Human urotensin II as a link between hypertension and coronary artery disease

Serum Urotensin II Levels Are Elevated in Patients with Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) has become major public concern and is continuously investigated in new aspects of pathophysiology and management. Urotensin II (UII) is a powerful vasoconstrictor with a role in cardiovascular diseases. The main goal of this study was to evaluate serum UII levels in OSA patients and matched controls. A total of 89 OSA patients and 89 controls were consecutively enrolled. A medical history review and physical examination of the participants was conducted, with polysomnography performed in the investigated group. UII levels and other biochemical parameters were assessed according to the standard laboratory protocols. The median AHI in the OSA group was 39.0 (31.4-55.2) events/h, and they had higher levels of hsCRP when compared to control group (2.87 ± 0.71 vs. 1.52 ± 0.68 mg/L; p < 0.001). Additionally, serum UII levels were significantly higher in the OSA group (3.41 ± 1.72 vs. 2.18 ± 1.36 ng/mL; p < 0.001), while positive correlation was found between UII levels and hsCRP (r = 0.450; p < 0.001) and systolic blood pressure (SPB) (r = 0.317; p < 0.001). Finally, multiple regression analysis showed significant association of UII levels with AHI (0.017 ± 0.006, p = 0.013), SBP (0.052 ± 0.008, p < 0.001) and hsCRP (0.538 ± 0.164, p = 0.001). As UII levels were associated with blood pressure and markers of inflammation and OSA severity, it might play an important role in the complex pathophysiology of OSA and its cardiometabolic complications.

Birth Weight Standard Deviation Score is a Significant Determinant of Serum Urotensin-II Levels at Term-Equivalent Age in Preterm Infants

OBJECTIVE

Urotensin II (U-II) is a potent vasoconstrictor peptide, and increased U-II levels are associated with atherosclerosis and hypertension in adults. Low birth weight (LBW) infants have higher risks of such diseases in the future. A small number of nephrons is one of possible mechanism underlying these risks in LBW infants, while vascular elasticity and cardiac function might be another important factor. The objective of this study is to evaluate U-II levels in preterm LBW infants at an early stage of life and determine perinatal factors associated with U-II levels.

STUDY DESIGN

The study population consisted of 57 preterm LBW infants (26 males and 31 females), including 49 appropriate for gestational age (AGA) and 8 small for gestational age (SGA) infants, born at a gestational age of ≤34 weeks with a mean birth weight of 1,589 g. Serum U-II levels were measured at term-equivalent age to evaluate perinatal factors related to serum U-II levels.

RESULTS

Preterm SGA infants had significantly higher serum U-II levels than preterm AGA infants at term-equivalent age (p = 0.019). Serum U-II levels in preterm LBW infants at term-equivalent age were inversely correlated with birth weight standard deviation (SD) score in a simple regression analysis (r =  - 0.395, p = 0,002) and the correlation was maintained in the multiple regression analysis.

CONCLUSION

Our results indicate that birth weight SD score might be associated with serum U-II levels in preterm LBW infants at term-equivalent age. Further studies are required to determine whether U-II levels at an early stage of life might influence the risk of atherosclerosis and hypertension.

KEY POINTS

· U-II is a potent vasoconstrictor.. · We evaluated serum U-II levels in preterm infants.. · Fetal growth is negatively related to serum U-II levels..

Urotensin II levels in patients with inflammatory bowel disease

BACKGROUND

Patients with inflammatory bowel disease (IBD) are associated with increased cardiovascular risk and have increased overall cardiovascular burden. On the other hand, urotensin II (UII) is one of the most potent vascular constrictors with immunomodulatory effect that is connected with a number of different cardiometabolic disorders as well. Furthermore, patients with ulcerative colitis have shown increased expression of urotensin II receptor in comparison to healthy controls. Since the features of IBD includes chronic inflammation and endothelial dysfunction as well, it is plausible to assume that there is connection between increased cardiac risk in IBD and UII.

AIM

To determine serum UII levels in patients with IBD and to compare them to control subjects, as well as investigate possible associations with relevant clinical and biochemical parameters.

METHODS

This cross sectional study consecutively enrolled 50 adult IBD patients (26 with Crohn’s disease and 24 with ulcerative colitis) and 50 age and gender matched controls. Clinical assessment was performed by the same experienced gastroenterologist according to the latest guidelines. Ulcerative Colitis Endoscopic Index of Severity and Simple Endoscopic Score for Crohn’s Disease were used for endoscopic evaluation. Serum levels of UII were determined using the enzyme immunoassay kit for human UII, according to the manufacturer’s instructions.

RESULTS

IBD patients have significantly higher concentrations of UII when compared to control subjects (7.57 ± 1.41 vs 1.98 ± 0.69 ng/mL, P < 0.001), while there were no significant differences between Crohn’s disease and ulcerative colitis patients (7.49 ± 1.42 vs 7.65 ± 1.41 ng/mL, P = 0.689). There was a significant positive correlation between serum UII levels and high sensitivity C reactive peptide levels (r = 0.491, P < 0.001) and a significant negative correlation between serum UII levels and total proteins (r = -0.306, P = 0.032). Additionally, there was a significant positive correlation between serum UII levels with both systolic (r = 0.387, P = 0.005) and diastolic (r = 0.352, P = 0.012) blood pressure. Moreover, serum UII levels had a significant positive correlation with Ulcerative Colitis Endoscopic Index of Severity (r = 0.425, P = 0.048) and Simple Endoscopic Score for Crohn’s Disease (r = 0.466, P = 0.028) scores. Multiple linear regression analysis showed that serum UII levels retained significant association with high sensitivity C reactive peptide (β ± standard error, 0.262 ± 0.076, P < 0.001) and systolic blood pressure (0.040 ± 0.017, P = 0.030).

CONCLUSION

It is possible that UII is involved in the complex pathophysiology of cardiovascular complications in IBD patients, and its purpose should be investigated in further studies.

Urantide alleviates the symptoms of atherosclerotic rats in vivo and in vitro models through the JAK2/STAT3 signaling pathway

Atherosclerosis is the leading cause of human death, and its occurrence and development are related to the urotensin II (UII) and UII receptor (UT) system and the biological function of vascular smooth muscle cells (VSMCs). During atherosclerosis, impaired biological function VSMCs may promote atherosclerotic plaque formation. The Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway is an important mediator of signal transduction; however, the role of this signaling pathway in atherosclerosis and VSMCs remains unknown. This study aimed to investigate the effects of urantide on the JAK2/STAT3 signaling pathway in atherosclerosis. We examined the effect of urantide on the UII/UT system and the JAK2/STAT3 signaling pathway in a high fat diet induced atherosclerosis rat model and studied the effect and mechanism of urantide on the phenotypic transformation of VSMCs. We found that the UII/UT system and JAK2/STAT3 signaling pathway were highly activated in the thoracic aorta in atherosclerotic rats and in ox-LDL- and UII-induced VSMCs. After urantide treatment, the pathological changes in atherosclerotic rats were effectively improved, and the activities of the UII/UT system and JAK2/STAT3 signaling pathway were inhibited. Moreover, urantide effectively inhibited proliferation and migration and reversed the phenotypic transformation of VSMCs. These results demonstrated that urantide may control the JAK2/STAT3 signaling pathway by antagonizing the UII/UT system, thereby maintaining the biological function of VSMCs and potentially preventing and curing atherosclerosis.

Urantide decreases hepatic steatosis in rats with experimental atherosclerosis via the MAPK/Erk/JNK pathway

Hepatic steatosis, an indicator of atherosclerosis (AS), is always accompanied by inflammatory responses and disturbances in lipid metabolism. The present study investigated the protective effect of urantide, a urotensin II (UII) receptor antagonist, on the liver of rats with AS with hepatic steatosis by regulating the MAPK pathway. AS was induced in rats via an intraperitoneal injection of vitamin D3 and the administration of a high‑fat diet. Urantide treatment was then administered to the rats. Pathology, liver index, lipid levels and liver function were measured to determine liver injury. The expression levels of UII and G protein‑coupled receptor 14 (GPR14) were determined using immunohistochemistry, reverse transcription‑quantitative PCR and western blotting. The expression levels of MAPK‑related proteins in hepatocytes from each group were quantified using western blotting and immunofluorescence staining. Rats with AS had typical pathological changes associated with AS and hepatic steatosis, which were significantly improved by urantide treatment. Blood lipid levels, body weight, liver index and liver function were recovered in rats with AS after urantide treatment. Urantide downregulated the expression levels of UII and GPR14 in the livers of rats with AS; concurrently, the phosphorylation of Erk1/2 and JNK was significantly decreased. Moreover, no significant changes were observed in the phosphorylation of p38 MAPK in AS rat livers. In conclusion, urantide inhibits the activation of Erk1/2 and JNK by blocking the binding of UII and GPR14, thereby alleviating hepatic steatosis in rats with AS, ultimately restoring lipid metabolism in the liver and alleviating AS lesions.

The Relationship of the Urotensin-2 Level in the Aqueous Humor with Systemic Diseases and Pupil Size: Comparative Study

Purpose: To detect the presence of urotensin-2 (U-II) in the aqueous humor and evaluate the relationship between aqueous humor level and systemic diseases and pupil size. Methods: The study included 88 patients who underwent cataract surgery. Those with a pupil diameter (PD) of up to 4 mm were considered to have small dilation, those with 4-7 mm of dilatation were considered to have moderate dilation, and those with a PD of more than 7 mm considered to have large dilation. Patients with HT (hypertension) were classified as group 1, those with DM (diabetes mellitus) as group 2, and those with HT+DM as group 3, and those without any systemic disease as group 4. The U-II levels in humor aqueous samples taken from anterior chamber were measured. Results: When compared with the control group, it was observed that the level of U-II in the aqueous humor of the HT, DM, and DM+HT groups was significantly higher (P < 0.05). At the same time, when we compared the DM+HT group with the other groups, the level of U-II in the aqueous humor was significantly higher compared to the group with DM (P < 0.05). The U-II levels of the aqueous humor were higher in the patients with small pupils compared to the remaining groups (P < 0.005). Conclusion: U-II may play a role in small pupil pathophysiology. In addition, it was determined that patients with HT and/or diabetes had higher U-II levels in the aqueous humor than healthy individuals.

Role of Urotensin-II in Saphenous Vein Graft Disease

Objective

To elucidate the effect of diabetes mellitus (DM) on the atherosclerotic process in saphenous vein grafts by determining urotensin-II (U-II) levels in harvested saphenous veins of patients who underwent coronary artery bypass grafting (CABG).

Methods

Coronary artery disease (CAD) patients who underwent CABG were divided into two groups: Group I (eight non-diabetic patients; CAD group) and Group II (13 patients; DM+CAD group). All patients underwent coronary angiography prior to surgery and Gensini score was used to determine the severity of coronary atherosclerosis. Saphenous vein samples were stained with hematoxylin-eosin and U-II, then damage score, H-Score, and vein layer thicknesses were calculated and statistically evaluated.

Results

In light microscopic evaluation, significant difference was observed between the groups in terms of endothelial cells damage, internal elastic lamina degradation, and tunica media vascular smooth muscle cells (VSMCs) damage (P<0.001). U-II immunoreactivity was increased in tunica adventitia in the DM+CAD group (P=0.002). The increase in foam cells was directly proportional to the thickening of the subendothelial layer, and this increased U-II immunoreactivity. Gensini score was higher in the DM+CAD group than in the CAD group (P=0.002).

Conclusion

Our results show that saphenous vein grafts are already atherosclerotic before they are grafted in CAD patients. This disease is more severe in diabetic CAD patients and these changes can be detected using U-II immunoreactivity.

The relationship between urotensin II and insulin resistance in women with gestational diabetes mellitus

AIM

Urotensin II (UII), a pluripotent vasoactive peptide, plays a crucial role in development of insulin resistance. Gestational diabetes mellitus (GDM) is a metabolic disorder associated with insulin resistance. The aims of the current study were to compare UII levels in women with or without GDM and to investigate the relationship between UII and insulin resistance in women with GDM.

METHODS

A total of 84 women were recruited in this case-control study (42 women with GDM and 42 age- and body mass index (BMI)-matched pregnant women without GDM as controls). GDM was diagnosed by a 2-h 75-g oral glucose tolerance test over a period of 24-28 gestational weeks. Circulating UII levels were assessed via the ELISA method. The metabolic parameters of the recruited women were also determined.

RESULTS

The circulating levels of UII in women with GDM were higher than in controls (11.56 ± 4.13 vs. 7.62 ± 3.45 ng/ml, P < 0.001). UII showed a positive correlation with insulin resistance marker (HOMA-IR), fasting blood glucose, and BMI. Moreover, according to the results of multiple linear regression analyses, UII was independently related to HOMA-IR. Additionally, the binary logistic analysis revealed that the women with the highest tertile of UII levels showed increased risk for GDM by comparison with those women with the lowest tertile of UII levels.

CONCLUSION

Elevated UII levels are associated with insulin resistance in women with GDM.

Genome-Wide Linkage Analysis of Large Multiple Multigenerational Families Identifies Novel Genetic Loci for Coronary Artery Disease

Coronary artery disease (CAD) is the leading cause of death, and genetic factors contribute significantly to risk of CAD. This study aims to identify new CAD genetic loci through a large-scale linkage analysis of 24 large and multigenerational families with 433 family members (GeneQuest II). All family members were genotyped with markers spaced by every 10 cM and a model-free nonparametric linkage (NPL-all) analysis was carried out. Two highly significant CAD loci were identified on chromosome 17q21.2 (NPL score of 6.20) and 7p22.2 (NPL score of 5.19). We also identified four loci with significant NPL scores between 4.09 and 4.99 on 2q33.3, 3q29, 5q13.2 and 9q22.33. Similar analyses in individual families confirmed the six significant CAD loci and identified seven new highly significant linkages on 9p24.2, 9q34.2, 12q13.13, 15q26.1, 17q22, 20p12.3, and 22q12.1, and two significant loci on 2q11.2 and 11q14.1. Two loci on 3q29 and 9q22.33 were also successfully replicated in our previous linkage analysis of 428 nuclear families. Moreover, two published risk variants, SNP rs46522 in UBE2Z and SNP rs6725887 in WDR12 by GWAS, were found within the 17q21.2 and 2q33.3 loci. These studies lay a foundation for future identification of causative variants and genes for CAD.

Mild coronary artery stenosis has no impact on cardiac and vascular parameters in miniature swine exposed to positive acceleration stress

BACKGROUND

Exposure of pilots' heart to acceleration-associated stress (+Gz stress) is an adverse effect of high-performance aviation. The occurrence of coronary heart diseases is one of the most frequent medical causes leading to cessation of flying.

AIM

To assess the effects of +Gz stress on coronary artery stenosis (CAS) in a minimally invasive miniature swine model with a fast recovery.

METHODS

The proximal left anterior descending branch was ligated in 20 swine using silk suture. CAS degree (mild, moderate, severe) was analyzed by quantitative computerized angiography. Five swine underwent a sham operation. +Gz stress exposure was performed and venous blood was collected before/after exposure. Plasma C-reactive protein (CRP), endothelin (ET)-1, angiotensin (Ang) II and urotensin 2 (U2) levels were measured.

RESULTS

CAS models were successful in 18 animals. Two swine exhibited ventricular fibrillation during the procedure and died. Plasma CRP, ET-1, Ang II and U2 changed significantly after maximal tolerated +Gz stress exposure (all P < 0.05). After maximal tolerated +Gz stress exposure, plasma CRP, ET-1, Ang II and U2 levels increased in the moderate and severe stenosis groups, compared with the sham group (all P < 0.05), but there was no significant difference between the mild stenosis group and the sham group (all P > 0.05).

CONCLUSION

The fully endoscopic operation method successfully generated animal models of different degrees of CAS. Plasma CRP, ET-1, Ang II and U2 levels increased after +Gz stress exposure with increasing CAS severity. Animals with mild stenosis showed no ill effect under +Gz stress, suggesting that pilots with mild stenosis might be allowed to continue flying, but it must be confirmed in humans.

Is the serum level of salusin-β associated with hypertension and atherosclerosis in the pediatric population?

BACKGROUND

Salusins are recently identified endogenous bioactive peptides that have hypotensive and bradycardiac effects. Salusin-β is involved in the pathogenesis of human atherosclerosis.

METHODS

This was a prospective cohort study of a young patient population with hypertension (HTN). Based on ambulatory blood pressure monitoring (ABPM), the adolescents were categorized into two groups, namely, a hypertensive group consisting of patients with essential (primary) HTN (HTN group) and a group consisting of patients with white-coat HTN [reference (R) group]. Correlations between serum salusin-β level and clinical, laboratory and ambulatory blood pressure (BP) variables were assessed.

RESULTS

The median salusin-β concentration was significantly higher in patients with essential HTN than in those with white-coat HTN (R group). Salusin-β was positively correlated with the body mass index Z-score, systolic and diastolic blood pressure (BP) from three independent measurements, mean systolic BP during the daytime, triglyceride (TG) level, and atherogenic index (TG/high-density lipoprotein-cholesterol ratio).

CONCLUSIONS

The results of this preliminary study suggest that salusin-β may play an important role in the pathogenesis of HTN in a young population. Further research should focus on the role of salusin-β in the mechanism of essential HTN and the assessment of possible correlations between salusin-β and other well-known markers of atherosclerosis in both teenagers and adults. This research should serve as a base for future studies in this field.

Plasma urotensin II and neurokinin B levels in acute myocardial infarction and stable coronary artery disease

Objective:

This aim of the study is to investigate whether there are possible plasma urotensin-II (U-II) and neurokinin B (NKB) level changes in patients with acute myocardial infarction (AMI) or not and plasma urotensin-II (U-II) and neurokinin B (NKB) level changes in patients with acute myocardial infarction (AMI) and stable coronary artery disease (CAD) and to evaluate whether there is any relationship between these changes and the pathogenesis of these diseases.

Methods:

This is a prospective case-control study. Three groups were formed from randomly admitted patients with AMI, stable CAD, and controls. Biochemical parameters and U-II and NKB levels were measured. Patients with congestive heart failure, chronic hepatic and renal failure, severe cardiac valve disease, and severe pulmonary hypertension were excluded from the study. The normality of the data was evaluated using the Kolmogorov-Smirnov test. We compared the three groups with one-way ANOVA and Tukey test (Kruskal-Wallis test and Mann-Whitney U test).

Results:

Compared with controls (n=31) and CAD patients (n=32), AMI patients (n=32) had lower U-II and NKB levels. In cases of stable CAD, U-II and NKB levels were similar. A positive correlation was found between U-II and NKB (r=0.720; p=0.000). U-II and NKB were poorly correlated with left ventricle ejection fraction but not with C-reactive protein.

Conclusion:

We found that U-II and NKB levels were lower in patients with AMİ in than those with CAD or the control group. According to our findings, the decreased U-II and NKB levels were related to complicated atherosclerotic events.

Therapeutic implications of peptide interactions with G-protein-coupled receptors in diabetic vasculopathy

The dramatic worldwide increase in the prevalence of diabetes has generated an attempt by the scientific community to identify strategies for its treatment and prevention. Vascular dysfunction is a hallmark of diabetes and frequently leads to the development of atherosclerosis, coronary disease-derived myocardial infarction, stroke, peripheral arterial disease and diabetic 'triopathy' (retinopathy, nephropathy and neuropathy). These vascular complications, developing in an increasingly younger cohort of patients with diabetes, contribute to morbidity and mortality. Despite the development of new anti-diabetic or anti-hyperglycaemic drugs, vascular complications remain to be a problem. This warrants a need for new therapeutic strategies to tackle diabetic vasculopathy. There is a growing body of evidence showing that peptide-binding G-protein-coupled receptors (peptide-binding GPCRs) play an important role in the pathophysiology of vascular dysfunction during diabetes. Thus, in this review, we discuss some of the peptide-binding GPCRs involved in the regulation of vascular function that have potential to be a therapeutic target in the treatment of diabetic vasculopathy.

A quantitative trait locus for ascites on chromosome 9 in broiler chicken lines

A genome-wide SNP survey was used to identify chromosomal regions that showed linkage disequilibrium with respect to ascites susceptibility and ventricular hypertrophy in an F2 cross between previously described ascites-resistant and -susceptible lines. Variable number tandem repeats were used to obtain genotype data to further characterize these regions. A region on chromosome 9 (12 to 13 Mbp in 2011 assembly) shows association with ascites in the ascites lines and in several commercial broiler breeder lines with a significant sex effect. There are 2 candidate genes, AGTR1 (an angiotensin II type 1 receptor) and UTS2D (urotensin 2 domain containing), in this region that have been associated with hypertension and hypoxic response in mammals.

Urotensin II promotes vagal-mediated bradycardia by activating cardiac-projecting parasympathetic neurons of nucleus ambiguus

Urotensin II (U-II) is a cyclic undecapeptide that regulates cardiovascular function at central and peripheral sites. The functional role of U-II nucleus ambiguus, a key site controlling cardiac tone, has not been established, despite the identification of U-II and its receptor at this level. We report here that U-II produces an increase in cytosolic Ca(2+) concentration in retrogradely labeled cardiac vagal neurons of nucleus ambiguus via two pathways: (i) Ca(2+) release from the endoplasmic reticulum via inositol 1,4,5-trisphosphate receptor; and (ii) Ca(2+) influx through P/Q-type Ca(2+) channels. In addition, U-II depolarizes cultured cardiac parasympathetic neurons. Microinjection of increasing concentrations of U-II into nucleus ambiguus elicits dose-dependent bradycardia in conscious rats, indicating the in vivo activation of the cholinergic pathway controlling the heart rate. Both the in vitro and in vivo effects were abolished by the urotensin receptor antagonist, urantide. Our findings suggest that, in addition, to the previously reported increase in sympathetic outflow, U-II activates cardiac vagal neurons of nucleus ambiguus, which may contribute to cardioprotection.

Blocking the urotensin II receptor pathway ameliorates the metabolic syndrome and improves cardiac function in obese mice

The metabolic syndrome is defined by the presence of hyperlipidemia, obesity, hypertension, and diabetes. The syndrome is associated with significant cardiovascular morbidity and mortality. The aim of the present study was to determine the role of the vasoactive peptide urotensin II (UII) in the pathogenesis of the metabolic syndrome. We used obese mice (ob/ob) to determine the effect of UII receptor (UT) blockage on the different facets of the metabolic syndrome with special emphasis on cardiac function. Our data demonstrate a significant increase in UII and UT expression in the myocardium of obese mice accompanied by a significant decrease in sarco/endoplasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) expression, as well as intracellular Na(+) and Ca(2+) compared with wild-type mice (P<0.05). Treatment of ob/ob mice with the UII receptor antagonist SB657510 significantly improved glucose levels, blood pressure, hyperlipidemia, expression of myocardial SERCA2a, intracellular Na(+) and Ca(2+) and cardiac function in association with a decrease in weight gain, and mammalian target of rapamycin (mTOR) and sodium/hydrogen exchanger 1 (NHE-1) protein expression compared with vehicle (P<0.05). These findings demonstrate an important role for UII in the pathogenesis of the metabolic syndrome and suggest that the use of UT receptor antagonists may provide a new therapeutic tool for the treatment of this syndrome.

Salusins: potential use as a biomarker for atherosclerotic cardiovascular diseases

Human salusin- α and salusin- β are related peptides produced from prosalusin. Bolus injection of salusin- β into rats induces more profound hypotension and bradycardia than salusin- α . Central administration of salusin- β increases blood pressure via release of norepinephrine and arginine-vasopressin. Circulating levels of salusin- α and salusin- β are lower in patients with essential hypertension. Salusin- β exerts more potent mitogenic effects on human vascular smooth muscle cells (VSMCs) and fibroblasts than salusin- α . Salusin- β accelerates inflammatory responses in human endothelial cells and monocyte-endothelial adhesion. Human macrophage foam cell formation is stimulated by salusin- β but suppressed by salusin- α . Chronic salusin- β infusion into apolipoprotein E-deficient mice enhances atherosclerotic lesions; salusin- α infusion reduces lesions. Salusin- β is expressed in proliferative neointimal lesions of porcine coronary arteries after stenting. Salusin- α and salusin- β immunoreactivity have been detected in human coronary atherosclerotic plaques, with dominance of salusin- β in macrophage foam cells, VSMCs, and fibroblasts. Circulating salusin- β levels increase and salusin- α levels decrease in patients with coronary artery disease. These findings suggest that salusin- β and salusin- α may contribute to proatherogenesis and antiatherogenesis, respectively. Increased salusin- β and/or decreased salusin- α levels in circulating blood and vascular tissue are closely linked with atherosclerosis. Salusin- α and salusin- β could be candidate biomarkers and therapeutic targets for atherosclerotic cardiovascular diseases.

Pulmonary arterial hypertension (ascites syndrome) in broilers: a review

Pulmonary arterial hypertension (PAH) syndrome in broilers (also known as ascites syndrome and pulmonary hypertension syndrome) can be attributed to imbalances between cardiac output and the anatomical capacity of the pulmonary vasculature to accommodate ever-increasing rates of blood flow, as well as to an inappropriately elevated tone (degree of constriction) maintained by the pulmonary arterioles. Comparisons of PAH-susceptible and PAH-resistant broilers do not consistently reveal differences in cardiac output, but PAH-susceptible broilers consistently have higher pulmonary arterial pressures and pulmonary vascular resistances compared with PAH-resistant broilers. Efforts clarify the causes of excessive pulmonary vascular resistance have focused on evaluating the roles of chemical mediators of vasoconstriction and vasodilation, as well as on pathological (structural) changes occurring within the pulmonary arterioles (e.g., vascular remodeling and pathology) during the pathogenesis of PAH. The objectives of this review are to (1) summarize the pathophysiological progression initiated by the onset of pulmonary hypertension and culminating in terminal ascites; (2) review recent information regarding the factors contributing to excessively elevated resistance to blood flow through the lungs; (3) assess the role of the immune system during the pathogenesis of PAH; and (4) present new insights into the genetic basis of PAH. The cumulative evidence attributes the elevated pulmonary vascular resistance in PAH-susceptible broilers to an anatomically inadequate pulmonary vascular capacity, to excessive vascular tone reflecting the dominance of pulmonary vasoconstrictors over vasodilators, and to vascular pathology elicited by excessive hemodynamic stress. Emerging evidence also demonstrates that the pathogenesis of PAH includes characteristics of an inflammatory/autoimmune disease involving multifactorial genetic, environmental, and immune system components. Pulmonary arterial hypertension susceptibility appears to be multigenic and may be manifested in aberrant stress sensitivity, function, and regulation of pulmonary vascular tissue components, as well as aberrant activities of innate and adaptive immune system components. Major genetic influences and high heritabilities for PAH susceptibility have been demonstrated by numerous investigators. Selection pressures rigorously focused to challenge the pulmonary vascular capacity readily expose the genetic basis for spontaneous PAH in broilers. Chromosomal mapping continues to identify regions associated with ascites susceptibility, and candidate genes have been identified. Ongoing immunological and genomic investigations are likely to continue generating important new knowledge regarding the fundamental biological bases for the PAH/ascites syndrome.

Role of urotensin-Ⅱ in the pathogenesis of liver cirrhosis and portal hypertension and collateral circulation

Urotensin-Ⅱ (U-Ⅱ) is a somatostatin-like cyclic peptide which has a potent vasoactive effect and can promote vascular reconstruction and hyperplasia. Research shows that UⅡ plays an important role in the development of liver cirrhosis and portal hypertension. UⅡ influences intrahepatic resistance and splanchnic hemodynamics through a variety of pathways, causing portal hypertension and participating in the formation of esophageal and gastric varices. UⅡ receptor antagonists can reduce portal pressure in cirrhotic rats, but this finding need to be confirmed clinically.

Genetic and pharmacological manipulation of urotensin II ameliorate the metabolic and atherosclerosis sequalae in mice

OBJECTIVE

Urotensin II (UII) is a potent vasoactive peptide that binds to the urotensin receptor-coupled receptor-14 (known as UT) and exerts a wide range of actions in humans and experimental animals. We tested the hypothesis that UII gene deletion or UT blockade ameliorate experimental atherosclerosis.

METHODS AND RESULTS

We observed a significant reduction in weight gain, visceral fat, blood pressure, circulating plasma lipids, and proatherogenic cytokines and improvement of glucose tolerance in UII knockout mice compared with wild type (P<0.05). Deletion of UII after an apolipoprotein E knockout resulted in a significant reduction in serum cytokines, adipokines, and aortic atherosclerosis compared with apolipoprotein E knockout mice. Similarly, treatment of apolipoprotein E knockout mice fed on high-fat diet with the UT antagonist SB657510A reduced weight gain, visceral fat, and hyperlipidemia and improved glucose tolerance (P<0.05) and attenuated the initiation and progression of atherosclerosis. The UT antagonist also decreased aortic extracellular signal-regulated kinase 1/2 phosphorylation and oxidant formation and serum level of cytokines (P<0.05).

CONCLUSIONS

These findings demonstrate for the first time the role of UII gene deletion in atherosclerosis and suggest that the use of pharmaceutical agents aimed at blocking the UII pathway may provide a novel approach in the treatment of atherosclerosis and its associated precursors such as obesity, hyperlipidemia, diabetes mellitus, and hypertension.

Effects of urotensin II on functional activity of late endothelial progenitor cells

Urotensin II (UII) is a potent vasoactive cyclic peptide which has multiple effects on the cardiovascular system. However, the effects of UII on late endothelial progenitor cells (EPCs) are still unclear. The aim of the present study is to investigate whether UII influences the functional activity of late EPCs. Late EPCs were isolated from human umbilical cord blood by Ficoll density gradient centrifugation and treated with UII (10(-10), 10(-9), 10(-8), 10(-7) and 10(-6)M), or vehicle control. Expression of urotensin II receptor (UT) in late EPCs was confirmed by indirect immunofluorescence staining. Late EPCs proliferation, migration and in vitro vasculogenesis activity were assayed with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, transwell chamber assay, and matrigel tube formation assay. Late EPCs adhesive assay was performed by replating cells on fibronectin-coated dishes, and then adherent cells were counted. Incubation with UII increased the migratory, adhesive and in vitro vasculogenesis capacity and inhibited the proliferative activity of late EPCs. Furthermore, these UII-mediated effects on late EPCs were attenuated by pretreatment with the UT antagonist urantide. These findings indicate that UII may exert multiple effects on functional activity of late EPCs through UT.

Urotensin-II-stimulated expression of pro-angiogenic factors in human vascular endothelial cells

Urotensin-II (U-II) is an endogenous peptide recently characterized as a "nonclassic" pro-angiogenic cytokine. In fact, human vascular endothelial cells express the U-II receptor and exhibit a strong in vitro angiogenic response to the peptide, which was specifically triggered by the binding of U-II to its receptor and involved the activation of ERK1/2 and PI3K/Akt signaling pathways. Moreover, available studies, designed to investigate the pro-angiogenic effect quite shortly following U-II stimulation, suggested that the angiogenic action of the peptide was direct and not associated with an increased expression of vascular endothelial growth factor (VEGF) and/or its receptors. In the present study, the expression of three pro-angiogenic factors, namely VEGF, endothelin-1, and adrenomedullin, was studied in human umbilical vein endothelial cells (HUVEC) for longer times of U-II stimulation. RT-PCR and Western blot indicated that in HUVEC, exposed for at least 24h to U-II, the expression of the three angiogenic molecules was significantly increased at both mRNA and protein level, opening the possibility that U-II, not only could exert a direct stimulation of an angiogenic phenotype in endothelial cells quite shortly following exposure to the peptide, but could also further enhance the process indirectly by inducing in the cells a delayed production of other pro-angiogenic factors. Interestingly, a preliminary analysis of the time course of the in vitro capillary-like pattern formation was consistent with this view, suggesting a two phase temporal dynamics of the process.

Erythropoietin Increases Expression and Function of Transient Receptor Potential Canonical 5 Channels

Hypertension is a common complication in hemodialysis patients during erythropoietin (EPO) treatment. The underlying mechanisms of EPO-induced hypertension still remain to be determined. Increased transient receptor potential canonical (TRPC) channels have been associated with hypertension. Now, TRPC gene expression was investigated using quantitative real-time RT-PCR and immunoblotting in cultured human endothelial cells and in monocytes from hemodialysis patients. EPO dose-dependently increased TRPC5 mRNA in endothelial cells. EPO increased TRPC5 mRNA stability, that is, EPO prolonged the half-life period for TRPC5 mRNA from 16 hours (control) to 24 hours ( P <0.05). The poly(A) tail length was measured by rapid amplification of cDNA ends-poly(A) test. Increased TRPC5 mRNA stability was attributed to longer 3′ poly(A) tail lengths after EPO administration. EPO also significantly increased TRPC5 channel protein abundance by 70% ( P <0.05). Whole-cell patch clamp showed that angiotensin II–induced, TRPC5-mediated currents were dramatically increased in endothelial cells treated with EPO. Fluorescent dye techniques confirmed that increased calcium influx after EPO treatment was abolished after TRPC5 knockdown ( P <0.05). EPO also significantly increased intracellular reactive oxygen species production. Knockdown of TRPC5 alleviated EPO-induced reactive oxygen species generation in endothelial cells ( P <0.05). In vivo, EPO-treated hemodialysis patients showed significantly increased amounts of TRPC5 mRNA in monocytes compared with EPO-free hemodialysis patients (6.0±2.4 [n=12] versus 1.0±0.5 [n=9]; P <0.01). Patients undergoing EPO treatment also showed significantly elevated systolic blood pressure (160±7 versus 139±6 mm Hg; P <0.05). Our findings suggest that upregulated functional TRPC5 gene may be one cause of EPO-induced hypertension in patients with chronic kidney disease.

Urantide alleviates monocrotaline induced pulmonary arterial hypertension in Wistar rats

Pulmonary arterial hypertension (PAH) is a serious disorder with poor prognosis. Urotensin II (UII) has been confirmed to be powerful vasoconstrictor than endothelin-1, which may play an important role in PAH development. The aim of this study is to observe the effects of urantide, a UII receptor antagonist, on monocrotaline (MCT) induced PAH in rats. 60 male Wistar rats were divided into six groups. For early treatment experiment, rats were divided into normal control group, MCT(4w) model group (MCT + saline × 3 wks from the 8th day of MCT injection) and urantide early treatment group (MCT + urantide 10 μg/kg/d × 3 wks, 1 week after MCT injection once). For late treatment experiment, rats were divided as controls, MCT(6w) model group (MCT + saline × 2 wks, 4 weeks after MCT injection once) and urantide late treatment group (MCT + urantide 10 μg/kg/d × 2 wks, 4 weeks after MCT injection once). At the end of experiments, mean pulmonary arterial pressures (mPAP) and mean blood pressure (MBP) of rats in each group were measured by catheterization. Right ventricular weight ratio was also weighed. Relaxation effects of urantide on intralobar pulmonary arterial rings of normal control and MCT(4w) model rats were investigated. Pulmonary artery remodeling was detected by hematoxylin and eosin (HE) staining and immunohistochemistry analysis. Serum nitric oxide (NO) levels in all six groups were assayed by ELISA kits. Urantide markedly reduced the mPAP levels of MCT induced PAH in both early and late treatment groups. It didn't change the MBP. Urantide dose-dependently relaxed the pulmonary arterial rings of normal control and MCT(4w) model rats. Moreover, N(G)-Nitro-l-arginine Methyl Ester (l-NAME) blocked the dilation response induced by urantide. In addition, urantide inhibited the pulmonary vascular remodeling remarkably. Serum NO level elevated in both early and late treatment rats with urantide infusion. These results suggest that urantide effectively alleviated MCT induced rats PAH may through relaxing pulmonary arteries and inhibiting pulmonary vascular remodeling. NO pathway might be one of the mechanisms in urantide induced pulmonary artery dilation. Thus, it is expected that urantide may be a novel therapy for PAH.

Advances in understanding the role of the UII/UT system in the pathogenesis of portal hypertension

Urotensin II (UII), a vasoactive peptide with structural similarity to somatostatin, is the most potent vasoconstrictor known in systemic resistance vessels and has multiple biological effects related to a variety of human diseases. Numerous studies have found that UII and its receptor (UT) play an important role in the pathogenesis of portal hypertension. This paper reviews the recent advances in understanding the role of the UII/UT system in the pathogenesis of portal hypertension.

Urotensin II alters vascular reactivity in animals subjected to volume overload

Congestive heart failure (CHF) alters vascular reactivity and up regulates in urotensin II (UTII), a potent vasoactive peptide. The aim of this study was to investigate the interaction between CHF and UTII in altering vascular reactivity in a rat model of volume overload heart failure. Animals were divided into 4 groups: control, UTII infused (UTII), volume overload only (VO) or volume overload+UTII (VO+UTII). Volume overload was established by the formation of an aortocaval fistula. Following fistula formation animals were administered UTII at a rate of 300 pmol/kg/h for 4 weeks subcutaneously with mini-osmotic pumps. Thoracic aorta rings, with/without endothelium, were subjected to cumulative dose-responses to phenylephrine, sodium nitroprusside (SNP), acetylcholine (ACH), UTII, and the Rho-kinase inhibitor HA-1077. Aortas from VO animals exhibited increased sensitivity to phenylephrine and UTII with a decreased relaxation response to ACH and HA-1077. Aortas from animals subjected to chronic UTII with volume overload (VO + UTII) retained their sensitivity to phenylephrine and UTII while they improved their relaxation to HA-1077 but not ACH. The constrictive response to UTII was dose-dependent and augmented at concentrations <0.01 μM in VO animals. The changes in vascular reactivity paralleled an elevation of both the UTII and α(1A)-adrenergic receptor while the Rho and Rho-kinase signalling proteins were diminished. We found that volume overload increased sensitivity to the vasoconstrictor agents that was inversely related to changes in the Rho-kinase expression. The addition of UTII with VO reversed the constrictive vascular response through alterations in the Rho-kinase signalling pathway.

Urotensin II-induced signaling involved in proliferation of vascular smooth muscle cells

The urotensin II receptor, bound by the ligand urotensin II, generates second messengers, ie, inositol triphosphate and diacylglycerol, which stimulate the subsequent release of calcium (Ca²⁺) in vascular smooth muscle cells. Ca²⁺ influx leads to the activation of Ca²⁺-dependent kinases (CaMK) via calmodulin binding, resulting in cellular proliferation. We hypothesize that urotensin II signaling in pulmonary arterial vascular smooth muscle cells (Pac1) and primary aortic vascular smooth muscle cells (PAVSMC) results in phosphorylation of Ca²⁺/calmodulin-dependent kinases leading to cellular proliferation. Exposure of Pac1 cultures to urotensin II increased intracellular Ca²⁺, subsequently activating Ca²⁺/calmodulin-dependent kinase kinase (CaMKK), and Ca²⁺/calmodulin-dependent kinase Type I (CaMKI), extracellular signal-regulated kinase (ERK 1/2), and protein kinase D. Treatment of Pac1 and PAVSMC with urotensin II increased proliferation as measured by ³H-thymidine uptake. The urotensin II-induced increase in ³H-thymidine incorporation was inhibited by a CaMKK inhibitor. Taken together, our results demonstrate that urotensin II stimulation of smooth muscle cells leads to a Ca²⁺/calmodulin-dependent kinase-mediated increase in cellular proliferation.

Role of urotensin II in health and disease

Urotensin II (UII) is an 11 amino acid cyclic peptide originally isolated from the goby fish. The amino acid sequence of UII is exceptionally conserved across most vertebrate taxa, sharing structural similarity to somatostatin. UII binds to a class of G protein-coupled receptor known as GPR14 or the urotensin receptor (UT). UII and its receptor, UT, are widely expressed throughout the cardiovascular, pulmonary, central nervous, renal, and metabolic systems. UII is generally agreed to be the most potent endogenous vasoconstrictor discovered to date. Its physiological mechanisms are similar in some ways to other potent mediators, such as endothelin-1. For example, both compounds elicit a strong vascular smooth muscle-dependent vasoconstriction via Ca2+ release. UII also exerts a wide range of actions in other systems, such as proliferation of vascular smooth muscle cells, fibroblasts, and cancer cells. It also 1) enhances foam cell formation, chemotaxis of inflammatory cells, and inotropic and hypertrophic effects on heart muscle; 2) inhibits insulin release, modulates glomerular filtration, and release of catecholamines; and 3) may help regulate food intake and the sleep cycle. Elevated plasma levels of UII and increased levels of UII and UT expression have been demonstrated in numerous diseased conditions, including hypertension, atherosclerosis, heart failure, pulmonary hypertension, diabetes, renal failure, and the metabolic syndrome. Indeed, some of these reports suggest that UII is a marker of disease activity. As such, the UT receptor is emerging as a promising target for therapeutic intervention. Here, a concise review is given on the vast physiologic and pathologic roles of UII.

Relation of urotensin II levels to lone atrial fibrillation

Human urotensin II (U-II) is an 11-amino acid peptide that plays an important role in hypertension and coronary artery disease. However, because there is no information on the role of U-II in the development of lone atrial fibrillation (AF), the goal of this study was to clarify the role of U-II in the development of lone AF. The study enrolled 42 patients (42.1 +/- 4.0 years old) with paroxysmal lone AF and 30 healthy gender- and age-matched control subjects. The following factors were measured in blood collected after an overnight fast: glucose, total cholesterol, low-density lipoprotein cholesterol, triglycerides, high-sensitivity C-reactive protein (hs-CRP), U-II, and vascular cell adhesion molecule 1 (VCAM-1). U-II levels were significantly higher in the lone AF than in the control group (4.09 +/- 1.28 vs 2.85 +/- 0.63 ng/ml, p <0.001). VCAM-1 levels were also higher in the lone AF than in the control group (337 +/- 250 vs 218 +/- 117 ng/ml, p = 0.018). In addition, hs-CRP levels were higher in the lone AF than in the control group (0.88 +/- 0.29 mg/dl vs 0.67 +/- 0.31 mg/dl, p = 0.004). Multivariate logistic regression analysis that included U-II, VCAM-1, hs-CP, and conventional AF risk factors showed that only U-II and hs-CRP were independently associated with lone AF. In conclusion, the results indicate that increased levels of U-II are associated with the development of lone AF. Additional studies will be necessary to determine whether the elevation of U-II is the cause or the result of AF.

Urotensin II modulates hepatic fibrosis and portal hemodynamic alterations in rats

The influence of circulating urotensin II (UII) on liver disease and portal hypertension is unknown. We aimed to evaluate whether UII executes a pathogenetic role in the development of hepatic fibrosis and portal hypertension. UII was administered by continuous infusion over 4 wk in 20 healthy rats divided into three treatment groups, controls (saline, n = 7), low dose (UII, 1 nmol x kg(-1) x h(-1), n = 8), and high dose (UII, 3 nmol x kg(-1) x h(-1), n = 5). Hemodynamic parameters and morphometric quantification of fibrosis were assessed, and profibrotic cytokines and fibrosis markers were assayed in hepatic tissue. UII induced a significant dose-dependent increase in portal venous pressure (5.8 +/- 0.4, 6.4 +/- 0.3, and 7.6 +/- 0.7, respectively, P = 0.03). High-dose UII infusion was associated with an increase in hepatic transcript for transforming growth factor-beta (P < 0.05) and platelet-derived growth factor-beta (P = 0.06). Liver tissue hydroxyproline was elevated in the high-dose group (P < 0.05). No systemic hemodynamic alterations were noted. We concluded that UII infusion elevates portal pressure and induces hepatic fibrosis in normal rats. This response may be mediated via induction of fibrogenic cytokines. These findings have pathophysiological implications in human liver disease where increased plasma UII levels have been observed.

Transient receptor potential canonical type 3 channels and blood pressure in humans

OBJECTIVE

There is evidence that transient receptor potential canonical type 3 (TRPC3) cation channels are involved in the regulation of blood pressure, but this has not been studied using human renal tissue. We tested the hypothesis that the expression of TRPC3 in human renal tissue is associated with blood pressure in patients.

MATERIAL AND METHODS

TRPC3 was detected in cultured human endothelial cells and in vascular endothelium cells from human renal tissue by immunoblotting, immunohistochemistry, and quantitative real-time reverse transcriptase-PCR. The changes of TRPC3 and vascular endothelial growth factor receptor type 2 expression in cultured human endothelial cells were measured after administration of vascular endothelial growth factor isoform 121.

RESULTS

In cultured human endothelial cells, vascular endothelial growth factor isoform 121 significantly reduced TRPC3 expression by 57% and vascular endothelial growth factor receptor type 2 by 70%. This reduction was partly blocked by phosphatidylinositol 3-kinase inhibitors, wortmannin, or LY294002. Downregulation of TRPC3 channel expression was associated with reduced calcium influx. The changes of calcium influx could be abolished by the inhibitor of TRPC channels, 2-aminoethoxydiphenylborane, pointing to their functional importance. TRPC3 expression was significantly higher in patients with SBP more than 140 mmHg compared with patients with SBP of 140 mmHg or less (0.00181 +/- 0.00059 versus 0.00037 +/- 0.00012 arbitrary units; P < 0.01).

CONCLUSION

The data support the hypothesis that TRPC3 expression in human renal tissue including vascular endothelium is associated with blood pressure regulation in humans.

Hypertension and myocardial ischemia

Detailed studies over the past 30 years have built up an impressive evidence base for the presence of myocardial ischemia in patients who have hypertension. This relationship ranges from the obvious association with obstructive coronary artery disease to mechanisms related to hemodynamic, microcirculatory, and neuroendocrine abnormalities. All of these factors serve to destabilize the critical balance between myocardial oxygen supply and demand. We have at our disposal a range of sophisticated investigations that allow us to demonstrate the presence and extent of the ischemia and therefore to target specific therapies to reduce the risk to these patients. Achieving target BP and managing all reversible components of the patient's cardiovascular risk status reduce to a minimum the clinical sequelae of myocardial ischemia in this vulnerable population..

Pro-angiogenic activity of Urotensin-II on different human vascular endothelial cell populations

Urotensin-II (U-II), along its receptor UT, is widely expressed in the cardiovascular system, where it exerts regulatory actions under both physiological and pathological conditions. In the present study, human vascular endothelial cells (EC) from one arterious and three venous vascular beds were used to investigate in vitro their heterogeneity in terms of expression of U-II and UT and of angiogenic response to the peptide. Real-time PCR and immunocytochemistry demonstrated the expression of UT, as mRNA and protein, in all the EC populations investigated. U-II, on the contrary, was detectable only in EC from aorta and umbilical vein. U-II did not affect the proliferation rate of adult human EC, but induced a moderate proliferative effect on EC from human umbilical vein. When tested in the Matrigel assay, however, all EC exhibited a strong angiogenic response to the peptide, comparable to that of fibroblast growth factor-2 (FGF-2) and it was not associated to an increased expression of vascular endothelial growth factor (VEGF) and/or its receptors. The angiogenic effect of U-II was abolished by the UT antagonist palosuran. Overall, these data suggest that U-II, in addition to the well known role in the regulation of cardiovascular function, also exert a specific angiogenic activity.

Increased TRPC3 expression in vascular endothelium of patients with malignant hypertension

An increased expression of transient receptor potential canonical type 3 (TRPC3) cation channels has been proposed as one of the factors contributing to the pathogenesis of hypertension. To test that hypothesis we compared the expression of TRPC3 and TRPC6 as an endogenous control in human vascular endothelium of preglomerular arterioles in kidney biopsies from six patients with malignant hypertension and from four patients with diarrhea-associated hemolytic-uremic syndrome. Patients with malignant hypertension showed significantly higher systolic blood pressure and more prominent expression of TRPC3 in vascular endothelium of preglomerular arterioles compared to patients with hemolytic-uremic syndrome. The expression of TRPC6 was not different between the two groups. The study supports the hypothesis that the increased expression of TRPC3 is associated with malignant hypertension in humans.

Acute neurohumoral modulation of diastolic function

Diastole plays a central role in cardiovascular homeostasis. Its two main determinants, myocardial relaxation and passive properties of the ventricular wall, are nowadays regarded as physiological mechanisms susceptible of active modulation. Furthermore, diastolic dysfunction and heart failure with normal ejection fraction (previously called diastolic heart failure) are two subjects of major clinical relevance and an intense area of research. The role of several neurohumoral mediators like angiotensin-II and endothelin-1 on the modulation of diastolic function was systematically described as having only chronic deleterious effects such as cardiac hypertrophy and fibrosis. However, over the last years a growing body of evidence described a new role for several peptides on the acute modulation of diastolic function. In the acute setting, some of these mediators may have the potential to induce an adaptive cardiac response. In this review, we describe the role of angiotensin-II, endothelin-1, nitric oxide, urotensin-II and ghrelin on the acute modulation of diastolic function, emphasizing its pathophysiological relevance. Only a thorough understanding of diastolic physiology as well as its active modulation, both in the acute and chronic settings, will improve our knowledge on diastolic dysfunction and allow us to solve the enigmas of heart failure with normal ejection fraction.

Urotensin II in cardiovascular regulation

Cardiovascular function is modulated by neuronal transmitters, circulating hormones, and factors that are released locally from tissues. Urotensin II (UII) is an 11 amino acid peptide that stimulates its' obligatory G protein coupled urotensin II receptors (UT) to modulate cardiovascular function in humans and in other animal species, and has been implicated in both vasculoprotective and vasculopathic effects. For example, tissue and circulating concentrations of UII have been reported to increase in some studies involving patients with atherosclerosis, heart failure, hypertension, preeclampsia, diabetes, renal disease and liver disease, raising the possibility that the UT receptor system is involved in the development and/or progression of these conditions. Consistent with this hypothesis, administration of UT receptor antagonists to animal models of cardiovascular disease have revealed improvements in cardiovascular remodelling and hemodynamics. However, recent studies have questioned this contributory role of UII in disease, and have instead postulated a protective effect on the cardiovascular system. For example, high concentrations of circulating UII correlated with improved clinical outcomes in patients with renal disease or myocardial infarction. The purpose of this review is to consider the regulation of the cardiovascular system by UII, giving consideration to methodologies for measurement of plasma concentrations, sites of synthesis and triggers for release.

Increased plasma urotensin-II levels are associated with diabetic retinopathy and carotid atherosclerosis in Type 2 diabetes

Human U-II (urotensin-II), the most potent vasoconstrictor peptide identified to date, is associated with cardiovascular disease. A single nucleotide polymorphism (S89N) in the gene encoding U-II (UTS2) is associated with the onset of Type 2 diabetes and insulin resistance in the Japanese population. In the present study, we have demonstrated a relationship between plasma U-II levels and the progression of diabetic retinopathy and vascular complications in patients with Type 2 diabetes. Eye fundus, IMT (intima-media thickness) and plaque score in the carotid artery, BP (blood pressure), FPG (fasting plasma glucose), HbA(1c) (glycated haemoglobin), U-II, angiogenesis-stimulating factors, such as VEGF (vascular endothelial growth factor) and heregulin-beta(1), and lipid profiles were determined in 64 patients with Type 2 diabetes and 24 non-diabetic controls. FPG, HbA(1c) and VEGF levels were significantly higher in patients with Type 2 diabetes than in non-diabetic controls. Diabetes duration, insufficient glycaemic and BP control, plasma U-II levels, IMT, plaque score and nephropathy grade increased significantly across the subjects as follows: non-diabetic controls, patients with Type 2 diabetes without retinopathy (group N), patients with Type 2 diabetes with simple (background) retinopathy (group A) and patients with Type 2 diabetes with pre-proliferative and proliferative retinopathy (group B). The prevalence of obesity and smoking, age, low-density lipoprotein, triacylglycerols (triglycerides) and heregulin-beta(1) were not significantly different among the four groups. In all subjects, U-II levels were significantly positively correlated with IMT, FPG, and systolic and diastolic BP. Multiple logistic regression analysis revealed that, of the above parameters, U-II levels alone had a significantly independent association with diabetic retinopathy. In conclusion, the results of the present study provide the first evidence that increased plasma U-II levels may be associated with the progression of diabetic retinopathy and carotid atherosclerosis in patients with Type 2 diabetes.

Serum salusin-alpha levels are decreased and correlated negatively with carotid atherosclerosis in essential hypertensive patients

Salusin-alpha is a new bioactive peptide with mild hypotensive and bradycardic effects. Our recent study showed that salusin-alpha suppresses foam cell formation in human monocyte-derived macrophages by down-regulating acyl-CoA:cholesterol acyltransferase-1, contributing to its anti-atherosclerotic effect. To clarify the clinical implications of salusin-alpha in hypertension and its complications, we examined the relationship between serum salusin-alpha levels and carotid atherosclerosis in hypertensive patients. The intima-media thickness (IMT) and plaque score in the carotid artery, blood pressure, serum levels of salusin-alpha, and atherosclerotic parameters were determined in 70 patients with essential hypertension and in 20 normotensive controls. There were no significant differences in age, gender, body mass index, fasting plasma glucose level, or serum levels of high-sensitive C-reactive protein, high- or low-density lipoprotein (LDL) cholesterol, small dense LDL, triglycerides, lipoprotein(a), or insulin between the two groups. Serum salusin-alpha levels were significantly lower in hypertensive patients than in normotensive controls. The plasma urotensin-II level, maximal IMT, plaque score, systolic and diastolic blood pressure, and homeostasis model assessment for insulin resistance (HOMA-IR) were significantly greater in hypertensive patients than in normotensive controls. In all subjects, maximal IMT was significantly correlated with age, systolic blood pressure, LDL cholesterol, urotensin-II, salusin-alpha, and HOMA-IR. Forward stepwise multiple linear regression analysis revealed that salusin-alpha levels had a significantly independent and negative association with maximal IMT. Serum salusin-alpha levels were significantly lower in accordance with the severity of plaque score. Our results suggest that the decrease in serum salusin-alpha, an anti-atherogenic peptide, may be associated with carotid atherosclerosis in hypertensive patients.

Urotensin II induces phenotypic differentiation, migration, and collagen synthesis of adventitial fibroblasts from rat aorta

BACKGROUND

Urotensin II is a new potent vasoconstrictor. Nevertheless, little is known about its effects on the activation of adventitial fibroblasts.

OBJECTIVE

To explore the effects of urotensin II on phenotypic differentiation, migration, and collagen I synthesis of rat aortic adventitial fibroblasts.

METHODS

Growth-arrested adventitial fibroblasts were incubated in serum-free medium with urotensin II and some inhibitors of signal transduction pathways. The alpha-smooth muscle-actin expression, collagen I synthesis and migration of adventitial fibroblasts induced by urotensin II were evaluated by western blot, enzyme-linked immunosorbant assay, and the transwell technique, respectively.

RESULTS

Urotensin II induced the [alpha]-smooth muscle-actin expression in a dose-dependent and time-dependent manner, with maximal effect at a concentration of 10(-8) mol/l at 24 h (79.9%); it also caused a dose-dependent increase in collagen I synthesis, with maximal effect at a concentration of 10(-7) mol/l (42.6%). The Ca2+ channel blocker nicardipine (10(-5) mol/l), protein kinase C inhibitor H7 (10(-5) mol/l), Rho protein kinase inhibitor Y-27632 (10(-5) mol/l), calcineurin inhibitor cyclosporine A (10(-5) mol/l), and mitogen-activated protein kinase inhibitor PD98059 (10(-5) mol/l) inhibited urotensin II-induced increases in [alpha]-smooth muscle-actin expression and collagen synthesis. Meanwhile, urotensin II stimulated the migration of adventitial fibroblasts dose dependently, with maximal effect at a concentration of 10(-8) mol/l, which was 5.7-fold greater than that of the control. This effect could also be inhibited by PD98059, H7, cyclosporine A, and Y-27632 but not nicardipine.

CONCLUSION

Urotensin II may stimulate adventitial fibroblasts phenotypic conversion, migration, and collagen I synthesis through the protein kinase C, mitogen-activated protein kinase, calcineurin, Rho kinase, and/or Ca2+ signal transduction pathways, contributing to the development of vascular remodeling through adventitial fibroblasts activation.

Urotensin-II and cardiovascular remodeling

Urotensin-II (U-II), a cyclic undecapeptide, and its receptor, UT, have been linked to vascular and cardiac remodeling. In patients with coronary artery disease (CAD), it has been shown that U-II plasma levels are significantly greater than in normal patients and the severity of the disease is increased proportionally to the U-II plasma levels. We showed that U-II protein and mRNA levels were significantly elevated in the arteries of patients with coronary atherosclerosis in comparison to healthy arteries. We observed U-II expression in endothelial cells, foam cells, and myointimal and medial vSMCs of atherosclerotic human coronary arteries. Recent studies have demonstrated that U-II acts in synergy with mildly oxidized LDL inducing vascular smooth muscle cell (vSMC) proliferation. Additionally, U-II has been shown to induce cardiac fibrosis and cardiomyocyte hypertrophy leading to cardiac remodeling. When using a selective U-II antagonist, SB-611812, we demonstrated a decrease in cardiac dysfunction including a reduction in cardiomyocyte hypertrophy and cardiac fibrosis. These findings suggest that U-II is undoubtedly a potential therapeutic target in treating cardiovascular remodeling.

Human urotensin II induces tissue factor and cellular adhesion molecules expression in human coronary endothelial cells: an emerging role for urotensin II in cardiovascular disease

BACKGROUND

Human urotensin II is an 11-aminoacid peptide with a controversial role in the human cardiovascular system. Indeed, urotensin effects on vascular reactivity and in heart failure are well documented, while its potential role in the pathophysiology of athero-thrombosis is still unknown. This study investigates the effects of urotensin on tissue factor (TF) and VCAM-1/ICAM-1 expression in human coronary endothelial cells (HCAECs).

METHODS AND RESULTS

Urotensin induced TF-mRNA transcription as demonstrated by real time PCR and expression of TF that was functionally active as demonstrated by procoagulant activity assay. In addition, urotensin induced expression of VCAM-1 and ICAM-1 as demonstrated by FACS analysis. VCAM-1 and ICAM-1 were functionally active because they increased leukocyte adhesivity to HCAECs. Urotensin-induced expression of TF and of VCAM-1/ICAM-1 was mediated through the Rho A-activation of the transcription factor, NF-kappaB, as demonstrated by EMSA. Indeed, lovastatin, an HMG-CoA reductase inhibitor, by modulating the Rho activation, and NF-kappaB inhibitors, suppressed the urotensin effects on TF and CAMs.

CONCLUSIONS

Data of the present study, although in vitro, describe the close relationship existing between urotensin II and athero-thrombosis, providing for the first time support for the view that this peptide might have not only vasoactive functions but it might be an effector molecule able to induce a pro-atherothrombotic phenotype in cells of the coronary circulation. Although future studies are required to clarify whether these mechanisms are also important in the clinical setting, this report supports an emerging new role for urotensin II in the pathogenesis and progression of cardiovascular disease.

Increased circulating urotensin II in cirrhosis: potential implications in liver disease

Urotensin II (UII) is a potent vasoactive mediator which, through interaction with a specific G-protein coupled receptor, can result in either a vasoconstrictive or vasodilatory response. In addition to its effect upon vascular tone, UII possess mitogenic and fibrogenic potential. The influence of UII on vascular tone is to some degree both species-specific and disease-specific. Increased circulating UII levels have been documented in subjects with liver cirrhosis although the significance of this finding with regards to the development of chronic liver disease and portal hypertension has yet to be fully elucidated. In this review we focus on the potential relevance of UII as a vasoactive mediator in the chronic liver disease population and postulate as to the site of overproduction of UII.

Liberation of urotensin II from the teleost urophysis: an historical overview

During the past 20 years, urotensin II (UII) has progressed from being a peptide synthesized only in the urophysis of the caudal neurosecretory system of teleost fish to being considered an important physiological regulator in mammals with implications for the pathogenesis of a range of human cardiovascular and renal diseases. The "liberation" of UII from the urophysis was a gradual process and involved the sequential realization that (a) UII is present not only in the urophysis but also in the central nervous systems (CNS) of teleosts, (b) UII peptides, similar in structure to the urophysial peptides, are present in the diffuse caudal neurosecretory systems and/or CNS of species less evolutionarily advanced than teleosts, including Agnatha, thereby showing that UII is a phylogenetically ancient peptide, (c) UII is present in the brain and spinal cord of a tetrapod, the green frog Rana ridibunda, and (d) the UII gene and its specific receptor (GPR14/UT) are expressed in the CNS and certain peripheral tissues of mammals, including the human. The discovery that the genomes of mammals contain an additional gene encoding a UII-related peptide (URP) and the availability of highly effective peptide and non-peptide antagonists to investigate the role of UII in human physiology and pathophysiology ensure that the peptide will remain "center stage" for several years to come.