51
|
Lechpammer M, Manning SM, Samonte F, Nelligan J, Sabo E, Talos DM, Volpe JJ, Jensen FE. Minocycline treatment following hypoxic/ischaemic injury attenuates white matter injury in a rodent model of periventricular leucomalacia. Neuropathol Appl Neurobiol 2008; 34:379-93. [PMID: 18221261 DOI: 10.1111/j.1365-2990.2007.00925.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
AIMS Periventricular white matter injury in premature infants occurs following hypoxia/ischaemia and systemic infection, and results in hypomyelination, as well as neuromotor and cognitive deficits later in life. Inflammatory infiltrates are seen within human cerebral white matter from periventricular leucomalacia (PVL) cases. METHODS In this study, we examine the time course of CD-68+ microglial cell responses relative to cell death within white matter following hypoxia/ischaemia in a rat model of PVL. We also tested the efficacy of the minocycline, an agent that suppresses microglial activation, in this model when administered as a post-insult treatment. RESULTS We show that preoligodendrocyte injury in the post-natal day 6 begins within 24 h and continues for 48-96 h after hypoxia/ischaemia, and that microglial responses occur primarily over the first 96 h following hypoxia/ischaemia. Minocycline treatment over this 96 h time window following the insult resulted in significant protection against white matter injury, and this effect was concomitant with a reduction in CD-68+ microglial cell numbers. CONCLUSIONS These results suggest that anti-inflammatory treatments may represent a useful strategy in the treatment of PVL, where clinical conditions would favour a post-insult treatment strategy.
Collapse
Affiliation(s)
- M Lechpammer
- Department of Neurology, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | | | | | | | | | | | | | | |
Collapse
|
52
|
Candelario-Jalil E, de Oliveira ACP, Gräf S, Bhatia HS, Hüll M, Muñoz E, Fiebich BL. Resveratrol potently reduces prostaglandin E2 production and free radical formation in lipopolysaccharide-activated primary rat microglia. J Neuroinflammation 2007; 4:25. [PMID: 17927823 PMCID: PMC2100038 DOI: 10.1186/1742-2094-4-25] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 10/10/2007] [Indexed: 01/22/2023] Open
Abstract
Background Neuroinflammatory responses are triggered by diverse ethiologies and can provide either beneficial or harmful results. Microglial cells are the major cell type involved in neuroinflammation, releasing several mediators, which contribute to the neuronal demise in several diseases including cerebral ischemia and neurodegenerative disorders. Attenuation of microglial activation has been shown to confer protection against different types of brain injury. Recent evidence suggests that resveratrol has anti-inflammatory and potent antioxidant properties. It has been also shown that resveratrol is a potent inhibitor of cyclooxygenase (COX)-1 activity. Previous findings have demonstrated that this compound is able to reduce neuronal injury in different models, both in vitro and in vivo. The aim of this study was to examine whether resveratrol is able to reduce prostaglandin E2 (PGE2) and 8-iso-prostaglandin F2α (8-iso-PGF2α) production by lipopolysaccharide (LPS)-activated primary rat microglia. Methods Primary microglial cell cultures were prepared from cerebral cortices of neonatal rats. Microglial cells were stimulated with 10 ng/ml of LPS in the presence or absence of different concentrations of resveratrol (1–50 μM). After 24 h incubation, culture media were collected to measure the production of PGE2 and 8-iso-PGF2α using enzyme immunoassays. Protein levels of COX-1, COX-2 and microsomal prostaglandin E synthase-1 (mPGES-1) were studied by Western blotting after 24 h of incubation with LPS. Expression of mPGES-1 at the mRNA level was investigated using reverse transcription-polymerase chain reaction (RT-PCR) analysis. Results Our results indicate that resveratrol potently reduced LPS-induced PGE2 synthesis and the formation of 8-iso-PGF2α, a measure of free radical production. Interestingly, resveratrol dose-dependently reduced the expression (mRNA and protein) of mPGES-1, which is a key enzyme responsible for the synthesis of PGE2 by activated microglia, whereas resveratrol did not affect the expression of COX-2. Resveratrol is therefore the first known inhibitor which specifically prevents mPGES-1 expression without affecting COX-2 levels. Another important observation of the present study is that other COX-1 selective inhibitors (SC-560 and Valeroyl Salicylate) potently reduced PGE2 and 8-iso-PGF2α production by LPS-activated microglia. Conclusion These findings suggest that the naturally occurring polyphenol resveratrol is able to reduce microglial activation, an effect that might help to explain its neuroprotective effects in several in vivo models of brain injury.
Collapse
Affiliation(s)
- Eduardo Candelario-Jalil
- Neurochemistry Research Group, Department of Psychiatry, University of Freiburg Medical School, Hauptstrasse 5, D-79104 Freiburg, Germany.
| | | | | | | | | | | | | |
Collapse
|
53
|
Annaházi A, Mracskó E, Süle Z, Karg E, Penke B, Bari F, Farkas E. Pre-treatment and post-treatment with α-tocopherol attenuates hippocampal neuronal damage in experimental cerebral hypoperfusion. Eur J Pharmacol 2007; 571:120-8. [PMID: 17597609 DOI: 10.1016/j.ejphar.2007.05.048] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2007] [Revised: 05/27/2007] [Accepted: 05/29/2007] [Indexed: 11/24/2022]
Abstract
Alpha-tocopherol, a potent antioxidant, has been widely investigated as a dietary supplement with which to reduce the risk of atherosclerosis, and has recently been considered as a potential supplement to moderate oxidative neuronal damage in Alzheimer's disease patients. Since alpha-tocopherol appears beneficial in vascular and neurodegenerative disorders, we set out to identify its neuroprotective action in a rat model of chronic cerebral hypoperfusion-induced brain injury. The bilateral common carotid arteries of male Wistar rats were permanently occluded (2VO). Sham-operated animals served as controls. Half of the animals were pre- or post-treated repeatedly with alpha-tocopherol (5x100 mg/kg daily, i.p.), the other half receiving only soybean oil, the alpha-tocopherol vehicle. One week after the onset of 2VO, the spatial learning capacity of the animals was assessed in the Morris water maze. After testing, hippocampal slices were stained with cresyl violet in order to examine the pyramidal cell layer integrity. The density of microtubule-associated protein-2 (MAP-2)-positive dendrites and the OX-42-labeled microglial activation level were determined immunocytochemically. Finally, alpha-tocopherol was determined in the peripheral tissues, blood and brain. Alpha-tocopherol moderated the 2VO-induced learning impairment. The various forms of alpha-tocopherol treatment, and particularly the post-treatment, prevented the 2VO-induced pyramidal cell death and the activation of microglia in the hippocampus CA1 region, and the degeneration of MAP-2-positive dendrites in the CA3 region. The alpha-tocopherol concentration was elevated in the peripheral tissues and the blood, but not in the brain. The data indicate that alpha-tocopherol, particularly when administered as post-treatment, is neuroprotective in chronic cerebral hypoperfusion.
Collapse
Affiliation(s)
- Anita Annaházi
- Department of Physiology, School of Medicine, University of Szeged, Szeged, Hungary
| | | | | | | | | | | | | |
Collapse
|
54
|
Woster AP, Combs CK. Differential ability of a thiazolidinedione PPARgamma agonist to attenuate cytokine secretion in primary microglia and macrophage-like cells. J Neurochem 2007; 103:67-76. [PMID: 17573821 DOI: 10.1111/j.1471-4159.2007.04706.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists are known to inhibit select pro-inflammatory changes in models of CNS and systemic inflammation. Recent reports suggest that these anti-inflammatory effects are due to mechanisms other than canonical nuclear receptor-mediated transcriptional alteration. Using primary microglia and the monocytic cell line, THP-1, we demonstrate that rosiglitazone, a PPARgamma-activating thiazolidinedione, decreases pro-inflammatory cytokine secretion as measured by ELISA. Cells were pre-treated with various thiazolidinediones, including rosiglitazone, prior to stimulation with lipopolysaccharide or phorbol 12-myristate 13-acetate (PMA) to stimulate cytokine production. Tumor necrosis factor alpha (TNFalpha) secretion was significantly inhibited in both primary microglia and THP-1 cells differentiated for 72 h in the presence of PMA to induce a macrophage-like phenotype. No reduction in TNFalpha secretion was observed in undifferentiated THP-1 cells with rosiglitazone pre-treatment. Electrophoretic mobility shift assay revealed no significant difference in PPARgamma activation between PMA-differentiated and undifferentiated THP-1 cells. When PMA-differentiated and undifferentiated THP-1 cells were treated with the irreversible PPARgamma antagonist, GW 9662, a significant, dose-dependent decrease in TNFalpha secretion was observed. These results suggest that the anti-inflammatory benefit of PPARgamma ligands occur independently of classical PPARgamma activation.
Collapse
Affiliation(s)
- Andrew P Woster
- Department of Pharmacology, Physiology & Therapeutics, University of North Dakota, School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | | |
Collapse
|
55
|
Abstract
Nuclear factor (NF-kappaB)(1) is a eukaryotic transcription factor that may be activated by oxidative stress. Because of this hypothesis, the effect of vitamin E on NF-kappaB activation has been examined in many studies, using both in vivo and in vitro models. Most of these studies have observed that vitamin E inhibits the activation of NF-kappaB, with the greatest inhibition seen with the succinate form. Vitamin E may be inhibiting NF-kappaB by reducing oxidative stress or through one of its nonantioxidant functions; this is not clear at the present time. It also is not known if the inhibition of NF-kappaB is necessary for any of vitamin E's effects on gene expression and the resulting physiological effects.
Collapse
Affiliation(s)
- Howard P Glauert
- Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, Kentucky 40506, USA
| |
Collapse
|
56
|
Wilkinson BL, Landreth GE. The microglial NADPH oxidase complex as a source of oxidative stress in Alzheimer's disease. J Neuroinflammation 2006; 3:30. [PMID: 17094809 PMCID: PMC1637099 DOI: 10.1186/1742-2094-3-30] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Accepted: 11/09/2006] [Indexed: 01/16/2023] Open
Abstract
Alzheimer's disease is the most common cause of dementia in the elderly, and manifests as progressive cognitive decline and profound neuronal loss. The principal neuropathological hallmarks of Alzheimer's disease are the senile plaques and the neurofibrillary tangles. The senile plaques are surrounded by activated microglia, which are largely responsible for the proinflammatory environment within the diseased brain. Microglia are the resident innate immune cells in the brain. In response to contact with fibrillar beta-amyloid, microglia secrete a diverse array of proinflammatory molecules. Evidence suggests that oxidative stress emanating from activated microglia contribute to the neuronal loss characteristic of this disease. The source of fibrillar beta-amyloid induced reactive oxygen species is primarily the microglial nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. The NADPH oxidase is a multicomponent enzyme complex that, upon activation, produces the highly reactive free radical superoxide. The cascade of intracellular signaling events leading to NADPH oxidase assembly and the subsequent release of superoxide in fibrillar beta-amyloid stimulated microglia has recently been elucidated. The induction of reactive oxygen species, as well as nitric oxide, from activated microglia can enhance the production of more potent free radicals such as peroxynitrite. The formation of peroxynitrite causes protein oxidation, lipid peroxidation and DNA damage, which ultimately lead to neuronal cell death. The elimination of beta-amyloid-induced oxidative damage through the inhibition of the NADPH oxidase represents an attractive therapeutic target for the treatment of Alzheimer's disease.
Collapse
Affiliation(s)
- Brandy L Wilkinson
- Alzheimer Laboratory, Department of Neuroscience, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Gary E Landreth
- Alzheimer Laboratory, Department of Neuroscience, Case Western Reserve University, Cleveland, OH 44106, USA
| |
Collapse
|
57
|
Lee SY, Son DJ, Lee YK, Lee JW, Lee HJ, Yun YW, Ha TY, Hong JT. Inhibitory effect of sesaminol glucosides on lipopolysaccharide-induced NF-κB activation and target gene expression in cultured rat astrocytes. Neurosci Res 2006; 56:204-12. [PMID: 16842873 DOI: 10.1016/j.neures.2006.06.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2005] [Accepted: 04/12/2006] [Indexed: 11/24/2022]
Abstract
The inflammatory reaction plays an important role in the pathogenesis of the neurodegenerative disorder including Alzheimer's disease (AD). Sesame lignan compounds such as sesaminol glucosides (SG) exhibit a range of pharmacological activities including anti-oxidative and anti-inflammatory action. In this study, we tried to elucidate possible effects of SG on lipopolysaccharide (LPS)-induced inflammatory reaction and its underlying mechanism in cultured astrocytes. SG (10-100 microg/ml) inhibited LPS-induced generation of nitric oxide (NO) and reactive oxygen species (ROS), as well as inhibited LPS-induced cytosolic phospholipase A2 (cPLA2), cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) expression dose-dependently. This inhibitory effect of SG on NO and ROS generation was enforced by addition of glutathione (GSH) in culture. In addition, SG prevented LPS-induced DNA binding and transcriptional activity of nuclear factor KappaB (NF)-kappaB. Consistent with the inhibitory effect on NF-kappaB activity, SG inhibits phosphorylation and degradation of inhibitory KappaB (IkappaB), thereby translocation of p50 of NF-kappaB. These data show that SG has an anti-inflammatory effect through inhibition of NF-kappaB, and may be a useful agent for prevention of inflammatory disease like AD.
Collapse
Affiliation(s)
- Sun Young Lee
- College of Pharmacy, Chungbuk National University, Cheongju, Chungbuk 361-763, Republic of Korea
| | | | | | | | | | | | | | | |
Collapse
|
58
|
Jung KK, Lee HS, Cho JY, Shin WC, Rhee MH, Kim TG, Kang JH, Kim SH, Hong S, Kang SY. Inhibitory effect of curcumin on nitric oxide production from lipopolysaccharide-activated primary microglia. Life Sci 2006; 79:2022-31. [PMID: 16934299 DOI: 10.1016/j.lfs.2006.06.048] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 06/20/2006] [Accepted: 06/26/2006] [Indexed: 10/24/2022]
Abstract
Curcumin has been shown to exhibit anti-inflammatory, antimutagenic, and anticarcinogenic activities. However, the modulatory effect of curcumin on the functional activation of primary microglial cells, brain mononuclear phagocytes causing the neuronal damage, largely remains unknown. The current study examined whether curcumin influenced NO production in rat primary microglia and investigated its underlying signaling pathways. Curcumin decreased NO production in LPS-stimulated microglial cells in a dose-dependent manner, with an IC(50) value of 3.7 microM. It also suppressed both mRNA and protein levels of inducible nitric oxide synthase (iNOS), indicating that this drug may affect iNOS gene expression process. Indeed, curcumin altered biochemical patterns induced by LPS such as phosphorylation of all mitogen-activated protein kinases (MAPKs), and DNA binding activities of nuclear factor-kappaB (NF-kappaB) and activator protein (AP)-1, assessed by reporter gene assay. By analysis of inhibitory features of specific MAPK inhibitors, a series of signaling cascades including c-Jun N-terminal kinase (JNK), p38 and NF-kappaB was found to play a critical role in curcumin-mediated NO inhibition in microglial cells. The current results suggest that curcumin is a promising agent for the prevention and treatment of both NO and microglial cell-mediated neurodegenerative disorders.
Collapse
Affiliation(s)
- Ki Kyung Jung
- Pharmacology Department, National Institute of Toxicological Research, KFDA, Seoul 122-704, Republic of Korea
| | | | | | | | | | | | | | | | | | | |
Collapse
|
59
|
Nedzvetsky VS, Tuzcu M, Yasar A, Tikhomirov AA, Baydas G. Effects of vitamin E against aluminum neurotoxicity in rats. BIOCHEMISTRY (MOSCOW) 2006; 71:239-44. [PMID: 16545059 DOI: 10.1134/s0006297906030023] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The present study examined the protective effects of vitamin E against aluminum-induced neurotoxicity in rats. Wistar rats were given daily aluminum via their drinking water containing 1600 mg/liter aluminum chloride for six weeks. Aluminum induced a significant increase in lipid peroxidation (LPO) in hippocampus and frontal cortex. Furthermore, aluminum caused marked elevation in the levels of the glial markers (glial fibrillary acidic protein (GFAP) and S100B) and proinflammatory cytokines (TNF-alpha and IL-1beta) in both brain areas. Vitamin E treatment reduced the contents of glial markers and cytokines and the levels of LPO. In conclusion, this study demonstrates that vitamin E ameliorates glial activation and reduces release of proinflammatory cytokines induced by aluminum.
Collapse
Affiliation(s)
- V S Nedzvetsky
- Department of Biophysics and Biochemistry, Faculty of Biology, Dnepropetrovsk National University, Ukraine.
| | | | | | | | | |
Collapse
|
60
|
Sriram K, Miller DB, O'Callaghan JP. Minocycline attenuates microglial activation but fails to mitigate striatal dopaminergic neurotoxicity: role of tumor necrosis factor-alpha. J Neurochem 2006; 96:706-18. [PMID: 16405514 DOI: 10.1111/j.1471-4159.2005.03566.x] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Activated microglia are implicated in the pathogenesis of disease-, trauma- and toxicant-induced damage to the CNS, and strategies to modulate microglial activation are gaining impetus. A novel action of the tetracycline derivative minocycline is the ability to inhibit inflammation and free radical formation, factors that influence microglial activation. Minocycline is therefore being tested as a neuroprotective agent to alleviate CNS damage, although findings so far have yielded mixed results. Here, we showed that administration of a single low dose of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or methamphetamine (METH), a paradigm that causes selective degeneration of striatal dopaminergic nerve terminals without affecting the cell body in substantia nigra, increased the expression of mRNAs encoding microglia-associated factors F4/80, interleukin (IL)-1alpha, IL-6, monocyte chemoattractant protein-1 (MCP-1, CCL2) and tumor necrosis factor (TNF)-alpha. Minocycline treatment attenuated MPTP- or METH-mediated microglial activation, but failed to afford neuroprotection. Lack of neuroprotection was shown to be due to the inability of minocycline to abolish the induction of TNF-alpha and its receptors, thereby failing to modulate TNF signaling. Thus, TNF-alpha appeared to be an obligatory component of dopaminergic neurotoxicity. To address this possibility, we examined the effects of MPTP or METH in mice lacking genes encoding IL-6, CCL2 or TNF receptor (TNFR)1/2. Deficiency of either IL-6 or CCL2 did not alter MPTP neurotoxicity. However, deficiency of both TNFRs protected against the dopaminergic neurotoxicity of MPTP. Taken together, our findings suggest that attenuation of microglial activation is insufficient to modulate neurotoxicity as transient activation of microglia may suffice to initiate neurodegeneration. These findings support the hypothesis that TNF-alpha may play a role in the selective vulnerability of the nigrostriatal pathway associated with dopaminergic neurotoxicity and perhaps Parkinson's disease.
Collapse
MESH Headings
- 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine/pharmacology
- 3,4-Dihydroxyphenylacetic Acid/metabolism
- Animals
- Blotting, Western/methods
- Cell Count/methods
- Chemokine CCL2/genetics
- Chromatography, High Pressure Liquid/methods
- Corpus Striatum/cytology
- Dopamine/metabolism
- Dopamine Agents/toxicity
- Dose-Response Relationship, Drug
- Drug Interactions
- Glial Fibrillary Acidic Protein/metabolism
- Homovanillic Acid/metabolism
- Interleukin-6/genetics
- Male
- Methamphetamine/toxicity
- Mice
- Mice, Mutant Strains
- Microglia/drug effects
- Minocycline/pharmacology
- Neurons/drug effects
- Neurons/metabolism
- Receptors, Tumor Necrosis Factor/genetics
- Receptors, Tumor Necrosis Factor/physiology
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Time Factors
- Tyrosine 3-Monooxygenase/metabolism
Collapse
Affiliation(s)
- Krishnan Sriram
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA
| | | | | |
Collapse
|
61
|
Flanary BE, Streit WJ. Alpha-tocopherol (vitamin E) induces rapid, nonsustained proliferation in cultured rat microglia. Glia 2006; 53:669-74. [PMID: 16419088 DOI: 10.1002/glia.20313] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Microglial cells undergo cell division in vitro, as well as in vivo after brain injury. Mitotic activity of microglia suggests that they have limited life spans and rely on self-renewal to replace senescent cells. In the current study we examined long-term effects of antioxidants vitamin E and alpha-lipoic acid on cultured rat microglia with respect to proliferative ability, telomere length, telomerase activity, and interleukin-1beta (IL-1beta) production. We report that vitamin E induces dramatic microglial proliferation, as measured by MTT assay and BrdU incorporation, surpassing that of the well-known microglial mitogen granulocyte macrophage-colony stimulating factor, and therefore establishing vitamin E as the most potent, known mitogen for microglia in vitro. The high rate of microglial proliferation resulted in a concomitant decrease in telomere length and telomerase activity. Production of IL-1beta was significantly decreased in vitamin E-treated microglia in vitro. Our findings provide an impetus to investigate potential benefits of vitamin E supplementation on microglial renewal capacity in vivo during aging or after brain injury.
Collapse
Affiliation(s)
- Barry E Flanary
- Department of Neuroscience, University of Florida College of Medicine and McKnight Brain Institute,Gainesville, 32610-0244, USA
| | | |
Collapse
|
62
|
Godbout JP, Berg BM, Krzyszton C, Johnson RW. Alpha-tocopherol attenuates NFkappaB activation and pro-inflammatory cytokine production in brain and improves recovery from lipopolysaccharide-induced sickness behavior. J Neuroimmunol 2005; 169:97-105. [PMID: 16146653 DOI: 10.1016/j.jneuroim.2005.08.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Accepted: 08/03/2005] [Indexed: 02/07/2023]
Abstract
This study was conducted to determine if alpha-tocopherol facilitates recovery from lipopolysaccharide (LPS)-induced sickness behavior through a NFkappaB-dependent mechanism. In the first study, 3 daily intraperitoneal (i.p.) injections of alpha-tocopherol (20 mg) improved recovery from sickness behavior induced by i.p. injected LPS. Furthermore, alpha-tocopherol pretreatment attenuated LPS-activated NFkappaB and pro-inflammatory cytokine production in brain. In addition, inhibiting NFkappaB activity in the brain specifically by ICV injection of a NFkappaB decoy prior to LPS, significantly accelerated recovery from LPS-induced sickness behavior. Taken together, these data indicate alpha-tocopherol modulates sickness behavior and inflammatory cytokine production in the brain through an NFkappaB-dependent pathway.
Collapse
Affiliation(s)
- J P Godbout
- Division of Nutritional Sciences and Department of Animal Sciences, University of Illinois, 1207 W. Gregory Drive, Urbana, IL 61801, USA
| | | | | | | |
Collapse
|
63
|
Hou RCW, Chen YS, Chen CH, Chen YH, Jeng KCG. Protective effect of 1,2,4-benzenetriol on LPS-induced NO production
by BV2 microglial cells. J Biomed Sci 2005; 13:89-99. [PMID: 16308662 DOI: 10.1007/s11373-005-9039-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2005] [Accepted: 09/20/2005] [Indexed: 10/25/2022] Open
Abstract
Hydroxyhydroquinone or 1,2,4-benzenetriol (BT) detected in the beverages has a structure that coincides with the water-soluble form of a sesame lignan, sesamol. We previously showed that sesame antioxidants had neuroprotective abilities due to their antioxidant properties and/or inducible nitric oxide synthase (iNOS) inhibition. However, studies show that BT can induce DNA damage through the generation of reactive oxygen species (ROS). Therefore, we were interested to investigate the neuroprotective effect of BT in vitro and in vivo. The results showed that instead of enhancing free radical generation, BT dose-dependently (10-100 microM) attenuated nitrite production, iNOS mRNA and protein expression in lipopolysaccharide (LPS)-stimulated murine BV-2 microglia. BT significantly reduced LPS-induced NF-kappaB and p38 MAPK activation. It also significantly reduced the generation of ROS in H2O2-induced BV-2 cells and in H2O2-cellfree conditions. The neuroprotective effect of BT was further demonstrated in the focal cerebral ischemia model of Sprague-Dawley rat. Taken together, the inhibition of LPS-induced nitrite production might be due to the suppression of NF-kappaB, p38 MAPK signal pathway and the ROS scavenging effect. These effects might help to protect neurons from the ischemic injury.
Collapse
|
64
|
Liu L, Li Y, Van Eldik LJ, Griffin WST, Barger SW. S100B-induced microglial and neuronal IL-1 expression is mediated by cell type-specific transcription factors. J Neurochem 2005; 92:546-53. [PMID: 15659225 DOI: 10.1111/j.1471-4159.2004.02909.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Both the astrocytic cytokine S100B and the pro-inflammatory interleukin-1 (IL-1) are elevated in Alzheimer's disease, and each has been implicated in Alzheimer-related neuropathology. We examined the gene-regulatory events through which S100B induces IL-1beta expression. In primary microglia, S100B activated the transcription factors Sp1 and NFkappaB, followed by an increase in IL-1beta mRNA levels. The latter was blocked by a peptide inhibitor of NFkappaB or by a double-stranded oligonucleotide containing a NFkappaB-binding site to serve as "decoy" DNA and reduce available NFkappaB. But in primary cortical neurons, decoy and siRNA experiments indicated that the IL-1beta induction by S100B was mediated by Sp1 without evidence of a role for NFkappaB. Our results suggest that the elevation of S100B and IL-1 in Alzheimer brain and consequent neurodegenerative events are mediated through cell-type specific gene-regulatory events, providing mechanistic insight into connections between glial activation and neuronal dysfunction.
Collapse
Affiliation(s)
- Ling Liu
- Department of Geriatrics, University of Arkansas for Medical Sciences, 629 Jack Stephens Drive #807, Little Rock, AR 72205, USA
| | | | | | | | | |
Collapse
|
65
|
Jeng KCG, Hou RCW, Wang JC, Ping LI. Sesamin inhibits lipopolysaccharide-induced cytokine production by suppression of p38 mitogen-activated protein kinase and nuclear factor-kappaB. Immunol Lett 2005; 97:101-6. [PMID: 15626481 DOI: 10.1016/j.imlet.2004.10.004] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 10/01/2004] [Accepted: 10/08/2004] [Indexed: 10/26/2022]
Abstract
Sesame seed oil increases the survival after cecal ligation and puncture in mice and the increased IL-10 levels with non-lethal lipopolysaccharides (LPS) challenge. We showed that sesamin and sesamolin, major lignans of sesame oil, regulated LPS-induced nitric oxide production in the murine microglia and BV-2 cell line. In this study, we studied the effect of sesamin on cytokine production by LPS stimulation. The result showed that sesamin significantly inhibited LPS-stimulated IL-6 mRNA and protein, and to a lesser degree TNF-alpha, in BV-2 microglia. Sesamin and sesamolin also reduced LPS-activated p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappaB activations. Furthermore, SB203580, a specific inhibitor of p38 MAP kinase, specifically inhibited LPS-induced IL-6 production. These results suggest that sesamin inhibited LPS-induced IL-6 production by suppression of p38 MAPK signal pathway and NF-kappaB activation.
Collapse
Affiliation(s)
- Kee-Ching G Jeng
- Department of Education and Research, Taichung Veterans General Hospital, 160 Chung Kang Road, sec 3, Taichung 40705, Taiwan, ROC.
| | | | | | | |
Collapse
|
66
|
Dheen ST, Jun Y, Yan Z, Tay SSW, Ling EA. Retinoic acid inhibits expression of TNF-alpha and iNOS in activated rat microglia. Glia 2005; 50:21-31. [PMID: 15602748 DOI: 10.1002/glia.20153] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The release of proinflammatory mediators such as tumor necrosis factor-alpha (TNF-alpha) and nitric oxide by microglia has been implicated in neurotoxicity in chronic neurodegenerative diseases such as Alzheimer's disease. As all-trans-retinoic acid (RA) has been reported to exert anti-inflammatory actions in various cell types, we have examined its effects on the expression of TNF-alpha and inducible nitric oxide synthase (iNOS) in microglia activated by beta-amyloid peptide (Abeta) and lipopolysaccharide (LPS). Exposure of primary cultures of rat microglial cells to Abeta or LPS stimulated the mRNA expression level of TNF-alpha (6-116-fold) and iNOS (8-500-fold) significantly. RA acted in a dose-dependent manner (0.1-10 microM) by attenuating both TNF-alpha (29-97%) and iNOS (61-96%) mRNA expression in microglia exposed to Abeta or LPS. RA-induced inhibition of TNF-alpha and iNOS mRNA expression in activated microglia was accompanied by the concomitant reduction in release of iNOS and TNF-alpha proteins as revealed by nitrite assay and ELISA, respectively. The anti-inflammatory effects of RA were correlated with the enhanced expression of retinoic acid receptor-beta, and transforming growth factor-beta1 as well as the inhibition of NF-kappaB translocation. These results suggest that RA may inhibit the neurotoxic effect of activated microglia by suppressing the production of inflammatory cytokines and cytotoxic molecules.
Collapse
Affiliation(s)
- S Thameem Dheen
- Department of Anatomy, Molecular Neurobiology Laboratory, Faculty of Medicine, National University of Singapore, Singapore.
| | | | | | | | | |
Collapse
|
67
|
Muller T, Grandbarbe L, Morga E, Heuschling P, Luu B. Tocopherol long chain fatty alcohols decrease the production of TNF-alpha and NO radicals by activated microglial cells. Bioorg Med Chem Lett 2005; 14:6023-6. [PMID: 15546721 DOI: 10.1016/j.bmcl.2004.09.078] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Revised: 09/27/2004] [Accepted: 09/28/2004] [Indexed: 01/05/2023]
Abstract
The synthesis of a series of Tocopherol long chain Fatty Alcohols (TFA) and their biological activities on the modulation of microglial activation are described. Specifically, the 2-(12-hydroxy-dodecyl)-2,5,7,8-tetramethyl-chroman-6-ol, the TFA bearing 12 carbon atoms on the side chain (n=12), shows the most potent inhibition of secretion on nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha) by lipopolysaccharide (LPS)-activated microglia.
Collapse
Affiliation(s)
- Thierry Muller
- Laboratoire de chimie organique des substances naturelles, Centre de Neurochimie, UMR 7123 CNRS, Université Louis Pasteur, 67084 Strasbourg, France
| | | | | | | | | |
Collapse
|
68
|
Haddad JJ. Mitogen-activated protein kinases and the evolution of Alzheimer's: a revolutionary neurogenetic axis for therapeutic intervention? Prog Neurobiol 2004; 73:359-77. [PMID: 15312913 DOI: 10.1016/j.pneurobio.2004.06.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2002] [Accepted: 06/16/2004] [Indexed: 01/10/2023]
Abstract
Alzheimer's disease (AD) is a neurogenetic condition that affects the processes via which the brain functions. Major observable hallmarks of AD are accumulated clusters of proteins in the brain. These clusters, termed neurofibrillary tangles (NFT), resemble pairs of threads wound around each other in a helix fashion accumulating within neurons. These tangles consist of a protein called Tau, which binds to tubulin, thus forming microtubules. Unlike NFTs, deposits of amyloid precursor protein (beta-APP) gather in the spaces between nerve cells. The nearby neurons often look swollen and deformed, and the clusters of protein are usually accompanied by reactive inflammatory cells, microglia, which are part of the brain's immune system responsible for degrading and removing damaged neurons or plaques. Since phosphorylation/dephosphorylation mechanisms are crucial in the regulation of Tau and beta-APP, a superfamily of mitogen-activated protein kinases (MAPKs) has recently emerged as key regulators of the formation of plagues, eventually leading to dementia and AD. The complex molecular interactions between MAPKs and proteins (plagues) associated with the evolution of AD form a cornerstone in the knowledge of a still burgeoning field of neurodegenerative diseases and ageing. This review overviews current understanding of the molecular pathways related to MAPKs and their role in the development of AD and, possibly, dementia. MAPKs, therefore, may constitute a neurogenetic, therapeutic target for the diagnosis and evolution of a preventative medical strategy for early detection, and likely treatment, of Alzheimer's.
Collapse
Affiliation(s)
- John J Haddad
- Severinghaus-Radiometer Research Laboratories, Department of Anesthesia and Perioperative Care, University of California, San Francisco, CA, USA.
| |
Collapse
|
69
|
Suk K, Park JH, Lee WH. Neuropeptide PACAP inhibits hypoxic activation of brain microglia: a protective mechanism against microglial neurotoxicity in ischemia. Brain Res 2004; 1026:151-6. [PMID: 15476707 DOI: 10.1016/j.brainres.2004.08.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2004] [Indexed: 11/30/2022]
Abstract
Hypoxia is one of the important physiological stimuli that are often associated with a variety of pathological states such as ischemia, respiratory diseases, and tumorigenesis. In the central nervous system, hypoxia that is accompanied by cerebral ischemia not only causes neuronal cell injury, but may also induce pathological microglial activation. We have previously shown that hypoxia induces inflammatory activation of cultured microglia and their inducible nitric oxide synthase induction via p38 mitogen-activated protein kinase (MAPK) pathway, and a neuropeptide PACAP selectively inhibits microglial signal transduction. Based on these findings, we hypothesized that the neuropeptide may inhibit the hypoxic activation of microglia, and this may provide a neuroprotection against inflammation-induced neuronal injury. When this possibility was tested using cultured microglia and PC12 cells, we found that PACAP attenuates inflammatory activation of microglia under hypoxic condition, and protects cocultured PC12 cells from microglial neurotoxicity. In addition, the neuropeptide reduced the hypoxia-induced activation of p38 MAPK, indicating that the p38 MAPK is a molecular target of the PACAP action in microglia. The neuroprotective effects of PACAP in animal models of cerebral hypoxia/ischemia may be partly due to its direct actions on brain microglia and neurotoxic inflammation.
Collapse
Affiliation(s)
- Kyoungho Suk
- Department of Pharmacology, School of Medicine, Kyungpook National University, 101 Dong-In, Joong-gu, Daegu, 700-422 South Korea.
| | | | | |
Collapse
|
70
|
Milatovic D, Zaja-Milatovic S, Montine KS, Shie FS, Montine TJ. Neuronal oxidative damage and dendritic degeneration following activation of CD14-dependent innate immune response in vivo. J Neuroinflammation 2004; 1:20. [PMID: 15498098 PMCID: PMC527876 DOI: 10.1186/1742-2094-1-20] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2004] [Accepted: 10/21/2004] [Indexed: 11/10/2022] Open
Abstract
The cause-and-effect relationship between innate immune activation and neurodegeneration has been difficult to prove in complex animal models and patients. Here we review findings from a model of direct innate immune activation via CD14 stimulation using intracerebroventricular injection of lipopolysaccharide. These data show that CD14-dependent innate immune activation in cerebrum leads to the closely linked outcomes of neuronal membrane oxidative damage and dendritic degeneration. Both forms of neuronal damage could be blocked by ibuprofen and alpha-tocopherol, but not naproxen or gamma-tocopherol, at pharmacologically relevant concentrations. This model provides a convenient method to determine effective agents and their appropriate dose ranges for protecting neurons from CD14-activated innate immunity-mediated damage, and can guide drug development for diseases, such as Alzheimer disease, that are thought to derive in part from CD14-activated innate immune response.
Collapse
Affiliation(s)
- Dejan Milatovic
- Department of Pathology, University of Washington, Harborview Medical Center, Seattle Washington 98104, USA
| | - Snjezana Zaja-Milatovic
- Department of Pathology, University of Washington, Harborview Medical Center, Seattle Washington 98104, USA
| | - Kathleen S Montine
- Department of Pathology, University of Washington, Harborview Medical Center, Seattle Washington 98104, USA
| | - Feng-Shiun Shie
- Department of Pathology, University of Washington, Harborview Medical Center, Seattle Washington 98104, USA
| | - Thomas J Montine
- Department of Pathology, University of Washington, Harborview Medical Center, Seattle Washington 98104, USA
| |
Collapse
|
71
|
Ayasolla K, Khan M, Singh AK, Singh I. Inflammatory mediator and beta-amyloid (25-35)-induced ceramide generation and iNOS expression are inhibited by vitamin E. Free Radic Biol Med 2004; 37:325-38. [PMID: 15223066 DOI: 10.1016/j.freeradbiomed.2004.04.007] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2003] [Revised: 03/25/2004] [Accepted: 04/02/2004] [Indexed: 10/26/2022]
Abstract
To investigate the putative role of beta-amyloid peptide (A beta) in inducing oxidative stress damage in Alzheimer disease (AD), we studied the effects of proinflammatory cytokines and A beta peptide on the induction of inducible nitric oxide synthase (iNOS). A beta(25-35) upregulated the cytokine (TNF-alpha/IL-1 beta)-induced expression of iNOS and the production of nitric oxide (NO) in astrocytes, which were inhibited by vitamin E. A beta treatment of C6 glial cells (together with LPS and IFN-gamma), in addition to inducing iNOS, enhanced the oxidative stress as measured by increased expression of manganese superoxide dismutase and an increase in 2,7'-dichlorofluorescein diacetate fluorescence. We also observed that LPS, IFN-gamma, and A beta(25-35) treatment led to the activation of the sphingomyelin-ceramide (SM-Cer) cascade with an increase in cellular ceramide. Inhibition of the SM-Cer cascade either by vitamin E treatment or by the neutral sphingomyelinase inhibitor 3-O-methyl sphingomyelin also resulted in alteration of the transcriptional binding activities of C/EBP, NFkappaB, AP-1, and CREB in C6 glial cells. Hence, these findings suggest a role for ceramide in iNOS induction and NO production in Abeta-induced AD pathobiology and provide a possible explanation for the beneficial effects of vitamin E therapy.
Collapse
Affiliation(s)
- Kamesh Ayasolla
- Department of Pediatrics, Medical University of South Carolina, Charleston, SC 29425, USA
| | | | | | | |
Collapse
|
72
|
Li Y, Liu L, Liu D, Woodward S, Barger SW, Mrak RE, Griffin WST. Microglial activation by uptake of fDNA via a scavenger receptor. J Neuroimmunol 2004; 147:50-5. [PMID: 14741427 PMCID: PMC3846353 DOI: 10.1016/j.jneuroim.2003.10.043] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The fate of the fragmented DNA (fDNA) observed in neuronal nuclei in Alzheimer brain is unknown. However, its fate is suggested as fDNA is found in the cytoplasm of adjacent activated microglia. After a brief incubation with fDNA, approximately 70% of microglia had fDNA in their cytoplasm, were activated, and overexpressed interleukin-1beta. Microglial activation enhanced uptake whereas blocking scavenger receptors suppressed this uptake. These results suggest that the brain rids itself of fDNA from dying neurons through microglial uptake, activation, and overexpression of IL-1. Such overexpression of IL-1 in Alzheimer brain has been linked to Alzheimer pathogenesis.
Collapse
MESH Headings
- Alzheimer Disease/metabolism
- Animals
- Animals, Newborn
- Antibodies/pharmacology
- Antineoplastic Agents/pharmacology
- Biological Transport
- Blotting, Northern
- Brain/cytology
- Brain/physiopathology
- Case-Control Studies
- Cells, Cultured
- Cerebral Cortex/cytology
- DNA/metabolism
- Flow Cytometry/methods
- Humans
- In Situ Nick-End Labeling/methods
- Interferon-gamma/pharmacology
- Membrane Proteins
- Mice
- Mice, Inbred C57BL
- Microglia/drug effects
- Microglia/metabolism
- Phagocytes/metabolism
- Polysaccharides/pharmacology
- RNA, Messenger
- Rats
- Rats, Sprague-Dawley
- Receptors, Immunologic/metabolism
- Receptors, Lipoprotein
- Receptors, Scavenger
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Scavenger Receptors, Class B
Collapse
Affiliation(s)
- Yuekui Li
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Ling Liu
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Dongge Liu
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
- Department of Pathology, Beijing Hospital, Beijing 100730, China
| | - S. Woodward
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Steven W. Barger
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
- Department of Anatomy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
- Geriatric Research Education Clinical Center, Department of Veterans Affairs Medical Center, Little Rock, AR 72205, USA
| | - Robert E. Mrak
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - W. Sue T. Griffin
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
- Department of Anatomy, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
- Geriatric Research Education Clinical Center, Department of Veterans Affairs Medical Center, Little Rock, AR 72205, USA
- Corresponding author. Department of Geriatrics, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205, USA, (W.S.T. Griffin)
| |
Collapse
|
73
|
Götz ME, Riederer P. Advances in Neuroprotection Research for Neurodegenerative Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 541:1-19. [PMID: 14977205 DOI: 10.1007/978-1-4419-8969-7_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Mario E Götz
- Institute of Pharmacology and Toxicology, 97078 Würzburg, Germany
| | | |
Collapse
|
74
|
Hensley K, Benaksas EJ, Bolli R, Comp P, Grammas P, Hamdheydari L, Mou S, Pye QN, Stoddard MF, Wallis G, Williamson KS, West M, Wechter WJ, Floyd RA. New perspectives on vitamin E: gamma-tocopherol and carboxyelthylhydroxychroman metabolites in biology and medicine. Free Radic Biol Med 2004; 36:1-15. [PMID: 14732286 DOI: 10.1016/j.freeradbiomed.2003.10.009] [Citation(s) in RCA: 208] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Revised: 10/16/2003] [Accepted: 10/17/2003] [Indexed: 01/20/2023]
Abstract
Vitamin E (alpha-tocopherol or alphaT) has long been recognized as a classic free radical scavenging antioxidant whose deficiency impairs mammalian fertility. In actuality, alpha-tocopherol is one member of a class of phytochemicals that are distinguished by varying methylation of a chroman head group. Early studies conducted between 1922 and 1950 indicated that alpha-tocopherol was specific among the tocopherols in allowing fertility of laboratory animals. The unique vitamin action of alphaT, combined with its prevalence in the human body and the similar efficiency of tocopherols as chain-breaking antioxidants, led biologists to almost completely discount the "minor" tocopherols as topics for basic and clinical research. Recent discoveries have forced a serious reconsideration of this conventional wisdom. New and unexpected biological activities have been reported for the desmethyl tocopherols, such as gamma-tocopherol, and for specific tocopherol metabolites, most notably the carboxyethyl-hydroxychroman (CEHC) products. The activities of these other tocopherols do not map directly to their chemical antioxidant behavior but rather reflect anti-inflammatory, antineoplastic, and natriuretic functions possibly mediated through specific binding interactions. Moreover, a nascent body of epidemiological data suggests that gamma-tocopherol is a better negative risk factor for certain types of cancer and myocardial infarction than is a alpha-tocopherol. The potential public health implications are immense, given the extreme popularity of alphaT supplementation which can unintentionally deplete the body of gamma-tocopherol. These findings may or may not signal a major paradigm shift in free radical biology and medicine. The data argue for thorough experimental and epidemiological reappraisal of desmethyl tocopherols, especially within the contexts of cardiovascular disease and cancer biology.
Collapse
Affiliation(s)
- Kenneth Hensley
- Free Radical Biology and Aging Research Program, Oklahoma Medical Reserach Foundation, Oklahoma City, OK 73104, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
75
|
Hou RCW, Chen HL, Tzen JTC, Jeng KCG. Effect of sesame antioxidants on LPS-induced NO production by BV2 microglial cells. Neuroreport 2003; 14:1815-9. [PMID: 14534426 DOI: 10.1097/00001756-200310060-00011] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Sesame antioxidants have been shown to inhibit lipid peroxidation and regulate cytokine production. In this study, we focused on the effect of sesamin and sesamolin, on nitric oxide (NO) induction by lipopolysaccharides (LPS) in the murine microglial cell line BV-2 and rat primary microglia. The results showed that sesamin and sesamolin significantly inhibited NO production, iNOS mRNA and protein expression in LPS-stimulated BV-2 cells. Sesamin or sesamolin significantly reduced LPS-activated p38 MAPK of BV-2 cells. Furthermore, SB203580, a specific inhibitor of p38 MAP kinase, dose-dependently inhibited NO production in LPS-stimulated BV-2 cells. Taken together, the inhibition of NO production might be due to the reduction of LPS-induced p38 MAPK signal pathway by sesamin and sesamolin.
Collapse
Affiliation(s)
- Rolis Chien-Wei Hou
- Graduate Institute of Biotechnology, National Chung Hsing University, Taiwan, RO China.
| | | | | | | |
Collapse
|
76
|
Lee H, Kim YO, Kim H, Kim SY, Noh HS, Kang SS, Cho GJ, Choi WS, Suk K. Flavonoid wogonin from medicinal herb is neuroprotective by inhibiting inflammatory activation of microglia. FASEB J 2003; 17:1943-4. [PMID: 12897065 DOI: 10.1096/fj.03-0057fje] [Citation(s) in RCA: 202] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Wogonin (5,7-dihydroxy-8-methoxyflavone), a flavonoid originated from the root of a medicinal herb Scutellaria baicalensis Georgi, has been previously shown to have anti-inflammatory activities in various cell types including macrophages. In this work, we have found that wogonin is a potent neuroprotector from natural source. Wogonin inhibited inflammatory activation of cultured brain microglia by diminishing lipopolysaccharide-induced tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta, and nitric oxide (NO) production. Wogonin inhibited NO production by suppressing inducible NO synthase (iNOS) induction and NF-kappaB activation in microglia. Inhibition of inflammatory activation of microglia by wogonin led to the reduction in microglial cytotoxicity toward cocultured PC12 cells, supporting a neuroprotective role for wogonin in vitro. The neuroprotective effect of wogonin was further demonstrated in vivo using two experimental brain injury models; transient global ischemia by four-vessel occlusion and excitotoxic injury by systemic kainate injection. In both animal models, wogonin conferred neuroprotection by attenuating the death of hippocampal neurons, and the neuroprotective effect was associated with inhibition of the inflammatory activation of microglia. Hippocampal induction of inflammatory mediators such as iNOS and TNF-alpha was reduced by wogonin in the global ischemia model, and microglial activation was markedly down-regulated by wogonin in the kainate injection model as judged by microglia-specific isolectin B4 staining. Taken together, our results indicate that wogonin exerts its neuroprotective effect by inhibiting microglial activation, which is a critical component of pathogenic inflammatory responses in neurodegenerative diseases. The current study emphasizes the importance of medicinal herbs and their constituents as an invaluable source for the development of novel neuroprotective drugs.
Collapse
Affiliation(s)
- Heasuk Lee
- Department of Anatomy and Neurobiology, Research Institute of Natural Science, Gyeongsang National University College of Medicine, 92 Chilam-dong, Jinju, Kyungnam 660-751, Korea
| | | | | | | | | | | | | | | | | |
Collapse
|
77
|
Michel U, Gerber J, E O'Connor A, Bunkowski S, Brück W, Nau R, Phillips DJ. Increased activin levels in cerebrospinal fluid of rabbits with bacterial meningitis are associated with activation of microglia. J Neurochem 2003; 86:238-45. [PMID: 12807443 DOI: 10.1046/j.1471-4159.2003.01834.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Activin, a member of the transforming growth factor superfamily, is upregulated in a number of inflammatory episodes such as septicemia and rheumatoid arthritis. In the CNS, activin has been predominantly assessed in terms of a neuroprotective role. In this report we characterized the activin response in the CNS in a rabbit model of meningitis. In normal animals, cerebrospinal fluid (CSF) activin levels were higher than those in serum, indicating an intracranial secretion of this cytokine. Following intracisternal inoculation with Streptococcus pneumoniae, activin in CSF was unchanged for the first 12 h and then rose progressively; levels were increased approximately 15-fold within 24 h. Activin levels were correlated positively with CSF protein content and with the number of apoptotic neurons in the dentate gyrus. No apparent correlation was observed between CSF activin concentrations and bacterial titer, lactate concentrations or leukocyte density. Using immunohistochemistry, activin staining was localized to epithelial cells of the choroid plexus, cortical neurons and the CA3 region of the hippocampus, with similar staining intensities in both normal and meningitic brains. However, in meningitic brains there was also strong staining in activated microglia and infiltrating macrophages. Taken together, these results demonstrate that activin forms part of the CNS response to immune challenge and may be an important mediator to modulate inflammatory processes in the brain.
Collapse
Affiliation(s)
- Uwe Michel
- Monash Institute of Reproduction and Development, Monash University, Clayton, Victoria, Australia.
| | | | | | | | | | | | | |
Collapse
|
78
|
Interleukin-1 mediates pathological effects of microglia on tau phosphorylation and on synaptophysin synthesis in cortical neurons through a p38-MAPK pathway. J Neurosci 2003. [PMID: 12629164 DOI: 10.1523/jneurosci.23-05-01605.2003] [Citation(s) in RCA: 379] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The presence of tangles of abnormally phosphorylated tau is a characteristic of Alzheimer's disease (AD), and the loss of synapses correlates with the degree of dementia. In addition, the overexpression of interleukin-1 (IL-1) has been implicated in tangle formation in AD. As a direct test of the requirement for IL-1 in tau phosphorylation and synaptophysin expression, IL-1 actions in neuron-microglia cocultures were manipulated. Activation of microglia with secreted beta-amyloid precursor protein or lipopolysaccharide elevated their expression of IL-1alpha, IL-1beta, and tumor necrosis factor alpha (TNFalpha) mRNA. When such activated microglia were placed in coculture with primary neocortical neurons, a significant increase in the phosphorylation of neuronal tau was accompanied by a decline in synaptophysin levels. Similar effects were evoked by treatment of neurons with recombinant IL-1beta. IL-1 receptor antagonist (IL-1ra) as well as anti-IL-1beta antibody attenuated the influence of activated microglia on neuronal tau and synaptophysin, but anti-TNFalpha antibody was ineffective. Some effects of microglial activation on neurons appear to be mediated by activation of p38 mitogen-activated protein kinase (p38-MAPK), because activated microglia stimulated p38-MAPK phosphorylation in neurons, and an inhibitor of p38-MAPK reversed the influence of IL-1beta on tau phosphorylation and synaptophysin levels. Our results, together with previous observations, suggest that activated microglia may contribute to neurofibrillary pathology in AD through their production of IL-1, activation of neuronal p38-MAPK, and resultant changes in neuronal cytoskeletal and synaptic elements.
Collapse
|
79
|
Egger T, Schuligoi R, Wintersperger A, Amann R, Malle E, Sattler W. Vitamin E (alpha-tocopherol) attenuates cyclo-oxygenase 2 transcription and synthesis in immortalized murine BV-2 microglia. Biochem J 2003; 370:459-67. [PMID: 12429020 PMCID: PMC1223182 DOI: 10.1042/bj20021358] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2002] [Revised: 11/08/2002] [Accepted: 11/13/2002] [Indexed: 01/20/2023]
Abstract
One of the immediate early microglial genes that are up-regulated in response to proinflammatory stimuli is cyclo-oxygenase 2 (COX-2). In the present study, we have investigated the effects of alpha-tocopherol (alpha TocH), an essential constituent of the nervous system, on the activation of COX-2 in lipopolysaccharide (LPS)-stimulated mouse BV-2 microglia. In unstimulated BV-2 cells, COX-2 mRNA and protein were almost undetectable but were strongly up-regulated in response to LPS. Activation of COX-2 protein synthesis in LPS-stimulated BV-2 cells involved activation of the extracellular-signal-regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) pathway and was sensitive to the protein kinase C (PKC) inhibitors staurosporine and chelerythrine, and the MAP kinase/ERK kinase 1/2 inhibitors PD98059 and U0126. Supplementation of BV-2 cells with alpha TocH before LPS stimulation resulted in pronounced up-regulation of protein phosphatase 2A (PP2A) activity, down-regulation of PKC activity, ERK1/2 phosphorylation and nuclear factor kappa B (NF kappa B) activation. As a result, COX-2 protein levels and prostaglandin E(2) production were significantly lower in alpha TocH-supplemented cells. The effects of alpha TocH on PKC activity could be reverted by calyculin A and okadaic acid, two PP inhibitors. In summary, our results suggest that alpha TocH activates microglial PP2A activity and thereby silences an LPS-activated PKC/ERK/NF kappa B signalling cascade resulting in significantly attenuated COX-2 protein synthesis. These in vitro results imply that alpha TocH could induce quiescence to pathways that are associated with acute or chronic inflammatory conditions in the central nervous system.
Collapse
Affiliation(s)
- Tamara Egger
- Institute of Medical Biochemistry and Molecular Biology, University Graz, Harrachgasse 21, 8010 Graz, Austria
| | | | | | | | | | | |
Collapse
|
80
|
Li Y, Liu L, Barger SW, Griffin WST. Interleukin-1 mediates pathological effects of microglia on tau phosphorylation and on synaptophysin synthesis in cortical neurons through a p38-MAPK pathway. J Neurosci 2003; 23:1605-11. [PMID: 12629164 PMCID: PMC3833596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023] Open
Abstract
The presence of tangles of abnormally phosphorylated tau is a characteristic of Alzheimer's disease (AD), and the loss of synapses correlates with the degree of dementia. In addition, the overexpression of interleukin-1 (IL-1) has been implicated in tangle formation in AD. As a direct test of the requirement for IL-1 in tau phosphorylation and synaptophysin expression, IL-1 actions in neuron-microglia cocultures were manipulated. Activation of microglia with secreted beta-amyloid precursor protein or lipopolysaccharide elevated their expression of IL-1alpha, IL-1beta, and tumor necrosis factor alpha (TNFalpha) mRNA. When such activated microglia were placed in coculture with primary neocortical neurons, a significant increase in the phosphorylation of neuronal tau was accompanied by a decline in synaptophysin levels. Similar effects were evoked by treatment of neurons with recombinant IL-1beta. IL-1 receptor antagonist (IL-1ra) as well as anti-IL-1beta antibody attenuated the influence of activated microglia on neuronal tau and synaptophysin, but anti-TNFalpha antibody was ineffective. Some effects of microglial activation on neurons appear to be mediated by activation of p38 mitogen-activated protein kinase (p38-MAPK), because activated microglia stimulated p38-MAPK phosphorylation in neurons, and an inhibitor of p38-MAPK reversed the influence of IL-1beta on tau phosphorylation and synaptophysin levels. Our results, together with previous observations, suggest that activated microglia may contribute to neurofibrillary pathology in AD through their production of IL-1, activation of neuronal p38-MAPK, and resultant changes in neuronal cytoskeletal and synaptic elements.
Collapse
Affiliation(s)
- Yuekui Li
- Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
| | | | | | | |
Collapse
|
81
|
Obermuller-Jevic b U, Packer a L. Vitamin E in Disease Prevention and Therapy. Antioxidants (Basel) 2003. [DOI: 10.1201/9781439822173.ch19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
82
|
Wang MJ, Lin WW, Chen HL, Chang YH, Ou HC, Kuo JS, Hong JS, Jeng KCG. Silymarin protects dopaminergic neurons against lipopolysaccharide-induced neurotoxicity by inhibiting microglia activation. Eur J Neurosci 2002; 16:2103-12. [PMID: 12473078 DOI: 10.1046/j.1460-9568.2002.02290.x] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
An inflammatory response in the central nervous system mediated by activation of microglia is a key event in the early stages of the development of neurodegenerative diseases. Silymarin is a polyphenolic flavanoid derived from milk thistle that has anti-inflammatory, cytoprotective and anticarcinogenic effects. In this study, we first investigated the neuroprotective effect of silymarin against lipopolysaccharide (LPS)-induced neurotoxicity in mesencephalic mixed neuron-glia cultures. The results showed that silymarin significantly inhibited the LPS-induced activation of microglia and the production of inflammatory mediators, such as tumour necrosis factor-alpha and nitric oxide (NO), and reduced the damage to dopaminergic neurons. Therefore, the inhibitory mechanisms of silymarin on microglia activation were studied further. The production of inducible nitric oxide synthase (iNOS) was studied in LPS-stimulated BV-2 cells as a model of microglia activation. Silymarin significantly reduced the LPS-induced nitrite, iNOS mRNA and protein levels in a dose-dependent manner. Moreover, LPS could induce the activation of p38 mitogen-activated protein kinase (MAPK) and c-jun N-terminal kinase but not extracellular signal-regulated kinase. The LPS-induced production of NO was inhibited by the selective p38 MAPK inhibitor SB203580. These results indicated that the p38 MAPK signalling pathway was involved in the LPS-induced NO production. However, the activation of p38 MAPK was not inhibited by silymarin. Nevertheless, silymarin could effectively reduce LPS-induced superoxide generation and nuclear factor kappaB (NF-kappaB) activation. It suggests that the inhibitory effect of silymarin on microglia activation is mediated through the inhibition of NF-kappaB activation.
Collapse
Affiliation(s)
- Mei-Jen Wang
- Department of Education and Research, Taichung Veterans General Hospital, Taichung 40705, Taiwan
| | | | | | | | | | | | | | | |
Collapse
|
83
|
Abstract
Although microglial cells are thought to play a beneficial role in the regeneration and plasticity of the central nervous system (CNS), recent studies have indicated that at least some molecules released by microglia may be harmful in acute brain insults and neurodegenerative diseases. Therefore, the pathways mediating the synthesis and release of these neurotoxic compounds are of importance. p38 and p44/42 families of mitogen-activated protein kinases (MAPKs) in microglia respond strongly to various extracellular stimuli, such as ATP, thrombin, and beta-amyloid, a peptide thought to be responsible for the neuropathology in Alzheimer's disease. In this review we describe in vivo evidence implicating that p38 and p44/42 MAPKs may play a critical role in harmful microglial activation in acute brain injury, such as stroke, and in more chronic neurodegenerative diseases, such as Alzheimer's disease. We also clarify the extracellular signals responsible for activation of p38 and p44/42 MAPK in microglia and review the responses so far reported to be mediated by these kinases.
Collapse
Affiliation(s)
- Milla Koistinaho
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Kuopio, Finland
| | - Jari Koistinaho
- Department of Neurobiology, A.I. Virtanen Institute for Molecular Sciences, University of Kuopio, Finland
- Department of Clinical Pathology, Kuopio University Hospital, Kuopio, Finland
| |
Collapse
|
84
|
Abstract
Microglia, residential macrophages in the central nervous system, can release a variety of factors including cytokines, chemokines, etc. to regulate the communication among neuronal and other types of glial cells. Microglia play immunological roles in mechanisms underlying the phagocytosis of invading microorganisms and removal of dead or damaged cells. When microglia are hyperactivated due to a certain pathological imbalance, they may cause neuronal degeneration. Pathological activation of microglia has been reported in a wide range of conditions such as cerebral ischemia, Alzheimer's disease, prion diseases, multiple sclerosis, AIDS dementia, and others. Nearly 5000 papers on microglia can be retrieved on the Web site PubMed at present (November 2001) and half of them were published within the past 5 years. Although it is not possible to read each paper in detail, as many factors as possible affecting microglial functions in in vitro culture systems are presented in this review. The factors are separated into "activators" and "inhibitors," although it is difficult to classify many of them. An overview on these factors may help in the development of a new strategy for the treatment of various neurodegenerative diseases.
Collapse
Affiliation(s)
- Yoichi Nakamura
- Laboratory of Integrative Physiology in Veterinary Sciences, Osaka Prefecture University; Sakai, Japan.
| |
Collapse
|
85
|
Egger T, Hammer A, Wintersperger A, Goti D, Malle E, Sattler W. Modulation of microglial superoxide production by alpha-tocopherol in vitro: attenuation of p67(phox) translocation by a protein phosphatase-dependent pathway. J Neurochem 2001; 79:1169-82. [PMID: 11752058 DOI: 10.1046/j.1471-4159.2001.00641.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
As in other phagocytic cells, the NADPH-oxidase system in microglia is thought to be primarily responsible for the production of superoxide anion radicals (O2(-.), a potentially cytotoxic reactive oxygen species. The assembly of a functional NADPH-oxidase complex at the plasma membrane depends on the phosphorylation and subsequent translocation of several cytosolic subunits. Immunocytochemical and subcellular fractionation experiments performed during the present study revealed that the NADPH-oxidase subunit p67(phox) translocates from the cytosol to the plasma membrane upon stimulation. Pre-incubation of microglia in alpha-tocopherol (alphaTocH) containing medium decreased O2(-.) production in a time- and concentration-dependent manner, findings attributed to attenuated p67(phox) translocation to the plasma membrane. Moreover, alphaTocH-supplementation of the culture medium resulted in decreased microglial protein kinase C (PKC) activities, an effect that could be partially or completely reversed by the addition of protein phosphatase inhibitors (okadaic acid and calyculin A). The addition of the PKC-inhibitor staurosporine inhibited the microglial respiratory burst in a manner comparable to alphaTocH. The addition of okadaic acid or calyculin A completely restored O2(-.) production in alphaTocH-supplemented cells. The present findings suggest that alphaTocH inactivates PKC via a PP1 or PP2A-mediated pathway and, as a consequence, blocks the phosphorylation-dependent translocation of p67(phox) to the plasma membrane. As a result, O2(-.) production by the microglial NADPH-oxidase system is substantially inhibited.
Collapse
Affiliation(s)
- T Egger
- Institute of Medical Biochemistry and Molecular Biology, Karl Franzens University Graz, Graz, Austria
| | | | | | | | | | | |
Collapse
|