Cyclooxygenase-2, prostaglandin E2, and microglial activation in prion diseases

Exogenous oxygen is required for prostanoid induction under brain ischemia as evidence for a novel regulatory mechanism

Previously, we and others reported a rapid and dramatic increase in brain prostanoids (PG), including prostaglandins, prostacyclins, and thromboxanes, under ischemia that is traditionally explained through the activation of esterified arachidonic acid (20:4n6) release by phospholipases as a substrate for cyclooxygenases (COX). However, the availability of another required COX substrate, oxygen, has not been considered in this mechanism. To address this mechanism for PG upregulation through oxygen availability, we analyzed mouse brain PG, free 20:4n6, and oxygen levels at different time points after ischemic onset using head-focused microwave irradiation (MW) to inactivate enzymes in situ before craniotomy. The oxygen half-life in the ischemic brain was 5.32 ± 0.45 s and dropped to undetectable levels within 12 s of ischemia onset, while there were no significant free 20:4n6 or PG changes at 30 s of ischemia. Furthermore, there was no significant PG increase at 2 and 10 min after ischemia onset compared to basal levels, while free 20:4n6 was increased ∼50 and ∼100 fold, respectively. However, PG increased ∼30-fold when ischemia was followed by craniotomy of nonMW tissue that provided oxygen for active enzymes. Moreover, craniotomy performed under anoxic conditions without MW did not result in PG induction, while exposure of these brains to atmospheric oxygen significantly induced PG. Our results indicate, for the first time, that oxygen availability is another important regulatory factor for PG production under ischemia. Further studies are required to investigate the physiological role of COX/PG regulation through tissue oxygen concentration.

Carthamus tinctorius Suppresses LPS-Induced Anti-Inflammatory Responses by Inhibiting the MAPKs/NF-κB Signaling Pathway in HaCaT Cells

This study aimed to elucidate the anti-inflammatory activity of C. tinctorius leaves by measuring inflammatory parameters such as nitric oxide (NO) production and mRNA expression of iNOS, interleukin-6 (IL-6), and IL-1β in lipopolysaccharide (LPS)-induced HaCaT cells. Further, the effect of C. tinctorius ethanol extract on the MAPKs/NF-κB signaling pathway was examined in HaCaT cells. The phytochemical profile of the ethanol extract of C. tinctorius leaves was determined using UPLC-QTOF-MS/MS. The results indicated that the ethanol extract of C. tinctorius effectively attenuated LPS-induced secretion of NO, IL-6, and IL-1β in HaCaT cells. Further, LPS-stimulated mRNA and protein expressions of iNOS were decreased by pre-treatment with C. tinctorius ethanol extract at the transcriptional level in HaCaT cells. Moreover, the ethanol extract of C. tinctorius suppressed NF-κB signaling in LPS-induced HaCaT cells. This suppression was mediated by MAPKs/NF-κB signaling, inhibiting the phosphorylation of p38 and p65 in HaCaT cells. However, there is no significant effect on the phosphorylation of JNK by the ethanol extract. The QTOF-MS/MS analysis revealed the identification of 27 components in the ethanol extract of C. tinctorius leaves. The data demonstrate that the ethanol extract of C. tinctorius leaves protects the LPS-induced HaCaT cells by inhibiting the expression of iNOS, IL-6, and IL-1β and suppressing the phosphorylation of the p38, p65, p-JNK via inactivation of MAPKs/NF-κB signaling pathway. These results demonstrate that C. tinctorius leaves may serve as a potential candidate to prevent inflammation-related diseases.

Pharmacological Treatment for Neuroinflammation in Stress-Related Disorder

Stress is an organism’s response to a biological or psychological stressor, a method of responding to threats. The autonomic nervous system and hypothalamic–pituitary–adrenal axis (HPA axis) regulate adaptation to acute stress and secrete hormones and excitatory amino acids. This process can induce excessive inflammatory reactions to the central nervous system (CNS) by HPA axis, glutamate, renin-angiotensin system (RAS) etc., under persistent stress conditions, resulting in neuroinflammation. Therefore, in order to treat stress-related neuroinflammation, the improvement effects of several mechanisms of receptor antagonist and pharmacological anti-inflammation treatment were studied. The N-methyl-D-aspartate (NMDA) receptor antagonist, peroxisome proliferator-activated receptor agonist, angiotensin-converting enzyme inhibitor etc., effectively improved neuroinflammation. The interesting fact is that not only can direct anti-inflammation treatment improve neuroinflammation, but so can stress reduction or pharmacological antidepressants. The antidepressant treatments, including selective serotonin reuptake inhibitors (SSRI), also helped improve stress-related neuroinflammation. It presents the direction of future development of stress-related neuroinflammation drugs. Therefore, in this review, the mechanism of stress-related neuroinflammation and pharmacological treatment candidates for it were reviewed. In addition, treatment candidates that have not yet been verified but indicate possibilities were also reviewed.

An in vivo Caenorhabditis elegans model for therapeutic research in human prion diseases

Human prion diseases are fatal neurodegenerative disorders that include sporadic, infectious and genetic forms. Inherited Creutzfeldt-Jakob disease due to the E200K mutation of the prion protein-coding gene is the most common form of genetic prion disease. The phenotype resembles that of sporadic Creutzfeldt-Jakob disease at both the clinical and pathological levels, with a median disease duration of 4 months. To date, there is no available treatment for delaying the occurrence or slowing the progression of human prion diseases. Existing in vivo models do not allow high-throughput approaches that may facilitate the discovery of compounds targeting pathological assemblies of human prion protein or their effects on neuronal survival. Here, we generated a genetic model in the nematode Caenorhabditis elegans, which is devoid of any homologue of the prion protein, by expressing human prion protein with the E200K mutation in the mechanosensitive neuronal system. Expression of E200K prion protein induced a specific behavioural pattern and neurodegeneration of green fluorescent protein-expressing mechanosensitive neurons, in addition to the formation of intraneuronal inclusions associated with the accumulation of a protease-resistant form of the prion protein. We demonstrated that this experimental system is a powerful tool for investigating the efficacy of anti-prion compounds on both prion-induced neurodegeneration and prion protein misfolding, as well as in the context of human prion protein. Within a library of 320 compounds that have been approved for human use and cross the blood-brain barrier, we identified five molecules that were active against the aggregation of the E200K prion protein and the neurodegeneration it induced in transgenic animals. This model breaks a technological limitation in prion therapeutic research and provides a key tool to study the deleterious effects of misfolded prion protein in a well-described neuronal system.

Neuropathic Pain: Biomolecular Intervention and Imaging via Targeting Microglia Activation

Many diseases, including cancer, can lead to neuropathic pain (NP). NP is one of the accompanying symptoms of suffering in many conditions and the life quality of NP patient is seriously affected. Due to complex causes, the effects of clinical treatments have been very unsatisfactory. Many experts have found that neuron-microglia interaction plays an essential role in NP occurrence and development. Therefore, the activation of microglia, related inflammatory mediators and molecular and cellular signaling pathways have become the focus of NP research. With the help of modern functional imaging technology, advanced pre-and clinical studies have been carried out and NP interventions have been attempted by using the different pharmaceuticals and the extracted active components of various traditional herbal medicines. In this communication, we review the mechanism of microglia on NP formation and treatment and molecular imaging technology's role in the clinical diagnosis and evaluation of NP therapies.

Construction of immune/Creutzfeldt-Jakob disease-related gene coexpression network to predict biomarkers

BACKGROUND AND PURPOSE

Creutzfeldt-Jakob disease (CJD) is a transmissible spongiform encephalopathy characterized by rapid onset and high mortality. Despite considerable progress in the treatment and diagnosis of CJD, patient prognosis remains poor. Many studies have found that the immune response is associated with the pathophysiology of CJD. However, few studies have reported coexpression correlations between genes associated with CJD and the immune response. This study was undertaken to construct a network of coexpressed immune- and CJD-related genes that may reveal new biomarkers and therapeutic targets for CJD.

METHODS

Gene expression data from 11 CJD patients and 10 nonneurological controls were obtained from the Gene Expression Omnibus database. High-confidence protein-protein interaction (PPI) data were downloaded from the Human Protein Reference Database, and gene expression data of immune- and CJD-associated genes were downloaded from the AmiGo16 and DisGeNET databases, respectively. An immune/CJD-related expression network was constructed based on Pearson correlation coefficients and PPI networks, and a CJD-directed neighbour coexpression network was extracted, in which we compared the gene expression patterns and correlations between different groups. The samples were classified using CJD-specific modules, and differentially expressed genes (DEGs) between the CJD and nonneurological controls groups were identified within the CJD-specific modules. Further functional analysis was performed using Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analysis of genes in each CJD-specific module.

RESULTS

We constructed an immune/CJD-related coexpression gene network comprising 2007 nodes and 5268 edges, with immune-associated genes occupying important positions in the network. In the CJD-directed neighbour coexpression network, immune-associated genes exhibited the highest coexpression level with their interacting genes. Results from Pearson correlation analysis showed that most of the CJD-associated genes were positively correlated with immune-associated genes. Screening for CJD-specific modules identified MAPK1, CASP3, APP, MAPT, SNCA, and YWHAH, indicating a close connection between CJD and the immune response. Analyses of coexpression status and expression level of CJD-specific genes revealed a very high coexpression pattern for any two genes, with most genes being DEGs. Finally, KEGG enrichment analyses of all CJD-specific genes showed that the pathophysiology of CJD is closely related to infection and the immune response.

CONCLUSIONS

Our coexpression network analysis revealed a close connection between CJD- and immune-associated genes, and we identified six CJD-specific modules. Biological function analysis of CJD-specific module genes revealed that immune responses are associated with CJD pathophysiology and may provide novel diagnostic and therapeutic biomarkers for this disease.

A review on mPGES-1 inhibitors: From preclinical studies to clinical applications

Prostaglandin E₂ (PGE₂) is a lipid mediator of inflammation and cancer progression. It is mainly formed via metabolism of arachidonic acid by cyclooxygenases (COX) and the terminal enzyme microsomal prostaglandin E synthase-1 (mPGES-1). Widely used non-steroidal anti-inflammatory drugs (NSAIDs) inhibit COX activity, resulting in decreased PGE₂ production and symptomatic relief. However, NSAIDs block the production of many other lipid mediators that have important physiological and resolving actions, and these drugs cause gastrointestinal bleeding and/or increase the risk for severe cardiovascular events. Selective inhibition of downstream mPGES-1 for reduction in only PGE₂ biosynthesis is suggested as a safer therapeutic strategy. This review covers the recent advances in characterization of new mPGES-1 inhibitors in preclinical models and their future clinical applications.

Interplay between inflammation and neural plasticity: Both immune activation and suppression impair LTP and BDNF expression

An increasing number of studies show that both inflammation and neural plasticity act as key players in the vulnerability and recovery from psychiatric disorders and neurodegenerative diseases. However, the interplay between these two players has been limitedly explored. In fact, while a few studies reported an immune activation, others conveyed an immune suppression, associated with an impairment in neural plasticity. Therefore, we hypothesized that deviations in inflammatory levels in both directions may impair neural plasticity. We tested this hypothesis experimentally, by acute treatment of C57BL/6 adult male mice with different doses of two inflammatory modulators: lipopolysaccharide (LPS), an endotoxin, and ibuprofen (IBU), a nonselective cyclooxygenase inhibitor, which are respectively a pro- and an anti-inflammatory agent. The results showed that LPS and IBU have different effects on behavior and inflammatory response. LPS treatment induced a reduction of body temperature, a decrease of body weight and a reduced food and liquid intake. In addition, it led to increased levels of inflammatory markers expression, both in the total hippocampus and in isolated microglia cells, including Interleukin (IL)-1β, and enhanced the concentration of prostaglandin E₂ (PGE₂). On the other hand, IBU increased the level of anti-inflammatory markers, decreased tryptophan 2,3-dioxygenase (TDO2), the first step in the kynurenine pathway known to be activated during inflammatory conditions, and PGE₂ levels. Though LPS and IBU administration differently affected mediators related with pro- or anti-inflammatory responses, they produced overlapping effects on neural plasticity. Indeed, higher doses of both LPS and IBU induced a statistically significant decrease in the amplitude of long-term potentiation (LTP), in Brain-Derived Neurotrophic Factor (BDNF) expression levels and in the phosphorylation of the AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor subunit GluR1, compared to the control group. Such effect appears to be dose-dependent since only the higher, but not the lower, dose of both compounds led to a plasticity impairment. Overall, the present findings indicate that acute treatment with pro- and anti-inflammatory agents impair neural plasticity in a dose dependent manner.

Neurobiology and Therapeutic Potential of Cyclooxygenase-2 (COX-2) Inhibitors for Inflammation in Neuropsychiatric Disorders

Neuropsychiatric disorders, such as depression, bipolar disorder, schizophrenia, obsessive-compulsive disorder, and neurodevelopmental disorders such as autism spectrum disorder, are associated with significant illness burden. Accumulating evidence supports an association between these disorders and inflammation. Consequently, anti-inflammatory agents, such as the cyclooxygenase-2 inhibitors, represent a novel avenue to prevent and treat neuropsychiatric illness. In this paper, we first review the role of inflammation in psychiatric pathophysiology including inflammatory cytokines' influence on neurotransmitters, the hypothalamic-pituitary-adrenal axis, and microglial mechanisms. We then discuss how cyclooxygenase-2-inhibitors influence these pathways with potential therapeutic benefit, with a focus on celecoxib, due to its superior safety profile. A search was conducted in PubMed, Embase, and PsychINFO databases, in addition to Clinicaltrials.gov and the Stanley Medical Research Institute trial registries. The results were presented as a narrative review. Currently available outcomes for randomized controlled trials up to November 2017 are also discussed. The evidence reviewed here suggests cyclooxygenase-2 inhibitors, and in particular celecoxib, may indeed assist in treating the symptoms of neuropsychiatric disorders; however, further studies are required to assess appropriate illness stage-related indication.

Diallyl Trisulfide Suppresses the Production of Lipopolysaccharide-induced Inflammatory Mediators in BV2 Microglia by Decreasing the NF-κB Pathway Activity Associated With Toll-like Receptor 4 and CXCL12/CXCR4 Pathway Blockade

Background

Diallyl trisulfide (DATS), a garlic-derived organosulfuric compound, has been documented for potential anti-inflammatory effects. However, the mechanism in microglia remains unknown. In this study, we investigated the anti-inflammatory effects of DATS in lipopolysaccharide (LPS)-stimulated BV2 microglial cells.

Methods

The effects of DATS on LPS-induced pro-inflammatory mediators such as nitric oxide (NO) and prostaglandin E₂ (PGE₂) were assessed under conditions not in the cytotoxicity of DATS. The protein expression of inflammation regulatory genes was measured by Western blot analysis.

Results

DATS significantly inhibited the LPS-induced secretion of NO and PGE₂, which was associated with the suppression of their regulatory genes, inducible NO synthase and COX-2. DATS had been shown to inhibit nuclear translocation of NF-κB by destroying the degradation and phosphorylation of IκB-α inhibitors in the cytoplasm. In addition, DATS effectively inhibited the expression of LPS-induced toll-like receptor 4 (TLR4) and myeloid differentiation factor 88. Furthermore, DATS markedly reduced the LPS-induced expression of chemokine (CXC motif) ligand (CXCL) 12 and CXC receptor (CXCR) 4, demonstrating its capacity to block chemo-attractive activity.

Conclusions

These results indicate that DATS inhibits the activation of the CXCL12/CXCR4 axis associated with antagonizing effect on TLR4 and blocks NF-κB signaling, thus demonstrating anti-inflammatory effects against LPS stimulation.

Alterations in neuronal metabolism contribute to the pathogenesis of prion disease

Neurodegenerative conditions are characterised by a progressive loss of neurons, which is believed to be initiated by misfolded protein aggregations. During this time period, many physiological and metabolomic alterations and changes in gene expression contribute to the decline in neuronal function. However, these pathological effects have not been fully characterised. In this study, we utilised a metabolomic approach to investigate the metabolic changes occurring in the hippocampus and cortex of mice infected with misfolded prion protein. In order to identify these changes, the samples were analysed by ultrahigh-performance liquid chromatography-tandem mass spectroscopy. The present dataset comprises a total of 498 compounds of known identity, named biochemicals, which have undergone principal component analysis and supervised machine learning. The results generated are consistent with the prion-inoculated mice having significantly altered metabolic profiles. In particular, we highlight the alterations associated with the metabolism of glucose, neuropeptides, fatty acids, L-arginine/nitric oxide and prostaglandins, all of which undergo significant changes during the disease. These data provide possibilities for future studies targeting and investigating specific pathways to better understand the processes involved in neuronal dysfunction in neurodegenerative diseases.

Early upregulation of 18-kDa translocator protein in response to acute neurodegenerative damage in TREM2-deficient mice

Mutations in the TREM2 gene confer risk for Alzheimer's disease and susceptibility for Parkinson's disease (PD). We evaluated the effect of TREM2 deletion in a 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model, measuring neurodegeneration and microglia activation using a combined in vivo imaging and postmortem molecular approach. In wild-type mice, MPTP administration induced a progressive decrease of [¹¹C]FECIT uptake, culminating at day 7. Neuronal loss was accompanied by an increase of TREM2, IL-1β, and translocator protein (TSPO) transcript levels, [¹¹C]PK11195 binding and GFAP staining (from day 2), and an early and transient increase of TNF-α, Galectin-3, and Iba-1 (from day 1). In TREM2 null (TREM2^-/-) mice, MPTP similarly affected neuron viability and microglial cells, as shown by the lower level of Iba-1 staining in basal condition, and reduced increment of Iba-1, TNF-α, and IL-1β in response to MPTP. Likely to compensate for TREM2 absence, TREM2^-/- mice showed an earlier increment of [¹¹C]PK11195 binding and a significant increase of IL-4. Taken together, our data demonstrate a central role of TREM2 in the regulation of microglia response to acute neurotoxic insults and suggest a potential modulatory role of TSPO in response to immune system deficit.

Defining the Microglia Response during the Time Course of Chronic Neurodegeneration

Inflammation has been proposed as a major component of neurodegenerative diseases, although the precise role it plays has yet to be defined. We examined the role of key contributors to this inflammatory process, microglia, the major resident immune cell population of the brain, in a prion disease model of chronic neurodegeneration. Initially, we performed an extensive reanalysis of a large study of prion disease, where the transcriptome of mouse brains had been monitored throughout the time course of disease. Our analysis has provided a detailed classification of the disease-associated genes based on cell type of origin and gene function. This revealed that the genes upregulated during disease, regardless of the strain of mouse or prion protein, are expressed predominantly by activated microglia. In order to study the microglia contribution more specifically, we established a mouse model of prion disease in which the 79A murine prion strain was introduced by an intraperitoneal route into BALB/cJ(Fms-EGFP/-) mice, which express enhanced green fluorescent protein under the control of the c-fms operon. Samples were taken at time points during disease progression, and histological analysis of the brain and transcriptional analysis of isolated microglia was carried out. The analysis of isolated microglia revealed a disease-specific, highly proinflammatory signature in addition to an upregulation of genes associated with metabolism and respiratory stress. This study strongly supports the growing recognition of the importance of microglia within the prion disease process and identifies the nature of the response through gene expression analysis of isolated microglia.

IMPORTANCE

Inflammation has been proposed as a major component of neurodegenerative diseases. We have examined the role of key contributors to this inflammatory process, microglia, the major resident immune cell population of the brain, in a murine prion disease model of chronic neurodegeneration. Our study demonstrates that genes upregulated throughout the disease process are expressed predominantly by microglia. A disease-specific, highly proinflammatory signature was observed in addition to an upregulation of genes associated with metabolism and respiratory stress. This study strongly supports the growing recognition of the important contribution of microglia to a chronic neurodegenerative disease process.

Pathophysiological Roles of Cyclooxygenases and Prostaglandins in the Central Nervous System

Cyclooxygenases (COXs) oxidize arachidonic acid to prostaglandin (PG) G2 and H2 followed by PG synthases that generates PGs and thromboxane (TX) A2. COXs are divided into COX-1 and COX-2. In the central nervous system, COX-1 is constitutively expressed in neurons, astrocytes, and microglial cells. COX-2 is upregulated in these cells under pathophysiological conditions. In hippocampal long-term potentiation, COX-2, PGE synthase, and PGE2 are induced in post-synaptic neurons. PGE2 acts pre-synaptic EP2 receptor, generates cAMP, stimulates protein kinase A, modulates voltage-dependent calcium channel, facilitates glutamatergic synaptic transmission, and potentiates long-term plasticity. PGD2, PGE2, and PGI2 exhibit neuroprotective effects via Gs-coupled DP1, EP2/EP4, and IP receptors, respectively. COX-2, PGD2, PGE2, PGF2α, and TXA2 are elevated in stroke. COX-2 inhibitors exhibit neuroprotective effects in vivo and in vitro models of stroke, Alzheimer's disease, Parkinson's disease, multiple sclerosis, amyotrophic lateral sclerosis, epilepsy, and schizophrenia, suggesting neurotoxicities of COX products. PGE2, PGF2α, and TXA2 can contribute to the neurodegeneration via EP1, FP, and TP receptors, respectively, which are coupled with Gq, stimulate phospholipase C and cleave phosphatidylinositol diphosphate to produce inositol triphosphate and diacylglycerol. Inositol triphosphate binds to inositol triphosphate receptor in endoplasmic reticulum, releases calcium, and results in increasing intracellular calcium concentrations. Diacylglycerol activates calcium-dependent protein kinases. PGE2 disrupts Ca(2+) homeostasis by impairing Na(+)-Ca(2+) exchange via EP1, resulting in the excess Ca(2+) accumulation. Neither PGE2, PGF2α, nor TXA2 causes neuronal cell death by itself, suggesting that they might enhance the ischemia-induced neurodegeneration. Alternatively, PGE2 is non-enzymatically dehydrated to a cyclopentenone PGA2, which induces neuronal cell death. Although PGD2 induces neuronal apoptosis after a lag time, neither DP1 nor DP2 is involved in the neurotoxicity. As well as PGE2, PGD2 is non-enzymatically dehydrated to a cyclopentenone 15-deoxy-Δ(12,14)-PGJ2, which induces neuronal apoptosis without a lag time. However, neurotoxicities of these cyclopentenones are independent of their receptors. The COX-2 inhibitor inhibits both the anchorage-dependent and anchorage-independent growth of glioma cell lines regardless of COX-2 expression, suggesting that some COX-2-independent mechanisms underlie the antineoplastic effect of the inhibitor. PGE2 attenuates this antineoplastic effect, suggesting that the predominant mechanism is COX-dependent. COX-2 or EP1 inhibitors show anti-neoplastic effects. Thus, our review presents evidences for pathophysiological roles of cyclooxygenases and prostaglandins in the central nervous system.

Anti-Inflammatory Effects of 3-(4'-Hydroxyl-3',5'-Dimethoxyphenyl)Propionic Acid, an Active Component of Korean Cabbage Kimchi, in Lipopolysaccharide-Stimulated BV2 Microglia

We investigated the protective ability of 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid (HDMPPA), an active principle in Korean cabbage kimchi, against the production of proinflammatory mediators and cytokines, and the mechanisms involved in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. HDMPPA significantly suppressed the production of nitric oxide (NO) and prostaglandin E2, along with the expression of inducible NO synthase and cyclooxygenase-2 in LPS-stimulated BV2 cells, at concentrations with no cytotoxicity. HDMPPA also attenuated the LPS-induced expression and secretion of proinflammatory cytokines, such as tumor necrosis factor-α and interleukin-1β. Furthermore, HDMPPA inhibited LPS-induced nuclear factor-κB (NF-κB) activation, which was associated with the abrogation of IκB-α degradation and phosphorylation, and subsequent decreases in NF-κB p65 levels. Moreover, the phosphorylation of mitogen-activated protein kinases (MAPKs) and Akt, a downstream molecule of phosphatidylinositol-3-kinase (PI3K), in LPS-stimulated BV2 cells was suppressed markedly by HDMPPA. This effect was associated with a significant reduction in the formation of intracellular reactive oxygen species. The findings in this study suggest that HDMPPA may exert anti-inflammatory responses by suppressing LPS-induced expression of proinflammatory mediators and cytokines through blockage of NF-κB, MAPKs, and PI3K/Akt signaling pathways and oxidative stress in microglia.

Association study of COX-2 (PTGS2) -765 G/C promoter polymorphism by pyrosequencing in Sicilian patients with Alzheimer's disease

INTRODUCTION

Alzheimer's disease (AD) is characterized by progression of memory problems to a slow global decline of cognitive function. Inflammation when left unregulated becomes a major cofactor in the pathogenesis of AD. PTGS2 is of crucial relevance in the inflammatory response, and it has been shown to play a considerable role in AD pathogenesis.

MATERIAL AND METHODS

To assess the possible putative role of a PTGS2 polymorphism (-765 G/C) in AD patients, we examined, by pyrosequencing, its distribution in 84 Sicilian AD patients and in 80 controls.

RESULTS

No significant statistical difference in PTGS2 -765 G/C genotype distribution was found comparing patients with AD and controls. In addition, no significant difference was observed in the distribution of the PTGS2 -765 alleles between AD patients and controls.

CONCLUSIONS

These findings suggest that the PTGS2 -765 G/C polymorphism may not be associated with AD in the Sicilian population.

Celecoxib Inhibits Prion Protein 90-231-Mediated Pro-inflammatory Responses in Microglial Cells

Activation of microglia is a central event in the atypical inflammatory response occurring during prion encephalopathies. We report that the prion protein fragment encompassing amino acids 90-231 (PrP90-231), a model of the neurotoxic activity of the pathogenic prion protein (PrP(Sc)), causes activation of both primary microglia cultures and N9 microglial cells in vitro. This effect was characterized by cell proliferation arrest and induction of a secretory phenotype, releasing prostaglandin E2 (PGE2) and nitric oxide (NO). Conditioned medium from PrP90-231-treated microglia induced in vitro cytotoxicity of A1 mesencephalic neurons, supporting the notion that soluble mediators released by activated microglia contributes to the neurodegeneration during prion diseases. The neuroinflammatory role of COX activity, and its potential targeting for anti-prion therapies, was tested measuring the effects of ketoprofen and celecoxib (preferential inhibitors of COX1 and COX2, respectively) on PrP90-231-induced microglial activation. Celecoxib, but not ketoprofen significantly reverted the growth arrest as well as NO and PGE2 secretion induced by PrP90-231, indicating that PrP90-231 pro-inflammatory response in microglia is mainly dependent on COX2 activation. Taken together, these data outline the importance of microglia in the neurotoxicity occurring during prion diseases and highlight the potentiality of COX2-selective inhibitors to revert microglia as adjunctive pharmacological approach to contrast the neuroinflammation-dependent neurotoxicity.

Subtype and regional-specific neuroinflammation in sporadic creutzfeldt-jakob disease

The present study identifies deregulated cytokines and mediators of the immune response in the frontal cortex and cerebellum of sporadic Creutzfeldt-Jakob disease (sCJD) MM1 and VV2 subtypes compared to age-matched controls. Deregulated genes include pro- and anti-inflammatory cytokines, toll-like receptors, colony stimulating factors, cathepsins, members of the complement system, and members of the integrin and CTL/CTLD family with particular regional and sCJD subtype patterns. Analysis of cytokines and mediators at protein level shows expression of selected molecules and receptors in neurons, in astrocytes, and/or in microglia, thus suggesting interactions between neurons and glial cells, mainly microglia, in the neuroinflammatory response in sCJD. Similar inflammatory responses have been shown in the tg340 sCJD MM1 mice, revealing a progressive deregulation of inflammatory mediators with disease progression. Yet, inflammatory molecules involved are subjected to species differences in humans and mice. Moreover, inflammatory-related cell signaling pathways NFκB/IKK and JAK/STAT are activated in sCJD and sCJD MM1 mice. Together, the present observations show a self-sustained complex inflammatory and inflammatory-related responses occurring already at early clinical stages in animal model and dramatically progressing at advanced stages of sCJD. Considering this scenario, measures tailored to modulate (activate or inhibit) specific molecules could be therapeutic options in CJD.

Ethanol extract of Poria cocos reduces the production of inflammatory mediators by suppressing the NF-kappaB signaling pathway in lipopolysaccharide-stimulated RAW 264.7 macrophages

Background

Poria cocos Wolf, a medicinal fungus, is widely used in traditional medicines in East Asian countries owing to its various therapeutic potentials. Although several studies have demonstrated the anti-inflammatory activity of this fungus, its underlying mechanisms have not yet been clearly defined.

Methods

In the present study, we have demonstrated the anti-inflammatory effects of ethanol extract of P. cocos (EEPC) in lipopolysaccaride (LPS)-stimulated RAW 264.7 macrophages. As inflammatory parameters, the productions of nitric oxide (NO), prostaglandin E2 (PGE2), interleukin (IL)-1β and tumor necrosis factor (TNF)-α were evaluated. We also examined the EEPC’s effect on the nuclear factor-kappaB (NF-κB) signaling pathway.

Results

Our results indicated that EEPC exhibits a potent inhibitory effect on NO production and inhibits PGE2 release in LPS-induced macrophages without affecting cell viability. EEPC also significantly attenuated LPS-induced secretion of inflammatory cytokines IL-1β and TNF-α. Additionally, LPS-induced expression of inducible NO synthase (iNOS), cyclooxygenase (COX)-2, IL-1β, and TNF-α was decreased by pre-treatment with EEPC at the transcriptional level. Moreover, EEPC clearly inhibited LPS-induced nuclear translocation of NF-κB p65 subunits, which correlated with EEPC’s inhibitory effects on inhibitor kappaB (IκB) degradation. Moreover, EEPC clearly suppressed the LPS-induced DNA-binding activity of NF-κB, as well as the nuclear translocation of the NF-κB p65, which correlated with EEPC’s inhibitory effects on inhibitor kappaB (IκB) degradation.

Conclusions

Taken together, our data indicates that EEPC targets the inflammatory response of macrophages via inhibition of iNOS, COX-2, IL-1β, and TNF-α through inactivation of the NF-κB signaling pathway, supporting the pharmacological basis of P. cocos as a traditional herbal medicine for treatment of inflammation and its associated disorders.

7,8-Dihydroxyflavone attenuates the release of pro-inflammatory mediators and cytokines in lipopolysaccharide-stimulated BV2 microglial cells through the suppression of the NF-κB and MAPK signaling pathways

7,8-Dihydroxyflavone (7,8-DHF), a member of the flavonoid family, has received considerable attention as a selective tyrosine kinase receptor B agonist. However, the pharmacological mechanisms responsible for its anti-inflammatory activities in microglial cells have yet to be elucidated. In this study, we evaluated the anti-inflammatory effects of this compound on the production of inflammatory mediators and cytokines in lipopolysaccharide (LPS)-stimulated murine BV2 microglial cells. At non-toxic concentrations, 7,8-DHF attenuated the production of nitric oxide (NO) and prostaglandin E2 (PGE2), by inhibiting inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) expression, respectively. Furthermore, the release and expression of inflammatory cytokines, including tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), were inhibited by 7,8-DHF. In addition, 7,8-DHF suppressed nuclear factor-κB (NF-κB) translocation and its transcriptional activity by blocking IκB (IκB)-α degradation; in addition, it exerted suppressive effects on the phosphorylation of mitogen-activated protein kinases (MAPKs). These results indicate that 7,8-DHF possesses therapeutic potential against neurodegenerative diseases that involve microglial activation.

CCAAT/enhancer binding protein β regulates prostaglandin E synthase expression and prostaglandin E2 production in activated microglial cells

The eicosanoid prostaglandin E2 (PGE2 ) plays important roles in neuroinflammation and it is produced by the sequential action of the enzymes cyclooxygenase-2 (COX-2) and prostaglandin E synthase (PTGES). The expression of both enzymes and the production of PGE2 are increased in neuroinflammation. The objective of this study was to elucidate whether the transcription factor CCAAT/enhancer binding protein β (C/EBPβ) regulates the expression of prostaglandin synthesis enzymes in neuroinflammation. To this aim, the expression of these enzymes in wild-type and C/EBPβ-null mice was analyzed in vitro and in vivo. In mixed glial cultures, lipopolysaccharide (LPS) ± interferon γ (IFN-γ) induced C/EBPβ binding to COX-2 and PTGES promoters. LPS ± IFN-γ-induced increases in PTGES expression and in PGE2 production in mixed glial and microglial cultures were abrogated in the absence of C/EBPβ. Also, increased brain PTGES expression induced by systemic LPS administration was markedly reduced in C/EBPβ-null mice. In contrast to PTGES, the induction of COX-2 expression in vitro or in vivo was not markedly affected by the absence of C/EBPβ. These results demonstrate that C/EBPβ regulates PTGES expression and PGE2 production by activated microglial cells in vitro and point to C/EBPβ as a regulator of PTGES expression in vivo in the inflamed central nervous system. Altogether, these findings strengthen the proposed role of C/EBPβ as a key player in the orchestration of neuroinflammatory gene response.

A fast one-step extraction and UPLC-MS/MS analysis for E2/D 2 series prostaglandins and isoprostanes

Prostaglandins (PG) and isoprostanes (iso-PG) may be derived through cyclooxygenase or free radical pathways and are important signaling molecules that are also robust biomarkers of oxidative stress. Their quantification is important for understanding many biological processes where PG, iso-PG, or oxidative stress are involved. One of the common methods for PG and iso-PG quantifications is LC-MS/MS that allows a highly selective, sensitive, simultaneous analysis for prostanoids without derivatization. However, the currently used LC-MS/MS methods require a multi-step extraction and a long (within an hour) LC separation to achieve simultaneous separation and analysis of the major iso-PG. The developed and validated for brain tissue analysis one-step extraction protocol and UPLC-MS/MS method significantly increases the recovery of the PG extraction up to 95 %, and allows for a much faster (within 4 min) major iso-PGE2 and -PGD2 separation with 5 times narrower chromatographic peaks as compared to previously used methods. In addition, it decreases the time and cost of analysis due to the one-step extraction approach performed in disposable centrifuge tubes. All together, this significantly increases the sensitivity, and the time and cost efficiency of the PG and iso-PG analysis.

Enhanced acute immune response in IL-12p35-/- mice is followed by accelerated distinct repair mechanisms in Staphylococcus aureus-induced murine brain abscess

BACKGROUND

Murine Staphylococcus aureus-mediated brain abscess comprises 2 major phases, an initial phase of cerebritis, followed by a healing phase characterized by capsule formation.

METHODS

C57BL/6 wild-type (WT) and IL-12p35(-/-) mice were intracerebrally infected with S. aureus to induce brain abscesses. Clinical disease activity and bacterial load were monitored. The cell populations that were involved, as well as their specific mediators, were analyzed by immunohistochemistry, quantitative real-time polymerase chain reaction, and flow cytometry.

RESULTS

In the acute phase, IL-12p35(-/-) mice were protected from disease. This was associated with enhanced recruitment of granulocytes, accompanied by upregulated expression of Il17a, Csf2 (which encodes granulocyte-macrophage colony-stimulating factor), Cxcl1, and Cxcl5, as well as increased expression of proinflammatory mediators, including Nos2 (which encodes inducible nitric oxide synthase), Ptgs2 (which encodes cyclooxygenase 2), and Tnf, that were primarily produced by granulocytes and activated microglia/macrophages. Furthermore, mechanisms associated with beneficial wound healing, including an accelerated formation of a fibrous capsule, were demonstrated by prominent VEGF-A production and collagen deposition driven by an earlier onset of T-helper 2 immunity in the absence of interleukin 12 (IL-12).

CONCLUSIONS

Brain abscess development is orchestrated by IL-12 at different stages of disease. Our data indicate that IL-12 has a nonprotective role in the acute phase and that IL-12 deficiency results in the accelerated formation of a protective capsule during the healing phase, which we consider crucial for early recovery from disease.

Soybean isoflavone genistein regulates apoptosis through NF-κB dependent and independent pathways

Cyclooxygenase-2 (COX-2), the key enzyme of the conversion of arachidonic acid to prostaglandins is an important regulator of inflammation and perhaps apoptosis. Genistein is an active component of legumes and other related food associated with prevention of degenerative diseases possibly through modulating certain signaling pathways. It was investigated whether the induction of apoptosis with genistein was carried out via COX-2 suppression through the regulation of NF-κB. The cox-2 positive and negative cells were used to compare the effect of genistein on the modulation of NF-κB in COX-2 expressed or non-expressed genotypic systems. Suppression of COX-2 as well as decreasing NF-κB DNA binding activity was accompanied with the induction of apoptosis in genistein-treated COX-2 expressed cells. However, in cox-2 negative cells, apoptosis occurred without any involvement of NF-κB with genistein treatement. Genistein induced apoptosis through the generation of reactive oxygen species (ROS) both of cox-2 positive and negative cells. These results suggested that genistein is capable of exihibiting NF-κB-dependent and NF-κB-independent apoptotic control via ROS generation depending on genetic cell types.

Cyclooxygenase expression and prostaglandin levels in central nervous system tissues during the course of chronic relapsing experimental autoimmune encephalomyelitis (EAE)

OBJECTIVE

Multiple sclerosis (MS) and its animal counterpart experimental autoimmune encephalomyelitis (EAE) have a major inflammatory component that drives and orchestrates both diseases. One particular group of mediators are the prostaglandins (PGs), which we have previously shown, through quantitation and pharmacological intervention, to be closely involved in the pathology of MS and EAE. The aim of the current study was to determine the expression of the PG-generating cyclooxygenase (COX) enzymes and the profile of PGE(2) and PGD(2), in selected central nervous system (CNS) tissues, with the development of the chronic relapsing (CR) form of EAE. In particular, the work investigates the possible relationship between the expression of COX isoenzymes and PG levels during the neurological phases of CR EAE.

METHODS

CR EAE was induced in Biozzi mice with inoculum containing lyophilised, syngeneic spinal cord emulsified in complete Freund's adjuvant. The cerebral cortex, cerebellum and spinal cord were dissected from mice during the acute, remission and relapse stages of disease with a minimum of five animals per treatment. The expression of COX-1, COX-1b variant and COX-2, in pooled samples, was determined by Western blotting. PGE(2) and PGD(2) levels in extracted samples were measured using commercial enzyme immunoassay kits.

RESULTS

COX-2 expression in spinal cords during acute disease remained unaltered and was in contrast to an enhancement of the enzyme, together with COX-1 and COX-1b, in all other sampled areas. PGE(2) and PGD(2) levels remained unchanged during the acute phase and the subsequent remission of symptoms. COX-1 and COX-1b expression was elevated in tissues during the relapse stage of CR EAE and concentrations of the prostanoids were markedly increased.

CONCLUSIONS

The study examines the implications of COX isoenzyme expression over the course of CR EAE and discusses the reported relationship between PGE(2) and PGD(2) in the instigation and resolution of CNS inflammation. Consideration is also given to the treatment of CR EAE and suggests that drugs designed to limit the inflammatory effects of the PGs should be administered prior to or during the relapse phase of the disease.

LC/MS/MS method for analysis of E₂ series prostaglandins and isoprostanes

15-series prostaglandins (PGE₂s) and isoprostanes (isoPGE₂s) are robust biomarkers of oxidative stress, possess potent biological activity, and may be derived through cyclooxygenase or free radical pathways. Thus, their quantification is critical in understanding many biological processes where PG, isoPG, or oxidative stress are involved. LC/MS/MS methods allow a highly selective, sensitive, simultaneous analysis for prostanoids without derivatization. However, the LC/MS/MS methods currently used do not allow for simultaneous separation of the major brain PGE₂/D₂) and isoPGE₂ without derivatization and multiple HPLC separations. The developed LC/MS/MS method allows for the major brain PGE₂/PGD₂/isoPGE₂ such as PGE₂, entPGE₂, 8-isoPGE₂, 11β-PGE₂, PGD₂, and 15(R)-PGD₂ to be separated and quantified without derivatization. The method was validated by analyzing free and esterified isoPGE₂ in mouse brains fixed with head-focused microwave irradiation before or after global ischemia. Using the developed method, we report for the first time the esterified isoPGE₂ levels in brain tissue under basal conditions and upon global ischemia and demonstrate a nonreleasable pool of esterified isoPG upon ischemia. In addition, we demonstrated that PGE₂s found esterified in the sn-2 position in phospholipids are derived from a free radical nonenzymatic pathway under basal conditions. Our method for brain PG analysis provides a high level of selectivity to detect changes in brain PG and isoPG mass under both basal and pathological conditions.

Rapidly progressive Creutzfeldt-Jakob disease in patients with Familial Mediterranean Fever

BACKGROUND

The largest cluster of familial Creutzfeldt-Jakob disease (fCJD) exists in Jews of Libyan origin. Familial Mediterranean fever (FMF) is an inflammatory disease also common in this population.

OBJECTIVES

We hypothesized that FMF, as a pro-inflammatory condition, may affect the course of CJD.

METHODS

Three hundred and seventy-two consecutive patients diagnosed clinically and genetically as CJD were included in the study. Two hundred and thirty-six had fCJD, and 136 had sporadic disease (sCJD). Review of the patient's records revealed three patients with FMF-CJD co-morbidity. In addition, 50 DNA samples of patients with CJD were genotyped as homozygote, heterozygote, and non-carriers of the FMF mutation. The demographic and clinical variables of the groups were compared.

RESULTS

The three patients with FMF had an earlier age of onset and significantly shorter disease duration than the patients without FMF. Heterozygote carriers did not differ in disease onset and duration from patients without FMF.

CONCLUSIONS

The shorter disease duration of CJD patients with FMF may indicate the importance of pro-inflammatory factors in the disease.

Heterogeneity of microglial activation in the innate immune response in the brain

The immune response in the brain has been widely investigated and while many studies have focused on the proinflammatory cytotoxic response, the brain's innate immune system demonstrates significant heterogeneity. Microglia, like other tissue macrophages, participate in repair and resolution processes after infection or injury to restore normal tissue homeostasis. This review examines the mechanisms that lead to reduction of self-toxicity and to repair and restructuring of the damaged extracellular matrix in the brain. Part of the resolution process involves switching macrophage functional activation to include reduction of proinflammatory mediators, increased production and release of anti-inflammatory cytokines, and production of cytoactive factors involved in repair and reconstruction of the damaged brain. Two partially overlapping and complimentary functional macrophage states have been identified and are called alternative activation and acquired deactivation. The immunosuppressive and repair processes of each of these states and how alternative activation and acquired deactivation participate in chronic neuroinflammation in the brain are discussed.

Genomic and post-genomic analyses of human prion diseases

Prion diseases share common features of neurodegenerative disorders, infectious diseases and pathologies linked to misfolded proteins. Whether these aspects are independently and fortuitously present in prion diseases or are somewhat linked together remains unsettled, but the contribution of genomic, proteomic, metabolomic and spectroscopic techniques might give insights into this puzzle, and likely give hope for therapy to patients. Although the prion protein gene (PRNP) governs most of the clinical and pathological features of prion diseases and plays a pivotal role in determining host susceptibility, there are still many uncertainties and unknown risk factors that need to be clarified and identified. Several genes, other than PRNP, have recently been found to be associated with a risk of developing sporadic or variant Creutzfeldt-Jakob disease, but these novel data have been produced in a relatively small number of patients and controls and, therefore, need further confirmation. The same criticism applies to the identification of the over 20 new cerebrospinal fluid or plasma markers of disease. Some of these markers seem related to the massive brain damage that occurs, rather than being specific to prion infection. Nevertheless, genomic and post-genomic approaches have shown that these techniques are very powerful, and the best way to overcome the scantiness of samples would be to encourage strong collaboration between different centers of excellence in prion diseases. In this review, we describe the most recent and outstanding advances offered by genomics and post-genomics analyses in the field of human prion diseases.

The distinct roles of cyclooxygenase-1 and -2 in neuroinflammation: implications for translational research

Cyclooxygenases (COX-1 and COX-2) are key enzymes in the conversion of arachidonic acid to prostaglandins and other lipid mediators. Because it can be induced by inflammatory stimuli, COX-2 has been classically considered as the most appropriate target for anti-inflammatory drugs. However, recent data indicate that COX-2 can mediate neuroprotection and that COX-1 is a major player in the neuroinflammatory process. We discuss the specific contributions of COX-1 and COX-2 in various neurodegenerative diseases and in models of neuroinflammation. We suggest that, owing to its predominant localization in microglia, COX-1 might be the major player in neuroinflammation, whereas COX-2, which is localized in neurons, might have a major role in models in which the neurons are directly challenged. Overall, the benefit of using COX-2 inhibitors should be carefully evaluated and COX-1 preferential inhibitors should be further investigated as a potential therapeutic approach in neurodegenerative diseases with an inflammatory component.

Prostaglandin as a target molecule for pharmacotherapy of allergic inflammatory diseases

The purpose of this review is to summarize the role of prostaglandins (PGs) in allergic inflammation and to know the value of PGs, as a target molecule for an anti-allergic drug. PGD(2) is the major PG produced by the cyclooxygenase pathway in mast cells. Our and others findings indicate that PGD(2) is one of the potent allergic inflammatory mediators and must be a target molecule of anti-allergic agent. From our data, one of PGD(2) receptor antagonists show clear inhibition of airway hypersensitivity caused by allergic reaction. Concerning the role of PGE(2) in allergic inflammation, conflicting results have been reported. Many experimental data suggest an individual role of each PGE(2) receptor, EP(1), EP(2), EP(3) and EP(4) in allergic reaction. Our results indicate the protective action of PGE(2) on allergic reaction via EP(3). In addition, one of EP(3) agonists clearly inhibits the allergic airway inflammation. These findings indicate the value of EP(3) agonists as an anti-allergic agent. In addition, some investigators including us reported that PGI(2) plays an important role for the protection of the onset of allergic reaction. However, the efficacy of PGI(2) analogue as an anti-allergic agent is not yet fully investigated. Finally, the role of thromboxane A(2) (TxA(2)) in allergic reaction is discussed. Our experimental results suggest a different participation of TxA(2) in allergic reaction of airway and skin. In this review, the role of PGs in allergic inflammation is summarized and the value of PGs as a target molecule for developing a new anti-allergic agent will be discussed.