Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 35
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Front Cell Neurosci ; 15: 736120, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34744631

RESUMO

Ribbon synapses of cochlear hair cells undergo pruning and maturation before the hearing onset. In the central nervous system (CNS), synaptic pruning was mediated by microglia, the brain-resident macrophages, via activation of the complement system. Whether a similar mechanism regulates ribbon synapse pruning is currently unknown. In this study, we report that the densities of cochlear macrophages surrounding hair cells were highest at around P8, corresponding well to the completion of ribbon synaptic pruning by P8-P9. Surprisingly, using multiple genetic mouse models, we found that postnatal pruning of the ribbon synapses and auditory functions were unaffected by the knockout of the complement receptor 3 (CR3) or by ablations of macrophages expressing either LysM or Cx3cr1. Our results suggest that unlike microglia in the CNS, macrophages in the cochlea do not mediate pruning of the cochlear ribbon synapses.

2.
Zhongguo Zhong Yao Za Zhi ; 46(2): 391-397, 2021 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-33645127

RESUMO

This paper aims to solve the problems of complicated-unstable test solution preparation process and insufficient extraction of the active ingredient astragaloside Ⅳ in the legal method for the determination of astragaloside Ⅳ in Astragali Radix. The continuous single-factor analysis of seven main factors affecting the content of astragaloside Ⅳ was carried out by HPLC-ELSD, and then the pre-paration method of test solution was optimized. This optimized method exhibited excellent performance in precision, repeatability and stability. The average recovery rate of astragaloside Ⅳ was 99.65% with RSD 2.2%. Astragaloside Ⅳ showed a good linearity between the logarithm of peak area and the logarithm of injection quantity in the range of 0.46-9.1 µg(r=0.999 6). The contents of astragaloside Ⅳ in 29 batches of Astragali Radix were determined by the new and the legal methods. The results showed that the average content of astragaloside Ⅳ in these Astragali Radix samples determined by the former method was 1.458 times than that of the latter one, indicating the new method was simple, reliable and more adequate to extract target compound. According to the results, it is suggested to improve the content standard of astragaloside Ⅳ in Astragali Radix in the new edition of Chinese Pharmacopeia.


Assuntos
Astrágalo (Planta) , Medicamentos de Ervas Chinesas , Saponinas , Triterpenos , Cromatografia Líquida de Alta Pressão , Triterpenos/análise
3.
Biochem Biophys Res Commun ; 533(4): 1148-1154, 2020 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-33046245

RESUMO

BACKGROUND: The underlying mechanism of viral infection as a risk factor for Parkinson's disease (PD), the second most common neurodegenerative disease, remains unclear. OBJECTIVE: We used Mac-1-/- and gp91phox-/- transgene animal models to investigate the mechanisms by which poly I:C, a mimic of virus double-stranded RNA, induces PD neurodegeneration. METHOD: Poly I:C was stereotaxically injected into the substantia nigra (SN) of wild-type (WT), Mac-1-knockout (Mac-1-/-) and gp91 phox-knockout (gp91 phox-/-) mice (10 µg/µl), and nigral dopaminergic neurodegeneration, α-synuclein accumulation and neuroinflammation were evaluated. RESULT: Dopaminergic neurons in the nigra and striatum were markedly reduced in WT mice after administration of poly I:C together with abundant microglial activation in the SN, and the expression of α-synuclein was also elevated. However, these pathological changes were greatly dampened in Mac-1-/- and gp91 phox-/- mice. CONCLUSIONS: Our findings demonstrated that viral infection could result in the activation of microglia as well as NADPH oxidase, which may lead to neuron loss and the development of Parkinson's-like symptoms. Mac-1 is a key receptor during this process.


Assuntos
Neurônios Dopaminérgicos/metabolismo , Neurônios Dopaminérgicos/patologia , Antígeno de Macrófago 1/metabolismo , NADPH Oxidase 2/metabolismo , Doenças Neurodegenerativas/metabolismo , RNA de Cadeia Dupla/toxicidade , Substância Negra/metabolismo , Animais , Morte Celular/genética , Corpo Estriado/citologia , Corpo Estriado/metabolismo , Corpo Estriado/patologia , Neurônios Dopaminérgicos/citologia , Inflamação/metabolismo , Antígeno de Macrófago 1/genética , Masculino , Camundongos , Camundongos Knockout , Microglia/metabolismo , NADPH Oxidase 2/genética , NADPH Oxidases/metabolismo , Doenças Neurodegenerativas/enzimologia , Doenças Neurodegenerativas/genética , RNA de Cadeia Dupla/metabolismo , Substância Negra/citologia , Substância Negra/patologia , alfa-Sinucleína/metabolismo
4.
J Neuroinflammation ; 17(1): 258, 2020 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-32867800

RESUMO

BACKGROUND: Exposure to benzo(a)pyrene (BaP) was associated with cognitive impairments and some Alzheimer's disease (AD)-like pathological changes. However, it is largely unknown whether BaP exposure participates in the disease progression of AD. OBJECTIVES: To investigate the effect of BaP exposure on AD progression and its underlying mechanisms. METHODS: BaP or vehicle was administered to 4-month-old APPswe/PS1dE9 transgenic (APP/PS1) mice and wildtype (WT) mice for 2 months. Learning and memory ability and exploratory behaviors were evaluated 1 month after the initiation/termination of BaP exposure. AD-like pathological and biochemical alterations were examined 1 month after 2-month BaP exposure. Levels of soluble beta-amyloid (Aß) oligomers and the number of Aß plaques in the cortex and the hippocampus were quantified. Gene expression profiling was used to evaluate alternation of genes/pathways associated with AD onset and progression. Immunohistochemistry and Western blot were used to demonstrate neuronal loss and neuroinflammation in the cortex and the hippocampus. Treatment of primary neuron-glia cultures with aged Aß (a mixture of monomers, oligomers, and fibrils) and/or BaP was used to investigate mechanisms by which BaP enhanced Aß-induced neurodegeneration. RESULTS: BaP exposure induced progressive decline in spatial learning/memory and exploratory behaviors in APP/PS1 mice and WT mice, and APP/PS1 mice showed severer behavioral deficits than WT mice. Moreover, BaP exposure promoted neuronal loss, Aß burden and Aß plaque formation in APP/PS1 mice, but not in WT mice. Gene expression profiling showed most robust alteration in genes and pathways related to inflammation and immunoregulatory process, Aß secretion and degradation, and synaptic formation in WT and APP/PS1 mice after BaP exposure. Consistently, the cortex and the hippocampus of WT and APP/PS1 mice displayed activation of microglia and astroglia and upregulation of inducible nitric oxide synthase (iNOS), glial fibrillary acidic protein (GFAP), and NADPH oxidase (three widely used neuroinflammatory markers) after BaP exposure. Furthermore, BaP exposure aggravated neurodegeneration induced by aged Aß peptide in primary neuron-glia cultures through enhancing NADPH oxidase-derived oxidative stress. CONCLUSION: Our study showed that chronic exposure to environmental pollutant BaP induced, accelerated, and exacerbated the progression of AD, in which elevated neuroinflammation and NADPH oxidase-derived oxidative insults were key pathogenic events.


Assuntos
Doença de Alzheimer/patologia , Benzo(a)pireno/toxicidade , Disfunção Cognitiva/induzido quimicamente , Neurônios/efeitos dos fármacos , Placa Amiloide/patologia , Precursor de Proteína beta-Amiloide/genética , Animais , Comportamento Animal/efeitos dos fármacos , Disfunção Cognitiva/patologia , Modelos Animais de Doenças , Comportamento Exploratório/efeitos dos fármacos , Aprendizagem em Labirinto/efeitos dos fármacos , Camundongos , Neurônios/patologia , Presenilina-1/genética , Memória Espacial/efeitos dos fármacos
5.
Int J Mol Sci ; 21(2)2020 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-31940754

RESUMO

Chronic neuroinflammation contributes to the pathogenesis of Parkinson's disease (PD). However, cellular and molecular mechanisms by which chronic neuroinflammation is formed and maintained remain elusive. This study aimed to explore detailed mechanisms by which anti-inflammatory cytokine interleukin-10 (IL-10) prevented chronic neuroinflammation and neurodegeneration. At 24 h after an intranigral injection of lipopolysaccharide (LPS), levels of NLRP3, pro-caspase-1, pro-IL-1ß, active caspase-1, and mature IL-1ß in the midbrain were much higher in IL-10-/- mice than wildtype mice. Mechanistically, IL-10-/- microglia produced more intracellular reactive oxygen species (iROS) and showed more profound activation of NADPH oxidase (NOX2) than wildtype microglia. Meanwhile, suppression of NOX2-derived iROS production blocked LPS-elicited caspase-1 activation and IL-1ß maturation in IL-10-/- microglia in vitro and in vivo. One month after intranigral LPS injection, IL-10-/- mice revealed more profound microglial activation and dopaminergic neurodegeneration in the substantia nigra than wildtype mice. Importantly, such PD-like pathological changes were prevented by IL-1ß neutralization. Collectively, IL-10 inhibited LPS-elicited production of NOX2-derived iROS thereby suppressing synthesis of NLRP3, pro-caspase-1 and pro-IL-1ß and their activation and cleavage. By this mechanism, IL-10 prevented chronic neuroinflammation and neurodegeneration. This study suggested boosting anti-inflammatory effects of IL-10 and suppressing NLRP3 inflammasome activation could be beneficial for PD treatment.


Assuntos
Caspase 1/metabolismo , Neurônios Dopaminérgicos/metabolismo , Interleucina-10/metabolismo , Interleucina-1beta/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Animais , Células Cultivadas , Neurônios Dopaminérgicos/efeitos dos fármacos , Feminino , Interleucina-10/genética , Lipopolissacarídeos/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/efeitos dos fármacos , Microglia/metabolismo , NADPH Oxidase 2/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Substância Negra/citologia , Substância Negra/metabolismo
6.
J Neuroinflammation ; 16(1): 255, 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31805953

RESUMO

BACKGROUND: Metabolic dysfunction and neuroinflammation are increasingly implicated in Parkinson's disease (PD). The pentose phosphate pathway (PPP, a metabolic pathway parallel to glycolysis) converts glucose-6-phosphate into pentoses and generates ribose-5-phosphate and NADPH thereby governing anabolic biosynthesis and redox homeostasis. Brains and immune cells display high activity of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the PPP. A postmortem study reveals dysregulation of G6PD enzyme in brains of PD patients. However, spatial and temporal changes in activity/expression of G6PD in PD remain undetermined. More importantly, it is unclear how dysfunction of G6PD and the PPP affects neuroinflammation and neurodegeneration in PD. METHODS: We examined expression/activity of G6PD and its association with microglial activation and dopaminergic neurodegeneration in multiple chronic PD models generated by an intranigral/intraperitoneal injection of LPS, daily subcutaneous injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 6 days, or transgenic expression of A53T α-synuclein. Primary microglia were transfected with G6PD siRNAs and treated with lipopolysaccharide (LPS) to examine effects of G6PD knockdown on microglial activation and death of co-cultured neurons. LPS alone or with G6PD inhibitor(s) was administrated to mouse substantia nigra or midbrain neuron-glia cultures. While histological and biochemical analyses were conducted to examine microglial activation and dopaminergic neurodegeneration in vitro and in vivo, rotarod behavior test was performed to evaluate locomotor impairment in mice. RESULTS: Expression and activity of G6PD were elevated in LPS-treated midbrain neuron-glia cultures (an in vitro PD model) and the substantia nigra of four in vivo PD models. Such elevation was positively associated with microglial activation and dopaminergic neurodegeneration. Furthermore, inhibition of G6PD by 6-aminonicotinamide and dehydroepiandrosterone and knockdown of microglial G6PD attenuated LPS-elicited chronic dopaminergic neurodegeneration. Mechanistically, microglia with elevated G6PD activity/expression produced excessive NADPH and provided abundant substrate to over-activated NADPH oxidase (NOX2) leading to production of excessive reactive oxygen species (ROS). Knockdown and inhibition of G6PD ameliorated LPS-triggered production of ROS and activation of NF-кB thereby dampening microglial activation. CONCLUSIONS: Our findings indicated that G6PD-mediated PPP dysfunction and neuroinflammation exacerbated each other mediating chronic dopaminergic neurodegeneration and locomotor impairment. Insight into metabolic-inflammatory interface suggests that G6PD and NOX2 are potential therapeutic targets for PD.


Assuntos
Neurônios Dopaminérgicos/metabolismo , Mediadores da Inflamação/metabolismo , Degeneração Neural/metabolismo , Via de Pentose Fosfato/fisiologia , Animais , Células Cultivadas , Técnicas de Cocultura , Neurônios Dopaminérgicos/patologia , Feminino , Técnicas de Silenciamento de Genes , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Camundongos , Camundongos Endogâmicos C57BL , Degeneração Neural/genética , Degeneração Neural/patologia , Gravidez , Ratos , Ratos Endogâmicos F344 , Espécies Reativas de Oxigênio/metabolismo
7.
Toxicol Appl Pharmacol ; 322: 51-59, 2017 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-28283350

RESUMO

BACKGROUND: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. METHODS: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. RESULTS: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100µg/cm2 induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10µg/cm2) and rotenone (2nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91phox, p47phox and p40phox); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47phox and p67phox translocation assembling active NADPH oxidase. CONCLUSION: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to oxidative damage to DA neurons. Our findings delineated the potential role of ultrafine particles alone and in combination with pesticide rotenone in the pathogenesis of PD.


Assuntos
Neurônios Dopaminérgicos/enzimologia , Microglia/enzimologia , NADPH Oxidases/metabolismo , Rotenona/toxicidade , Silicones/toxicidade , Fuligem/toxicidade , Animais , Células Cultivadas , Técnicas de Cocultura , Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/patologia , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/fisiologia , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Microglia/efeitos dos fármacos , Microglia/patologia , Neurônios/efeitos dos fármacos , Neurônios/enzimologia , Neurônios/patologia , Material Particulado , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo
8.
Brain Behav Immun ; 55: 260-272, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27132056

RESUMO

Endotoxin tolerance (ET) is a reduced responsiveness of innate immune cells like macrophages/monocytes to an endotoxin challenge following a previous encounter with the endotoxin. Although ET in peripheral systems has been well studied, little is known about ET in the brain. The present study showed that brain immune cells, microglia, being different from peripheral macrophages, displayed non-cell autonomous mechanisms in ET formation. Specifically, neurons and astroglia were indispensable for microglial ET. Macrophage colony-stimulating factor (M-CSF) secreted from these non-immune cells was essential for governing microglial ET. Neutralization of M-CSF deprived the neuron-glia conditioned medium of its ability to enable microglia to form ET when microglia encountered two lipopolysaccharide (LPS) treatments. Recombinant M-CSF protein rendered enriched microglia refractory to the second LPS challenge leading to microglial ET. Activation of microglial M-CSF receptor (M-CSFR; also known as CSF1R) and the downstream ERK1/2 signals was responsible for M-CSF-mediated microglial ET. Endotoxin-tolerant microglia in neuron-glia cultures displayed M2-like polarized phenotypes, as shown by upregulation of M2 marker Arg-1, elevated production of anti-inflammatory cytokine interleukin 10, and decreased secretion of pro-inflammatory mediators (tumor necrosis factor α, nitric oxide, prostaglandin E2 and interleukin 1ß). Endotoxin-tolerant microglia protected neurons against LPS-elicited inflammatory insults, as shown by reduced neuronal damages in LPS pre-treatment group compared with the group without LPS pre-treatment. Moreover, while neurons and astroglia became injured during chronic neuroinflammation, microglia failed to form ET. Thus, this study identified a distinct non-cell autonomous mechanism of microglial ET. Interactions of M-CSF secreted by neurons and astroglia with microglial M-CSFR programed microglial ET. Loss of microglial ET could be an important pathogenetic mechanism of inflammation-associated neuronal damages.


Assuntos
Astrócitos/metabolismo , Endotoxinas , Inflamação/metabolismo , Sistema de Sinalização das MAP Quinases/fisiologia , Microglia/metabolismo , Neurônios/metabolismo , Neuroproteção/fisiologia , Receptor de Fator Estimulador de Colônias de Macrófagos/metabolismo , Animais , Células Cultivadas , Camundongos , Camundongos Endogâmicos C57BL
9.
Int J Mol Sci ; 15(12): 22604-25, 2014 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-25490140

RESUMO

The variable patterns of DNA methylation in mammals have been linked to a number of physiological processes, including normal embryonic development and disease pathogenesis. Active removal of DNA methylation, which potentially regulates neuronal gene expression both globally and gene specifically, has been recently implicated in neuronal plasticity, learning and memory processes. Model pathways of active DNA demethylation involve ten-eleven translocation (TET) methylcytosine dioxygenases that are dependent on oxidative metabolites. In addition, reactive oxygen species (ROS) and oxidizing agents generate oxidative modifications of DNA bases that can be removed by base excision repair proteins. These potentially link the two processes of active DNA demethylation and mitochondrial oxidative metabolism in post-mitotic neurons. We review the current biochemical understanding of the DNA demethylation process and discuss its potential interaction with oxidative metabolism. We then summarise the emerging roles of both processes and their interaction in neural plasticity and memory formation and the pathophysiology of neurodegeneration. Finally, possible therapeutic approaches for neurodegenerative diseases are proposed, including reprogramming therapy by global DNA demethylation and mitohormesis therapy for locus-specific DNA demethylation in post-mitotic neurons.


Assuntos
Metilação de DNA , Mitocôndrias/genética , Mitocôndrias/metabolismo , Neurônios/metabolismo , Cimentos de Resina , Animais , Citosina/metabolismo , Dioxigenases/metabolismo , Humanos , Aprendizagem/fisiologia , Memória/fisiologia , Mitocôndrias/efeitos dos fármacos , Doenças Neurodegenerativas/tratamento farmacológico , Doenças Neurodegenerativas/genética , Doenças Neurodegenerativas/metabolismo , Oxidantes/metabolismo , Oxidantes/farmacologia , Oxirredução , Espécies Reativas de Oxigênio/metabolismo
10.
Int J Nurs Stud ; 51(3): 458-69, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23850065

RESUMO

OBJECTIVES: The objective of this systematic review and meta-analysis was to estimate the effectiveness of problem-based learning in developing nursing students' critical thinking. DATA SOURCES: Searches of PubMed, EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Proquest, Cochrane Central Register of Controlled Trials (CENTRAL) and China National Knowledge Infrastructure (CNKI) were undertaken to identify randomized controlled trails from 1965 to December 2012, comparing problem-based learning with traditional lectures on the effectiveness of development of nursing students' critical thinking, with no language limitation. The mesh-terms or key words used in the search were problem-based learning, thinking, critical thinking, nursing, nursing education, nurse education, nurse students, nursing students and pupil nurse. REVIEW METHODS: Two reviewers independently assessed eligibility and extracted data. Quality assessment was conducted independently by two reviewers using the Cochrane Collaboration's Risk of Bias Tool. We analyzed critical thinking scores (continuous outcomes) using a standardized mean difference (SMD) or weighted mean difference (WMD) with a 95% confidence intervals (CIs). Heterogeneity was assessed using the Cochran's Q statistic and I(2) statistic. Publication bias was assessed by means of funnel plot and Egger's test of asymmetry. RESULTS: Nine articles representing eight randomized controlled trials were included in the meta-analysis. Most studies were of low risk of bias. The pooled effect size showed problem-based learning was able to improve nursing students' critical thinking (overall critical thinking scores SMD=0.33, 95%CI=0.13-0.52, P=0.0009), compared with traditional lectures. There was low heterogeneity (overall critical thinking scores I(2)=45%, P=0.07) in the meta-analysis. No significant publication bias was observed regarding overall critical thinking scores (P=0.536). Sensitivity analysis showed that the result of our meta-analysis was reliable. Most effect sizes for subscales of the California Critical Thinking Dispositions Inventory (CCTDI) and Bloom's Taxonomy favored problem-based learning, while effect sizes for all subscales of the California Critical Thinking Skills Test (CCTST) and most subscales of the Watson-Glaser Critical Thinking Appraisal (WCGTA) were inconclusive. CONCLUSIONS: The results of the current meta-analysis indicate that problem-based learning might help nursing students to improve their critical thinking. More research with larger sample size and high quality in different nursing educational contexts are required.


Assuntos
Aprendizagem Baseada em Problemas , Estudantes de Enfermagem/psicologia , Pensamento , Humanos
11.
J Immunol ; 190(1): 115-25, 2013 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-23209319

RESUMO

During viral infection, extracellular dsRNA is a potent signaling molecule that activates many innate immune cells, including macrophages. TLR3 is a well-known receptor for extracellular dsRNA, and internalization of extracellular dsRNA is required for endosomal TLR3 activation. Preserved inflammatory responses of TLR3-deficient macrophages to extracellular dsRNA strongly support a TLR3-independent mechanism in dsRNA-mediated immune responses. The present study demonstrated that CD11b/CD18 (Mac-1 [macrophage-1 Ag]), a surface integrin receptor, recognized extracellular dsRNA and induced macrophage immune responses. CD11b deficiency reduced inflammatory cytokine induction elicited by polyinosinic:polycytidylic acid (poly I:C; a synthetic dsRNA) in mouse sera and livers, as well as in cultured peritoneal macrophages. dsRNA-binding assay and confocal immunofluorescence showed that Mac-1, especially the CD11b subunit, interacted and colocalized with poly I:C on the surface of macrophages. Further mechanistic studies revealed two distinct signaling events following dsRNA recognition by Mac-1. First, Mac-1 facilitated poly I:C internalization through the activation of PI3K signaling and enhanced TLR3-dependent activation of IRF3 in macrophages. Second, poly I:C induced activation of phagocyte NADPH oxidase in a TLR3-independent, but Mac-1-dependent, manner. Subsequently, phagocyte NADPH oxidase-derived intracellular reactive oxygen species activated MAPK and NF-κB pathways. Our results indicate that extracellular dsRNA activates Mac-1 to enhance TLR3-dependent signaling and to trigger TLR3-independent, but Mac-1-dependent, inflammatory oxidative signaling, identifying a novel mechanistic basis for macrophages to recognize extracellular dsRNA to regulate innate immune responses. This study identifies Mac-1 as a novel surface receptor for extracellular dsRNA and implicates it as a potential therapeutic target for virus-related inflammatory diseases.


Assuntos
Antígeno CD11b/metabolismo , Antígenos CD18/metabolismo , Espaço Extracelular/genética , Mediadores da Inflamação/fisiologia , Antígeno de Macrófago 1/metabolismo , RNA de Cadeia Dupla/fisiologia , Animais , Antígeno CD11b/genética , Antígenos CD18/genética , Linhagem Celular , Espaço Extracelular/imunologia , Espaço Extracelular/metabolismo , Inflamação/genética , Inflamação/imunologia , Inflamação/metabolismo , Antígeno de Macrófago 1/genética , Macrófagos Peritoneais/enzimologia , Macrófagos Peritoneais/imunologia , Macrófagos Peritoneais/patologia , Masculino , Camundongos , Camundongos Knockout , NADPH Oxidases/deficiência , NADPH Oxidases/genética , NADPH Oxidases/metabolismo , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Receptor 3 Toll-Like
12.
Trends Pharmacol Sci ; 33(6): 295-303, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22503440

RESUMO

Oxidative stress is a key pathologic factor in neurodegenerative diseases such as Alzheimer and Parkinson diseases (AD, PD). The failure of free-radical-scavenging antioxidants in clinical trials pinpoints an urgent need to identify and to block major sources of oxidative stress in neurodegenerative diseases. As a major superoxide-producing enzyme complex in activated phagocytes, phagocyte NADPH oxidase (PHOX) is essential for host defense. However, recent preclinical evidence has underscored a pivotal role of overactivated PHOX in chronic neuroinflammation and progressive neurodegeneration. Deficiency in PHOX subunits mitigates neuronal damage induced by diverse insults/stresses relevant to neurodegenerative diseases. More importantly, suppression of PHOX activity correlates with reduced neuronal impairment in models of neurodegenerative diseases. The discovery of PHOX and non-phagocyte NADPH oxidases in astroglia and neurons further reinforces the crucial role of NADPH oxidases in oxidative stress-mediated chronic neurodegeneration. Thus, proper modulation of NADPH oxidase activity might hold therapeutic potential for currently incurable neurodegenerative diseases.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Inibidores Enzimáticos/farmacologia , Glicoproteínas de Membrana/antagonistas & inibidores , NADPH Oxidases/antagonistas & inibidores , Estresse Oxidativo/efeitos dos fármacos , Doença de Parkinson/tratamento farmacológico , Doença de Alzheimer/metabolismo , Animais , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Astrócitos/enzimologia , Descoberta de Drogas/tendências , Inibidores Enzimáticos/uso terapêutico , Humanos , Glicoproteínas de Membrana/metabolismo , Camundongos , NADPH Oxidase 2 , NADPH Oxidases/metabolismo , Neurônios/enzimologia , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Doença de Parkinson/enzimologia , Fagócitos/enzimologia , Espécies Reativas de Oxigênio/antagonistas & inibidores , Espécies Reativas de Oxigênio/metabolismo , Superóxidos/metabolismo
13.
J Neuroimmune Pharmacol ; 7(1): 187-201, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21870076

RESUMO

Increasing evidence suggests a possible involvement of neuroinflammation in some psychiatric disorders, and also pharmacological reports indicate that anti-inflammatory effects are associated with therapeutic actions of psychoactive drugs, such as anti-depressants and antipsychotics. The purpose of this study was to explore whether clozapine, a widely used antipsychotic drugs, displays anti-inflammatory and neuroprotective effects. Using primary cortical and mesencephalic neuron-glia cultures, we found that clozapine was protective against inflammation-related neurodegeneration induced by lipopolysaccharide (LPS). Pretreatment of cortical or mesencephalic neuron-glia cultures with clozapine (0.1 or 1 µM) for 24 h attenuated LPS-induced neurotoxicity. Clozapine also protected neurons against 1-methyl-4-phenylpyridinium(+) (MPP(+))-induced neurotoxicity, but only in cultures containing microglia, indicating an indispensable role of microglia in clozapine-afforded neuroprotection. Further observation revealed attenuated LPS-induced microglial activation in primary neuron-glia cultures and in HAPI microglial cell line with clozapine pretreatment. Clozapine ameliorated the production of microglia-derived superoxide and intracellular reactive oxygen species (ROS), as well as the production of nitric oxide and TNF-α following LPS. In addition, the protective effect of clozapine was not observed in neuron-glia cultures from mice lacking functional NADPH oxidase (PHOX), a key enzyme for superoxide production in immune cells. Further mechanistic studies demonstrated that clozapine pretreatment inhibited LPS-induced translocation of cytosolic subunit p47(phox) to the membrane in microglia, which was most likely through inhibiting the phosphoinositide 3-kinase (PI3K) pathway. Taken together, this study demonstrates that clozapine exerts neuroprotective effect via the attenuation of microglia activation through inhibition of PHOX-generated ROS production and suggests potential use of antipsychotic drugs for neuroprotection.


Assuntos
Anti-Inflamatórios/farmacologia , Clozapina/farmacologia , Neurônios Dopaminérgicos/efeitos dos fármacos , Inflamação/prevenção & controle , Microglia/efeitos dos fármacos , Animais , Antipsicóticos/farmacologia , Western Blotting , Sobrevivência Celular/efeitos dos fármacos , Técnicas de Cocultura , Neurônios Dopaminérgicos/imunologia , Neurônios Dopaminérgicos/patologia , Citometria de Fluxo , Inflamação/induzido quimicamente , Lipopolissacarídeos/toxicidade , Camundongos , Camundongos Endogâmicos C57BL , Microglia/metabolismo , Microscopia Confocal , Degeneração Neural/induzido quimicamente , Degeneração Neural/prevenção & controle , Fármacos Neuroprotetores/farmacologia , Ratos
14.
Free Radic Biol Med ; 52(2): 303-13, 2012 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-22094225

RESUMO

Rotenone, a widely used pesticide, reproduces parkinsonism in rodents and associates with increased risk for Parkinson disease. We previously reported that rotenone increased superoxide production by stimulating the microglial phagocyte NADPH oxidase (PHOX). This study identified a novel mechanism by which rotenone activates PHOX. Ligand-binding assay revealed that rotenone directly bound to membrane gp91(phox), the catalytic subunit of PHOX; such binding was inhibited by diphenyleneiodonium, a PHOX inhibitor with a binding site on gp91(phox). Functional studies showed that both membrane and cytosolic subunits were required for rotenone-induced superoxide production in cell-free systems, intact phagocytes, and COS7 cells transfected with membrane subunits (gp91(phox)/p22(phox)) and cytosolic subunits (p67(phox) and p47(phox)). Rotenone-elicited extracellular superoxide release in p47(phox)-deficient macrophages suggested that rotenone enabled activation of PHOX through a p47(phox)-independent mechanism. Increased membrane translocation of p67(phox), elevated binding of p67(phox) to rotenone-treated membrane fractions, and coimmunoprecipitation of p67(phox) and gp91(phox) in rotenone-treated wild-type and p47(phox)-deficient macrophages indicated that p67(phox) played a critical role in rotenone-induced PHOX activation via its direct interaction with gp91(phox). Rac1, a Rho-like small GTPase, enhanced p67(phox)-gp91(phox) interaction; Rac1 inhibition decreased rotenone-elicited superoxide release. In conclusion, rotenone directly interacted with gp91(phox); such an interaction triggered membrane translocation of p67(phox), leading to PHOX activation and superoxide production.


Assuntos
Ativação Enzimática/efeitos dos fármacos , Ativadores de Enzimas/farmacologia , Macrófagos Peritoneais/enzimologia , Glicoproteínas de Membrana/metabolismo , NADPH Oxidases/metabolismo , Rotenona/farmacologia , Animais , Células COS , Membrana Celular/enzimologia , Chlorocebus aethiops , Grupo dos Citocromos b/metabolismo , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/metabolismo , Glicoproteínas de Membrana/genética , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microglia/enzimologia , Microglia/metabolismo , NADPH Oxidase 2 , NADPH Oxidases/genética , Neuropeptídeos/metabolismo , Ligação Proteica , Subunidades Proteicas/metabolismo , Transporte Proteico , Ratos , Ratos Endogâmicos F344 , Superóxidos/metabolismo , Proteínas rac de Ligação ao GTP/metabolismo , Proteínas rac1 de Ligação ao GTP
15.
Parkinsonism Relat Disord ; 18 Suppl 1: S213-7, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22166439

RESUMO

Neuroinflammation is closely associated with the pathogenesis of Parkinson's disease (PD) and other neurological disorders. Increasing evidence suggests that inhibition of microglia-mediated neuroinflammation might represent a promising therapeutic potential for PD and related disorders. Fluoxetine, a selective serotonin reuptake inhibitor, is commonly used for the treatment of major depression due to its tolerability and safety profiles. Recent studies have shown that fluoxetine affords robust neuroprotection in a series of neurological disease models. However, the mechanism underlying fluoxetine-mediated neuroprotection remains unclear. Here, by using rat primary midbrain neuronglia cultures, we report that both R and S enantiomers of fluoxetine attenuated chronic neurodegeneration induced by a common inflammogen lipopolysaccharide (LPS) and a neurotoxin 1-methyl-4-phenylpyridinium (MPP(+)). Reconstituted cell culture studies further revealed that microglia were required for fluoxetine-mediated neuroprotection. Fluoxetine significantly inhibited LPS-induced activation of microglia and subsequent release of multiple pro-inflammatory and cytotoxic factors including tumor necrosis factor-α, interleukin-1ß, nitric oxide, and reactive oxygen species. Furthermore, inhibition of microglial NF-κB signaling pathway participated in fluoxetine-mediated neuroprotection. Collectively, fluoxetine exerted neuroprotection against microglia-mediated neurotoxicity. Thus, fluoxetine might hold a potential to retard inflammation-mediated chronic neurodegenerative process of PD.


Assuntos
Fluoxetina/uso terapêutico , Microglia/efeitos dos fármacos , Microglia/metabolismo , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/uso terapêutico , Doença de Parkinson/prevenção & controle , Animais , Células Cultivadas , Feminino , Fluoxetina/farmacologia , Microglia/patologia , NF-kappa B/antagonistas & inibidores , NF-kappa B/metabolismo , Neurônios/metabolismo , Neurônios/patologia , Fármacos Neuroprotetores/farmacologia , Síndromes Neurotóxicas/metabolismo , Síndromes Neurotóxicas/prevenção & controle , Doença de Parkinson/metabolismo , Gravidez , Ratos , Ratos Endogâmicos F344 , Espécies Reativas de Oxigênio/metabolismo
16.
Parkinsons Dis ; 2011: 216298, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21603248

RESUMO

Parkinson's disease (PD) is a neurodegenerative condition characterized by chronic inflammation. Nuclear factor κB (NF-κB) is a family of inducible transcription factors that are expressed in a wide variety of cells and tissues, including microglia, astrocytes, and neurons, and the classical NF-κB pathway plays a key role in the activation and regulation of inflammatory mediator production during inflammation. Activation of the classical NF-κB pathway is mediated through the activity of the IKK kinase complex, which consists of a heterotrimer of IKKα, IKKß, and IKKγ subunits. Targeting NF-κB has been proposed as an approach to the treatment of acute and chronic inflammatory conditions, and the use of inhibitors specific for either IKKß or IKKγ has now been found to inhibit neurodegeneration of TH+ DA-producing neurons in murine and primate models of Parkinson's disease. These studies suggest that targeting the classical pathway of NF-κB through the inhibition of the IKK complex can serve as a useful therapeutic approach to the treatment of PD.

17.
Prog Neurobiol ; 94(1): 1-19, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21439347

RESUMO

Parkinson's disease (PD) is the second most common neurodegenerative disease. The gradual, irreversible loss of dopamine neurons in the substantia nigra is the signature lesion of PD. Clinical symptoms of PD become apparent when 50-60% of nigral dopamine neurons are lost. PD progresses insidiously for 5-7 years (preclinical period) and then continues to worsen even under the symptomatic treatment. To determine what triggers the disease onset and what drives the chronic, self-propelling neurodegenerative process becomes critical and urgent, since lack of such knowledge impedes the discovery of effective treatments to retard PD progression. At present, available therapeutics only temporarily relieve PD symptoms. While the identification of causative gene defects in familial PD uncovers important genetic influences in this disease, the majority of PD cases are sporadic and idiopathic. The current consensus suggests that PD develops from multiple risk factors including aging, genetic predisposition, and environmental exposure. Here, we briefly review research on the genetic and environmental causes of PD. We also summarize very recent genome-wide association studies on risk gene polymorphisms in the emergence of PD. We highlight the new converging evidence on gene-environment interplay in the development of PD with an emphasis on newly developed multiple-hit PD models involving both genetic lesions and environmental triggers.


Assuntos
Meio Ambiente , Predisposição Genética para Doença , Doença de Parkinson/etiologia , Doença de Parkinson/genética , Animais , Modelos Animais de Doenças , Humanos
18.
Environ Health Perspect ; 119(6): 807-14, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21245015

RESUMO

BACKGROUND: Mechanisms whereby gene-environment interactions mediate chronic, progressive neurodegenerative processes in Parkinson's disease (PD)-the second most common neurodegenerative disease-remain elusive. OBJECTIVE: We created a two-hit [neuroinflammation and mutant α-synuclein (α-syn) overexpression] animal model to investigate mechanisms through which mutant α-syn and inflammation work in concert to mediate chronic PD neurodegeneration. METHODS: We used an intraperitoneal injection of the inflammogen lipopolysaccharide (LPS; 3 × 106 EU/kg) to initiate systemic and brain inflammation in wild-type (WT) mice and transgenic (Tg) mice overexpressing human A53T mutant α-syn. We then evaluated nigral dopaminergic neurodegeneration, α-syn pathology, and neuroinflammation. RESULTS: After LPS injection, both WT and Tg mice initially displayed indistinguishable acute neuroinflammation; however, only Tg mice developed persistent neuroinflammation, chronic progressive degeneration of the nigrostriatal dopamine pathway, accumulation of aggregated, nitrated α-syn, and formation of Lewy body-like inclusions in nigral neurons. Further mechanistic studies indicated that 4-week infusion of two inhibitors of inducible nitric oxide synthase and NADPH oxidase, major free radical-generating enzymes in activated microglia, blocked nigral α-syn pathology and neurodegeneration in LPS-injected Tg mice. CONCLUSIONS: Microglia-derived oxidative stress bridged neuroinflammation and α-syn pathogenic alteration in mediating chronic PD progression. Our two-hit animal model involving both a genetic lesion and an environmental trigger reproduced key features of PD and demonstrated synergistic effects of genetic predisposition and environmental exposures in the development of PD. The chronic progressive nature of dopaminergic neurodegeneration, which is absent in most existing PD models, makes this new model invaluable for the study of mechanisms of PD progression.


Assuntos
NADPH Oxidases/antagonistas & inibidores , Degeneração Neural/patologia , Doenças Neurodegenerativas/patologia , Óxido Nítrico Sintase Tipo II/antagonistas & inibidores , Doença de Parkinson/patologia , Substância Negra/patologia , alfa-Sinucleína/metabolismo , Amidinas/farmacologia , Animais , Animais Geneticamente Modificados , Benzilaminas/farmacologia , Modelos Animais de Doenças , Injeções Intraperitoneais , Corpos de Lewy/patologia , Lipopolissacarídeos/imunologia , Lipopolissacarídeos/farmacologia , Camundongos , Degeneração Neural/induzido quimicamente , Degeneração Neural/imunologia , Doenças Neurodegenerativas/induzido quimicamente , Doenças Neurodegenerativas/genética , Doenças Neurodegenerativas/imunologia , Oniocompostos/farmacologia , Estresse Oxidativo , Doença de Parkinson/genética , Doença de Parkinson/imunologia , Substância Negra/imunologia , alfa-Sinucleína/genética
19.
J Neurosci ; 31(3): 1081-92, 2011 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-21248133

RESUMO

What drives the gradual degeneration of dopamine neurons in Parkinson's disease (PD), the second most common neurodegenerative disease, remains elusive. Here, we demonstrated, for the first time, that persistent neuroinflammation was indispensible for such a neurodegenerative process. 1-Methyl-4-phenylpyridinium, lipopolysaccharide (LPS), and rotenone, three toxins often used to create PD models, produced acute but nonprogressive neurotoxicity in neuron-enriched cultures. In the presence of microglia (brain immune cells), these toxins induced progressive dopaminergic neurodegeneration. More importantly, such neurodegeneration was prevented by removing activated microglia. Collectively, chronic neuroinflammation may be a driving force of progressive dopaminergic neurodegeneration. Conversely, ongoing neurodegeneration sustained microglial activation. Microglial activation persisted only in the presence of neuronal damage in LPS-treated neuron-glia cultures but not in LPS-treated mixed-glia cultures. Thus, activated microglia and damaged neurons formed a vicious cycle mediating chronic, progressive neurodegeneration. Mechanistic studies indicated that HMGB1 (high-mobility group box 1), released from inflamed microglia and/or degenerating neurons, bound to microglial Mac1 (macrophage antigen complex 1) and activated nuclear factor-κB pathway and NADPH oxidase to stimulate production of multiple inflammatory and neurotoxic factors. The treatment of microglia with HMGB1 led to membrane translocation of p47(phox) (a cytosolic subunit of NADPH oxidase) and consequent superoxide release, which required the presence of Mac1. Neutralization of HMGB1 and genetic ablation of Mac1 and gp91(phox) (the catalytic submit of NADPH oxidase) blocked the progressive neurodegeneration. Our findings indicated that HMGB1-Mac1-NADPH oxidase signaling axis bridged chronic neuroinflammation and progressive dopaminergic neurodegeneration, thus identifying a mechanistic basis for chronic PD progression.


Assuntos
Proteína HMGB1/metabolismo , Inflamação/metabolismo , Antígeno de Macrófago 1/metabolismo , Microglia/metabolismo , Degeneração Neural/metabolismo , Análise de Variância , Animais , Western Blotting , Contagem de Células , Fracionamento Celular , Células Cultivadas , Técnicas de Cocultura , Dopamina/metabolismo , Inflamação/induzido quimicamente , Inflamação/patologia , Mediadores da Inflamação/metabolismo , Lipopolissacarídeos/farmacologia , Mesencéfalo/citologia , Mesencéfalo/metabolismo , Microglia/citologia , Microglia/patologia , NADPH Oxidases/metabolismo , Degeneração Neural/patologia , Neurônios/citologia , Neurônios/metabolismo , Neurônios/patologia , Ratos , Ratos Endogâmicos F344 , Transdução de Sinais
20.
Mol Pharmacol ; 78(3): 466-77, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20554604

RESUMO

Parkinson's disease (PD) is the second most common neurodegenerative disease characterized by a progressive loss of dopamine (DA) neurons in the substantia nigra. Accumulating evidence indicates that inhibition of microglia-mediated neuroinflammation may become a reliable protective strategy for PD. Resveratrol, a nonflavonoid polyphenol naturally found in red wine and grapes, has been known to possess antioxidant, anticancer, and anti-inflammatory properties. Although recent studies have shown that resveratrol provided neuroprotective effects against ischemia, seizure, and neurodegenerative disorders, the mechanisms underlying its beneficial effects on dopaminergic neurodegeneration are poorly defined. In this study, rat primary midbrain neuron-glia cultures were used to elucidate the molecular mechanisms underlying resveratrol-mediated neuroprotection. The results clearly demonstrated that resveratrol protected DA neurons against lipopolysaccharide (LPS)-induced neurotoxicity in concentration- and time-dependent manners through the inhibition of microglial activation and the subsequent reduction of proinflammatory factor release. Mechanistically, resveratrol-mediated neuroprotection was attributed to the inhibition of NADPH oxidase. This conclusion is supported by the following observations. First, resveratrol reduced NADPH oxidase-mediated generation of reactive oxygen species. Second, LPS-induced translocation of NADPH oxidase cytosolic subunit p47 to the cell membrane was significantly attenuated by resveratrol. Third and most importantly, resveratrol failed to exhibit neuroprotection in cultures from NADPH oxidase-deficient mice. Furthermore, this neuroprotection was also related to an attenuation of the activation of mitogen-activated protein kinases and nuclear factor-kappaB signaling pathways in microglia. These findings suggest that resveratrol exerts neuroprotection against LPS-induced dopaminergic neurodegeneration, and NADPH oxidase may be a major player in resveratrol-mediated neuroprotection.


Assuntos
Neurônios/efeitos dos fármacos , Animais , Anti-Inflamatórios/metabolismo , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Dopamina/metabolismo , Dopamina/farmacologia , Dopamina/fisiologia , Embrião de Mamíferos , Feminino , Flavonoides/metabolismo , Flavonoides/farmacologia , Flavonoides/uso terapêutico , Lipopolissacarídeos/antagonistas & inibidores , Lipopolissacarídeos/metabolismo , Lipopolissacarídeos/farmacologia , Mesencéfalo/citologia , Mesencéfalo/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Microglia/efeitos dos fármacos , Microglia/metabolismo , Microglia/fisiologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/farmacologia , NADPH Oxidases/antagonistas & inibidores , NADPH Oxidases/metabolismo , NADPH Oxidases/fisiologia , Degeneração Neural/metabolismo , Degeneração Neural/prevenção & controle , Neuroglia/efeitos dos fármacos , Neuroglia/metabolismo , Neurônios/metabolismo , Neurônios/fisiologia , Fármacos Neuroprotetores/metabolismo , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Síndromes Neurotóxicas/metabolismo , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/metabolismo , Fenóis/metabolismo , Fenóis/farmacologia , Fenóis/uso terapêutico , Polifenóis , Gravidez , Ratos , Ratos Endogâmicos F344 , Espécies Reativas de Oxigênio/metabolismo , Espécies Reativas de Oxigênio/farmacologia , Espécies Reativas de Oxigênio/uso terapêutico , Resveratrol
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...