Cardiac hypertrophy and hypertension

Cholecystokinin Expression in the Development of Myocardial Hypertrophy

BACKGROUND

Expression of cholecystokinin is found in myocardial tissues as a gastrointestinal hormone and may be involved in cardiovascular regulation. However, it is unclear whether there is an increase in cholecystokinin expression in myocardial hypertrophy progression induced by abdominal aortic constriction. The study is aimed at exploring the relationship between cholecystokinin expression and myocardial hypertrophy.

METHODS

We randomly divided the 70 Sprague-Dawley rats into two groups: the sham operation group and the abdominal aortic constriction group. The hearts of rats were measured by echocardiography, and myocardial tissues and blood were collected at 4 weeks, 8 weeks, and 12 weeks after surgery. Morphological changes were assessed by microscopy. The cholecystokinin expression was evaluated by immunochemistry, Western blotting, quantitative real-time polymerase chain reaction, and enzyme-linked immunosorbent assay.

RESULTS

The relative protein levels of cholecystokinin were significantly increased in the abdominal aortic constriction groups compared with the corresponding sham operation groups at 8 weeks and 12 weeks. The cholecystokinin mRNA in the abdominal aortic constriction groups was significantly higher than the time-matched sham operation groups. Changes in the left ventricular wall thickness were positively correlated with the relative protein levels of cholecystokinin and the mRNA of cholecystokinin.

CONCLUSIONS

The development of myocardial hypertrophy can affect the cholecystokinin expression of myocardial tissues.

Obligatory Role for B Cells in the Development of Angiotensin II–Dependent Hypertension

Clinical hypertension is associated with raised serum IgG antibodies. However, whether antibodies are causative agents in hypertension remains unknown. We investigated whether hypertension in mice is associated with B-cell activation and IgG production and moreover whether B-cell/IgG deficiency affords protection against hypertension and vascular remodeling. Angiotensin II (Ang II) infusion (0.7 mg/kg per day; 28 days) was associated with (1) a 25% increase in the proportion of splenic B cells expressing the activation marker CD86, (2) an 80% increase in splenic plasma cell numbers, (3) a 500% increase in circulating IgG, and (4) marked IgG accumulation in the aortic adventitia. In B-cell–activating factor receptor–deficient (BAFF-R −/− ) mice, which lack mature B cells, there was no evidence of Ang II–induced increases in serum IgG. Furthermore, the hypertensive response to Ang II was attenuated in BAFF-R −/− (Δ30±4 mm Hg) relative to wild-type (Δ41±5 mm Hg) mice, and this response was rescued by B-cell transfer. BAFF-R −/− mice displayed reduced IgG accumulation in the aorta, which was associated with 80% fewer aortic macrophages and a 70% reduction in transforming growth factor-β expression. BAFF-R −/− mice were also protected from Ang II–induced collagen deposition and aortic stiffening (assessed by pulse wave velocity analysis). Finally, like BAFF-R deficiency, pharmacological depletion of B cells with an anti-CD20 antibody attenuated Ang II–induced hypertension by ≈35%. Hence, these studies demonstrate that B cells/IgGs are crucial for the development of Ang II–induced hypertension and vessel remodeling in mice. Thus, B-cell–targeted therapies—currently used for autoimmune diseases—may hold promise as future treatments for hypertension.

Celecoxib prevents pressure overload-induced cardiac hypertrophy and dysfunction by inhibiting inflammation, apoptosis and oxidative stress

To explore the effects of celecoxib on pressure overload‐induced cardiac hypertrophy (CH), cardiac dysfunction and explore the possible protective mechanisms. We surgically created abdominal aortic constrictions (AAC) in rats to induce CH. Rats with CH symptoms at 4 weeks after surgery were treated with celecoxib [2 mg/100 g body‐weight(BW)] daily for either 2 or 4 weeks. Survival rate, blood pressure and cardiac function were evaluated after celecoxib treatment. Animals were killed, and cardiac tissue was examined for morphological changes, cardiomyocyte apoptosis, fibrosis, inflammation and oxidative stress. Four weeks after AAC, rats had significantly higher systolic, diastolic and mean blood pressure, greater heart weight and enlarged cardiomyocytes, which were associated with cardiac dysfunction. Thus, the CH model was successfully established. Two weeks later, animals had impaired cardiac function and histopathological abnormalities including enlarged cardiomyocytes and cardiac fibrosis, which were exacerbated 2 weeks later. However, these pathological changes were remarkably prevented by the treatment of celecoxib, independent of preventing hypertension. Mechanistic studies revealed that celecoxib‐induced cardiac protection against CH and cardiac dysfunction was due to inhibition of apoptosis via the murine double mimute 2/P53 pathway, inhibition of inflammation via the AKT/mTOR/NF‐κB pathway and inhibition of oxidative stress via increases in nuclear factor E2‐related factor‐2‐mediated gene expression of multiple antioxidants. Celecoxib suppresses pressure overload‐induced CH by reducing apoptosis, inflammation and oxidative stress.

Serum uric acid is associated with left ventricular hypertrophy independent of serum parathyroid hormone in male cardiac patients

Background

Several studies have shown that serum uric acid (UA) is associated with left ventricular (LV) hypertrophy. Serum levels of parathyroid hormone (PTH), which has bbe shown to be correlated with UA, is also known to be associated with cardiac hypertrophy; however, whether the association between UA and cardiac hypertrophy is independent of PTH remains unknown.

Purpose

We investigated whether the relationship between serum uric acid (UA) and LV hypertrophy is independent of intact PTH and other calcium-phosphate metabolism-related factors in cardiac patients.

Methods and Results

In a retrospective study, the association between UA and left ventricular mass index was assessed among 116 male cardiac patients (mean age 65±12 years) who were not taking UA lowering drugs. The median UA value was 5.9 mg/dL. Neither age nor body mass index differed significantly among the UA quartile groups. Patients with higher UA levels were more likely to be taking loop diuretics. UA showed a significant correlation with intact PTH (R = 0.34, P<0.001) but not with other calcium-phosphate metabolism-related factors. Linear regression analysis showed that log-transformed UA showed a significant association with left ventricular mass index, and this relationship was found to be significant exclusively in patients who were not taking loop and/or thiazide diuretics. Multivariate logistic regression analysis showed that log-transformed UA was independently associated with LV hypertrophy with an odds ratio of 2.79 (95% confidence interval 1.48–5.28, P = 0.002 per one standard deviation increase).

Conclusions

Among cardiac patients, serum UA was associated with LV hypertrophy, and this relationship was, at least in part, independent of intact PTH levels, which showed a significant correlation with UA in the same population.

Animal models of cardiac disease and stem cell therapy

Animal models that mimic cardiovascular diseases are indispensable tools for understanding the mechanisms underlying the diseases at the cellular and molecular level. This review focuses on various methods in preclinical research to create small animal models of cardiac diseases, such as myocardial infarction, dilated cardiomyopathy, heart failure, myocarditis and cardiac hypertrophy, and the related stem cell treatment for these diseases.

Target organ damage in patients with rheumatoid arthritis: the role of blood pressure and heart rate

BACKGROUND

Rheumatoid arthritis (RA) is characterised by increased cardiovascular morbidity and mortality. Even though hypertension (HT) is highly prevalent in RA, the extent of target organ damage (TOD) caused by it remains unknown. Inflammation and sympathetic overdrive may also associate with TOD. We investigated the prevalence and associations of TOD in RA.

METHODS

In this cross-sectional, observational study, 251 RA patients with no overt cardiovascular or renal disease had extensive clinical and laboratory evaluations, including a 12-lead electrocardiogram and urine albumin:creatinine ratio. Pulse pressure (PP) was used as a proxy of arterial stiffness and heart rate (HR) of autonomic activity. TOD was defined as described in the European guidelines for the management of arterial hypertension. Binary logistic regression analysis was used to evaluate the independence of the variables that associated with the presence of TOD.

RESULTS

TOD prevalence was 23.5% (59/251). Of the 59 patients with TOD, 45.8% had suboptimally controlled HT, whereas 32.3% had undiagnosed HT. In univariable analysis, TOD was significantly associated with higher age (64.2+/-11.7 years vs. 58.0+/-12.4 years, p=0.001), HT prevalence (89.8% vs. 60.4%, p<0.001), systolic blood pressure (SBP) (150.3+/-18.8mmHg vs. 139.7+/-20.7mmHg, p=0.001), PP (70.6+/-16.6mmHg vs. 60.3+/-17.3mmHg, p<0.001), HR (77.1+/-15.4bpm vs. 72.2+/-12.2bpm, p<0.001), serum uric acid (320.6+/-88.8mumol/l vs. 285.0+/-74.9mumol/l, p=0.03) and type 2 diabetes mellitus prevalence (13.6% vs. 4.7%, p=0.019). Binary logistic regression analysis revealed that only hypertension indices and HR associated independently with TOD.

CONCLUSIONS

TOD is highly prevalent in patients with RA and associates independently with hypertension, arterial stiffness and heart rate. Further prospective studies are needed to confirm these findings and examine the role of beta-blockers in this particular population.

Effects of active and negative mutants of Ras on rat arterial neointima formation

BACKGROUND

Ras protein is a key signal transducer in the cause of cell proliferation. We studied the effects of active and negative mutants of the Ras gene on arterial neointimal formation in rats, with the aim of elucidating the molecular mechanisms regulating restenosis following percutaneous transluminal coronary angioplasty.

MATERIALS AND METHODS

AdRasV12 and AdRasN17, the recombinant adenoviruses containing a constitutively active mutant and a dominant negative mutant of Ras, respectively, were used to determine whether Ras is necessary and sufficient to modulate the smooth muscle cell proliferation and neointima formation. Following balloon injury, rat common carotid arteries were treated in their distal half with AdRasV12, AdRasN17, or AdLacZ, with the proximal half used as uninfected control.

RESULTS

In rat arteries subjected to balloon injury, either uninfected or treated with AdLacZ, there were pronounced SMC proliferation and neointima formation. These changes were markedly augmented by AdRasV12 and reduced by AdRasN17.

CONCLUSION

Ras is necessary and sufficient for SMC proliferation and neointima formation and may play a critical role in restenosis following balloon angioplasty.