Nutrient dynamics in wetland systems associated with hydrological and anthropogenic variations in the south of Samborombón Bay, Argentina

Wetlands provide numerous ecosystem services to the environment, such as nutrient removal and storage. The aim of this work is to evaluate the nutrient dynamics in different sectors within wetland systems in the south of the Samborombón Bay (Argentina) based on hydrological and/or anthropogenic variations. For this purpose, the hydrological features of the wetland were defined through the analysis of satellite images, precipitation and tidal data, and field surveys. Three sectors were identified in the wetland: one with tidal influence, another which is dependent on rainfall, and another that receives inputs from rainfall and from a sewage effluent treatment plant. In order to analyze the nutrient dynamics, samples of surface water, groundwater, and sediments were collected from these sectors. Measurements of pH and electrical conductivity were determined in situ in water samples, while the concentration of inorganic forms of phosphorus and nitrogen, soluble reactive silica, and organic carbon were determined through laboratory analysis. Also, bioavailable phosphorus, organic matter, pH, and electrical conductivity were determined in the sediment samples collected. Statistical analysis of the data reveals differences between the sectors and allows the interpretation of the dynamics of the studied components in the wetland. Electrical conductivity distinguishes the intertidal sectors of the wetland while components associated with P and N discriminate the sectors with inputs from the sewage effluent treatment plant. On the other hand, soluble reactive silica, organic carbon, and organic matter do not seem to be influenced by the tide or effluent discharge. This study demonstrates that the studied wetland works as a nutrient retention area, providing ecosystem services to local inhabitants. Although these services can be utilized, they require a continuous monitoring over time to provide an early warning in case the variations in P and N cycles could lead to eutrophication or wetland degradation.

Assessment of meso- and microplastics distribution in coastal sediments and waters at the middle estuary of the Rio De La Plata, Argentina (SW Atlantic Ocean)

Estuarine coastal water and sediments collected from multiple locations within the middle Río de la Plata (RDLP) estuary were analyzed in order to identify the presence of microplastics (MPs, <5 mm) and mesoplastics (MePs, 5-25 mm) in one of the most significant estuaries in the Southwestern Atlantic. The present study represents one of the first researches to survey MPs and MePs contamination in key stations at RDLP estuary. Average concentrations of 14.17 ± 5.50 MPs/L and 10.00 MePs/L were detected in water samples, while 547.83 ± 620.06 MPs/kg (dry weight) and 74.23 ± 47.29 MePs/kg d.w. were recorded in sediments. The greatest abundances were observed in the more anthropized areas, near urban settlements. Fibers were the most conspicuous plastic items in water and sediments, followed by fragments. On the other hand, surface sediments, and 50 cm and 100 cm-depth sediments also presented MPs and MePs indicating they could serve as a stratigraphic indicator for recently formed sediments. The main polymer type identified were acrylic fibers, followed by polypropylene (PP) and polyethylene terephthalate (PET). Besides, SEM-EDX detected the presence of Si, Fe, Ti, Al and Cl onto the plastics' surface. These elements may serve as additives to enhance the plastics' properties, such as in the case of Ti, or they could originate from the environment, like biogenic Si or Fe, and Al possibly as a component of the suspended particles or sediments adhered to the micro or meso plastics. Finally, the results of the present study showed that MPs and MePs are commonly found in waters and also tend to be trapped in sediments of the RDLP estuary supporting the assertion that these areas play a substantial role in influencing the transport, dispersion, and buildup of MPs in estuarine regions.

Assessment of groundwater-driven dissolved nutrient inputs to coastal wetlands associated with marsh-coastal lagoons systems of the littoral of the outer Río de la Plata estuary

In coastal wetlands the hydrological dynamics and in particular the groundwater flows play a critical role in the establishment of wetlands and in the transport of salts and nutrients. The aim of the work is to analyze the role that groundwater discharge has in the dynamics of the dissolved nutrients of the wetland associated with the coastal lagoon and marshes of the Punta Rasa Natural Reserve, which is located on the coastal sector of the southern end of the Río de la Plata estuary. A monitoring network in the form of transects was generated in order to define groundwater flows and take samples of dissolved species of N and P. The presence of sandy sediments with similar granulometric profiles in all geomorphological environments determines that the underground flow occurs in a homogeneous aquifer. From the dunes and beach ridges the fresh to brackish groundwater flows with a very low hydraulic gradient towards the marsh and coastal lagoon. The contributions of N and P would derive from the degradation of the organic matter of the environment, in the case of the marsh and coastal lagoon also from the tidal flow and discharge of groundwater, and possibly from atmospheric sources in the case of N. Since in all environments oxidizing conditions dominate, nitrification is the main process which is why the most abundant species of N is the NO₃^-. Under oxidizing conditions, P has a greater affinity for the sediments in which it is mostly retained, registering it in low concentrations in water. The discharge of groundwater from the dunes and beach ridges provides dissolved nutrients to the marsh and coastal lagoon. However, the low hydraulic gradient and the dominant oxidizing conditions determine that the flow is scarce and that it only acquires relevance in the contribution of NO₃^-.

A New Potential Resource in the Fight against Candida auris: the Cinnamomum zeylanicum Essential Oil in Synergy with Antifungal Drug

Candida auris is a multidrug-resistant fungus known to be a global public health problem. The skin-based transmission, together with the marked resistance to drugs, resulted in its rapid spread to all continents. The aim of this study was to identify an essential oil (EO) active in the fight against C. auris. A total of 15 EOs were tested against 10 clinical strains of C. auris. Cinnamomum zeylanicum EO (CZ-EO) was the most effective (MIC90 and MFC90 equal to 0.06% vol/vol). Three fractions obtained from CZ-EO, and the cinnamaldehyde (CIN), the major chemical compound, were tested to identify the principal compound effectives against C. auris. All CIN-containing samples showed anti-fungal activity. To study the synergy with fluconazole, CZ-EO, its active fraction (FR2), and CIN were tested in checkerboard tests. Results show that CZ-EO and FR2, but not CIN, synergize with fluconazole. Furthermore, only the copresence of CZ-EO or FR2 synergize with fluconazole at therapeutic concentrations of the drug (0.45 ± 0.32 μg/mL and 0.64 ± 0.67 μg/mL, respectively), while CIN only shows additive activity. In vivo studies conducted on Galleria mellonella larvae show the absence of toxicity of CZ-EO up to concentrations of 16% vol/vol, and the ability of CZ-EO to reactivate the efficacy of fluconazole when formulated at synergic concentrations. Finally, biochemical tests were made to study the mechanism of action of CZ-EO. These studies show that in the presence of both fluconazole and CZ-EO, the activity of fungal ATPases decreases and, at the same time, the amount of intracellular drug increases. IMPORTANCE This study highlights how small doses of CZ-EO are able to inhibit the secretion of fluconazole and promote its accumulation in the fungal cell. In this manner, the drug is able to exert its pharmacological effects bypassing the resistance of the yeast. If further studies will confirm this synergy, it will be possible to develop new therapeutic formulations active in the fight against C. auris resistances.

Hydrogeochemical and isotopic signature of surface and groundwater in a highly industrialized sector of the Rio de la Plata coastal plain (Argentina)

The coastal plain of the middle estuary of the Río de la Plata is a highly industrialized area and is densely populated by sectors. The main human activity in the sector encompassed between the cities of Ensenada and Berisso is associated with the petrochemical industry. In this work, hydrogeochemical and isotopic characteristics of surface and groundwater in the impacted area are analyzed and the results are contrasted with those obtained in an undisturbed protected area. Major and trace elements were determined using standardized methods while the stable isotopes δ¹⁸O y δ²H were analyzed by mass spectroscopy. Human impact is evidenced by the occurrence of large variations in the major chemical composition of water, and also by the elevated concentrations of some trace elements that are not contributed from natural sources. These results may contribute to the understanding of chemical processes and pollutants distribution in highly industrialized coastal plain areas.

Highly specific blockade of CCR5 inhibits leukocyte trafficking and reduces mucosal inflammation in murine colitis

Targeted disruption of leukocyte trafficking to the gut represents a promising approach for the treatment of inflammatory bowel diseases (IBDs). CCR5, the shared receptor for MIP1α and β and RANTES, is expressed by multiple leukocytes. Here, we aimed to determine the role of CCR5 in mediating leukocyte trafficking in models of colitis, and evaluate the therapeutic potential of maraviroc, an orally active CCR5 antagonist used in the treatment of CCR5-tropic HIV. Acute and chronic colitis were induced by administration of DSS or TNBS to wild-type and CCR5^−/− mice or adoptive transfer of splenic naïve CD4⁺ T-cells from wild type or CCR5^−/− mice into RAG-1^−/−. CCR5 gene ablation reduced the mucosal recruitment and activation of CCR5-bearing CD4⁺ and CD11b⁺ leukocytes, resulting in profound attenuation of signs and symptoms of inflammation in the TNBS and transfer models of colitis. In the DSS/TNBS colitis and in the transfer model, maraviroc attenuated development of intestinal inflammation by selectively reducing the recruitment of CCR5 bearing leukocytes. In summary, CCR5 regulates recruitment of blood leukocytes into the colon indicating that targeting CCR5 may offer therapeutic options in IBDs.

Bile acid activated receptors are targets for regulation of integrity of gastrointestinal mucosa

Bile acids are the end product of cholesterol metabolism. Synthesized in the liver, primary bile acids are secreted by hepatocytes and are transformed by intestinal microbiota into secondary bile acids. In addition to their role in cholesterol and lipid absorption, bile acids act as signaling molecules activating a family of nuclear and G-protein-coupled receptors collectively known as bile acid activated receptors (BARs). These receptors are expressed at high density in enterohepatic tissues, but their expression occurs throughout the body and their activation mediates regulatory functions of bile acids on lipids and glucose metabolism and immunity. In the gastrointestinal tract, BARs maintain intestinal integrity, and their deletion makes the intestine more susceptible to the damage caused by acetylsalicylic acid and nonsteroidal anti-inflammatory drugs (NSAIDs). Deficiency in farnesoid X receptor and G-protein-coupled bile acid receptor 1 genes alters the expression/activity of cystathione γ-lyase and endothelial nitric oxide synthase, two genes involved in the synthesis of hydrogen sulfide and nitric oxide, i.e., two gaseous mediators that have been shown to be essential in maintaining the intestinal homeostasis. In addition, farnesoid X receptor regulates the expression of transporters required for secretion of phospholipid by hepatocytes. Because phospholids attenuate intestinal injury caused by acetylsalicylic acid and NSAIDs, BAR agonism could be exploited to protect the intestinal mucosa against injury caused by anti-inflammatory medications. This approach might be useful in the prevention of so-called NSAID enteropathy, a common clinical condition occurring in long-term users of NSAIDs, which is not effectively prevented either by cotreatment with proton pump inhibitors or by the use of coxibs.

Non-invasive hemodynamic analysis in cardiac resynchronization therapy patients wearing quadripolar left ventricular leads: the importance of pacing electrode selection

AIM

Quadripolar left ventricular (LV) leads offer multiple choices for LV pacing increasing programming flexibility. Aim of this study is to assess the influence of LV pacing vector selection on hemodynamic parameters for patients who underwent cardiac resynchronization therapy (CRT) using quadripolar LV lead chronically evaluated with a non-invasive approach by Nexfin(®) system provided analysis (BMEYE B.V., Amsterdam, The Netherlands).

METHODS AND RESULTS

In 16 CRT patients implanted with a quadripolar LV lead (mean follow-up 8,8 ±13,4 months after implantation), we measured Cardiac Output (CO), Mean Blood Pressure (MBP), Total Peripheral Resistance (TPR), LV dP/dt max and Stroke volume (SV) from each one of the ten available bipolar pacing configurations. All the recorded parameters showed marked differences among the ten pacing configurations, but dP/dt max, SV and TPR were those showing the wider range, depending of the selected pacing vector. The average delta for the whole group of subjects between the maximum and minimum hemodynamic values for each pacing configuration were 15.9% for SV, 21.1% for dP/dt max and 20.3% for TPR. Inter-individual analysis of data failed to identify a link between a specific pacing vector and the hemodynamic response.

CONCLUSION

Our study demonstrates that different bipolar pacing configurations, even if arising from a single CS branch, substantially modify the hemodynamic effect of LV pacing in CRT patients. Moreover, the non-invasive hemodynamic analysis suggests the better pacing configuration should be established individually and could represent an important issue in optimizing CRT during follow-up.

In vivo administration of ritonavir worsens intestinal damage caused by cyclooxygease inhibitors

The protease inhibitor ritonavir is part of the highly active anti-retroviral therapy (HAART) successfully used in the treatment of human immunodeficiency virus (HIV)-1 infection. There is evidence that ritonavir alters intestinal permeability and induces damage to the small intestine. Because HIV infected patients taking HAART are at high risk for developing cardiovascular complications, there might be a need for the use of low dose of aspirin (ASA) to prevent ischemic events. Similarly, long term survival exposes HIV infected persons to detrimental interactions of ritonavir with non-steroidal anti-inflammatory drugs (NSAIDs). In the present work we tested whether ritonavir worsens intestinal injury caused by NSAIDs and ASA. C57BL6 mice were treated for 25 days with ritonavir and for a further 5 days with the combination of ritonavir plus ASA or ritonavir plus naproxen. In a second set of experiments C57BL6 mice were cotreated with ritonavir plus misoprostol, a PGE1 analog. We found that ritonavir administration caused intestinal damage and its co-administration with naproxen or ASA exacerbated the severity of injury and intestinal inflammation, as assessed by measuring haematocrit, MPO, mucosal levels of PGE2 and mRNA levels of iNOS, MCP-1 and VLA-1. Co-administration of misoprostol protected against intestinal damage induced by naproxen and ritonavir. In conclusion we demonstrated that ritonavir causes intestinal damage and that its association with NSAIDs or ASA worsens the damage caused by COX-inhibitors. Misoprostol rescues from intestinal damage caused by ritonavir. Further studies are need to clarify whether this observation has a clinical readout.

Activation of the bile acid receptor GPBAR1 protects against gastrointestinal injury caused by non-steroidal anti-inflammatory drugs and aspirin in mice

BACKGROUND AND PURPOSE

Low doses of aspirin (acetylsalicylic acid; ASA) and non-steroidal anti-inflammatory drugs (NSAIDs) increase the risk of gastrointestinal bleeding. GPBAR1 is a bile acid receptor expressed in the gastrointestinal tract. Here, we have investigated whether GPBAR1 was required for mucosal protection in models of gastrointestinal injury caused by ASA and NSAIDs. EXPERIMENTAL APPROCH: GPBAR1(+/+) and GPBAR1(-/-) mice were given ASA (10-50 mg.kg(-1)) or naproxen. Gastric and intestinal mucosal damage was assessed by measuring lesion scores.

KEY RESULTS

Expression of GPBAR1, mRNA and protein, was detected in mouse stomach. Mice lacking GPBAR1 were more sensitive to gastric and intestinal injury caused by ASA and NSAIDs and exhibited a markedly reduced expression of cystathionine-γ-liase (CSE), cystathionine-β-synthase (CBS) and endothelial NOS enzymes required for generation of H(2)S and NO, in the stomach. Treating GPBAR1(+/+) mice with two GPBAR1 agonists, ciprofloxacin and betulinic acid, rescued mice from gastric injury caused by ASA and NSAIDs. The protective effect of these agents was lost in GPBAR1(-/-) mice. Inhibition of CSE by DL-propargylglycine completely reversed protection afforded by ciprofloxacin in wild type mice, whereas treating mice with an H(2)S donor restored the protective effects of ciprofloxacin in GPBAR1(-/-) mice. Deletion of GPBAR1 altered the morphology of the small intestine and increased sensitivity to injury caused by naproxen.

CONCLUSION AND IMPLICATIONS

GPBAR1 is essential to maintain gastric and intestinal mucosal integrity. GPBAR1 agonists protect against gastrointestinal injury caused by ASA and NSAIDs by a COX-independent mechanism.

Activation of the farnesoid-X receptor protects against gastrointestinal injury caused by non-steroidal anti-inflammatory drugs in mice

BACKGROUND AND PURPOSE

Low doses of acetyl salicylic acid (ASA) and non-steroidal anti-inflammatory drugs (NSAIDs) cause gastrointestinal damage. The farnesoid X receptor (FXR) is a bile acid sensor essential for maintenance of intestinal homeostasis. Here, we have investigated whether FXR is required for mucosal protection in models of gastrointestinal injury caused by ASA and NSAIDs and if FXR activation has potential in the treatment or prevention of gastrointestinal injury caused by these agents.

EXPERIMENTAL APPROACH

FXR(+/+) and FXR(-/-) mice were given ASA (10 to 100 mg·kg(-1) ) or NSAIDs. Gastric and intestinal mucosal damage assessed by measuring lesion scores. FXR were activated by giving mice natural (chenodeoxycholic acid; CDCA) or synthetic (GW4064) FXR agonists.

KEY RESULTS

FXR, mRNA and protein, was detected in human and mouse stomach. FXR(-/-) mice were more prone to develop severe gastric and intestinal injury in response to ASA and NSAIDs and showed a severe reduction in the gastrointestinal expression of cystathionine-γ-lyase (CSE), an enzyme required for generation of hydrogen sulphide. CSE expression was reduced by ≈50% in wild-type mice challenged with ASA. Treating wild-type mice but not FXR(-/-) mice with CDCA or GW4064 protected against gastric injury caused by ASA and NSAIDs, by a CSE-dependent and cycloxygenase- and NO-independent, mechanism. FXR activation by GW4064 rescued mice from intestinal injury caused by naproxen.

CONCLUSIONS AND IMPLICATIONS

FXR was essential to maintain gastric and intestinal mucosal barriers. FXR agonists protected against gastric injury caused by ASA and NSAIDs by a CSE-mediated mechanism.

The bile acid sensor farnesoid X receptor is a modulator of liver immunity in a rodent model of acute hepatitis

Immune-mediated liver diseases including autoimmune and viral hepatitis are a major health problem worldwide. In this study, we report that activation of the farnesoid X receptor (FXR), a member of the ligand-activated nuclear receptor superfamily and bile sensor highly expressed in the liver, attenuates liver injury in a model of autoimmune hepatitis induced by Con A. We found that FXR gene ablation results in a time-dependent increase of liver expression (up to 20-fold in a 9-mo-old mouse) of osteopontin, a NKT cell-derived extracellular matrix protein and immunoregulatory cytokine. In comparison to wild-type, FXR(-/-) mice are more susceptible to Con A-induced hepatitis and react to Con A administration by an unregulated production of osteopontin. Administering wild-type mice with a synthetic FXR agonist attenuated Con A-induced liver damage and liver expression of the osteopontin gene. By in vitro studies, we found that FXR is expressed by primarily isolated NKT cells and its ablation favors ostepontin production in response to Con A. Chromatin immunoprecipitation assay and coimmunoprecipitation experiments demonstrate that the short heterodimer partner (SHP), a nuclear receptor and FXR target, was expressed by NKT cell hybridomas and increased in response to FXR activation. FXR activates SHP that interacts with and inhibits c-Jun binding to the osteopontin promoter. These data indicate that in NKT cells, FXR activation causes a SHP-mediated inhibition of osteopontin production. These data support the notion that the bile acid sensor FXR regulates the activation of liver NKT cells.

Glucocorticoid-induced leucine zipper is protective in Th1-mediated models of colitis

BACKGROUND & AIMS

Inflammatory bowel diseases are relatively common diseases of the gastrointestinal tract. The relative therapeutic efficacy of glucocorticoids used in inflammatory bowel diseases resides in part in their capability to inhibit activity of nuclear factor kappaB (NF-kappaB), a transcription factor central to the inflammatory process, and the consequent production of T-helper 1 (Th1)-type cytokines. Previous studies indicate that increased expression in transgenic mice of glucocorticoid-induced leucine zipper (GILZ), a gene rapidly induced by glucocorticoids, inhibits NF-kappaB and Th1 activity.

METHODS

We performed experiments with the aim to test the susceptibility of GILZ transgenic (GILZ-TG) mice to dinitrobenzene sulfonic acid-induced colitis.

RESULTS

Consistent with a decreased Th1 response, GILZ-TG mice were less susceptible to colitis induction as compared with wild-type littermates, while they were more susceptible to Th2-mediated colitis. The inhibition was comparable to that obtained with dexamethasone treatment. Moreover, diminished intestinal tissue damage, associated with inhibition of NF-kappaB nuclear translocation, interferon-gamma, tumor necrosis factor-alpha, and interleukin-1 production in CD4+ T lymphocytes of the lamina propria, was evident in GILZ-TG as compared with wild-type mice. In addition, inhibition of colitis development was also evident when GILZ fusion protein was delivered in vivo in dinitrobenzene sulfonic acid-treated WT animals as well as in interleukin-10 knockout mice.

CONCLUSIONS

Together these results demonstrate that GILZ mimics the effects of glucocorticoids, suggesting a contribution of this protein to the anti-inflammatory activity of glucocorticoids in Th1-induced colitis.

The methionine connection: homocysteine and hydrogen sulfide exert opposite effects on hepatic microcirculation in rats

Increased intrahepatic resistance in cirrhotic livers is caused by endothelial dysfunction and impaired formation of two gaseous vasodilators, nitric oxide (NO) and hydrogen sulfide (H(2)S). Homocysteine, a sulfur-containing amino acid and H(2)S precursor, is formed from hepatic methionine metabolism. In the systemic circulation, hyperhomocystenemia impairs vasodilation and NO production from endothelial cells. Increased blood levels of homocysteine are common in patients with liver cirrhosis. In this study, we demonstrate that acute liver perfusion with homocysteine impairs NO formation and intrahepatic vascular relaxation induced by acetylcholine in methoxamine-precontracted normal livers (7.3% +/- 3.0% versus 26% +/- 2.7%; P < 0.0001). In rats with mild, diet-induced hyperhomocystenemia, the vasodilating activity of acetylcholine was markedly attenuated, and incremental increases in flow induced a greater percentage of increases in perfusion pressure than in control livers. Compared with normal rats, animals rendered cirrhotic by 12 weeks' administration of carbon tetrachloride exhibited a greater percentage of increments in perfusion pressure in response to shear stress (P < 0.05), and intrahepatic resistance to incremental increases in flow was further enhanced by homocysteine (P < 0.05). In normal hyperhomocysteinemic and cirrhotic rat livers, endothelial dysfunction caused by homocysteine was reversed by perfusion of the livers with sodium sulfide. Homocysteine reduced NO release from sinusoidal endothelial cells and also caused hepatic stellate cell contraction; this suggests a dual mechanism of action, with the latter effect being counteracted by H(2)S.

CONCLUSION

Impaired vasodilation and hepatic stellate cell contraction caused by homocysteine contribute to the dynamic component of portal hypertension.

NSAIDs, coxibs, CINOD and H2S-releasing NSAIDs: what lies beyond the horizon

Nonsteroidal anti-inflammatory drugs are widely prescribed for treatment of pain and inflammation, despite their association with gastrointestinal complications, including bleeding and perforation. Inhibition of cyclo-oxygenases, is the main mechanism of action of aspirin and nonsteroidal anti-inflammatory drugs. Non-selective nonsteroidal anti-inflammatory drugs inhibit cyclo-oxygenase-1 and cyclo-oxygenase-2. Inhibition of cyclo-oxygenase-1 derived prostanoids in the stomach represent the underlying mechanism involved in development of gastric and duodenal ulcers in patients taking nonsteroidal anti-inflammatory drugs. Selective cyclo-oxygenases-2 inhibitor (coxibs) spare cyclo-oxygenase-1 show enhanced safety profile in the gastrointestinal tract, but increase the risk of heart attack and stroke. Spurred by these findings, two coxibs, rofecoxib and valdecoxib, were withdrawn from the market. In addition to prostanoids, two gaseous mediators, nitric oxide (NO) and hydrogen sulfide (H(2)S) exert protective effects in gastric mucosa. The inhibitory effects of NO on nonsteroidal anti-inflammatory drugs-induced leukocyte adherence have been exploited in the development of NO-releasing nonsteroidal anti-inflammatory drugs, also indicated as cyclo-oxygenase-inhibiting NO-donating drugs. Despite its non-selective profile versus cyclo-oxygenase isoenzymes, naprocyclo-oxygenase-inhibiting NO-donating drugs, the prototype of this class of anti-inflammatory agents, reduces systemic blood pressure and might have enhanced cardiovascular safety than coxibs, while causing less gastrointestinal damage than its parent drug, the naproxen. H(2)S-releasing nonsteroidal anti-inflammatory drugs derivatives have been recently developed, based on the observed ability of this gaseous mediator to cause vasodilation and to prevent leukocyte adherence. In pre-clinical settings, H(2)S-releasing nonsteroidal anti-inflammatory drugs produce less gastric damage as compared to the parent drugs. Cyclo-oxygenases-inhibiting NO-donating drugs and H(2)S-releasing nonsteroidal anti-inflammatory drugs represent examples of new anti-inflammatory drugs created through the exploitation of the beneficial effects of endogenous gaseous mediators in the gastrointestinal and cardiovascular systems.

Cardiac safety and antitumoral activity of a new nitric oxide derivative of pegylated epirubicin in mice

The use of epirubicin is limited by the risk of a dilatory congestive heart failure that develops as a consequence of induction of a mitochondrial-dependent cardiomyocyte apoptosis. In a previous in-vitro study, we have provided evidence that a new formulation of pegylated epirubicin- bearing moieties that release nitric oxide, named BP-747, exerted a potent antitumoral activity against a colon cancer cell line, which was completely devoid of cytotoxic activity against cardiomyocytes. The aim of this study was to investigate the antitumoral and cardiotoxic profile of BP-747 in Caco-2 and SKOV-2 tumor-bearing mice. Epirubicin-induced cardiomyopathy was detected by clinical (survival, weight loss), anatomical (heart weight loss) and biochemical evaluations (measurement of serum troponin and creatine phosphokinase levels). The antitumoral activity was investigated by the measurement of tumor diameters and weight. In comparison with free epirubicin and pegylated epirubicin, BP-747 showed more potent antineoplastic effects, as demonstrated by the 95% reduction of tumor volume. Moreover, while administration of epirubicin and pegylated epirubicin resulted in the development of a severe anthracycline cardiomyopathy, BP-747-treated mice were virtually devoid of clinical and biochemical signs of cardiotoxicity. The present data provide evidence that addition of a nitric oxide-releasing moiety to pegylated epirubicin confers a new and unique cytotoxic profile to the drug.

Targeting farnesoid X receptor for liver and metabolic disorders

The farnesoid X receptor (FXR) is a metabolic nuclear receptor expressed in the liver, intestine, kidney and adipose tissue. By regulating the expression and function of genes involved in bile acid (BA) synthesis, uptake and excretion, FXR has emerged as a key gene involved in the maintenance of cholesterol and BA homeostasis. FXR ligands are currently under clinical investigation for the treatment of cholestasis, dyslipidemic disorders and conditions of insulin resistance in type 2 diabetes and non-alcoholic steatohepatitis (NASH). Because activation of FXR impacts a considerable number of genes, development of FXR modulators that selectively regulate specific pathways will limit potentially undesirable side effects. Interaction of FXR with other BAs and xenobiotics sensors such as the constitutive androstane receptor and the pregnane X receptor might allow the development of combination therapies for liver and metabolic disorders.

Enhanced activity of a hydrogen sulphide-releasing derivative of mesalamine (ATB-429) in a mouse model of colitis

BACKGROUND AND PURPOSE

Mesalamine is the first-line therapy for colitis, but it lacks potency and is only effective for mild-to-moderate forms of this disease. Hydrogen sulphide has been shown to be a potent, endogenous anti-inflammatory substance, modulating leukocyte-endothelial adhesion and leukocyte migration. The purpose of this study was to determine if an H(2)S-releasing derivative of mesalamine (ATB-429) would exhibit increased potency and effectiveness in a mouse model of colitis.

EXPERIMENTAL APPROACH

Colitis was induced in mice with trinitrobenzene sulphonic acid and the effects of ATB-429 and mesalamine were compared in several treatment regimens. The severity of colitis was determined using several indices, including a disease activity score (comprised of scores for diarrhea, weight loss and fecal blood), colonic myeloperoxidase activity and macroscopic/microscopic scoring of tissue injury.

KEY RESULTS

Irrespective of the treatment regiment, ATB-429 was more effective than mesalamine in reducing the severity of colitis. ATB-429 was particularly effective in reducing granulocyte infiltration into the colonic tissue (by approximately 70%), as well as reducing the expression of mRNA for several key proinflammatory cytokines/chemokines (e.g., TNFalpha, IFNgamma). Treatment with ADT-OH, the H(2)S-releasing moiety of ATB-429, did not affect severity of colitis.

CONCLUSIONS AND IMPLICATIONS

ATB-429 exhibits a marked increase in anti-inflammatory activity and potency in a murine model of colitis, as compared to mesalamine. These results are consistent with recently described anti-inflammatory effects of H(2)S. ATB-429 may represent an attractive alternative to mesalamine for the treatment of inflammatory bowel disease.

GITR modulates innate and adaptive mucosal immunity during the development of experimental colitis in mice

BACKGROUND

Uncontrolled T cell activation and abnormal function of the innate immune system against normal enteric bacterial flora play a critical part in the pathogenesis of inflammatory bowel disease (IBD). Therefore, pharmacological strategies directed to restore the normal responsiveness of the immune system could be efficacious in the treatment of these pathological conditions. Glucocorticoid-induced tumour necrosis factor receptor (GITR)-related gene is a member of the tumour necrosis factor receptor superfamily that is constitutively expressed at high levels on regulatory T cells and at low levels on unstimulated T cells, B cells and macrophages. GITR triggering leads to activation of T effectors and reversal of suppressive function of regulatory T cells.

AIM

To investigate the role of GITR in the development of experimental colitis in mice.

RESULTS

Using GITR(-/-) mice, GITR deletion protected against 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced colitis by reducing innate immune responses and effector T cell activity. Effector T cells isolated from GITR(-/-) mice were less effective than T cells isolated from GITR(+/+) mice to transfer colitis in immunodeficient mice. Blocking the GITR/ligand for GITR (GITRL) signal by giving soluble GITR prevented TNBS-induced colitis in normal GITR(+/+) and also in lymphocyte-deficient SCID mice.

CONCLUSIONS

Collectively, these data suggest that GITR plays a critical part in regulating both acquired and innate mucosal immune responses during the development of experimental colitis in mice. Therefore, targeting the GITR/GITRL system signalling may represent a potential pharmacological tool for the treatment of IBD.

Nitric oxide modulates proapoptotic and antiapoptotic properties of chemotherapy agents: the case of NO-pegylated epirubicin

The use of the anthracycline epirubicin (EPI) is limited by the risk of a dilatory congestive heart failure that develops as a consequence of induction of a mitochondrial-dependent cardiomyocyte and endothelial cell apoptosis. Nitric oxide (NO) increases the antitumoral activity of several chemotherapics, while it provides protection against apoptosis induced by oxidative stress both in endothelial cells and cardiomyocytes. The aim of the present study was to investigate whether the addition of an NO-releasing moiety to a pegylated derivative of EPI (p-EPI-NO) confers to the drug a different cytotoxic profile against tumoral and normal cells. The cytotoxic profile of the drugs was investigated in Caco-2 cell line, in embryonic rat heart-derived myoblasts (H9c2), in adult cardiomyocytes, and in endothelial cells (HUVEC). p-EPI-NO was more efficient than EPI in inducing Caco-2 cell apoptosis, while it spared HUVEC, H9c2 cells and adult cardiomyocytes from EPI-induced toxicity. Exposure of cells to p-EPI-NO resulted in a NO-mediated inhibition of cellular respiration followed by mitochondrial membrane depolarization and cell death in Caco-2 cells but not in HUVEC and H9c2 cells in which mitochondrial membrane polarization was maintained at the expense of glycolytically generated ATP. These findings indicate that addition of an NO-releasing moiety to p-EPI increases the anti-neoplastic activity of the drug, while it reduces its cytotoxicity against nonneoplastic cells.

Circulating anti-actin and anti-ATP synthase antibodies identify a sub-set of patients with idiopathic nephrotic syndrome

Idiopathic nephrotic syndrome (iNS) with resistance or dependence to steroids is a common disease in children but in spite of an increasing clinical impact its pathogenesis is unknown. We screened for the presence of circulating antibodies against glomerular (podocytes, mesangium) and tubular cells (tubular epithelia) a cohort of 60 children with iNS including 8 patients with a familial trait of iNS or with proven mutation of NPHS1-NPHS2 and 12 with good sensitivity to steroids. Positive sera were found in 8 cases, all belonging to the category without familial trait/molecular defects. The targets of antibodies were characterized with Western blot and MALDI-Mass utilizing beta-hexyl cell extracts separated with two-dimensional electrophoresis. In all cases antibodies of the IgM class were directed against ATP synthase beta chain alone (4 cases) or in combination with actin (3 cases); one child presented IgG against aldose reductase. The clinical picture was nephrotic syndrome with steroid resistance or dependence and variable cyclosporin sensitivity; 3 patients developed end stage renal failure. The basic pathology picture was focal segmental glomerulosclerosis (FSGS) in 4 cases and mesangial proliferative glomerulonephrites with deposition of IgM in 2. Overall, patients with circulating auto-antibodies could not be readely differentiated on clinical grounds with the exception of 3 children who developed positivity for antinuclear antibodies during the follow-up. Affinity-purified IgM from one patient who underwent plasmapheresis for therapeutical pourposes (but not from a normal pool) induced proteinuria in Sprague-Dawley rats and concomitant human IgM deposition within glomeruli. This is the first report of circulating anti-actin/ATP synthase beta chain antibodies in a subset of patients with iNS. Both pathological significance and clinical impact given by the presence of these antibodies and the relationship with other conditions such as lupus-erythematosus, characterized by their presence, must be defined.

Different sensitivity of lamina propria T-cell subsets to nitric oxide-induced apoptosis explains immunomodulatory activity of a nitric oxide-releasing derivative of mesalamine in rodent colitis

BACKGROUND & AIMS

Uncontrolled T-cell activation plays a critical role in the pathogenesis of inflammatory bowel diseases. Therefore, pharmacological strategies directed toward restoring the normal responsiveness of the immune system could be effective in the treatment of these pathologic conditions. The addition of a nitric oxide-releasing moiety to conventional drugs, such as aspirin and other anti-inflammatory analgesic drugs, results in new chemical entities with potent immunomodulatory activities. The aim of this study was to investigate the immunomodulatory activity of a nitric oxide-releasing derivative of mesalamine (NCX-456), as compared with standard mesalamine, in 2,4,6-trinitrobenzene sulfonic acid-induced colitis in mice.

METHODS

Cells and tissues from mice with 2,4,6-trinitrobenzene sulfonic acid-induced colitis and from interleukin 10-deficient mice with spontaneous chronic colitis receiving treatment with several doses of NCX-456 or mesalamine were analyzed for morphology, cytokine production, and apoptosis.

RESULTS

NCX-456, but not mesalamine, administration resulted in a marked reduction in clinical, histological, and immunologic signs of colitis in both models. NCX-456 inhibited the release of T-helper type 1-derived cytokines and increased the release of the regulatory T cell-derived cytokines interleukin 10 and transforming growth factor beta. In vitro analyses showed that NCX-456 inhibited proliferation and caused selective apoptosis of the subset of activated lamina propria T-helper type 1 cells, whereas it was ineffective for regulatory T-cell function and survival.

CONCLUSIONS

Collectively, these data show that NCX-456 inhibits lamina propria T-helper type 1 function and stimulates the activity of interleukin 10- and transforming growth factor beta-secreting cells, thus restoring mucosal immune homeostasis and suppressing intestinal inflammation.

Interaction of a selective cyclooxygenase-2 inhibitor with aspirin and NO-releasing aspirin in the human gastric mucosa

In addition to inhibiting cyclooxygenase (COX)-1-derived prostanoid biosynthesis, aspirin acetylates COX-2, enabling the conversion of arachidonic acid to 15(R)-epi lipoxin A4, or aspirin-triggered lipoxin (ATL). Selective COX-2 inhibitors block ATL formation and exacerbate mucosal injury in rats treated with aspirin. In the present study, we have examined whether inhibition of COX-2 activity in healthy volunteers taking aspirin exacerbates gastric mucosal injury and if such an effect would be prevented by NCX-4016, a NO-releasing derivative of aspirin. Thirty-two volunteers were randomized to receive 2 wk of treatment with NCX-4016 (800 mg twice a day) or aspirin (100 mg once a day) alone or in combination with 200 mg of celecoxib twice a day. Mucosal damage was assessed by endoscopy. The mean mucosal injury score was 5.8 +/- 1.8 in subjects treated with aspirin and 2.4 +/- 0.7 (P < 0.01 vs. aspirin) in subjects treated with NCX-4016. Administration of celecoxib increased the injury score in volunteers treated with aspirin (9.9 +/- 1.9) but not in subjects taking NCX-4016 (1.5 +/- 0.8). Aspirin and NCX-4016 caused a comparable suppression of serum thromboxane B2 levels and increased urinary excretion of ATL. Celecoxib inhibited endotoxin-induced prostaglandin E2 generation in whole blood by approximately 80% and abolished ATL formation. These findings suggests that (i) aspirin and NCX-4016 trigger ATL formation in humans, (ii) celecoxib inhibits ATL formation and exacerbates the mucosal injury caused by low doses of aspirin, and (iii) the NO-donating moiety of NCX-4016 protects the gastric mucosa even in the presence of suppression of COX-1 and COX-2.

Galectin-1 suppresses experimental colitis in mice

BACKGROUND & AIMS

Uncontrolled T-cell activation plays a critical role in the pathogenesis of inflammatory bowel diseases. Therefore, pharmacologic strategies directed to restore the normal responsiveness of the immune system by deleting inappropriately activated T cells could be efficacious in the treatment of these pathologic conditions. Galectin-1 is an endogenous lectin expressed in lymphoid organs that plays a role in the maintenance of central and peripheral tolerance. The aim of the present study was to evaluate the therapeutic effects of galectin-1 on T-helper cell type 1-mediated experimental colitis induced by intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) in mice.

METHODS

Cells and tissues from mice with TNBS colitis receiving treatment with several doses of human recombinant galectin-1 (hrGAL-1) were analyzed for morphology, cytokine production, and apoptosis.

RESULTS

Prophylactic and therapeutic administration of rhGAL-1 resulted in a striking improvement in the clinical and histopathologic aspects of the disease. hrGAL-1 reduced the number of hapten-activated spleen T cells, decreased inflammatory cytokine production, and profoundly reduced the ability of lamina propria T cells to produce IFN gamma in vitro. Moreover, hrGAL-1 led to the appearance of apoptotic mononuclear cells in colon tissue when administered in vivo and induced selective apoptosis of TNBS-activated lamina propria T cells in vitro.

CONCLUSION

Collectively, these data show that hrGAL-1 exerts protective and immunomodulatory activity in TNBS-induced colitis and it might be effective in the treatment of inflammatory bowel diseases.

Gastrointestinal safety of NO-aspirin (NCX-4016) in healthy human volunteers: a proof of concept endoscopic study

BACKGROUND AND AIMS

NCX-4016 is a nitric oxide-releasing derivative of aspirin with antiplatelet activity. The aim of this study was to investigate the effect of NCX-4016 on gastrointestinal mucosa and platelet functions in healthy human volunteers.

METHODS

This was a parallel-group, double-blind, placebo-controlled study. Forty healthy subjects were randomly allocated to receive 7 days of treatment with NCX-4016 (400 and 800 mg twice daily), equimolar doses of aspirin (200 and 420 mg twice daily), or placebo. Upper endoscopies were performed before and at the end of the treatment period, and gastroduodenal lesions were graded using a predefined scoring system. Basal and posttreatment platelet aggregation in response to arachidonic acid (AA) and serum thromboxane (TX) B(2) and AA-stimulated platelet TXB(2) production were investigated.

RESULTS

Mucosal endoscopic injury score on day 7 was 0.63 +/- 0.16 in the placebo group and 11.0 +/- 3.0 and 16.1 +/- 1.6 in healthy volunteers treated with 200 and 420 mg aspirin twice daily (P < 0.0001 vs. placebo). NCX-4016 was virtually devoid of gastric and duodenal toxicity, resulting in a total gastric and duodenal endoscopic score of 1.38 +/- 0.3 and 1.25 +/- 0.5 (P < 0.0001 vs. aspirin, not significant vs. placebo). NCX-4016 inhibited AA-induced platelet aggregation as well as serum TXB(2) and platelet TXB(2) generation induced by AA to the same extent as aspirin (not significant vs. aspirin).

CONCLUSIONS

In this study, we have proven the concept that addition of an NO-donating moiety to aspirin results in a new chemical entity that maintains cyclooxygenase-1 and platelet inhibitory activity while nearly avoiding gastrointestinal damage.

IL-1 beta converting enzyme is a target for nitric oxide-releasing aspirin: new insights in the antiinflammatory mechanism of nitric oxide-releasing nonsteroidal antiinflammatory drugs

Caspase-1, the IL-1beta converting enzyme (ICE), is required for intracellular processing/maturation of IL-1beta and IL-18. NO releasing nonsteroidal antiinflammatory drugs (NSAIDs) are a new class of NSAID derivatives that spare the gastric mucosa. Here, we tested the hypothesis that NCX-4016, a NO-aspirin derivative, inhibits proinflammatory cytokine release from endotoxin (LPS)-challenged monocytes. Our results demonstrated that exposing LPS-stimulated human monocytes to NCX-4016 resulted in a 40-80% inhibition of IL-1beta, IL-8, IL-12, IL-18, IFN-gamma, and TNF-alpha release with an EC(50) of 10-20 microM for IL-1beta and IL-18. Incubating LPS-primed monocytes with NCX-4016 resulted in intracellular NO formation as assessed by measuring nitrite/nitrate, intracellular cGMP concentration, and intracellular NO formation. Exposing LPS-stimulated monocytes to aspirin or celecoxib caused a 90% inhibition of prostaglandin E(2) generation but had no effect on cytokine release. NCX-4016, similar to the NO donor S-nitroso-N-acetyl-D-L-penicillamine, inhibited caspase-1 activity with an EC(50) of approximately 20 microM. The inhibition of caspase-1 by NCX-4016 was reversible by the addition of DTT, which is consistent with S-nitrosylation as the mechanism of caspase-1 inhibition. NCX-4016, but not aspirin, prevented ICE activation as measured by assessing the release of ICE p20 subunit. IL-18 immunoneutralization resulted in a 60-80% reduction of IL-1beta, IL-8, IFN-gamma, and TNF-alpha release from LPS-stimulated monocytes. Taken together, these data indicate that incubating human monocytes with NCX-4016 causes intracellular NO formation and suppresses IL-1beta and IL-18 processing by inhibiting caspase-1 activity. Caspase-1 inhibition is a new, cycloxygenase-independent antiinflammatory mechanism of NO-aspirin.

NO-naproxen modulates inflammation, nociception and downregulates T cell response in rat Freund's adjuvant arthritis

1. Anti-inflammatory non steroidal drugs releasing NO (NO-NSAIDs) are a new class of anti-inflammatory drugs to which has been added an NO-releasing moiety. These compounds have been shown to retain the anti-inflammatory, analgesic and antipyretic activity of the parent compound but to be devoid of gastrointestinal (GI) toxicity. 2. Freund's adjuvant (FA) arthritis was induced in rats by a single intraplantar injection into the right hindpaw of 100 microl of mycobacterium butirricum (6 mg ml(-1)). The effect of equimolar doses of naproxen (1, 3 and 10 mg kg(-1)) and NO-naproxen (1.5, 4.5 and 16 mg kg(-1)) was evaluated using two dosage regimen protocols: (i) preventive, starting oral administration of the drugs at the time of induction of arthritis and for the following 21 days (day 1 - 21); (ii) therapeutic, starting oral administration of the drugs 7 days after adjuvant injection and for the following 14 days (day 7 - 21). 3. Hindpaw swelling (days 3, 7, 11, 14, 17, 21) and nociception (days 15 and 21) were measured. On day 22 rats were sacrificed, draining lymph nodes were removed and T cells isolated. In vitro proliferation of T cells following stimulation with concanavalin A (0.5 - 5 microg ml(-1)) was measured using a tritiated thymidine incorporation assay. IL-2 receptor expression on T cells was measured by FACS analysis. 4. Naproxen and NO-naproxen showed similar activity in reducing oedema formation in the non-injected (controlateral) hindpaw. Both drugs showed anti-nociceptive effect. NO-naproxen was anti-nociceptive at a dose of 4.5 mg kg(-1) while naproxen showed the same extent of inhibition only at a dose of 10 mg kg(-1). 5. T cells were isolated and characterized by FACS analysis. Stimulation of isolated T cells with concanavallin A in vitro caused a significant increase in thymidine uptake. NO-naproxen at a dose of 4.5 mg kg(-1) inhibited T cell proliferation to the same extent as 10 mg kg(-1) of naproxen. 6. Inhibition of T cell proliferation was well correlated with reduced IL-2 receptor expression on T cells. In addition, NO-naproxen reduced both IL-1beta and TNFalpha plasma levels whilst naproxen reduced IL-1beta levels only. 7. In conclusion, both naproxen and NO-naproxen reduce inflammation and nociception associated with arthritis. In addition NO-naproxen interferes to a larger extent with cellular mechanism involved in T cell activation in rat adjuvant arthritis indicating that introduction of the NO moiety in the naproxen structure increases the effect at the level of the immune system.

Galectin-1 exerts immunomodulatory and protective effects on concanavalin A-induced hepatitis in mice

Galectin-1, an endogenous lectin with immunomodulatory activities, induces selective, Fas-independent apoptosis of activated T cells. The aim of the present study was to evaluate the effect galectin-1 exerts on concanavalin A (Con A)-induced hepatitis, a T-cell-dependent model of liver injury. Con A administration resulted in liver injury, as shown by the increased transaminase plasma levels and liver DNA fragmentation, and caused spleen T-cell activation, which was associated with a strong increment in liver infiltrating T helper cells. Moreover, Con A injection leads to a marked increase in plasma tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) levels. Galectin-1 pretreatment dose-dependently prevented both liver injury and T-helper cell liver infiltration induced by Con A. In vivo and in vitro experiments indicated that the protective effects of galectin-1 depend on the selective elimination of Con A-activated T cells. In addition, galectin-1 almost completely prevented the Con A-induced increase in plasma TNF-alpha and IFN-gamma, an effect that was, at least in part, independent on the elimination of activated T helper cells, because galectin-1 prevented lipopolysaccharide (LPS)-induced release of TNF-alpha and IFN-gamma also from macrophages in vitro, without affecting their viability. The present study suggests that galectin-1 is potentially useful in the treatment of T-cell-mediated human liver disorders.

NO-aspirin protects from T cell-mediated liver injury by inhibiting caspase-dependent processing of Th1-like cytokines

BACKGROUND & AIMS

Concanavalin A (con A)-induced hepatitis is an immunomediated disease in which assembly of CD4(+) T cells and T helper (Th)1-like cytokines causes Fas-mediated liver cell death. Nitric oxide (NO) modulates Th1 response in vitro. NCX-4016 is an NO-aspirin derivative that spares the gastrointestinal tract and shares molecular targets with NO. The aim of this study was to investigate whether this NO-aspirin modulates Th1-like response induced by con A.

METHODS

BALB/c mice were injected with 0.3 mg con A per mouse alone or in combination with NO-aspirin (18-100 mg/kg) or aspirin (10-55 mg/kg).

RESULTS

NO-aspirin, but not aspirin, caused a dose-dependent protection against liver damage induced by con A. At a dose of 100 mg/kg, NO-aspirin caused a 40%-80% reduction of interleukin (IL)-1beta, IL-12, IL-18, interferon (IFN)-gamma, and tumor necrosis factor alpha production without affecting cytokine messenger RNA expression. NO-aspirin prevented Fas, Fas ligand, and IL-2 receptor up-regulation on spleen lymphocytes and Fas ligand on hepatocytes and caused the S-nitrosylation/inhibition of IL-1beta-converting enzyme-like cysteine proteases (caspases) involved in the processing and maturation of IL-1beta and IL-18. IL-18 immunoneutralization prevented IFN-gamma release and protected from liver injury induced by con A. In contrast to a selective caspase 1 inhibitor, zVAD.FMK, a pancaspase inhibitor, prevented IFN-gamma release and protected the liver from injury.

CONCLUSIONS

Th1-like response induced by con A is mediated by IL-18 and requires activation of multiple caspases. NCX-4016 causes the S-nitrosylation/inhibition of caspases involved in cytokine production. Inhibition of Th1-like response is a new anti-inflammatory mechanism of action of NO-aspirin.

Anti-very late antigen-1 monoclonal antibody modulates the development of secondary lesion and T-cell response in experimental arthritis

Rats injected in the hind paw with a mixture of Mycobacterium butirricum emulsified in mineral oil (FA) developed a severe polyarthritis that shared some immunological features with human rheumatoid arthritis. After this local administration, rats developed a secondary lesion (edema) in the contralateral paw, which is a hallmark of immune system activation. In vivo intravenous treatment with a monoclonal anti-very late antigen (VLA)-1 antibody (HA31/8) significantly reduced the edema formation in the contralateral paw. T cells isolated from contralateral paw draining lymph nodes of FA rats treated with HA31/8 showed a reduced cell proliferation in vitro, after stimulation with concanavalin A. Furthermore FACS analysis showed that the reduction in proliferation was concomitant to a reduction in the number of T cells positive to surface IL-2 receptor expression. Our data indicate that after in vivo treatment with a monoclonal anti-very late antigen-1 antibody, there is a beneficial effect on the development of the secondary lesion, which correlates to the reduced ability of T cells to proliferate in vitro as well as to a reduced surface expression of IL-2 receptor. The association of this antibody to other drugs interfering at other levels in rheumatoid arthritis may open a new therapeutic window.

Gastrointestinal safety of nitric oxide-derived aspirin is related to inhibition of ICE-like cysteine proteases in rats

BACKGROUND & AIMS

Caspases, a class of cysteine proteases, modulate apoptosis. Nitric oxide (NO)-releasing nonsteroidal anti-inflammatory drugs (NSAIDs) are a new class of NSAID derivatives with reduced gastrointestinal toxicity. The aim of this study was to investigate whether cysteine endoproteases are involved in the pathogenesis of NSAID gastropathy and are target for NO-aspirin (NCX-4016).

METHODS

Rats were treated orally with aspirin or equimolar doses of NCX-4016. Caspase activities were measured by fluorometric assay. Apoptosis was quantified by an enzyme-linked immunosorbent assay for histone-associated DNA, DNA ladder on agarose gel, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay. A primary culture of gastric chief cells was used to investigate whether NCX-4016 modulates guanosine 3',5'-cyclic monophosphate (cGMP)-dependent pathways.

RESULTS

Short- and long-term (7 days) aspirin administration resulted in a time- and dose-dependent gastric injury that was associated with apoptosis and caspase up-regulation. Z-VAD.FMK, a pancaspase inhibitor, and NO donors protected from acute damage induced by aspirin. NCX-4016 spared the gastric mucosa and caused caspase inactivation by S-nitrosylation. Inhibition of tumor necrosis factor (TNF)-alpha release or activity by TAPI-2 or anti-TNF-alpha receptor monoclonal antibodies protected against mucosal damage and caspase activation. NCX-4016 protected gastric chief cells from toxicity induced by TNF-alpha by activating cGMP-dependent pathways.

CONCLUSIONS

Aspirin administration leads to a TNF-alpha-dependent activation of gastric caspases. NO-aspirin spares the gastric mucosa and inhibits caspase activity through cGMP-dependent and -independent pathways.

Nitric oxide-releasing NSAIDs inhibit interleukin-1beta converting enzyme-like cysteine proteases and protect endothelial cells from apoptosis induced by TNFalpha

BACKGROUND

Nitric oxide (NO)-releasing NSAIDs are a new class of NSAID derivatives with markedly reduced gastrointestinal toxicity. Although it has been demonstrated that NO-NSAIDs spare gastric mucosal blood flow, molecular determinants involved in this effect are unknown.

AIM

To investigate the effect of aspirin, naproxen and flurbiprofen, and their NO-derivatives, on gastric apoptosis and endothelial cell damage induced by tumour necrosis factor-alpha (TNFalpha). In other systems, TNFalpha-induced apoptosis is mediated by caspases, a growing family of cysteine proteases similar to the IL-1beta converting enzyme (ICE), and so we have investigated whether NO-NSAIDs modulate ICE-like endopeptidases.

METHODS

Rats were treated orally with aspirin, naproxen and flurbiprofen, or their NO-releasing derivatives in equimolar doses, and were killed 3 h later to assess mucosal damage and caspase activity. Endothelial cells (HUVECs) were obtained from human umbilical cord by enzymatic digestion. Caspase 1 and 3 activities were measured by a fluorimetric assay using selective peptides as substrates and inhibitors. Apoptosis was quantified by ELISA specific for histone-associated DNA fragments and by the terminal transferase nick-end translation method (TUNEL).

RESULTS

In vivo NSAID administration caused a time-dependent increase in gastric mucosal damage and caspase activity. NCX-4016, NO-naproxen and NO-flurbiprofen did not cause any mucosal damage and prevented cysteine protease activation. NSAIDs and NO-NSAIDs stimulated TNFalpha release. Exposure to TNFalpha resulted in a time- and concentration-dependent HUVEC apoptosis, an effect that was prevented by pretreating the cells with NCX-4016, NO-naproxen, NO-flurbiprofen, SNP or Z-VAD.FMK, a pan-caspase inhibitor. The activation of ICE-like cysteine proteases was required to mediate TNFalpha-induced apoptosis of HUVECs. Exogenous NO donors inhibited TNFalpha-induced cysteine protease activation. Inhibition of caspase activity was due to S-nitrosylation of ICE/CPP32-like proteases. NO-NSAIDs prevented IL-1beta release from endotoxin-stimulated macrophages.

CONCLUSIONS

NO-releasing NSAIDs are a new class of non-peptide caspase inhibitors. Inhibition of ICE-like cysteine proteases prevents endothelial cell damage induced by pro-inflammatory agents and might contribute to the gastro-protective effects of NO-NSAIDs.

TNFalpha processing enzyme inhibitors prevent aspirin-induced TNFalpha release and protect against gastric mucosal injury in rats

BACKGROUND

Although previous studies indicate that prevention of tumour necrosis factor alpha (TNFalpha) release protects against NSAID-induced gastric mucosal injury, intracellular pathways by which aspirin causes TNFalpha release are unknown. TNFalpha is synthesized as a precursor which is proteolytically cleaved by a specific converting enzyme, TACE, to release the mature cytokine. TACE inhibitors prevent TNFalpha release and protect against TNFalpha-mediated disease.

AIM

To investigate: (i) molecular events that regulate TNFalpha secretion in response to aspirin in vivo and in vitro; (ii) whether TNFalpha secretion inhibitors prevent aspirin-induced TNFalpha release and protect against gastric mucosal damage; and (iii) whether TNFalpha exerts a direct cytotoxic effect on gastric epithelial cells.

METHODS

In vitro studies were carried out on mouse macrophages and rat gastric mucosal cells. Gastric mucosal damage was induced in rats by oral administration of 300 mg/kg aspirin. TNFalpha cytotoxicity on gastric mucosal cells was examined by treating rats with lipopolysaccharide to release TNFalpha or by incubating dispersed gastric mucosal cells with increasing concentrations of TNFalpha.

RESULTS

Aspirin increases intracellular calcium (Ca2+) levels and causes a time and concentration dependent increase in macrophage TNFalpha mRNA accumulation and cytokine release. Agents that cause Ca2+ mobilization with a receptor-independent mechanism, such as ionomycin and thapsigargin, stimulate TNFalpha release. Incubating the macrophages in a Ca2+ free medium inhibited TNFalpha secretion. Agents that prevent TNFalpha mRNA transcription, e.g. lisophylline, PGE2, interleukin-10 and 8-BrcAMP, or TACE inhibitors, e.g. EDTA, TAPI-2 and BB-3103, inhibit TNFalpha release and protect rats against gastric mucosal injury induced by oral administration of aspirin. TNFalpha exerts a direct cytotoxic effect on gastric epithelial cells as demonstrated by the reduced viability observed in gastric mucosal cells prepared from rats treated with lipopolysaccharide, or directly incubated with increasing concentrations of TNFalpha.

CONCLUSIONS

(i) Aspirin directly stimulates TNFalpha gene transcription; (ii) TACE inhibitors protect against aspirin-induced gastric mucosal injury; and (iii) TNFalpha exerts a direct cytotoxic effect on gastric epithelial cells.

NSAIDs upregulate beta 2-integrin expression on human neutrophils through a calcium-dependent pathway

BACKGROUND

Margination of circulating neutrophils (PMN) into the gastric microcirculation is an early and critical event in the pathogenesis of non-steroidal antinflammatory drug (NSAID)-induced gastropathy. This effect is mediated through the upregulation of beta 2 integrins on the PMN surface.

AIMS

To investigate whether indomethacin modulates: (1) Mac-1 expression; (2) Ca2+ mobilization ([Ca2+]i), protein kinase C and nitric oxide accumulation; and (3) mitogen-associated protein kinase phosphorylation in human PMN.

METHODS

Human PMN were isolated by centrifugation through a double Ficoll gradient. [Ca2+]i was measured in PMN loaded with fura-2 and Mac-1 expression by flow cytometry.

RESULTS

Indomethacin caused a concentration- and time-dependent upregulation of CD11b and CD18 expression and PMN adhesion to endothelial cells. Maximal upregulation of Mac-1 expression (40-50%) occurred after a 30-min incubation with 0.1mM indomethacin. The effect was prevented by removing the Ca2+. Ionomycin and thapsigargin caused a 7-10-fold increase in [Ca2+]i and a 2-4-fold increase in Mac-1 expression. Indomethacin induced a concentration-dependent phosphorylation of a 41-kDa mitogen-associated protein kinase. Tyrosine kinase inhibitors prevented the effect of indomethacin on Mac-1 expression and Ca2+ mobilization. Indomethacin and ionomycin increased superoxide generation, myeloperoxidase secretion and PMN adherence to endothelial cells and stimulated nitric oxide production. Indomethacin-induced Mac-1 upregulation was prevented by a nitric oxide synthase inhibitor.

CONCLUSIONS

Indomethacin-induced upregulation of Mac-1 is mediated by changes in [Ca2+]i and nitric oxide. Phosphorylation of the 41-kDa mitogen-associated protein isoform is a previously unreported target of NSAID action. These effects might help to explain the ability of indomethacin to cause gastric neutrophil margination.

Epidermal growth factor modulates pepsinogen secretion in guinea pig gastric chief cells

BACKGROUND & AIMS

Although epidermal growth factor (EGF) inhibits gastric acid secretion, the effects it exerts on gastric chief cells are unknown. The aim of this study was to investigate whether EGF modulates pepsinogen release and intracellular Ca2+ concentrations ([Ca2+]i) and whether the effect involves mitogen-activated protein (MAP) kinase, eicosanoid generation, and nitric oxide.

METHODS

Chief cells were obtained by sequential digestion with collagenase and Ca2+ chelation. [Ca2+]i was measured in cells loaded with Fura-2 and NO generation by the NO coproduct citrulline.

RESULTS

In situ hybridization, immunohistochemistry, and immunoblotting showed that EGF receptor and MAP kinases were constitutively expressed in chief cells. EGF caused a concentration-dependent stimulation of pepsinogen secretion and MAP kinase activity and determined a 2.5-7.0-fold increase in [Ca2+]i, inositol 1,4,5-tryphosphate, prostaglandin E2, and leukotriene B4. Tyrosine kinase inhibitors and cyclooxygenase and lipoxygenase inhibitors reduced pepsinogen secretion and eicosanoid generation induced by EGF. EGF increased citrulline generation and guanosine 3',5'-cyclic monophosphate accumulation sixfold; the effect was blocked by NG monomethyl-L-arginine, which is an NO synthase inhibitor.

CONCLUSIONS

EGF stimulates pepsinogen secretion by activating eicosanoid generation, tyrosine kinases, MAP kinases, Ca2+, NO, and guanosine 3',5'-cyclic monophosphate.

Interleukin 10 reduces lethality and hepatic injury induced by lipopolysaccharide in galactosamine-sensitized mice

BACKGROUND & AIMS

Tumor necrosis factor alpha (TNF-alpha) release plays a pivotal role in the pathogenesis of liver injury induced by lipopolysaccharide (LPS) administration in D-galactosamine (GalN)-sensitized mice. Interleukin (IL) 10 is an anti-inflammatory cytokine that inhibits TNF-alpha synthesis and release both in vitro and in vivo and prevents lethality from experimental endotoxemia. The present study was designed to ascertain whether in vivo treatment with IL-10 protects mice against LPS/GalN-induced liver injury.

METHODS

Mice were treated with an intraperitoneal dose of LPS/GalN with or without IL-10 pretreatment. Liver injury was assessed biochemically and histologically, and plasma TNF-alpha levels, liver myeloperoxidase activity, and adhesion molecule expression were determined.

RESULTS

Administration of LPS in GalN-sensitized mice caused lethal shock and massive hepatic necrosis in almost 100% of the mice. The effect was associated with a significant increase in plasma TNF-alpha concentrations, liver myeloperoxidase activity, and up-regulation of adhesion molecules on liver specimens and circulating neutrophils. Pretreatment with IL-10 reduced plasma TNF-alpha concentrations and LPS/GalN-induced liver injury and lethality. Moreover, IL-10 reduced the LPS/GalN-induced liver neutrophil margination and up-regulation of adhesion molecules both on liver specimens and circulating neutrophils.

CONCLUSIONS

The present results suggest that IL-10 therapy could be useful in the treatment of TNF-alpha-mediated liver diseases.

Selective endoscopic retrograde cholangiography and preoperative bile duct stone removal in patients scheduled for laparoscopic cholecystectomy: a prospective study

OBJECTIVES

Laparoscopic cholecystectomy (LC) has become the treatment of choice for patients with symptomatic cholelithiasis. About 10% of patients with symptomatic gallstones may bear associated common bile duct (CBD) stones. The preferred approach to these patients is the removal of CBD stones by endoscopic retrograde cholangiography (ERCP) before LC. However, ERCP before LC should be performed only in patients with suspected choledocholithiasis. The aims of this study were to: 1) generate an efficacious predictive model for selecting patients with suspected choledocholithiasis to submit to preoperative ERCP, and 2) test the safety of the endoscopic/laparoscopic procedure.

METHODS

Historical, biochemical, and ultrasonographic data were collected prospectively. Receiver operating characteristics curve analysis was adopted for determining optimal biochemical and ultrasonographic cut-off values. Multivariate analysis using logistic regression with generation of the best model identifying independent predictors of CBD stones was also employed.

RESULTS

The optimal model predicted a 95% probability of CBD stones in a patient who presented with elevated ALP (over 300 IU/L) and ALT (over 40 IU/L) levels and CBD dilation > 8 mm at ultrasonography. Endoscopic removal of CBD stones was achieved in 95% of patients, with minimal morbidity and no mortality.

CONCLUSIONS

The identified independent predictors of CBD stones are highly efficient selectors of patients with choledocholithiasis. Moreover, endoscopic removal of CBD stones before LC is a safe and efficacious procedure.

A 4-week, double-blind, parallel-group study to compare the gastrointestinal effects of meloxicam 7.5 mg, meloxicam 15 mg, piroxicam 20 mg and placebo by means of faecal blood loss, endoscopy and symptom evaluation in healthy volunteers

Meloxicam is a new non-steroidal anti-inflammatory drug (NSAID) which preferentially inhibits cyclooxygenase-2 (COX-2) over cyclooxygenase-1 (COX-1). Gastrointestinal (GI) tolerability of meloxicam 7.5 and 15 mg vs piroxicam 20 mg was evaluated in a 4-week, double-blind, parallel group, placebo-controlled study in 51 healthy male volunteers, using a combination of oesphago-gastro-duodenal endoscopy, faecal blood loss measurement and symptom evaluation. Analysis of covariance found no significant difference in faecal blood loss between the groups. However, significantly higher bleeding was found with piroxicam 20 mg compared with placebo using a Student's t-test on the weighted means. Endoscopy score were significantly higher with piroxicam than with meloxicam 7.5 mg or placebo (P < 0.01). A significant difference from baseline was observed in the meloxicam 15 mg and piroxicam groups (P < 0.05), but not in the meloxicam 7.5 mg and placebo groups. Six piroxicam-treated volunteers were withdrawn following a poor endoscopic score, but no such withdrawals occurred in the meloxicam and placebo groups (P < 0.01). Meloxicam 7.5 mg caused less GI damage compared with piroxicam 20 when administered to healthy young volunteers for 28 days; a possible dose dependency effect in GI tolerability was also suggested for meloxicam 7.5 and 15 mg, in relation to endoscopic findings.

Isolated guinea pig gastric chief cells express tumour necrosis factor receptors coupled with the sphingomyelin pathway

The tumour necrosis factor alpha (TNF), has been implicated in the pathogenesis of non-steroidal anti-inflammatory drug (NSAID) induced gastropathy and Helicobacter pylori induced gastritis. Both conditions are characterised by high plasma pepsinogen concentrations, which are thought to reflect an increased rate of enzyme release by the pepsinogen secreting (chief) cells. The mechanisms responsible for this cell dysfunction are unknown. This study investigates whether chief cells express TNF receptors and, if so, whether their activation results in cell death. Immunohistochemical studies conducted with monoclonal antibodies (mAbs) directed against two TNF receptor associated proteins of 55 kDa (TNF-R1) and 75 kDa (TNF-R2) showed that TNF binding sites were expressed in approximately 100% gastric chief cells. Western blot analysis of whole chief cell lysates probed with the TNF-R1 and TNF-R2 mAbs gave two distinct bands of 55 and 75 kDa in the immunoprecipitate. Incubating chief cells with TNF caused concentration and time dependent cell death, which was prevented by pretreating the cells with anti-TNF receptor mAbs. Exposing the cells to TNF reduced sphingomyelin content by 25%. Sphingomyelinase (10(-6) to 10(-2) IU/ml) mimicked the effect of TNF in that it provoked a concentration and time dependent reduction in chief cell viability and increased pepsinogen release. In conclusion, gastric chief cells express two TNF receptors partially linked to the sphingomyelin pathway. TNF induced chief cell dysfunction might be responsible for the high plasma pepsinogen concentrations seen in patients with NSAID gastropathy or H pylori induced gastritis.

Nitric oxide modulates pepsinogen secretion induced by calcium-mediated agonist in guinea pig gastric chief cells

BACKGROUND & AIMS

Nitric oxide, a putative cellular messenger synthesized from L-arginine, is a powerful modulator of gastric motility and secretions. The aim of this study was to investigate whether (1) guinea pig gastric chief cells express NO synthase, (2) NO modulates the pepsinogen secretion and guanosine 3',5'-cyclic monophosphate (cGMP) generation induced by calcium (Ca2+)-mediated agents, and (3) NO donors and cGMP analogues stimulate pepsinogen release.

METHODS

Chief cells were prepared by sequential digestion with collagenase and Ca2+ chelation. NO generation was measured by determining the NO coproduct citrulline.

RESULTS

NO synthase immunoreactivities were constitutively expressed in approximately 70% chief cells. Carbachol (10 mumol/L) caused a 4- 6-fold increase in pepsinogen release, citrulline generation, intracellular Ca2+ concentration ([Ca2+]i) and cGMP concentration. These effects were concentration dependently inhibited by NG-monomethyl-L-arginine (L-NMMA). As gastrin, cholecystokinin, thapsigargin, and Ca2+ ionophore increased NO generation, [Ca2+]i seemed to regulate NO synthase activity. [Ca2+]i chelator and calmodulin antagonist inhibited the carbachol-induced pepsinogen secretion and NO generation. Preincubating the cells with L-NMMA had no effect on carbachol-stimulated inositol triphosphate generation or [Ca2+]i or Ca(2+)-dependent adenosine triphosphatase levels. Nitrovasodilator agents and 8-bromo-cGMP stimulated pepsinogen release.

CONCLUSIONS

Gastric chief cells express a Ca2+/calmodulin-dependent NO synthase. NO modulates the stimulatory effect of Ca(2+)-mediated agonists on pepsinogen release.