1801
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Abstract
Microglia and macrophages in the CNS contain multimolecular complexes termed inflammasomes. Inflammasomes function as intracellular sensors for infectious agents as well as for host-derived danger signals that are associated with neurological diseases, including meningitis, stroke and Alzheimer's disease. Assembly of an inflammasome activates caspase 1 and, subsequently, the proteolysis and release of the cytokines interleukin-1β and interleukin-18, as well as pyroptotic cell death. Since the discovery of inflammasomes in 2002, there has been burgeoning recognition of their complexities and functions. Here, we review the current understanding of the functions of different inflammasomes in the CNS and their roles in neurological diseases.
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Affiliation(s)
- John G Walsh
- Department of Medicine (Neurology), University of Alberta, Edmonton, Alberta T6G 2S2, Canada
| | - Daniel A Muruve
- Department of Medicine (Nephrology), University of Calgary, Calgary, Alberta T2N 4N1, Canada
| | - Christopher Power
- Department of Medicine (Neurology), University of Alberta, Edmonton, Alberta T6G 2S2, Canada
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1802
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Baik SH, Cha MY, Hyun YM, Cho H, Hamza B, Kim DK, Han SH, Choi H, Kim KH, Moon M, Lee J, Kim M, Irimia D, Mook-Jung I. Migration of neutrophils targeting amyloid plaques in Alzheimer's disease mouse model. Neurobiol Aging 2014; 35:1286-92. [PMID: 24485508 DOI: 10.1016/j.neurobiolaging.2014.01.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 12/27/2013] [Accepted: 01/04/2014] [Indexed: 01/24/2023]
Abstract
Immune responses in the brain are thought to play a role in disorders of the central nervous system, but an understanding of the process underlying how immune cells get into the brain and their fate there remains unclear. In this study, we used a 2-photon microscopy to reveal that neutrophils infiltrate brain and migrate toward amyloid plaques in a mouse model of Alzheimer's disease. These findings suggest a new molecular process underlying the pathophysiology of Alzheimer's disease.
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Affiliation(s)
- Sung Hoon Baik
- Department of Biochemistry and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea
| | - Moon-Yong Cha
- Department of Biochemistry and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea
| | - Young-Min Hyun
- Department of Microbiology and Immunology, David H. Smith Center for Vaccine Biology and Immunology, University of Rochester, Rochester, NY, USA
| | - Hansang Cho
- BioMEMS Resource Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Bashar Hamza
- BioMEMS Resource Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Dong Kyu Kim
- Department of Biochemistry and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea
| | - Sun-Ho Han
- Department of Biochemistry and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea
| | - Heesun Choi
- Department of Biochemistry and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea
| | - Kyung Ho Kim
- Department of Biochemistry and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea
| | - Minho Moon
- Department of Biochemistry and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea
| | - Jeewoo Lee
- Department of Pharmacology, College of Pharmacy, Seoul National University, Seoul, Korea
| | - Minsoo Kim
- Department of Biochemistry and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea; Department of Microbiology and Immunology, David H. Smith Center for Vaccine Biology and Immunology, University of Rochester, Rochester, NY, USA
| | - Daniel Irimia
- BioMEMS Resource Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Inhee Mook-Jung
- Department of Biochemistry and Biomedical Sciences, College of Medicine, Seoul National University, Seoul, Korea.
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1803
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Cao Z, Robinson RAS. Proteome characterization of splenocytes from an A
βpp/ps-
1 Alzheimer's disease model. Proteomics 2014; 14:291-7. [DOI: 10.1002/pmic.201300130] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 10/22/2013] [Accepted: 11/21/2013] [Indexed: 12/17/2022]
Affiliation(s)
- Zhiyun Cao
- Department of Chemistry; University of Pittsburgh; Pittsburgh PA USA
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1804
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Intra-hippocampal transplantation of neural precursor cells with transgenic over-expression of IL-1 receptor antagonist rescues memory and neurogenesis impairments in an Alzheimer's disease model. Neuropsychopharmacology 2014; 39:401-14. [PMID: 23954849 PMCID: PMC3870779 DOI: 10.1038/npp.2013.208] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/28/2013] [Accepted: 08/05/2013] [Indexed: 01/08/2023]
Abstract
Ample evidence implicates neuroinflammatory processes in the etiology and progression of Alzheimer's disease (AD). To assess the specific role of the pro-inflammatory cytokine interleukin-1 (IL-1) in AD we examined the effects of intra-hippocampal transplantation of neural precursor cells (NPCs) with transgenic over-expression of IL-1 receptor antagonist (IL-1raTG) on memory functioning and neurogenesis in a murine model of AD (Tg2576 mice). WT NPCs- or sham-transplanted Tg2576 mice, as well as naive Tg2576 and WT mice served as controls. To assess the net effect of IL-1 blockade (not in the context of NPCs transplantation), we also examined the effects of chronic (4 weeks) intra-cerebroventricular (i.c.v.) administration of IL-1ra. We report that 12-month-old Tg2576 mice exhibited increased mRNA expression of hippocampal IL-1β, along with severe disturbances in hippocampal-dependent contextual and spatial memory as well as in neurogenesis. Transplantation of IL-1raTG NPCs 1 month before the neurobehavioral testing completely rescued these disturbances and significantly increased the number of endogenous hippocampal cells expressing the plasticity-related molecule BDNF. Similar, but less-robust effects were also produced by transplantation of WT NPCs and by i.c.v. IL-1ra administration. NPCs transplantation produced alterations in hippocampal plaque formation and microglial status, which were not clearly correlated with the cognitive effects of this procedure. The results indicate that elevated levels of hippocampal IL-1 are causally related to some AD-associated memory disturbances, and provide the first example for the potential use of genetically manipulated NPCs with anti-inflammatory properties in the treatment of AD.
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1805
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Oligomeric amyloid β induces IL-1β processing via production of ROS: implication in Alzheimer's disease. Cell Death Dis 2013; 4:e975. [PMID: 24357806 PMCID: PMC3877570 DOI: 10.1038/cddis.2013.503] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 10/29/2013] [Accepted: 11/12/2013] [Indexed: 12/20/2022]
Abstract
Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by progressive neuronal loss and cognitive decline. Oligomeric amyloid β (oAβ) is involved in the pathogenesis of AD by affecting synaptic plasticity and inhibiting long-term potentiation. Although several lines of evidence suggests that microglia, the resident immune cells in the central nervous system (CNS), are neurotoxic in the development of AD, the mechanism whether or how oAβ induces microglial neurotoxicity remains unknown. Here, we show that oAβ promotes the processing of pro-interleukin (IL)-1β into mature IL-1β in microglia, which then enhances microglial neurotoxicity. The processing is induced by an increase in activity of caspase-1 and NOD-like receptor family, pyrin domain containing 3 (NLRP3) via mitochondrial reactive oxygen species (ROS) and partially via NADPH oxidase-induced ROS. The caspase-1 inhibitor Z-YVAD-FMK inhibits the processing of IL-1β, and attenuates microglial neurotoxicity. Our results indicate that microglia can be activated by oAβ to induce neuroinflammation through processing of IL-1β, a pro-inflammatory cytokine, in AD.
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1806
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Ramaswamy V, Walsh JG, Sinclair DB, Johnson E, Tang-Wai R, Wheatley BM, Branton W, Maingat F, Snyder T, Gross DW, Power C. Inflammasome induction in Rasmussen's encephalitis: cortical and associated white matter pathogenesis. J Neuroinflammation 2013; 10:152. [PMID: 24330827 PMCID: PMC3881507 DOI: 10.1186/1742-2094-10-152] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 11/18/2013] [Indexed: 11/11/2022] Open
Abstract
Background Rasmussen’s encephalitis (RE) is an inflammatory encephalopathy of unknown cause defined by seizures with progressive neurological disabilities. Herein, the pathogenesis of RE was investigated focusing on inflammasome activation in the brain. Methods Patients with RE at the University of Alberta, Edmonton, AB, Canada, were identified and analyzed by neuroimaging, neuropsychological, molecular, and pathological tools. Primary human microglia, astrocytes, and neurons were examined using RT-PCR, enzyme-linked immunosorbent assay (ELISA), and western blotting. Results Four patients with RE were identified at the University of Alberta. Magnetic resonance imaging (MRI) disclosed increased signal intensities in cerebral white matter adjacent to cortical lesions of RE patients, accompanied by a decline in neurocognitive processing speed (P <0.05). CD3ϵ, HLA-DRA, and TNFα together with several inflammasome-associated genes (IL-1β, IL-18, NLRP1, NLRP3, and CASP1) showed increased transcript levels in RE brains compared to non-RE controls (n = 6; P <0.05). Cultured human microglia displayed expression of inflammasome-associated genes and responded to inflammasome activators by releasing IL-1β, which was inhibited by the caspase inhibitor, zVAD-fmk. Major histocompatibility complex (MHC) class II, IL-1β, caspase-1, and alanine/serine/cysteine (ASC) immunoreactivity were increased in RE brain tissues, especially in white matter myeloid cells, in conjunction with mononuclear cell infiltration and gliosis. Neuroinflammation in RE brains was present in both white matter and adjacent cortex with associated induction of inflammasome components, which was correlated with neuroimaging and neuropsychological deficits. Conclusion Inflammasome activation likely contributes to the disease process underlying RE and offers a mechanistic target for future therapeutic interventions.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Christopher Power
- Department of Psychiatry, University of Alberta, Edmonton, AB, Canada.
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1807
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François A, Terro F, Janet T, Rioux Bilan A, Paccalin M, Page G. Involvement of interleukin-1β in the autophagic process of microglia: relevance to Alzheimer's disease. J Neuroinflammation 2013; 10:151. [PMID: 24330807 PMCID: PMC3878742 DOI: 10.1186/1742-2094-10-151] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 11/24/2013] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Autophagy is a major pathway of protein and organelle degradation in the lysosome. Autophagy exists at basal constitutive level and can be induced as a defense mechanism under stress conditions. Molecular relationships between autophagy and inflammation at the periphery were recently evidenced, highlighting a role of autophagy in the regulation of inflammation. Impairment of autophagy (with accumulation of autophagic vacuoles) and substantial inflammation are found in neurodegenerative diseases such as Alzheimer's Disease (AD). However, the links between autophagy and inflammation in AD remain to be determined. METHODS Here, we examined the inflammatory reaction and autophagy in murine tri-cultures of neurons, astrocytes, and microglia. Tri-cultures were exposed to various inflammatory stresses (lipopolysaccharide (LPS), amyloid peptide (Aβ42) with or without cytokines) for 48 hours. Furthermore, the relationships between inflammation and autophagy were also analyzed in astrocyte- and microglia-enriched cultures. Data for multiple variable comparisons were analyzed by a one-way ANOVA followed by a Newman-keuls' test. RESULTS Aβ42 induced a low inflammation without accumulation of acidic vesicles contrary to moderate or severe inflammation induced by LPS or the cytokine cocktail (IL-1β, TNF-α, and IL-6) or IL-1β alone which led to co-localization of p62 and LC3, two markers of autophagy, with acidic vesicles stained with Lyso-ID Red dye. Moreover, the study reveals a major role of IL-1β in the induction of autophagy in tri-cultures in the presence or absence of Aβ42. However, the vulnerability of the autophagic process in purified microglia to IL-1β was prevented by Aβ42. CONCLUSION These findings show a close relationship between inflammation and autophagy, in particular a major role of IL-1β in the induction of the microglial autophagy which could be the case in AD. New therapeutic strategies could target inflammasome and autophagy in microglia to maintain its role in the amyloid immunosurveillance.
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Affiliation(s)
| | | | | | | | | | - Guylène Page
- EA3808 Molecular Targets and Therapeutic of Alzheimer's Disease, University of Poitiers, Poitiers F-86022, France.
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1808
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Šišková Z, Tremblay MÈ. Microglia and synapse: interactions in health and neurodegeneration. Neural Plast 2013; 2013:425845. [PMID: 24392228 PMCID: PMC3874338 DOI: 10.1155/2013/425845] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 09/30/2013] [Accepted: 10/19/2013] [Indexed: 01/04/2023] Open
Abstract
A series of discoveries spanning for the last few years has challenged our view of microglial function, the main form of immune defense in the brain. The surveillance of neuronal circuits executed by each microglial cell overseeing its territory occurs in the form of regular, dynamic interactions. Microglial contacts with individual neuronal compartments, such as dendritic spines and axonal terminals, ensure that redundant or dysfunctional elements are recognized and eliminated from the brain. Microglia take on a new shape that is large and amoeboid when a threat to brain integrity is detected. In this defensive form, they migrate to the endangered sites, where they help to minimize the extent of the brain insult. However, in neurodegenerative diseases that are associated with misfolding and aggregation of synaptic proteins, these vital defensive functions appear to be compromised. Many microglial functions, such as phagocytosis, might be overwhelmed during exposure to the abnormal levels of misfolded proteins in their proximity. This might prevent them from attending to their normal duties, such as the stripping of degenerating synaptic terminals, before neuronal function is irreparably impaired. In these conditions microglia become chronically activated and appear to take on new, destructive roles by direct or indirect inflammatory attack.
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Affiliation(s)
- Zuzana Šišková
- German Center for Neurodegenerative Diseases (DZNE), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
| | - Marie-Ève Tremblay
- Axe Neurosciences, Centre de Recherche du CHU de Québec, Département de Médecine Moléculaire, Université Laval, 2705 Boulevard Laurier, Québec, QC, Canada G1V 4G2
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1809
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He Y, Varadarajan S, Muñoz-Planillo R, Burberry A, Nakamura Y, Núñez G. 3,4-methylenedioxy-β-nitrostyrene inhibits NLRP3 inflammasome activation by blocking assembly of the inflammasome. J Biol Chem 2013; 289:1142-50. [PMID: 24265316 DOI: 10.1074/jbc.m113.515080] [Citation(s) in RCA: 204] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The NLRP3 inflammasome is a critical component of the innate immune system. NLRP3 activation is induced by diverse stimuli associated with bacterial infection or tissue damage, but its inappropriate activation is involved in the pathogenesis of inherited and acquired inflammatory diseases. However, the mechanism by which NLRP3 is activated remains poorly understood. In this study, we explored the role of kinases in NLRP3 inflammasome activation by screening a kinase inhibitor library and identified 3,4-methylenedioxy-β-nitrostyrene (MNS) as an inhibitor for NLRP3 inflammasome activation. Notably, MNS did not affect the activation of the NLRC4 or AIM2 (absent in melanoma 2) inflammasome. Mechanistically, MNS specifically prevented NLRP3-mediated ASC speck formation and oligomerization without blocking potassium efflux induced by NLRP3 agonists. Surprisingly, Syk kinase, the reported target of MNS, did not mediate the inhibitory activity of MNS on NLRP3 inflammasome activation. We also found that the nitrovinyl group of MNS is essential for the inhibitory activity of MNS. Immunoprecipitation, mass spectrometry, and mutation studies suggest that both the nucleotide binding oligomerization domain and the leucine-rich repeat domain of NLRP3 were the intracellular targets of MNS. Administration of MNS also inhibited NLRP3 ATPase activity in vitro, suggesting that MNS blocks the NLRP3 inflammasome by directly targeting NLRP3 or NLRP3-associated complexes. These studies identified a novel chemical probe for studying the molecular mechanism of NLRP3 inflammasome activation which may advance the development of novel strategies to treat diseases associated with abnormal activation of NLRP3 inflammasome.
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Affiliation(s)
- Yuan He
- From the Department of Pathology and Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, Michigan 48109
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1810
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Abstract
Innate immune response pathways and metabolic pathways are evolutionarily conserved throughout species and are fundamental to survival. As such, the regulation of whole-body and cellular metabolism is intimately integrated with immune responses. However, the introduction of new variables to this delicate evolutionarily conserved physiological interaction can lead to deleterious consequences for organisms as a result of inappropriate immune responses. In recent decades, the prevalence and incidence of metabolic diseases associated with obesity have dramatically increased worldwide. As a recently acquired human characteristic, obesity has exposed the critical role of innate immune pathways in multiple metabolic pathophysiological processes. Here, we review recent evidence that highlights inflammasomes as critical sensors of metabolic perturbations in multiple tissues and their role in the progression of highly prevalent metabolic diseases.
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Affiliation(s)
- Jorge Henao-Mejia
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06520;
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1811
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Microglial beclin 1 regulates retromer trafficking and phagocytosis and is impaired in Alzheimer's disease. Neuron 2013; 79:873-86. [PMID: 24012002 DOI: 10.1016/j.neuron.2013.06.046] [Citation(s) in RCA: 285] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/27/2013] [Indexed: 01/13/2023]
Abstract
Phagocytosis controls CNS homeostasis by facilitating the removal of unwanted cellular debris. Accordingly, impairments in different receptors or proteins involved in phagocytosis result in enhanced inflammation and neurodegeneration. While various studies have identified extrinsic factors that modulate phagocytosis in health and disease, key intracellular regulators are less understood. Here we show that the autophagy protein beclin 1 is required for efficient phagocytosis in vitro and in mouse brains. Furthermore, we show that beclin 1-mediated impairments in phagocytosis are associated with dysfunctional recruitment of retromer to phagosomal membranes, reduced retromer levels, and impaired recycling of phagocytic receptors CD36 and Trem2. Interestingly, microglia isolated from human Alzheimer's disease (AD) brains show significantly reduced beclin 1 and retromer protein levels. These findings position beclin 1 as a link between autophagy, retromer trafficking, and receptor-mediated phagocytosis and provide insight into mechanisms by which phagocytosis is regulated and how it may become impaired in AD.
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1812
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Kawana N, Yamamoto Y, Ishida T, Saito Y, Konno H, Arima K, Satoh JI. Reactive astrocytes and perivascular macrophages express NLRP3 inflammasome in active demyelinating lesions of multiple sclerosis and necrotic lesions of neuromyelitis optica and cerebral infarction. ACTA ACUST UNITED AC 2013. [DOI: 10.1111/cen3.12068] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Natsuki Kawana
- Department of Bioinformatics and Molecular Neuropathology; Meiji Pharmaceutical University; Tokyo Japan
| | - Yoji Yamamoto
- Department of Bioinformatics and Molecular Neuropathology; Meiji Pharmaceutical University; Tokyo Japan
| | - Tsuyoshi Ishida
- Department of Pathology and Laboratory Medicine; Kohnodai Hospital; NCGM; Chiba Japan
| | - Yuko Saito
- Department of Laboratory Medicine; National Center Hospital; NCNP; Tokyo Japan
| | - Hidehiko Konno
- Department of Neurology; Nishitaga National Hospital; Sendai Japan
| | - Kunimasa Arima
- Department of Psychiatry; National Center Hospital; NCNP; Tokyo Japan
| | - Jun-ichi Satoh
- Department of Bioinformatics and Molecular Neuropathology; Meiji Pharmaceutical University; Tokyo Japan
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1813
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Gao Y, Ottaway N, Schriever SC, Legutko B, García-Cáceres C, de la Fuente E, Mergen C, Bour S, Thaler JP, Seeley RJ, Filosa J, Stern JE, Perez-Tilve D, Schwartz MW, Tschöp MH, Yi CX. Hormones and diet, but not body weight, control hypothalamic microglial activity. Glia 2013; 62:17-25. [PMID: 24166765 DOI: 10.1002/glia.22580] [Citation(s) in RCA: 185] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 09/02/2013] [Accepted: 09/05/2013] [Indexed: 12/24/2022]
Abstract
The arcuate nucleus (ARC) of the hypothalamus plays a key role in sensing metabolic feedback and regulating energy homeostasis. Recent studies revealed activation of microglia in mice with high-fat diet (HFD)-induced obesity (DIO), suggesting a potential pathophysiological role for inflammatory processes within the hypothalamus. To further investigate the metabolic causes and molecular underpinnings of such glial activation, we analyzed the microglial activity in wild-type (WT), monogenic obese ob/ob (leptin deficient), db/db (leptin-receptor mutation), and Type-4 melanocortin receptor knockout (MC4R KO) mice on either a HFD or on standardized chow (SC) diet. Following HFD exposure, we observed a significant increase in the total number of ARC microglia, immunoreactivity of ionized calcium binding adaptor molecule 1 (iba1-ir), cluster of differentiation 68 (CD68-ir), and ramification of microglial processes. The ob/ob mice had significantly less iba1-ir and ramifications. Leptin replacement rescued these phenomena. The db/db mice had similar iba1-ir comparable with WT mice but had significantly lower CD68-ir and more ramifications than WT mice. After 2 weeks of HFD, ob/ob mice showed an increase of iba1-ir, and db/db mice showed increase of CD68-ir. Obese MC4R KO mice fed a SC diet had comparable iba1-ir and CD68-ir with WT mice but had significantly more ramifications than WT mice. Intriguingly, treatment of DIO mice with glucagon-like peptide-1 receptor agonists reduced microglial activation independent of body weight. Our results show that diet type, adipokines, and gut signals, but not body weight, affect the presence and activity levels of hypothalamic microglia in obesity.
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Affiliation(s)
- Yuanqing Gao
- Institute for Diabetes and Obesity, Helmholtz Centre for Health and Environment and Technische Universität München, Munich, Germany; Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio
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1814
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The microglial sensome revealed by direct RNA sequencing. Nat Neurosci 2013; 16:1896-905. [PMID: 24162652 PMCID: PMC3840123 DOI: 10.1038/nn.3554] [Citation(s) in RCA: 1060] [Impact Index Per Article: 96.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 09/17/2013] [Indexed: 12/11/2022]
Abstract
Microglia, the principal neuroimmune sentinels of the brain, continuously sense changes in their environment and respond to invading pathogens, toxins and cellular debris. Microglia exhibit plasticity and can assume neurotoxic or neuroprotective priming states that determine their responses to danger. We used direct RNA sequencing, without amplification or cDNA synthesis, to determine the quantitative transcriptomes of microglia of healthy adult and aged mice. We validated our findings using fluorescence dual in situ hybridization, unbiased proteomic analysis and quantitative PCR. We found that microglia have a distinct transcriptomic signature and express a unique cluster of transcripts encoding proteins for sensing endogenous ligands and microbes that we refer to as the sensome. With aging, sensome transcripts for endogenous ligand recognition were downregulated, whereas those involved in microbe recognition and host defense were upregulated. In addition, aging was associated with an overall increase in the expression of microglial genes involved in neuroprotection.
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1815
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Shaw AC, Goldstein DR, Montgomery RR. Age-dependent dysregulation of innate immunity. Nat Rev Immunol 2013; 13:875-87. [PMID: 24157572 DOI: 10.1038/nri3547] [Citation(s) in RCA: 716] [Impact Index Per Article: 65.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
As we age, the innate immune system becomes dysregulated and is characterized by persistent inflammatory responses that involve multiple immune and non-immune cell types and that vary depending on the cell activation state and tissue context. This ageing-associated basal inflammation, particularly in humans, is thought to be induced by several factors, including the reactivation of latent viral infections and the release of endogenous damage-associated ligands of pattern recognition receptors (PRRs). Innate immune cell functions that are required to respond to pathogens or vaccines, such as cell migration and PRR signalling, are also impaired in aged individuals. This immune dysregulation may affect conditions associated with chronic inflammation, such as atherosclerosis and Alzheimer's disease.
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Affiliation(s)
- Albert C Shaw
- Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut 06520, USA
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1816
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Innate sensors of pathogen and stress: linking inflammation to obesity. J Allergy Clin Immunol 2013; 132:287-94. [PMID: 23905917 DOI: 10.1016/j.jaci.2013.06.022] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 06/20/2013] [Accepted: 06/21/2013] [Indexed: 12/11/2022]
Abstract
Pathogen and nutrient response pathways are evolutionarily conserved and highly integrated to regulate metabolic and immune homeostasis. Excessive nutrients can be sensed by innate pattern recognition receptors as danger signals either directly or through production of endogenous ligands or modulation of intestinal microbiota. This triggers the activation of downstream inflammatory cascades involving nuclear factor κB and mitogen-activated protein kinase and ultimately induces the production of inflammatory cytokines and immune cell infiltration in various metabolic tissues. The chronic low-grade inflammation in the brain, islet, liver, muscle, and adipose tissue further promotes insulin resistance, energy imbalance, and impaired glucose/lipid metabolism, contributing to the metabolic complications of obesity, such as diabetes and atherosclerosis. In addition, innate pathogen receptors have now emerged as a critical link between the intestinal microbiota and host metabolism. In this review we summarize recent studies demonstrating the important roles of innate pathogen receptors, including Toll-like receptors, nucleotide oligomerization domain containing proteins, and inflammasomes in mediating the inflammatory response to metabolic stress in different tissues and highlight the interaction of innate pattern recognition receptors, gut microbiota, and nutrients during the development of obesity and related metabolic disorders.
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1817
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Zhong Y, Kinio A, Saleh M. Functions of NOD-Like Receptors in Human Diseases. Front Immunol 2013; 4:333. [PMID: 24137163 PMCID: PMC3797414 DOI: 10.3389/fimmu.2013.00333] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 10/02/2013] [Indexed: 12/26/2022] Open
Abstract
Nucleotide-binding and oligomerization domain NOD-like receptors (NLRs) are highly conserved cytosolic pattern recognition receptors that perform critical functions in surveying the intracellular environment for the presence of infection, noxious substances, and metabolic perturbations. Sensing of these danger signals by NLRs leads to their oligomerization into large macromolecular scaffolds and the rapid deployment of effector signaling cascades to restore homeostasis. While some NLRs operate by recruiting and activating inflammatory caspases into inflammasomes, others trigger inflammation via alternative routes including the nuclear factor-κB, mitogen-activated protein kinase, and regulatory factor pathways. The critical role of NLRs in development and physiology is demonstrated by their clear implications in human diseases. Mutations in the genes encoding NLRP3 or NLRP12 lead to hereditary periodic fever syndromes, while mutations in CARD15 that encodes NOD2 are linked to Crohn’s disease or Blau’s syndrome. Genome-wide association studies (GWASs) have identified a number of risk alleles encompassing NLR genes in a host of diseases including allergic rhinitis, multiple sclerosis, inflammatory bowel disease, asthma, multi-bacillary leprosy, vitiligo, early-onset menopause, and bone density loss in elderly women. Animal models have allowed the characterization of underlying effector mechanisms in a number of cases. In this review, we highlight the functions of NLRs in health and disease and discuss how the characterization of their molecular mechanisms provides new insights into therapeutic strategies for the management of inflammatory pathologies.
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Affiliation(s)
- Yifei Zhong
- Department of Microbiology and Immunology, McGill University , Montreal, QC , Canada
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1818
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Tan MS, Yu JT, Jiang T, Zhu XC, Wang HF, Zhang W, Wang YL, Jiang W, Tan L. NLRP3 polymorphisms are associated with late-onset Alzheimer's disease in Han Chinese. J Neuroimmunol 2013; 265:91-5. [PMID: 24144834 DOI: 10.1016/j.jneuroim.2013.10.002] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 10/03/2013] [Indexed: 10/26/2022]
Abstract
The innate immunity and inflammatory response plays an important role in AD pathogenesis. Recently, a wealth of information linking the activation of NLRP3 inflammasome to Alzheimer's disease (AD) pathogenesis has emerged. Considering the pivotal role of NLRP3 in the inflammatory process and in AD, we hypothesized that variations in NLRP3 gene may also affect susceptibility to AD. Three selected functional single-nucleotide polymorphisms (SNPs) in NLRP3 gene (rs2027432, rs10754558, rs35829419) were genotyped in 1133 late-onset AD (LOAD) patients and 1159 healthy controls in a large Northern Han Chinese population. Among them, the 5'-flanking rs2027432 polymorphism seemed to be most associated with LOAD risk even after adjusting for age, gender, and ApoE ε4 status. For rs10754558, the genotype frequency differed significantly only in ApoE ε4 carriers. On the other hand, the minor A allele of rs35829419 (Q705K) polymorphism appeared to exert a protective effect against the development of LOAD. Our data support the notion that genetic variation in NLRP3 gene may contribute to LOAD risk in Northern Han Chinese.
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Affiliation(s)
- Meng-Shan Tan
- Department of Neurology, Qingdao Municipal Hospital, College of Medicine and Pharmaceutics, Ocean University of China, China
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1819
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Abstract
The identification of microglia-associated, neurological disease-causing mutations in patients, combined with studies in mouse models has highlighted microglia, the brain’s intrinsic myeloid cells, as key modulators of pathogenesis and disease progression in neurodegenerative diseases. In Alzheimer’s disease (AD) in particular, the activation and accumulation of microglial cells around b-Amyloid (Ab) plaques has long been described and is believed to result in chronic neuroinflammation—a term that, despite being commonly used, lacks a precise definition. This seemingly directed response of microglia to amyloid deposits conflicts with the fact that the increasing buildup of Ab plaques is not inhibited by these cells during disease progression. While recent evidence suggests that microglia lose their intrinsic beneficial function during the course of AD and may even acquire a ‘‘toxic’’ phenotype over time, Ab may also simply not be an appropriate trigger to induce phagocytosis and degradation by microglia in vivo. As recent experimental evidence has indicated the importance of the microglia in AD pathogenesis, future efforts aimed at tackling this disease via utilization or modulation of microglia or factors therefrom appear to be an exciting and challenging research front.
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1820
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Youm YH, Grant RW, McCabe LR, Albarado DC, Nguyen KY, Ravussin A, Pistell P, Newman S, Carter R, Laque A, Münzberg H, Rosen CJ, Ingram DK, Salbaum JM, Dixit VD. Canonical Nlrp3 inflammasome links systemic low-grade inflammation to functional decline in aging. Cell Metab 2013; 18:519-32. [PMID: 24093676 PMCID: PMC4017327 DOI: 10.1016/j.cmet.2013.09.010] [Citation(s) in RCA: 435] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 07/07/2013] [Accepted: 09/13/2013] [Indexed: 12/20/2022]
Abstract
Despite a wealth of clinical data showing an association between inflammation and degenerative disorders in the elderly, the immune sensors that causally link systemic inflammation to aging remain unclear. Here we detail a mechanism by which the Nlrp3 inflammasome controls systemic low-grade age-related "sterile" inflammation in both periphery and brain independently of the noncanonical caspase-11 inflammasome. Ablation of Nlrp3 inflammasome protected mice from age-related increases in the innate immune activation, alterations in CNS transcriptome, and astrogliosis. Consistent with the hypothesis that systemic low-grade inflammation promotes age-related degenerative changes, the deficient Nlrp3 inflammasome-mediated caspase-1 activity improved glycemic control and attenuated bone loss and thymic demise. Notably, IL-1 mediated only Nlrp3 inflammasome-dependent improvement in cognitive function and motor performance in aged mice. These studies reveal Nlrp3 inflammasome as an upstream target that controls age-related inflammation and offer an innovative therapeutic strategy to lower Nlrp3 activity to delay multiple age-related chronic diseases.
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Affiliation(s)
- Yun-Hee Youm
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - Ryan W. Grant
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - Laura R. McCabe
- Department of Physiology, Michigan State University, East Lansing, MI48824, USA
| | - Diana C. Albarado
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - Kim Yen Nguyen
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - Anthony Ravussin
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - Paul Pistell
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - Susan Newman
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - Renee Carter
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, LSU, Baton Rouge, LA70803, USA
| | - Amanda Laque
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - Heike Münzberg
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - Clifford J. Rosen
- Center for Clinical and Translational Research, Maine Medical Center Research Institute, Scarborough, Maine 04074, USA
| | - Donald K. Ingram
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - J. Michael Salbaum
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
| | - Vishwa Deep Dixit
- Pennington Biomedical Research Center, LSU System, Baton Rouge LA70808, USA
- Section of Comparative Medicine and Department of Immunobiology, Yale University School of Medicine, New Haven, CT06520, USA
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1821
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IPAF inflammasome is involved in interleukin-1β production from astrocytes, induced by palmitate; implications for Alzheimer's Disease. Neurobiol Aging 2013; 35:309-21. [PMID: 24054992 DOI: 10.1016/j.neurobiolaging.2013.08.016] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 07/25/2013] [Accepted: 08/16/2013] [Indexed: 11/23/2022]
Abstract
Inflammatory response has been strongly implicated in the pathogenesis of numerous diseases, including Alzheimer's disease (AD). However, little is known about the molecular mechanisms initiating the generation of inflammatory molecules in the central nervous system, such as interleukin-1β (IL-1β). Previously we identified that palmitate can induce primary astrocytes to produce cytokines, causing AD-like changes in primary neurons. Here we investigated and identified that palmitate induced the activation of ice protease-activating factor (IPAF)-apoptosis-associated speck-like protein containing a caspase activation and recruitment domains (CARD) (ASC) inflammasome in astrocytes leading to the maturation of IL-1β, thereby implicating that not only pathogen-related factors can activate the IPAF-ASC inflammasome. Moreover, downregulating IPAF (which was found to be regulated by cAMP response element-binding protein) in astrocytes through silencing to decrease IL-1β secretion from the astrocytes reduced the generation of amyloid-β42 by primary neurons. Furthermore, the expression levels of IPAF and ASC were found significantly elevated in a subgroup of sporadic AD patients, suggesting an involvement of the IPAF-ASC inflammasome in the inflammatory response associated with AD, and thus could be a potential therapeutic target for AD.
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1822
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Ramanan VK, Saykin AJ. Pathways to neurodegeneration: mechanistic insights from GWAS in Alzheimer's disease, Parkinson's disease, and related disorders. AMERICAN JOURNAL OF NEURODEGENERATIVE DISEASE 2013; 2:145-175. [PMID: 24093081 PMCID: PMC3783830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 08/25/2013] [Indexed: 06/02/2023]
Abstract
The discovery of causative genetic mutations in affected family members has historically dominated our understanding of neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal dementia (FTD), and amyotrophic lateral sclerosis (ALS). Nevertheless, most cases of neurodegenerative disease are not explained by Mendelian inheritance of known genetic variants, but instead are thought to have a complex etiology with numerous genetic and environmental factors contributing to susceptibility. Although unbiased genome-wide association studies (GWAS) have identified novel associations to neurodegenerative diseases, most of these hits explain only modest fractions of disease heritability. In addition, despite the substantial overlap of clinical and pathologic features among major neurodegenerative diseases, surprisingly few GWAS-implicated variants appear to exhibit cross-disease association. These realities suggest limitations of the focus on individual genetic variants and create challenges for the development of diagnostic and therapeutic strategies, which traditionally target an isolated molecule or mechanistic step. Recently, GWAS of complex diseases and traits have focused less on individual susceptibility variants and instead have emphasized the biological pathways and networks revealed by genetic associations. This new paradigm draws on the hypothesis that fundamental disease processes may be influenced on a personalized basis by a combination of variants - some common and others rare, some protective and others deleterious - in key genes and pathways. Here, we review and synthesize the major pathways implicated in neurodegeneration, focusing on GWAS from the most prevalent neurodegenerative disorders, AD and PD. Using literature mining, we also discover a novel regulatory network that is enriched with AD- and PD-associated genes and centered on the SP1 and AP-1 (Jun/Fos) transcription factors. Overall, this pathway- and network-driven model highlights several potential shared mechanisms in AD and PD that will inform future studies of these and other neurodegenerative disorders. These insights also suggest that biomarker and treatment strategies may require simultaneous targeting of multiple components, including some specific to disease stage, in order to assess and modulate neurodegeneration. Pathways and networks will provide ideal vehicles for integrating relevant findings from GWAS and other modalities to enhance clinical translation.
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Affiliation(s)
- Vijay K Ramanan
- Center for Neuroimaging, Department of Radiology and Imaging Sciences, Indiana University School of MedicineIndianapolis, IN, USA
- Department of Medical and Molecular Genetics, Indiana University School of MedicineIndianapolis, IN, USA
- Medical Scientist Training Program, Indiana University School of MedicineIndianapolis, IN, USA
| | - Andrew J Saykin
- Center for Neuroimaging, Department of Radiology and Imaging Sciences, Indiana University School of MedicineIndianapolis, IN, USA
- Department of Medical and Molecular Genetics, Indiana University School of MedicineIndianapolis, IN, USA
- Center for Computational Biology and Bioinformatics, Indiana University School of MedicineIndianapolis, IN, USA
- Indiana Alzheimer Disease Center, Indiana University School of MedicineIndianapolis, IN, USA
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1823
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Abstract
NOD-like receptors (NLRs) are a class of cytoplasmic pattern-recognition receptors. Although most NLRs play some role in immunity, their functions range from regulating antigen presentation (NLRC5, CIITA) to pathogen/damage sensing (NLRP1, NLRP3, NLRC1/2, NLRC4) to suppression or modulation of inflammation (NLRC3, NLRP6, NLRP12, NLRX1). However, NLRP2, NLRP5, and NLRP7 are also involved in non-immune pathways such as embryonic development. In this review, we highlight some of the least well-understood aspects of NLRs, including the mechanisms by which they sense pathogens or damage. NLRP3 recognizes a diverse range of stimuli and numerous publications have presented potential unifying models for NLRP3 activation, but no single mechanism proposed thus far appears to account for all possible NLRP3 activators. Additionally, NLRC3, NLRP6, and NLRP12 inhibit NF-κB activation, but whether direct ligand sensing is a requirement for this function is not known. Herein, we review the various mechanisms of sensing and activation proposed for NLRP3 and other inflammasome activators. We also discuss the role of NLRC3, NLRP6, NLRP12, and NLRX1 as inhibitors and how they are activated and function in their roles to limit inflammation. Finally, we present an overview of the emerging roles that NLRP2, NLRP5, and NLRP7 play during embryonic development and postulate on the potential pathways involved.
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Affiliation(s)
- Christopher Lupfer
- Department of Immunology, St. Jude Children's Research Hospital , Memphis, TN , USA
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1824
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Monsonego A, Nemirovsky A, Harpaz I. CD4 T cells in immunity and immunotherapy of Alzheimer's disease. Immunology 2013; 139:438-46. [PMID: 23534386 DOI: 10.1111/imm.12103] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 03/13/2013] [Accepted: 03/18/2013] [Indexed: 01/09/2023] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia, with prevalence progressively increasing with aging. Pathological hallmarks of the disease include accumulation of amyloid β-protein (Aβ) peptides and neurofibrillary tangles in the brain associated with glial activation and synaptotoxicity. In addition, AD involves peripheral and brain endogenous inflammatory processes that appear to enhance disease progression. More than a decade ago a new therapeutic paradigm emerged for AD, namely the activation of the adaptive immune system directly against the self-peptide Aβ, aimed at lowering its accumulation in the brain. This was the first time that a brain peptide was used to vaccinate human subjects in a manner similar to classic viral or bacterial vaccines. The vaccination approach has taken several forms, from initially active to passive and then back to modified active vaccines. As the first two approaches to date failed to show sufficient efficacy, the last is presently being evaluated in ongoing clinical trials. The present review summarizes the immunogenic characteristics of Aβ in humans and mice and discusses past, present and future Aβ-based immunotherapeutic approaches for AD. We emphasize potential pathogenic and beneficial roles of CD4 T cells in light of the pathogenesis and the general decline in T-cell responsiveness evident in the disease.
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Affiliation(s)
- Alon Monsonego
- The Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
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1825
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Kim EH, Won JH, Hwang I, Yu JW. Cobalt Chloride-induced Hypoxia Ameliorates NLRP3-Mediated Caspase-1 Activation in Mixed Glial Cultures. Immune Netw 2013; 13:141-7. [PMID: 24009541 PMCID: PMC3759711 DOI: 10.4110/in.2013.13.4.141] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 07/15/2013] [Accepted: 07/18/2013] [Indexed: 01/01/2023] Open
Abstract
Hypoxia has been shown to promote inflammation, including the release of proinflammatory cytokines, but it is poorly investigated how hypoxia directly affects inflammasome signaling pathways. To explore whether hypoxic stress modulates inflammasome activity, we examined the effect of cobalt chloride (CoCl2)-induced hypoxia on caspase-1 activation in primary mixed glial cultures of the neonatal mouse brain. Unexpectedly, hypoxia induced by oxygen-glucose deprivation or CoCl2 treatment failed to activate caspase-1 in microglial BV-2 cells and primary mixed glial cultures. Of particular interest, CoCl2-induced hypoxic condition considerably inhibited NLRP3-dependent caspase-1 activation in mixed glial cells, but not in bone marrow-derived macrophages. CoCl2-mediated inhibition of NLRP3 inflammasome activity was also observed in the isolated brain microglial cells, but CoCl2 did not affect poly dA:dT-triggered AIM2 inflammasome activity in mixed glial cells. Our results collectively demonstrate that CoCl2-induced hypoxia may negatively regulate NLRP3 inflammasome signaling in brain glial cells, but its physiological significance remains to be determined.
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Affiliation(s)
- Eun-Hee Kim
- Department of Microbiology, BK 21 project for Medical Science, Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 120-752, Korea
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1826
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Abstract
Acute cerebrovascular disease can affect people at all stages of life, from neonates to the elderly, with devastating consequences. It is responsible for up to 10% of deaths worldwide, is a major cause of disability, and represents an area of real unmet clinical need. Acute cerebrovascular disease is multifactorial with many mechanisms contributing to a complex pathophysiology. One of the major processes worsening disease severity and outcome is inflammation. Pro-inflammatory cytokines of the interleukin (IL)-1 family are now known to drive damaging inflammatory processes in the brain. The aim of this review is to discuss the recent literature describing the role of IL-1 in acute cerebrovascular disease and to provide an update on our current understanding of the mechanisms of IL-1 production. We also discuss the recent literature where the effects of IL-1 have been targeted in animal models, thus reviewing potential future strategies that may limit the devastating effects of acute cerebrovascular disease.
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Affiliation(s)
- James Galea
- Manchester Academic Health Sciences Center, Brain Injury Research Group, Clinical Sciences Building, Salford Royal Foundation Trust, Salford, UK
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1827
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Clark IA, Vissel B. Treatment implications of the altered cytokine-insulin axis in neurodegenerative disease. Biochem Pharmacol 2013; 86:862-71. [PMID: 23939185 DOI: 10.1016/j.bcp.2013.07.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 07/24/2013] [Accepted: 07/25/2013] [Indexed: 11/15/2022]
Abstract
The disappointments of a series of large anti-amyloid trials have brought home the point that until the driving force behind Alzheimer's disease, and the way it causes harm, are firmly established and accepted, researchers will remain ill-equipped to find a way to treat patients successfully. The origin of inflammation in neurodegenerative diseases is still an open question. We champion and expand the argument that a shift in intracellular location of α-synuclein, thereby moving a key methylation enzyme from the nucleus, provides global hypomethylation of patients' cerebral DNA that, through being sensed by TLR9, initiates production of the cytokines that drive these cerebral inflammatory states. After providing a background on the relevant inflammatory cytokines, this commentary then discusses many of the known alternatives to the primary amyloid argument of the pathogenesis of Alzheimer's disease, and the treatment approaches they provide. A key point to appreciate is the weight of evidence that inflammatory cytokines, largely through increasing insulin resistance and thereby reducing the strength of the ubiquitously important signaling mediated by insulin, bring together most of these treatments under development for neurodegenerative disease under the one roof. Moreover, the principles involved apply to a wide range of inflammatory diseases on both sides of the blood brain barrier.
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Affiliation(s)
- Ian A Clark
- Research School of Biology, Australian National University, Canberra, Australia.
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1828
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Affiliation(s)
- Sam Gandy
- Icahn School of Medicine and James J. Peters VA Medical Center, New York, NY 10029, USA.
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1829
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Microglial phenotype and adaptation. J Neuroimmune Pharmacol 2013; 8:807-23. [PMID: 23881706 DOI: 10.1007/s11481-013-9490-4] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Accepted: 07/08/2013] [Indexed: 12/14/2022]
Abstract
Microglia are the prime innate immune cells of the central nervous system. They can transit from a (so-called) resting state under homeostatic conditions towards a pro-inflammatory activation state upon homeostatic disturbances. Under neurodegenerative conditions, microglia have been largely perceived as neurotoxic cells. It is now becoming clear that resting microglia are not inactive but that they serve house-keeping functions. Moreover, microglia activity is not limited to proinflammatory responses, but covers a spectrum of reactive profiles. Depending on the actual situation, activated microglia display specific effector functions supporting inflammation, tissue remodeling, synaptic plasticity and neurogenesis. Many of these functions not only relate to the current state of the local neural environment but also depend on previous experience. In this review, we address microglia functions with respect to determining factors, phenotypic presentations, adaptation to environmental signals and aging. Finally, we point out primary mechanisms of microglia activation, which may comprise therapeutic targets to control neuro-inflammatory and neurodegenerative activity.
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1830
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Selenica MLB, Alvarez JA, Nash KR, Lee DC, Cao C, Lin X, Reid P, Mouton PR, Morgan D, Gordon MN. Diverse activation of microglia by chemokine (C-C motif) ligand 2 overexpression in brain. J Neuroinflammation 2013; 10:86. [PMID: 23866683 PMCID: PMC3726363 DOI: 10.1186/1742-2094-10-86] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 06/24/2013] [Indexed: 11/10/2022] Open
Abstract
Background The chemokine (C-C motif) ligand 2 (CCL2) is a monocyte chemoattractant protein that mediates macrophage recruitment and migration during peripheral and central nervous system (CNS) inflammation. Methods To determine the impact of CCL2 in inflammation in vivo and to elucidate the CCL2-induced polarization of activated brain microglia, we delivered CCL2 into the brains of wild-type mice via recombinant adeno-associated virus serotype 9 (rAAV-9) driven by the chicken β-actin promoter. We measured microglial activation using histological and chemical measurement and recruitment of monocytes using histology and flow cytometry. Results The overexpression of CCL2 in the CNS induced significant activation of brain resident microglia. CD45 and major histocompatibility complex class II immunoreactivity significantly increased at the sites of CCL2 administration. Histological characterization of the microglial phenotype revealed the elevation of “classically activated” microglial markers, such as calgranulin B and IL-1β, as well as markers associated with “alternative activation” of microglia, including YM1 and arginase 1. The protein expression profile in the hippocampus demonstrated markedly increased levels of IL-6, GM-CSF and eotaxin (CCL-11) in response to CCL2, but no changes in the levels of other cytokines, including TNF-α and IFN-γ. Moreover, real-time PCR analysis confirmed increases in mRNA levels of gene transcripts associated with neuroinflammation following CCL2 overexpression. Finally, we investigated the chemotactic properties of CCL2 in vivo by performing adoptive transfer of bone marrow–derived cells (BMDCs) isolated from donor mice that ubiquitously expressed green fluorescent protein. Flow cytometry and histological analyses indicated that BMDCs extravasated into brain parenchyma and colabeled with microglial markers. Conclusion Taken together, our results suggest that CCL2 strongly activates resident microglia in the brain. Both pro- and anti-inflammatory activation of microglia were prominent, with no bias toward the M1 or M2 phenotype in the activated cells. As expected, CCL2 overexpression actively recruited circulating monocytes into the CNS. Thus, CCL2 expression in mouse brain induces microglial activation and represents an efficient method for recruitment of peripheral macrophages.
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Affiliation(s)
- Maj-Linda B Selenica
- Department of Molecular Pharmacology & Physiology, Byrd Alzheimer Institute, University of South Florida, Tampa, FL, USA
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1831
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Salminen A, Kaarniranta K, Kauppinen A, Ojala J, Haapasalo A, Soininen H, Hiltunen M. Impaired autophagy and APP processing in Alzheimer's disease: The potential role of Beclin 1 interactome. Prog Neurobiol 2013; 106-107:33-54. [DOI: 10.1016/j.pneurobio.2013.06.002] [Citation(s) in RCA: 198] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 06/12/2013] [Accepted: 06/18/2013] [Indexed: 12/18/2022]
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1832
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Sheedy FJ, Grebe A, Rayner KJ, Kalantari P, Ramkhelawon B, Carpenter SB, Becker CE, Ediriweera HN, Mullick AE, Golenbock DT, Stuart LM, Latz E, Fitzgerald KA, Moore KJ. CD36 coordinates NLRP3 inflammasome activation by facilitating intracellular nucleation of soluble ligands into particulate ligands in sterile inflammation. Nat Immunol 2013; 14:812-20. [PMID: 23812099 PMCID: PMC3720827 DOI: 10.1038/ni.2639] [Citation(s) in RCA: 667] [Impact Index Per Article: 60.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 05/09/2013] [Indexed: 12/23/2022]
Abstract
Particulate ligands including cholesterol crystals and amyloid fibrils induce NLRP3-dependent production of interleukin-1β (IL-1β) in atherosclerosis, Alzheimer's disease and diabetes. Soluble endogenous ligands including oxidized-LDL, amyloid-β and amylin peptides accumulate in these diseases. Here we identify a CD36-mediated endocytic pathway that coordinates the intracellular conversion of these soluble ligands to crystals or fibrils, resulting in lysosomal disruption and NLRP3-inflammasome activation. Consequently, macrophages lacking CD36 failed to elicit IL-1β production in response to these ligands and targeting CD36 in atherosclerotic mice reduced serum IL-1β and plaque cholesterol crystal accumulation. Collectively, these findings highlight the importance of CD36 in the accrual and nucleation of NLRP3 ligands from within the macrophage and position CD36 as a central regulator of inflammasome activation in sterile inflammation.
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Affiliation(s)
- Frederick J Sheedy
- Department of Medicine, Marc and Ruti Bell Program for Vascular Biology and Disease, The Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, USA
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1833
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Cloonan SM, Choi AMK. Mitochondria: sensors and mediators of innate immune receptor signaling. Curr Opin Microbiol 2013; 16:327-38. [PMID: 23757367 PMCID: PMC6010029 DOI: 10.1016/j.mib.2013.05.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 05/06/2013] [Accepted: 05/13/2013] [Indexed: 12/14/2022]
Abstract
By integrating stress signals with inputs from other cellular organelles, eukaryotic mitochondria are dynamic sensing systems that can confer substantial impact on innate immune signaling in both health and disease. This review highlights recently discovered elements of innate immune receptor signaling (TLR, RLR, NLR, and CLR) associated with mitochondrial function and discusses the role of mitochondria in the initiation and/or manifestation of inflammatory diseases and disorders. We also highlight the role of mitochondria as therapeutic targets for inflammatory disease.
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Affiliation(s)
- Suzanne M Cloonan
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Harvard Medical School, Brigham and Women's Hospital, Boston, MA, USA
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1834
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Golde TE, Streit WJ, Chakrabarty P. Alzheimer's disease risk alleles in TREM2 illuminate innate immunity in Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2013; 5:24. [PMID: 23692967 PMCID: PMC3706774 DOI: 10.1186/alzrt178] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Genetic studies have provided the best evidence for cause and effect relationships in Alzheimer's disease (AD). Indeed, the identification of deterministic mutations in the APP, PSEN1 and PSEN2 genes and subsequent preclinical studies linking these mutations to alterations in Aβ production and aggregation have provided pivotal support for the amyloid cascade hypothesis. In addition, genetic, pathologic and biological studies of APOE have also indicated that the genetic risk for AD associated with APOE4 can be attributed, at least in part, to its pro-amyloidogenic effect on Aβ. In recent years a number of SNPs that show unequivocal genome-wide association with AD risk have implicated novel genetic loci as modifiers of AD risk. However, the functional implications of these genetic associations are largely unknown. For almost all of these associations, the functional variants have not been identified. Very recently, two large consortiums demonstrated that rare variants in the triggering receptor expressed on myeloid cells 2 (TREM2) gene confer significant risk for AD. TREM2 is a type 1 membrane receptor protein primarily expressed on microglia in the central nervous system that has been shown to regulate phagocytosis and activation of monocytes. Previously it had been shown that homozygous loss of function mutations in TREM2 cause polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL, Nasu Hakola disease) and also a pure form of early-onset dementia. The association of TREM2 variants with AD brings innate immune signaling into the light, affirming innate immunity's role as a significant factor in AD pathogenesis.
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Affiliation(s)
- Todd E Golde
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Wolfgang J Streit
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Paramita Chakrabarty
- Center for Translational Research in Neurodegenerative Disease, Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
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1835
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The NLRP3 inflammasome in Alzheimer's disease. Mol Neurobiol 2013; 48:875-82. [PMID: 23686772 DOI: 10.1007/s12035-013-8475-x] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 05/09/2013] [Indexed: 01/12/2023]
Abstract
Innate immunity and inflammatory response plays an important role in the pathogenesis of Alzheimer's disease (AD). As the major resident immune cells in the brain, microglial cells constantly survey the microenvironment and are activated by and recruited to senile plaques. Subsequently, they can phagocytose amyloid-β (Aβ) and secrete pro-inflammatory cytokines that influence the surrounding brain tissue. Recently, a wealth of information linking the microglia-specific activation of NLRP3 inflammasome to AD pathogenesis has emerged. We review here the activation mechanisms of NLRP3 inflammasome in microglia and several downstream effects in the brain, demonstrating that toxic Aβ peptide can light a fire in NLRP3 inflammasome and eventually induce AD pathology and tissue damage. More importantly, it has been demonstrated that inhibition of NLRP3 could largely protect from memory loss and decrease Aβ deposition in AD transgenic mouse model. So, we further discuss the recent advances and challenges in targeting NLRP3 inflammasome for AD therapy.
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Hanisch UK. Functional diversity of microglia - how heterogeneous are they to begin with? Front Cell Neurosci 2013; 7:65. [PMID: 23717262 PMCID: PMC3653062 DOI: 10.3389/fncel.2013.00065] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 04/19/2013] [Indexed: 02/06/2023] Open
Abstract
Microglia serve in the surveillance and maintenance, protection and restoration of the central nervous system (CNS) homeostasis. By their parenchymal location they differ from other CNS-associated myeloid cells, and by origin as well as functional characteristics they are also–at least in part–distinct from extraneural tissue macrophages. Nevertheless, microglia themselves may not comprise a uniform cell type. CNS regions vary by cellular and chemical composition, including white matter (myelin) content, blood–brain barrier properties or prevailing neurotransmitters. Such a micromilieu could instruct as well as require local adaptions of microglial features. Yet even cells within circumscribed populations may reveal some specialization by subtypes, regarding house-keeping duties and functional capacities upon challenges. While diversity of reactive phenotypes has been established still little is known as to whether all activated cells would respond with the same program of induced genes and functions or whether responder subsets have individual contributions. Preferential synthesis of a key cytokine could asign a master control to certain cells among a pool of activated microglia. Critical functions could be sequestered to discrete microglial subtypes in order to avoid interference, such as clearance of endogenous material and presentation of antigens. Indeed, several and especially a number of recent studies provide evidence for the constitutive and reactive heterogeneity of microglia by and within CNS regions. While such a principle of “division of labor” would influence the basic notion of “the” microglia, it could come with the practival value of addressing separate microglia types in experimental and therapeutic manipulations.
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Misgeld T, Lichtenthaler SF, Dichgans M. Between new genetic discoveries and large randomized trials--neurological research in the era of systems medicine. EMBO Rep 2013; 14:489-92. [PMID: 23670197 PMCID: PMC3674454 DOI: 10.1038/embor.2013.70] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The 2012 Eibsee meeting on 'Cellular Mechanisms of Neurodegeneration' addressed the need to integrate research on classical neurodegenerative mechanisms with investigations that relate to the immunological, glial and vascular sequels that accompany and often propagate neuronal injury. We report on the central topics that were addressed and discuss future directions towards establishing 'systems neurology' as a new integrated research field.
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Campbell M, Doyle SL. An eye on the future of inflammasomes and drug development in AMD. J Mol Med (Berl) 2013; 91:1059-70. [PMID: 23661041 DOI: 10.1007/s00109-013-1050-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 04/17/2013] [Accepted: 04/29/2013] [Indexed: 01/07/2023]
Abstract
Age-related macular degeneration (AMD) is the leading cause of central vision loss worldwide. While activation of the immune system has been implicated in disease progression, the pathways involved remain relatively unclear. Typically, inflammatory responses are caused as a result of pathogenic infection. However, in chronic conditions, like AMD, a form of 'sterile' inflammation can exist in localised areas of the body in response to modified host-derived elements and particulate matter accumulation, due to the activation of a complex termed the 'inflammasome'. Inflammasomes control the activity of two major pro-inflammatory cytokines, namely, interleukin (IL)-1β and IL-18, by allowing for their cleavage from inactive pro-forms into mature cytokines. The major pathological hallmark common to both 'dry' and 'wet' AMD is the presence of extracellular deposits, known as drusen, below the retinal pigment epithelium in the macula of the eye. Past studies have shown that host-derived particulate matter such as amyloid deposits and atherosclerotic plaques can be 'sensed' by the NLRP3-inflammasome causing cleavage of pro-IL-1β and pro-IL-18. We have recently reported that the NLRP3-inflammasome can also 'sense' drusen isolated from human AMD donor eyes and that IL-18 protects against the development of choroidal neovascularisation in a model that mimics 'wet' AMD. In fact, since then, a number of studies have reported roles for the NLRP3-inflammasome in AMD. This review will focus on describing, comparing and contrasting these reports and analyzing the potential for manipulating the NLRP3-inflammasome as a therapy for AMD.
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Affiliation(s)
- Matthew Campbell
- Ocular Genetics Unit, Trinity College Dublin, Lincoln Place Gate, Dublin 2, Ireland.
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Di Domizio J, Dorta-Estremera S, Cao W. Methylated BSA mimics amyloid-related proteins and triggers inflammation. PLoS One 2013; 8:e63214. [PMID: 23650555 PMCID: PMC3641125 DOI: 10.1371/journal.pone.0063214] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 04/01/2013] [Indexed: 11/19/2022] Open
Abstract
The mechanistic study of inflammatory or autoimmune diseases requires the generation of mouse models that reproduce the alterations in immune responses observed in patients. Methylated bovine serum albumin (mBSA) has been widely used to induce antigen-specific inflammation in targeted organs or in combination with single stranded DNA (ssDNA) to generate anti-nucleic acids antibodies in vivo. However, the mechanism by which this modified protein triggers inflammation is poorly understood. By analyzing the biochemical properties of mBSA, we found that mBSA exhibits features of an intermediate of protein misfolding pathway. mBSA readily interact with a list of dyes that have binding specificity towards amyloid fibrils. Intriguingly, mBSA displayed cytotoxic activity and its binding to ssDNA further enhanced formation of beta-sheet rich amyloid fibrils. Moreover, mBSA is recognized by the serum amyloid P, a protein unanimously associated with amyloid plaques in vivo. In macrophages, we observed that mBSA disrupted the lysosomal compartment, signaled along the NLRP3 inflammasome pathway, and activated caspase 1, which led to the production of IL-1β. In vivo, mBSA triggered rapid and prominent immune cell infiltration that is dependent on IL-1β induction. Taken together, these data demonstrate that by mimicking amyloidogenic proteins mBSA exhibits strong innate immune functions and serves as a potent adjuvant. These findings advance our understanding on the underlying mechanism of how aberrant immune responses lead to autoimmune reactions.
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Affiliation(s)
- Jeremy Di Domizio
- Department of Immunology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Stephanie Dorta-Estremera
- Department of Immunology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Wei Cao
- Department of Immunology, University of Texas M. D. Anderson Cancer Center, Houston, Texas, United States of America
- * E-mail:
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Qazi O, Parthasarathy PT, Lockey R, Kolliputi N. Can microRNAs keep inflammasomes in check? Front Genet 2013; 4:30. [PMID: 23495355 PMCID: PMC3595571 DOI: 10.3389/fgene.2013.00030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 02/23/2013] [Indexed: 11/16/2022] Open
Affiliation(s)
- Omar Qazi
- Department of Internal Medicine, Division of Allergy and Immunology, Morsani College of Medicine, University of South Florida Tampa, FL, USA
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Fröhlich C, Paarmann K, Steffen J, Stenzel J, Krohn M, Heinze HJ, Pahnke J. Genomic background-related activation of microglia and reduced β-amyloidosis in a mouse model of Alzheimer's disease. Eur J Microbiol Immunol (Bp) 2013; 3:21-27. [PMID: 23814667 DOI: 10.1556/eujmi.3.2013.1.3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Alzheimer's disease (AD) is by far the most common neurodegenerative disease. AD is histologically characterized not only by extracellular senile plaques and vascular deposits consisting of β-amyloid (Aβ) but also by accompanying neuroinflammatory processes involving the brain's microglia. The importance of the microglia is still in controversial discussion, which currently favors a protective function in disease progression. Recent findings by different research groups highlighted the importance of strain-specific and mitochondria-specific genomic variations in mouse models of cerebral β-amyloidosis. Here, we want to summarize our previously presented data and add new results that draw attention towards the consideration of strain-specific genomic alterations in the setting of APP transgenes. We present data from APP-transgenic mice in commonly used C57Bl/6J and FVB/N genomic backgrounds and show a direct influence on the kinetics of Aβ deposition and the activity of resident microglia. Plaque size, plaque deposition rate and the total amount of Aβ are highest in C57Bl/6J mice as compared to the FVB/N genomic background, which can be explained at least partially by a reduced microglia activity towards amyloid deposits in the C57BL/6J strain.
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Affiliation(s)
- Christina Fröhlich
- Neurodegeneration Research Lab (NRL), Department of Neurology, University of Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany
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Gandy S, Haroutunian V, DeKosky ST, Sano M, Schadt EE. CR1 and the "vanishing amyloid" hypothesis of Alzheimer's disease. Biol Psychiatry 2013; 73:393-5. [PMID: 23399469 PMCID: PMC3600375 DOI: 10.1016/j.biopsych.2013.01.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Accepted: 01/07/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Sam Gandy
- Department of Psychiatry and Alzheimer's Disease Research Center, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA.
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Abstract
Recent works have demonstrated a rare functional variant (R47H) in triggering receptor expressed on myeloid cells (TREM) 2 gene, encoding TREM2 protein, increase susceptibility to late-onset Alzheimer's disease (AD), with an odds ratio similar to that of the apolipoprotein E ε4 allele. The reduced function of TREM2 was speculated to be the main cause in the pathogenic effects of this risk variant, and TREM2 is highly expressed in white matter, as well as in the hippocampus and neocortex, which is partly consistent with the pathological features reported in AD brain, indicating the possible involvement of TREM2 in AD pathogenesis. Emerging evidence has demonstrated that TREM2 could suppress inflammatory response by repression of microglia-mediated cytokine production and secretion, which may prevent inflammation-induced bystander damage of neurons. TREM2 also participates in the regulation of phagocytic pathways that are responsible for the removal of neuronal debris. In this article, we review the recent epidemiological findings of TREM2 that related with late-onset AD and speculate the possible roles of TREM2 in progression of this disease. Based on the potential protective actions of TREM2 in AD pathogenesis, targeting TREM2 might provide new opportunities for AD treatment.
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Shi JQ, Zhang CC, Sun XL, Cheng XX, Wang JB, Zhang YD, Xu J, Zou HQ. Antimalarial drug artemisinin extenuates amyloidogenesis and neuroinflammation in APPswe/PS1dE9 transgenic mice via inhibition of nuclear factor-κB and NLRP3 inflammasome activation. CNS Neurosci Ther 2013; 19:262-8. [PMID: 23406388 DOI: 10.1111/cns.12066] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 01/14/2013] [Accepted: 01/14/2013] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND The activation of nuclear factor-kappa B (NF-κB) and NLRP3 inflammasome is involved in neuroinflammation, which is closely linked to Alzheimer's disease (AD). In vivo and in vitro studies have suggested that artemisinin shows antiinflammatory effects in inflammation-related diseases. However, the impacts of artemisinin on AD have not been investigated. AIMS In this study, 5-month-old APPswe/PS1dE9 transgenic mice were treated daily with 40 mg/kg artemisinin for 30 days by intraperitoneal injection to evaluate the effects of artemisinin on AD. RESULTS We found that artemisinin treatment (1) decreased neuritic plaque burden; (2) did not alter Aβ transport across the blood-brain barrier; (3) regulated APP processing via inhibiting β-secretase activity; (4) inhibited NF-κB activity and NALP3 inflammasome activation in APPswe/PS1dE9 double transgenic mice. CONCLUSIONS The in vivo study clearly demonstrates that artemisinin has protective effects on AD pathology due to its effects on suppressing NF-κB activity and NALP3 inflammasome activation. Our study suggests that targeting NF-κB activity and NALP3 inflammasome activation offers a valuable intervention for AD.
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Affiliation(s)
- Jian-Quan Shi
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
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Abstract
Microglia were previously attributed to be vital brain guardians for neuronal survival and synaptic pruning during development as well as for the brain's fight against environmental pathogens. A new report in Nature by the Heneka, Latz and Golenbock groups, however, sheds new light on these distinct myeloid cells by revealing their deadly nature for mature neurons during neurodegeneration.
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Harrison C. Inflammasome activation in Alzheimer's disease. Nat Rev Drug Discov 2013. [DOI: 10.1038/nrd3952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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1847
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