Deoxycholic acid induces proinflammatory cytokine production by model oesophageal cells via lipid rafts.

The bile acid component of gastric refluxate has been implicated in inflammation of the oesophagus including conditions such as gastro-oesophageal reflux disease (GORD) and Barrett's Oesophagus (BO). Here we demonstrate that the hydrophobic bile acid, deoxycholic acid (DCA), stimulated the production of IL-6 and IL-8 mRNA and protein in Het-1A, a model of normal oesophageal cells. DCA-induced production of IL-6 and IL-8 was attenuated by pharmacologic inhibition of the Protein Kinase C (PKC), MAP kinase, tyrosine kinase pathways, by the cholesterol sequestering agent, methyl-beta-cyclodextrin (MCD) and by the hydrophilic bile acid, ursodeoxycholic acid (UDCA). The cholesterol-interacting agent, nystatin, which binds cholesterol without removing it from the membrane, synergized with DCA to induce IL-6 and IL-8. This was inhibited by the tyrosine kinase inhibitor genistein. DCA stimulated the phosphorylation of lipid raft component Src tyrosine kinase (Src). while knockdown of caveolin-1 expression using siRNA resulted in a decreased level of IL-8 production in response to DCA. Taken together, these results demonstrate that DCA stimulates IL-6 and IL-8 production in oesophageal cells via lipid raft-associated signaling. Inhibition of this process using cyclodextrins represents a novel therapeutic approach to the treatment of inflammatory diseases of the oesophagus including GORD and BO.

Secondary (iso)BAs cooperate with endogenous ligands to activate FXR under physiological and pathological conditions.

IsoBAs, stereoisomers of primary and secondary BAs, are found in feces and plasma of human individuals. BA signaling via the nuclear receptor FXR is crucial for regulation of hepatic and intestinal physiology/pathophysiology. AIM: Investigate the ability of BA-stereoisomers to bind and modulate FXR under physiological/pathological conditions. METHODS: Expression-profiling, luciferase-assays, fluorescence-based coactivator-association assays, administration of (iso)-BAs to WT and cholestatic mice. RESULTS: Compared to CDCA/isoCDCA, administration of DCA/isoDCA, UDCA/isoUDCA only slightly increased mRNA expression of FXR target genes; the induction was more evident looking at pre-mRNAs. Notably, almost 50% of isoBAs were metabolized to 3-oxo-BAs within 4 h in cell-based assays, making it difficult to study their actions. FRET-based real-time monitoring of FXR activity revealed that isoCDCA>CDCA stimulated FXR, and isoDCA and isoUDCA allowed fully activated FXR to be re-stimulated by a second dose of GW4064. In vivo co-administration of a single dose of isoBAs followed by GW4064 cooperatively activated FXR, as did feeding of UDCA in a background of endogenous FXR ligands. However, in animals with biliary obstruction and concomitant loss of intestinal BAs, UDCA was unable to increase intestinal Fgf15. In contrast, mice with an impaired enterohepatic circulation of BAs (Asbt-/-, Ostα-/-), administration of UDCA was still able to induce ileal Fgf15 and repress hepatic BA-synthesis, arguing that UDCA is only effective in the presence of endogenous FXR ligands. CONCLUSION: Secondary (iso)BAs cooperatively activate FXR in the presence of endogenous BAs, which is important to consider in diseases linked to disturbances in BA enterohepatic cycling.

Investigation of association of genetic variant rs3918242 of matrix metalloproteinase-9 with hypertension, myocardial infarction and progression of ventricular dysfunction in Irish Caucasian patients with diabetes: a report from the STOP-HF follow-up programme.

BACKGROUND: Hypertension and/or myocardial infarction are common causes of heart failure in Type 2 diabetes. Progression to heart failure is usually preceded by ventricular dysfunction, linked to matrix metalloproteinase (MMP) mediated extracellular matrix changes. We hypothesise that the minor allele of genetic variant rs3918242 in the promoter region of the MMP-9 gene is associated with hypertension and/or myocardial infarction, with resultant progression of dysfunctional cardiac remodelling in patients with diabetes without symptomatic heart failure. METHODS: We genotyped 498 diabetes patients participating in the St Vincent's Screening TO Prevent Heart Failure (STOP-HF) follow-up programme for the rs3918242 single nucleotide polymorphism and investigated associations with the co-primary endpoints hypertension and/or myocardial infarction using a dominant model. We also evaluated resulting cardiometabolic phenotype and progression of ventricular dysfunction and cardiac structural abnormalities over a median follow-up period of 3.5 years. RESULTS: The CT/TT genotype comprised 28.1% of the cohort and was associated with a twofold higher risk of myocardial infarction (17.9% vs 8.4%), a reduction in ejection fraction and greater left ventricular systolic dysfunction progression [adjusted OR = 2.56 (1.09, 6.01), p = 0.026] over a median follow-up of 3.5 years [IQR 2.6, 4.9 years]. Conversely, rs3918242 was not associated with hypertension, blood pressure, pulse pressure or left ventricular mass index at baseline or over follow up. CONCLUSIONS: Diabetes patients with the minor T allele of rs3918242 in the STOP-HF follow up programme have greater risk of myocardial infarction, lower ejection fraction and greater progression of left ventricular systolic abnormalities, a precursor to heart failure. These data may support further work on MMP-9 as a biomarker of ventricular dysfunction and the investigation of MMP-9 inhibitors for heart failure prevention in diabetes, particularly in the post-infarction setting. ClinicalTrials.gov Identifier: NCT00921960.

Impact of Deoxycholic Acid on Oesophageal Adenocarcinoma Invasion: Effect on Matrix Metalloproteinases.

Bile acids (BAs) have been implicated in the development of oesophagitis, Barrett's oesophagus and oesophageal adenocarcinoma (OAC). However, whether BAs promote cancer invasiveness has not been elucidated. We evaluated the role of BAs, in particular deoxycholic acid (DCA), in OAC invasion. Migration and invasiveness in untreated and BA-treated oesophageal SKGT-4 cancer cells were evaluated. Activity and expression of different matrix metalloproteinases (MMPs) were determined by zymography, ELISA, PCR and Western blot. Finally, human OAC tissues were stained for MMP-10 by immunohistochemistry. It was found that SKGT-4 cells incubated with low concentrations of DCA had a significant increase in invasion. In addition, MMP-10 mRNA and protein expression were also increased in the presence of DCA. MMP-10 was found to be highly expressed both in-vitro and in-vivo in neoplastic OAC cells relative to non-neoplastic squamous epithelial cells. Our results show that DCA promotes OAC invasion and MMP-10 overexpression. This study will advance our understanding of the pathophysiological mechanisms involved in human OAC and shows promise for the development of new therapeutic strategies.

Novel Barbiturate-Nitrate Compounds Inhibit the Upregulation of Matrix Metalloproteinase-9 Gene Expression in Intestinal Inflammation through a cGMP-Mediated Pathway.

Matrix metalloproteinase-9 is upregulated in inflammatory bowel disease. Barbiturate nitrate hybrid compounds have been designed to inhibit MMP secretion and enzyme activity. In this study, we investigated the mechanism of action of barbiturate-nitrate hybrid compounds and their component parts using models of intestinal inflammation in vitro. Cytokine-stimulated Caco-2 cells were used in all in vitro experiments. The NO donors SNAP and DETA-NONOate were used to study the effect of NO on MMP-9 mRNA. Mechanistic elucidation was carried out using the soluble guanylate cyclase (sGC) inhibitor, ODQ, and the cGMP analogue, 8-Bromo-cGMP. Further experiments were carried out to elucidate the role of NF-κB. NO donors exerted an inhibitory effect on MMP-9 mRNA in cytokine-stimulated cells. While the non-nitrate barbiturates had a limited effect on MMP-9 expression, the hybrid compounds inhibited MMP-9 expression through its NO-mimetic properties. No effect could be observed on mRNA for MMP-1 or MMP-2. The sGC inhibitior, ODQ, abolished the nitrate-barbiturate inhibition of MMP-9 gene expression, an effect which was reversed by 8-Br-cGMP. This study shows that the barbiturate scaffold is suitable for hybrid design as an MMP-9 inhibitor in cytokine-stimulated Caco-2 cells. The inhibition of MMP-9 levels was largely mediated through a reduction in its mRNA by a sGC/cGMP pathway mediated mechanism.

High Content Imaging of Barrett's-Associated High-Grade Dysplasia Cells After siRNA Library Screening Reveals Acid-Responsive Regulators of Cellular Transitions.

BACKGROUND & AIMS: Esophageal adenocarcinoma (EAC) develops from within Barrett's esophagus (BE) concomitant with gastroesophageal reflux disease (GERD). Wound healing processes and cellular transitions, such as epithelial-mesenchymal transitions, may contribute to the development of BE and the eventual migratory escape of metastatic cancer cells. Herein, we attempt to identify the genes underlying esophageal cellular transitions and their potential regulation by the low pH environments observed in GERD and commonly encountered by escaping cancer cells. METHODS: Small interfering RNA library screening and high-content imaging analysis outlined changes in BE high-grade dysplasia (HGD) and EAC cell morphologies after gene silencing. Gene expression microarray data and low pH exposures studies modeling GERD-associated pulses (pH 4.0, 10 min) and tumor microenvironments (pH 6.0, constant) were used. RESULTS: Statistical analysis of small interfering RNA screening data defined 207 genes (Z-score >2.0), in 12 distinct morphologic clusters, whose suppression significantly altered BE-HGD cell morphology. The most significant genes in this list included KIF11, RRM2, NUBP2, P66BETA, DUX1, UBE3A, ITGB8, GAS1, GPS1, and PRC1. Guided by gene expression microarray study data, both pulsatile and constant low pH exposures were observed to suppress the expression of GPS1 and RRM2 in a nonoverlapping temporal manner in both BE-HGD and EAC cells, with no changes observed in squamous esophageal cells. Functional studies uncovered that GPS1 and RRM2 contributed to amoeboid and mesenchymal cellular transitions, respectively, as characterized by differential rates of cell motility, pseudopodia formation, and altered expression of the mesenchymal markers vimentin and E-cadherin. CONCLUSIONS: Collectively, we have shown that low pH microenvironments associated with GERD, and tumor invasive edges, can modulate the expression of genes that triggered esophageal cellular transitions potentially critical to colonization and invasion.

Cardioprotective effect of MMP-2-inhibitor-NO-donor hybrid against ischaemia/reperfusion injury.

Hypoxic injury of cardiovascular system is one of the most frequent complications following ischaemia. Heart injury arises from increased degradation of contractile proteins, such as myosin light chains (MLCs) and troponin I by matrix metalloproteinase 2 (MMP-2). The aim of the current research was to study the effects of 5-phenyloxyphenyl-5-aminoalkyl nitrate barbiturate (MMP-2-inhibitor-NO-donor hybrid) on hearts subjected to ischaemia/reperfusion (I/R) injury. Primary human cardiac myocytes and Wistar rat hearts perfused using Langendorff method have been used. Human cardiomyocytes or rat hearts were subjected to I/R in the presence or absence of tested hybrid. Haemodynamic parameters of heart function, markers of I/R injury, gene and protein expression of MMP-2, MMP-9, inducible form of NOS (iNOS), asymmetric dimethylarginine (ADMA), as well as MMP-2 activity were measured. Mechanical heart function, coronary flow (CF) and heart rate (HR) were decreased in hearts subjected to I/R Treatment of hearts with the hybrid (1-10 µmol/L) resulted in a concentration-dependent recovery of mechanical function, improved CF and HR. This improvement was associated with decreased tissue injury and reduction of synthesis and activity of MMP-2. Decreased activity of intracellular MMP-2 led to reduced degradation of MLC and improved myocyte contractility in a concentration-dependent manner. An infusion of a MMP-2-inhibitor-NO-donor hybrid into I/R hearts decreased the expression of iNOS and reduced the levels of ADMA. Thus, 5-phenyloxyphenyl-5-aminoalkyl nitrate barbiturate protects heart from I/R injury.

Mesothelial cell autoantibodies upregulate transcription factors associated with fibrosis.

Amphibole asbestos exposure is associated with the production of mesothelial cell autoantibodies (MCAA). These MCAA have been linked with pleural fibrotic disease in the asbestos exposed community of Libby, Montana, and induce collagen deposition by cultured mesothelial cells. However, the exact intracellular mechanism by which these autoantibodies cause an increase in collagen deposition remains unknown. This study sought to gain insight into the transcription factors involved in the collagen production after human mesothelial cells are exposed to MCAA. In this study, transcription factor activation profiles were generated from human mesothelial cells (Met5A) treated with serum from Libby subjects, and were compared to cells treated with serum cleared of IgG, and therefore containing no MCAA. Analysis of those profiles indicated C/EBP-beta and hypoxia inducible factor 1 alpha (HIF-1α) are significantly increased in the nucleus, indicating activation, due to MCAA exposure compared to controls. Inhibition of either of these transcription factors significantly reduced collagen 1 deposition by these cells following exposure to MCAA. These data suggest autoantibodies are directly involved in type I collagen deposition and may elucidate potential therapeutic targets for autoantibody mediated fibrosis.

Inhibition of matrix metalloproteinase-9 by a barbiturate-nitrate hybrid ameliorates dextran sulphate sodium-induced colitis: effect on inflammation-related genes.

BACKGROUND AND PURPOSE: Matrix metalloproteinase-9 (MMP-9) is up-regulated in ulcerative colitis and implicated in the pathology of the disease. In this study, we have examined the effects of a barbiturate-based MMP inhibitor incorporating a nitric oxide donor/mimetic group (dinitrate-barbiturate) on the intestinal injury induced by dextran sulphate sodium (DSS). EXPERIMENTAL APPROACH: In vivo experiments were carried out using male Wistar rats given 5% DSS ad libitum in drinking water. The dinitrate-barbiturate, non-nitrate equivalent, nitrate side chains alone or vehicle were administered rectally, twice daily. MMP-9 release was measured by gelatin zymography, and analysis of gene expression was carried out using RT-qPCR. TaqMan low density arrays were used to evaluate the expression of 91 inflammatory genes in the rat colon. KEY RESULTS: The dinitrate-barbiturate inhibited the induction and activity of MMP-9 during DSS colitis in the rat. This occurred in association with significant reductions in the colitic response to DSS as assessed by an established clinical disease activity index and a pathological colitis grade score. The compound modified expression rates of numerous inflammation-related genes in the colon. CONCLUSIONS AND IMPLICATIONS: This study demonstrated the efficacy of the dinitrate-barbiturate in DSS-induced colitis. Therefore, barbiturate-nitrate hybrids may be developed as a promising anti-inflammatory approach to the treatment of inflammatory bowel disease.

Novel Iron-Whey Protein Microspheres Protect Gut Epithelial Cells from Iron-Related Oxidative Stress and Damage and Improve Iron Absorption in Fasting Adults.

BACKGROUND: Iron food fortification and oral iron formulations are frequently limited by poor absorption, resulting in the widespread use of high-dose oral iron, which is poorly tolerated. METHODS: We evaluated novel iron-denatured whey protein (Iron-WP) microspheres on reactive oxygen species (ROS) and viability in gut epithelial (HT29) cells. We compared iron absorption from Iron-WP versus equimolar-dose (25 mg elemental iron) ferrous sulphate (FeSO4) in a prospective, randomised, cross-over study in fasting volunteers (n = 21 per group) dependent on relative iron depletion (a ferritin level ≤/>30 ng/mL). RESULTS: Iron-WP caused less ROS generation and better HT29 cell viability than equimolar FeSO4. Iron-WP also showed better absorption with a maximal 149 ± 39% increase in serum iron compared to 65 ± 14% for FeSO4 (p = 0.01). The response to both treatments was dependent on relative iron depletion, and multi-variable analysis showed that better absorption with Iron-WP was independent of baseline serum iron, ferritin, transferrin saturation, and haemoglobin in the overall group and in the sub-cohort with relative iron depletion at baseline (p < 0.01). CONCLUSIONS: Novel Iron-WP microspheres may protect gut epithelial cells and improve the absorption of iron versus FeSO4. Further evaluation of this approach to food fortification and supplementation with iron is warranted.

Unconjugated secondary bile acids activate the unfolded protein response and induce golgi fragmentation via a src-kinase-dependant mechanism.

Bile acids are components of gastro-duodenal refluxate and regarded as causative agents in oesophageal disease but the precise mechanisms are unknown. Here we demonstrate that a specific subset of physiological bile acids affect the protein secretory pathway by inducing ER stress, activating the Unfolded Protein Response (UPR) and causing disassembly of the Golgi apparatus in oesophageal cells. Deoxycholic acid (DCA), Chemodeoxycholic acid (CDCA) and Lithocholic acid (LCA) activated the PERK arm of the UPR, via phosphorylation of eIF2α and up-regulation of ATF3, CHOP and BiP/GRP78. UPR activation by these bile acids is mechanistically linked with Golgi fragmentation, as modulating the UPR using a PERK inhibitor (GSK2606414) or salubrinal attenuated bile acid-induced effects on Golgi structure. Furthermore we demonstrate that DCA, CDCA and LA activate Src kinase and that inhibition of this kinase attenuated both bile acid-induced BiP/GRP78 expression and Golgi fragmentation. This study highlights a novel mechanism whereby environmental factors (bile acids) impact important cellular processes regulating cell homeostasis, including the UPR and Golgi structure, which may contribute to cancer progression in the oesophagus.

A fluorescent analogue of tauroursodeoxycholic acid reduces ER stress and is cytoprotective.

Tauroursodeoxycholic acid (TUDCA) is a cytoprotective ER stress inhibitor and chemical chaperone. It has therapeutic potential in a wide array of diseases but a specific macromolecular target or molecular mechanism of action remains obscure. This Letter describes an effective new synthetic approach to taurine conjugation of bile acids which we used to prepare 3α-dansyl TUDCA (4) as a probe for TUDCA actions. As a model of ER stress we used the hepatocarcinoma cell line HUH7 and stimulation with either deoxycholic acid (DCA, 200µM) or tunicamycin (5µg/ml) and measured levels of Bip/GRP78, ATF4, CHOP and XBP1s/XBP1u. Compound 4 was more effective than UDCA at inhibiting ER stress markers and had similar effects to TUDCA. In a model of cholestasis using the cytotoxic DCA to induce apoptosis, pretreatment with 4 prevented cell death similarly to TUDCA whereas the unconjugated clinically used UDCA had no effect. 3α-Dansyl TUDCA (4) appears to be a suitable reporter for TUDCA effects on ER stress and related cytoprotective activity.

Novel Selective Butyrylcholinesterase Inhibitors Incorporating Antioxidant Functionalities as Potential Bimodal Therapeutics for Alzheimer's Disease.

Isosorbide-2-carbamates-5-aryl esters are highly potent and very selective butyrylcholinesterase inhibitors. The objective of the present work was to address the hypothesis that the isosorbide-aryl-5-ester group could be replaced with an antioxidant functionality while maintaining inhibitor effects and selectivity. We successfully incorporated ferulic acid or lipoic acid groups producing potent selective inhibitors of butyrylcholinesterase (BuChE). The hybrid compounds were non-toxic to the murine hippocampal cell line HT-22 and lipoate esters were neuroprotective at 10 and 25 µM when the cells were challenged with glutamate (5 mM) in a similar manner to the positive control quercetin. The benzyl carbamate 7a was a potent inhibitor of BuChE (IC50 150 nM) and it was effective in reducing glutamate toxicity to neuronal cells at >5 µM. Representative compounds exhibited an antioxidant effect in the oxygen radical absorbance capacity assay as the lipoate 7d was not active, whereas the ferulate 8a showed a weak, but significant, activity with 0.635 ± 0.020 Trolox Equivalent.

Libby amphibole-induced mesothelial cell autoantibodies bind to surface plasminogen and alter collagen matrix remodeling.

Lamellar pleural thickening (LPT) is a fibrotic disease induced by exposure to Libby amphibole (LA) asbestos that causes widespread scarring around the lung, resulting in deterioration of pulmonary function. Investigating the effects of autoantibodies to mesothelial cells (MCAA) present in the study populations has been a major part of the effort to understand the mechanism of pathogenesis. It has been shown in vitro that human mesothelial cells (Met5a) exposed to MCAA increase collagen deposition into the extracellular matrix (ECM). In this study, we sought to further elucidate how MCAA drive increased collagen deposition by identifying the protein targets bound by MCAA on the cellular surface using biotinylation to label and isolate surface proteins. Isolated surface protein fractions were identified as containing MCAA targets using ELISA The fractions that demonstrated binding by MCAA were then analyzed by tandem mass spectrometry (MS/MS) and MASCOT analysis. The most promising result from the MASCOT analysis, plasminogen (PLG), was tested for MCAA binding using purified human PLG in an ELISA We report that serum containing MCAA bound at an optical density (OD) 3 times greater than that of controls, and LA-exposed subjects had a high frequency of positive tests for anti-PLG autoantibodies. This work implicates the involvement of the plasminogen/plasmin system in the mechanism of excess collagen deposition in Met5a cells exposed to MCAA Elucidating this mechanism could contribute to the understanding of LPT.

Libby amphibole-induced mesothelial cell autoantibodies promote collagen deposition in mice.

Libby amphibole (LA) causes a unique progressive lamellar pleural fibrosis (LPF) that is associated with pulmonary function decline. Pleural fibrosis among the LA-exposed population of Libby, MT, has been associated with the production of anti-mesothelial cell autoantibodies (MCAA), which induce collagen production from cultured human mesothelial cells. We hypothesized that the progressive nature of LPF could be at least partially attributed to an autoimmune process and sought to demonstrate that LA-induced MCAA trigger collagen deposition in vivo. C57BL/6 mice were exposed to LA for 7 mo, and serum was tested for MCAA by cell-based ELISA on primary mouse mesothelial cells. When treated in vitro with serum from mice exposed to LA, mesothelial cells upregulated collagen matrix production. This effect was lost when the serum was cleared of IgG using protein G beads, implicating IgG autoantibodies. Using the peritoneal cavity as a surrogate for the pleural cavity, groups of naïve (non-asbestos-exposed) mice were injected intraperitoneally with 1) control serum, 2) one dose of serum from LA-exposed mice (LA serum), 3) two doses of LA serum, or 4) two doses of LA serum cleared of IgG. After 1 mo, analysis of collagen in peritoneal walls using two-photon confocal microscopy (SHG analysis) and a hydroxyproline assay demonstrated significant increases in collagen by LA serum but not control or cleared serum. These data support the hypothesis that MCAA in LA-exposed mice induce fibrotic responses in vivo, demonstrating that an autoimmune component may be contributing to the progressive pleural fibrosis seen in LA-exposed patients.

A Central Role for Monocyte-Platelet Interactions in Heart Failure.

Heart failure (HF) is an increasingly prevalent and costly multifactorial syndrome with high morbidity and mortality rates. The exact pathophysiological mechanisms leading to the development of HF are not completely understood. Several emerging paradigms implicate cardiometabolic risk factors, inflammation, endothelial dysfunction, myocardial fibrosis, and myocyte dysfunction as key factors in the gradual progression from a healthy state to HF. Inflammation is now a recognized factor in disease progression in HF and a therapeutic target. Furthermore, the monocyte-platelet interaction has been highlighted as an important pathophysiological link between inflammation, thrombosis, endothelial activation, and myocardial malfunction. The contribution of monocytes and platelets to acute cardiovascular injury and acute HF is well established. However, their role and interaction in the pathogenesis of chronic HF are not well understood. In particular, the cross talk between monocytes and platelets in the peripheral circulation and in the vicinity of the vascular wall in the form of monocyte-platelet complexes (MPCs) may be a crucial element, which influences the pathophysiology and progression of chronic heart disease and HF. In this review, we discuss the role of monocytes and platelets as key mediators of cardiovascular inflammation in HF, the mechanisms of cell activation, and the importance of monocyte-platelet interaction and complexes in HF pathogenesis. Finally, we summarize recent information on pharmacological inhibition of inflammation and studies of antithrombotic strategies in the setting of HF that can inform opportunities for future work. We discuss recent data on monocyte-platelet interactions and the potential benefits of therapy directed at MPCs, particularly in the setting of HF with preserved ejection fraction.

Selective inhibitory effects of 50-nm gold nanoparticles on mouse macrophage and spleen cells.

Nanoparticles (NP) are significant to multiple industrial processes, consumer products and medical applications today. The health effects of many different types of NP, however, are largely unknown. The purpose of this study was to test the effects of 50-nm gold NP coated with poly-N-vinylpyrrolidone (PVP) on mouse macrophage and spleen cells with and without lipopolysaccharide (LPS), testing the hypothesis that the NP would modulate immune responses without being overtly toxic. Gold NP had no effect on macrophage viability and, in the absence of LPS, they had no effect on tumor necrosis factor (TNF)-α production as measured by ELISA. The presence of LPS significantly increased the release of TNFα from the macrophages above no-treatment controls, but increasing gold NP concentration led to decreasing release of TNFα. The reactive oxygen species (ROS) produced by exposed macrophages were also reduced compared to untreated controls, both with and without LPS, suggesting some kind of oxygen radical scavenging. In splenocyte cultures, gold NP had no effect alone, but significantly reduced the release of interleukin (IL)-17 and TNFα triggered by LPS. These results suggest that the gold NP used here are not cytotoxic to immune cells at these concentrations, but may affect cellular responses to infection or inflammation by altering the balance of cytokines.

Pharmacological characterization of nanoparticle-induced platelet microaggregation using quartz crystal microbalance with dissipation: comparison with light aggregometry.

BACKGROUND: Engineered nanoparticles (NPs) can induce platelet activation and aggregation, but the mechanisms underlying these interactions are not well understood. This could be due in part to use of devices that study platelet function under quasi-static conditions with low sensitivity to measure platelet microaggregation. Therefore, in this study we investigated the pharmacological pathways and regulators of NP-induced platelet microaggregation under flow conditions at nanoscale using quartz crystal microbalance with dissipation (QCM-D) and compared the data thus obtained with those generated by light aggregometry. METHODS: Blood was collected from healthy volunteers, and platelet-rich plasma was obtained. Thrombin receptor-activating peptide, a potent stimulator of platelet function, and pharmacological inhibitors were used to modulate platelet microaggregation in the presence/absence of silica (10 nm and 50 nm) and polystyrene (23 nm) NPs. Light aggregometry was used to study platelet aggregation in macroscale. Optical, immunofluorescence, and scanning electron microscopy were also used to visualize platelet aggregates. RESULTS: Platelet microaggregation was enhanced by thrombin receptor-activating peptide, whereas prostacyclin, nitric oxide donors, acetylsalicylic acid, and phenanthroline, but not adenosine diphosphate (ADP) blockers, were able to inhibit platelet microaggregation. NPs caused platelet microaggregation, an effect not detectable by light aggregometry. NP-induced microaggregation was attenuated by platelet inhibitors. CONCLUSION: NP-induced platelet microaggregation appears to involve classical proaggregatory pathways (thromboxane A2-mediated and matrix metalloproteinase-2-mediated) and can be regulated by endogenous (prostacyclin) and pharmacological (acetylsalicylic acid, phenanthroline, and nitric oxide donors) inhibitors of platelet function. Quartz crystal microbalance with dissipation, but not light aggregometry, is an appropriate method for studying NP-induced microaggregation.

Matrix metalloproteinases in inflammatory bowel disease: an update.

Matrix metalloproteinases (MMPs) are known to be upregulated in inflammatory bowel disease (IBD) and other inflammatory conditions, but while their involvement is clear, their role in many settings has yet to be determined. Studies of the involvement of MMPs in IBD since 2006 have revealed an array of immune and stromal cells which release the proteases in response to inflammatory cytokines and growth factors. Through digestion of the extracellular matrix and cleavage of bioactive proteins, a huge diversity of roles have been revealed for the MMPs in IBD, where they have been shown to regulate epithelial barrier function, immune response, angiogenesis, fibrosis, and wound healing. For this reason, MMPs have been recognised as potential biomarkers for disease activity in IBD and inhibition remains a huge area of interest. This review describes new roles of MMPs in the pathophysiology of IBD and suggests future directions for the development of treatment strategies in this condition.

Part Two: Evaluation of N-methylbupropion as a Potential Bupropion Prodrug.

N-methylbupropion was selected as a potential prodrug from our in vitro screening of analogues of bupropion described in the preceding paper. This study describes in vivo pharmacokinetics of N-methylbupropion in the guinea-pig animal model, which is reported to best predict human metabolism of bupropion. The suitability of the guinea pig was established by studying N-demethylation of N-methylbupropion using S9 liver fractions. An LC-MS method was developed and validated to measure N-methylbupropion, bupropion and their metabolites in plasma and brain tissue. In separate studies, the prodrug was delivered by intraperitoneal injection (IP) to assess hepatic metabolism and then by oral gavage (PO) to assess the contribution from intestinal enzymes. Bupropion was administered in parallel. The pharmacokinetic profile of bupropion and N-methylbupropion were not comparable when dosed by intraperitoneal injection but when dosed orally, N-methylbupropion showed a comparable bupropion and metabolite PK plasma profile to bupropion. Plasma and brain levels of N-methylbupropion show that it is extensively metabolized to bupropion and its metabolites, and N-methyl-threo-hydrobupropion. This data coupled to the reduced DAT and NET system in vitro activity described in paper 1 would suggest that the N-methyl derivative of bupropion may have potential as an oral prodrug of bupropion in humans.