Angiotensin, inflammation, hypertension, and cardiovascular disease

A small erythropoietin derived non-hematopoietic peptide reduces cardiac inflammation, attenuates age associated declines in heart function and prolongs healthspan

Background

Aging is associated with increased levels of reactive oxygen species and inflammation that disrupt proteostasis and mitochondrial function and leads to organism-wide frailty later in life. ARA290 (cibinetide), an 11-aa non-hematopoietic peptide sequence within the cardioprotective domain of erythropoietin, mediates tissue protection by reducing inflammation and fibrosis. Age-associated cardiac inflammation is linked to structural and functional changes in the heart, including mitochondrial dysfunction, impaired proteostasis, hypertrophic cardiac remodeling, and contractile dysfunction. Can ARA290 ameliorate these age-associated cardiac changes and the severity of frailty in advanced age?

Methods

We conducted an integrated longitudinal (n = 48) and cross-sectional (n = 144) 15 months randomized controlled trial in which 18-month-old Fischer 344 x Brown Norway rats were randomly assigned to either receive chronic ARA290 treatment or saline. Serial echocardiography, tail blood pressure and body weight were evaluated repeatedly at 4-month intervals. A frailty index was calculated at the final timepoint (33 months of age). Tissues were harvested at 4-month intervals to define inflammatory markers and left ventricular tissue remodeling. Mitochondrial and myocardial cell health was assessed in isolated left ventricular myocytes. Kaplan-Meier survival curves were established. Mixed ANOVA tests and linear mixed regression analysis were employed to determine the effects of age, treatment, and age-treatment interactions.

Results

Chronic ARA290 treatment mitigated age-related increases in the cardiac non-myocyte to myocyte ratio, infiltrating leukocytes and monocytes, pro-inflammatory cytokines, total NF-κB, and p-NF-κB. Additionally, ARA290 treatment enhanced cardiomyocyte autophagy flux and reduced cellular accumulation of lipofuscin. The cardiomyocyte mitochondrial permeability transition pore response to oxidant stress was desensitized following chronic ARA290 treatment. Concurrently, ARA290 significantly blunted the age-associated elevation in blood pressure and preserved the LV ejection fraction. Finally, ARA290 preserved body weight and significantly reduced other markers of organism-wide frailty at the end of life.

Conclusion

Administration of ARA290 reduces cell and tissue inflammation, mitigates structural and functional changes within the cardiovascular system leading to amelioration of frailty and preserved healthspan.

Ascorbic Acid: A New Player of Epigenetic Regulation in LPS-gingivalis Treated Human Periodontal Ligament Stem Cells

Periodontitis is usually sustained from microorganism of oral cavity, like Porphyromonas gingivalis (P. gingivalis). Periodontal disease is an infectious disease that afflicts a large number of people. Researches are investigating on the mesenchymal stem cells (MSCs) response to inflammatory events in combination with antioxidant substances. In particular, ascorbic acid (AA) increased cell proliferation, upregulated the cells pluripotency marker expression, provide a protection from inflammation, and induced the regeneration of periodontal ligament tissue. The purpose of the present research was to investigate the effects of AA in primary culture of human periodontal ligament stem cells (hPDLSCs) exposed to P. gingivalis lipopolysaccharide (LPS-G). The effect of AA on hPDLSCs exposed to LPS-G was determined through the cell proliferation assay. The molecules involved in the inflammatory pathway and epigenetic regulation have been identified using immunofluorescence and Western blot analyses. miR-210 level was quantified by qRT-PCR, and the ROS generation was finally studied. Cells co-treated with LPS-G and AA showed a restoration in terms of cell proliferation. The expression of NFκB, MyD88, and p300 was upregulated in LPS-G exposed cells, while the expression was attenuated in the co-treatment with AA. DNMT1 expression is attenuated in the cells exposed to the inflammatory stimulus. The level of miR-210 was reduced in stimulated cells, while the expression was evident in the hPDLSCs co-treated with LPS-G and AA. In conclusion, the AA could enhance a protective effect in in vitro periodontitis model, downregulating the inflammatory pathway and ROS generation and modulating the miR-210 level.

Insulin Resistance the Hinge Between Hypertension and Type 2 Diabetes

Epidemiological studies have documented a high incidence of diabetes in hypertensive patients.Insulin resistance is defined as a less than expected biologic response to a given concentration of the hormone and plays a pivotal role in the pathogenesis of diabetes. However, over the last decades, it became evident that insulin resistance is not merely a metabolic abnormality, but is a complex and multifaceted syndrome that can also affect blood pressure homeostasis. The dysregulation of neuro-humoral and neuro-immune systems is involved in the pathophysiology of both insulin resistance and hypertension. These mechanisms induce a chronic low grade of inflammation that interferes with insulin signalling transduction. Molecular abnormalities associated with insulin resistance include the defects of insulin receptor structure, number, binding affinity, and/or signalling capacity. For instance, hyperglycaemia impairs insulin signalling through the generation of reactive oxygen species, which abrogate insulin-induced tyrosine autophosphorylation of the insulin receptor. Additional mechanisms have been described as responsible for the inhibition of insulin signalling, including proteasome-mediated degradation of insulin receptor substrate 1/2, phosphatase-mediated dephosphorylation and kinase-mediated serine/threonine phosphorylation of both insulin receptor and insulin receptor substrates. Insulin resistance plays a key role also in the pathogenesis and progression of hypertension-induced target organ damage, like left ventricular hypertrophy, atherosclerosis and chronic kidney disease. Altogether these abnormalities significantly contribute to the increase the risk of developing type 2 diabetes.

Deletion of protein kinase B2 preserves cardiac function by blocking interleukin-6-mediated injury and restores blood pressure during angiotensin II/high-salt-diet-induced hypertension

OBJECTIVE

Protein kinase B2 (AKT2) is implicated in cardiomyocyte survival during various stress conditions. However, the role of AKT2 in heart function, cardiac hypertrophy and blood pressure (BP) control during hypertension is not fully understood. Therefore, we sought to determine whether the deletion of AKT2 protects cardiac function during angiotensin II/high-salt-diet (AngII/HSD) treatment and find out the signaling pathway.

METHODS

Male C57BL/6J (wild type), AKT2 knockout and interleukin (IL)-6 knockout mice were fed a 4% NaCl diet for 5 weeks. In the last week, mice were split in two groups and infused subcutaneously with either vehicle or AngII (1.5 μg/h per mouse) for 1 week. Then, BP and cardiac function were assessed. Immunohistology of IL-6 and monocyte chemoattractant protein 1 was performed to detect inflammation in the heart. Masson's trichrome staining was performed to evaluate cardiac fibrosis. Heart tissue homogenates and neonatal mice cardiomyocytes were collected to analyze oxidative stress.

RESULTS

Compared with wild-type mice, AKT2 knockout mice maintained BP and showed better left ventricle ejection fraction, lower level of fibrosis, reduced oxidative stress, reduced IL-6 expression and less macrophage infiltration, when treated with AngII/HSD. IL-6 knockout mice treated with AngII/HSD also showed alleviated left ventricular function, fibrosis, oxidative stress and macrophage infiltration compared with wild type.

CONCLUSION

AKT2 deficiency prevents the development of AngII/HSD-induced hypertension, cardiac dysfunction and myocardial injury including oxidative stress, fibrosis and inflammation by suppressing IL-6 expression. These data reveal an important role of the AKT2-IL-6 pathway in mediating AngII/HSD-induced hypertension and cardiomyopathy.

Mechanisms of isolevuglandin-protein adduct formation in inflammation and hypertension

Inflammation has been implicated in the pathogenesis of hypertension and recent evidence suggests that isolevuglandin (IsoLG)-protein adducts play a role. Several hypertensive stimuli contribute to formation of IsoLG-protein adducts including excess dietary salt and catecholamines. The precise intracellular mechanisms by which these hypertensive stimuli lead to IsoLG-protein adduct formation are still not well understood; however, there is now evidence implicating NADPH-oxidase derived reactive oxygen species (ROS) in this process. ROS oxidize arachidonic acid leading to formation of IsoLGs, which non-covalently adduct to lysine residues and alter protein structure and function. Recent studies suggest that these altered proteins act as neo-antigens leading to an autoimmune state that results in hypertension. The goal of this mini-review is to highlight some of the hypertensive stimuli and the mechanisms contributing to IsoLG-protein adduct formation leading to inflammation and hypertension.

Angiotensin II-induced Hypertension is Reduced by Deficiency of P-selectin Glycoprotein Ligand-1

Identification of inflammatory mediators that regulate the vascular response to vasopressor molecules may aid in the development of novel therapeutic agents to treat or prevent hypertensive vascular diseases. Leukocytes have recently been shown to be capable of modifying blood pressure responses to vasopressor molecules. The purpose of this study was to test the hypothesis that deficiency of the leukocyte ligand, Psgl-1, would reduce the pressor response to angiotensin II (Ang II). Mice deficient in Psgl-1 (Psgl-1^−/−) along with wild-type (WT) controls were treated for 2 weeks with a continuous infusion of Ang II. No differences in blood pressure between the groups were noted at baseline, however after 5 days of Ang II infusion, systolic blood pressures were higher in WT compared to Psgl-1^−/− mice. The pressor response to acute administration of high dose Ang II was also attenuated in Psgl-1^−/− compared to WT mice. Chimeric mice with hematopoietic deficiency of Psgl-1 similarly showed a reduced pressor response to Ang II. This effect was associated with reduced plasma interleukin-17 (IL-17) levels in Psgl-1^−/− mice and the reduced pressor response was restored by administration of recombinant IL-17. In conclusion, hematopoietic deficiency of Psgl-1 attenuates Ang II-induced hypertension, an effect that may be mediated by reduced IL-17.

Quercetin and Vitamin C Mitigate Cobalt Chloride-Induced Hypertension through Reduction in Oxidative Stress and Nuclear Factor Kappa Beta (NF-Kb) Expression in Experimental Rat Model

The objective of the present work was to evaluate the toxic effects of cobalt chloride, a potent oxidative stress-inducing chemical, at 650 ppm in rats and the protective effect of quercetin and/or vitamin C against the cobalt chloride-induced toxicity. Thirty rats were randomly selected, and assigned to one of five groups: control, cobalt chloride, cobalt chloride + quercetin, cobalt chloride + vitamin C and cobalt chloride + quercetin + vitamin C. The exposure of rats to cobalt chloride led to a significant increase (p < 0.05) in malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) generated, but decreased nitric oxide (NO) bioavailability. Also, significant (p < 0.05) reductions were observed in the activity of glutathione peroxidase (GPx) and reduced glutathione (GSH) content in the cardiac and renal tissues. Treatment with quercetin and vitamin C reversed the effect of cobalt chloride on MDA, H₂O₂ and NO, more potently than with either of the two antioxidants, and increased the antioxidant defence system. Further, treatment of rats with quercetin and vitamin C in combination resulted in significant (p < 0.05) decreases in the systolic, diastolic, and mean arterial blood pressure of rats, relative to those exposed to cobalt chloride alone. Immunohistochemical studies revealed a greater expression of nuclear factor kappa beta (NF-kB) in the cobalt chloride group compared with the control- and antioxidants-treated rats. The results of this study suggest a protective role for quercetin and vitamin C in the amelioration of the toxic mechanisms leading to cobalt chloride-induced hypertension and its associated cardiac and renal complications in rats.

A Brief Introduction into the Renin-Angiotensin-Aldosterone System: New and Old Techniques

The renin-angiotensin-aldosterone system (RAAS) is a complex system of enzymes, receptors, and peptides that help to control blood pressure and fluid homeostasis. Techniques in studying the RAAS can be difficult due to such factors as peptide/enzyme stability and receptor localization. This paper gives a brief account of the different components of the RAAS and current methods in measuring each component. There is also a discussion of different methods in measuring stem and immune cells by flow cytometry, hypertension, atherosclerosis, oxidative stress, energy balance, and other RAAS-activated phenotypes. While studies on the RAAS have been performed for over 100 years, new techniques have allowed scientists to come up with new insights into this system. These techniques are detailed in this Methods in Molecular Biology Series and give students new to studying the RAAS the proper controls and technical details needed to perform each procedure.

Antihypertensive treatment decreases arterial stiffness at night but not during the day. Results from the Hypertension in the Very Elderly Trial

The main Hypertension in the Very Elderly Trial (HYVET) demonstrated a very marked reduction in cardiovascular events by treating hypertensive participants 80 years or older with a low dose, sustained release prescription of indapamide (indapamide SR, 1.5 mg) to which was added a low dose of an angiotensin converting enzyme inhibitor in two-thirds of cases (perindopril 2-4 mg). This report from the ambulatory blood pressure sub-study investigates whether changes in arterial stiffness and ambulatory blood pressure (BP) could both explain the benefits observed in the main trial. A total of 139 participants were randomized to placebo [67] and to active treatment [72] and had both day and night observations of BP and arterial stiffness as determined from the Q wave Korotkoff diastolic (QKD) interval. The QKD interval was 5.6 ms longer (p = 0.017) in the actively treated group at night than in the placebo group. This was not true for the more numerous daytime readings so that 24-h results were similar in the two groups. The QKD interval remained longer at night in the actively treated group even when adjusted for systolic pressure, heart rate and height. The reduced arterial stiffness at night may partly explain the marked benefits observed in the main trial.

Inflammatory Markers in Primary Aldosteronism

Primary aldosteronism (PA) is the most common cause of endocrine hypertension with a high frequency of cardiovascular complications. The unfavorable cardiometabolic profile may be due to aldosterone-mediated activation of inflammatory cells, circulatory cytokines and activation of collagen synthesis in the vessel wall. Aim of our study was to evaluate differences in the levels of hsCRP, IL-6, TNF-α and N-terminal propeptide of collagen I (PINP) in patients with PA and essential hypertension (EH) as a control group, and between the subtypes of PA (aldosterone producing adenoma – APA, idiopathic hyperaldosteronism – IHA). We studied 28 patients with PA (IHA – 10 patients, APA – 12 patients, 6 unclassified) and 28 matched patients with EH. There were no differences in the levels of inflammatory markers between the followed groups [EH vs. PA: TNF-α (5.09 [3.68-6.32] vs. 4.84 [3.62-6.50] pg/ml), IL-6 (0.94 [0.70-1.13] vs. 0.97 [0.71-1.28] pg/ml), hsCRP (0.53 [0.25-1.54] vs. 0.37 [0.31-0.61] mg/l), leukocytes (6.35±1.42 vs. 5.97±1.29 109 l); APA vs. IHA: TNF-α (4.54 [3.62-7.03] vs. 5.19 [4.23-5.27] pg/ml), IL-6 (0.96 [0.63-1.21] vs. 0.90 [0.65-1.06] pg/ml), hsCRP (0.34 [0.29-0.47] vs. 0.75 [0.36-1.11] mg/l), leukocytes (6.37±1.41 vs. 5.71±1.21 109 l)]. Significant differences in the levels of PINP between PA and EH group were observed (35.18 [28.46-41.16] vs. 45.21 [36.95-62.81] μg/l, p≤0.003). No differences in inflammatory markers were observed between the followed groups, we confirmed higher levels of PINP in patients with PA.

Role and therapeutic potential of G-protein coupled receptors in breast cancer progression and metastases

G-protein-coupled receptors (GPCRs) comprise a large family of cell-surface receptors, which have recently emerged as key players in tumorigenesis, angiogenesis and metastasis. In this review, we discussed our current understanding of the many roles played by GPCRs in general, and particularly Angiotensin II type I receptor (AGTR1), a member of the seven-transmembrane-spanning G-protein coupled receptor superfamily, and its significance in breast cancer progression and metastasis. We have also discussed different strategies for targeting AGTR1, and its ligand Angiotension II (Ang II), which might unravel unique opportunities for breast cancer prevention and treatment. For example, AGTR1 blockers (ARBs) which are already in clinical use for treating hypertension, merit further investigation as a therapeutic strategy for AGTR1-positive cancer patients and may have the potential to prevent Ang II-AGTR1 signalling mediated cancer pathogenesis and metastases.

High-fat diet- and angiotensin II-induced aneurysm concurrently elicits splenic hypertrophy

BACKGROUND

Angiotensin II (Ang II) and high-fat diet are implicated in causing pathological changes in the vascular endothelium, brain, kidney and liver. The association of aneurysm leading to histopathological changes in the splenic compartment remains elusive. Further, the salubrious credentials of antioxidants, especially α-tocopherol and β-carotene in the resolution of splenic pathology have not been investigated.

METHODS

Four-month-old Apoe(-/-) mice were used in the induction of aneurysm by infusing Ang II, and subsequently were orally administered with α-tocopherol and β-carotene-enriched diet for 60 days.

RESULTS

We observed splenomegaly in Ang II-infused aneurysm and high-fat diet-supplemented mice as compared to normal mice. These observations were further confirmed through histopathological investigations, demonstrating splenic follicular hypertrophy. We observed a remarkable decrease in the size of spleen in α-tocopherol and β-carotene-treated Apoe(-/-) mice as compared with Ang II-treated animals. Furthermore, no marked changes in the histopathological splenic sections were seen in the β-carotene-treated group. However, hyperplasia and proliferation of immature lymphocytes in the follicles were observed in the α-tocopherol-treated animals. We found that CD4+ T-cell levels were increased in the high-fat diet group relative to the control group and were decreased in the β-carotene-treated animals.

CONCLUSIONS

Our study provides evidence that Ang II infusion and high-fat supplementation induces abdominal aortic aneurysm that has pathological implications to the spleen. The use of β-carotene but not α-tocopherol as an antioxidant markedly ameliorates the pathological changes in spleen.

Positioning of inflammatory biomarkers in the heart failure landscape

The clinical syndrome of heart failure is characterized by a systemic inflammatory response that contributes to end organ damage in the heart and circulation and can thus lead to worsening heart failure. The ensemble of inflammatory mediators that have been detected in heart failure patients include pro-inflammatory cytokines and their cognate receptors, as well as molecules secreted/released by macrophages (galectin-3 and pentraxin-3). Inflammatory biomarkers correlate with disease severity and prognosis across the broad spectrum of heart failure syndromes. Given the proliferation of new biomarkers that predict disease severity and prognosis in heart failure, it is reasonable to ask whether there is a current role for measuring inflammatory mediators in heart failure. This review will attempt to address this question, as well as review several novel approaches that have utilized inflammatory biomarkers to enhance risk stratification and prognosis in heart failure patients.

Upregulation of junctional adhesion molecule-A is a putative prognostic marker of hypertension

Aims

Establishing biochemical markers of pre-hypertension and early hypertension could help earlier diagnostics and therapeutic intervention. We assess dynamics of junctional adhesion molecule-A (JAM-A) expression in rat models of hypertension and test whether JAM-A expression could be driven by angiotensin (ANG) II and whether JAM-A contributes to the progression of hypertension. We also compare JAM-A expression in normo- and hypertensive humans.

Methods and results

In pre-hypertensive and spontaneously hypertensive rats (SHRs), JAM-A protein was overexpressed in the brainstem microvasculature, lung, liver, kidney, spleen, and heart. JAM-A upregulation at early and late stages was even greater in the stroke-prone SHR. However, JAM-A was not upregulated in leucocytes and platelets of SHRs. In Goldblatt 2K-1C hypertensive rats, JAM-A expression was augmented before any increase in blood pressure, and similarly JAM-A upregulation preceded hypertension caused by peripheral and central ANG II infusions. In SHRs, ANG II type 1 (AT₁) receptor antagonism reduced JAM-A expression, but the vasodilator hydralazine did not. Body-wide downregulation of JAM-A with Vivo-morpholinos in juvenile SHRs delayed the progression of hypertension. In the human saphenous vein, JAM-A mRNA was elevated in hypertensive patients with untreated hypertension compared with normotensive patients but reduced in patients treated with renin–angiotensin system antagonists.

Conclusion

Body-wide upregulation of JAM-A in genetic and induced models of hypertension in the rat precedes the stable elevation of arterial pressure. JAM-A upregulation may be triggered by AT₁ receptor-mediated signalling. An association of JAM-A with hypertension and sensitivity to blockers of ANG II signalling were also evident in humans. We suggest a prognostic and possibly a pathogenic role of JAM-A in arterial hypertension.

Comparative effects of angiotensin-converting enzyme inhibition and angiotensin-receptor blockade on inflammation during hemodialysis

Biomarkers of oxidative stress and inflammation predict cardiovascular events in maintenance hemodialysis patients. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin-receptor blockers (ARBs) reduce cardiovascular mortality in the general population, but their benefit in maintenance hemodialysis patients is not fully explored. To test whether ACE inhibitors and ARBs differentially affect markers of oxidative stress, inflammation, and fibrinolysis during hemodialysis, we conducted a randomized, double-blind, placebo-controlled 3×3 crossover study. We randomly assigned 15 participants undergoing hemodialysis to placebo, ramipril (5 mg/d), and valsartan (160 mg/d) for 7 days, with a washout period of 3 weeks in between the treatments. On the morning of the seventh day of drug treatment, participants underwent serial blood sampling during hemodialysis. Neither ramipril nor valsartan affected BP during hemodialysis. Ramipril increased IL-1β concentrations (P=0.02) and decreased IL-10 concentrations (P=0.04) compared with placebo. Valsartan and ramipril both lowered IL-6 levels during dialysis (P<0.01 for each compared with placebo). Valsartan increased F(2)-isoprostane levels, and ramipril suggested a similar trend (P=0.09). Valsartan and ramipril both lowered D-dimer levels (P<0.01 for both), whereas only ramipril seemed to prevent a rise in vWf levels (P=0.04). In summary, during hemodialysis, valsartan induces a greater anti-inflammatory effect compared with ramipril, although ramipril seems to prevent dialysis-induced endothelial dysfunction as measured by levels of vWf. A prospective clinical trial is necessary to determine whether ACE inhibitors and ARBs also differ with respect to their effects on cardiovascular mortality in this population.

The effect of an Angiotensin receptor blocker on arterial stiffness in type 2 diabetes mellitus patients with hypertension

BACKGROUND

Hypertension and type 2 diabetes mellitus are major risk factors for cardiovascular disease. This study analyzed the changes in central aortic waveforms and pulse wave velocity as well as related parameters after treatment with valsartan, an angiotensin II type 1 receptor blocker, in patients with type 2 diabetes and hypertension.

METHODS

We used pulse wave analysis to measure central aortic waveform in a total of 98 subjects. In 47 of these patients, pulse wave velocity measurements were obtained before and after 12 weeks of treatment with valsartan.

RESULTS

In the central aortic waveform analysis, the aortic pulse pressure and augmentation index were significantly decreased after valsartan treatment, as was the aortic pulse wave velocity. Factors contributing to the improvement in pulse wave velocity were the fasting blood glucose and haemoglobin A1c levels.

CONCLUSION

Short-term treatment with valsartan improves arterial stiffness in patients with type 2 diabetes and hypertension, and the glucose status at baseline was associated with this effect.

Critical appraisal of the differential effects of antihypertensive agents on arterial stiffness

Increased central arterial stiffness, involving accelerated vascular ageing of the aorta, is a powerful and independent risk factor for early mortality and provides prognostic information above and beyond traditional risk factors for cardiovascular disease (CVD). Central arterial stiffness is an important determinant of pulse pressure; therefore, any pathological increase may result in left ventricular hypertrophy and impaired coronary perfusion. Central artery stiffness can be assessed noninvasively by measurement of aortic pulse wave velocity, which is the gold standard for measurement of arterial stiffness. Earlier, it was believed that changes in arterial stiffness, which are primarily influenced by long-term pressure-dependent structural changes, may be slowed but not reversed by pharmacotherapy. Recent studies with drugs that inhibit the renin-angiotensin-aldosterone system, advanced glycation end products crosslink breakers, and endothelin antagonists suggest that blood pressure (BP)-independent reduction and reversal of arterial stiffness are feasible. We review the recent literature on the differential effect of antihypertensive agents either as monotherapy or combination therapy on arterial stiffness. Arterial stiffness is an emerging therapeutic target for CVD risk reduction; however, further clinical trials are required to confirm whether BP-independent changes in arterial stiffness directly translate to a reduction in CVD events.

Pentosan polysulfate treatment preserves renal autoregulation in ANG II-infused hypertensive rats via normalization of P2X1 receptor activation

Inflammatory factors are elevated in animal and human subjects with hypertension and renal injury. We hypothesized that inflammation contributes to hypertension-induced renal injury by impairing autoregulation and microvascular reactivity to P2X(1) receptor activation. Studies were conducted in vitro using the blood-perfused juxtamedullary nephron preparation. Rats receiving ANG II (60 ng/min) infusion were treated with the anti-inflammatory agent pentosan polysulfate (PPS) for 14 days. The magnitude and progression of hypertension were similar in ANG II and ANG II+PPS-treated rats (169 ± 5 vs. 172 ± 2 mmHg). Afferent arterioles from control rats exhibited normal autoregulatory behavior with diameter decreasing from 18.4 ± 1.6 to 11.4 ± 1.7 μm when perfusion pressure was increased from 70 to 160 mmHg. In contrast, pressure-mediated vasoconstriction was markedly attenuated in ANG II-treated rats, and diameter remained essentially unchanged over the range of perfusion pressures. However, ANG II-treated rats receiving PPS exhibited normal autoregulatory behavior compared with ANG II alone rats. Arteriolar reactivity to ATP and β,γ-methylene ATP was significantly reduced in ANG II hypertensive rats compared with controls. Interestingly, PPS treatment preserved normal reactivity to P2 and P2X(1) receptor agonists despite the persistent hypertension. The maximal vasoconstriction was 79 ± 3 and 81 ± 2% of the control diameter for ATP and β,γ-methylene ATP, respectively, similar to responses in control rats. PPS treatment significantly reduced α-smooth muscle actin staining in afferent arterioles and plasma transforming growth factor-β1 concentration in ANG II-treated rats. In conclusion, PPS normalizes autoregulation without altering ANG II-induced hypertension, suggesting that inflammatory processes reduce P2X(1) receptor reactivity and thereby impair autoregulatory behavior in ANG II hypertensive rats.

Inflammation in lone atrial fibrillation

OBJECTIVES

This study was designed to evaluate the correlation between lone atrial fibrillation and inflammation.

METHODS

A total of 411 subjects were enrolled in this study, including 333 patients with lone atrial fibrillation, and 78 controls. C-reactive protein (CRP) and echocardiography were evaluated, and the electrocardiograph was monitored to identify cardiac rhythm at the time of blood sampling. According to the rhythm, paroxysmal atrial fibrillation was divided into presence and absence of atrial fibrillation.

RESULTS

Subjects with lone atrial fibrillation had higher CRP levels than controls (media, 1.00 mg/L; IQR, 1.00-2.54 versus media, 1.00 mg/L; IQR, 1.00-1.55; p = 0.016) and subjects with persistent atrial fibrillation had higher CRP levels than those with paroxysmal atrial fibrillation (media, 1.62 mg/L; IQR, 1.00-3.98 versus media, 1.00 mg/L, IQR, 1.00-2.10; p = 0.022), and so did presence of atrial fibrillation rather than absence of atrial fibrillation (media, 2.11 mg/L; IQR, 1.00-3.60 versus media, 1.00 mg/L; IQR, 1.00-1.76; p = 0.000) in paroxysmal atrial fibrillation. However, there was no significant difference in CRP levels between persistent atrial fibrillation and presence of atrial fibrillation in paroxysmal atrial fibrillation (p = 0.992). Neither was there any difference between absence of atrial fibrillation in paroxysmal atrial fibrillation and controls (p = 0.483). In patients with lone atrial fibrillation, atrial fibrillation rhythm (B = 4.85, 95%CI: 2.61-8.99) was the only independent predictor of elevated CRP levels after adjusted covariants.

CONCLUSIONS

Patients with lone atrial fibrillation had elevated CRP levels only when they were in atrial fibrillation rhythm and an elevated CRP level was not related to duration of time or history of atrial fibrillation.

Valsartan improves arterial stiffness in type 2 diabetes independently of blood pressure lowering

Increased arterial stiffness, as estimated from aortic pulse wave velocity (Ao-PWV), and albuminuria are independent predictors for cardiovascular disease in type 2 diabetes mellitus (T2DM). Whether angiotensin receptor blockers (ARBs), drugs with cardio-renal protective effects, improve Ao-PWV to a greater extent than other equipotent antihypertensive medications remains unclear. After a 4-week washout phase, we compared the effects of valsartan (n=66), an ARB, with that of amlodipine (n=65), a calcium channel blocker on Ao-PWV in 131 T2DM patients with pulse pressure (PP) >or=60 mm Hg and raised albumin excretion rate (AER) in a 24-week randomized, double-blind, parallel group study. Hydrochlorothiazide (HCTZ) 25 mg/d was added to valsartan 160 mg and amlodipine 5 mg/od uptitrated to 10 mg/od after 4 weeks to ensure equivalent BP control. After 24 weeks brachial and central aortic PP had fallen to a similar extent with attained mean (SD) brachial and central PP of 61.6 (13.6) and 47.3 (14.1) mm Hg in the valsartan/HCTZ group and 61.5 (12.2) and 47.3 (9.9) mm Hg in the amlodipine group, respectively. Ao-PWV showed a significantly greater reduction, mean (95% CI), -0.9 m/s (-1.4 to -0.3) for valsartan/HCTZ compared to amlodipine (P=0.002). AER fell significantly only with Val/HCTZ from 30.8(20.4, 46.5) to 18.2(12.5, 26.3) mcg/min, (P=0.01) with between treatment difference in favor of Val/HCTZ of -15.3mcg/min (P<0.001). Changes in AER and Ao-PWV were not correlated. Valsartan/HCTZ improves arterial stiffness and AER to a significantly greater extent than amlodipine despite similar central and brachial BP control. These 2 effects, which appear independent of each other, may explain the specific cardio-renal protective properties of ARBs.

Mast cell renin and a local renin-angiotensin system in the airway: role in bronchoconstriction

We previously reported that mast cells express renin, the rate-limiting enzyme in the renin-angiotensin cascade. We have now assessed whether mast cell renin release triggers angiotensin formation in the airway. In isolated rat bronchial rings, mast cell degranulation released enzyme with angiotensin I-forming activity blocked by the selective renin inhibitor BILA2157. Local generation of angiotensin (ANG II) from mast cell renin elicited bronchial smooth muscle contraction mediated by ANG II type 1 receptors (AT(1)R). In a guinea pig model of immediate type hypersensitivity, anaphylactic mast cell degranulation in bronchial rings resulted in ANG II-mediated constriction. As in rat bronchial rings, bronchoconstriction (BC) was inhibited by a renin inhibitor, an AT(1)R blocker, and a mast cell stabilizer. Anaphylactic release of renin, histamine, and beta-hexosaminidase from mast cells was confirmed in the effluent from isolated, perfused guinea pig lung. To relate the significance of this finding to humans, mast cells were isolated from macroscopically normal human lung waste tissue specimens. Sequence analysis of human lung mast cell RNA showed 100% homology between human lung mast cell renin and kidney renin between exons 1 and 10. Furthermore, the renin protein expressed in lung mast cells was enzymatically active. Our results demonstrate the existence of an airway renin-angiotensin system triggered by release of mast-cell renin. The data show that locally produced ANG II is a critical factor governing BC, opening the possibility for novel therapeutic targets in the management of airway disease.

Aldose reductase-regulated tumor necrosis factor-alpha production is essential for high glucose-induced vascular smooth muscle cell growth

Diabetes is associated with increased generation of cytokines and tissue inflammation, but it is unclear how increased cytokine synthesis is causally related to the development of diabetic complications. Here, we report that exposure to high (25 mm) glucose, but not iso-osmotic concentrations of mannitol or 3-methyl glucose, increased TNF-alpha secretion by rat and human aortic smooth muscle cells in culture. The increase in TNF-alpha production was prevented by actinomycin D and cycloheximide, indicating transcriptional activation of TNF-alpha gene. High glucose (HG)-induced TNF-alpha release was specifically inhibited by protein kinase C (PKC)-delta inhibitor (Rottlerin; EMD Biosciences, San Diego, CA), but not PKC-beta2 inhibitor (CGP53353; Tocris Cookson Inc., Ellisville, MO), indicating the possible involvement of PKC-delta in HG signaling. TNF-alpha secretion was also prevented by pretreating cells with aldose reductase (AR) inhibitors, sorbinil or tolrestat and in cells treated with antisense AR mRNA. Inhibition of AR also prevented the increase in TNF-alpha mRNA. Addition of anti-TNF-alpha antibodies or soluble TNF-alpha receptors 1 and 2 to the medium or RNA interference ablation of TNF-alpha attenuated nuclear factor-kappaB activation and prevented HG-stimulated cell growth. These data indicate that AR is required for HG-induced TNF-alpha synthesis and release. In vivo, the release of TNF-alpha by HG leading to autocrine stimulation of TNF-alpha synthesis may be a critical step in the development of the cardiovascular complications of diabetes. Interruption of the autocrine effects of TNF-alpha may be a useful strategy for treating diabetic vasculopathies.

Cooperation of SRC-1 and p300 with NF-kappaB and CREB in angiotensin II-induced IL-6 expression in vascular smooth muscle cells

OBJECTIVE

The purpose of this study was to evaluate the role of coactivator histone acetyltransferases (HATs) p300 and SRC-1 in angiotensin II (Ang II)-induced interleukin-6 (IL-6) gene expression in vascular smooth muscle cells (VSMCs).

METHODS AND RESULTS

Ang II increased IL-6 mRNA expression via NF-kappaB and CREB in an extracellular signal-regulated kinase (ERK)-dependent manner in rat VSMCs. It was also significantly enhanced by the histone deacetylase inhibitor, Trichostatin A. Chromatin immunoprecipitation (ChIP) assays showed that Ang II increased Histone H3 Lysine (K9/14) acetylation on the IL-6 promoter. Ang II-induced IL-6 promoter transactivation was significantly enhanced by p300 and SRC-1, with maximal activation in cells cotransfected with NF-kappaB (p65) and SRC-1. Nucleofection of VSMCs with either an ERK phosphorylation site mutant of SRC-1 or p300/CBP HAT deficient mutants significantly blocked Ang II-induced IL-6 expression. ChIP assays revealed that Ang II enhanced coordinate occupancy of p65, CREB, p300, and SRC-1 at the IL-6 promoter. An ERK pathway inhibitor blocked Ang-induced IL-6 promoter SRC-1 occupancy and histone acetylation.

CONCLUSIONS

Ang II-induced IL-6 expression requires NF-kappaB and CREB as well as ERK-dependent histone acetylation mediated by p300 and SRC-1. These results provide new insights into nuclear chromatin mechanisms by which Ang II regulates inflammatory gene expression.

Calcium-channel modulators for cardiovascular disease

It is generally accepted that hypertension doubles the risk of cardiovascular disease, of which coronary heart disease is the most common and lethal. Hypertension is a predisposing factor for the development of stroke, peripheral arterial disease, heart failure and end-state renal disease. Atherosclerosis-causing coronary heart disease is related to the severity of hypertension. Inhibition of calcium entry reduces the active tone of vascular smooth muscle and produces vasodilatation. This pharmacological action has been the basis for the use of calcium-channel blockers (CCBs) for the management of hypertension. Other drug families may achieve this: diuretics, beta-blockers, angiotensin-converting enzyme inhibitors, angiotensin-receptor antagonists. Cardiovascular hypertrophy and atherosclerosis are major complications related to high blood pressure. Cardiac hypertrophy is considered as an independent risk factor associated with abnormalities of diastolic function and can result in heart failure. Atherosclerosis is associated with activation of innate immunity. Atherosclerosis is expressing itself not only as coronary heart disease, but as a cerebrovascular and peripheral arterial disease. By impairing physiological vasomotor function, atherosclerosis includes ultimately necrosis of myocardium. CCBs reduce blood pressure. Do they prevent the progress of the main complications of hypertension? This major question is the matter of the present paper.

Role of angiotensin II in retinal leukostasis in the diabetic rat

To study if the endogenous renin-angiotensin system affects diabetic retinal leukostasis, rats with streptozotocin-induced diabetes were treated with an ACE inhibitor (ramipril), an angiotensin II AT(1) receptor antagonist (losartan) and the Ca channel blocker, (nifedipine). In the diabetic rats, these drug treatments reduced systolic blood pressure by approximately 16 mmHg but did not change blood glucose. After 2 weeks, the rats were examined for retinal leukostasis in vivo with a scanning laser ophthalmoscope (SLO). Retinal leukostasis, which was defined as no movement of arrested leukocytes over 2 min, was markedly higher in diabetic rats than normal controls (P<0.01). Leukostasis was significantly decreased by ramipril and losartan (P<0.01 vs. untreated diabetic rats) but was still higher than normal. Retinal leukostasis after nifedipine treatment was not significantly different than in untreated diabetic rats. The same trend was observed when leukostasis was analyzed on retinal flat mounts with concanavalin A and CD45 immunofluorescence; ramipril and losartan treatment, however, decreased leukostasis to values no different than controls. Retinal leukostasis was lowered by nifedipine (P<0.05, untreated diabetes vs. nifedipine-treated) but was still higher than in normal, ramipril-, or losartan-treated rats. Assays of gene expression of retinal intercellular adhesion molecule (ICAM-1) by semi-quantitative RT-PCR indicated that ICAM-1 mRNA was increased in diabetic rats but was decreased markedly by treatment with losartan or ramipril, and modestly by nifedipine. In summary, suppressing the activity of the endogenous renin-angiotensin system markedly decreases, perhaps even normalizes, the retinal leukostasis that accompanies type I diabetes in rats. These effects seem to be partly independent of blood pressure and to be associated with a decrease in ICAM-1 gene expression. Angiotensin II may, thus, mediate retinal leukostasis in early diabetes.

Angiotensin II induces interleukin-6 in humans through a mineralocorticoid receptor-dependent mechanism

This study tested the hypothesis that angiotensin promotes oxidative stress and inflammation in humans via aldosterone and the mineralocorticoid receptor. We measured the effect of intravenous aldosterone (0.7 mug/kg per hour for 10 hours followed by 0.9 mug/kg per hour for 4 hours) and vehicle in a randomized, double-blind crossover study in 11 sodium-restricted normotensive subjects. Aldosterone increased interleukin (IL)-6 (from 4.7+/-4.9 to 9.4+/-7.1 pg/mL; F=4.94; P=0.04) but did not affect blood pressure, serum potassium, or high-sensitivity C-reactive protein. We next conducted a randomized, double-blind, placebo-controlled, crossover study to measure the effect of 3-hour infusion of angiotensin II (2 ng/kg per minute) and norepinephrine (30 ng/kg per minute) on separate days after 2 weeks of placebo or spironolactone (50 mg per day) in 14 salt-replete normotensive subjects. Angiotensin II increased blood pressure (increase in systolic pressure: 13.7+/-7.5 and 15.2+/-9.4 mm Hg during placebo and spironolactone, respectively; P<0.001 for angiotensin II) and decreased renal plasma flow (-202+/-73 and -167+/-112 mL/min/1.73 kg/m(2); P<0.001 for angiotensin II effect) similarly during placebo and spironolactone. Spironolactone enhanced the aldosterone response to angiotensin II (increase of 17.0+/-10.6 versus 9.0+/-5.7 ng/dL; P=0.002). Angiotensin II transiently increased free plasma F(2)-isoprostanes similarly during placebo and spironolactone. Angiotensin II increased serum IL-6 concentrations during placebo (from 1.8+/-1.1 to 2.4+/-1.4 pg/mL; F=4.5; P=0.04) but spironolactone prevented this effect (F=6.4; P=0.03 for spironolactone effect). Norepinephrine increased blood pressure and F(2)-isoprostanes but not aldosterone or IL-6. Aldosterone increases IL-6 in humans. These data suggest that angiotensin II induces IL-6 through a mineralocorticoid receptor-dependent mechanism in humans. In contrast, angiotensin II-induced oxidative stress, as measured by F(2)-isoprostanes, is mineralocorticoid receptor independent and may be pressor dependent.

Relation of C-reactive protein to the first onset and the recurrence rate in lone atrial fibrillation

The presence of systemic inflammation determined by elevations in high-sensitivity C-reactive protein (hs-CRP) has been associated with persistence of atrial fibrillation (AF). The influence of inflammation markers, such as hs-CRP, on the recurrences of lone AF, however, has not been clarified. We tested the hypothesis of whether, in patients with a first paroxysmal episode of lone AF, the hs-CRP levels were elevated, and whether elevated hs-CRP could predict the recurrence rate of lone AF in patients without antiarrhythmic drugs. Using a case-control study design, the hs-CRP levels in 125 patients with a documented symptomatic first paroxysmal episode of lone AF was compared with the hs-CRP levels in 65 control patients. hs-CRP levels are presented as median values with the interquartile range (25th to 75th percentiles). The hazard ratio compared the 75th percentile of hs-CRP with the 25th percentile. In the arrhythmia group, hs-CRP was higher than in the control patients (median 0.23 mg/dl, interquartile range 0.12 to 0.49, vs 0.087 mg/dl, interquartile range 0.058 to 0.098, p <0.001). After adjusting for baseline characteristics, including, age, gender, and baseline blood pressure, hs-CRP remained a significant predictor of recurrent AF (hazard ratio 1.15, 95% confidence interval 1.04 to 1.24, p = 0.002) at 2 years of follow-up. In conclusion, this study is the first to document that the first paroxysmal episode of lone AF is associated with elevated hs-CRP levels, suggesting that hs-CRP may be a marker for inflammatory states that may promote the initiation of lone AF. These pathways may represent a novel mechanism by which structural changes resulting from inflammation could induce lone AF. The elevated hs-CRP levels could also predict the recurrence rate of lone AF in patients without antiarrhythmic drugs.

Dual pathways for nuclear factor kappaB activation by angiotensin II in vascular smooth muscle: phosphorylation of p65 by IkappaB kinase and ribosomal kinase

Activation of nuclear factor (NF)-kappaB by angiotensin II (Ang II) plays an essential role in stimulating expression of vascular adhesion molecules, which are essential for vascular inflammation. We report that Ang II activates NF-kappaB by phosphorylating its p65 subunit via a pathway mediated partially by ribosomal S6 kinase (RSK). In investigating other pathway(s) that may be involved, we found that the ability of Ang II to activate NF-kappaB in mouse embryonic fibroblast is suppressed (approximately 70%) either by deletion of IkappaB Kinase (IKK) or by inhibiting or knocking down IKK in vascular smooth muscle cells using a dominant-negative IKK adenovirus or small interference RNA to IKKbeta. Thus, Ang II also stimulates NF-kappaB via IKK. In vitro, we found that Ang II stimulates IKK to phosphorylate myelin basic protein and the p65 subunit of NF-kappaB. The mechanism by which Ang II activates IKK is to increase phosphorylation of IKKbeta in its activation loop (Ser181) rather than IkappaB phosphorylation. Inhibiting both the RSK and IKK pathways completely blocks the Ang II-induced p65 phosphorylation and NF-kappaB activation. These 2 pathways are independent: inhibiting IKK does not block Ang II-induced phosphorylation of RSK, whereas inhibiting mitogen-activated protein kinase 1 does not affect phosphorylation of IKK. Finally, we found that Ang II can induce expression of vascular adhesion molecules by 2 pathways; both IKK and RSK lead to phosphorylation of the p65 subunit of NF-kappaB to increase vascular cell adhesion molecule-1 transcription. The 2 pathways are functionally important because inhibiting IKK and RSK in vascular smooth muscle cells blocks Ang II-induced expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 to limit vascular inflammation.

Angiotensin-converting enzyme inhibition attenuates myonuclear addition in overloaded slow-twitch skeletal muscle

Because optimal overload-induced skeletal muscle hypertrophy requires ANG II, we aimed to determine the effects of blocking ANG II production [via angiotensin-converting enzyme (ACE) inhibition] on potential mediators of hypertrophy in overloaded skeletal muscle, namely, myonuclear addition and fibroblast content. In a 2 × 2 design, adult (200–225 g) female Sprague-Dawley rats were placed into one of four groups ( n = 8/group): 7-day skeletal muscle overload, sham operation, 7-day skeletal muscle overload with ACE inhibition, or sham operation with ACE inhibition. Functional overloads of the plantaris and soleus muscles were produced via bilateral surgical ablation of the synergistic gastrocnemius muscle, and ACE inhibition was accomplished by the addition of the ACE inhibitor enalapril maleate to the animals' daily drinking water (0.3 mg/ml). Myonuclear addition and extrasarcolemmal nuclear proliferation, as measured by in vivo 5-bromo-2′-deoxyuridine labeling, were significantly ( P ≤ 0.05) increased by overload in both the slow-twitch soleus and fast-twitch plantaris muscles. Furthermore, ACE inhibition attenuated these overload-induced increases in the soleus muscle but not in the plantaris muscle. However, the effect of ACE inhibition on soleus extrasarcolemmal nuclei was not likely due to differences in fibroblast content because overload elicited significant increases in vimentin-positive areas in soleus and plantaris muscles, and these areas were unaffected by ACE inhibition in either muscle. There was no effect of ACE inhibition on any measure in sham-operated muscles. Collectively, these data indicate that ANG II may mediate the satellite cell response to overload in slow-twitch soleus but not in fast-twitch plantaris muscles and that this effect may occur independently of changes in fibroblast content.

Angiotensin II Enhances Interleukin-18 Mediated Inflammatory Gene Expression in Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) express functional interleukin-18 receptors (IL-18Rs), composed of α and β subunits. These subunits are elevated in VSMCs of atherosclerotic plaques and can be induced by inflammatory agents in cultured VSMC. Because both IL-18 and Angiotensin II (Ang II) are implicated in atherosclerosis, our objective was to analyze the role of IL-18 signaling and potential cross-talk with Ang II in VSMC. We observed that IL-18 activated Src kinase, protein kinase C, p38 and JNK MAPKs, Akt kinase, transcription factors NF-kB and AP-1, and induced expression of pro-inflammatory cytokines in VSMC. Pretreatment of VSMC with Ang II enhanced IL-18-induced NF-kB activation and cytokine gene expression. Interestingly, Ang II directly increased mRNA and cell surface protein levels of the IL-18Rα subunit. Functional relevance in an organ culture model was demonstrated by the observation that incubation of intact mouse aortas ex vivo with Ang II also significantly increased IL-18Rα expression. Furthermore, Ang II significantly stimulated transcription from a minimal IL-18Rα promoter containing putative binding sites for STAT and AP-1. Ang II also increased in vivo recruitment of STAT-3 on the IL-18Rα promoter. Finally, dominant negative STAT-3 mutant blocked Ang II-induced IL-18Rα promoter activation in CHO cells overexpressing AT1a receptor and IL-18Rα mRNA expression in HVSMC. Thus, Ang II enhances IL-18 induced inflammatory genes by increasing IL-18Rα expression. These results illustrate a novel mechanism wherein Ang II- mediated increases in inflammatory genes and proatherogenic effects in the vasculature are enhanced by a vicious loop and cross-talk with the IL-18 signaling pathway.

Growth arrest specific protein 6/Axl signaling in human inflammatory renal diseases

BACKGROUND

Growth arrest-specific gene 6 (Gas6) and its binding partner, the receptor tyrosine kinase Axl, are important mediators in experimental nephritis. The authors tested whether the Gas6/Axl signaling pathway participates in human renal diseases.

METHODS

The authors compared 26 human renal specimens from patients with IgA nephritis, acute diffuse immune complex glomerulonephritis, acute lupus nephritis, antineutrophil cytoplasmic antibody--associated glomerulonephritis, acute transplant rejection, and normal renal tissue. Because reactive oxygen species are pivotal in inflammation, the authors tested whether the Axl/Gas6 expression is influenced by NADPH oxidase in vitro.

RESULTS

Gas6 and Axl immunofluorescence was barely detectable in normal kidney. However, in disease Axl was copiously expressed in the small vessel media, glomeruli, distal tubules, and collecting ducts. Similarly, Gas6 was upregulated in the small vessel intima and media, all segments of the renal tubules, the brush border, and glomeruli. Gas6 and Axl upregulation was a prominent but nonspecific finding in these renal diseases. Cultured rat vascular smooth muscle cells and immortalized human mesangial cells were stimulated with angiotensin (Ang) II (1 x 10(-7) mol/L) for 6 or 18 hours. Confocal microscopy and Western blot showed Ang II-dependent Gas6 and Axl expression. An antisense probe against the p22 phox unit of NADPH-oxidase suppressed Ang II-induced Gas6 and Axl expression. In addition, in p47 phox knockout cells Ang II-induced Gas6 and Axl expression were blocked.

CONCLUSION

GAS6/Axl signaling is involved in human renal disease. The Ang II-induced Gas6 and Axl expression may be dependent on NADPH-oxidase. Gas6 and Axl are important signaling molecules in human renal disease and may be potential therapeutic targets.

Insulin resistance and chronic cardiovascular inflammatory syndrome

Insulin resistance is increasingly recognized as a chronic, low-level, inflammatory state. Hyperinsulinemia and insulin action were initially proposed as the common preceding factors of hypertension, low high-density lipoprotein cholesterol, hypertriglyceridemia, abdominal obesity, and altered glucose tolerance, linking all these abnormalities to the development of coronary heart disease. The similarities of insulin resistance with another inflammatory state, atherosclerosis, have been described only in the last few decades. Atherosclerosis and insulin resistance share similar pathophysiological mechanisms, mainly due to the actions of the two major proinflammatory cytokines, TNF-alpha and IL-6. Genetic predisposition to increased transcription rates of these cytokines is associated with metabolic derangement and simultaneously with coronary heart disease. Dysregulation of the inflammatory axis predicts the development of insulin resistance and type 2 diabetes mellitus. The knowledge of how interactions between metabolic and inflammatory pathways occur will be useful in future therapeutic strategies. The effective administration of antiinflammatory agents in the treatment of insulin resistance and atherosclerosis is only the beginning of a promising approach in the management of these syndromes.

RAS and connective tissue in the heart

Circulating angiotensin (Ang) II has well-known endocrine properties in the cardiovasculature. AngII, produced de novo within the heart, has various autocrine and paracrine properties on resident cells expressed via AT(1) receptor-ligand binding. Herein, we review the heart's renin-angiotensin system and its role in connective tissue turnover involving heart valve leaflets and fibrous tissue that appears at sites of injury, such as following myocardial infarction.

Endothelial activation by angiotensin II through NFkappaB and p38 pathways: Involvement of NFkappaB-inducible kinase (NIK), free oxygen radicals, and selective inhibition by aspirin

Angiotensin-II (AII), the dominant effector of the renin-angiotensin system, is involved in the pathogenesis of cardiovascular diseases, such as atherosclerosis. Upregulation of the adhesion molecules VCAM-1, ICAM-1, and E-selectin in endothelial cells by inflammatory cytokines through nuclear factor kappa B (NFkappaB) activation is implicated in formation and progression of atherosclerotic plaque. Here we show that AII induces NFkappaB-dependent transcription in primary endothelial cell lines, leading to the upregulation of ICAM-1 and VCAM-1 expression. NFkappaB activation by AII is mediated by the NFkappaB-inducing kinase (NIK), a common mediator of NFkappaB activation by inflammatory cytokines, such as TNF-alpha. However, NFkappaB stimulation by AII differs from that of TNF-alpha since a TNF-receptor associated factor 2 (TRAF-2) dominant negative mutant does not prevent AII-mediated NFkappaB activation. In analogy with TNF-alpha-dependent activation of NFkappaB, treatment with either the anti-oxidant N-acetyl cysteine (NAC) or the cyclooxygenase (COX) inhibitor acetyl salicylic acid (aspirin), but not indometacin, prevents the induction of NFkappaB-dependent transcription by AII. Thus, production of reactive oxygen species, aspirin (asp)-sensitive enzymes of the arachidonate metabolism, and NIK are common transducers of AII- and TNF-dependent pathways to NFkappaB. AII also activates the inflammatory p38 kinase in endothelial cells, an effect inhibited by exposure to either NAC or asp. Pharmacological interference of the p38 pathway, with the inhibitor SB 202190, prevented AII-mediated activation of the NFkappaB target V-CAM, without affecting degradation of IkappaBalpha. These results support a pro-inflammatory effect of the vasoactive peptide AII in endothelial cells, through at least two pathways-NFkappaB and p38-both of which are sensitive to asp and antioxidants.

Arterial hypertension and ischaemic stroke

OBJECTIVES

Arterial hypertension is, besides age, the number one risk factor for ischaemic stroke. Patients with arterial hypertension frequently present with additional coexisting vascular risk factors interacting in a complex way.

MATERIAL AND METHODS

This paper reviews the benefit of antihypertensive treatment, as well as different treatment options of arterial hypertension and their side-effects.

RESULTS

Patients with definite arterial hypertension, but also patients with so-called normal or high-normal blood pressure are at increased risk to develop stroke and other cardiovascular complications. Vascular remodelling of small and large vessels provoked by arterial hypertension is the initial step in the development of atherosclerosis and lipohyalinosis. Vascular remodelling can be improved or even normalized by antihypertensive treatment with angiotensin-converting-enzyme inhibitors and angiotensin-I-receptor antagonists showing the most convincing effects. Angiotensin-converting-enzyme inhibitors and angiotensin-I-receptor antagonists have the lowest rate of side-effects, however, economic restraints hinder their general application. Statins are needed to treat dyslipidaemia. They also lower blood pressure and have a synergistic effect with the above two antihypertensive components in lowering blood pressure. In hypertensive patients, risk of stroke and other cardiovascular complications is determined by the blood pressure level and the presence or absence of target organ damage and the interaction with other risk factors, such as cigarette smoking, dyslipidaemia, and diabetes. These high-risk patients should be treated even more aggressively than usual.

CONCLUSIONS

In the vast majority of patients and healthy individuals, target blood pressure should be as high as or below 120/80 mmHg to minimize the occurrence of stroke and other cardiovascular complications.

C-reactive protein elevation in patients with atrial arrhythmias: inflammatory mechanisms and persistence of atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) may persist due to structural changes in the atria that are promoted by inflammation. C-reactive protein (CRP), a marker of systemic inflammation, predicts cardiovascular events and stroke, a common sequela of AF. We hypothesized that CRP is elevated in patients with atrial arrhythmias.

METHODS AND RESULTS

Using a case-control study design, CRP in 131 patients with atrial arrhythmias was compared with CRP in 71 control patients. Among arrhythmia patients, 6 had frequent atrial ectopy or tachycardia, 86 had paroxysmal AF, 39 had persistent AF lasting >30 days, and 70 had lone arrhythmias. CRP was higher in arrhythmia than in control patients (median, 0.21 versus 0.096 mg/dL; P<0.001). Arrhythmia patients in AF within 24 hours before sampling had higher CRP than those in sinus rhythm (0.30 versus 0.15 mg/dL; P<0.001). CRP in controls was not different than in patients with atrial ectopy or tachycardia. Lone arrhythmia patients had a CRP of 0.21 mg/dL, which was not significantly lower than arrhythmia patients with structural heart disease (CRP, 0.23 mg/dL) but higher than controls (P=0.002). Persistent AF patients had a higher CRP (0.34 mg/dL) than paroxysmal AF patients (0.18 mg/dL; P=0.008); both groups had higher CRP levels than controls (P</=0.005).

CONCLUSIONS

CRP is elevated in AF patients. This study is the first to document elevated CRP in non-postoperative arrhythmia patients. These findings are reinforced by stepwise CRP elevation with higher AF burden. Although the cause of elevated CRP levels in AF patients remains unknown, elevated CRP may reflect an inflammatory state that promotes the persistence of AF.