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Funaki M, Nio-Kobayashi J, Suzuki R, Bando Y. Galectin-3 Plays a Role in Neuroinflammation in the Visual Pathway in Experimental Optic Neuritis. Cells 2024; 13:612. [PMID: 38607051 PMCID: PMC11011492 DOI: 10.3390/cells13070612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/18/2024] [Accepted: 03/30/2024] [Indexed: 04/13/2024] Open
Abstract
Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) featuring numerous neuropathologies, including optic neuritis (ON) in some patients. However, the molecular mechanisms of ON remain unknown. Galectins, β-galactoside-binding lectins, are involved in various pathophysiological processes. We previously showed that galectin-3 (gal-3) is associated with the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of MS. In the current study, we investigated the expression of gal-3 in the visual pathway in EAE mice to clarify its role in the pathogenesis of ON. Immunohistochemical analysis revealed upregulation of gal-3 in the visual pathway of the EAE mice during the peak stage of the disease, compared with naïve and EAE mice during the chronic stage. Gal-3 was detected mainly in microglia/macrophages and astrocytes in the visual pathway in EAE mice. In addition, gal-3+/Iba-1+ cells, identified as phagocytic by immunostaining for cathepsin D, accumulated in demyelinating lesions in the visual pathway during the peak disease stage of EAE. Moreover, NLRP3 expression was detected in most gal-3+/Iba-1+ cells. These results strongly suggest that gal-3 regulates NLRP3 signaling in microglia/macrophages and neuroinflammatory demyelination in ON. In astrocytes, gal-3 was expressed from the peak to the chronic disease stages. Taken together, our findings suggest a critical role of gal-3 in the pathogenesis of ON. Thus, gal-3 in glial cells may serve as a potential therapeutic target for ON.
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Affiliation(s)
- Masako Funaki
- Department of Anatomy, Akita University Graduate School of Medicine, Akita 010-8543, Japan
| | - Junko Nio-Kobayashi
- Department of Functional Glycobiology in Infectious Diseases, National Research Center for the Control and Prevention of Infectious Diseases, Nagasaki University, Nagasaki 852-8523, Japan
| | - Ryoji Suzuki
- Department of Anatomy, Akita University Graduate School of Medicine, Akita 010-8543, Japan
| | - Yoshio Bando
- Department of Anatomy, Akita University Graduate School of Medicine, Akita 010-8543, Japan
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Pitts KM, Margeta MA. Myeloid masquerade: Microglial transcriptional signatures in retinal development and disease. Front Cell Neurosci 2023; 17:1106547. [PMID: 36779012 PMCID: PMC9909491 DOI: 10.3389/fncel.2023.1106547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 01/12/2023] [Indexed: 01/27/2023] Open
Abstract
Microglia are dynamic guardians of neural tissue and the resident immune cells of the central nervous system (CNS). The disease-associated microglial signature (DAM), also known as the microglial neurodegenerative phenotype (MGnD), has gained significant attention in recent years as a fundamental microglial response common to various neurodegenerative disease pathologies. Interestingly, this signature shares many features in common with developmental microglia, suggesting the existence of recycled gene programs which play a role both in early neural circuit formation as well as in response to aging and disease. In addition, recent advances in single cell RNA sequencing have revealed significant heterogeneity within the original DAM signature, with contributions from both yolk sac-derived microglia as well as bone marrow-derived macrophages. In this review, we examine the role of the DAM signature in retinal development and disease, highlighting crosstalk between resident microglia and infiltrating monocytes which may critically contribute to the underlying mechanisms of age-related neurodegeneration.
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Affiliation(s)
- Kristen M. Pitts
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
- Schepens Eye Research Institute of Mass, Eye and Ear, Boston, MA, United States
| | - Milica A. Margeta
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, United States
- Schepens Eye Research Institute of Mass, Eye and Ear, Boston, MA, United States
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Ju WY, Wang Q, Song LJ, Ding ZB, Li XH, Kumar G, Yan Y, Ma CG. Drug-induced microglial phagocytosis in multiple sclerosis and experimental autoimmune encephalomyelitis and the underlying mechanisms. Mol Biol Rep 2023; 50:749-59. [PMID: 36309614 DOI: 10.1007/s11033-022-07968-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 09/21/2022] [Indexed: 02/01/2023]
Abstract
Microglia are resident macrophages of the central nervous system (CNS). It plays a significant role in immune surveillance under physiological conditions. On stimulation by pathogens, microglia change their phenotypes, phagocytize toxic molecules, secrete pro-inflammatory/anti-inflammatory factors, promotes tissue repair, and maintain the homeostasis in CNS. Accumulation of myelin debris in multiple sclerosis (MS)/experimental autoimmune encephalomyelitis (EAE) inhibits remyelination by decreasing the phagocytosis by microglia and prevent the recovery of MS/EAE. Drug induced microglia phagocytosis could be a novel therapeutic intervention for the treatment of MS/EAE. But the abnormal phagocytosis of neurons and synapses by activated microglia will lead to neuronal damage and degeneration. It indicates that the phagocytosis of microglia has many beneficial and harmful effects in central neurodegenerative diseases. Therefore, simply promoting or inhibiting the phagocytic activity of microglia may not achieve ideal therapeutic results. However, limited reports are available to elucidate the microglia mediated phagocytosis and its underlying molecular mechanisms. On this basis, the present review describes microglia-mediated phagocytosis, drug-induced microglia phagocytosis, molecular mechanism, and novel approach for MS/EAE treatment.
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Rotshenker S. Galectin-3 (MAC-2) controls phagocytosis and macropinocytosis through intracellular and extracellular mechanisms. Front Cell Neurosci 2022; 16:949079. [PMID: 36274989 PMCID: PMC9581057 DOI: 10.3389/fncel.2022.949079] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 09/05/2022] [Indexed: 11/29/2022] Open
Abstract
Galectin-3 (Gal-3; formally named MAC-2) is a β-galactoside-binding lectin. Various cell types produce Gal-3 under either normal conditions and/or pathological conditions. Gal-3 can be present in cells' nuclei and cytoplasm, secreted from producing cells, and associated with cells' plasma membranes. This review focuses on how Gal-3 controls phagocytosis and macropinocytosis. Intracellular and extracellular Gal-3 promotes the phagocytosis of phagocytic targets/cargo (e.g., tissue debris and apoptotic cells) in “professional phagocytes” (e.g., microglia and macrophages) and “non-professional phagocytes” (e.g., Schwann cells and astrocytes). Intracellularly, Gal-3 promotes phagocytosis by controlling the “eat me” signaling pathways that phagocytic receptors generate, directing the cytoskeleton to produce the mechanical forces that drive the structural changes on which phagocytosis depends, protrusion and then retraction of filopodia and lamellipodia as they, respectively, engulf and then internalize phagocytic targets. Extracellularly, Gal-3 promotes phagocytosis by functioning as an opsonin, linking phagocytic targets to phagocytic receptors, activating them to generate the “eat me” signaling pathways. Macropinocytosis is a non-selective endocytic mechanism that various cells use to internalize the bulk of extracellular fluid and included materials/cargo (e.g., dissolved nutrients, proteins, and pathogens). Extracellular and intracellular Gal-3 control macropinocytosis in some types of cancer. Phagocytosed and macropinocytosed targets/cargo that reach lysosomes for degradation may rupture lysosomal membranes. Damaged lysosomal membranes undergo either repair or removal by selective autophagy (i.e., lysophagy) that intracellular Gal-3 controls.
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Chaudhary S, Chaudhary S, Rawat S, Kulkarni A, Bilgrami AL, Perveen A, Alghamdi BS, Zughaibi TA, Ashraf GM, Alam MZ, Hussain T. Galectins—Potential Therapeutic Targets for Neurodegenerative Disorders. Int J Mol Sci 2022; 23:11012. [PMID: 36232314 PMCID: PMC9569834 DOI: 10.3390/ijms231911012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 11/17/2022] Open
Abstract
Advancements in medicine have increased the longevity of humans, resulting in a higher incidence of chronic diseases. Due to the rise in the elderly population, age-dependent neurodegenerative disorders are becoming increasingly prevalent. The available treatment options only provide symptomatic relief and do not cure the underlying cause of the disease. Therefore, it has become imperative to discover new markers and therapies to modulate the course of disease progression and develop better treatment options for the affected individuals. Growing evidence indicates that neuroinflammation is a common factor and one of the main inducers of neuronal damage and degeneration. Galectins (Gals) are a class of β-galactoside-binding proteins (lectins) ubiquitously expressed in almost all vital organs. Gals modulate various cellular responses and regulate significant biological functions, including immune response, proliferation, differentiation, migration, and cell growth, through their interaction with glycoproteins and glycolipids. In recent years, extensive research has been conducted on the Gal superfamily, with Gal-1, Gal-3, and Gal-9 in prime focus. Their roles have been described in modulating neuroinflammation and neurodegenerative processes. In this review, we discuss the role of Gals in the causation and progression of neurodegenerative disorders. We describe the role of Gals in microglia and astrocyte modulation, along with their pro- and anti-inflammatory functions. In addition, we discuss the potential use of Gals as a novel therapeutic target for neuroinflammation and restoring tissue damage in neurodegenerative diseases.
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Jansen MI, Thomas Broome S, Castorina A. Exploring the Pro-Phagocytic and Anti-Inflammatory Functions of PACAP and VIP in Microglia: Implications for Multiple Sclerosis. Int J Mol Sci 2022; 23:ijms23094788. [PMID: 35563181 PMCID: PMC9104531 DOI: 10.3390/ijms23094788] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/22/2022] [Accepted: 04/25/2022] [Indexed: 02/04/2023] Open
Abstract
Multiple sclerosis (MS) is a chronic neuroinflammatory and demyelinating disease of the central nervous system (CNS), characterised by the infiltration of peripheral immune cells, multifocal white-matter lesions, and neurodegeneration. In recent years, microglia have emerged as key contributors to MS pathology, acting as scavengers of toxic myelin/cell debris and modulating the inflammatory microenvironment to promote myelin repair. In this review, we explore the role of two neuropeptides, pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP), as important regulators of microglial functioning during demyelination, myelin phagocytosis, and remyelination, emphasising the potential of these neuropeptides as therapeutic targets for the treatment of MS.
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Fan W, Huang W, Chen J, Li N, Mao L, Hou S. Retinal microglia: Functions and diseases. Immunology 2022; 166:268-286. [PMID: 35403700 DOI: 10.1111/imm.13479] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 01/26/2022] [Accepted: 02/22/2022] [Indexed: 11/29/2022] Open
Affiliation(s)
- Wei Fan
- The First Affiliated Hospital of Chongqing Medical University Chongqing China
- Chongqing Key Laboratory of Ophthalmology Chongqing China
- Chongqing Eye Institute Chongqing China
- Chongqing Branch of National Clinical Research Center for Ocular Diseases Chongqing China
| | - Weidi Huang
- The First Affiliated Hospital of Chongqing Medical University Chongqing China
- Department of Ophthalmology, Second Xiangya Hospital Central South University Changsha Hunan China
| | - Jiayi Chen
- The First Affiliated Hospital of Chongqing Medical University Chongqing China
| | - Na Li
- College of Basic Medicine Chongqing Medical University Chongqing China
| | - Liming Mao
- Department of Immunology School of Medicine, Nantong University, 19 Qixiu Road Nantong Jiangsu China
| | - Shengping Hou
- The First Affiliated Hospital of Chongqing Medical University Chongqing China
- Chongqing Key Laboratory of Ophthalmology Chongqing China
- Chongqing Eye Institute Chongqing China
- Chongqing Branch of National Clinical Research Center for Ocular Diseases Chongqing China
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Linares-Alcántara E, Mendlovic F. Scavenger Receptor A1 Signaling Pathways Affecting Macrophage Functions in Innate and Adaptive Immunity. Immunol Invest 2022; 51:1725-1755. [PMID: 34986758 DOI: 10.1080/08820139.2021.2020812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
First discovered on macrophages by Goldstein and Brown in 1979, Scavenger Receptors have since been shown to participate in a diverse number of cell functions; equally diverse are their structures and the ligands they bind. Macrophage activation is crucial in the outcome of an immune response. SR-A1 is highly abundant on macrophages and recognizes both host- and microorganism-derived molecules that impact processes that are initiated, perpetuated, or modified. This review summarizes the involvement of SR-A1 in both inflammatory and anti-inflammatory responses, the multiple-ligand internalization mechanisms and the diversity of signaling pathways that impact macrophage function and activation. Engagement of SR-A1 results in the stimulation of differential signaling pathways and patterns of cytokine expression, kinetics, magnitude of response and activation status. SR-A1 plays essential roles in phagocytosis and efferocytosis, interacting with other receptors and promoting tolerance in response to apoptotic cell uptake. In cell adhesion, tissue remodeling, and cell migration, SR-A1 signals through different pathways engaging different cytoplasmic motifs. We describe the role of SR-A1 during innate and adaptive immune responses, such as participation in macrophage polarization and interaction with other innate receptors, as well as in antigen uptake, processing, and presentation, regulating T and B cell activation. The dichotomous contribution of SR-A1 on macrophage functions is discussed. A better understanding of the role SR-A1 plays through molecular mechanisms and crosstalk with other receptors may provide insights into developing novel therapeutic strategies to modulate immune responses and immunopathologies.
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Affiliation(s)
- Elizabeth Linares-Alcántara
- Facultad de Ciencias, UNAM, Av. Universidad 3000, Col. Copilco-Universidad, Ciudad de Mexico, Mexico.,Departamento de Microbiología y Parasitología, Facultad de Medicina, UNAM, Av. Universidad 3000, Col. Copilco-Universidad, Ciudad de Mexico, Mexico
| | - Fela Mendlovic
- Departamento de Microbiología y Parasitología, Facultad de Medicina, UNAM, Av. Universidad 3000, Col. Copilco-Universidad, Ciudad de Mexico, Mexico.,Facultad de Ciencias de la Salud, Universidad Anahuac Mexico Norte, Huixquilucan, Mexico
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Xue J, Zhu Y, Liu Z, Lin J, Li Y, Li Y, Zhuo Y. Demyelination of the Optic Nerve: An Underlying Factor in Glaucoma? Front Aging Neurosci 2021; 13:701322. [PMID: 34795572 PMCID: PMC8593209 DOI: 10.3389/fnagi.2021.701322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 10/13/2021] [Indexed: 11/13/2022] Open
Abstract
Neurodegenerative disorders are characterized by typical neuronal degeneration and axonal loss in the central nervous system (CNS). Demyelination occurs when myelin or oligodendrocytes experience damage. Pathological changes in demyelination contribute to neurodegenerative diseases and worsen clinical symptoms during disease progression. Glaucoma is a neurodegenerative disease characterized by progressive degeneration of retinal ganglion cells (RGCs) and the optic nerve. Since it is not yet well understood, we hypothesized that demyelination could play a significant role in glaucoma. Therefore, this study started with the morphological and functional manifestations of demyelination in the CNS. Then, we discussed the main mechanisms of demyelination in terms of oxidative stress, mitochondrial damage, and immuno-inflammatory responses. Finally, we summarized the existing research on the relationship between optic nerve demyelination and glaucoma, aiming to inspire effective treatment plans for glaucoma in the future.
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Affiliation(s)
- Jingfei Xue
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yingting Zhu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Zhe Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jicheng Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yangjiani Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yiqing Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yehong Zhuo
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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Soares LC, Al-Dalahmah O, Hillis J, Young CC, Asbed I, Sakaguchi M, O’Neill E, Szele FG. Novel Galectin-3 Roles in Neurogenesis, Inflammation and Neurological Diseases. Cells 2021; 10:3047. [PMID: 34831271 PMCID: PMC8618878 DOI: 10.3390/cells10113047] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 12/16/2022] Open
Abstract
Galectin-3 (Gal-3) is an evolutionarily conserved and multifunctional protein that drives inflammation in disease. Gal-3's role in the central nervous system has been less studied than in the immune system. However, recent studies show it exacerbates Alzheimer's disease and is upregulated in a large variety of brain injuries, while loss of Gal-3 function can diminish symptoms of neurodegenerative diseases such as Alzheimer's. Several novel molecular pathways for Gal-3 were recently uncovered. It is a natural ligand for TREM2 (triggering receptor expressed on myeloid cells), TLR4 (Toll-like receptor 4), and IR (insulin receptor). Gal-3 regulates a number of pathways including stimulation of bone morphogenetic protein (BMP) signaling and modulating Wnt signalling in a context-dependent manner. Gal-3 typically acts in pathology but is now known to affect subventricular zone (SVZ) neurogenesis and gliogenesis in the healthy brain. Despite its myriad interactors, Gal-3 has surprisingly specific and important functions in regulating SVZ neurogenesis in disease. Gal-1, a similar lectin often co-expressed with Gal-3, also has profound effects on brain pathology and adult neurogenesis. Remarkably, Gal-3's carbohydrate recognition domain bears structural similarity to the SARS-CoV-2 virus spike protein necessary for cell entry. Gal-3 can be targeted pharmacologically and is a valid target for several diseases involving brain inflammation. The wealth of molecular pathways now known further suggest its modulation could be therapeutically useful.
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Affiliation(s)
- Luana C. Soares
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, South Parks Road, Oxford OX1 3QX, UK; (L.C.S.); (I.A.)
- Department of Oncology, University of Oxford, Oxford OX1 3QX, UK;
| | - Osama Al-Dalahmah
- Irving Medical Center, Columbia University, New York, NY 10032, USA;
| | - James Hillis
- Massachusets General Hospital, Harvard Medical School, 15 Parkman Street, Boston, MA 02114, USA;
| | - Christopher C. Young
- Department of Neurological Surgery, University of Washington, 325 Ninth Avenue, Seattle, WA 98104, USA;
| | - Isaiah Asbed
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, South Parks Road, Oxford OX1 3QX, UK; (L.C.S.); (I.A.)
| | - Masanori Sakaguchi
- International Institute for Integrative Sleep Medicine, University of Tsukuba, Tsukuba 305-8575, Japan;
| | - Eric O’Neill
- Department of Oncology, University of Oxford, Oxford OX1 3QX, UK;
| | - Francis G. Szele
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, South Parks Road, Oxford OX1 3QX, UK; (L.C.S.); (I.A.)
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Sanchez-Molina P, Almolda B, Benseny-Cases N, González B, Perálvarez-Marín A, Castellano B. Specific microglial phagocytic phenotype and decrease of lipid oxidation in white matter areas during aging: Implications of different microenvironments. Neurobiol Aging 2021; 105:280-295. [PMID: 34139605 DOI: 10.1016/j.neurobiolaging.2021.03.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 03/25/2021] [Accepted: 03/28/2021] [Indexed: 12/25/2022]
Abstract
Physiological aging is characterized by an imbalance of pro-inflammatory and anti-inflammatory mediators leading to neuroinflammation. Microglial cells, which are highly regulated by the local microenvironment, undergo specific changes depending upon the brain area during aging. The aim of this study was to evaluate the influence of age over microglial cells along different brain areas and microenvironments. For this purpose, transgenic mice with overproduction of either the anti-inflammatory IL-10 cytokine or the pro-inflammatory IL-6 cytokine were used. Our results show that, during aging, microglial cells located in white matter (WM) areas maintain their phagocytic capacity but present a specific phagocytic phenotype with receptors involved in myelin recognition, arguing for aging-derived myelin damage. Whereas IL-10 overproduction anticipates the age-related microglial phagocytic phenotype, maintaining it over time, IL-6 overproduction exacerbates this phenotype in aging. These modifications were linked with a higher efficiency of myelin engulfment by microglia in aged transgenic animals. Moreover, we show, in a novel way, lower lipid oxidation during aging in WM areas, regardless of the genotype. The novelty of the insights presented in this study open a window to deeply investigate myelin lipid oxidation and the role of microglial cells in its regulation during physiological aging.
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Affiliation(s)
- Paula Sanchez-Molina
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Beatriz Almolda
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
| | - Núria Benseny-Cases
- ALBA Synchrotron Light Source, Carrer de la Llum 2-26, Cerdanyola del Vallès, Catalonia, Spain
| | - Berta González
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
| | - Alex Perálvarez-Marín
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Department of Biochemistry and Molecular Biology. Universitat Autònoma de Barcelona, Bellaterra, Catalonia, Spain
| | - Bernardo Castellano
- Institute of Neurosciences, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain; Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain
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Abstract
INTRODUCTION Microglia is the resident tissue macrophages of the central nervous system. Prolonged microglial activation often occurs after traumatic brain injury and is associated with deteriorating neurocognitive outcomes. Resolution of microglial activation is associated with limited tissue loss and improved neurocognitive outcomes. Limiting the prolonged pro-inflammatory response and the associated secondary tissue injury provides the rationale and scientific premise for considering microglia as a therapeutic target. AREAS COVERED In this review, we discuss markers of microglial activation, such as immunophenotype and microglial response to injury, including cytokine/chemokine release, free radical formation, morphology, phagocytosis, and metabolic shifts. We compare the origin and role in neuroinflammation of microglia and monocytes/macrophages. We review potential therapeutic targets to shift microglial polarization. Finally, we review the effect of cell therapy on microglia. EXPERT OPINION Dysregulated microglial activation after neurologic injury, such as traumatic brain injury, can worsen tissue damage and functional outcomes. There are potential targets in microglia to attenuate this activation, such as proteins and molecules that regulate microglia polarization. Cellular therapeutics that limit, but do not eliminate, the inflammatory response have improved outcomes in animal models by reducing pro-inflammatory microglial activation via secondary signaling. These findings have been replicated in early phase clinical trials.
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Affiliation(s)
- M Collins Scott
- Department of Pediatric Surgery, University of Texas Health Science Center at Houston (Uthealth), USA
| | - Supinder S Bedi
- Department of Pediatric Surgery, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Scott D Olson
- Department of Pediatric Surgery, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Candice M Sears
- Department of Pediatric Surgery, University of Texas Medical School at Houston, Houston, Texas, USA
| | - Charles S Cox
- Department of Pediatric Surgery, University of Texas Medical School at Houston, Houston, Texas, USA
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Tan Y, Zheng Y, Xu D, Sun Z, Yang H, Yin Q. Galectin-3: a key player in microglia-mediated neuroinflammation and Alzheimer's disease. Cell Biosci 2021; 11:78. [PMID: 33906678 PMCID: PMC8077955 DOI: 10.1186/s13578-021-00592-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 04/20/2021] [Indexed: 12/12/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common cause of dementia and is characterized by the deposition of extracellular aggregates of amyloid-β (Aβ), the formation of intraneuronal tau neurofibrillary tangles and microglial activation-mediated neuroinflammation. One of the key molecules involved in microglial activation is galectin-3 (Gal-3). In recent years, extensive studies have dissected the mechanisms by which Gal-3 modulates microglial activation, impacting Aβ deposition, in both animal models and human studies. In this review article, we focus on the emerging role of Gal-3 in biology and pathobiology, including its origin, its functions in regulating microglial activation and neuroinflammation, and its emergence as a biomarker in AD and other neurodegenerative diseases. These aspects are important to elucidate the involvement of Gal-3 in AD pathogenesis and may provide novel insights into the use of Gal-3 for AD diagnosis and therapy.
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Affiliation(s)
- Yinyin Tan
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, 250021, Shandong, China
| | - Yanqun Zheng
- Department of Neurology, The Dongshan Hospital of Linyi, Linyi, 276017, Shandong, China
| | - Daiwen Xu
- Department of Neurology, The People Hospital of Huaiyin Jinan, Jinan, 250021, Shandong, China
| | - Zhanfang Sun
- Department of Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, 250021, Shandong, China
| | - Huan Yang
- Department of Radiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, 250021, Shandong, China
| | - Qingqing Yin
- Department of Geriatric Neurology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, 250021, Shandong, China.
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Nazareth L, St John J, Murtaza M, Ekberg J. Phagocytosis by Peripheral Glia: Importance for Nervous System Functions and Implications in Injury and Disease. Front Cell Dev Biol 2021; 9:660259. [PMID: 33898462 PMCID: PMC8060502 DOI: 10.3389/fcell.2021.660259] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 03/17/2021] [Indexed: 12/30/2022] Open
Abstract
The central nervous system (CNS) has very limited capacity to regenerate after traumatic injury or disease. In contrast, the peripheral nervous system (PNS) has far greater capacity for regeneration. This difference can be partly attributed to variances in glial-mediated functions, such as axon guidance, structural support, secretion of growth factors and phagocytic activity. Due to their growth-promoting characteristic, transplantation of PNS glia has been trialed for neural repair. After peripheral nerve injuries, Schwann cells (SCs, the main PNS glia) phagocytose myelin debris and attract macrophages to the injury site to aid in debris clearance. One peripheral nerve, the olfactory nerve, is unique in that it continuously regenerates throughout life. The olfactory nerve glia, olfactory ensheathing cells (OECs), are the primary phagocytes within this nerve, continuously clearing axonal debris arising from the normal regeneration of the nerve and after injury. In contrast to SCs, OECs do not appear to attract macrophages. SCs and OECs also respond to and phagocytose bacteria, a function likely critical for tackling microbial invasion of the CNS via peripheral nerves. However, phagocytosis is not always effective; inflammation, aging and/or genetic factors may contribute to compromised phagocytic activity. Here, we highlight the diverse roles of SCs and OECs with the focus on their phagocytic activity under physiological and pathological conditions. We also explore why understanding the contribution of peripheral glia phagocytosis may provide us with translational strategies for achieving axonal regeneration of the injured nervous system and potentially for the treatment of certain neurological diseases.
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Affiliation(s)
- Lynn Nazareth
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia
| | - James St John
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Mariyam Murtaza
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Jenny Ekberg
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
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15
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Abstract
Galectin-3 (Gal-3) is the only member of galectin family able to form pentamers and heterodimers with chemokines. Its presence in various cells and tissues suggests variety of regulatory functions in physiological conditions, but increasing body of evidence indicates involvement of Gal-3 in pathological cascades of many diseases. Gal-3 exerts different, sometimes opposite, effects in various disorders or in different phases of the same disease. These differences in action of Gal-3 are related to the localization of Gal-3 in the cell, types of receptors through which it acts, or the types of cells that secrete it. As a regulator of immune response and T-cell activity, Gal-3 appears to have important role in development of autoimmunity mediated by T cells. Absence of Gal-3 in C57Bl6 mice favors Th2 mediated inflammatory myocarditis but attenuate fibrosis. Recent data also indicate Gal-3 involvement in development atherosclerosis. In pathogenesis of diabetes type 1 and autoimmune components of diabetes type 2 Gal-3 may have detrimental or protective role depending on its intracellular or extracellular localization. Gal-3 mediates autoimmune hepatic damage through activation of T-cells or natural killer T cells. Gal-3 is an important mediator in neurodevelopment, neuropathology and behavior due to its expression both in neurons and glial cells. All together, assessing the role of Gal-3 in immunopathology and autoimmunity it could be concluded that it is an important participant in pathogenesis, as well as promising monitoring marker and therapeutic target.
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Affiliation(s)
- Ivan M Srejovic
- University of Kragujevac, Faculty of Medical Sciences, Department of Physiology, Svetozara Markovica 69, 34000, Kragujevac, Serbia.
| | - Miodrag L Lukic
- University of Kragujevac, Faculty of Medical Sciences, Department of Physiology, Svetozara Markovica 69, 34000, Kragujevac, Serbia; University of Kragujevac, Faculty of Medical Sciences, Center for Molecular Medicine and Stem Cell Research, Svetozara Markovica 69, 34000, Kragujevac, Serbia.
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16
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Borucki DM, Toutonji A, Couch C, Mallah K, Rohrer B, Tomlinson S. Complement-Mediated Microglial Phagocytosis and Pathological Changes in the Development and Degeneration of the Visual System. Front Immunol 2020; 11:566892. [PMID: 33072106 PMCID: PMC7541817 DOI: 10.3389/fimmu.2020.566892] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/17/2020] [Indexed: 12/21/2022] Open
Abstract
The focus of this review is the role of complement-mediated phagocytosis in retinal and neurological diseases affecting the visual system. Complement activation products opsonize synaptic material on neurons for phagocytic removal, which is a normal physiological process during development, but a pathological process in several neurodegenerative diseases and conditions. We discuss the role of complement in the refinement and elimination of synapses in the retina and lateral geniculate nucleus, both during development and in disease states. How complement and aberrant phagocytosis promotes injury to the visual system is discussed primarily in the context of multiple sclerosis, where it has been extensively studied, although the role of complement in visual dysfunction in other diseases such as stroke and traumatic brain injury is also highlighted. Retinal diseases are also covered, with a focus on glaucoma and age-related macular degeneration. Finally, we discuss the potential of complement inhibitory strategies to treat diseases affecting the visual system.
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Affiliation(s)
- Davis M. Borucki
- Medical Scientist Training Program, Medical University of South Carolina, Charleston, SC, United States
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, United States
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC, United States
| | - Amer Toutonji
- Medical Scientist Training Program, Medical University of South Carolina, Charleston, SC, United States
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, United States
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC, United States
| | - Christine Couch
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, United States
- Department of Health Sciences and Research, College of Health Professions, Medical University of South Carolina, Charleston, SC, United States
| | - Khalil Mallah
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, United States
| | - Baerbel Rohrer
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC, United States
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, United States
- Ralph H. Johnson VA Medical Center, Charleston, SC, United States
| | - Stephen Tomlinson
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, United States
- Ralph H. Johnson VA Medical Center, Charleston, SC, United States
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17
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Abstract
During development, oligodendrocytes contact and wrap neuronal axons with myelin. Similarly to neurons and synapses, excess myelin sheaths are produced and selectively eliminated, but how elimination occurs is unknown. Microglia, the resident immune cells of the central nervous system, engulf surplus neurons and synapses. To determine whether microglia also prune myelin sheaths, we used zebrafish to visualize and manipulate interactions between microglia, oligodendrocytes, and neurons during development. We found that microglia closely associate with oligodendrocytes and specifically phagocytose myelin sheaths. By using a combination of optical, genetic, chemogenetic, and behavioral approaches, we reveal that neuronal activity bidirectionally balances microglial association with neuronal cell bodies and myelin phagocytosis in the optic tectum. Furthermore, multiple strategies to deplete microglia resulted in oligodendrocytes maintaining excessive and ectopic myelin. Our work reveals a neuronal activity-regulated role for microglia in modifying developmental myelin targeting by oligodendrocytes.
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Affiliation(s)
| | - Bruce Appel
- Department of Pediatrics, Section of Developmental Biology, University of Colorado, Aurora, CO, USA.
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18
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Martineau É, Arbour D, Vallée J, Robitaille R. Properties of Glial Cell at the Neuromuscular Junction Are Incompatible with Synaptic Repair in the SOD1G37R ALS Mouse Model. J Neurosci 2020; 40:7759-77. [PMID: 32859714 DOI: 10.1523/JNEUROSCI.1748-18.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 08/12/2020] [Accepted: 08/17/2020] [Indexed: 12/17/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting motoneurons (MNs) in a motor-unit (MU)-dependent manner. Glial dysfunction contributes to numerous aspects of the disease. At the neuromuscular junction (NMJ), early alterations in perisynaptic Schwann cell (PSC), glial cells at this synapse, may impact their ability to regulate NMJ stability and repair. Indeed, muscarinic receptors (mAChRs) regulate the repair phenotype of PSCs and are overactivated at disease-resistant NMJs [soleus muscle (SOL)] in SOD1G37R mice. However, it remains unknown whether this is the case at disease-vulnerable NMJs and whether it translates into an impairment of PSC-dependent repair mechanisms. We used SOL and sternomastoid (STM) muscles from SOD1G37R mice and performed Ca2+-imaging to monitor PSC activity and used immunohistochemistry to analyze their repair and phagocytic properties. We show that PSC mAChR-dependent activity was transiently increased at disease-vulnerable NMJs (STM muscle). Furthermore, PSCs from both muscles extended disorganized processes from denervated NMJs and failed to initiate or guide nerve terminal sprouts at disease-vulnerable NMJs, a phenomenon essential for compensatory reinnervation. This was accompanied by a failure of numerous PSCs to upregulate galectin-3 (MAC-2), a marker of glial axonal debris phagocytosis, on NMJ denervation in SOD1 mice. Finally, differences in these PSC-dependent NMJ repair mechanisms were MU type dependent, thus reflecting MU vulnerability in ALS. Together, these results reveal that neuron-glia communication is ubiquitously altered at the NMJ in ALS. This appears to prevent PSCs from adopting a repair phenotype, resulting in a maladapted response to denervation at the NMJ in ALS.SIGNIFICANCE STATEMENT Understanding how the complex interplay between neurons and glial cells ultimately lead to the degeneration of motor neurons and loss of motor function is a fundamental question to comprehend amyotrophic lateral sclerosis (ALS). An early and persistent alteration of glial cell activity takes place at the neuromuscular junction (NMJ), the output of motor neurons, but its impact on NMJ repair remains unknown. Here, we reveal that glial cells at disease-vulnerable NMJs often fail to guide compensatory nerve terminal sprouts and to adopt a phagocytic phenotype on denervated NMJs in SOD1G37R mice. These results show that glial cells at the NMJ elaborate an inappropriate response to NMJ degeneration in a manner that reflects motor-unit (MU) vulnerability and potentially impairs compensatory reinnervation.
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Puigdellívol M, Allendorf DH, Brown GC. Sialylation and Galectin-3 in Microglia-Mediated Neuroinflammation and Neurodegeneration. Front Cell Neurosci 2020; 14:162. [PMID: 32581723 PMCID: PMC7296093 DOI: 10.3389/fncel.2020.00162] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 05/15/2020] [Indexed: 12/31/2022] Open
Abstract
Microglia are brain macrophages that mediate neuroinflammation and contribute to and protect against neurodegeneration. The terminal sugar residue of all glycoproteins and glycolipids on the surface of mammalian cells is normally sialic acid, and addition of this negatively charged residue is known as “sialylation,” whereas removal by sialidases is known as “desialylation.” High sialylation of the neuronal cell surface inhibits microglial phagocytosis of such neurons, via: (i) activating sialic acid receptors (Siglecs) on microglia that inhibit phagocytosis and (ii) inhibiting binding of opsonins C1q, C3, and galectin-3. Microglial sialylation inhibits inflammatory activation of microglia via: (i) activating Siglec receptors CD22 and CD33 on microglia that inhibit phagocytosis and (ii) inhibiting Toll-like receptor 4 (TLR4), complement receptor 3 (CR3), and other microglial receptors. When activated, microglia release a sialidase activity that desialylates both microglia and neurons, activating the microglia and rendering the neurons susceptible to phagocytosis. Activated microglia also release galectin-3 (Gal-3), which: (i) further activates microglia via binding to TLR4 and TREM2, (ii) binds to desialylated neurons opsonizing them for phagocytosis via Mer tyrosine kinase, and (iii) promotes Aβ aggregation and toxicity in vivo. Gal-3 and desialylation may increase in a variety of brain pathologies. Thus, Gal-3 and sialidases are potential treatment targets to prevent neuroinflammation and neurodegeneration.
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Affiliation(s)
- Mar Puigdellívol
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - David H Allendorf
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Guy C Brown
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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20
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Srejovic I, Selakovic D, Jovicic N, Jakovljević V, Lukic ML, Rosic G. Galectin-3: Roles in Neurodevelopment, Neuroinflammation, and Behavior. Biomolecules 2020; 10:biom10050798. [PMID: 32455781 PMCID: PMC7277476 DOI: 10.3390/biom10050798] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/1970] [Revised: 05/09/2020] [Accepted: 05/13/2020] [Indexed: 12/16/2022] Open
Abstract
There is a plethora of evidence to suggest that Galectin-3 plays an important role in normal functions of mammalian cells, as well as in different pathogenic conditions. This review highlights recent data published by researchers, including our own team, on roles of Galectin-3 in the nervous system. Here, we discuss the roles of Galectin-3 in brain development, its roles in glial cells, as well as the interactions of glial cells with other neural and invading cells in pathological conditions. Galectin-3 plays an important role in the pathogenesis of neuroinflammatory and neurodegenerative disorders, such as multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. On the other hand, there is also evidence of the protective role of Galectin-3 due to its anti-apoptotic effect in target cells. Interestingly, genetic deletion of Galectin-3 affects behavioral patterns in maturing and adult mice. The results reviewed in this paper and recent development of highly specific inhibitors suggests that Galectin-3 may be an important therapeutic target in pathological conditions including the disorders of the central nervous system.
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Affiliation(s)
- Ivan Srejovic
- Department of Physiology, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34000 Kragujevac Serbia; (I.S.); (D.S.); (V.J.)
| | - Dragica Selakovic
- Department of Physiology, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34000 Kragujevac Serbia; (I.S.); (D.S.); (V.J.)
| | - Nemanja Jovicic
- Department of Histology and Embryology, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34000 Kragujevac, Serbia;
| | - Vladimir Jakovljević
- Department of Physiology, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34000 Kragujevac Serbia; (I.S.); (D.S.); (V.J.)
- Department of Human Pathology, 1st Moscow State Medical University IM Sechenov, 119146 Moscow, Russia
| | - Miodrag L. Lukic
- Department of Physiology—Molecular Medicine Unit, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34000 Kragujevac, Serbia
- Correspondence: (M.L.L.); (G.R.)
| | - Gvozden Rosic
- Department of Physiology, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34000 Kragujevac Serbia; (I.S.); (D.S.); (V.J.)
- Correspondence: (M.L.L.); (G.R.)
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21
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de Jong CGHM, Gabius HJ, Baron W. The emerging role of galectins in (re)myelination and its potential for developing new approaches to treat multiple sclerosis. Cell Mol Life Sci 2020; 77:1289-317. [PMID: 31628495 DOI: 10.1007/s00018-019-03327-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 09/27/2019] [Accepted: 09/30/2019] [Indexed: 12/12/2022]
Abstract
Multiple sclerosis (MS) is an inflammatory, demyelinating and neurodegenerative disease of the central nervous system with unknown etiology. Currently approved disease-modifying treatment modalities are immunomodulatory or immunosuppressive. While the applied drugs reduce the frequency and severity of the attacks, their efficacy to regenerate myelin membranes and to halt disease progression is limited. To achieve such therapeutic aims, understanding biological mechanisms of remyelination and identifying factors that interfere with remyelination in MS can give respective directions. Such a perspective is given by the emerging functional profile of galectins. They form a family of tissue lectins, which are potent effectors in processes as diverse as adhesion, apoptosis, immune mediator release or migration. This review focuses on endogenous and exogenous roles of galectins in glial cells such as oligodendrocytes, astrocytes and microglia in the context of de- and (re)myelination and its dysregulation in MS. Evidence is arising for a cooperation among family members so that timed expression and/or secretion of galectins-1, -3 and -4 result in modifying developmental myelination, (neuro)inflammatory processes, de- and remyelination. Dissecting the mechanisms that underlie the distinct activities of galectins and identifying galectins as target or tool to modulate remyelination have the potential to contribute to the development of novel therapeutic strategies for MS.
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22
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Smolders SMT, Kessels S, Vangansewinkel T, Rigo JM, Legendre P, Brône B. Microglia: Brain cells on the move. Prog Neurobiol 2019; 178:101612. [PMID: 30954517 DOI: 10.1016/j.pneurobio.2019.04.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 02/13/2019] [Accepted: 04/01/2019] [Indexed: 02/08/2023]
Abstract
In the last decade, tremendous progress has been made in understanding the biology of microglia - i.e. the fascinating immigrated resident immune cell population of the central nervous system (CNS). Recent literature reviews have largely dealt with the plentiful functions of microglia in CNS homeostasis, development and pathology, and the influences of sex and the microbiome. In this review, the intriguing aspect of their physical plasticity during CNS development will get specific attention. Microglia move around (mobility) and reshape their processes (motility). Microglial migration into and inside the CNS is most prominent throughout development and consequently most of the data described in this review concern mobility and motility in the changing environment of the developing brain. Here, we first define microglia based on their highly specialized age- and region-dependent gene expression signature and associated functional heterogeneity. Next, we describe their origin, the migration route of immature microglial cells towards the CNS, the mechanisms underlying their invasion of the CNS, and their spatiotemporal localization and surveying behaviour inside the developing CNS. These processes are dependent on microglial mobility and motility which are determined by the microenvironment of the CNS. Therefore, we further zoom in on the changing environment during CNS development. We elaborate on the extracellular matrix and the respective integrin receptors on microglia and we discuss the purinergic and molecular signalling in microglial mobility. In the last section, we discuss the physiological and pathological functions of microglia in which mobility and motility are involved to stress the importance of microglial 'movement'.
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Affiliation(s)
- Sophie Marie-Thérèse Smolders
- UHasselt, BIOMED, Diepenbeek, Belgium; INSERM, UMR-S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Paris, France; Sorbonne Universités, UPMC Université Paris 06, UM CR18, Neuroscience Paris Seine, Paris, France
| | | | | | | | - Pascal Legendre
- INSERM, UMR-S 1130, CNRS, UMR 8246, Neuroscience Paris Seine, Institute of Biology Paris Seine, Paris, France; Sorbonne Universités, UPMC Université Paris 06, UM CR18, Neuroscience Paris Seine, Paris, France
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23
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Reichert F, Rotshenker S. Galectin-3 (MAC-2) Controls Microglia Phenotype Whether Amoeboid and Phagocytic or Branched and Non-phagocytic by Regulating the Cytoskeleton. Front Cell Neurosci 2019; 13:90. [PMID: 30930748 PMCID: PMC6427835 DOI: 10.3389/fncel.2019.00090] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 02/22/2019] [Indexed: 11/13/2022] Open
Abstract
Myelin surrounding central nervous system (CNS) axons breaks down in multiple sclerosis (MS) and following traumatic axonal injury. Myelin-debris so produced is harmful to repair since it impedes remyelination in MS and the regeneration of traumatized axons. These devastating outcomes are largely due to inefficient removal by phagocytosis of myelin-debris by microglia. Therefore, revealing mechanisms that control phagocytosis is vital. We previously showed that in phagocytosis, filopodia and lamellipodia extend/engulf and then retract/internalize myelin-debris. Moreover, cofilin activates phagocytosis by advancing the remodeling of actin filaments (i.e., existing filaments disassemble and new filaments assemble in a new configuration), causing filopodia/lamellipodia to protrude, and furthermore, Galectin-3 (formally named MAC-2) activates phagocytosis by enhancing K-Ras.GTP/PI3K signaling that leads to actin/myosin-based contraction, causing filopodia/lamellipodia to retract. To understand further how Galectin-3 controls phagocytosis we knocked-down (KD) Galectin-3 expression in cultured primary microglia using Galectin-3 small-hairpin RNA (Gal-3-shRNA). KD Galectin-3 protein levels reduced phagocytosis extensively. Further, inhibiting nucleolin (NCL) and nucleophosmin (NPM), which advance K-Ras signaling as does Galectin-3, also reduced phagocytosis. Strikingly and unexpectedly, knocking down Galectin-3 resulted in a dramatic transformation of microglia morphology from “amoeboid-like” to “branched-like,” rearrangement of actin filaments and inactivation of cofilin. Thus, Galectin-3 may control microglia morphology and phagocytosis by regulating the activation state of cofilin, which, in turn, affects how actin filaments organize and how stable they are. Furthermore, our current and previous findings together suggest that Galectin-3 activates phagocytosis by targeting the cytoskeleton twice: first, by advancing cofilin activation, causing filopodia/lamellipodia to extend/engulf myelin-debris. Second, by advancing actin/myosin-based contraction through K-Ras.GTP/PI3K signaling, causing filopodia/lamellipodia to retract/internalize myelin-debris.
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Affiliation(s)
- Fanny Reichert
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University, Jerusalem, Israel
| | - Shlomo Rotshenker
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hebrew University, Jerusalem, Israel
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24
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Zhao T, Wei X, Yang J, Wang S, Zhang Y. Galactoside-binding lectin in Solen grandis as a pattern recognition receptor mediating opsonization. Fish Shellfish Immunol 2018; 82:183-189. [PMID: 30107261 DOI: 10.1016/j.fsi.2018.08.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 07/31/2018] [Accepted: 08/11/2018] [Indexed: 06/08/2023]
Abstract
Galactoside-binding lectin (galectin) is a type of pathogen recognition molecule that occupies an important position in the invertebrate innate immunity system. Our previous study has identified a galectin gene in mollusk Solen grandis (SgGal-1) and illustrated its potential roles in innate immunity. By the functional study using recombinant protein and specific antibody, here, we confirmed the pivotal roles of SgGal-1 in immune defense of S. grandis. SgGal-1 protein was expressed in many tested tissues including gill, mantle, hepatopancreas and gonad, except hemocytes and muscle. The recombinant SgGal-1 (rSgGal-1) bound PGN and β-glucan instead of LPS in vitro, and it further caused significant agglutination of five different microbes, suggesting SgGal-1 served as a pattern recognition receptor (PRR) involved in immune defense of mollusk. Furthermore, SgGal-1 recruited hemocytes to encapsulate, which was blocked by anti-rSgGal-1 serum. In the meantime, rSgGal-1 as well as promoted the phagocytosis of hemocytes against Escherichia coli in vitro. All these results suggested that SgGal-1 in S. grandis not only acted as a PRR recognizing microbes but also directly participated in the process of immune opsonization to protect the host from pathogenic infection.
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Affiliation(s)
- Tianyu Zhao
- Laboratory of Aquatic Comparative Immunology, School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Xiumei Wei
- Laboratory of Aquatic Comparative Immunology, School of Life Sciences, East China Normal University, Shanghai 200241, China.
| | - Jialong Yang
- Laboratory of Aquatic Comparative Immunology, School of Life Sciences, East China Normal University, Shanghai 200241, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Sheng Wang
- Shandong Marine Resource and Environment Research Institute, Yantai 264006, China
| | - Yu Zhang
- Laboratory of Aquatic Comparative Immunology, School of Life Sciences, East China Normal University, Shanghai 200241, China
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25
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Thomas L, Pasquini LA. Galectin-3-Mediated Glial Crosstalk Drives Oligodendrocyte Differentiation and (Re)myelination. Front Cell Neurosci 2018; 12:297. [PMID: 30258354 PMCID: PMC6143789 DOI: 10.3389/fncel.2018.00297] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 08/17/2018] [Indexed: 12/17/2022] Open
Abstract
Galectin-3 (Gal-3) is the only chimeric protein in the galectin family. Gal-3 structure comprises unusual tandem repeats of proline and glycine-rich short stretches bound to a carbohydrate-recognition domain (CRD). The present review summarizes Gal-3 functions in the extracellular and intracellular space, its regulation and its internalization and secretion, with a focus on the current knowledge of Gal-3 role in central nervous system (CNS) health and disease, particularly oligodendrocyte (OLG) differentiation, myelination and remyelination in experimental models of multiple sclerosis (MS). During myelination, microglia-expressed Gal-3 promotes OLG differentiation by binding glycoconjugates present only on the cell surface of OLG precursor cells (OPC). During remyelination, microglia-expressed Gal-3 favors an M2 microglial phenotype, hence fostering myelin debris phagocytosis through TREM-2b phagocytic receptor and OLG differentiation. Gal-3 is necessary for myelin integrity and function, as evidenced by myelin ultrastructural and behavioral studies from LGALS3-/- mice. Mechanistically, Gal-3 enhances actin assembly and reduces Erk 1/2 activation, leading to early OLG branching. Gal-3 later induces Akt activation and increases MBP expression, promoting gelsolin release and actin disassembly and thus regulating OLG final differentiation. Altogether, findings indicate that Gal-3 mediates the glial crosstalk driving OLG differentiation and (re)myelination and may be regarded as a target in the design of future therapies for a variety of demyelinating diseases.
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Affiliation(s)
- Laura Thomas
- Department of Biological Chemistry, School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina.,Institute of Chemistry and Biological Physicochemistry (IQUIFIB), National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
| | - Laura Andrea Pasquini
- Department of Biological Chemistry, School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina.,Institute of Chemistry and Biological Physicochemistry (IQUIFIB), National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
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Itabashi T, Arima Y, Kamimura D, Higuchi K, Bando Y, Takahashi-Iwanaga H, Murakami M, Watanabe M, Iwanaga T, Nio-Kobayashi J. Cell- and stage-specific localization of galectin-3, a β-galactoside-binding lectin, in a mouse model of experimental autoimmune encephalomyelitis. Neurochem Int 2018; 118:176-84. [PMID: 29920290 DOI: 10.1016/j.neuint.2018.06.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 06/15/2018] [Accepted: 06/15/2018] [Indexed: 12/13/2022]
Abstract
Multiple sclerosis (MS) is an autoimmune disease in which pathogenic T cells play an important role, and an experimental autoimmune encephalomyelitis (EAE) is used as an animal model of MS. Galectins are β-galactoside-binding lectins and involved in various physiological and pathological events. Among fifteen members of galectins, galectin-1, -8, and -9 play immunosuppressive roles in MS and EAE; however, the role of galectin-3 (gal-3) is complex and controversial. We examined expression of gal-3 in the spinal cord and nerve roots of EAE mice. No immunohistochemical signals were detected in naïve mice, whereas gal-3 appeared at lower lumbar levels of the spinal cord and nerve roots in EAE mice. In the spinal cord, gal-3-positive cells were activated microglia and/or infiltrating macrophages, which were round in shape and intensified for the lysosomal enzyme, cathepsin D, indicating elevated phagocytic activity. Gal-3-positive cells in the spinal cord were most abundant during the peak symptomatic period. In the recovery period, they disappeared from the spinal parenchyma but remained at moderate levels in the pia mater. Interestingly, gal-3-positive cells selectively appeared in ventral, but not dorsal, nerve roots running through the spinal canal, with expression peaking during the recovery period. In ventral nerve roots, the major cell type expressing gal-3 was a specific population of Schwann cells that surround unmyelinated axons and express the biosynthetic enzyme for l-serine, a potent neurotrophic amino acid. Gal-3 was also induced in Iba1/F4/80-positive macrophages, which engulf damaged myelin and axon debris. Thus, gal-3 is induced in distinct cell types that are engaged in removal of damaged axons and cell debris and axon regeneration and remyelination, suggesting a potential neuroprotective role of gal-3 in EAE mice.
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Wang HF, Liu XK, Li R, Zhang P, Chu Z, Wang CL, Liu HR, Qi J, Lv GY, Wang GY, Liu B, Li Y, Wang YY. Effect of glial cells on remyelination after spinal cord injury. Neural Regen Res 2017; 12:1724-1732. [PMID: 29171439 PMCID: PMC5696855 DOI: 10.4103/1673-5374.217354] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Remyelination plays a key role in functional recovery of axons after spinal cord injury. Glial cells are the most abundant cells in the central nervous system. When spinal cord injury occurs, many glial cells at the lesion site are immediately activated, and different cells differentially affect inflammatory reactions after injury. In this review, we aim to discuss the core role of oligodendrocyte precursor cells and crosstalk with the rest of glia and their subcategories in the remyelination process. Activated astrocytes influence proliferation, differentiation, and maturation of oligodendrocyte precursor cells, while activated microglia alter remyelination by regulating the inflammatory reaction after spinal cord injury. Understanding the interaction between oligodendrocyte precursor cells and the rest of glia is necessary when designing a therapeutic plan of remyelination after spinal cord injury.
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Affiliation(s)
- Hai-Feng Wang
- Department of Neurosurgery, First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Xing-Kai Liu
- Department of Hepatobiliary and Pancreas Surgery, First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Rui Li
- Hand & Foot Surgery and Reparative & Reconstruction Surgery Center, Second Hospital of Jilin University, Changchun, Jilin Province, China
| | - Ping Zhang
- Department of Hepatobiliary and Pancreas Surgery, First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Ze Chu
- Department of Emergency, First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Chun-Li Wang
- Department of Hepatobiliary and Pancreas Surgery, First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Hua-Rui Liu
- Department of Hepatobiliary and Pancreas Surgery, First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Jun Qi
- Department of Hepatobiliary and Pancreas Surgery, First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Guo-Yue Lv
- Department of Hepatobiliary and Pancreas Surgery, First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Guang-Yi Wang
- Department of Hepatobiliary and Pancreas Surgery, First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Bin Liu
- Department of Cardiology, First Hospital of Jilin University, Changchun, Jilin Province, China
| | - Yan Li
- Department of Surgery, School of Medicine, University of Louisville, Louisville, KY, USA
| | - Yuan-Yi Wang
- Department of Orthopedics, First Hospital of Jilin University, Changchun, Jilin Province, China
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Schmidt C, Frahm C, Schneble N, Müller JP, Brodhun M, Franco I, Witte OW, Hirsch E, Wetzker R, Bauer R. Phosphoinositide 3-Kinase γ Restrains Neurotoxic Effects of Microglia After Focal Brain Ischemia. Mol Neurobiol 2015; 53:5468-79. [PMID: 26452362 DOI: 10.1007/s12035-015-9472-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 10/01/2015] [Indexed: 12/22/2022]
Abstract
Phosphoinositide 3-kinase γ (PI3Kγ) is linked to neuroinflammation and phagocytosis. This study was conducted to elucidate conjectural differences of lipid kinase-dependent and kinase-independent functions of PI3Kγ in the evolvement of brain damage induced by focal cerebral ischemia/reperfusion. Therefore, PI3Kγ wild-type, knockout, and kinase-dead mice were subjected to middle cerebral artery occlusion followed by reperfusion. Tissue damage and cellular composition were assessed by immunohistochemical stainings. In addition, microglial cells derived from respective mouse genotypes were used for analysis of PI3Kγ effects on phagocytic activity, matrix metalloproteinase-9 release, and cAMP content under conditions of oxygen/glucose deprivation and recovery. Brain infarction was more pronounced in PI3Kγ-knockout mice compared to wild-type and kinase-dead mice 48 h after reperfusion. Immunohistochemical analyses revealed a reduced amount of galectin-3/MAC-2-positive microglial cells indicating that activated phagocytosis was reduced in ischemic brains of knockout mice. Cell culture studies disclosed enhanced metalloproteinase-9 secretion in supernatants derived from microglia of PI3Kγ-deficient mice after 2-h oxygen/glucose deprivation and 48-h recovery. Furthermore, PI3Kγ-deficient microglial cells showed a failed phagocytic activation throughout the observed recovery period. Lastly, PI3Kγ-deficient microglia exhibited strongly increased cAMP levels in comparison with wild-type microglia or cells expressing kinase-dead PI3Kγ after oxygen/glucose deprivation and recovery. Our data suggest PI3Kγ kinase activity-independent control of cAMP phosphodiesterase as a crucial mediator of microglial cAMP regulation, MMP-9 expression, and phagocytic activity following focal brain ischemia/recirculation. The suppressive effect of PI3Kγ on cAMP levels appears critical for the restriction of ischemia-induced immune cell functions and in turn tissue damage.
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Affiliation(s)
- Caroline Schmidt
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine, Jena University Hospital, Friedrich Schiller University, Hans-Knöll-Strasse 2, D-07745, Jena, Germany
| | - Christiane Frahm
- Department of Neurology, Jena University Hospital, Jena, Germany
| | - Nadine Schneble
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine, Jena University Hospital, Friedrich Schiller University, Hans-Knöll-Strasse 2, D-07745, Jena, Germany
| | - Jörg P Müller
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine, Jena University Hospital, Friedrich Schiller University, Hans-Knöll-Strasse 2, D-07745, Jena, Germany
| | | | - Irene Franco
- Department of Genetics, Biology, Biochemistry and Molecular Biotechnology Center, University of Torino, Torino, Italy
| | - Otto W Witte
- Department of Neurology, Jena University Hospital, Jena, Germany
| | - Emilio Hirsch
- Department of Genetics, Biology, Biochemistry and Molecular Biotechnology Center, University of Torino, Torino, Italy
| | - Reinhard Wetzker
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine, Jena University Hospital, Friedrich Schiller University, Hans-Knöll-Strasse 2, D-07745, Jena, Germany
| | - Reinhard Bauer
- Institute of Molecular Cell Biology, Center for Molecular Biomedicine, Jena University Hospital, Friedrich Schiller University, Hans-Knöll-Strasse 2, D-07745, Jena, Germany.
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Franco PG, Pasquini LA, Pérez MJ, Rosato-Siri MV, Silvestroff L, Pasquini JM. Paving the way for adequate myelination: The contribution of galectin-3, transferrin and iron. FEBS Lett 2015; 589:3388-95. [PMID: 26296311 DOI: 10.1016/j.febslet.2015.08.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 07/29/2015] [Accepted: 08/11/2015] [Indexed: 12/24/2022]
Abstract
Considering the worldwide incidence of well characterized demyelinating disorders such as Multiple Sclerosis (MS) and the increasing number of pathologies recently found to involve hypomyelinating factors such as micronutrient deficits, elucidating the molecular basis of central nervous system (CNS) demyelination, remyelination and hypomyelination becomes essential to the development of future neuroregenerative therapies. In this context, this review discusses novel findings on the contribution of galectin-3 (Gal-3), transferrin (Tf) and iron to the processes of myelination and remyelination and their potentially positive regulation of oligodendroglial precursor cell (OPC) differentiation. Studies were conducted in cuprizone (CPZ)-induced demyelination and iron deficiency (ID)-induced hypomyelination, and the participation of glial and neural stem cells (NSC) in the remyelination process was evaluated by means of both in vivo and in vitro assays on primary cell cultures.
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Affiliation(s)
- Paula G Franco
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, IQUIFIB-CONICET, Universidad de Buenos Aires, Argentina
| | - Laura A Pasquini
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, IQUIFIB-CONICET, Universidad de Buenos Aires, Argentina
| | - María J Pérez
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, IQUIFIB-CONICET, Universidad de Buenos Aires, Argentina
| | - María V Rosato-Siri
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, IQUIFIB-CONICET, Universidad de Buenos Aires, Argentina
| | - Lucas Silvestroff
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, IQUIFIB-CONICET, Universidad de Buenos Aires, Argentina
| | - Juana M Pasquini
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, IQUIFIB-CONICET, Universidad de Buenos Aires, Argentina.
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Volden TA, Reyelts CD, Hoke TA, Arikkath J, Bonasera SJ. Validation of Flow Cytometry and Magnetic Bead-Based Methods to Enrich CNS Single Cell Suspensions for Quiescent Microglia. J Neuroimmune Pharmacol 2015; 10:655-65. [PMID: 26260923 DOI: 10.1007/s11481-015-9628-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 07/30/2015] [Indexed: 11/29/2022]
Abstract
Microglia are resident mononuclear phagocytes within the CNS parenchyma that intimately interact with neurons and astrocytes to remodel synapses and extracellular matrix. We briefly review studies elucidating the molecular pathways that underlie microglial surveillance, activation, chemotaxis, and phagocytosis; we additionally place these studies in a clinical context. We describe and validate an inexpensive and simple approach to obtain enriched single cell suspensions of quiescent parenchymal and perivascular microglia from the mouse cerebellum and hypothalamus. Following preparation of regional CNS single cell suspensions, we remove myelin debris, and then perform two serial enrichment steps for cells expressing surface CD11b. Myelin depletion and CD11b enrichment are both accomplished using antigen-specific magnetic beads in an automated cell separation system. Flow cytometry of the resultant suspensions shows a significant enrichment for CD11b(+)/CD45(+) cells (perivascular microglia) and CD11b(+)/CD45(-) cells (parenchymal microglia) compared to starting suspensions. Of note, cells from these enriched suspensions minimally express Aif1 (aka Iba1), suggesting that the enrichment process does not evoke significant microglial activation. However, these cells readily respond to a functional challenge (LPS) with significant changes in the expression of molecules specifically associated with microglia. We conclude that methods employing a combination of magnetic-bead based sorting and flow cytometry produce suspensions highly enriched for microglia that are appropriate for a variety of molecular and cellular assays.
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Affiliation(s)
- T A Volden
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - C D Reyelts
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - T A Hoke
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - J Arikkath
- Developmental Neuroscience, Munroe-Meyer Institute for Genetics and Rehabilitation, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - S J Bonasera
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA. .,University of Nebraska Medical Center, 3028 Durham Research Center II, Omaha, NE, 68198-5039, USA.
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Mostacada K, Oliveira FL, Villa-Verde DM, Martinez AM. Lack of galectin-3 improves the functional outcome and tissue sparing by modulating inflammatory response after a compressive spinal cord injury. Exp Neurol 2015; 271:390-400. [PMID: 26183316 DOI: 10.1016/j.expneurol.2015.07.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 07/04/2015] [Accepted: 07/07/2015] [Indexed: 01/21/2023]
Abstract
Spinal cord injury (SCI) is a traumatic event that results in motor, sensitive or autonomic function disturbances, which have direct impact on the life quality of the affected individual. Recent studies have shown that attenuation of the inflammatory response after SCI plays a key role in the reestablishment of motor function. Galectin-3 is a pleiotropic molecule belonging to the carbohydrate-ligand lectin family, which is expressed by different cells in different tissues. Studies have shown that galectin-3 induces the recruitment and activation of neutrophils, monocytes/macrophages, lymphocytes and microglia. Thus, the aim of this study was to evaluate the effects of the lack of galectin-3 on the functional outcome, cellular recruitment and morphological changes in tissue, after SCI. C57BL/6 wild-type and galectin-3 knockout mice were used in this study. A vascular clip was used for 1 min to generate a compressive SCI. By BMS we detected that the Gal-3(-/-) presented a better functional outcome during the studied period. This finding is related to a decrease in the injury length and a higher volume of spared white matter at 7 and 42 days post injury (dpi). Moreover, Gal-3(-/-) mice showed a higher number of spared fibers at 28 dpi. Because of the importance of the inflammatory response after SCI and the role that galectin-3 plays in it, we investigated possible differences in the inflammatory response between the analyzed groups. No differences in neutrophils were observed 24h after injury. However, at 3 dpi, the Gal-3(-/-) mice showed more neutrophils infiltrated into the spinal tissue when compared with the WT mice. At this same time point, no differences in the percentage of the CD11b/Arginase1 positive cells were observed. Remarkably, Gal-3(-/-) mice displayed a decrease in CD11b staining at 7 dpi, compared with the WT mice. At the same time, Gal-3(-/-) mice presented a more prominent Arginase1 stained area, suggesting an anti-inflammatory cell phenotype. Taken together, these results demonstrated that the lack of galectin-3 plays a key role in the inflammatory process triggered by SCI, leading to better and early recovery of locomotor function.
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de Oliveira FL, Gatto M, Bassi N, Luisetto R, Ghirardello A, Punzi L, Doria A. Galectin-3 in autoimmunity and autoimmune diseases. Exp Biol Med (Maywood) 2015; 240:1019-28. [PMID: 26142116 DOI: 10.1177/1535370215593826] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Galectin-3 (gal-3) is a β-galactoside-binding lectin, which regulates cell-cell and extracellular interactions during self/non-self-antigen recognition and cellular activation, proliferation, differentiation, migration and apoptosis. It plays a significant role in cellular and tissue pathophysiology by organizing niches that drive inflammation and immune responses. Gal-3 has some therapeutic potential in several diseases, including chronic inflammatory disorders, cancer and autoimmune diseases. Gal-3 exerts a broad spectrum of functions which differs according to its intra- or extracellular localization. Recombinant gal-3 strategy has been used to identify potential mode of action of gal-3; however, exogenous gal-3 may not reproduce the functions of the endogenous gal-3. Notably, gal-3 induces monocyte-macrophage differentiation, interferes with dendritic cell fate decision, regulates apoptosis on T lymphocytes and inhibits B-lymphocyte differentiation into immunoglobulin secreting plasma cells. Considering the influence of these cell populations in the pathogenesis of several autoimmune diseases, gal-3 seems to play a role in development of autoimmunity. Gal-3 has been suggested as a potential therapeutic agent in patients affected with some autoimmune disorders. However, the precise role of gal-3 in driving the inflammatory process in autoimmune or immune-mediated disorders remains elusive. Here, we reviewed the involvement of gal-3 in cellular and tissue events during autoimmune and immune-mediated inflammatory diseases.
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Affiliation(s)
- Felipe L de Oliveira
- Coimbra Group Fellowship for Latin American Professors, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ CEP 21941-902, Brazil Rheumatology Unit, Department of Medicine, University of Padova, Padova 35128, Italy
| | - Mariele Gatto
- Rheumatology Unit, Department of Medicine, University of Padova, Padova 35128, Italy
| | - Nicola Bassi
- Rheumatology Unit, Department of Medicine, University of Padova, Padova 35128, Italy
| | - Roberto Luisetto
- Rheumatology Unit, Department of Medicine, University of Padova, Padova 35128, Italy
| | - Anna Ghirardello
- Rheumatology Unit, Department of Medicine, University of Padova, Padova 35128, Italy
| | - Leonardo Punzi
- Rheumatology Unit, Department of Medicine, University of Padova, Padova 35128, Italy
| | - Andrea Doria
- Rheumatology Unit, Department of Medicine, University of Padova, Padova 35128, Italy
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Manouchehrian O, Arnér K, Deierborg T, Taylor L. Who let the dogs out?: detrimental role of Galectin-3 in hypoperfusion-induced retinal degeneration. J Neuroinflammation 2015; 12:92. [PMID: 25968897 PMCID: PMC4490716 DOI: 10.1186/s12974-015-0312-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 04/28/2015] [Indexed: 11/30/2022] Open
Abstract
Background Retinal ischemia results in a progressive degeneration of neurons and a pathological activation of glial cells, resulting in vision loss. In the brain, progressive damage after ischemic insult has been correlated to neuroinflammatory processes involving microglia. Galectin-3 has been shown to mediate microglial responses to ischemic injury in the brain. Therefore, we wanted to explore the contribution of Galectin-3 (Gal-3) to hypoperfusion-induced retinal degeneration in mice. Methods Gal-3 knockout (Gal-3 KO) and wildtype (WT) C57BL/6 mice were subjected to chronic cerebral hypoperfusion by bilateral narrowing of the common carotid arteries using metal coils resulting in a 30% reduction of blood flow. Sham operated mice served as controls. After 17 weeks, the mice were sacrificed and the eyes were analyzed for retinal architecture, neuronal cell survival, and glial reactivity using morphological staining and immunohistochemistry. Results Hypoperfusion caused a strong increase in Gal-3 expression and microglial activation in WT mice, coupled with severe degenerative damage to all retinal neuronal subtypes, remodeling of the retinal lamination and Müller cell gliosis. In contrast, hypoperfused Gal-3 KO mice displayed a retained laminar architecture, a significant preservation of photoreceptors and ganglion cell neurons, and an attenuation of microglial and Müller cell activation. Conclusion Moderate cerebral blood flow reduction in the mouse results in severe retinal degenerative damage. In mice lacking Gal-3 expression, pathological changes are significantly attenuated. Gal-3 is thereby a potential target for treatment and prevention of hypoperfusion-induced retinal degeneration and a strong candidate for further research as a factor behind retinal degenerative disease. Electronic supplementary material The online version of this article (doi:10.1186/s12974-015-0312-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Oscar Manouchehrian
- Department of Ophthalmology, BMC, Lund University, Klinikgatan 26, Lund, S-22184, Sweden.
| | - Karin Arnér
- Department of Ophthalmology, BMC, Lund University, Klinikgatan 26, Lund, S-22184, Sweden.
| | - Tomas Deierborg
- Experimental Neuroinflammation Laboratory, BMC, Lund University, Klinikgatan 26, Lund, S-22184, Sweden.
| | - Linnéa Taylor
- Department of Ophthalmology, BMC, Lund University, Klinikgatan 26, Lund, S-22184, Sweden.
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Abstract
Galectins are an evolutionarily ancient family of glycan-binding proteins (GBPs) and are found in all animals. Although they were discovered over 30 years ago, ideas about their biological functions continue to evolve. Current evidence indicates that galectins, which are the only known GBPs that occur free in the cytoplasm and extracellularly, are involved in a variety of intracellular and extracellular pathways contributing to homeostasis, cellular turnover, cell adhesion, and immunity. Here we review evolving insights into galectin biology from a historical perspective and explore current evidence regarding biological roles of galectins.
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Wang X, Cao K, Sun X, Chen Y, Duan Z, Sun L, Guo L, Bai P, Sun D, Fan J, He X, Young W, Ren Y. Macrophages in spinal cord injury: phenotypic and functional change from exposure to myelin debris. Glia 2014; 63:635-51. [PMID: 25452166 DOI: 10.1002/glia.22774] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 11/05/2014] [Accepted: 11/12/2014] [Indexed: 01/14/2023]
Abstract
Macrophage activation and persistent inflammation contribute to the pathological process of spinal cord injury (SCI). It was reported that M2 macrophages were induced at 3-7 days after SCI but M2 markers were reduced or eliminated after 1 week. By contrast, M1 macrophage response is rapidly induced and then maintained at injured spinal cord. However, factors that modulate macrophage phenotype and function are poorly understood. We developed a model to distinguish bone-marrow derived macrophages (BMDMs) from residential microglia and explored how BMDMs change their phenotype and functions in response to the lesion-related factors in injured spinal cord. Infiltrating BMDMs expressing higher Mac-2 and lower CX3CR1 migrate to the epicenter of injury, while microglia expressing lower Mac-2 but higher CX3CR1 distribute to the edges of lesion. Myelin debris at the lesion site switches BMDMs from M2 phenotype towards M1-like phenotype. Myelin debris activates ATP-binding cassette transporter A1 (ABCA1) for cholesterol efflux in response to myelin debris loading in vitro. However, this homeostatic mechanism in injured site is overwhelmed, leading to the development of foamy macrophages and lipid plaque in the lesion site. The persistence of these cells indicates a pro-inflammatory environment, associated with enhanced neurotoxicity and impaired wound healing. These foamy macrophages have poor capacity to phagocytose apoptotic neutrophils resulting in uningested neutrophils releasing their toxic contents and further tissue damage. In conclusion, these data demonstrate for the first time that myelin debris generated in injured spinal cord modulates macrophage activation. Lipid accumulation following macrophage phenotype switch contributes to SCI pathology.
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Affiliation(s)
- Xi Wang
- W. M. Keck Center for Collaborative Neuroscience, Rutgers, The State University of New Jersey, New Jersey; Institute of Neurosciences, the Fourth Military Medical University, Xian, China
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Abstract
Microglia, the resident macrophages of the central nervous system, rapidly activate in nearly all kinds of neurological diseases. These activated microglia become highly motile, secreting inflammatory cytokines, migrating to the lesion area, and phagocytosing cell debris or damaged neurons. During the past decades, the secretory property and chemotaxis of microglia have been well-studied, while relatively less attention has been paid to microglial phagocytosis. So far there is no obvious concordance with whether it is beneficial or detrimental in tissue repair. This review focuses on phagocytic phenotype of microglia in neurological diseases such as Alzheimer's disease, multiple sclerosis, Parkinson's disease, traumatic brain injury, ischemic and other brain diseases. Microglial morphological characteristics, involved receptors and signaling pathways, distribution variation along with time and space changes, and environmental factors that affecting phagocytic function in each disease are reviewed. Moreover, a comparison of contributions between macrophages from peripheral circulation and the resident microglia to these pathogenic processes will also be discussed.
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Affiliation(s)
- Ruying Fu
- Department of Neurology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Number 107, Yan Jiang Xi Road, Guangzhou, 510120 Guangdong Province China
| | - Qingyu Shen
- Department of Neurology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Number 107, Yan Jiang Xi Road, Guangzhou, 510120 Guangdong Province China
- Department of Neurology, Zengcheng People’s Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Pengfei Xu
- Department of Neurology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Number 107, Yan Jiang Xi Road, Guangzhou, 510120 Guangdong Province China
| | - Jin Jun Luo
- Department of Neurology, School of Medicine, Temple University, Philadelphia, PA USA
| | - Yamei Tang
- Department of Neurology, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Number 107, Yan Jiang Xi Road, Guangzhou, 510120 Guangdong Province China
- Key Laboratory of Malignant Tumor Gene Regulation and Target Therapy of Guangdong Higher Education Institutes, Sun Yat-Sen University, Guangzhou, China
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Ray A, Basu S, Miller NM, Chan AM, Dittel BN. An increase in tolerogenic dendritic cell and natural regulatory T cell numbers during experimental autoimmune encephalomyelitis in Rras-/- mice results in attenuated disease. J Immunol 2014; 192:5109-17. [PMID: 24771856 PMCID: PMC4041102 DOI: 10.4049/jimmunol.1302254] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
R-Ras is a member of the Ras superfamily of small GTPases, which are regulators of various cellular processes, including adhesion, survival, proliferation, trafficking, and cytokine production. R-Ras is expressed by immune cells and has been shown to modulate dendritic cell (DC) function in vitro and has been associated with liver autoimmunity. We used Rras-deficient mice to study the mechanism whereby R-Ras contributes to autoimmunity using experimental autoimmune encephalomyelitis (EAE), a mouse model of the CNS autoimmune disease multiple sclerosis. We found that a lack of R-Ras in peripheral immune cells resulted in attenuated EAE disease. Further investigation revealed that, during EAE, absence of R-Ras promoted the formation of MHC II(low) DC concomitant with a significant increase in proliferation of natural regulatory T cells, resulting in an increase in their cell numbers in the periphery. Our study suggests a novel role for R-Ras in promoting autoimmunity through negative regulation of natural regulatory T cell numbers by inhibiting the development of MHCII(low) DC with tolerogenic potential.
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Affiliation(s)
- Avijit Ray
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53201
| | - Sreemanti Basu
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53201; Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226; and
| | - Nichole M Miller
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53201
| | - Andrew M Chan
- Division of Hematology and Oncology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Bonnie N Dittel
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53201; Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, WI 53226; and
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Hoyos H, Rinaldi M, Mendez-huergo S, Marder M, Rabinovich G, Pasquini J, Pasquini L. Galectin-3 controls the response of microglial cells to limit cuprizone-induced demyelination. Neurobiol Dis 2014; 62:441-55. [DOI: 10.1016/j.nbd.2013.10.023] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 10/10/2013] [Accepted: 10/23/2013] [Indexed: 11/23/2022] Open
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Hovakimyan M, Meyer A, Lukas J, Luo J, Gudziol V, Hummel T, Rolfs A, Wree A, Witt M. Olfactory deficits in Niemann-Pick type C1 (NPC1) disease. PLoS One 2013; 8:e82216. [PMID: 24391715 PMCID: PMC3877006 DOI: 10.1371/journal.pone.0082216] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 10/24/2013] [Indexed: 01/22/2023] Open
Abstract
Background Niemann-Pick type C disease (NPC) is a rare autosomal recessive lipid storage disease characterized by progressive neurodegeneration. As only a few studies have been conducted on the impact of NPC on sensory systems, we used a mutant mouse model (NPC1−/−) to examine the effects of this disorder to morphologically distinct regions of the olfactory system, namely the olfactory epithelium (OE) and olfactory bulb (OB). Methodology/Principal findings For structural and functional analysis immunohistochemistry, electron microscopy, western blotting, and electrophysiology have been applied. For histochemistry and western blotting, we used antibodies against a series of neuronal and glia marker proteins, as well as macrophage markers. NPC1−/− animals present myelin-like lysosomal deposits in virtually all types of cells of the peripheral and central olfactory system. Especially supporting cells of the OE and central glia cells are affected, resulting in pronounced astrocytosis and microgliosis in the OB and other olfactory cortices. Up-regulation of Galectin-3, Cathepsin D and GFAP in the cortical layers of the OB underlines the critical role and location of the OB as a possible entrance gate for noxious substances. Unmyelinated olfactory afferents of the lamina propria seem less affected than ensheathing cells. Supporting the structural findings, electro-olfactometry of the olfactory mucosa suggests that NPC1−/− animals exhibit olfactory and trigeminal deficits. Conclusions/Significance Our data demonstrate a pronounced neurodegeneration and glia activation in the olfactory system of NPC1−/−, which is accompanied by sensory deficits.
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Affiliation(s)
- Marina Hovakimyan
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
| | - Anja Meyer
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
| | - Jan Lukas
- Albrecht-Kossel Institute for Neuroregeneration, Rostock University Medical Center, Rostock, Germany
| | - Jiankai Luo
- Albrecht-Kossel Institute for Neuroregeneration, Rostock University Medical Center, Rostock, Germany
| | - Volker Gudziol
- Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany
| | - Thomas Hummel
- Department of Otorhinolaryngology, University of Dresden Medical School, Dresden, Germany
| | - Arndt Rolfs
- Albrecht-Kossel Institute for Neuroregeneration, Rostock University Medical Center, Rostock, Germany
| | - Andreas Wree
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
| | - Martin Witt
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
- * E-mail:
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Abstract
The Ras inhibitor S-trans,trans-farnesylthiosalicylic acid (FTS, Salirasib®) interferes with Ras membrane interactions that are crucial for Ras-dependent signaling and cellular transformation. FTS had been successfully evaluated in clinical trials of cancer patients. Interestingly, its effect is mediated by targeting Ras chaperones that serve as key coordinators for Ras proper folding and delivery, thus offering a novel target for cancer therapy. The development of new FTS analogs has revealed that the specific modifications to the FTS carboxyl group by esterification and amidation yielded compounds with improved growth inhibitory activity. When FTS was combined with additional therapeutic agents its activity toward Ras was significantly augmented. FTS should be tested not only in cancer but also for genetic diseases associated with abnormal Ras signaling, as well as for various inflammatory and autoimmune disturbances, where Ras plays a major role. We conclude that FTS has a great potential both as a safe anticancer drug and as a promising immune modulator agent.
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Affiliation(s)
- Yoel Kloog
- Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv, Israel.
| | - Galit Elad-Sfadia
- Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv, Israel
| | - Roni Haklai
- Department of Neurobiology, Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv, Israel
| | - Adam Mor
- Department of Medicine, New York University School of Medicine, New York, New York, USA; Department of Pathology, New York University School of Medicine, New York, New York, USA
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Mukaro VR, Bylund J, Hodge G, Holmes M, Jersmann H, Reynolds PN, Hodge S. Lectins offer new perspectives in the development of macrophage-targeted therapies for COPD/emphysema. PLoS One 2013; 8:e56147. [PMID: 23441163 PMCID: PMC3575470 DOI: 10.1371/journal.pone.0056147] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 01/07/2013] [Indexed: 01/29/2023] Open
Abstract
We have previously shown that the defective ability of alveolar macrophages (AM) to phagocytose apoptotic cells (‘efferocytosis’) in chronic obstructive pulmonary disease/emphysema (COPD) could be therapeutically improved using the C-type lectin, mannose binding lectin (MBL), although the exact mechanisms underlying this effect are unknown. An S-type lectin, galectin-3, is also known to regulate macrophage phenotype and function, via interaction with its receptor CD98. We hypothesized that defective expression of galectin/CD98 would be associated with defective efferocytosis in COPD and that mechanisms would include effects on cytoskeletal remodeling and macrophage phenotype and glutathione (GSH) availability. Galectin-3 was measured by ELISA in BAL from controls, smokers and current/ex-smokers with COPD. CD98 was measured on AM using flow cytometry. We assessed the effects of galectin-3 on efferocytosis, CD98, GSH, actin polymerisation, rac activation, and the involvement of PI3K (using β-actin probing and wortmannin inhibition) in vitro using human AM and/or MH-S macrophage cell line. Significant decreases in BAL galectin-3 and AM CD98 were observed in BAL from both current- and ex-smoker COPD subjects vs controls. Galectin 3 increased efferocytosis via an increase in active GTP bound Rac1. This was confirmed with β-actin probing and the role of PI3K was confirmed using wortmannin inhibition. The increased efferocytosis was associated with increases in available glutathione and expression of CD98. We provide evidence for a role of airway lectins in the failed efferocytosis in COPD, supporting their further investigation as potential macrophage-targeted therapies.
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Affiliation(s)
- Violet R. Mukaro
- Department of Thoracic Medicine, Royal Adelaide Hospital and Lung Research Laboratory, Hanson Institute, Adelaide, South Australia, Australia
| | - Johan Bylund
- Department of Rheumatology and Inflammation Research, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Greg Hodge
- Department of Thoracic Medicine, Royal Adelaide Hospital and Lung Research Laboratory, Hanson Institute, Adelaide, South Australia, Australia
- Department of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - Mark Holmes
- Department of Thoracic Medicine, Royal Adelaide Hospital and Lung Research Laboratory, Hanson Institute, Adelaide, South Australia, Australia
- Department of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - Hubertus Jersmann
- Department of Thoracic Medicine, Royal Adelaide Hospital and Lung Research Laboratory, Hanson Institute, Adelaide, South Australia, Australia
- Department of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - Paul N. Reynolds
- Department of Thoracic Medicine, Royal Adelaide Hospital and Lung Research Laboratory, Hanson Institute, Adelaide, South Australia, Australia
- Department of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - Sandra Hodge
- Department of Thoracic Medicine, Royal Adelaide Hospital and Lung Research Laboratory, Hanson Institute, Adelaide, South Australia, Australia
- Department of Medicine, University of Adelaide, Adelaide, South Australia, Australia
- * E-mail:
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Mietto BS, Jurgensen S, Alves L, Pecli C, Narciso MS, Assunção-Miranda I, Villa-Verde DMS, de Souza Lima FR, de Menezes JRL, Benjamim CF, Bozza MT, Martinez AMB. Lack of galectin-3 speeds Wallerian degeneration by altering TLR and pro-inflammatory cytokine expressions in injured sciatic nerve. Eur J Neurosci 2013; 37:1682-90. [PMID: 23406314 DOI: 10.1111/ejn.12161] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 01/15/2013] [Accepted: 01/17/2013] [Indexed: 02/06/2023]
Abstract
Wallerian degeneration (WD) comprises a series of events that includes activation of non-neuronal cells and recruitment of immune cells, creating an inflammatory milieu that leads to extensive nerve fragmentation and subsequent clearance of the myelin debris, both of which are necessary prerequisites for effective nerve regeneration. Previously, we documented accelerated axon regeneration in animals lacking galectin-3 (Gal-3), a molecule associated with myelin clearance. To clarify the mechanisms underlying this enhanced regeneration, we focus here on the early steps of WD following sciatic nerve crush in Gal-3(-/-) mice. Using an in vivo model of nerve degeneration, we observed that removal of myelin debris is more efficient in Gal-3(-/-) than in wild-type (WT) mice; we next used an in vitro phagocytosis assay to document that the phagocytic potential of macrophages and Schwann cells was enhanced in the Gal-3(-/-) mice. Moreover, both RNA and protein levels for the pro-inflammatory cytokines IL-1β and TNF-α, as well as for Toll-like receptor (TLR)-2 and -4, show robust increases in injured nerves from Gal-3(-/-) mice compared to those from WT mice. Collectively, these data indicate that the lack of Gal-3 results in an augmented inflammatory profile that involves the TLR-cytokine pathway, and increases the phagocytic capacity of Schwann cells and macrophages, which ultimately contributes to speeding the course of WD.
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Affiliation(s)
- Bruno Siqueira Mietto
- Laboratório de Neurodegeneração e Reparo, Programa de Pesquisa em Neurociência Básica e Clínica, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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Starossom SC, Mascanfroni ID, Imitola J, Cao L, Raddassi K, Hernandez SF, Bassil R, Croci DO, Cerliani JP, Delacour D, Wang Y, Elyaman W, Khoury SJ, Rabinovich GA. Galectin-1 deactivates classically activated microglia and protects from inflammation-induced neurodegeneration. Immunity 2012; 37:249-63. [PMID: 22884314 DOI: 10.1016/j.immuni.2012.05.023] [Citation(s) in RCA: 271] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 04/05/2012] [Accepted: 05/01/2012] [Indexed: 12/27/2022]
Abstract
Inflammation-mediated neurodegeneration occurs in the acute and the chronic phases of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Classically activated (M1) microglia are key players mediating this process. Here, we identified Galectin-1 (Gal1), an endogenous glycan-binding protein, as a pivotal regulator of M1 microglial activation that targets the activation of p38MAPK-, CREB-, and NF-κB-dependent signaling pathways and hierarchically suppresses downstream proinflammatory mediators, such as iNOS, TNF, and CCL2. Gal1 bound to core 2 O-glycans on CD45, favoring retention of this glycoprotein on the microglial cell surface and augmenting its phosphatase activity and inhibitory function. Gal1 was highly expressed in the acute phase of EAE, and its targeted deletion resulted in pronounced inflammation-induced neurodegeneration. Adoptive transfer of Gal1-secreting astrocytes or administration of recombinant Gal1 suppressed EAE through mechanisms involving microglial deactivation. Thus, Gal1-glycan interactions are essential in tempering microglial activation, brain inflammation, and neurodegeneration, with critical therapeutic implications for MS.
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Hosmane S, Tegenge MA, Rajbhandari L, Uapinyoying P, Kumar NG, Thakor N, Venkatesan A. Toll/interleukin-1 receptor domain-containing adapter inducing interferon-β mediates microglial phagocytosis of degenerating axons. J Neurosci. 2012;32:7745-7757. [PMID: 22649252 DOI: 10.1523/JNEUROSCI.0203-12.2012] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Following CNS injury, microglial phagocytosis of damaged endogenous tissue is thought to play an important role in recovery and regeneration. Previous work has focused on delineating mechanisms of clearance of neurons and myelin. Little, however, is known of the mechanisms underlying phagocytosis of axon debris. We have developed a novel microfluidic platform that enables coculture of microglia with bundles of CNS axons to investigate mechanisms of microglial phagocytosis of axons. Using this platform, we find that axon degeneration results in the induction of type-1 interferon genes within microglia. Pharmacologic and genetic disruption of Toll/interleukin-1 receptor domain-containing adapter inducing interferon-β (TRIF), a Toll-like receptor adapter protein, blocks induction of the interferon response and inhibits microglial phagocytosis of axon debris in vitro. In vivo, microglial phagocytosis of axons following dorsal root axotomy is impaired in mice in which TRIF has been genetically deleted. Furthermore, we identify the p38 mitogen-activated protein kinase (MAPK) cascade as a signaling pathway downstream of TRIF following axon degeneration and find that inhibition of p38 MAPK by SB203580 (4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)-1H-imidazole) also blocked clearance of axon debris. Finally, we find that TRIF-dependent microglial clearance of unmyelinated axon debris facilitates axon outgrowth. Overall, we provide evidence that TRIF-mediated signaling plays an unexpected role in axonal debris clearance by microglia, thereby facilitating a more permissive environment for axonal outgrowth. Our study has significant implications for the development of novel regenerative and restorative strategies for the many traumatic, neuroinflammatory, and neurodegenerative conditions characterized by CNS axon degeneration.
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Hadas S, Spira M, Hanisch UK, Reichert F, Rotshenker S. Complement receptor-3 negatively regulates the phagocytosis of degenerated myelin through tyrosine kinase Syk and cofilin. J Neuroinflammation 2012; 9:166. [PMID: 22776089 PMCID: PMC3418574 DOI: 10.1186/1742-2094-9-166] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 06/07/2012] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Intact myelin, which normally surrounds axons, breaks down in Wallerian degeneration following axonal injury and during neurodegenerative diseases such as multiple sclerosis. Clearance of degenerated myelin by phagocytosis is essential since myelin impedes repair and exacerbates damage. CR3 (complement receptor-3) is a principal phagocytic receptor in myelin phagocytosis. We studied how tyrosine kinase Syk (spleen tyrosine kinase) and cofilin control phagocytosis of degenerated myelin by CR3 in microglia and macrophages. Syk is a non-receptor tyrosine kinase that CR3 recruits to convey cellular functions. Cofilin is an actin-depolymerizing protein that controls F-actin (filamentous actin) remodeling (i.e., disassembly and reassembly) by shifting between active unphosphorylated and inactive phosphorylated states. RESULTS Syk was continuously activated during prolonged phagocytosis. Phagocytosis increased when Syk activity and expression were reduced, suggesting that normally Syk down regulates CR3-mediated myelin phagocytosis. Levels of inactive p-cofilin (phosphorylated cofilin) decreased transiently during prolonged phagocytosis. In contrast, p-cofilin levels decreased continuously when Syk activity and expression were continuously reduced, suggesting that normally Syk advances the inactive state of cofilin. Observations also revealed inverse relationships between levels of phagocytosis and levels of inactive p-cofilin, suggesting that active unphosphorylated cofilin advances phagocytosis. Active cofilin could advance phagocytosis by promoting F-actin remodeling, which supports the production of membrane protrusions (e.g., filopodia), which, as we also revealed, are instrumental in myelin phagocytosis. CONCLUSIONS CR3 both activates and downregulates myelin phagocytosis at the same time. Activation was previously documented. We presently demonstrate that downregulation is mediated through Syk, which advances the inactive phosphorylated state of cofilin. Self-negative control of phagocytosis by the phagocytic receptor can be useful in protecting phagocytes from excessive phagocytosis (i.e., "overeating") during extended exposure to particles that are destined for ingestion.
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Affiliation(s)
- Smadar Hadas
- Dept. of Medical Neurobiology, IMRIC, Hebrew University Faculty of Medicine, Ein-Kerem, 12272, Jerusalem, 91120, Israel
| | - Maya Spira
- Dept. of Medical Neurobiology, IMRIC, Hebrew University Faculty of Medicine, Ein-Kerem, 12272, Jerusalem, 91120, Israel
- Sheba Medical Center, Ramat-Gan, Israel
| | | | - Fanny Reichert
- Dept. of Medical Neurobiology, IMRIC, Hebrew University Faculty of Medicine, Ein-Kerem, 12272, Jerusalem, 91120, Israel
| | - Shlomo Rotshenker
- Dept. of Medical Neurobiology, IMRIC, Hebrew University Faculty of Medicine, Ein-Kerem, 12272, Jerusalem, 91120, Israel
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Bosse F. Extrinsic cellular and molecular mediators of peripheral axonal regeneration. Cell Tissue Res 2012; 349:5-14. [PMID: 22476657 DOI: 10.1007/s00441-012-1389-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 02/23/2012] [Indexed: 12/11/2022]
Abstract
The ability of injured peripheral nerves to regenerate and reinnervate their original targets is a characteristic feature of the peripheral nervous system (PNS). On the other hand, neurons of the central nervous system (CNS), including retinal ganglion cell (RGC) axons, are incapable of spontaneous regeneration. In the adult PNS, axonal regeneration after injury depends on well-orchestrated cellular and molecular processes that comprise a highly reproducible series of degenerative reactions distal to the site of injury. During this fine-tuned process, named Wallerian degeneration, a remodeling of the distal nerve fragment prepares a permissive microenvironment that permits successful axonal regrowth originating from the proximal nerve fragment. Therefore, a multitude of adjusted intrinsic and extrinsic factors are important for surviving neurons, Schwann cells, macrophages and fibroblasts as well as endothelial cells in order to achieve successful regeneration. The aim of this review is to summarize relevant extrinsic cellular and molecular determinants of successful axonal regeneration in rodents that contribute to the regenerative microenvironment of the PNS.
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Guerrero AR, Uchida K, Nakajima H, Watanabe S, Nakamura M, Johnson WE, Baba H. Blockade of interleukin-6 signaling inhibits the classic pathway and promotes an alternative pathway of macrophage activation after spinal cord injury in mice. J Neuroinflammation 2012; 9:40. [PMID: 22369693 PMCID: PMC3310810 DOI: 10.1186/1742-2094-9-40] [Citation(s) in RCA: 144] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Accepted: 02/27/2012] [Indexed: 12/26/2022] Open
Abstract
Background Recent in vivo and in vitro studies in non-neuronal and neuronal tissues have shown that different pathways of macrophage activation result in cells with different properties. Interleukin (IL)-6 triggers the classically activated inflammatory macrophages (M1 phenotype), whereas the alternatively activated macrophages (M2 phenotype) are anti-inflammatory. The objective of this study was to clarify the effects of a temporal blockade of IL-6/IL-6 receptor (IL-6R) engagement, using an anti-mouse IL-6R monoclonal antibody (MR16-1), on macrophage activation and the inflammatory response in the acute phase after spinal cord injury (SCI) in mice. Methods MR16-1 antibodies versus isotype control antibodies or saline alone were administered immediately after thoracic SCI in mice. SC tissue repair was compared between the two groups by Luxol fast blue (LFB) staining for myelination and immunoreactivity for the neuronal markers growth-associated protein (GAP)-43 and neurofilament heavy 200 kDa (NF-H) and for locomotor function. The expression of T helper (Th)1 cytokines (interferon (IFN)-γ and tumor necrosis factor-α) and Th2 cytokines (IL-4, IL-13) was determined by immunoblot analysis. The presence of M1 (inducible nitric oxide synthase (iNOS)-positive, CD16/32-positive) and M2 (arginase 1-positive, CD206-positive) macrophages was determined by immunohistology. Using flow cytometry, we also quantified IFN-γ and IL-4 levels in neutrophils, microglia, and macrophages, and Mac-2 (macrophage antigen-2) and Mac-3 in M2 macrophages and microglia. Results LFB-positive spared myelin was increased in the MR16-1-treated group compared with the controls, and this increase correlated with enhanced positivity for GAP-43 or NF-H, and improved locomotor Basso Mouse Scale scores. Immunoblot analysis of the MR16-1-treated samples identified downregulation of Th1 and upregulation of Th2 cytokines. Whereas iNOS-positive, CD16/32-positive M1 macrophages were the predominant phenotype in the injured SC of non-treated control mice, MR16-1 treatment promoted arginase 1-positive, CD206-positive M2 macrophages, with preferential localization of these cells at the injury site. MR16-1 treatment suppressed the number of IFN-γ-positive neutrophils, and increased the number of microglia present and their positivity for IL-4. Among the arginase 1-positive M2 macrophages, MR16-1 treatment increased positivity for Mac-2 and Mac-3, suggestive of increased phagocytic behavior. Conclusion The results suggest that temporal blockade of IL-6 signaling after SCI abrogates damaging inflammatory activity and promotes functional recovery by promoting the formation of alternatively activated M2 macrophages.
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Affiliation(s)
- Alexander Rodriguez Guerrero
- Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medical Sciences, University of Fukui, Matsuoka-Shimoaizuki 23, Eiheiji, Fukui 910-1193, Japan
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Abstract
Phagocytosis of apoptotic cells and cellular debris is a critical process of maintaining tissue and immune homeostasis. Defects in the phagocytosis process cause autoimmunity and degenerative diseases. Phagocytosis ligands or "eat-me" signals control the initiation of the process by linking apoptotic cells to receptors on phagocyte surface and triggering signaling cascades for cargo engulfment. Eat-me signals are traditionally identified on a case-by-case basis with challenges, and the identification of their cognate receptors is equally daunting. Here, we identified galectin-3 (Gal-3) as a new MerTK ligand by an advanced dual functional cloning strategy, in which phagocytosis-based functional cloning is combined with receptor-based affinity cloning to directly identify receptor-specific eat-me signal. Gal-3 interaction with MerTK was independently verified by co-immunoprecipitation. Functional analyses showed that Gal-3 stimulated the phagocytosis of apoptotic cells and cellular debris by macrophages and retinal pigment epithelial cells with MerTK activation and autophosphorylation. The Gal-3-mediated phagocytosis was blocked by excessive soluble MerTK extracellular domain and lactose. These results suggest that Gal-3 is a legitimate MerTK-specific eat-me signal. The strategy of dual functional cloning with applicability to other phagocytic receptors will facilitate unbiased identification of their unknown ligands and improve our capacity for therapeutic modulation of phagocytic activity and innate immune response.
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Affiliation(s)
- Nora B Caberoy
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami School of Medicine, Miami, Florida 33136, USA
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Jaarsma D, van der Pluijm I, de Waard MC, Haasdijk ED, Brandt R, Vermeij M, Rijksen Y, Maas A, van Steeg H, Hoeijmakers JH, van der Horst GT. Age-related neuronal degeneration: complementary roles of nucleotide excision repair and transcription-coupled repair in preventing neuropathology. PLoS Genet 2011; 7:e1002405. [PMID: 22174697 DOI: 10.1371/journal.pgen.1002405] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 10/17/2011] [Indexed: 12/11/2022] Open
Abstract
Neuronal degeneration is a hallmark of many DNA repair syndromes. Yet, how DNA damage causes neuronal degeneration and whether defects in different repair systems affect the brain differently is largely unknown. Here, we performed a systematic detailed analysis of neurodegenerative changes in mouse models deficient in nucleotide excision repair (NER) and transcription-coupled repair (TCR), two partially overlapping DNA repair systems that remove helix-distorting and transcription-blocking lesions, respectively, and that are associated with the UV-sensitive syndromes xeroderma pigmentosum (XP) and Cockayne syndrome (CS). TCR–deficient Csa−/− and Csb−/− CS mice showed activated microglia cells surrounding oligodendrocytes in regions with myelinated axons throughout the nervous system. This white matter microglia activation was not observed in NER–deficient Xpa−/− and Xpc−/− XP mice, but also occurred in XpdXPCS mice carrying a point mutation (G602D) in the Xpd gene that is associated with a combined XPCS disorder and causes a partial NER and TCR defect. The white matter abnormalities in TCR–deficient mice are compatible with focal dysmyelination in CS patients. Both TCR–deficient and NER–deficient mice showed no evidence for neuronal degeneration apart from p53 activation in sporadic (Csa−/−, Csb−/−) or highly sporadic (Xpa−/−, Xpc−/−) neurons and astrocytes. To examine to what extent overlap occurs between both repair systems, we generated TCR–deficient mice with selective inactivation of NER in postnatal neurons. These mice develop dramatic age-related cumulative neuronal loss indicating DNA damage substrate overlap and synergism between TCR and NER pathways in neurons, and they uncover the occurrence of spontaneous DNA injury that may trigger neuronal degeneration. We propose that, while Csa−/− and Csb−/− TCR–deficient mice represent powerful animal models to study the mechanisms underlying myelin abnormalities in CS, neuron-specific inactivation of NER in TCR–deficient mice represents a valuable model for the role of NER in neuronal maintenance and survival. Metabolism produces reactive oxygen species that damage our DNA and other cellular components, and as such it contributes to the aging process, including neuronal degeneration. Accordingly, genetic disorders associated with impaired DNA damage repair are frequently associated with premature onset of aging pathology in a variety of tissues, including the brain. This is well-illustrated by the progeroid DNA repair syndromes xeroderma pigmentosum (XP) and Cockayne syndrome (CS), in which patients suffer from defects in nucleotide excision repair (NER) and transcription-coupled repair (TCR), two partially overlapping DNA repair systems that remove helix-distorting and transcription-blocking lesions, respectively. We have used a panel of XP and CS mice (including conditional double-mutant animals) to systematically investigate the impact of NER and TCR defects on neuronal degeneration. We have shown that, whereas a TCR defect causes white matter pathology, a NER defect can result in age related cumulative loss of neurons. These findings well match the neuropathology observed in CS and XP patients, underscoring the impact of spontaneous DNA damage in the onset of neuronal aging. Therefore, the XP and CS mouse models serve as valuable tools to delineate intervention strategies that combat age-associated pathology of the brain.
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Olah M, Amor S, Brouwer N, Vinet J, Eggen B, Biber K, Boddeke HWGM. Identification of a microglia phenotype supportive of remyelination. Glia 2011; 60:306-21. [PMID: 22072381 DOI: 10.1002/glia.21266] [Citation(s) in RCA: 261] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 10/11/2011] [Indexed: 11/07/2022]
Abstract
In multiple sclerosis, endogenous oligodendrocyte precursor cells (OPCs) attempt to remyelinate areas of myelin damage. During disease progression, however, these attempts fail. It has been suggested that modulating the inflammatory environment of the lesion might provide a promising therapeutic approach to promote endogenous remyelination. Microglia are known to play a central role in neuroinflammatory processes. To investigate the microglia phenotype that supports remyelination, we performed genome-wide gene expression analysis of microglia from the corpus callosum during demyelination and remyelination in the mouse cuprizone model, in which remyelination spontaneously occurs after an episode of toxin-induced primary demyelination. We provide evidence for the existence of a microglia phenotype that supports remyelination already at the onset of demyelination and persists throughout the remyelination process. Our data show that microglia are involved in the phagocytosis of myelin debris and apoptotic cells during demyelination. Furthermore, they express a cytokine and chemokine repertoire enabling them to activate and recruit endogenous OPCs to the lesion site and deliver trophic support during remyelination. This study not only provides a detailed transcriptomic analysis of the remyelination-supportive microglia phenotype but also reinforces the notion that the primary function of microglia is the maintenance of tissue homeostasis and the support of regeneration already at the earliest stages in the development of demyelinating lesions.
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Affiliation(s)
- Marta Olah
- Department of Neuroscience, Section Medical Physiology, University Medical Center Groningen, Groningen, The Netherlands
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