Apoptosis in target organs of hypertension

Regulated vascular smooth muscle cell death in vascular diseases

Regulated cell death (RCD) is a complex process that involves several cell types and plays a crucial role in vascular diseases. Vascular smooth muscle cells (VSMCs) are the predominant elements of the medial layer of blood vessels, and their regulated death contributes to the pathogenesis of vascular diseases. The types of regulated VSMC death include apoptosis, necroptosis, pyroptosis, ferroptosis, parthanatos, and autophagy-dependent cell death (ADCD). In this review, we summarize the current evidence of regulated VSMC death pathways in major vascular diseases, such as atherosclerosis, vascular calcification, aortic aneurysm and dissection, hypertension, pulmonary arterial hypertension, neointimal hyperplasia, and inherited vascular diseases. All forms of RCD constitute a single, coordinated cell death system in which one pathway can compensate for another during disease progression. Pharmacologically targeting RCD pathways has potential for slowing and reversing disease progression, but challenges remain. A better understanding of the role of regulated VSMC death in vascular diseases and the underlying mechanisms may lead to novel pharmacological developments and help clinicians address the residual cardiovascular risk in patients with cardiovascular diseases.

Hypertension and Ovarian Cancer: A Case-Control Study in Saudi Arabia

Background There is limited evidence that evaluates the association between hypertension and ovarian cancer. The study aims to investigate the association between ovarian cancer and hypertension, the difference in lipid profile, and the association between body mass index (BMI) and ovarian cancer. Methods We conducted a case-control study at King Abdelaziz Medical City (KAMC), oncology department. All Saudi female patients who were diagnosed with primary ovarian cancer admitted to the oncology department at KAMC from 2016 to 2019 were selected. The data were collected from medical records of patients of the KAMC by chart review using The Ministry of National Guard Health Affairs BESTCare database. Results A total of 137 Saudi female patients diagnosed with ovarian cancer attending to gynecology and oncology center in KAMC from 2016 to 2019 were included in this study. The mean age of participants was 57 in cases and 56 in controls with a mean BMI of 29.64 in cases and 31 in controls. There were 63 obese cases, therefore, the proportion of obesity was 46%. Approximately one-third of cases were overweight (28%) while one-fourth (26%) of them were underweight or normal weight. Roughly two-thirds of cases were hypertensive with an overall proportion of 66 % (95% confidence interval (CI) 58-74) while one-third of controls were hypertensive with an overall proportion of 32%. Cases were having significantly higher triglycerides (p=0.03) and lower high-density lipoprotein (HDL) (p=0.001) than controls. The significant variables were analyzed using logistic regression. It was found that hypertensive subjects were 10.06 times more likely (95% CI: 4.88-20.71) to be associated with the cases as compared to controls (p<0.001). Also, an increase in BMI was significantly associated with being a case with OR = 1.07 (95% CI: 1.02-1.12; p=0.004). Conclusion In conclusion, hypertension, elevated BMI, higher triglycerides, and lower HDL were significantly associated with ovarian cancer.

Sex differences in apoptosis do not contribute to sex differences in blood pressure or renal T cells in spontaneously hypertensive rats

Apoptosis is a physiological and anti-inflammatory form of cell death that is indispensable for normal physiology and homeostasis. Several studies have reported aberrant activation of apoptosis in various tissues at the onset of hypertension. However, the functional significance of apoptosis during essential hypertension remains largely undefined. The current study was designed to test the hypothesis that apoptosis contributes to sex differences in blood pressure and the T cell profile in spontaneously hypertensive rats (SHR). Apoptosis was measured in kidney, aorta and spleen of 13-week-old adult hypertensive male and female SHR. Female SHR had greater renal and aortic apoptosis compared to age-matched males; apoptosis in the spleen was comparable between the sexes. Based on well-established sex differences in hypertension, we tested the hypothesis that greater apoptosis in female SHR contributes to the lower BP and pro-inflammatory profile compared to males. Male and female SHR were randomized to receive vehicle or ZVAD-FMK, a cell permeable pan-caspase inhibitor, in established hypertension from 13 to 15 weeks of age or at the onset of hypertension from 6 to 12 weeks or age. Treatment with ZVAD-FMK lowered renal apoptosis in both studies, yet neither BP nor renal T cells were altered in either male or female SHR. These results suggest that apoptosis does not contribute to the control or maintenance of BP in male or female SHR or sex differences in renal T cells.

Association between hypertension and cutaneous melanoma, and the effect of aspirin: extended follow-up of a large randomised controlled trial

BACKGROUND

The association between hypertension and melanoma is unclear, and previous analyses of data from the ASPirin in Reducing Events in the Elderly (ASPREE) study demonstrated a reduced number of invasive melanoma events amongst aspirin-exposed hypertensive individuals.

METHODS

Data from the ASPREE study which included (1) the intervention period with a median follow-up of 4.7 years, and (2) the observational period with an additional 2 years follow-up, were combined for this analysis. Logistic regression analyses examined the association between baseline hypertension and treatment status and past melanoma history. Survival analyses examined the association between hypertension and melanoma risk, and the effect of aspirin across hypertension groups. Cox proportional hazards models were used to compare incidence across groups.

RESULTS

19,114 participants (median age of 74 years) were randomised to daily 100 mg aspirin or placebo. At baseline, hypertension and past melanoma history were recorded in 14,195 and 685 individuals, respectively. After adjustment for confounders, hypertension was significantly associated with past melanoma history (OR=1.34, 95%CI: 1.11-1.62). In a prospective analysis, baseline hypertension was not associated with melanoma risk. However, aspirin was associated with a reduced risk of incident melanoma amongst individuals with uncontrolled hypertension (blood pressure ≥140/90 mmHg; HR=0.63, 95%CI 0.44-0.89), but not in those with controlled hypertension (HR=1.04, 95%CI 0.74-1.46).

CONCLUSION

Our results support a reduced melanoma incidence amongst individuals with uncontrolled hypertension exposed to aspirin. Additional studies are required to confirm these findings.

Aerobic Exercise Training Improves Renal Injury in Spontaneously Hypertensive Rats by Increasing Renalase Expression in Medulla

We aimed to examine the effects of aerobic exercise training on renal function in spontaneously hypertensive rats (SHR) and elucidate their possible mechanisms. Adult male SHR and age-matched Wistar-Kyoto rats (WKY) were divided into four groups: WKY sedentary group, SHR sedentary group, low-intensity training group, and medium-intensity training group. Using molecular and biochemical approaches, we investigated the effects of 14-week training on renalase (RNLS) protein levels, renal function, and apoptosis and oxidative stress modulators in kidney tissues. In vitro, angiotensin II (Ang II)-induced human kidney proximal epithelial cells (HK-2) were treated with RNLS, and changes in apoptosis and oxidative stress levels were observed. Our results show that moderate training improved renal function decline in SHR. In addition, aerobic exercise therapy significantly increased levels of RNLS in the renal medulla of SHR. We observed in vitro that RNLS significantly inhibited the increase of Ang II-inducedapoptosis and oxidative stress levels in HK-2. In conclusion, aerobic exercise training effectively improved renal function in SHR by promoting RNLS expression in the renal medulla. These results explain the possible mechanism in which exercise improves renal injury in hypertensive patients and suggest RNLS as a novel therapy for kidney injury patients.

Anti-apoptotic and pro-survival effect of exercise training on early aged hypertensive rat cerebral cortex

The anti-apoptotic and pro-survival effects of exercise training were evaluated on the early aged hypertensive rat cerebral cortex. The brain tissues were analysed from ten sedentary male Wistar Kyoto normotensive rats (WKY), ten sedentary spontaneously 12 month early aged hypertensive rats (SHR), and ten hypertensive rats undergoing treadmill exercise training (60 min/day, 5 days/week) for 12 weeks (SHR-EX). TUNEL-positive apoptotic cells, the expression levels of endonuclease G (EndoG) and apoptosis-inducing factor (AIF) (caspase-independent apoptotic pathway), Fas ligand, Fas death receptor, tumor necrosis factor (TNF)-α, TNF receptor 1, Fas-associated death domain, active caspase-8 and active caspase-3 (Fas-mediated apoptotic pathways) as well as t-Bid, Bax, Bak, Bad, cytochrome c, active caspase 9 and active caspase-3 (mitochondria-mediated apoptotic pathways) were reduced in SHR-EX compared with SHR. Pro-survival Bcl2, Bcl-xL, p-Bad, 14-3-3, insulin-like growth factor (IGF)-1, pPI3K/PI3K, and pAKT/AKT were significantly increased in SHR-EX compared to those in SHR. Exercise training suppressed neural EndoG/AIF-related caspase-independent, Fas/FasL-mediated caspase-dependent, mitochondria-mediated caspase-dependent apoptotic pathways as well as enhanced Bcl-2 family-related and IGF-1-related pro-survival pathways in the early aged hypertensive cerebral cortex. These findings indicated new therapeutic effects of exercise training on preventing early aged hypertension-induced neural apoptosis in cerebral cortex.

Good or bad: Application of RAAS inhibitors in COVID-19 patients with cardiovascular comorbidities

The coronavirus disease 2019 (COVID-19) pandemic is caused by a newly emerged coronavirus (CoV) called Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2). COVID-19 patients with cardiovascular disease (CVD) comorbidities have significantly increased morbidity and mortality. The use of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor type 1 blockers (ARBs) improve CVD outcomes; however, there is concern that they may worsen the prognosis of CVD patients that become infected with SARS-CoV-2 because the virus uses the ACE2 receptor to bind to and subsequently infect host cells. Thus, some health care providers and media sources have questioned the continued use of ACE inhibitors and ARBs. In this brief review, we discuss the effect of ACE inhibitor-induced bradykinin on the cardiovascular system, on the renin-angiotensin-aldosterone system (RAAS) regulation in COVID-19 patients, and analyze recent clinical studies regarding patients treated with RAAS inhibitors. We propose that the application of RAAS inhibitors for COVID-19 patients with CVDs may be beneficial rather than harmful.

Bioactive peptides attenuate cardiac apoptosis in spontaneously hypertensive rat hearts through activation of autophagy and mitochondrial biogenesis pathway

Alcalase potato protein hydrolysate (APPH) might have a very important role in therapeutic effects. This study aims to examine the beneficial effects of bioactive peptides (DIKTNKPVIF [DI] and IF) from APPH supplement in the regulation of cardiac apoptosis, autophagy, and mitochondrial biogenesis pathway in spontaneously hypertensive rats (SHR). We have investigated ejection fraction, fractional shortening, Tunel assay, apoptosis, autophagy, and mitochondrial biogenesis pathway marker expression to show the efficacy of bioactive peptides in an SHR model. Bioactive peptides significantly upregulate ejection fraction and fractional shortening in SHR rats. SHR rats exhibited higher protein expression of apoptotic markers such as BAD, cytochrome c, and caspase 3. Finally, the bioactive peptides upregulate survival proteins (p-AKT/p-PI3K), autophagy (Beclin1/LC3B), and mitochondrial biogenesis (p-AMPKα/SIRT1/PGC1α/p-Foxo3a/Nrf2/CREB) marker expressions compared with the SHR groups. In summary, the bioactive peptides protect the heart tissues through the activation of autophagy and mitochondrial biogenesis pathway and thereby attenuate cardiac apoptosis in a spontaneously hypertensive rat model.

Perinatal taurine exerts a hypotensive effect in male spontaneously hypertensive rats and down-regulates endothelial oxide nitric synthase in the aortic arch

Essential hypertension is considered to be a result of the interaction between genetic and environmental factors, including perinatal factors. Different advantageous perinatal factors proved to have beneficial long-lasting effects against an abnormal genetic background. Taurine is a ubiquitous sulphur-containing amino acid present in foods such as seafood. The antihypertensive effects of taurine have been reported in experimental studies and in human hypertension. We aimed to investigate the effects of perinatal treatment with taurine in spontaneously hypertensive rats (SHR), a known model of genetic hypertension. Female SHR were administered with taurine (3 g/L) during gestation and lactation (SHR-TAU). Untreated SHR and Wistar-Kyoto rats (WKY) were used as controls. Long-lasting effects in offspring were investigated. Addition of taurine to the mother's drinking water reduced blood pressure in adult offspring. No differences were observed in cardiac hypertrophy. Findings on morphometric evaluations suggest that perinatal treatment with taurine would be partially effective in improving structural alterations of the aorta. Modifications in gene expression of Bcl-2 family members and upregulation of endothelial nitric oxide synthase in the aorta of 22-week-old male offspring were found. No differences were observed on relative telomere length in different cardiovascular tissues between SHR and SHR-TAU. Altogether results suggest that taurine programming, albeit sex specific, is associated with gene expression changes which ultimately may lead to improvement of aortic remodelling and enhanced endothelial function because of augmented nitric oxide (NO) production.

Effects of Taurine and L-Arginine on the Apoptosis of Vascular Smooth Muscle Cells in Insulin Resistance Hypertensive Rats

OBJECTIVE

In order to find the effects and mechanism of taurine and L-arginine on the apoptosis of VSMCs in insulin resistance hypertensive rats.

METHODS

25% fructose were administered in the drinking water to Wistar rats for 12 weeks to induce the insulin resistance hypertensive model. Apoptosis of VSMCs was identified by TUNEL. The expressions of Bax protein and Bcl-2 protein were examined by immunohistochemistry.

RESULTS

High level of fructose significantly suppressed the apoptosis of VSMCs. Taurine and L-arginine promoted apoptosis of VSMCs via increasing the Bax protein expression and decreasing the Bcl-2 protein expression.

CONCLUSIONS

Taurine and L-arginine have obvious anti-hypertensive effects in insulin resistance hypertensive rats, and its mechanism might partially be associated with attenuating vascular remodeling by promoting apoptosis in VSMCs. In addition, the combined medication of taurine and L-arginine was more effective than single medication.

Novel candidate genes important for asthma and hypertension comorbidity revealed from associative gene networks

BACKGROUND

Hypertension and bronchial asthma are a major issue for people's health. As of 2014, approximately one billion adults, or ~ 22% of the world population, have had hypertension. As of 2011, 235-330 million people globally have been affected by asthma and approximately 250,000-345,000 people have died each year from the disease. The development of the effective treatment therapies against these diseases is complicated by their comorbidity features. This is often a major problem in diagnosis and their treatment. Hence, in this study the bioinformatical methodology for the analysis of the comorbidity of these two diseases have been developed. As such, the search for candidate genes related to the comorbid conditions of asthma and hypertension can help in elucidating the molecular mechanisms underlying the comorbid condition of these two diseases, and can also be useful for genotyping and identifying new drug targets.

RESULTS

Using ANDSystem, the reconstruction and analysis of gene networks associated with asthma and hypertension was carried out. The gene network of asthma included 755 genes/proteins and 62,603 interactions, while the gene network of hypertension - 713 genes/proteins and 45,479 interactions. Two hundred and five genes/proteins and 9638 interactions were shared between asthma and hypertension. An approach for ranking genes implicated in the comorbid condition of two diseases was proposed. The approach is based on nine criteria for ranking genes by their importance, including standard methods of gene prioritization (Endeavor, ToppGene) as well as original criteria that take into account the characteristics of an associative gene network and the presence of known polymorphisms in the analysed genes. According to the proposed approach, the genes IL10, TLR4, and CAT had the highest priority in the development of comorbidity of these two diseases. Additionally, it was revealed that the list of top genes is enriched with apoptotic genes and genes involved in biological processes related to the functioning of central nervous system.

CONCLUSIONS

The application of methods of reconstruction and analysis of gene networks is a productive tool for studying the molecular mechanisms of comorbid conditions. The method put forth to rank genes by their importance to the comorbid condition of asthma and hypertension was employed that resulted in prediction of 10 genes, playing the key role in the development of the comorbid condition. The results can be utilised to plan experiments for identification of novel candidate genes along with searching for novel pharmacological targets.

Short-term hypoxia upregulated Mas receptor expression to repress the AT1 R signaling pathway and attenuate Ang II-induced cardiomyocyte apoptosis

Hypertension-stimulated cardiac hypertrophy and apoptosis play critical roles in the progression of heart failure. Our previous study suggested that hypertensive angiotensin II (Ang II) enhanced insulin-like growth factor receptor II (IGF-IIR) expression and cardiomyocyte apoptosis, which are involved JNK activation, sirtuin1 (SIRT1) degradation, and heat-shock transcription factor 1 (HSF1) acetylation. Moreover, previous studies have implied that short-term hypoxia (STH) might exert cardioprotective effects. However, the effects of STH on Ang II-induced cardiomyocyte apoptosis remain unknown. In this study, we found that STH reduced myocardial apoptosis caused by Ang II via upregulation of the Mas receptor (MasR) to inhibit the AT₁ R signaling pathway. STH activates MasR to counteract the Ang II pro-apoptotic signaling cascade by inhibiting IGF-IIR expression via downregulation of JNK activation and reduction of SIRT1 degradation. Hence, HSF could remain deacetylated, and repress IGF-IIR expression. These effects decrease the activation of downstream pro-apoptotic and hypertrophic cascades and protect cardiomyocytes from Ang II-induced injury. In addition, we also found that silencing MasR expression enhanced Ang II-induced cardiac hypertrophy and the apoptosis signaling pathway. These findings suggest a critical role for MasR in cardiomyocyte survival. Altogether, our findings indicate that STH protects cardiomyocytes from Ang II-stimulated apoptosis. The protective effects of STH are associated with the upregulation of MasR to inhibit AT₁ R signaling. STH could be a potential therapeutic strategy for cardiac diseases in hypertensive patients.

Age-related changes in hypertensive brain damage in the hippocampi of spontaneously hypertensive rats

The aim of the present study was to investigate the age-related alterations in hypertensive brain damage in the hippocampi of spontaneously hypertensive rats (SHR) and the underlying mechanisms. Aging resulted in a significant increase in the number of activated astrocytes and apoptotic cells in the SHR group, which was accompanied by increased expression of oxidative stress markers (iNOS and gp47^phox) and apoptotic regulatory proteins (Bax and caspase-3). In addition, the expression of PPAR-γ and Bcl-2 were progressively reduced with increasing age in the SHR group. The 32 and 64-week-old SHRs exhibited significantly increased numbers of apoptotic cells, oxidative stress markers and pro-apoptotic proteins compared with age-matched WKY rats, which was accompanied by reduced expression of PPAR-γ. Compared with the 16 and 32-week-old WKY group, the 64-week-old WKY rats exhibited increased oxidative stress and pro-apoptotic markers, and increased levels apoptotic cells. In conclusion, the present study indicated that both aging and hypertension enhanced brain damage and oxidative stress injury in the hippocampi of SHRs, indicated by an increased presence of apoptotic cells and astrocytes. In addition, reduced expression of PPAR-γ may contribute to the age-related brain damage in SHRs.

Induction of apoptosis by hypertension via endoplasmic reticulum stress

BACKGROUND/AIMS

Endoplasmic reticulum (ER) stress is one of the intrinsic apoptosis pathways, and cardiac apoptosis can occur in cardiovascular diseases, such as hypertension. However, the mechanisms by which ER stress leads to apoptosis remain enigmatic, particularly in the progression from cardiac hypertrophy to diastolic heart failure due to hypertension.

METHODS

We used spontaneously hypertensive rats (SHRs) to investigate possible signalling pathways for ER stress.

RESULTS

We found that cardiac protein and mRNA levels of glucoseregulated protein 78 were up-regulated. In addition, the CHOP- and caspase-12-dependent pathways, but not that of JNK, were activated in the SHR rats.

CONCLUSIONS

These results suggest that ER stress can contribute to myocardial apoptosis during hypertensive disease.

Variability in vascular smooth muscle cell stretch-induced responses in 2D culture

The pulsatile nature of blood flow exposes vascular smooth muscle cells (VSMCs) in the vessel wall to mechanical stress, in the form of circumferential and longitudinal stretch. Cyclic stretch evokes VSMC proliferation, apoptosis, phenotypic switching, migration, alignment, and vascular remodeling. Given that these responses have been observed in many cardiovascular diseases, a defined understanding of their underlying mechanisms may provide critical insight into the pathophysiology of cardiovascular derangements. Cyclic stretch-triggered VSMC responses and their effector mechanisms have been studied in vitro using tension systems that apply either uniaxial or equibiaxial stretch to cells grown on an elastomer-bottomed culture plate and ex vivo by stretching whole vein segments with small weights. This review will focus mainly on VSMC responses to the in vitro application of mechanical stress, outlining the inconsistencies in acquired data, and comparing them to in vivo or ex vivo findings. Major discrepancies in data have been seen in mechanical stress-induced proliferation, apoptosis, and phenotypic switching responses, depending on the stretch conditions. These discrepancies stem from variations in stretch conditions such as degree, axis, duration, and frequency of stretch, wave function, membrane coating, cell type, cell passage number, culture media content, and choice of in vitro model. Further knowledge into the variables that cause these incongruities will allow for improvement of the in vitro application of cyclic stretch.

Involvement of cardiomyocyte survival–apoptosis balance in hypertensive cardiac remodeling

The balance between cell death and cell survival is a tightly controlled process, especially in terminally differentiated cells, such as the cardiomyocyte. Accumulating data support a role for cardiomyocyte apoptosis in the development of several cardiac diseases, including the transition from hypertensive compensatory hypertrophy to heart failure. This review briefly summarizes the status of the knowledge regarding the death-survival balance of cardiomyocytes in the context of hypertensive heart disease. Several molecular and cellular aspects as well as the most relevant pathophysiological implications are presented. Moreover, diagnosis tools under development and the possibilities for pharmacological intervention are also examined.

Long-term prehypertension treatment with losartan effectively prevents brain damage and stroke in stroke-prone spontaneously hypertensive rats

Prehypertension has been associated with adverse cerebrovascular events and brain damage. The aims of this study were to investigate i) whether short- and long-term treatments with losartan or amlodipine for prehypertension were able to prevent blood pressure (BP)-linked brain damage, and ii) whether there is a difference in the effectiveness of treatment with losartan and amlodipine in protecting BP-linked brain damage. In the present study, prehypertensive treatment with losartan and amlodipine (6 and 16 weeks treatment with each drug) was performed on 4-week-old stroke-prone spontaneously hypertensive rats (SHRSP). The results showed that long-term (16 weeks) treatment with losartan is the most effective in lowering systolic blood pressure in the long term (up to 40 weeks follow-up). Additionally, compared with the amlodipine treatment groups, the short- and long-term losartan treatments protected SHRSP from stroke and improved their brains structurally and functionally more effectively, with the long-term treatment having more benefits. Mechanistically, the short- and long-term treatments with losartan reduced the activity of the local renin-angiotensin-aldosterone system (RAAS) in a time-dependent manner and more effectively than their respective counterpart amlodipine treatment group mainly by decreasing AT1R levels and increasing AT2R levels in the cerebral cortex. By contrast, the amlodipine treatment groups inhibited brain cell apoptosis more effectively as compared with the losartan treatment groups mainly through the suppression of local oxidative stress. Taken together, the results suggest that long-term losartan treatment for prehypertension effectively protects SHRSP from stroke-induced brain damage, and this protection is associated with reduced local RAAS activity than with brain cell apoptosis. Thus, the AT1R receptor blocker losartan is a good candidate drug that may be used in the clinic for long-term treatment on prehypertensive populations in order to prevent BP-linked brain damage.

Hypertension, hypertension-clustering factors and Alzheimer's disease

Hypertension is a risk factor for stroke, ischemic white matter lesions, silent infarcts, general atherosclerosis, myocardial infarction and cardiovascular morbidity and mortality. This risk increases with increasing blood pressure also at blood pressure within the normal ranges, and a high percentage of these cardiovascular events occur in those with normal blood or mild hypertension. Several studies have reported that high blood pressure precedes Alzheimer's disease by decades, but blood pressure decreases the years before dementia onset and is lower in individuals with Alzheimer's disease than in controls. High blood pressure has also been related to the neuropathological manifestations of Alzheimer's disease. Hypertension often clusters with other vascular risk factors, including diabetes mellitus, obesity, and hypercholesterolemia. Also, these risk factors have been related to Alzheimer's disease. The exact mechanism behind these associations is not clear. Hypertension may cause cerebrovascular disease that may increase the likelihood that individuals with AD encephalopathy will express a dementia syndrome, but hypertension may also accelerate the AD process, subclinical AD may lead to increased blood pressure, and similar biological mechanisms may be involved in the pathogenesis of both disorders. Hypertension is a common disorder and often untreated. Even if hypertension only results in a moderately increased risk of AD, or overall dementia, better treatment of hypertension may have an immense effect on the total numbr of demented individuals.

Effect of kefir and low-dose aspirin on arterial blood pressure measurements and renal apoptosis in unhypertensive rats with 4 weeks salt diet

Abstract We aim to study the effect of low-dose aspirin and kefir on arterial blood pressure measurements and renal apoptosis in unhypertensive rats with 4 weeks salt diet. Forty adult male Sprague-Dawley rats were divided into five groups: control, high-salt (HS) (8.0% NaCl), HS+aspirin (10 mg/kg), HS+kefir (10.0%w/v), HS+aspirin +kefir. We measured sistolic blood pressure (SBP), mean arterial pressure (MAP), diastolic pressure, pulse pressure in the rats. Cathepsin B, L, DNA fragmentation and caspase-3 activities were determined from rat kidney tissues and rats clearance of creatinine calculated. Although HS diet increased significantly SBP, MAP, diastolic pressure, pulse pressure parameters compared the control values. They were not as high as accepted hypertension levels. When compared to HS groups, kefir groups significantly decrease Cathepsin B and DNA fragmentation levels. Caspase levels were elevated slightly in other groups according to control group. While, we also found that creatinine clearance was higher in HS+kefir and HS+low-dose aspirin than HS group. Thus, using low-dose aspirin had been approximately decreased of renal function damage. Kefir decreased renal function damage playing as Angiotensin-converting enzyme inhibitor. But, low-dose aspirin together with kefir worsened rat renal function damage. Cathepsin B might play role both apoptosis and prorenin-processing enzyme. But not caspase pathway may be involved in the present HS diet induced apoptosis. In conclusion, kefir and low-dose aspirin used independently protect renal function and renal damage induced by HS diet in rats.

[Delayed appearance of hypertension in spontaneously hypertensive rat (SHR) injected with CpG-rich DNA early in ontogenesis]

In this study we have investigated properties of blood serum extracellular DNA (cell-free DNA) from patients with essential arterial hypertension (AH). Cell-free DNA concentration was not changed in the control AH group compared to norma (healthy donors) but fragments of CpG-rich cell-free DNA marker content were increased at transcribed area of ribosomal repeat (TArDNA, CpG-DNA). To evaluate effect of CpG-DNA on AH development in 2-day SHR line and in control normotensive line (WKY), 700 ng of human TArDNA single subcutaneous injection were inoculated to obtain anti-CpG-DNA polyclonal antibodies. These antibodies could change CpG-DNA contents in total cell-free DNA. Blood pressure (BP) in 9-week SHR line rats immunized with CpG-DNA was equal to BP of WKY rats. Then BP of immunized SHR steadily increased with age and reached high value 8 weeks later compared to control SHR rats. Cell-free DNA analysis in 17-week SHR line rats showed significantly reduced concentrations of cell-free DNA and also showed decrease in small DNA fragments content, but increased content of CpG-DNA (rat TArDNA). These changes were accompanied with 3.5-fold blood endonuclease activity increase and decrease of free (unbound to cell-free DNA) anti-CpG-DNA antibodies quantity. Total anti-CpG-DNA antibodies quantity in immunized rats wasn't changed compared to control animals. Thus, observed effect of increase in stable BP elevation age in immunized SHR line rats doesn't relate to increase of anti-CpG-DNA antibody production. Possible reason of this effect is further discussed.

Mechanism of pressure-overload right ventricular hypertrophy in infant rabbits

Although pressure-overload right ventricular hypertrophy is a long-term risk in some congenital heart diseases such as tetralogy of Fallot, how it develops is unclear. The aim of this study was to investigate the mechanism of development of this right ventricular heart failure.Pulmonary artery banding in 10-day-old rabbits induced pressure-overload right ventricular hypertrophy as they grew. Comparisons were made with age-matched sham controls (n = 24 per group). In weekly serial echocardiography, the right ventricular contraction and diastolic function decreased from 3 weeks after surgery (P < 0.01), and the right ventricle became hypertrophic from 4 weeks after (P < 0.05). Pressure-overload increased cardiomyocyte apoptosis from 4 weeks postoperatively (TUNEL staining and Western blotting analysis, P < 0.05); and fibrosis occurred in the right ventricular cardiomyocytes at 8 weeks after operation (Masson's trichrome stain, P < 0.01). In our model, pressure-overload to the right ventricle caused the right ventricular disorder, hypertrophy, and fibrosis. Apoptosis of right ventricular cardiomyocytes was involved in progression. We have shown for the first time the mechanism whereby pressure-overload right ventricular hypertrophy develops in an infant rabbit model.

Atorvastatin prevents left ventricular remodeling in spontaneously hypertensive rats

Statins improve left ventricular (LV) remodeling in spontaneously hypertensive rats (SHRs). This study was designed to investigate the effects of atorvastatin administered in the early stage on LV remodeling in SHRs, and to explore the underlying mechanisms.Sixteen male 8-week-old SHRs were randomized to receive distilled water (SHR-DW) or atorvastatin (SHR-ATV) for 12 weeks. Age-matched male Wistar-Kyoto (WKY) rats gavaged with distilled water served as controls. LV remodeling was evaluated, myocardial CTGF expression levels were detected using Western blotting, and cardiomyocyte apoptosis was detected with the TUNEL method.Compared with WKY and SHR-DW, atorvastatin treatment significantly decreased systolic blood pressure in SHRs; atorvastatin significantly inhibited LV remodeling, as indicated by the reduced LV weight/body weight ratio (SHR-ATV: 4.0 ± 0.4 versus SHR-DW: 4.7 ± 0.4 mg/g, P < 0.05), cardiomyocyte diameter (SHR-ATV: 16.2 ± 2.8 versus SHR-DW: 19.0 ± 1.0 µm, P < 0.05), and interstitial fibrosis (SHR-ATV: 3.3 ± 2.1 versus SHR-DW: 4.5 ± 1.8%, P < 0.05). Compared with WKY, myocardial CTGF expression was significantly increased and cardiomyocyte apoptosis decreased in SHRs. Compared with the SHR-DW group, atorvastatin treatment significantly inhibited myocardial CTGF expression (SHR-ATV: 0.69 ± 0.21 versus SHR-DW: 1.12 ± 0.27, P < 0.05) and induced cardiomyocyte apoptosis in SHRs (SHR-ATV: 5.2 ± 0.6 versus SHR-DW: 1.9 ± 0.3%, P < 0.05).The results indicate that early-stage administration of atorvastatin effectively prevented LV remodeling in SHRs, and that inhibition of myocardial CTGF expression and induction of cardiomyocyte apoptosis may be the underlying mechanisms.

Hypertension, antihypertensive medication use, and breast cancer risk in the California Teachers Study cohort

BACKGROUND

We investigated the association between hypertension, antihypertensive (AH) medication use, and breast cancer in a large prospective study, the California Teachers Study (CTS).

METHODS

Information on history of hypertension and lifetime regular use of AH medications was collected from 114,549 women in 1995-1996. Among them, 4,151 invasive breast cancers were diagnosed between 1995 and 2006. Additional information on AH use was collected from 73,742 women in 2000-2001, and 1,714 of these women were subsequently diagnosed with breast cancer. Cox proportional hazards regression was used to estimate relative risks (RR) and 95% confidence intervals (CI) for breast cancer.

RESULTS

Use of AH medication for ≥5 years, when compared with no use, was associated with a modest increased risk of invasive breast cancer (RR = 1.18, 95%CI 1.02-1.36). This increased risk appeared to be confined to estrogen receptor (ER)-positive tumors (RR = 1.21, 95%CI 1.03-1.43) and pre-/peri-menopausal women (RR = 1.58, 95%CI 1.11-2.25).

CONCLUSIONS

Increased risk of invasive breast cancer was observed for long-term (≥5 years) AH use, and this appeared to be confined to ER + breast cancer and younger women.

Matrix metalloproteinases cleave the beta2-adrenergic receptor in spontaneously hypertensive rats

We recently observed the enhanced serine and matrix metalloproteinase (MMP) activity in the spontaneously hypertensive rat (SHR) compared with its normotensive Wistar-Kyoto (WKY) rat and the cleavage of membrane receptors in the SHR by MMPs. We demonstrate in vivo that MMP-7 and MMP-9 injection leads to a vasoconstrictor response in microvessels of rats that is blocked by a specific MMP inhibitor (GM-6001, 1 microM). Multiple pathways may be responsible. Since the beta(2)-adrenergic receptor (beta(2)-AR) is susceptible to the action of endogenous MMPs, we hypothesize that MMPs in the plasma of SHRs are able to cleave the extracellular domain of the beta(2)-AR. SHR arterioles respond in an attenuated fashion to beta(2)-AR agonists and antagonists. Aorta and heart muscle of control Wistar rats were exposed for 24 h (37 degrees C) to fresh plasma of male Wistar and WKY rats and SHRs with and without doxycycline (30 microM) and EDTA (10 mM) to reduce MMP activity. The density of extracellular and intracellular domains of beta(2)-AR was determined by immunohistochemistry. The density of the extracellular domain of beta(2)-AR is reduced in aortic endothelial cells and cardiac microvessels of SHRs compared with that of WKY or Wistar rats. Treatment of the aorta and the heart of control Wistar rats with plasma from SHRs, but not from WKY rats, reduced the number of extracellular domains, but not intracellular domains, of beta(2)-AR in aortic endothelial cells and cardiac microvessels. MMP inhibitors (EDTA and doxycycline) prevented the cleavage of the extracellular domain. Thus MMPs may contribute to the reduced density of the extracellular domain of beta(2)-AR in blood vessels and to the increased arteriolar tone of SHRs compared with normotensive rats.

Apoptosis repressor with caspase recruitment domain is dramatically reduced in cardiac, skeletal, and vascular smooth muscle during hypertension

Apoptosis repressor with caspase recruitment domain (ARC) is a unique anti-apoptotic protein with a distinct tissue distribution. In addition, unlike most anti-apoptotic proteins which act on one pathway, ARC can inhibit apoptosis mediated by both the death-receptor and mitochondrial signaling pathways. In this study, we confirm previous reports showing high levels of ARC protein in rat heart and skeletal muscle, but demonstrate for the first time that ARC is also expressed in rat aorta. Immunoblot analysis on endothelium-denuded aorta as well as immunohistochemical analysis on intact aorta demonstrated that ARC was highly expressed in smooth muscle. Immunoblot analysis also found that ARC protein was severely downregulated in skeletal muscle (-82%; P<0.001), heart (-80%; P<0.001), and aorta (-71%; P<0.001) of spontaneously hypertensive rats (SHR) compared to normotensive Wistar-Kyoto (WKY) rats. Decreased ARC levels were also confirmed in tissues of hypertensive animals by immunohistochemical analysis. Collectively, this data suggests that ARC protein is expressed in vascular smooth muscle and is significantly reduced in several target tissues during hypertension.

Development of left ventricular diastolic dysfunction with preservation of ejection fraction during progression of infant right ventricular hypertrophy

BACKGROUND

Progressive left ventricular (LV) dysfunction can be a major late complication in patients with chronic right ventricular pressure overload (eg, tetralogy of Fallot). Therefore, we examined LV function (serial echocardiography and ex vivo Langendorff) and histology in a model of infant pressure-load right ventricular hypertrophy (RVH).

METHODS AND RESULTS

Ten-day-old rabbits (n=6 per time point, total n=48) that underwent pulmonary artery banding were euthanized at 2 to 8 weeks after pulmonary artery banding, and comparisons were made with age-matched sham controls. LV performance (myocardial performance index) decreased during the progression of RVH, although the LV ejection fraction was maintained. In addition, RVH caused significant septal displacement, reduced septal contractility, and decreased LV end-systolic and end-diastolic dimensions, resulting in LV diastolic dysfunction with the appearance of preserved ejection fraction. Significant septal and LV free-wall apoptosis (myocyte-specific TUNEL and activated caspase-3), fibrosis (Masson trichrome stain), and reduced capillary density (CD31 immunostaining) occurred in the pulmonary artery banding group after 6 to 8 weeks (all P<0.05).

CONCLUSIONS

This is the first study showing that pressure overload of the right ventricular resulting in RVH causes LV diastolic dysfunction while preserving ejection fraction through mechanical and molecular effects on the septum and LV myocardium. In particular, the development of RVH is associated with septal and LV apoptosis and reduced LV capillary density.

Recombinant adeno-associated virus-mediated human kallikrein gene therapy protects against hypertensive target organ injuries through inhibiting cell apoptosis

AIM

Overexpression of human tissue kallikrein (HK), mediated by recombinant adeno-associated virus (rAAV), decreased blood pressure in spontaneous hypertensive rats (SHRs) and reduced injury to the heart, aorta and kidney. In this study, we used both an in vivo animal model and in vitro cell culture system to investigate whether rAAV-mediated HK gene therapy protects against organ damage by inhibiting cell apoptosis.

METHODS

rAAV encoding HK (rAAV-HK) or LacZ (rAAV-lacZ) were delivered as a control to spontaneously hypertensive rats (SHRs) and cultured human embryonic kidney (HEK) 293 cells.

RESULTS

Treatment with rAAV-HK decreased cell apoptosis in the target organs of SHRs and also inhibited lipopolysaccharide (LPS)-induced HEK 293 apoptosis. The rAAV-HK delivery system also increased the levels of apoptosis-inhibiting proteins bcl-2 and bcl-x(L), and decreased the level of Bax and the activity of caspase 3, two promoters of apoptosis. In addition to its role in the inhibition of apoptosis, rAAV-HK also activated the cell survival and proliferation signaling pathways ERK1/2 and PI3K/AKT.

CONCLUSION

rAAV-mediated HK gene delivery has multiple therapeutic possibilities for treating hypertension, not only by decreasing blood pressure, but also by directly inhibiting end-organ damage.

Chronic NHE-1 blockade induces an antiapoptotic effect in the hypertrophied heart

Na+/H+ exchanger (NHE-1) inhibition was demonstrated to induce the regression of cardiac hypertrophy (CH) in several experimental models and to inhibit mitochondrial death pathway in “in-vitro” experiments. Since recent reports show that NHE-1 inhibition delays the transition from CH to failure, and apoptosis plays a key role in this process, we investigated the effect of chronic treatment with the NHE-1 blocker cariporide on CH and apoptosis in the SHR. One month of cariporide treatment (30 mg·kg−1·day−1) induced the regression of CH (cardiomyocyte cross-sectional area: 468 ± 20 vs. 285 ± 9 μm2 in untreated and cariporide-treated spontaneously hypertensive rats; P < 0.05). Apoptosis was assessed by TUNEL staining, the expression of Bcl-2, Bax, and activation of caspase-3 and PARP-1 by immunoblot. Cariporide treatment decreased the TUNEL-positive cells, the Bax-to-Bcl-2 ratio (3.16 ± 0.32 vs. 1.70 ± 0.17, untreated and cariporide-treated, respectively; P < 0.05); caspase-3 and PARP-1 activation (465 ± 62 vs. 260 ± 22 and 2,239 ± 62 vs. 1,683 ± 85 AU, untreated and cariporide-treated, respectively; P < 0.05). Angiotensin II, a growth factor and apoptotic stimulus, was used to induce O2− production that activated the ERK1/2-p90RSK pathway, increasing NHE-1 phosphorylation. These effects were prevented by losartan, N-(2-mercaptopropionyl)-glycine, and cariporide. In conclusion, we present data demonstrating that chronic NHE-1 inhibition with cariporide decreases both hypertrophy and apoptosis susceptibility in the spontaneously hypertensive rat heart. The antiapoptotic effect would be the consequence of two different actions of cariporide: the prevention of cytosolic Na+ and Ca2+ overload due to the inhibition of the sarcolemmal NHE-1 and a direct mitochondrial effect preventing mitochondrial permeability transition pore opening.

Myocardial DNA strand breaks are detected in biopsy tissues from patients with dilated cardiomyopathy

BACKGROUND

Progressive damage of cardiomyocytes with interstitial and replacement fibrosis accompanied by less inflammatory cell infiltration is observed in patients with dilated cardiomyopathy (DCM), suggesting some other mechanisms rather than necrotic cell death.

HYPOTHESIS

The aim of this study was to assess the possible involvement of apoptotic process in the pathogenesis of DCM and myocarditis.

METHODS

Endomyocardial biopsy was performed in patients with DCM (n = 9), myocarditis (n = 4), or atypical chest pain syndrome (as controls; n = 5). The TUNEL method was used for in situ detection of oligonucleosomal DNA strand breaks.

RESULTS

The TUNEL-positive cells were observed in three of nine patients with DCM and in all four with myocarditis, but in none of the controls. The TUNEL-positive nuclei were observed exclusively in cardiomyocytes in DCM, whereas in myocarditis they were detected mainly in interstitial cells and in a few myocytes. In DCM, interstitial fibrosis was greater in the TUNEL-positive than in TUNEL-negative patients (p < 0.05). In either DCM or myocarditis, electron microscopic examination could not reveal morphologic features of apoptosis of cardiomyocytes.

CONCLUSION

The DNA strand breaks were detected in cardiomyocytes in patients with DCM and mainly in interstitial cells in myocarditis. It is possible that the DNA strand breaks can be involved in mechanisms of progressive loss of functional cardiac units in these myocardial diseases.

Smooth muscle apoptosis and vascular remodeling

PURPOSE OF REVIEW

The present review is to summarize recent advances in molecular mechanisms that regulate vascular smooth muscle cell apoptosis during vascular remodeling. In normal blood vessels apoptosis counteracts cell division, whereas apoptosis is especially crucial for regulating vascular remodeling during cardiovascular diseases.

RECENT FINDINGS

Recent results have expanded our knowledge regarding the signaling pathways and molecules that regulate vascular smooth muscle cell death in postnatal vascular remodeling. Compelling data from genetic disorders associated with vascular smooth muscle cell loss (e.g., Hutchinson-Gilford progeria syndrome) and experimental studies suggest that changes in hemodynamic and mechanical forces are major modulators for vascular smooth muscle cell apoptosis. Furthermore, understanding the therapeutic effects of antihypertensive drugs related to apoptosis may identify pathways that can improve outcomes independent of the blood pressure fall.

SUMMARY

Regulation of vascular smooth muscle cell apoptosis is a potential target to modify pathological vascular remodeling and new drugs development.

Sustained tubulo-interstitial protection in SHRs by transient losartan treatment: an effect of decelerated aging?

BACKGROUND

Hypertensive target organ damage shows characteristics of accelerated cell turnover and aging. This might have developed during the evolution of hypertension. In the kidney, high cell turnover is mainly restricted to tubular cells. It was the aim of this study to investigate whether a transient intervention in spontaneously hypertensive rats (SHRs) leads to reduced tubular cell turnover and attenuates the renal aging process and tubulo-interstitial damage in the long-term.

METHODS

SHRs (i) were prehypertensively (weeks 4-8) treated with losartan (ii) or hydralazine (iii) (20 and 4 mg/kg/day, respectively) and compared to Wistar-Kyoto (WKY) rats (iv). Groups were investigated at weeks 8 and 72 (except iii). At both time points tubular cell proliferation (proliferative cell nuclear antigen) and systolic blood pressure (SBP) were evaluated. At week 72, aging parameters such as telomere length were assessed. Renal damage was semiquantitatively assessed (scale: 0-4) by measuring the parenchyma (atrophy) and vasculature (media thickness).

RESULTS

Treatments equipotently reduced SBP in young SHRs (P < 0.01) but only losartan reduced renal proliferation (proliferative cell nuclear antigen: (i) 2.8 +/- 0.8, (ii) 1.3 +/- 0.3, (iii) 3.0 +/- 0.6, (iv) 0.1 +/- 0.1 cells/mm(2)). In SHRs treated with losartan(SHR-Los) tubular proliferation remained reduced and renal telomere length was significantly greater than in untreated SHRs (fold: (i) 1.0 +/- 0.1, (ii) 2.8 +/- 0.3, P < 0.01). Untreated SHRs (median 2.0, range 1-3; P < 0.007), but not SHR-Los (median 1.0, range 0-2; P = 0.06) demonstrated more tubular atrophy than WKY rats (median 0.5, range 0-1).

CONCLUSIONS

Transient losartan treatment reduces cell-turnover not only acutely but also for a prolonged period after drug withdrawal. This results in the long-term in reduced aging and attenuated tubulo-interstitial damage, suggesting there exists a modulating effect of angiotensin II (ANGII)-antagonism on long-term cell turnover.

Control of left ventricular mass by moxonidine involves reduced DNA synthesis and enhanced DNA fragmentation

BACKGROUND AND PURPOSE

Left ventricular hypertrophy (LVH) is a maladaptive process associated with increased cardiovascular risk. Regression of LVH is associated with reduced complications of hypertension. Moxonidine is an antihypertensive imidazoline compound that reduces blood pressure primarily by central inhibition of sympathetic outflow and by direct actions on the heart to release atrial natriuretic peptide, a vasodilator and an antihypertrophic cardiac hormone. This study investigated the effect of moxonidine on LVH and the mechanisms involved in this effect.

EXPERIMENTAL APPROACH

Spontaneously hypertensive rats were treated with several doses of moxonidine (s.c.) over 4 weeks. Blood pressure and heart rate were continuously monitored by telemetry. Body weight and water and food intake were measured weekly. Measurements also included left ventricular mass, DNA content, synthesis, fragmentation, and apoptotic/anti-apoptotic pathway proteins.

KEY RESULTS

The decrease in mean arterial pressure stabilized at approximately -10 mm Hg after 1 week of treatment and thereafter. Compared to vehicle-treated rats (100%), left ventricular mass was dose- and time-dependently reduced by treatment. This reduction remained significantly lower after normalizing to body weight. Moxonidine reduced left ventricular DNA content and inhibited DNA synthesis. DNA fragmentation transiently, but significantly increased at 1 week of moxonidine treatment and was paralleled by elevated active caspase-3 protein. The highest dose significantly decreased the apoptotic protein Bax and all doses stimulated anti-apoptotic Bcl-2 after 4 weeks of treatment.

CONCLUSIONS AND IMPLICATIONS

These studies implicate the modulation of cardiac DNA dynamics in the control of left ventricular mass by moxonidine in a rat model of hypertension.

Systemic delivery of adult stem cells improves cardiac function in spontaneously hypertensive rats

1. Heart regeneration after myocardial infarction (MI) can occur after cell therapy, but the mechanisms, cell types and delivery methods responsible for this improvement are still under investigation. In the present study, we evaluated the impact of systemic delivery of bone marrow cells (BMC) and cultivated mesenchymal stem cells (MSC) on cardiac morphology, function and mortality in spontaneously hypertensive rats (SHR) submitted to coronary occlusion. 2. Female syngeneic adult SHR, submitted or not (control group; C) to MI, were treated with intravenous injection of MSC (MI + MSC) or BMC (MI + BM) from male rats and evaluated after 1, 15 and 30 days by echocardiography. Systolic blood pressure (SBP), functional capacity, histology, mortality rate and polymerase chain reaction for the Y chromosome were also analysed. 3. Myocardial infarction induced a decrease in SBP and BMC, but not MSC, prevented this decrease. An improvement in functional capacity and ejection fraction (38 +/- 4, 39 +/- 3 and 58 +/- 2% for MI, MI + MSC and MI + BM, respectively; P < 0.05), as well as a reduction of the left ventricle infarcted area, were observed in rats from the MI + BM group compared with the other three groups. Treated animals had a significantly reduced lesion tissue score. The mortality rate in the C, MI + BM, MI + MSC and MI groups was 0, 0, 16.7 and 44.4%, respectively (P < 0.05 for the MI + MSC and MI groups compared with the C and MI + BM groups). 4. The results of the present study suggest that systemic administration of BMC can improve left ventricular function, functional capacity and, consequently, reduce mortality in an animal model of MI associated with hypertension. We speculate that the cells transiently home to the myocardium, releasing paracrine factors that recruit host cells to repair the lesion.

Activation of apoptotic processes during transition from hypertrophy to heart failure in guinea pigs

Changes in oxidative stress and apoptotic process were studied during the progression of a compensated hypertrophy to a decompensated heart failure in guinea pigs. Banding of the ascending aorta resulted in heart hypertrophy. At 10 wk, ventricle-to-body weight ratio and thickness of the interventricular septum as well as the left ventricular wall were increased significantly. Although fractional shortening and ejection fraction were decreased, there were no signs of heart failure. Furthermore, there was no increase in wet-to-dry weight ratios for the lungs and liver at this stage. However, at 20 wk, heart failure was characterized by a significant depression in heart function as indicated by a decrease in fractional shortening, and ejection fraction and a lesser increase in wall thickness from diastole to systole. Animals also showed clinical signs of heart failure, and the wet-to-dry weight ratios of the lungs and liver were significantly higher. Cardiomyocyte oxidative stress was significantly higher in the 20-wk aortic-banded group. The ratio of Bax to Bcl-xl showed an increase at 10 wk, and there was a further increase at 20 wk. Mitochondrial membrane potential in the aortic-banded animals was significantly decreased at 10 and 20 wk. Cytochrome c levels were higher in the cytosol compared with the mitochondria, leading to a considerable increase in the expression of p17 subunit of caspase-3. At 20 wk, both early and late stages of apoptosis were observed in isolated cardiomyocytes. It is suggested that an increase in oxidative stress initiates mitochondrial death pathway during the hypertrophic stage, leading to apoptosis and heart failure at a later stage.

Update on hypertension and Alzheimer's disease

Several studies report that blood pressure is increased in victims of Alzheimer's disease (AD) decades before the onset of the disease. Years before onset of Alzheimer's disease, blood pressure start to decrease and continues to decrease during the disease process. High blood pressure has also been related to pathological manifestations of Alzheimer's disease (senile plaques, neurofibrillary tangles, hippocampal atrophy). The exact mechanism behind these associations is not clear. Hypertension is also a risk factor for stroke, ischemic white matter lesions, silent infarcts, general atherosclerosis, myocardial infarction and cardiovascular diseases, and often clusters with other vascular risk factors, including diabetes mellitus, obesity and hypercholesterolemia. Also these risk factors have been related to Alzheimer's disease. Hypertension may thus cause cerebrovascular disease that may increase the possibility for individuals with AD encephalopathy to express a dementia syndrome. Hypertension may also lead to vessel wall changes in the brain, leading to hypoperfusion, ischemia and hypoxia which may initiate the pathological process of AD. Finally, subclinical AD may lead to increased blood pressure, and similar biological mechanisms may be involved in the pathogenesis of both disorders. Hypertension is a common disorder and often untreated. Several observational studies have reported that use of antihypertensives decreases risk of AD. Even though hypertension only results in a moderately increased risk of AD, or overall dementia, better treatment of hypertension may have an immense effect on the total number of demented individuals.

"How do cardiomyocytes die?" apoptosis and autophagic cell death in cardiac myocytes

BACKGROUND

Cell death constitutes one of the key events in biology. Historically, apoptosis and necrosis have been considered to represent the 2 fundamental forms of cell death. Apoptosis is a tightly regulated, energy-dependent process in which cell death follows a programmed set of events. Necrosis refers to the sum of degenerative changes that follow any type of cell death.

METHODS AND RESULTS

The role of apoptosis in development of ischemic heart disease, hypertensive heart disease, and end-stage heart failure has been well documented. Recent evidence suggests the potential role of a third mechanism of cell death, autophagy, in loss of cardiac myocytes. Autophagic cell death has been recently documented in myocardial cells from hypertrophied, failing, and hibernating myocardium.

CONCLUSION

In this review, we will list the basic mechanisms of apoptosis and autophagic cell death and examine the recent developments in apoptosis and autophagic cell death as it pertains to cardiovascular disease.

Effects of exercise training on pathological cardiac hypertrophy related gene expression and apoptosis

This study determined whether exercise training prevents pathological hypertrophy in the left ventricle by modulation of myocardial and apoptosis-associated genes. We used spontaneously hypertensive rats (n=15, non-exercise SHR), exercise-trained SHR (n=15, treadmill exercise for 12 weeks), and sedentary Wistar-Kyoto (WKY) rats (n=15). Exercise-trained SHR expressed adaptive changes such as reduced body weight, heart rate, blood pressures, left ventricle wall thickness, lipid profiles, and homocysteine level. The mRNA expression of angiotensin converting enzyme, endothelin-1, and brain natriuretic peptides in the heart was lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR, whereas mRNA expression of caveolin-3 and eNOS in the heart was higher. Bcl-2 protein was higher in the exercise-trained SHR than in the WKY and the non-exercise SHR. In contrast, Bax protein levels were lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR. Furthermore, the levels of the active forms of caspase-3 (20 kDa) were lower in the exercise-trained SHR and in the WKY than in the non-exercise SHR. These findings suggest that exercise training prevents pathological hypertrophy in the left ventricle by modulation of myocardial genes and that it interferes with a signal transduction pathway of apoptosis secondary to the pathological cardiac hypertrophy.

Apoptosis and oncosis in acute coronary syndromes: assessment and implications

The rational design of therapeutic interventions for protection of ischemic myocardium from ultimate death requires an understanding of the mechanistic basis of cardiomyocyte (CM) cell death, its timing and the tools for its quantification. Until recently, CM cell death following ischemia and/or reperfusion was considered to involve necrosis or 'accidental cell death' from very early on. Collective evidence over the past decade indicates that early CM cell death after myocardial ischemia and post-ischemic reperfusion involves apoptosis with cell shrinkage and drop-out, and/or oncosis with cell swelling followed by necrosis. This paradigm shift suggests that different approaches for cardioprotection are required. Oncologists, pathologists, anatomists and basic scientists who have studied apoptosis over the last three decades separated physiological apoptosis from inappropriate apoptosis in pathological states. Until recently, cardiologists resisted the concepts of CM apoptosis and regeneration. Cumulative evidence indicating that apoptosis in the heart may occur in different cell types, spread from one cell type to another, and occur in bursts, may have profound implications for therapies aimed at protection of ischemic myocardium by targeting CM apoptosis in acute coronary syndromes. This review focuses on a critique of the methods used for the assessment of CM apoptosis and the implications of CM apoptosis in acute coronary syndromes.

ACE2: A novel therapeutic target for cardiovascular diseases

Hypertension afflicts over 65 million Americans and poses an increased risk for cardiovascular morbidity such as stroke, myocardial infarction and end-stage renal disease resulting in significant mortality. Overactivity of the renin-angiotensin system (RAS) has been identified as an important determinant that is implicated in the etiology of these diseases and therefore represents a major target for therapy. In spite of the successes of drugs inhibiting various elements of the RAS, the incidence of hypertension and cardiovascular diseases remain steadily on the rise. This has lead many investigators to seek novel and innovative approaches, taking advantage of new pathways and technologies, for the control and possibly the cure of hypertension and related pathologies. The main objective of this review is to forward the concept that gene therapy and the genetic targeting of the RAS is the future avenue for the successful control and treatment of hypertension and cardiovascular diseases. We will present argument that genetic targeting of angiotensin-converting enzyme 2 (ACE2), a newly discovered member of the RAS, is ideally poised for this purpose. This will be accomplished by discussion of the following: (i) summary of our current understanding of the RAS with a focus on the systemic versus tissue counterparts as they relate to hypertension and other cardiovascular pathologies; (ii) the newly discovered ACE2 enzyme with its physiological and pathophysiological implications; (iii) summary of the current antihypertensive pharmacotherapy and its limitations; (iv) the discovery and design of ACE inhibitors; (v) the emerging concepts for ACE2 drug design; (vi) the current status of genetic targeting of the RAS; (vii) the potential of ACE2 as a therapeutic target for hypertension and cardiovascular disease treatment; and (viii) future perspectives for the treatment of cardiovascular diseases.

Pretreatment with tyrosine kinase inhibitor attenuates the reduction of apoptosis 24 h after ischemic preconditioning

We investigated whether ischemic preconditioning (PC) attenuates ischemia/reperfusion-induced injury in part by decreasing apoptosis and whether tyrosine kinase (TK) can regulate the signaling pathway leading to apoptosis in delayed cardioprotection. Six groups of rabbits were studied in the early phase (EP) and in the delayed phase (DP): (1) sham-operated control animals were received vehicle only (Veh-sham); (2) rabbits that received I.V. genistein (a nonspecific TK inhibitor) 10 min before ischemia (Gen-sham); (3) rabbits that received I.V. daidzein (an inactive structural analog of genistein) 10 min before ischemia (Dzn-sham); (4) rabbits preconditioned with 4 cycles of 5-min occlusion of left anterior descending coronary artery (LAD) and 10-min reperfusion (PC); (5) rabbits that received I.V. genistein, 10 min before PC (Gen-PC); (6) rabbits that received I.V. daidzein 10 min before PC (Dzn-PC). All rabbits underwent 30-min ischemia followed by 180-min reperfusion. Infarct size in the PC, Gen-PC, and Dzn-PC groups in the EP was significantly (p < 0.0001) reduced relative to controls Gen and Dzn. Delayed cardioprotection was blocked significantly (p < 0.0001) by genistein. In the EP, apoptosis was significantly (p < 0.0001) decreased in PC, Gen-PC, and Dzn-PC groups relative to controls Gen and Dzn. In the DP, a reduction of apoptosis was not seen in the Gen-PC group. This study suggests that PC reduces ischemic injury in part by decreasing apoptosis after ischemia/reperfusion and also that TK phosphorylation is involved in the signal transduction cascade leading to the decline of apoptosis in the DP.