Mohali, Punjab, India
| | - Anita Kotwani
- Department of Pharmacology, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi, India
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Baptista FI, Castilho ÁF, Gaspar JM, Liberal JT, Aveleira CA, Ambrósio AF. Long-term exposure to high glucose increases the content of several exocytotic proteins and of vesicular GABA transporter in cultured retinal neural cells. Neurosci Lett 2015; 602:56-61. [PMID: 26141610 DOI: 10.1016/j.neulet.2015.06.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 06/21/2015] [Accepted: 06/22/2015] [Indexed: 11/21/2022]
Abstract
Diabetic retinopathy is a leading cause of vision loss and blindness. Increasing evidence has shown that the neuronal components of the retina are affected even before the detection of vascular lesions. Hyperglycemia is considered the main pathogenic factor for the development of diabetic complications. Nevertheless, other factors like neuroinflammation, might also contribute for neural changes. To clarify whether hyperglycemia can be the main trigger of synaptic changes, we evaluated whether prolonged elevated glucose per se, mimicking chronic hyperglycemia, is able to change the content and distribution of several exocytotic proteins and vesicular glutamate and GABA transporters in retinal neurons. Moreover, we also tested the hypothesis that an inflammatory stimulus (interleukin-1β) could exacerbate the effects induced by exposure to elevated glucose, contributing for changes in synaptic proteins in retinal neurons. Rat retinal neural cells were cultured for 9 days. Cells were exposed to elevated D-glucose (30 mM) or D-mannitol (osmotic control), for 7 days, or were exposed to interleukin-1β (10 ng/ml) or LPS (1 μg/ml) for 24 h. The protein content and distribution of SNARE proteins (SNAP-25, syntaxin-1, VAMP-2), synapsin-1, synaptotagmin-1, rabphilin 3a, VGluT-1 and VGAT, were evaluated by western blotting and immunocytochemistry. The protein content and immunoreactivity of syntaxin-1, synapsin-1, rabphilin 3a and VGAT increased in retinal neural cells exposed to high glucose. No changes were detected when cells were exposed to interleukin-1β, LPS or mannitol per se. Particularly, exposure to interleukin-1β for 24 h did not exacerbate the effect of high glucose on the content and immunoreactivity of exocytotic proteins, suggesting the primordial role of hyperglycemia for neuronal changes. In summary, prolonged exposure to elevated glucose alters the total content of several proteins involved in exocytosis, suggesting that hyperglycemia per se is a fundamental factor for neuronal changes caused by diabetes.
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Affiliation(s)
- Filipa I Baptista
- Institute for Biomedical Imaging and Life Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; CNC.IBILI, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Áurea F Castilho
- Institute for Biomedical Imaging and Life Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; CNC.IBILI, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Joana M Gaspar
- Institute for Biomedical Imaging and Life Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; CNC.IBILI, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Joana T Liberal
- CNC.IBILI, University of Coimbra, 3004-517 Coimbra, Portugal
| | | | - António F Ambrósio
- Institute for Biomedical Imaging and Life Sciences, IBILI, Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; CNC.IBILI, University of Coimbra, 3004-517 Coimbra, Portugal; AIBILI, 3004-548 Coimbra, Portugal.
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Yu Y, Chen H, Su SB. Neuroinflammatory responses in diabetic retinopathy. J Neuroinflammation 2015; 12:141. [PMID: 26245868 PMCID: PMC4527131 DOI: 10.1186/s12974-015-0368-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 07/27/2015] [Indexed: 01/14/2023] Open
Abstract
Diabetic retinopathy (DR) is a common complication of diabetes and has been recognized as a vascular dysfunction leading to blindness in working-age adults. It becomes increasingly clear that neural cells in retina play an important role in the pathogenesis of DR. Neural retina located at the back of the eye is part of the brain and a representative of the central nervous system. The neurosensory deficits seen in DR are related to inflammation and occur prior to the clinically identifiable vascular complications. The neural deficits are associated with abnormal reactions of retina glial cells and neurons in response to hyperglycemia. Improper activation of the innate immune system may also be an important contributor to the pathophysiology of DR. Therefore, DR manifests characteristics of both vasculopathy and chronic neuroinflammatory diseases. In this article, we attempt to provide an overview of the current understanding of inflammation in neural retina abnormalities in diabetes. Inhibition of neuroinflammation may represent a novel therapeutic strategy to the prevention of the progression of DR.
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Affiliation(s)
- Ying Yu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 S Xianlie Road, Guangzhou, 510060, China.
| | - Hui Chen
- Eye Institute, Affiliated Hospital of Nantong University, Nantong, 226001, China.
| | - Shao Bo Su
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 S Xianlie Road, Guangzhou, 510060, China.
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Reichenbach A, Bringmann A. Purinergic signaling in retinal degeneration and regeneration. Neuropharmacology 2015; 104:194-211. [PMID: 25998275 DOI: 10.1016/j.neuropharm.2015.05.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 05/07/2015] [Accepted: 05/07/2015] [Indexed: 02/01/2023]
Abstract
Purinergic signaling is centrally involved in mediating the degeneration of the injured and diseased retina, the induction of retinal gliosis, and the protection of the retinal tissue from degeneration. Dysregulated calcium signaling triggered by overactivation of P2X7 receptors is a crucial step in the induction of neuronal and microvascular cell death under pathogenic conditions like ischemia-hypoxia, elevated intraocular pressure, and diabetes, respectively. Overactivation of P2X7 plays also a pathogenic role in inherited and age-related photoreceptor cell death and in the age-related dysfunction and degeneration of the retinal pigment epithelium. Gliosis of micro- and macroglial cells, which is induced and/or modulated by purinergic signaling and associated with an impaired homeostatic support to neurons, and the ATP-mediated propagation of retinal gliosis from a focal injury into the surrounding noninjured tissue are involved in inducing secondary cell death in the retina. On the other hand, alterations in the glial metabolism of extracellular nucleotides, resulting in a decreased level of ATP and an increased level of adenosine, may be neuroprotective in the diseased retina. Purinergic signals stimulate the proliferation of retinal glial cells which contributes to glial scarring which has protective effects on retinal degeneration and adverse effects on retinal regeneration. Pharmacological modulation of purinergic receptors, e.g., inhibition of P2X and activation of adenosine receptors, may have clinical importance for the prevention of photoreceptor, neuronal, and microvascular cell death in diabetic retinopathy, retinitis pigmentosa, age-related macular degeneration, and glaucoma, respectively, for the clearance of retinal edema, and the inhibition of dysregulated cell proliferation in proliferative retinopathies. This article is part of a Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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Affiliation(s)
- Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany.
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
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19
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The role of microglia in diabetic retinopathy. J Ophthalmol 2014; 2014:705783. [PMID: 25258680 PMCID: PMC4166427 DOI: 10.1155/2014/705783] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 07/08/2014] [Accepted: 07/31/2014] [Indexed: 02/06/2023] Open
Abstract
There is growing evidence that chronic inflammation plays a role in both the development and progression of diabetic retinopathy. There is also evidence that molecules produced as a result of hyperglycemia can activate microglia. However the exact contribution of microglia, the resident immune cells of the central nervous system, to retinal tissue damage during diabetes remains unclear. Current data suggest that dysregulated microglial responses are linked to their deleterious effects in several neurological diseases associated with chronic inflammation. As inflammatory cytokines and hyperglycemia disseminate through the diabetic retina, microglia can change to an activated state, increase in number, translocate through the retina, and themselves become the producers of inflammatory and apoptotic molecules or alternatively exert anti-inflammatory effects. In addition, microglial genetic variations may account for some of the individual differences commonly seen in patient's susceptibility to diabetic retinopathy.
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Abstract
The pancreas is an organ with a central role in nutrient breakdown, nutrient sensing and release of hormones regulating whole body nutrient homeostasis. In diabetes mellitus, the balance is broken-cells can be starving in the midst of plenty. There are indications that the incidence of diabetes type 1 and 2, and possibly pancreatogenic diabetes, is rising globally. Events leading to insulin secretion and action are complex, but there is emerging evidence that intracellular nucleotides and nucleotides are not only important as intracellular energy molecules but also as extracellular signalling molecules in purinergic signalling cascades. This signalling takes place at the level of the pancreas, where the close apposition of various cells-endocrine, exocrine, stromal and immune cells-contributes to the integrated function. Following an introduction to diabetes, the pancreas and purinergic signalling, we will focus on the role of purinergic signalling and its changes associated with diabetes in the pancreas and selected tissues/organ systems affected by hyperglycaemia and other stress molecules of diabetes. Since this is the first review of this kind, a comprehensive historical angle is taken, and common and divergent roles of receptors for nucleotides and nucleosides in different organ systems will be given. This integrated picture will aid our understanding of the challenges of the potential and currently used drugs targeted to specific organ/cells or disorders associated with diabetes.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF UK
- Department of Pharmacology, Melbourne University, Melbourne, Australia
| | - Ivana Novak
- Molecular and Integrative Physiology, Department of Biology, University of Copenhagen, August Krogh Building, Universitetsparken 13, 2100 Copenhagen Ø, Denmark
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Vindeirinho J, Costa GN, Correia MB, Cavadas C, Santos PF. Effect of diabetes/hyperglycemia on the rat retinal adenosinergic system. PLoS One 2013; 8:e67499. [PMID: 23840723 PMCID: PMC3696088 DOI: 10.1371/journal.pone.0067499] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 05/20/2013] [Indexed: 02/04/2023] Open
Abstract
The early stages of diabetic retinopathy (DR) are characterized by alterations similar to neurodegenerative and inflammatory conditions such as increased neural apoptosis, microglial cell activation and amplified production of pro-inflammatory cytokines. Adenosine regulates several physiological functions by stimulating four subtypes of receptors, A1AR, A2AAR, A2BAR, and A3AR. Although the adenosinergic signaling system is affected by diabetes in several tissues, it is unknown whether diabetic conditions in the retina can also affect it. Adenosine delivers potent suppressive effects on virtually all cells of the immune system, but its potential role in the context of DR has yet to be studied in full. In this study, we used primary mixed cultures of rat retinal cells exposed to high glucose conditions, to mimic hyperglycemia, and a streptozotocin rat model of type 1 diabetes to determine the effect diabetes/hyperglycemia have on the expression and protein levels of adenosine receptors and of the enzymes adenosine deaminase and adenosine kinase. We found elevated mRNA and protein levels of A1AR and A2AAR, in retinal cell cultures under high glucose conditions and a transient increase in the levels of the same receptors in diabetic retinas. Adenosine deaminase and adenosine kinase expression and protein levels showed a significant decrease in diabetic retinas 30 days after diabetes induction. An enzymatic assay performed in retinal cell cultures revealed a marked decrease in the activity of adenosine deaminase under high glucose conditions. We also found an increase in extracellular adenosine levels accompanied by a decrease in intracellular levels when retinal cells were subjected to high glucose conditions. In conclusion, this study shows that several components of the retinal adenosinergic system are affected by diabetes and high glucose conditions, and the modulation observed may uncover a possible mechanism for the alleviation of the inflammatory and excitotoxic conditions observed in diabetic retinas.
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Affiliation(s)
- Joana Vindeirinho
- CNC – Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Gabriel N. Costa
- CNC – Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Mariana B. Correia
- CNC – Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Cláudia Cavadas
- CNC – Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Paulo F. Santos
- CNC – Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, Coimbra, Portugal
- * E-mail:
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Giunta S, Castorina A, Bucolo C, Magro G, Drago F, D'Agata V. Early changes in pituitary adenylate cyclase-activating peptide, vasoactive intestinal peptide and related receptors expression in retina of streptozotocin-induced diabetic rats. Peptides 2012; 37:32-9. [PMID: 22721946 DOI: 10.1016/j.peptides.2012.06.004] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 06/11/2012] [Accepted: 06/11/2012] [Indexed: 11/26/2022]
Abstract
The retinal expression and distribution of pituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal peptide (VIP) and their receptors was investigated in early streptozotocin (STZ)-induced diabetic rats. Diabetes was induced in rats by STZ injection (60 mg/kg i.p.). PACAP, VIP and their receptors in nondiabetic control and diabetic retinas were assayed by quantitative real-time PCR and Western blot 1 and 3 weeks after STZ injection. Effects of intravitreal treatment with PACAP38 on the expression of the two apoptotic-related genes Bcl-2 and p53 were also evaluated. PACAP and VIP, as well as VPAC1 and VPAC2 receptors, but not PAC1 mRNA levels, were transiently induced in retinas 1 week following STZ. These findings were confirmed by immunoblot analyses. Three weeks after the induction of diabetes, significant decreases in the expression of peptides and their receptors were observed, Bcl-2 expression decreased and p53 expression increased. Intravitreal injection of PACAP38 restored STZ-induced changes in retinal Bcl-2 and p53 expression to nondiabetic levels. The initial upregulation of PACAP, VIP and related receptors and the subsequent downregulation in retina of diabetic rats along with the protective effects of PACAP38 treatment, suggest a role for both peptides in the pathogenesis of diabetic retinopathy.
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MESH Headings
- Animals
- Base Sequence
- Blood Glucose
- DNA Primers/genetics
- Diabetes Mellitus, Experimental/blood
- Diabetes Mellitus, Experimental/metabolism
- Gene Expression/drug effects
- Intravitreal Injections
- Male
- Pituitary Adenylate Cyclase-Activating Polypeptide/administration & dosage
- Pituitary Adenylate Cyclase-Activating Polypeptide/metabolism
- Pituitary Adenylate Cyclase-Activating Polypeptide/pharmacology
- Proto-Oncogene Proteins c-bcl-2/genetics
- Proto-Oncogene Proteins c-bcl-2/metabolism
- Rats, Sprague-Dawley
- Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I/genetics
- Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I/metabolism
- Receptors, Vasoactive Intestinal Peptide, Type II/genetics
- Receptors, Vasoactive Intestinal Peptide, Type II/metabolism
- Receptors, Vasoactive Intestinal Polypeptide, Type I/genetics
- Receptors, Vasoactive Intestinal Polypeptide, Type I/metabolism
- Retina/metabolism
- Streptozocin
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
- Vasoactive Intestinal Peptide/metabolism
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Calcium mediates high glucose-induced HIF-1α and VEGF expression in cultured rat retinal Müller cells through CaMKII-CREB pathway. Acta Pharmacol Sin 2012; 33:1030-6. [PMID: 22796763 DOI: 10.1038/aps.2012.61] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM To investigate the effects of high glucose (HG) medium on expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) in cultured rat retinal Müller cells and to determine the signaling pathways mediating the effects. METHODS Primary cultures of retinal Müller cells were prepared from Sprague-Dawley rats, and incubated in a medium containg HG (30 mmol/L) in the presence of the membrane-permeable Ca(2+) chelator BAPTA-AM (10 μmol/L) or the CaMKII inhibitor KN93 (10 μmol/L). The levels of CaMKII, p-CaMKII, CREB, p-CREB, HIF-1α, and VEGF proteins were measured with Western blotting, while HIF-1á and VEGF mRNA levels were determined using real-time RT-PCR. RESULTS The stimulation of retinal Müller cell with HG for 24 h remarkably increased the expression levels of HIF-1α and VEGF. These responses were significantly inhibited in the presence of BAPTA-AM or KN93. Both BAPTA-AM and KN93 also significantly inhibited HG-induced phosphorylation of CaMKII and CREB in the cultured retinal Müller cells. Transfection of the cultured retinal Müller cells with antisense CREB oligonucleotide (300 nmol/L) was similarly effective in blocking the HG-induced increase of HIF-1α and VEGF. CONCLUSION HG-induced HIF-1α and VEGF expression in cultured rat retinal Müller cells depends on intracellular free Ca(2+) and activation of CaMKII-CREB pathway. The activation of CaMKII-CREB pathway by HG may be a possible mechanism underlying the pathogenesis of diabetic retinopathy.
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Chavira-Suárez E, Sandoval A, Quintero H, Bustamante P, Felix R, Lamas M. Hyperglycemia induces early upregulation of the calcium sensor KChIP3/DREAM/calsenilin in the rat retina. Biochem Biophys Res Commun 2012; 418:420-5. [PMID: 22277672 DOI: 10.1016/j.bbrc.2012.01.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 01/10/2012] [Indexed: 11/18/2022]
Abstract
Hyperglycemia alters the tight control of intracellular calcium dynamics in retinal cells and may lead to the development of diabetic retinopathy. The potassium channel interacting protein 3 (KChIP3) also known as DREAM (Downstream Regulatory Element Antagonist Modulator) or calsenilin (KChIP3/DREAM/calsenilin), a member of the neuronal calcium sensor protein family, is expressed in Müller glial cells and upregulated under high glucose experimental culture conditions. Here, we analyzed the expression and function of KChIP3 in the retina of streptozotocin induced diabetic Long Evans rats by immunofluorescence confocal microscopy, western blot, co-immunoprecipitation, whole cell patch clamp recording on isolated cells and KChIP3 gene silencing by RNA interference. Three weeks after streptozotocin application, KChIP3 was increased throughout the different retinal layers and this process was not linked to augmented apoptosis. KChIP3 co-immunoprecipitated with voltage gated K(+) channels of the K(V)4.2-4.3 subtype in retinal extracts from control and hyperglycemic rats. Electrophysiological analysis showed that control cells did not express A type (K(V)4-mediated) K(+) currents but most of the cells from streptozotocin treated retinas displayed macroscopic currents with an inactivating component sensitive to 4-AP, suggesting the persistence of the A type currents at early times after treatment. siRNA analysis in Müller cells cultures grown under high glucose experimental conditions corroborated that, when the expression of KChIP3 is 50% reduced, the number of cells expressing A type currents decreases significantly. Together these data suggest an altered expression and function of KChIP3 after streptozotocin induced hyperglycemia that might help explain some pathological alterations in early diabetic retinopathy.
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Affiliation(s)
- Erika Chavira-Suárez
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del IPN (Cinvestav-IPN), Mexico Distrito Federal, Mexico
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Abstract
Microglial cells are the resident macrophages in the central nervous system. These cells of mesodermal/mesenchymal origin migrate into all regions of the central nervous system, disseminate through the brain parenchyma, and acquire a specific ramified morphological phenotype termed "resting microglia." Recent studies indicate that even in the normal brain, microglia have highly motile processes by which they scan their territorial domains. By a large number of signaling pathways they can communicate with macroglial cells and neurons and with cells of the immune system. Likewise, microglial cells express receptors classically described for brain-specific communication such as neurotransmitter receptors and those first discovered as immune cell-specific such as for cytokines. Microglial cells are considered the most susceptible sensors of brain pathology. Upon any detection of signs for brain lesions or nervous system dysfunction, microglial cells undergo a complex, multistage activation process that converts them into the "activated microglial cell." This cell form has the capacity to release a large number of substances that can act detrimental or beneficial for the surrounding cells. Activated microglial cells can migrate to the site of injury, proliferate, and phagocytose cells and cellular compartments.
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Kim NH, Park KS, Sohn JH, Yeh BI, Ko CM, Kong ID. Functional Expression of P2Y Receptors in WERI-Rb1 Retinoblastoma Cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2011; 15:61-6. [PMID: 21461242 DOI: 10.4196/kjpp.2011.15.1.61] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 02/16/2011] [Accepted: 02/18/2011] [Indexed: 01/28/2023]
Abstract
P2Y receptors are metabotropic G-protein-coupled receptors, which are involved in many important biologic functions in the central nervous system including retina. Subtypes of P2Y receptors in retinal tissue vary according to the species and the cell types. We examined the molecular and pharmacologic profiles of P2Y purinoceptors in retinoblastoma cell, which has not been identified yet. To achieve this goal, we used Ca(2+) imaging technique and western blot analysis in WERI-Rb-1 cell, a human retinoblastoma cell line. ATP (10 µM) elicited strong but transient [Ca(2+)](i) increase in a concentration-dependent manner from more than 80% of the WERI-Rb-1 cells (n=46). Orders of potency of P2Y agonists in evoking [Ca(2+)](i) transients were 2MeS-ATP>ATP>>UTP=αβ-MeATP, which was compatible with the subclass of P2Y(1) receptor. The [Ca(2+)](i) transients evoked by applications of 2MeS-ATP and/or ATP were also profoundly suppressed in the presence of P2Y(1) selective blocker (MRS 2179; 30 µM). P2Y(1) receptor expression in WERI-Rb-1 cells was also identified by using western blot. Taken together, P2Y(1) receptor is mainly expressed in a retinoblastoma cell, which elicits Ca(2+) release from internal Ca(2+) storage sites via the phospholipase C-mediated pathway. P2Y(1) receptor activation in retinoblastoma cell could be a useful model to investigate the role of purinergic [Ca(2+)](i) signaling in neural tissue as well as to find a novel therapeutic target to this lethal cancer.
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Affiliation(s)
- Na-Hyun Kim
- Department of Basic Nursing Science and Institute for Nursing Science, Keimyung University, Daegu 704-701, Korea
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Effect of neurotrophic factors on neuronal apoptosis and neurite regeneration in cultured rat retinas exposed to high glucose. Brain Res 2010; 1346:43-51. [DOI: 10.1016/j.brainres.2010.05.073] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2010] [Revised: 05/17/2010] [Accepted: 05/24/2010] [Indexed: 01/18/2023]
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