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Trojan E, Tylek K, Schröder N, Kahl I, Brandenburg LO, Mastromarino M, Leopoldo M, Basta-Kaim A, Lacivita E. The N-Formyl Peptide Receptor 2 (FPR2) Agonist MR-39 Improves Ex Vivo and In Vivo Amyloid Beta (1-42)-Induced Neuroinflammation in Mouse Models of Alzheimer's Disease. Mol Neurobiol 2021; 58:6203-6221. [PMID: 34468933 PMCID: PMC8639560 DOI: 10.1007/s12035-021-02543-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 08/21/2021] [Indexed: 01/04/2023]
Abstract
The major histopathological hallmarks of Alzheimer's disease (AD) include β-amyloid (Aβ) plaques, neurofibrillary tangles, and neuronal loss. Aβ 1-42 (Aβ1-42) has been shown to induce neurotoxicity and secretion of proinflammatory mediators that potentiate neurotoxicity. Proinflammatory and neurotoxic activities of Aβ1-42 were shown to be mediated by interactions with several cell surface receptors, including the chemotactic G protein-coupled N-formyl peptide receptor 2 (FPR2). The present study investigated the impact of a new FPR2 agonist, MR-39, on the neuroinflammatory response in ex vivo and in vivo models of AD. To address this question, organotypic hippocampal cultures from wild-type (WT) and FPR2-deficient mice (knockout, KO, FPR2-/-) were treated with fibrillary Aβ1-42, and the effect of the new FPR2 agonist MR-39 on the release of pro- and anti-inflammatory cytokines was assessed. Similarly, APP/PS1 double-transgenic AD mice were treated for 20 weeks with MR-39, and immunohistological staining was performed to assess neuronal loss, gliosis, and Aβ load in the hippocampus and cortex. The data indicated that MR-39 was able to reduce the Aβ1-42-induced release of proinflammatory cytokines and to improve the release of anti-inflammatory cytokines in mouse hippocampal organotypic cultures. The observed effect was apparently related to the inhibition of the MyD88/TRAF6/NFкB signaling pathway and a decrease in NLRP3 inflammasome activation. Administration of MR-39 to APP/PS1 mice improved neuronal survival and decreased microglial cell density and plaque load.These results suggest that FPR2 may be a promising target for alleviating the inflammatory process associated with AD and that MR-39 may be a useful therapeutic agent for AD.
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Affiliation(s)
- Ewa Trojan
- Department of Experimental Neuroendocrinology, Immunoendocrinology Laboratory, Maj Institute of Pharmacology Polish Academy of Sciences, 12 Smętna Str, 31-343, Kraków, Poland
| | - Kinga Tylek
- Department of Experimental Neuroendocrinology, Immunoendocrinology Laboratory, Maj Institute of Pharmacology Polish Academy of Sciences, 12 Smętna Str, 31-343, Kraków, Poland
| | - Nicole Schröder
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
- Department of Anatomy and Cell Biology, RWTH Aachen University, Aachen, Germany
| | - Iris Kahl
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
- Department of Anatomy and Cell Biology, RWTH Aachen University, Aachen, Germany
| | - Lars-Ove Brandenburg
- Institute of Anatomy, Rostock University Medical Center, Rostock, Germany
- Department of Anatomy and Cell Biology, RWTH Aachen University, Aachen, Germany
| | | | - Marcello Leopoldo
- Department of Pharmacy-Drug Sciences, University of Bari, via Orabona 4, 70125, Bari, Italy
| | - Agnieszka Basta-Kaim
- Department of Experimental Neuroendocrinology, Immunoendocrinology Laboratory, Maj Institute of Pharmacology Polish Academy of Sciences, 12 Smętna Str, 31-343, Kraków, Poland.
| | - Enza Lacivita
- Department of Pharmacy-Drug Sciences, University of Bari, via Orabona 4, 70125, Bari, Italy
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Martin-Estebane M, Gomez-Nicola D. Targeting Microglial Population Dynamics in Alzheimer's Disease: Are We Ready for a Potential Impact on Immune Function? Front Cell Neurosci 2020; 14:149. [PMID: 32581720 PMCID: PMC7289918 DOI: 10.3389/fncel.2020.00149] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 05/05/2020] [Indexed: 12/15/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common form of dementia, affecting two-thirds of people with dementia in the world. To date, no disease-modifying treatments are available to stop or delay the progression of AD. This chronic neurodegenerative disease is dominated by a strong innate immune response, whereby microglia plays a central role as the main resident macrophage of the brain. Recent genome-wide association studies (GWASs) have identified single-nucleotide polymorphisms (SNPs) located in microglial genes and associated with a delayed onset of AD, highlighting the important role of these cells on the onset and/or progression of the disease. These findings have increased the interest in targeting microglia-associated neuroinflammation as a potentially disease-modifying therapeutic approach for AD. In this review we provide an overview on the contribution of microglia to the pathophysiology of AD, focusing on the main regulatory pathways controlling microglial population dynamics during the neuroinflammatory response, such as the colony-stimulating factor 1 receptor (CSF1R), its ligands (the colony-stimulating factor 1 and interleukin 34) and the transcription factor PU.1. We also discuss the current therapeutic strategies targeting proliferation to modulate microglia-associated neuroinflammation and their potential impact on peripheral immune cell populations in the short and long-term. Understanding the effects of immunomodulatory approaches on microglia and other immune cell types might be critical for developing specific, effective, and safe therapies for neurodegenerative diseases.
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Affiliation(s)
- Maria Martin-Estebane
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Diego Gomez-Nicola
- School of Biological Sciences, University of Southampton, Southampton, United Kingdom
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3
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Early intraneuronal amyloid triggers neuron-derived inflammatory signaling in APP transgenic rats and human brain. Proc Natl Acad Sci U S A 2020; 117:6844-6854. [PMID: 32144141 PMCID: PMC7104377 DOI: 10.1073/pnas.1914593117] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
This work provides evidence that soluble and oligomeric amyloid protein stokes neuronal inflammation during the earliest stages of Alzheimer’s disease. Identifying neuron-derived factors that engage the brain’s immune system will provide insight into how vulnerable neurons might interact with other immune cells to propagate cytotoxic signaling cascades and cellular dysfunction during disease development. Chronic inflammation during Alzheimer’s disease (AD) is most often attributed to sustained microglial activation in response to amyloid-β (Aβ) plaque deposits and cell death. However, cytokine release and microgliosis are consistently observed in AD transgenic animal models devoid of such pathologies, bringing into question the underlying processes that may be at play during the earliest AD-related immune response. We propose that this plaque-independent inflammatory reaction originates from neurons burdened with increasing levels of soluble and oligomeric Aβ, which are known to be the most toxic amyloid species within the brain. Laser microdissected neurons extracted from preplaque amyloid precursor protein (APP) transgenic rats were found to produce a variety of potent immune factors, both at the transcript and protein levels. Neuron-derived cytokines correlated with the extent of microglial activation and mobilization, even in the absence of extracellular plaques and cell death. Importantly, we identified an inflammatory profile unique to Aβ-burdened neurons, since neighboring glial cells did not express similar molecules. Moreover, we demonstrate within disease-vulnerable regions of the human brain that a neuron-specific inflammatory response may precede insoluble Aβ plaque and tau tangle formation. Thus, we reveal the Aβ-burdened neuron as a primary proinflammatory agent, implicating the intraneuronal accumulation of Aβ as a significant immunological component in the AD pathogenesis.
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Richter M, Vidovic N, Biber K, Dolga A, Culmsee C, Dodel R. The neuroprotective role of microglial cells against amyloid beta-mediated toxicity in organotypic hippocampal slice cultures. Brain Pathol 2020; 30:589-602. [PMID: 31769564 PMCID: PMC8018096 DOI: 10.1111/bpa.12807] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 11/18/2019] [Indexed: 02/02/2023] Open
Abstract
During Alzheimer's disease (AD) progression, microglial cells play complex roles and have potentially detrimental as well as beneficial effects. The use of appropriate model systems is essential for characterizing and understanding the roles of microglia in AD pathology. Here, we used organotypic hippocampal slice cultures (OHSCs) to investigate the impact of microglia on amyloid beta (Aβ)-mediated toxicity. Neurons in OHSCs containing microglia were not vulnerable to cell death after 7 days of repeated treatment with Aβ1-42 oligomer-enriched preparations. However, when clodronate was used to remove microglia, treatment with Aβ1-42 resulted in significant neuronal death. Further investigations indicated signs of endoplasmic reticulum stress and caspase activation after Aβ1-42 challenge only when microglia were absent. Interestingly, microglia provided protection without displaying any classic signs of activation, such as an amoeboid morphology or the release of pro-inflammatory mediators (e.g., IL-6, TNF-α, NO). Furthermore, depleting microglia or inhibiting microglial uptake mechanisms resulted in significant more Aβ deposition compared to that observed in OHSCs containing functional microglia, suggesting that microglia efficiently cleared Aβ. Because inhibiting microglial uptake increased neuronal cell death, the ability of microglia to engulf Aβ is thought to contribute to its protective properties. Our study argues for a beneficial role of functional ramified microglia whereby they act against the accumulation of neurotoxic forms of Aβ and support neuronal resilience in an in situ model of AD pathology.
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Affiliation(s)
- Maren Richter
- Department of Neurology, Philipps-University Marburg, Marburg, Germany.,Institute for Pharmacology and Clinical Pharmacy, Philipps-University Marburg, Marburg, Germany
| | - Natascha Vidovic
- Department of Neurology, Philipps-University Marburg, Marburg, Germany.,Chair of Geriatric Medicine, University Duisburg-Essen, Essen, Germany
| | - Knut Biber
- Molecular Psychiatry, Psychiatric Hospital, University of Freiburg, Freiburg, Germany.,Department of Neuroscience, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Amalia Dolga
- Institute for Pharmacology and Clinical Pharmacy, Philipps-University Marburg, Marburg, Germany.,Department of Molecular Pharmacology, Groningen Research Institute of Pharmacy, Faculty of Science and Engineering, Groningen, the Netherlands
| | - Carsten Culmsee
- Institute for Pharmacology and Clinical Pharmacy, Philipps-University Marburg, Marburg, Germany
| | - Richard Dodel
- Department of Neurology, Philipps-University Marburg, Marburg, Germany.,Chair of Geriatric Medicine, University Duisburg-Essen, Essen, Germany
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Howe MD, Furr JW, Munshi Y, Roy-O’Reilly MA, Maniskas ME, Koellhoffer EC, d’Aigle J, Sansing LH, McCullough LD, Urayama A. Transforming growth factor-β promotes basement membrane fibrosis, alters perivascular cerebrospinal fluid distribution, and worsens neurological recovery in the aged brain after stroke. GeroScience 2019; 41:543-559. [PMID: 31721012 PMCID: PMC6885082 DOI: 10.1007/s11357-019-00118-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 10/04/2019] [Indexed: 12/14/2022] Open
Abstract
Aging and stroke alter the composition of the basement membrane and reduce the perivascular distribution of cerebrospinal fluid and solutes, which may contribute to poor functional recovery in elderly patients. Following stroke, TGF-β induces astrocyte activation and subsequent glial scar development. This is dysregulated with aging and could lead to chronic, detrimental changes within the basement membrane. We hypothesized that TGF-β induces basement membrane fibrosis after stroke, leading to impaired perivascular CSF distribution and poor functional recovery in aged animals. We found that CSF entered the aged brain along perivascular tracts; this process was reduced by experimental stroke and was rescued by TGF-β receptor inhibition. Brain fibronectin levels increased with experimental stroke, which was reversed with inhibitor treatment. Exogenous TGF-β stimulation increased fibronectin expression, both in vivo and in primary cultured astrocytes. Oxygen-glucose deprivation of cultured astrocytes induced multiple changes in genes related to astrocyte activation and extracellular matrix production. Finally, in stroke patients, we found that serum TGF-β levels correlated with poorer functional outcomes, suggesting that serum levels may act as a biomarker for functional recovery. These results support a potential new treatment strategy to enhance recovery in elderly stroke patients.
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Affiliation(s)
- Matthew D. Howe
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030 USA
| | - J. Weldon Furr
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030 USA
| | - Yashasvee Munshi
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030 USA
| | - Meaghan A. Roy-O’Reilly
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030 USA
| | - Michael E. Maniskas
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030 USA
| | - Edward C. Koellhoffer
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030 USA
| | - John d’Aigle
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030 USA
| | - Lauren H. Sansing
- Department of Neurology, Yale University School of Medicine, 1450 Chapel Street, New Haven, CT 06511 USA
| | - Louise D. McCullough
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030 USA
| | - Akihiko Urayama
- Department of Neurology, McGovern Medical School, University of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030 USA
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Irons DL, Meinhardt T, Allers C, Kuroda MJ, Kim WK. Overexpression and activation of colony-stimulating factor 1 receptor in the SIV/macaque model of HIV infection and neuroHIV. Brain Pathol 2019; 29:826-836. [PMID: 31033097 DOI: 10.1111/bpa.12731] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 04/19/2019] [Indexed: 01/09/2023] Open
Abstract
In the present study, we investigated whether colony-stimulating factor 1 receptor (CSF1R) is expressed on brain macrophages and microglia in the human and macaque brain and whether it is upregulated and activated after lentivirus infection in vivo and contributes to development of encephalitic lesions. We examined, using multi-label and semi-quantitative immunofluorescence microscopy, the protein expression level and cellular localization of CSF1R in brain tissues from uninfected controls and SIV-infected adult macaques with or without encephalitis and also from uninfected controls, HIV-infected encephalitic subjects and virally suppressed subjects. In the normal uninfected brain, CSF1R protein was detected only on microglia and brain macrophages but not on neurons, astrocytes or oligodendrocytes. Microglia constitutively expressed CSF1R at low levels, and its expression was largely unchanged in non-encephalitic and encephalitic animals. Brain macrophages, including perivascular macrophages (PVMs), expressed higher levels of CSF1R compared to microglia. Interestingly, we found significantly increased expression of CSF1R on the infected PVMs and lesional macrophages in the brains of encephalitic macaques. Moreover, the per cell expression of CSF1R determined by its mean pixel intensity (MPI) correlated positively with the MPI of SIV Gag p28 in SIV-infected PVMs. Using phosphorylated CSF1R at tyrosine residue 723 and phosphorylated signal transducer and activator of transcription 5 at tyrosine reside 694 as markers for CSF1R activation, we found selective activation of CSF1R signaling in infected brain macrophages in encephalitis. We also found colocalization of CSF1R and its ligand CSF1 in PVMs and lesional macrophages in the brains of encephalitic macaques and humans. Notably, elevated brain CSF1R expression was found in virally suppressed subjects. These findings point to opportunities for developing a specific approach targeting infected brain macrophages, with several brain-penetrant CSF1R inhibitors that are available now, in order to eliminate central nervous system macrophage reservoirs, while not affecting resting uninfected microglia and PVMs that show no CSF1R activation.
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Affiliation(s)
- Derek L Irons
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA
| | - Timothy Meinhardt
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA
| | - Carolina Allers
- The Division of Immunology, Tulane National Primate Research Center, Covington, LA
| | - Marcelo J Kuroda
- The Division of Immunology, Tulane National Primate Research Center, Covington, LA
| | - Woong-Ki Kim
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, Norfolk, VA
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7
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Walker DG, Tang TM, Lue LF. Studies on Colony Stimulating Factor Receptor-1 and Ligands Colony Stimulating Factor-1 and Interleukin-34 in Alzheimer's Disease Brains and Human Microglia. Front Aging Neurosci 2017; 9:244. [PMID: 28848420 PMCID: PMC5552759 DOI: 10.3389/fnagi.2017.00244] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 07/12/2017] [Indexed: 01/08/2023] Open
Abstract
Microglia are dependent on signaling through the colony stimulating factor-1 receptor (CSF-1R/CD115) for growth and survival. Activation of CSF-1R can lead to cell division, while blocking CSF-1R can lead to rapid microglia cell death. CSF-1R has two ligands, the growth factors colony stimulating factor-1 (CSF-1) and the more recently identified interleukin-34 (IL-34). Studies of IL-34 activation of rodent microglia and human macrophages have suggested it has different properties to CSF-1, resulting in an anti-inflammatory reparative phenotype. The goal of this study was to identify if the responses of human postmortem brain microglia to IL-34 differed from their responses to CSF-1 with the aim of identifying different phenotypes of microglia as a result of their responses. To approach this question, we also sought to identify differences between IL-34, CSF-1, and CSF-1R expression in human brain samples to establish whether there was an imbalance in Alzheimer's disease (AD). Using human brain samples [inferior temporal gyrus (ITG) and middle temporal gyrus (MTG)] from distinct cohorts of AD, control and high pathology, or mild cognitive impairment cases, we showed that there was increased expression of CSF-1R and CSF-1 mRNAs in both series of AD cases, and reduced expression of IL-34 mRNA in AD ITG samples. There was no change in expression of these genes in RNA from cerebellum of AD, Parkinson's disease (PD), or control cases. The results suggested an imbalance in CSF-1R signaling in AD. Using RNA sequencing to compare gene expression responses of CSF-1 and IL-34 stimulated human microglia, a profile of responses to CSF-1 and IL-34 was identified. Contrary to earlier work with rodent microglia, IL-34 induced primarily a classical activation response similar to that of CSF-1. It was not possible to identify any genes expressed significantly different by IL-34-stimulated microglia compared to CSF-1-stimulated microglia, but both cytokines did induce certain alternative activation-associated genes. These profiles also showed that a number of genes associated with lysosomal function and Aβ removal were downregulated by IL-34 and CSF-1 stimulation. Compared to earlier results our data indicate that CSF-1R stimulation by IL-34 or CSF-1 produced similar types of responses by elderly postmortem brain-derived microglia.
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Affiliation(s)
- Douglas G Walker
- Neurodegenerative Disease Research Center, Biodesign Institute, Arizona State UniversityTempe, AZ, United States.,Laboratory of Neuroinflammation, Banner Sun Health Research Institute, Sun CityArizona, AZ, United States
| | - Tiffany M Tang
- Neurodegenerative Disease Research Center, Biodesign Institute, Arizona State UniversityTempe, AZ, United States
| | - Lih-Fen Lue
- Neurodegenerative Disease Research Center, Biodesign Institute, Arizona State UniversityTempe, AZ, United States.,Laboratory of Neuroinflammation, Banner Sun Health Research Institute, Sun CityArizona, AZ, United States
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8
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Pathologic role of glial nitric oxide in adult and pediatric neuroinflammatory diseases. Neurosci Biobehav Rev 2014; 45:168-82. [DOI: 10.1016/j.neubiorev.2014.06.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Revised: 05/28/2014] [Accepted: 06/05/2014] [Indexed: 01/22/2023]
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Cacabelos R, Fernández-Novoa L, Lombardi V, Corzo L, Pichel V, Kubota Y. Cerebrovascular risk factors in Alzheimer's disease: Brain hemodynamics and pharmacogenomic implications. Neurol Res 2013; 25:567-80. [PMID: 14503010 DOI: 10.1179/016164103101202002] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Recent evidence indicates that different vascular risk factors are present in Alzheimer's disease (AD) and other prevalent dementia types probably contributing to deterioration of cerebrovascular function, thus enhancing neurodegeneration and premature neuronal death due to a reduction in brain perfusion. Brain blood flow shows a reduced velocity and increased pulsatility (PI) and resistance indices (RI) in different types of dementia and in diabetes and hypertension, as well. High levels of diastolic blood pressure correlate with diminished brain blood flow and elevated PI and RI, accompanied by cognitive deterioration. Nitric oxide (NO) levels are found increased in the sera and brain tissue of AD patients. Vascular risk factors (hyperglycemia, LDL-cholesterol, triglycerides, hypertension) and altered brain hemodynamic parameters correlate with APOE genotypes of which APOE-4/4 carriers represent the AD population with the highest cerebrovascular risk. In addition, the genomic profiles of patients with dementia integrating AD-related genes (APOE, PS1, PS2, cFOS) in a mini-tetragenic haplotype significantly differ from controls with an absolute genetic variation of about 50%-60%. Cerebrovascular dysfunction is a factor common to most types of dementia; however, genetic variation among different dementia types might be determinant for the activation of early vascular events inducing or accelerating neurodegeneration. In this regard, cerebrovascular dysfunction should be considered a potential therapeutic target in dementia.
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Affiliation(s)
- Ramón Cacabelos
- Department of Clinical Neuroscience, EBIOTEC, EuroEspes Biomedical Research Center, Institute for CNS Disorders, Bergondo, Coruña, Spain.
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Song M, Jin J, Lim JE, Kou J, Pattanayak A, Rehman JA, Kim HD, Tahara K, Lalonde R, Fukuchi KI. TLR4 mutation reduces microglial activation, increases Aβ deposits and exacerbates cognitive deficits in a mouse model of Alzheimer's disease. J Neuroinflammation 2011; 8:92. [PMID: 21827663 PMCID: PMC3169468 DOI: 10.1186/1742-2094-8-92] [Citation(s) in RCA: 213] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 08/09/2011] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Amyloid plaques, a pathological hallmark of Alzheimer's disease (AD), are accompanied by activated microglia. The role of activated microglia in the pathogenesis of AD remains controversial: either clearing Aβ deposits by phagocytosis or releasing proinflammatory cytokines and cytotoxic substances. Microglia can be activated via toll-like receptors (TLRs), a class of pattern-recognition receptors in the innate immune system. We previously demonstrated that an AD mouse model homozygous for a loss-of-function mutation of TLR4 had increases in Aβ deposits and buffer-soluble Aβ in the brain as compared with a TLR4 wild-type AD mouse model at 14-16 months of age. However, it is unknown if TLR4 signaling is involved in initiation of Aβ deposition as well as activation and recruitment of microglia at the early stage of AD. Here, we investigated the role of TLR4 signaling and microglial activation in early stages using 5-month-old AD mouse models when Aβ deposits start. METHODS Microglial activation and amyloid deposition in the brain were determined by immunohistochemistry in the AD models. Levels of cerebral soluble Aβ were determined by ELISA. mRNA levels of cytokines and chemokines in the brain and Aβ-stimulated monocytes were quantified by real-time PCR. Cognitive functions were assessed by the Morris water maze. RESULTS While no difference was found in cerebral Aβ load between AD mouse models at 5 months with and without TLR4 mutation, microglial activation in a TLR4 mutant AD model (TLR4M Tg) was less than that in a TLR4 wild-type AD model (TLR4W Tg). At 9 months, TLR4M Tg mice had increased Aβ deposition and soluble Aβ42 in the brain, which were associated with decrements in cognitive functions and expression levels of IL-1β, CCL3, and CCL4 in the hippocampus compared to TLR4W Tg mice. TLR4 mutation diminished Aβ-induced IL-1β, CCL3, and CCL4 expression in monocytes. CONCLUSION This is the first demonstration of TLR4-dependent activation of microglia at the early stage of β-amyloidosis. Our results indicate that TLR4 is not involved in the initiation of Aβ deposition and that, as Aβ deposits start, microglia are activated via TLR4 signaling to reduce Aβ deposits and preserve cognitive functions from Aβ-mediated neurotoxicity.
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Affiliation(s)
- Min Song
- Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, PO Box 1649, Peoria, IL 61656, USA
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Gowing G, Lalancette-Hébert M, Audet JN, Dequen F, Julien JP. Macrophage colony stimulating factor (M-CSF) exacerbates ALS disease in a mouse model through altered responses of microglia expressing mutant superoxide dismutase. Exp Neurol 2009; 220:267-75. [DOI: 10.1016/j.expneurol.2009.08.021] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Revised: 08/20/2009] [Accepted: 08/22/2009] [Indexed: 01/19/2023]
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12
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Yadav A, Collman RG. CNS inflammation and macrophage/microglial biology associated with HIV-1 infection. J Neuroimmune Pharmacol 2009; 4:430-47. [PMID: 19768553 PMCID: PMC5935112 DOI: 10.1007/s11481-009-9174-2] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 09/03/2009] [Indexed: 10/20/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) infection of the central nervous system (CNS) can result in neurological dysfunction with devastating consequences in a significant proportion of individuals with acquired immune deficiency syndrome. HIV-1 does not infect neurons directly but induces damage indirectly through the accumulation of activated macrophage/microglia (M/M) cells, some of which are infected, that release neurotoxic mediators including both cellular activation products and viral proteins. One mechanism for the accumulation of activated M/M involves the development in infected individuals of an activated peripheral blood monocyte population that traffics through the blood-brain barrier, a process that also serves to carry virus into CNS and establish local infection. A second mechanism involves the release by infected and activated M/M in the CNS of chemotactic mediators that recruit additional monocytes from the periphery. These activated M/M, some of which are infected, release a number of cytokines and small molecule mediators as well as viral proteins that act on bystander cells and in turn activate them, thus amplifying the cascade. These viral proteins and cellular products have neurotoxic properties as well, both directly and through induction of astrocyte dysfunction, which ultimately lead to neuronal injury and death. In patients effectively treated with antiretroviral therapy, frank dementia is now uncommon and has been replaced by milder forms of neurocognitive impairment, with less frequent and more focal neuropathology. This review summarizes key findings that support the critical role and mechanisms of monocyte/macrophage activation and inflammation as a major component for HIV-1 encephalitis or HIV-1 associated dementia.
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Affiliation(s)
- Anjana Yadav
- Department of Medicine and Center for AIDS Research, University of Pennsylvania School of Medicine, 522 Johnson Pavilion, 36th & Hamilton Walk, Philadelphia, PA 19104, USA
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Wisor JP, Striz M, DeVoss J, Murphy GM, Edgar DM, O'Hara BF. A novel quantitative trait locus on mouse chromosome 18, "era1," modifies the entrainment of circadian rhythms. Sleep 2008; 30:1255-63. [PMID: 17969459 DOI: 10.1093/sleep/30.10.1255] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
STUDY OBJECTIVE The mammalian circadian clock in the suprachiasmatic nuclei (SCN) of the hypothalamus conveys 24-h rhythmicity to sleep-wake cycles, locomotor activity, and other behavioral and physiological processes. The timing of rhythms relative to the light/dark (LD12:12) cycle is influenced in part by the endogenous circadian period and the time of day specific sensitivity of the clock to light. We now describe a novel circadian rhythm phenotype, and a locus influencing that phenotype, in a segregating population of mice. METHODS By crossbreeding 2 genetically distinct nocturnal strains of mice (Cast/Ei and C57BL/6J) and backcrossing the resulting progeny to Cast/Ei, we have produced a novel circadian phenotype, called early runner mice. RESULTS Early runner mice entrain to a light/dark cycle at an advanced phase, up to 9 hours before dark onset. This phenotype is not significantly correlated with circadian period in constant darkness and is not associated with disruption of molecular circadian rhythms in the SCN, as assessed by analysis of period gene expression. We have identified a genomic region that regulates this phenotype-a major quantitative trait locus on chromosome 18 (near D18Mit184) that we have named era1 for Early Runner Activity locus one. Phase delays caused by light exposure early in the subjective night were of smaller magnitude in backcross offspring that were homozygous Cast/Ei at D18Mit184 than in those that were heterozygous at this locus. CONCLUSION Genetic variability in the circadian response to light may, in part, explain the variance in phase angle of entrainment in this segregating mouse population.
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Affiliation(s)
- Jonathan P Wisor
- Molecular Neurobiology Laboratory, SRI International, Menlo Park, CA 94025, USA.
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Cumiskey D, Curran BP, Herron CE, O'Connor JJ. A role for inflammatory mediators in the IL-18 mediated attenuation of LTP in the rat dentate gyrus. Neuropharmacology 2007; 52:1616-23. [PMID: 17459425 DOI: 10.1016/j.neuropharm.2007.03.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Revised: 02/23/2007] [Accepted: 03/12/2007] [Indexed: 10/23/2022]
Abstract
Pro-inflammatory cytokines are known to be elevated in several pathological conditions that are associated with deficits in cognition. We have previously demonstrated that interleukin-18 (IL-18) inhibits long-term potentiation (LTP) in the dentate gyrus in vitro. In this study we have examined the involvement of the inflammatory mediators COX-2 and iNOS in IL-18-mediated inhibition of LTP. The effect of an anti-inflammatory PPARgamma agonist was also investigated. We report that the impairment of LTP by IL-18 is significantly attenuated by prior application of the COX-2 inhibitor, SC-236 and the iNOS inhibitor 1400W. These agents had no effect on paired pulse depression in the dentate gyrus. Furthermore, application of the PPARgamma agonist ciglitazone also attenuated IL-18-mediated inhibition of LTP. We discuss a role for p38 MAP kinase in these effects. This study provides novel evidence for the involvement of inflammatory mediators in IL-18-mediated inhibition of LTP in the rat dentate gyrus in vitro.
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Affiliation(s)
- D Cumiskey
- UCD School of Biomolecular and Biomedical Science, UCD Conway Institute of Biomolecular & Biomedical Research, Belfield, Dublin 4, Ireland
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15
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Lalancette-Hébert M, Gowing G, Simard A, Weng YC, Kriz J. Selective ablation of proliferating microglial cells exacerbates ischemic injury in the brain. J Neurosci 2007; 27:2596-605. [PMID: 17344397 PMCID: PMC6672496 DOI: 10.1523/jneurosci.5360-06.2007] [Citation(s) in RCA: 685] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Here we report in vivo evidence of a neuroprotective role of proliferating microglial cells in cerebral ischemia. Using transgenic mice expressing a mutant thymidine kinase form of herpes simplex virus driven by myeloid-specific CD11b promoter and ganciclovir treatment as a tool, we selectively ablated proliferating (Mac-2 positive) microglia after transient middle cerebral artery occlusion. The series of experiments using green fluorescent protein-chimeric mice demonstrated that within the first 72 h after ischemic injury, the Mac-2 marker [unlike Iba1 (ionized calcium-binding adapter molecule 1)] was preferentially expressed by the resident microglia. Selective ablation of proliferating resident microglia was associated with a marked alteration in the temporal dynamics of proinflammatory cytokine expression, a significant increase in the size of infarction associated with a 2.7-fold increase in the number of apoptotic cells, predominantly neurons, and a 1.8-fold decrease in the levels of IGF-1. A double-immunofluorescence analysis revealed a approximately 100% colocalization between IGF-1 positive cells and Mac-2, a marker of activated/proliferating resident microglia. Conversely, stimulation of microglial proliferation after cerebral ischemia by M-CSF (macrophage colony stimulating factor) resulted in a 1.9-fold increase in IGF-1 levels and a significant increase of Mac2+ cells. Our findings suggest that a postischemic proliferation of the resident microglial cells may serve as an important modulator of a brain inflammatory response. More importantly, our results revealed a marked neuroprotective potential of proliferating microglia serving as an endogenous pool of neurotrophic molecules such as IGF-1, which may open new therapeutic avenues in the treatment of stroke and other neurological disorders.
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Affiliation(s)
- Mélanie Lalancette-Hébert
- Department of Anatomy and Physiology, Laval University, Centre de Recherche du Centre Hospitalier de l'Université Laval, Quebec, Canada G1V 4G2
| | - Geneviève Gowing
- Department of Anatomy and Physiology, Laval University, Centre de Recherche du Centre Hospitalier de l'Université Laval, Quebec, Canada G1V 4G2
| | - Alain Simard
- Department of Anatomy and Physiology, Laval University, Centre de Recherche du Centre Hospitalier de l'Université Laval, Quebec, Canada G1V 4G2
| | - Yuan Cheng Weng
- Department of Anatomy and Physiology, Laval University, Centre de Recherche du Centre Hospitalier de l'Université Laval, Quebec, Canada G1V 4G2
| | - Jasna Kriz
- Department of Anatomy and Physiology, Laval University, Centre de Recherche du Centre Hospitalier de l'Université Laval, Quebec, Canada G1V 4G2
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16
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Chiou WF. Effect of Aβ exposure on the mRNA expression patterns of voltage-sensitive calcium channel α1 subunits (α1A–α1D) in human SK-N-SH neuroblastoma. Neurochem Int 2006; 49:256-61. [PMID: 16574279 DOI: 10.1016/j.neuint.2006.01.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Revised: 12/29/2005] [Accepted: 01/24/2006] [Indexed: 11/18/2022]
Abstract
Evidence for loss of Ca(2+) homeostasis through voltage-sensitive Ca(2+) channels (VSCCs) contribution to neuronal degeneration induced by beta-amyloid protein (Abeta) is considerable and rapidly increasing. Thus, the expression patterns of four alpha(1) subunits for P/Q (alpha(1A))-, N (alpha(1B))-, and L (alpha(1C) and alpha(1D))-type VSCCs before and after Abeta exposure were investigated in human SK-N-SH neuroblastoma. Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed a constitutive and abundant co-expression of mRNA for alpha(1A) and alpha(1D) subunit in control cells. The mRNA expression of another L-type subunit alpha(1C) was undetectable in control cells while N-type subunit alpha(1B) was relative lower when compared to alpha(1A) and alpha(1D) subunits. Interestingly, mRNA levels of alpha(1A), alpha(1B), and alpha(1C) were remarkably and time-dependently increased in response to Abeta (20 microM) for 72 h culture period. In contrast, the constitutively expressed alpha(1D) mRNA was not further modified during Abeta exposure. Western blot analysis of four alpha(1) subunits expression was consistent with the findings obtained by RT-PCR. In conclusion, our results suggested that P/Q-, N-, as well as L-type Ca(2+) channel genes might be existed in SK-N-SH cells. Among them, mRNA for alpha(1A), alpha(1B), and alpha(1D) were expressed constitutively while alpha(1C) were inducible. Furthermore, Abeta exposure selectively modulates the transcription of alpha(1A), alpha(1B), and alpha(1C) subunits. These suggested that except activating of existed VSCCs, up-regulation of alpha(1) subunits expression might also contribute to Abeta-induced neuronal toxicity and the complex of these VSCCs expression may participate in Ca(2+) current disturbance in Alzheimer's disease.
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Affiliation(s)
- Wen-Fei Chiou
- Division of Basic Chinese Medical Research, National Research Institute of Chinese Medicine, No. 155-1, Sec. 2, Li-Nung St., Shipai, Taipei 112, Taiwan, ROC.
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17
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Ishikawa T, Aoshiba K, Yokohori N, Nagai A. Macrophage Colony-Stimulating Factor Aggravates Rather than Regenerates Emphysematous Lungs in Mice. Respiration 2006; 73:538-45. [PMID: 16601323 DOI: 10.1159/000092545] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Accepted: 12/12/2005] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Lung regeneration is an innovative strategy that may cure pulmonary emphysema. The bone marrow (BM) harbors pulmonary stem cells. Hematopoietic cytokine-driven mobilization of BM cells may thus support lung regeneration. OBJECTIVES The aim of this study was to determine whether systemic administration of macrophage colony-stimulating factor (M-CSF) leads to the regeneration of lungs in a murine model of elastase-induced emphysema. METHODS C57BL/6J mice were administered elastase intratracheally. Four weeks later, in the absence or presence of elastase treatment, mice were intraperitoneally given either M-CSF or saline on days 1-5 each week for 3 weeks. Lung tissue was harvested 24 h after the last injection. RESULTS M-CSF administration without prior elastase did not affect the mean linear intercept, surface area, or surface area/lung volume. In contrast, M-CSF administration following elastase injury caused a greater increase in the mean linear intercept and greater decreases in surface area and surface area/lung volume than saline administration following elastase, indicating that M-CSF aggravated emphysema. This aggravation of emphysema was accompanied by accumulation of pulmonary alveolar macrophages (AMs) expressing metalloproteinase (MMP)-9 and MMP-12. M-CSF stimulated AMs to express MMPs in vitro. CONCLUSIONS These results suggest that M-CSF administration does not support lung regeneration but rather aggravates the lung destruction associated with elastase injury.
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Affiliation(s)
- Takaaki Ishikawa
- First Department of Medicine, Tokyo Women's Medical University, Tokyo, Japan
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Abstract
Elevated levels of NO produced within the central nervous system (CNS) are associated with the pathogenesis of neuroinflammatory and neurodegenerative human diseases such as multiple sclerosis, HIV dementia, brain ischemia, trauma, Parkinson's disease, and Alzheimer's disease. Resident glial cells in the CNS (astroglia and microglia) express inducible nitric oxide synthase (iNOS) and produce high levels of NO in response to a wide variety of proinflammatory and degenerative stimuli. Although pathways resulting in the expression of iNOS may vary in two different glial cells of different species, the intracellular signaling events required for the expression of iNOS in these cells are slowly becoming clear. Various signaling cascades converge to activate several transcription factors that control the transcription of iNOS in glial cells. The present review summarizes different results and discusses current understandings about signaling mechanisms for the induction of iNOS expression in activated glial cells. A complete understanding of the regulation of iNOS expression in glial cells is expected to identify novel targets for therapeutic intervention in NO-mediated neurological disorders.
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Affiliation(s)
- Ramendra N Saha
- Department of Oral Biology, Section of Neuroscience, University of Nebraska Medical Center, Lincoln, 68583, USA
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Chitu V, Stanley ER. Colony-stimulating factor-1 in immunity and inflammation. Curr Opin Immunol 2005; 18:39-48. [PMID: 16337366 DOI: 10.1016/j.coi.2005.11.006] [Citation(s) in RCA: 456] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Accepted: 11/24/2005] [Indexed: 11/17/2022]
Abstract
Colony-stimulating factor-1 (CSF-1, also known as macrophage-CSF) is the primary regulator of the survival, proliferation, differentiation and function of mononuclear phagocytes. Studies that involve CSF-1-deficient mice demonstrate that there is a variable requirement for CSF-1 in the development of individual mononuclear phagocyte populations. However, these cells uniformly express the CSF-1 receptor, and their morphology, phagocytosis and responsiveness to infectious and non-infectious stimuli is regulated by CSF-1. CSF-1 plays important roles in innate immunity, cancer and inflammatory diseases, including systemic lupus erythematosus, arthritis, atherosclerosis and obesity. In several conditions, activation of macrophages involves a CSF-1 autocrine loop. In addition, secreted and cell-surface isoforms of CSF-1 can have differential effects in inflammation and immunity.
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Affiliation(s)
- Violeta Chitu
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, NY 10461, USA
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20
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Gingerich S, Krukoff TL. Estrogen modulates endothelial and neuronal nitric oxide synthase expression via an estrogen receptor beta-dependent mechanism in hypothalamic slice cultures. Endocrinology 2005; 146:2933-41. [PMID: 15790731 DOI: 10.1210/en.2004-1375] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Although it is evident that estrogen has important physiological effects in the brain, the signaling mechanisms mediating these effects remain unclear. We recently showed that estrogen mediates attenuated blood pressure responses to psychological stress in ovariectomized female rats through brain nitric oxide (NO). An area likely to mediate these effects is the hypothalamic paraventricular nucleus (PVN), because here NO exerts inhibitory effects on autonomic output to the periphery. Because little is known about how estrogen acts on the NO system in the PVN, our aim was to study the effects of estrogen on the NO system in the PVN of hypothalamic slices cultures. We show that 17beta-estradiol (E2; 1 nm) increases endothelial NO synthase (eNOS) protein expression and decreases the numbers of neuronal NOS (nNOS)-positive neurons in the PVN after 8 and 24 h, respectively. Using the nonselective estrogen receptor (ER) antagonist, ICI 182,780 (10 nm), we determined that E2-induced changes in NOS expression in the PVN are ER dependent. Using the ERbeta agonist, genistein (0.1 microm), we determined that activation of ERbeta induces increased eNOS expression and a decreased number of nNOS-positive neurons. We used the selective ERalpha agonist, propyl-pyrazole-triol (10 nm), and antagonist, methyl-piperidino-pyrazole (1 microm), to exclude the possibility that ERalpha is involved in the E2-induced increase in eNOS and nNOS in the PVN. These results demonstrate that E2 induces changes in NOS expression in the PVN and that these effects are ERbeta dependent.
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Affiliation(s)
- Sarah Gingerich
- Center for Neuroscience, Department of Cell Biology, University of Alberta, Edmonton, Canada T6G 2H7
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von Bernhardi R, Eugenín J. Microglial reactivity to β-amyloid is modulated by astrocytes and proinflammatory factors. Brain Res 2004; 1025:186-93. [PMID: 15464759 DOI: 10.1016/j.brainres.2004.07.084] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2004] [Indexed: 12/24/2022]
Abstract
The brains of Alzheimer's disease (AD) patients present activated glial cells, amyloid plaques and dystrophic neurites. The core of amyloid plaques is composed of aggregated amyloid peptide (Abeta), a peptide known to activate glial cells and to have neurotoxic effects. We evaluated the capability of glial cells to mediate Abeta(1-42) cytotoxicity in hippocampal cultures. Conditioned media obtained from microglial cultures exposed to Abeta induced apoptosis of hippocampal cells. This pro-apoptotic effect was not observed in hippocampal cultures exposed to conditioned media obtained from mixed glial (astrocytes and microglia) cultures that had been exposed to Abeta. Microglia exposed to Abeta responded with reactive morphological changes, induction of iNOS, elevated nitric oxide production and decreased reductive metabolism. All these responses were attenuated by the presence of astrocytes. This astrocyte modulation was however, not observed when glial cells were exposed to proinflammatory factors (LPS+Interferon-gamma) alone or in combination with Abeta. Our results suggest that astrocytes and proinflammatory molecules are determining factors in the response of microglia to Abeta.
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Affiliation(s)
- Rommy von Bernhardi
- Department of Neurology, Faculty of Medicine, Pontificia Universidad Católica de Chile, Av. Libertador Bernardo O'Higgins 340, Santiago, Chile.
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Mitrasinovic OM, Robinson CC, Tenen DG, Lee YL, Poon C, Murphy GM. Biolistic expression of the macrophage colony stimulating factor receptor in organotypic cultures induces an inflammatory response. J Neurosci Res 2004; 77:420-9. [PMID: 15248298 DOI: 10.1002/jnr.20168] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The receptor for macrophage colony-stimulating factor (M-CSFR; c-fms) is expressed at increased levels by microglia in Alzheimer's disease (AD) and in mouse models for AD. Increased expression of M-CSFR on cultured microglia results in a strong proinflammatory response, but the relevance of this cell culture finding to intact brain is unknown. To determine the effects of increased microglial expression of M-CSFR in a complex organotypic environment, we developed a system for biolistic transfection of microglia in hippocampal slice cultures. The promoter for the Mac-1 integrin alpha subunit CD11b is active in cells of myeloid origin. In the brain, CD11b expression is restricted to microglia. Constructs consisting of the promoter for CD11b and a c-fms cDNA or an enhanced green fluorescent protein (EGFP) cDNA were introduced into monotypic cultures of microglia, neurons, and astrocytes. Strong CD11b promoter activity was observed in microglia, whereas little activity was observed in other cell types. Biolistic transfection of organotypic hippocampal cultures with the CD11b/c-fms construct resulted in expression of the c-fms mRNA and protein that was localized to microglia. Furthermore, biolistic overexpression of M-CSFR on microglia resulted in significantly increased production by the hippocampal cultures of the proinflammatory cytokines interleukin (IL)-1alpha macrophage inflammatory protein (MIP-1alpha), and trends toward increased production of IL-6 and M-CSF. These findings demonstrate that microglial overexpression of M-CSFR in an organotypic environment induces an inflammatory response, and suggest that increased microglial expression of M-CSFR could contribute to the inflammatory response observed in AD brain.
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Affiliation(s)
- Olivera M Mitrasinovic
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California 94305-5485, USA
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McCullough L, Wu L, Haughey N, Liang X, Hand T, Wang Q, Breyer RM, Andreasson K. Neuroprotective function of the PGE2 EP2 receptor in cerebral ischemia. J Neurosci 2004; 24:257-68. [PMID: 14715958 PMCID: PMC6729582 DOI: 10.1523/jneurosci.4485-03.2004] [Citation(s) in RCA: 314] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The cyclooxygenases COX-1 and COX-2 catalyze the first committed step of prostaglandin synthesis from arachidonic acid. Previous studies in rodent stroke models have shown that the inducible COX-2 isoform promotes neuronal injury, and the administration of COX-2 inhibitors reduces infarct volume. We investigated the function of PGE2, a principal prostaglandin product of COX-2 enzymatic activity, in neuronal survival in cerebral ischemia. PGE2 exerts its downstream effects by signaling through a class of four distinct G-protein-coupled EP receptors (for E-prostanoid: EP1, EP2, EP3, and EP4) that have divergent effects on cAMP and phosphoinositol turnover and different anatomical distributions in brain. The EP2 receptor subtype is abundantly expressed in cerebral cortex, striatum, and hippocampus, and is positively coupled to cAMP production. In vitro studies of dispersed neurons and organotypic hippocampal cultures demonstrated that activation of the EP2 receptor was neuroprotective in paradigms of NMDA toxicity and oxygen glucose deprivation. Pharmacologic blockade of EP2 signaling by inhibition of protein kinase A activation reversed this protective effect, suggesting that EP2-mediated neuroprotection is dependent on cAMP signaling. In the middle cerebral artery occlusion-reperfusion model of transient forebrain ischemia, genetic deletion of the EP2 receptor significantly increased cerebral infarction in cerebral cortex and subcortical structures. These studies indicate that activation of the PGE2 EP2 receptor can protect against excitotoxic and anoxic injury in a cAMP-dependent manner. Taken together, these data suggest a novel mechanism of neuroprotection mediated by a dominant PGE2 receptor subtype in brain that may provide a target for therapeutic intervention.
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Affiliation(s)
- Louise McCullough
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Shimadzu H, Suemoto T, Suzuki M, Shiomitsu T, Okamura N, Kudo Y, Sawada T. A novel probe for imaging amyloid-?: Synthesis of F-18 labelled BF-108, an Acridine Orange analog. J Labelled Comp Radiopharm 2003. [DOI: 10.1002/jlcr.716] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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