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Ball JB, Frank MG, Green-Fulgham SM, Watkins LR. Use of adeno-associated viruses for transgenic modulation of microglia structure and function: A review of technical considerations and challenges. Brain Behav Immun 2024; 118:368-379. [PMID: 38471576 DOI: 10.1016/j.bbi.2024.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 02/08/2024] [Accepted: 03/03/2024] [Indexed: 03/14/2024] Open
Abstract
Microglia play a central role in the etiology of many neuropathologies. Transgenic tools are a powerful experiment approach to gain reliable and specific control over microglia function. Adeno-associated virus (AAVs) vectors are already an indispensable tool in neuroscience research. Despite ubiquitous use of AAVs and substantial interest in the role of microglia in the study of central nervous system (CNS) function and disease, transduction of microglia using AAVs is seldom reported. This review explores the challenges and advancements made in using AAVs for expressing transgenes in microglia. First, we will examine the functional anatomy of the AAV capsid, which will serve as a basis for subsequent discussions of studies exploring the relationship between capsid mutations and microglia transduction efficacy. After outlining the functional anatomy of AAVs, we will consider the experimental evidence demonstrating AAV-mediated transduction of microglia and microglia-like cell lines followed by an examination of the most promising experimental approaches identified in the literature. Finally, technical limitations will be considered in future applications of AAV experimental approaches.
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Affiliation(s)
- Jayson B Ball
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado, Boulder, CO 80309, USA.
| | - Matthew G Frank
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado, Boulder, CO 80309, USA
| | - Suzanne M Green-Fulgham
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado, Boulder, CO 80309, USA
| | - Linda R Watkins
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado, Boulder, CO 80309, USA
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2
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Frank MG, Baratta MV. Use of an immunocapture device to detect cytokine release in discrete brain regions. Neural Regen Res 2024; 19:703-704. [PMID: 37843193 PMCID: PMC10664115 DOI: 10.4103/1673-5374.382237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/19/2023] [Accepted: 06/30/2023] [Indexed: 10/17/2023] Open
Affiliation(s)
- Matthew G. Frank
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA
| | - Michael V. Baratta
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, USA
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3
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Green-Fulgham SM, Ball JB, Kwilasz AJ, Harland ME, Frank MG, Dragavon JM, Grace PM, Watkins LR. Interleukin-1beta and inflammasome expression in spinal cord following chronic constriction injury in male and female rats. Brain Behav Immun 2024; 115:157-168. [PMID: 37838078 PMCID: PMC10841465 DOI: 10.1016/j.bbi.2023.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 10/02/2023] [Accepted: 10/07/2023] [Indexed: 10/16/2023] Open
Abstract
Females represent a majority of chronic pain patients and show greater inflammatory immune responses in human chronic pain patient populations as well as in animal models of neuropathic pain. Recent discoveries in chronic pain research have revealed sex differences in inflammatory signaling, a key component of sensory pathology in chronic neuropathic pain, inviting more research into the nuances of these sex differences. Here we use the chronic constriction injury (CCI) model to explore similarities and differences in expression and production of Inflammatory cytokine IL-1beta in the lumbar spinal cord, as well as its role in chronic pain. We have discovered that intrathecal IL-1 receptor antagonist reverses established pain in both sexes, and increased gene expression of inflammasome NLRP3 is specific to microglia and astrocytes rather than neurons, while IL-1beta is specific to microglia in both sexes. We report several sex differences in the expression level of the genes coding for IL-1beta, as well as the four inflammasomes responsible for IL-1beta release: NLRP3, AIM2, NLRP1, and NLRC4 in the spinal cord. Total mRNA, but not protein expression of IL-1beta is greater in females than males after CCI. Also, while CCI increases all four inflammasomes in both sexes, there are sex differences in relative levels of inflammasome expression. NLRP3 and AIM2 are more highly expressed in females, whereas NLRP1 expression is greater in males.
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Affiliation(s)
- Suzanne M Green-Fulgham
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Jayson B Ball
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Andrew J Kwilasz
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Michael E Harland
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Matthew G Frank
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado, Boulder, CO, United States
| | - Joseph M Dragavon
- Advanced Light Microscopy Core, BioFrontiers Institute, University of Colorado, Boulder, CO, United States
| | - Peter M Grace
- Laboratories of Neuroimmunology, Department of Symptom Research, University of Texas MD Anderson Cancer Center, Houston, TX, United States
| | - Linda R Watkins
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado, Boulder, CO, United States.
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4
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Coleman PT, Costanza-Chavez GW, Martin HN, Amat J, Frank MG, Sanchez RJ, Potter GJ, Mellert SM, Carter RK, Bonnici GN, Maier SF, Baratta MV. Prior experience with behavioral control over stress facilitates social dominance. Neurobiol Stress 2024; 28:100597. [PMID: 38213318 PMCID: PMC10783635 DOI: 10.1016/j.ynstr.2023.100597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 11/13/2023] [Accepted: 12/01/2023] [Indexed: 01/13/2024] Open
Abstract
Dominance status has extensive effects on physical and mental health, and an individual's relative position can be shaped by experiential factors. A variety of considerations suggest that the experience of behavioral control over stressors should produce winning in dominance tests and that winning should blunt the impact of later stressors, as does prior control. To investigate the interplay between competitive success and stressor control, we first examined the impact of stressor controllability on subsequent performance in a warm spot competition test modified for rats. Prior experience of controllable, but not physically identical uncontrollable, stress increased later effortful behavior and occupation of the warm spot. Controllable stress subjects consistently ranked higher than did uncontrollable stress subjects. Pharmacological inactivation of the prelimbic (PL) cortex during behavioral control prevented later facilitation of dominance. Next, we explored whether repeated winning experiences produced later resistance against the typical sequelae of uncontrollable stress. To establish dominance status, triads of rats were given five sessions of warm spot competition. The development of stable dominance was prevented by reversible inactivation of the PL or NMDA receptor blockade in the dorsomedial striatum. Stable winning blunted the later stress-induced increase in dorsal raphe nucleus serotonergic activity, as well as prevented uncontrollable stress-induced social avoidance. In contrast, endocrine and neuroimmune responses to uncontrollable stress were unaffected, indicating a selective impact of prior dominance. Together, these data demonstrate that instrumental control over stress promotes later dominance, but also reveal that winning experiences buffer against the neural and behavioral outcomes of future adversity.
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Affiliation(s)
| | | | - Heather N. Martin
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA
| | - Jose Amat
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA
| | - Matthew G. Frank
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA
| | - Rory J. Sanchez
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA
| | - Garrett J. Potter
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA
| | - Simone M. Mellert
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA
| | - Rene K. Carter
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA
| | - Gianni N. Bonnici
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA
| | - Steven F. Maier
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA
| | - Michael V. Baratta
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA
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Desmond LW, Holbrook EM, Wright CTO, Zambrano CA, Stamper CE, Bohr AD, Frank MG, Podell BK, Moreno JA, MacDonald AS, Reber SO, Hernández-Pando R, Lowry CA. Effects of Mycobacterium vaccae NCTC 11659 and Lipopolysaccharide Challenge on Polarization of Murine BV-2 Microglial Cells. Int J Mol Sci 2023; 25:474. [PMID: 38203645 PMCID: PMC10779110 DOI: 10.3390/ijms25010474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/15/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
Previous studies have shown that the in vivo administration of soil-derived bacteria with anti-inflammatory and immunoregulatory properties, such as Mycobacterium vaccae NCTC 11659, can prevent a stress-induced shift toward an inflammatory M1 microglial immunophenotype and microglial priming in the central nervous system (CNS). It remains unclear whether M. vaccae NCTC 11659 can act directly on microglia to mediate these effects. This study was designed to determine the effects of M. vaccae NCTC 11659 on the polarization of naïve BV-2 cells, a murine microglial cell line, and BV-2 cells subsequently challenged with lipopolysaccharide (LPS). Briefly, murine BV-2 cells were exposed to 100 µg/mL whole-cell, heat-killed M. vaccae NCTC 11659 or sterile borate-buffered saline (BBS) vehicle, followed, 24 h later, by exposure to 0.250 µg/mL LPS (Escherichia coli 0111: B4; n = 3) in cell culture media vehicle (CMV) or a CMV control condition. Twenty-four hours after the LPS or CMV challenge, cells were harvested to isolate total RNA. An analysis using the NanoString platform revealed that, by itself, M. vaccae NCTC 11659 had an "adjuvant-like" effect, while exposure to LPS increased the expression of mRNAs encoding proinflammatory cytokines, chemokine ligands, the C3 component of complement, and components of inflammasome signaling such as Nlrp3. Among LPS-challenged cells, M. vaccae NCTC 11659 had limited effects on differential gene expression using a threshold of 1.5-fold change. A subset of genes was assessed using real-time reverse transcription polymerase chain reaction (real-time RT-PCR), including Arg1, Ccl2, Il1b, Il6, Nlrp3, and Tnf. Based on the analysis using real-time RT-PCR, M. vaccae NCTC 11659 by itself again induced "adjuvant-like" effects, increasing the expression of Il1b, Il6, and Tnf while decreasing the expression of Arg1. LPS by itself increased the expression of Ccl2, Il1b, Il6, Nlrp3, and Tnf while decreasing the expression of Arg1. Among LPS-challenged cells, M. vaccae NCTC 11659 enhanced LPS-induced increases in the expression of Nlrp3 and Tnf, consistent with microglial priming. In contrast, among LPS-challenged cells, although M. vaccae NCTC 11659 did not fully prevent the effects of LPS relative to vehicle-treated control conditions, it increased Arg1 mRNA expression, suggesting that M. vaccae NCTC 11659 induces an atypical microglial phenotype. Thus, M. vaccae NCTC 11659 acutely (within 48 h) induced immune-activating and microglial-priming effects when applied directly to murine BV-2 microglial cells, in contrast to its long-term anti-inflammatory and immunoregulatory effects observed on the CNS when whole-cell, heat-killed preparations of M. vaccae NCTC 11659 were given peripherally in vivo.
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Affiliation(s)
- Luke W. Desmond
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (L.W.D.); (E.M.H.); (C.T.O.W.); (C.A.Z.); (C.E.S.); (A.D.B.); (M.G.F.)
| | - Evan M. Holbrook
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (L.W.D.); (E.M.H.); (C.T.O.W.); (C.A.Z.); (C.E.S.); (A.D.B.); (M.G.F.)
| | - Caelan T. O. Wright
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (L.W.D.); (E.M.H.); (C.T.O.W.); (C.A.Z.); (C.E.S.); (A.D.B.); (M.G.F.)
| | - Cristian A. Zambrano
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (L.W.D.); (E.M.H.); (C.T.O.W.); (C.A.Z.); (C.E.S.); (A.D.B.); (M.G.F.)
| | - Christopher E. Stamper
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (L.W.D.); (E.M.H.); (C.T.O.W.); (C.A.Z.); (C.E.S.); (A.D.B.); (M.G.F.)
| | - Adam D. Bohr
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (L.W.D.); (E.M.H.); (C.T.O.W.); (C.A.Z.); (C.E.S.); (A.D.B.); (M.G.F.)
| | - Matthew G. Frank
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (L.W.D.); (E.M.H.); (C.T.O.W.); (C.A.Z.); (C.E.S.); (A.D.B.); (M.G.F.)
- Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Brendan K. Podell
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO 80523, USA;
| | - Julie A. Moreno
- Prion Research Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA;
- Department of Environmental and Radiological Health Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
- Center for Healthy Aging, Colorado State University, Fort Collins, CO 80523, USA
| | - Andrew S. MacDonald
- Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester M13 9NT, UK;
| | - Stefan O. Reber
- Laboratory for Molecular Psychosomatics, Department of Psychosomatic Medicine and Psychotherapy, Ulm University Medical Center, 89081 Ulm, Germany;
| | - Rogelio Hernández-Pando
- Sección de Patología Experimental, Departamento de Patología, Instituto Nacional De Ciencias Médicas Y Nutrición Salvador Zubirán, Ciudad de México 14080, Mexico;
| | - Christopher A. Lowry
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (L.W.D.); (E.M.H.); (C.T.O.W.); (C.A.Z.); (C.E.S.); (A.D.B.); (M.G.F.)
- Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
- Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO 80309, USA
- Department of Physical Medicine and Rehabilitation and Center for Neuroscience, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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6
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Frank MG, Fleshner M, Maier SF. Exploring the immunogenic properties of SARS-CoV-2 structural proteins: PAMP:TLR signaling in the mediation of the neuroinflammatory and neurologic sequelae of COVID-19. Brain Behav Immun 2023; 111:259-269. [PMID: 37116592 PMCID: PMC10132835 DOI: 10.1016/j.bbi.2023.04.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/07/2023] [Accepted: 04/23/2023] [Indexed: 04/30/2023] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) produces an array of neurologic and neuropsychiatric symptoms in the acute and post-acute phase of infection (PASC; post-acute sequelae of SARS-CoV-2 infection). Neuroinflammatory processes are considered key factors in the etiology of these symptoms. Several mechanisms underpinning the development of inflammatory events in the brain have been proposed including SARS-CoV-2 neurotropism and peripheral inflammatory responses (i.e., cytokine storm) to infection, which might produce neuroinflammation via immune-to-brain signaling pathways. In this review, we explore evidence in support of an alternate mechanism whereby structural proteins (e.g., spike and spike S1 subunit) derived from SARS-CoV-2 virions function as pathogen-associated molecular patterns (PAMPs) to elicit proinflammatory immune responses in the periphery and/or brain via classical Toll-Like Receptor (TLR) inflammatory pathways. We propose that SARS-CoV-2 structural proteins might directly produce inflammatory processes in brain independent of and/or in addition to peripheral proinflammatory effects, which might converge to play a causal role in the development of neurologic/neuropsychiatric symptoms in COVID-19.
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Affiliation(s)
- Matthew G Frank
- Department of Integrative Physiology, University of Colorado Boulder, Boulder CO 80301, United States.
| | - Monika Fleshner
- Department of Integrative Physiology, University of Colorado Boulder, Boulder CO 80301, United States
| | - Steven F Maier
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder CO 80301, United States
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Coleman PT, Costanza-Chavez GW, Martin HN, Amat J, Frank MG, Sanchez RJ, Potter GJ, Mellert SM, Carter RK, Bonnici GN, Maier SF, Baratta MV. Prior experience with behavioral control over stress facilitates social dominance. bioRxiv 2023:2023.06.06.543982. [PMID: 37333397 PMCID: PMC10274770 DOI: 10.1101/2023.06.06.543982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Dominance status has extensive effects on physical and mental health, and an individual's relative position can be shaped by experiential factors. A variety of considerations suggest that the experience of behavioral control over stressors should produce winning in dominance tests and that winning should blunt the impact of later stressors, as does prior control. To investigate the interplay between competitive success and stressor control, we first examined the impact of stressor controllability on subsequent performance in a warm spot competition test modified for rats. Prior experience of controllable, but not physically identical uncontrollable, stress increased later effortful behavior and occupation of the warm spot. Controllable stress subjects consistently ranked higher than did uncontrollable stress subjects. Pharmacological inactivation of the prelimbic (PL) cortex during behavioral control prevented later facilitation of dominance. Next, we explored whether repeated winning experiences produced later resistance against the typical sequelae of uncontrollable stress. To establish dominance status, triads of rats were given five sessions of warm spot competition. Reversible inactivation of the PL or NMDA receptor blockade in the dorsomedial striatum led to a long-term reduction in social rank. Stable dominance blunted the later stress-induced increase in dorsal raphe nucleus serotonergic activity, as well as prevented stress-induced social avoidance. In contrast, endocrine and neuroimmune responses to uncontrollable stress were unaffected, indicating a selective impact of prior dominance. Together, these data demonstrate that instrumental control over stress promotes later dominance, but also reveal that winning experiences buffer against the neural and behavioral outcomes of future adversity.
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8
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Holbrook EM, Zambrano CA, Wright CTO, Dubé EM, Stewart JR, Sanders WJ, Frank MG, MacDonald AS, Reber SO, Lowry CA. Mycobacterium vaccae NCTC 11659, a Soil-Derived Bacterium with Stress Resilience Properties, Modulates the Proinflammatory Effects of LPS in Macrophages. Int J Mol Sci 2023; 24:ijms24065176. [PMID: 36982250 PMCID: PMC10049321 DOI: 10.3390/ijms24065176] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/15/2023] [Accepted: 02/20/2023] [Indexed: 03/10/2023] Open
Abstract
Inflammatory conditions, including allergic asthma and conditions in which chronic low-grade inflammation is a risk factor, such as stress-related psychiatric disorders, are prevalent and are a significant cause of disability worldwide. Novel approaches for the prevention and treatment of these disorders are needed. One approach is the use of immunoregulatory microorganisms, such as Mycobacterium vaccae NCTC 11659, which have anti-inflammatory, immunoregulatory, and stress-resilience properties. However, little is known about how M. vaccae NCTC 11659 affects specific immune cell targets, including monocytes, which can traffic to peripheral organs and the central nervous system and differentiate into monocyte-derived macrophages that, in turn, can drive inflammation and neuroinflammation. In this study, we investigated the effects of M. vaccae NCTC 11659 and subsequent lipopolysaccharide (LPS) challenge on gene expression in human monocyte-derived macrophages. THP-1 monocytes were differentiated into macrophages, exposed to M. vaccae NCTC 11659 (0, 10, 30, 100, 300 µg/mL), then, 24 h later, challenged with LPS (0, 0.5, 2.5, 250 ng/mL), and assessed for gene expression 24 h following challenge with LPS. Exposure to M. vaccae NCTC 11659 prior to challenge with higher concentrations of LPS (250 ng/mL) polarized human monocyte-derived macrophages with decreased IL12A, IL12B, and IL23A expression relative to IL10 and TGFB1 mRNA expression. These data identify human monocyte-derived macrophages as a direct target of M. vaccae NCTC 11659 and support the development of M. vaccae NCTC 11659 as a potential intervention to prevent stress-induced inflammation and neuroinflammation implicated in the etiology and pathophysiology of inflammatory conditions and stress-related psychiatric disorders.
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Affiliation(s)
- Evan M. Holbrook
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Cristian A. Zambrano
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Caelan T. O. Wright
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Elizabeth M. Dubé
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Jessica R. Stewart
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - William J. Sanders
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Matthew G. Frank
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Andrew S. MacDonald
- Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester M13 9NT, UK
| | - Stefan O. Reber
- Laboratory for Molecular Psychosomatics, Department of Psychosomatic Medicine and Psychotherapy, Ulm University Medical Center, 89081 Ulm, Germany
| | - Christopher A. Lowry
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
- Center for Neuroscience and Center for Microbial Exploration, University of Colorado, Boulder, CO 80309, USA
- Department of Physical Medicine and Rehabilitation and Center for Neuroscience, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Veterans Health Administration, Rocky Mountain Mental Illness Research Education and Clinical Center (MIRECC), The Rocky Mountain Regional Veterans Affairs Medical Center (RMRVAMC), Aurora, CO 80045, USA
- Military and Veteran Microbiome Consortium for Research and Education (MVM-CoRE), Aurora, CO 80045, USA
- Senior Fellow, inVIVO Planetary Health, of the Worldwide Universities Network (WUN), West New York, NJ 07093, USA
- Correspondence: ; Tel.: +1-303-492-6029; Fax: +1-303-492-0811
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9
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Frank MG, Nguyen KH, Ball JB, Hopkins S, Kelley T, Baratta MV, Fleshner M, Maier SF. SARS-CoV-2 spike S1 subunit induces neuroinflammatory, microglial and behavioral sickness responses: Evidence of PAMP-like properties. Brain Behav Immun 2022; 100:267-277. [PMID: 34915155 PMCID: PMC8667429 DOI: 10.1016/j.bbi.2021.12.007] [Citation(s) in RCA: 71] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 11/30/2021] [Accepted: 12/09/2021] [Indexed: 12/19/2022] Open
Abstract
SARS-CoV-2 infection produces neuroinflammation as well as neurological, cognitive (i.e., brain fog), and neuropsychiatric symptoms (e.g., depression, anxiety), which can persist for an extended period (6 months) after resolution of the infection. The neuroimmune mechanism(s) that produces SARS-CoV-2-induced neuroinflammation has not been characterized. Proposed mechanisms include peripheral cytokine signaling to the brain and/or direct viral infection of the CNS. Here, we explore the novel hypothesis that a structural protein (S1) derived from SARS-CoV-2 functions as a pathogen-associated molecular pattern (PAMP) to induce neuroinflammatory processes independent of viral infection. Prior evidence suggests that the S1 subunit of the SARS-CoV-2 spike protein is inflammatory in vitro and signals through the pattern recognition receptor TLR4. Therefore, we examined whether the S1 subunit is sufficient to drive 1) a behavioral sickness response, 2) a neuroinflammatory response, 3) direct activation of microglia in vitro, and 4) activation of transgenic human TLR2 and TLR4 HEK293 cells. Adult male Sprague-Dawley rats were injected intra-cisterna magna (ICM) with vehicle or S1. In-cage behavioral monitoring (8 h post-ICM) demonstrated that S1 reduced several behaviors, including total activity, self-grooming, and wall-rearing. S1 also increased social avoidance in the juvenile social exploration test (24 h post-ICM). S1 increased and/or modulated neuroimmune gene expression (Iba1, Cd11b, MhcIIα, Cd200r1, Gfap, Tlr2, Tlr4, Nlrp3, Il1b, Hmgb1) and protein levels (IFNγ, IL-1β, TNF, CXCL1, IL-2, IL-10), which varied across brain regions (hypothalamus, hippocampus, and frontal cortex) and time (24 h and 7d) post-S1 treatment. Direct exposure of microglia to S1 resulted in increased gene expression (Il1b, Il6, Tnf, Nlrp3) and protein levels (IL-1β, IL-6, TNF, CXCL1, IL-10). S1 also activated TLR2 and TLR4 receptor signaling in HEK293 transgenic cells. Taken together, these findings suggest that structural proteins derived from SARS-CoV-2 might function independently as PAMPs to induce neuroinflammatory processes via pattern recognition receptor engagement.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, United States.
| | - Kathy H Nguyen
- Department of Integrative Physiology, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, United States
| | - Jayson B Ball
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, United States
| | - Shelby Hopkins
- Department of Integrative Physiology, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, United States
| | - Tel Kelley
- Department of Integrative Physiology, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, United States
| | - Michael V Baratta
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, United States
| | - Monika Fleshner
- Department of Integrative Physiology, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, United States
| | - Steven F Maier
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, United States
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10
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Loupy KM, Cler KE, Marquart BM, Yifru TW, D'Angelo HM, Arnold MR, Elsayed AI, Gebert MJ, Fierer N, Fonken LK, Frank MG, Zambrano CA, Maier SF, Lowry CA. Comparing the effects of two different strains of mycobacteria, Mycobacterium vaccae NCTC 11659 and M. vaccae ATCC 15483, on stress-resilient behaviors and lipid-immune signaling in rats. Brain Behav Immun 2021; 91:212-229. [PMID: 33011306 PMCID: PMC7749860 DOI: 10.1016/j.bbi.2020.09.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/17/2020] [Accepted: 09/26/2020] [Indexed: 12/11/2022] Open
Abstract
Stress-related disorders, such as posttraumatic stress disorder (PTSD), are highly prevalent and often difficult to treat. In rodents, stress-related, anxiety-like defensive behavioral responses may be characterized by social avoidance, exacerbated inflammation, and altered metabolic states. We have previously shown that, in rodents, subcutaneous injections of a heat-killed preparation of the soil-derived bacterium Mycobacterium vaccae NCTC 11659 promotes stress resilience effects that are associated with immunoregulatory signaling in the periphery and the brain. In the current study, we sought to determine whether treatment with a heat-killed preparation of the closely related M. vaccae type strain, M. vaccae ATCC 15483, would also promote stress-resilience in adult male rats, likely due to biologically similar characteristics of the two strains. Here we show that immunization with either M. vaccae NCTC 11659 or M. vaccae ATCC 15483 prevents stress-induced increases in hippocampal interleukin 6 mRNA expression, consistent with previous studies showing that M. vaccae NCTC 11659 prevents stress-induced increases in peripheral IL-6 secretion, and prevents exaggeration of anxiety-like defensive behavioral responses assessed 24 h after exposure to inescapable tail shock stress (IS) in adult male rats. Analysis of mRNA expression, protein abundance, and flow cytometry data demonstrate overlapping but also unique effects of treatment with the two M. vaccae strains on immunological and metabolic signaling in the host. These data support the hypothesis that treatment with different M. vaccae strains may immunize the host against stress-induced dysregulation of physiology and behavior.
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Affiliation(s)
- Kelsey M Loupy
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Kristin E Cler
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Brandon M Marquart
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Tumim W Yifru
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Heather M D'Angelo
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Mathew R Arnold
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Ahmed I Elsayed
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Matthew J Gebert
- Department of Ecology and Evolutionary Biology, Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder, CO 80309, USA; Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Noah Fierer
- Department of Ecology and Evolutionary Biology, Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder, CO 80309, USA; Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Laura K Fonken
- Division of Pharmacology and Toxicology, University of Texas at Austin, Austin, TX 78712, USA
| | - Matthew G Frank
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Cristian A Zambrano
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Steven F Maier
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Christopher A Lowry
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO 80309, USA; Department of Physical Medicine and Rehabilitation and Center for Neuroscience, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Veterans Health Administration, Rocky Mountain Mental Illness Research Education and Clinical Center (MIRECC), Rocky Mountain Regional Veterans Affairs Medical Center (RMRVAMC), Aurora, CO 80045, USA; Military and Veteran Microbiome: Consortium for Research and Education (MVM-CoRE), Aurora, CO 80045, USA; inVIVO Planetary Health, of the Worldwide Universities Network (WUN), West New York, NJ 07093, USA.
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11
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Frank MG, Baratta MV, Zhang K, Fallon IP, Pearson MA, Liu G, Hutchinson MR, Watkins LR, Goldys EM, Maier SF. Acute stress induces the rapid and transient induction of caspase-1, gasdermin D and release of constitutive IL-1β protein in dorsal hippocampus. Brain Behav Immun 2020; 90:70-80. [PMID: 32750541 PMCID: PMC7544655 DOI: 10.1016/j.bbi.2020.07.042] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/27/2020] [Accepted: 07/28/2020] [Indexed: 01/31/2023] Open
Abstract
The proinflammatory cytokine interleukin (IL)-1β plays a pivotal role in the behavioral manifestations (i.e., sickness) of the stress response. Indeed, exposure to acute and chronic stressors induces the expression of IL-1β in stress-sensitive brain regions. Thus, it is typically presumed that exposure to stressors induces the extra-cellular release of IL-1β in the brain parenchyma. However, this stress-evoked neuroimmune phenomenon has not been directly demonstrated nor has the cellular process of IL-1β release into the extracellular milieu been characterized in brain. This cellular process involves a form of inflammatory cell death, termed pyroptosis, which involves: 1) activation of caspase-1, 2) caspase-1 maturation of IL-1β, 3) caspase-1 cleavage of gasdermin D (GSDMD), and 4) GSDMD-induced permeability of the cell membrane through which IL-1β is released into the extracellular space. Thus, the present study examined whether stress induces the extra-cellular release of IL-1β and engages the above cellular process in mediating IL-1β release in the brain. Male Sprague-Dawley rats were exposed to inescapable tailshock (IS). IL-1β extra-cellular release, caspase-1 activity and cleavage of GSDMD were measured in dorsal hippocampus. We found that exposure to IS induced a transient increase in the release of IL-1β into the extracellular space immediately after termination of the stressor. IS also induced a transient increase in caspase-1 activity prior to IL-1β release, while activation of GSDMD was observed immediately after termination of the stressor. IS also increased mRNA and protein expression of the ESCRTIII protein CHMP4B, which is involved in cellular repair. The present results suggest that exposure to an acute stressor induces the hallmarks of pyroptosis in brain, which might serve as a key cellular process involved in the release of IL-1β into the extracellular milieu of the brain parenchyma.
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Affiliation(s)
- Matthew G. Frank
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO;,Corresponding Author: Department of Psychology and Neuroscience, Center for Neuroscience, Campus Box 603, University of Colorado Boulder, Boulder, CO, 80301, USA, Tel: +1-303-919-8116,
| | - Michael V. Baratta
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO
| | - Kaixin Zhang
- ARC Centre of Excellence in Nanoscale Biophotonics (CNBP), Macquarie University, North Ryde, Australia;,Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, Australia
| | - Isabella P. Fallon
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO
| | - Mikayleigh A. Pearson
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO
| | - Guozhen Liu
- Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, Australia;,International Joint Research Center for Intelligent Biosensor Technology and Health, Central China Normal University, Wuhan, China
| | - Mark R. Hutchinson
- Adelaide Medical School & ARC Centre of Excellence in Nanoscale Biophotonics (CNBP), The University of Adelaide, Adelaide, Australia
| | - Linda R. Watkins
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO
| | - Ewa M. Goldys
- Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, Australia
| | - Steven F. Maier
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO
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12
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Loupy KM, Lee T, Zambrano CA, Elsayed AI, D'Angelo HM, Fonken LK, Frank MG, Maier SF, Lowry CA. Alzheimer's Disease: Protective Effects of Mycobacterium vaccae, a Soil-Derived Mycobacterium with Anti-Inflammatory and Anti-Tubercular Properties, on the Proteomic Profiles of Plasma and Cerebrospinal Fluid in Rats. J Alzheimers Dis 2020; 78:965-987. [PMID: 33074227 DOI: 10.3233/jad-200568] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Alzheimer's disease (AD) is an inflammatory neurodegenerative disease that may be associated with prior bacterial infections. Microbial "old friends" can suppress exaggerated inflammation in response to disease-causing infections or increase clearance of pathogens such as Mycobacterium tuberculosis, which causes tuberculosis (TB). One such "old friend" is Mycobacterium vaccae NCTC 11659, a soil-derived bacterium that has been proposed either as a vaccine for prevention of TB, or as immunotherapy for the treatment of TB when used alongside first line anti-TB drug treatment. OBJECTIVE The goal of this study was to use a hypothesis generating approach to explore the effects of M. vaccae on physiological changes in the plasma and cerebrospinal fluid (CSF). METHODS Liquid chromatography-tandem mass spectrometry-based proteomics were performed in plasma and CSF of adult male rats after immunization with a heat-killed preparation of M. vaccae NCTC 11659 or borate-buffered saline vehicle. Gene enrichment analysis and analysis of protein-protein interactions were performed to integrate physiological network changes in plasma and CSF. We used RT-qPCR to assess immune and metabolic gene expression changes in the hippocampus. RESULTS In both plasma and CSF, immunization with M. vaccae increased proteins associated with immune activation and downregulated proteins corresponding to lipid (including phospholipid and cholesterol) metabolism. Immunization with M. vaccae also increased hippocampal expression of interleukin-4 (IL-4) mRNA, implicating anti-inflammatory effects in the central nervous system. CONCLUSION M. vaccae alters host immune activity and lipid metabolism. These data are consistent with the hypothesis that microbe-host interactions may protect against possible infection-induced, inflammation-related cognitive impairments.
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Affiliation(s)
- Kelsey M Loupy
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA
| | - Thomas Lee
- Central Analytical Laboratory and Mass Spectrometry Facility, Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Cristian A Zambrano
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA
| | - Ahmed I Elsayed
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA
| | - Heather M D'Angelo
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - Laura K Fonken
- Division of Pharmacology and Toxicology, University of Texas at Austin, Austin, TX, USA
| | - Matthew G Frank
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, USA.,Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - Steven F Maier
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, USA.,Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - Christopher A Lowry
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO, USA.,Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA.,Center for Microbial Exploration, University of Colorado Boulder, Boulder, CO, USA.,Department of Physical Medicine and Rehabilitation and Center for Neuroscience, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.,Veterans Health Administration, Rocky Mountain Mental Illness Research Education and Clinical Center (MIRECC), Rocky Mountain Regional Veterans Affairs Medical Center (RMRVAMC), Aurora, CO, USA.,Military and Veteran Microbiome: Consortium for Research and Education (MVM-CoRE), Aurora, CO, USA.,Senior Fellow, inVIVO Planetary Health, of the Worldwide Universities Network (WUN), West New York, NJ, USA
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13
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Frank MG, Fonken LK, Watkins LR, Maier SF. Acute stress induces chronic neuroinflammatory, microglial and behavioral priming: A role for potentiated NLRP3 inflammasome activation. Brain Behav Immun 2020; 89:32-42. [PMID: 32485293 PMCID: PMC7572608 DOI: 10.1016/j.bbi.2020.05.063] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 05/21/2020] [Accepted: 05/24/2020] [Indexed: 12/11/2022] Open
Abstract
Prior exposure to acute and chronic stressors potentiates the neuroinflammatory and microglial pro-inflammatory response to subsequent immune challenges suggesting that stressors sensitize or prime microglia. Stress-induced priming of the NLRP3 inflammasome has been implicated in this priming phenomenon, however the duration/persistence of these effects has not been investigated. In the present study, we examined whether exposure to a single acute stressor (inescapable tailshock) induced a protracted priming of the NLRP3 inflammasome as well as the neuroinflammatory, behavioral and microglial proinflammatory response to a subsequent immune challenge in hippocampus. In male Sprague-Dawley rats, acute stress potentiated the neuroinflammatory response (IL-1β, IL-6, and NFκBIα) to an immune challenge (lipopolysaccharide; LPS) administered 8 days after stressor exposure. Acute stress also potentiated the proinflammatory cytokine response (IL-1β, IL-6, TNF and NFκBIα) to LPS ex vivo. This stress-induced priming of microglia also was observed 28 days post-stress. Furthermore, challenge with LPS reduced juvenile social exploration, but not sucrose preference, in animals exposed to stress 8 days prior to immune challenge. Exposure to acute stress also increased basal mRNA levels of NLRP3 and potentiated LPS-induction of caspase-1 mRNA and protein activity 8 days after stress. The present findings suggest that acute stress produces a protracted vulnerability to the neuroinflammatory effects of subsequent immune challenges, thereby increasing risk for stress-related psychiatric disorders with an etiological inflammatory component. Further, these findings suggest the unique possibility that acute stress might induce innate immune memory in microglia.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, USA.
| | - Laura K Fonken
- Division of Pharmacology and Toxicology, University of Texas at Austin, Austin, TX 78712, USA
| | - Linda R Watkins
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, USA
| | - Steven F Maier
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, USA
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14
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Frank MG, Annis JL, Watkins LR, Maier SF. Glucocorticoids mediate stress induction of the alarmin HMGB1 and reduction of the microglia checkpoint receptor CD200R1 in limbic brain structures. Brain Behav Immun 2019; 80:678-687. [PMID: 31078691 PMCID: PMC6662571 DOI: 10.1016/j.bbi.2019.05.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/29/2019] [Accepted: 05/08/2019] [Indexed: 02/02/2023] Open
Abstract
Exposure to stressors primes neuroinflammatory responses to subsequent immune challenges and stress-induced glucocorticoids (GCs) play a mediating role in this phenomenon of neuroinflammatory priming. Recent evidence also suggests that the alarmin high-mobility group box-1 (HMGB1) and the microglial checkpoint receptor CD200R1 serve as proximal mechanisms of stress-induced neuroinflammatory priming. However, it is unclear whether stress-induced GCs play a causal role in these proximal mechanisms of neuroinflammatory priming; this forms the focus of the present investigation. Here, we found that exposure to a severe acute stressor (inescapable tailshock) induced HMGB1 and reduced CD200R1 expression in limbic brain regions and pharmacological blockade of GC signaling (RU486) mitigated these effects of stress. To confirm these effects of RU486, adrenalectomy (ADX) with basal corticosterone (CORT) replacement was used to block the stress-induced increase in GCs as well as effects on HMGB1 and CD200R1. As with RU486, ADX mitigated the effects of stress on HMGB1 and CD200R1. Subsequently, exogenous CORT was administered to determine whether GCs are sufficient to recapitulate the effects of stress. Indeed, exogenous CORT induced expression of HMGB1 and reduced expression of CD200R1. In addition, exposure of primary microglia to CORT also recapitulated the effects of stress on CD200R1 suggesting that CORT acts directly on microglia to reduce expression of CD200R1. Taken together, these findings suggest that GCs mediate the effects of stress on these proximal mechanisms of neuroinflammatory priming.
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Affiliation(s)
- Matthew G. Frank
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80301, USA,Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, USA,Corresponding Author: Department of Psychology and Neuroscience, Center for Neuroscience, 2860 Wilderness Place, Campus Box 603, University of Colorado Boulder, Boulder, CO 80301, USA, Tel: +1-303-919-8116,
| | - Jessica L. Annis
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, 22908
| | - Linda R. Watkins
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80301, USA,Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, USA
| | - Steven F. Maier
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80301, USA,Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80301, USA
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15
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Abstract
Neuroinflammatory processes promote a constellation of neurochemical and hormonal changes resulting in profound effects on motivational states (anhedonia), mood (depression and anxiety disorders), and cognitive function (decrements in learning and memory). The enhancement of immunoregulatory processes, such as increasing anti-inflammatory cytokines in the CNS, is a highly effective strategy for curtailing neuroinflammation. Here, we explore recent evidence that probiotic treatment approaches might be an effective strategy to induce long-lasting immunoregulation in the CNS and thus mitigate the neural and behavioral effects of neuroinflammation.
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Affiliation(s)
- Matthew G. Frank
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Center for Neuroscience, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Laura K. Fonken
- Division of Pharmacology and Toxicology, University of Texas at Austin, Austin, Texas 78712, United States
| | - Linda R. Watkins
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Center for Neuroscience, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Steven F. Maier
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Center for Neuroscience, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Christopher A. Lowry
- Center for Neuroscience, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Department of Physical Medicine & Rehabilitation, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, United States
- Center for Neuroscience, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, United States
- Veterans Health Administration Rocky Mountain Mental Illness Research Education and Clinical Center (MIRECC), Denver Veterans Affairs Medical Center (VAMC), Denver, Colorado 80220, United States
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16
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Frank MG, Fonken LK, Watkins LR, Maier SF. Microglia: Neuroimmune-sensors of stress. Semin Cell Dev Biol 2019; 94:176-185. [PMID: 30638704 DOI: 10.1016/j.semcdb.2019.01.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 12/29/2018] [Accepted: 01/04/2019] [Indexed: 02/07/2023]
Abstract
Exposure to stressors disrupts homeostasis and results in the release of stress hormones including glucocorticoids, epinepherine and norepinepherine. Interestingly, stress also has profound affects on microglia, which are tissue-resident macrophages in the brain parenchyma. Microglia express a diverse array of receptors, which also allows them to respond to stress hormones derived from peripheral as well as central sources. Here, we review studies of how exposure to acute and chronic stressors alters the immunophenotype and function of microglia. Further, we examine a causal for stress hormones in these effects of stress on microglia. We propose that microglia serve as immunosensors of the stress response, which puts them in the unique position to sense and respond rapidly to alterations in homeostasis and integrate the neural response to threats.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA.
| | - Laura K Fonken
- Division of Pharmacology and Toxicology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Linda R Watkins
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - Steven F Maier
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO, 80309, USA
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17
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Frank MG, Fonken LK, Dolzani SD, Annis JL, Siebler PH, Schmidt D, Watkins LR, Maier SF, Lowry CA. Immunization with Mycobacterium vaccae induces an anti-inflammatory milieu in the CNS: Attenuation of stress-induced microglial priming, alarmins and anxiety-like behavior. Brain Behav Immun 2018; 73:352-363. [PMID: 29807129 PMCID: PMC6129419 DOI: 10.1016/j.bbi.2018.05.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 05/17/2018] [Accepted: 05/24/2018] [Indexed: 12/12/2022] Open
Abstract
Exposure to stressors induces anxiety- and depressive-like behaviors, which are mediated, in part, by neuroinflammatory processes. Recent findings demonstrate that treatment with the immunoregulatory and anti-inflammatory bacterium, Mycobacterium vaccae (M. vaccae), attenuates stress-induced exaggeration of peripheral inflammation and stress-induced anxiety-like behavioral responses. However, the effects of M. vaccae on neuroimmune processes have largely been unexplored. In the present study, we examined the effect of M. vaccae NCTC11659 on neuroimmune regulation, stress-induced neuroinflammatory processes and anxiety-like behavior. Adult male rats were immunized 3× with a heat-killed preparation of M. vaccae (0.1 mg, s.c.) or vehicle. M. vaccae induced an anti-inflammatory immunophenotype in hippocampus (increased interleukin (Il)4, Cd200r1, and Mrc1 mRNA expression) and increased IL4 protein 8 d after the last immunization. Central administration of recombinant IL4 recapitulated the effects of M. vaccae on Cd200r1 and Mrc1 mRNA expression. M. vaccae reduced basal levels of genes (Nlrp3 and Nfkbia) involved in microglial priming; thus, we explored the effects of M. vaccae on stress-induced hippocampal microglial priming and HMGB1, which mediates priming. We found that M. vaccae blocked stress-induced decreases in Cd200r1, increases in the alarmin HMGB1, and priming of the microglial response to immune challenge. Furthermore, M. vaccae prevented stress-induced increases in anxiety-like behavior. The present findings suggest that M. vaccae enhances immunomodulation in the CNS and mitigates the neuroinflammatory and behavioral effects of stress, which may underpin its capacity to impart a stress resilient phenotype.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA.
| | - Laura K Fonken
- Division of Pharmacology and Toxicology, University of Texas at Austin, Austin, TX 78712, USA
| | - Samuel D Dolzani
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Jessica L Annis
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Philip H Siebler
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Dominic Schmidt
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Linda R Watkins
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Steven F Maier
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA; Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Christopher A Lowry
- Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA; Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; Department of Physical Medicine & Rehabilitation, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Center for Neuroscience, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA; Rocky Mountain Mental Illness Research Education and Clinical Center (MIRECC), Denver Veterans Affairs Medical Center (VAMC), Denver, CO 80220, USA; Military and Veteran Microbiome Consortium for Research and Education (MVM-CoRE), Denver, CO 80220, USA
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18
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Fonken LK, Frank MG, Gaudet AD, Maier SF. Stress and aging act through common mechanisms to elicit neuroinflammatory priming. Brain Behav Immun 2018; 73:133-148. [PMID: 30009999 PMCID: PMC6129421 DOI: 10.1016/j.bbi.2018.07.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 07/09/2018] [Accepted: 07/12/2018] [Indexed: 01/05/2023] Open
Abstract
Over the course of an animal's lifespan, there is a protracted breakdown in basic homeostatic functions. Stressors (both psychological and physiological) can accelerate this process and compromise multiple homeostatic mechanisms. For example, both stress and aging can modulate neuroinflammatory function and cause a primed phenotype resulting in a heightened neuroinflammatory profile upon immune activation. Microglia, the brain's resident myeloid cell, produce "silent" immune machinery in response to stress and aging that does not cause immediate immune activation; rather, these changes prime the cell for a subsequent immune insult. Primed microglia exhibit a hyperinflammatory response upon immune activation that can exacerbate pathology. In this review, we will explore parallels between stress- and aging-induced neuroinflammatory priming. First, we will provide a background on the basic principles of neuroimmunology. Next, we will discuss evidence that neuroinflammatory responses become primed in the context of both stress and aging. We will also describe cell-specific contributions to neuroinflammatory priming with a focus on microglia. Finally, common mechanisms underlying priming in the context of stress and aging will be discussed: these mechanisms include glucocorticoid signaling; accumulation of danger signals; dis-inhibition of microglia; and breakdown of circadian rhythms. Overall, there are multifarious parallels between stress- and aging-elicited neuroinflammatory priming, suggesting that stress may promote a form of premature aging. Further unravelling mechanisms underlying priming could lead to improved treatments for buffering against stress- and aging-elicited behavioral pathologies.
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Affiliation(s)
- Laura K. Fonken
- University of Texas at Austin, Division of Pharmacology and Toxicology, Austin, TX 78712 USA;,To whom correspondence should be addressed: Laura K. Fonken, Division of Pharmacology and Toxicology, University of Texas at Austin, 107 W. Dean Keeton, BME 3.510C, Austin, TX 78712 USA.
| | - Matthew G. Frank
- University of Colorado Boulder, Department of Psychology and Neuroscience, Boulder, CO 80309 USA
| | - Andrew D. Gaudet
- University of Colorado Boulder, Department of Psychology and Neuroscience, Boulder, CO 80309 USA
| | - Steven F. Maier
- University of Colorado Boulder, Department of Psychology and Neuroscience, Boulder, CO 80309 USA
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Zhang K, Baratta MV, Liu G, Frank MG, Leslie NR, Watkins LR, Maier SF, Hutchinson MR, Goldys EM. A novel platform for in vivo detection of cytokine release within discrete brain regions. Brain Behav Immun 2018; 71:18-22. [PMID: 29678795 DOI: 10.1016/j.bbi.2018.04.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/02/2018] [Accepted: 04/16/2018] [Indexed: 12/20/2022] Open
Abstract
Mounting evidence indicates that cytokines secreted by innate immune cells in the brain play a central role in regulating neural circuits that subserve mood, cognition, and sickness responses. A major impediment to the study of neuroimmune signaling in healthy and disease states is the absence of tools for in vivo detection of cytokine release in the brain. Here we describe the design and application of a cytokine detection device capable of serial monitoring of local cytokine release in discrete brain regions. The immunocapture device consisted of a modified optical fiber labeled with a capture antibody specific for the pro-inflammatory cytokine interleukin-1 beta (IL-1β). Using a sandwich immunoassay method, in vitro data demonstrate that the sensing interface of the modified optical fiber has a linear detection range of 3.9 pg mL-1-500 pg mL-1 and spatial resolution on the order of 200-450 μm. Finally, we show that the immunocapture device can be introduced into a perforated guide cannula for repeated analyte measurements in vivo. An increase in fluorescence detection of spatially localized intrahippocampal IL-1β release was observed following a peripheral lipopolysaccharide challenge in Sprague-Dawley rats. This novel immunosensing technology represents an opportunity for unlocking the function of neuroimmune signaling.
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Affiliation(s)
- Kaixin Zhang
- ARC Centre of Excellence in Nanoscale Biophotonics (CNBP), Macquarie University, Sydney, Australia.
| | - Michael V Baratta
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, USA.
| | - Guozhen Liu
- ARC Centre of Excellence in Nanoscale Biophotonics (CNBP), Macquarie University, Sydney, Australia; Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, Australia; International Joint Research Center for Intelligent Biosensor Technology and Health, Central China Normal University, Wuhan, China.
| | - Matthew G Frank
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, USA.
| | - Nathan R Leslie
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, USA.
| | - Linda R Watkins
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, USA.
| | - Steven F Maier
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, USA.
| | - Mark R Hutchinson
- ARC Centre of Excellence in Nanoscale Biophotonics (CNBP), The University of Adelaide, Adelaide, Australia.
| | - Ewa M Goldys
- ARC Centre of Excellence in Nanoscale Biophotonics (CNBP), Macquarie University, Sydney, Australia; Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, Australia.
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Schindler SM, Frank MG, Annis JL, Maier SF, Klegeris A. Pattern recognition receptors mediate pro-inflammatory effects of extracellular mitochondrial transcription factor A (TFAM). Mol Cell Neurosci 2018; 89:71-79. [DOI: 10.1016/j.mcn.2018.04.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 04/09/2018] [Accepted: 04/13/2018] [Indexed: 12/11/2022] Open
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Fonken LK, Frank MG, Gaudet AD, D’Angelo HM, Daut RA, Hampson EC, Ayala MT, Watkins LR, Maier SF. Neuroinflammatory priming to stress is differentially regulated in male and female rats. Brain Behav Immun 2018; 70. [PMID: 29524458 PMCID: PMC5953809 DOI: 10.1016/j.bbi.2018.03.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Exposure to stressors can enhance neuroinflammatory responses, and both stress and neuroinflammation are predisposing factors in the development of psychiatric disorders. Females suffer disproportionately more from several psychiatric disorders, yet stress-induced changes in neuroinflammation have primarily been studied in males. Here we tested whether exposure to inescapable tail shock sensitizes or 'primes' neuroinflammatory responses in male and female rats. At 24 h post-stress, male and female rats exposed to a peripheral immune challenge enhanced neuroinflammatory responses and exacerbated anxiety- and depressive-like behaviors. These changes are likely glucocorticoid dependent, as administering exogenous CORT, caused a similar primed inflammatory response in the hippocampus of male and female rats. Further, stress disinhibited anti-inflammatory signaling mechanisms (such as CD200R) in the hippocampus of male and female rats. In males, microglia are considered the likely cellular source mediating neuroinflammatory priming; stress increased cytokine expression in ex vivo male microglia. Conversely, microglia isolated from stressed or CORT treated females did not exhibit elevated cytokine responses. Microglia isolated from both stressed male and female rats reduced phagocytic activity; however, suggesting that microglia from both sexes experience stress-induced functional impairments. Finally, an immune challenge following either stress or CORT in females, but not males, increased peripheral inflammation (serum IL-1β). These novel data suggest that although males and females both enhance stress-induced neuroinflammatory and behavioral responses to an immune challenge, this priming may occur through distinct, sex-specific mechanisms.
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Affiliation(s)
- Laura K. Fonken
- Corresponding author: Laura K. Fonken, Division of Pharmacology and Toxicology, University of Texas, Austin, TX 78712; (512) 232-8331;
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Frank MG, Fonken LK, Annis JL, Watkins LR, Maier SF. Stress disinhibits microglia via down-regulation of CD200R: A mechanism of neuroinflammatory priming. Brain Behav Immun 2018; 69:62-73. [PMID: 29104062 PMCID: PMC5857401 DOI: 10.1016/j.bbi.2017.11.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 10/20/2017] [Accepted: 11/01/2017] [Indexed: 12/22/2022] Open
Abstract
Exposure to stressors primes the neuroinflammatory and microglial proinflammatory response to subsequent immune challenges, suggesting that stress might attenuate immunoregulatory mechanisms in the CNS microenvironment. CD200:CD200R is a key immunoregulatory signaling dyad that constrains microglial activation, and disruption of CD200:CD200R signaling primes microglia to subsequent immune challenges. Therefore, the present study examined the mediating role of CD200:CD200R signaling in stress-induced microglial priming. Here, we found that exposure to an acute stressor reduced CD200R expression across sub-regions of the hippocampus, amygdala as well as in isolated hippocampal microglia. A transcriptional suppressor of CD200R, CAAT/Enhancer Binding Proteinβ, was induced by stress and inversely associated with CD200R expression. To examine whether disrupted CD200:CD200R signaling plays a mediating role in stress-induced microglial priming, a soluble fragment of CD200 (mCD200Fc) was administered intra-cisterna magna prior to stressor exposure and stress-induced microglia priming assessed ex vivo 24 h later. Treatment with mCD200Fc blocked the stress-induced priming of the microglial pro-inflammatory response. Further, treatment with mCD200R1Fc recapitulated the effects of stress on microglial priming. We previously found that stress increases the alarmin high mobility group box-1 (HMGB1) in hippocampus, and that HMGB1 mediates stress-induced priming of microglia. Thus, we examined whether stress-induced increases in hippocampal HMGB1 are a consequence of disrupted CD200:CD200R signaling. Indeed, treatment with mCD200Fc prior to stress exposure blocked the stress-induced increase in hippocampal HMGB1. The present study suggests that stress exposure disrupts immunoregulatory mechanisms in the brain, which typically constrain the immune response of CNS innate immune cells. This attenuation of immunoregulatory mechanisms may thus permit a primed activation state of microglia to manifest.
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Affiliation(s)
- Matthew G. Frank
- Corresponding Author: Department of Psychology and Neuroscience, Center for Neuroscience, Campus Box 345, University of Colorado Boulder, Boulder, CO, 80309-0345, USA, Tel: +1-303-919-8116, Fax: +1-303-492-2967,
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Frank MG, Weber MD, Fonken LK, Hershman SA, Watkins LR, Maier SF. The redox state of the alarmin HMGB1 is a pivotal factor in neuroinflammatory and microglial priming: A role for the NLRP3 inflammasome. Brain Behav Immun 2016; 55:215-224. [PMID: 26482581 PMCID: PMC4837097 DOI: 10.1016/j.bbi.2015.10.009] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 10/02/2015] [Accepted: 10/15/2015] [Indexed: 01/05/2023] Open
Abstract
The alarmin high mobility group box-1 (HMGB1) has been implicated as a key factor mediating neuroinflammatory processes. Recent findings suggest that the redox state of HMGB1 is a critical molecular feature of HMGB1 such that the reduced form (fr-HMGB1) is chemotactic, while the disulfide form (ds-HMGB1) is pro-inflammatory. The present study examined the neuroinflammatory effects of these molecular forms as well as the ability of these forms to prime the neuroinflammatory and microglial response to an immune challenge. To examine the neuroinflammatory effects of these molecular forms in vivo, animals were administered intra-cisterna magna (ICM) a single dose of fr-HMGB1 (10μg), ds-HMGB1 (10μg) or vehicle and basal pro-inflammatory effects were measured 2 and 24h post-injection in hippocampus. Results of this initial experiment demonstrated that ds-HMGB1 increased hippocampal pro-inflammatory mediators at 2h (NF-κBIα mRNA, NLRP3 mRNA and IL-1β protein) and 24h (NF-κBIα mRNA, TNFα mRNA, and NLRP3 protein) after injection. fr-HMGB1 had no effect on these mediators. These neuroinflammatory effects of ds-HMGB1 suggested that ds-HMGB1 may function to prime the neuroinflammatory response to a subsequent immune challenge. To assess the neuroinflammatory priming effects of these molecular forms, animals were administered ICM a single dose of fr-HMGB1 (10μg), ds-HMGB1 (10μg) or vehicle and 24h after injection, animals were challenged with LPS (10μg/kg IP) or vehicle. Neuroinflammatory mediators and the sickness response (3, 8 and 24h after injection) were measured 2h after immune challenge. We found that ds-HMGB1 potentiated the neuroinflammatory (NF-κBIα mRNA, TNFα mRNA, IL-1β mRNA, IL-6 mRNA, NLRP3 mRNA and IL-1β protein) and sickness response (reduced social exploration) to LPS challenge. fr-HMGB1 failed to potentiate the neuroinflammatory response to LPS. To examine whether these molecular forms of HMGB1 directly induce neuroinflammatory effects in isolated microglia, whole brain microglia were isolated and treated with fr-HMGB1 (0, 1, 10, 100, or 1000ng/ml) or ds-HMGB1 (0, 1, 10, 100, or 1000ng/ml) for 4h and pro-inflammatory mediators measured. To assess the effects of these molecular forms on microglia priming, whole brain microglia were pre-exposed to these forms of HMGB1 (0, 1, 10, 100, or 1000ng/ml) and subsequently challenged with LPS (10ng/ml). We found that ds-HMGB1 increased expression of NF-κBIα mRNA and NLRP3 mRNA in isolated microglia, and potentiated the microglial pro-inflammatory response (TNFα mRNA, IL-1β mRNA and IL-1β protein) to LPS. fr-HMGB1 failed to potentiate the microglial pro-inflammatory response to LPS. Consistent with prior reports, the present findings demonstrate that the disulfide form of HMGB1 not only potentiates the neuroinflammatory response to a subsequent immune challenge in vivo, but also potentiates the sickness response to that challenge. Moreover, the present findings demonstrate for the first time that ds-HMGB1 directly potentiates the microglia pro-inflammatory response to an immune challenge, a finding that parallels the effects of ds-HMGB1 in vivo. In addition, ds-HMGB1 induced expression of NLRP3 and NF-κBIα in vivo and in vitro suggesting that the NLRP3 inflammasome may play role in the priming effects of ds-HMGB1. Taken together, the present results suggest that the redox state of HMGB1 is a critical determinant of the priming properties of HMGB1 such that the disulfide form of HMGB1 induces a primed immunophenotype in the CNS, which may result in an exacerbated neuroinflammatory response upon exposure to a subsequent pro-inflammatory stimulus.
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Affiliation(s)
- Matthew G. Frank
- Corresponding Author: Department of Psychology and Neuroscience, Center for Neuroscience, Campus Box 345, University of Colorado Boulder Boulder, CO, 80309-0345, USA, Tel: +1-303-919-8116, Fax: +1-303-492-2967,
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Fonken LK, Weber MD, Daut RA, Kitt MM, Frank MG, Watkins LR, Maier SF. Stress-induced neuroinflammatory priming is time of day dependent. Psychoneuroendocrinology 2016; 66:82-90. [PMID: 26799851 PMCID: PMC4788538 DOI: 10.1016/j.psyneuen.2016.01.006] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 01/05/2016] [Accepted: 01/06/2016] [Indexed: 10/22/2022]
Abstract
Circadian rhythms are endogenous cycles of physiology and behavior that align with the daily rotation of the planet and resulting light-dark cycle. The circadian system ensures homeostatic balance and regulates many aspects of physiology, including the stress response and susceptibility to and/or severity of stress-related sequelae. Both acute and chronic stressors amplify neuroinflammatory responses to a subsequent immune challenge, however it is not known whether circadian timing of the stressor regulates the priming response. Here, we test whether stress-induced neuroinflammatory priming is regulated by the circadian system. As has been previously shown, exposure to 100 inescapable tails shocks (IS) increased hippocampal cytokines following a subsequent inflammatory challenge. However, this effect was limited to animals that experienced the stressor during the light phase. Rats exposed to stress during the dark phase did not alter inflammatory potential following lipopolysaccharide (LPS) challenge. To determine whether microglia might be involved in diurnal differences in neuroinflammatory priming, microglia were isolated 24h after stress that occurred either during the middle of the light or dark phase. Only microglia isolated from animals stressed during the light phase demonstrated an exaggerated inflammatory response when treated ex vivo with LPS. To determine possible circadian dependency of microglia responsiveness to glucocorticoids - the likely proximal mediator for stress associated neuroinflammatory priming - microglia were isolated during the middle of the light or dark phase and treated ex vivo with corticosterone. Glucocorticoids treatment downregulated CX3CR1 and CD200R, two genes involved in microglial inflammatory "off" signaling; however, there was no effect of time of day on expression of either gene. Importantly, while absolute concentrations of corticosterone were comparable following IS during the light and dark phase, the magnitude of change in corticosterone was greater during the light phase. This work highlights the importance of studying circadian rhythms to elucidate biological mechanisms of stress.
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Affiliation(s)
- Laura K. Fonken
- To whom correspondence should be addressed: Laura K. Fonken, Department of Psychology and Neuroscience, University of Colorado, Muenzinger Psychology D244, 1905, Colorado Ave., Boulder, CO 80309 USA.
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Frank MG, Weber MD, Watkins LR, Maier SF. Stress-induced neuroinflammatory priming: A liability factor in the etiology of psychiatric disorders. Neurobiol Stress 2015; 4:62-70. [PMID: 27981190 PMCID: PMC5146200 DOI: 10.1016/j.ynstr.2015.12.004] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 12/23/2015] [Indexed: 12/09/2022] Open
Abstract
Stress and glucocorticoids (GCs) have universally been considered to be anti-inflammatory, however in recent years, stress and GCs have been found to exert permissive effects (immunological priming) on neuroinflammatory processes. This phenomenon of priming is characterized by prior stress or GC exposure potentiating the neuroinflammatory response to a subsequent immune challenge. A considerable body of evidence is discussed here that supports this permissive effect of stress and GCs. In light of this evidence, a mechanism of neuroinflammatory priming is proposed involving a signal cascade in the brain involving danger-associated molecular patterns (HMGB-1) and inflammasomes (NLRP3), which results in an exaggerated or amplified neuroinflammatory response and subsequently, the amplification of the physiological and behavioral sequelae of this response (i.e. sickness). Finally, we explore the notion that stressor-induced sensitization of the neuroimmune microenvironment may predispose individuals to psychiatric disorders, in which exaggerated innate immune/inflammatory responses in the brain are now thought to play a key role.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado, Boulder, CO, USA
| | - Michael D Weber
- Institute for Behavioral Medicine Research, The Ohio State University, Columbus, OH, USA
| | - Linda R Watkins
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado, Boulder, CO, USA
| | - Steven F Maier
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado, Boulder, CO, USA
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Frank MG, Weber MD, Watkins LR, Maier SF. Stress sounds the alarmin: The role of the danger-associated molecular pattern HMGB1 in stress-induced neuroinflammatory priming. Brain Behav Immun 2015; 48:1-7. [PMID: 25816800 PMCID: PMC4508196 DOI: 10.1016/j.bbi.2015.03.010] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/12/2015] [Accepted: 03/18/2015] [Indexed: 02/07/2023] Open
Abstract
High mobility group box-1 (HMGB1) is an endogenous danger signal or alarmin that mediates activation of the innate immune response including chemotaxis and pro-inflammatory cytokine release. HMGB1 has been implicated in the pathophysiology of several neuroinflammatory conditions including ischemia, traumatic brain injury, seizure and chronic ethanol use. In the present review, the unique structural and functional properties of HMGB1 will be explored including its affinity for multiple pattern recognition receptors (TLR2/TLR4), redox sensitivity and adjuvant-like properties. In light of recent evidence suggesting that HMGB1 may also mediate stress-induced sensitization of neuroinflammatory responses, mechanisms of HMGB1 action in neuroinflammatory priming are explored. A model of neuroinflammatory priming is developed wherein glucocorticoids induce synthesis and release of HMGB1 from microglia, which signals through TLR2/TLR4, thereby priming the NLRP3 inflammasome. We propose that if GCs reach a critical threshold as during a fight/flight response, they may thus function as an alarmin by inducing HMGB1, thereby preparing an organism's innate immune system (NLRP3 inflammasome priming) for subsequent immune challenges such as injury, trauma or infection, which are more likely to occur during a fight/flight response. In doing so, GCs may confer a significant survival advantage by enhancing the central innate immune and sickness response to immune challenges.
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Affiliation(s)
- Matthew G. Frank
- Corresponding Author: Department of Psychology and Neuroscience, Center for Neuroscience, Campus Box 345, University of Colorado Boulder, Boulder, CO, 80309-0345, USA, Tel: +1-303-919-8116, Fax: +1-303-492-2967,
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Abstract
PURPOSE OF REVIEW Glucocorticoids have been universally regarded as anti-inflammatory; however, a considerable number of studies now demonstrate that under some conditions, glucocorticoids are capable of potentiating neuroinflammatory processes (i.e. priming), a permissive function of glucocorticoids. The present review addresses recent evidence that provides insight into the mechanism(s) of glucocorticoid-induced neuroinflammatory priming. RECENT FINDINGS Glucocorticoids have been found to prime inflammasomes [i.e. nucleotide-binding domain, leucine-rich repeat, pyrin domain containing proteins-3 (NLRP3)], which are intracellular multiprotein complexes that mediate proinflammatory processes. Inflammasomes are activated by products of stressed or damaged cells. Interestingly, these products (damage-associated molecular patterns) are induced by stress and mediate stress-induced neuroinflammatory priming. SUMMARY In light of these findings, we propose a model of glucocorticoid-induced neuroinflammatory priming whereby stress and glucocorticoids induce cellular damage/stress in the brain, the products of which prime the NLRP3 inflammasome. Thus, glucocorticoid-induced priming of the NLRP3 inflammasome may mediate the potentiated neuroinflammatory response to a subsequent proinflammatory immune challenge. We propose that during a flight-or-flight response, available energy stores should be diverted to defensive behaviours, and it might be after the emergency is over that resources should be shifted to recuperation and host defense against infection. This is the scenario that would be promoted by elevated glucocorticoids reducing ongoing inflammation while simultaneously priming the NLRP3 inflammasome.
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Affiliation(s)
- Matthew G. Frank
- Corresponding Author: Department of Psychology and Neuroscience, Center for Neuroscience, Campus Box 345, University of Colorado Boulder, Boulder, CO, 80309-0345, USA, Tel: +1-303-919-8116, Fax: +1-303-492-2967,
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Fonken LK, Frank MG, Kitt MM, Barrientos RM, Watkins LR, Maier SF. Microglia inflammatory responses are controlled by an intrinsic circadian clock. Brain Behav Immun 2015; 45:171-9. [PMID: 25433170 PMCID: PMC4386638 DOI: 10.1016/j.bbi.2014.11.009] [Citation(s) in RCA: 182] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 11/04/2014] [Accepted: 11/18/2014] [Indexed: 10/24/2022] Open
Abstract
The circadian system regulates many physiological functions including inflammatory responses. For example, mortality caused by lipopolysaccharide (LPS) injection varies depending on the time of immunostimulation in mammals. The effects of more subtle challenges on the immune system and cellular mechanisms underlying circadian differences in neuroinflammatory responses are not well understood. Here we show that adult male Sprague-Dawley rats injected with a sub-septic dose of LPS during the light phase displayed elevated sickness behaviors and hippocampal cytokine production compared to rats injected during the dark phase. Microglia are the primary central nervous system (CNS) immune cell type and may mediate diurnal differences in sickness response, thus we explored whether microglia demonstrate temporal variations in inflammatory factors. Hippocampal microglia isolated from adult rats rhythmically expressed inflammatory factors and circadian clock genes. Microglia displayed robust rhythms of TNFα, IL1β and IL6 mRNA, with peak cytokine gene expression occurring during the middle of the light phase. Microglia isolated during the light phase were also more reactive to immune stimulation; such that, ex vivo LPS treatment induced an exaggerated cytokine response in light phase-isolated microglia. Treating microglia with corticosterone ex vivo induced expression of the circadian clock gene Per1. However, microglia isolated from adrenalectomized rats maintained temporal differences in clock and inflammatory gene expression. This suggests circadian clock gene expression in microglia is entrained by, but oscillates in the absence of, glucocorticoids. Taken together, these findings demonstrate that microglia possess a circadian clock that influences inflammatory responses. These results indicate time-of-day is an important factor to consider when planning inflammatory interventions such as surgeries or immunotherapies.
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Affiliation(s)
- Laura K. Fonken
- To whom correspondence should be addressed: Laura K. Fonken, Department of Psychology and Neuroscience, University of Colorado, Muenzinger Psychology D244, 1905 Colorado Ave., Boulder, CO 80309 USA.
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Barrientos RM, Thompson VM, Arnold TH, Frank MG, Watkins LR, Maier SF. The role of hepatic and splenic macrophages in E. coli-induced memory impairments in aged rats. Brain Behav Immun 2015; 43:60-7. [PMID: 25043992 PMCID: PMC4258417 DOI: 10.1016/j.bbi.2014.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 06/28/2014] [Accepted: 07/08/2014] [Indexed: 12/11/2022] Open
Abstract
Bi-directional communication between the peripheral and central nervous systems has been extensively demonstrated. Aged rats exhibit a prolonged proinflammatory response in the hippocampus region of the brain following a peripheral bacterial infection, and this response in turn causes robust memory declines. Here we aimed to determine whether hepatic or splenic macrophages play a role in the maintenance of this central response. Proinflammatory cytokines measured in liver and spleen four days following an Escherichia coli infection revealed a potentiated proinflammatory response in liver, and to a lesser extent in spleen, in aged relative to young rats. To determine whether this potentiated response was caused by impaired bacterial clearance in these organs, E. coli colony forming units in liver and spleen were measured 4 days after infection, and there were no difference between young and aged rats in either organ. No E. coli was detected in the hippocampus, eliminating the possibility that the aged blood brain barrier allowed E. coli to enter the brain. Depletion of hepatic and splenic macrophages with clodronate-encapsulated liposomes effectively eliminated the proinflammatory response to E. coli at four days in both organs. However, this treatment failed to reduce the proinflammatory response in the hippocampus. Moreover, depletion of peripheral macrophages from liver and spleen did not prevent E. coli-induced memory impairment. These data strongly suggest that hepatic and splenic macrophages do not play a major role in the long-lasting maintenance of the proinflammatory response in the hippocampus of aged rats following a bacterial infection, or the memory declines that this response produces.
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Affiliation(s)
- Ruth M Barrientos
- Dept. of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA.
| | - Vanessa M Thompson
- Dept. of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - T Hayes Arnold
- Dept. of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Matthew G Frank
- Dept. of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Linda R Watkins
- Dept. of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Steven F Maier
- Dept. of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309, USA
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Kreisel T, Frank MG, Licht T, Reshef R, Ben-Menachem-Zidon O, Baratta MV, Maier SF, Yirmiya R. Dynamic microglial alterations underlie stress-induced depressive-like behavior and suppressed neurogenesis. Mol Psychiatry 2014; 19:699-709. [PMID: 24342992 DOI: 10.1038/mp.2013.155] [Citation(s) in RCA: 456] [Impact Index Per Article: 45.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2013] [Revised: 09/16/2013] [Accepted: 10/10/2013] [Indexed: 12/17/2022]
Abstract
The limited success in understanding the pathophysiology of major depression may result from excessive focus on the dysfunctioning of neurons, as compared with other types of brain cells. Therefore, we examined the role of dynamic alterations in microglia activation status in the development of chronic unpredictable stress (CUS)-induced depressive-like condition in rodents. We report that following an initial period (2-3 days) of stress-induced microglial proliferation and activation, some microglia underwent apoptosis, leading to reductions in their numbers within the hippocampus, but not in other brain regions, following 5 weeks of CUS exposure. At that time, microglia displayed reduced expression of activation markers as well as dystrophic morphology. Blockade of the initial stress-induced microglial activation by minocycline or by transgenic interleukin-1 receptor antagonist overexpression rescued the subsequent microglial apoptosis and decline, as well as the CUS-induced depressive-like behavior and suppressed neurogenesis. Similarly, the antidepressant drug imipramine blocked the initial stress-induced microglial activation as well as the CUS-induced microglial decline and depressive-like behavior. Treatment of CUS-exposed mice with either endotoxin, macrophage colony-stimulating factor or granulocyte-macrophage colony-stimulating factor, all of which stimulated hippocampal microglial proliferation, partially or completely reversed the depressive-like behavior and dramatically increased hippocampal neurogenesis, whereas treatment with imipramine or minocycline had minimal or no anti-depressive effects, respectively, in these mice. These findings provide direct causal evidence that disturbances in microglial functioning has an etiological role in chronic stress-induced depression, suggesting that microglia stimulators could serve as fast-acting anti-depressants in some forms of depressive and stress-related conditions.
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Affiliation(s)
- T Kreisel
- Department of Psychology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - M G Frank
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, USA
| | - T Licht
- Deparment of Developmental Biology and Cancer Research, Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - R Reshef
- Department of Psychology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | | | - M V Baratta
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, USA
| | - S F Maier
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, USA
| | - R Yirmiya
- Department of Psychology, The Hebrew University of Jerusalem, Jerusalem, Israel
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Frank MG, Hershman SA, Weber MD, Watkins LR, Maier SF. Chronic exposure to exogenous glucocorticoids primes microglia to pro-inflammatory stimuli and induces NLRP3 mRNA in the hippocampus. Psychoneuroendocrinology 2014; 40:191-200. [PMID: 24485491 PMCID: PMC3912460 DOI: 10.1016/j.psyneuen.2013.11.006] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 11/06/2013] [Accepted: 11/07/2013] [Indexed: 10/26/2022]
Abstract
Chronic stress as well as chronic treatment with glucocorticoids (GCs) primes the neuroinflammatory response to a subsequent pro-inflammatory challenge. However, it remains unclear whether chronic GCs sensitize the response of key CNS immune substrates (i.e. microglia) to pro-inflammatory stimuli. In the present set of studies, male Sprague-Dawley rats underwent sham surgery or were adrenalectomized and then treated with varying concentrations of corticosterone (CORT; 0, 25, 50, and 75 μg/ml) administered in their drinking water. After 10 days of CORT exposure, whole hippocampus was collected and expression of glial activation markers measured or hippocampal microglia were isolated and challenged with LPS to probe for CORT-induced sensitization of pro-inflammatory responses. Chronic CORT exposure increased the gene expression of NLRP3, Iba-1, MHCII, and NF-κBIα in a concentration dependent manner. Chronic CORT (75 μg/ml) exposure potentiated the microglial proinflammatory response (TNFα, IL-1β, IL-6 and NLRP3) to LPS compared to the microglial response of sham surgery animals treated with vehicle. The present set of results demonstrate that chronic exposure to GCs primes microglia to pro-inflammatory stimuli and add to a growing body of evidence suggesting that a permissive function of GCs is that of an endogenous danger signal or alarmin.
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Affiliation(s)
- Matthew G. Frank
- Corresponding Author: Department of Psychology and Neuroscience, Center for Neuroscience, Campus Box 345, University of Colorado at Boulder, Boulder, CO, 80309-0345, USA, Tel: +1-303-919-8116, Fax: +1-303-492-2967,
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Frank MG, Watkins LR, Maier SF. Stress-induced glucocorticoids as a neuroendocrine alarm signal of danger. Brain Behav Immun 2013; 33:1-6. [PMID: 23459026 PMCID: PMC5652304 DOI: 10.1016/j.bbi.2013.02.004] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 01/30/2013] [Accepted: 02/13/2013] [Indexed: 11/24/2022] Open
Abstract
A considerable number of studies demonstrate that acute and chronic stressors prime CNS innate immune responses to subsequent pro-inflammatory challenges and that glucocorticoids mediate, in part, stress-induced sensitization of pro-inflammatory immune responses. Here, we explore the notion that GCs produce a persisting sensitization of CNS innate immune effectors (e.g. microglia) so that they will generate a potentiated pro-inflammatory response after the GC rise has dissipated, thereby enhancing the sickness response to infection or injury and maximizing the animal's ability to neutralize danger. The stress-induced GC response is conceptualized here as an neuroendocrine warning signal or alarmin to the innate immune system, which prepares or sensitizes the innate immune response to potential danger. Thus, a new understanding of the stress response and its function (priming CNS innate immune responses to infection or injury during a fight/flight emergency) would be suggested.
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Affiliation(s)
- Matthew G. Frank
- Corresponding author. Address: Department of Psychology and Neuroscience, Center for Neuroscience, Campus Box 345, University of Colorado at Boulder, Boulder, CO 80309-0345, USA. Tel: +1 303 919 8116; fax: +1 303 492 2967. (M.G. Frank)
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Weber MD, Frank MG, Sobesky JL, Watkins LR, Maier SF. Blocking toll-like receptor 2 and 4 signaling during a stressor prevents stress-induced priming of neuroinflammatory responses to a subsequent immune challenge. Brain Behav Immun 2013; 32:112-21. [PMID: 23500798 PMCID: PMC3810175 DOI: 10.1016/j.bbi.2013.03.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 02/26/2013] [Accepted: 03/08/2013] [Indexed: 11/16/2022] Open
Abstract
Acute and chronic stressors sensitize or prime the neuroinflammatory response to a subsequent peripheral or central immunologic challenge. However, the neuroimmune process(es) by which stressors prime or sensitize subsequent neuroinflammatory responses remains unclear. Prior evidence suggested that toll-like receptors (TLRs) might be involved in the mediation of primed neuroinflammatory responses, but the role of TLRs during a stressor has never been directly tested. Here, a novel TLR2 and TLR4 antagonist, OxPAPC, was used to probe the contribution of TLRs in the stress sensitization phenomenon. OxPAPC has not previously been administered to the brain, and so its action in blocking TLR2 and TLR4 action in brain was first verified. Administration of OxPAPC into the CNS prior to stress prevented the stress-induced potentiation of hippocampal pro-inflammatory response to a subsequent peripheral LPS challenge occurring 24 h later. In addition, in vivo administration of OxPAPC prior to stress prevented the sensitized pro-inflammatory response from isolated microglia following administration of LPS ex vivo, further implicating microglia as a key neuroimmune substrate that mediates stress-induced sensitized neuroinflammation.
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Affiliation(s)
- Michael D. Weber
- Corresponding Author: Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0345, USA. Phone number: 614-937-2613. Fax number: 303-492-2967,
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Frank MG, Barrientos RM, Thompson BM, Weber MD, Watkins LR, Maier SF. IL-1RA injected intra-cisterna magna confers extended prophylaxis against lipopolysaccharide-induced neuroinflammatory and sickness responses. J Neuroimmunol 2012; 252:33-9. [PMID: 22871632 PMCID: PMC5652306 DOI: 10.1016/j.jneuroim.2012.07.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 06/13/2012] [Accepted: 07/19/2012] [Indexed: 01/20/2023]
Abstract
IL-1RA has been used intra-cerebrally to ameliorate neuroinflammatory responses. The present study explored the possibility that the bioactivity of IL-1RA administered intra-cerebrally may be prolonged in the CNS. hIL-1RA was detected in hippocampus from 2h to 14d post-ICM treatment. hIL-1RA ameliorated both the hippocampal cytokine (TNFα and NFκBIα) and sickness response to peripheral LPS administered 4d after hIL-1RA. Four days post treatment, hIL-1RA reduced the basal expression of IL-1R1, Iba-1, MHCII, and TLR4 and blunted the microglial IL-1β and IL-6 response to LPS ex vivo. IL-1RA might be administered prophylactically to prevent the neuroinflammatory effects of trauma.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO 80309-0345, USA.
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Barrientos RM, Frank MG, Watkins LR, Maier SF. Aging-related changes in neuroimmune-endocrine function: implications for hippocampal-dependent cognition. Horm Behav 2012; 62:219-27. [PMID: 22370243 PMCID: PMC3371098 DOI: 10.1016/j.yhbeh.2012.02.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Revised: 02/08/2012] [Accepted: 02/10/2012] [Indexed: 01/12/2023]
Abstract
Healthy aged individuals are more likely to suffer profound memory impairments following a challenging life event such as a severe bacterial infection, surgery, or an intense psychological stressor, than are younger adults. Importantly, these peripheral challenges are capable of producing a neuroinflammatory response, (e.g., increased pro-inflammatory cytokines). In this review we will present the literature demonstrating that in the healthy aged brain this response is exaggerated and prolonged. Normal aging primes or sensitizes microglia and this appears to be the source of this amplified response. We will review the growing literature suggesting that a dysregulated neuroendocrine response in the aged organism is skewed toward higher brain CORT levels, and that this may play a critical role in priming microglia. Among the outcomes of an exaggerated neuroinflammatory response are impairments in synaptic plasticity, and reductions in key downstream mediators such as Arc and BDNF. We will show that each of these mechanisms is important for long-term memory formation, and is compromised by elevated pro-inflammatory cytokines.
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Affiliation(s)
- Ruth M Barrientos
- Department of Psychology and Neuroscience, University of Colorado at Boulder, Boulder, CO 80309, USA.
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Hains LE, Loram LC, Taylor FR, Strand KA, Wieseler JL, Barrientos RM, Young JJ, Frank MG, Sobesky J, Martin TJ, Eisenach JC, Maier SF, Johnson JD, Fleshner M, Watkins LR. Prior laparotomy or corticosterone potentiates lipopolysaccharide-induced fever and sickness behaviors. J Neuroimmunol 2011; 239:53-60. [PMID: 21907418 DOI: 10.1016/j.jneuroim.2011.08.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 08/12/2011] [Accepted: 08/16/2011] [Indexed: 12/31/2022]
Abstract
Stimulating sensitized immune cells with a subsequent immune challenge results in potentiated pro-inflammatory responses translating into exacerbated sickness responses (i.e. fever, pain and lethargy). Both corticosterone (CORT) and laparotomy cause sensitization, leading to enhanced sickness-induced neuroinflammation or pain (respectively). However, it is unknown whether this sensitization affects all sickness behaviors and immune cell responses equally. We show that prior CORT and prior laparotomy potentiated LPS-induced fever but not lethargy. Prior CORT, like prior laparotomy, was able to potentiate sickness-induced pain. Release of nitric oxide (NO) from peritoneal macrophages stimulated ex vivo demonstrates that laparotomy, but not CORT sensitizes these cells.
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Hains LE, Loram LC, Weiseler JL, Frank MG, Bloss EB, Sholar P, Taylor FR, Harrison JA, Martin TJ, Eisenach JC, Maier SF, Watkins LR. Pain intensity and duration can be enhanced by prior challenge: initial evidence suggestive of a role of microglial priming. J Pain 2011; 11:1004-14. [PMID: 20434956 DOI: 10.1016/j.jpain.2010.01.271] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2009] [Revised: 12/12/2009] [Accepted: 01/25/2010] [Indexed: 01/09/2023]
Abstract
UNLABELLED Activation of spinal microglia and consequent release of proinflammatory mediators facilitate pain. Under certain conditions, responses of activated microglia can become enhanced. Enhanced microglial production of proinflammatory products may result from priming (sensitization), similar to macrophage priming. We hypothesized that if spinal microglia were primed by an initial inflammatory challenge, subsequent challenges may create enhanced pain. Here, we used a "two-hit" paradigm using 2 successive challenges, which affect overlapping populations of spinal microglia, presented 2 weeks apart. Mechanical allodynia and/or activation of spinal glia were assessed. Initially, laparotomy preceded systemic lipopolysaccharide (LPS). Prior laparotomy caused prolonged microglial (not astrocyte) activation plus enhanced LPS-induced allodynia. In this "two-hit" paradigm, minocycline, a microglial activation inhibitor, significantly reduced later exaggerated pain induced by prior surgery when minocycline was administered intrathecally for 5 days starting either at the time of surgery or 5 days before LPS administration. To test generality of the priming effect, subcutaneous formalin preceded intrathecal HIV-1 gp120, which activates spinal microglia and causes robust allodynia. Prior formalin enhanced intrathecal gp120-induced allodynia, suggesting that microglial priming is not limited to laparotomy and again supporting a spinal site of action. Therefore, spinal microglial priming may increase vulnerability to pain enhancement. PERSPECTIVE Spinal microglia may become "primed" (sensitized) following their activation by disparate forms of peripheral trauma/inflammation. As a result, such primed microglia may overrespond to subsequent challenges, thereby enhancing pain intensity and duration.
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Affiliation(s)
- Leah E Hains
- Department of Psychology and Neuroscience, and the Center for Neuroscience, University of Colorado at Boulder, Boulder, Colorado 80309-0345, USA
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Frank MG, Barrientos RM, Watkins LR, Maier SF. Aging sensitizes rapidly isolated hippocampal microglia to LPS ex vivo. J Neuroimmunol 2010; 226:181-4. [PMID: 20537730 DOI: 10.1016/j.jneuroim.2010.05.022] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 05/01/2010] [Accepted: 05/05/2010] [Indexed: 12/19/2022]
Abstract
The present study tested whether aging sensitizes hippocampal microglia to a pro-inflammatory challenge ex vivo. Hippocampal microglia from 3 and 24 mo old male F344 x BN F1 rats were exposed to LPS (0, 0.1, 1, 10 and 100 ng/ml) ex vivo. 2 h post-LPS challenge, gene expression of microglial activation markers and cytokines were assessed. 24 mo old animals exhibited a potentiated pro-inflammatory cytokine (IL-1β and IL-6) response to LPS and increased levels of CD11b, Iba-1 and MHCII irrespective of LPS treatment. The present results demonstrate that aging sensitizes hippocampal microglia to pro-inflammatory challenges.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO 80309-0345, USA.
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Soderquist RG, Sloane EM, Loram LC, Harrison JA, Dengler EC, Johnson SM, Amer LD, Young CS, Lewis MT, Poole S, Frank MG, Watkins LR, Milligan ED, Mahoney MJ. Release of plasmid DNA-encoding IL-10 from PLGA microparticles facilitates long-term reversal of neuropathic pain following a single intrathecal administration. Pharm Res 2010; 27:841-54. [PMID: 20224990 DOI: 10.1007/s11095-010-0077-y] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 02/01/2010] [Indexed: 01/23/2023]
Abstract
PURPOSE Interleukin-10 (IL-10) is an anti-inflammatory molecule that has achieved interest as a therapeutic for neuropathic pain. In this work, the potential of plasmid DNA-encoding IL-10 (pDNA-IL-10) slowly released from biodegradable microparticles to provide long-term pain relief in an animal model of neuropathic pain was investigated. METHODS PLGA microparticles encapsulating pDNA-IL-10 were developed and assessed both in vitro and in vivo. RESULTS In vitro, pDNA containing microparticles activated macrophages, enhanced the production of nitric oxide, and increased the production of IL-10 protein relative to levels achieved with unencapsulated pDNA-IL-10. In vivo, intrathecally administered microparticles embedded in meningeal tissue, induced phagocytic cell recruitment to the cerebrospinal fluid, and relieved neuropathic pain for greater than 74 days following a single intrathecal administration, a feat not achieved with unencapsulated pDNA. Therapeutic effects of microparticle-delivered pDNA-IL-10 were blocked in the presence of IL-10-neutralizing antibody, and elevated levels of plasmid-derived IL-10 were detected in tissues for a prolonged time period post-injection (>28 days), demonstrating that therapeutic effects are dependent on IL-10 protein production. CONCLUSIONS These studies demonstrate that microparticle encapsulation significantly enhances the potency of intrathecally administered pDNA, which may be extended to treat other disorders that require intrathecal gene therapy.
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Affiliation(s)
- Ryan Gene Soderquist
- Department of Chemical & Biological Engineering, University of Colorado at Boulder, 424 UCB, Boulder, Colorado, 80309, USA
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Frank MG, Barrientos RM, Hein AM, Biedenkapp JC, Watkins LR, Maier SF. IL-1RA blocks E. coli-induced suppression of Arc and long-term memory in aged F344xBN F1 rats. Brain Behav Immun 2010; 24:254-62. [PMID: 19822205 PMCID: PMC2818379 DOI: 10.1016/j.bbi.2009.10.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2009] [Revised: 10/03/2009] [Accepted: 10/05/2009] [Indexed: 11/29/2022] Open
Abstract
In normal aging, a peripheral immune challenge induces a sensitized and protracted neuroinflammatory response in parallel with long-term memory (LTM) impairments. Pro-inflammatory mediators of neuroinflammation impair LTM, synaptic plasticity and LTP. The immediate early gene Arc is considered a critical protein regulating LTM and synaptic plasticity. The present investigation examined whether (1) a peripheral Escherichia coli infection suppresses hippocampal Arc expression, and (2) central pro-inflammatory cytokines (IL-1beta and IL-6) mediate the effects of peripheral E. coli infection on Arc and LTM. In 24 months F344xBN F1 rats, E. coli infection suppressed basal Arc gene expression as well as contextual fear conditioning-induced Arc expression. E. coli treatment failed to alter either basal or conditioning-induced c-Fos expression. At 24h post-infection, intra-cisterna magna (ICM) treatment with the anti-inflammatory cytokine IL-1RA blocked the E. coli-induced suppression of hippocampal Arc and increases in IL-6 protein. At 4-day post-infection, IL-1RA blocked the E. coli-induced LTM impairments and increases in IL-6 protein. The present results suggest that central pro-inflammatory cytokines play a salient role in the suppression of Arc and impairments of LTM by a peripheral immune challenge in older animals.
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Affiliation(s)
- Matthew G. Frank
- Department of Psychology and Center for Neuroscience, Campus Box 345, University of Colorado at Boulder, Boulder, CO, 80309-0345, USA,Corresponding author: Department of Psychology and Center for Neuroscience, Campus Box 345 University of Colorado at Boulder Boulder, CO, 80309-0345, USA Tel: +1-303-919-8116 Fax: +1-303-492-2967
| | - Ruth M. Barrientos
- Department of Psychology and Center for Neuroscience, Campus Box 345, University of Colorado at Boulder, Boulder, CO, 80309-0345, USA
| | - Amy M. Hein
- Department of Neurobiology and Anatomy, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
| | | | - Linda R. Watkins
- Department of Psychology and Center for Neuroscience, Campus Box 345, University of Colorado at Boulder, Boulder, CO, 80309-0345, USA
| | - Steven F. Maier
- Department of Psychology and Center for Neuroscience, Campus Box 345, University of Colorado at Boulder, Boulder, CO, 80309-0345, USA
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Barrientos RM, Frank MG, Watkins LR, Maier SF. Memory impairments in healthy aging: Role of aging-induced microglial sensitization. Aging Dis 2010; 1:212-231. [PMID: 21132050 PMCID: PMC2995216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 09/09/2010] [Accepted: 09/09/2010] [Indexed: 05/30/2023] Open
Abstract
Healthy aged individuals are more likely to suffer profound memory impairments following a challenging life event such as a severe bacterial infection, surgery, or an intense psychological stressor, than are younger adults. These peripheral challenges are capable of producing a neuroinflammatory response, (e.g., increased pro-inflammatory cytokines), and in the healthy aged brain this response is exaggerated and prolonged. Normal aging primes or sensitizes microglia and this appears to be the source of this amplified response. Among the outcomes of this exaggerated neuroinflammatory response is an impairment in synaptic plasticity, and a reduction in key downstream mediators such as Arc and BDNF. Each of these mechanisms is important for long-term memory formation, and is compromised by elevated pro-inflammatory cytokines. Pharmacological, dietary and physical interventions are discussed as potential therapies to abrogate the challenge-induced neuroinflammatory response, thereby preventing or reducing memory deficits in aged subjects.
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Affiliation(s)
- Ruth M. Barrientos
- Correspondence should be addressed to: Dr. Ruth M. Barrientos, Dept. of Psychology and Neuroscience, University of Colorado at Boulder, Boulder, CO 80309, USA. E-mail:
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Frank MG, Miguel ZD, Watkins LR, Maier SF. Prior exposure to glucocorticoids sensitizes the neuroinflammatory and peripheral inflammatory responses to E. coli lipopolysaccharide. Brain Behav Immun 2010; 24:19-30. [PMID: 19647070 DOI: 10.1016/j.bbi.2009.07.008] [Citation(s) in RCA: 218] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 07/23/2009] [Accepted: 07/25/2009] [Indexed: 11/26/2022] Open
Abstract
Acute and chronic stress has been found to sensitize or prime the neuroinflammatory response to both peripheral and central immunologic challenges. Several studies suggest that stress-induced sensitization of neuroinflammatory processes may be mediated by the glucocorticoid (GC) response to stress. GCs, under some conditions, exhibit pro-inflammatory properties, however whether GCs are sufficient to prime neuroinflammatory responses has not been systematically investigated. In the present investigation, we tested whether acute administration of exogenous GCs would be sufficient to reproduce the stress-induced sensitization of neuroinflammatory responses under a number of different timing relationships between GC administration and immune challenge (lipopolysaccharide; LPS). We demonstrate here that GCs potentiate both the peripheral (liver) and central (hippocampus) pro-inflammatory response (e.g. TNFalpha, IL-1beta, IL-6) to a peripheral immune challenge (LPS) if GCs are administered prior (2 and 24h) to challenge. Prior exposure (24h) to GCs also potentiated the pro-inflammatory response of hippocampal microglia to LPS ex vivo. In contrast, when GCs are administered after (1h) a peripheral immune challenge, GCs suppress the pro-inflammatory response to LPS in both liver and hippocampus. GCs also up-regulated microglial activation markers including Toll-like Receptor 2. The present data suggest that the temporal relationship between GC treatment and immune challenge may be an important factor determining whether GCs exhibit pro- or anti-inflammatory properties.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Center for Neuroscience, Campus Box 345, University of Colorado at Boulder, Boulder, CO, 80309-0345, USA.
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Barrientos RM, Frank MG, Hein AM, Higgins EA, Watkins LR, Rudy JW, Maier SF. Time course of hippocampal IL-1 beta and memory consolidation impairments in aging rats following peripheral infection. Brain Behav Immun 2009; 23:46-54. [PMID: 18664380 PMCID: PMC2630971 DOI: 10.1016/j.bbi.2008.07.002] [Citation(s) in RCA: 171] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Revised: 07/02/2008] [Accepted: 07/03/2008] [Indexed: 11/17/2022] Open
Abstract
We previously reported that aging F344XBN rats are more vulnerable to disruptions of memory consolidation processes following an injection of Escherichia coli than are young rats. Furthermore, this disruption was specific to hippocampal-dependent memory. In the present study we examined the time course of the proinflammatory cytokine IL-1 beta in young and old rats following a peripheral injection of E. coli. Compared to young rats, aging rats treated with E. coli showed an exaggerated and prolonged up-regulation of IL-1 beta protein in the hippocampus, but not in hypothalamus, parietal cortex, prefrontal cortex, serum or spleen. Aging rats showed greater hippocampal IL-1 beta protein levels than their young counterparts 4h after E. coli, and these levels remained significantly elevated for 8 but not 14 days after E. coli. In a second experiment, aging rats exhibited anterograde memory consolidation impairments 4 and 8 days after an E. coli injection, but not after 14 days. A third experiment revealed that following an E. coli injection, bacterial clearance from the spleen and peritoneum was not impaired in aged rats, suggesting that elevations in hippocampal IL-1 beta were not mediated by impaired clearance in the periphery in aging rats. These data suggest that the exaggerated and prolonged elevation of IL-1 beta, specifically in the hippocampus, may be responsible for hippocampal-dependent memory impairments observed in aging rats following a bacterial infection.
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Affiliation(s)
- Ruth M Barrientos
- Department of Psychology & Center for Neuroscience, Campus Box 345, University of Colorado at Boulder, Boulder, CO 80309-0345, USA.
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Schoeniger-Skinner DK, Ledeboer A, Frank MG, Milligan ED, Poole S, Martin D, Maier SF, Watkins LR. Interleukin-6 mediates low-threshold mechanical allodynia induced by intrathecal HIV-1 envelope glycoprotein gp120. Brain Behav Immun 2007; 21:660-7. [PMID: 17204394 PMCID: PMC1991283 DOI: 10.1016/j.bbi.2006.10.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 10/11/2006] [Accepted: 10/20/2006] [Indexed: 12/20/2022] Open
Abstract
Spinal cord glia (microglia and astrocytes) contribute to enhanced pain states. One model that has been used to study this phenomenon is intrathecal (i.t.) administration of gp120, an envelope glycoprotein of HIV-1 known to activate spinal cord glia and thereby induce low-threshold mechanical allodynia, a pain symptom where normally innocuous (non-painful) stimuli are perceived as painful. Previous studies have shown that i.t. gp120-induced allodynia is mediated via the release of the glial pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF), and interleukin-1beta (IL-1). As we have recently reported that i.t. gp120 induces the release of interleukin-6 (IL-6), in addition to IL-1 and TNF, the present study tested whether this IL-6 release in spinal cord contributes to gp120-induced mechanical allodynia and/or to gp120-induced increases in TNF and IL-1. An i.t. anti-rat IL-6 neutralizing antibody was used to block IL-6 actions upon its release by i.t. gp120. This IL-6 blockade abolished gp120-induced mechanical allodynia. While the literature predominantly documents the cascade of pro-inflammatory cytokines as beginning with TNF, followed by the stimulation of IL-1, and finally TNF plus IL-1 stimulating the release of IL-6, the present findings indicate that a blockade of IL-6 inhibits the gp120-induced elevations of TNF, IL-1, and IL-6 mRNA in dorsal spinal cord, elevation of IL-1 protein in lumbar dorsal spinal cord, and TNF and IL-1 protein release into the surrounding lumbosacral cerebrospinal fluid. These results would suggest that IL-6 induces pain facilitation, and may do so in part by stimulating the production and release of other pro-inflammatory cytokines.
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Affiliation(s)
- Diana K. Schoeniger-Skinner
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
| | - Annemarie Ledeboer
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
| | - Matthew G. Frank
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
| | - Erin D. Milligan
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
| | - Stephen Poole
- Division of Endocrinology, National Institute for Biological Standards and Control, South Mimms, Potters Bar, Herts Eng 3QG, United Kingdom
| | - David Martin
- Department of Pharmacology, Amgen, Thousand Oaks, CA 91320
| | - Steven F. Maier
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
| | - Linda R. Watkins
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
- # To whom correspondence should be addressed: Department of Psychology, Muenzinger D-244, Campus Box 345, University of Colorado at Boulder, Boulder, CO 30809-0345, Ph: 303-492-7034, Fax: 303-492-2967,
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Frank MG, Der-Avakian A, Bland ST, Watkins LR, Maier SF. Stress-induced glucocorticoids suppress the antisense molecular regulation of FGF-2 expression. Psychoneuroendocrinology 2007; 32:376-84. [PMID: 17383826 DOI: 10.1016/j.psyneuen.2007.02.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Revised: 01/19/2007] [Accepted: 02/01/2007] [Indexed: 11/23/2022]
Abstract
Psychological stress can upregulate basic fibroblast growth factor (FGF-2) expression. Because glucocorticoids can also upregulate FGF-2 expression, the present studies investigated whether stress-induced glucocorticoids mediate the effects of stress on FGF-2. FGF-2 is regulated by an FGF-2 antisense (AS) molecular mechanism and so the present experiments also, for the first time, assessed the effects of stress on FGF-2-AS mRNA, as well as the mediating role of glucocorticoids. The effects of either escapable shock (ES) or yoked-inescapable tail shock (IS) on FGF-2 and FGF-2-AS were determined. To test whether glucocorticoids mediate the effect of stress on FGF-2 and FGF-2-AS, animals were pretreated with temporary corticosterone (CORT) synthesis inhibitors and exposed to IS. To test whether glucocorticoids are sufficient to modulate FGF-2 and FGF-2-AS mRNA, animals were injected with CORT and mRNA measured. ES and IS similarly downregulated FGF-2-AS mRNA at 0 h post-stress and upregulated FGF-2 mRNA 2 h post-stress. Inhibition of CORT synthesis abrogated the effect of IS on both FGF-2-AS and FGF-2 mRNA. Exogenous CORT mimicked the effects of ES and IS on FGF-2, but not FGF-2-AS mRNA. The present study demonstrates that glucocorticoids mediate the effects of stress on FGF-2 and FGF-2-AS.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Center for Neuroscience, Campus Box 345, University of Colorado, Boulder, CO 80309-0345, USA.
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Holguin A, Frank MG, Biedenkapp JC, Nelson K, Lippert D, Watkins LR, Rudy JW, Maier SF. Characterization of the temporo-spatial effects of chronic bilateral intrahippocampal cannulae on interleukin-1beta. J Neurosci Methods 2007; 161:265-72. [PMID: 17241670 PMCID: PMC2464278 DOI: 10.1016/j.jneumeth.2006.11.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 11/18/2006] [Accepted: 11/28/2006] [Indexed: 11/23/2022]
Abstract
The implantation of a foreign object in the brain produces an acute neuroinflammatory state in which glia (astrocytes and microglia) may remain chronically activated in response to the inert foreign object. Activated glia can exhibit a sensitized pro-inflammatory response to immunogenic stimuli. This may be relevant to intracranial cannula implantation, which is commonly used to administer substances directly into the brain. If intracranial cannulation activates glia, a subsequent neuroinflammatory stimulus might induce a potentiated pro-inflammatory response, thereby introducing a potential experimental confound. We tested the temporal and spatial responses of interleukin-1beta (IL-1beta) to an acute immune challenge produced by lipopolysaccharide (LPS) in animals with chronic bilateral intrahippocampal cannulae implants (stainless steel). Cannulation increased the gene expression of the microglia activation antigens MHC II and CD11b, but not the astrocyte antigen GFAP. Moreover, this activation was temporally and spatially dependent. In addition, IL-1beta mRNA, but not IL-1beta protein, was significantly elevated in cannulated animals. Administration of LPS, however, significantly potentiated the brain IL-1beta response in cannulated animals, but not in stab wounded or naïve animals. This IL-1beta response was also temporo-spatially dependent. Thus, the pro-inflammatory sequelae of intracranial cannulation should be considered when designing studies of neuroinflammatory processes.
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Affiliation(s)
- Adelina Holguin
- Department of Psychology, Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309, USA.
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Frank MG, Baratta MV, Sprunger DB, Watkins LR, Maier SF. Microglia serve as a neuroimmune substrate for stress-induced potentiation of CNS pro-inflammatory cytokine responses. Brain Behav Immun 2007; 21:47-59. [PMID: 16647243 DOI: 10.1016/j.bbi.2006.03.005] [Citation(s) in RCA: 423] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 03/06/2006] [Accepted: 03/09/2006] [Indexed: 02/07/2023] Open
Abstract
Prior exposure to a stressor can potentiate CNS pro-inflammatory immune responses to a peripheral immune challenge. However, the neuroimmune substrate(s) mediating this effect has not been determined. The present investigation examined whether microglia serve as this neuroimmune substrate given that microglia are the primary immune effector cell in the CNS. The effect of inescapable shock (IS) on glial activation (MHC II, CD11b, Iba-1, and GFAP) and regulatory markers (CD200) in vivo, and microglia pro-inflammatory responses (interleukin-1beta; IL-1beta) to lipopolysaccharide (LPS) ex vivo, were assessed in rat hippocampus. IS upregulated the microglia activation marker MHC II 24h post-IS, while the astroglia marker GFAP was unaffected. IS also downregulated the neuronal glycoprotein CD200, which functions to hold microglia in a quiescent state. Moreover, IS potentiated the pro-inflammatory response to LPS ex vivo 24h post-IS in isolated hippocampal microglia. Finally, the behavioral controllability of shock was manipulated and the effect of escapable (controllable) shock was comparable to the effect of IS on hippocampal microglia responses to LPS ex vivo. The present results suggest that stress can activate microglia, thereby sensitizing the pro-inflammatory reactivity of microglia to immunogenic stimuli.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Center for Neuroscience, Campus Box 345, University of Colorado, Boulder, CO 80309-0345, USA.
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Milligan ED, Sloane EM, Langer SJ, Hughes TS, Jekich BM, Frank MG, Mahoney JH, Levkoff LH, Maier SF, Cruz PE, Flotte TR, Johnson KW, Mahoney MM, Chavez RA, Leinwand LA, Watkins LR. Repeated intrathecal injections of plasmid DNA encoding interleukin-10 produce prolonged reversal of neuropathic pain. Pain 2006; 126:294-308. [PMID: 16949747 DOI: 10.1016/j.pain.2006.07.009] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2006] [Revised: 07/05/2006] [Accepted: 07/17/2006] [Indexed: 01/23/2023]
Abstract
Neuropathic pain is a major clinical problem unresolved by available therapeutics. Spinal cord glia play a pivotal role in neuropathic pain, via the release of proinflammatory cytokines. Anti-inflammatory cytokines, like interleukin-10 (IL-10), suppress proinflammatory cytokines. Thus, IL-10 may provide a means for controlling glial amplification of pain. We recently documented that intrathecal IL-10 protein resolves neuropathic pain, albeit briefly (approximately 2-3 h), given its short half-life. Intrathecal gene therapy using viruses encoding IL-10 can also resolve neuropathic pain, but for only approximately 2 weeks. Here, we report a novel approach that dramatically increases the efficacy of intrathecal IL-10 gene therapy. Repeated intrathecal delivery of plasmid DNA vectors encoding IL-10 (pDNA-IL-10) abolished neuropathic pain for greater than 40 days. Naked pDNA-IL-10 reversed chronic constriction injury (CCI)-induced allodynia both shortly after nerve injury as well as 2 months later. This supports that spinal proinflammatory cytokines are important in both the initiation and maintenance of neuropathic pain. Importantly, pDNA-IL-10 gene therapy reversed mechanical allodynia induced by CCI, returning rats to normal pain responsiveness, without additional analgesia. Together, these data suggest that intrathecal IL-10 gene therapy may provide a novel approach for prolonged clinical pain control.
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Affiliation(s)
- Erin D Milligan
- Department of Psychology and the Center for Neuroscience, University of CO at Boulder, Boulder, CO 80309, USA.
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Frank MG, Barrientos RM, Biedenkapp JC, Rudy JW, Watkins LR, Maier SF. mRNA up-regulation of MHC II and pivotal pro-inflammatory genes in normal brain aging. Neurobiol Aging 2006; 27:717-22. [PMID: 15890435 DOI: 10.1016/j.neurobiolaging.2005.03.013] [Citation(s) in RCA: 244] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2005] [Revised: 03/01/2005] [Accepted: 03/05/2005] [Indexed: 02/01/2023]
Abstract
In normal brain aging, CNS resident macrophages exhibit increased expression of major histocompatibility complex (MHC) II expression. However, the transcriptional basis for this observation has not been clarified nor have age-related alterations in pivotal pro-inflammatory genes been characterized. Age-related mRNA alterations in MHC II, MHC II accessory molecules and several pro-inflammatory mediators were measured in older (24 months) and younger (3 months) male F344xBN F1 rats. Real time RT-PCR was utilized to measure steady state mRNA levels in hippocampus. Older as compared to younger animals exhibited increased mRNA levels of MHC II, CD86, CIITA and IFN-gamma. Furthermore, IL-10 and CD200 mRNA, molecules that down-regulate macrophage activation, was decreased in older animals. The present results indicate that normal brain aging is characterized by a shift towards a pro-inflammatory microenvironment in the CNS.
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Affiliation(s)
- Matthew G Frank
- Department of Psychology and Center for Neuroscience, University of Colorado at Boulder, Campus Box 345, Boulder, CO 80309-0345, USA.
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Ginsberg AB, Frank MG, Francis AB, Rubin BA, O'Connor KA, Spencer RL. Specific and time-dependent effects of glucocorticoid receptor agonist RU28362 on stress-induced pro-opiomelanocortin hnRNA, c-fos mRNA and zif268 mRNA in the pituitary. J Neuroendocrinol 2006; 18:129-38. [PMID: 16420282 DOI: 10.1111/j.1365-2826.2005.01396.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
This study examined the effects of the glucocorticoid receptor (GR) agonist RU28362 on stress-induced gene expression in the pituitary of rats to investigate mechanisms of glucocorticoid negative feedback in vivo. In an initial experiment, acute restraint stress produced rapid (within 15 min) induction of c-fos mRNA, zif268 mRNA and pro-opiomelanocortin (POMC) hnRNA within the anterior and intermediate/posterior pituitary as determined by quantitative real-time polymerase chain reaction. Treatment with RU28362 (150 microg/kg, i.p.) 60 min before restraint inhibited adrenocorticotrophic hormone (ACTH) and corticosterone secretion and selectively suppressed the stress-induced increase in POMC hnRNA in the anterior pituitary gland. The failure of RU28362 to surpress the stress-induced rise in c-fos and expression of zif268 mRNA suggests that the central release of ACTH secretagogues was not affected at this time point by treatment with the GR agonist. Rather, the inhibition of ACTH release appeared to be due to a direct effect of RU28362 within the pituitary. A follow-up time-course study varied the interval (10, 60 or 180 min) between RU28362 pretreatment and the onset of restraint. The stress-induced increase in POMC hnRNA was completely blunted by RU28362 treatment within 10 min of treatment, although the stress induced hormone secretion, c-fos mRNA and zif268 mRNA were unaffected. The rapid inhibition of the stress-induced rise in POMC hnRNA in the anterior pituitary appears to reflect direct, GR-mediated suppression of POMC gene expression. RU28362 pretreatment 180 min before restraint onset was sufficient to suppress the stress-induced expression in the anterior pituitary gland of all three genes examined. Thus, the delayed negative feedback effects on hypothalamic-pituitary-adrenal axis activity that emerged after 180 min after glucocorticoid treatment were not evident at 60 min. Taken together, the data suggest that the inhibition of the stress-induced release of ACTH apparent within the first hour of glucocorticoid exposure is effected at the level of the pituitary gland. The delayed glucocorticoid effects evident 180 min after RU28362 treatment may include glucocorticoid actions in the brain and additional actions within the pituitary.
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Affiliation(s)
- A B Ginsberg
- Department of Psychology and Center for Neurosciences, University of Colorado at Boulder, USA.
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