The antiatherogenic effect of new biocompatible cationically modified polysaccharides: chitosan and pullulan - the comparison study

Pullulan and chitosan are biocompatible polysaccharides obtained from natural sources with many biomedical applications. Cationically modified polymers, such as chitosan and pullulan after covalent attachment of glycidyltrimethylammonium chloride (GTMAC), showed beneficial biological properties. In the present study, it was clearly demonstrated and confirmed that both cationically modified polysaccharides (chitosan-GTMAC and pullulan-GTMAC) have the antiatherosclerotic potential by inhibition of atherosclerotic plaque development and controlling the expression of genes involved in lipid metabolism. It has also been shown that the cationically modified chitosan (HTCC) at a dose of 200 mg/kg b.w./day in male apoE-knockout mice acted as hypolipidaemic agent. It was observed that a statistically significant decrease in low-density lipoprotein (LDL) cholesterol level by 32% occurred under the influence of HTCC at a dose of 200 mg/kg b.w./day after 16 weeks of the experiment compared to the control group of apoE(-/-) mice. Moreover, under the influence of cationically modified chitosan administered orally to female apoE-knockout mice at a dose of 300 mg/kg b.w./day for 18 weeks a statistically significant reduction by 33% in the area of atherosclerotic plaque was observed compared to the control group, i.e., apoE-knockout mice whose diet was not supplemented with the cationically modified polysaccharide. Current in vivo studies connected with cationically modified pullulan showed a statistically significant 22% reduction of the area of atherosclerotic plaque in the apoE(-/-) mice fed with a feed containing Pull-GTMAC at a dose of 500 mg/kg b.w./day for 18 weeks in comparison to the control group of apoE-knockout mice. In the in vitro studies it was also shown that cationically modified chitosan acted therapeutically by reduction of the level of the expression of human 3-hydroxy-3-methylglutaryl-CoA reductase (human HMG-CoAR) after 24 hours of incubation with HepG2 cells. However, cationically modified pullulan did not show this effect in the experiment on HepG2 cell line. On the other hand, Pull-GTMAC caused a statistically significant increase in insulin induced gene 1 (INSIG1) expression and increase in mRNA level of LDL receptor in brown fat tissue of female apoE-knockout mice after oral administration with feed at a dose of 300 mg/kg b.w./day for 18 weeks in comparison to the control group of apoE(-/-) mice, that was crearly demonstrated the effect of cationically modified pullulan on the expression of lipid metabolism genes in in vivo conditions. In the present article we have shown for first time that cationically modified pullulan and chitosan have some similarities in their antiatherogenic action but there are also some minor differences in mechanism of their effect on lipid metabolism.

Fibrinolytic Activity and the Effects of Beta-Pyridylcarbinol (Ronicol) in Patients with Arteriosclerosis Obliterans

Twenty-one patients with arteriosclerosis obliterans of lower extremities were treated with beta-pyridylcarbinol (Ronicol) for five weeks. The long-term therapy with beta-pyridylcarbinol did not influence platelet aggregability. Activation of the fibrinolytic system was observed. This fibrinolytic effect of Ronicol was abolished in patients treated with aspirin. In most cases a slight clinical improvement was seen, manifested by elongation of pain-free walking distance and increased blood flow in affected limbs. It is concluded that the therapeutic effect of Ronicol in humans may be partly mediated by the release of endogenous prostacyclin.

On the Mechanism of Thrombolytic Action of Thromboxane Synthetase Inhibitors

Using our in vivo model for studying drugs which prevent deposition of thrombi or dissipate thrombi formed in extracorporeal circulation over a collagen strip superfused with arterial blood of anaesthetized and heparinized cats, we have found that dazoxiben - a thromboxane synthetase inhibitor - possesses not only antithrombotic but also thrombolytic potency in vivo (ED50 = 3.8 mg/kg i.v.). The thrombolytic potency of dazoxiben was antagonized by aspirin at a dose of 50 mg/kg i.v. Moreover, dazoxiben stimulated the generation of prostacyclin in isolated rat aortic slices incubated in platelet rich plasma, but not in platelet poor plasma. It is suggested that the thrombolytic potency of thromboxane synthetase inhibitors after their systemic administration is associated with the release of prostacyclin and/or prostacyclin-stable metabolites by the vascular endothelium owing to feeding of prostacyclin synthetase with prostaglandin endoperoxides acumulated in platelets following the inhibition of thromboxane synthetase.

Anti-atherosclerotic effect of the angiotensin 1-7 mimetic AVE0991 is mediated by inhibition of perivascular and plaque inflammation in early atherosclerosis

BACKGROUND AND PURPOSE

Inflammation plays a key role in atherosclerosis. The protective role of angiotensin 1-7 (Ang-(1-7)) in vascular pathologies suggested the therapeutic use of low MW, non-peptide Ang-(1-7) mimetics, such as AVE0991. The mechanisms underlying the vaso-protective effects of AVE0991, a Mas receptor agonist, remain to be explored.

EXPERIMENTAL APPROACH

We investigated the effects of AVE0991 on the spontaneous atherosclerosis in apolipoprotein E (ApoE)-/- mice, in the context of vascular inflammation and plaque stability.

KEY RESULTS

AVE0991 has significant anti-atherosclerotic properties in ApoE-/- mice and increases plaque stability, by reducing plaque macrophage content, without effects on collagen. Using the descending aorta of chow-fed ApoE-/- mice, before significant atherosclerotic plaque develops, we gained insight to early events in atherosclerosis. Interestingly, perivascular adipose tissue (PVAT) and adventitial infiltration with macrophages and T-cells precedes atherosclerotic plaque or the impairment of endothelium-dependent NO bioavailability (a measure of endothelial function). AVE0991 inhibited perivascular inflammation, by reducing chemokine expression in PVAT and through direct actions on monocytes/macrophages inhibiting their activation, characterized by production of IL-1β, TNF-α, CCL2 and CXCL10, and differentiation to M1 phenotype. Pretreatment with AVE0991 inhibited migration of THP-1 monocytes towards supernatants of activated adipocytes (SW872). Mas receptors were expressed in PVAT and in THP-1 cells in vitro, and the anti-inflammatory effects of AVE0991 were partly Mas dependent.

CONCLUSIONS AND IMPLICATIONS

The selective Mas receptor agonist AVE0991 exhibited anti-atherosclerotic and anti-inflammatory actions, affecting monocyte/macrophage differentiation and recruitment to the perivascular space during early stages of atherosclerosis in ApoE-/- mice.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

New cationically modified pullulan attenuates atherogenesis and influences lipid metabolism in apoE-knockout mice

Pullulan is a biocompatible polysaccharide obtained from black, yeast-like fungus Aureobasidium pullulans. This polymer is used to deliver various substances to the liver because of its specificity for this organ. Pullulan is internalized into hepatocytes in the process of asialoglycoprotein receptor mediated endocytosis. Recently, by reaction with glycidyltrimethylammonium chloride (GTMAC) we have successfully synthesized a cationically-modified pullulan (Pull-GTMAC). Pull-GTMAC exhibits some unique beneficial effects not found for its native counterpart. In this article we have reported for the first time that Pull-GTMAC administered orally to apoE-knockout mice (murine model of atherosclerosis) at a dose of 300 mg/kg b.w./day for 18 weeks showed anti-atherosclerotic activity reducing the area of atherosclerotic plaque. We have also found that Pull-GTMAC at a dose of 300 mg/kg b.w./day increases both the average daily mass of feces and the average number of droppings excreted by apoE(-/-) mouse in relation to the control sample derived from the mice fed with feed without the tested compound. However, the raw fat content in the feces of apoE-knockout mice was decreased in the group fed with the diet containing Pull-GTMAC towards control group of animals. Pull-GTMAC caused also statistically significant increase of mRNA level for LDL receptor in the apoE(-/-) mice liver after administration at a dose of 300 mg/kg/b.w./day for 18 weeks. However, the compound had no impact on lipid profile in serum of the tested mice. What is more, the studies on HepG2 cell line indicated an antiproliferative potential of cationically modified pullulan after 24 hour and 48 hour of incubation with the polysaccharide. In this paper we have shown for first time that cationically modified pullulan has antiatherogenic potential and influences on lipid metabolism.

Polymorphism in the chemokine receptor 7 gene (CCR7) is associated with previous myocardial infarction in patients undergoing elective coronary angiography

Coronary artery disease (CAD) remains a major cause of death in developed countries. Both environmental and, less known, genetic factors contribute to progression of CAD to myocardial infarction (MI). Immune system is activated in patients with CAD through dendritic cells (DCs), which present plaque antigens to T lymphocytes. Production of proinflammatory cytokines by activated T cells contributes to plaque rupture in MI. Chemokine receptor 7 (CCR7) on DCs is required for their chemotaxis from plaque to lymph nodes. This makes possible an interaction of DCs with T lymphocytes and initiation of specific immune response. We hypothesized that single nucleotide polymorphisms (SNPs) in CCR7 gene locus are associated with previous MI in patients with CAD. To test this hypothesis, we genotyped six SNPs from the CCR7 gene locus in 300 consecutive patients, admitted for elective coronary angiography. We performed univariate-, multivariate- (including potential confounders) and haplotype-based tests of association of SNPs with previous MI and results of angiography. Allele A of rs17708087 SNP was associated with previous MI. This association remained significant after adjustment for age, sex, smoking, hypercholesterolaemia and drugs used by patients (odds ratio 2.13, 95% confidence interval: 1.13-3.86). Therefore, we conclude that CCR7 gene locus harbours a polymorphism that modifies risk of MI in patients with CAD. Replication of this association could be sought in a prospective cohort of initially healthy individuals.

Perindoprilat changes ANG (1-9) production in renal arteries isolated from young spontaneously hypertensive rats after ANG I incubation

We used mass spectrometry to quantitate production of angiotensinogen metabolites in renal artery of 3- and 7-month-old Wistar-Kyoto (WKY) and Spontaneously Hypertensive Rats (SHR). Tissue fragments were incubated for 15 min in oxygenated buffer, with added angiotensin I. Concentrations of angiotensins I (ANG I), II (ANG II), III (ANG III), IV (ANG IV), angiotensin (1-9) [ANG (1-9)], angiotensin (1-7) [ANG (1-7)], and angiotensin (1-5) [ANG (1-5)], excreted into the buffer during experiment, were measured using liquid chromatography-mass spectrometry (LC/MS) and expressed per mg of dry tissue. Effects of pretreatment with 10 microM perindoprilat on the production of ANG I metabolites were quantitated. Background production of any of ANG I metabolites differed neither between WKY and SHR rats nor between 3- and 7-month-old rats. Perindoprilat pretreatment of renal arteries resulted, as expected, in decrease of ANG II production. However, renal arteries of 7-month-old SHR rats were resistant to ACE inhibitor and did not change ANG II production in response to perindoprilat. In renal arteries, taken from 3-month-old rats, pretreated with perindoprilat, incubation with ANG I, resulted in the level of ANG (1-9) significantly higher in SHR than WKY rats. Our conclusion is that in SHR rats, sensitivity of renal artery ACE to perindoprilat inhibition changes with age.

The renin-angiotensin system and its vasoactive metabolite angiotensin-(1-7) in the mechanism of the healing of preexisting gastric ulcers. The involvement of Mas receptors, nitric oxide, prostaglandins and proinflammatory cytokines

The inhibition of angiotensin-converting enzyme (ACE) or the blockade of angiotensin (Ang) AT-1 receptors affords protection against acute gastric mucosal injury, but whether the major metabolite of renin-angiotensin system (RAS), Ang-(1-7), accelerates the healing process of preexisting gastric ulcers remains unknown. Previous studies documented that Ang-(1-7) acting via its own Mas receptor exerts vascular responses opposing those of Ang II. We studied the effects of the Ang-(1-7)/Mas receptor axis on the healing rate of acetic-acid-induced gastric ulcers with or without the blockade of Mas receptors by A 779 and compared it with the effects of activation and blockade of the AT-1 receptor by the treatment with Ang II and losartan, respectively, the inhibition of ACE by lisinopril, the NO/cNOS inhibition by L-NAME and inhibition of prostaglandin/COX system by indomethacin in the presence of Ang-(1-7). Additionally, ex vivo metabolism of Ang I in gastric tissue was assessed by LC/MS method. At day 9 after ulcer induction, the area of these ulcers and the accompanying changes in total gastric blood flow (GBF) were determined as were gastric mucosal blood flow (GMBF) at ulcer margin and gastric oxygen uptake (GVO2). The gastric mucosal expression of mRNAs for constitutive nitric oxide synthase (cNOS), superoxide dismutase (SOD), and pro-inflammatory cytokines interleukin 1β (IL-1β) and tumor necrosis factor alpha (TNF-α) and plasma level of both cytokines were determined by RT-PCR and ELISA. The 9 days treatment with Ang II dose-dependently increased the area of gastric ulcers and this effect was accompanied by a significant fall in the GBF, GVO2 and GMBF at ulcer margin. In contrast, treatment with Ang-(1-7) which produced a significant rise in the luminal content of NO significantly reduced the area of gastric ulcer and significantly increased the GBF, GVO2 and the GMBF at ulcer margin. Similar GMBF changes and significant reduction the area of gastric ulcer was observed in rats with gastric ulcers treated with the agonist of Mas receptor, AVE 0991. These effects of Ang-(1-7) and AVE 0991 were eliminated by blockade of the Mas receptor with A779. Similarly to Ang-(1-7), treatment with losartan or lisinopril significantly reduced the area of gastric ulcers and the accompanying increase in the GMBF at ulcer margin and these effects were significantly attenuated by a concomitant administration of L-NAME and indomethacin. The rate of healing of ulcers was associated with a decrease in ex vivo Ang-(1-7) formation and this effect was attenuated by lisinopril. The treatment with Ang-(1- 7) or AVE 0991 increased the expression of mRNA for cNOS and SOD and downregulated that of IL-1β and TNF-α followed by the decrease in the plasma IL-1β and TNF-α levels. We conclude that the Ang-(1-7)/Mas receptor system accelerates the healing of preexisting gastric ulcers via an increase in the gastric macro- and microcirculations, and an increase in gastric tissue oxygenation. These effects are mediated by PG and NO derived from overexpression of cNOS, an increase in the expression of antioxidizing enzyme SOD 2 and an anti-inflammatory action involving the inhibition of expression and release of pro-inflammatory cytokines IL-1β and TNF-α. Our results seem to underlie the importance of the Ang-(1-7), AT-1 and Mas receptors in the regulation of local vascular and metabolic effects associated with mechanism of gastric ulcer healing.

Exogenous Angiotensin I Metabolism in Aorta Isolated from Streptozotocin Treated Diabetic Rats

Purpose. Products of angiotensin (ANG) I metabolism may predispose to vascular complications of diabetes mellitus. Methods. Diabetes was induced with streptozotocin (75 mg/kg i.p.). Rat aorta fragments, isolated 4 weeks later, were pretreated with perindoprilat (3 μM), thiorphan (3 μM), or vehicle and incubated for 15 minutes with ANG I (1 μM). Products of ANG I metabolism through classical (ANG II, ANG III, and ANG IV) and alternative (ANG (1-9), ANG (1-7), and ANG (1-5)) pathways were measured in the buffer, using liquid chromatography-mass spectrometry. Results. Incubation with ANG I resulted in higher concentration of ANG II (P = 0.02, vehicle pretreatment) and lower of ANG (1-9) (P = 0.048, perindoprilat pretreatment) in diabetes. Preference for the classical pathway is suggested by higher ANG III/ANG (1-7) ratios in vehicle (P = 0.03), perindoprilat (P = 0.02), and thiorphan pretreated (P = 0.02) diabetic rat. Within the classical pathway, ratios of ANG IV/ANG II (P = 0.01) and of ANG IV/ANG III (P = 0.049), but not of ANG III/ANG II are lower in diabetes. Conclusions. Diabetes in rats led to preference toward deleterious (ANG II, ANG III) over protective (ANG IV, ANG (1-9), and ANG (1-7)) ANG I metabolites.

Significant deterioration of anti-atherogenic efficacy of nebivolol in a double (apolipoprotein E and endothelial nitric oxide synthase) knockout mouse model of atherosclerosis in comparison to single (apolipoprotein E) knockout model

Anti-atherogenic action of nebivolol in apolipoprotein E (apoE)-single knockout mouse model can be explained by its beneficial effect on endothelium, especially on endothelial nitric oxide synthase (eNOS). We, therefore, decided to use apoE and eNOS-double knockout mouse model to confirm that mechanism of nebivolol beneficial action. In apoE-single knockout mice, lesion area measured by "cross-section" of aortic roots was 79,244 ± 6,143 μm(2) in the control group versus 65,347 ± 6,152 μm(2) in nebivolol-treated group (P<0.05). However, in apoE and eNOS-double knockout mice, lesion area measured by "cross-section" of aortic roots was 92,319 ± 8,876 μm(2) in the control group versus 98,609 ± 9,164 μm(2) in nebivolol-treated group (P>0.05). The comparison between apoE-single knockout mice and apoE & eNOS-double knockout mice without treatment also showed statistically significant difference: 81,232 ± 8,264 μm(2) versus 92,319 ± 8,876 μm(2) (P<0.05). This is the first report that describes the effect of nebivolol on atherogenesis in apoE and eNOS-double knockout mice, proving directly the necessity of the presence of eNOS in endothelium for nebivolol to show its an anti-atherogenic potency.

The current view on biological potency of cationically modified chitosan

Chitosan is biocompatible polymer obtained from chitin, the building component of the crustacean shells. In this paper we make an attempt to review the current state of knowledge on some biological effects of chitosan in comparison with those of cationically modified chitosan, N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC) that was recently synthetized by us by covalent attachment of glycidyltrimethylammonium chloride (GTMAC). Biological effects of HTCC and non-modified polymer are very similar. However, HTCC shows some unique beneficial properties which have not been found in its non-modified counterpart. One such example is that HTCC has the ability to bind heparin at physiological pH. HTCC having the degree of substitution almost 63.6% is easily absorbed within 1 hour after oral administration as found in C57BL/6j mice using FITC-labeled polymer. HTCC is distributed to lung, heart, and kidneys. HTCC stimulates and enhances blood platelet aggregation and decreases erythrocyte deformability (RBC). Moreover, HTCC seems to decrease both plasma total cholesterol level and LDL-cholesterol level in apoE-knockout mice fed with a diet containing HTCC. HTCC possibly down-regulates the HMG-CoAR mRNA level after 24 hour incubation with HepG2 cells in vitro.

The influence of angiotensin-(1-7) peptidomimetic (AVE 0991) and nebivolol on angiotensin I metabolism in aorta of apoE-knockout mice

The detrimental role of over activation of renin-angiotensin system (RAS) in atherogenesis is widely recognized. Recently, we have demonstrated that Ang-(1-7) peptidomimetic - AVE0991, as well as known beta-adrenolytic agent nebivolol, exert anti-atherogenic actions in mouse model of atherosclerosis - apoE-knockout mice. Here, using LC-ESI-MS ex vivo system, we tested whether prolonged treatment of apoE-knockout mice by these drugs can influence RAS in aorta of apoE-knockout mice in regard to generation of most active metabolites of Ang I-Ang II and Ang-(1-7). As compared to wild type animals there was increased generation of Ang II in aorta of apoE-knockout mice, while the formation of Ang-(1-7) did not differ between both groups. Either treatment with AVE0991 or nebivolol resulted in significant attenuation of Ang II production in aorta of apoE-knockout mice. In conclusion, for the first time we directly demonstrated that there is increase in ability of aortic tissue to generate Ang II in mouse model of atherosclerosis of apoE knockout mice, and that such effect could be efficiently attenuated either by treatment of nebivolol or Ang-(1-7) peptidomimetic - AVE0991. The exact mechanism(s) responsible for interference of both drugs with RAS require further investigation.

Vasodilatory effect and endothelial integrity in papaverine- and milrinone-treated human radial arteries

Prevention of the vasospasm is an important aspect of coronary artery bypass grafting (CABG) with the use of radial artery (RA) as the conduit. We compared the effect of two phosphodiesterase inhibitors papaverine and milrinone on vasodilation and endothelial integrity of human RA segments harvested from 20 CABG patients. Vasodilatory effect of the drugs were assessed by organ bath technique in RA rings precontracted with KCl and phenylephrine. Endothelial integrity was evaluated by CD34 immunofluorescence in frozen sections. Vasorelaxation induced by papaverine was significantly greater as compared to that induced by milrinone (90.47% ± 10.16% vs. 78.98% ± 19.56%, p<0.05). Similarly, pretreament with papaverine more strongly inhibited the contractile response of RA rings to KCl (6.0 ± 8.0 mN vs. 26.7 ± 21.5 mN, p<0.001). Papaverine was also superior to milrinone in the preservation of endothelial integrity (75.3% ± 12.9% vs. 51.8% ± 18.0%, p<0.02). In conclusion, papaverine seems to be more suitable than milrinone for prevention of vasospasm in radial artery conduits used for CABG.

Angiotensin-(1-7) receptor Mas agonist ameliorates progress of atherosclerosis in apoE-knockout mice

Our interest focused on an open question whether AT-(1-7), nonpeptide receptor agonist: AVE 0991, is able to ameliorate atherosclerosis. We used an apolipoprotein E (apoE) - knockout mice model of atherosclerosis. Experimental groups received the same diet as control, mixed with: AVE 0991 at a dose of 0.58 μmol/kg b.w./day, perindopril at a dose of 0.4 mg/kg b.w./day or with tiorphan at a dose of 2.5 mg/kg b.w./day. A-779 [(D-alanine)-angiotensin (1-7)] was given at a dose of 3.3 mg/kg b.w., 3 times a week i.p. Measured by "en face" method, the percentage of occupied by Sudan IV-stained surfaces were as follows: 14.2±1.9 % in control group, whereas in AVE 0991-treated as well as in perindopril-treated groups percentages were statistically significantly lower. In tiorphan group there was no change comparing to control group, whereas in A-779 group percentage was statistically significantly higher. "Cross-section" of aortic roots revealed also the difference in atherosclerotic lesions. The mean surfaces, occupied by oil red O-stained changes were: 91.213±8.123 μm(2) in control group, while in AVE 0991-treated as well as in perindopril-treated groups lesions were statistically significantly lower. In tiorphan group there was no change; however, in A-779 group lesions were statistically significantly higher. Measured by real time RT-PCR relative p22phox (submit of NADPH oxidase) expression was significantly decreased in AVE 0991-treated mice. As revealed by flow cytometry, the expression of co-stimulatory molecules: CD86, CD80 and CD40 on both dendritic cells (CD11c+) and macrophages (F4/80+) was reduced in AVE 0991-treated group, which correlated with decreased expression of CD69 activation marker on CD4+T cells. In our report we showed the beneficial effect of AVE 0991 on atherogenesis in gene-targeted mice.

Angiotensinogen and angiotensin-converting enzyme mRNA decrease and AT1 receptor mRNA and protein increase in epididymal fat tissue accompany age-induced elevation of adiposity and reductions in expression of GLUT4 and peroxisome proliferator-activated receptor (PPARγ)

Elevated adiposity is one of the accompanying features of increased age in humans and animals. Angiotensin II (Ang II) is considered as growth promoting peptide to be involved in hypertrophic enlargement of adipose tissue. However, systemic renin-angiotensin system (RAS) seems to decrease with increased age of rats. Local adipose tissue RAS might be independent of the systemic one. Therefore we performed a comprehensive study using rats with increased age from 9 to 26 weeks and evaluated angiotensinogen, angiotensin-converting enzyme (ACE) and AT(1) receptor mRNA in epididymal adipose tissue by RT-PCR. In addition, we determined AT(1) receptor protein by Western blotting and Ang II binding. These RAS parameters were correlated with expression of selected adiposity-dependent proteins such as leptin, adiponectin, insulin-dependent glucose transporter (GLUT4) and PPARgamma. Angiotensinogen and ACE expression decreased with increased age and adiposity. On the contrary, AT(1) receptor mRNA and protein was significantly elevated in 26-week-old rats though the Ang II binding was not different between 9 and 26-week-old animals. These results suggest dynamic adaptation of local adipose tissue RAS components to increased age and adiposity most likely by decreasing local Ang II formation which is thereafter compensated by increased expression of AT(1) receptor. However, this increase in AT(1) receptor mRNA and protein is not reflected in increased receptor binding. We believe that this complex regulation of adipose tissue RAS slows down the negative age and adiposity related changes in adipose tissue leptin, adiponectin, GLUT4 and PPARgamma.

The effect of doxycycline on atherogenesis in apoE-knockout mice

Doxycycline at subantimicrobial doses inhibits matrix metalloproteinases (MMPs) activity, and is the only MMP inhibitor which is widely available in clinical practice. The aim of the study was to reveal whether non-specific MMPs inhibition by tetracycline could ameliorate development of atherosclerosis in apolipoprotein E (apoE)-knockout mice. Doxycycline (1.5 mg/ kg b.w./day) administered orally attenuated atherogenesis, measured both by "en face" method (10.25±1.7% vs. 15.7±2.0%, p<0.05) and "cross-section" method (66,254±7,468 μm(2) vs. 90,687±8,521 μm(2), p<0.05). In-situ zymography showed decrease of the extent of non-specific gelatinase activity in doxycycline-treated mice This is the first report to date describing the effect of doxycycline on atherogenesis in apoE-targeted mice.

The current view on the role of leukotrienes in atherogenesis

Since inflammation plays an important role in atherogenesis, during recent years it has become apparent that the 5-lipoxygenase (5-LO) pathway may take significant part in modifying the pathogenesis of atherosclerosis. Indeed, it has been recently demonstrated that the 5-LO substantially contribute to atherosclerosis in both mouse models and humans. However, animal models potentially bear the risk of compensatory mechanisms, due to genetic modification of the target gene that render the results difficult to interpret. Another caveat is species differences between mice and humans. 5-LO expression in intimal atherosclerotic lesions varies between mice and humans; also, 5-LO and 12/15-LO appear to be differentially regulated in inflammatory cells of mice. Moreover, atherogenesis in mice differs in several facets from the human pathology. Thus, T cells, whose presence in all stages of atherosclerotic lesions is acknowledged, are underrepresented in murine models of atherosclerosis. 5-LO/LT pathway shows important disparities between murine and human atherosclerosis. Advanced human plaques show differences in 5-LO expression compared with mouse lesions. Taken together, in advanced human atherosclerosis, a role for 5-LO is likely, which is distinct from its role in early atherogenesis. This presence of the 5-LO/LT pathway in advanced lesions is not found in mouse models, which might be due to: (i) rapid progression of atheroma growth in mice vs. slower, often interrupted progression in humans; (ii) advanced human plaques display a higher degree of instability and risk to rupture than murine plaques; (iii) temporal dissociation in the Th1/Th2 'balance' at distinct lesion stages between mice and humans.

Angiotensinogen metabolism in rat aorta: robust formation of proangiotensin-12

Renin-angiotensin system (RAS) plays important role in the regulation of vessel wall homeostasis. Proangiotensin-12 (proAng-12, Ang-(1-12)) is a newly characterized metabolite of angiotensinogen, formed in array of organs of rats, which may serve as an alternate substrate for local angiotensin production, by-passing the traditional renin-dependent conversion of angiotensinogen to angiotensin I. In this work using LC/MS method we identified proAng-12 as a main product of angiotensinogen metabolism ex vivo, in organ-bath of rat aortic tissue. In this setting, proAng-12 appeared to be not only prevalent metabolite of angiotensinogen, but also served as a substrate for generation of Ang I and subsequently, Ang II. The functional significance of this surprising finding requires further investigation.

AVE 0991-angiotensin-(1-7) receptor agonist, inhibits atherogenesis in apoE-knockout mice

Recent evidence shows that the renin-angiotensin system is a crucial player in atherosclerotic processes. It was also proved that Ang II promotes atherogenesis. Angiotensin-(1-7) [Ang-(1-7)] opposites Ang II action. Therefore, we would like to find out whether Ang-(1-7) receptor agonist: AVE 0991, could ameliorate atherosclerosis progression in an experimental model of atherosclerosis: apolipoprotein E (apoE) - knockout mice. AVE 0991 inhibited atherogenesis, measured both by "en face" method (7.63+/-1.6% vs. 14.6+/-2.1%) and "cross-section" method (47 235+/-7 546 microm(2) vs. 91 416+/-8 357 microm(2)). This is the first report showing the effect of AVE 0991 on atherogenesis in gene-targeted mice.

The effect of nebivolol on atherogenesis in apoE-knockout mice

Nebivolol is a novel beta1-blocker with a nitric oxide (NO)--potentiating, vasodilatory effect that is unique among beta-blockers. It was already shown that nebivolol ameliorates atherosclerosis in cholesterol-fed rabbits. We, therefore, wanted to investigate whether this is the case in the fine experimental model of atherosclerosis: apolipoprotein E (apoE)-knockout mice. Nebivolol attenuated atherogenesis, measured both by "en face" method (9.23+/-1.8% vs. 14.6+/-2.1%) and "cross-section" method (63125+/-8455 microm(2) vs. 91416+/-8357 m(2)). This is the first report showing the effect of nebivolol on atherogenesis in gene-targeted mice.

Angiotensin metabolism in rat stomach wall: prevalence of angiotensin-(1-7) formation

Our view of renin-angiotensin system (RAS) has changed over the past two decades: new metabolites and pathways have been described; also the importance of local renin-angiotensin systems became more clearly understood. However, there is relatively scarce information about formation and action of angiotensin peptides in gastrointestinal tract, especially in the stomach. Here, using LC-ESI-MS method we assessed the metabolism of Ang I in organ bath of rat stomach wall. Additionally we compared the expression of mRNA of angiotensin converting enzymes (ACE, ACE2) and neprilysin (NEP) in the stomach, aorta and renal artery in rats. Despite, similar levels of expression of ACE and ACE2 mRNA in stomach wall, aorta and renal artery, the absolute amounts of main Ang I metabolites produced by stomach wall (in ng/mg of dry tissue) were much lower than that produced by aorta and renal artery. Also, the pattern of angiotensin I metabolites was different: opposite to aorta and renal artery, incubation of Ang I with stomach wall fragments resulted in predominant formation of Ang-(1-7) and relatively lower production of Ang II. In stomach wall both, perindoprilat and tiorphan decreased production of Ang II, but did not influence generation of Ang-(1-7). In conclusion, we identified Ang-(1-7) as the main product of Ang I conversion in rat stomach wall. The biological role of prevalence of Ang-(1-7) formation in stomach require further investigation.

The effect of montelukast on atherogenesis in apoE/LDLR-double knockout mice

We have shown that inhibitors of five lipoxygenase activating protein (FLAP)--MK-886 and BAYx1005 inhibit atherosclerosis in apolipoprotein E/LDL receptor-double knockout mice. We, therefore, investigated whether cysteinyl leukotrienes receptor inhibitor--montelukast, given at a dose of 0.125 microg per 100 mg of body weight per day during 16 weeks, could also attenuate atherogenesis. In apoE/LDLR-DKO mouse model montelukast significantly decreased atherogenesis, measured both by "en face" method (25.5+/-2.% vs. 17.23 +/- 1.8%) and "cross-section" method (455,494 +/- 26,477 microm(2) vs. 299,201 +/- 20,373 microm(2)). The results were, however, less pronounced, comparing to FLAP inhibitors. This is the first report showing the effect of montelukast on atherogenesis in gene-targeted mice.

Kaempferol, but not resveratrol inhibits angiotensin converting enzyme

Inhibition of angiotensin converting enzyme (ACE) has proved to be beneficial in the treatment of various cardiovascular disorders. The aim of this study was to evaluate ACE inhibitory potential of two polyphenolic compounds with different structures: resveratrol (present in high quantities in French wine) and kaempferol (abundant in greens), using method of liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS) for ex vivo measurement of angiotensin I to angiotensin II conversion by ACE in aortic tissue of Wistar-Kyoto rats. In this setting, kaempferol (10-30-100 microM), but not resveratrol (10-30-100 microM) appeared to inhibit dose-dependently conversion of Ang I to Ang II. Although the mechanism of ACE inhibition by kaempferol remains to be elucidated, this observation may help in search or designing of new classes of ACE inhibitors.

NADPH oxidase and uncoupled nitric oxide synthase are major sources of reactive oxygen species in oral squamous cell carcinoma. Potential implications for immune regulation in high oxidative stress conditions

The development of cancer is associated with high oxidative stress and at the same time with immune system activation. Tumors develop efficient mechanisms of protection against the immune response, which allow them to escape the immune surveillance. Simultaneously, key events in the process of carcinogenesis are related to oxidative stress. The relationship between the two remains unknown. Novel understanding of oxidative stress shows that discrete changes of activities of certain enzyme systems such as NADPH oxidases or nitric oxide synthases may be more important than the overall balance of production and removal of reactive oxygen species. Such imbalance of nitric oxide and superoxide production could modify inflammation and immune regulation. We studied superoxide anion production (by lucigenin enhanced chemiluminescence - 5 microM), NADPH oxidase activity and nitric oxide synthase (NOS) dysfunction. In parallel mRNA expression of immunomodulatory markers such as FoxP3 (T regulatory cell marker), CCR6 (mucosal homing effector T cell marker) and CD85j (NK cell/CD8 T cell Ig-like MHC class I inhibitory receptor) was determined. Basal superoxide production and NADPH oxidase activity are increased in oral squamous cell carcinoma. Tumor superoxide production was inhibited by NADPH oxidase inhibitor apocynin and by NOS inhibitor L-NAME. This indicates, for the first time, that oral squamous cell carcinoma is characterized by dysregulated nitric oxide synthase, which apart from increased NADPH oxidase activity contributes to oxidative stress and may be related to the immuno-pathology of these tumors. Studied tumors were infiltrated by CCR6+, but showed lower expression of both CD85j and FoxP3 mRNA. Finally, the CD85j mRNA expression was inversely correlated to oxidative stress parameters. These preliminary studies indicate that tumor oxidative stress, related to NADPH oxidase activity and NOS activity could be related to immune responses to cancer, thus therapeutic modification of oxidative stress, which could include the correction of NOS dysfunction, could facilitate immune surveillance.

Perivascular adipose tissue as a messenger of the brain-vessel axis: role in vascular inflammation and dysfunction

Perivascular adipose tissue AT is a critical regulator of vascular function, which until recently has been greatly overlooked. Virtually all arteries are surrounded by a significant amount of perivascular adipose tissue, which has long been considered to serve primarily a supportive, mechanical purpose. Recent studies show that both visceral and perivascular fat is a very active endocrine and paracrine source of inflammatory cytokines and adipokines. The latter include beneficial adipocytokines such as adiponectin or so far unidentified adipocyte derived relaxing factor (ADRF) as the presence of perivascular AT may decrease contractile responses to vasoconstrictive agents. However, in pathological states such as obesity, hypertension, diabetes metabolic syndrome and other cardiovascular disorders perivascular tissue becomes dysfunctional and production of protective factors diminishes while detrimental adipocytokines such as leptin, resistin, IL-6, TNF-alpha or IL-17 increases. Moreover the dysfunction of perivascular fat can lead to imbalance between vascular nitric oxide (NO) and superoxide production. Adipokines also regulate immune system as chemokines (such as MIP-1 or RANTES) and induce inflammation with infiltration of T cells and macrophages to the vessel wall. Interestingly central nervous system can affect vascular function through mediation of perivascular adipose tissue dysfunction. In particular sympathetic nervous system endings are present in both visceral and perivascular AT. This powerful relationship between the brain and the vessel can be termed "brain-vessel axis" in which--we propose in the Review--perivascular adipose tissue may take center stage. The role of perivascular fat in the regulation of blood vessels depends on metabolic state, inflammation and clinical risk factors. In health protective and vasorelaxant properties of perivascular AT dominate while in pathology pathogenetic influences including neural stimulation of sympathetic nerve endings or humoral effects of certain hormones and adipocytokines dominates. We propose to term this state "perivascular adipose tissue dysfunction" in similarity to endothelial dysfunction.

BAY x 1005 attenuates atherosclerosis in apoE/LDLR - double knockout mice

Recently, we have shown that MK-886 - an inhibitor of five lipoxygenase activating protein (FLAP) inhibits atherosclerosis in apolipoprotein E / LDL receptor - double knockout mice. We, therefore, wanted to find out if other FLAP inhibitor - BAYx1005 given at a dose of 1.88 mg per 100 mg of body weight per day during 16 weeks, could also attenuate atherogenesis. In apoE/LDLR - DKO mouse model BAYx1005 inhibited atherogenesis, measured both by "en face" method (23.84 +/- 2.7% vs. 15.16 +/- 1.4%) and "cross-section" method (497236 +/- 31516 microm(2) vs. 278107 +/- 21824 microm(2)). This is the first report that shows the effect of BAYx1005 on atherogenesis in gene-targeted mice.

Measurement of angiotensin metabolites in organ bath and cell culture experiments by liquid chromatography - electrospray ionization - mass spectrometry (LC-ESI-MS)

The metabolism of renin-angiotensin system (RAS) is more complicated than previously expected and understanding the biological phenomena regulated by variety of angiotensin metabolites requires their precise and possibly comprehensive quantitation. Physiological concentrations of angiotensins (Ang) in biological fluids are low, therefore their accurate measurements require very sensitive and specific analytical methods. In this study we developed an accurate and reproducible method of quantitation of angiotensin metabolites through coupling of liquid chromatography and electrospray ionization - mass spectrometry (LC-ESI-MS). With this method main angiotensin metabolites (Ang I, II, III, IV, 1-9, 1-7, 1-5) can be reliably measured in organ bath of rat tissues (aorta, renal artery, periaortal adipose tissue) and in medium of cultured endothelial cells (EA.hy926), exposed to Ang I for 15 minutes, in the absence or in the presence of angiotensin converting enzyme inhibitor, perindoprilat. Presented LC-ESI-MS method proved to be a quick and reliable solution to comprehensive analysis of angiotensin metabolism in biological samples.

Production of prostacyclin and prostaglandin E2 in resting and IL-1beta-stimulated A549, HUVEC and hybrid EA.HY 926 cells

Production of arachidonic acid (AA) metabolites - prostacyclin (PGI(2)) in large vessels and prostaglandin E(2) (PGE(2)) in microcirculation is intrinsically involved in maintenance of vascular wall homeostasis. EA.hy 926 is a hybrid cell line, is derived by fusion of HUVEC with A549 cells. The aim of this study was to examine the production of prostacyclin and PGE2 in resting and IL-1beta-stimulated EA.ha 926 cells, in comparison with its progenitor cells. Non-stimulated EA.hy 926 cells has been found to produce much lower amounts of prostacyclin than resting HUVEC. Resting hybrid cells produced more PGE(2) than prostacyclin, despite they expressed high levels of COX-1 and PGI(2) synthase. On the contrary to HUVEC and A549, EA.hy 926 cells did not respond to IL-1beta with COX-2 induction and increase of prostaglandin production, however they did it in response to lysophosphatidylcholine (LPC). The characteristics of EA.hy 926 cells in terms of the pattern of prostanoid formation could facilitate studies on endothelial metabolism and role of these important lipid mediators.

Effects of novel plant antioxidants on platelet superoxide production and aggregation in atherosclerosis

Superoxide anion is produced in human platelets predominantly by Nox2-dependent NADPH oxidases. In vitro experiments have shown that it might play a role in modulating platelet functions. The relationship between platelet superoxide production and aggregation remains poorly defined. Accordingly, we aimed to study superoxide production and aggregation in platelets from subjects with significant cardiovascular risk factors (hypertension, hypercholesterolemia, smoking and diabetes mellitus) and from control individuals. Moreover, we studied the effects of novel polyphenol-rich extracts of Aronia melanocarpa (chokeberry) berries on platelet function in vitro. Superoxide production was significantly increased in patients with cardiovascular risk profile when compared to controls, while platelet aggregation in response to either collagen or thrombin were borderline higher, and did not reach statistical significance. Interestingly, no relationship was observed between platelet aggregation ex vivo and platelet superoxide production in either of studied groups. No correlation was found between endothelial function (measured by FMD) and platelet aggregation ex vivo either. Polyphenol-rich extracts of A. melanocarpa berries caused a significant concentration dependent decrease in superoxide production only in patients with cardiovascular risk factors, while no effect was observed in the control group. A. melanocarpa extracts abolished the difference in superoxide production between risk factor patients and controls. A. melanocarpa extracts exerted significant concentration dependent anti-aggregatory effects in both studied groups, which indicated that these effects may be independent of it's ability to modulate superoxide production. The anti-aggregatory effects of chokeberry extracts were similar irrespective of aggregation inducing agent (collagen or thrombin). Moreover, they appear to be independent of platelet NO release as NOS inhibition by L-NAME did not lead to their abrogation.

Adipocytokines - novel link between inflammation and vascular function?

Obesity and obesity related diseases are a major public health problem. Recent studies have shown that fat tissue is not a simple energy storage organ, but exerts important endocrine and immune functions. These are achieved predominantly through release of adipocytokines, which include several novel and highly active molecules released abundantly by adipocytes like leptin, resistin, adiponectin or visfatin, as well as some more classical cytokines released possibly by inflammatory cells infiltrating fat, like TNF-alpha, IL-6, MCP-1 (CCL-2), IL-1. All of those molecules may act on immune cells leading to local and generalized inflammation and may also affect vascular (endothelial) function by modulating vascular nitric oxide and superoxide release and mediating obesity related vascular disorders (including hypertension, diabetes, atherosclerosis, and insulin resistance) but also cancer or non-alcoholic fatty liver diseases. Present review, in a concise form, focuses on the effects of major adipocytokines, characteristic for adipose tissue like leptin, adiponectin, resistin and visfatin on the immune system, particularly innate and adaptive immunity as well as on blood vessels. Macrophages and T cells are populating adipose tissue which develops into almost an organized immune organ. Activated T cells further migrate to blood vessels, kidney, brain and other organs surrounded by infiltrated fat leading to their damage, thus providing a link between metabolic syndrome, inflammation and cardiovascular and other associated disorders. Ceretain treatments may lead to significant changes in adipocytokine levels. For example include beta-2 adrenoreceptor agonists, thiazolidinediones as well as androgens lead to decrease of plasma leptin levels. Moreover future treatments of metabolic system associated disorders should focus on the regulation of adipocytokines and their modes of action.

Pharmacology at the Jagiellonian University in Kracow, short review of contribution to global science and cardiovascular research through 400 years of history

Pharmacology at the Jagiellonian University was taught since the foundation of the University in 1364 under then used names of medical botany and pharmacognosy. The first in Poland Division of Pharmacology and Pharmacognosy was created in 1857. Modern era in the history of pharmacology in Krakow starts in 1929 when Prof. Janusz Supniewski became the Head of the Department. He was the relentless researcher whose scientific interests were as diverse as ranging from anticancer chemotherapeutics, antibiotics, and oral hypoglycemic drugs to lipid-lowering agents. Skills of organic chemistry synthesis were of paramount importance for the scientific achievements. Prof. Supniewski died in 1964, leaving the Department well equipped in instruments. He raised in his laboratory many eminent scientists who later became heads of pharmacology departments throughout Poland. In 1964, the Head of the Department of Pharmacology became Prof. Ryszard Gryglewski. Under his leadership the Department focused scientific efforts on various aspects of cardiovascular pharmacology. Prof. Gryglewski established collaborations with many of the best pharmacology researchers in the world, including Sir John Vane, Nobel Prize laureate. Prof. Gryglewski's assistants had ample opportunity to train in these laboratories and to bring these skills back to Krakow. Prof. Gryglewski and his team published many articles in the most prestigious scientific journals. The most important themes included discovery of prostacyclin, role of nitric oxide and of free radicals for vascular biology. Since 2003, when Prof. Gryglewski retired, the Department of Pharmacology has been led by Prof. Ryszard Korbut.

Inhibition of NOS-2 induction in LPS-stimulated J774.2 cells by 1, 5-isoquinolinediol, an inhibitor of PARP

Activation of both poly (ADP-ribose) polymerase (PARP) and inducible nitric oxide synthase (NOS-2) have been implicated in the pathogenesis of various forms of inflammation, therefore compounds which may simultaneously inhibit both pathways are of potential therapeutic interest. We tested the influence of potent inhibitor of PARP, 1, 5-isoquinolinediol (ISO), on NOS-2 induction in model of mouse macrophages (cell line J774.2) stimulated with lipopolysaccharide (1 microg/ml). Pretreatment with ISO (1-300 microM) resulted in dose-dependent inhibition of accumulation of NOS-2-derived nitrite in culture medium (IC(50) = 9,3 microM) as well as inhibition of NOS-2 protein induction in cultured J774.2 cells; ISO given 10 hours after LPS did not influence activity of NOS-2. Interestingly, another PARP inhibitor, 3-aminobenzamide (3-AB, 10-3000 microM), did not influence 24-hr nitrite accumulation in J774.2 cell culture, either administered 15 minutes prior to LPS or 10 hrs after LPS. Scavenging of reactive oxygen species by use of mixture of SOD and catalase (SOD/Cat, 100/300 - 1000/3000 U/ml) as well as cell permeable SOD-mimetic [Mn(III)TBAP, 1- 100 microM], did not influence NOS-2 induction in J774.2 cells. In summary, we identified 1, 5-isoquinoline as potent inhibitor of induction of NOS-2 in LPS-treated mouse macrophages. The exact mechanism of inhibitory action of this compound on NOS-2 induction requires further investigation.

Inhibition of five lipoxygenase activating protein (FLAP) by MK-886 decreases atherosclerosis in apoE/LDLR-double knockout mice

BACKGROUND

Recent reports point to an important role of leukotrienes in atherogenesis. Leukotrienes are produced by 5-lipoxygenase co-operating with five lipoxygenase activating protein (FLAP). We hypothesized that MK-886, an inhibitor of FLAP, could attenuate the development of atherosclerosis in the atherogenic apolipoprotein E/low density lipoprotein receptor (apoE/LDLR) double knockout (DKO) mouse model.

MATERIALS AND METHODS

Female apoE/LDLR-DKO mice at the age of 8 weeks were put on Western diet. The experimental group (n = 10) received the same diet as the control group (n = 10), but mixed with MK-886 (Merck, Rahway, NJ) at a dose of 4 microg per 100 mg of body-weight per day. At age 6 months the mice were sacrificed under anaesthesia.

RESULTS

Measured by the en face method, the percentage of area occupied by lesions in aortas in the control group was 25.15 +/- 2.9%, whereas in the MK-886-treated group it was 11.16 +/- 0.7% (P < 0.05). Lesion area measured by cross-section of aortic roots was 455,494 +/- 29,564 microm(2) in the control group versus 263,042 +/- 20,736 microm(2) in the MK-886-treated group (P < 0.05). The MK-886 did not change the plasma cholesterol lipoprotein profile as compared with the control mice. Finally, we show that MK-886 may increase plaque stability by decreasing the macrophage content as well as increasing the collagen and smooth-muscle cell content.

CONCLUSIONS

Our results show for the first time that inhibition of FLAP by MK-886 reduces development of atherosclerosis in gene-targeted apoE/LDLR-DKO mice.

The involvement of adhesion molecules and lipid mediators in the adhesion of human platelets to eosinophils

Platelet-leukocyte interactions represent an important determinant of the inflammatory response. Although mechanisms of platelet-neutrophil adhesion were studied extensively, little is known on the mechanisms of platelet-eosinophil interactions. The aim of the present study was to analyze the involvement of adhesion molecules and lipid mediators in platelet-eosinophil adhesion as compared to platelet-neutrophil adhesion. For that purpose human platelets, eosinophils and neutrophils were isolated and platelet-eosinophil and platelet-neutrophil adhesion induced by thrombin (30 mU/ml), LPS (0.01 microg/ml) and fMLP (1 microM) was quantified using the "rosettes" assay. The involvement of adhesion molecules such as selectin P, glycoprotein IIb/IIIa (GPIIb/IIIa) and lipid mediators such as of thromboxane A2 (TXA2), platelet activating factor (PAF) and cysteinyl leukotrienes (cysLTs) were studied using monoclonal antibodies and pharmacological inhibitors, respectively. Thrombin (30 mU/ml), LPS (0.01 microg/ml) and fMLP (1 microM) each of them induced platelet-eosinophil adhesion that was even more pronounced as compared with platelet-neutrophil adhesion induced by the same stimulus. Anti-CD62P antibody (1 microg/ml) and anti-GP IIb/IIIa antibody (abciximab-3 microg/ml) strongly inhibited platelet-eosinophil as well as platelet-neutrophil adhesion. Aspirin inhibited platelet-eosinophil adhesion, while MK 886-a FLAP inhibitor (10 microM), or WEB 2170-a PAF receptor antagonist (100 microM) were less active. On the other hand aspirin, MK 886 and WEB 2170 all three of them inhibited platelet-neutrophil adhesion. In summary, platelets adhered avidly to eosinophils both after activation of platelets by thrombin, eosinophils by fMLP or simultaneous activation of platelets and eosinophils by LPS. Similarly to platelet-neutrophil interaction adhesion of platelets to eosinophils involved not only adhesion molecules (selectin P, GPIIb/IIIa), but also lipid mediators such as TXA2. The involvement of PAF and cysteinyl leukotrienes in platelet-eosinophil adhesion was less pronounced as compared to platelet-neutrophil adhesion.

Effect of curcumin on atherosclerosis in apoE/LDLR-double knockout mice

It is widely appreciated that inflammation and oxidant stress contribute to atherogenesis. Curcumin, a polyphenolic natural compound has been reported to possess anti-inflammatory and anti-oxidant actions. We hypothesized that curcumin could inhibit the development of atherosclerosis in the apoE/LDLR-double knockout mice fed with Western diet (21% fat, 0.15% cholesterol w/w, without cholic acid). Curcumin (purity>or=98%), premixed with diet, was given for 4 months at a dose of 0.3 mg/ per day/ per mouse. In this model curcumin inhibited atherogenesis, measured both by "en face" method (25,15+/-2,9% vs. 19,2+/-0,6%, p<0,05) and "cross-section" method (565867+/-39764 microm2 vs. 299201+/-20373 microm2, p<0,05). Importantly, curcumin influenced neither the concentrations of cholesterol and triglycerides in blood nor animal body weight. To our knowledge, this is the first report that shows the anti-atherogenic effect of low dose of curcumin in fine model of atherosclerosis: gene-targeted apoE/LDLR-double knockout mice.

Inhibition of nuclear factor-kappaB attenuates artherosclerosis in apoE/LDLR - double knockout mice

Nuclear factor - kappaB (NF-kappaB) is a good therapeutic target for cardiovascular disease and numerous efforts are being made to develop safe NF-kappaB inhibitors. Nowadays many authors address NF-kappaB as a major therapeutic target in atherosclerosis, especially for preventive measures, in the light of two main hypothesis of atherosclerosis: oxidation and inflammation. We hypothesized that ammonium pyrrolidinedithioocarbamate (PDTC) - a well-known inhibitor of NF-kappaB could inhibit the development of atherosclerosis in this experimental model. We used apoE/LDLR - DKO mouse model, which is considered as a one of the best models to study the anti-atherosclerotic effect of drugs. In this model PDTC inhibited atherogenesis, measured both by "en face" method (25,15+/-2,9% vs. 15,63+/-0,6%) and "cross-section" method (565867+/-39764 microm2 vs. 291695+/-30384 microm2). Moreover, PDTC did not change the profile of cholesterol and triglycerides in blood. To our knowledge, this is the first report that shows the effect of PDTC on atherogenesis in gene-targeted apoE/LDLR - double knockout mice.

Superoxide dismutase activity and expression in human venous and arterial bypass graft vessels

Venous bypass grafts are more prone to accelerated atherosclerosis than arterial grafts, which is partly related to increased oxidative stress and diminished nitric oxide bioavailability. In veins superoxide production is dependent primarily on nox2 NAD(P)H oxidase expression, while in arteries nox4 appears to play an important role. This may in part explain differences in susceptibility to graft failure. Net levels of oxidative stress are however determined in parallel by the production as well as by degradation of free radicals (eg. by superoxide dismutases, catalases, thioredoxins etc). The differences in superoxide dismutase (SOD) expression and activity in human bypass conduit vessels remain unclear. Accordingly, we aimed to compare SOD activity and protein levels as well as its functional effects on superoxide production in segments of human internal mammary arteries (IMA) and saphenous veins (HSV) from patients undergoing bypass graft surgery (n=24). SOD activity was assessed by inhibition of pyrogallol autoxidation, Cu-Zn SOD and Mn SOD protein levels were studied by immunoblotting. Basal superoxide release was detected by lucigenin (5 microM) enhanced chemiluminescence. Total SOD activity did not differ significantly between HSV and IMA. Similarly, no difference was observed in SOD activity in the presence of KCN (Mn-SOD). Human bypass conduit vessels show amounts of Cu-Zn SOD or Mn-SOD protein levels. In both HSV and IMA segments superoxide production was more than doubled in the presence of SOD inhibitor-DETC.

CONCLUSIONS

These studies suggest that the differences in oxidative stress between human arteries and veins are unlikely to be caused by SOD activity. However SOD plays and important role in amelioration of oxidative stress in both types of vessels.

Endotoxaemia in rats: role of leukocyte sequestration in rapid pulmonary nitric oxide synthase-2 expression

Nitric oxide (NO), depending on the amount, time and source of generation may exert both, protective and deleterious actions during endotoxic acute lung injury (ALI). Evaluation of the expression and localization of NOS isoforms in the lung of lipopolysaccharide (LPS)-treated rats may contribute to understanding the role of NO in pathogenesis of ALI. Tissue samples (lung, heart, liver, kidney and spleen) as well as peripheral blood polymorphonuclear cells (PMNs) were collected from control male Wistar rats and LPS - treated animals, 15, 30, 60, 120 and 180 min after LPS injection (2 mg kg(-1) min(-1) for 10 minutes, i.v.). Levels of NOS-2 and NOS-3 mRNA and protein in tissues and PMNs were estimated by RT-PCR, Northern blotting and Western blotting. Additionally, myeloperoxidase (MPO) activity in tissue samples was assayed. NOS-3 mRNA as well as protein were detected in lungs of control animals; pulmonary NOS-3 expression was not influenced by LPS. The induction of NOS-2 mRNA in rat lungs and in PMNs isolated from peripheral blood was observed 15 minutes after LPS challenge. In contrast, increase of NOS-2 mRNA in the heart, kidneys, liver and spleen was observed 2-3 hours after LPS injection. In all tissues rise in NOS-2 mRNA was followed after 1-2 hours by increase of NOS-2 protein. Importantly, progressive leukocyte sequestration in the lung parenchyma that started as early as 15 min after LPS injection was revealed only in the lungs; in other organs no significant changes in MPO activity were detected up to 180 min after LPS injection. In conclusion, infusion of LPS caused much more rapid expression of NOS-2 in lungs as compared to the heart, kidneys, liver and spleen. Early induction of NOS-2 may depend on the LPS-stimulated rapid neutrophil sequestration within lung vasculature and fast induction of NOS-2 in sequestrated neutrophils.

Effects of prolonged oral supplementation with l-arginine on blood pressure and nitric oxide synthesis in preeclampsia

BACKGROUND

Several lines of evidence point to the dysfunction of the endothelial l-arginine-NO system in preeclampsia. We investigated the influence of dietary supplementation with l-arginine on blood pressure and biochemical measures of NO production in women with preeclampsia in prospective, randomized, placebo-controlled study.

DESIGN

The 61 preeclamptic women on a standardized low nitrate diet received orally 3 g of l-arginine (n = 30) or placebo (n = 31) daily for 3 weeks as a supplement to standard therapy. The differences between the two groups in systolic (SBP), diastolic (DBP) and mean arterial blood pressures (MAP) as well as in plasma levels of selected aminoacids, plasma concentrations of nitrates/nitrites (NOx) and in 24-h urine NOx excretion were determined.

RESULTS

After 3 weeks of treatment, values of SBP, DPB and MAP were significantly lower in the group taking l-arginine as compared with the placebo group (SBP: 134.2 +/- 2.9 vs. 143.1 +/- 2.8; DBP: 81.6 +/- 1.7 vs. 86.5 +/- 0.9; MAP: 101.8 +/- 1.5 vs. 108.0 +/- 1.2 mmHg, P < 0.01). Importantly, treatment with exogenous l-arginine significantly elevated 24-h urinary excretion of NOx and mean plasma levels of l-citrulline. Exogenous l-arginine did not influence plasma concentrations of l-arginine, l-ornithine and methylated arginines (ADMA, SDMA, L-NMMA).

CONCLUSIONS

We conclude that in women with preeclampsia, prolonged dietary supplementation with l-arginine significantly decreased blood pressure through increased endothelial synthesis and/or bioavailability of NO. It is tempting to speculate that the supplementary treatment with l-arginine may represent a new, safe and efficient strategy to improve the function of the endothelium in preeclampsia.

Effect of aspirin on cysteinyl leukotrienes production by eosinophils co-cultured with epithelial cells

Eosinophils have long been considered to play solely crucial role in the pathogenesis of aspirin-induced asthma, however increasing evidence suggest that the bronchial epithelium is also involved in the initiation and maintenance of allergic inflammation. Epithelial cells and eosinophils retained within airways interact reciprocally to mount and sustain inflammatory response. Recently, we have shown that eosinophil-epithelial cell interactions are capable of amplifying the production of cysteinyl leukotrienes (Cys-LTs). The aim of this study was to investigate if there is any influence of aspirin (ASA) on Cys-LTs and prostaglandin E2 (PGE(2)) production in the model of co-cultured human epithelial cells (line BEAS-2B) and human eosinophils. Synthesis of Cys-LTs in eosinophils was increased after incubation with ASA. At the same time the production of PGE(2) was decreased by aspirin (n=32). BEAS-2B cells barely formed Cys-LTs; addition of ASA increased this production, while production of PGE(2) was inhibited by aspirin (n=32). Synthesis of Cys-LTs by eosinophils co-incubated with BEAS-2B was nearly 7-fold higher than that of activated eosinophils alone (1631.5 pg/ml +/- 154 vs. 258 pg/ml +/- 31; p<0.05; n=32). Surprisingly, in the eosinophil-epithelial cell co-culture, aspirin inhibited both augmentation of Cys-LTs synthesis (from 1631.5 pg/ml +/- 154 to 1458 pg/ml +/- 137; p<0.05; n=32) and the production of PGE2 (from 2640 pg/ml +/- 231 to 319 pg/ml +/- 27; p<0.05; n=32). In summary, we have demonstrated that interactions between non-atopic eosinophils and epithelial cells result in augmentation of Cys-LTs production, and this augmentation could be inhibited by aspirin.

Mouse models of experimental atherosclerosis

Since 1992 the mouse has become an excellent model for experimental atherosclerosis research. Until 1992, the diet -- induced atherosclerosis mouse model has been used effectively, but the lesions tended to be small and were limited to early fatty-streak stage. This model was also criticized because of the toxicity and inflammatory responses due to the diet. In 1992 the first line of gene targeted animal models, namely apolipoprotein E -- knockout mice was developed. Of the genetically engineered models, the apoE -- deficient model is the only one that develops extensive atherosclerotic lesions on a chow diet. It is also the model in which the lesions have been characterized most thoroughly. The lesions develop into fibrous plaques; however, there is no evidence that plaque rupture occurs in this model. The LDL receptor - deficient model has elevated LDL levels, but no lesions, or only very small lesions, form on the chow diet, however, robust lesions do form on the western-type diet. The creation of apoE -- knockout mice has changed the face of atherosclerosis research.

Influence of pre-operative ketoprofen administration (preemptive analgesia) on analgesic requirement and the level of prostaglandins in the early postoperative period

The aim of this study was to examine the effect of ketoprofen used in preemptive analgesia on the intensity of pain and requirement for analgesics in the perioperative period. Sixty patients scheduled for elective lumbar disc prolapse surgery were randomly divided into two groups. In the PRE group (n = 30) ketoprofen was administered one hour before incision. In the POST group ( n = 30) ketoprofen was used immediately after the surgery. The operation was performed under general anesthesia. Postoperative analgesia was realized by NCA (Nurse Controlled Analgesia) and the "required" dose of ketoprofen was 100 mg. After the operation, pain intensity was measured using visual-analog scale (VAS), ketoprofen requirements, the time to the first dose of ketoprofen, and levels of prostaglandin E(2) (PEG(2)) in blood serum were compared. There were no differences between the groups in the VAS pain scores, and levels of PGE(2) in blood serum. However, in patients of PRE group who had received preemptive analgesia, a significantly lower total consumption of ketoprofen, as compared with POST group, was observed between 12th and 36th postoperative hours. It was also found that the time which elapsed between the end of the operation and the first NCA activation was significantly shorter in the PRE group, as compared with the POST group. The results of our study confirm the possibility of modifying the nociception process in the perioperative period through preemptive analgesia by ketoprofen.

Nitric oxide and superoxide in inflammation and immune regulation

Nitric oxide (NO) and reactive oxygen species exert multiple modulating effects on inflammation and play a key role in the regulation of immune responses. They affect virtually every step of the development of inflammation. Low concentrations of nitric oxide produced by constitutive and neuronal nitric oxide synthases inhibit adhesion molecule expression, cytokine and chemokine synthesis and leukocyte adhesion and transmigration. Large amounts of NO, generated primarily by iNOS can be toxic and pro-inflammatory. Actions of nitric oxide are however not dependent primarily on the enzymatic source, but rather on the cellular context, NO concentration (dependent on the distance from NO source) and initial priming of immune cells. These observations may explain difficulties in determining the exact role of NO in Th1 and Th2 lymphocyte balance in normal immune responses and in allergic disease. Similarly superoxide anion produced by NAD(P)H oxidases present in all cell types participating in inflammation (leukocytes, endothelial and other vascular cells etc) may lead to toxic effects, when produced at high levels during oxidative burst, but may also modulate inflammation in a far more discrete way, when continuously produced at low levels by NOXs (non-phagocytic oxidases). The effects of both nitric oxide and superoxide in immune regulation are exerted through multiple mechanisms, which include interaction with cell signalling systems like cGMP, cAMP, G-protein, JAK/STAT or MAPK dependent signal transduction pathways. They may also lead to modification of transcription factors activity and in this way modulate the expression of multiple other mediators of inflammation. Moreover genetic polymorphisms exist within genes encoding enzymes producing both NO and superoxide. The potential role of these polymorphisms in inflammation and susceptibility to infection is discussed. Along with studies showing increasing role of NO and free radicals in mediating inflammatory responses drugs which interfere with these systems are being introduced in the treatment of inflammation. These include statins, angiotensin receptor blockers, NAD(P)H oxidase inhibitors, NO-aspirin and others. In conclusion in this mini-review we discuss the mechanisms of nitric oxide and superoxide dependent modulation of inflammatory reactions in experimental animals and humans. We also discuss potential roles of nitric oxide as a mediator of allergic inflammation.