Hypertension and atherosclerosis: clinical implications from the ALLHAT Trial

Role of Translationally Controlled Tumor Protein (TCTP) in the Development of Hypertension and Related Diseases in Mouse Models

Translationally controlled tumor protein (TCTP) is a multifunctional protein that plays a wide variety of physiological and pathological roles, including as a cytoplasmic repressor of Na,K-ATPase, an enzyme pivotal in maintaining Na+ and K+ ion gradients across the plasma membrane, by binding to and inhibiting Na,K-ATPase. Studies with transgenic mice overexpressing TCTP (TCTP-TG) revealed the pathophysiological significance of TCTP in the development of systemic arterial hypertension. Overexpression of TCTP and inhibition of Na,K-ATPase result in the elevation of cytoplasmic Ca2+ levels, which increases the vascular contractility in the mice, leading to hypertension. Furthermore, studies using an animal model constructed by multiple mating of TCTP-TG with apolipoprotein E knockout mice (ApoE KO) indicated that TCTP-induced hypertension facilitates the severity of atherosclerotic lesions in vivo. This review attempts to discuss the mechanisms underlying TCTP-induced hypertension and related diseases gleaned from studies using genetically altered animal models and the potential of TCTP as a target in the therapy of hypertension-related pathological conditions.

Therapeutic approaches to drug targets in atherosclerosis

Non-communicable diseases such as cancer, atherosclerosis and diabetes are responsible for major social and health burden as millions of people are dying every year. Out of which, atherosclerosis is the leading cause of deaths worldwide. The lipid abnormality is one of the major modifiable risk factors for atherosclerosis. Both genetic and environmental components are associated with the development of atherosclerotic plaques. Immune and inflammatory mediators have a complex role in the initiation and progression of atherosclerosis. Understanding of all these processes will help to invent a range of new biomarkers and novel treatment modalities targeting various cellular events in acute and chronic inflammation that are accountable for atherosclerosis. Several biochemical pathways, receptors and enzymes are involved in the development of atherosclerosis that would be possible targets for improving strategies for disease diagnosis and management. Earlier anti-inflammatory or lipid-lowering treatments could be useful for alleviating morbidity and mortality of atherosclerotic cardiovascular diseases. However, novel drug targets like endoglin receptor, PPARα, squalene synthase, thyroid hormone analogues, scavenger receptor and thyroid hormone analogues are more powerful to control the process of atherosclerosis. Therefore, the review briefly focuses on different novel targets that act at the starting stage of the plaque form to the thrombus formation in the atherosclerosis.

The effects of qindan-capsule-containing serum on the TGF-β1/ERK signaling pathway, matrix metalloproteinase synthesis and cell function in adventitial fibroblasts

CONTEXT

Qindan capsule (QC), a compound used in traditional Chinese medicine, has been used as an anti-hypertensive agent in clinical settings for years. Our previous studies have shown that QC can improve the morphological index of the artery, down-regulate the collagen volume fraction in the media and inhibit the transformation of smooth muscle cells. However, the detailed mechanisms underlying its effects require further investigation, which might provide more scientific evidence for the clinical treatment of hypertensive vascular remodeling (VR).

OBJECTIVE

We investigated the effects of QC-containing serum on the TGF-β1/ERK signaling pathway, cell proliferation, migration, the cell cycle, apoptosis and matrix metalloproteinase synthesis (MMPs) in rat aortic adventitial fibroblasts (AFs).

MATERIALS AND METHODS

AFs were cultured through tissue explants in vitro. The levels of extracellular signal-regulated kinase 1/2 (ERK1/2), phospho-ERK1/2 (p-ERK1/2), connective tissue growth factor (CTGF), MMP2 and MMP9 expression were measured by western blotting and RT-PCR. The proliferation and migration of AFs were measured by MTT and transwell migration assays. Cell cycle progression and apoptosis in AFs were analyzed by flow cytometry.

RESULTS

The proliferation and migration rates of AFs treated with transforming growth factor β1 (TGF-β1) for 24 h were 2.4 ± 0.75 and 2.2 ± 0.06 times higher than those of untreated AFs, and increases in the expression of p-ERK1/2 (3.7 ± 0.15 times), CTGF (3.3 ± 0.24 times), MMP2 (5.7 ± 0.37 times) and MMP9 (5.4 ± 0.46 times) (p < 0.05) were observed. Treatment with QC-containing serum significantly down-regulated cell proliferation (1.9 ± 0.06 times), migration (1.6 ± 0.05 times) and the expression of p-ERK1/2 (1.3 ± 0.75 times), CTGF (1.8 ± 0.64 times), MMP2 (1.6 ± 0.65 times) and MMP9 (1.4 ± 0.46 times) (p < 0.05). We also found that QC-containing serum down-regulated the percentage of cells in the G1 phase by 1.6 ± 0.43 times and increased early-phase apoptosis by 2.3 ± 0.33 times (p < 0.05) in AFs.

CONCLUSIONS

QC effectively inhibits the proliferation and migration of AFs and changes cell bioactivity and MMPs, possibly through the TGF-β/ERK/CTGF signaling pathway. Our findings may provide new insights into the potential function of QC in preventing or treating hypertension.

Interaction between hypertension and HSP70 variants increase the risk of cerebral ischemia in Chinese Han population: an association study

Cerebral infarction has become one of the leading diseases and a major mortality factor around the world. Atherosclerosis is recognized as one of the important causes of ischemic stroke. Recently, accumulating evidences have indicated that the anti-inflammatory and anti-apoptotic functions of the HSP70 family play an important role in cerebral ischemia. However, the association between HSP70 SNPs and ischemic stroke was also not well established. We chose 101 cases of cerebral ischemia and 100 healthy people from the Chinese Han population as our study subjects, and PCR-RFLP was employed to analyze HSP70 polymorphisms: HSP70-1+190G/C, HSP70-2+1267A/G and HSP70-hom+2437T/C. There were no significant differences in +1267A/G allele or genotype frequencies between patients with stroke and healthy controls. However, genotypes of +190CG and +2437TT were differentially distributed between the patients and controls. A significant difference of T allele distribution in the HSP70-hom+2437T/C site was observed. Logistic regression analysis indicated that genotypes of +190CG, +2437TT and T allele in HSP70-hom were risk factors of ischemic stroke. Moreover, the study has formulated that the interactions between hypertension and +190CG or +2437TT may increase the risks of ischemic stroke. The results from this study have suggested a clinical indicator for assessing the possibilities of cerebral stroke, and supply basis to clinicians to give precaution to people who are at risk of stroke.

Optimal therapeutic strategy for treating patients with hypertension and atherosclerosis: focus on olmesartan medoxomil

Cardiovascular (CV) disease is a major factor in mortality rates around the world and contributes to more than one-third of deaths in the US. The underlying cause of CV disease is atherosclerosis, a chronic inflammatory process that is clinically manifested as coronary artery disease, carotid artery disease, or peripheral artery disease. It has been predicted that atherosclerosis will be the primary cause of death in the world by 2020. Consequently, developing a treatment regimen that can slow or even reverse the atherosclerotic process is imperative. Atherogenesis is initiated by endothelial injury due to oxidative stress associated with CV risk factors including diabetes mellitus, hypertension, cigarette smoking, dyslipidemia, obesity, and metabolic syndrome. Since the renin– angiotensin–aldosterone system (RAAS) plays a key role in vascular inflammatory responses, hypertension treatment with RAAS-blocking agents (angiotensin-converting enzyme inhibitors [ACEIs] and angiotensin II receptor blockers [ARBs]) may slow inflammatory processes and disease progression. Reduced nitric oxide (NO) bioavailability has an important role in the process of endothelial dysfunction and hypertension. Therefore, agents that increase NO and decrease oxidative stress, such as ARBs and ACEIs, may interfere with atherosclerosis. Studies show that angiotensin II type 1 receptor antagonism with an ARB improves endothelial function and reduces atherogenesis. In patients with hypertension, the ARB olmesartan medoxomil provides effective blood pressure lowering, with inflammatory marker studies demonstrating significant RAAS suppression. Several prospective, randomized studies show vascular benefits with olmesartan medoxomil: reduced progression of coronary atherosclerosis in patients with stable angina pectoris (OLIVUS); decreased vascular inflammatory markers in patients with hypertension and micro- (pre-clinical) inflammation (EUTOPIA); improved common carotid intima-media thickness and plaque volume in patients with diagnosed atherosclerosis (MORE); and resistance vessel remodeling in patients with stage 1 hypertension (VIOS). Although CV outcomes were not assessed in these studies, the observed benefits in surrogate endpoints of disease suggest that RAAS suppression with olmesartan medoxomil may potentially have beneficial effects on CV outcomes in these patient populations.

Hypertension resulting from overexpression of translationally controlled tumor protein increases the severity of atherosclerosis in apolipoprotein E knock-out mice

Hypertension is a well-established etiological factor for atherogenesis. We previously showed that transgenic mice overexpressing translationally controlled tumor protein (TCTP) develop systemic arterial hypertension. In this study we explored the cardiovascular effects of TCTP overexpression and possibly of the resultant hypertension on the severity of atherosclerosis in apolipoprotein E-deficient mice. Through multiple mating of TCTP-overexpressing transgenic mice (TCTP-TG) with apolipoprotein E knock-out mice (ApoE KO), we generated non-transgenic (nTG), TCTP-TG, nTG/ApoE KO and TCTP-TG/ApoE KO mice with similar genetic background. Male mice, 7-week old, were fed a lipid-enriched Western diet for 16 weeks, and blood pressure and body weight change were monitored every 2 weeks. Plasma lipid profiles and atherosclerotic lesions in aorta were quantified at the end of study. We found that blood pressure levels of TCTP-TG and TCTP-TG/ApoE KO, were similarly elevated while nTG and nTG/ApoE KO mice were normotensive. TCTP overexpression in ApoE KO mice led to significant exacerbation of atherosclerotic lesions. Feeding Western diet resulted in increases in total cholesterol, triglyceride (TG) and low density lipoprotein, and decreased high density lipoprotein (HDL) in ApoE KO mice. No significant differences were found in plasma lipid profiles of nTG/ApoE KO and TCTP-TG/ApoE KO. This study suggests that overexpression of TCTP, which induces hypertension, also accelerates the development of atherosclerotic lesion caused by high-fat and high-cholesterol diet without significantly altering plasma lipid profiles. We conclude that TCTP-induced hypertension could increase the severity of atherosclerotic lesion and suggest that inhibition of TCTP or its signaling pathways may be a potential approach to the therapy of both diseases, hypertension and atherosclerosis.

Optimal therapeutic strategy for treating patients with hypertension and atherosclerosis: focus on olmesartan medoxomil

Cardiovascular (CV) disease is a major factor in mortality rates around the world and contributes to more than one-third of deaths in the US. The underlying cause of CV disease is atherosclerosis, a chronic inflammatory process that is clinically manifested as coronary artery disease, carotid artery disease, or peripheral artery disease. It has been predicted that atherosclerosis will be the primary cause of death in the world by 2020. Consequently, developing a treatment regimen that can slow or even reverse the atherosclerotic process is imperative. Atherogenesis is initiated by endothelial injury due to oxidative stress associated with CV risk factors including diabetes mellitus, hypertension, cigarette smoking, dyslipidemia, obesity, and metabolic syndrome. Since the renin-angiotensin-aldosterone system (RAAS) plays a key role in vascular inflammatory responses, hypertension treatment with RAAS-blocking agents (angiotensin-converting enzyme inhibitors [ACEIs] and angiotensin II receptor blockers [ARBs]) may slow inflammatory processes and disease progression. Reduced nitric oxide (NO) bioavailability has an important role in the process of endothelial dysfunction and hypertension. Therefore, agents that increase NO and decrease oxidative stress, such as ARBs and ACEIs, may interfere with atherosclerosis. Studies show that angiotensin II type 1 receptor antagonism with an ARB improves endothelial function and reduces atherogenesis. In patients with hypertension, the ARB olmesartan medoxomil provides effective blood pressure lowering, with inflammatory marker studies demonstrating significant RAAS suppression. Several prospective, randomized studies show vascular benefits with olmesartan medoxomil: reduced progression of coronary atherosclerosis in patients with stable angina pectoris (OLIVUS); decreased vascular inflammatory markers in patients with hypertension and micro- (pre-clinical) inflammation (EUTOPIA); improved common carotid intima-media thickness and plaque volume in patients with diagnosed atherosclerosis (MORE); and resistance vessel remodeling in patients with stage 1 hypertension (VIOS). Although CV outcomes were not assessed in these studies, the observed benefits in surrogate endpoints of disease suggest that RAAS suppression with olmesartan medoxomil may potentially have beneficial effects on CV outcomes in these patient populations.

Long-Term and Short-Term Changes in Antihypertensive Prescribing by Office-Based Physicians in the United States

Medication choices for the treatment of elevated blood pressure have a large potential impact on both patient outcomes and health care costs. Historic trends of prescribing for hypertension will advance the understanding of physician practice of evidence-based medicine. This study describes both long- and short-term trends in US antihypertensive prescribing from 1990 through 2004. Data were extracted from the National Disease and Therapeutic Index, a continuing survey of a national sample of US office-based physicians. Cox and Stuart and z tests were performed. Diuretics ranked among the top 3 antihypertensive drug classes throughout the entire study time span. Angiotensin-converting enzyme (ACE) inhibitors and calcium channel blockers (CCBs) were preferred over diuretics beginning in 1993, with diuretics surpassing CCBs in 2000. β-Blockers were consistently the fourth most common class until 2002, when exceeded by angiotensin II receptor antagonists (ARBs). Most recent trends indicated an immediate but short-lived increase in the prescription of thiazide diuretics after the new clinical evidence released in December 2002 demonstrating clinical equivalence of thiazides to ACE inhibitors and CCBs. In contrast, prescription of ACE inhibitors declined, accompanied by continuation of a pre-existing increase in the prescription of ARBs, whereas prescription of CCBs remained essentially stable after the new evidence was released. The recorded long- and short-term trends indicate that evidence-based clinical recommendations had an impact on antihypertensive prescribing practices, but the magnitude of impact may be smaller and of more limited duration than desired.