NCX-4016, a nitric oxide-releasing aspirin, protects endothelial cells against apoptosis by modulating mitochondrial function

Nonsteroidal Anti-Inflammatory Therapy: A Journey Toward Safety

The efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against inflammation, pain, and fever has been supporting their worldwide use in the treatment of painful conditions and chronic inflammatory diseases until today. However, the long-term therapy with NSAIDs was soon associated with high incidences of adverse events in the gastrointestinal tract. Therefore, the search for novel drugs with improved safety has begun with COX-2 selective inhibitors (coxibs) being straightaway developed and commercialized. Nevertheless, the excitement has fast turned to disappointment when diverse coxibs were withdrawn from the market due to cardiovascular toxicity. Such events have once again triggered the emergence of different strategies to overcome NSAIDs toxicity. Here, an integrative review is provided to address the breakthroughs of two main approaches: (i) the association of NSAIDs with protective mediators and (ii) the design of novel compounds to target downstream and/or multiple enzymes of the arachidonic acid cascade. To date, just one phosphatidylcholine-associated NSAID has already been approved for commercialization. Nevertheless, the preclinical and clinical data obtained so far indicate that both strategies may improve the safety of nonsteroidal anti-inflammatory therapy.

Panax quinquefolium saponin combined with dual antiplatelet drugs inhibits platelet adhesion to injured HUVECs via PI3K/AKT and COX pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Panax quinquefolium saponin (PQS) is the active component extracted from traditional Chinese medicine Panax quinquefolius L. and has been widely used as a supplement to dual antiplatelet drugs (DA) for treatment of coronary artery disease (CAD) for two decades; however, the efficacy of PQS combined with DA against platelet adhesion to endothelial cells (ECs), an essential step in thrombosis, remains unclear.

AIM OF THE STUDY

To compare PQS combined with DA and DA alone in inhibiting platelet adhesion to injured human umbilical vein endothelial cells (HUVECs) and to explore the possible mechanisms focusing on PI3K/AKT, COX-2/6-keto-PGF_1α, and COX-1/TXB₂ pathways.

METHODS

HUVECs injured by oxidized low-density lipoprotein (ox-LDL) were randomly allocated into control, model, DA, PQS+DA (P+DA), LY294002 (a PI3K inhibitor)+DA (L+DA), and LY294002+PQS+DA (LP+DA) groups. HUVEC apoptosis, platelet adhesion to injured HUVECs, and platelet CD62p expression were assayed by fluorescence activated cell sorting (FACS). The concentrations of 6-keto-PGF_1α and TXB₂ in the supernatant were measured by radioimmunoassay. Protein expression of phosphorylated-PI3K, PI3K, phosphorylated-AKT, AKT, COX-1, and COX-2 in both platelets and HUVECs was evaluated by western blot.

RESULTS

Compared to DA alone, PQS combined with DA reduced platelet adhesion to HUVECs and HUVEC apoptosis more potently, increased the concentration of supernatant 6-keto-PGF_1α and up-regulated phospho-AKT protein in HUVECs. LY294002 mitigated the effects of PQS on HUVEC apoptosis and platelet adhesion.

CONCLUSIONS

These findings show that PQS as a powerful supplement to DA, attenuated HUVEC apoptosis and improved the DA-mediated reduction of platelet adhesion to injured HUVECs and the underlying mechanisms may be associated with PI3K/AKT and COX pathways in HUVECs and platelets. PQS might provide a new complementary approach to improve the prognosis of thrombotic diseases in future.

Comparison between Flurbiprofen and its Nitric Oxide-Releasing Derivatives HCT-1026 and NCX-2216 on Aβ(1-42)-Induced Brain Inflammation and Neuronal Damage in the Rat

Brain inflammation is an underlying factor in the pathogenesis of Alzheimer's disease (AD) and epidemiological studies indicate that a sustained use of non-steroidal anti-inflammatory drugs (NSAIDs) has a protective effect on the disease. We investigated, in vivo, whether differences exist in the antiinflammatory and neuroprotective actions of flurbiprofen and its two nitric oxide-donor derivatives, HCT-1026 and NCX-2216, and the ability of these two derivatives to release nitric oxide in the brain. In adult rats injected into the nucleus basalis with preaggregated Aβ(1-42) we investigated by immunohistochemical methods glia reaction, the induction of inducible nitric oxide synthase (iNOS), the activation of p38 mitogen-activated protein kinase (p38MAPK) pathway and the number of choline acetyltransferase (ChAT)-positive neurons and, in naïve rats we investigated, by microdialysis, cortical extracellular levels of nitrite. Injection of Aβ(1-42) induced iNOS at the injection site, activated p38MAPK 7 days after injection and brought about an intense microglia and astrocyte reaction along with a marked reduction in the number of ChAT-positive neurones, persisting up to at least up to 21 days. Flurbiprofen, HCT-1026 and NCX-2216 (15 mg/kg) significantly attenuated the Aβ(1-42)-induced glia reaction, iNOS induction and p38MAPK activation 7 days after treatment and astrocytes reaction 21 days after treatment. On an equimolar basis, HCT-1026 resulted the most active agent in reducing the Aβ(1-42)-induced microglia reaction. The cholinergic cell loss was also significantly reduced by 21 days of HCT-1026 treatment. No differences in the body weight were found between the animals treated for 21 days with 15 mg/kg of either HCT-1026 or NCX-2216 and the controls. An oral administration of HCT-1026 (15 mg/kg) or NCX-2216 (100 mg/kg) to naiïve rats was followed by significant and long long -lasting increases in cortical nitrite levels. These findings indicate that the addition of a nitric oxide donor potentiates the anti-inflammatory activity of flurbiprofen in a model of brain inflammation.

New antiplatelet drugs: beyond aspirin and clopidogrel

Antiplatelet therapy remains a cornerstone of modern management of atherothrombotic vascular disease. For many years, aspirin has been the mainstay of initial antiplatelet drug management in coronary heart disease, while the need for inhibition of other platelet activation pathways has led to the development of various other antiplatelet drugs, such as clopidogrel. An improved understanding of the underlying mechanisms involved in thrombogenesis has paved the way for further development of newer antiplatelet drug therapies. Various clinical studies have probed the effectiveness and risk profile of the newer antiplatelet drugs, such as prasugrel, in comparison with currently available drugs. Some newer agents such as prasugrel are close to being approved for clinical use, whereas other agents such as cangrelor and AZD6140 are in phase 3 clinical trials. New drug classes, such as the thromboxane receptor antagonists (such as NCX-4016 and S18886), as well as platelet adhesion antagonists and thrombin receptor antagonists are similarly being evaluated for their efficacy and risk profile in phase I and II trials.

The nitric oxide-donating derivative of acetylsalicylic acid, NCX 4016, stimulates glucose transport and glucose transporters translocation in 3T3-L1 adipocytes

NCX 4016 is a nitric oxide (NO)-donating derivative of acetylsalicylic acid. NO and salicylate, in vivo metabolites of NCX 4016, were shown to be potential actors in controlling glucose homeostasis. In this study, we evaluated the action of NCX 4016 on the capacity of 3T3-L1 adipocytes to transport glucose in basal and insulin-stimulated conditions. NCX 4016 induced a twofold increase in glucose uptake in parallel with the translocation of the glucose transporters GLUT1 and GLUT4 to the plasma membrane, leaving unaffected their total expression levels. Importantly, NCX 4016 further increased glucose transport induced by a physiological concentration of insulin. The stimulatory effect of NCX 4016 on glucose uptake appears to be mediated by its NO moiety. Indeed, it is inhibited by a NO scavenger and treatment with acetylsalicylic or salicylic acid had no effect. Although NO is involved in the action of NCX 4016, it did not mainly depend on the soluble cGMP cyclase/protein kinase G pathway. Furthermore, NCX 4016-stimulated glucose transport did not involve the insulin-signaling cascade required to stimulate glucose transport. NCX 4016 induces a small activation of the mitogen-activated protein kinases p38 and c-Jun NH(2)-terminal kinase and no activation of other stress-activated signaling molecules, including extracellular signal-regulated kinase, inhibitory factor kappaB, or AMP-activated kinases. Interestingly, NCX 4016 modified the content of S-nitrosylated proteins in adipocytes. Taken together, our results indicate that NCX 4016 induced glucose transport in adipocytes through a novel mechanism possibly involving S-nitrosylation. NCX 4016 thus possesses interesting characteristics to be considered as a candidate molecule for the treatment of patients suffering from metabolic syndrome and type 2 diabetes.

Cardioprotective effects of nitric oxide-aspirin in myocardial ischemia-reperfused rats

In this study, the cardioprotective effects of nitric oxide (NO)-aspirin, the nitroderivative of aspirin, were compared with those of aspirin in an anesthetized rat model of myocardial ischemia-reperfusion. Rats were given aspirin or NO-aspirin orally for 7 consecutive days preceding 25 min of myocardial ischemia followed by 48 h of reperfusion (MI/R). Treatment groups included vehicle (Tween 80), aspirin (30 mg·kg−1·day−1), and NO-aspirin (56 mg·kg−1·day−1). NO-aspirin, compared with aspirin, displayed remarkable cardioprotection in rats subjected to MI/R as determined by the mortality rate and infarct size. Mortality rates for vehicle ( n = 23), aspirin ( n = 22), and NO-aspirin groups ( n = 22) were 34.8, 27.3, and 18.2%, respectively. Infarct size of the vehicle group was 44.5 ± 2.7% of the left ventricle (LV). In contrast, infarct size of the LV decreased in the aspirin- and NO-aspirin-pretreated groups, 36.7 ± 1.8 and 22.9 ± 4.3%, respectively (both P < 0.05 compared with vehicle group; P < 0.05, NO-aspirin vs. aspirin ). Moreover, NO-aspirin also improved ischemiareperfusion-induced myocardial contractile dysfunction on postischemic LV developed pressure. In addition, NO-aspirin downregulated inducible NO synthase (iNOS; 0.37-fold, P < 0.01) and cyclooxygenase-2 (COX-2; 0.61-fold, P < 0.05) gene expression compared with the vehicle group after 48 h of reperfusion. Treatment with NG-nitro-l-arginine methyl ester (l-NAME; 20 mg/kg), a nonselective NOS inhibitor, aggravated myocardial damage in terms of mortality and infarct size but attenuated effects when coadministered with NO-aspirin. l-NAME administration did not alter the increase in iNOS and COX-2 expression but did reverse the NO-aspirin-induced inhibition of expression of the two genes. The beneficial effects of NO-aspirin appeared to be derived largely from the NO moiety, which attenuated myocardial injury to limit infarct size and better recovery of LV function following ischemia and reperfusion.

Role of oxygen in postischemic myocardial injury

Myocardial function is dependent on a constant supply of oxygen from the coronary circulation. A reduction of oxygen supply due to coronary obstruction results in myocardial ischemia, which leads to cardiac dysfunction. Reperfusion of the ischemic myocardium is required for tissue survival. Thrombolytic therapy, coronary artery bypass surgery and coronary angioplasty are some of the treatments available for the restoration of blood flow to the ischemic myocardium. However, the restoration of blood flow may also lead to reperfusion injury, resulting in myocyte death. Thus, any imbalance between oxygen supply and metabolic demand leads to functional, metabolic, morphologic, and electrophysiologic alterations, causing cell death. Myocardial ischemia reperfusion (IR) injury is a multifactorial process that is mediated by oxygen free radicals, neutrophil activation and infiltration, calcium overload, and apoptosis. Controlled reperfusion of the ischemic myocardium has been advocated to prevent the IR injury. Studies have shown that reperfusion injury and postischemic cardiac function are related to the quantity and delivery of oxygen during reperfusion. Substantial evidence suggests that controlled reoxygenation may ameliorate postischemic organ dysfunction. In this review, we discuss the role of oxygenation during reperfusion and subsequent biochemical and pathologic alterations in reperfused myocardium and recovery of heart function.

Kringle 5 of human plasminogen, an angiogenesis inhibitor, induces both autophagy and apoptotic death in endothelial cells

Inhibition of endothelial cell proliferation and angiogenesis is emerging as an important strategy in cancer therapeutics. Kringle 5 (K5) of human plasminogen is a potent angiogenesis inhibitor. Previous studies have shown K5 exposure promotes caspase activity and apoptosis in endothelial cells. Here we report that K5 treatment evokes an autophagic response in endothelial cells that is specific and initiated even in the absence of nutritional stress. Endothelial cells exposed to K5 up-regulated Beclin 1 levels within a few hours. Furthermore, progressively increasing amounts of antiapoptotic Bcl-2 were found to be complexed with Beclin 1, although total levels of Bcl-2 remained unchanged. Prolonged exposure to K5 ultimately led to apoptosis via mitochondrial membrane depolarization and caspase activation in endothelial cells. Knocking down Beclin 1 levels by RNA interference decreased K5 induced autophagy but accelerated K5-induced apoptosis. These studies suggest that interfering with the autophagic survival response can potentiate the antiangiogenic effects of Kringle 5 in endothelial cells.

Functional effects of nitric oxide-releasing aspirin on vein conduits of diabetic patients undergoing CABG

BACKGROUND

Type 2 diabetes mellitus (DM) is known to negatively affect biological properties of venous vasculature, and, particularly, to reduce endothelium-derived nitric oxide release. This condition might influence venous graft function following coronary artery bypass surgery (CABG). The aim of this study was to evaluate the functional effects of a NO-releasing aspirin (NORA) on vein grafts (VG) of diabetics and control patients undergoing elective CABG.

METHODS

In 40 consecutive ischemic heart disease patients, the effects of NORA were tested on segments of saphenous vein conduits harvested during elective CABG. Twenty patients had type-2 DM (mean age 69+/-2), whereas 20 patients had no DM (NDM) and represented the control group (mean age 67+/-4). Functional responses were tested by exposing VGs to NORA and to standard vasoactive agents in an organ-bath preparation. Histological features of VGs were also assessed by light and electronic microscopy.

RESULTS

Significant impairment of endothelial-dependent vasodilation (acetylcholine induced) was documented in VGs of DM subjects. NORA induced a significant and comparable vascular relaxation in all venous segments of NDM and DM patients (56+/-12% of maximal relaxation vs 61+/-11% in the control group, respectively). Histology showed variable extent of vascular layer and cellular abnormalities in VGs of diabetics (intimal hyperplasia, calcific deposition, endothelial cell degeneration) likely responsible of the endothelial functional impairment, whereas control group VG showed preserved structures.

CONCLUSIONS

This preliminary study confirms the impairment of endothelium-dependent vasodilative property of VGs in DM patients. It also indicates that NORA effectively induces vasodilation of VGs which was effective also in DM patients thereby representing a promising therapy for diabetics undergoing CABG with the use of VGs, although further studies are mandatory to conclusively assess the safety and benefits of this pharmacological agent.

Nitric oxide-releasing aspirin: Will it say NO to atherothrombosis?

Aspirin is a powerful anti-platelet drug widely used in patients with coronary atherosclerosis, but its side effects and especially its toxicity for gastrointestinal tract limit its usefulness in specific groups of patients. A new category of agents, nitric oxide-releasing aspirins (such as NCX-4016), seems to provide an alternative solution. Although this drug is still at phase II clinical trials, it has provided promising results until now. When administered in vivo, it is separated into an aspirin moiety and an NO-donating complex, providing both the antithrombotic effect of aspirin and the gastroprotective effect of NO. Additionally, it increases NO bioavailability as a vascular level, and it may have the antiatherogenic properties of endogenously produced NO. Finally, recent evidence suggests that it may also improve functional aspects of vein grafts used in CABG, with possible benefit on graft patency. However, the outcome of the large ongoing trials is needed before any conclusion is made about the role of NO-releasing aspirins in cardiovascular disease.

Novel therapies targeting vascular endothelium

Endothelial dysfunction has been identified as a major mechanism involved in all the stages of atherogenesis. Evaluation of endothelial function seems to have a predictive role in humans, and therapeutic interventions improving nitric oxide bioavailability in the vasculature may improve the long-term outcome in healthy individuals, high-risk subjects, or patients with advanced atherosclerosis. Several therapeutic strategies are now available, targeting both the synthesis and oxidative inactivation of nitric oxide (NO) in human vasculature. Statins seem to be currently the most powerful category of these agents, improving endothelial function and decreasing cardiovascular risk after long-term administration. Other cardiovascular agents improving endothelial function in humans are angiotensin-converting enzyme inhibitors/angiotensin receptors blockers, which increase NO bioavailability by modifying the rennin-angiotensin-aldosterone system. Newer therapeutic approaches targeting endothelial dysfunction in specific disease states include insulin sensitizers, L-arginine (the substrate for endothelial NO synthase [eNOS]) as well as substances that target eNOS "coupling," such as folates or tetrahydrobiopterin. Although there are a variety of strategies to improve NO bioavailability in human endothelium, it is still unclear whether they have any direct benefit at a clinical level.

Prevention of Postischemic Myocardial Reperfusion Injury by the Combined Treatment of NCX-4016 and Tempol

Nitric oxide (NO) plays a protective role in myocardial ischemia-reperfusion (I/R) injury. However, the concomitant production of superoxide and other reactive oxygen species (ROS) during I/R may diminish the bioavailability of NO and hence compromise the beneficial effects. The objective of this study was to investigate the protective effect of the coadministration of NCX-4016 [2-(acetyloxy)benzoic acid 3-(nitrooxymethyl)phenyl ester] (an NO donor) with antioxidants Tempol, superoxide dismutase (SOD), or urate on I/R injury. Isolated rat hearts, perfused with Krebs-Henseleit buffer, were subjected to 30 minutes of global ischemia, followed by 45 minutes of reperfusion. Before the induction of ischemia, the hearts were infused for 1 minute with NCX-4016 (100 microM) either alone or in combination with Tempol (100 microM), SOD (200 U/mL), or urate (100 microM). Hearts pretreated with NCX-4016 showed a significantly enhanced recovery of function and decreased infarct size and LDH/CK release compared with the controls. However, treatment of hearts with NCX-4016 + Tempol, SOD, or urate showed a significantly enhanced recovery of heart function compared with NCX-4016 alone. The treatment of hearts with NCX-4016 + Tempol showed significantly enhanced NO generation and decreased ROS and dityrosine (a marker of peroxynitrite) formation. In conclusion, NCX-4016 in combination with Tempol demonstrated significant cardioprotection and, thus, may offer a novel therapeutic strategy to prevent I/R-mediated myocardial injury.

Pharmacologic Profile and Therapeutic Potential of NCX 4016, a Nitric Oxide-releasing Aspirin, for Cardiovascular Disorders

NCX 4016, 2-(acetyloxy)benzoic acid 3-[(nitrooxy)methyl]phenyl ester, is a new molecule in which a nitric oxide (NO)-releasing moiety is covalently linked to aspirin. After enzymatic metabolism, NCX 4016 releases both components. In vitro and in some animal models, these components exert their pharmacologic effects simultaneously. Nitric oxide (NO) is a small gaseous molecule that exerts several activities which may prevent atherothrombotic disorders. Moreover, it displays a protective activity on the gastric mucosa. NCX 4016 has been shown to inhibit platelet activation in vitro more effectively than aspirin, to inhibit smooth muscle cell proliferation, to exert an endothelial cell protective activity and to suppress the function of several inflammatory cells potentially involved in atherothrombosis. In animal models, NCX 4016 protected from platelet thromboembolism, prevented restenosis in atherosclerosis-prone animals, protected the heart from ischemia/reperfusion injury, and induced neoangiogenesis in critically ischemic limbs. Moreover, it displayed little or no gastric toxicity and appeared to protect stomach from noxious stimuli, including aspirin. NCX 4016 has been evaluated in healthy volunteers and found to inhibit platelet cyclo-oxygenase-1 (COX-1) similarly to or slightly less than aspirin, to raise the circulating levels of NO-degradation products, and to have little or no gastric toxicity in short term studies. In particular, in phase II studies, NCX 4016 had favorable effects on effort-induced endothelial dysfunction in intermittent claudication and on platelet-activation parameters elicited by short-term hyperglycemia in type II diabetics. In patients with type II diabetes the effects of NCX 4016 on microalbuminuria and on some hemodynamic parameters were promising. The pharmacokinetics of in vivo aspirin- and NO- released by NCX 4016, as well as the bioavailability of the two molecules, were not yet adequately studied. Also, the long-term tolerability of NCX 4016, as well as its possible effectiveness in preventing ischemic cardiovascular events and progression of atherosclerosis, should be explored.

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.

Pro-apoptotic effect of a nitric oxide-donating NSAID, NCX 4040, on bladder carcinoma cells

Nitric oxide-releasing non steroidal anti-inflammatory drugs (NO-NSAIDs) are a promising class of compounds that cause cell cycle perturbations and induce apoptosis in cell lines from different tumors. We investigated the activity of a recently developed NO-NSAID (NCX 4040) in bladder cancer cell lines (HT1376 and MCR). Cells were treated with different drug concentrations for different exposure times. Cytostatic and cytocidal activity was tested by SRB assay and apoptosis was evaluated by TUNEL analysis, ANNEXIN V assay and fluorescence microscopy. To further investigate the cell death-inducing mechanisms of NCX 4040, we analyzed gp-170, caspase expression and mitochondrial membrane potential (Delta Psi) depolarization. NCX 4040 showed a striking cytocidal activity in both cell lines, reaching LC(50) at a 10-microM and 50-microM concentrations in HT1376 and in MCR cells, respectively, after an exposure of only 6 h followed by an 18-h washout. Apoptosis was triggered in up to 90% of cells and was associated with active caspase-3 expression and Delta Psi depolarization in both cell lines after a 6-h exposure. In conclusion, NCX 4040, which probably causes apoptosis via a mitochondrial-dependent mechanism, could prove to be a useful agent for improving bladder cancer treatment.

A farnesoid x receptor-small heterodimer partner regulatory cascade modulates tissue metalloproteinase inhibitor-1 and matrix metalloprotease expression in hepatic stellate cells and promotes resolution of liver fibrosis

The farnesoid X receptor (FXR) is expressed by and regulates hepatic stellate cells (HSCs). In the present study, we investigated whether 6-ethyl chenodeoxycholic acid (6-ECDCA or INT-747), a semisynthetic derivative of chenodeoxycholic acid (CDCA), modulates tissue metalloproteinase inhibitor (TIMP)-1 and matrix metalloprotease (MMP)-2 expression/activity in HSCs and in the liver of rats rendered cirrhotic by 4-week administration of CCl(4). Exposure of HSCs to FXR ligands increases small heterodimer partner (SHP) mRNA by 3-fold and reduces basal and thrombin-stimulated expression of alpha1(I)collagen, alpha-smooth muscle actin (alpha-SMA), TIMP-1, and TIMP-2 by approximately 60 to 70%, whereas it increased matrix metalloprotease (MMP)-2 activity by 2-fold. In coimmunoprecipitation, electromobility shift, and transactivation experiments, FXR activation/overexpression caused a SHP-dependent inhibition of JunD binding to its consensus element in the TIMP-1 promoter. Inhibition of TIMP-1 expression by SHP overexpression enhanced the sensitivity of HSCs to proapoptogenic stimuli. Administration of 3 mg/kg 6-ECDCA, but not 15 mg/kg ursodeoxycholic acid, resulted in early (3-5-day) induction of SHP and prevention of early up-regulation of TIMP-1 mRNA induced by CCl(4). In the prevention protocol, 4-week administration of 6-ECDCA reduced alpha1(I)collagen, alpha-SMA, and TIMP-1 mRNA by 60 to 80%, whereas it increased MMP-2 activity by 5-fold. In the resolution protocol, administration of 3 mg/kg 6-ECDCA promoted liver fibrosis resolution and increased the apoptosis of nonparenchyma liver cells. By demonstrating that a FXR-SHP regulatory cascade promotes the development of a quiescent phenotype and increases apoptosis of HSCs, this study establishes that FXR ligands may be beneficial in treatment of liver fibrosis.

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.

The intimate relation between nitric oxide and superoxide in apoptosis and cell survival

Intra- and intercellular communication in or between cells allows adaptation to changes in the environment. Formation of reactive oxygen (ROS) and nitrogen (RNS) species in response to external insults gained considerable attention in provoking cell demise along an apoptotic subroute of cell death, thus attributing radical formation to pathologies. In close association, stabilization of the tumor suppressor p53 and activation of caspases convey proapoptotic signaling. Complexity was added with the notion that ROS and RNS signals overlap and/or produce synergistic as well as antagonistic effects. With respect to nitric oxide (NO) signaling, it became clear that the molecule is endowed with pro- or antiapoptotic signaling capabilities, depending to some extend on the concentration and cellular context, i.e., ROS generation. Here, some established concepts are summarized that allow an explanation of p53 accumulation under the impact of NO and an understanding of NO-evoked cell protection at the level of caspase inhibition, cyclic GMP formation, or expression of antiapoptotic proteins. In addition, the overlapping sphere of ROS and RNS signaling is recapitulated to appreciate cell physiology/pathology with the notion that marginal changes in the flux rates of either NO or superoxide may shift vital signals used for communication and cell survival into areas of pathology in close association with apoptosis/necrosis.

Liver delivery of NO by NCX-1000 protects against acute liver failure and mitochondrial dysfunction induced by APAP in mice

1. NCX-1000, (3alpha, 5beta, 7beta)-3,7-dihydroxycholan-24oic acid[2-methoxy-4-[3-[4-(nitroxy)butoxy]-3-oxo-1-propenyl]phenyl ester, is a nitric oxide (NO)-derivative of ursodeoxyxholic acid (UDCA) that selectively release NO in the liver. 2. Here, we demonstrated that administering mice with 40 micromol kg(-1) NCX-1000, but not UDCA, improves liver histopathology and reduces mortality caused by 330 micromol kg(-1) APAP from 60 to 25% (P<0.01). Administration of NCX-1000, in a therapeutic manner, that is, 2 h after acetaminophen (APAP) intoxication reduced mortality, improved liver histopathology and prevented liver IFN-gamma, TNF-alpha, Fas/Fas ligand and inducible nitric oxide synthase (iNOS) mRNA accumulation caused by APAP. 3. In vitro exposure of primary cultures of mouse hepatocytes to APAP, 6.6 mm, resulted in apoptosis followed by necrosis. Loss of cell viability correlates with early mitochondrial membrane potential (Deltapsi(m)) hyperpolarization followed by depolarization and cytochrome c translocation from mitochondria to cytosol. APAP-induced apoptosis associated with procaspase-3 and -9 cleavage, appearance of truncated Bid and activation of poly(ADP-ribose) polymerase (PARP). 4. Treating primary culture of hepatocytes with 5 microm cyclosporine and 10 microm trifluoperazine for eight resulted in significant reduction of apoptosis induced by APAP suggesting that loss of Deltapsim was mechanistically involved in apoptosis induced by APAP in vitro. 5. NCX-1000, but not UDCA, concentration-dependently (ED(50)=16 microm) protected against Deltapsi(m) depolarization and reduced transition from apoptosis to necrosis caused by 6.6 mm APAP. 6. Treating primary cultures of hepatocytes with the NO-donor DETA-NO, 100 microm, reduced apoptosis induced by APAP and prevented caspase activation. 7. In conclusion, NCX-1000 is effective in protecting against APAP-induced hepatotoxicity when administered in a therapeutic manner. This protection may involve the inhibition of apoptosis and the maintenance of mitochondrial integrity.

Nitric oxide-releasing aspirin derivative, NCX 4016, promotes reparative angiogenesis and prevents apoptosis and oxidative stress in a mouse model of peripheral ischemia

BACKGROUND

Recently, nitric oxide (NO) donors have been developed that mimic the physiological intracellular release of NO. We evaluated whether one of these new compounds, consisting of aspirin coupled to an NO-releasing moiety (NCX 4016), would protect limbs from supervening arterial occlusion.

METHODS AND RESULTS

Mice were assigned to receive regular chow or chow containing NCX 4016 or aspirin (both at 300 mumol/kg body weight, daily) throughout the 3-week experimental period. One week after randomization, they underwent surgical excision of the left femoral artery. Limb blood flow recovery (laser Doppler flowmetry) was accelerated by NCX 4016 as compared with aspirin or vehicle (P<0.05). In controls, histological analysis revealed a 35% increase in the capillary density of ischemic muscles compared with contralateral ones, indicative of spontaneous angiogenesis. Neovascularization was enhanced by NCX 4016 (91%; P<0.05 versus vehicle), but not by aspirin (51%; P=NS versus vehicle). Furthermore, NCX 4016 reduced endothelial cell (EC) apoptosis (4.3+/-1.0 versus 8.7+/-2.0 in aspirin and 12.6+/-3.3 ECs/1000 cap in vehicle; P<0.05 for either comparison) as well as caspase-3 mRNA levels in ischemic muscles ([caspase-3/GAPDH]*100 = 0.09+/-0.04 versus 2.30+/-0.44 in aspirin and 2.30+/-0.32 in vehicle; P<0.01 for either comparison). Nitrite levels and the ratio of reduced to oxidized glutathione were selectively increased in ischemic muscles by NCX 4016. Vascular endothelial growth factor-A expression was reduced by aspirin, with this effect being blunted by NCX 4016.

CONCLUSIONS

Pretreatment with the new oral NO-releasing aspirin derivative stimulates reparative angiogenesis and prevents apoptosis and oxidative stress, thereby alleviating the consequences of supervening arterial occlusion.

Nitric oxide regulates immune cell bioenergetic: a mechanism to understand immunomodulatory functions of nitric oxide-releasing anti-inflammatory drugs

The 2-(acetyloxy)benzoic acid 3-(nitrooxymethyl)phenyl ester (NCX-4016) is a NO-releasing derivative of aspirin. In this study, we provide evidence that NCX-4016 delivered to PMBC-derived T lymphocytes and monocytes causes a transitory inhibition of cell respiration and approximately 50% reduction of cellular ATP, which translates in a time-reversible inhibition of cell proliferation and IL-2, IL-4, IL-5, and IFN-gamma secretion. Exposure of lymphocytes and monocytes to aspirin, 2-(acetyloxy)benzoic acid 3-(hydroxymethyl)phenyl ester (NCX-4017), a non-NO-releasing analog of NCX-4016, and cyclooxygenase inhibitors, reduced PG formation, but has no effect on cytokine/chemokine release. In contrast, delivering NO with (z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino] diazen-1-ium-1,2 diolate (DETA-NO) reproduced most of the metabolic and anti-cytokine activities of NCX-4016. Scavenging NO with hemoglobin or adding selective substrates of complex II, III, and IV of the mitochondrial respiratory chain reverses NCX-4016' inhibitory activities. Exposure to DETA-NO and NCX-4016 enhances glucose uptake, glycolytic rate, and lactate generation in CD3/CD28-costimulated lymphocytes, while reduced citric acid cycle intermediates. These effects were not reproduced by selective and nonselective cyclooxygenase 2 inhibitors. In summary, we demonstrated that exposure of lymphocytes to NCX-4016 causes a metabolic hypoxia that inhibits lymphocyte reactivity to costimulatory molecules, providing a potential counteregulatory mechanism to control activated immune system.

Inhibition of nuclear factor-κB and nitric oxide by curcumin induces G2/M cell cycle arrest and apoptosis in human melanoma cells

Curcumin (diferuloylmethane) inhibits tumour cell growth by inducing apoptosis in many tumour types, including melanoma, via complex and ill-defined pathways. Recent studies have shown that curcumin is both a nitric oxide scavenger and an inhibitor of inducible nitric oxide synthase (iNOS) expression, low levels of which correlate with antiapoptotic function and poor survival and which may be regulated by inhibition of nuclear factor-kappaB (NFkappaB) activation. To elucidate the mechanisms by which curcumin inhibits melanoma proliferation, we tested the in vitro effects of curcumin on specific cell cycle pathways and melanoma cell survival, including NFkappaB activation. Curcumin induced melanoma cell apoptosis and cell cycle arrest, which is associated with the downregulation of NFkappaB activation, iNOS and DNA-dependent protein kinase catalytic subunit expression, and upregulation of p53, p21(Cip1), p27(Kip1) and checkpoint kinase 2. Curcumin also downregulated constitutive iNOS activity in melanoma cells. Our results demonstrate that curcumin arrested cell growth at the G(2)/M phase and induced apoptosis in human melanoma cells by inhibiting NFkappaB activation and thus depletion of endogenous nitric oxide. Therefore, curcumin should be considered further as a potential therapy for patients with melanoma.

Antioxidant activity of nitro derivative of aspirin against ischemia-reperfusion in hamster cheek pouch microcirculation

Aspirin that has been chemically combined with a nitric oxide (NO) donor (NCX-4016) has been shown to inhibit cyclooxygenase and prostaglandin generation while maintaining the inhibitory effects of aspirin. The possible role of reactive oxygen species (ROS) in the action of NCX-4016 in ischemia-reperfusion (I/R) has not been studied. Furthermore, we were interested in comparing the effects of a conventional NO donor [2,2'-hydroxynitrosohydrazino-bis-etanamine (DETA/NO)] and NCX-4016 at the microvascular level in the hamster cheek pouch visualized by using an intravital fluorescent microscopy technique. Microvascular injury was assessed by measuring diameter change, the perfused capillary length (PCL), and leukocyte adhesion. Animals were treated with NCX-4016 (100 mg/kg or 30 mg.kg(-1).day(-1) for 5 days po) or DETA-NO (0.5 mg/kg). Mean arterial blood pressure increased slightly but significantly after NCX-4016 treatment. During 5- and 15-min reperfusion, lipid peroxides in the systemic blood increased by 72 and 89% vs. baseline, respectively, and were still higher than in basal conditions after 30-min reperfusion in the I/R group. Pretreatment with NCX-4016 maintained ROS at normal levels; increased arteriolar diameter, blood flow, and PCL; and decreased leukocyte adhesion (P < 0.05). DETA-NO decreased ROS during 30-min reperfusion; however, later there was a significant increase during reperfusion. DETA-NO decreased leukocyte adhesion (P < 0.05) but microvascular permeability increased after 30 min of reperfusion. In conclusion, NCX-4016 attenuates oxidative stress and prevents arteriolar constriction during I/R, whereas DETA-NO increases lipid peroxides in the systemic blood and permeability after reperfusion.

Polymorphism of NCX4016, an NO-Releasing Derivative of Acetylsalicylic Acid

NCX4016 [2-acetoxybenzoic acid 3'-(nitrooxymethyl)phenyl ester] is a recently developed nitrooxy-derivative of aspirin with improved antiinflammatory, analgesic, and antithrombotic activity as well as increased gastrointestinal safety. Systematic polymorphic screening performed with different solvents and preparation methods resulted in the identification of two polymorphs, designated Forms I and II. They were characterized by scanning electron microscopy, powder X-ray diffraction, thermal analyses, and infrared spectroscopy; the crystal structure of polymorph I was solved by single-crystal X-ray analysis and compared with that of aspirin. Finally, intrinsic dissolution rate studies and calculations according to the melting data method were performed to assess the thermodynamic relationship between the two polymorphs.

Effect of vascular endothelial growth factor and epidermal growth factor on iatrogenic apoptosis in human endothelial cells

To study the effect of growth factors on iatrogenic apoptosis, we examined the influence of vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) on staurosporine-induced apoptosis in primary cultures of human umbilical vein endothelial cells (HUVEC). Apoptosis was evaluated by a cell viability test, the TUNEL-POD assay and the activation of the pro-apoptotic caspase-3. Staurosporine (10-100nM) caused the activation of caspase-3. This effect was manifest after 2hr of incubation and reached its maximum after 5hr. Severe loss of viability followed within 18hr. VEGF or EGF (10-100ng/mL) added together with staurosporine decreased the activation of caspase-3. The loss of viability was 24hr delayed. The action of growth factors was observed at 1% serum concentration but also at concentration optimal for HUVEC survival (10%, v/v). Furthermore, the inhibition of PI-3 kinase (PI-3K) by wortmannin or LY294002 as well as the inhibition of MEK by PD098059 or U0126 prevented the protective effect of VEGF and EGF. Western blotting analysis showed that after 3hr of incubation with staurosporine the level of the anti-apoptotic protein Mcl-1 decreased and this effect was reverted by VEGF. It is concluded that VEGF and EGF antagonize the pro-apoptotic action of staurosporine by the combined signalling of PI-3K and ERKs pathways.

A nitric oxide‐releasing derivative of enalapril, NCX 899, prevents progressive cardiac dysfunction and remodeling in hamsters with heart failure

Nitric oxide (NO) production is known to be impaired in heart failure. A new compound (NCX 899), a NO-releasing derivative of enalapril was characterized, and its actions were evaluated in Bio 14.6 cardiomyopathic (CM) hamsters with heart failure. The hamsters were randomized to oral treatment for 4 weeks with vehicle (n=11), NCX 899 (NCX, 25 mg/kg, n=10), or enalapril (25 mg/kg, n=10). In the vehicle group, fractional shortening by echocardiography decreased (-23.6+/-2.0%) and LV end-diastolic dimension) increased (+10.9+/-1.0%), whereas fractional shortening increased (+17.5+/-4.4%) in NCX and was unchanged in the enalapril group (both P<0.01 vs. vehicle). End-diastolic dimension decreased only in NCX. LV contractility (LVdP/dt max and Emax) was significantly greater in NCX than in enalapril or vehicle, while relaxation (Tau) was shortened in both NCX and enalapril vs. vehicle. ACE activity was inhibited equally by NCX and enalapril in the CM hamster, and plasma nitrate levels were increased only in NCX (P<0.05 vs. enalapril and vehicle). In aortic strips endothelium-independent relaxation occurred only with NCX. The superior effects of NO-releasing enalapril (NCX) vs. enalapril alone to enhance vascular effects, increase LV contractility and prevent unfavorable remodeling and are consistent with vascular delivery of exogenous NO. NCX 899 may hold promise for the future treatment of heart failure.

Nitric oxide in vascular biology

Nitric oxide is a highly versatile heterodiatomic molecule that effects a variety of actions in the vasculture. Originally identified as a principal determination of vascular tone, nitric oxide has since been recognized to exert anti thrombotic, antiproliferative, and anti-inflammatory effects in the vasculture. At higher concentrations and in the setting of other oxidants, nitric oxide can promote vascular pathology. In this review, we summarize the molecular mechanisms of nitric oxides actions in vascular biology and pathology.

Nitric oxide inhibits H2O2-induced transferrin receptor-dependent apoptosis in endothelial cells: Role of ubiquitin-proteasome pathway

We investigated here the mechanism of cytoprotection of nitric oxide (*NO) in bovine aortic endothelial cells treated with H2O2. NONOates were used as *NO donors that released *NO slowly at a well defined rate in the extracellular and intracellular milieus. H2O2-mediated intracellular dichlorofluorescein fluorescence and apoptosis were enhanced by the transferrin receptor (TfR)-mediated iron uptake. *NO inhibited the TfR-mediated iron uptake, dichlorofluorescein fluorescence, and apoptosis in H2O2-treated cells. *NO increased the proteasomal activity and degradation of nitrated TfR via ubiquitination. Nomega-nitro-L-arginine methyl ester, a nonspecific inhibitor of endogenous *NO biosynthesis, decreased the trypsin-like activity of 26S proteasome. *NO, by activating proteolysis, mitigates TfR-dependent iron uptake, dichlorodihydrofluorescein oxidation, and apoptosis in H2O2-treated bovine aortic endothelial cells. The relevance of biological nitration on redox signaling is discussed.

Intracellular release of nitric oxide by NCX 972, an NO-releasing metronidazole, enhances in vitro killing of Entamoeba histolytica

The activity of NCX 972, a new molecule obtained by adding a nitric oxide (NO) moiety to metronidazole, was tested against six isolates of Entamoeba histolytica in xenic cultures. NCX 972 released NO into trophozoite cells and enhanced killing of amoebas in a dose- and time-dependent manner compared to metronidazole.

NO-aspirin: mechanism of action and gastrointestinal safety

Nitric oxide-releasing aspirins are new chemical entities obtained by adding a nitric oxide-releasing moiety to aspirin. NCX-4016 is the prototype of this family of molecules. NCX-4016 consists of the parent molecule (aspirin) linked to a 'spacer' via an ester linkage, which is in turn connected to a nitric oxide-releasing moiety. Both aspirin and nitric oxide moieties of NCX-4016 contribute to its effectiveness, the latter occurring via both cyclic guanosyl monophosphate-dependent and -independent mechanisms. In vitro studies have shown that NCX-4016 inhibits platelet aggregation induced by aspirin-sensitive (arachidonic acid) and aspirin-insensitive (thrombin) agonist. In contrast to aspirin, NCX-4016 exerts a multilevel regulation of inflammatory target, including caspase-1 and NF-kappaB. This broad spectrum of activities translates to an increased potency of this drug in modulating cardiovascular inflammation. Human studies have shown, that while nitric oxide-aspirin maintains its anti-thrombotic activity, it spares the gastrointestinal tract. Indeed, a 7-day course of NCX-4016 results in 90% reduction of gastric damage caused by equimolar doses of aspirin. Further studies are ongoing to define whether this superior anti-inflammatory and anti-thrombotic profile translates in clinical benefits in patients with cardiovascular 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.