Amyloid peptide-induced cytokine and chemokine expression in THP-1 monocytes is blocked by small inhibitory RNA duplexes for early growth response-1 messenger RNA

The Inhibition of Mitogen-Activated Protein Kinases (MAPKs) and NF-κB Underlies the Neuroprotective Capacity of a Cinnamon/Curcumin/Turmeric Spice Blend in Aβ-Exposed THP-1 Cells

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by an increased level of β-amyloid (Aβ) protein deposition in the brain, yet the exact etiology remains elusive. Nowadays, treatments only target symptoms, thus the search for novel strategies is constantly stimulated, and looking to natural substances from the plant kingdom. The aim of this study was to investigate the neuroprotective effects of a spice blend composed of cinnamon bark and two different turmeric root extracts (CCSB) in Aβ-exposed THP-1 cells as a model of neuroinflammation. In abiotic assays, CCSB demonstrated an antioxidant capacity up to three times stronger than Trolox in the ORAC assay, and it reduced reactive oxygen species (ROS) induced by the amyloid fragment in THP-1 cells by up to 39.7%. Moreover, CCSB lowered the Aβ stimulated secretion of the pro-inflammatory cytokines IL-1β and IL-6 by up to 24.9% and 43.4%, respectively, along with their gene expression by up to 25.2% and 43.1%, respectively. The mechanism involved the mitogen-activated protein kinases ERK, JNK and p38, whose phosphorylation was reduced by up to 51.5%, 73.7%, and 58.2%, respectively. In addition, phosphorylation of p65, one of the five components forming NF-κB, was reduced by up to 86.1%. Our results suggest that CCSB can counteract the neuroinflammatory stimulus induced by Aβ-exposure in THP-1 cells, and therefore can be considered a potential candidate for AD management.

Bioinformatics Analysis of the Molecular Networks Associated with the Amelioration of Aberrant Gene Expression by a Tyr-Trp Dipeptide in Brains Treated with the Amyloid-β Peptide

Short-chain peptides derived from various protein sources have been shown to exhibit diverse bio-modulatory and health-promoting effects in animal experiments and human trials. We recently reported that the oral administration of the Tyr-Trp (YW) dipeptide to mice markedly enhances noradrenaline metabolism in the brain and ameliorates the working-memory deficits induced by the β-amyloid 25-35 peptide (Aβ_25-35). In the current study, we performed multiple bioinformatics analyses of microarray data from Aβ_25-35/YW-treated brains to determine the mechanism underlying the action of YW in the brain and to infer the molecular mechanisms and networks involved in the protective effect of YW in the brain. We found that YW not only reversed inflammation-related responses but also activated various molecular networks involving a transcriptional regulatory system, which is mediated by the CREB binding protein (CBP), EGR-family proteins, ELK1, and PPAR, and the calcium-signaling pathway, oxidative stress tolerance, and an enzyme involved in de novo l-serine synthesis in brains treated with Aβ_25-35. This study revealed that YW has a neuroprotective effect against Aβ_25-35 neuropathy, suggesting that YW is a new functional-food-material peptide.

Optical Nanosensor for Intracellular and Intracranial Detection of Amyloid-Beta

Amyloid-beta (Aβ) deposition occurs in the early stages of Alzheimer's disease (AD), but the early detection of Aβ is a persistent challenge. Herein, we engineered a near-infrared optical nanosensor capable of detecting Aβ intracellularly in live cells and intracranially in vivo. The sensor is composed of single-walled carbon nanotubes functionalized with Aβ wherein Aβ-Aβ interactions drive the response. We found that the Aβ nanosensors selectively responded to Aβ via solvatochromic modulation of the near-infrared emission of the nanotube. The sensor tracked Aβ accumulation in live cells and, upon intracranial administration in a genetic model of AD, signaled distinct responses in aged mice. This technology enables the interrogation of molecular mechanisms underlying Aβ neurotoxicity in the development of AD in living systems.

Identification and evaluation of immunogenic MHC-I and MHC-II binding peptides from Mycobacterium tuberculosis

Due to several limitations of the only available BCG vaccine, to generate adequate protective immune responses, it is important to develop potent and cost-effective vaccines against tuberculosis (TB). In this study, we have used an immune-informatics approach to identify potential peptide based vaccine targets against TB. The proteome of Mycobacterium tuberculosis (Mtb), the causative agent of TB, was analyzed for secretory or surface localized antigenic proteins as potential vaccine candidates. The T- and B-cell epitopes as well as MHC molecule binding efficiency were identified and mapped in the modelled structures of the selected proteins. Based on antigenicity score and molecular dynamic simulation (MD) studies two peptides namely Pep-9 and Pep-15 were analyzed, modelled and docked with MHC-I and MHC-II structures. Both peptides exhibited no cytotoxicity and were able to induce proinflammatory cytokine secretion in stimulated macrophages. The molecular docking, MD and in-vitro studies of the predicted B and T-cell epitopes of Pep-9 and Pep-15 peptides with the modelled MHC structures exhibited strong binding affinity and antigenic properties, suggesting that the complex is stable, and that these peptides can be considered as a potential candidates for the development of vaccine against TB.

The Alzheimer's Disease Amyloid-Beta Hypothesis in Cardiovascular Aging and Disease: JACC Focus Seminar

Aging-related cellular and molecular processes including low-grade inflammation are major players in the pathogenesis of cardiovascular disease (CVD) and Alzheimer's disease (AD). Epidemiological studies report an independent interaction between the development of dementia and the incidence of CVD in several populations, suggesting the presence of overlapping molecular mechanisms. Accumulating experimental and clinical evidence suggests that amyloid-beta (Aβ) peptides may function as a link among aging, CVD, and AD. Aging-related vascular and cardiac deposition of Αβ induces tissue inflammation and organ dysfunction, both important components of the Alzheimer's disease amyloid hypothesis. In this review, the authors describe the determinants of Aβ metabolism, summarize the effects of Aβ on atherothrombosis and cardiac dysfunction, discuss the clinical value of Αβ1-40 in CVD prognosis and patient risk stratification, and present the therapeutic interventions that may alter Aβ metabolism in humans.

Enterocyte-Based Bioassay via Quantitative Combination of Proinflammatory Sentinels Specific to 8-keto-trichothecenes

Type B 8-keto-trichothecenes are muco-active mycotoxins that exist as inevitable contaminants in cereal-based foodstuffs. Gut-associated inflammation is an early frontline response during human and animal exposure to these mycotoxins. Despite various tools for chemical identification, optimized biomonitoring of sentinel response-associated biomarkers is required to assess the specific proinflammatory actions of 8-keto-trichothecenes in the gut epithelial barrier. In the present study, intoxication with 8-keto-trichothecenes in human intestinal epithelial cells was found to trigger early response gene 1 product (EGR-1) that plays crucial roles in proinflammatory chemokine induction. In contrast, epithelial exposure to 8-keto-trichothecenes resulted in downregulated expression of nuclear factor NF-kappa-B p65 protein, a key transcription factor, during general inflammatory responses in the gut. Based on the early molecular patterns of expression, the inflammation-inducing activity of 8-keto-trichothecenes was quantified using intestinal epithelial cells with dual reporters for EGR-1 and p65 proteins. EGR-1-responsive elements were linked to luciferase reporter while p65 promoter was bound to secretory alkaline phosphatase (SEAP) reporter. In response to conventional inflammagens such as endotoxins and cytokines such as TNF-α, both luciferase and SEAP activity were elevated in a dose-dependent manner. However, as expected from the mechanistic evaluation, 8-keto-trichothecene-exposed dual reporters of luciferase and SEAP displayed contrasting expression patterns. Furthermore, 8-keto-trichothecene-elevated EGR-1-responsive luciferase activity was improved by deficiency of PSMA3, an α-type subunit of the 20S proteasome core complex for ubiquitin-dependent EGR-1 degradation. This molecular event-based dual biomonitoring in epithelial cells is a promising supplementary tool for detecting typical molecular inflammatory pathways in response to 8-keto-trichothecenes in the food matrix.

Prodromal Intestinal Events in Alzheimer's Disease (AD): Colonic Dysmotility and Inflammation Are Associated with Enteric AD-Related Protein Deposition

Increasing evidence suggests that intestinal dysfunctions may represent early events in Alzheimer’s disease and contribute to brain pathology. This study examined the relationship between onset of cognitive impairment and colonic dysfunctions in a spontaneous AD model before the full development of brain pathology. SAMP8 mice underwent Morris water maze and assessment of faecal output at four, six and eight months of age. In vitro colonic motility was examined. Faecal and colonic Aβ, tau proteins, α-synuclein and IL-1β were assessed by ELISA. Colonic citrate synthase activity was assessed by spectrophotometry. Colonic NLRP3, caspase-1 and ASC expression were evaluated by Western blotting. Colonic eosinophil density and claudin-1 expression were evaluated by immunohistochemistry. The effect of Aβ on NLRP3 signalling and mitochondrial function was tested in cultured cells. Cognitive impairment and decreased faecal output occurred in SAMP8 mice from six months. When compared with SAMR1, SAMP8 animals displayed: (1) impaired in vitro colonic contractions; (2) increased enteric AD-related proteins, IL-1β, active-caspase-1 expression and eosinophil density; and (3) decreased citrate synthase activity and claudin-1 expression. In THP-1 cells, Aβ promoted IL-1β release, which was abrogated upon incubation with caspase-1 inhibitor or in ASC^-/- cells. Aβ decreased mitochondrial function in THP-1 cells. In SAMP8, enteric AD-related proteins deposition, inflammation and impaired colonic excitatory neurotransmission, occurring before the full brain pathology development, could contribute to bowel dysmotility and represent prodromal events in AD.

Amyloid protein aggregation in diabetes mellitus accelerate intervertebral disc degeneration

Diabetes is one of the risk factors for disc degeneration, but the exact mechanism is still unclear. Misfolding and aggregation of human islet amyloid polypeptide (hIAPP) is an important factor in diabetes. hIAPP proteins misfold from monomers to β-sheet-rich oligomers, destroy the permeability of the cell membrane and cause abnormal cell function and death. Under the pathological state of diabetes, hIAPP oligomers can promote the expression and secretion of the inflammatory factor IL-1β, while IL-1β-mediated inflammatory response is the pathogenesis basis of intervertebral disc degeneration. Thus, amyloid hIAPP aggregation accelerates disc degeneration in the pathological state of diabetes.

Recent advances in neurogenic and neuroprotective effects of curcumin through the induction of neural stem cells

Curcumin is extensively used in the prevention and treatment of various diseases. Recently, growing attention has been paid to the use of curcumin as a neurogenic and neuroprotective agent. This review study is aimed to collect and categorize the recent findings regarding the effects of curcumin on various neurological diseases through the induction of neural stem cell proliferation and differentiation. In addition, we have discussed the molecular mechanisms modulated by curcumin that contribute to this efficacy and have summarized the recent advancements in the novel delivery strategies used to improve the induction of neural stem cells by curcumin.

Different gene response to mechanical loading during early and late phases of rat Achilles tendon healing

Mechanical loading stimulates tendon healing both when applied in the inflammatory phase and in the early remodeling phase of the process, although not necessarily via the same mechanisms. We investigated the gene response to mechanical loading in these two phases of tendon healing. The right Achilles tendon in rats was transected, and the hindlimbs were unloaded by tail suspension. The rats were exposed to 5 min of treadmill running 3 or 14 days after tendon transection. Thereafter, they were resuspended for 15 min or 3 h until euthanasia. The controls were suspended continuously. Gene analysis was first performed by microarray analysis followed by quantitative RT-PCR on selected genes, focusing on inflammation. Fifteen minutes after loading, the most important genes seemed to be the transcription factors EGR1 and C-FOS, regardless of healing phase. These transcription factors might promote tendon cell proliferation and differentiation, stimulate collagen production, and regulate inflammation. Three hours after loading on day 3, inflammation was strongly affected. Seven inflammation-related genes were upregulated according to PCR: CCL20, CCL7, IL-6, NFIL3, PTX3, SOCS1, and TLR2. These genes can be connected to macrophages, T cells, and recruitment of leukocytes. According to Ingenuity Pathway Analysis, the recruitment of leukocytes was increased by loading on day 3, which also was confirmed by histology. This inflammation-related gene response was not seen on day 14 Our results suggest that the immediate gene response after mechanical loading is similar in the early and late phases of healing but the late gene response is different.NEW & NOTEWORTHY This study investigates the direct effect of mechanical loading on gene expression during different healing phases in tendon healing. One isolated episode of mechanical loading was studied in otherwise unloaded healing tendons. This enabled us to study a time sequence, i.e., which genes were the first ones to be regulated after the loading episode.

Statins Reduce Lipopolysaccharide-Induced Cytokine and Inflammatory Mediator Release in an In Vitro Model of Microglial-Like Cells

The anti-inflammatory effects of statins (HMG-CoA reductase inhibitors) within the cardiovascular system are well-established; however, their neuroinflammatory potential is unclear. It is currently unknown whether statins' neurological effects are lipid-dependent or due to pleiotropic mechanisms. Therefore, the assumption that all statin compounds will have the same effect within the central nervous system is potentially inappropriate, with no studies to date having compared all statins in a single model. Thus, the aim of this study was to compare the effects of the six statins (atorvastatin, fluvastatin, pitavastatin, pravastatin, rosuvastatin, and simvastatin) within a single in vitro model of neuroinflammation. To achieve this, PMA-differentiated THP-1 cells were used as surrogate microglial cells, and LPS was used to induce inflammatory conditions. Here, we show that pretreatment with all statins was able to significantly reduce LPS-induced interleukin (IL)-1β and tumour necrosis factor (TNF)-α release, as well as decrease LPS-induced prostaglandin E2 (PGE2). Similarly, global reactive oxygen species (ROS) and nitric oxide (NO) production were decreased following pretreatment with all statins. Based on these findings, it is suggested that more complex cellular models should be considered to further compare individual statin compounds, including translation into in vivo models of acute and/or chronic neuroinflammation.

Induction of Bex genes by curcumin is associated with apoptosis and activation of p53 in N2a neuroblastoma cells

Brain expressed X-linked (Bex) genes are newer group of pro-apoptotic genes. Role of any Bex gene in neuroblastoma and Bex4 and Bex6 in any cancer is completely unknown. Re-expression of all endogenous Bex genes by any nutraceutical is also unknown. Therefore, we investigated the induction of all endogenous Bex genes and associated mechanisms by curcumin using N2a, an aggressive neuroblastoma cell line. Curcumin induced all endogenous Bex genes prior to apoptosis in N2a cells in a dose- and time-dependent manner. Wortmannin (PI-3Kinases inhibitor), SP600125 (JNK inhibitor) and pifithrin-α (p53 inhibitor) abrogated curcumin-mediated induction of Bex genes. Inhibition of curcumin-mediated induction of Bex genes by pifithrin-α also inhibited N2a cells apoptosis suggesting, a direct role of Bex genes in N2a cells apoptosis and involvement of p53 in Bex genes induction. Curcumin treatment activated p53 through hyperphosphorylation at serine 15 before Bex genes induction indicating Bex genes are novel downstream targets of p53. Collectively, curcumin, a safe nutraceutical has the potential to induce all endogenous Bex genes to harness their anti-cancer properties in neuroblastoma cells. Re-expression of Bex genes by curcumin acts as tumor suppressors and may provide alternate strategy to treat neuroblastomas and other cancers with silenced Bex genes.

Citrus bergamia Juice Extract Attenuates β-Amyloid-Induced Pro-Inflammatory Activation of THP-1 Cells Through MAPK and AP-1 Pathways

Flavonoids have been shown to be effective in protecting against age-related cognitive and motor decline in both in vitro and in vivo models. Recently, a flavonoid-rich extract of Citrus bergamia juice (BJe) has been shown to display anti-oxidant and anti-inflammatory properties against LPS-induced activation of human THP-1 monocytes. In the light of these observations, we wondered whether BJe may be beneficial against neuroinflammatory processes, such as those observed in Alzheimer’s disease. To this aim we used THP-1 monocytes to investigate the mechanisms underlying the beneficial potential of BJe against amyloid-beta_1–42 (Aβ₁₋₄₂) -mediated inflammation. Exposure of THP-1 cells to Aβ₁₋₄₂ significantly induced the expression and secretion of IL-6 and IL-1β in THP-1 cells and increased the phosphorylation of ERK 1/2 as well as p46 and p54 members of JNK family. Moreover, Aβ₁₋₄₂ raises AP-1 DNA binding activity in THP-1-treated cells. Interestingly, all these effects were reduced in the presence of BJe. Our data indicate that BJe may effectively counteract the pro-inflammatory activation of monocytes/microglial cells exposed to amyloid fibrils, suggesting a promising role as a natural drug against neuroinflammatory processes.

Curcumin and Apigenin - novel and promising therapeutics against chronic neuroinflammation in Alzheimer's disease

Alzheimer's disease is a progressive neurodegenerative disorder, characterized by deposition of amyloid beta, neurofibrillary tangles, astrogliosis and microgliosis, leading to neuronal dysfunction and loss in the brain. Current treatments for Alzheimer's disease primarily focus on enhancement of cholinergic transmission. However, these treatments are only symptomatic, and no disease-modifying drug is available for Alzheimer's disease patients. This review will provide an overview of the proven antioxidant, anti-inflammatory, anti-amyloidogenic, neuroprotective, and cognition-enhancing effects of curcumin and apigenin and discuss the potential of these compounds for Alzheimer's disease prevention and treatment. We suggest that these compounds might delay the onset of Alzheimer's disease or slow down its progression, and they should enter clinical trials as soon as possible.

Expression of early growth response 1 affects miR-106a/signal transducer and activator of transcription 3 regulating cognitive impairment in ovariectomized mice

OBJECTIVE

This study aims to investigate the effects of early growth response 1 (Egr1) on miR-106a/signal transducer and activator of transcription 3 (STAT3) regulating cognitive impairment in an ovariectomy model.

METHODS

Using the Morris water maze test, we assessed escape latency and time spent in a quadrant among mice at 6, 8, and 12 weeks after ovariectomy and their age-matched controls (n = 15 each group). Egr1, miR-106a, and STAT3 messenger RNA expression (n = 7) in the hippocampus and cortex of mice at 6, 8, and 12 weeks after ovariectomy was detected by quantitative real-time polymerase chain reaction, whereas Egr1, phospho-STAT3 (p-STAT3), and STAT3 protein expression (n = 8) was evaluated by Western blot analysis. Moreover, alterations in miR-106a and STAT3 expression were investigated in neuroblastoma (SH-SY5Y) cells transfected with a human Egr1 interference fragment (si-Egr1) or an Egr1-overexpressing plasmid (GV141-Egr1), respectively.

RESULTS

Escape latency was significantly increased and time spent in a platform quadrant was reduced in mice at 12 weeks after ovariectomy compared with age-matched controls. Egr1 and miR-106a expression was obviously increased in the hippocampus and cortex at 12 weeks after ovariectomy, whereas STAT3 levels were decreased compared with 12-week controls. After SH-SY5Y cell transfection with the si-Egr1 fragment, miR-106a levels decreased and STAT3/p-STAT3 levels increased, whereas cotransfection of the miR-106a mimic caused a significant decrease in STAT3 levels. MiR-106a messenger RNA expression was significantly increased and STAT3/p-STAT3 protein levels were decreased by Egr1 overexpression, whereas simultaneous transfection with the miR-106a inhibitor inhibited alterations in STAT3 levels.

CONCLUSIONS

This study suggests that Egr1 decreases STAT3 expression via miR-106a in ovariectomized mice with cognitive impairment, indicating that Egr1 represents a potential target for therapeutic intervention in postmenopausal cognitive decline.

Selective acetyl- and butyrylcholinesterase inhibitors reduce amyloid-β ex vivo activation of peripheral chemo-cytokines from Alzheimer's disease subjects: exploring the cholinergic anti-inflammatory pathway

Increasing evidence suggests that elevated production and/or reduced clearance of amyloid-β peptide (Aβ) drives the early pathogenesis of Alzheimer's disease (AD). Aβ soluble oligomers trigger a neurotoxic cascade that leads to neuronal dysfunction, neurodegeneration and, ultimately, clinical dementia. Inflammation, both within brain and systemically, together with a deficiency in the neurotransmitter acetylcholine (ACh) that underpinned the development of anticholinesterases for AD symptomatic treatment, are invariable hallmarks of the disease. The inter-relation between Aβ, inflammation and cholinergic signaling is complex, with each feeding back onto the others to drive disease progression. To elucidate these interactions plasma samples and peripheral blood mononuclear cells (PBMCs) were evaluated from healthy controls (HC) and AD patients. Plasma levels of acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and Aβ were significantly elevated in AD vs. HC subjects, and ACh showed a trend towards reduced levels. Aβ challenge of PBMCs induced a greater release of inflammatory cytokines interleukin-1β (IL-1β), monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-α) from AD vs. HC subjects, with IL-10 being similarly affected. THP-1 monocytic cells, a cell culture counterpart of PBMCs and brain microglial cells, responded similarly to Aβ as well as to phytohaemagglutinin (PHA) challenge, to allow preliminary analysis of the cellular and molecular pathways underpinning Aβ-induced changes in cytokine expression. As amyloid-β precursor protein expression, and hence Aβ, has been reported regulated by particular cytokines and anticholinesterases, the latter were evaluated on Aβ- and PHA-induced chemocytokine expression. Co-incubation with selective AChE/BuChE inhibitors, (-)-phenserine (AChE) and (-)-cymserine analogues (BuChE), mitigated the rise in cytokine levels and suggest that augmentation of the cholinergic anti-inflammatory pathway may prove valuable in AD.

Phenolic excipients of insulin formulations induce cell death, pro-inflammatory signaling and MCP-1 release

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Insulin formulations are cytotoxic in vitro.

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Toxicity is caused by the excipients phenol and m-cresol.

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Phenolic excipients activate stress kinases and attenuate AKT phosphorylation.

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Phenolic excipients induce pro-inflammatory responses and MCP-1 release.

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The toxic effects of excipients might explain inflammation of infusion sites in vivo.

Skin reactions at the infusion site are a common side effect of continuous subcutaneous insulin infusion therapy. We hypothesized that local skin complications are caused by components of commercial insulin formulations that contain phenol or m-cresol as excipients. The toxic potential of insulin solutions and the mechanisms leading to skin reactions were explored in cultured cells.

The toxicity of insulin formulations (Apidra, Humalog, NovoRapid, Insuman), excipient-free insulin, phenol and m-cresol was investigated in L929 cells, human adipocytes and monocytic THP-1 cells. The cells were incubated with the test compounds dose- and time-dependently. Cell viability, kinase signaling pathways, monocyte activation and the release of pro-inflammatory cytokines were analyzed.

Insulin formulations were cytotoxic in all cell-types and the pure excipients phenol and m-cresol were toxic to the same extent. P38 and JNK signaling pathways were activated by phenolic compounds, whereas AKT phosphorylation was attenuated. THP-1 cells incubated with sub-toxic levels of the test compounds showed increased expression of the activation markers CD54, CD11b and CD14 and secreted the chemokine MCP-1 indicating a pro-inflammatory response.

Insulin solutions displayed cytotoxic and pro-inflammatory potential caused by phenol or m-cresol. We speculate that during insulin pump therapy phenol and m-cresol might induce cell death and inflammatory reactions at the infusion site in vivo. Inflammation is perpetuated by release of MCP-1 by activated monocytic cells leading to enhanced recruitment of inflammatory cells. To minimize acute skin complications caused by phenol/m-cresol accumulation, a frequent change of infusion sets and rotation of the infusion site is recommended.

Peroxisome proliferator-activated receptor-α-mediated transcription of miR-199a2 attenuates endothelin-1 expression via hypoxia-inducible factor-1α

Endothelin-1, a potent vasoconstrictor, plays an important role in pulmonary hypertension (PH) in sickle cell disease (SCD). Our previous studies show that higher levels of placenta growth factor (PlGF), secreted by erythroid precursor cells, correlate with increased plasma levels of endothelin-1 (ET-1) and other functional markers of PH in SCD. PlGF-mediated ET-1 expression occurs via activation of hypoxia-inducible factor-1α (HIF-1α). However, relatively less is understood regarding how PlGF-mediated expression of HIF-1α and its downstream effector ET-1 are post-transcriptionally regulated. Herein, we show that PlGF treatment of endothelial cells resulted in reduced levels of miR-199a2, which targeted the 3'-UTR of HIF-1α mRNA and concomitantly led to augmented ET-1 expression. Plasma levels of miR-199a2 in SCD subjects were significantly lower with reciprocally high levels of plasma ET-1, unlike unaffected controls. This observation provided a molecular link between miR-199a2 and high levels of ET-1 in SCD. Furthermore, we show that miR-199a2 located in the DNM3os transcription unit was co-transcriptionally regulated by peroxisome proliferator-activated receptor α (PPARα). Binding of the latter to PPARα cis-elements in the promoter of DNM3os was demonstrated by promoter mutational analysis and ChIP. Additionally, we show that fenofibrate, a PPARα agonist, increased the expression of miR-199a2 and DNM3os; the former was responsible for reduced expression of HIF-1α and ET-1. In vivo studies of fenofibrate-fed Berkeley sickle mice resulted in increased levels of miR-199a2 and reduced levels of ET-1 in lung tissues. Our studies provide a potential therapeutic approach whereby fenofibrate-induced miR-199a2 expression can ameliorate PH by reduction of ET-1 levels.

Development of a novel cellular model of Alzheimer's disease utilizing neurosphere cultures derived from B6C3-Tg(APPswe,PSEN1dE9)85Dbo/J embryonic mouse brain

Increased production, oligomerization and aggregation of amyloid-β (Aβ) peptides are hallmark pathologies of Alzheimer’s disease (AD). Expressing familial AD mutations (amyloid precursor protein and/or presenilins mutations), the Aβ-pathologies of AD has been recapitulated in animal models of AD. Very few primary cell culture-based models of AD are available and they exhibit very weak Aβ-pathologies compared to what is seen in AD patients and animal models of AD. CNS stem/progenitor cells are present in both embryonic and adult brains. They can be isolated, grown as neurospheres and differentiated into neurons, astrocytes and oligodendrocytes. It is not yet known whether CNS stem/progenitor cells can support the production of Aβ peptides in culture. In this report, we have established Aβ-pathologies such as production, secretion, oligomerization and aggregation of Aβ peptides utilizing neurosphere cultures to create a new cellular model of AD. These cultures were developed from E15 embryonic brains of transgenic mice carrying the Swedish mutations in humanized mouse APP cDNA and the exon-9 deleted human presenilin 1 cDNA both regulated by mouse prion protein gene (Prnp) promoter. Results demonstrated the expression of transgene transcripts, APPswe protein and its processed products only in transgene positive neurosphere cultures. These cultures generate and secrete both Aβ40 and Aβ42 peptides into culture medium at levels comparable to the Aβ load in the brain of AD patients and animal models of AD, and produce pathogenic oligomers of Aβ peptides. The Aβ42/Aβ40 ratio in the medium of transgene positive neurosphere cultures is higher than any known cellular models of AD. Conformation dependent immunocytochemistry demonstrated the possible presence of intracellular and extracellular aggregation of Aβ peptides in neurosphere cultures, which are also seen in AD brain and animal models of AD. Collectively, our neurosphere cultures provide robust Aβ-pathologies of AD better than existing cellular model of Alzheimer’s disease.

Retinoids as potential targets for Alzheimer's disease

Vitamin A and its derivatives, the retinoids, modulate several physiological and pathological processes through their interactions with nuclear retinoid receptor proteins termed as retinoic acid receptors (RARs) and retinoid X receptors (RXRs). An increasing body of evidence signifies the existence of retinoid signaling in diverse brain areas including cortex, amygdala, hypothalamus, hippocampus, and striatum suggesting its involvement in adult brain functions. Defective retinoid signaling has been evidenced in the pathology of Alzheimer's disease. Reports demonstrate that vitamin A deprived mice exhibit serious defects in spatial learning and memory signifying its importance in the maintenance of memory functions. Retinoid signaling impacts the development of AD pathology through multiple pathways. Ligand activation of RAR and RXR in APP/PS1 transgenic mice ameliorated the symptoms of AD and reduced amyloid accumulation and tau hyperphosphorylation. Retinoids also reduce the production of pro-inflammatory cytokines and chemokines by astrocytes and the microglia. Studies also suggest that neuronal cell lines treated with retinoid agonists exhibit an up-regulation in the expression and activity of choline acetyltransferase (ChAT). Reports depict that retinoic acid isomers enhance, the expression of genes linked with cholesterol efflux e.g. apoe, abca-1 and abcg-1 proteins in astrocytes. Furthermore numerous studies also indicate antioxidant potential of retinoids. Through this review we concisely summarize the biology of retinoids, emphasizing on their probable neuroprotective mechanisms that will help to elucidate the pivotal role of these receptors in AD pathology.

A Novel Anticancer Agent, 8-Methoxypyrimido[4',5':4,5]thieno(2,3-b) Quinoline-4(3H)-One Induces Neuro 2a Neuroblastoma Cell Death through p53-Dependent, Caspase-Dependent and -Independent Apoptotic Pathways

Neuroblastoma is the most common cancer in infants and fourth most common cancer in children. Despite recent advances in cancer treatments, the prognosis of stage-IV neuroblastoma patients continues to be dismal which warrant new pharmacotherapy. A novel tetracyclic condensed quinoline compound, 8-methoxypyrimido [4',5':4,5]thieno(2,3-b) quinoline-4(3H)-one (MPTQ) is a structural analogue of an anticancer drug ellipticine and has been reported to posses anticancer property. Study on MPTQ on neuroblastoma cells is very limited and mechanisms related to its cytotoxicity on neuroblastoma cells are completely unknown. Here, we evaluated the anticancer property of MPTQ on mouse neuro 2a and human SH-SY5Y neuroblastoma cells and investigated the mechanisms underlying MPTQ-mediated neuro 2a cell death. MPTQ-mediated neuro 2a and SH-SY5Y cell deaths were found to be dose and time dependent. Moreover, MPTQ induced cell death reached approximately 99.8% and 90% in neuro 2a and SH-SY5Y cells respectively. Nuclear oligonucleosomal DNA fragmentation and Terminal dUTP Nick End Labelling assays indicated MPTQ-mediated neuro 2a cell death involved apoptosis. MPTQ-mediated apoptosis is associated with increased phosphorylation of p53 at Ser15 and Ser20 which correlates with the hyperphosphorylation of Ataxia-Telangiectasia mutated protein (ATM). Immunocytochemical analysis demonstrated the increased level of Bax protein in MPTQ treated neuro 2a cells. MPTQ-mediated apoptosis is also associated with increased activation of caspase-9, -3 and -7 but not caspase-2 and -8. Furthermore, increased level of caspase-3 and cleaved Poly (ADP Ribose) polymerase were observed in the nucleus of MPTQ treated neuro 2a cells, suggesting the involvement of caspase-dependent intrinsic but not extrinsic apoptotic pathway. Increased nuclear translocation of apoptosis inducing factor suggests additional involvement of caspase-independent apoptosis pathway in MPTQ treated neuro 2a cells. Collectively, MPTQ-induced neuro 2a cell death is mediated by ATM and p53 activation, and Bax-mediated activation of caspase-dependent and caspase-independent mitochondrial apoptosis pathways.

Liver X receptors: emerging therapeutic targets for Alzheimer's disease

Alzheimer's disease (AD) is a complex neurodegenerative disorder, typified by the pathological accumulation of ß-amyloid peptides (Aß) and neurofibrillary tangles within the brain, culminating to cognitive impairment. Epidemiological and biochemical data have suggested a link between cholesterol content, APP (amyloid precursor protein) processing, Aß, inflammation and AD. The intricacy of the disease presents considerable challenges for the development of newer therapeutic agents. Liver X receptors (LXRa and LXRß) are oxysterol activated nuclear receptors that play essential role in lipid and glucose homeostasis, steroidogenesis and inflammatory responses. LXR signalling impacts the development of AD pathology through multiple pathways. Reports indicate that genetic loss of either lxra or lxrß in APP/PS1 transgenic mice results in increased amyloid plaque load. Studies also suggest that ligand activation of LXRs in Tg2576 mice enhanced, the expression of genes linked with cholesterol efflux e.g. apoe, abca-1, down regulated APP processing and Aß production with significant improvement in memory functions. LXR agonists have also depicted to inhibit neuroinflammation through modulation of microglial phagocytosis and by repressing the expression of cox2, mcp1 and iNos in glial cells. This review summarizes in brief the biology of LXRs, with an emphasis on their probable pathophysiological mechanisms that may elicit the defending role of these receptors in brains of AD patients.

Relationship between inflammatory mediators, Aβ levels and ApoE genotype in Alzheimer disease

Activation of inflammatory processes is observed within the brain as well as periphery of subjects with Alzheimer's disease (AD). Whether or not inflammation represents a possible cause of AD or occurs as a consequence of the disease process, or, alternatively, whether the inflammatory response might be beneficial to slow the disease progression remains to be elucidated. The cytokine IL-18 shares with IL-1 the same pro-inflammatory features. Consequent to these similarities, IL-18 and its endogenous inhibitor, IL-18BP, were investigated in the plasma of AD patients versus healthy controls (HC). An imbalance of IL-18 and IL-18BP was observed in AD, with an elevated IL-18/IL-18BP ratio that might be involved in disease pathogenesis. As part of the inflammatory response, altered levels of RANTES, MCP-1 and ICAM- 1, molecules involved in cell recruitment to inflammatory sites, were observed in AD. Hence, correlations between IL-18 and other inflammatory plasma markers were analyzed. A negative correlation was observed between IL-18 and IL-18BP in both AD and HC groups. A positive correlation was observed between IL-18 and ICAM-1 in AD patients, whereas a negative correlation was evident in the HC group. IL-18 positively correlated with Aβ in both groups, and no significant correlations were observed between IL-18, RANTES and MCP-1. An important piece of evidence supporting a pathophysiologic role for inflammation in AD is the number of inflammatory mediators that have been found to be differentially regulated in AD patients, and specific ones may provide utility as part of a biomarker panel to not only aid early AD diagnosis, but follow its progression.

Atherogenic ω-6 Lipids Modulate PPAR- EGR-1 Crosstalk in Vascular Cells

Atherogenic ω-6 lipids are physiological ligands of peroxisome proliferator-activated receptors (PPARs) and elicit pro- and antiatherogenic responses in vascular cells. The objective of this study was to investigate if ω-6 lipids modulated the early growth response-1 (Egr-1)/PPAR crosstalk thereby altering vascular function. Rat aortic smooth muscle cells (RASMCs) were exposed to ω-6 lipids, linoleic acid (LA), or its oxidized form, 13-HPODE (OxLA) in the presence or absence of a PPARα antagonist (MK886) or PPARγ antagonist (GW9662) or PPAR-specific siRNA. Our results demonstrate that ω-6 lipids, induced Egr-1 and monocyte chemotactic protein-1 (MCP-1) mRNA and protein levels at the acute phase (1-4 hrs) when PPARα was downregulated and at subacute phase (4-12 hrs) by modulating PPARγ, thus resulting in altered monocyte adhesion to RASMCs. We provide novel insights into the mechanism of action of ω-6 lipids on Egr-1/PPAR interactions in vascular cells and their potential in altering vascular function.

Egr-1 transactivates Bim gene expression to promote neuronal apoptosis

The proapoptotic BH3-only protein Bim is a crucial regulator of neuronal apoptosis. Previous studies have indicated the involvement of the c-Jun, FOXO1/3a, and B/C-Myb transcription factors in the regulation of Bim during neuronal apoptosis. However, the mechanism underlying the transcriptional regulation of Bim in activity deprivation-induced neuronal apoptosis has remained unclear. The present study demonstrates that early growth response 1 (Egr-1), rather than c-Jun, FOXO1/3a, or B/C-Myb, directly transactivates Bim gene expression to mediate apoptosis of rat cerebellar granule neurons. We showed that Egr-1 was sufficient and necessary for neuronal apoptosis. Suppression of Egr-1 activity using dominant-negative mutant or knockdown of Egr-1 using small interfering RNAs led to a decrease in Bim expression, whereas overexpression of Egr-1 resulted in induction of Bim. Deletion and site-directed mutagenesis of the Bim promoter revealed that Bim transcriptional activation depends primarily on a putative Egr-binding sequence between nucleotides -56 and -47 upstream of the start site. We also showed that Egr-1 binding to this sequence increased in response to activity deprivation in vitro and in vivo. Moreover, inhibition of Egr-1 binding to the Bim promoter, by mithramycin A and chromomycin A3, reduced the activity deprivation-induced increases in Bim promoter activity and mRNA and protein levels and protected neurons from apoptosis, further supporting the Egr-1-mediated transactivation of Bim. Additionally, Bim overcame the Egr-1 knockdown-mediated inhibition of apoptosis, whereas Bim knockdown impaired the increase in apoptosis induced by Egr-1. These findings establish Bim as an Egr-1 target gene in neurons, uncovering a novel Egr-1/Bim pathway by which activity deprivation induces neuronal apoptosis.

Neuroprotection by spice-derived nutraceuticals: you are what you eat!

Numerous lines of evidence indicate that chronic inflammation plays a major role in the development of various neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, brain tumor, and meningitis. Why these diseases are more common among people from some countries than others is not fully understood, but lifestyle factors have been linked to the development of neurodegenerative diseases. For example, the incidence of certain neurodegenerative diseases among people living in the Asian subcontinent, where people regularly consume spices, is much lower than in countries of the western world. Extensive research over the last 10 years has indicated that nutraceuticals derived from such spices as turmeric, red pepper, black pepper, licorice, clove, ginger, garlic, coriander, and cinnamon target inflammatory pathways, thereby may prevent neurodegenerative diseases. How these nutraceuticals modulate various pathways and how they exert neuroprotection are the focus of this review.

ERK pathway activation is required for amyloid-β(1-40)(-)induced neurotoxicity of THP-1 human monocytes towards SK-N-SH neuroblastoma

Alzheimer's disease (AD) is characterized by amyloid-β peptide deposition, increased activated microglia, and progressive loss of neurons in the brain. Although Aβ₁₋₄₀ can elicit inflammation in microglia, the intracellular signaling events mediating these effects are poorly defined. Here we show that cell-free supernatant from Aβ₁₋₄₀-treated THP-1 monocytes induced cytotoxicity towards neuroblastoma SK-N-SH cells. Exposure of THP-1 monocytes to Aβ₁₋₄₀ leads to increased tyrosine phosphorylation and extracellular signaling-regulated kinase (ERK) and increased levels of inflammatory cytokines (IL-1β, IL-8, and TNF-α) in the supernatant of THP-1 monocytes. Pretreatment of THP-1 monocytes with either a protein tyrosine kinase (PTK) inhibitor or an ERK inhibitor protects SK-N-SH cells from the cytotoxic effect of conditional supernatant from Aβ₁₋₄₀-treated THP-1 monocytes. Aβ₁₋₄₀-treated THP-1 monocytes also lead to upregulation of cyclooxygenase-2 and iNOS expression and increased of nitric oxide production. These results suggest that Aβ₁₋₄₀-induced activation of PTK/MEK/ERK pathway in THP-1 monocytes leads to the release of inflammatory factors that are toxic to SK-N-SH cells and might contribute to the onset of AD.

Alzheimer's and seizures: interleukin-18, indoleamine 2,3-dioxygenase and quinolinic Acid

Emergent seizures are common in Alzheimer's disease (AD), although the mechanisms mediating this are unknown. It is proposed that stress induced interleukin-18 (IL-18), via interferon-gamma (IFNy) and independently, increases indoleamine 2,3-dioxygenase (IDO) and subsequent quinolinic acid (QA) in microglia. QA increases seizures and concurrently contributes to neuronal loss via excitotoxicity. The ApoE4 allele interacts with IL-18 polymorphisms to increase the risk of AD, and seems likely to potentiate the emergence of seizures. Concurrent changes in IDO and the kynurenine pathways at the blood-brain-barrier (BBB) have implications for treatment, including in the efficacy of different anti-hypertensives. Melatonin is proposed to inhibit these overlapping excitotoxic and neurodegenerative processes, and would be a useful adjunctive treatment.

Ethanol-induced HO-1 and NQO1 are differentially regulated by HIF-1alpha and Nrf2 to attenuate inflammatory cytokine expression

Oxidative stress plays an important role in alcohol-induced inflammation and liver injury. Relatively less is known about how Kupffer cells respond to oxidative stress-induced expression of heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase (NQO1) to blunt inflammation and liver injury. We showed that Kupffer cells from ethanol-fed rats and ethanol-treated rat Kupffer cells and THP-1 cells displayed increased mRNA expression of HO-1, NQO1, and hypoxia-inducible factor-1α (HIF-1α). Our studies showed that silencing with HIF-1α and JNK-1 siRNAs attenuated ethanol-mediated mRNA expression of HO-1, but not NQO1, whereas Nrf2 siRNA attenuated the mRNA expression of both HO-1 and NQO1. Additionally, JunD but not JunB formed an activator protein-1 (AP-1) oligomeric complex to augment HO-1 promoter activity. Ethanol-induced HO-1 transcription involved antioxidant response elements, hypoxia-response elements, and an AP-1 binding motif in its promoter, as demonstrated by mutation analysis of the promoter, EMSA, and ChIP. Furthermore, livers of ethanol-fed c-Jun(fl/fl) mice showed reduced levels of mRNA for HO-1 but not of NQO1 compared with ethanol-fed control rats, supporting the role of c-Jun or the AP-1 transcriptional complex in ethanol-induced HO-1 expression. Additionally, attenuation of HO-1 levels in ethanol-fed c-Jun(fl/fl) mice led to increased proinflammatory cytokine expression in the liver. These results for the first time show that ethanol regulates HO-1 and NQO1 transcription by different signaling pathways. Additionally, up-regulation of HO-1 protects the liver from excessive formation of inflammatory cytokines. These studies provide novel therapeutic targets to ameliorate alcohol induced inflammation and liver injury.

Immunomodulatory and therapeutic activity of curcumin

Inflammation is a disease of vigorous uncontrolled activated immune responses. Overwhelming reports have suggested that the modulation of immune responses by curcumin plays a dominant role in the treatment of inflammation and metabolic diseases. Observations from both in-vitro and in-vivo studies have provided strong evidence towards the therapeutic potential of curcumin. These studies have also identified a plethora of biological targets and intricate mechanisms of action that characterize curcumin as a potent 'drug' for numerous ailments. During inflammation the functional influence of lymphocytes and the related cross-talk can be modulated by curcumin to achieve the desired immune status against diseases. This review describes the regulation of immune responses by curcumin and effectiveness of curcumin in treatment of diseases of diverse nature.

Polymorphisms in glutathione S-transferase omega-1 gene and increased risk of sporadic Alzheimer disease

Previous studies examining the association between the glutathione S-transferase omega-1 (GSTO1) single-nucleotide polymorphisms (SNPs) and Alzheimer disease (AD) have yielded conflicting results. Furthermore, an effect of GSTO1 rs4925 on the age-at-onset (AAO) of AD was found in different studies on sporadic and familial AD cases, but with contrasting findings. A total sample of 103 AD patients, and 157 age- and sex-matched unrelated caregivers from Apulia, southern Italy, were genotyped for the apolipoprotein E (APOE) polymorphism and the GSTO1 rs4925 and rs1804834 SNPs. Furthermore, we performed a haplotype analysis on these two SNPs on the GSTO1 locus and evaluated the possibility of interaction with APOE. Significant differences were observed in rs4925 genotype distribution between AD patients and age- and sex-matched healthy controls. Both the C/A (odds ratio [OR] = 3.116; 95% confidence interval [CI], 1.749-5.550) and the A/A (OR = 10.802; 95% CI, 3.605-32.128) genotypes resulted in an association with AD. A higher frequency of the allele A was observed in AD patients than in age- and sex-matched controls (OR = 3.789; 95% CI, 2.442-5.878). No significant differences were observed in the rs1804834 genotype or allele frequencies between AD patients and controls. No significant influence of the GSTO1 genotypes on the AAO was observed. No significant interaction was found among the GSTO1 SNPs and APOE. In both AD and controls, no important linkage disequilibrium (LD) was observed among the markers investigated. Whereas the C-A haplotype appeared to be protective against AD (OR = 0.303; 95% CI, 0.204-0.451), the A-A haplotype appeared to be at increased risk for AD (OR = 4.014,; 95% CI, 2.528-6.382). Our findings supported a role of the GSTO1 rs4925 SNP in the risk of sporadic AD in southern Italy, suggesting that this and other variants of the GSTO1 gene could be implicated in AD pathogenesis.

Isoflurane anesthesia elicits protein pattern changes in rat hippocampus

Postoperative cognitive dysfunction (POCD) is a known phenomenon occurring after anesthesia with volatile anesthetics (VA), such as isoflurane. Recent reports suggest that VA interact with neurodegenerative disease-associated proteins including compounds with pathogenic relevance in Alzheimer disease (AD) and induce processes that may be linked to AD neuropathology. Unfortunately, our present understanding of the exact anesthetics' molecular mechanisms of action, their side effects on the brain, and their catenation with AD pathology is still limited. The present study analyzes the differential proteome of the hippocampus immediately after and 3 days after a 3-hour 1 minimal alveolar concentration isoflurane anesthesia in rats. Differential 2-dimensional electrophoresis, mass spectrometry, and functional network mapping were used to identify and functionally classify 12 different hippocampal proteins, which were significantly regulated after isoflurane anesthesia (6 up-regulated, 11 down-regulated with P<0.01). Induction of differential expression ranged from 0.05 (25-fold down-regulation) to 4.4 (4.4-fold up-regulation). Ten proteins were regulated immediately after and 7 proteins 3 days after isoflurane exposure. The proteome displays isoflurane-responsive protein candidates, which have also been shown to play a role in AD. They were grouped according to their key biologic activities, which showed that isoflurane affects selected biologic processes including synaptic plasticity, stress response, detoxification, and cytoskeleton in early and late recovery phases after anesthesia. These processes are also affected in AD. Results are discussed in view of AD, the toxicity mechanisms of isoflurane as well as the implications for our present understanding and conduction of clinical anesthesia.

Placenta growth factor-induced early growth response 1 (Egr-1) regulates hypoxia-inducible factor-1alpha (HIF-1alpha) in endothelial cells

Leukotrienes, the lipid inflammatory products derived from arachidonic acid, are involved in the pathogenesis of respiratory and cardiovascular diseases and reactive airway disease in sickle cell disease. Placenta growth factor (PlGF), elaborated from erythroid cells, increased the mRNA expression of 5-lipoxygenase and 5-lipoxygenase-activating protein (FLAP) in human pulmonary microvascular endothelial cells. PlGF-induced both promoter activity and mRNA expression of hypoxia-inducible factor-1alpha (HIF-1alpha), which was abrogated by early growth response-1 (EGR-1) small interfering RNA. PlGF showed a temporal reciprocal relationship in the mRNA levels of EGR-1 and NAB2, the latter a repressor of Egr-1. Moreover, Nab2, but not mutant Nab2, significantly reduced promoter activity and mRNA expression of HIF-1alpha and also reduced expression of the HIF-1alpha target gene FLAP. Furthermore, overexpression of Egr-1 led to increased promoter activities for both HIF-1alpha and FLAP in the absence of PlGF. Additionally, the Egr-1-mediated induction of HIF-1alpha and FLAP promoters was reduced to basal levels by EGR-1 small interfering RNA. The binding of Egr-1 to HIF-1alpha promoter was corroborated by electrophoretic mobility shift assay and chromatin immunoprecipitation assay, which showed increased Egr-1 binding to the HIF-1alpha promoter in response to PlGF stimulation. These studies provide a novel mechanism for PlGF-mediated regulation of HIF-1alpha via Egr-1, which results in increased FLAP expression. This study provides a new therapeutic target, namely Egr-1, for attenuation of elevated leukotriene levels in patients with sickle cell disease and other inflammatory diseases.

Placenta growth factor (PlGF), a novel inducer of plasminogen activator inhibitor-1 (PAI-1) in sickle cell disease (SCD)

Sickle cell disease (SCD) is characterized by a prothrombotic state. Plasminogen activator inhibitor-1 (PAI-1) is known to modulate fibrinolysis, lung injury/fibrosis, and angiogenesis. However, its role in SCD is less understood, and the molecular mechanisms underlying increased PAI-1 are unknown. Herein, we show a novel link between PAI-1 and sickle erythropoiesis. Plasma PAI-1 levels were high in SCD patients at steady state and in two humanized sickle mouse models, with increased PAI-1 immunolabeling in sickle mouse lung, bronchial epithelial cells, alveolar macrophages, and pulmonary microvascular endothelial cells. Placenta growth factor (PlGF), released at high levels by sickle erythroblasts, induced PAI-1 expression in primary human pulmonary microvascular endothelial cells and monocytes through activation of c-Jun N-terminal kinase (JNK), NADPH oxidase, and hypoxia-inducible factor-1alpha (HIF-1alpha). Analysis of the human PAI-1 promoter revealed this induction was mediated by hypoxia-response element (HRE)-1, HRE-2, and distal activator protein (AP-1) sites. We also identify the involvement of c-Jun, c-Jun/c-Fos, and JunD, but not JunB, in binding with AP-1 sites of the PAI-1 promoter upon PlGF induction. Consistent with these findings, levels of PAI-1 were low in PlGF knock-out mice and sickle-PlGF knock-out mice; overexpression of PlGF in normal mice increased circulating PAI-1. In conclusion, we identify a novel mechanism of PAI-1 elevation in SCD.

Hypoxia-mediated expression of 5-lipoxygenase-activating protein involves HIF-1alpha and NF-kappaB and microRNAs 135a and 199a-5p

Hypoxia occurs in a number of pathological states, such as pulmonary, hematological, and cardiovascular disorders. In this study, we examined the molecular mechanism by which hypoxia contributes to increased leukotriene formation. Our studies showed hypoxia augmented the expression of 5-lipoxygenase activating protein (FLAP), a key enzyme in leukotriene formation, in both human pulmonary microvascular endothelial cells and a transformed human brain endothelial cell line. Hypoxia-induced FLAP mRNA expression involved activation of NADPH-oxidase, PI-3 kinase, mitogen-activated protein kinase, NF-kappaB, and hypoxia-inducible factor (HIF)-1alpha. Hypoxia-induced FLAP promoter activity was attenuated on mutation of hypoxia-response elements (HREs) and NF-kappaB binding motif in the FLAP promoter. Hypoxia also augmented binding of HIF-1alpha to HREs in FLAP promoter as demonstrated by EMSA with nuclear extracts. Furthermore, chromain immunoprecipitation analysis showed HIF-1alpha bound to HREs in native chromatin obtained from hypoxia-treated cells. Next, we examined the role of HIF-1alpha regulated microRNAs on FLAP expression. Our studies showed decreased expression of miR-135a and miR-199a-5p in response to hypoxia. However, overexpression of anti-miR-135a and anti-miR-199a-5p oligonucleotides led to a several fold increased FLAP mRNA and protein expression. These studies demonstrate for the first time that hypoxia-mediated FLAP expression is regulated by HREs and NF-kappaB site in its promoter, and negatively regulated by miR-135a and miR-199a-5p, which target the 3'-UTR of FLAP mRNA. An understanding of these regulatory pathways provides new avenues to ameliorate leukotriene formation and hence reactive airway disease, and inflammation in individuals who have sickle cell disease.

Ethanol-induced expression of ET-1 and ET-BR in liver sinusoidal endothelial cells and human endothelial cells involves hypoxia-inducible factor-1alpha and microrNA-199

Chronic alcohol consumption leads to inflammation and cirrhosis of the liver. In this study, we observed that liver sinusoidal endothelial cells (LSEC) derived from ethanol-fed rats showed several fold increases in the mRNA expression of endothelin-1 (ET-1), hypoxia-inducible factor-1alpha (HIF-1alpha), and inflammatory cytochemokines compared with control rat LSEC. We also observed the same results in acute ethanol-treated LSEC from control rats and human dermal microvascular endothelial cells. Ethanol-mediated ET-1 expression involved NADPH oxidase and HIF-1alpha activation. Furthermore, ethanol increased the expression of the ET-1 cognate receptor ET-BR in Kupffer cells and THP-1 monocytic cells, which also involved HIF-1alpha activation. Promoter analysis and chromatin immunoprecipitation showed that hypoxia response element sites in the proximal promoter of ET-1 and ET-BR were required for the binding of HIF-1alpha to up-regulate their expression. We showed that microRNAs, miR-199 among several microRNAs, attenuated HIF-1alpha and ET-1 expression, while anti-miR-199 reversed the effects, suggesting that ethanol-induced miR-199 down-regulation may contribute to augmented HIF-1alpha and ET-1 expression. Our studies, for the first time to our knowledge, show that ethanol-mediated ET-1 and ET-BR expression involve HIF-1alpha, independent of hypoxia. Additionally, ethanol-induced ET-1 expression in rat LSEC is regulated by miR-199, while in human endothelial cells, ET-1 expression is regulated by miR-199 and miR-155, indicating that these microRNAs may function as novel negative regulators to control ET-1 transcription and, thus, homeostatic levels of ET-1 to maintain microcirculatory tone.

Ethanol augments RANTES/CCL5 expression in rat liver sinusoidal endothelial cells and human endothelial cells via activation of NF-kappa B, HIF-1 alpha, and AP-1

Chronic alcohol consumption leads to liver inflammation and cirrhosis. Alcoholic liver disease patients have increased levels of hepatic RANTES/CCL5. However, less is known about the molecular mechanisms for ethanol-induced RANTES up-regulation. In this study, we observed that liver sinusoidal endothelial cells derived from ethanol-fed rats (E-rLSECs) showed severalfold increases in RANTES and hypoxia-inducible factor 1alpha (HIF-1alpha) mRNAs compared with control rLSECs (C-rLSECs). Similar effects were seen in acute ethanol treatment of isolated rLSECs and human dermal microvascular endothelial cells. Ethanol-induced RANTES mRNA expression required ethanol metabolism, p38 MAPK, HIF-1alpha, and JNK-2, but not JNK-1. EMSA experiments showed increased HIF-1alpha binding to wild-type hypoxia response elements (HREs; -31 to -9 bp) within the RANTES promoter in response to ethanol. RANTES promoter analysis showed that cis elements proximal to the transcription start site, HRE-1 (nt -22 to -19), HRE-2 (nt -32 to -29), and AP-1 (nt -250 to -244) were required for ethanol-mediated RANTES expression. These results were corroborated by chromatin immunoprecipitation assays showing augmented HIF-1alpha binding to HRE-1. Additionally, promoter analysis revealed c-Jun, c-Jun/c-Fos, and JunD, but not JunB, bound to the AP-1 site of the RANTES promoter. Ethanol-mediated activation of NF-kappaB led to HIF-1alpha activation and concomitant RANTES expression. Plasma of ethanol-fed c-Jun(flox/flox)-Mx-1-Cre mice showed attenuated levels of RANTES compared with ethanol-fed control mice, supporting the role of c-Jun in ethanol-induced RANTES expression. Our studies showed that ethanol-mediated RANTES/CCL5 expression occurs via HIF-1alpha activation independently of hypoxia. The identification of HIF-1alpha and AP-1 in ethanol-induced RANTES expression provides new strategies to ameliorate ethanol-induced inflammatory responses.

Massive gliosis induced by interleukin-6 suppresses Abeta deposition in vivo: evidence against inflammation as a driving force for amyloid deposition

Proinflammatory stimuli, after amyloid beta (Abeta) deposition, have been hypothesized to create a self-reinforcing positive feedback loop that increases amyloidogenic processing of the Abeta precursor protein (APP), promoting further Abeta accumulation and neuroinflammation in Alzheimer's disease (AD). Interleukin-6 (IL-6), a proinflammatory cytokine, has been shown to be increased in AD patients implying a pathological interaction. To assess the effects of IL-6 on Abeta deposition and APP processing in vivo, we overexpressed murine IL-6 (mIL-6) in the brains of APP transgenic TgCRND8 and TG2576 mice. mIL-6 expression resulted in extensive gliosis and concurrently attenuated Abeta deposition in TgCRND8 mouse brains. This was accompanied by up-regulation of glial phagocytic markers in vivo and resulted in enhanced microglia-mediated phagocytosis of Abeta aggregates in vitro. Further, mIL-6-induced neuroinflammation had no effect on APP processing in TgCRND8 and had no effect on APP processing or steady-state levels of Abeta in young Tg2576 mice. These results indicate that mIL-6-mediated reactive gliosis may be beneficial early in the disease process by potentially enhancing Abeta plaque clearance rather than mediating a neurotoxic feedback loop that exacerbates amyloid pathology. This is the first study that methodically dissects the contribution of mIL-6 with regard to its potential role in modulating Abeta deposition in vivo.