Alpha-lipoic acid inhibits TNF-alpha-induced NF-kappaB activation and adhesion molecule expression in human aortic endothelial cells

Polyamine synthesis inhibition induces S phase cell cycle arrest in vascular smooth muscle cells

Polyamines are important for cell growth and proliferation and they are formed from arginine and ornithine via arginase and ornithine decarboxylase (ODC). Arginine may alternatively be metabolised to NO via NO synthase. Here we study if vascular smooth muscle cell proliferation can be reversed by polyamine synthesis inhibitors and investigate their mechanism of action. Cell proliferation was assessed in cultured vascular smooth muscle A7r5 cells and in endothelium-denuded rat arterial rings by measuring [3H]-thymidine incorporation and by cell counting. Cell cycle phase distribution was determined by flow cytometry and polyamines by HPLC. Protein expression was determined by Western blotting. The ODC inhibitor DFMO (1-10 mM) reduced polyamine concentration and attenuated proliferation in A7r5 cells and rat tail artery. DFMO accumulated cells in S phase of the cell cycle and reduced cyclin A expression. DFMO had no effect on cell viability and apoptosis as assessed by fluorescence microscopy. Polyamine concentration and cellular proliferation were not affected by the arginase inhibitor NOHA (100-200 microM) and the NO synthase inhibitor L-NAME (100 microM). Lack of effect of NOHA was reflected by absence of arginase expression. Polyamine synthesis inhibition attenuates vascular smooth muscle cell proliferation by reducing DNA synthesis and accumulation of cells in S phase, and may be a useful approach to prevent vascular smooth muscle cell proliferation in cardiovascular diseases.

High glucose-induced NF-kappaB activation occurs via tyrosine phosphorylation of IkappaBalpha in human glomerular endothelial cells: involvement of Syk tyrosine kinase

Activation of nuclear factor-kappaB (NF-kappaB) occurs by dissociation from IkappaB after serine or tyrosine phosphorylation of IkappaBalpha, but the way of NF-kappaB activation by high glucose has not been defined. High glucose is known to activate NF-kappaB via protein kinase C and reactive oxygen species (ROS). In this study, we investigated how high glucose activates NF-kappaB for CC chemokine ligand 2 production in cultured human glomerular endothelial cells. High glucose increased nuclear translocation of p65 and also increased NF-kappaB DNA binding activity. High glucose-induced NF-kappaB activation occurred without degradation of IkappaBalpha. In agreement with this, there was no increase in serine phosphorylation of IkappaBalpha, while tyrosine phosphorylation of IkappaBalpha was increased by high glucose. High glucose increased the generation of ROS, whereas both alpha-lipoic acid and N-acetylcysteine scavenged the ROS and decreased high glucose-induced tyrosine phosphorylation of IkappaBalpha, nuclear translocation of p65, and NF-kappaB DNA binding activity. Protein kinase C pseudosubstrate inhibited high glucose-induced ROS production, tyrosine phosphorylation of IkappaBalpha, and nuclear translocation of p65. Both BAY 61-3606, a specific inhibitor of Syk protein-tyrosine kinase, and small interfering RNA directed against Syk inhibited high glucose-induced tyrosine phosphorylation of IkappaBalpha as well as p65 nuclear translocation. High glucose increased tyrosine phosphorylation of Syk, while it was inhibited by alpha-lipoic acid and protein kinase C pseudosubstrate. In summary, high glucose-induced NF-kappaB activation occurred not by serine phosphorylation of IkappaBalpha. Our data suggest that ROS-mediated tyrosine phosphorylation of IkappaBalpha is the mechanism for high glucose-induced NF-kappaB activation, and Syk may play a role in tyrosine phosphorylation of IkappaBalpha.

Lipoic acid supplementation and endothelial function

Endothelial dysfunction is caused by all the recognized cardiovascular risk factors and has been implicated in the complex processes leading to the initiation and progression of atherosclerosis. Short-term treatment with lipoic acid is shown in the current issue of the British Journal of Pharmacology to improve endothelial function of aortic rings of old rats. The age-related decrease in phosphorylation of nitric oxide synthase and Akt was improved by lipoic acid supplementation. The improved phosphorylation status may have been due to reduced activity of the phosphatase PPA2, associated with decreased levels of endothelial ceramide induced by lipoic acid. Neutral sphingomyelinase activity was also reduced by lipoic acid, which was due, at least in part, to increased glutathione levels in endothelial cells. The favourable antioxidant, anti-inflammatory, metabolic and endothelial effects of lipoic acid shown in rodents, in this and other recently published studies, warrant further assessment of its potential role for prevention and treatment of cardiovascular diseases.

Ursolic acid: an anti- and pro-inflammatory triterpenoid

There is growing interest in the elucidation of the biological functions of triterpenoids, ubiquitously distributed throughout the plant kingdom, some of which are used as anticancer and anti-inflammatory agents in Asian countries. Ursolic acid (UA), a natural pentacyclic triterpenoid carboxylic acid, is the major component of some traditional medicine herbs and is well known to possess a wide range of biological functions, such as antioxidative, anti-inflammation, and anticancer activities, that are able to counteract endogenous and exogenous biological stimuli. In contrast to these beneficial properties, some laboratory studies have recently revealed that the effects of UA on normal cells and tissues are occasionally pro-inflammatory. Thus, UA may be designated as a double-edged sword with both positive and negative effects, and further evaluations of the effects of UA on the biological status of target cells or tissues are necessary. This review summarizes previous and current information regarding UA, and provides new insights into the underlying molecular mechanisms of its activities.

Dietary alpha-lipoic acid supplementation inhibits atherosclerotic lesion development in apolipoprotein E-deficient and apolipoprotein E/low-density lipoprotein receptor-deficient mice

BACKGROUND

Vascular inflammation and lipid deposition are prominent features of atherosclerotic lesion formation. We have shown previously that the dithiol compound alpha-lipoic acid (LA) exerts antiinflammatory effects by inhibiting tumor necrosis factor-alpha- and lipopolysaccharide-induced endothelial and monocyte activation in vitro and lipopolysaccharide-induced acute inflammatory responses in vivo. Here, we investigated whether LA inhibits atherosclerosis in apolipoprotein E-deficient (apoE-/-) and apoE/low-density lipoprotein receptor-deficient mice, 2 well-established animal models of human atherosclerosis.

METHODS AND RESULTS

Four-week-old female apoE-/- mice (n=20 per group) or apoE/low-density lipoprotein receptor-deficient mice (n=21 per group) were fed for 10 weeks a Western-type chow diet containing 15% fat and 0.125% cholesterol without or with 0.2% (wt/wt) R,S-LA or a normal chow diet containing 4% fat without or with 0.2% (wt/wt) R-LA, respectively. Supplementation with LA significantly reduced atherosclerotic lesion formation in the aortic sinus of both mouse models by approximately 20% and in the aortic arch and thoracic aorta of apoE-/- and apoE/low-density lipoprotein receptor-deficient mice by approximately 55% and 40%, respectively. This strong antiatherogenic effect of LA was associated with almost 40% less body weight gain and lower serum and very low-density lipoprotein levels of triglycerides but not cholesterol. In addition, LA supplementation reduced aortic expression of adhesion molecules and proinflammatory cytokines and aortic macrophage accumulation. These antiinflammatory effects of LA were more pronounced in the aortic arch and the thoracic aorta than in the aortic sinus, reflecting the corresponding reductions in atherosclerosis.

CONCLUSIONS

Our study shows that dietary LA supplementation inhibits atherosclerotic lesion formation in 2 mouse models of human atherosclerosis, an inhibition that appears to be due to the "antiobesity," antihypertriglyceridemic, and antiinflammatory effects of LA. LA may be a useful adjunct in the prevention and treatment of atherosclerotic vascular diseases.

Alpha-lipoic acid modulates gut inflammation induced by trinitrobenzene sulfonic acid in rats

BACKGROUND AND AIM

Alpha-lipoic acid (ALA) has been shown to combat oxidative stress by quenching a variety of reactive oxygen species. It is involved in the regeneration of exogenous and endogenous antioxidants, chelation of metal ions, and repair of oxidized proteins. This study aimed to evaluate the potential beneficial effect of ALA on trinitrobenzenesulfonic acid (TNBS)-induced gut ileitis and colitis in rats.

METHOD

After 48 h of fasting, Sprague-Dawley rats underwent a laparotomy under ether anesthesia. TNBS solution 30 mg/mL in 40% ethanol (1 mL) was injected into the lumen, 10 cm proximal to the ileocolonic junction to induce ileitis or intrarectally 8 cm proximal to the anal sphincter to induce colitis. ALA (25 mg/kg intraperitoneally, twice a day) was given after induction of inflammation and continued for 3 days. All animals were decapitated 3 days after induction of the inflammation. The mucosal lesions of the ileum and colon were scored macroscopically and microscopically. Samples were taken for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels, tissue-associated myeloperoxidase (MPO) activity and luminol- or lucigenin-enhanced chemiluminescence (CL).

RESULTS

Macroscopic scores, morphological changes and increased tissue lipid peroxidation with a concomitant reduction in GSH of the ileitis or colitis groups were all reversed by treatment with ALA. ALA treatment was also effective in improving tissue MPO activity and CL values, which were elevated in untreated ileitis or colitis groups.

CONCLUSION

ALA is beneficial in TNBS-induced gut inflammation in rats via suppression of neutrophil accumulation, preservation of endogenous glutathione and inhibition of reactive oxidant generation.

CB2-receptor stimulation attenuates TNF-alpha-induced human endothelial cell activation, transendothelial migration of monocytes, and monocyte-endothelial adhesion

Targeting cannabinoid-2 (CB(2)) receptors with selective agonists may represent a novel therapeutic avenue in various inflammatory diseases, but the mechanisms by which CB(2) activation exerts its anti-inflammatory effects and the cellular targets are elusive. Here, we investigated the effects of CB(2)-receptor activation on TNF-alpha-induced signal transduction in human coronary artery endothelial cells in vitro and on endotoxin-induced vascular inflammatory response in vivo. TNF-alpha induced NF-kappaB and RhoA activation and upregulation of adhesion molecules ICAM-1 and VCAM-1, increased expression of monocyte chemoattractant protein, enhanced transendothelial migration of monocytes, and augmented monocyte-endothelial adhesion. Remarkably, all of the above-mentioned effects of TNF-alpha were attenuated by CB(2) agonists. CB(2) agonists also decreased the TNF-alpha- and/or endotoxin-induced ICAM-1 and VCAM-1 expression in isolated aortas and the adhesion of monocytes to aortic vascular endothelium. CB(1) and CB(2) receptors were detectable in human coronary artery endothelial cells by Western blotting, RT-PCR, real-time PCR, and immunofluorescence staining. Because the above-mentioned TNF-alpha-induced phenotypic changes are critical in the initiation and progression of atherosclerosis and restenosis, our findings suggest that targeting CB(2) receptors on endothelial cells may offer a novel approach in the treatment of these pathologies.

R-(+)-alpha-lipoic acid inhibits endothelial cell apoptosis and proliferation: involvement of Akt and retinoblastoma protein/E2F-1

Lipoic acid was recently demonstrated to improve endothelial dysfunction or retinopathy not only in rats but also in diabetic patients. We tested the hypothesis that R-(+)-alpha-lipoic acid (LA) directly affects human endothelial cell (EC) function (e.g., apoptosis, proliferation, and protein expression), independent of the cells' vascular origin. Macrovascular EC (macEC), isolated from umbilical (HUVEC) and adult saphenous veins and from aortae, as well as microvascular EC (micEC) from retinae, skin, and uterus, were exposed to LA (1 mumol/l-1 mmol/l) with/without different stimuli (high glucose, TNF-alpha, VEGF, wortmannin, LY-294002). Apoptosis, proliferation, cell cycle distribution, and protein expression were determined by DNA fragmentation assays, [(3)H]thymidine incorporation, FACS, and Western blot analyses, respectively. In macro- and microvascular EC, LA (1 mmol/l) reduced (P < 0.05) basal (macEC, -36 +/- 4%; micEC, -46 +/- 6%) and stimulus-induced (TNF-alpha: macEC, -75 +/- 11%; micEC, -68 +/- 13%) apoptosis. In HUVEC, inhibition of apoptosis by LA (500 mumol/l) was paralleled by reduction of NF-kappaB. LA's antiapoptotic activity was reduced by PI 3-kinase inhibitors (wortmannin, LY-294002), being in line with LA-induced Akt phosphorylation (Ser(437), +159 +/- 43%; Thr(308), +98 +/- 25%; P < 0.01). LA (500 mumol/l) inhibited (P < 0.001) proliferation of macEC (-29 +/- 3%) and micEC (-29 +/- 3%) by arresting the cells at the G(1)/S transition due to an increased ratio of cyclin E/p27(Kip) (4.2-fold), upregulation of p21(WAF-1/Cip1) (+104 +/- 21%), and reduction of cyclin A (-32 +/- 11%), of hyperphosphorylated retinoblastoma protein (macEC: -51 +/- 7%; micEC: -50 +/- 15%), and of E2F-1 (macEC: -48 +/- 3%; micEC: -31 +/- 10%). LA's ability to inhibit apoptosis and proliferation of ECs could beneficially affect endothelial dysfunction, which precedes manifestation of late diabetic vascular complications.

Arginase: a critical regulator of nitric oxide synthesis and vascular function

1. Arginase is the focal enzyme of the urea cycle hydrolysing L-arginine to urea and L-ornithine. Emerging studies have identified arginase in the vasculature and have implicated this enzyme in the regulation of nitric oxide (NO) synthesis and the development of vascular disease. 2. Arginase inhibits the production of NO via several potential mechanisms, including competition with NO synthase (NOS) for the substrate L-arginine, uncoupling of NOS resulting in the generation of the NO scavenger, superoxide and peroxynitrite, repression of the translation and stability of inducible NOS protein, inhibition of inducible NOS activity via the generation of urea and by sensitization of NOS to its endogenous inhibitor asymmetric dimethyl-L-arginine. 3. Upregulation of arginase inhibits endothelial NOS-mediated NO synthesis and may contribute to endothelial dysfunction in hypertension, ageing, ischaemia-reperfusion and diabetes. 4. Arginase also redirects the metabolism of L-arginine to L-ornithine and the formation of polyamines and L-proline, which are essential for smooth muscle cell growth and collagen synthesis. Therefore, the induction of arginase may also promote aberrant vessel wall remodelling and neointima formation. 5. Arginase represents a promising novel therapeutic target that may reverse endothelial and smooth muscle cell dysfunction and prevent vascular disease.

The interplay between uric acid and antioxidants in relation to physical function in older persons

OBJECTIVES

To investigate the relationship between circulating uric acid (UA) levels and plasma antioxidants and whether antioxidant levels modulate the association between UA and physical function.

DESIGN

Cross-sectional.

SETTING

Community-based.

PARTICIPANTS

Nine hundred sixty-six elderly persons participating in the baseline assessment of the Invecchiare in Chianti Study.

MEASUREMENTS

UA, carotenoid, tocopherol, and selenium concentrations were assayed. Physical function was measured using the Short Physical Performance Battery (SPPB) and difficulties in instrumental activities of daily living (IADLs). Potential confounders were assessed using standardized methods.

RESULTS

Total carotenoids (P=.008), in particular alpha-carotene (P=.02), lutein (P<.001), zeaxanthin (P<.001), lycopene (P=.07), cryptoxanthin (P=.29), and selenium (P=.04) were inversely associated with UA levels. Total tocopherols (P=.06) and alpha-tocopherol (P=.10) had a positive trend across UA levels. SPPB (P=.01) and IADL disability (P=.002) were nonlinearly distributed across the UA quintiles. Participants within the middle UA quintile (4.8-5.3 mg/dL) were less disabled in IADLs and had better SPPB scores than those in the extreme UA quintiles. There was a significant interaction between UA and selenium in the model predicting SPPB score (P=.02).

CONCLUSION

UA levels are inversely associated with circulating carotenoids and selenium. Participants with intermediate UA levels had a higher prevalence of good physical functions, higher SPPB scores, and lower IADL disability. This study suggests that older subjects with intermediate UA levels may have an optimum balance between proinflammatory and antioxidant compounds that may contribute to better physical performance.

Roles of attenuated neuronal nitric-oxide synthase protein expression and accelerated arginase activity in impairing neurogenic relaxation of corpus cavernosum in aged rabbits

OBJECTIVE

To investigate whether changes in neuronal nitric oxide synthase (nNOS) protein expression and arginase activity are implicated in impairing the neurogenic cavernosal relaxation in aged rabbits, as NO is important in the neurogenic relaxation of corpus cavernosum during the erectile state.

MATERIALS AND METHODS

Cavernosal specimens of young adult (3-6 months old) and aged (36-48 months old) rabbits were used for isometric tension experiments, Western blot analysis, cGMP determination and measurements of NOS and arginase activities.

RESULTS

The neurogenic relaxation and cGMP production in response to electrical-field stimulation were significantly impaired in aged cavernosal specimens. Western blot analysis showed that nNOS protein was highly expressed in cavernosal specimens from young rabbits, but was undetectable or greatly decreased in old rabbits, with no change in overall NOS activity. Arginase activity in aged cavernosal specimens was significantly higher than in young rabbits. Supplementing with excess l-arginine, or giving S-(2-boronoethyl)-l-cysteine as an arginase inhibitor, significantly increased the neurogenic relaxation at lower frequencies only in the younger rabbits.

CONCLUSION

These results suggest that impairment of neurogenic and NO-mediated relaxation in the aged corpus cavernosum possibly results from the down-regulation of nNOS protein. The reduced l-arginine bioavailability to nNOS due to accelerated arginase activity would lead to further impairment of neurogenic NO production, in concert with decreased nNOS protein expression.

Effects of PGC-1alpha on TNF-alpha-induced MCP-1 and VCAM-1 expression and NF-kappaB activation in human aortic smooth muscle and endothelial cells

Increased oxidative stress in vascular cells is implicated in the pathogenesis of atherosclerosis. Reactive oxygen species (ROS) induce vascular inflammation via the proinflammatory cytokine/NF-kappaB pathway. Several lines of evidence suggest that peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1alpha) is an important regulator of intracellular ROS levels. However, no studies have examined the effects of PGC-1alpha on this process. We investigated the effects of PGC-1alpha on inflammatory molecule expression and activity of the redox-sensitive transcription factor, NF-kappaB, in vascular cells. PGC-1alpha expressed in human aortic smooth (HASMCs) and endothelial cells (HAECs) is upregulated by AMP-activated protein kinase activators, including metformin, rosiglitazone and alpha-lipoic acid. Tumor necrosis factor-alpha (TNF-alpha), a major proinflammatory factor in the development of vascular inflammation, stimulates intracellular ROS production through an increase in both mitochondrial ROS and NAD(P)H oxidase activity. Adenovirus-mediated overexpression of the PGC-1alpha gene in HASMCs and HAECs leads to a significant reduction in intracellular and mitochondrial ROS production as well as NAD(P)H oxidase activity. Consequently, NF-kappaB activity and MCP-1 and VCAM-1 induced by TNF-alpha are suppressed. Our data support the possibility that agents stimulating PGC-1alpha expression in the vasculature aid in preventing the development of atherosclerosis.

Alpha-lipoic acid attenuates LPS-induced inflammatory responses by activating the phosphoinositide 3-kinase/Akt signaling pathway

The phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway was recently shown to negatively regulate LPS-induced acute inflammatory responses. We previously observed that the metabolic thiol antioxidant alpha-lipoic acid (LA) inhibits LPS-induced expression of cellular adhesion molecules and adherence of monocytes to human aortic endothelial cells. Here we investigated the mechanism by which LA attenuates LPS-induced monocyte activation in vitro and acute inflammatory responses in vivo. Incubation of human monocytic THP-1 cells with LA induced phosphorylation of Akt in a time- and dose-dependent manner. In cells pretreated with LA followed by LPS, Akt phosphorylation was elevated initially and further increased during incubation with LPS. This LA-dependent increase in Akt phosphorylation was accompanied by inhibition of LPS-induced NF-kappaB DNA binding activity and up-regulation of TNFalpha and monocyte chemoattractant protein 1. Lipoic acid-dependent Akt phosphorylation and inhibition of NF-kappaB activity were abolished by the PI3K inhibitors LY294002 and wortmannin. Furthermore, LA treatment of LPS-exposed C57BL/6N mice strongly enhanced phosphorylation of Akt and glycogen synthase kinase 3beta in blood cells; inhibited the LPS-induced increase in serum concentrations and/or tissue expression of adhesion molecules, monocyte chemoattractant protein 1, and TNFalpha; and attenuated NF-kappaB activation in lung, heart, and aorta. Lipoic acid also improved survival of endotoxemic mice. All of these antiinflammatory effects of LA were abolished by treatment of the animals with wortmannin. We conclude that LA inhibits LPS-induced monocyte activation and acute inflammatory responses in vitro and in vivo by activating the PI3K/Akt pathway. Lipoic acid may be useful in the prevention of sepsis and inflammatory vascular diseases.

Decrease in lung nitric oxide production after peritonitis in mice with sickle cell disease*

OBJECTIVE

Nitric oxide bioavailability may limit the occurrence or severity of acute vaso-occlusive episodes in patients with sickle cell disease. Because sepsis is frequently involved in the initiation of vaso-occlusive crisis and acute chest syndrome, we designed the present study in transgenic (SAD) sickle cell mice to investigate whether acute infectious peritonitis affects the enzymatic balance (nitric oxide synthases/arginases) that governs lung nitric oxide production.

DESIGN

Controlled animal study.

SETTING

Research laboratory of an academic institution.

SUBJECTS

Transgenic Hbbsingle/single SAD1 (SAD) mice and nontransgenic wild-type littermates (C57/Black mice, control group).

INTERVENTIONS

Cecal ligation and puncture-induced peritonitis.

MEASUREMENTS AND MAIN RESULTS

We found that 24 hrs after peritonitis, control littermate mice showed an increase in inducible and endothelial nitric oxide synthase messenger RNA and proteins, together with an increase in exhaled nitric oxide (shift of the balance toward nitric oxide synthesis). In contrast, SAD mice, which showed elevated inducible and endothelial nitric oxide synthase protein expression at baseline, showed a marked decrease in nitric oxide synthase proteins, lung nitric oxide end-products, and exhaled nitric oxide after peritonitis, reflecting a shift of the enzymatic balance toward inhibition of nitric oxide synthesis. Peritonitis increased messenger RNA levels of arginase I and arginase II in controls and SAD mice but with a greater increase in arginase I in SAD than in control mice. Peritonitis was associated with a higher mortality rate at 24 hrs in SAD mice. Inhalation of nitric oxide (40 ppm in air) abolished the mortality rate induced by acute peritonitis in SAD mice.

CONCLUSIONS

Acute peritonitis in SAD mice is associated with a defect in lung nitric oxide production and bioavailability that may participate in the acute systemic and lung vaso-occlusive complications of sickle cell disease.

Janus-faced role of endothelial NO synthase in vascular disease: uncoupling of oxygen reduction from NO synthesis and its pharmacological reversal

Endothelial NO synthase (eNOS) is the predominant enzyme responsible for vascular NO synthesis. A functional eNOS transfers electrons from NADPH to its heme center, where L-arginine is oxidized to L-citrulline and NO. Common conditions predisposing to atherosclerosis, such as hypertension, hypercholesterolemia, diabetes mellitus and smoking, are associated with enhanced production of reactive oxygen species (ROS) and reduced amounts of bioactive NO in the vessel wall. NADPH oxidases represent major sources of ROS in cardiovascular pathophysiology. NADPH oxidase-derived superoxide avidly interacts with eNOS-derived NO to form peroxynitrite (ONOO(-)), which oxidizes the essential NOS cofactor (6R-)5,6,7,8-tetrahydrobiopterin (BH(4)). As a consequence, oxygen reduction uncouples from NO synthesis, thereby rendering NOS to a superoxide-producing pro-atherosclerotic enzyme. Supplementation with BH(4) corrects eNOS dysfunction in several animal models and in patients. Administration of high local doses of the antioxidant L-ascorbic acid (vitamin C) improves endothelial function, whereas large-scale clinical trials do not support a strong role for oral vitamin C and/or E in reducing cardiovascular disease. Statins, angiotensin-converting enzyme inhibitors and AT1 receptor blockers have the potential of reducing vascular oxidative stress. Finally, novel approaches are being tested to block pathways leading to oxidative stress (e.g. protein kinase C) or to upregulate antioxidant enzymes.

γ-Tocotrienol Inhibits Nuclear Factor-κB Signaling Pathway through Inhibition of Receptor-interacting Protein and TAK1 Leading to Suppression of Antiapoptotic Gene Products and Potentiation of Apoptosis

Unlike the tocopherols, the tocotrienols, also members of the vitamin E family, have an unsaturated isoprenoid side chain. In contrast to extensive studies on tocopherol, very little is known about tocotrienol. Because the nuclear factor-kappaB (NF-kappaB) pathway has a central role in tumorigenesis, we investigated the effect of gamma-tocotrienol on the NF-kappaB pathway. Although gamma-tocotrienol completely abolished tumor necrosis factor alpha (TNF)-induced NF-kappaB activation, a similar dose of gamma-tocopherol had no effect. Besides TNF, gamma-tocotrienol also abolished NF-kappaB activation induced by phorbol myristate acetate, okadaic acid, lipopolysaccharide, cigarette smoke, interleukin-1beta, and epidermal growth factor. Constitutive NF-kappaB activation expressed by certain tumor cells was also abrogated by gamma-tocotrienol. Reducing agent had no effect on the gamma-tocotrienol-induced down-regulation of NF-kappaB. Mevalonate reversed the NF-kappaB inhibitory effect of gamma-tocotrienol, indicating the role of hydroxymethylglutaryl-CoA reductase. Gamma-tocotrienol blocked TNF-induced phosphorylation and degradation of IkappaBalpha through the inhibition of IkappaBalpha kinase activation, thus leading to the suppression of the phosphorylation and nuclear translocation of p65. gamma-Tocotrienol also suppressed NF-kappaB-dependent reporter gene transcription induced by TNF, TNFR1, TRADD, TRAF2, TAK1, receptor-interacting protein, NIK, and IkappaBalpha kinase but not that activated by p65. Additionally, the expressions of NF-kappaB-regulated gene products associated with antiapoptosis (IAP1, IAP2, Bcl-xL, Bcl-2, cFLIP, XIAP, Bfl-1/A1, TRAF1, and Survivin), proliferation (cyclin D1, COX2, and c-Myc), invasion (MMP-9 and ICAM-1), and angiogenesis (vascular endothelial growth factor) were down-regulated by gamma-tocotrienol. This correlated with potentiation of apoptosis induced by TNF, paclitaxel, and doxorubicin. Overall, our results demonstrate that gamma-tocotrienol inhibited the NF-kappaB activation pathway, leading to down-regulation of various gene products and potentiation of apoptosis.

Cardiovascular proteomics: past, present, and future

With cardiovascular (CV)-related disorders accounting for the highest mortality rates in the world, affecting the quantity and quality of life of patients and creating an economic burden of prolonged therapeutic intervention, there is great significance in understanding the cellular and molecular alterations that influence the progression of these pathologies. The cellular genotype is regulated by the DNA component, whilst the cellular phenotype is influenced by the protein complement. By improving the understanding of the molecular mechanisms that influence the protein profile, the pathologies that influence the intrinsic functions of the CV system may be detected earlier or managed more efficiently. This is achievable with technologies encompassed by 'proteomics.' Proteomic investigations of CV diseases, including dilated cardiomyopathy (DCM), atherosclerosis, and ischemia/reperfusion (I/R) injury, have identified candidate proteins altered with the pathologic states, complementing past biochemical and physiologic observations. Whilst proteomics is still a relatively new discipline to be applied to the basic scientific investigation of CV diseases, it is emerging as a technique to screen for potential biomarkers in both tissues/cells and biologic fluids (biofluids), as well as to identify the targets of existing therapeutics. By enabling the separation of complex mixtures over numerous dimensions, exploiting the intrinsic properties of proteins, including charge state, molecular mass, and hydrophobicity, in addition to cellular location, the discrete alterations within the cell may be resolved. Proteomics has shown alterations to myofilament proteins including troponin I and myosin light chain, correlating with the reduction in contractility in the myocardium from DCM and I/R. The diverse cell types that coalesce to induce atherosclerotic plaque formation have been investigated both collectively and individually to elucidate the influence of the modifications to single cell types on the developing plaque as a whole. Proteomics has also been used to observe changes to biofluids occurring with these pathologies, a new potential link between basic science and clinical applications. The development of CV proteomics has helped to identify a number of possible protein candidates, and offers the potential to treat and diagnose CV disease more effectively in the future.

Preadministration of high-dose salicylates, suppressors of NF-kappaB activation, may increase the chemosensitivity of many cancers: an example of proapoptotic signal modulation therapy

NF-kappaB activity is elevated in a high proportion of cancers, particularly advanced cancers that have been treated previously. Cytotoxic treatment selects for such up-regulation inasmuch as NF-kappaB promotes transcription of a large number of proteins that inhibit both the intrinsic and extrinsic pathways of apoptosis; NF-kappaB also boosts expression of mdr1, which expels many drugs from cells. Indeed, high NF-kappaB activity appears to be largely responsible for the chemo- and radioresistance of many cancers. Thus, agents that suppress NF-kappaB activity should be useful as adjuvants to cytotoxic cancer therapy. Of the compounds that are known to be NF-kappaB antagonists, the most practical for current use may be the nonsteroidal anti-inflammatory drugs aspirin, salicylic acid, and sulindac, each of which binds to and inhibits Ikappa kinase- beta, a central mediator of NF-kappa activation; the low millimolar plasma concentrations of salicylate required for effective inhibition of this kinase in vivo can be achieved with high-dose regimens traditionally used to manage rheumatic disorders. The gastrointestinal toxicity of such regimens could be minimized by using salsalate or enteric-coated sodium salicy-late or by administering misoprostol in conjunction with aspirin therapy. Presumably, best results would be seen if these agents were administered for several days prior to a course of chemo- or radiotherapy, continuing throughout the course. This concept should first be tested in nude mice bearing xenografts of chemoresistant human tumors known to have elevated NF-kappa activity. Ultimately, more complex adjuvant regimens can be envisioned in which salicylates are used in conjunction with other NF-kappa antagonists and/or agents that target other mediators of down-regulated apoptosis in cancer, such as Stat3; coadministration of salicylate and organic selenium may have intriguing potential in this regard. These strategies may also have potential as adjuvants to metronomic chemotherapy, which seeks to suppress angio-genesis by targeting cycling endothelial cells in tumors.

Regulation of dendritic cell function and T cell priming by the fatty acid-binding protein AP2

The fatty acid-binding protein (FABP) family consists of a number of conserved cytoplasmic proteins with roles in intracellular lipid transport, storage, and metabolism. Examination of a comprehensive leukocyte gene expression database revealed strong expression of the adipocyte FABP aP2 in human monocyte-derived dendritic cells (DCs). We isolated bone marrow-derived DC from aP2-deficient mice, and showed that expression of DC cytokines including IL-12 and TNF was significantly impaired in these cells. Degradation of IkappaBalpha was also impaired in aP2-deficient DCs, indicative of reduced signaling through the IkappaB kinase-NF-kappaB pathway. The cytokine defect was selective because there was no effect on Ag uptake or expression of MHC class II, CD40, CD80, or CD86. In an MLR, aP2-deficient DCs stimulated markedly lower T cell proliferation and cytokine production than did wild-type DCs. Moreover, aP2-deficient mice immunized with keyhole limpet hemocyanin/CFA showed reduced production of IFN-gamma by restimulated draining lymph node cells, suggesting a similar defect in DC function in vivo. Similarly, infection of aP2-deficient mice with the natural mouse pathogen ectromelia virus resulted in substantially lower production of IFN-gamma by CD8+ T cells. Thus, FABP aP2 plays an important role in DC function and T cell priming, and provides an additional link between metabolic processes and the regulation of immune responses.

Alpha-lipoic acid inhibits fractalkine expression and prevents neointimal hyperplasia after balloon injury in rat carotid artery

Vascular inflammation induced by the proinflammatory cytokine/NF-kappaB pathway is one of the key mechanisms in the development of neointimal hyperplasia. Accumulating evidence suggests that a recently identified chemokine, fractalkine, is involved in arterial inflammation and atherogenesis. However, no study has examined the expression of neointimal fractalkine and the effects of pharmacological agents on this process. The purposes of this study were to measure neointimal fractalkine expression in the rat carotid artery following balloon injury and to determine if alpha-lipoic acid (ALA) inhibits fractalkine expression and neointimal hyperplasia. Balloon injury of the rat carotid artery induced fractalkine expression in the medial as well as neointimal regions. ALA inhibited this expression and consequently prevented neoinitmal hyperplasia in a balloon-injured rat carotid artery. Additionally, ALA inhibited TNF-alpha-stimulated fractalkine expression in cultured vascular smooth muscle cells (VSMCs), a process which is mediated through the NF-kappaB pathway. In addition to fractalkine, ALA successfully inhibited TNF-alpha-stimulated expression of vascular cell adhesion molecule-1 and monocyte chemotactic protein-1 in cultured VSMCs. These data suggest that the cytokine-fractalkine system is involved in the pathogenesis of restenosis. The present study supports the possibility that ALA, which inhibits the NF-kappaB/fractalkine pathway, may be used to prevent neointimal hyperplasia after angioplasty or stenting.

NF-kappaB regulation of endothelial cell function during LPS-induced toxemia and cancer

The transcription factor NF-kappaB is an important regulator of homeostatic growth and inflammation. Although gene-targeting studies have revealed important roles for NF-kappaB, they have been complicated by component redundancy and lethal phenotypes. To examine the role of NF-kappaB in endothelial tissues, Tie2 promoter/enhancer-IkappaBalpha(S32A/S36A) transgenic mice were generated. These mice grew normally but exhibited enhanced sensitivity to LPS-induced toxemia, notable for an increase in vascular permeability and apoptosis. Moreover, B16-BL6 tumors grew significantly more aggressively in transgenic mice, underscoring a new role for NF-kappaB in the homeostatic response to cancer. Tumor vasculature in transgenic mice was extensive and disorganized. This correlated with a marked loss in tight junction formation and suggests that NF-kappaB plays an important role in the maintenance of vascular integrity and response to stress.

Alpha-lipoic acid modulates ovarian surface epithelial cell growth

OBJECTIVE

The intracellular redox state plays an important role in controlling inflammation. Clinical and laboratory data suggest that inflammation can lead to tumor progression. We hypothesized that restoring intracellular redox control would inhibit inflammation and subsequently tumor progression. Our studies were designed to investigate the effect of alpha-lipoic acid (ALA), a naturally occurring antioxidant, on a key inflammatory signaling pathway and cell proliferation in normal and tumorigenic ovarian surface epithelial cells.

METHODS

Normal and tumorigenic ovarian surface epithelial cells were isolated as described by Roby and coworkers [Roby KF, Taylor CC, Sweetwood JP, Cheng Y, Pace JL, Tawpik O, Persons DL, Smith PG, Terranova PF, Development of a syngeneic mouse model for events related to ovarian cancer. Carcinogen 2000;21 (4):585. [1]]. The effect of ALA on cellular function was measured in cell proliferation and apoptosis assays. p27(kip1) protein levels were measured by Western analysis. Activation of NF-kappaB dependent transcription was assessed in cell cultures transiently transfected with NF-kappaB controlled reporter constructs.

RESULTS

Our results reveal that ALA selectively inhibits the growth of tumorigenic as compared to non-tumorigenic ovarian surface epithelial cells. The growth inhibitory effect of ALA is not due to induction of apoptosis but instead is associated with an increase in the half-life of the cyclin-dependent kinase inhibitor, p27(kip1). In parallel to the growth inhibitory effect, ALA also affects a key inflammatory signaling pathway by inhibiting TNFalpha-induced NF-kappaB signaling activity.

CONCLUSIONS

Our studies are the first to show that ALA treatment has a growth inhibitory effect on malignant surface epithelial cells of ovarian origin. We have also confirmed the reproducibility of the immunocompetent mouse ovarian cancer model originally described by Roby and coworkers [Roby KF, Taylor CC, Sweetwood JP, Cheng Y, Pace JL, Tawpik O, Persons DL, Smith PG, Terranova PF, Development of a syngeneic mouse model for events related to ovarian cancer. Carcinogen 2000;21 (4):585].

Short-term arginine deprivation results in large-scale modulation of hepatic gene expression in both normal and tumor cells: microarray bioinformatic analysis

Background

We have reported arginine-sensitive regulation of LAT1 amino acid transporter (SLC 7A5) in normal rodent hepatic cells with loss of arginine sensitivity and high level constitutive expression in tumor cells. We hypothesized that liver cell gene expression is highly sensitive to alterations in the amino acid microenvironment and that tumor cells may differ substantially in gene sets sensitive to amino acid availability. To assess the potential number and classes of hepatic genes sensitive to arginine availability at the RNA level and compare these between normal and tumor cells, we used an Affymetrix microarray approach, a paired in vitro model of normal rat hepatic cells and a tumorigenic derivative with triplicate independent replicates. Cells were exposed to arginine-deficient or control conditions for 18 hours in medium formulated to maintain differentiated function.

Results

Initial two-way analysis with a p-value of 0.05 identified 1419 genes in normal cells versus 2175 in tumor cells whose expression was altered in arginine-deficient conditions relative to controls, representing 9–14% of the rat genome. More stringent bioinformatic analysis with 9-way comparisons and a minimum of 2-fold variation narrowed this set to 56 arginine-responsive genes in normal liver cells and 162 in tumor cells. Approximately half the arginine-responsive genes in normal cells overlap with those in tumor cells. Of these, the majority was increased in expression and included multiple growth, survival, and stress-related genes. GADD45, TA1/LAT1, and caspases 11 and 12 were among this group. Previously known amino acid regulated genes were among the pool in both cell types. Available cDNA probes allowed independent validation of microarray data for multiple genes. Among genes downregulated under arginine-deficient conditions were multiple genes involved in cholesterol and fatty acid metabolism. Expression of low-density lipoprotein receptor was decreased in both normal and tumor cells.

Conclusion

Arginine-sensitive regulation appears to be an important homeostatic mechanism to coordinate cell response and nutrient availability in hepatic cells. Genes predicted as arginine-responsive in stringent microarray data analysis were confirmed by Northern blot and RT-PCR. Although the profile of arginine-responsive genes is altered and increased, a considerable portion of the "arginome" is maintained upon neoplastic transformation.

Hydrogen peroxide upregulates TNF-related apoptosis-inducing ligand (TRAIL) expression in human astroglial cells, and augments apoptosis of T cells

The brain is particularly vulnerable to oxygen free radicals, and these radicals have been implicated in the pathology of several neurological disorders. In this study, the modulation of TNF-related apoptosis-inducing ligand (TRAIL) expression by oxidative stress was shown in LN215 cells, an astroglioma cell line. Hydrogen peroxide (H2O2) treatment increased TRAIL expression in LN215 cells and H2O2-induced TRAIL augmented apoptosis in Peer cells, a cell line sensitive to TRAIL- mediated cell death. Our findings suggest that the upregulation of TRAIL in astroglial cells may abrogate immune cell effector functions.

3-Hydroxyanthranilic acid, one of l-tryptophan metabolites, inhibits monocyte chemoattractant protein-1 secretion and vascular cell adhesion molecule-1 expression via heme oxygenase-1 induction in human umbilical vein endothelial cells

Heme oxygenase (HO)-1 is important in the vascular system, and its genetic or pharmacological induction in endothelium would be effective for the prevention and treatment of atherosclerosis. The naturally occurring antioxidant 3-hydroxyanthranilic acid (HA), one of l-tryptophan metabolites formed in vivo along the metabolic route known as the kynurenine pathway during inflammation or infection, was found to induce HO-1 expression and to stimulate nuclear translocation of NF-E2 related factor 2 (Nrf2) in human umbilical vein endothelial cells (HUVECs). Pre-treatment with HA inhibited the secretion of monocyte chemoattractant protein (MCP)-1, the expression of vascular cell adhesion molecule (VCAM)-1 and the activation of transcriptional nuclear factor (NF)-kappaB in HUVECs stimulated with tumor necrosis factor-alpha, the major pro-inflammatory cytokine causing endothelial inflammation. Interestingly, the observed anti-inflammatory effects of HA were mimicked by a HO-1 inducer, cobalt protoporphyrin, and bilirubin, one of HO-1 enzymatic products, but abolished in the presence of a HO-1 inhibitor, tin protoporphyrin. Based on our findings, we suggest that Nrf2-dependent HO-1 expression induced by HA inhibits MCP-1 secretion, VCAM-1 expression and NF-kappaB activation associated with vascular injury and inflammation in atherosclerosis.

Dietary antioxidants in preventing atherogenesis

Several naturally occurring constituents have received considerable attention because of their potential antioxidant activity. Consuming a diet rich in natural antioxidants has been associated with prevention from and/or treatment of atherosclerosis. Bioactive components of food, which are of special interest, include the Vitamins E and C, polyphenols, carotenoids-mainly lycopene and beta-carotene, and coenzyme Q10, featured by antioxidant properties. Antioxidant therapy is supposed to be effective in the early stages of atherosclerosis by preventing LDL oxidation and the oxidative lesion of endothelium. This review focuses on the effect of dietary antioxidants pertained to LDL oxidation and to the vascular endothelial dysfunction. Now that the human genome has been completely sequenced, genetic factors involved in oxidation may open new horizons to identify persons at risk for cardiovascular disease, allowing effective dietary intervention strategies to recover normal homeostasis and to prevent diet-related implications. On this basis, current studies on the action of selected antioxidant nutraceuticals on the activity of transcription factors, such as final targets in the signal transduction cascade and gene regulation, may emerge into new treatment concepts.

The comparative physiology of food deprivation: from feast to famine

The ability of animals to survive food deprivation is clearly of considerable survival value. Unsurprisingly, therefore, all animals exhibit adaptive biochemical and physiological responses to the lack of food. Many animals inhabit environments in which food availability fluctuates or encounters with appropriate food items are rare and unpredictable; these species offer interesting opportunities to study physiological adaptations to fasting and starvation. When deprived of food, animals employ various behavioral, physiological, and structural responses to reduce metabolism, which prolongs the period in which energy reserves can cover metabolism. Such behavioral responses can include a reduction in spontaneous activity and a lowering in body temperature, although in later stages of food deprivation in which starvation commences, activity may increase as food-searching is activated. In most animals, the gastrointestinal tract undergoes marked atrophy when digestive processes are curtailed; this structural response and others seem particularly pronounced in species that normally feed at intermittent intervals. Such animals, however, must be able to restore digestive functions soon after feeding, and these transitions appear to occur at low metabolic costs.

Lipoic acid inhibits expression of ICAM-1 and VCAM-1 by CNS endothelial cells and T cell migration into the spinal cord in experimental autoimmune encephalomyelitis

Lipoic acid (LA) suppresses and treats murine experimental autoimmune encephalomyelitis (EAE), which models multiple sclerosis. However, the mechanisms by which LA mediates its effects in EAE are only partially known. In the present study, LA (25, 50 and 100 microg/ml) inhibited upregulation of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in tumor necrosis factor-alpha (TNF-alpha) stimulated cultured brain endothelial cells. Immunohistochemical analysis of spinal cords from SJL mice that had received LA (100 mg/kg/day) following immunization to induce EAE exhibited markedly reduced expression of ICAM-1 and VCAM-1 compared with that of EAE mice receiving saline. Co-localization analysis showed that ICAM-1 and VCAM-1 expression increased over endothelial cells (staining positive for von Willebrand factor, vWF) in EAE and that LA decreased the expression levels to that observed in naïve mice. Spinal cords from mice receiving LA had significantly reduced inflammation (decreased CD4 and CD11b staining) as compared to EAE mice that received saline. Overall, our data suggest that the anti-inflammatory effects of LA in EAE may be partly due to inhibition of ICAM-1 and VCAM-1 expression by central nervous system (CNS) endothelial cells.

Control of ErbB signaling through metalloprotease mediated ectodomain shedding of EGF-like factors

Epidermal growth factor (EGF)-like proteins comprise a group of structurally similar growth factors, which contain a conserved six-cysteine residue motif called the EGF-domain. EGF-like factors are synthesized as transmembrane precursors, which can undergo proteolytic cleavage at the cell surface to release a mature soluble ectodomain; a process often referred to as "ectodomain shedding". Ectodomain shedding of EGF-like factors has been linked to multiple zinc-binding metalloproteases of the matrix metalloprotease (MMP) and a disintegrin and metalloprotease (ADAM) families. Shedding can be activated by a variety of pharmacological and physiological stimuli and these activation events have been linked to the enhancement of metalloprotease activity, possibly via the action of intracellular signaling modules. Once shed from the cell surface, EGF-like factors bind to a family of four cell surface receptors named ErbB-1, -2, -3 and -4. Heterodimerization or homodimerization of these receptors following ligand binding drives intracellular signal transduction cascades, which eventuate in diverse cell fates including proliferation, differentiation, migration and inhibition of apoptosis. In addition to its role in driving normal developmental processes, a wealth of evidence now exists showing that de-regulated ErbB signaling is associated with the formation of tumors in a variety of tissues and that ectodomain shedding of EGF-like factors plays a critical event in this process. Thus, knowledge of the molecular mechanisms by which EGF-like factors are shed from the cell surface and the nature of the proteases and cellular signals that govern this process is crucial to understanding ErbB receptor signaling and potentially also in the development of novel cancer therapeutics targeting the ErbB pathway. This review focuses on the structure and function of EGF-like factors, and the mechanisms that govern the shedding of these transmembrane molecules from the cell surface.

Antiinflammatory effects of Tacrolimus in a mouse model of pleurisy

INTRODUCTION

Tacrolimus is an antibiotic macrolide with immunosuppressant properties isolated from Streptomyces tsukubaensis.

OBJECTIVES

This study evaluated whether the acute and systemic administration of Tacrolimus significantly interfered in leukocyte migration, exudation, myeloperoxidase and adenosine-deaminase and nitric oxide levels, as well as Interleukin-1 (IL-1beta) and tumor necrosis factor alpha (TNFalpha) levels in a mouse model of pleurisy in comparison to those obtained with dexamethasone.

MATERIALS AND METHODS

Pleurisy was induced by carrageenan (Cg, 1%), bradykinin (BK, 10 nmol), histamine (HIS, 1 micromol) or substance P (PS, 20 nmol) administered by intrapleural route (ipl.) and the inflammatory parameters (cell migration and exudation) were analyzed 4 h after. In the model of pleurisy induced by carrageenan, other markers in the pleural fluid, such as cytokines (TNFalpha and Il-1beta), nitrite/nitrate (NOx), myeloperoxidase (MPO) and adenosine-deaminase (ADA) levels, were also studied. Dexamethaseone (0.5 mg/kg, i.p., 0.5 h before) was also analyzed in all protocols.

RESULTS

In the pleurisy induced by carrageenan, Tacrolimus (1 mg/kg, i.p.) and dexamethasone (0.5 mg/kg, i.p.) administered 0.5 h before caused a significant decrease in leukocytes, neutrophils and exudation (P < 0.01). Under the same conditions, Tacrolimus and dexamethasone did not modify the blood's white or red cells (P > 0.05). Tacrolimus showed a long lasting antiinflammatory effect, inhibiting leukocytes and neutrophils for up to 24 h (P < 0.01), whereas the inhibition of exudation was less marked (up to 2 h) (P < 0.01). These drugs caused a marked reduction in MPO activity, as well as IL-1beta and TNFalpha levels (P < 0.01), but only Tacrolimus inhibited ADA activity (P < 0.01). On the other hand, dexamethasone, but not Tacrolimus, inhibited NOx levels (P < 0.01). In the same conditions, Tacrolimus significantly inhibited cell migration induced by either bradykinin, histamine or substance P (P < 0.05). In a similar manner, dexamethasone inhibited leukocyte influx induced by bradykinin and histamine (P < 0.05). Regarding exudation effects, dexamethasone markedly inhibited this parameter induced by BK, HIS or SP, whereas Tacrolimus only inhibited exudation caused by HIS (P < 0.05).

CONCLUSIONS

The results of the present work indicate that Tacrolimus showed important antiinflammatory properties against pleurisy in mice that are different from those caused by dexamethasone. The inhibition of proinflammatory cytokine (TNFalpha, IL-1beta), enzyme (myeloperoxidase, adenosine-deaminase) and mediator (bradykinin, histamine, substance P) release and/or action appears to account for Tacrolimus's actions.

alpha-Lipoic acid and N-acetyl cysteine prevent zinc deficiency-induced activation of NF-kappaB and AP-1 transcription factors in human neuroblastoma IMR-32 cells

This work investigated the capacity of alpha-lipoic acid (LA) and N-acetyl-L-cysteine (NAC) to reduce zinc deficiency-induced oxidative stress, and prevent the activation of nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1), and the cross-talk between both activated cascades through beta-Transducin Repeat-containing Protein (beta-TrCP). IMR-32 cells were incubated in control media or media containing variable concentrations of zinc, without or with 0.5 mM LA or 1 mM NAC. Relative to control and zinc supplemented (15 microM Zn) groups, Hydrogen peroxide (H(2)O(2)) and total oxidant cell concentrations were higher, and total glutathione concentrations were lower in the zinc deficient groups (1.5 and 5 microM Zn). Both, LA and NAC, markedly reduced the increase in cell oxidants and the reduction in glutathione concentrations in the zinc deficient cells. Consistent with this, LA and NAC prevented zinc deficiency-induced activation of the early steps of NF- kappaB (IkappaBalpha phosphorylation) and AP-1 [c-Jun-N-terminal kinase (JNK) and p38 phophorylation] cascades, and the high NF-kappaB- and AP-1-DNA binding activities in total cell extracts. Thus, LA and NAC can reduce the oxidative stress associated with zinc deficiency and the subsequent triggering of NF-kappaB- and AP-1-activation in neuronal cells.

Antioxidant alpha-lipoic acid inhibits osteoclast differentiation by reducing nuclear factor-kappaB DNA binding and prevents in vivo bone resorption induced by receptor activator of nuclear factor-kappaB ligand and tumor necrosis factor-alpha

The relationship between oxidative stress and bone mineral density or osteoporosis has recently been reported. As bone loss occurring in osteoporosis and inflammatory diseases is primarily due to increases in osteoclast number, reactive oxygen species (ROS) may be relevant to osteoclast differentiation, which requires receptor activator of nuclear factor-kappaB ligand (RANKL). Tumor necrosis factor-alpha (TNF-alpha) frequently present in inflammatory conditions has a profound synergy with RANKL in osteoclastogenesis. In this study, we investigated the effects of alpha-lipoic acid (alpha-LA), a strong antioxidant clinically used for some time, on osteoclast differentiation and bone resorption. At concentrations showing no growth inhibition, alpha-LA potently suppressed osteoclastogenesis from bone marrow-derived precursor cells driven either by a high-dose RANKL alone or by a low-dose RANKL plus TNF-alpha (RANKL/TNF-alpha). alpha-LA abolished ROS elevation by RANKL or RANKL/TNF-alpha and inhibited NF-kappaB activation in osteoclast precursor cells. Specifically, alpha-LA reduced DNA binding of NF-kappaB but did not inhibit IKK activation. Furthermore, alpha-LA greatly suppressed in vivo bone loss induced by RANKL or TNF-alpha in a calvarial remodeling model. Therefore, our data provide evidence that ROS plays an important role in osteoclast differentiation through NF-kappaB regulation and the antioxidant alpha-lipoic acid has a therapeutic potential for bone erosive diseases.

Amino acids, arginase and nitric oxide in vascular health

1. Nitric oxide (NO) plays a fundamental role in the vasculature because of its diverse influence in vascular protection, including its well-reported antiproliferative, anti-inflammatory, antithrombotic and vasodilator effects. In many vascular disease states, NO production is reduced as a result of endothelial dysfunction, in part caused by a decrease in substrate (L-arginine) availability. 2. The role of L-arginine and other amino acids important in nitrogen balance has been re-examined in the context of their effects on vascular health. The metabolism of L-arginine is complex because it is involved in a plethora of other pathways, such as urea, creatine and agmatine production. L-Arginine supplementation in patients with vascular disease is well reported to benefit patients therapeutically because of its effect on both NO-dependent and -independent mechanisms. 3. L-Arginine availability depends on the flux of other amino acids in the body, including L-glutamine, L-glutamate, L-ornithine, L-citrulline and L-lysine. The role of L-methionine and homocystine and their effect on NO also play an influential role in the body. 4. Recent data suggest that the key enzyme involved in the L-arginine-urea cycle, arginase, is coexpressed in NO-producing cells in the vasculature. In the present review, we examine the potential role of arginase as a therapeutic target for vascular health.

A novel mechanism of action of methyl-2-cyano-3,12 dioxoolean-1,9 diene-28-oate: direct permeabilization of the inner mitochondrial membrane to inhibit electron transport and induce apoptosis

Methyl-2-cyano-3,12 dioxoolean-1,9 diene-28-oate (CDDO-Me) is a synthetic oleanolic acid derivative that displays antitumorigenic and anti-inflammatory activities, and we have previously reported that this agent potently activates the intrinsic apoptotic pathway in leukemia cells. In this study, we demonstrate that mitochondrial dysfunction induced by CDDO-Me is mediated by direct permeabilization of the inner mitochondrial membrane, which results in the rapid depletion of mitochondrial glutathione (GSXm), loss of cardiolipin, and inhibition of mitochondrial respiration. More importantly, we demonstrate that in addition to activating the intrinsic apoptotic pathway, the mitochondrial effects of CDDO-Me may mediate its anti-inflammatory activity by modulating the generation of superoxide anion (O2*). It is noteworthy that CDDO-Me did not increase the generation of O2* and pretreatment of leukemia cells with CDDO-Me prevented the increase of this reactive oxygen species elicited by inhibition of complex I or III in the absence of de novo protein synthesis. CDDO-Me, but not other inhibitors of respiration, induced a time- and dose-dependent, cyclosporin A-independent permeability transition (PT) of isolated mitochondria that was sensitive to sulfhydryl antioxidants but not to EDTA. PT induced by CDDO-Me and Ca2+ was accompanied by loss of GSXm, suggesting that the increased permeability of the inner mitochondrial membrane facilitates the loss of this antioxidant. Finally, transmission electron microscopy revealed that CDDO-Me rapidly induced caspase-independent mitochondrial swelling and loss of inner membrane structure before the release of cytochrome c. Taken together, our results indicate that CDDO-Me is a novel mitochondriotoxic agent that induces apoptosis and inhibits mitochondrial electron transport via perturbations in inner mitochondrial membrane integrity.

Dimeric sesquiterpenoids isolated from Chloranthus japonicus inhibited the expression of cell adhesion molecules

In the search for cell adhesion inhibitors from natural sources, three active compounds were isolated from Chloranthus japonicus Sieb. (Chloranthaceae) roots. The compounds were identified as dimeric sesquiterpenoids of shizukaol B (1), cycloshizukaol A (2) and shizukaol F (3). These compounds inhibited PMA-induced homotypic aggregation of HL-60 cells without cytotoxicity with MIC values of 34.1 nM (1), 0.9 microM (2) and 27.3 nM (3), respectively. Although 1-3 did not affect the direct binding of LFA-1 to ICAM-1, these compounds markedly inhibited ICAM-1 expression in HL-60 cells in a dose-dependent fashion. On the other hand, when HUVEC were pretreated with 1-3 and stimulated with TNF-alpha, adhesion of THP-1 cells to HUVEC decreased in dose-dependent manner with IC(50) values of 54.6 nM, 1.2 microM and 34.1 nM, respectively. In fact, 1 inhibited TNF-alpha-induced surface expression of the ICAM-1, VCAM-1 and E-selectin in HUVEC with IC(50) values of 5.4 nM, 13.6 microM and 95.6 nM, respectively. The present findings suggest that 1-3 prevent monocyte adhesion to HUVEC through the inhibition of cell adhesion molecules expression stimulated by TNF-alpha.

Testicular Isoform of Angiotensin I-Converting Enzyme (ACE, CD143) on the Surface of Human Spermatozoa: Revelation and Quantification Using Monoclonal Antibodies

PROBLEM

The elucidation of the role of angiotensin-converting enzyme (ACE, CD143) in the male fertility has been hampered by the absence of highly specific antibodies to the native testicular isoform (tACE). The quantification of tACE expression on human-ejaculated spermatozoa was performed using a novel panel of monoclonal antibodies (mAbs).

METHOD OF STUDY

The expression of tACE on the surface of live and fixed human spermatozoa was analyzed by flow cytometry and immunocytochemistry using new mAbs to human tACE.

RESULTS

Monoclonal antibodies 1E10 and 4E3 similarly revealed tACE on the surface of live and fixed spermatozoa. The high percentage of tACE-positive spermatozoa (median 81%) was revealed in the swim-up fraction of sperm. Antibody-induced tACE shedding occurs preferentially from live sperm with defective function and/or morphology. Testicular ACE is located on the plasma membrane of the post-acrosomal region, the neck and midpiece of normal spermatozoa, but showed a variable distribution on the defective cells.

CONCLUSIONS

The new mAbs recognizing the C-terminal domain of human ACE are useful tools for quantification of tACE expression on human live and fixed spermatozoa and further adequate analysis of the tACE role in reproduction.

α-Lipoic Acid Inhibits Inflammatory Bone Resorption by Suppressing Prostaglandin E2 Synthesis

alpha-Lipoic acid (LA) has been intensely investigated as a therapeutic agent for several pathological conditions, including diabetic polyneuropathy. In the present study, we examined the effects of LA on osteoclastic bone loss associated with inflammation. LA significantly inhibited IL-1-induced osteoclast formation in cocultures of mouse osteoblasts and bone marrow cells, but LA had only a marginal effect on osteoclastogenesis from bone marrow macrophages induced by receptor activator of NF-kappaB ligand (RANKL). LA inhibited both the sustained up-regulation of RANKL expression and the production of PGE2 induced by IL-1 in osteoblasts. In addition, treatment with either prostaglandin E2 (PGE2) or RANKL rescued IL-1-induced osteoclast formation inhibited by LA or NS398, a specific cyclooxygenase-2 (COX-2) inhibitor, in cocultures. LA blocked IL-1-induced PGE2 production even in the presence of arachidonic acid, without affecting the expression of COX-2 and membrane-bound PGE2 synthase. Dihydrolipoic acid (the reduced form of LA), but not LA, attenuated recombinant COX-2 activity in vitro. LA also inhibited osteoclast formation and bone loss induced by IL-1 and LPS in mice. Our results suggest that the reduced form of LA inhibits COX-2 activity, PGE2 production, and sustained RANKL expression, thereby inhibiting osteoclast formation and bone loss in inflammatory conditions.

Lipoic acid decreases exhaled nitric oxide concentrations in anesthetized endotoxemic rats

We recently demonstrated that lipoic acid suppresses endotoxin-stimulated expression of inducible nitric oxide synthase and nitric oxide production in mouse macrophages. In this study, we tested whether lipoic acid suppresses these inflammatory mediators in the lungs of rats. Rats were assigned to receive either no special treatment, endotoxin alone, or pretreatment with lipoic acid followed by endotoxin. After anesthetizing the rats and injecting them intraperitoneally with lipoic acid (100 mg/kg) at 4 h and again at 1 h before treatment, the rats then received either endotoxin (0.01 mg/kg) or its vehicle solution. Exhaled gas was sampled every 15 min and concentrations of nitric oxide in the samples were measured using a chemiluminescence analyzer. After 150 min of exposure to endotoxin, the lungs were harvested and snap-frozen in liquid nitrogen for subsequent analysis. Lipoic acid attenuated endotoxin-induced increases in exhaled nitric oxide concentrations (P<0.001) and iNOS (P<0.05). These findings support the hypothesis that lipoic acid inhibits endotoxin-stimulated formation of intrapulmonary nitric oxide.

Induction of heat shock proteins may combat insulin resistance

The molecular mechanism responsible for obesity-associated insulin resistance has been partially clarified: increased fatty acid levels in muscle fibers promote diacylglycerol synthesis, which activates certain isoforms of protein kinase C (PKC). This in turn triggers a kinase cascade which activates both IkappaB kinase-beta (IKK-beta) and c-Jun N-terminal kinase (JNK), each of which can phosphorylate a key serine residue in IRS-1, rendering it a poor substrate for the activated insulin receptor. Heat shock proteins Hsp27 and Hsp72 have the potential to prevent the activation of IKK-beta and JNK, respectively; this suggests that induction of heat shock proteins may blunt the adverse impact of fat overexposure on insulin function. Indeed, bimoclomol--a heat shock protein co-inducer being developed for treatment of diabetic neuropathy--and lipoic acid--suspected to be a heat shock protein inducer--have each demonstrated favorable effects on the insulin sensitivity of obese rodents, and parenteral lipoic acid is reported to improve the insulin sensitivity of type 2 diabetics. Moreover, there is reason to believe that heat shock protein induction may have a favorable impact on the microvascular complications of diabetes, and on the increased risk for macrovascular disease associated with diabetes and insulin resistance syndrome. Heat shock protein induction may also have potential for preventing or treating neurodegenerative disorders, controlling inflammation, and possibly even slowing the aging process. The possible complementarity of bimoclomol and lipoic acid for heat shock protein induction should be assessed, and further efforts to identify well-tolerated agents active in this regard are warranted.

Pretreatment of diabetic rats with lipoic acid improves healing of subsequently-induced abrasion wounds

The etiology of delayed or impaired wound-healing in diabetic individuals is multifactoral, but peripheral vascular dysfunction is an underlying factor in the majority of cases. Recent studies have shown that lipoic acid improves vascular function in diabetic skin and reduces the symptoms associated with the diabetic peripheral neuropathy. In this study, rats were made diabetic with streptozotocin (STZ) and treated systemically on alternative days with lipoic acid (100 mg/kg given via intraperitoneal injection) for 8 weeks. Untreated STZ-diabetic rats and non-diabetic rats served as control. At the end of the 8-week period, rats from all the three groups were subjected to abrasion wound formation. Skin wounds healed more rapidly in untreated non-diabetic rats than in the untreated diabetic rats. Wounds in lipoic acid-treated diabetic rats healed more rapidly than wounds in untreated diabetic rats. Subsequent in vitro studies demonstrated that lipoic acid protected endothelial cells from oxidant injury. At the same time, lipoic acid had no apparent effect on endothelial cell proliferation and had no measurable effect on fibroblast function (proliferation, collagen synthesis and matrix metalloproteinase expression). These findings suggest that prophylactic use of lipoic acid might be useful in preventing the development of non-healing skin ulcers from minor traumas in at-risk skin.

The role of fatty acid binding proteins in metabolic syndrome and atherosclerosis

PURPOSE OF REVIEW

The global prevalence of obesity is increasing epidemically. Obesity causes an array of health problems, reduces life expectancy, and costs over US dollar 100 billion annually. More than a quarter of the population suffers from an aggregation of co-morbidities, including obesity, atherosclerosis, insulin resistance, dyslipidemias, coagulopathies, hypertension, and a pro-inflammatory state known as the metabolic syndrome. Patients with metabolic syndrome have high risk of atherosclerosis as well as type 2 diabetes and other health problems. Like obesity, atherosclerosis has very limited therapeutic options.

RECENT FINDINGS

Fatty acid binding proteins integrate metabolic and immune responses and link the inflammatory and lipid-mediated pathways that are critical in the metabolic syndrome. This review will highlight recent studies on fatty acid binding protein-deficient models and several fatty acid binding protein-mediated pathways specifically modified in macrophages, cells that are paramount to the initiation and persistence of cardiovascular lesions.

SUMMARY

Adipocyte/macrophage fatty acid binding proteins, aP2 and mal1, act at the interface of metabolic and inflammatory pathways. These fatty acid binding proteins are involved in the formation of atherosclerosis predominantly through the direct modification of macrophage cholesterol trafficking and inflammatory responses. In addition to atherosclerosis, these fatty acid binding proteins also exert a dramatic impact on obesity, insulin resistance, type 2 diabetes and fatty liver disease. The creation of pharmacological agents to modify fatty acid binding protein function will provide tissue or cell-type-specific control of these lipid signaling pathways, inflammatory responses, atherosclerosis, and the other components of the metabolic syndrome, therefore offering a new class of multi-indication therapeutic agents.

Redox-dependent protein kinase regulation by angiotensin II: mechanistic insights and its pathophysiology

Reactive oxygen species (ROS) are proposed to induce cardiovascular diseases, such as atherosclerosis, hypertension, restenosis, and fibrosis, through several mechanisms. One such mechanism involves ROS acting as intracellular second messengers, which lead to induction of unique signal transductions. Angiotensin II (AngII), a potent cardiovascular pathogen, stimulates ROS production through the G protein-coupled AngII type 1 receptor expressed in its target organs, such as vascular tissues, heart, and kidney. Recent accumulating evidence indicates that through ROS production, AngII activates downstream ROS-sensitive kinases that are critical in mediating cardiovascular remodeling. Each of these ROS-sensitive kinases could potentially mediate its own specific function. In this review, we will focus our discussion on the current findings that suggest novel mechanisms of how AngII mediates activation of these redox-sensitive kinases in target organs, as well as the pathological significance of their activation.

Alpha-lipoic acid-induced heme oxygenase-1 expression is mediated by nuclear factor erythroid 2-related factor 2 and p38 mitogen-activated protein kinase in human monocytic cells

OBJECTIVE

Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme catabolism, plays a protective role in the vascular system. HO-1 induction inhibits cytokine production in macrophages. Antioxidants induce HO-1 expression in various cell types. Alpha-lipoic acid (ALA), a thiol-containing dietary antioxidant, exhibits protective effects in vascular disease and induces anti-inflammatory effects in monocytes. This study examined the effects of ALA on HO-1 expression in human monocytic cells.

METHODS AND RESULTS

ALA time and dose-dependently induced HO-1 mRNA expression in THP-1 cells, with peak expression at 4 hours and returning to baseline by 24 hours. This correlated with an increase in HO-1 protein expression. ALA stimulated translocation of the transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2) into the nucleus and binding to a human HO-1 antioxidant response element (ARE) by 30 minutes. A dominant-negative Nrf2 inhibitor reduced ALA-induced HO-1 mRNA expression by 66%. Pretreatment with SB203580, a p38 mitogen-activated protein kinase inhibitor, reduced ALA-induced HO-1 mRNA expression by 75% and inhibited ALA-induced Nrf2 binding to the HO-1 ARE.

CONCLUSIONS

These results demonstrate that ALA induces HO-1 expression in THP-1 monocytic cells via Nrf2 and p38. Further studies are required to investigate whether the protective effects of ALA in monocytes are mediated by HO-1.

A manganese porphyrin suppresses oxidative stress and extends the life span of streptozotocin-diabetic rats

Enhanced oxidative stress due to hyperglycemia has been implicated in diabetic complications and is considered a major cause of cell and tissue damage. The aim of the present study was to investigate whether synthetic manganese porphyrin, Mn(III) 5,10,15,20-tetrakis(N-methylpyridinium-2-yl)porphyrin (MnTM-2-PyP5+) can ameliorate diabetes-induced oxidative stress and affect life span of diabetic rats. Diabetes was induced by a single (60 mg/kg) intraperitoneal injection of streptozotocin in male Wistar rats. Oxidative stress was monitored by measuring malondialdehyde levels (MDA) in blood plasma and erythrocytes using HPLC. The antioxidant status was assessed by measuring the total radical-trapping potential (TRAP) of blood plasma. Life span of the animals was used as an indication of the overall effect of MnTM-2-PyP5+. MnTM-2-PyP5+ was administered subcutaneously at 1 mg/kg for the duration of the experiment, five times/week followed by one week of rest. Diabetes increased plasma and erythrocyte levels of MDA and decreased TRAP. MnTM-2-PyP5+ had no effect on blood glucose and glycosylated hemoglobin, but significantly increased TRAP and lowered MDA. This Mn porphyrin decreased mortality and markedly extended the life span of the diabetic animals. MnTM-2-PyP5+ suppressed diabetes-induced oxidative stress, which presumably accounts for its beneficial effect on the life span of the diabetic rats. The results indicate that Mn(III) N-alkylpyridylporphyrins can be used as potent therapeutic agents in diabetes.

α-Lipoic acid supplementation inhibits oxidative damage, accelerating chronic wound healing in patients undergoing hyperbaric oxygen therapy

Hyperbaric oxygen (HBO) therapy is successfully used for the treatment of a variety of conditions. However, prolonged exposure to high concentrations of oxygen induces production of reactive oxygen species, causing damage to the cells. Thus, antioxidant supplementation has been proposed as an adjuvant to attenuate such deleterious secondary effects. We evaluated the effects of alpha-lipoic acid (LA) in patients affected by chronic wounds undergoing HBO treatment. LA supplementation efficiently reduces both the lipid and DNA oxidation induced by oxygen exposure. LA exerted its antioxidant activity by directly interacting with free radicals or by recycling vitamin E. An inhibitory effect of LA on the pro-inflammatory cytokine interleukin-6 was observed. Taken together, we demonstrated an adjuvant effect of LA in HBO therapy used for impaired wound healing treatment. We propose that LA may be used to further promote the beneficial effects of HBO therapy.

Lipoic acid in multiple sclerosis: a pilot study

Lipoic acid (LA) is an antioxidant that suppresses and treats an animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis. The purpose of this study was to determine the pharmacokinetics (PK), tolerability and effects on matrix metalloproteinase-9 (MMP-9) and soluble intercellular adhesion molecule-1 (sICAMP-1) of oral LA in patients with MS. Thirty-seven MS subjects were randomly assigned to one of four groups: placebo, LA 600 mg twice a day, LA 1200 mg once a day and LA 1200 mg twice a day. Subjects took study capsules for 14 days. We found that subjects taking 1200 mg LA had substantially higher peak serum LA levels than those taking 600 mg and that peak levels varied considerably among subjects. We also found a significant negative correlation between peak serum LA levels and mean changes in serum MMP-9 levels (T = -0.263, P =0.04). There was a significant dose response relationship between LA and mean change in serum sICAM-1 levels (P =0.03). We conclude that oral LA is generally well tolerated and appears capable of reducing serum MMP-9 and sICAM-1 levels. LA may prove useful in treating MS by inhibiting MMP-9 activity and interfering with T-cell migration into the CNS.

The fatty acid-binding protein, aP2, coordinates macrophage cholesterol trafficking and inflammatory activity. Macrophage expression of aP2 impacts peroxisome proliferator-activated receptor gamma and IkappaB kinase activities

Fatty acid-binding proteins are cytosolic fatty acid chaperones, and the adipocyte isoform, aP2, plays an important role in obesity and glucose metabolism. Recently, this protein has been detected in macrophages where it strongly contributes to the development of atherosclerosis. Here, we investigated the role of aP2 in macrophage biology and the molecular mechanisms underlying its actions. We demonstrate that aP2-deficient macrophages display defects in cholesterol accumulation and alterations in pro-inflammatory responsiveness. Deficiency of aP2 alters the lipid composition in macrophages and enhances peroxisome proliferator-activated receptor gamma activity, leading to elevated CD36 expression and enhanced uptake of modified low density lipoprotein. The increased peroxisome proliferator-activated receptor gamma activity in aP2-deficient macrophages is also accompanied by a significant stimulation of the liver X receptor alpha-ATP-binding cassette transporter A1-mediated cholesterol efflux pathway. In parallel, aP2-deficient macrophages display reduced IkappaB kinase and NF-kappaB activity, resulting in suppression of inflammatory function including reduced cyclooxygenase-2 and inducible nitric-oxide synthase expression and impaired production of inflammatory cytokines. Our results demonstrate that aP2 regulates two central molecular pathways to coordinate macrophage cholesterol trafficking and inflammatory activity.