Suppression of vascular transforming growth factor-beta1 and extracellular matrix gene expressions by cilazapril and nifedipine in hypertensive rats

Gene expression in peripheral blood of patients with hypertension and patients with type 2 diabetes

AIM

To evaluate the expression of atherosclerosis-associated genes in patients with hypertension and type 2 diabetes mellitus.

MATERIAL AND METHODS

Twenty-seven patients (14 men, 13 women), mean age 43.26 ± 11.69 years, were included in the study, which was divided into three groups: group 1 - patients with newly diagnosed hypertension and normal glucose tolerance (n = 9), group 2 - normotensive individuals with newly diagnosed type 2 diabetes (n = 9), and control group - normotensive individuals with normal glucose tolerance (n = 9). Gene expression analysis was performed with Human Atherosclerosis RT2 Profiler PCR Array.

RESULTS

In patients with hypertension, we found eight genes with increased expression - FABP3, FAS, FN1, IL1R2, LPL, SERPINE1, TGFB1, and VCAM1. Decreased expression was observed for two genes - SELPLG and SERPINEB2. In patients with type 2 diabetes we found seven up-regulated genes - APOE, BAX, MMP1, NFKB1, PDGFB, SPP1, and TGFB2, whereas no specifically down-regulated genes were observed. Three genes - KLF2, PDGFRB, and PPARD were found to be expressed only in groups 1 and 2.

CONCLUSION

Hypertension is associated with increased expression of FABP3, FAS, FN1, IL1R2, LPL, SERPINE1, TGFB1, and VCAM1 and decreased expression of SELPLG and SERPINEB2. The up-regulation of FAS, FN1, SERPINE1, TGFB1, and VCAM1 might be associated with an increased cardiovascular risk. Type 2 diabetes is associated with increased expression of APOE, BAX, MMP1, NFKB1, PDGFB, SPP1, and TGFB2. KLF2 and PPARD might be part of protective mechanisms that limit target organ damage in both disease conditions. Expression of PDGFRB might play an important role in the pathogenesis of both hypertension and type 2 diabetes.

Comparative study of the effects of lacidipine and enalapril on the left ventricular cardiomyocyte remodeling in spontaneously hypertensive rats

Antihypertensive medications are the most efficient drugs in achieving regression of myocardial hypertrophy in both clinical studies and animal models of hypertension. Nevertheless, there is a lack of clear and concise comparative study of their effects on the modulation of cardiomyocyte morphology and function. Here, we assessed the tissue-protective actions of 2 of these drugs, the calcium channel blocker lacidipine (3 mg/kg/day) and the angiotensin-converting enzyme-inhibitor enalapril (10 mg/kg/day) in vivo, after 8 weeks of treatment of 12-week-old spontaneously hypertensive rats, as well as in vitro, after short-term (4 min) application to isolated cardiomyocytes. Left ventricular hypertrophy (LVH) was compared at organ, tissue, and single-cell level. Our data showed that both drugs prevented the LVH of 20-week-old spontaneously hypertensive rats, but only lacidipine significantly decreased the cardiomyocyte size. Similarly, the single-cell contractility was significantly lowered in lacidipine-treated rats only. The effect of lacidipine was initiated shortly after exposure to the drug in a dose-dependent manner at 0.5 Hz, as well as at 2 Hz, with EC(50) of 10(-7) mol/L. These results can help in understanding the effects of these drugs on the prevention of LVH.

Pulmonary vascular remodeling: a target for therapeutic intervention in pulmonary hypertension

Pulmonary vascular remodelling is an important pathological feature of pulmonary hypertension, leading to increased pulmonary vascular resistance and reduced compliance. It involves thickening of all three layers of the blood vessel wall (due to hypertrophy and/or hyperplasia of the predominant cell type within each layer), as well as extracellular matrix deposition. Neomuscularisation of non-muscular arteries and formation of plexiform and neointimal lesions also occur. Stimuli responsible for remodelling involve transmural pressure, stretch, shear stress, hypoxia, various mediators [angiotensin II, endothelin (ET)-1, 5-hydroxytryptamine, growth factors, and inflammatory cytokines], increased serine elastase activity, and tenascin-C. In addition, there are reductions in the endothelium-derived antimitogenic substances, nitric oxide, and prostacyclin. Intracellular signalling mechanisms involved in pulmonary vascular remodelling include elevations in intracellular Ca2+ and activation of the phosphatidylinositol pathway, protein kinase C, and mitogen-activated protein kinase. In animal models of pulmonary hypertension, various drugs have been shown to attenuate pulmonary vascular remodelling. These include angiotensin-converting enzyme inhibitors, angiotensin receptor antagonists, ET receptor antagonists, ET-converting enzyme inhibitors, nitric oxide, phosphodiesterase 5 inhibitors, prostacyclin, Ca2+ -channel antagonists, heparin, and serine elastase inhibitors. Inhibition of remodelling is generally accompanied by reductions in pulmonary artery pressure. The efficacy of some of the drugs varies, depending on the animal model of the disease. In view of the complexity of the remodelling process and the diverse aetiology of pulmonary hypertension in humans, it is to be anticipated that successful anti-remodelling therapy in the clinic will require a range of different drug options.

Effect of calcium channel blockers on proteoglycan synthesis by vascular smooth muscle cells and low density lipoprotein--proteoglycan interaction

Calcium channel blockers are known to retard atherosclerosis. In this study, we tested the hypothesis that one mechanism by which calcium channel blockers retard atherosclerosis is through the modulation of proteoglycan metabolism by vascular smooth muscle cells. We investigated the effect of amlodipine and nifedipine on proteoglycan synthesis by human aortic smooth muscle cells and the ability of the newly synthesized proteoglycans to bind low density lipoprotein (LDL). Confluent smooth muscle cells were incubated with [(35)S]sulfate alone or [(35)S]sulfate and [(3)H]leucine in the presence and absence of different concentrations of amlodipine and nifedipine (0.1--20 microg/ml) for 24 h, and newly synthesized proteoglycans were analyzed. Both amlodipine and nifedipine inhibited proteoglycan synthesis by smooth muscle cells in a dose-dependent manner; however, amlodipine was significantly more potent than nifedipine in this regard. In the presence of 20 microg/ml amlodipine, media and cellular proteoglycans decreased by 56%. This was due to inhibition of de novo proteoglycan synthesis by amlodipine. Compared with the proteoglycans synthesized by control smooth muscle cells, those synthesized by cells exposed to amlodipine were smaller and less sulfated, and contained fewer glycosaminoglycan chains. In addition, proteoglycans synthesized by cells treated with amlodipine bound LDL with low affinity. These results suggest that amlodipine may protect against atherosclerosis through a proteoglycan-mediated mechanism.

Phorbol ester-induced U-937 differentiation: effects on integrin alpha(5) gene transcription

Lung injury is accompanied by increased deposition of fibronectin (FN) matrices. Activated monocytic cells recruited to sites of lung injury express integrin receptors for FN that mediate their interaction with this matrix. One such integrin, alpha(5)beta(1), mediates many of the biological effects of FN, and its expression may be important for immune cell function at sites of lung injury. Herein, we examine the expression of alpha(5)beta(1) in response to the tumor promoter phorbol 12-myristate 13-acetate (PMA) in the human promonocytic cell line U-937. We demonstrate that PMA enhanced the adherence of U-937 cells to FN by increasing the expression of both the alpha(5)- and beta(1)-subunit mRNAs and the surface expression of the protein. In U-937 cells transfected with an alpha(5) promoter-reporter gene, we found that PMA induced the transcription of the alpha(5) gene by acting on very specific promoter sequences other than activator protein-1 in a protein kinase C-dependent manner. Lipopolysaccharide had a similar effect. Modulation of alpha(5)beta(1) expression may be important for regulation of monocytic cell function in lung inflammation after injury.

Differentiation of coronary smooth muscle cells to a cell cycle-arrested hypertrophic growth status by a synthetic non-toxic heparin-mimicking compound

Studies on the mode of action of basic fibroblast growth factor (bFGF) identified an essential role of heparan sulfate and heparin-like molecules in the formation of distinct bFGF-heparan sulfate-bFGF-receptor complexes that are required for bFGF-induced signal transduction. In coronary smooth muscle cells that express 6-8 ng bFGF mg(-1) cell protein, the heparan sulfate chains of membrane-associated proteoheparan sulfate are implicated in bFGF signaling and thus are involved in the regulation of proliferation and differentiation of vascular smooth muscle cells. We studied the mode of action of a synthetic non-sulfated heparin-mimicking compound termed RG-13,577 (poly-4-hydroxyphenoxy acetic acid, Mr approximately 5 kD) and found a dose-dependent antiproliferative effect that was characterized by a block of G(1)/S-phase transition indicated by a marked (80%) reduction of [3H]thymidine incorporation at a concentration of 5 microg ml(-1) RG-13,577. Cell cycle analysis showed a block of cell division in the G(1)-phase. In response to RG-13,577 the cells were converted into a hypertrophic growth status within 72 h as judged from a doubling of the cellular protein content and measurement of cell and nucleus size. The increased cell protein content resulted from a de novo synthesis and was also associated with an increase in the incorporation of [35S]sulfate into cell-associated proteoglycans, including the proteoheparan sulfate coreceptor of bFGF. In contrast, the compound-induced G(1)-phase arrest was associated with an extensive downregulation of the cellular and pericellular bFGF level. The reduced bFGF content was accompanied by downregulation of the bFGF signaling-involved protein kinase C-alpha and MAP kinase, abrogation of MAP kinase phosphorylation and overexpression of protein kinase C-gamma. RG-13,577 failed to elicit apoptotic reactions at a concentration range of 0.5-10 microg ml(-1) and its effect was reversible upon removal of the compound. It appears that RG-13,577 induces a phenotype transformation of coronary SMC into a metabolically active hypertrophic status that could promote repair processes after balloon angioplasty (PTCA) without stimulating cell proliferation. Development of non-toxic polyanionic compounds may provide an effective strategy to inhibit cell proliferation associated with restenosis following balloon angioplasty and coronary artery bypass surgery.

Differential modes of regulation of interleukin-1beta expression by extracellular matrices

Extracellular matrices (ECMs) can stimulate human monocytic cells to express interleukin-1beta (IL-1beta), a proinflammatory cytokine implicated in the regulation of tissue inflammation. In this study, we explored the intracellular mechanisms responsible for ECM induction of IL-1beta using human promonocytic U937 cells transfected with the full-length human IL-1beta gene promoter connected to a reporter gene. Using this system, we demonstrated that the ECM molecules fibronectin (FN), type I collagen (Coll), fibrin (Fb) and laminin (Lm) induced transcription of the IL-1beta gene (which was associated with a modest increase in IL-1beta protein secretion) in suspended cells, when used in their soluble monomeric form. This effect was mimicked or blocked by anti-integrin monoclonal antibodies (mAbs) and was dependent on the activation of protein kinase C (PKC). Three of the ECMs tested (FN, Coll and Fb) induced the activation of mitogen-activated protein kinases (MAPKs), whereas Lm had no effect. FN, Coll and Fb (but not Lm) also induced DNA binding of the transcription factor activator protein-1 (AP-1), but not that of nuclear factor-kappaB. Co-transfection of U937 cells with a competing AP-1 oligomer blocked the IL-1beta response induced by FN, but not that induced by the other ECMs. By inhibiting AP-1 translocation, glucocorticoids also blocked the FN-induced response, but not that of the other ECMs. These studies suggest that the signalling pathways which mediate ECM induction of IL-1beta expression in human monocytic cells converge at the level of PKC activation. However, they diverge in other aspects, as demonstrated by the differential activation of MAPKs and the need for diverse transcription factors.

Lacidipine reduces high blood pressure and the target organ damage induced by high fructose diet in rats

OBJECTIVE

Normotensive rats fed a high fructose diet (HFD) develop hypertriglyceridemia, hyperinsulinemia and hypertension. The glomerular changes observed in the kidneys of these animals are similar to those observed in diabetic rats. The aim of this study was to evaluate whether lacidipine could be effective not only in preventing, but also in inducing the regression of hypertension, and renal and cardiac damage in rats fed HFD.

METHODS

Thirty male Wistar-Kyoto (WKY) rats received HFD for 1 month; thereafter, five rats were sacrificed (Group 1) and the other 25 rats were divided into three groups: Group 2 (five rats) received HFD plus placebo, Group 3 (10 rats) HFD plus lacidipine 3 mg/kg per day, and Group 4 (10 rats) HFD plus hydralazine 10 mg/kg per day. At the end of the second month all animals were sacrificed. Kidneys and hearts were immediately removed. Renal deposits of collagen I, collagen IV, fibronectin and cardiac deposits of collagen III were assessed by means of immunohistochemistry.

RESULTS

In the rats receiving HFD plus placebo, blood pressure was increased after the first and the second month of diet. This increase was reversed by lacidipine and hydralazine but, although both drugs normalized blood pressure, only lacidipine was effective in reducing renal and cardiac damage.

CONCLUSIONS

These data suggest that lacidipine is effective in reversing hypertension and reducing target organ damage induced by HFD. Moreover, this protective effect on target organs appears to be not simply a consequence of blood pressure reduction, but seems to be connected to the type of hypotensive drug administered.

Effects of amlodipine on gene expression and extracellular matrix formation in human vascular smooth muscle cells and fibroblasts: implications for vascular protection

Vascular smooth muscle cells (VSMC) are involved in the pathogenesis of hypertension and coronary artery disease. Amlodipine, a calcium channel blocker of the dihydropyridine type, is widely used in the therapy of these diseases, and has been shown to reduce the progression of the underlying pathophysiological mechanisms, such as atherosclerosis and restenosis. Research on the impact of calcium channel blockers on cell behavior has revealed an antiproliferative effect on VSMC. Cell proliferation is tightly controlled by permanent interaction of cells with their surrounding microenvironment, the extracellular matrix (ECM). The ECM is subjected to a continuous turnover and implicated in (i) stabilization and compartmentalization of tissue architecture and (ii) local binding and preservation of growth factors and cytokines. These growth factors and cytokines can be released during degradation of the ECM, and can function as local inflammatory factors without de novo synthesis. In this context, we assessed the effects of amlodipine on the composition of the ECM and related factors. We investigated the effects of amlodipine on (i) the regulation of cellular cholesterol metabolism, (ii) the activation of genes encoding for inflammatory factors, (iii) gene expression and turnover of ECM compounds, and (iv) the activity of matrix-degrading enzymes. Most of these effects of calcium channel blockers require direct induction of gene expression. In this respect, we demonstrate that amlodipine increases expression of the cytokine interleukin-6 by directly activating the respective gene promoter in human VSMC.