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Srinivasan L, Page G, Kirpalani H, Murray JC, Das A, Higgins RD, Carlo WA, Bell EF, Goldberg RN, Schibler K, Sood BG, Stevenson DK, Stoll BJ, Van Meurs KP, Johnson KJ, Levy J, McDonald SA, Zaterka-Baxter KM, Kennedy KA, Sánchez PJ, Duara S, Walsh MC, Shankaran S, Wynn JL, Cotten CM. Genome-wide association study of sepsis in extremely premature infants. Arch Dis Child Fetal Neonatal Ed 2017; 102:F439-F445. [PMID: 28283553 PMCID: PMC5563277 DOI: 10.1136/archdischild-2016-311545] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 02/02/2017] [Accepted: 02/13/2017] [Indexed: 12/16/2022]
Abstract
OBJECTIVE To identify genetic variants associated with sepsis (early-onset and late-onset) using a genome-wide association (GWA) analysis in a cohort of extremely premature infants. STUDY DESIGN Previously generated GWA data from the Neonatal Research Network's anonymised genomic database biorepository of extremely premature infants were used for this study. Sepsis was defined as culture-positive early-onset or late-onset sepsis or culture-proven meningitis. Genomic and whole-genome-amplified DNA was genotyped for 1.2 million single-nucleotide polymorphisms (SNPs); 91% of SNPs were successfully genotyped. We imputed 7.2 million additional SNPs. p Values and false discovery rates (FDRs) were calculated from multivariate logistic regression analysis adjusting for gender, gestational age and ancestry. Target statistical value was p<10-5. Secondary analyses assessed associations of SNPs with pathogen type. Pathway analyses were also run on primary and secondary end points. RESULTS Data from 757 extremely premature infants were included: 351 infants with sepsis and 406 infants without sepsis. No SNPs reached genome-wide significance levels (5×10-8); two SNPs in proximity to FOXC2 and FOXL1 genes achieved target levels of significance. In secondary analyses, SNPs for ELMO1, IRAK2 (Gram-positive sepsis), RALA, IMMP2L (Gram-negative sepsis) and PIEZO2 (fungal sepsis) met target significance levels. Pathways associated with sepsis and Gram-negative sepsis included gap junctions, fibroblast growth factor receptors, regulators of cell division and interleukin-1-associated receptor kinase 2 (p values<0.001 and FDR<20%). CONCLUSIONS No SNPs met genome-wide significance in this cohort of extremely low birthweight infants; however, areas of potential association and pathways meriting further study were identified.
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Affiliation(s)
- Lakshmi Srinivasan
- Department of Pediatrics, The Children’s Hospital of Philadelphia and The University of Pennsylvania, Philadelphia, PA
| | - Grier Page
- Social, Statistical and Environmental Sciences Unit, RTI International, Research Triangle Park, NC
| | - Haresh Kirpalani
- Department of Pediatrics, The Children’s Hospital of Philadelphia and The University of Pennsylvania, Philadelphia, PA
| | | | - Abhik Das
- Social, Statistical and Environmental Sciences Unit, RTI International, Rockville, MD
| | - Rosemary D. Higgins
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD
| | - Waldemar A. Carlo
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL
| | - Edward F. Bell
- University of Iowa, Department of Pediatrics, Iowa City, IA
| | | | - Kurt Schibler
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH
| | - Beena G. Sood
- Department of Pediatrics, Wayne State University, Detroit, MI
| | - David K. Stevenson
- Department of Pediatrics, Division of Neonatal and Developmental Medicine, Stanford University School of Medicine and Lucile Packard Children’s Hospital, Palo Alto, CA
| | - Barbara J. Stoll
- Emory University School of Medicine, Department of Pediatrics, Children’s Healthcare of Atlanta, Atlanta, GA
| | - Krisa P. Van Meurs
- Department of Pediatrics, Division of Neonatal and Developmental Medicine, Stanford University School of Medicine and Lucile Packard Children’s Hospital, Palo Alto, CA
| | | | - Joshua Levy
- Social, Statistical and Environmental Sciences Unit, RTI International, Research Triangle Park, NC
| | - Scott A. McDonald
- Social, Statistical and Environmental Sciences Unit, RTI International, Research Triangle Park, NC
| | | | - Kathleen A. Kennedy
- Department of Pediatrics, University of Texas Medical School at Houston, Houston, TX
| | - Pablo J. Sánchez
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Shahnaz Duara
- University of Miami Miller School of Medicine, Miami, FL
| | - Michele C. Walsh
- Department of Pediatrics, Rainbow Babies & Children’s Hospital, Case Western Reserve University, Cleveland, OH
| | | | - James L. Wynn
- Department of Pediatrics, University of Florida, Gainesville, FL
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Abstract
Neuronal survival, electrical signaling and synaptic activity require a well-balanced micro-environment in the central nervous system. This is achieved by the blood-brain barrier (BBB), an endothelial barrier situated in the brain capillaries, that controls near-to-all passage in and out of the brain. The endothelial barrier function is highly dependent on signaling interactions with surrounding glial, neuronal and vascular cells, together forming the neuro-glio-vascular unit. Within this functional unit, connexin (Cx) channels are of utmost importance for intercellular communication between the different cellular compartments. Connexins are best known as the building blocks of gap junction (GJ) channels that enable direct cell-cell transfer of metabolic, biochemical and electric signals. In addition, beyond their role in direct intercellular communication, Cxs also form unapposed, non-junctional hemichannels in the plasma membrane that allow the passage of several paracrine messengers, complementing direct GJ communication. Within the NGVU, Cxs are expressed in vascular endothelial cells, including those that form the BBB, and are eminent in astrocytes, especially at their endfoot processes that wrap around cerebral vessels. However, despite the density of Cx channels at this so-called gliovascular interface, it remains unclear as to how Cx-based signaling between astrocytes and BBB endothelial cells may converge control over BBB permeability in health and disease. In this review we describe available evidence that supports a role for astroglial as well as endothelial Cxs in the regulation of BBB permeability during development as well as in disease states.
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Vicario N, Calabrese G, Zappalà A, Parenti C, Forte S, Graziano ACE, Vanella L, Pellitteri R, Cardile V, Parenti R. Inhibition of Cx43 mediates protective effects on hypoxic/reoxygenated human neuroblastoma cells. J Cell Mol Med 2017; 21:2563-2572. [PMID: 28488330 PMCID: PMC5618696 DOI: 10.1111/jcmm.13177] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 02/28/2017] [Indexed: 12/18/2022] Open
Abstract
Olfactory ensheathing cells (OECs), a special population of glial cells, are able to synthesise several trophic factors exerting a neuroprotective action and promoting growth and functional recovery in both in vitro and in vivo models. In the present work, we investigated the neuroprotective effects of OEC-conditioned medium (OEC-CM) on two different human neuron-like cell lines, SH-SY5Y and SK-N-SH (neuroblastoma cell lines), under normoxic and hypoxic conditions. In addition, we also focused our attention on the role of connexins (Cxs) in the neuroprotective processes. Our results confirmed OEC-CM mediated neuroprotection as shown by cell adherence, proliferation and cellular viability analyses. Reduced connexin 43 (Cx43) levels in OEC-CM compared to unconditioned cells in hypoxic conditions prompted us to investigate the role of Cx43-Gap junctions (GJs) and Cx43-hemichannels (HCs) in hypoxic/reoxygenation injury using carbenoxolone (non-selective GJ inhibitor), ioxynil octanoato (selective Cx43-GJ inhibitor) and Gap19 (selective Cx43-HC inhibitor). We found that Cx43-GJ and Cx43-HC inhibitors are able to protect SH-SY5Y and allow to these cultures to overcome the injury. Our findings support the hypothesis that both OEC-CM and the inhibition of Cx43-GJs and Cx43-HCs offer a neuroprotective effect by reducing Cx43-mediated cell-to-cell and cell-to-extracellular environment communications.
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Affiliation(s)
- Nunzio Vicario
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, Catania, Italy
| | - Giovanna Calabrese
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, Catania, Italy
| | - Agata Zappalà
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, Catania, Italy
| | - Carmela Parenti
- Department of Drug Sciences, University of Catania, Catania, Italy
| | | | | | - Luca Vanella
- Department of Drug Sciences, University of Catania, Catania, Italy
| | - Rosalia Pellitteri
- Institute Neurological Sciences, National Research Council, Catania, Italy
| | - Venera Cardile
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, Catania, Italy
| | - Rosalba Parenti
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, Catania, Italy
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Xu J, Chen L, Li L. Pannexin hemichannels: A novel promising therapy target for oxidative stress related diseases. J Cell Physiol 2017; 233:2075-2090. [PMID: 28295275 DOI: 10.1002/jcp.25906] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 03/09/2017] [Indexed: 12/16/2022]
Abstract
Pannexins, which contain three subtypes: pannexin-1, -2, and -3, are vertebrate glycoproteins that form non-junctional plasma membrane intracellular hemichannels via oligomerization. Oxidative stress refers to an imbalance of the generation and elimination of reactive oxygen species (ROS). Studies have shown that elevated ROS levels are pivotal in the development of a variety of diseases. Recent studies indicate that the occurrence of these oxidative stress related diseases is associated with pannexin hemichannels. It is also reported that pannexins regulate the production of ROS which in turn may increase the opening of pannexin hemichannels. In this paper, we review recent researches about the important role of pannexin hemichannels in oxidative stress related diseases. Thus, pannexin hemichannels, novel therapeutic targets, hold promise in managing oxidative stress related diseases such as the tumor, inflammatory bowel diseases (IBD), pulmonary fibrosis, chronic obstructive pulmonary disease (COPD), cardiovascular disease, insulin resistance (IR), and neural degeneration diseases.
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Affiliation(s)
- Jin Xu
- Learning Key Laboratory for Pharmacoproteomics, Institute of Pharmacy and Pharmacology, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, P. R. China
| | - Linxi Chen
- Learning Key Laboratory for Pharmacoproteomics, Institute of Pharmacy and Pharmacology, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, P. R. China
| | - Lanfang Li
- Learning Key Laboratory for Pharmacoproteomics, Institute of Pharmacy and Pharmacology, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang, P. R. China
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Age-dependent alterations in neuronal activity in the hippocampus and visual cortex in a mouse model of Juvenile Neuronal Ceroid Lipofuscinosis (CLN3). Neurobiol Dis 2017; 100:19-29. [DOI: 10.1016/j.nbd.2016.12.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/20/2016] [Accepted: 12/28/2016] [Indexed: 11/19/2022] Open
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Scemes E, Velíšková J. Exciting and not so exciting roles of pannexins. Neurosci Lett 2017; 695:25-31. [PMID: 28284836 DOI: 10.1016/j.neulet.2017.03.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 03/02/2017] [Accepted: 03/06/2017] [Indexed: 01/24/2023]
Abstract
It is the current view that purinergic signaling regulates many physiological functions. Pannexin1 (Panx1), a member of the gap junction family of proteins is an ATP releasing channel that plays important physio-pathological roles in various tissues, including the CNS. Upon binding to purinergic receptors expressed in neural cells, ATP triggers cellular responses including increased cell proliferation, cell morphology changes, release of cytokines, and regulation of neuronal excitability via release of glutamate, GABA and ATP itself. Under pathological conditions such as ischemia, trauma, inflammation, and epilepsy, extracellular ATP concentrations increases drastically but the consequences of this surge is still difficult to characterize due to its rapid metabolism in ADP and adenosine, the latter having inhibitory action on neuronal activity. For seizures, for instance, the excitatory effect of ATP on neuronal activity is mainly related to its action of P2X receptors, while the inhibitory effects are related to activation of P1, adenosine receptors. Here we provide a mini review on the properties of pannexins with a main focus on Panx1 and its involvement in seizure activity. Although there are only few studies implicating Panx1 in seizures, they are illustrative of the dual role that Panx1 has on neuronal excitability.
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Affiliation(s)
- Eliana Scemes
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - Jana Velíšková
- Departments of Cell Biology & Anatomy, Obstetrics & Gynecology and Neurology, New York Medical College, Valhalla, NY, 10595, USA.
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57
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Belousov AB, Fontes JD, Freitas-Andrade M, Naus CC. Gap junctions and hemichannels: communicating cell death in neurodevelopment and disease. BMC Cell Biol 2017; 18:4. [PMID: 28124625 PMCID: PMC5267333 DOI: 10.1186/s12860-016-0120-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Gap junctions are unique membrane channels that play a significant role in intercellular communication in the developing and mature central nervous system (CNS). These channels are composed of connexin proteins that oligomerize into hexamers to form connexons or hemichannels. Many different connexins are expressed in the CNS, with some specificity with regard to the cell types in which distinct connexins are found, as well as the timepoints when they are expressed in the developing and mature CNS. Both the main neuronal Cx36 and glial Cx43 play critical roles in neurodevelopment. These connexins also mediate distinct aspects of the CNS response to pathological conditions. An imbalance in the expression, translation, trafficking and turnover of connexins, as well as mutations of connexins, can impact their function in the context of cell death in neurodevelopment and disease. With the ever-increasing understanding of connexins in the brain, therapeutic strategies could be developed to target these membrane channels in various neurological disorders.
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Affiliation(s)
- Andrei B Belousov
- Department of Molecular & Integrative Physiology, University of Kansas Medical Center, The University of Kansas, Kansas City, KS, 66160, USA
| | - Joseph D Fontes
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, The University of Kansas, Kansas City, KS, 66160, USA
| | - Moises Freitas-Andrade
- Department of Cellular & Physiological Sciences, Faculty of Medicine, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Christian C Naus
- Department of Cellular & Physiological Sciences, Faculty of Medicine, Life Sciences Institute, The University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
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Choi SR, Roh DH, Yoon SY, Kwon SG, Choi HS, Han HJ, Beitz AJ, Lee JH. Astrocyte sigma-1 receptors modulate connexin 43 expression leading to the induction of below-level mechanical allodynia in spinal cord injured mice. Neuropharmacology 2016; 111:34-46. [PMID: 27567941 DOI: 10.1016/j.neuropharm.2016.08.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 08/21/2016] [Accepted: 08/23/2016] [Indexed: 01/13/2023]
Abstract
We have previously shown using a spinal cord injury (SCI) model that gap junctions contribute to the early spread of astrocyte activation in the lumbar spinal cord and that this astrocyte communication plays critical role in the induction of central neuropathic pain. Sigma-1 receptors (Sig-1Rs) have been implicated in spinal astrocyte activation and the development of peripheral neuropathic pain, yet their contribution to central neuropathic pain remains unknown. Thus, we investigated whether SCI upregulates spinal Sig-1Rs, which in turn increase the expression of the astrocytic gap junction protein, connexin 43 (Cx43) leading to the induction of central neuropathic pain. A thoracic spinal cord hemisection significantly increased both astrocyte activation and Cx43 expression in lumbar dorsal horn. Sig-1Rs were also increased in lumbar dorsal horn astrocytes, but not neurons or microglia. Intrathecal injection of an astrocyte metabolic inhibitor (fluorocitrate); a gap junction/hemichannel blocker (carbenoxolone); or a Cx43 mimetic peptide (43Gap26) significantly reduced SCI-induced bilateral below-level mechanical allodynia. Blockade of Sig-1Rs with BD1047 during the induction phase of pain significantly suppressed the SCI-induced development of mechanical allodynia, astrocyte activation, increased expression of Cx43 in both total and membrane levels, and increased association of Cx43 with Sig-1R. However, SCI did not change the expression of oligodendrocyte (Cx32) or neuronal (Cx36) gap junction proteins. These findings demonstrate that SCI activates astrocyte Sig-1Rs leading to increases in the expression of the gap junction protein, Cx43 and astrocyte activation in the lumbar dorsal horn, and ultimately contribute to the induction of bilateral below-level mechanical allodynia.
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Affiliation(s)
- Sheu-Ran Choi
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | - Dae-Hyun Roh
- Department of Maxillofacial Tissue Regeneration and Research Center for Tooth and Periodontal Tissue Regeneration, School of Dentistry, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Seo-Yeon Yoon
- Pain Cognitive Function Research Center, Department of Brain and Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Soon-Gu Kwon
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | - Hoon-Seong Choi
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | - Ho-Jae Han
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea
| | - Alvin J Beitz
- Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, MN 55108, USA
| | - Jang-Hern Lee
- Department of Veterinary Physiology, BK21 PLUS Program for Creative Veterinary Science Research, Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul 08826, Republic of Korea.
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Gajardo-Gómez R, Labra VC, Maturana CJ, Shoji KF, Santibañez CA, Sáez JC, Giaume C, Orellana JA. Cannabinoids prevent the amyloid β-induced activation of astroglial hemichannels: A neuroprotective mechanism. Glia 2016; 65:122-137. [PMID: 27757991 DOI: 10.1002/glia.23080] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/13/2016] [Accepted: 09/19/2016] [Indexed: 11/06/2022]
Abstract
The mechanisms involved in Alzheimer's disease are not completely understood and how astrocytes and their gliotransmission contribute to this neurodegenerative disease remains to be fully elucidated. Previous studies have shown that amyloid-β peptide (Aβ) induces neuronal death by a mechanism that involves the excitotoxic release of ATP and glutamate associated to astroglial hemichannel opening. We have demonstrated that synthetic and endogenous cannabinoids (CBs) reduce the opening of astrocyte Cx43 hemichannels evoked by activated microglia or inflammatory mediators. Nevertheless, whether CBs could prevent the astroglial hemichannel-dependent death of neurons evoked by Aβ is unknown. Astrocytes as well as acute hippocampal slices were treated with the active fragment of Aβ alone or in combination with the following CBs: WIN, 2-AG, or methanandamide (Meth). Hemichannel activity was monitored by single channel recordings and by time-lapse ethidium uptake while neuronal death was assessed by Fluoro-Jade C staining. We report that CBs fully prevented the hemichannel activity and inflammatory profile evoked by Aβ in astrocytes. Moreover, CBs fully abolished the Aβ-induced release of excitotoxic glutamate and ATP associated to astrocyte Cx43 hemichannel activity, as well as neuronal damage in hippocampal slices exposed to Aβ. Consequently, this work opens novel avenues for alternative treatments that target astrocytes to maintain neuronal function and survival during AD. GLIA 2016 GLIA 2017;65:122-137.
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Affiliation(s)
- Rosario Gajardo-Gómez
- Departamento de Neurología; Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Valeria C Labra
- Departamento de Neurología; Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Carola J Maturana
- Departamento de Neurología; Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Kenji F Shoji
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago de Chile, Chile and Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso, Chile
| | - Cristian A Santibañez
- Departamento de Neurología; Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan C Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de Chile, Santiago de Chile, Chile and Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso, Chile
| | - Christian Giaume
- Center for Interdisciplinary Research in Biology, Collège de France/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241, Institut National de la Santé et de la Recherche Médicale U1050, Paris Cedex 05, France
| | - Juan A Orellana
- Departamento de Neurología; Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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Olympiou M, Sargiannidou I, Markoullis K, Karaiskos C, Kagiava A, Kyriakoudi S, Abrams CK, Kleopa KA. Systemic inflammation disrupts oligodendrocyte gap junctions and induces ER stress in a model of CNS manifestations of X-linked Charcot-Marie-Tooth disease. Acta Neuropathol Commun 2016; 4:95. [PMID: 27585976 PMCID: PMC5009701 DOI: 10.1186/s40478-016-0369-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 08/17/2016] [Indexed: 11/10/2022] Open
Abstract
X-linked Charcot-Marie-Tooth disease (CMT1X) is a common form of inherited neuropathy resulting from different mutations affecting the gap junction (GJ) protein connexin32 (Cx32). A subset of CMT1X patients may additionally present with acute fulminant CNS dysfunction, typically triggered by conditions of systemic inflammation and metabolic stress. To clarify the underlying mechanisms of CNS phenotypes in CMT1X we studied a mouse model of systemic inflammation induced by lipopolysaccharide (LPS) injection to compare wild type (WT), connexin32 (Cx32) knockout (KO), and KO T55I mice expressing the T55I Cx32 mutation associated with CNS phenotypes. Following a single intraperitoneal LPS or saline (controls) injection at the age of 40-60 days systemic inflammatory response was documented by elevated TNF-α and IL-6 levels in peripheral blood and mice were evaluated 1 week after injection. Behavioral analysis showed graded impairment of motor performance in LPS treated mice, worse in KO T55I than in Cx32 KO and in Cx32 KO worse than WT. Iba1 immunostaining revealed widespread inflammation in LPS treated mice with diffusely activated microglia throughout the CNS. Immunostaining for the remaining major oligodendrocyte connexin Cx47 and for its astrocytic partner Cx43 revealed widely reduced expression of Cx43 and loss of Cx47 GJs in oligodendrocytes. Real-time PCR and immunoblot analysis indicated primarily a down regulation of Cx43 expression with secondary loss of Cx47 membrane localization. Inflammatory changes and connexin alterations were most severe in the KO T55I group. To examine why the presence of the T55I mutant exacerbates pathology even more than in Cx32 KO mice, we analyzed the expression of ER-stress markers BiP, Fas and CHOP by immunostaining, immunoblot and Real-time PCR. All markers were increased in LPS treated KO T55I mice more than in other genotypes. In conclusion, LPS induced neuroinflammation causes disruption of the main astrocyte-oligodendrocyte GJs, which may contribute to the increased sensitivity of Cx32 KO mice to LPS and of patients with CMT1X to various stressors. Moreover the presence of an intracellularly retained, misfolded CMT1X mutant such as T55I induces ER stress under inflammatory conditions, further exacerbating oligodendrocyte dysfunction and pathological changes in the CNS.
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Affiliation(s)
- Margarita Olympiou
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Irene Sargiannidou
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Kyriaki Markoullis
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Christos Karaiskos
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Alexia Kagiava
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Styliana Kyriakoudi
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus
| | - Charles K Abrams
- Department of Neurology and Rehabilitation, University of Illinois at Chicago, Chicago, USA
| | - Kleopas A Kleopa
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, Nicosia, Cyprus.
- Neurology Clinics, The Cyprus Institute of Neurology and Genetics and Cyprus School of Molecular Medicine, 6 International Airport Avenue, P.O. Box 23462, , 1683, Nicosia, Cyprus.
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Astroglial connexin43 contributes to neuronal suffering in a mouse model of Alzheimer's disease. Cell Death Differ 2016; 23:1691-701. [PMID: 27391799 DOI: 10.1038/cdd.2016.63] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 05/19/2016] [Accepted: 05/25/2016] [Indexed: 01/15/2023] Open
Abstract
In Alzheimer's disease (AD), astrocyte properties are modified but their involvement in this pathology is only beginning to be appreciated. The expression of connexins, proteins forming gap junction channels and hemichannels, is increased in astrocytes contacting amyloid plaques in brains of AD patients and APP/PS1 mice. The consequences on their channel functions was investigated in a murine model of familial AD, the APPswe/PS1dE9 mice. Whereas gap junctional communication was not affected, we revealed that hemichannels were activated in astrocytes of acute hippocampal slices containing Aβ plaques. Such hemichannel activity was detected in all astrocytes, whatever their distance from amyloid plaques, but with an enhanced activity in the reactive astrocytes contacting amyloid plaques. Connexin43 was the main hemichannel contributor, however, a minor pannexin1 component was also identified in the subpopulation of reactive astrocytes in direct contact with plaques. Distinct regulatory pathways are involved in connexin and pannexin hemichannel activation. Inflammation triggered pannexin hemichannel activity, whereas connexin43 hemichannels were activated by the increase in resting calcium level of astrocytes. Importantly, hemichannel activation led to the release of ATP and glutamate that contributed to maintain a high calcium level in astrocytes placing them in the center of a vicious circle. The astroglial targeted connexin43 gene knocking-out in APPswe/PS1dE9 mice allowed to diminish gliotransmitter release and to alleviate neuronal damages, reducing oxidative stress and neuritic dystrophies in hippocampal neurons associated to plaques. Altogether, these data highlight the importance of astroglial hemichannels in AD and suggest that blocking astroglial hemichannel activity in astrocytes could represent an alternative therapeutic strategy in AD.
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Willebrords J, Crespo Yanguas S, Maes M, Decrock E, Wang N, Leybaert L, Kwak BR, Green CR, Cogliati B, Vinken M. Connexins and their channels in inflammation. Crit Rev Biochem Mol Biol 2016; 51:413-439. [PMID: 27387655 PMCID: PMC5584657 DOI: 10.1080/10409238.2016.1204980] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Inflammation may be caused by a variety of factors and is a hallmark of a plethora of acute and chronic diseases. The purpose of inflammation is to eliminate the initial cell injury trigger, to clear out dead cells from damaged tissue and to initiate tissue regeneration. Despite the wealth of knowledge regarding the involvement of cellular communication in inflammation, studies on the role of connexin-based channels in this process have only begun to emerge in the last few years. In this paper, a state-of-the-art overview of the effects of inflammation on connexin signaling is provided. Vice versa, the involvement of connexins and their channels in inflammation will be discussed by relying on studies that use a variety of experimental tools, such as genetically modified animals, small interfering RNA and connexin-based channel blockers. A better understanding of the importance of connexin signaling in inflammation may open up towards clinical perspectives.
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Affiliation(s)
- Joost Willebrords
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
| | - Sara Crespo Yanguas
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
| | - Michaël Maes
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology Group, Ghent
University, De Pintelaan 185, 9000 Ghent, Belgium; Elke Decrock: Tel: +32 9 332 39
73, Nan Wang: Tel: +32 9 332 39 38, Luc Leybaert: Tel: +32 9 332 33 66
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology Group, Ghent
University, De Pintelaan 185, 9000 Ghent, Belgium; Elke Decrock: Tel: +32 9 332 39
73, Nan Wang: Tel: +32 9 332 39 38, Luc Leybaert: Tel: +32 9 332 33 66
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology Group, Ghent
University, De Pintelaan 185, 9000 Ghent, Belgium; Elke Decrock: Tel: +32 9 332 39
73, Nan Wang: Tel: +32 9 332 39 38, Luc Leybaert: Tel: +32 9 332 33 66
| | - Brenda R. Kwak
- Department of Pathology and Immunology and Division of Cardiology,
University of Geneva, Rue Michel-Servet 1, CH-1211 Geneva, Switzerland; Brenda R.
Kwak: Tel: +41 22 379 57 37
| | - Colin R. Green
- Department of Ophthalmology and New Zealand National Eye Centre,
University of Auckland, New Zealand; Colin R. Green: Tel: +64 9 923 61 35
| | - Bruno Cogliati
- Department of Pathology, School of Veterinary Medicine and Animal
Science, University of São Paulo, Av. Prof. Dr. Orlando Marques de Paiva 87,
05508-270 São Paulo, Brazil; Bruno Cogliati: Tel: +55 11 30 91 12 00
| | - Mathieu Vinken
- Department of In Vitro Toxicology and
Dermato-Cosmetology, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels,
Belgium; Joost Willebrords: + Tel: 32 2 477 45 87, Michaël Maes: Tel: +32 2
477 45 87, Sara Crespo Yanguas: Tel: +32 2 477 45 87
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Hu X, Yuan Y, Wang D, Su Z. Heterogeneous astrocytes: Active players in CNS. Brain Res Bull 2016; 125:1-18. [PMID: 27021168 DOI: 10.1016/j.brainresbull.2016.03.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/22/2016] [Accepted: 03/24/2016] [Indexed: 12/12/2022]
Abstract
Astrocytes, the predominant cell type that are broadly distributed in the brain and spinal cord, play key roles in maintaining homeostasis of the central nerve system (CNS) in physiological and pathological conditions. Increasing evidence indicates that astrocytes are a complex colony with heterogeneity on morphology, gene expression, function and many other aspects depending on their spatio-temporal distribution and activation level. In pathological conditions, astrocytes differentially respond to all kinds of insults, including injury and disease, and participate in the neuropathological process. Based on current studies, we here give an overview of the roles of heterogeneous astrocytes in CNS, especially in neuropathologies, which focuses on biological and functional diversity of astrocytes. We propose that a precise understanding of the heterogeneous astrocytes is critical to unlocking the secrets about pathogenesis and treatment of the mazy CNS.
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Affiliation(s)
- Xin Hu
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China
| | - Yimin Yuan
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China
| | - Dan Wang
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China
| | - Zhida Su
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China.
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64
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Niu J, Li T, Yi C, Huang N, Koulakoff A, Weng C, Li C, Zhao CJ, Giaume C, Xiao L. Connexin-based channels contribute to metabolic pathways in the oligodendroglial lineage. J Cell Sci 2016; 129:1902-14. [PMID: 27006115 DOI: 10.1242/jcs.178731] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 03/14/2016] [Indexed: 12/22/2022] Open
Abstract
Oligodendrocyte precursor cells (OPCs) undergo a series of energy-consuming developmental events; however, the uptake and trafficking pathways for their energy metabolites remain unknown. In the present study, we found that 2-NBDG, a fluorescent glucose analog, can be delivered between astrocytes and oligodendrocytes through connexin-based gap junction channels but cannot be transferred between astrocytes and OPCs. Instead, connexin hemichannel-mediated glucose uptake supports OPC proliferation, and ethidium bromide uptake or increase of 2-NBDG uptake rate is correlated with intracellular Ca(2+) elevation in OPCs, indicating a Ca(2+)-dependent activation of connexin hemichannels. Interestingly, deletion of connexin 43 (Cx43, also known as GJA1) in astrocytes inhibits OPC proliferation by decreasing matrix glucose levels without impacting on OPC hemichannel properties, a process that also occurs in corpus callosum from acute brain slices. Thus, dual functions of connexin-based channels contribute to glucose supply in oligodendroglial lineage, which might pave a new way for energy-metabolism-directed oligodendroglial-targeted therapies.
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Affiliation(s)
- Jianqin Niu
- Department of Histology and Embryology, Faculty of Basic Medicine, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China
| | - Tao Li
- Department of Histology and Embryology, Faculty of Basic Medicine, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China
| | - Chenju Yi
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Institut National de la Santé et de la Recherche Médicale U1050, Paris 75231, Cedex 05, France
| | - Nanxin Huang
- Department of Histology and Embryology, Faculty of Basic Medicine, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China
| | - Annette Koulakoff
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Institut National de la Santé et de la Recherche Médicale U1050, Paris 75231, Cedex 05, France
| | - Chuanhuang Weng
- Southwest Eye Hospital, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Chengren Li
- Department of Histology and Embryology, Faculty of Basic Medicine, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China
| | - Cong-Jian Zhao
- Southwest Eye Hospital, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Christian Giaume
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Institut National de la Santé et de la Recherche Médicale U1050, Paris 75231, Cedex 05, France
| | - Lan Xiao
- Department of Histology and Embryology, Faculty of Basic Medicine, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, Chongqing 400038, China
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Kıray H, Lindsay SL, Hosseinzadeh S, Barnett SC. The multifaceted role of astrocytes in regulating myelination. Exp Neurol 2016; 283:541-9. [PMID: 26988764 PMCID: PMC5019113 DOI: 10.1016/j.expneurol.2016.03.009] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/01/2016] [Accepted: 03/08/2016] [Indexed: 11/29/2022]
Abstract
Astrocytes are the major glial cell of the central nervous system (CNS), providing both metabolic and physical support to other neural cells. After injury, astrocytes become reactive and express a continuum of phenotypes which may be supportive or inhibitory to CNS repair. This review will focus on the ability of astrocytes to influence myelination in the context of specific secreted factors, cytokines and other neural cell targets within the CNS. In particular, we focus on how astrocytes provide energy and cholesterol to neurons, influence synaptogenesis, affect oligodendrocyte biology and instigate cross-talk between the many cellular components of the CNS.
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Affiliation(s)
- Hülya Kıray
- Institute of Infection, Inflammation and Immunity, Sir Graeme Davies Building, Glasgow Biomedical Research Centre, 120 University Place, University of Glasgow, Glasgow G12 8TA, United Kingdom
| | - Susan L Lindsay
- Institute of Infection, Inflammation and Immunity, Sir Graeme Davies Building, Glasgow Biomedical Research Centre, 120 University Place, University of Glasgow, Glasgow G12 8TA, United Kingdom
| | - Sara Hosseinzadeh
- Institute of Infection, Inflammation and Immunity, Sir Graeme Davies Building, Glasgow Biomedical Research Centre, 120 University Place, University of Glasgow, Glasgow G12 8TA, United Kingdom
| | - Susan C Barnett
- Institute of Infection, Inflammation and Immunity, Sir Graeme Davies Building, Glasgow Biomedical Research Centre, 120 University Place, University of Glasgow, Glasgow G12 8TA, United Kingdom..
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66
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Microglial interleukin-1β in the ipsilateral dorsal horn inhibits the development of mirror-image contralateral mechanical allodynia through astrocyte activation in a rat model of inflammatory pain. Pain 2016; 156:1046-1059. [PMID: 25749305 DOI: 10.1097/j.pain.0000000000000148] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Damage on one side of the body can also result in pain on the contralateral unaffected side, called mirror-image pain (MIP). Currently, the mechanisms responsible for the development of MIP are unknown. In this study, we investigated the involvement of spinal microglia and interleukin-1β (IL-1β) in the development of MIP using a peripheral inflammatory pain model. After unilateral carrageenan injection, mechanical allodynia (MA) in both hind paws and the expression levels of spinal Iba-1, IL-1β, and GFAP were evaluated. Ipsilateral MA was induced beginning at 3 hours after carrageenan injection, whereas contralateral MA showed a delayed onset occurring 5 days after injection. A single intrathecal (i.t.) injection of minocycline, a tetracycline derivative that displays selective inhibition of microglial activation, or an interleukin-1 receptor antagonist (IL-1ra) on the day of carrageenan injection caused an early temporary induction of contralateral MA, whereas repeated i.t. treatment with these drugs from days 0 to 3 resulted in a long-lasting contralateral MA, which was evident in its advanced development. We further showed that IL-1β was localized to microglia and that minocycline inhibited the carrageenan-induced increases in spinal Iba-1 and IL-1β expression. Conversely, minocycline or IL-1ra pretreatment increased GFAP expression as compared with that of control rats. However, i.t. pretreatment with fluorocitrate, an astrocyte inhibitor, restored minocycline- or IL-1ra-induced contralateral MA. These results suggest that spinal IL-1β derived from activated microglia temporarily suppresses astrocyte activation, which can ultimately prevent the development of contralateral MA under inflammatory conditions. These findings imply that microglial IL-1β plays an important role in regulating the induction of inflammatory MIP.
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67
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Ochoa-Cortes F, Turco F, Linan-Rico A, Soghomonyan S, Whitaker E, Wehner S, Cuomo R, Christofi FL. Enteric Glial Cells: A New Frontier in Neurogastroenterology and Clinical Target for Inflammatory Bowel Diseases. Inflamm Bowel Dis 2016; 22:433-49. [PMID: 26689598 PMCID: PMC4718179 DOI: 10.1097/mib.0000000000000667] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 08/29/2015] [Indexed: 12/12/2022]
Abstract
The word "glia" is derived from the Greek word "γλoια," glue of the enteric nervous system, and for many years, enteric glial cells (EGCs) were believed to provide mainly structural support. However, EGCs as astrocytes in the central nervous system may serve a much more vital and active role in the enteric nervous system, and in homeostatic regulation of gastrointestinal functions. The emphasis of this review will be on emerging concepts supported by basic, translational, and/or clinical studies, implicating EGCs in neuron-to-glial (neuroglial) communication, motility, interactions with other cells in the gut microenvironment, infection, and inflammatory bowel diseases. The concept of the "reactive glial phenotype" is explored as it relates to inflammatory bowel diseases, bacterial and viral infections, postoperative ileus, functional gastrointestinal disorders, and motility disorders. The main theme of this review is that EGCs are emerging as a new frontier in neurogastroenterology and a potential therapeutic target. New technological innovations in neuroimaging techniques are facilitating progress in the field, and an update is provided on exciting new translational studies. Gaps in our knowledge are discussed for further research. Restoring normal EGC function may prove to be an efficient strategy to dampen inflammation. Probiotics, palmitoylethanolamide (peroxisome proliferator-activated receptor-α), interleukin-1 antagonists (anakinra), and interventions acting on nitric oxide, receptor for advanced glycation end products, S100B, or purinergic signaling pathways are relevant clinical targets on EGCs with therapeutic potential.
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Affiliation(s)
| | - Fabio Turco
- Department of Anesthesiology, The Ohio State University, Columbus, Ohio
- Department of Clinical and Experimental Medicine, Gastroenterological Unit, “Federico II” University of Naples, Naples, Italy; and
| | | | - Suren Soghomonyan
- Department of Anesthesiology, The Ohio State University, Columbus, Ohio
| | - Emmett Whitaker
- Department of Anesthesiology, The Ohio State University, Columbus, Ohio
| | - Sven Wehner
- Department of Surgery, University of Bonn, Bonn, Germany
| | - Rosario Cuomo
- Department of Clinical and Experimental Medicine, Gastroenterological Unit, “Federico II” University of Naples, Naples, Italy; and
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68
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Gap Junction Intercellular Communication Mediates Ammonia-Induced Neurotoxicity. Neurotox Res 2015; 29:314-24. [PMID: 26646155 DOI: 10.1007/s12640-015-9581-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/20/2015] [Accepted: 11/24/2015] [Indexed: 12/21/2022]
Abstract
Astrocytes are important brain targets of ammonia, a neurotoxin implicated in the development of hepatic encephalopathy. During hyperammonemia, the pivotal role of astrocytes in brain function and homeostasis is impaired. These cells are abundantly interconnected by gap junctions (GJ), which are intercellular channels that allow the exchange of signaling molecules and metabolites. This communication may also increase cellular vulnerability during injuries, while GJ uncoupling could limit the extension of a lesion. Therefore, the current study was performed to investigate whether astrocyte coupling through GJ contributes to ammonia-induced cytotoxicity. We found that carbenoxolone (CBX), an effective GJ blocker, prevented the following effects induced by ammonia in astrocyte primary cultures: (1) decrease in cell viability and membrane integrity; (2) increase in reactive oxygen species production; (3) decrease in GSH intracellular levels; (4) GS activity; (5) pro-inflammatory cytokine release. On the other hand, CBX had no effect on C6 astroglial cells, which are poorly coupled via GJ. To our knowledge, this study provides the first evidence that GJ play a role in ammonia-induced cytotoxicity. Although more studies in vivo are required to confirm our hypothesis, our data suggest that GJ communication between astrocytes may transmit damage signals and excitotoxic components from unhealthy to normal cells, thereby contributing to the propagation of the neurotoxicity of ammonia.
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69
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Del Rio R, Quintanilla RA, Orellana JA, Retamal MA. Neuron-Glia Crosstalk in the Autonomic Nervous System and Its Possible Role in the Progression of Metabolic Syndrome: A New Hypothesis. Front Physiol 2015; 6:350. [PMID: 26648871 PMCID: PMC4664731 DOI: 10.3389/fphys.2015.00350] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 11/09/2015] [Indexed: 01/26/2023] Open
Abstract
Metabolic syndrome (MS) is characterized by the following physiological alterations: increase in abdominal fat, insulin resistance, high concentration of triglycerides, low levels of HDL, high blood pressure, and a generalized inflammatory state. One of the pathophysiological hallmarks of this syndrome is the presence of neurohumoral activation, which involve autonomic imbalance associated to hyperactivation of the sympathetic nervous system. Indeed, enhanced sympathetic drive has been linked to the development of endothelial dysfunction, hypertension, stroke, myocardial infarct, and obstructive sleep apnea. Glial cells, the most abundant cells in the central nervous system, control synaptic transmission, and regulate neuronal function by releasing bioactive molecules called gliotransmitters. Recently, a new family of plasma membrane channels called hemichannels has been described to allow the release of gliotransmitters and modulate neuronal firing rate. Moreover, a growing amount of evidence indicates that uncontrolled hemichannel opening could impair glial cell functions, affecting synaptic transmission and neuronal survival. Given that glial cell functions are disturbed in various metabolic diseases, we hypothesize that progression of MS may relies on hemichannel-dependent impairment of glial-to-neuron communication by a mechanism related to dysfunction of inflammatory response and mitochondrial metabolism of glial cells. In this manuscript, we discuss how glial cells may contribute to the enhanced sympathetic drive observed in MS, and shed light about the possible role of hemichannels in this process.
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Affiliation(s)
- Rodrigo Del Rio
- Centro de Investigación Biomédica, Universidad Autónoma de Chile Santiago, Chile ; Dirección de Investigación, Universidad Científica del Sur Lima, Perú
| | | | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina. Clínica Alemana Universidad del Desarrollo Santiago, Chile
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Bosch ME, Kielian T. Neuroinflammatory paradigms in lysosomal storage diseases. Front Neurosci 2015; 9:417. [PMID: 26578874 PMCID: PMC4627351 DOI: 10.3389/fnins.2015.00417] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 10/15/2015] [Indexed: 01/02/2023] Open
Abstract
Lysosomal storage diseases (LSDs) include approximately 70 distinct disorders that collectively account for 14% of all inherited metabolic diseases. LSDs are caused by mutations in various enzymes/proteins that disrupt lysosomal function, which impairs macromolecule degradation following endosome-lysosome and phagosome-lysosome fusion and autophagy, ultimately disrupting cellular homeostasis. LSDs are pathologically typified by lysosomal inclusions composed of a heterogeneous mixture of various proteins and lipids that can be found throughout the body. However, in many cases the CNS is dramatically affected, which may result from heightened neuronal vulnerability based on their post-mitotic state. Besides intrinsic neuronal defects, another emerging factor common to many LSDs is neuroinflammation, which may negatively impact neuronal survival and contribute to neurodegeneration. Microglial and astrocyte activation is a hallmark of many LSDs that affect the CNS, which often precedes and predicts regions where eventual neuron loss will occur. However, the timing, intensity, and duration of neuroinflammation may ultimately dictate the impact on CNS homeostasis. For example, a transient inflammatory response following CNS insult/injury can be neuroprotective, as glial cells attempt to remove the insult and provide trophic support to neurons. However, chronic inflammation, as seen in several LSDs, can promote neurodegeneration by creating a neurotoxic environment due to elevated levels of cytokines, chemokines, and pro-apoptotic molecules. Although neuroinflammation has been reported in several LSDs, the cellular basis and mechanisms responsible for eliciting neuroinflammatory pathways are just beginning to be defined. This review highlights the role of neuroinflammation in select LSDs and its potential contribution to neuron loss.
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Affiliation(s)
- Megan E. Bosch
- Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical CenterOmaha, NE, USA
| | - Tammy Kielian
- Pathology and Microbiology, University of Nebraska Medical CenterOmaha, NE, USA
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Morioka N, Zhang FF, Nakamura Y, Kitamura T, Hisaoka-Nakashima K, Nakata Y. Tumor necrosis factor-mediated downregulation of spinal astrocytic connexin43 leads to increased glutamatergic neurotransmission and neuropathic pain in mice. Brain Behav Immun 2015; 49:293-310. [PMID: 26116449 DOI: 10.1016/j.bbi.2015.06.015] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 06/05/2015] [Accepted: 06/16/2015] [Indexed: 11/29/2022] Open
Abstract
Spinal cord astrocytes are critical in the maintenance of neuropathic pain. Connexin 43 (Cx43) expressed on spinal dorsal horn astrocytes modulates synaptic neurotransmission, but its role in nociceptive transduction has yet to be fully elaborated. In mice, Cx43 is mainly expressed in astrocytes, not neurons or microglia, in the spinal dorsal horn. Hind paw mechanical hypersensitivity was observed beginning 3days after partial sciatic nerve ligation (PSNL), but a persistent downregulation of astrocytic Cx43 in ipsilateral lumbar spinal dorsal horn was not observed until 7days post-PSNL, suggesting that Cx43 downregulation mediates the maintenance and not the initiation of nerve injury-induced hypersensitivity. Downregulation of Cx43 expression by intrathecal treatment with Cx43 siRNA also induced mechanical hypersensitivity. Conversely, restoring Cx43 by an adenovirus vector expressing Cx43 (Ad-Cx43) ameliorated PSNL-induced mechanical hypersensitivity. The sensitized state following PSNL is likely maintained by dysfunctional glutamatergic neurotransmission, as Cx43 siRNA-induced mechanical hypersensitivity was attenuated with intrathecal treatment of glutamate receptor antagonists MK801 and CNQX, but not neurokinin-1 receptor antagonist CP96345 or the Ca(2+) channel subunit α2δ1 blocker gabapentin. The source of this dysfunctional glutamatergic neurotransmission is likely decreased clearance of glutamate from the synapse rather than increased glutamate release into the synapse. Astrocytic expression of glutamate transporter GLT-1, but not GLAST, and activity of glutamate transport were markedly decreased in mice intrathecally injected with Cx43-targeting siRNA but not non-targeting siRNA. Glutamate release from spinal synaptosomes prepared from mice treated with either Cx43-targeting siRNA or non-targeting siRNA was unchanged. Intrathecal injection of Ad-Cx43 in PSNL mice restored astrocytic GLT-1 expression. The cytokine tumor necrosis factor (TNF) has been implicated in the induction of central sensitization, particularly through its actions on astrocytes, in the spinal cord following peripheral injury. Intrathecal injection of TNF in naïve mice induced the downregulation of both Cx43 and GLT-1 in spinal dorsal horn, as well as hind paw mechanical hypersensitivity, as observed in PSNL mice. Conversely, intrathecal treatment of PSNL mice with the TNF inhibitor etanercept prevented not only mechanical hypersensitivity but also the downregulation of Cx43 and GLT-1 expression in astrocytes. The current findings indicate that spinal astrocytic Cx43 are essential for the maintenance of neuropathic pain following peripheral nerve injury and suggest modulation of Cx43 as a novel target for developing analgesics for neuropathic pain.
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Affiliation(s)
- Norimitsu Morioka
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan.
| | - Fang Fang Zhang
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoki Nakamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Tomoya Kitamura
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Kazue Hisaoka-Nakashima
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
| | - Yoshihiro Nakata
- Department of Pharmacology, Hiroshima University Graduate School of Biomedical & Health Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
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Intracellular Cleavage of the Cx43 C-Terminal Domain by Matrix-Metalloproteases: A Novel Contributor to Inflammation? Mediators Inflamm 2015; 2015:257471. [PMID: 26424967 PMCID: PMC4573893 DOI: 10.1155/2015/257471] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Accepted: 08/13/2015] [Indexed: 01/11/2023] Open
Abstract
The coordination of tissue function is mediated by gap junctions (GJs) that enable direct cell-cell transfer of metabolic and electric signals. GJs are formed by connexin (Cx) proteins of which Cx43 is most widespread in the human body. Beyond its role in direct intercellular communication, Cx43 also forms nonjunctional hemichannels (HCs) in the plasma membrane that mediate the release of paracrine signaling molecules in the extracellular environment. Both HC and GJ channel function are regulated by protein-protein interactions and posttranslational modifications that predominantly take place in the C-terminal domain of Cx43. Matrix metalloproteases (MMPs) are a major group of zinc-dependent proteases, known to regulate not only extracellular matrix remodeling, but also processing of intracellular proteins. Together with Cx43 channels, both GJs and HCs, MMPs contribute to acute inflammation and a small number of studies reports on an MMP-Cx43 link. Here, we build further on these reports and present a novel hypothesis that describes proteolytic cleavage of the Cx43 C-terminal domain by MMPs and explores possibilities of how such cleavage events may affect Cx43 channel function. Finally, we set out how aberrant channel function resulting from cleavage can contribute to the acute inflammatory response during tissue injury.
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Connexin 43 stabilizes astrocytes in a stroke-like milieu to facilitate neuronal recovery. Acta Pharmacol Sin 2015; 36:928-38. [PMID: 26095039 DOI: 10.1038/aps.2015.39] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 04/02/2015] [Indexed: 01/26/2023] Open
Abstract
AIM Connexin 43 (Cx43) is a member of connexin family mainly expressed in astrocytes, which forms gap junctions and hemichannels and maintains the normal shape and function of astrocytes. In this study we investigated the role of Cx43 in astrocytes in facilitating neuronal recovery during ischemic stroke. METHODS Primary culture of astrocytes or a mixed culture of astrocytes and cortical neurons was subjected to oxygen glucose deprivation and reperfusion (OGD/R). The expression of Cx43 and Ephrin-A4 in astrocytes was detected using immunocytochemical staining and Western blot assays. Intercellular Ca(2+) concentration was determined with Fluo-4 AM fluorescent staining. Middle cerebral artery occlusion (MCAO) model rats were used for in vivo studies. RESULTS OGD/R treatment of cultured astrocytes caused a decrement of Cx43 expression and translocation of Cx43 from cell membrane to cytoplasm, accompanied by cell retraction. Furthermore, OGD/R increased intracellular Ca(2+) concentration, activated CaMKII/CREB pathways and upregulated expression of Ephrin-A4 in the astrocytes. All these changes in OGD/R-treated astrocytes were alleviated by overexpression of Cx43. In the cortical neurons cultured with astrocytes, OGD/R inhibited the neurite growth, whereas overexpression of Cx43 or knockdown of Ephrin-A4 in astrocytes restored the neurite growth. In MCAO model rats, neuronal recovery was found to be correlated with the recuperation of Cx43 and Ephrin-A4 in astrocytes. CONCLUSION Cx43 can stabilize astrocytes and facilitate the resistance to the deleterious effects of a stroke-like milieu and promote neuronal recovery.
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Decrock E, De Bock M, Wang N, Bultynck G, Giaume C, Naus CC, Green CR, Leybaert L. Connexin and pannexin signaling pathways, an architectural blueprint for CNS physiology and pathology? Cell Mol Life Sci 2015; 72:2823-51. [PMID: 26118660 PMCID: PMC11113968 DOI: 10.1007/s00018-015-1962-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 02/06/2023]
Abstract
The central nervous system (CNS) is composed of a highly heterogeneous population of cells. Dynamic interactions between different compartments (neuronal, glial, and vascular systems) drive CNS function and allow to integrate and process information as well as to respond accordingly. Communication within this functional unit, coined the neuro-glio-vascular unit (NGVU), typically relies on two main mechanisms: direct cell-cell coupling via gap junction channels (GJCs) and paracrine communication via the extracellular compartment, two routes to which channels composed of transmembrane connexin (Cx) or pannexin (Panx) proteins can contribute. Multiple isoforms of both protein families are present in the CNS and each CNS cell type is characterized by a unique Cx/Panx portfolio. Over the last two decades, research has uncovered a multilevel platform via which Cxs and Panxs can influence different cellular functions within a tissue: (1) Cx GJCs enable a direct cell-cell communication of small molecules, (2) Cx hemichannels and Panx channels can contribute to autocrine/paracrine signaling pathways, and (3) different structural domains of these proteins allow for channel-independent functions, such as cell-cell adhesion, interactions with the cytoskeleton, and the activation of intracellular signaling pathways. In this paper, we discuss current knowledge on their multifaceted contribution to brain development and to specific processes in the NGVU, including synaptic transmission and plasticity, glial signaling, vasomotor control, and blood-brain barrier integrity in the mature CNS. By highlighting both physiological and pathological conditions, it becomes evident that Cxs and Panxs can play a dual role in the CNS and that an accurate fine-tuning of each signaling mechanism is crucial for normal CNS physiology.
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Affiliation(s)
- Elke Decrock
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Marijke De Bock
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Nan Wang
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Louvain, Belgium
| | - Christian Giaume
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, 75231 Paris Cedex 05, France
- University Pierre et Marie
Curie, ED, N°158, 75005 Paris, France
- MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005 Paris, France
| | - Christian C. Naus
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3 Canada
| | - Colin R. Green
- Department of Ophthalmology, The University of Auckland, Auckland, New Zealand
| | - Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
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Hansson E, Skiöldebrand E. Coupled cell networks are target cells of inflammation, which can spread between different body organs and develop into systemic chronic inflammation. JOURNAL OF INFLAMMATION-LONDON 2015. [PMID: 26213498 PMCID: PMC4514450 DOI: 10.1186/s12950-015-0091-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Several organs in the body comprise cells coupled into networks. These cells have in common that they are excitable but do not express action potentials. Furthermore, they are equipped with Ca2+ signaling systems, which can be intercellular and/or extracellular. The transport of small molecules between the cells occurs through gap junctions comprising connexin 43. Examples of cells coupled into networks include astrocytes, keratinocytes, chondrocytes, synovial fibroblasts, osteoblasts, connective tissue cells, cardiac and corneal fibroblasts, myofibroblasts, hepatocytes, and different types of glandular cells. These cells are targets for inflammation, which can be initiated after injury or in disease. If the inflammation reaches the CNS, it develops into neuroinflammation and can be of importance in the development of systemic chronic inflammation, which can manifest as pain and result in changes in the expression and structure of cellular components. Biochemical parameters of importance for cellular functions are described in this review.
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Affiliation(s)
- Elisabeth Hansson
- Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Per Dubbsgatan 14, 1tr, , SE 413 45 Gothenburg, Sweden
| | - Eva Skiöldebrand
- Section of Pathology, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden ; Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska University Hospital, Gothenburg University, Gothenburg, Sweden
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76
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Sin WC, Aftab Q, Bechberger JF, Leung JH, Chen H, Naus CC. Astrocytes promote glioma invasion via the gap junction protein connexin43. Oncogene 2015; 35:1504-16. [DOI: 10.1038/onc.2015.210] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 04/22/2015] [Accepted: 04/24/2015] [Indexed: 01/03/2023]
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77
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Mahi N, Kumar A, Jaggi AS, Singh N, Dhawan R. Possible role of pannexin 1/P2x7 purinoceptor in neuroprotective mechanism of ischemic postconditioning in mice. J Surg Res 2015; 196:190-9. [DOI: 10.1016/j.jss.2015.02.050] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 02/18/2015] [Accepted: 02/19/2015] [Indexed: 01/01/2023]
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Rama Rao KV, Kielian T. Astrocytes and lysosomal storage diseases. Neuroscience 2015; 323:195-206. [PMID: 26037807 DOI: 10.1016/j.neuroscience.2015.05.061] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 05/21/2015] [Accepted: 05/22/2015] [Indexed: 12/19/2022]
Abstract
Lysosomal storage diseases (LSDs) encompass a wide range of disorders characterized by inborn errors of lysosomal function. The majority of LSDs result from genetic defects in lysosomal enzymes, although some arise from mutations in lysosomal proteins that lack known enzymatic activity. Neuropathological abnormalities are a feature of several LSDs and when severe, represent an important determinant in disease outcome. Glial dysfunction, particularly in astrocytes, is also observed in numerous LSDs and has been suggested to impact neurodegeneration. This review will discuss the potential role of astrocytes in LSDs and highlight the possibility of targeting glia as a beneficial strategy to counteract the neuropathology associated with LSDs.
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Affiliation(s)
- K V Rama Rao
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, United States
| | - T Kielian
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, United States.
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79
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Vázquez C, Tolón RM, Pazos MR, Moreno M, Koester EC, Cravatt BF, Hillard CJ, Romero J. Endocannabinoids regulate the activity of astrocytic hemichannels and the microglial response against an injury: In vivo studies. Neurobiol Dis 2015; 79:41-50. [PMID: 25917763 DOI: 10.1016/j.nbd.2015.04.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 04/02/2015] [Accepted: 04/19/2015] [Indexed: 10/23/2022] Open
Abstract
Anandamide (AEA) is an endocannabinoid (EC) that modulates multiple functions in the CNS and that is released in areas of injury, exerting putative neuroprotective actions. In the present study, we have used intravital microscopy to analyze the role of the EC system in the glial response against an acute insult. Our data show that AEA modulates astroglial function in vivo by increasing connexin-43 hemichannel (HC) activity. Furthermore, the genetic inactivation of the AEA-degrading enzyme, fatty acid amide hydrolase (FAAH), also increased HC activity and enhanced the microglial response against an acute injury to the brain parenchyma, effects that were mediated by cannabinoid CB1 receptors. The contribution of ATP released through an astrocytic HC was critical for the microglial response, as this was prevented by the use of the HC blocker flufenamic acid and by apyrase. As could be expected, brain concentrations of AEA, palmitoylethanolamide (PEA) and oleoylethanolamide (OEA) were elevated in FAAH-null mice, while 2-arachidonoylglycerol (2-AG) concentrations remained unaltered. In summary, these findings demonstrate that AEA modifies glial functions by promoting an enhanced pro-inflammatory glial response in the brain.
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Affiliation(s)
- Carmen Vázquez
- Laboratorio de Apoyo a la Investigación, Hospital Universitario Fundación Alcorcón, 28922 Alcorcón, Madrid, Spain
| | - Rosa María Tolón
- Laboratorio de Apoyo a la Investigación, Hospital Universitario Fundación Alcorcón, 28922 Alcorcón, Madrid, Spain
| | - María Ruth Pazos
- Laboratorio de Apoyo a la Investigación, Hospital Universitario Fundación Alcorcón, 28922 Alcorcón, Madrid, Spain; Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Marta Moreno
- Laboratorio de Apoyo a la Investigación, Hospital Universitario Fundación Alcorcón, 28922 Alcorcón, Madrid, Spain
| | - Erin C Koester
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Benjamin F Cravatt
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Cecilia J Hillard
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Julián Romero
- Laboratorio de Apoyo a la Investigación, Hospital Universitario Fundación Alcorcón, 28922 Alcorcón, Madrid, Spain; School of Biosciences, Universidad Francisco de Vitoria, Pozuelo de Alarcón, 28223 Madrid, Spain.
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80
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Freitas-Andrade M, Naus CC. Astrocytes in neuroprotection and neurodegeneration: The role of connexin43 and pannexin1. Neuroscience 2015; 323:207-21. [PMID: 25913636 DOI: 10.1016/j.neuroscience.2015.04.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Revised: 04/13/2015] [Accepted: 04/15/2015] [Indexed: 12/26/2022]
Abstract
The World Health Organization has predicted that by 2040 neurodegenerative diseases will overtake cancer to become the world's second leading cause of death after cardiovascular disease. This has sparked the development of several European and American brain research initiatives focusing on elucidating the underlying cellular and molecular mechanisms of neurodegenerative diseases. Connexin (Cx) and pannexin (Panx) membrane channel proteins are conduits through which neuronal, glial, and vascular tissues interact. In the brain, this interaction is highly critical for homeostasis and brain repair after injury. Understanding the molecular mechanisms by which these membrane channels function, in health and disease, might be particularly influential in establishing conceptual frameworks to develop new therapeutics against Cx and Panx channels. This review focuses on current insights and emerging concepts, particularly the impact of connexin43 and pannexin1, under neuroprotective and neurodegenerative conditions within the context of astrocytes.
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Affiliation(s)
- M Freitas-Andrade
- Department of Cellular and Physiological Sciences, The Life Science Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - C C Naus
- Department of Cellular and Physiological Sciences, The Life Science Institute, University of British Columbia, Vancouver, British Columbia, Canada.
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81
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Orellana JA, Moraga-Amaro R, Díaz-Galarce R, Rojas S, Maturana CJ, Stehberg J, Sáez JC. Restraint stress increases hemichannel activity in hippocampal glial cells and neurons. Front Cell Neurosci 2015; 9:102. [PMID: 25883550 PMCID: PMC4382970 DOI: 10.3389/fncel.2015.00102] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 03/09/2015] [Indexed: 12/21/2022] Open
Abstract
Stress affects brain areas involved in learning and emotional responses, which may contribute in the development of cognitive deficits associated with major depression. These effects have been linked to glial cell activation, glutamate release and changes in neuronal plasticity and survival including atrophy of hippocampal apical dendrites, loss of synapses and neuronal death. Under neuro-inflammatory conditions, we recently unveiled a sequential activation of glial cells that release ATP and glutamate via hemichannels inducing neuronal death due to activation of neuronal NMDA/P2X7 receptors and pannexin1 hemichannels. In the present work, we studied if stress-induced glia activation is associated to changes in hemichannel activity. To this end, we compared hemichannel activity of brain cells after acute or chronic restraint stress in mice. Dye uptake experiments in hippocampal slices revealed that acute stress induces opening of both Cx43 and Panx1 hemichannels in astrocytes, which were further increased by chronic stress; whereas enhanced Panx1 hemichannel activity was detected in microglia and neurons after acute/chronic and chronic stress, respectively. Moreover, inhibition of NMDA/P2X7 receptors reduced the chronic stress-induced hemichannel opening, whereas blockade of Cx43 and Panx1 hemichannels fully reduced ATP and glutamate release in hippocampal slices from stressed mice. Thus, we propose that gliotransmitter release through hemichannels may participate in the pathogenesis of stress-associated psychiatric disorders and possibly depression.
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Affiliation(s)
- Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Rodrigo Moraga-Amaro
- Laboratorio de Neurobiología, Centro de Investigaciones Biomédicas, Facultad de Ciencias Biológicas and Facultad de Medicina, Universidad Andres Bello Santiago, Chile
| | - Raúl Díaz-Galarce
- Laboratorio de Neurobiología, Centro de Investigaciones Biomédicas, Facultad de Ciencias Biológicas and Facultad de Medicina, Universidad Andres Bello Santiago, Chile
| | - Sebastián Rojas
- Laboratorio de Neurobiología, Centro de Investigaciones Biomédicas, Facultad de Ciencias Biológicas and Facultad de Medicina, Universidad Andres Bello Santiago, Chile
| | - Carola J Maturana
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Jimmy Stehberg
- Laboratorio de Neurobiología, Centro de Investigaciones Biomédicas, Facultad de Ciencias Biológicas and Facultad de Medicina, Universidad Andres Bello Santiago, Chile
| | - Juan C Sáez
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile Santiago, Chile ; Instituto Milenio, Centro Interdisciplinario de Neurociencias de Valparaíso Santiago, Chile
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82
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Abudara V, Roux L, Dallérac G, Matias I, Dulong J, Mothet JP, Rouach N, Giaume C. Activated microglia impairs neuroglial interaction by opening Cx43 hemichannels in hippocampal astrocytes. Glia 2015; 63:795-811. [PMID: 25643695 DOI: 10.1002/glia.22785] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 12/18/2014] [Indexed: 01/04/2023]
Abstract
Glia plays an active role in neuronal functions and dysfunctions, some of which depend on the expression of astrocyte connexins, the gap junction channel and hemichannel proteins. Under neuroinflammation triggered by the endotoxin lipopolysacharide (LPS), microglia is primary stimulated and releases proinflammatory agents affecting astrocytes and neurons. Here, we investigate the effects of such microglial activation on astrocyte connexin-based channel functions and their consequences on synaptic activity in an ex vivo model. We found that LPS induces astroglial hemichannel opening in acute hippocampal slices while no change is observed in gap junctional communication. Based on pharmacological and genetic approaches we found that the LPS-induced hemichannel opening is mainly due to Cx43 hemichannel activity. This process primarily requires a microglial stimulation resulting in the release of at least two proinflammatory cytokines, IL-1β and TNF-α. Consequences of the hemichannel-mediated increase in membrane permeability are a calcium rise in astrocytes and an enhanced glutamate release associated to a reduction in excitatory synaptic activity of pyramidal neurons in response to Schaffer's collateral stimulation. As a whole our findings point out astroglial hemichannels as key determinants of the impairment of synaptic transmission during neuroinflammation.
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Affiliation(s)
- Verónica Abudara
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, Paris Cedex, France; University Pierre et Marie Curie, ED, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France; Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
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Morris G, Berk M, Galecki P, Walder K, Maes M. The Neuro-Immune Pathophysiology of Central and Peripheral Fatigue in Systemic Immune-Inflammatory and Neuro-Immune Diseases. Mol Neurobiol 2015; 53:1195-1219. [PMID: 25598355 DOI: 10.1007/s12035-015-9090-9] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 01/05/2015] [Indexed: 01/18/2023]
Abstract
Many patients with systemic immune-inflammatory and neuro-inflammatory disorders, including depression, rheumatoid arthritis, systemic lupus erythematosus, Sjögren's disease, cancer, cardiovascular disorder, Parkinson's disease, multiple sclerosis, stroke, and chronic fatigue syndrome/myalgic encephalomyelitis, endure pathological levels of fatigue. The aim of this narrative review is to delineate the wide array of pathways that may underpin the incapacitating fatigue occurring in systemic and neuro-inflammatory disorders. A wide array of immune, inflammatory, oxidative and nitrosative stress (O&NS), bioenergetic, and neurophysiological abnormalities are involved in the etiopathology of these disease states and may underpin the incapacitating fatigue that accompanies these disorders. This range of abnormalities comprises: increased levels of pro-inflammatory cytokines, e.g., interleukin-1 (IL-1), IL-6, tumor necrosis factor (TNF) α and interferon (IFN) α; O&NS-induced muscle fatigue; activation of the Toll-Like Receptor Cycle through pathogen-associated (PAMPs) and damage-associated (DAMPs) molecular patterns, including heat shock proteins; altered glutaminergic and dopaminergic neurotransmission; mitochondrial dysfunctions; and O&NS-induced defects in the sodium-potassium pump. Fatigue is also associated with altered activities in specific brain regions and muscle pathology, such as reductions in maximum voluntary muscle force, downregulation of the mitochondrial biogenesis master gene peroxisome proliferator-activated receptor gamma coactivator 1-alpha, a shift to glycolysis and buildup of toxic metabolites within myocytes. As such, both mental and physical fatigue, which frequently accompany immune-inflammatory and neuro-inflammatory disorders, are the consequence of interactions between multiple systemic and central pathways.
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Affiliation(s)
- Gerwyn Morris
- Tir Na Nog, Bryn Road seaside 87, Llanelli, SA152LW, Wales, UK
| | - Michael Berk
- IMPACT Strategic Research Centre, School of Medicine, Deakin University, P.O. Box 291, Geelong, 3220, Australia.,Orygen Youth Health Research Centre and the Centre of Youth Mental Health, Poplar Road 35, Parkville, 3052, Australia.,The Florey Institute for Neuroscience and Mental Health, University of Melbourne, Kenneth Myer Building, Royal Parade 30, Parkville, 3052, Australia.,Department of Psychiatry, University of Melbourne, Level 1 North, Main Block, Royal Melbourne Hospital, Parkville, 3052, Australia
| | - Piotr Galecki
- Department of Adult Psychiatry, Medical University of Lodz, Lodz, Poland
| | - Ken Walder
- Metabolic Research Unit, Deakin University, Geelong, Australia
| | - Michael Maes
- IMPACT Strategic Research Centre, School of Medicine, Deakin University, P.O. Box 291, Geelong, 3220, Australia. .,Department of Psychiatry, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. .,Health Sciences Graduate Program, Health Sciences Center, State University of Londrina, Londrina, Brazil. .,Impact Strategic Research Center, Deakin University, Geelong, Australia.
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84
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Pannexin‑1 silencing inhibits the proliferation of U87‑MG cells. Mol Med Rep 2015; 11:3487-92. [PMID: 25572468 DOI: 10.3892/mmr.2015.3169] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 07/23/2014] [Indexed: 11/05/2022] Open
Abstract
Pannexin‑1 (Panx‑1) is abundantly expressed in vertebrates and has been shown to assemble into high‑conductance single‑membrane channels, which are permeable to large molecules and regulate cellular function. However, the association between Panx‑1 and astrocyte proliferation is poorly understood. This study provides evidence for a difference in cell proliferation between wild‑type and Panx‑1‑knockdown cells. Proliferation of the U87‑MG malignant glioma cell line was reduced following transfection with Panx‑1‑short interfering RNA. In addition, treatment with the Panx‑1 activator, adenosine triphosphate, significantly reduced cell proliferation at 48 h in Panx‑1‑knockdown cells compared with wild type cells. In conclusion, on the basis of the present findings, Panx‑1 is likely to be important in the regulation of U87‑MG cell proliferation. This provides further support for the hypothesis that there is a correlation between Panx‑1 expression and U87‑MG cell proliferation.
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85
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Orellana JA, Busso D, Ramírez G, Campos M, Rigotti A, Eugenín J, von Bernhardi R. Prenatal nicotine exposure enhances Cx43 and Panx1 unopposed channel activity in brain cells of adult offspring mice fed a high-fat/cholesterol diet. Front Cell Neurosci 2014; 8:403. [PMID: 25520621 PMCID: PMC4251442 DOI: 10.3389/fncel.2014.00403] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 11/08/2014] [Indexed: 01/06/2023] Open
Abstract
Nicotine, the most important neuroteratogen of tobacco smoke, can reproduce brain and cognitive disturbances per se when administered prenatally. However, it is still unknown if paracrine signaling among brain cells participates in prenatal nicotine-induced brain impairment of adult offspring. Paracrine signaling is partly mediated by unopposed channels formed by connexins hemichannels (HCs) and pannexins serving as aqueous pores permeable to ions and small signaling molecules, allowing exchange between the intra- and extracellular milieus. Our aim was to address whether prenatal nicotine exposure changes the activity of those channels in adult mice offspring under control conditions or subjected to a second challenge during young ages: high-fat/cholesterol (HFC) diet. To induce prenatal exposure to nicotine, osmotic minipumps were implanted in CF1 pregnant mice at gestational day 5 to deliver nicotine bitartrate or saline (control) solutions. After weaning, offspring of nicotine-treated or untreated pregnant mice were fed ad libitum with chow or HFC diets for 8 weeks. The functional state of connexin 43 (Cx43) and pannexin 1 (Panx1) unopposed channels was evaluated by dye uptake experiments in hippocampal slices from 11-week-old mice. We found that prenatal nicotine increased the opening of Cx43 HCs in astrocytes, and Panx1 channels in microglia and neurons only if offspring mice were fed with HFC diet. Blockade of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX2) and prostaglandin E receptor 1 (EP1), ionotropic ATP receptor type 7 (P2X7) and NMDA receptors, showed differential inhibition of prenatal nicotine-induced channel opening in glial cells and neurons. Importantly, inhibition of the above mentioned enzymes and receptors, or blockade of Cx43 and Panx1 unopposed channels greatly reduced adenosine triphosphate (ATP) and glutamate release from hippocampal slices of prenatally nicotine-exposed offspring. We propose that unregulated gliotransmitter release through Cx43 and Panx1 unopposed channels may participate in brain alterations observed in offspring of mothers exposed to tobacco smoke during pregnancy.
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Affiliation(s)
- Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Dolores Busso
- Departamento de Nutrición, Diabetes y Metabolismo, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile ; Centro de Nutrición Molecular y Enfermedades Crónicas, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Gigliola Ramírez
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Marlys Campos
- Laboratorio de Sistemas Neurales, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile Santiago, Chile
| | - Attilio Rigotti
- Departamento de Nutrición, Diabetes y Metabolismo, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile ; Centro de Nutrición Molecular y Enfermedades Crónicas, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Jaime Eugenín
- Laboratorio de Sistemas Neurales, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile Santiago, Chile
| | - Rommy von Bernhardi
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
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Morgun AV, Malinovskaya NA, Komleva YK, Lopatina OL, Kuvacheva NV, Panina YA, Taranushenko TY, Solonchuk YR, Salmina AB. STRUCTURAL AND FUNCTIONAL HETEROGENEITY OF ASTROCYTES IN THE BRAIN: ROLE IN NEURODEGENERATION AND NEUROINFLAMMATION. BULLETIN OF SIBERIAN MEDICINE 2014. [DOI: 10.20538/1682-0363-2014-5-138-148] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The review covers the current concepts on structural and functional heterogeneity of brain astrocytes that serve for numerous (patho)physiological processes in the central nervous system. Astrocytes from various subpopulations demonstrate different sensitivity to the action of pathogenic factors, varied behaviors in reactive processes and within the local immune response. Key functions of astrocytes like neurogenesis, neuron-astroglia metabolic coupling, glial control of local blood flow greatly depend on the origin and characteristics of astroglial cells. Changes at the initial stages of neurodegeneration or in neurodevelopmental disorders are associated with significant alterations in astroglial structural and functional properties, thus suggesting new approaches to therapeutic strategies implementing astroglia-expressing molecules and targets for effective
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Affiliation(s)
- A. V. Morgun
- V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk
| | | | - Yu. K Komleva
- V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk
| | - O. L. Lopatina
- V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk
| | - N. V. Kuvacheva
- V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk
| | - Yu. A. Panina
- V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk
| | | | - Yu. R. Solonchuk
- V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk
| | - A. B. Salmina
- V.F. Voino-Yasenetsky Krasnoyarsk State Medical University, Krasnoyarsk
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87
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Triggering of protection mechanism against Phoneutria nigriventer spider venom in the brain. PLoS One 2014; 9:e107292. [PMID: 25211468 PMCID: PMC4161398 DOI: 10.1371/journal.pone.0107292] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 08/11/2014] [Indexed: 01/03/2023] Open
Abstract
Severe accidents caused by the "armed" spider Phoneutria nigriventer cause neurotoxic manifestations in victims. In experiments with rats, P. nigriventer venom (PNV) temporarily disrupts the properties of the BBB by affecting both the transcellular and the paracellular route. However, it is unclear how cells and/or proteins participate in the transient opening of the BBB. The present study demonstrates that PNV is a substrate for the multidrug resistance protein-1 (MRP1) in cultured astrocyte and endothelial cells (HUVEC) and increases mrp1 and cx43 and down-regulates glut1 mRNA transcripts in cultured astrocytes. The inhibition of nNOS by 7-nitroindazole suggests that NO derived from nNOS mediates some of these effects by either accentuating or opposing the effects of PNV. In vivo, MRP1, GLUT1 and Cx43 protein expression is increased differentially in the hippocampus and cerebellum, indicating region-related modulation of effects. PNV contains a plethora of Ca(2+), K(+) and Na(+) channel-acting neurotoxins that interfere with glutamate handling. It is suggested that the findings of the present study are the result of a complex interaction of signaling pathways, one of which is the NO, which regulates BBB-associated proteins in response to PNV interference on ions physiology. The present study provides additional insight into PNV-induced BBB dysfunction and shows that a protective mechanism is activated against the venom. The data shows that PNV has qualities for potential use in drug permeability studies across the BBB.
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88
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Gutierrez-Murgas Y, Snowden JN. Ventricular shunt infections: immunopathogenesis and clinical management. J Neuroimmunol 2014; 276:1-8. [PMID: 25156073 DOI: 10.1016/j.jneuroim.2014.08.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/17/2014] [Accepted: 08/06/2014] [Indexed: 12/22/2022]
Abstract
Ventricular shunts are the most common neurosurgical procedure performed in the United States. This hydrocephalus treatment is often complicated by infection of the device with biofilm-forming bacteria. In this review, we discuss the pathogenesis of shunt infection, as well as the implications of the biofilm formation on treatment and prevention of these infections. Many questions remain, including the contribution of glia and the impact of inflammation on developmental outcomes following infection. Immune responses within the CNS must be carefully regulated to contain infection while minimizing bystander damage; further study is needed to design optimal treatment strategies for these patients.
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Affiliation(s)
- Yenis Gutierrez-Murgas
- Department of Pathology & Microbiology, University of Nebraska Medical Center, 985900 Nebraska Medical Center, Omaha, NE 68198-5900, USA.
| | - Jessica N Snowden
- Department of Pathology & Microbiology, University of Nebraska Medical Center, 985900 Nebraska Medical Center, Omaha, NE 68198-5900, USA; Department of Pediatrics, University of Nebraska Medical Center, 985900 Nebraska Medical Center, Omaha, NE 68198-5900, USA.
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89
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Actin filament reorganization in astrocyte networks is a key functional step in neuroinflammation resulting in persistent pain: novel findings on network restoration. Neurochem Res 2014; 40:372-9. [PMID: 24952067 DOI: 10.1007/s11064-014-1363-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 06/09/2014] [Accepted: 06/13/2014] [Indexed: 10/25/2022]
Abstract
In recent years, the importance of glial cell activation in the generation and maintenance of long-term pain has been investigated. One novel mechanism underlying long-lasting pain is injury-induced inflammation in the periphery, followed by microglial activation in the dorsal horn of the spinal cord, which results in local neuroinflammation. An increase in neuronal excitability may follow, with intense signaling along the pain tracts to the thalamus and the parietal cortex along with other cortical regions for the identification and recognition of the injury. If the local neuroinflammation develops into a pathological state, then the astrocytes become activated. Previous studies in which lipopolysaccharide (LPS) was used to induce inflammation have shown that in a dysfunctional astrocyte network, the actin cytoskeleton is reorganized from the normally occurring F-actin stress fibers into the more diffusible, disorganized, ring-form globular G-actin. In addition, Ca(2+) signaling systems are altered, Na(+)- and glutamate transporters are downregulated, and pro-inflammatory cytokines, particularly IL-1β, are released in dysfunctional astrocyte networks. In a series of experiments, we have demonstrated that these LPS-induced changes in astrocyte function can be restored by stimulation of Gi/o and inhibition of Gs with a combination of a μ-receptor agonist and ultralow concentrations of a μ-receptor antagonist and by inhibition of cytokine release, particularly IL-1β, by the antiepileptic drug levetiracetam. These findings could be of clinical significance and indicate a novel treatment for long-term pain.
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90
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Filiou MD, Arefin AS, Moscato P, Graeber MB. 'Neuroinflammation' differs categorically from inflammation: transcriptomes of Alzheimer's disease, Parkinson's disease, schizophrenia and inflammatory diseases compared. Neurogenetics 2014; 15:201-12. [PMID: 24928144 DOI: 10.1007/s10048-014-0409-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/02/2014] [Indexed: 12/30/2022]
Abstract
'Neuroinflammation' has become a widely applied term in the basic and clinical neurosciences but there is no generally accepted neuropathological tissue correlate. Inflammation, which is characterized by the presence of perivascular infiltrates of cells of the adaptive immune system, is indeed seen in the central nervous system (CNS) under certain conditions. Authors who refer to microglial activation as neuroinflammation confuse this issue because autoimmune neuroinflammation serves as a synonym for multiple sclerosis, the prototypical inflammatory disease of the CNS. We have asked the question whether a data-driven, unbiased in silico approach may help to clarify the nomenclatorial confusion. Specifically, we have examined whether unsupervised analysis of microarray data obtained from human cerebral cortex of Alzheimer's, Parkinson's and schizophrenia patients would reveal a degree of relatedness between these diseases and recognized inflammatory conditions including multiple sclerosis. Our results using two different data analysis methods provide strong evidence against this hypothesis demonstrating that very different sets of genes are involved. Consequently, the designations inflammation and neuroinflammation are not interchangeable. They represent different categories not only at the histophenotypic but also at the transcriptomic level. Therefore, non-autoimmune neuroinflammation remains a term in need of definition.
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Affiliation(s)
- Michaela D Filiou
- Max Planck Institute of Psychiatry, Kraepelinstraße 2, 80804, Munich, Germany
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91
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Ultrafine carbon black induces glutamate and ATP release by activating connexin and pannexin hemichannels in cultured astrocytes. Toxicology 2014; 323:32-41. [PMID: 24932759 DOI: 10.1016/j.tox.2014.06.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/21/2014] [Accepted: 06/11/2014] [Indexed: 12/22/2022]
Abstract
Ultrafine particles could enter central nervous system and were associated with brain damage. The underlying mechanisms have not been fully elucidated. Glutamate and ATP are important signaling molecules in brain physiology and pathology. We investigated whether ultrafine carbon black (ufCB) could regulate the release of glutamate and ATP from cultured cortical astrocytes and the involvement of hemichannels in the release mechanism. Our results showed that ufCB dose-dependently increased glutamate and ATP release and activated hemichannels in astrocytes. ufCB-activated hemichannels were attributed to the activation of both connexin 43 (Cx43) and pannexin1 (Panx1) hemichannels, which was based on the finding of increased protein expression and distribution on cell surface of Cx43 and Panx1, and the inhibiting effects of hemichannel inhibitor carbenoxolone, Cx43 hemichannel inhibitor (43)Gap27 and Panx1 hemichannel inhibitor (10)Panx1 on hemichannel activation. Furthermore, ufCB-induced glutamate and ATP release were dependent on Cx43 and Panx1 hemichannels, because carbenoxolone and (43)Gap27 inhibited ufCB-induced glutamate and ATP release, and (10)Panx1 inhibited ufCB-induced ATP release. Taken together, we demonstrated, for the first time, that ufCB could induce glutamate and ATP release by activating Cx43 and Panx1 hemchannels in astrocytes. Our findings suggest a novel mechanism for neurotoxicity caused by ultrafine particles.
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92
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Castellano P, Eugenin EA. Regulation of gap junction channels by infectious agents and inflammation in the CNS. Front Cell Neurosci 2014; 8:122. [PMID: 24847208 PMCID: PMC4023065 DOI: 10.3389/fncel.2014.00122] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 04/17/2014] [Indexed: 01/04/2023] Open
Abstract
Gap junctions (GJs) are conglomerates of intercellular channels that connect the cytoplasm of two or more cells, and facilitate the transfer of ions and small molecules, including second messengers, resulting in metabolic and electrical coordination. In general, loss of gap junctional communication (GJC) has been associated with cellular damage and inflammation resulting in compromise of physiological functions. Recently, it has become evident that GJ channels also play a critical role in the pathogenesis of infectious diseases and associated inflammation. Several pathogens use the transfer of intracellular signals through GJ channels to spread infection and toxic signals that amplify inflammation to neighboring cells. Thus, identification of the mechanisms by which several infectious agents alter GJC could result in new potential therapeutic approaches to reduce inflammation and their pathogenesis.
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Affiliation(s)
- Paul Castellano
- Public Health Research Institute (PHRI), New Jersey Medical School, Rutgers The State University of New Jersey Newark, NJ, USA ; Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers The State University of New Jersey Newark, NJ, USA
| | - Eliseo A Eugenin
- Public Health Research Institute (PHRI), New Jersey Medical School, Rutgers The State University of New Jersey Newark, NJ, USA ; Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers The State University of New Jersey Newark, NJ, USA
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93
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De Bock M, Decrock E, Wang N, Bol M, Vinken M, Bultynck G, Leybaert L. The dual face of connexin-based astroglial Ca(2+) communication: a key player in brain physiology and a prime target in pathology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2211-32. [PMID: 24768716 DOI: 10.1016/j.bbamcr.2014.04.016] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/11/2014] [Accepted: 04/12/2014] [Indexed: 12/21/2022]
Abstract
For decades, studies have been focusing on the neuronal abnormalities that accompany neurodegenerative disorders. Yet, glial cells are emerging as important players in numerous neurological diseases. Astrocytes, the main type of glia in the central nervous system , form extensive networks that physically and functionally connect neuronal synapses with cerebral blood vessels. Normal brain functioning strictly depends on highly specialized cellular cross-talk between these different partners to which Ca(2+), as a signaling ion, largely contributes. Altered intracellular Ca(2+) levels are associated with neurodegenerative disorders and play a crucial role in the glial responses to injury. Intracellular Ca(2+) increases in single astrocytes can be propagated toward neighboring cells as intercellular Ca(2+) waves, thereby recruiting a larger group of cells. Intercellular Ca(2+) wave propagation depends on two, parallel, connexin (Cx) channel-based mechanisms: i) the diffusion of inositol 1,4,5-trisphosphate through gap junction channels that directly connect the cytoplasm of neighboring cells, and ii) the release of paracrine messengers such as glutamate and ATP through hemichannels ('half of a gap junction channel'). This review gives an overview of the current knowledge on Cx-mediated Ca(2+) communication among astrocytes as well as between astrocytes and other brain cell types in physiology and pathology, with a focus on the processes of neurodegeneration and reactive gliosis. Research on Cx-mediated astroglial Ca(2+) communication may ultimately shed light on the development of targeted therapies for neurodegenerative disorders in which astrocytes participate. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.
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Affiliation(s)
- Marijke De Bock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium.
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mélissa Bol
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mathieu Vinken
- Department of Toxicology, Center for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, B-1090 Brussels, Belgium
| | - Geert Bultynck
- Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signalling, KULeuven, Campus Gasthuisberg O/N-I bus 802, B-3000 Leuven, Belgium
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
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Burkovetskaya M, Karpuk N, Xiong J, Bosch M, Boska MD, Takeuchi H, Suzumura A, Kielian T. Evidence for aberrant astrocyte hemichannel activity in Juvenile Neuronal Ceroid Lipofuscinosis (JNCL). PLoS One 2014; 9:e95023. [PMID: 24736558 PMCID: PMC3988164 DOI: 10.1371/journal.pone.0095023] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 03/23/2014] [Indexed: 12/14/2022] Open
Abstract
Juvenile Neuronal Ceroid Lipofuscinosis (JNCL) is a lysosomal storage disease caused by an autosomal recessive mutation in CLN3 that leads to vision loss, progressive cognitive and motor decline, and premature death. Morphological evidence of astrocyte activation occurs early in the disease process and coincides with regions where neuronal loss eventually ensues. However, the consequences of CLN3 mutation on astrocyte function remain relatively ill-defined. Astrocytes play a critical role in CNS homeostasis, in part, by their ability to regulate the extracellular milieu via the formation of extensive syncytial networks coupled by gap junction (GJ) channels. In contrast, unopposed hemichannels (HCs) have been implicated in CNS pathology by allowing the non-discriminant passage of molecules between the intracellular and extracellular milieus. Here we examined acute brain slices from CLN3 mutant mice (CLN3Δex7/8) to determine whether CLN3 loss alters the balance of GJ and HC activity. CLN3Δex7/8 mice displayed transient increases in astrocyte HC opening at postnatal day 30 in numerous brain regions, compared to wild type (WT) animals; however, HC activity steadily decreased at postnatal days 60 and 90 in CLN3Δex7/8 astrocytes to reach levels lower than WT cells. This suggested a progressive decline in astrocyte function, which was supported by significant reductions in glutamine synthetase, GLAST, and connexin expression in CLN3Δex7/8 mice compared to WT animals. Based on the early increase in astrocyte HC activity, CLN3Δex7/8 mice were treated with the novel carbenoxolone derivative INI-0602 to inhibit HCs. Administration of INI-0602 for a one month period significantly reduced lysosomal ceroid inclusions in the brains of CLN3Δex7/8 mice compared to WT animals, which coincided with significant increases in astrocyte GJ communication and normalization of astrocyte resting membrane potential to WT levels. Collectively, these findings suggest that alterations in astrocyte communication may impact the progression of JNCL and could offer a potential therapeutic target.
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Affiliation(s)
- Maria Burkovetskaya
- Departments of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Nikolay Karpuk
- Departments of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Juan Xiong
- Departments of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Megan Bosch
- Departments of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Michael D. Boska
- Department of Radiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Hideyuki Takeuchi
- Department of Neuroimmunology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Akio Suzumura
- Department of Neuroimmunology, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | - Tammy Kielian
- Departments of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- * E-mail:
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Shen N, Mo LQ, Hu F, Chen PX, Guo RX, Feng JQ. A novel role of spinal astrocytic connexin 43: mediating morphine antinociceptive tolerance by activation of NMDA receptors and inhibition of glutamate transporter-1 in rats. CNS Neurosci Ther 2014; 20:728-36. [PMID: 24629168 DOI: 10.1111/cns.12244] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 01/30/2014] [Accepted: 02/09/2014] [Indexed: 01/03/2023] Open
Abstract
AIMS Connexin 43 (Cx43) has been reported to be involved in neuropathic pain, but whether it contributes to morphine antinociceptive tolerance remains unknown. The present study investigated the role of spinal Cx43 in the development of morphine tolerance and its mechanisms in rats. METHODS Morphine tolerance was induced by intrathecal (i.t.) administration of morphine (15 μg) daily for seven consecutive days. The analgesia effect was assessed by hot-water tail-flick test. Expression of proteins was detected by Western blot and immunohistochemistry assay. RESULTS Chronic morphine markedly increased the expression of spinal Cx43. Gap26, a specific Cx43 mimic peptide, attenuated not only morphine antinociceptive tolerance, but also the up-regulation of spinal Cx43 expression, the activation of astrocytes, and N-methyl-D-aspartic acid (NMDA) receptors (NR1 and NR2B subunits), as well as the decreased GLT-1 expression induced by chronic morphine. MK-801, a noncompetitive NMDA receptors antagonist, suppressed the chronic morphine-induced spinal Cx43 up-regulation, astrocytes activation and decline of GLT-1 expression. CONCLUSIONS The spinal astrocytic Cx43 contributes to the development of morphine antinociceptive tolerance by activating astrocytes and NMDA receptors, and inhibiting GLT-1 expression. We also demonstrate that the role of interaction between the spinal astrocytic Cx43 and neuronal NMDA receptors is important in morphine tolerant rats.
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Affiliation(s)
- Ning Shen
- Department of Physiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
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96
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Bou Saab J, Losa D, Chanson M, Ruez R. Connexins in respiratory and gastrointestinal mucosal immunity. FEBS Lett 2014; 588:1288-96. [PMID: 24631537 DOI: 10.1016/j.febslet.2014.02.059] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 02/27/2014] [Accepted: 02/27/2014] [Indexed: 12/18/2022]
Abstract
The mucosal lining forms the physical and chemical barrier that protects against pathogens and hostile particles and harbors its own population of bacteria, fungi and archea, known as the microbiota. The immune system controls tolerance of this population of microorganisms that have proven to be beneficial for its host. Keeping its physical integrity and a correct balance with the microbiota, the mucosa preserves its homeostasis and its protective function and maintains host's health. However, in some conditions, pathogens may succeed in breaching mucosal homeostasis and successfully infecting the host. In this review we will discuss the role the mucosa plays in the defense against bacterial pathogens by considering the gap junction protein connexins. We will detail their implication in mucosal homeostasis and upon infection with bacteria in the respiratory and the gastrointestinal tracts.
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Affiliation(s)
- Joanna Bou Saab
- Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Davide Losa
- Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Marc Chanson
- Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
| | - Richard Ruez
- Geneva University Hospitals and University of Geneva, Geneva, Switzerland
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Cui Y, Masaki K, Yamasaki R, Imamura S, Suzuki SO, Hayashi S, Sato S, Nagara Y, Kawamura MF, Kira JI. Extensive dysregulations of oligodendrocytic and astrocytic connexins are associated with disease progression in an amyotrophic lateral sclerosis mouse model. J Neuroinflammation 2014; 11:42. [PMID: 24597481 PMCID: PMC4016493 DOI: 10.1186/1742-2094-11-42] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 02/25/2014] [Indexed: 11/17/2022] Open
Abstract
Background Non-cell-autonomous motor neuronal death is suggested in a mutant Cu/Zn superoxide dismutase 1 (mSOD1)-mediated amyotrophic lateral sclerosis (ALS) model, in which glial cells play significant roles in disease progression. Connexins (Cxs) form homotypic or heterotypic gap junctions (GJs) and allow direct intercellular communications among nervous tissue cells. The role of Cxs in motor neuron disease has never been investigated; therefore, we aimed to evaluate alterations of Cxs in mSOD1-transgenic (mSOD1-Tg) mice in comparison with their non-transgenic (non-Tg) littermates at the same ages. Methods We pathologically evaluated temporal changes to astrocytic Cx43/Cx30 and oligodendrocytic Cx47/Cx32 immunoreactivities at presymptomatic, disease-progressive, and end stages, relative to aquaporin-4 (AQP4), glial fibrillary acidic protein (GFAP), excitatory amino acid transporter-2 (EAAT2), myelin-oligodendrocyte glycoprotein (MOG), and Nogo-A immunoreactivities, and observed neuronal loss by NeuN and neurofilament immunostaining, and microglial response by Iba-1 immunostaining. We also performed quantitative immunoblotting and real-time PCR analyses for Cxs. Results The mSOD1-Tg mice showed neuronal and axonal loss in the anterior horns of the lumbar spinal cord accompanied by increased activation of microglia compared with non-Tg mice at the disease-progressive and end stages. Expression patterns of Cxs were not different between mSOD1-Tg and non-Tg mice at the presymptomatic stage, but immunoreactivities for GFAP, Cx43, Cx30 and AQP4 were increased in the anterior horns of mSOD1-Tg mice at the disease-progressive and end stages. By contrast, Cx47 and Cx32 immunoreactivities were markedly diminished in Nogo-A-positive oligodendrocytes in the anterior horns of mSOD1-Tg mice at the disease-progressive and end stages, especially in oligodendrocytes showing SOD1 accumulation. EAAT2 immunoreactivity was also diminished in the anterior horns of mSOD1-Tg mice at the disease-progressive and end stages. Quantitative immunoblotting revealed a significant reduction in Cx47 and Cx32 protein levels in mSOD1-Tg mice at the disease-progressive and end stages. The levels of Cx47 and Cx32 mRNAs were also decreased at these stages. Conclusions Our findings indicate that oligodendrocytic and astrocytic GJ proteins in the anterior horns of spinal cord in mSOD1-Tg mice are profoundly affected at the disease-progressive and end stages, where disruption of GJs among glial cells may exacerbate motor neuronal death.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Jun-ichi Kira
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
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98
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McClain J, Grubišić V, Fried D, Gomez-Suarez RA, Leinninger GM, Sévigny J, Parpura V, Gulbransen BD. Ca2+ responses in enteric glia are mediated by connexin-43 hemichannels and modulate colonic transit in mice. Gastroenterology 2014; 146:497-507.e1. [PMID: 24211490 PMCID: PMC3935238 DOI: 10.1053/j.gastro.2013.10.061] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 10/18/2013] [Accepted: 10/30/2013] [Indexed: 12/17/2022]
Abstract
BACKGROUND & AIMS In the enteric nervous system, neurotransmitters initiate changes in calcium (Ca(2+) responses) in glia, but it is not clear how this process affects intestinal function. We investigated whether Ca(2+)-mediated responses in enteric glia are required to maintain gastrointestinal function. METHODS We used in situ Ca(2+) imaging to monitor glial Ca(2+) responses, which were manipulated with pharmacologic agents or via glia-specific disruption of the gene encoding connexin-43 (Cx43) (hGFAP::CreER(T2+/-)/Cx43(f/f) mice). Gastrointestinal function was assessed based on pellet output, total gut transit, colonic bead expulsion, and muscle tension recordings. Proteins were localized and quantified by immunohistochemistry, immunoblot, and reverse transcription polymerase chain reaction analyses. RESULTS Ca(2+) responses in enteric glia of mice were mediated by Cx43 hemichannels. Cx43 immunoreactivity was confined to enteric glia within the myenteric plexus of the mouse colon; the Cx43 inhibitors carbenoxolone and 43Gap26 inhibited the ability of enteric glia to propagate Ca(2+) responses. In vivo attenuation of Ca(2+) responses in the enteric glial network slowed gut transit overall and delayed colonic transit--these changes are also observed during normal aging. Altered motility with increasing age was associated with reduced glial Ca(2+)-mediated responses and changes in glial expression of Cx43 messenger RNA and protein. CONCLUSIONS Ca(2+)-mediated responses in enteric glia regulate gastrointestinal function in mice. Altered intercellular signaling between enteric glia and neurons might contribute to motility disorders.
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Affiliation(s)
- Jonathon McClain
- Neuroscience Program and Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824 USA
| | - Vladimir Grubišić
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy and Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL 35294, USA
| | - David Fried
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824
| | - Roberto A Gomez-Suarez
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy and Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL 35294, USA.,Department of Pediatrics Division of Pediatric Gastroenterology Hepatology And Nutrition at Nemours Chlidren's Hospital. Orlando, FL 32827, USA
| | - Gina M Leinninger
- Neuroscience Program and Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824 USA
| | - Jean Sévigny
- Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada.,Centre de recherche du CHU de Québec, Québec, QC, G1V 4G2 Canada
| | - Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy and Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL 35294, USA.,Department of Biotechnology, University of Rijeka, 51000 Rijeka, Croatia
| | - Brian D Gulbransen
- Neuroscience Program and Department of Physiology, Michigan State University, 567 Wilson Road, East Lansing, MI, 48824 USA
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Eugenin EA. Role of connexin/pannexin containing channels in infectious diseases. FEBS Lett 2014; 588:1389-95. [PMID: 24486013 DOI: 10.1016/j.febslet.2014.01.030] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 01/20/2014] [Accepted: 01/21/2014] [Indexed: 12/12/2022]
Abstract
In recent years it has become evident that gap junctions and hemichannels, in concert with extracellular ATP and purinergic receptors, play key roles in several physiological processes and pathological conditions. However, only recently has their importance in infectious diseases been explored, likely because early reports indicated that connexin containing channels were completely inactivated under inflammatory conditions, and therefore no further research was performed. However, recent evidence indicates that several infectious agents take advantage of these communication systems to enhance inflammation and apoptosis, as well as to participate in the infectious cycle of several pathogens. In the current review, we will discuss the role of these channels/receptors in the pathogenesis of several infectious diseases and the possibilities of generating novel therapeutic approaches to reduce or prevent these diseases.
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Affiliation(s)
- Eliseo A Eugenin
- Public Health Research Institute (PHRI), Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ, USA; Department of Microbiology and Molecular Genetics, Rutgers New Jersey Medical School, Rutgers The State University of New Jersey, Newark, NJ, USA.
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100
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Astrocytes and microglia in acute cerebral injury underlying cerebral palsy associated with preterm birth. Pediatr Res 2014; 75:234-40. [PMID: 24336433 DOI: 10.1038/pr.2013.188] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 07/11/2013] [Indexed: 02/06/2023]
Abstract
Cerebral palsy is one of the most devastating consequences of brain injury around the time of birth, and nearly a third of cases are now associated with premature birth. Compared with term babies, preterm babies have an increased incidence of complications that may increase the risk of disability, such as intraventricular hemorrhage, periventricular leukomalacia, sepsis, and necrotizing enterocolitis. The response to injury is highly dependent on brain maturity, and although cellular vulnerability is well documented, there is now evidence that premyelinating axons are also particularly sensitive to ischemic injury. In this review, we will explore recent evidence highlighting a central role for glia in mediating increased risk of disability in premature infants, including excessive activation of microglia and opening of astrocytic gap junction hemichannels in spreading injury after brain ischemia, in part likely involving release of adenosine triphosphate (ATP) and overactivation of purinergic receptors, particularly in white matter. We propose the hypothesis that inflammation-induced opening of connexin hemichannels is a key regulating event that initiates a vicious circle of excessive ATP release, which in turn propagates activation of purinergic receptors on microglia and astrocytes. This suggests that developing effective neuroprotective strategies for preterm infants requires a detailed understanding of glial responses.
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