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Georges HM, Cassin C, Tong M, Abrahams VM. TLR8-activating miR-146a-3p is an intermediate signal contributing to fetal membrane inflammation in response to bacterial LPS. Immunology 2024; 172:577-587. [PMID: 38631842 PMCID: PMC11223956 DOI: 10.1111/imm.13794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 04/05/2024] [Indexed: 04/19/2024] Open
Abstract
Preterm birth is the largest contributor to neonatal morbidity and is often associated with chorioamnionitis, defined as inflammation/infection of the fetal membranes (FMs). Chorioamnionitis is characterised by neutrophil infiltration of the FMs and is associated with elevated levels of the neutrophil chemoattractant, interleukin (IL)-8 and the proinflammatory cytokine, IL-1β. While FMs can respond to infections through innate immune sensors, such as toll-like receptors (TLRs), the downstream mechanisms by which chorioamnionitis arises are not fully understood. A novel group of non-classical microRNAs (miR-21a, miR-29a, miR-146a-3p, Let-7b) function as endogenous danger signals by activating the ssRNA viral sensors TLR7 and TLR8. In this study, the pro-inflammatory roles of TLR7/TLR8-activating miRs were examined as mediators of FM inflammation in response to bacterial lipopolysaccharide (LPS) using an in vitro human FM explant system, an in vivo mouse model of pregnancy, and human clinical samples. Following LPS exposure, miR-146a-3p was significantly increased in both human FM explants and wild-type mouse FMs. Expression of miR-146a-3p was also significantly elevated in FMs from women with preterm birth and chorioamnionitis. FM IL-8 and inflammasome-mediated IL-1β production in response to LPS was dependent on miR-146a-3p and TLR8 downstream of TLR4 activation. In wild-type mice, LPS exposure increased FM IL-8 and IL-1β production and induced preterm birth. In TLR7-/-/TLR8-/- mice, LPS exposure was able to initiate but not sustain preterm birth, and FM inflammation was reduced. Together, we demonstrate a novel signalling mechanism at the maternal-fetal interface in which TLR8-activating miR-146a-3p acts as an intermediate danger signal to drive FM inflammasome-dependent and -independent mechanisms of inflammation and, thus, may play a role in chorioamnionitis and subsequent preterm birth.
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Affiliation(s)
- Hanah M. Georges
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Caterina Cassin
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Mancy Tong
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
| | - Vikki M. Abrahams
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA
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2
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Allard RL, Mayfield J, Barchiesi R, Salem NA, Mayfield RD. Toll-like receptor 7: A novel neuroimmune target to reduce excessive alcohol consumption. Neurobiol Stress 2024; 31:100639. [PMID: 38765062 PMCID: PMC11101708 DOI: 10.1016/j.ynstr.2024.100639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/30/2024] [Accepted: 05/03/2024] [Indexed: 05/21/2024] Open
Abstract
Toll-like receptors (TLRs) are a family of innate immune receptors that recognize molecular patterns in foreign pathogens and intrinsic danger/damage signals from cells. TLR7 is a nucleic acid sensing endosomal TLR that is activated by single-stranded RNAs from microbes or by small noncoding RNAs that act as endogenous ligands. TLR7 signals through the MyD88 adaptor protein and activates the transcription factor interferon regulatory factor 7 (IRF7). TLR7 is found throughout the brain and is highly expressed in microglia, the main immune cells of the brain that have also been implicated in alcohol drinking in mice. Upregulation of TLR7 mRNA and protein has been identified in postmortem hippocampus and cortex from AUD subjects that correlated positively with lifetime consumption of alcohol. Similarly, Tlr7 and downstream signaling genes were upregulated in rat hippocampal and cortical slice cultures after chronic alcohol exposure and in these regions after chronic binge-like alcohol treatment in mice. In addition, repeated administration of the synthetic TLR7 agonists imiquimod (R837) or resiquimod (R848) increased voluntary alcohol drinking in different rodent models and produced sustained upregulation of IRF7 in the brain. These findings suggest that chronic TLR7 activation may drive excessive alcohol drinking. In the brain, this could occur through increased levels of endogenous TLR7 activators, like microRNAs and Y RNAs. This review explores chronic TLR7 activation as a pathway of dysregulated neuroimmune signaling in AUD and the endogenous small RNA ligands in the brain that could perpetuate innate immune responses and escalate alcohol drinking.
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Affiliation(s)
- Ruth L. Allard
- Waggoner Center for Alcohol and Addiction Research and The University of Texas at Austin, Austin, TX, 78712, USA
| | - Jody Mayfield
- Waggoner Center for Alcohol and Addiction Research and The University of Texas at Austin, Austin, TX, 78712, USA
| | - Riccardo Barchiesi
- Waggoner Center for Alcohol and Addiction Research and The University of Texas at Austin, Austin, TX, 78712, USA
| | - Nihal A. Salem
- Waggoner Center for Alcohol and Addiction Research and The University of Texas at Austin, Austin, TX, 78712, USA
| | - R. Dayne Mayfield
- Waggoner Center for Alcohol and Addiction Research and The University of Texas at Austin, Austin, TX, 78712, USA
- Department of Neuroscience, The University of Texas at Austin, Austin, TX, 78712, USA
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Huang Y, Jiang C, Liu X, Tang W, Gui H, Sun T, Xu D, He M, Han M, Qiu H, Chen M, Huang S. Melatonin suppresses TLR4-mediated RSV infection in the central nervous cells by inhibiting NLRP3 inflammasome formation and autophagy. J Cell Mol Med 2024; 28:e18338. [PMID: 38683122 PMCID: PMC11057421 DOI: 10.1111/jcmm.18338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 03/22/2024] [Accepted: 03/29/2024] [Indexed: 05/01/2024] Open
Abstract
Respiratory syncytial virus (RSV) infects neuronal cells in the central nervous system (CNS), resulting in neurological symptoms. In the present study, we intended to explore the mechanism of RSV infection-induced neuroinflammatory injury from the perspective of the immune response and sought to identify effective protective measures against the injury. The findings showed that toll-like receptor 4 (TLR4) was activated after RSV infection in human neuronal SY5Y cells. Furthermore, TLR4 activation induced autophagy and apoptosis in neuronal cells, promoted the formation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, and increased the secretion of downstream inflammatory cytokines such as interleukin-1β (IL-1β), interleukin-18 (IL-18) and tumour necrosis factor-α (TNF-α). Interestingly, blockade of TLR4 or treatment with exogenous melatonin significantly suppressed TLR4 activation as well as TLR4-mediated apoptosis, autophagy and immune responses. Therefore, we infer that melatonin may act on the TLR4 to ameliorate RSV-induced neuronal injury, which provides a new therapeutic target for RSV infection.
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Affiliation(s)
- Yixuan Huang
- Department of EndocrinologyThe First Affiliated Hospital of Anhui Medical UniversityHefeiChina
| | - Chengcheng Jiang
- Department of Microbiology, School of Basic Medical SciencesAnhui Medical UniversityHefeiChina
| | - Xiaojie Liu
- Department of Microbiology, School of Basic Medical SciencesAnhui Medical UniversityHefeiChina
| | - Wei Tang
- Department of Microbiology, School of Basic Medical SciencesAnhui Medical UniversityHefeiChina
| | - Hongya Gui
- Department of Microbiology, School of Basic Medical SciencesAnhui Medical UniversityHefeiChina
| | - Tao Sun
- Department of Microbiology, School of Basic Medical SciencesAnhui Medical UniversityHefeiChina
| | - Doudou Xu
- Department of PediatricsThe First Affiliated Hospital of Anhui Medical UniversityHefeiChina
| | - Maozhang He
- Department of Microbiology, School of Basic Medical SciencesAnhui Medical UniversityHefeiChina
| | - Maozhen Han
- School of Life SciencesAnhui Medical UniversityHefeiChina
| | - Huan Qiu
- School of NursingAnhui Medical UniversityHefeiChina
| | - Mingwei Chen
- Department of EndocrinologyThe First Affiliated Hospital of Anhui Medical UniversityHefeiChina
| | - Shenghai Huang
- Department of Microbiology, School of Basic Medical SciencesAnhui Medical UniversityHefeiChina
- School of Life SciencesAnhui Medical UniversityHefeiChina
- Department of Clinical LaboratoryAnhui Public Health Clinical Center, The First Affiliated Hospital of Anhui Medical UniversityHefeiChina
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4
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Kaizuka M, Kawaguchi S, Tatsuta T, Tachizaki M, Kobori Y, Tanaka Y, Seya K, Matsumiya T, Imaizumi T, Sakuraba H. Resiquimod Induces C-C Motif Chemokine Ligand 2 Via Nuclear Factor-Kappa B in SH-SY5Y Human Neuroblastoma Cells. Neuromolecular Med 2024; 26:16. [PMID: 38668900 DOI: 10.1007/s12017-024-08782-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 03/07/2024] [Indexed: 05/01/2024]
Abstract
Toll-like receptor (TLR) 7 plays an important role in recognizing virus-derived nucleic acids. TLR7 signaling in astrocytes and microglia is critical for activating immune responses against neurotrophic viruses. Neurons express TLR7, similar to glial cells; however, the role of neuronal TLR7 has not yet been fully elucidated. This study sought to determine whether resiquimod, the TLR7/8 agonist, induces the expression of inflammatory chemokines in SH-SY5Y human neuroblastoma cells. Immunofluorescence microscopy revealed that TLR7 was constitutively expressed in SH-SY5Y cells. Stimulation with resiquimod induced C-C motif chemokine ligand 2 (CCL2) expression, accompanied by the activation of nuclear factor-kappa B (NF-κB) in SH-SY5Y cells. Resiquimod increased mRNA levels of C-X-C motif chemokine ligand 8 (CXCL8) and CXCL10, while the increase was slight at the protein level. Knockdown of NF-κB p65 eliminated resiquimod-induced CCL2 production. This study provides novel evidence that resiquimod has promising therapeutic potential against central nervous system viral infections through its immunostimulatory effects on neurons.
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Affiliation(s)
- Masatoshi Kaizuka
- Department of Gastroenterology and Hematology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Shogo Kawaguchi
- Department of Vascular Biology, Institute of Brain Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan.
| | - Tetsuya Tatsuta
- Department of Gastroenterology and Hematology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Mayuki Tachizaki
- Department of Vascular Biology, Institute of Brain Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Yuri Kobori
- Department of Vascular Biology, Institute of Brain Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
- Department of Respiratory Medicine, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Yusuke Tanaka
- Department of Vascular Biology, Institute of Brain Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
- Department of Respiratory Medicine, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Kazuhiko Seya
- Department of Vascular Biology, Institute of Brain Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Tomoh Matsumiya
- Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Science, 5 Zaifu-cho, Hirosaki, Aomori, 036-8564, Japan
| | - Tadaatsu Imaizumi
- Department of Vascular Biology, Institute of Brain Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
| | - Hirotake Sakuraba
- Department of Gastroenterology and Hematology, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki, Aomori, 036-8562, Japan
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McGurran H, Kumbol V, Krüger C, Wallach T, Lehnardt S. miR-154-5p Is a Novel Endogenous Ligand for TLR7 Inducing Microglial Activation and Neuronal Injury. Cells 2024; 13:407. [PMID: 38474371 DOI: 10.3390/cells13050407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 02/20/2024] [Accepted: 02/22/2024] [Indexed: 03/14/2024] Open
Abstract
Toll-like receptors (TLRs) are a collection of pattern recognition sensors that form a first line of defence by detecting pathogen- or damage-associated molecular patterns and initiating an inflammatory response. TLR activation in microglia, the major immune cells in the brain, can trigger the release of inflammatory molecules, which may contribute to various CNS diseases including Alzheimer's disease. Recently, some microRNAs were shown to serve as signalling molecules for TLRs. Here, we present miR-154-5p as a novel TLR7 ligand. Exposing microglia to miR-154-5p results in cytokine release and alters expression of the TLR signalling pathway dependent on TLR7. Additionally, miR-154-5p causes neuronal injury in enriched cortical neuron cultures and additive toxicity in the presence of microglia. Finally, intrathecal injection of miR-154-5p into mice leads to neuronal injury and accumulation of microglia in the cerebral cortex dependent on TLR7 expression. In conclusion, this study establishes miR-154-5p as a direct activator of TLR7 that can cause neuroinflammation and neuronal injury, which may contribute to CNS disease.
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Affiliation(s)
- Hugo McGurran
- Charité-Universitätsmedizin Berlin, Einstein Center for Neurosciences Berlin, 10117 Berlin, Germany
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany
| | - Victor Kumbol
- Charité-Universitätsmedizin Berlin, Einstein Center for Neurosciences Berlin, 10117 Berlin, Germany
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany
| | - Christina Krüger
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany
| | - Thomas Wallach
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany
| | - Seija Lehnardt
- Institute of Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany
- Department of Neurology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany
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6
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Fila M, Pawlowska E, Szczepanska J, Blasiak J. Epigenetic Connections of the TRPA1 Ion Channel in Pain Transmission and Neurogenic Inflammation - a Therapeutic Perspective in Migraine? Mol Neurobiol 2023; 60:5578-5591. [PMID: 37326902 PMCID: PMC10471718 DOI: 10.1007/s12035-023-03428-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 06/05/2023] [Indexed: 06/17/2023]
Abstract
Persistent reprogramming of epigenetic pattern leads to changes in gene expression observed in many neurological disorders. Transient receptor potential cation channel subfamily A member 1 (TRPA1), a member of the TRP channels superfamily, is activated by many migraine triggers and expressed in trigeminal neurons and brain regions that are important in migraine pathogenesis. TRP channels change noxious stimuli into pain signals with the involvement of epigenetic regulation. The expression of the TRPA1 encoding gene, TRPA1, is modulated in pain-related syndromes by epigenetic alterations, including DNA methylation, histone modifications, and effects of non-coding RNAs: micro RNAs (miRNAs), long non-coding RNAs, and circular RNAs. TRPA1 may change epigenetic profile of many pain-related genes as it may modify enzymes responsible for epigenetic modifications and expression of non-coding RNAs. TRPA1 may induce the release of calcitonin gene related peptide (CGRP), from trigeminal neurons and dural tissue. Therefore, epigenetic regulation of TRPA1 may play a role in efficacy and safety of anti-migraine therapies targeting TRP channels and CGRP. TRPA1 is also involved in neurogenic inflammation, important in migraine pathogenesis. The fundamental role of TRPA1 in inflammatory pain transmission may be epigenetically regulated. In conclusion, epigenetic connections of TRPA1 may play a role in efficacy and safety of anti-migraine therapy targeting TRP channels or CGRP and they should be further explored for efficient and safe antimigraine treatment. This narrative/perspective review presents information on the structure and functions of TRPA1 as well as role of its epigenetic connections in pain transmission and potential in migraine therapy.
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Affiliation(s)
- Michal Fila
- Department of Developmental Neurology and Epileptology, Polish Mother's Memorial Hospital Research Institute, 93-338, Lodz, Poland
| | - Elzbieta Pawlowska
- Department of Pediatric Dentistry, Medical University of Lodz, 92-217, Lodz, Poland
| | - Joanna Szczepanska
- Department of Pediatric Dentistry, Medical University of Lodz, 92-217, Lodz, Poland
| | - Janusz Blasiak
- Department of Molecular Genetics, University of Lodz, 90-236, Lodz, Poland.
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7
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Kunze R, Fischer S, Marti HH, Preissner KT. Brain alarm by self-extracellular nucleic acids: from neuroinflammation to neurodegeneration. J Biomed Sci 2023; 30:64. [PMID: 37550658 PMCID: PMC10405513 DOI: 10.1186/s12929-023-00954-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 07/22/2023] [Indexed: 08/09/2023] Open
Abstract
Neurological disorders such as stroke, multiple sclerosis, as well as the neurodegenerative diseases Parkinson's or Alzheimer's disease are accompanied or even powered by danger associated molecular patterns (DAMPs), defined as endogenous molecules released from stressed or damaged tissue. Besides protein-related DAMPs or "alarmins", numerous nucleic acid DAMPs exist in body fluids, such as cell-free nuclear and mitochondrial DNA as well as different species of extracellular RNA, collectively termed as self-extracellular nucleic acids (SENAs). Among these, microRNA, long non-coding RNAs, circular RNAs and extracellular ribosomal RNA constitute the majority of RNA-based DAMPs. Upon tissue injury, necrosis or apoptosis, such SENAs are released from neuronal, immune and other cells predominantly in association with extracellular vesicles and may be translocated to target cells where they can induce intracellular regulatory pathways in gene transcription and translation. The majority of SENA-induced signaling reactions in the brain appear to be related to neuroinflammatory processes, often causally associated with the onset or progression of the respective disease. In this review, the impact of the diverse types of SENAs on neuroinflammatory and neurodegenerative diseases will be discussed. Based on the accumulating knowledge in this field, several specific antagonistic approaches are presented that could serve as therapeutic interventions to lower the pathological outcome of the indicated brain disorders.
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Affiliation(s)
- Reiner Kunze
- Institute of Physiology and Pathophysiology, Department of Cardiovascular Physiology, Ruprecht-Karls-University, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany
| | - Silvia Fischer
- Department of Biochemistry, Medical School, Justus-Liebig-University, Giessen, Germany
| | - Hugo H. Marti
- Institute of Physiology and Pathophysiology, Department of Cardiovascular Physiology, Ruprecht-Karls-University, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany
| | - Klaus T. Preissner
- Department of Biochemistry, Medical School, Justus-Liebig-University, Giessen, Germany
- Kerckhoff-Heart-Research-Institute, Department of Cardiology, Medical School, Justus-Liebig-University, Giessen, Germany
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8
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Patlola SR, Donohoe G, McKernan DP. Counting the Toll of Inflammation on Schizophrenia-A Potential Role for Toll-like Receptors. Biomolecules 2023; 13:1188. [PMID: 37627253 PMCID: PMC10452856 DOI: 10.3390/biom13081188] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 07/25/2023] [Accepted: 07/25/2023] [Indexed: 08/27/2023] Open
Abstract
Toll-like receptors (TLRs) are a family of pattern recognition receptors (PRRs) that are ubiquitously expressed in the human body. They protect the brain and central nervous system from self and foreign antigens/pathogens. The immune response elicited by these receptors culminates in the release of cytokines, chemokines, and interferons causing an inflammatory response, which can be both beneficial and harmful to neurodevelopment. In addition, the detrimental effects of TLR activation have been implicated in multiple neurodegenerative diseases such as Alzheimer's, multiple sclerosis, etc. Many studies also support the theory that cytokine imbalance may be involved in schizophrenia, and a vast amount of literature showcases the deleterious effects of this imbalance on cognitive performance in the human population. In this review, we examine the current literature on TLRs, their potential role in the pathogenesis of schizophrenia, factors affecting TLR activity that contribute towards the risk of schizophrenia, and lastly, the role of TLRs and their impact on cognitive performance in schizophrenia.
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Affiliation(s)
- Saahithh Redddi Patlola
- Department of Pharmacology & Therapeutics, School of Medicine, University of Galway, H91 TK33 Galway, Ireland;
| | - Gary Donohoe
- School of Psychology, University of Galway, H91 TK33 Galway, Ireland;
| | - Declan P. McKernan
- Department of Pharmacology & Therapeutics, School of Medicine, University of Galway, H91 TK33 Galway, Ireland;
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Campbell GR, Rawat P, Teodorof-Diedrich C, Spector SA. IRAK1 inhibition blocks the HIV-1 RNA mediated pro-inflammatory cytokine response from microglia. J Gen Virol 2023; 104:001858. [PMID: 37256770 PMCID: PMC10336426 DOI: 10.1099/jgv.0.001858] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 05/10/2023] [Indexed: 06/02/2023] Open
Abstract
Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) are a common source of morbidity in people living with HIV (PLWH). Although antiretroviral therapy (ART) has lessened the severity of neurocognitive disorders, cognitive impairment still occurs in PLWH receiving ART. The pathogenesis of HAND is likely multifaceted, but common factors include the persistence of HIV transcription within the central nervous system, higher levels of pro-inflammatory cytokines in the cerebrospinal fluid, and the presence of activated microglia. Toll-like receptor (TLR) 7 and TLR8 are innate pathogen recognition receptors located in microglia and other immune and non-immune cells that can recognise HIV RNA and trigger pro-inflammatory responses. IL-1 receptor-associated kinase (IRAK) 1 is key to these signalling pathways. Here, we show that IRAK1 inhibition inhibits the TLR7 and TLR8-dependent pro-inflammatory response to HIV RNA. Using genetic and pharmacological inhibition, we demonstrate that inhibition of IRAK1 prevents IRAK1 phosphorylation and ubiquitination, and the subsequent recruitment of TRAF6 and the TAK1 complex to IRAK1, resulting in the inhibition of downstream signalling and the suppression of pro-inflammatory cytokine and chemokine release.
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Affiliation(s)
- Grant R. Campbell
- Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, USA
| | - Pratima Rawat
- Division of Infectious Diseases, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Present address: Microbiologics Inc, San Diego, CA, USA
| | - Carmen Teodorof-Diedrich
- Division of Infectious Diseases, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Stephen A. Spector
- Division of Infectious Diseases, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Rady Children’s Hospital, San Diego, CA, USA
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10
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Wallach T, Raden M, Hinkelmann L, Brehm M, Rabsch D, Weidling H, Krüger C, Kettenmann H, Backofen R, Lehnardt S. Distinct SARS-CoV-2 RNA fragments activate Toll-like receptors 7 and 8 and induce cytokine release from human macrophages and microglia. Front Immunol 2023; 13:1066456. [PMID: 36713399 PMCID: PMC9880480 DOI: 10.3389/fimmu.2022.1066456] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 12/23/2022] [Indexed: 01/14/2023] Open
Abstract
Introduction The pandemic coronavirus disease 19 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is marked by thromboembolic events and an inflammatory response throughout the body, including the brain. Methods Employing the machine learning approach BrainDead we systematically screened for SARS-CoV-2 genome-derived single-stranded (ss) RNA fragments with high potential to activate the viral RNA-sensing innate immune receptors Toll-like receptor (TLR)7 and/or TLR8. Analyzing HEK TLR7/8 reporter cells we tested such RNA fragments with respect to their potential to induce activation of human TLR7 and TLR8 and to activate human macrophages, as well as iPSC-derived human microglia, the resident immune cells in the brain. Results We experimentally validated several sequence-specific RNA fragment candidates out of the SARS-CoV-2 RNA fragments predicted in silico as activators of human TLR7 and TLR8. Moreover, these SARS-CoV-2 ssRNAs induced cytokine release from human macrophages and iPSC-derived human microglia in a sequence- and species-specific fashion. Discussion Our findings determine TLR7 and TLR8 as key sensors of SARS-CoV-2-derived ssRNAs and may deepen our understanding of the mechanisms how this virus triggers, but also modulates an inflammatory response through innate immune signaling.
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Affiliation(s)
- Thomas Wallach
- Institute of Cell Biology and Neurobiology, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Martin Raden
- Bioinformatics, Department of Computer Science, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Lukas Hinkelmann
- Institute of Cell Biology and Neurobiology, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Mariam Brehm
- Institute of Cell Biology and Neurobiology, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Dominik Rabsch
- Bioinformatics, Department of Computer Science, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Hannah Weidling
- Institute of Cell Biology and Neurobiology, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany,Cellular Neuroscience, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Christina Krüger
- Institute of Cell Biology and Neurobiology, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Helmut Kettenmann
- Cellular Neuroscience, Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Rolf Backofen
- Bioinformatics, Department of Computer Science, Albert-Ludwigs-University Freiburg, Freiburg, Germany,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany,*Correspondence: Seija Lehnardt, ; Rolf Backofen,
| | - Seija Lehnardt
- Institute of Cell Biology and Neurobiology, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany,Department of Neurology, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany,*Correspondence: Seija Lehnardt, ; Rolf Backofen,
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11
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Reyes EY, Shinohara ML. Host immune responses in the central nervous system during fungal infections. Immunol Rev 2022; 311:50-74. [PMID: 35672656 PMCID: PMC9489659 DOI: 10.1111/imr.13101] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 04/24/2022] [Accepted: 05/18/2022] [Indexed: 12/19/2023]
Abstract
Fungal infections in the central nervous system (CNS) cause high morbidity and mortality. The frequency of CNS mycosis has increased over the last two decades as more individuals go through immunocompromised conditions for various reasons. Nevertheless, options for clinical interventions for CNS mycoses are still limited. Thus, there is an urgent need to understand the host-pathogen interaction mechanisms in CNS mycoses for developing novel treatments. Although the CNS has been regarded as an immune-privileged site, recent studies demonstrate the critical involvement of immune responses elicited by CNS-resident and CNS-infiltrated cells during fungal infections. In this review, we discuss mechanisms of fungal invasion in the CNS, fungal pathogen detection by CNS-resident cells (microglia, astrocytes, oligodendrocytes, neurons), roles of CNS-infiltrated leukocytes, and host immune responses. We consider that understanding host immune responses in the CNS is crucial for endeavors to develop treatments for CNS mycosis.
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Affiliation(s)
- Estefany Y. Reyes
- Department of Immunology, Duke University School of Medicine, Durham, NC 27705, USA
| | - Mari L. Shinohara
- Department of Immunology, Duke University School of Medicine, Durham, NC 27705, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27705, USA
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12
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Acioglu C, Heary RF, Elkabes S. Roles of neuronal toll-like receptors in neuropathic pain and central nervous system injuries and diseases. Brain Behav Immun 2022; 102:163-178. [PMID: 35176442 DOI: 10.1016/j.bbi.2022.02.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 01/12/2022] [Accepted: 02/11/2022] [Indexed: 12/12/2022] Open
Abstract
Toll-like receptors (TLRs) are innate immune receptors that are expressed in immune cells as well as glia and neurons of the central and peripheral nervous systems. They are best known for their role in the host defense in response to pathogens and for the induction of inflammation in infectious and non-infectious diseases. In the central nervous system (CNS), TLRs modulate glial and neuronal functions as well as innate immunity and neuroinflammation under physiological or pathophysiological conditions. The majority of the studies on TLRs in CNS pathologies investigated their overall contribution without focusing on a particular cell type, or they analyzed TLRs in glia and infiltrating immune cells in the context of neuroinflammation and cellular activation. The role of neuronal TLRs in CNS diseases and injuries has received little attention and remains underappreciated. The primary goal of this review is to summarize findings demonstrating the pivotal and unique roles of neuronal TLRs in neuropathic pain, Alzheimer's disease, Parkinson's disease and CNS injuries. We discuss how the current findings warrant future investigations to better define the specific contributions of neuronal TLRs to these pathologies. We underline the paucity of information regarding the role of neuronal TLRs in other neurodegenerative, demyelinating, and psychiatric diseases. We draw attention to the importance of broadening research on neuronal TLRs in view of emerging evidence demonstrating their distinctive functional properties.
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Affiliation(s)
- Cigdem Acioglu
- The Reynolds Family Spine Laboratory, Department of Neurosurgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, United States
| | - Robert F Heary
- Department of Neurological Surgery, Hackensack Meridian School of Medicine, Mountainside Medical Center, Montclair, NJ 07042, United States
| | - Stella Elkabes
- The Reynolds Family Spine Laboratory, Department of Neurosurgery, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, United States.
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13
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Systemic Administration of the TLR7/8 Agonist Resiquimod (R848) to Mice Is Associated with Transient, In Vivo-Detectable Brain Swelling. BIOLOGY 2022; 11:biology11020274. [PMID: 35205140 PMCID: PMC8869423 DOI: 10.3390/biology11020274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 01/24/2022] [Accepted: 01/26/2022] [Indexed: 11/17/2022]
Abstract
Peripheral administration of the E. coli endotoxin lipopolysaccharide (LPS) to rats promotes secretion of pro-inflammatory cytokines and in previous studies was associated with transient enlargement of cortical volumes. Here, resiquimod (R848) was administered to mice to stimulate peripheral immune activation, and the effects on brain volumes and neurometabolites determined. After baseline scans, 24 male, wild-type C57BL mice were triaged into three groups including R848 at low (50 μg) and high (100 μg) doses and saline controls. Animals were scanned again at 3 h and 24 h following treatment. Sickness indices of elevated temperature and body weight loss were observed in all R848 animals. Animals that received 50 μg R848 exhibited decreases in hippocampal N-acetylaspartate and phosphocreatine at the 3 h time point that returned to baseline levels at 24 h. Animals that received the 100 μg R848 dose demonstrated transient, localized, volume expansion (~5%) detectable at 3 h in motor, somatosensory, and olfactory cortices; and pons. A metabolic response evident at the lower dose and a volumetric change at the higher dose suggests a temporal evolution of the effect wherein the neurochemical change is demonstrable earlier than neurostructural change. Transient volume expansion in response to peripheral immune stimulation corresponds with previous results and is consistent with brain swelling that may reflect CNS edema.
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14
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Wallach T, Mossmann ZJ, Szczepek M, Wetzel M, Machado R, Raden M, Miladi M, Kleinau G, Krüger C, Dembny P, Adler D, Zhai Y, Kumbol V, Dzaye O, Schüler J, Futschik M, Backofen R, Scheerer P, Lehnardt S. MicroRNA-100-5p and microRNA-298-5p released from apoptotic cortical neurons are endogenous Toll-like receptor 7/8 ligands that contribute to neurodegeneration. Mol Neurodegener 2021; 16:80. [PMID: 34838071 PMCID: PMC8626928 DOI: 10.1186/s13024-021-00498-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 11/03/2021] [Indexed: 12/30/2022] Open
Abstract
Background MicroRNA (miRNA) expression in the brain is altered in neurodegenerative diseases. Recent studies demonstrated that selected miRNAs conventionally regulating gene expression at the post-transcriptional level can act extracellularly as signaling molecules. The identity of miRNA species serving as membrane receptor ligands involved in neuronal apoptosis in the central nervous system (CNS), as well as the miRNAs’ sequence and structure required for this mode of action remained largely unresolved. Methods Using a microarray-based screening approach we analyzed apoptotic cortical neurons of C56BL/6 mice and their supernatant with respect to alterations in miRNA expression/presence. HEK-Blue Toll-like receptor (TLR) 7/8 reporter cells, primary microglia and macrophages derived from human and mouse were employed to test the potential of the identified miRNAs released from apoptotic neurons to serve as signaling molecules for the RNA-sensing receptors. Biophysical and bioinformatical approaches, as well as immunoassays and sequential microscopy were used to analyze the interaction between candidate miRNA and TLR. Immunocytochemical and -histochemical analyses of murine CNS cultures and adult mice intrathecally injected with miRNAs, respectively, were performed to evaluate the impact of miRNA-induced TLR activation on neuronal survival and microglial activation. Results We identified a specific pattern of miRNAs released from apoptotic cortical neurons that activate TLR7 and/or TLR8, depending on sequence and species. Exposure of microglia and macrophages to certain miRNA classes released from apoptotic neurons resulted in the sequence-specific production of distinct cytokines/chemokines and increased phagocytic activity. Out of those miRNAs miR-100-5p and miR-298-5p, which have consistently been linked to neurodegenerative diseases, entered microglia, located to their endosomes, and directly bound to human TLR8. The miRNA-TLR interaction required novel sequence features, but no specific structure formation of mature miRNA. As a consequence of miR-100-5p- and miR-298-5p-induced TLR activation, cortical neurons underwent cell-autonomous apoptosis. Presence of miR-100-5p and miR-298-5p in cerebrospinal fluid led to neurodegeneration and microglial accumulation in the murine cerebral cortex through TLR7 signaling. Conclusion Our data demonstrate that specific miRNAs are released from apoptotic cortical neurons, serve as endogenous TLR7/8 ligands, and thereby trigger further neuronal apoptosis in the CNS. Our findings underline the recently discovered role of miRNAs as extracellular signaling molecules, particularly in the context of neurodegeneration. Supplementary Information The online version contains supplementary material available at 10.1186/s13024-021-00498-5.
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Affiliation(s)
- Thomas Wallach
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany.
| | - Zoé J Mossmann
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Michal Szczepek
- Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Max Wetzel
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Rui Machado
- Department of Biomedical Sciences and Medicine, University of Algarve, 8005-139, Faro, Portugal
| | - Martin Raden
- Bioinformatics, Department of Computer Science, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Milad Miladi
- Bioinformatics, Department of Computer Science, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Gunnar Kleinau
- Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Christina Krüger
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Paul Dembny
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Drew Adler
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Yuanyuan Zhai
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Victor Kumbol
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Omar Dzaye
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Jutta Schüler
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany
| | - Matthias Futschik
- Department of Biomedical Sciences and Medicine, University of Algarve, 8005-139, Faro, Portugal.,School of Biomedical Sciences, Faculty of Health, University of Plymouth, Plymouth, PL6 8BU, UK.,MRC London Institute of Medical Sciences (LMS), Faculty of Medicine, Imperial College London, London, W12 0NN, UK
| | - Rolf Backofen
- Bioinformatics, Department of Computer Science, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Patrick Scheerer
- Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography & Signal Transduction, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany.,German Centre for Cardiovascular Research, partner site Berlin, Berlin, Germany
| | - Seija Lehnardt
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany. .,Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117, Berlin, Germany.
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15
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TLR Signaling in Brain Immunity. Handb Exp Pharmacol 2021; 276:213-237. [PMID: 34761292 DOI: 10.1007/164_2021_542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Toll-like receptors (TLRs) comprise a group of transmembrane proteins with crucial roles in pathogen recognition, immune responses, and signal transduction. This family represented the first line of immune homeostasis in an evolutionarily conserved manner. Extensive researches in the past two decades had emphasized their structural and functional characteristics under both healthy and pathological conditions. In this review, we summarized the current understanding of TLR signaling in the central nervous system (CNS), which had been viewed as a previously "immune-privileged" but now "immune-specialized" area, with major implications for further investigation of pathological nature as well as potential therapeutic manipulation of TLR signaling in various neurological disorders.
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16
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Adhikarla SV, Jha NK, Goswami VK, Sharma A, Bhardwaj A, Dey A, Villa C, Kumar Y, Jha SK. TLR-Mediated Signal Transduction and Neurodegenerative Disorders. Brain Sci 2021; 11:brainsci11111373. [PMID: 34827372 PMCID: PMC8615980 DOI: 10.3390/brainsci11111373] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 10/16/2021] [Accepted: 10/16/2021] [Indexed: 11/16/2022] Open
Abstract
A special class of proteins called Toll-like receptors (TLRs) are an essential part of the innate immune system, connecting it to the adaptive immune system. There are 10 different Toll-Like Receptors that have been identified in human beings. TLRs are part of the central nervous system (CNS), showing that the CNS is capable of the immune response, breaking the long-held belief of the brain's "immune privilege" owing to the blood-brain barrier (BBB). These Toll-Like Receptors are present not just on the resident macrophages of the central nervous system but are also expressed by the neurons to allow them for the production of proinflammatory agents such as interferons, cytokines, and chemokines; the activation and recruitment of glial cells; and their participation in neuronal cell death by apoptosis. This study is focused on the potential roles of various TLRs in various neurodegenerative diseases such as Parkinson's disease (PD) and Alzheimer's disease (AD), namely TLR2, TLR3, TLR4, TLR7, and TLR9 in AD and PD in human beings and a mouse model.
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Affiliation(s)
- Shashank Vishwanath Adhikarla
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology (Formerly NSIT, University of Delhi), New Delhi 110078, India;
| | - Niraj Kumar Jha
- Department of Biotechnology, School of Engineering & Technology (SET), Sharda University, Greater Noida 201310, India; (N.K.J.); (A.B.)
| | - Vineet Kumar Goswami
- Department of Biotechnology, Delhi Technological University, Delhi 110042, India;
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham 2770, Australia;
| | - Ankur Sharma
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham 2770, Australia;
- Department of Life Science, School of Basic Science & Research (SBSR), Sharda University, Greater Noida 201310, India
| | - Anuradha Bhardwaj
- Department of Biotechnology, School of Engineering & Technology (SET), Sharda University, Greater Noida 201310, India; (N.K.J.); (A.B.)
| | - Abhijit Dey
- Department of Life Sciences, Presidency University, 86/1 College Street, Kolkata 700073, India;
| | - Chiara Villa
- School of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy;
| | - Yatender Kumar
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology (Formerly NSIT, University of Delhi), New Delhi 110078, India;
- Correspondence: (Y.K.); (S.K.J.)
| | - Saurabh Kumar Jha
- Department of Biotechnology, School of Engineering & Technology (SET), Sharda University, Greater Noida 201310, India; (N.K.J.); (A.B.)
- Department of Science and Engineering, Novel Global Community Educational Foundation, Hebersham 2770, Australia;
- Correspondence: (Y.K.); (S.K.J.)
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17
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Proskocil BJ, Wai K, Lebold KM, Norgard MA, Michaelis KA, De La Torre U, Cook M, Marks DL, Fryer AD, Jacoby DB, Drake MG. TLR7 is expressed by support cells, but not sensory neurons, in ganglia. J Neuroinflammation 2021; 18:209. [PMID: 34530852 PMCID: PMC8447680 DOI: 10.1186/s12974-021-02269-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 08/31/2021] [Indexed: 11/10/2022] Open
Abstract
Background Toll-like receptor 7 (TLR7) is an innate immune receptor that detects viral single-stranded RNA and triggers the production of proinflammatory cytokines and type 1 interferons in immune cells. TLR7 agonists also modulate sensory nerve function by increasing neuronal excitability, although studies are conflicting whether sensory neurons specifically express TLR7. This uncertainty has confounded the development of a mechanistic understanding of TLR7 function in nervous tissues. Methods TLR7 expression was tested using in situ hybridization with species-specific RNA probes in vagal and dorsal root sensory ganglia in wild-type and TLR7 knockout (KO) mice and in guinea pigs. Since TLR7 KO mice were generated by inserting an Escherichia coli lacZ gene in exon 3 of the mouse TLR7 gene, wild-type and TLR7 (KO) mouse vagal ganglia were also labeled for lacZ. In situ labeling was compared to immunohistochemistry using TLR7 antibody probes. The effects of influenza A infection on TLR7 expression in sensory ganglia and in the spleen were also assessed. Results In situ probes detected TLR7 in the spleen and in small support cells adjacent to sensory neurons in the dorsal root and vagal ganglia in wild-type mice and guinea pigs, but not in TLR7 KO mice. TLR7 was co-expressed with the macrophage marker Iba1 and the satellite glial cell marker GFAP, but not with the neuronal marker PGP9.5, indicating that TLR7 is not expressed by sensory nerves in either vagal or dorsal root ganglia in mice or guinea pigs. In contrast, TLR7 antibodies labeled small- and medium-sized neurons in wild-type and TLR7 KO mice in a TLR7-independent manner. Influenza A infection caused significant weight loss and upregulation of TLR7 in the spleens, but not in vagal ganglia, in mice. Conclusion TLR7 is expressed by macrophages and satellite glial cells, but not neurons in sensory ganglia suggesting TLR7’s neuromodulatory effects are mediated indirectly via activation of neuronally-associated support cells, not through activation of neurons directly. Our data also suggest TLR7’s primary role in neuronal tissues is not related to antiviral immunity. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02269-x.
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Affiliation(s)
- Becky J Proskocil
- Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, UHN67, Portland, OR, 97239, USA
| | - Karol Wai
- Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, UHN67, Portland, OR, 97239, USA
| | - Katherine M Lebold
- Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, UHN67, Portland, OR, 97239, USA
| | - Mason A Norgard
- Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, OR, USA
| | - Katherine A Michaelis
- Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, OR, USA
| | - Ubaldo De La Torre
- Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, UHN67, Portland, OR, 97239, USA
| | - Madeline Cook
- Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, UHN67, Portland, OR, 97239, USA
| | - Daniel L Marks
- Papé Family Pediatric Research Institute, Oregon Health & Science University, Portland, OR, USA
| | - Allison D Fryer
- Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, UHN67, Portland, OR, 97239, USA
| | - David B Jacoby
- Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, UHN67, Portland, OR, 97239, USA
| | - Matthew G Drake
- Division of Pulmonary and Critical Care Medicine, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, UHN67, Portland, OR, 97239, USA.
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18
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Qin L, Zou J, Barnett A, Vetreno RP, Crews FT, Coleman LG. TRAIL Mediates Neuronal Death in AUD: A Link between Neuroinflammation and Neurodegeneration. Int J Mol Sci 2021; 22:2547. [PMID: 33806288 PMCID: PMC7961445 DOI: 10.3390/ijms22052547] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 02/25/2021] [Accepted: 02/26/2021] [Indexed: 12/12/2022] Open
Abstract
Although the cause of progressive neurodegeneration is often unclear, neuronal death can occur through several mechanisms. In conditions such as Alzheimer's or alcohol use disorder (AUD), Toll-like receptor (TLR) induction is observed with neurodegeneration. However, links between TLR activation and neurodegeneration are lacking. We report a role of apoptotic neuronal death in AUD through TLR7-mediated induction of death receptor signaling. In postmortem human cortex, a two-fold increase in apoptotic terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining in neurons was found in AUD versus controls. This occurred with the increased expression of TLR7 and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) death receptors. Binge ethanol treatment in C57BL/6 mice increased TLR7 and induced neuronal apoptosis in cortical regions that was blocked by TLR7 antagonism. Mechanistic studies in primary organotypic brain slice culture (OBSC) found that the inhibition of TLR7 and its endogenous ligand let-7b blocked ethanol-induced neuronal cell death. Both IMQ and ethanol induced the expression of TRAIL and its death receptor. In addition, TRAIL-neutralizing monoclonal antibodies blocked both imiquimod (IMQ) and ethanol induced neuronal death. These findings implicate TRAIL as a mediator of neuronal apoptosis downstream of TLR7 activation. TLR7 and neuronal apoptosis are implicated in other neurodegenerative diseases, including Alzheimer's disease. Therefore, TRAIL may represent a therapeutic target to slow neurodegeneration in multiple diseases.
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Affiliation(s)
- Liya Qin
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
| | - Jian Zou
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
| | - Alexandra Barnett
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
| | - Ryan P. Vetreno
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
- Department of Psychiatry, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
| | - Fulton T. Crews
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
- Department of Psychiatry, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
- Department of Pharmacology, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Leon G. Coleman
- Bowles Center for Alcohol Studies, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA;
- Department of Pharmacology, School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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19
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Buonfiglioli A, Efe IE, Guneykaya D, Ivanov A, Huang Y, Orlowski E, Krüger C, Deisz RA, Markovic D, Flüh C, Newman AG, Schneider UC, Beule D, Wolf SA, Dzaye O, Gutmann DH, Semtner M, Kettenmann H, Lehnardt S. let-7 MicroRNAs Regulate Microglial Function and Suppress Glioma Growth through Toll-Like Receptor 7. Cell Rep 2020; 29:3460-3471.e7. [PMID: 31825829 DOI: 10.1016/j.celrep.2019.11.029] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 08/08/2019] [Accepted: 11/06/2019] [Indexed: 12/20/2022] Open
Abstract
Microglia express Toll-like receptors (TLRs) that sense pathogen- and host-derived factors, including single-stranded RNA. In the brain, let-7 microRNA (miRNA) family members are abundantly expressed, and some have recently been shown to serve as TLR7 ligands. We investigated whether let-7 miRNA family members differentially control microglia biology in health and disease. We found that a subset of let-7 miRNA family members function as signaling molecules to induce microglial release of inflammatory cytokines, modulate antigen presentation, and attenuate cell migration in a TLR7-dependent manner. The capability of the let-7 miRNAs to control microglial function is sequence specific, mapping to a let-7 UUGU motif. In human and murine glioblastoma/glioma, let-7 miRNAs are differentially expressed and reduce murine GL261 glioma growth in the same sequence-specific fashion through microglial TLR7. Taken together, these data establish let-7 miRNAs as key TLR7 signaling activators that serve to regulate the diverse functions of microglia in health and glioma.
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Affiliation(s)
- Alice Buonfiglioli
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; Department of Cellular Neurosciences, Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
| | - Ibrahim E Efe
- Department of Cellular Neurosciences, Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany; Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
| | - Dilansu Guneykaya
- Department of Cellular Neurosciences, Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
| | - Andranik Ivanov
- Core Unit Bioinformatics, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
| | - Yimin Huang
- Department of Cellular Neurosciences, Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
| | - Elisabeth Orlowski
- Department of Cellular Neurosciences, Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
| | - Christina Krüger
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
| | - Rudolf A Deisz
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
| | - Darko Markovic
- Department of Neurosurgery, Helios Clinics, 13125 Berlin, Germany
| | - Charlotte Flüh
- Department of Neurosurgery, University Medical Center Schleswig-Holstein (UKSH), 24105 Kiel, Germany
| | - Andrew G Newman
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
| | - Ulf C Schneider
- Department of Neurosurgery, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
| | - Dieter Beule
- Core Unit Bioinformatics, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Susanne A Wolf
- Department of Ophthalmology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany
| | - Omar Dzaye
- Department of Radiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David H Gutmann
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Marcus Semtner
- Department of Cellular Neurosciences, Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
| | - Helmut Kettenmann
- Department of Cellular Neurosciences, Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany.
| | - Seija Lehnardt
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany; Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, 10117 Berlin, Germany.
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20
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Effect of Cladribine on Neuronal Apoptosis: New Insight of In Vitro Study in Multiple Sclerosis Therapy. Brain Sci 2020; 10:brainsci10080548. [PMID: 32823496 PMCID: PMC7464206 DOI: 10.3390/brainsci10080548] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/11/2020] [Accepted: 08/11/2020] [Indexed: 12/01/2022] Open
Abstract
Background: Cladribine (2-CdA) can cross the blood–brain barrier, resulting in inhibition of DNA synthesis and repair and disruption of cellular proliferation in actively dividing lymphocytes. No data on effect on neurons are available. Aim: To study “in vitro” 2-CdA apoptotic effects on neurons in healthy donor and multiple sclerosis patient lymphocytes. Methods: Neuroblastoma cells were co-cultured with lymphocytes, with and without 2-CdA. Results: Apoptosis increased in lymphocytes with 2-CdA; increase was also observed when lymphocytes were cultured with neuronal cells. However, neurons were not affected by 2-CdA for apoptosis. Conclusions: 2-CdA causes peripheral and central lymphocyte death preserving neurons, with a reasonable impact on inflammation and neuroprotection.
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21
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Rodríguez-Gómez JA, Kavanagh E, Engskog-Vlachos P, Engskog MK, Herrera AJ, Espinosa-Oliva AM, Joseph B, Hajji N, Venero JL, Burguillos MA. Microglia: Agents of the CNS Pro-Inflammatory Response. Cells 2020; 9:E1717. [PMID: 32709045 PMCID: PMC7407646 DOI: 10.3390/cells9071717] [Citation(s) in RCA: 168] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 12/21/2022] Open
Abstract
The pro-inflammatory immune response driven by microglia is a key contributor to the pathogenesis of several neurodegenerative diseases. Though the research of microglia spans over a century, the last two decades have increased our understanding exponentially. Here, we discuss the phenotypic transformation from homeostatic microglia towards reactive microglia, initiated by specific ligand binding to pattern recognition receptors including toll-like receptor-4 (TLR4) or triggering receptors expressed on myeloid cells-2 (TREM2), as well as pro-inflammatory signaling pathways triggered such as the caspase-mediated immune response. Additionally, new research disciplines such as epigenetics and immunometabolism have provided us with a more holistic view of how changes in DNA methylation, microRNAs, and the metabolome may influence the pro-inflammatory response. This review aimed to discuss our current knowledge of pro-inflammatory microglia from different angles, including recent research highlights such as the role of exosomes in spreading neuroinflammation and emerging techniques in microglia research including positron emission tomography (PET) scanning and the use of human microglia generated from induced pluripotent stem cells (iPSCs). Finally, we also discuss current thoughts on the impact of pro-inflammatory microglia in neurodegenerative diseases.
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Affiliation(s)
- José A. Rodríguez-Gómez
- Institute of Biomedicine of Seville (IBIS)-Hospital Universitario Virgen del Rocío/CSIC/University of Seville, 41012 Seville, Spain; (J.A.R.-G.); (A.J.H.); (A.M.E.-O.); (J.L.V.)
- Department of Medical Physiology and Biophysics, Faculty of Medicine, University of Seville, 41009 Sevilla, Spain
| | - Edel Kavanagh
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain;
| | - Pinelopi Engskog-Vlachos
- Institute of Environmental Medicine, Toxicology Unit, Karolinska Institute, 17177 Stockholm, Sweden; (P.E.-V.); (B.J.)
| | - Mikael K.R. Engskog
- Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry, Uppsala University, 751 23 Uppsala, Sweden;
| | - Antonio J. Herrera
- Institute of Biomedicine of Seville (IBIS)-Hospital Universitario Virgen del Rocío/CSIC/University of Seville, 41012 Seville, Spain; (J.A.R.-G.); (A.J.H.); (A.M.E.-O.); (J.L.V.)
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain;
| | - Ana M. Espinosa-Oliva
- Institute of Biomedicine of Seville (IBIS)-Hospital Universitario Virgen del Rocío/CSIC/University of Seville, 41012 Seville, Spain; (J.A.R.-G.); (A.J.H.); (A.M.E.-O.); (J.L.V.)
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain;
| | - Bertrand Joseph
- Institute of Environmental Medicine, Toxicology Unit, Karolinska Institute, 17177 Stockholm, Sweden; (P.E.-V.); (B.J.)
| | - Nabil Hajji
- Division of Brain Sciences, The John Fulcher Molecular Neuro-Oncology Laboratory, Imperial College London, London W12 ONN, UK;
| | - José L. Venero
- Institute of Biomedicine of Seville (IBIS)-Hospital Universitario Virgen del Rocío/CSIC/University of Seville, 41012 Seville, Spain; (J.A.R.-G.); (A.J.H.); (A.M.E.-O.); (J.L.V.)
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain;
| | - Miguel A. Burguillos
- Institute of Biomedicine of Seville (IBIS)-Hospital Universitario Virgen del Rocío/CSIC/University of Seville, 41012 Seville, Spain; (J.A.R.-G.); (A.J.H.); (A.M.E.-O.); (J.L.V.)
- Department of Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain;
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22
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23
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Cho KHT, Zeng N, Anekal PV, Xu B, Fraser M. Effects of delayed intraventricular TLR7 agonist administration on long-term neurological outcome following asphyxia in the preterm fetal sheep. Sci Rep 2020; 10:6904. [PMID: 32327682 PMCID: PMC7181613 DOI: 10.1038/s41598-020-63770-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 03/31/2020] [Indexed: 02/07/2023] Open
Abstract
In the preterm brain, accumulating evidence suggests toll-like receptors (TLRs) are key mediators of the downstream inflammatory pathways triggered by hypoxia-ischemia (HI), which have the potential to exacerbate or ameliorate injury. Recently we demonstrated that central acute administration of the TLR7 agonist Gardiquimod (GDQ) confers neuroprotection in the preterm fetal sheep at 3 days post-asphyxial recovery. However, it is unknown whether GDQ can afford long-term protection. To address this, we examined the long-term effects of GDQ. Briefly, fetal sheep (0.7 gestation) received sham asphyxia or asphyxia induced by umbilical cord occlusion, and were studied for 7 days recovery. Intracerebroventricular (ICV) infusion of GDQ (total dose 3.34 mg) or vehicle was performed from 1-4 hours after asphyxia. GDQ was associated with a robust increase in concentration of tumor necrosis factor-(TNF)-α in the fetal plasma, and interleukin-(IL)-10 in both the fetal plasma and cerebrospinal fluid. GDQ did not significantly change the number of total and immature/mature oligodendrocytes within the periventricular and intragyral white matter. No changes were observed in astroglial and microglial numbers and proliferating cells in both white matter regions. GDQ increased neuronal survival in the CA4 region of the hippocampus, but was associated with exacerbated neuronal injury within the caudate nucleus. In conclusion, our data suggest delayed acute ICV administration of GDQ after severe HI in the developing brain may not support long-term neuroprotection.
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Affiliation(s)
- Kenta H T Cho
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Nina Zeng
- Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Praju V Anekal
- Biomedical Imaging Research Unit, The University of Auckland, Auckland, New Zealand
| | - Bing Xu
- Department of Physiology, The University of Auckland, Auckland, New Zealand
- The Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen, 518000, People's Republic of China
| | - Mhoyra Fraser
- Department of Physiology, The University of Auckland, Auckland, New Zealand.
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24
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Dembny P, Newman AG, Singh M, Hinz M, Szczepek M, Krüger C, Adalbert R, Dzaye O, Trimbuch T, Wallach T, Kleinau G, Derkow K, Richard BC, Schipke C, Scheidereit C, Stachelscheid H, Golenbock D, Peters O, Coleman M, Heppner FL, Scheerer P, Tarabykin V, Ruprecht K, Izsvák Z, Mayer J, Lehnardt S. Human endogenous retrovirus HERV-K(HML-2) RNA causes neurodegeneration through Toll-like receptors. JCI Insight 2020; 5:131093. [PMID: 32271161 DOI: 10.1172/jci.insight.131093] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 03/04/2020] [Indexed: 01/27/2023] Open
Abstract
Although human endogenous retroviruses (HERVs) represent a substantial proportion of the human genome and some HERVs, such as HERV-K(HML-2), are reported to be involved in neurological disorders, little is known about their biological function. We report that RNA from an HERV-K(HML-2) envelope gene region binds to and activates human Toll-like receptor (TLR) 8, as well as murine Tlr7, expressed in neurons and microglia, thereby causing neurodegeneration. HERV-K(HML-2) RNA introduced into the cerebrospinal fluid (CSF) of either C57BL/6 wild-type mice or APPPS1 mice, a mouse model for Alzheimer's disease (AD), resulted in neurodegeneration and microglia accumulation. Tlr7-deficient mice were protected against neurodegenerative effects but were resensitized toward HERV-K(HML-2) RNA when neurons ectopically expressed murine Tlr7 or human TLR8. Transcriptome data sets of human AD brain samples revealed a distinct correlation of upregulated HERV-K(HML-2) and TLR8 RNA expression. HERV-K(HML-2) RNA was detectable more frequently in CSF from individuals with AD compared with controls. Our data establish HERV-K(HML-2) RNA as an endogenous ligand for species-specific TLRs 7/8 and imply a functional contribution of human endogenous retroviral transcripts to neurodegenerative processes, such as AD.
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Affiliation(s)
- Paul Dembny
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Andrew G Newman
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Manvendra Singh
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Michael Hinz
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Michal Szczepek
- Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH, Berlin, Germany
| | - Christina Krüger
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | | | - Omar Dzaye
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany.,Department of Radiology.,Department of Neuroradiology
| | | | - Thomas Wallach
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Gunnar Kleinau
- Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH, Berlin, Germany
| | - Katja Derkow
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | | | - Carola Schipke
- Department of Psychiatry and Psychotherapy, and.,Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH.,German Center for Neurodegenerative Diseases, Berlin, Germany
| | - Claus Scheidereit
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Harald Stachelscheid
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, BIH, Berlin-Brandenburg Center for Regenerative Therapies, Berlin, Germany
| | - Douglas Golenbock
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Oliver Peters
- Department of Psychiatry and Psychotherapy, and.,Experimental and Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH.,German Center for Neurodegenerative Diseases, Berlin, Germany
| | - Michael Coleman
- Babraham Institute and John van Geest Centre for Brain Repair, University of Cambridge, Cambridge, United Kingdom
| | - Frank L Heppner
- NeuroCure Cluster of Excellence.,Department of Neuropathology.,German Center for Neurodegenerative Diseases, Berlin, Germany
| | - Patrick Scheerer
- Institute for Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH, Berlin, Germany.,German Centre for Cardiovascular Research, partner site Berlin, Berlin, Germany
| | - Victor Tarabykin
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | - Klemens Ruprecht
- Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH, Berlin, Germany
| | - Zsuzsanna Izsvák
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Jens Mayer
- Institute of Human Genetics, Universität des Saarlandes, Hamburg, Germany
| | - Seija Lehnardt
- Institute of Cell Biology and Neurobiology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany.,Department of Neurology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and BIH, Berlin, Germany
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25
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Wallach T, Wetzel M, Dembny P, Staszewski O, Krüger C, Buonfiglioli A, Prinz M, Lehnardt S. Identification of CNS Injury-Related microRNAs as Novel Toll-Like Receptor 7/8 Signaling Activators by Small RNA Sequencing. Cells 2020; 9:E186. [PMID: 31940779 PMCID: PMC7017345 DOI: 10.3390/cells9010186] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/06/2020] [Accepted: 01/07/2020] [Indexed: 12/26/2022] Open
Abstract
Toll-like receptors (TLRs) belong to pattern recognition receptors, which respond to danger signals such as pathogen-associated molecular patterns or damage-associated molecular patterns. Upon TLR activation in microglia, the major immune cells in the brain, distinct signaling cascades trigger the production of inflammatory molecules, being a critical feature in neuroinflammation and neurodegenerative processes. Recently, individual microRNAs (miRNAs) were shown to act as endogenous TLR ligands. Here, we conducted systematic screening for miRNAs as potential TLR7/8 ligands by small RNA sequencing of apoptotic neurons and their corresponding supernatants. Several miRNA species were identified in both supernatants and injured neurons, and 83.3% of the media-enriched miRNAs activated murine and/or human TLR7/8 expressed in HEK293-derived TLR reporter cells. Among the detected extracellular miRNAs, distinct miRNAs such as miR-340-3p and miR-132-5p induced cytokine and chemokine release from microglia and triggered neurotoxicity in vitro. Taken together, our systematic study establishes miRNAs released from injured neurons as new TLR7/8 activators, which contribute to inflammatory and neurodegenerative responses in the central nervous system (CNS).
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Affiliation(s)
- Thomas Wallach
- Institute of Cell Biology and Neurobiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany; (T.W.); (M.W.); (P.D.); (C.K.); (A.B.)
| | - Max Wetzel
- Institute of Cell Biology and Neurobiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany; (T.W.); (M.W.); (P.D.); (C.K.); (A.B.)
| | - Paul Dembny
- Institute of Cell Biology and Neurobiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany; (T.W.); (M.W.); (P.D.); (C.K.); (A.B.)
| | - Ori Staszewski
- Institute of Neuropathology, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany; (O.S.); (M.P.)
- Berta-Ottenstein-Programme for Clinician Scientists, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - Christina Krüger
- Institute of Cell Biology and Neurobiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany; (T.W.); (M.W.); (P.D.); (C.K.); (A.B.)
| | - Alice Buonfiglioli
- Institute of Cell Biology and Neurobiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany; (T.W.); (M.W.); (P.D.); (C.K.); (A.B.)
| | - Marco Prinz
- Institute of Neuropathology, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany; (O.S.); (M.P.)
- Signalling Research Centres BIOSS and CIBSS, University of Freiburg, 79106 Freiburg, Germany
- Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - Seija Lehnardt
- Institute of Cell Biology and Neurobiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany; (T.W.); (M.W.); (P.D.); (C.K.); (A.B.)
- Department of Neurology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, 10117 Berlin, Germany
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26
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Persistent Toll-like receptor 7 stimulation induces behavioral and molecular innate immune tolerance. Brain Behav Immun 2019; 82:338-353. [PMID: 31499172 PMCID: PMC6956569 DOI: 10.1016/j.bbi.2019.09.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 12/18/2022] Open
Abstract
Toll-like receptors 7 and 8 (TLR7 and TLR8) are endosomal pattern recognition receptors that detect a variety of single-stranded RNA species. While TLR7/8 agonists have robust therapeutic potential, clinical utility of these agents is limited by sickness responses associated with treatment induction. To understand the kinetics and mechanism of these responses, we characterized the acute and chronic effects of TLR7 stimulation. Single-cell RNA-sequencing studies, RNAscope, and radiolabeled in situ hybridization demonstrate that central nervous system gene expression of TLR7 is exclusive to microglia. In vitro studies demonstrate that microglia are highly sensitive to TLR7 stimulation, and respond in a dose-dependent manner to the imidazoquinoline R848. In vivo, both intraperitoneal (IP) and intracerebroventricular (ICV) R848 induce acute sickness responses including hypophagia, weight loss, and decreased voluntary locomotor activity, associated with increased CNS pro-inflammatory gene expression and changes to glial morphology. However, chronic daily IP R848 resulted in rapid tachyphylaxis of behavioral and molecular manifestations of illness. In microglial in vitro assays, pro-inflammatory transcriptional responses rapidly diminished in the context of repeated R848. In addition to TLR7 desensitization, we found that microglia become partially refractory to lipopolysaccharide (LPS) following R848 pretreatment, associated with induction of negative regulators A20 and Irak3. Similarly, mice pre-treated with R848 demonstrate reduced sickness responses, hypothalamic inflammation, and hepatic inflammation in response to LPS. These data combined demonstrate that TLR7 stimulation induces acute behavioral and molecular evidence of sickness responses. Following prolonged dosing, R848 induces a refractory state to both TLR7 and TLR4 activation, consistent with induced immune tolerance.
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27
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Hu T, Yu H, Lu M, Yuan X, Wu X, Qiu H, Chen J, Huang S. TLR4 and nucleolin influence cell injury, apoptosis and inflammatory factor expression in respiratory syncytial virus-infected N2a neuronal cells. J Cell Biochem 2019; 120:16206-16218. [PMID: 31081244 DOI: 10.1002/jcb.28902] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 03/19/2019] [Accepted: 03/22/2019] [Indexed: 12/18/2022]
Abstract
Respiratory syncytial virus (RSV) infection was recently reported to be associated with central nervous system (CNS) symptoms and neurological complications; however, related studies are very limited. Moreover, the molecular mechanism underlying RSV neuropathogenesis is still unclear. Our previous study revealed that toll-like receptor 4 (TLR4) and nucleolin (C23) could be modulated and that they played a role during RSV infection in mouse neuronal-2a (N2a) cells. In the present study, the effects of silencing of TLR4 and C23 on RSV propagation and N2a cellular responses were examined by using RNA interference technology. Four N2a cell treatment groups were established, namely, a normal control group, RSV control group, TLR4 siRNA + RSV group, and C23 siRNA + RSV group. Expression changes in NeuN protein and colocalization of C23 and TLR4 with RSV F protein were assessed using confocal microscopy. Changes in TLR4 and C23 mRNA expression, TLR4, C23, TLR3, TLR7, and p-NF-κB protein expression, and interleukin (IL)-8, IL-6, and tumor necrosis factor (TNF-α) cytokine secretion was measured using quantitative real-time reverse-transcription polymerase chain reaction, Western blot analysis, and enzyme-linked immunosorbent assay, respectively. RSV titers and the apoptotic status of N2a cells were monitored using plaque formation assays and flow cytometry, respectively. The results indicated that TLR4 and C23 gene knockdown decreased the amount of F protein in RSV-infected N2a cells, inhibited RSV propagation, attenuated N2a neuronal injury, diminished cell apoptosis levels, downregulated TLR3 and TLR7 protein expression, and reduced inflammatory protein expression. Therefore, TLR4 and C23 knockdown influences cell injury, apoptosis and inflammatory protein expression in RSV-infected N2a cells.
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Affiliation(s)
- Tao Hu
- Department of Microbiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui, PR China
| | - Haiyang Yu
- Department of Microbiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui, PR China
| | - Min Lu
- Department of Laboratory, the first affiliated hospital of Anhui Medical University, Hefei, Anhui, PR China
| | - Xiaoling Yuan
- Department of Microbiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui, PR China
| | - Xuan Wu
- Department of Microbiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui, PR China
| | - Huan Qiu
- Department of Microbiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui, PR China
| | - Jason Chen
- Department of Microbiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui, PR China
- Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Shenghai Huang
- Department of Microbiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, Anhui, PR China
- School of Life Sciences, Anhui Medical University, Hefei, Anhui, PR China
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28
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Abstract
Innate immune signaling is an important feature in the pathology of alcohol use disorders. Alcohol abuse causes persistent innate immune activation in the brain. This is seen in postmortem human alcoholic brain specimens, as well as in primate and rodent models of alcohol consumption. Further, in vitro models of alcohol exposure in neurons and glia also demonstrate innate immune activation. The activation of the innate immune system seems to be important in the development of alcohol use pathology, as anti-immune therapies reduce pathology and ethanol self-administration in rodent models. Further, innate immune activation has been identified in each of the stages of addiction: binge/intoxication, withdrawal/negative affect, and preoccupation/craving. This suggests that innate immune activation may play a role both in the development and maintenance of alcoholic pathology. In this chapter, we discuss the known contributions of innate immune signaling in the pathology of alcohol use disorders, and present potential therapeutic interventions that may be beneficial for alcohol use disorders.
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Affiliation(s)
- Leon G Coleman
- Bowles Center for Alcohol Studies, Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA.
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Fulton T Crews
- Bowles Center for Alcohol Studies, Department of Pharmacology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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29
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Rizzo MD, Crawford RB, Bach A, Sermet S, Amalfitano A, Kaminski NE. Imiquimod and interferon-alpha augment monocyte-mediated astrocyte secretion of MCP-1, IL-6 and IP-10 in a human co-culture system. J Neuroimmunol 2019; 333:576969. [PMID: 31136945 DOI: 10.1016/j.jneuroim.2019.576969] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/10/2019] [Accepted: 05/17/2019] [Indexed: 12/11/2022]
Abstract
Toll-like receptor 7 (TLR7)-activation has been implicated as a significant mechanism of neuroinflammation triggered by ssRNA viruses. Infiltration of monocytes into the brain and astrocyte activation occurs during in vivo TLR7-mediated neuroinflammation. The objective here was to determine whether the TLR7 agonist, imiquimod, and interferon-alpha (IFN-α), promote monocyte-mediated astrocyte secretion of pro-inflammatory factors. Using a human primary co-culture system, we demonstrate that monocytes, together with imiquimod and IFN-α, promote astrocyte secretion of MCP-1, IL-6 and IP-10. Furthermore, TLR7-induced monocyte-derived IL-1β is critical for promoting the astrocyte response. Overall, this study provides a potential mechanism for TLR7-mediated neuroinflammation.
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Affiliation(s)
- Michael D Rizzo
- Michigan State University, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America; Cell & Molecular Biology Program, 1129 Farm Lane Rm. 311, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America; Institute for Integrative Toxicology, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America.
| | - Robert B Crawford
- Michigan State University, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America; Institute for Integrative Toxicology, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America
| | - Anthony Bach
- Michigan State University, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America; Institute for Integrative Toxicology, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America.
| | - Sera Sermet
- Michigan State University, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America.
| | - Andrea Amalfitano
- Michigan State University, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America; Department of Microbiology & Molecular Genetics, 4108 Biomedical Physical Sciences, East Lansing, MI 48824, United States of America; Department of Osteopathic Medicine, 4108 Biomedical Physical Sciences, East Lansing, MI 48824, United States of America.
| | - Norbert E Kaminski
- Michigan State University, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America; Institute for Integrative Toxicology, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America; Department of Pharmacology & Toxicology, 1129 Farm Lane Rm. 165G, Food Safety & Toxicology Bldg, East Lansing, MI 48824, United States of America.
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Lawrimore CJ, Coleman LG, Crews FT. Ethanol induces interferon expression in neurons via TRAIL: role of astrocyte-to-neuron signaling. Psychopharmacology (Berl) 2019; 236:2881-2897. [PMID: 30610351 PMCID: PMC6646093 DOI: 10.1007/s00213-018-5153-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/14/2018] [Indexed: 02/07/2023]
Abstract
RATIONALE Alcohol use disorder (AUD) involves dysregulation of innate immune signaling in brain. Toll-like receptor 3 (TLR3), an innate immune receptor that is upregulated in post-mortem human alcoholics, leads to induction of interferon (IFN) signaling. IFNs have been linked to depressive-like symptoms and therefore may play a role in addiction pathology. Astrocyte-neuronal signaling may contribute to maladaptation of neuronal circuits. OBJECTIVES In this manuscript, we examine ethanol (EtOH) induction of IFN signaling in neuronal, astrocyte, and microglial cell lines and assess astrocyte-neuronal interactions. METHODS U373 astrocytes, SH-SY5Y neurons, and BV2 microglia were treated with EtOH and analyzed for autocrine/paracrine IFN signaling. RESULTS EtOH induced TLR3, IFNβ, and IFNγ in SH-SY5Y neurons and U373 astrocytes, but not in BV2 microglia. The IFN response gene TRAIL was also strongly upregulated by TLR3 agonist Poly(I:C) and EtOH in U373 astrocytes. TRAIL blockage via neutralizing antibody prevented induction of IFNs in SH-SY5Y neurons but not in U373 astrocytes. Blocking TRAIL in conditioned media from EtOH-treated astrocytes prevented induction of IFNs in SH-SY5Y neurons. Finally, an in vivo model of chronic 10-day binge EtOH exposure in C57BL6/J mice, as well as single acute treatment with Poly(I:C), showed increased TRAIL +IR cells in both orbitofrontal and entorhinal cortex. CONCLUSIONS This study establishes a role of astrocyte to neuron TRAIL release in EtOH-induced IFN responses. This may contribute to alcohol associated negative affect and suggest potential therapeutic benefit of TRAIL inhibition in AUD.
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Affiliation(s)
- Colleen J. Lawrimore
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC USA ,Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC USA
| | - Leon G. Coleman
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC USA ,Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC USA
| | - Fulton T. Crews
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC USA ,Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC USA ,Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC USA
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31
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Caspases orchestrate microglia instrumental functions. Prog Neurobiol 2018; 171:50-71. [DOI: 10.1016/j.pneurobio.2018.09.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 09/21/2018] [Accepted: 09/29/2018] [Indexed: 12/16/2022]
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Fiebich BL, Batista CRA, Saliba SW, Yousif NM, de Oliveira ACP. Role of Microglia TLRs in Neurodegeneration. Front Cell Neurosci 2018; 12:329. [PMID: 30333729 PMCID: PMC6176466 DOI: 10.3389/fncel.2018.00329] [Citation(s) in RCA: 182] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 09/10/2018] [Indexed: 12/13/2022] Open
Abstract
Toll-like receptors (TLRs) are a group of receptors widely distributed in the organism. In the central nervous system, they are expressed in neurons, astrocytes and microglia. Although their involvement in immunity is notorious, different articles have demonstrated their roles in physiological and pathological conditions, including neurodegeneration. There is increasing evidence of an involvement of TLRs, especially TLR2, 4 and 9 in neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS). In this sense, their expression in microglia might modulate the activity of these cells, which in turn, lead to protective or deleterious effects over neurons and other cells. Therefore, TLRs might mediate the link between inflammation and neurodegenerative diseases. However, further studies have to be performed to elucidate the role of the other TLRs in these diseases and to further prove and confirm the pathophysiological role of all TLRs in neurodegeneration. In this article, we revise and summarize the current knowledge regarding the role of TLRs in neurodegeneration with the focus on the possible functions of these receptors in microglia.
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Affiliation(s)
- Bernd L Fiebich
- Neuroimmunology and Neurochemistry Research Group, Department of Psychiatry and Psychotherapy, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | | | - Soraya Wilke Saliba
- Neuroimmunology and Neurochemistry Research Group, Department of Psychiatry and Psychotherapy, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Nizar M Yousif
- Neuroimmunology and Neurochemistry Research Group, Department of Psychiatry and Psychotherapy, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
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Yuan X, Hu T, He H, Qiu H, Wu X, Chen J, Wang M, Chen C, Huang S. Respiratory syncytial virus prolifically infects N2a neuronal cells, leading to TLR4 and nucleolin protein modulations and RSV F protein co-localization with TLR4 and nucleolin. J Biomed Sci 2018; 25:13. [PMID: 29427996 PMCID: PMC6389248 DOI: 10.1186/s12929-018-0416-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 02/02/2018] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Respiratory syncytial virus (RSV) infects the central nervous system, resulting in neurological symptoms. However, the precise underlying pathogenic mechanisms have not been elucidated. In the present study, the infectivity of RSV on N2a neuronal cells and the possible roles of Toll-like receptor 4 (TLR4) and nucleolin (C23) during RSV infection were investigated. METHODS We compared two experimental groups (infected and non-infected) and monitored the RSV viral titers in the culture supernatant by a viral plaque assay. We also inspected the morphology of the nucleus in infected N2a cells. We measured the level of RSV F protein and studied its co-localization with TLR4 and nucleolin using immunofluorescence assays and laser confocal microscopy. The potential interaction of RSV F protein with TLR4 and nucleolin was examined by coimmunoprecipitation. The expression changes of TLR4, nucleolin, TLR3 and TLR7 proteins in N2a cells and IL-6 and TNF-α in the culture supernatant were investigated by Western Blot analysis and ELISA assay. Changes in neuronal cell apoptosis status was examined by flow cytometry. RESULTS The results demonstrated prolific RSV infection of N2a cells, which triggered a decrease of NeuN protein expression, coinciding with an increase of nuclear lesions, F protein expression, RSV viral titers, and late apoptotic levels of N2a cells. RSV infection induced co-localization of RSV F protein with TLR4 and nucleolin, which could potentially lead to a direct interaction. Furthermore, it was found that TLR4 and nucleolin levels increased early after infection and decreased subsequently, whereas TLR3 and TLR7 expression increased throughout RSV infection. CONCLUSION The RSV Long strain can prolifically infect N2a neuronal cells, modulating the expression of TLR4 and nucleolin, as well as TLR3, TLR7 and their downstream inflammatory factors, and inducing the co-localization of the RSV F protein with TLR4 and nucleolin.
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Affiliation(s)
- Xiaoling Yuan
- Department of Microbiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui Province 230032 People’s Republic of China
| | - Tao Hu
- Department of Microbiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui Province 230032 People’s Republic of China
| | - Hanwen He
- Department of Laboratory Medicine, Anhui Health College, Chizhou, Anhui Province 247099 People’s Republic of China
| | - Huan Qiu
- Department of Microbiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui Province 230032 People’s Republic of China
| | - Xuan Wu
- Department of Microbiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui Province 230032 People’s Republic of China
| | - Jingxian Chen
- Department of Microbiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui Province 230032 People’s Republic of China
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032 USA
| | - Minmin Wang
- Department of Microbiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui Province 230032 People’s Republic of China
| | - Cheng Chen
- Department of Clinical Medicine, Anhui Medical University, Hefei, Anhui Province 230032 People’s Republic of China
| | - Shenghai Huang
- Department of Microbiology, School of Basic Medicine, Anhui Medical University, Hefei, Anhui Province 230032 People’s Republic of China
- School of Life Sciences, Anhui Medical University, Hefei, Anhui Province 230032 People’s Republic of China
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The role of neuroimmune signaling in alcoholism. Neuropharmacology 2017; 122:56-73. [PMID: 28159648 DOI: 10.1016/j.neuropharm.2017.01.031] [Citation(s) in RCA: 208] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 01/24/2017] [Accepted: 01/29/2017] [Indexed: 02/07/2023]
Abstract
Alcohol consumption and stress increase brain levels of known innate immune signaling molecules. Microglia, the innate immune cells of the brain, and neurons respond to alcohol, signaling through Toll-like receptors (TLRs), high-mobility group box 1 (HMGB1), miRNAs, pro-inflammatory cytokines and their associated receptors involved in signaling between microglia, other glia and neurons. Repeated cycles of alcohol and stress cause a progressive, persistent induction of HMGB1, miRNA and TLR receptors in brain that appear to underlie the progressive and persistent loss of behavioral control, increased impulsivity and anxiety, as well as craving, coupled with increasing ventral striatal responses that promote reward seeking behavior and increase risk of developing alcohol use disorders. Studies employing anti-oxidant, anti-inflammatory, anti-depressant, and innate immune antagonists further link innate immune gene expression to addiction-like behaviors. Innate immune molecules are novel targets for addiction and affective disorders therapies. This article is part of the Special Issue entitled "Alcoholism".
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Coleman LG, Zou J, Crews FT. Microglial-derived miRNA let-7 and HMGB1 contribute to ethanol-induced neurotoxicity via TLR7. J Neuroinflammation 2017; 14:22. [PMID: 28118842 PMCID: PMC5264311 DOI: 10.1186/s12974-017-0799-4] [Citation(s) in RCA: 154] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Accepted: 01/16/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Toll-like receptor (TLR) signaling is emerging as an important component of neurodegeneration. TLR7 senses viral RNA and certain endogenous miRNAs to initiate innate immune responses leading to neurodegeneration. Alcoholism is associated with hippocampal degeneration, with preclinical studies linking ethanol-induced neurodegeneration with central innate immune induction and TLR activation. The endogenous miRNA let-7b binds TLR7 to cause neurodegeneration. METHODS TLR7 and other immune markers were assessed in postmortem human hippocampal tissue that was obtained from the New South Wales Tissue Bank. Rat hippocampal-entorhinal cortex (HEC) slice culture was used to assess specific effects of ethanol on TLR7, let-7b, and microvesicles. RESULTS We report here that hippocampal tissue from postmortem human alcoholic brains shows increased expression of TLR7 and increased microglial activation. Using HEC slice culture, we found that ethanol induces TLR7 and let-7b expression. Ethanol caused TLR7-associated neuroimmune gene induction and initiated the release let-7b in microvesicles (MVs), enhancing TLR7-mediated neurotoxicity. Further, ethanol increased let-7b binding to the danger signaling molecule high mobility group box-1 (HMGB1) in MVs, while reducing let-7 binding to classical chaperone protein argonaute (Ago2). Flow cytometric analysis of MVs from HEC media and analysis of MVs from brain cell culture lines found that microglia were the primary source of let-7b and HMGB1-containing MVs. CONCLUSIONS Our results identify that ethanol induces neuroimmune pathology involving the release of let-7b/HMGB1 complexes in microglia-derived microvesicles. This contributes to hippocampal neurodegeneration and may play a role in the pathology of alcoholism.
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Affiliation(s)
- Leon G Coleman
- Bowles Center for Alcohol Studies, The University of North Carolina School of Medicine, 104 Manning Drive, 1007 Thurston-Bowles Building, CB# 7178 UNC-CH, Chapel Hill, NC, 27599, USA. .,Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, 104 Manning Drive, CB#7178, Thurston-Bowles Building Room 1007, Chapel Hill, NC, 27599, USA.
| | - Jian Zou
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, 104 Manning Drive, CB#7178, Thurston-Bowles Building Room 1007, Chapel Hill, NC, 27599, USA
| | - Fulton T Crews
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, 104 Manning Drive, CB#7178, Thurston-Bowles Building Room 1007, Chapel Hill, NC, 27599, USA
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Paul AM, Acharya D, Le L, Wang P, Stokic DS, Leis AA, Alexopoulou L, Town T, Flavell RA, Fikrig E, Bai F. TLR8 Couples SOCS-1 and Restrains TLR7-Mediated Antiviral Immunity, Exacerbating West Nile Virus Infection in Mice. THE JOURNAL OF IMMUNOLOGY 2016; 197:4425-4435. [PMID: 27798161 DOI: 10.4049/jimmunol.1600902] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 09/29/2016] [Indexed: 12/11/2022]
Abstract
West Nile virus (WNV) is a neurotropic ssRNA flavivirus that can cause encephalitis, meningitis, and death in humans and mice. Human TLR7 and TLR8 and mouse TLR7 recognize viral ssRNA motifs and induce antiviral immunity. However, the role of mouse TLR8 in antiviral immunity is poorly understood. In this article, we report that TLR8-deficient (Tlr8-/-) mice were resistant to WNV infection compared with wild-type controls. Efficient WNV clearance and moderate susceptibility to WNV-mediated neuronal death in Tlr8-/- mice were attributed to overexpression of Tlr7 and IFN-stimulated gene-56 expression, whereas reduced expression of the proapoptotic gene coding Bcl2-associated X protein was observed. Interestingly, suppressor of cytokine signaling (SOCS)-1 directly associated with TLR8, but not with TLR7, indicating a novel role for TLR8 regulation of SOCS-1 function, whereas selective small interfering RNA knockdown of Socs-1 resulted in induced IFN-stimulated gene-56 and Tlr7 expression following WNV infection. Collectively, we report that TLR8 coupling with SOCS-1 inhibits TLR7-mediated antiviral immunity during WNV infection in mice.
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Affiliation(s)
- Amber M Paul
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406
| | - Dhiraj Acharya
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406
| | - Linda Le
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406
| | - Penghua Wang
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520.,Department of Microbiology and Immunology, School of Medicine, New York Medical College, Valhalla, NY 10595
| | - Dobrivoje S Stokic
- Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, MS 39216
| | - A Arturo Leis
- Center for Neuroscience and Neurological Recovery, Methodist Rehabilitation Center, Jackson, MS 39216
| | - Lena Alexopoulou
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2, INSERM, U1104, CNRS UMR7280, 13288 Marseille, France
| | - Terrence Town
- Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90033
| | - Richard A Flavell
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520; and.,Howard Hughes Medical Institute, New Haven, CT 06520
| | - Erol Fikrig
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520.,Howard Hughes Medical Institute, New Haven, CT 06520
| | - Fengwei Bai
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, MS 39406;
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Wu PJ, Liu HY, Huang TN, Hsueh YP. AIM 2 inflammasomes regulate neuronal morphology and influence anxiety and memory in mice. Sci Rep 2016; 6:32405. [PMID: 27561456 PMCID: PMC5000013 DOI: 10.1038/srep32405] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 08/09/2016] [Indexed: 12/20/2022] Open
Abstract
Inflammasomes are the protein assemblies that consist of inflammasome sensors, adaptor apoptosis-associated speck-like proteins containing a CARD (ASC) and inflammasome caspase. Inflammasomes sense multiple danger signals via various inflammasome sensors and consequently use caspase to trigger proteolytic processing and secretion of IL-1β cytokines. Recent studies have suggested that neurons use their own innate immune system to detect danger signals and regulate neuronal morphology. Here, we investigate whether inflammasomes, the critical components of innate immunity, participate in regulation of neuronal morphology and function. Among various sensors, Absent in melanoma 2 (Aim2) expression in neurons is most prominent. Adding synthetic double-stranded DNA (dsDNA) to cultured neurons induces IL-1β secretion in an AIM2-dependent manner and consequently downregulates dendritic growth but enhances axon extension. The results of Aim2 knockout and knockdown show that AIM2 acts cell-autonomously to regulate neuronal morphology. Behavioral analyses further reveal that Aim2-/- mice exhibit lower locomotor activity, increased anxious behaviors and reduced auditory fear memory. In conclusion, our study suggests that AIM2 inflammasomes regulate neuronal morphology and influence mouse behaviors.
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Affiliation(s)
- Pei-Jung Wu
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Hsin-Yu Liu
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Tzyy-Nan Huang
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Yi-Ping Hsueh
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan.,Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
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Mukherjee P, Winkler CW, Taylor KG, Woods TA, Nair V, Khan BA, Peterson KE. SARM1, Not MyD88, Mediates TLR7/TLR9-Induced Apoptosis in Neurons. THE JOURNAL OF IMMUNOLOGY 2015; 195:4913-21. [PMID: 26423149 DOI: 10.4049/jimmunol.1500953] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 09/08/2015] [Indexed: 01/09/2023]
Abstract
Neuronal apoptosis is a key aspect of many different neurologic diseases, but the mechanisms remain unresolved. Recent studies have suggested a mechanism of innate immune-induced neuronal apoptosis through the stimulation of endosomal TLRs in neurons. TLRs are stimulated both by pathogen-associated molecular patterns as well as by damage-associated molecular patterns, including microRNAs released by damaged neurons. In the present study, we identified the mechanism responsible for TLR7/TLR9-mediated neuronal apoptosis. TLR-induced apoptosis required endosomal localization of TLRs but was independent of MyD88 signaling. Instead, apoptosis required the TLR adaptor molecule SARM1, which localized to the mitochondria following TLR activation and was associated with mitochondrial accumulation in neurites. Deficiency in SARM1 inhibited both mitochondrial accumulation in neurites and TLR-induced apoptosis. These studies identify a non-MyD88 pathway of TLR7/ TLR9 signaling in neurons and provide a mechanism for how innate immune responses in the CNS directly induce neuronal damage.
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Affiliation(s)
- Piyali Mukherjee
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840; and
| | - Clayton W Winkler
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840; and
| | - Katherine G Taylor
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840; and
| | - Tyson A Woods
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840; and
| | - Vinod Nair
- Research Technologies Branch, Microscopy Unit, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840
| | - Burhan A Khan
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840; and
| | - Karin E Peterson
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840; and
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Derkow K, Krüger C, Dembny P, Lehnardt S. Microglia Induce Neurotoxic IL-17+ γδ T Cells Dependent on TLR2, TLR4, and TLR9 Activation. PLoS One 2015; 10:e0135898. [PMID: 26288016 PMCID: PMC4545749 DOI: 10.1371/journal.pone.0135898] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 07/28/2015] [Indexed: 11/29/2022] Open
Abstract
Background Interleukin-17 (IL-17) acts as a key regulator in central nervous system (CNS) inflammation. γδ T cells are an important innate source of IL-17. Both IL-17+ γδ T cells and microglia, the major resident immune cells of the brain, are involved in various CNS disorders such as multiple sclerosis and stroke. Also, activation of Toll-like receptor (TLR) signaling pathways contributes to CNS damage. However, the mechanisms underlying the regulation and interaction of these cellular and molecular components remain unclear. Objective In this study, we investigated the crosstalk between γδ T cells and microglia activated by TLRs in the context of neuronal damage. To this end, co-cultures of IL-17+ γδ T cells, neurons, and microglia were analyzed by immunocytochemistry, flow cytometry, ELISA and multiplex immunoassays. Results We report here that IL-17+ γδ T cells but not naïve γδ T cells induce a dose- and time-dependent decrease of neuronal viability in vitro. While direct stimulation of γδ T cells with various TLR ligands did not result in up-regulation of CD69, CD25, or in IL-17 secretion, supernatants of microglia stimulated by ligands specific for TLR2, TLR4, TLR7, or TLR9 induced activation of γδ T cells through IL-1β and IL-23, as indicated by up-regulation of CD69 and CD25 and by secretion of vast amounts of IL-17. This effect was dependent on the TLR adaptor myeloid differentiation primary response gene 88 (MyD88) expressed by both γδ T cells and microglia, but did not require the expression of TLRs by γδ T cells. Similarly to cytokine-primed IL-17+ γδ T cells, IL-17+ γδ T cells induced by supernatants derived from TLR-activated microglia also caused neurotoxicity in vitro. While these neurotoxic effects required stimulation of TLR2, TLR4, or TLR9 in microglia, neuronal injury mediated by bone marrow-derived macrophages did not require TLR signaling. Neurotoxicity mediated by IL-17+ γδ T cells required a direct cell-cell contact between T cells and neurons. Conclusion Taken together, these results point to a crucial role for microglia activated through TLRs in polarization of γδ T cells towards neurotoxic IL-17+ γδ T cells.
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Affiliation(s)
- Katja Derkow
- Department of Neurology, Charité - Universitaetsmedizin Berlin, Berlin, Germany
| | - Christina Krüger
- Department of Neurology, Charité - Universitaetsmedizin Berlin, Berlin, Germany
| | - Paul Dembny
- Department of Neurology, Charité - Universitaetsmedizin Berlin, Berlin, Germany
| | - Seija Lehnardt
- Department of Neurology, Charité - Universitaetsmedizin Berlin, Berlin, Germany; Cluster of Excellence NeuroCure, Charité - Universitaetsmedizin Berlin, Berlin, Germany; Institute of Cell Biology and Neurobiology, Center for Anatomy, Charité - Universitaetsmedizin Berlin, Berlin, Germany
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Zhang J, Banerjee B. Role of MicroRNA in Visceral Pain. J Neurogastroenterol Motil 2015; 21:159-71. [PMID: 25843071 PMCID: PMC4398244 DOI: 10.5056/jnm15027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 03/19/2015] [Accepted: 03/27/2015] [Indexed: 12/30/2022] Open
Abstract
The long-lasting nociceptive transmission under various visceral pain conditions involves transcriptional and/or translational alteration in neurotransmitter and receptor expression as well as modification of neuronal function, morphology and synaptic connections. Although it is largely unknown how such changes in posttranscriptional expression induce visceral pain, recent evidence strongly suggests an important role for microRNAs (miRNAs, small non-coding RNAs) in the cellular plasticity underlying chronic visceral pain. MicroRNAs are small noncoding RNA endogenously produced in our body and act as a major regulator of gene expression by either through cleavage or translational repression of the target gene. This regulation is essential for the normal physiological function but when disturbed can result in pathological conditions. Usually one miRNA has multiple targets and target mRNAs are regulated in a combinatorial fashion by multiple miRNAs. In recent years, many studies have been performed to delineate the posttranscriptional regulatory role of miRNAs in different tissues under various nociceptive stimuli. In this review, we intend to discuss the recent development in miRNA research with special emphases on miRNAs and their targets responsible for long term sensitization in chronic pain conditions. In addition, we review miRNAs expression and function data for different animal pain models and also the recent progress in research on miRNA-based therapeutic targets for the treatment of chronic pain.
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Affiliation(s)
- Jian Zhang
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin Milwaukee, WI , USA
| | - Banani Banerjee
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin Milwaukee, WI , USA
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Intrathecal heat shock protein 60 mediates neurodegeneration and demyelination in the CNS through a TLR4- and MyD88-dependent pathway. Mol Neurodegener 2015; 10:5. [PMID: 25887709 PMCID: PMC4365525 DOI: 10.1186/s13024-015-0003-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 02/03/2015] [Indexed: 01/11/2023] Open
Abstract
Background Toll-like receptors (TLR) constitute a highly conserved class of receptors through which the innate immune system responds to both pathogen- and host-derived factors. Although TLRs are involved in a wide range of central nervous system (CNS) disorders including neurodegenerative diseases, the molecular events leading from CNS injury to activation of these innate immune receptors remain elusive. The stress protein heat shock protein 60 (HSP60) released from injured cells is considered an endogenous danger signal of the immune system. In this context, the main objective of the present study was to investigate the impact of extracellular HSP60 on the brain in vivo. Results We show here that HSP60 injected intrathecally causes neuronal and oligodendrocyte injury in the CNS in vivo through TLR4-dependent signaling. Intrathecal HSP60 results in neuronal cell death, axonal injury, loss of oligodendrocytes, and demyelination in the cerebral cortex of wild-type mice. In contrast both mice lacking TLR4 and the TLR adaptor molecule MyD88 are protected against deleterious effects induced by HSP60. In contrast to the exogenous TLR4 ligand, lipopolysaccharide, intrathecal HSP60 does not induce such a considerable inflammatory response in the brain. In the CNS, endogenous HSP60 is predominantly expressed in neurons and released during brain injury, since the cerebrospinal fluid (CSF) from animals of a mouse stroke model contains elevated levels of this stress protein compared to the CSF of sham-operated mice. Conclusions Our data show a direct toxic effect of HSP60 towards neurons and oligodendrocytes in the CNS. The fact that these harmful effects involve TLR4 and MyD88 confirms a molecular pathway mediated by the release of endogenous TLR ligands from injured CNS cells common to many forms of brain diseases that bi-directionally links CNS injury and activation of the innate immune system to neurodegeneration and demyelination in vivo. Electronic supplementary material The online version of this article (doi:10.1186/s13024-015-0003-1) contains supplementary material, which is available to authorized users.
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Trendelenburg G. Molecular regulation of cell fate in cerebral ischemia: role of the inflammasome and connected pathways. J Cereb Blood Flow Metab 2014; 34:1857-67. [PMID: 25227604 PMCID: PMC4269743 DOI: 10.1038/jcbfm.2014.159] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/13/2014] [Accepted: 08/25/2014] [Indexed: 12/19/2022]
Abstract
Analogous to Toll-like receptors, NOD-like receptors represent a class of pattern recognition receptors, which are cytosolic and constitute part of different inflammasomes. These large protein complexes are activated not only by different pathogens, but also by sterile inflammation or by specific metabolic conditions. Mutations can cause hereditary autoinflammatory systemic diseases, and inflammasome activation has been linked to many multifactorial diseases, such as diabetes or cardiovascular diseases. Increasing data also support an important role in different central nervous diseases such as stroke. Thus, the current knowledge of the functional role of this intracellular 'master switch' of inflammation is discussed with a focus on its role in ischemic stroke, neurodegeneration, and also with regard to the recent data which argues for a relevant role in other organs or biologic systems which influence stroke incidence or prognosis.
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Affiliation(s)
- George Trendelenburg
- Department of Neurology, University Medical Center Göttingen, Göttingen, Germany
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Rosenberger K, Derkow K, Dembny P, Krüger C, Schott E, Lehnardt S. The impact of single and pairwise Toll-like receptor activation on neuroinflammation and neurodegeneration. J Neuroinflammation 2014; 11:166. [PMID: 25239168 PMCID: PMC4182775 DOI: 10.1186/s12974-014-0166-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 09/09/2014] [Indexed: 01/17/2023] Open
Abstract
Background Toll-like receptors (TLRs) enable innate immune cells to respond to pathogen- and host-derived molecules. The central nervous system (CNS) exhibits most of the TLRs identified with predominant expression in microglia, the major immune cells of the brain. Although individual TLRs have been shown to contribute to CNS disorders, the consequences of multiple activated TLRs on the brain are unclear. We therefore systematically investigated and compared the impact of sole and pairwise TLR activation on CNS inflammation and injury. Methods Selected TLRs expressed in microglia and neurons were stimulated with their specific TLR ligands in varying combinations. Cell cultures were then analyzed by immunocytochemistry, FlowCytomix, and ELISA. To determine neuronal injury and neuroinflammation in vivo, C57BL/6J mice were injected intrathecally with TLR agonists. Subsequently, brain sections were analyzed by quantitative real-time PCR and immunohistochemistry. Results Simultaneous stimulation of TLR4 plus TLR2, TLR4 plus TLR9, and TLR2 plus TLR9 in microglia by their respective specific ligands results in an increased inflammatory response compared to activation of the respective single TLR in vitro. In contrast, additional activation of TLR7 suppresses the inflammatory response mediated by the respective ligands for TLR2, TLR4, or TLR9 up to 24 h, indicating that specific combinations of activated TLRs individually modulate the inflammatory response. Accordingly, the composition of the inflammatory response pattern generated by microglia varies depending on the identity and combination of the activated TLRs engaged. Likewise, neuronal injury occurs in response to activation of only selected TLRs and TLR combinations in vitro. Activation of TLR2, TLR4, TLR7, and TLR9 in the brain by intrathecal injection of the respective TLR ligand into C57BL/6J mice leads to specific expression patterns of distinct TLR mRNAs in the brain and causes influx of leukocytes and inflammatory mediators into the cerebrospinal fluid to a variable extent. Also, the intensity of the inflammatory response and neurodegenerative effects differs according to the respective activated TLR and TLR combinations used in vivo. Conclusions Sole and pairwise activation of TLRs modifies the pattern and extent of inflammation and neurodegeneration in the CNS, thereby enabling innate immunity to take account of the CNS diseases’ diversity. Electronic supplementary material The online version of this article (doi:10.1186/s12974-014-0166-7) contains supplementary material, which is available to authorized users.
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Innate immune responses regulate morphogenesis and degeneration: roles of Toll-like receptors and Sarm1 in neurons. Neurosci Bull 2014; 30:645-54. [PMID: 24993772 DOI: 10.1007/s12264-014-1445-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 04/28/2014] [Indexed: 10/25/2022] Open
Abstract
The central nervous system is recognized as an immunoprivileged site because peripheral immune cells do not typically enter it. Microglial cells are thought to be the main immune cells in brain. However, recent reports have indicated that neurons express the key players of innate immunity, including Toll-like receptors (TLRs) and their adaptor proteins (Sarm1, Myd88, and Trif), and may produce cytokines in response to pathogen infection. In the absence of an immune challenge, neuronal TLRs can detect intrinsic danger signals and modulate neuronal morphology and function. In this article, we review the recent findings on the involvement of TLRs and Sarm1 in controlling neuronal morphogenesis and neurodegeneration. Abnormal behaviors in TLR- and Sarm1-deficient mice are also discussed.
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Winkler CW, Taylor KG, Peterson KE. Location is everything: let-7b microRNA and TLR7 signaling results in a painful TRP. Sci Signal 2014; 7:pe14. [PMID: 24866018 DOI: 10.1126/scisignal.2005407] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Extracellular let-7b, a microRNA found in the central nervous system, affects neurons through its interaction with Toll-like receptor 7 (TLR7), but with divergent outcomes in different neurons. Lehmann et al. found that let-7b stimulation of cortical and hippocampal neurons led to neuronal apoptosis, whereas Park et al. report that let-7b activation of TLR7 stimulated the cation channel transient receptor potential A1 (TRPA1) on dorsal root ganglia sensory neurons and induced pain responses. The primary difference that may influence these distinct responses to let-7b is the localization of TLR7 to the endosome in the cortical and hippocampal neurons or the plasma membrane in the sensory neurons. These studies suggest that different types of neurons traffic TLR7 to distinct membrane locations, affecting the functional response of neurons to let-7b stimulation.
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Affiliation(s)
- Clayton W Winkler
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
| | - Katherine G Taylor
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA
| | - Karin E Peterson
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.
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Abstract
Toll-like receptors (TLRs) recognize both pathogen- and danger-associated molecular patterns and induce innate immune responses. Some TLRs are expressed in neurons and regulate neurodevelopment and neurodegeneration. However, the downstream signaling pathways and effectors for TLRs in neurons are still controversial. In this report, we provide evidence that TLR7 negatively regulates dendrite growth through the canonical myeloid differentiation primary response gene 88 (Myd88)-c-Fos-interleukin (IL)-6 pathway. Although both TLR7 and TLR8 recognize single-stranded RNA (ssRNA), the results of quantitative reverse transcription-PCR suggested that TLR7 is the major TLR recognizing ssRNA in brains. In both in vitro cultures and in utero electroporation experiments, manipulation of TLR7 expression levels was sufficient to alter neuronal morphology, indicating the presence of intrinsic TLR7 ligands. Besides, the RNase A treatment that removed ssRNA in cultures promoted dendrite growth. We also found that the addition of ssRNA and synthetic TLR7 agonists CL075 and loxoribine, but not R837 (imiquimod), to cultured neurons specifically restricted dendrite growth via TLR7. These results all suggest that TLR7 negatively regulates neuronal differentiation. In cultured neurons, TLR7 activation induced IL-6 and TNF-α expression through Myd88. Using Myd88-, IL-6-, and TNF-α-deficient neurons, we then demonstrated the essential roles of Myd88 and IL-6, but not TNF-α, in the TLR7 pathway to restrict dendrite growth. In addition to neuronal morphology, TLR7 knockout also affects mouse behaviors, because young mutant mice ∼2 weeks of age exhibited noticeably lower exploratory activity in an open field. In conclusion, our study suggests that TLR7 negatively regulates dendrite growth and influences cognition in mice.
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Swaminathan G, Martin-Garcia J, Navas-Martin S. RNA viruses and microRNAs: challenging discoveries for the 21st century. Physiol Genomics 2013; 45:1035-48. [PMID: 24046280 DOI: 10.1152/physiolgenomics.00112.2013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
RNA viruses represent the predominant cause of many clinically relevant viral diseases in humans. Among several evolutionary advantages acquired by RNA viruses, the ability to usurp host cellular machinery and evade antiviral immune responses is imperative. During the past decade, RNA interference mechanisms, especially microRNA (miRNA)-mediated regulation of cellular protein expression, have revolutionized our understanding of host-viral interactions. Although it is well established that several DNA viruses express miRNAs that play crucial roles in their pathogenesis, expression of miRNAs by RNA viruses remains controversial. However, modulation of the miRNA machinery by RNA viruses may confer multiple benefits for enhanced viral replication and survival in host cells. In this review, we discuss the current literature on RNA viruses that may encode miRNAs and the varied advantages of engineering RNA viruses to express miRNAs as potential vectors for gene therapy. In addition, we review how different families of RNA viruses can alter miRNA machinery for productive replication, evasion of antiviral immune responses, and prolonged survival. We underscore the need to further explore the complex interactions of RNA viruses with host miRNAs to augment our understanding of host-virus interplay.
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Affiliation(s)
- Gokul Swaminathan
- Microbiology and Immunology Graduate Program, Drexel University College of Medicine, Philadelphia, Pennsylvania
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Affiliation(s)
- Sophia Häfner
- Univ. Paris Diderot, Sorbonne Paris Cité, UMR 7216 CNRS, Epigenetics and Cell Fate, 75013 Paris, France.
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