Impact of Optimal Medical Therapy on Long-Term Outcomes After Myocardial Revascularization for Multivessel Coronary Disease.

Although optimal medical therapy (OMT) after coronary revascularization is advocated for intensive secondary prevention, its criteria and effect on long-term outcomes are uncertain. Using data from the ASAN-Multivessel (Asan Medical Center-Multivessel Revascularization) registry, we identified 8,311 patients who underwent coronary artery bypass grafting (CABG) (n = 3,115) or percutaneous coronary intervention (PCI) (n = 5,196). OMT was defined as the combination of minimum of 3 medications in 4 drug classes (antiplatelet drugs, statins, ß blockers, and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers). Two primary outcomes were all-cause mortality and serious composite outcome of death, spontaneous myocardial infarction, or stroke at 10 years. Of 8,311 patients, 4,321 (52.0%) followed OMT. In the 3,397 propensity-score-matched cohort, OMT status compared with non-OMT status was significantly associated with a lower risk of all-cause mortality (10.7% vs 18.7%; hazard ratio [HR] 0.55, 95% confidence interval [CI] 0.47 to 0.65) and serious composite outcome (14.5% vs 22.5%, HR 0.635, 95% CI 0.55 to 0.73) at 10 years. The association on 10-year mortality was more prominent in the PCI group (HR 0.45, 95% CI 0.36 to 0.56) than in the CABG group (HR 0.72, 95% CI 0.58 to 0.90) with a significant interaction (p = 0.001). Overall findings were consistent using different OMT criteria (all 4 types of medications). In conclusion, OMT significantly lowered the risks of mortality and major cardiovascular events at 10 years in patients with multivessel revascularization. The OMT impact on mortality was more remarkable in the PCI group than in the CABG group. This work was registered at http://ClinicalTrials.gov (Identifier: NCT02039752).

Neurogenic effects of rotarod walking exercise in subventricular zone, subgranular zone, and substantia nigra in MPTP-induced Parkinson's disease mice.

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease, and its incidence is predicted to increase worldwide. Striatal dopamine depletion caused by substantia nigra (SN) degeneration is a pathological hallmark of PD and is strongly associated with cardinal motor and non-motor symptoms. Previous studies have reported that exercise increases neuroplasticity and promotes neurorestoration by increasing neurotrophic factors and synaptic strength and stimulating neurogenesis in PD. In the present study, we found that rotarod walking exercise, a modality of motor skill learning training, improved locomotor disturbances and reduced nigrostriatal degeneration in the subacute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. In addition, our exercise regimen improved MPTP-induced perturbation of adult neurogenesis in some areas of the brain, including the subventricular zone, subgranular zone, SN, and striatum. Moreover, rotarod walking activated the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and induced brain-derived neurotrophic factor (BDNF) expression in these regions. The results suggest that motor skill learning training using rotarod walking improves adult neurogenesis and restores motor performance by modulating the AMPK/BDNF pathway. Therefore, our findings provide evidence for neuroprotective effects and improved neuroplasticity in PD through motor skill learning training.

The Potent PDE10A Inhibitor MP-10 (PF-2545920) Suppresses Microglial Activation in LPS-Induced Neuroinflammation and MPTP-Induced Parkinson's Disease Mouse Models.

MP-10 (PF-2545920) is a selective inhibitor of phosphodiesterase 10A (PDE10A), an enzyme highly enriched in the striatum, nucleus accumbens, olfactory tubercle, and substantia nigra. The therapeutic effect of MP-10 has been reported in psychiatric and neurodegenerative disorders such as schizophrenia, depression, and Huntington's disease. However, the effect of MP-10 in Parkinson's disease (PD) has not been reported to date. In this study, we examined the effect of MP-10 in neuroinflammation and PD mouse models. MP-10 inhibited nitric oxide, tumor necrosis factor alpha, and interleukin (IL)-6 production, while it promoted IL-10 production in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. Subsequent western blot and reverse transcription polymerase chain reaction analyses showed that MP-10 reduced the mRNA and protein levels of inducible nitric oxide synthase, cyclooxygenase-2, proinflammatory cytokines, and matrix metalloproteinase-3, -8, and - 9 in LPS-stimulated BV2 cells. Further mechanistic studies revealed that MP-10 exerts anti-inflammatory effects by inhibiting the phosphorylation of c-Jun N-terminal kinase and Akt, reducing the activity of nuclear factor-kappa B/activator protein-1, and upregulating the nuclear factor erythroid 2-related factor 2/antioxidant response element and protein kinase A/cAMP response element-binding protein signaling pathways. The anti-inflammatory effect of MP-10 was confirmed in vivo. Specifically, MP-10 inhibited microglial activation and proinflammatory gene expression in the brains of LPS-injected mice. Moreover, MP-10 rescued behavioral deficits and recovered dopaminergic neuronal cell death in the brains of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced PD mice. MP-10 also reduced microglial activation in this PD mouse model. These data collectively suggest that MP-10 may have therapeutic potential in PD and other neuroinflammatory disorders. Graphical Abstract.

The phosphodiesterase 10 inhibitor papaverine exerts anti-inflammatory and neuroprotective effects via the PKA signaling pathway in neuroinflammation and Parkinson's disease mouse models.

BACKGROUND: Neuroinflammation plays a pivotal role in the pathogenesis of Parkinson's disease (PD). Thus, the development of agents that can control neuroinflammation has been suggested as a promising therapeutic strategy for PD. In the present study, we investigated whether the phosphodiesterase (PDE) 10 inhibitor has anti-inflammatory and neuroprotective effects in neuroinflammation and PD mouse models. METHODS: Papaverine (PAP) was utilized as a selective inhibitor of PDE10. The effects of PAP on the expression of pro-inflammatory molecules were examined in lipopolysaccharide (LPS)-stimulated BV2 microglial cells by ELISA, RT-PCR, and Western blot analysis. The effects of PAP on transcription factors were analyzed by the electrophoretic mobility shift assay, the reporter gene assay, and Western blot analysis. Microglial activation and the expression of proinflammatory molecules were measured in the LPS- or MPTP-injected mouse brains by immunohistochemistry and RT-PCR analysis. The effect of PAP on dopaminergic neuronal cell death and neurotrophic factors were determined by immunohistochemistry and Western blot analysis. To assess mouse locomotor activity, rotarod and pole tests were performed in MPTP-injected mice. RESULTS: PAP inhibited the production of nitric oxide and proinflammatory cytokines in LPS-stimulated microglia by modulating various inflammatory signals. In addition, PAP elevated intracellular cAMP levels and CREB phosphorylation. Treatment with H89, a PKA inhibitor, reversed the anti-inflammatory effects of PAP, suggesting the critical role of PKA signaling in the anti-inflammatory effects of PAP. We verified the anti-inflammatory effects of PAP in the brains of mice with LPS-induced systemic inflammation. PAP suppressed microglial activation and proinflammatory gene expression in the brains of these mice, and these effects were reversed by H89 treatment. We further examined the effects of PAP on MPTP-injected PD model mice. MPTP-induced dopaminergic neuronal cell death and impaired locomotor activity were recovered by PAP. In addition, PAP suppressed microglial activation and proinflammatory mediators in the brains of MPTP-injected mice. CONCLUSIONS: PAP has strong anti-inflammatory and neuroprotective effects and thus may be a potential candidate for treating neuroinflammatory disorders such as PD.

Exercise exerts an anxiolytic effect against repeated restraint stress through 5-HT2A-mediated suppression of the adenosine A2A receptor in the basolateral amygdala.

Repeated or chronic stressful stimuli induce emotion- and mood-related abnormalities, such as anxiety and depression. Conversely, regular exercise exerts protective effects. Here, we found that exercise recovered anxiety-like behaviors, as measured using the open field and elevated plus maze tests in an anxiety mouse model. In addition to behavioral improvement, exercise enhanced the synaptic density of the 5-hydroxytryptamine 2A receptor (5-HT2AR), but not the 5-HT1AR in the basolateral amygdala (BLA) region in this mouse model. Furthermore, global treatment with a selective 5-HT2AR antagonist (MDL11930) generated an anxiety phenotype. Thus, synaptic recruitment of 5-HT2AR in BLA neurons may mediate the anxiolytic effects of exercise. The exercise regimen also reduced adenosine A2A receptor (A2AR)-mediated protein kinase A (PKA) activation, and the anxiolytic effect of the exercise was blunted by local activation of A2AR within the BLA using CGS21680, a selective A2AR agonist. Particularly, A2AR-mediated PKA activity was shown to be dependent on 5-HT2AR signaling in the BLA. These results imply that repeated stress upregulates A2AR-mediated adenosine signaling to facilitate PKA activation, whereas regular exercise inhibits A2AR function by increasing 5-HT2AR in the BLA. Accordingly, this integrated modulation of 5-HT and adenosine signaling, via 5-HT2AR and A2AR respectively, may be a mechanism underlying the anxiolytic effect of regular exercise.

Antiatherogenic Effect of Resveratrol Attributed to Decreased Expression of ICAM-1 (Intercellular Adhesion Molecule-1).

Objective- Increasing evidence shows that resveratrol has antiatherogenic effects, but its underlying mechanisms are unknown. Thus, we evaluated the molecular mechanisms underlying the antiatherogenic effect of resveratrol. Approach and Results- Using the previously established mouse atherosclerosis model of partial ligation of the left carotid artery, we evaluated the role of resveratrol in antiatherosclerosis. We attempted to determine the mechanisms associated with focal adhesions using vascular endothelial cells. The results showed that resveratrol stimulated focal adhesion kinase cleavage via resveratrol-increased expression of lactoferrin in endothelial cells. Furthermore, we found that an N-terminal focal adhesion kinase fragment cleaved by resveratrol contained the FERM (band 4.1, ezrin, radixin, and moesin)-kinase domain. Furthermore, resveratrol inhibited lipopolysaccharide-stimulated adhesion of THP-1 human monocytes by decreased expression of ICAM-1 (intercellular adhesion molecule-1). A decreased ICAM-1 level was also observed in the left carotid artery of mice treated with resveratrol. To understand the relationship between resveratrol-induced antiinflammation and focal adhesion disruption, endothelial cells were transfected with FERM-kinase. Ectopically expressed FERM-kinase, the resveratrol-cleaved focal adhesion kinase fragment, was found in the nuclear fraction and inhibited the transcription level of icam-1 via the Nrf2 (nuclear factor erythroid 2-related factor 2)-antioxidant response element complex. Finally, ectopically expressed FERM-kinase blocked tumor necrosis factor-α- or IL- (interleukin) stimulated monocytic binding to endothelial cells. Conclusions- Our results show that resveratrol inhibits the expression of ICAM-1 via transcriptional regulation of the FERM-kinase and Nrf2 interaction, thereby blocking monocyte adhesion. These suppressive effects on the inflammatory mechanism suggest that resveratrol delayed the onset of atherosclerosis.

Neuroprotective Effect of ß-Lapachone in MPTP-Induced Parkinson's Disease Mouse Model: Involvement of Astroglial p-AMPK/Nrf2/HO-1 Signaling Pathways.

Parkinson's disease is a neurodegenerative disease characterized by the progressive loss of dopaminergic neurons within the substantia nigra pars compacta. In the present study, we investigated whether ß-Lapachone (ß-LAP), a natural naphthoquinone compound isolated from the lapacho tree (Tabebuia avellanedae), elicits neuroprotective effects in a 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP)-induced Parkinson's disease mouse model. ß-LAP reduced the tyrosine hydroxylase (TH)-immunoreactive fiber loss induced by MPTP in the dorsolateral striatum, and alleviated motor dysfunction as determined by the rotarod test. In addition, ß-LAP protected against MPTP-induced loss of TH positive neurons, and upregulated B-cell lymphoma 2 protein (Bcl-2) expression in the substantia nigra. Based on previous reports on the neuroprotective role of nuclear factor-E2-related factor-2 (Nrf2) in neurodegenerative diseases, we investigated whether ß-LAP induces upregulation of the Nrf2-hemeoxygenae-1 (HO-1) signaling pathway molecules in MPTP-injected mouse brains. Western blot and immunohistochemical analyses indicated that ß-LAP increased HO-1 expression in glial fibrillary acidic protein-positive astrocytes. Moreover, ß-LAP increased the nuclear translocation and DNA binding activity of Nrf2, and the phosphorylation of upstream adenosine monophosphate-activated protein kinase (AMPK). ß-LAP also increased the localization of p-AMPK and Nrf2 in astrocytes. Collectively, our data suggest that ß-LAP exerts neuroprotective effect in MPTP-injected mice by upregulating the p-AMPK/Nrf2/HO-1 signaling pathways in astrocytes.

Anti-inflammatory and anti-oxidant mechanisms of an MMP-8 inhibitor in lipoteichoic acid-stimulated rat primary astrocytes: involvement of NF-κB, Nrf2, and PPAR-γ signaling pathways.

BACKGROUND: Recent evidence suggests that reactive astrocytes play an important role in neuroinflammation and neurodegenerative diseases. Thus, controlling astrocyte reactivity has been suggested as a promising strategy for treating neurodegenerative diseases. In the present study, we investigated whether a matrix metalloproteinase (MMP)-8 inhibitor, M8I, could control neuroinflammation in lipoteichoic acid (LTA)-stimulated rat primary astrocytes. METHODS: The effects of M8I on the expression of inducible nitric oxide synthase, cytokines, and MMPs were examined in LTA-stimulated rat primary astrocytes by ELISA, RT-PCR, and Western blot analysis. The effects of M8I on reactive oxygen species (ROS) generation and phase II antioxidant enzyme expression were examined by the DCF-DA assay, RT-PCR, and Western blot analysis. The detailed molecular mechanisms underlying the anti-inflammatory and antioxidant effects of M8I were analyzed by the electrophoretic mobility shift assay, the reporter gene assay, Western blot, and RT-PCR analysis. RESULTS: Treatment with LTA, a major cell wall component of Gram-positive bacteria, led to astrocyte activation and induced the expression of inflammatory molecules such as iNOS, COX-2, and pro-inflammatory cytokines. In addition, LTA induced the expression of MMPs such as MMP-1, MMP-3, MMP-8, MMP-9, and MMP-13 in rat primary astrocytes. Based on previous reports showing that MMP-8 plays a role as a proinflammatory mediator in microglia, we investigated whether MMP-8 is also involved in inflammatory reactions of reactive astrocytes. We found that treatment of astrocytes with M8I significantly inhibited LTA-induced expression of iNOS, TNF-α, IL-1ß, IL-6, and TLR-2. In addition, M8I inhibited LTA-induced NF-κB, MAP kinase, and Akt activities, while it increased the anti-inflammatory PPAR-γ activities. Moreover, M8I showed antioxidant effects by suppressing ROS production in LTA- or H2O2-stimulated astrocytes. Interestingly, M8I increased the expression of phase II antioxidant enzymes such as hemeoxygenase-1, NQO1, catalase, and MnSOD by modulating the Nrf2/ARE signaling pathway. CONCLUSIONS: The data collectively suggest the therapeutic potential of an MMP-8 inhibitor in neuroinflammatory disorders that are associated with astrocyte reactivity.

Sulforaphane rescues amyloid-ß peptide-mediated decrease in MerTK expression through its anti-inflammatory effect in human THP-1 macrophages.

BACKGROUND: Mer tyrosine kinase (MerTK) activity necessary for amyloid-stimulated phagocytosis strongly implicates that MerTK dysregulation might contribute to chronic inflammation implicated in Alzheimer's disease (AD) pathology. However, the precise mechanism involved in the regulation of MerTK expression by amyloid-ß (Aß) in proinflammatory environment has not yet been ascertained. METHODS: The objective of this study was to determine the underlying mechanism involved in Aß-mediated decrease in MerTK expression through Aß-mediated regulation of MerTK expression and its modulation by sulforaphane in human THP-1 macrophages challenged with Aß1-42. We used protein preparation, Ca2+ influx fluorescence imaging, nuclear fractionation, Western blotting techniques, and small interfering RNA (siRNA) knockdown to perform our study. RESULTS: Aß1-42 elicited a marked decrease in MerTK expression along with increased intracellular Ca2+ level and induction of proinflammatory cytokines such as IL-1ß and TNF-α. Ionomycin A and thapsigargin also increased intracellular Ca2+ levels and production of IL-1ß and TNF-α, mimicking the effect of Aß1-42. In contrast, the Aß1-42-evoked responses were attenuated by depletion of Ca2+ with ethylene glycol tetraacetic acid. Furthermore, recombinant IL-1ß or TNF-α elicited a decrease in MerTK expression. However, immunodepletion of IL-1ß or TNF-α with neutralizing antibodies significantly inhibited Aß1-42-mediated downregulation of MerTK expression. Notably, sulforaphane treatment potently inhibited Aß1-42-induced intracellular Ca2+ level and rescued the decrease in MerTK expression by blocking nuclear factor-κB (NF-κB) nuclear translocation, thereby decreasing IL-1ß and TNF-α production upon Aß1-42 stimulation. Such adverse effects of sulforaphane were replicated by BAY 11-7082, a NF-κB inhibitor. Moreover, sulforaphane's anti-inflammatory effects on Aß1-42-induced production of IL-1ß and TNF-α were significantly diminished by siRNA-mediated knockdown of MerTK, confirming a critical role of MerTK in suppressing Aß1-42-induced innate immune response. CONCLUSION: These findings implicate that targeting of MerTK with phytochemical sulforaphane as a mechanism for preventing Aß1-42-induced neuroinflammation has potential to be applied in AD therapeutics.

Galangin Suppresses Pro-Inflammatory Gene Expression in Polyinosinic-Polycytidylic Acid-Stimulated Microglial Cells.

Galangin (3,5,7-trihydroxyflavone) is a polyphenolic compound abundant in honey and medicinal herbs, such as Alpinia officinarum. In this study, we investigated the anti-inflammatory effects of galangin under in vitro and in vivo neuroinflammatory conditions caused by polyinosinic-polycytidylic acid (poly(I:C)), a viral mimic dsRNA analog. Galangin suppressed the production of nitric oxide, reactive oxygen species, and pro-inflammatory cytokines in poly(I:C)-stimulated BV2 microglia. On the other hand, galangin enhanced anti-inflammatory interleukin (IL)-10 production. Galangin also suppressed the expression of pro-inflammatory markers in poly(I:C)-injected mouse brains. Further mechanistic studies showed that galangin inhibited poly(I:C)-induced nuclear factor (NF)-κB activity and phosphorylation of Akt without affecting MAP kinases. Interestingly, galangin increased the expression and transcriptional activity of peroxisome proliferator-activated receptor (PPAR)-γ, known to play an anti-inflammatory role. To investigate whether PPAR-γ is involved in the anti-inflammatory function of galangin, BV2 cells were pre-treated with PPAR-γ antagonist before treatment of galangin. We found that PPAR-γ antagonist significantly blocked galangin-mediated upregulation of IL-10 and attenuated the inhibition of tumor necrosis factor (TNF)-α and IL-6 in poly(I:C)-stimulated microglia. In conclusion, our data suggest that PI3K/Akt, NF-κB, and PPAR-γ play a pivotal role in mediating the anti-inflammatory effects of galangin in poly(I:C)-stimulated microglia.

Resveratrol Ameliorates Tau Hyperphosphorylation at Ser396 Site and Oxidative Damage in Rat Hippocampal Slices Exposed to Vanadate: Implication of ERK1/2 and GSK-3ß Signaling Cascades.

The objective of this study was to investigate the effect of resveratrol (a natural polyphenolic phytostilbene) on tau hyperphosphorylation and oxidative damage induced by sodium orthovanadate (Na3VO4), the prevalent species of vanadium (vanadate), in rat hippocampal slices. Our results showed that resveratrol significantly inhibited Na3VO4-induced hyperphosphorylation of tau at the Ser396 (p-S396-tau) site, which is upregulated in the hippocampus of Alzheimer's disease (AD) brains and principally linked to AD-associated cognitive dysfunction. Subsequent mechanistic studies revealed that reduction of ERK1/2 activation was involved in the inhibitory effect of resveratrol by inhibiting the ERK1/2 pathway with SL327 mimicking the aforementioned effect of resveratrol. Moreover, resveratrol potently induced GSK-3ß Ser9 phosphorylation and reduced Na3VO4-induced p-S396-tau levels, which were markedly replicated by pharmacologic inhibition of GSK-3ß with LiCl. These results indicate that resveratrol could suppress Na3VO4-induced p-S396-tau levels via downregulating ERK1/2 and GSK-3ß signaling cascades in rat hippocampal slices. In addition, resveratrol diminished the increased extracellular reactive oxygen species generation and hippocampal toxicity upon long-term exposure to Na3VO4 or FeCl2. Our findings strongly support the notion that resveratrol may serve as a potential nutraceutical agent for AD.

Suppression of neuroinflammation by matrix metalloproteinase-8 inhibitor in aged normal and LRRK2 G2019S Parkinson's disease model mice challenged with lipopolysaccharide.

Microglial priming is caused by aging and neurodegenerative diseases, and is characterized by an exaggerated microglial inflammatory response to secondary and sub-threshold challenges. In the present study, we examined the effects of the matrix metalloproteinase-8 (MMP-8) inhibitor (M8I) on the brain of aged normal and leucine-rich repeat kinase 2 (LRRK2) G2019S Parkinson's disease (PD) model mice systemically stimulated with lipopolysaccharide (LPS). The results indicated that Iba-1 positive microglia and GFAP-positive astrocytes, which were increased by LPS, significantly decreased by M8I in aged normal and PD model mice. M8I also decreased the expression of pro-inflammatory markers in the hippocampus and midbrain of aged normal and PD model mice challenged with LPS, while it also improved the motor coordination of aged normal mice after LPS challenge in rotor rod test and the general crossing locomotor activities of LPS-treated LRRK2G2019S PD mice after LPS challenge in open field test. To assess the effects of M8I in an in vitro priming model, BV2 microglia were pretreated with macrophage colony-stimulating factor (CSF)-1 or interleukin (IL)-34, and subsequently stimulated with LPS or polyinosinic-polycytidylic acid (poly[I:C]). M8I inhibited the LPS- or poly(I:C)-induced production of the tumor necrosis factor-α and nitric oxide, alone or in combination with CSF-1 or IL-34. Collectively, the data suggested that M8I has a therapeutic potential in treating neurodegenerative diseases that are aggravated by systemic inflammation.

Anti-inflammatory mechanism of galangin in lipopolysaccharide-stimulated microglia: Critical role of PPAR-γ signaling pathway.

Since microglia-associated neuroinflammation plays a pivotal role in the progression of neurodegenerative diseases, controlling microglial activation has been suggested as a potential therapeutic strategy. Here, we investigated the anti-inflammatory effects of galangin (3,5,7-trihydroxyflavone) in microglia and analyzed the underlying molecular mechanisms. Galangin inhibited the expression of inducible nitric oxide synthase (iNOS) and pro-inflammatory cytokines and enhanced the expression of anti-inflammatory interleukin (IL)-10 in lipopolysaccharide (LPS)-stimulated BV2 microglia. Galangin also suppressed microglial activation and the expression of pro-inflammatory markers in LPS-injected mouse brains. The results of mechanistic studies have shown that galangin inhibited LPS-induced phosphorylation of p38 mitogen activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK), phosphatidylinositol 3-kinase (PI3K)/Akt, and nuclear factor (NF)-κB activity. On the contrary, galangin increased the activity of transcription factors, such as nuclear factor-E2-related factor 2 (Nrf2), cAMP response element-binding protein (CREB), and peroxisome proliferator-activated receptor (PPAR)-γ, known to play an anti-inflammatory role. In addition, galangin showed antioxidant effects by suppressing the expression of NADPH oxidase subunits p47phox and gp91phox, and by enhancing hemeoxygenase-1. We then investigated whether PPAR-γ was involved in the anti-inflammatory function of galangin. Pretreatment with a PPAR-γ antagonist or siRNA significantly blocked galangin-mediated upregulation of IL-10 and attenuated the inhibition of tumor necrosis factor (TNF)-α, nitric oxide (NO), and IL-6 in LPS-stimulated microglia. Moreover, the PPAR-γ antagonist reversed the effects of galangin on NF-κB, Nrf2, and CREB. Altogether, our data suggest that PPAR-γ plays a key role in mediating the anti-inflammatory effects of galangin by modulating the NF-κB and Nrf2/CREB signaling pathways.

Anti-inflammatory mechanism of lonchocarpine in LPS- or poly(I:C)-induced neuroinflammation.

Neuroinflammation plays an important role in the progression of various neurodegenerative diseases. In this study, we investigated the anti-inflammatory effects of lonchocarpine, a natural compound isolated from Abrus precatorius, under in vitro and in vivo neuroinflammatory conditions induced by challenge with lipopolysaccharide (LPS)- or polyinosinic-polycytidylic acid (poly(I:C)). Lonchocarpine suppressed the expression of iNOS and proinflammatory cytokines in LPS or poly(I:C)-stimulated BV2 microglial cells. These anti-inflammatory effects were verified in brains of mice with systemic inflammation induced by administration of LPS or poly(I:C). Lonchocarpine reduced the number of Iba-1-positive activated microglia, and suppressed the mRNA expression of various proinflammatory markers in the cortex of LPS- or poly(I:C)-injected mice. Molecular mechanistic experiments showed that lonchocarpine inhibited NF-κB activity by reducing the phosphorylation and degradation of IκBα in LPS- or poly(I:C)-stimulated BV2 cells. Analysis of further upstream signaling pathways in LPS-stimulated microglia showed that lonchocarpine inhibited the phosphorylation of IκB kinase and TGFß-activated kinase 1 (TAK1). Moreover, lonchocarpine suppressed the interaction of myeloid differentiation factor 88 (MyD88) and intereleukin-1 receptor-associated kinase 4 (IRAK4). These data suggest that toll-like receptor 4 downstream signals such as MyD88/IRAK4-TAK1-NF-κB are at least partly involved in the anti-inflammatory mechanism of lonchocarpine in LPS-stimulated microglia. Its strong anti-inflammatory effects may make lonchocarpine an effective preventative drug for neuroinflammatory disorders that are associated with systemic inflammation.

Suppression of Lipopolysaccharide-Induced Neuroinflammation by Morin via MAPK, PI3K/Akt, and PKA/HO-1 Signaling Pathway Modulation.

Morin is a flavonoid isolated from certain fruits and Chinese herbs and is known to possess various medicinal properties. In this study, we investigated the anti-inflammatory effects of morin on lipopolysaccharide (LPS)-induced microglial activation, both in vitro and in vivo. We found that morin inhibited inducible nitric oxide synthase (iNOS) and pro-inflammatory cytokines in LPS-stimulated BV2 microglial cells. Furthermore, morin suppressed the microglial activation and cytokine expression in the brains of LPS-stimulated mice. Subsequent mechanistic studies revealed that morin inhibited the action of LPS-activated mitogen-activated protein kinases (MAPKs), protein kinase B (Akt) phosphorylation, nuclear factor-κB (NF-κB), and activating protein-1 (AP-1). Further, the phosphorylation and DNA binding activity of cAMP responsive element binding protein (CREB) was enhanced by morin. Moreover, morin suppressed the LPS-induced expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, while it increased heme oxygenase-1 (HO-1) expression and nuclear factor erythroid 2-related factor 2 (Nrf2) activation. Therefore, our data suggest that morin exerts anti-inflammatory effects in LPS-stimulated microglia by downregulating MAPK and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways while upregulating protein kinase A (PKA)/CREB and Nrf2/HO-1 signaling pathways.

ß-Lapachone increases phase II antioxidant enzyme expression via NQO1-AMPK/PI3K-Nrf2/ARE signaling in rat primary astrocytes.

ß-Lapachone (ß-LAP) is a naturally occurring quinine that exerts a number of pharmacological actions including antibacterial, antifungal, antimalarial, and antitumor activities. In the present study, we investigated whether ß-LAP has an antioxidant effect in rat primary astrocytes. ß-LAP suppressed intracellular reactive oxygen species (ROS) production induced by hydrogen peroxide and inhibited astroglial cell death. It also increased astrocytic expression of phase II antioxidant enzymes such as heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1), manganese superoxide dismutase (MnSOD), and catalase. Further mechanistic studies revealed that ß-LAP activated AMPK and Akt, and pretreatment of cells with an AMPK inhibitor (compound C) or PI3K/Akt inhibitor (LY294002) suppressed ß-LAP-induced antioxidant enzyme expression by inhibiting Nrf2/antioxidant response element (ARE) signaling. Compound C also decreased Akt phosphorylation, suggesting that AMPK is upstream of PI3K/Akt. Furthermore, the AMPK activator 5-aminoimidazole-4-carboxamide 1-ß-d-ribofuranoside mimicked the effect of ß-LAP by increasing Akt phosphorylation and ARE-mediated transcription, suggesting that AMPK plays a pivotal role in ß-LAP-mediated antioxidant enzyme expression. Because ß-LAP effects are usually associated with NQO1 activity, we examined the effect of NQO1 knockdown on antioxidant enzyme expression. Small interfering RNA (siRNA) specific for NQO1 inhibited ß-LAP-induced AMPK/Akt phosphorylation and downstream antioxidant enzyme expression. Collectively, the results suggest that ß-LAP increases antioxidant enzyme gene expression in astrocytes by modulating NQO1-AMPK/PI3K-Nrf2/ARE signaling.

Anti-Inflammatory and Antioxidant Mechanism of Tangeretin in Activated Microglia.

Tangeretin, a flavonoid from citrus fruit peels, has been proven to play an important role in anti-inflammatory responses and neuroprotective effects in several disease models, but further study is necessary for elucidating the detailed mechanisms of these effects. In this study, we examined the anti-inflammatory effect of tangeretin in lipopolysaccharide (LPS)-stimulated microglia. We first observed that tangeretin inhibited LPS-induced production of nitric oxide, tumor necrosis factor alpha, interleukin (IL)-6, and IL-1ß, as well as LPS-induced mRNA expression of inducible nitric oxide synthases and cytokines. Additionally, we found that the activities, mRNA levels, and protein levels of matrix metalloproteinase (MMP)-3 and MMP-8 were inhibited, while the expression of tissue inhibitor of metalloproteinase-2 was enhanced by tangeretin in LPS-stimulated microglia. Further mechanistic study showed that tangeretin suppressed LPS-induced phosphorylation of mitogen-activated protein kinases and Akt. Also, tangeretin inhibited nuclear factor-κB by upregulating sirtuin 1 and 5'-adenosine monophosphate-activated protein kinase. We further demonstrated the antioxidant effect of tangeretin by showing that tangeretin inhibited reactive oxygen species production and p47(phox) phosphorylation, while enhancing the expression of heme oxygenase-1 and the DNA binding activity of nuclear factor-erythroid 2-related factor 2 to the antioxidant response element in LPS-stimulated microglia. Taken together, the results of the present study demonstrate that tangeretin possesses a potent anti-inflammatory and antioxidant effect in microglia.