Correction: Kim et al. Neuroprotective Effect of Statins in a Rat Model of Chronic Ocular Hypertension. Int. J. Mol. Sci. 2021, 22, 12500.

In the original publication [...].

Neuroprotective Effect of Statins in a Rat Model of Chronic Ocular Hypertension.

Glaucoma is an optic neuropathy in which the degeneration of retinal ganglion cells (RGCs) results in irreversible vison loss. Therefore, neuroprotection of RGCs from glaucomatous afflictions is crucial for glaucoma treatment. In this study, we aimed to investigate the beneficial effects of statins in the protection of RGCs using a rat model. Glaucomatous injury was induced in rats by chronic ocular hypertension (OHT) achieved after performing a circumlimbal suture. The rats were given either statins such as simvastatin and atorvastatin or a solvent weekly for 6 weeks. Retina sections underwent hematoxylin and eosin, Brn3a, or cleaved casepase-3 staining to evaluate RGC survival. In addition, modulation of glial activation was assessed. While the retinas without statin treatment exhibited increased RGC death due to chronic OHT, statins promoted the survival of RGCs and reduced apoptosis. Statins also suppressed chronic OHT-mediated glial activation in the retina. Our results demonstrate that statins exert neuroprotective effects in rat retinas exposed to chronic OHT, which may support the prospect of statins being a glaucoma treatment.

Statins reduce TGF-beta2-modulation of the extracellular matrix in cultured astrocytes of the human optic nerve head.

Statins are cholesterol lowering drugs and have shown beneficial effects on glaucoma. With regard to the mechanism of statin action on glaucoma, we investigated the effects of statins on transforming growth factor-beta 2 (TGF-ß2)-induced expression of extracellular matrix (ECM) proteins in human astrocytes of the optic nerve head (ONH) lamina cribrosa (LC). By using primary human ONH astrocytes, we found that both simvastatin and lovastatin inhibited TGF-ß2-mediated expression of ECM proteins such as connective tissue growth factor, collagen I, fibronectin, and plasminogen activator inhibitor-1. Suppression of ECM related proteins is due to inhibition of Smad2/3 activation as statins inhibit TGF-ß2-induced Smad2 phosphorylation and Smad2/3 nuclear accumulation. In ONH astrocytes, TGF-ß2 does not induce MAPK activation. In this study we found an anti-fibrotic effect of statins in human astrocytes of the ONH and identified TGF-ß2 as a mediator of statin action, which may support a beneficial role for statins in blocking glaucomatous axonal damage induced by ECM remodeling.

Matrix metalloproteinase-8 plays a pivotal role in neuroinflammation by modulating TNF-α activation.

Matrix metalloproteinases (MMPs) play important roles in normal brain development and synaptic plasticity, although aberrant expression of MMPs leads to brain damage, including blood-brain barrier disruption, inflammation, demyelination, and neuronal cell death. In this article, we report that MMP-8 is upregulated in LPS-stimulated BV2 microglial cells and primary cultured microglia, and treatment of MMP-8 inhibitor (M8I) or MMP-8 short hairpin RNA suppresses proinflammatory molecules, particularly TNF-α secretion. Subsequent experiments showed that MMP-8 exhibits TNF-α-converting enzyme (TACE) activity by cleaving the prodomain of TNF-α (A(74)/Q(75), A(76)/V(77) residues) and, furthermore, that M8I inhibits TACE activity more efficiently than TAPI-0, a general TACE inhibitor. Biochemical analysis of the underlying anti-inflammatory mechanisms of M8I revealed that it inhibits MAPK phosphorylation, NF-κB/AP-1 activity, and reactive oxygen species production. Further support for the proinflammatory role of microglial MMP-8 was obtained from an in vivo animal model of neuroinflammatory disorder. MMP-8 is upregulated in septic conditions, particularly in microglia. Administration of M8I or MMP-8 short hairpin RNA significantly inhibits microglial activation and expression/secretion of TNF-α in brain tissue, serum, and cerebrospinal fluid of LPS-induced septic mice. These results demonstrate that MMP-8 critically mediates microglial activation by modulating TNF-α activity, which may explain neuroinflammation in septic mouse brain.

Visceral adipose tissue inflammation is associated with age-related brain changes and ischemic brain damage in aged mice.

Visceral adipose tissue is accumulated with aging. An increase in visceral fat accompanied by low-grade inflammation is associated with several adult-onset diseases. However, the effects of visceral adipose tissue inflammation on the normal and ischemic brains of aged are not clearly defined. To examine the role of visceral adipose tissue inflammation, we evaluated inflammatory cytokines in the serum, visceral adipose tissue, and brain as well as blood-brain barrier (BBB) permeability in aged male mice (20 months) underwent sham or visceral fat removal surgery compared with the young mice (2.5 months). Additionally, ischemic brain injury was compared in young and aged mice with sham and visceral fat removal surgery. Interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α levels in examined organs were increased in aged mice compared with the young mice, and these levels were reduced in the mice with visceral fat removal. Increased BBB permeability with reduced expression of tight junction proteins in aged sham mice were also decreased in mice with visceral fat removal. After focal ischemic injury, aged mice with visceral fat removal showed a reduction in infarct volumes, BBB permeability, and levels of proinflammatory cytokines in the ischemic brain compared with sham mice, although the neurological outcomes were not significantly improved. In addition, further upregulated visceral adipose tissue inflammation in response to ischemic brain injury was attenuated in mice with visceral fat removal. These results suggest that visceral adipose tissue inflammation is associated with age-related changes in the brain and contributes to the ischemic brain damage in the aged mice. We suggest that visceral adiposity should be considered as a factor affecting brain health and ischemic brain damage in the aged population.

Antifibrotic effects of pirfenidone on Tenon's fibroblasts in glaucomatous eyes: comparison with mitomycin C and 5-fluorouracil.

PURPOSE: The purpose of this study was to evaluate the antifibrotic effects of pirfenidone (PFD) on primary cultured human Tenon's fibroblasts (HTFs) from primary open-angle glaucoma (POAG) eyes, compared to mitomicin C (MMC) and 5-fluorouracil (5-FU). MATERIALS AND METHODS: Samples of human Tenon's capsule were obtained during respective surgeries from three groups of patients: patients with cataract (CAT group), patients with POAG who underwent glaucoma filtration surgery (GFS) (POAG1 group), and patients with POAG who underwent GFS due to failed bleb of previous GFS (POAG2 group). Cell toxicity, cell migration, and the expression level of α-smooth muscle actin (α-SMA) protein were evaluated in primary cultured HTFs from the three patient groups after treatment (PFD, MMC, or 5-FU). RESULTS: Overall, cell viability after PFD treatment was higher compared to MMC treatment (82.3 ± 5.1 % vs 56.7 ± 3.8 %; p = 0.001) and comparable to 5-FU treatment (82.3 ± 5.1 % vs 85.7 ± 10.7 %, p = 0.214) at the same concentration (0.4 mg/ml). Both 0.3 mg/ml PFD and 0.1 mg/ml MMC inhibited cell migration compared to control (without treatment) cells (p = 0.014 and 0.005, respectively), while 0.2 mg/ml 5-FU showed the highest degree of cell migration among the three agents in the POAG1 group (PFD vs MMC vs 5-FU; 29.5 ± 2.1 % vs 34.5 ± 0.7 % vs 76.0 ± 8.5 %, PFD vs MMC; p = 1.000, PFD vs 5-FU; p = 0.008, MMC vs 5-FU; p = 0.011). PFD (0.1 or 0.3 mg/ml) and MMC (0.05 and 0.1 mg/ml) treatment significantly reduced the protein expression level of α-SMA in the POAG 1 group (all p < 0.05), and the α-SMA protein level following treatment with 0.3 mg/ml PFD was lower than that of 0.1 mg/ml MMC (p = 0.040). CONCLUSION: PFD showed less cytotoxicity compared to MMC. PFD and MMC inhibited cell migration and reduced α-SMA protein expression levels, while 5-FU showed neither inhibition of cell migration nor reduction in α-SMA expression level. These findings indicate PFD as a potential adjunctive antifibrotic agent to prevent bleb failure during GFS.

Anti-inflammatory mechanism of exogenous C2 ceramide in lipopolysaccharide-stimulated microglia.

Ceramide is a major molecule among the sphingolipid metabolites which are produced in the brain and other organs and act as intracellular second messengers. Although a variety of physiological roles of ceramide have been reported in the periphery and central nervous systems, the role of ceramide in microglial activation has not been clearly demonstrated. In the present study, we examined the effects of exogenous cell permeable short chain ceramides on microglial activation in vitro and in vivo. We found that C2, C6, and C8 ceramide and C8 ceramide-1-phosphate inhibited iNOS and proinflammatory cytokines in lipopolysaccharide (LPS)-stimulated BV2 microglial cells and rat primary microglia. In addition, the administration of C2 ceramide suppressed microglial activation in the brains of LPS-exposed mice. By HPLC and LC/MS/MS analyses, we found that C2 ceramide on its own, rather than its modified form (i.e. ceramide-1-phosphate or long chain ceramides), mainly work by penetrating into microglial cells. Further mechanistic studies by using the most effective C2 ceramide among the short chain ceramides tested, revealed that C2 ceramide exerts anti-inflammatory effects via inhibition of the ROS, MAPKs, PI3K/Akt, and Jak/STAT pathways with upregulation of PKA and hemeoxygenase-1 expressions. Interestingly, we found that C2 ceramide inhibits TLR4 signaling by interfering with LPS and TLR4 interactions. Therefore, our data collectively suggests the therapeutic potential of short chain ceramides such as C2 for neuroinflammatory disorders such as Alzheimer's disease and Parkinson's disease.

Noggin improves ischemic brain tissue repair and promotes alternative activation of microglia in mice.

We previously reported that bone morphogenetic proteins (BMPs) and their endogenous antagonist noggin are expressed in the brain weeks after an ischemic insult. Here, to define their roles in ischemic brain tissue repair and remodeling, we infused recombinant BMP7 or noggin into the ipsilateral ventricle of mice for 2weeks starting 2weeks after transient middle cerebral artery occlusion (MCAO). Four weeks after MCAO, we measured ischemic brain volume, functional recovery, and molecules related to neurogenesis and angiogenesis such as synaptophysin, GAP-43, and VEGF. Noggin-treated mice but not BMP7-treated mice showed preserved ipsilateral brain volume and reduced neurological deficits compared with artificial cerebrospinal fluids (aCSF)-treated mice. Noggin treatment also decreased glial scar thickness, increased levels of GAP-43 and VEGF protein, and increased the number of Iba1-positive activated microglia in the ipsilateral brain. Furthermore, noggin treatment decreased M1 markers (IL-1ß, TNF-α, IL-12, CCL2 and CD86) and increased M2 markers (IL-1ra, IL-10, arginase 1, CD206 and Ym1) of activated microglia, suggesting a shift from M1 to M2 phenotypes. These results suggest that noggin improves functional recovery from ischemic stroke and enhances alternatively activated microglia, thereby promoting tissue repair and remodeling.

Noggin-mediated effects on metabolite profiles of microglia and oligodendrocytes after ischemic insult.

Recent studies show that shifts in energy metabolism in activated microglia are linked to their functions and immune responses in the ischemic brain. We previously reported that an antagonist of the bone morphogenetic protein, noggin, enhanced myelination in the ischemic brain during the chronic phase, and conditioned media (CM) from activated BV2 microglia treated with noggin after ischemia/reperfusion (I/R) increased the expression of myelin basic protein (MBP) in oligodendrocytes (MO3.13). To determine whether noggin induced changes in cell metabolism, metabolite profiles in BV2 and MO3.13 cells were analyzed by untargeted metabolomics using 1H nuclear magnetic resonance spectroscopy. Compared to vehicle-treated BV2 cells, noggin treatment (100 ng/mL for 3 h after I/R) suppressed the I/R-induced increase in intracellular glucose and lactate levels but increased extracellular levels of glucose and several amino acids. When MO3.13 cells were exposed to noggin CM from BV2 cells, most of the vehicle CM-induced changes in the levels of metabolites such as choline, formate, and intermediates of oxidative phosphorylation were reversed, while the glycerol level was markedly increased. An increase in glycerol level was also observed in the noggin-treated ischemic brain and was further supported by the expression of glycerol-3-phosphate dehydrogenase 1 (required for glycerol synthesis) in the cytoplasm of MBP-positive oligodendrocytes in the ischemic brains treated with noggin. These results suggest that noggin-induced changes in the metabolism of microglia provide a favorable environment for myelin synthesis in oligodendrocytes during the recovery phase after ischemic stroke.

PB101, a VEGF- and PlGF-targeting decoy protein, enhances antitumor immunity and suppresses tumor progression and metastasis.

Antiangiogenic therapy is a recognized method for countering the immunosuppressive tumor microenvironment (TME) and improving anti-tumor immunity. PB101 is a glycosylated decoy receptor that binds to VEGF-A and PlGF with high affinity, based on the VEGFR1 backbone. Here, we elucidated PB101-induced remodeling of tumor angiogenesis and immunity, which enhances anti-PD-L1 immune checkpoint blockade. PB101 inhibited tumor growth by suppressing angiogenesis and enhancing CD8+ T cell infiltration into the tumors. PB101 induced robust reprogramming of antitumor immunity and activates intratumoral CD8+ T cells. Anti-tumor efficacy of PB101 is mostly dependent on CD8+ T cells and IFN-γ. PB101 reprograms tumor immunity in a manner distinct from that of the conventional VEGF decoy receptor, VEGF-trap. With its potent immune-modulating capability, PB101 synergizes with an anti-PD-L1, triggering strengthened antitumor immunity. Combining PB101 and anti-PD-L1 could establish durable protective immunity against tumor recurrence and metastasis. The findings of this study offer scientific rationales for further clinical development of PB101, particularly when used in combination with immune checkpoint inhibitors, as a potential treatment for advanced cancers.

Conserved aquaporin 4 levels associated with reduction of brain edema are mediated by estrogen in the ischemic brain after experimental stroke.

Aquaporin 4 (AQP4), the most abundant water channel protein in the brain, is involved in brain edema induced by ischemic insults. To evaluate whether the neuroprotective effects of estrogen are associated with AQP4 expression and edema formation, changes in AQP levels and ischemic edema were examined in the brains of male and female mice subjected to transient middle cerebral artery occlusion. Infarct volume and edema formation were markedly less in females than in males. AQP4 expression in the ischemic cortex of females was relatively well preserved, whereas it was significantly decreased in males. These effects disappeared in ovariectomized females but were reversed by estrogen replacement. Furthermore, AQP4 expression was decreased with increased brain edema in females treated with ICI182,780, an estrogen receptor antagonist. These findings suggest that the estrogen effect on the reduction of ischemic brain edema is associated with the preserved level of AQP4 that is partly mediated by estrogen receptors.

Anti-inflammatory mechanism of compound K in activated microglia and its neuroprotective effect on experimental stroke in mice.

Microglial activation plays a pivotal role in the pathogenesis of various neurologic disorders, such as cerebral ischemia, Alzheimer's disease, and Parkinson's disease. Thus, controlling microglial activation is a promising therapeutic strategy for such brain diseases. In the present study, we found that a ginseng saponin metabolite, compound K [20-O-D-glucopyranosyl-20(S)-protopanaxadiol], inhibited the expressions of inducible nitric-oxide synthase, proinflammatory cytokines, monocyte chemotactic protein-1, matrix metalloproteinase-3, and matrix metalloproteinase-9 in lipopolysaccharide (LPS)-stimulated BV2 microglial cells and primary cultured microglia. Subsequent mechanistic studies revealed that compound K suppressed microglial activation via inhibiting reactive oxygen species, mitogen-activated protein kinases, and nuclear factor-κB/activator protein-1 activities with enhancement of heme oxygenase-1/antioxidant response element signaling. To address the anti-inflammatory effects of compound K in vivo, we used two brain disease models of mice: sepsis (systemic inflammation) and cerebral ischemia. Compound K reduced the number of Iba1-positive activated microglia and inhibited the expressions of tumor necrosis factor-α and interleukin-1ß in the LPS-induced sepsis brain. Furthermore, compound K reduced the infarct volume of ischemic brain induced by middle cerebral artery occlusion and suppressed microglial activation in the ischemic cortex. The results collectively suggest that compound K is a promising agent for prevention and/or treatment of cerebral ischemia and other neuroinflammatory disorders.

Different temporal patterns in the expressions of bone morphogenetic proteins and noggin during astroglial scar formation after ischemic stroke.

Bone morphogenetic proteins (BMPs) and their antagonists have roles in scar formation and regeneration after central nervous system injuries. However, temporal changes in their expression during astroglial scar formation in the ischemic brain are unknown. Here, we examined protein levels of BMP2, BMP7, and their antagonist noggin in the ischemic brain up to 4 weeks after experimental stroke in mice. BMP2 and BMP7 levels were increased from 1 to 4 weeks in the ischemic brain, and their expression was associated with astrogliosis. BMP7 expression was more intense and co-localized in reactive astrocytes in the ischemic subcortex at 1 week. Noggin expression began to increase after 2 weeks and was further increased at 4 weeks only in the ischemic subcortex, but the intensity was weak compared to the intensity of BMPs. Noggin was co-localized mainly in activated microglia. These findings show that expression of BMPs and noggin differed over time, in intensity and in types of cell, and suggest that BMPs and noggin have different roles in the processes of glial scar formation and neurorestoration in the ischemic brain.

Acute resveratrol treatment modulates multiple signaling pathways in the ischemic brain.

Resveratrol has several beneficial effects, including reductions of oxidative stress, inflammatory responses and apoptosis. It has been known that resveratrol is a sirtuin 1 (SIRT1) activator and protective effects of resveratrol are mediated by Akt and mitogen-activated protein kinases. However, it is not examined whether these pathways are regulated by resveratrol in the ischemic brain. Previously, we found that acute resveratrol treatment reduces brain injury induced by transient focal ischemic stroke. In the present study, we defined the signaling pathways modulated by resveratrol in ischemia by examining SIRT1 expression and phosphorylation of Akt, ERK1/2 and p38 in the ischemic cortex. Resveratrol increased expression of SIRT1 and phosphorylation of Akt and p38 but inhibited the increase in phosphorylation of ERK1/2. Gene and protein levels of peroxisome proliferator-activated receptor γ coactivator 1α, a downstream molecule of SIRT1, and mRNA levels of its target genes antioxidative superoxide dismutase 2 and uncoupling protein 2 were elevated. Resveratrol also increased phosphorylation of cyclic AMP-response-element-binding protein and transcription of the anti-apoptotic gene Bcl-2. These results suggest that various neuroprotective actions of resveratrol, including anti-oxidative, anti-apoptotic and inflammatory effects, are mediated via modulation of multiple signaling pathways in the ischemic brain.

The potential of BEN815 as an anti-inflammatory, antiviral and antioxidant agent for the treatment of COVID-19.

Background: The corona virus disease 2019 (COVID-19) pandemic has highlighted the fact that there are few effective antiviral agents for treating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Although the very recent development of vaccines is an extremely important breakthrough, it remains unclear how long-lived such vaccines will be. The development of new agents therefore remains an important goal. Purpose: Given the multifaceted pathology of COVID-19, a combinatorial formulation may provide an effective treatment. BEN815, a natural nutraceutical composed of extracts from guava leaves (Psidium guajava), green tea leaves (Camellia sinensis), and rose petals (Rosa hybrida), had previously shown to have a therapeutic effect on allergic rhinitis. We investigated whether BEN815 possesses anti-inflammatory, antiviral and antioxidant activities, since the combination of these effects could be useful for the treatment of COVID-19. Study design: We examined the anti-inflammatory effects of BEN815 and its principal active components quercetin and epigallocatechin gallate (EGCG) in lipopolysaccharide (LPS)-induced RAW264.7 cells and in an LPS-challenged mouse model of endotoxemia. We also assessed the antioxidant activity, and antiviral effect of BEN815, quercetin, and EGCG in SARS-CoV-2-infected Vero cells. Methods: The principal active ingredients in BEN815 were determined and quantified using HPLC. Changes in the levels of LPS-induced pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α were measured by ELISA. Changes in the expression levels of cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) were analyzed using western blotting. Antioxidant assay was performed using DPPH and ABTS assay. SARS-CoV-2 replication was measured by immunofluorescence staining. Results: BEN815 significantly suppressed the induction of IL-6 and TNF-α as well as COX-2 and iNOS in LPS-induced RAW264.7 cells. In addition, BEN815 protected against LPS-challenged endotoxic shock in mice. Two major constituents of BEN815, quercetin and EGCG, reduced the induction of IL-6 and TNF-α as well as COX-2 and iNOS synthase in LPS-induced RAW264.7 cells. BEN815, quercetin, and EGCG were also found to have antioxidant effects. Importantly, BEN815 and EGCG could inhibit SARS-CoV-2 replications in Vero cells. Conclusion: BEN815 is an anti-inflammatory, antiviral, and antioxidant natural agent that can be used to prevent and improve inflammation-related diseases, COVID-19.

Enhanced repair processes and iron uptake by ischemic preconditioning in the brain during the recovery phase after ischemic stroke.

Ischemic preconditioning (IP) reduces brain damage after subsequent ischemic strokes by activating endogenous protective mechanisms in rodents. Transient ischemic attack (TIA) induces tolerance in the human brain after ischemic strokes; defining mechanisms of IP effects may provide therapeutic targets to improve recovery of patients with ischemic strokes. Iron transported across the blood-brain barrier (BBB) is required for brain functions, including myelination, and its levels should be finely regulated to avoid harmful effects. This study aimed to determine whether IP enhances repair processes by modulating iron metabolism during the post-stroke chronic phase. Male mice were divided into sham and IP groups, and IP was induced 24 h before a transient focal ischemic stroke. Sensorimotor recovery was observed over 8 weeks after the stroke, and brain volumes and levels of proteins related to repair processes and iron metabolism in the ischemic brains were examined 8 weeks after the stroke. There was significantly less ischemic brain atrophy in the IP group than in the sham group, with no differences in sensorimotor recovery between the groups. Levels of tight junction proteins of BBB, neurites outgrowth markers, and myelin sheath proteins and markers for mature oligodendrocytes were significantly increased in the IP group. Iron import proteins, transferrin receptor 1 and DMT1, were also increased in the IP group. These results indicate that IP increases brain repair processes and iron uptake during the chronic phase after an ischemic stroke, and provide new insights to understand the molecular mechanisms of TIA effects on post-stroke recovery.

Induction of glioma apoptosis by microglia-secreted molecules: The role of nitric oxide and cathepsin B.

Microglia contributes significantly to brain tumor mass, particularly in astrocytic gliomas. Here, we examine the cytotoxic effects of soluble components secreted from microglia culture on glioma cells. Microglia conditioned culture medium (MCM) actively stimulated apoptotic death of glioma cells, and the effects of MCM prepared from LPS- or IFN-gamma-activated microglia were more pronounced. The cytotoxic effects were glioma-specific in that primary cultured rat astrocytes were not affected by MCM. A donor of peroxynitrite induced glioma-specific cell death. In addition, NO synthase inhibitor suppressed glioma cell death induced by activated MCM, indicating that NO is one of the key molecules responsible for glioma cytotoxicity mediated by activated MCM. However, since unstimulated resting microglia produces low or very limited level of NO, MCM may contain other critical molecule(s) that induce glioma apoptosis. To identify the proteins secreted in MCM, proteomic analysis was performed on control or activated medium. Among over 200 protein spots detected by Coomassie blue staining, we identified 26 constitutive and 28 LPS- or IFN-gamma-regulated MCM proteins. Several cathepsin proteases were markedly expressed, which were reduced upon activation. In particular, suppression of cathepsin B by the chemical inhibitors significantly reversed MCM-induced glioma cell death, implying a critical role of this protease in cytotoxicity. Our findings provide evidence on the functional implications of specific microglial-secreted proteins in glioma cytotoxicity, as well as a basis to develop a proteomic databank of both basal and activation-related proteins in microglia.

Glucosamine exerts a neuroprotective effect via suppression of inflammation in rat brain ischemia/reperfusion injury.

We investigated the neuroprotective effect of glucosamine (GlcN) in a rat middle cerebral artery occlusion model. At the highest dose used, intraperitoneal GlcN reduced infarct volume to 14.3% ± 7.4% that of untreated controls and afforded a reduction in motor impairment and neurological deficits. Neuroprotective effects were not reproduced by other amine sugars or acetylated-GlcN, and GlcN suppressed postischemic microglial activation. Moreover, GlcN suppressed lipopolysaccharide (LPS)-induced upregulation of proinflammatory mediators both in vivo and in culture systems using microglial or macrophage cells. The anti-inflammatory effects of GlcN were mainly attributable to its ability to inhibit nuclear factor kappaB (NF-κB) activation. GlcN inhibited LPS-induced nuclear translocation and DNA binding of p65 to both NF-κB consensus sequence and NF-κB binding sequence of inducible nitric oxide synthase promoter. In addition, we found that GlcN strongly repressed p65 transactivation in BV2 cells using Gal4-p65 chimeras system. P65 displayed increased O-GlcNAcylation in response to LPS; this effect was also reversed by GlcN. The LPS-induced increase in p65 O-GlcNAcylation was paralleled by an increase in interaction with O-GlcNAc transferase, which was reversed by GlcN. Finally, our results suggest that GlcN or its derivatives may serve as novel neuroprotective or anti-inflammatory agents.

Anti-inflammatory mechanism of ginsenoside Rh1 in lipopolysaccharide-stimulated microglia: critical role of the protein kinase A pathway and hemeoxygenase-1 expression.

Microglia activation plays a pivotal role in neurodegenerative diseases, and thus controlling microglial activation has been suggested as a promising therapeutic strategy for neurodegenerative diseases. In the present study, we showed that ginsenoside Rh1 inhibited inducible nitric oxide synthase, cyclooxygenase-2, and pro-inflammatory cytokine expression in lipopolysaccharide (LPS)-stimulated microglia, while Rh1 increased anti-inflammatory IL-10 and hemeoxygenase-1 (HO-1) expression. Suppression of microglial activation by Rh1 was also observed in the mouse brain following treatment with LPS. Subsequent mechanistic studies revealed that Rh1 inhibited LPS-induced MAPK phosphorylation and nuclear factor-κB (NF-κB)-mediated transcription without affecting NF-κB DNA binding. As the increase of pCREB (cAMP responsive element-binding protein) is known to result in suppression of NF-κB-mediated transcription, we examined whether Rh1 increased pCREB levels. As expected, Rh1 increased pCREB, which was shown to be related to the anti-inflammatory effect of Rh1 because pre-treatment with protein kinase A inhibitors attenuated the Rh1-mediated inhibition of nitric oxide production and the up-regulation of IL-10 and HO-1. Furthermore, treatment of HO-1 shRNA attenuated Rh1-mediated inhibition of nitric oxide and reactive oxygen species production. Through this study, we have demonstrated that protein kinase A and its downstream effector, HO-1, play a critical role in the anti-inflammatory mechanism of Rh1 by modulating pro- and anti-inflammatory molecules in activated microglia.

Syndecan-2 regulates cell migration in colon cancer cells through Tiam1-mediated Rac activation.

Expression of the cell surface adhesion receptor syndecan-2 is known to be involved in the regulation of cancer cell migration. However, the molecular mechanism of syndecan-2-mediated cell migration remains unknown. Here we report that Rac contributes to the regulation of syndecan-2-mediated cancer cell migration. Overexpression of syndecan-2 enhanced migration and invasion of human colon adenocarcinoma cells Caco-2 and HCT116 cells. In parallel with the increased cell migration/invasion, syndecan-2 overexpression enhanced Rac activity, while dominant negative Rac (RacN17) diminished syndecan-2-mediated increased cancer cell migration. In addition syndecan-2 expression increased membrane localization of Tiam1 and syndecan-2-mediated cell migration/invasion of Caco-2 cells was diminished when Tiam1 levels were knocked-down with small inhibitory RNAs. Furthermore, oligomerization-defective syndecan-2 mutants failed to increase membrane localization of Tiam1, activation of Rac and subsequent cell migration of both Caco-2 and HCT116 cells. Taken together, these results suggest that syndecan-2 regulates cell migration of colon carcinoma cells through Tiam1-dependent Rac activation in colon cancer cells.