Telmisartan delays myocardial fibrosis in rats with hypertensive left ventricular hypertrophy by TGF-β1/Smad signal pathway

Radiation Induced Skin Fibrosis (RISF): Opportunity for Angiotensin II-Dependent Intervention

Medical procedures, such as radiation therapy, are a vital element in treating many cancers, significantly contributing to improved survival rates. However, a common long-term complication of such exposure is radiation-induced skin fibrosis (RISF), a complex condition that poses substantial physical and psychological challenges. Notably, about 50% of patients undergoing radiation therapy may achieve long-term remission, resulting in a significant number of survivors managing the aftereffects of their treatment. This article delves into the intricate relationship between RISF, reactive oxygen species (ROS), and angiotensin II (Ang II) signaling. It proposes the underlying mechanisms and examines potential treatments for mitigating skin fibrosis. The primary goal is to offer essential insights in order to better care for and improve the quality of life of cancer survivors who face the risk of developing RISF.

Differential Role of Aldosterone and Transforming Growth Factor Beta-1 in Cardiac Remodeling

Angiotensin II, a major culprit in cardiovascular disease, activates mediators that are also involved in pathological cardiac remodeling. In this context, we aimed at investigating the effects of two of them: aldosterone (Ald) and transforming growth factor beta-1 (TGF-β1) in an in vivo model. Six-week-old male wild-type (WT) and TGF-β1-overexpressing transgenic (TGF-β1-TG) mice were infused with subhypertensive doses of Ald for 2 weeks and/or treated orally with eplerenone from postnatal day 21. Thehearts' ventricles were examined by morphometry, immunoblotting to assess the intracellular signaling pathways and RT qPCR to determine hypertrophy and fibrosis marker genes. The TGF-β1-TG mice spontaneously developed cardiac hypertrophy and interstitial fibrosis and exhibited a higher baseline phosphorylation of p44/42 and p38 kinases, fibronectin and ANP mRNA expression. Ald induced a comparable increase in the ventricular-heart-weight-to-body-weight ratio and cardiomyocyte diameter in both strains, but a less pronounced increase in interstitial fibrosis in the transgenic compared to the WT mice (23.6% vs. 80.9%, p < 0.005). Ald increased the phosphorylation of p44/42 and p38 in the WT but not the TGF-β1-TG mice. While the eplerenone-enriched chow partially prevented Ald-induced cardiac hypertrophy in both genotypes and interstitial fibrosis in the WT controls, it completely protected against additional fibrosis in transgenic mice. Ald appears to induce cardiac hypertrophy independently of TGF-β1, while in the case of fibrosis, the downstream signaling pathways of these two factors probably converge.

Topical captopril: a promising treatment for secondary lymphedema

Transforming growth factor-beta 1 (TGF-β1)-mediated tissue fibrosis is an important regulator of lymphatic dysfunction in secondary lymphedema. However, TGF-β1 targeting can cause toxicity and autoimmune complications, limiting clinical utility. Angiotensin II (Ang II) modulates intracellular TGF-β1 signaling, and inhibition of Ang II production using angiotensin-converting enzyme (ACE) inhibitors, such as captopril, has antifibrotic efficacy in some pathological settings. Therefore, we analyzed the expression of ACE and Ang II in clinical lymphedema biopsy specimens from patients with unilateral breast cancer-related lymphedema (BCRL) and mouse models, and found that cutaneous ACE expression is increased in lymphedematous tissues. Furthermore, topical captopril decreases fibrosis, activation of intracellular TGF-β1 signaling pathways, inflammation, and swelling in mouse models of lymphedema. Captopril treatment also improves lymphatic function and immune cell trafficking by increasing collecting lymphatic pumping. Our results show that the renin-angiotensin system in the skin plays an important role in the regulation of fibrosis in lymphedema, and inhibition of this signaling pathway may hold merit for treating lymphedema.

The Future of Lymphedema: Potential Therapeutic Targets for Treatment

Purpose of Review

This review aims to summarize the current knowledge regarding the pharmacological interventions studied in both experimental and clinical trials for secondary lymphedema.

Recent Findings

Lymphedema is a progressive disease that results in tissue swelling, pain, and functional disability. The most common cause of secondary lymphedema in developed countries is an iatrogenic injury to the lymphatic system during cancer treatment. Despite its high incidence and severe sequelae, lymphedema is usually treated with palliative options such as compression and physical therapy. However, recent studies on the pathophysiology of lymphedema have explored pharmacological treatments in preclinical and early phase clinical trials.

Summary

Many potential treatment options for lymphedema have been explored throughout the past two decades including systemic agents and topical approaches to decrease the potential toxicity of systemic treatment. Treatment strategies including lymphangiogenic factors, anti-inflammatory agents, and anti-fibrotic therapies may be used independently or in conjunction with surgical approaches.

How Effective Is a Late-Onset Antihypertensive Treatment? Studies with Captopril as Monotherapy and in Combination with Nifedipine in Old Spontaneously Hypertensive Rats

Background: A major problem in the treatment of human hypertension is the late diagnosis of hypertension and, hence, the delayed start of treatment. Very often, hypertension has existed for a long time and cardiac damage has already developed. Therefore, we tested whether late-onset antihypertensive treatment is effective in lowering blood pressure (BP) and in reducing or even preventing left ventricular hypertrophy and fibrosis. Methods: Twenty-one male 60-week-old spontaneously hypertensive rats (SHR) were included. Fourteen rats received oral treatment with captopril (CAP) either as monotherapy or combined with nifedipine (CAP + NIF) over 22 weeks. Seven untreated SHR served as controls. We examined the therapeutic effects on BP, heart weight and histological and biochemical markers of left ventricular remodeling and fibrosis. Results: At 82 weeks of age, BP was reduced in the CAP and CAP + NIF groups by 44 and 51 mmHg, respectively (p < 0.001), but not in untreated controls. Despite the late therapy start, cardiac hypertrophy and fibrosis were attenuated compared to controls. Both treatments reduced heart weight by 1.2 mg/g (25%, p = 0.001) and collagens I and III by 66% and 60%, respectively (p < 0.001), thus proving nearly equivalent cardioprotective efficacy. Conclusion: These data clearly emphasize the benefit of antihypertensive treatment in reducing BP and mitigating the development of cardiac damage even when treatment is started late in life.

Telmisartan relieves liver fibrosis and portal hypertension by improving vascular remodeling and sinusoidal dysfunction

BACKGROUNDS

Telmisartan(TEL) has demonstrated anti-fibrotic and blood pressure lowering effect in various diseases. In this study, we aimed to explore the beneficial effects of TEL on portal hypertension(PHT).

METHODS

Two models of cirrhosis-induced PHT were involved including carbon tetrachloride injection(CCl4) and bile duct ligation(BDL). Rats were orally gavaged with TEL for 4 weeks. After that, the portal pressure(PP) was determined, and liver and mesenteric tissue specimens were collected to evaluate inflammatory response, liver fibrosis, vascular remodeling, angiogenesis, etc. RESULTS: In CCl4 PHT models, TEL decreased PP significantly from 12.79 ± 2.92 to 6.91 ± 1.19 mmHg(p < 0.05). In inflammatory response, hepatic expressions of interleukin(IL)-6, lipopolysaccharide(LPS), and tumor necrosis factor-α(TNF-α) were significantly decreased after TEL treatment. Moreover, in the liver fibrotic area, the expressions of α-smooth muscle actin(α-SMA), collagen1a1(Col1a1), desmin, transforming growth factor-β(TGF-β), and hydroxyproline, and serum hyaluronic acid were significantly decreased after TEL treatment. Additionally, the expressions of von Willebrand factor(vWF), vascular endothelial growth factor(VEGF) and platelet-derived growth factor-β(PDGF-β), matrix metallopeptidase(MMP)-2, and MMP-9 were ameliorated in liver sinusoid, while the expressions of MMP-2 and vWF were reduced in mesenteric arteries after TEL treatment. Meanwhile, TEL treatment up-regulated the hepatic expressions of an anti-fibrotic factor Krüppel-like factor-4(KLF-4) and its downstream endothelial nitric oxide synthase(eNOS) in rats with PHT. The performance of TEL in BDL model was similar but slightly weaker.

CONCLUSIONS

TEL ameliorated the cirrhosis-induced PHT by reducing liver fibrosis, inflammation responses, angiogenesis, and vascular remodeling. Collectively, KLF-4 and eNOS were the possible molecular targets for the management of cirrhosis-associated PHT.

Adiponectin Modified BMSCs Alleviate Heart Fibrosis via Inhibition TGF-beta1/Smad in Diabetic Rats

Background: Accumulating evidence suggested that bone marrow mesenchymal stem cells (BMSCs) have therapeutic potential for diabetes and heart diseases. However, the effects of BMSC on reducing myocardial fibrosis need to be optimized. This study aimed to investigate the mechanism of adiponectin (APN) modified BMSCs on myocardial fibrosis in diabetic model in vivo and in vitro.

Methods: The high-fat diet combined with streptozotocin (STZ) injection were used to induced diabetic rat model. H9c2 cells were cultured under a high glucose medium as in vitro model. The BMSCs were modified by APN plasmid or APN small interfering RNA (siRNA), then transplanted to the diabetic rats by a single tail-vein injection, or co-cultured with H9c2 cells.

Results: We demonstrated that diabetic rats showed typical diabetic symptoms, such as decreased cardiac function, accumulation of pathological lesions and collagen expression. However, these impairments were significantly prevented by the APN modified BMSCs treatment while no effects on APN siRNA modified BMSCs treated diabetic rats. Moreover, we confirmed that APN modified BMSCs could attenuate the expression of TGF-beta1/smad to suppress the myocardial fibrosis in the diabetic rats and high glucose induced H9c2 cells.

Conclusion: The present results for the first time showed that APN modified BMSCs exerted protection on cardiac fibrosis via inhibiting TGF-beta1/smad signal pathway in diabetic rats. Our findings suggested that APN modified BMSCs might be a novel and optimal therapy for the diabetic cardiomyopathy in future.

LncRNA MHRT Promotes Cardiac Fibrosis via miR-3185 Pathway Following Myocardial Infarction

Long-chain noncoding RNA (lncRNA) is a new class of molecular regulators in heart development and disease. However, the role of specific lncRNA in cardiac fibrosis remains to be fully explored. This study aimed to investigate the role and potential mechanism of lncRNA MHRT in myocardial fibrosis after myocardial infarction (MI).Cardiac fibroblasts (CFs) were isolated from a mouse model of MI. The expression levels of MHRT and miR-3185 in the hearts of MI and CFs mice treated with transforming growth factor beta 1 (TGF-β1) were analyzed by qRT-PCR. The collagen expression was assessed using qRT-PCR and Western blot. Cell proliferation was assessed by performing MTT and EdU assays. The direct interaction between lncRNA and miRNA was analyzed by luciferase assay, RNA-binding protein immunoprecipitation (RIP) assay, and RNA pull-down assay.The expression levels of MHRT were raised in MI and CFs mice treated with TGF-β1. Overexpression of MHRT promoted collagen production and CF proliferation, while silencing of MHRT showed the opposite effect. MiR-3185 was a target gene of MHRT. In addition, overexpression of MHRT reduced the expression levels of miR-3185, and siMHRT reversed the inhibitory effect of TGF-β1 on the expression of miR-3185. Overexpression of miR-3185 inhibited the upregulation of Col I and Col III induced by TGF-β1.MHRT promoted cardiac fibrosis after MI through miR-3185 and increased myocardial collagen deposition and promoted myocardial fibrosis.

Irbesartan ameliorates myocardial fibrosis in diabetic cardiomyopathy rats by inhibiting the TGFβ1/Smad2/3 pathway

Myocardial fibrosis (MF) is an important pathological change in diabetic cardiomyopathy. The aim of the present study was to investigate whether irbesartan serves a role in improving MF in a diabetic rat model. Fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels were measured in rats using biochemical methods. Heart weight index (HWI), left ventricular weight index (LVWI), left ventricular systolic pressure (LVSP) and left ventricular end-diastolic pressure (LVEDP) were also measured, whilst type I collagen and hydroxyproline content in myocardial tissue was quantified. Western blotting was used to measure the expression of transforming growth factor β1 (TGFβ1), phosphorylated (p)-Smad2/3 and collagen type I α 1 chain (COL1A1) inmyocardial tissues or rat cardiac fibroblast (RCF) cells. Cell proliferation was measured using EdU staining. Procollagen type III N-terminal peptide (PIIINP) content, FBG, TC, TG and LDL-C levels were found to be significantly higher, whilst HDL-C levels were found to be significantly lower in rats in the diabetic group. Those in the diabetic group also exhibited significantly elevated HWI, LVWI, LVEDP, myocardial tissue type I collagen content and hydroxyproline content values, but significantly reduced LVSP. Changes in the aforementioned indicators were reversed after treatment with irbesartan, where the protein expression levels of TGFβ1 and p-Smad2/3 in myocardial tissue were also significantly reduced. In RCF cells, irbesartan significantly reversed high glucose-induced upregulation of TGFβ1 expression, Smad2/3 phosphorylation and COL1A1 expression, as well as reducing cell proliferation and rat type I PICP and PIIINP levels. Application of pirfenidone produced additive effects on reducing the expression levels of the proteins aforementioned when combined with irbesartan. Therefore, the present results demonstrated that irbesartan reduced the activity of the TGFβ1/Smad2/3 pathway and ameliorated diabetic MF by downregulating the expression of TGFβ1.

Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases in Extracellular Matrix Remodeling during Left Ventricular Diastolic Dysfunction and Heart Failure with Preserved Ejection Fraction: A Systematic Review and Meta-Analysis

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are pivotal regulators of extracellular matrix (ECM) composition and could, due to their dynamic activity, function as prognostic tools for fibrosis and cardiac function in left ventricular diastolic dysfunction (LVDD) and heart failure with preserved ejection fraction (HFpEF). We conducted a systematic review on experimental animal models of LVDD and HFpEF published in MEDLINE or Embase. Twenty-three studies were included with a total of 36 comparisons that reported established LVDD, quantification of cardiac fibrosis and cardiac MMP or TIMP expression or activity. LVDD/HFpEF models were divided based on underlying pathology: hemodynamic overload (17 comparisons), metabolic alteration (16 comparisons) or ageing (3 comparisons). Meta-analysis showed that echocardiographic parameters were not consistently altered in LVDD/HFpEF with invasive hemodynamic measurements better representing LVDD. Increased myocardial fibrotic area indicated comparable characteristics between hemodynamic and metabolic models. Regarding MMPs and TIMPs; MMP2 and MMP9 activity and protein and TIMP1 protein levels were mainly enhanced in hemodynamic models. In most cases only mRNA was assessed and there were no correlations between cardiac tissue and plasma levels. Female gender, a known risk factor for LVDD and HFpEF, was underrepresented. Novel studies should detail relevant model characteristics and focus on MMP and TIMP protein expression and activity to identify predictive circulating markers in cardiac ECM remodeling.

Sinapic Acid Attenuates Cardiovascular Disorders in Rats by Modulating Reactive Oxygen Species and Angiotensin Receptor Expression

The main avoidable risk factor for cardiovascular conditions is high blood pressure (hypertension). At global level, hypertension is believed to be responsible for a 54% stroke-related mortality rate and a 47% mortality rate associated with coronary heart disease. It is postulated that sinapic acid (SA) could help in hypertension management because it displays robust antioxidant, antihyperglycemic, and peroxynitrite scavenging effects. To explore this hypothesis, this work examined the effect of SA on oxidative stress and cardiovascular disease in rats with hypertension by comparison against captopril. For this purpose, 50 male rats were used and equally allocated to five groups, namely, normal control, positive control (L-NAME), L-NAME with concomitant captopril administration, L-NAME with concomitant SA administration, and L-NAME with concomitant administration of both SA and captopril. Results showed that, by contrast to control, L-NAME exhibited marked elevation in serum CK-MB, total cholesterol, triglycerides, VLDL-C, LDL-C, Ang II, AT2R, ET-1, and angiopoietin-2; on the other hand, L-NAME exhibited marked reduction in serum HDL-C, superoxide dismutase (SOD) activity, nitric oxide synthase 3 (NOS3), and glutathione (GSH). Furthermore, joint administration of SA and captopril ameliorated hypertension, enhanced cardiovascular function, hindered hyperlipidemia, and decreased oxidative stress and myocardial hypertrophy displayed by rats with hypertension. Based on such findings, better chemopreventive or therapeutic approaches can be devised to manage hypertension and cardiovascular conditions.

Telmisartan improves myocardial remodeling by inhibiting leptin autocrine activity and activating PPARγ

The mechanism responsible for myocardial remodeling in hypertensive left ventricular hypertrophy (LVH) is complex. This study was designed to investigate the role of telmisartan in improving myocardial remodeling in hypertensive LVH and to explore the molecular mechanisms underlying the effects of telmisartan on hypertensive LVH. Hypertensive LVH was established in eight-week-old male Sprague–Dawley (SD) rats by abdominal aortic constriction. Telmisartan was intragastrically administered six weeks after surgery. Telmisartan improved cardiac dysfunction and myocardial fibrosis and reduced myocardial renin-angiotensin-aldosterone system (RAAS) activity and leptin levels in hypertensive LVH rats. To assess the mechanism underlying hypertensive LVH, cardiac fibroblasts were treated in vitro with angiotensin II (Ang II) or leptin, plus various inhibitors. Ang II stimulated leptin synthesis and secretion in cardiac fibroblasts by promoting AP-1 nuclear translocation via the AT1R-ROS-ERK1/2 pathway. Leptin induced collagen metabolism disorder in cardiac fibroblasts via the JAK2/STAT3 pathway. Telmisartan improved collagen metabolism disorder by inhibiting leptin induced by local Ang II in an autocrine manner. Telmisartan also improved Ang II-induced collagen metabolism disorder by inhibiting STAT3 phosphorylation, a leptin downstream signal, by activating PPAR-γ. Telmisartan therefore improved myocardial remodeling in hypertensive LVH rats by acting as an AT1R antagonist, inhibiting leptin autocrine activity induced by local Ang II and by acting as a PPAR-γ agonist, inhibiting downstream leptin activation of STAT3 phosphorylation. These findings indicate the crosstalk between local myocardial RAAS and leptin and suggest a molecular mechanism by which telmisartan improves myocardial remodeling in hypertensive LVH.

Impact statement

This study shows the crosstalk between local myocardial RAAS and leptin in hypertensive LVH rats; that Ang II induces myocardial remodeling by stimulating leptin autocrine activity by promoting AP-1 nuclear translocation via the AT1R-ROS-ERK1/2 pathway; and that telmisartan improves myocardial remodeling by inhibiting local Ang II-induced leptin autocrine activity and by inhibiting the leptin downstream signal STAT3 phosphorylation by activating PPAR-γ. These findings reveal novel molecular mechanisms by which telmisartan improves myocardial remodeling and could help to identify therapeutic targets for hypertensive LVH.

MicroRNA-663 participates in myocardial fibrosis through interaction with TGF-β1

MicroRNA-663 (miRNA-663) regulates the expression of transforming growth factor β1 (TGF-β1), which participates in the pathogenesis of myocardial fibrosis. Therefore, microRNA-663 may also serve a role in myocardial fibrosis. The present study aimed to determine whether miRNA-663 participates in myocardial fibrosis via interaction with TGF-β1. In the present study, the expression of miRNA-663 was significantly downregulated, whereas that of TGF-β1 was significantly upregulated in the endomyocardial biopsies of patients with myocardial fibrosis compared with those in control necropsies. Pearson's correlation analysis revealed that the expression levels of miRNA-663 were negatively correlated with those of TGF-β1 in patients with myocardial fibrosis, but not in the controls. Receiver operating characteristic curve analysis demonstrated that the downregulation of miRNA-663 distinguished patients with myocardial fibrosis from controls. In the AC16 human cardiomyocyte cell line, miRNA-663 overexpression resulted in downregulated TGF-β1 expression, whereas exogenous TGF-β1 treatment exhibited no significant effects on miRNA-663 expression. These results indicate that miRNA-663 may participate in myocardial fibrosis, possibly through interaction with TGF-β1.

Effects of Geniposide from Gardenia Fruit Pomace on Skeletal-Muscle Fibrosis

Geniposide is the main bioactive constituent of gardenia fruit. Skeletal-muscle fibrosis is a common and irreversibly damaging process. Numerous studies have shown that geniposide could improve many chronic diseases, including metabolic syndrome and tumors. However, the effects of geniposide on skeletal-muscle fibrosis are still poorly understood. Here, we found that crude extracts of gardenia fruit pomace could significantly decrease the expression of profibrotic genes in vitro. Moreover, geniposide could also reverse profibrotic-gene expression induced by TGF-β and Smad4, a regulator of skeletal-muscle fibrosis. In addition, geniposide treatment could significantly downregulate profibrotic-gene expression and improve skeletal-muscle injuries in a mouse model of contusion. These results together suggest that geniposide has an antifibrotic effect on skeletal muscle through the suppression of the TGF-β-Smad4 signaling pathway.

The expression of Smad signaling pathway in myocardium and potential therapeutic effects

Myocardial infarction (MI) is a life-threatening disease. The expression of Smad proteins in the ischemic myocardium changes significantly following myocardial infarction, suggesting a close relationship between Smad proteins and heart remodeling. Moreover, it is known that the expression of Smads is regulated by transforming growth factor-β (TGF-β) and bone morphogenetic proteins (BMP). Based on these findings, regulating the expression of Smad proteins by targeting TGF-β and BMP in the ischemic myocardium may be considered to be a possible therapeutic strategy for the treatment of myocardial infarction.

Effects of telmisartan on fat distribution: a meta-analysis of randomized controlled trials

OBJECTIVES

Several meta-analyses have confirmed the positive metabolic effects of telmisartan, an angiotensin II receptor blocker that can also act as a partial peroxisome proliferator-activated receptor-γ agonist, compared to those of other angiotensin II receptor blockers. These effects include decreased fasting glucose, glycosylated hemoglobin, interleukin-6, and tumor necrosis factor-α levels. However, no systemic analysis of telmisartan's effects on body fat distribution has been performed. We performed a meta-analysis of randomized controlled telmisartan trials to investigate its effects on body weight, fat distribution, and visceral adipose reduction.

RESEARCH DESIGN AND METHODS

A literature search was performed using Embase, MEDLINE, and the Cochrane Library between January 1966 and November 2013. Randomized controlled trials in English and meeting the following criterion were included: random assignment of hypertensive participants with overweight/obesity, metabolic syndrome, or glucose intolerance to telmisartan or control therapy group.

RESULTS

Of 651 potentially relevant reports, 15 satisfied the inclusion criterion. While visceral fat area was significantly lower in the telmisartan group than in the control group (weighted mean difference = -18.13 cm(2), 95% C.I. = -27.16 to -9.11, Pχ(2) = 0.19, I(2) = 41%), subcutaneous fat area was similar (weighted mean difference =2.94 cm(2), 95% C.I. = -13.01 to 18.89, Pχ(2) = 0.30, I(2) = 17%). Total cholesterol levels were significantly different between the groups (standardized mean difference = -0.24, 95% C.I. = -0.45 to -0.03, Pχ(2) = 0.0002, I(2) = 67%).

LIMITATIONS

Limitations include: (1) limited number of studies, especially those evaluating fat distribution; (2) different imaging modalities to assess visceral fat area (V.F.A.) and subcutaneous fat area (S.F.A.); (3) observed heterogeneity.

CONCLUSION

The findings suggest that telmisartan affected fat distribution, inducing visceral fat reduction, and thus could be useful in hypertensive patients with obesity/overweight, metabolic syndrome, or glucose intolerance.

Histone deacetyltransferase inhibitors Trichostatin A and Mocetinostat differentially regulate MMP9, IL-18 and RECK expression, and attenuate Angiotensin II-induced cardiac fibroblast migration and proliferation

Histone acetylation/deacetylation plays a key role in the epigenetic regulation of multiple pro-fibrotic genes. Here we investigated the effects of histone deacetyltransferase (HDAC) inhibition on angiotensin (Ang)-II-induced pro-fibrotic changes in adult mouse cardiac fibroblasts (CF). CF express class I HDACs 1 and 2, and Ang-II induces their activation. Notably, silencing HDAC1 or HDAC2 attenuated Ang-II induced CF proliferation and migration. Under basal conditions, HDAC1 dimerizes with HDAC2 in CF and Ang-II reversed this interaction. Treatment with Trichostatin A (TSA), a broad-spectrum HDAC inhibitor, restored their physical association, and attenuated Ang-II-induced MMP9 expression, IL-18 induction, and extracellular matrix (collagen I, collagen III and fibronectin) production. Further, TSA inhibited Ang-II-induced MMP9 and Il18 transcription by blocking NF-κB and AP-1 binding to their respective promoter regions. By inhibiting Sp1 binding to RECK promoter, TSA reversed Ang-II-induced RECK suppression, collagen and fibronectin expression, and CF migration and proliferation. The class I-specific HDAC inhibitor Mocetinostat (MGCD) recapitulated TSA effects on Ang-II-treated CF. Together, these results demonstrate that targeting HDACs attenuates the pro-inflammatory and pro-fibrotic effects of Ang-II on CF.

Angiotensin II type 1 receptor antagonists in animal models of vascular, cardiac, metabolic and renal disease

We have reviewed the effects of angiotensin II type 1 receptor antagonists (ARBs) in various animal models of hypertension, atherosclerosis, cardiac function, hypertrophy and fibrosis, glucose and lipid metabolism, and renal function and morphology. Those of azilsartan and telmisartan have been included comprehensively whereas those of other ARBs have been included systematically but without intention of completeness. ARBs as a class lower blood pressure in established hypertension and prevent hypertension development in all applicable animal models except those with a markedly suppressed renin-angiotensin system; blood pressure lowering even persists for a considerable time after discontinuation of treatment. This translates into a reduced mortality, particularly in models exhibiting marked hypertension. The retrieved data on vascular, cardiac and renal function and morphology as well as on glucose and lipid metabolism are discussed to address three main questions: 1. Can ARB effects on blood vessels, heart, kidney and metabolic function be explained by blood pressure lowering alone or are they additionally directly related to blockade of the renin-angiotensin system? 2. Are they shared by other inhibitors of the renin-angiotensin system, e.g. angiotensin converting enzyme inhibitors? 3. Are some effects specific for one or more compounds within the ARB class? Taken together these data profile ARBs as a drug class with unique properties that have beneficial effects far beyond those on blood pressure reduction and, in some cases distinct from those of angiotensin converting enzyme inhibitors. The clinical relevance of angiotensin receptor-independent effects of some ARBs remains to be determined.

[Irbesartan ameliorates cardiac inflammation in type 2 diabetic db/db mice]

OBJECTIVE

To investigate the protective effects of irbesartan against cardiac inflammation associated with diabetes and obesity in the db/db mouse model of type 2 diabetes and explore the underlying mechanisms.

METHODS

Twenty- four 10-week-old diabetic db/db mice were equally randomized into irbesartan treatment (50 mg/kg per day) group and model group, using 12 nondiabetic littermates (db/+) as the controls, The mice were treated with irbesartan or saline vehicle for 16 consecutive weeks, after which the heart pathology was observed and the heart weight, body weight, and serum levels of fasting blood glucose (FBG), total cholesterol(TC), and triglycerides(TG) were measured. The expression of nuclear factor-kappaB (NF-κB) p65 in the myocardium was assessed with immunohistochemistry, the protein levels of P-IκBα ,IκBα and β-actin were analyzed with Western blotting, and the pro-inflammatory cytokines IL-6 and TNF-α mRNA were detected using quantitative real-time PCR (qPCR).

RESULTS

Compared with db/+ mice, the saline-treated db/db mice developed obesity, hyperglycemia and hyperlipidemia (P<0.01). Histopathological examination of the heart tissue revealed inflammatory cell infiltration, increased myocardial interstitium and disorders of myocardial fiber arrangement. The diabetic mice showed increased P-IαBα and decreased IκBα protein levels, enhanced activity and expression of NF-κB in the hearts, and increased mRNA expression of IL-6 and TNF-α in the myocardium. These abnormalities were all associated with increased inflammatory response. Treatment with irbesartan improved the heart architecture and attenuated high glucose-induced inflammation in the diabetic mice.

CONCLUSION

Treatment with irbesartan attenuates cardiac inflammation in type 2 diabetic db/db mice, and this effect was probably associated with the suppression of cardiac angiotensin II and NF-κB signaling pathway.

Transforming growth factor beta1 and aldosterone

PURPOSE OF REVIEW

It is well established that blocking the renin-angiotensin-aldosterone system (RAAS) is effective for the treatment of cardiovascular and renal complications in hypertension and diabetes mellitus. Although the induction of transforming growth factor beta1 (TGFbeta1) by components of the RAAS mediates the hypertrophic and fibrogenic changes in cardiovascular-renal complications, it is still controversial as to whether TGFbeta1 can be a target to prevent such complications. Here, we review recent findings on the role of TGFbeta1 in fluid homeostasis, focusing on the relationship with aldosterone.

RECENT FINDINGS

TGFbeta1 suppresses the adrenal production of aldosterone and renal tubular sodium reabsorption. We have generated mice with TGFbeta1 mRNA expression graded in five steps, from 10 to 300% of normal, and found that blood pressure and plasma volume are negatively regulated by TGFbeta1. Notably, the 10% hypomorph exhibits primary aldosteronism and sodium and water retention due to markedly impaired urinary excretion of water and electrolytes.

SUMMARY

These results identify TGFbeta signalling as an important counterregulatory system against aldosterone. Understanding the molecular mechanisms for the suppressive effects of TGFbeta1 on adrenocortical and renal function may further our understanding of primary aldosteronism, as well as assist in the development of novel therapeutic strategies for hypertension.

Oral administration of veratric acid, a constituent of vegetables and fruits, prevents cardiovascular remodelling in hypertensive rats: a functional evaluation

In our previous studies, veratric acid (VA) shows beneficial effect on hypertension and its associated dyslipidaemia. In continuation, this study was designed to investigate the effect of VA, one of the major benzoic acid derivatives from vegetables and fruits, on cardiovascular remodelling in hypertensive rats, primarily assessed by functional studies using Langendorff isolated heart system and organ bath system. Hypertension was induced in male albino Wistar rats by oral administration of N ω -nitro-l-arginine methyl ester hydrochloride (l-NAME) (40 mg/kg body weight (b.w.)) in drinking water for 4 weeks. VA was orally administered at a dose of 40 mg/kg b.w. l-NAME-treated rats showed impaired cardiac ventricular and vascular function, evaluated by Langendorff isolated heart system and organ bath studies, respectively; a significant increase in the lipid peroxidation products such as thiobarbituric acid-reactive substances and lipid hydroperoxides in aorta; and a significant decrease in the activities of superoxide dismutase, catalase, glutathione peroxidase and levels of GSH, vitamin C and vitamin E in aorta. Fibrotic remodelling of the aorta and heart were assessed by Masson's Trichrome staining and Van Gieson's staining, respectively. In addition, l-NAME rats showed increased heart fibronectin expression assessed by immunohistochemical analysis. VA supplementation throughout the experimental period significantly normalised cardiovascular function, oxidative stress, antioxidant status and fibrotic remodelling of tissues. These results of the present study conclude that VA acts as a protective agent against hypertension-associated cardiovascular remodelling.

Angiotensin receptor I stimulates osteoprogenitor proliferation through TGFβ-mediated signaling

Clinical studies of large human populations and pharmacological interventions in rodent models have recently suggested that anti-hypertensive drugs that target angiotensin II (Ang II) activity may also reduce loss of bone mineral density. Here, we identified in a genetic screening the Ang II type I receptor (AT1R) as a potential determinant of osteogenic differentiation and, implicitly, bone formation. Silencing of AT1R expression by RNA interference severely impaired the maturation of a multipotent mesenchymal cell line (W20-17) along the osteoblastic lineage. The same effect was also observed after the addition of the AT1R antagonist losartan but not the AT2R inhibitor PD123,319. Additional cell culture assays traced the time of greatest losartan action to the early stages of W20-17 differentiation, namely during cell proliferation. Indeed, addition of Ang II increased proliferation of differentiating W20-17 and primary mesenchymal stem cells and this stimulation was reversed by losartan treatment. Cells treated with losartan also displayed an appreciable decrease of activated (phosphorylated)-Smad2/3 proteins. Moreover, Ang II treatment elevated endogenous transforming growth factor β (TGFβ) expression considerably and in an AT1R-dependent manner. Finally, exogenous TGFβ was able to restore high proliferative activity to W20-17 cells that were treated with both Ang II and losartan. Collectively, these results suggest a novel mechanism of Ang II action in bone metabolism that is mediated by TGFβ and targets proliferation of osteoblast progenitors.

Prenatal exposure to lipopolysaccharide results in myocardial fibrosis in rat offspring

The epigenetic plasticity hypothesis indicates that exposure during pregnancy may cause adult-onset disorders, including hypertension, myocardial infarction and heart failure. Moreover, myocardial fibrosis coincides with hypertension, myocardial infarction and heart failure. This study was designed to investigate the effects of prenatal exposure to lipopolysaccharide (LPS) on myocardial fibrosis. The result showed that at six and 16 weeks of age, the LPS-treated offspring exhibited increased collagen synthesis, an elevated cardiac index (CI), higher mRNA levels of TIMP-2 and TGFβ and a reduced mRNA level of MMP2. The protein levels corresponded to the mRNA levels. The offspring that were prenatally treated with pyrrolidine dithiocarbamic acid (PDTC), an inhibitor of NF-κB, displayed improvements in the CI and in collagen synthesis. Moreover, PDTC ameliorated the expression of cytokines and proteins associated with myocardial fibrosis. The results showed that maternal inflammation can induce myocardial fibrosis in offspring during aging accompanied by an imbalance of TIMP-2/MMP2 and TGFβ expression.

Therapeutic effects of udenafil on pressure-overload cardiac hypertrophy

This study was performed to determine whether the newly developed phosphodiesterase type 5 (PDE5) inhibitor udenafil had beneficial effects on pressure-overload cardiac hypertrophy. Pressure overload cardiac hypertrophy was created by using suprarenal aortic constriction (SAC) in male Sprague-Dawley rats. Rats were divided into three groups: sham (n=19), SAC (n=18) and SAC+udenafil (n=14) groups. Three-week periods of SAC provoked significant left ventricular (LV) hypertrophy. Udenafil was administered (20 mg kg(-1) PO, daily) between the 3rd and 20th weeks after SAC in the SAC+udenafil group. Udenafil improved the survival rate (log-rank P=0.012) and exercise capacity (maximal exercise duration at the 20th week after surgery: 448±54 s for the SAC+udenafil group versus 317±73 s for the SAC group, P<0.05) of the rats with SAC. Serial echocardiographic examinations showed that udenafil attenuated LV remodeling processes following SAC (mean LV end-diastolic dimension at the 20th week after surgery: 9.84±0.59 mm for SAC and 9.05±0.58 mm for SAC+udenafil group, P<0.05). Invasive hemodynamic studies showed that udenafil improved the LV performance. Udenafil-attenuated myocardial fibrosis and apoptosis. Udenafil also decreased myocardial matrix metalloproteinase-9 expression and augmented serum interleukin-10 concentration. Long-term udenafil use prevented cardiac remodeling and improved exercise capacity and survival in rats exposed to pressure-overload cardiac hypertrophy.

Suppression of TGF-β1/Smad signaling pathway by sesamin contributes to the attenuation of myocardial fibrosis in spontaneously hypertensive rats

This study investigated the effect of sesamin on myocardial fibrosis in spontaneously hypertensive rats (SHRs) and the possible mechanisms involved. Twenty-eight male SHRs were randomly allocated to SHR group, Ses160 group (sesamin 160 mg/kg), Ses80 group (sesamin 80 mg/kg) and Cap30 group (captopril 30 mg/kg). Seven male WKY rats were used as control. Sesamin and captopril were administered intragastrically for 12 weeks. Captopril significantly reduced systolic blood pressure and angiotensin II (Ang II) levels in SHRs, accompanied by a marked attenuation of left ventricular hypertrophy (LVH) and collagen deposition (P <0.05 or P <0.01). Though sesamin had no significant influence on Ang II levels, and the hypotensive effect was also significantly inferior to that of captopril (P <0.05 or P <0.01), however, the improvement of LVH and collagen deposition was similar to that in captopril group. Sesamin markedly reduced transforming growth factor-β1 (TGF-β1) content in cardiac tissues, with Smad3 phosphorylation decreased and Smad7 protein expression increased notably (P <0.05 or P <0.01). Protein expression of type I collagen and type III collagen, target genes of Smad3, was down-regulated markedly by sesamin (P <0.05 or P <0.01). In addition, sesamin significantly increased total antioxidant capacity and superoxide dismutase protein in cardiac tissues (P <0.05 or P <0.01), while the expression of NADPH oxidase subunit p47phox and malondialdehyde content were reduced markedly (P <0.05 or P <0.01). In vitro studies also demonstrated that sesamin was able to suppress Ang II induced phosphorylation of Smad3 and secretion of TGF-β1 and type I and type III collagen in cultured rat cardiac fibroblasts. These data suggest that sesamin is capable of attenuating hypertensive myocardial fibrosis through, at least partly, suppression of TGF-β1/Smad signaling pathway.

AVE 3085, a novel endothelial nitric oxide synthase enhancer, attenuates cardiac remodeling in mice through the Smad signaling pathway

AVE 3085 is a novel endothelial nitric oxide synthase enhancer. Although AVE 3085 treatment has been shown to be effective in spontaneously restoring endothelial function in hypertensive rats, little is known about the effects and mechanisms of AVE 3085 with respect to cardiac remodeling. The present study was designed to examine the effects of AVE 3085 on cardiac remodeling and the mechanisms underlying the effects of this compound. Mice were subjected to aortic banding to induce cardiac remodeling and were then administered AVE 3085 (10 mg kg day(-1), orally) for 4 weeks. At the end of the treatment, the aortic banding-treated mice exhibited significant elevations in cardiac remodeling, characterized by an increase in left ventricular weight relative to body weight, an increase in the area of collagen deposition, an increase in the mean myocyte diameter, and increases in the gene expressions of the hypertrophic markers atrial natriuretic peptide (ANP) and β-MHC. These indexes were significantly decreased in the AVE 3085-treated mice. Furthermore, AVE 3085 treatment reduced the expression and activation of the Smad signaling pathway in the aortic banding-treated mice. Our data showed that AVE 3085 attenuated cardiac remodeling, and this effect was possibly mediated through the inhibition of Smad signaling.

DPP-4 inhibitor sitagliptin prevents inflammation and oxidative stress of heart and kidney in two kidney and one clip (2K1C) rats

BACKGROUND

Hyperglycemia and insulin resistance often develop cardiovascular and nephrological dysfunction in diabetic patients. Sitagliptin is used to treat diabetes and showed potential benefit in lowering increased blood glucose level in diabetes. This investigation reports the effect of sitagliptin treatment on oxidative stress in kidney and heart of 2K1C rats.

METHODS

Male Long Evans rats underwent unilateral surgical stenosis of the renal artery [2-kidney-1-clip (2K1C) method]. These animals entered a 4-weeks dosing period with sitagliptin. Blood and urine sampling and organ harvesting were finally performed. Blood plasma, heart, kidney tissues and urine were tested for the assessment of inflammation and oxidative stress in kidney and heart of 2K1C rats after 4 weeks of surgery.

RESULTS

2K1C rats showed cardiac hypertrophy, increased left ventricular wet weight compared to sham which was not significantly altered by sitagliptin treatment. Uric acid and creatinin concentrations were also increased in 2K1C rats. Sitagliptin significantly prevented the elevation of uric acid and creatinin concentration in plasma and urine in this rat model. Oxidative stress markers in plasma such as malondialdehyde (MDA), nitric oxide (NO), and advanced protein oxidation product (APOP) concentrations were increased in the 2K1C rats as compared to sham-operated animals. Increased concentrations of these oxidative stress markers were also normalized by sitagliptin treatment. 2K1C rats also showed increased level of uric acid and creatinine both in plasma and urine; which are also reduced to normal level in sitagliptin treated rats. Moreover, 2K1C surgery initiated inflammatory cell infiltration, increased MPO activity and fibrosis in both heart and kidneys which were further ameliorated by sitagliptin treatment.

CONCLUSION

Our study suggests that sitagliptin treatment in 2K1C rats prevented inflammation and fibrosis of heart and kidney by ameliorating elevated oxidative stress in heart and kidney tissues.

Sinapic acid prevents hypertension and cardiovascular remodeling in pharmacological model of nitric oxide inhibited rats

Objectives

Hypertensive heart disease is a constellation of abnormalities that includes cardiac fibrosis in response to elevated blood pressure, systolic and diastolic dysfunction. The present study was undertaken to examine the effect of sinapic acid on high blood pressure and cardiovascular remodeling.

Methods

An experimental hypertensive animal model was induced by L-NAME intake on rats. Sinapic acid (SA) was orally administered at a dose of 10, 20 and 40 mg/kg body weight (b.w.). Blood pressure was measured by tail cuff plethysmography system. Cardiac and vascular function was evaluated by Langendorff isolated heart system and organ bath studies, respectively. Fibrotic remodeling of heart and aorta was assessed by histopathologic analyses. Oxidative stress was measured by biochemical assays. mRNA and protein expressions were assessed by RT-qPCR and western blot, respectively. In order to confirm the protective role of SA on endothelial cells through its antioxidant property, we have utilized the in vitro model of H₂O₂-induced oxidative stress in EA.hy926 endothelial cells.

Results

Rats with hypertension showed elevated blood pressure, declined myocardial performance associated with myocardial hypertrophy and fibrosis, diminished vascular response, nitric oxide (NO) metabolites level, elevated markers of oxidative stress (TBARS, LOOH), ACE activity, depleted antioxidant system (SOD, CAT, GPx, reduced GSH), aberrant expression of TGF-β, β-MHC, eNOS mRNAs and eNOS protein. Remarkably, SA attenuated high blood pressure, myocardial, vascular dysfunction, cardiac fibrosis, oxidative stress and ACE activity. Level of NO metabolites, antioxidant system, and altered gene expression were also repaired by SA treatment. Results of in vitro study showed that, SA protects endothelial cells from oxidative stress and enhance the production of NO in a concentration dependent manner.

Conclusions

Taken together, these results suggest that SA may have beneficial role in the treatment of hypertensive heart disease by attenuating fibrosis and oxidative stress through its antioxidant potential.

β1-Adrenergic blockers exert antioxidant effects, reduce matrix metalloproteinase activity, and improve renovascular hypertension-induced cardiac hypertrophy

Hypertension induces left-ventricular hypertrophy (LVH) by mechanisms involving oxidative stress and unbalanced cardiac matrix metalloproteinase (MMP) activity. We hypothesized that β1-adrenergic receptor blockers with antioxidant properties (nebivolol) could reverse hypertension-induced LVH more effectively than conventional β1-blockers (metoprolol) when used at doses that exert similar antihypertensive effects. Two-kidney one-clip (2K1C) hypertension was induced in male Wistar rats. Six weeks after surgery, hypertensive and sham rats were treated with nebivolol (10 mg kg(-1)day(-1)) or metoprolol (20 mg kg(-1)day(-1)) for 4 weeks. Systolic blood pressure was monitored weekly by tail-cuff plethysmography. LV structural changes and fibrosis were studied in hematoxylin/eosin- and picrosirius-stained sections, respectively. Cardiac MMP levels and activity were determined by in situ zymography, gel zymography, and immunofluorescence. Dihydroethidium and lucigenin-derived chemiluminescence assays were used to assess cardiac reactive oxygen species (ROS) production. Nitrotyrosine levels were determined in LV samples by immunohistochemistry and green fluorescence and were evaluated using the ImageJ software. Cardiac protein kinase B/Akt (AKT) phosphorylation state was assessed by Western blot. Both β-blockers exerted similar antihypertensive effects and attenuated hypertension-induced cardiac remodeling. Both drugs reduced myocyte hypertrophy and collagen deposition in 2K1C rats. These effects were associated with lower cardiac ROS and nitrotyrosine levels and attenuation of hypertension-induced increases in cardiac MMP-2 levels and in situ gelatinolytic activity after treatment with both β-blockers. Whereas hypertension increased AKT phosphorylation, no effects were found with β-blockers. In conclusion, we found evidence that two β1-blockers with different properties attenuate hypertension-induced LV hypertrophy and cardiac collagen deposition in association with significant cardiac antioxidant effects and MMP-2 downregulation, thus suggesting a critical role for β1-adrenergic receptors in mediating those effects. Nebivolol is not superior to metoprolol, at least with respect to their capacity to reverse hypertension-induced LVH.

Comparison of two preclinical myocardial infarct models: coronary coil deployment versus surgical ligation

Background

Despite recent advances, myocardial infarction (MI) remains the leading cause of death worldwide. Pre-clinical animal models that closely mimic human MI are pivotal for a quick translation of research and swine have similarities in anatomy and physiology. Here, we compared coronary surgical ligation versus coil embolization MI models in swine.

Methods

Fifteen animals were randomly distributed to undergo surgical ligation (n = 7) or coil embolization (n = 8). We evaluated infarct size, scar fibrosis, inflammation, myocardial vascularization, and cardiac function by magnetic resonance imaging (MRI).

Results

Thirty-five days after MI, there were no differences between the models in infarct size (P = 0.53), left ventricular (LV) ejection fraction (P = 0.19), LV end systolic volume (P = 0.22), LV end diastolic volume (P = 0.84), and cardiac output (P = 0.89). Histologically, cardiac scars did not differ and the collagen content, collagen type I (I), collagen type III (III), and the I/III ratio were similar in both groups. Inflammation was assessed using specific anti-CD3 and anti-CD25 antibodies. There was similar activation of inflammation throughout the heart after coil embolization (P = 0.78); while, there were more activated lymphocytes in the infarcted myocardium in the surgical occlusion model (P = 0.02). Less myocardial vascularization in the infarction areas compared with the border and remote zones only in coil embolization animals was observed (P = 0.004 and P = 0.014, respectively).

Conclusions

Our results support that surgical occlusion and coil embolization MI models generate similar infarct size, cardiac function impairment, and myocardial fibrosis; although, inflammation and myocardial vascularization levels were closer to those found in humans when coil embolization was performed.

The role of transforming growth factor β1 in the regulation of blood pressure

Although human association studies suggest a link between polymorphisms in the gene encoding transforming growth factor (TGF) β1 and differing blood pressure levels, a causative mechanism for this correlation remains elusive. Recently we have generated a series of mice with graded expression of TGFβ1, ranging from approximately 10% to 300% compared to normal. We have found that blood pressure and plasma volume are negatively regulated by TGFβ1. Of note, the 10% hypomorph exhibits primary aldosteronism and markedly impaired urinary excretion of water and electrolytes. We here review previous literature highlighting the importance of TGFβ signaling as a natriuretic system, which we postulate is a causative mechanism explaining how polymorphisms in TGFβ1 could influence blood pressure levels.