Mechanical stretch-induced vascular hypertrophy occurs through modulation of leptin synthesis-mediated ROS formation and GATA-4 nuclear translocation

Alamandine attenuates oxidative stress in the right carotid following transverse aortic constriction in mice

OBJECTIVE

Pressure overload can result in significant changes to the structure of blood vessels, a process known as vascular remodeling. High levels of tension can cause vascular inflammation, fibrosis, and structural alterations to the vascular wall. Prior research from our team has demonstrated that the oral administration of alamandine can promote vasculoprotective effects in mice aorta that have undergone transverse aortic constriction (TAC). Furthermore, changes in local hemodynamics can affect the right and left carotid arteries differently after TAC. Thus, in this study, we aimed to assess the effects of alamandine treatment on right carotid remodeling and the expression of oxidative stress-related substances induced by TAC.

METHODS AND RESULTS

Male C57BL/6 mice were categorized into three groups: Sham, TAC, and TAC treated with alamandine (TAC+ALA). Alamandine treatment was administered orally by gavage (30 µg/kg/day), starting three days before the surgery, and continuing for a period of fourteen days. Morphometric analysis of hematoxylin and eosin-stained sections revealed that TAC induced hypertrophic and positive remodeling in the right carotid artery. Picrosirius Red staining also demonstrated an increase in total collagen deposition in the right carotid artery due to TAC-induced vascular changes. Alamandine treatment effectively prevented the increase in reactive oxygen species production and depletion of nitric oxide levels, which were induced by TAC. Finally, alamandine treatment was also shown to prevent the increased expression of nuclear factor erythroid 2-related factor 2 and 3-nitrotyrosine that were induced by TAC.

CONCLUSION

Our results suggest that alamandine can effectively attenuate pathophysiological stress in the right carotid artery of animals subjected to TAC.

Novel cardiovascular protective effects of RhoA signaling and its therapeutic implications

Ras homolog gene family member A (RhoA) belongs to the Rho GTPase superfamily, which was first studied in cancers as one of the essential regulators controlling cellular function. RhoA has long attracted attention as a key molecule involved in cell signaling and gene transcription, through which it affects cellular processes. A series of studies have demonstrated that RhoA plays crucial roles under both physiological states and pathological conditions in cardiovascular diseases. RhoA has been identified as an important regulator in cardiac remodeling by regulating actin stress fiber dynamics and cytoskeleton formation. However, its underlying mechanisms remain poorly understood, preventing definitive conclusions being drawn about its protective role in the cardiovascular system. In this review, we outline the characteristics of RhoA and its related signaling molecules, and present an overview of RhoA classical function and the corresponding cellular responses of RhoA under physiological and pathological conditions. Overall, we provide an update on the novel signaling under RhoA in the cardiovascular system and its potential clinical and therapeutic targets in cardiovascular medicine.

Selenium in Bodily Homeostasis: Hypothalamus, Hormones, and Highways of Communication

The ability of the body to maintain homeostasis requires constant communication between the brain and peripheral tissues. Different organs produce signals, often in the form of hormones, which are detected by the hypothalamus. In response, the hypothalamus alters its regulation of bodily processes, which is achieved through its own pathways of hormonal communication. The generation and transmission of the molecules involved in these bi-directional axes can be affected by redox balance. The essential trace element selenium is known to influence numerous physiological processes, including energy homeostasis, through its various redox functions. Selenium must be obtained through the diet and is used to synthesize selenoproteins, a family of proteins with mainly antioxidant functions. Alterations in selenium status have been correlated with homeostatic disturbances in humans and studies with animal models of selenoprotein dysfunction indicate a strong influence on energy balance. The relationship between selenium and energy metabolism is complicated, however, as selenium has been shown to participate in multiple levels of homeostatic communication. This review discusses the role of selenium in the various pathways of communication between the body and the brain that are essential for maintaining homeostasis.

Involvement of caveolae in hyperglycemia-induced changes in adiponectin and leptin expressions in vascular smooth muscle cells

Hyperglycemia exerts various harmful effects on the vasculature. Studies have shown an association between the levels of the adipokines leptin and adiponectin (APN) and vascular complications in diabetes mellitus. The aim of our study was to investigate the molecular mechanisms mediated by APN and leptin that are involved in hyperglycemia-induced vascular remodeling, especially at the level of oxidative stress and actin cytoskeleton dynamics. Rat aorta organ culture was used to investigate the effect of hyperglycemia on APN and leptin protein expression in vascular smooth muscle cells (VSMCs) using Western blot analysis and immunohistochemistry. Hyperglycemia lead to a significant increase in APN synthesis in VSMCs, mainly through caveolae, but this increase failed to provide vascular protection because of the decreased expression of APN receptors, especially AdipoR2, which was assessed by qPCR. In addition, hyperglycemia significantly upregulated leptin expression in VSMCs through caveolae and the RhoA/ROCK pathway. These variations lead to a marked increase in reactive oxygen species (ROS) production, detected by dihydroethidium (DHE) staining, and in NADPH oxidase type 4 (Nox4) expression. Moreover, Nox4 mediated the synthesis of APN in hyperglycemia in VSMCs. Finally, hyperglycemia activated the RhoA/ROCK pathway and subsequently induced the polymerization of globular actin (G-actin) into filamentous actin (F-actin), decreasing the G/F-actin ratio. Taken together, these data show that hyperglycemia increases oxidative stress and changes actin cytoskeleton dynamics in the aorta via caveolae, favoring vascular remodeling.

Between Inflammation and Autophagy: The Role of Leptin-Adiponectin Axis in Cardiac Remodeling

Cardiac remodeling is the process by which the heart adapts to stressful stimuli, such as hypertension and ischemia/reperfusion; it ultimately leads to heart failure upon long-term exposure. Autophagy, a cellular catabolic process that was originally considered as a mechanism of cell death in response to detrimental stimuli, is thought to be one of the main mechanisms that controls cardiac remodeling and induces heart failure. Dysregulation of the adipokines leptin and adiponectin, which plays essential roles in lipid and glucose metabolism, and in the pathophysiology of the neuroendocrine and cardiovascular systems, has been shown to affect the autophagic response in the heart and to contribute to accelerate cardiac remodeling. The obesity-associated protein leptin is a pro-inflammatory, tumor-promoting adipocytokine whose elevated levels in obesity are associated with acute cardiovascular events, and obesity-related hypertension. Adiponectin exerts anti-inflammatory and anti-tumor effects, and its reduced levels in obesity correlate with the pathogenesis of obesity-associated cardiovascular diseases. Leptin- and adiponectin-induced changes in autophagic flux have been linked to cardiac remodeling and heart failure. In this review, we describe the different molecular mechanisms of hyperleptinemia- and hypoadiponectinemia-mediated pathogenesis of cardiac remodeling and the involvement of autophagy in this process. A better understanding of the roles of leptin, adiponectin, and autophagy in cardiac functions and remodeling, and the exact signal transduction pathways by which they contribute to cardiac diseases may well lead to discovery of new therapeutic agents for the treatment of cardiovascular remodeling.

ROCK Inhibition as Potential Target for Treatment of Pulmonary Hypertension

Pulmonary hypertension (PH) is a cardiovascular disease caused by extensive vascular remodeling in the lungs, which ultimately leads to death in consequence of right ventricle (RV) failure. While current drugs for PH therapy address the sustained vasoconstriction, no agent effectively targets vascular cell proliferation and tissue inflammation. Rho-associated protein kinases (ROCKs) emerged in the last few decades as promising targets for PH therapy, since ROCK inhibitors demonstrated significant anti-remodeling and anti-inflammatory effects. In this review, current aspects of ROCK inhibition therapy are discussed in relation to the treatment of PH and RV dysfunction, from cell biology to preclinical and clinical studies.

Mechanical stretching of the pulmonary vein mediates pulmonary hypertension due to left heart disease by regulating SAC/MAPK pathway and the expression of IL-6 and TNF-α

Background

This study aimed to explore whether the mechanical stretching-induced expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in pulmonary veins occurred through the stretch-activated channel (SAC)/ mitogen-activated protein kinases (MAPKs) pathway.

Methods

Sixty male Sprague-Dawley rats were divided into three sham groups and seven model groups. A metal clip was placed on the ascending aorta in the model group to establish PH-LHD rat model. The sham group received a similar operation without ascending aorta clamped. On day 25, pulmonary vein was given mechanical stretching with 0 g, 2.0 g tension in two model groups and two sham groups. Another four model groups were given 2.0 g tension after MAPKs pathway inhibitors soaked. The last sham group and model group rats’ pulmonary veins, pulmonary artery and lung tissues were obtained on day 35. Pulmonary vein, pulmonary artery and lung tissue were evaluated by echocardiography, HE staining, immunohistochemistry and western blotting respectively.

Results

On day 25, left heart weight, right ventricular pressure (35.339 cmH₂O) and left atrial pressure (13.657 cmH₂O) were increased in model group than those in sham group. Echocardiography showed left heart failure in the PH-LHD group (Interventrieular septum dimension 1.716 mm, left ventricular internal end diastolic dimension 4.888 mm, left ventricular posterior wall thickness in diastole 1.749 mm, ejection fraction 76.917%). But there was no difference in lung tissue between the sham group and PH-LHD group as showed by HE staining. Our results showed that the expression of IL-6 and TNF-α was highly expressed in PH-LHD rats’ serum and pulmonary vein, which were further increased after 2.0 g tension was given and were decreased after SAC/MAPKs inhibitors treatment. Meanwhile, on day 25, immunohistochemistry analysis showed the expression of IL-6 and TNF-α was higher in the PH-LHD rats’ pulmonary vein than that in pulmonary artery and lung tissue, and these expressions in pulmonary vein of PH-LHD group were also higher than that in sham group. However, on day 35, IL-6 and TNF-α were all increased in the pulmonary veins, arteries and lung tissues. Besides, our results uncovered that SAC/MAPKs pathway were upregulating in PH-LHD rats’ pulmonary vein.

Conclusion

In conclusion, pulmonary vein mechanical stretching exacerbated PH-LHD possibly through the SAC/MAPKs pathway and upregulating expression of IL-6 and TNF-α.

Advances in Cardiovascular Biomarker Discovery

Cardiovascular diseases are the leading causes of mortality worldwide. Among them, hypertension and its pathological complications pose a major risk for the development of other cardiovascular diseases, including heart failure and stroke. Identifying novel and early stage biomarkers of hypertension and other cardiovascular diseases is of paramount importance in predicting and preventing the major morbidity and mortality associated with these diseases. Biomarkers of such diseases or predisposition to their development are identified by changes in a specific indicator’s expression between healthy individuals and patients. These include changes in protein and microRNA (miRNA) levels. Protein profiling using mass spectrometry and miRNA screening utilizing microarray and sequencing have facilitated the discovery of proteins and miRNA as biomarker candidates. In this review, we summarized some of the different, promising early stage protein and miRNA biomarker candidates as well as the currently used biomarkers for hypertension and other cardiovascular diseases. Although a number of promising markers have been identified, it is unlikely that a single biomarker will unambiguously aid in the classification of these diseases. A multi-marker panel-strategy appears useful and promising for classifying and refining risk stratification among patients with cardiovascular disease.

Mechanical stretching of pulmonary vein stimulates matrix metalloproteinase-9 and transforming growth factor-β1 through stretch-activated channel/MAPK pathways in pulmonary hypertension due to left heart disease model rats

Pulmonary hypertension due to left heart disease (PH-LHD) is a momentous pulmonary hypertension disease, and left heart disease is the most familiar cause. Mechanical stretching may be a crucial cause of vascular remodeling. While, the underlining mechanism of mechanical stretching-induced in remodeling of pulmonary vein in the early stage of PH-LHD has not been completely elucidated. In our study, the PH-LHD model rats were successfully constructed. After 25 days, doppler echocardiography and hemodynamic examination were performed. In addition, after treatment, the levels of matrix metalloproteinase-9 (MMP-9) and transforming growth factor-β1 (TGF-β1) were determined by ELISA, immunohistochemistry and western blot assays in the pulmonary veins. Moreover, the pathological change of pulmonary tissues was evaluated by H&E staining. Our results uncovered that left ventricular insufficiency and interventricular septal shift could be observed in PH-LHD model rats, and the right ventricular systolic pressure (RVSP) and mean left atrial pressure (mLAP) were also elevated in PH-LHD model rats. Meanwhile, we found that MMP-9 and TGF-β1 could be highly expressed in PH-LHD model rats. Besides, we revealed that stretch-activated channel (SAC)/mitogen-activated protein kinases (MAPKs) signaling pathway could be involved in the upregulations of MMP-9 and TGF-β1 mediated by mechanical stretching in pulmonary vein. Therefore, current research revealed that mechanical stretching induced the increasing expressions of MMP-9 and TGF-β1 in pulmonary vein, which could be mediated by activation of SAC/MAPKs signaling pathway in the early stage of PH-LHD.

Molecular Mechanisms of Adiponectin-Induced Attenuation of Mechanical Stretch-Mediated Vascular Remodeling

Hypertension induces vascular hypertrophy, which changes blood vessels structurally and functionally, leading to reduced tissue perfusion and further hypertension. It is also associated with dysregulated levels of the circulating adipokines leptin and adiponectin (APN). Leptin is an obesity-associated hormone that promotes vascular smooth muscle cell (VSMC) hypertrophy. APN is a cardioprotective hormone that has been shown to attenuate hypertrophic cardiomyopathy. In this study, we investigated the molecular mechanisms of hypertension-induced VSMC remodeling and the involvement of leptin and APN in this process. To mimic hypertension, the rat portal vein (RPV) was mechanically stretched, and the protective effects of APN on mechanical stretch-induced vascular remodeling and the molecular mechanisms involved were examined by using 10 μg/ml APN. Mechanically stretching the RPV significantly decreased APN protein expression after 24 hours and APN mRNA expression in a time-dependent manner in VSMCs. The mRNA expression of the APN receptors AdipoR1, AdipoR2, and T-cadherin significantly increased after 15 hours of stretch. The ratio of APN/leptin expression in VSMCs significantly decreased after 24 hours of mechanical stretch. Stretching the RPV for 3 days increased the weight and [³H]-leucine incorporation significantly, whereas APN significantly reduced hypertrophy in mechanically stretched vessels. Stretching the RPV for 10 minutes significantly decreased phosphorylation of LKB1, AMPK, and eNOS, while APN significantly increased p-LKB1, p-AMPK, and p-eNOS in stretched vessels. Mechanical stretch significantly increased p-ERK1/2 after 10 minutes, whereas APN significantly reduced stretch-induced ERK1/2 phosphorylation. Stretching the RPV also significantly increased ROS generation after 1 hour, whereas APN significantly decreased mechanical stretch-induced ROS production. Exogenous leptin (3.1 nM) markedly increased GATA-4 nuclear translocation in VSMCs, whereas APN significantly attenuated leptin-induced GATA-4 nuclear translocation. Our results decipher molecular mechanisms of APN-induced attenuation of mechanical stretch-mediated vascular hypertrophy, with the promising potential of ultimately translating this protective hormone into the clinic.

Localized Antileptin Therapy Prevents Aortic Root Dilatation and Preserves Left Ventricular Systolic Function in a Murine Model of Marfan Syndrome

Background Marfan syndrome (MFS) is a genetically transmitted connective tissue disorder characterized by aortic root dilatation, dissection, and rupture. Molecularly, MFS pathological features have been shown to be driven by increased angiotensin II in the aortic wall. Using an angiotensin II-driven aneurysm mouse model, we have recently demonstrated that local inhibition of leptin activity restricts aneurysm formation in the ascending and abdominal aorta. As we observed de novo leptin synthesis in the ascending aortic aneurysm wall of patients with MFS, we hypothesized that local counteracting of leptin activity in MFS may also prevent aortic cardiovascular complications in this context. Methods and Results Fbn1^C1039G/+ mice underwent periaortic application of low-dose leptin antagonist at the aortic root. Treatment abolished medial degeneration and prevented increase in aortic root diameter (P<0.001). High levels of leptin, transforming growth factor β1, Phosphorylated Small mothers against decapentaplegic 2, and angiotensin-converting enzyme 1 observed in saline-treated MFS mice were downregulated in leptin antagonist-treated animals (P<0.01, P<0.05, P<0.001, and P<0.001, respectively). Leptin and angiotensin-converting enzyme 1 expression levels in left ventricular cardiomyocytes were also decreased (P<0.001) and coincided with prevention of left ventricular hypertrophy and aortic and mitral valve leaflet thickening (P<0.01 and P<0.05, respectively) and systolic function preservation. Conclusions Local, periaortic application of leptin antagonist prevented aortic root dilatation and left ventricular valve remodeling, preserving left ventricular systolic function in an MFS mouse model. Our results suggest that local inhibition of leptin may constitute a novel, stand-alone approach to prevent MFS aortic root aneurysms and potentially other similar angiotensin II-driven aortic pathological features.

Protective Role of Nuclear Factor Erythroid-2-Related Factor 2 against Mechanical Trauma-Induced Apoptosis in a Vaginal Distension-Induced Stress Urinary Incontinence Mouse Model

Apoptosis and oxidative damage are involved in the pathogenesis and progression of stress urinary incontinence (SUI). Our previous results indicate that cell apoptosis and oxidative damage increase in a mouse model of mechanical injury-induced SUI and in fibroblasts treated with excessive mechanical strain. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a well-characterized global antioxidant gene inducer that can reduce oxidative damage and apoptosis. Therefore, we predicted that Nrf2 may have a protective role in mechanical trauma-induced SUI. To test this hypothesis, a mouse model of vaginal distension- (VD-) induced SUI was established. Leak point pressure (LPP); levels of apoptosis, apoptosis-related proteins, and peroxidation products; and the activities of antioxidative proteins in the anterior vaginal wall were measured in wild-type (Nfe2l2^+/+) C57BL/6 mice and Nrf2-knockout mice (Nfe2l2^−/−). The results showed that Nrf2 knockout aggravated VD-induced reduction in LPP, increase in cell apoptosis and peroxidation product levels, decrease in antioxidative protein activities, and alterations in apoptosis-related protein levels in the vaginal walls of mice. To further confirm the role of Nrf2 in mechanical trauma-induced apoptosis and SUI, VD was performed on mice overexpressing Nrf2 via in vivo transfection of LV-Nfe2l2. The results showed that Nrf2 overexpression significantly alleviated VD-induced abnormalities in the anterior vaginal wall. Taken together, our data suggested that Nrf2 is a potential protective factor in mechanical trauma-induced apoptosis in a mouse model of SUI. Antioxidative therapy may be a promising treatment for mechanical trauma-related SUI.

Mechanisms involved in inflammatory pulmonary fibrosis induced by lunar dust simulant in rats

Lunar dust is one of the biggest risk factors in the future manned exploration mission. Much is not known about the pulmonary toxicity of lunar dust. The aim of this study was to evaluate the lung inflammation and oxidative stress induced by subacute exposure to lunar dust stimulant (LDS) in rats. Wistar rats were intratracheally administered LDS, twice a week for 3 weeks. Inflammatory cell counting and cytokine assays using bronchoalveolar lavage fluid (BALF) were performed. Lung tissues were processed for histopathological examination and immunohistochemical staining. Biomarkers of oxidative stress and genes and proteins related to inflammation and fibrosis in lung tissue were also determined. The neutrophil count in the BALF of LDS-exposed groups was higher than that in controls (P < .05). LDS caused a significant increase in some of biochemical indicators and proinflammatory factors levels in BALF compared with control group. The normal balance between oxidation and antioxidation was broken by LDS. Pathological characteristics of lung tissue and immunohistochemical results for α-smooth muscle actin (α-SMA) indicated that inflammatory response was an extremely important passage to pulmonary fibrosis. Real-time PCR analysis showed elevated levels of nitric oxide synthase (NOS) and nicotinamide adenine dinucleotide phosphate oxidase (NOX) mRNA in the lungs (P < .05). Western blotting results were consistent with immunohistochemistry and qPCR results. These results indicate that inhalation of lunar dust may cause inflammatory pulmonary fibrosis. NOX4 may be a key potential therapeutic target for inflammatory injury and fibrosis in the lung.

Leptin attenuates cerebral ischemic injury in rats by modulating the mitochondrial electron transport chain via the mitochondrial STAT3 pathway

BACKGROUND

According to recent studies, leptin may exert a neuroprotective function by affecting the phosphorylation of signal transducer and activator of transcription 3 (STAT3). During stress, STAT3 regulates mitochondrial oxidative stress and reduces apoptosis.

OBJECTIVE

In the present study, we hypothesized that leptin increases STAT3 phosphorylation in the mitochondria and protects against mitochondrial oxidative stress in rats subjected to permanent middle cerebral artery occlusion (MCAO).

RESULTS

Leptin reduced reactive oxygen species (ROS) production, and we confirmed that the mechanism underlying this change involved the enzymatic activities of mitochondrial respiratory chain complexes I and II. In addition, leptin increased the level of STAT3 Ser727 phosphorylation in the mitochondria.

CONCLUSIONS

Based on these results, leptin may regulate mitochondrial respiratory chain enzymatic activities via mitochondria-targeted STAT3 to reduce ROS production and protect brain tissues from mitochondrial oxidative stress during cerebral ischemia.

Effects of RSC96 Schwann Cell-Derived Exosomes on Proliferation, Senescence, and Apoptosis of Dorsal Root Ganglion Cells In Vitro

Background

Stress urinary incontinence is a common condition in women and can be associated with peripheral nerve injury. Exosomes. derived from Schwann cells, can enhance the regeneration of axons of the peripheral nervous system. This study aimed to investigate the effects of RSC96 Schwann cell-derived exosomes in a novel in vitro model of dorsal root ganglion (DRG) cell injury induced by cyclic mechanical strain (CMS).

Material/Methods

RSC96 Schwann cells and DRG cells were cultured in vitro. CMS in DRG cells involved mechanical stretch trauma with 5333 μ strain. ExoQuick-TC polymer was used to precipitate exosomes from RSC96 Schwann cell culture medium and identified by nanoparticle tracking analysis, electron microscopy, and Western blot for detection of CD9 and tumor susceptibility gene 101 (Tsg101) protein. Cultured DRG cells were treated with RSC96 Schwann cell-derived exosomes, followed by measurement of cell viability, proliferation, senescence, and apoptosis using the cell counting kit-8 (CCK-8) assay, senescence-associated beta-galactosidase (SA-β-gal) staining, and Hoechst 33258 (blue) fluorescence nucleic acid staining using flow cytometry.

Results

Mechanical stretch with 5333 μ strain for 8 hours at 1 Hz decreased the activity of cultured DRG cells. RSC96 Schwann cell-derived exosomes promoted cell proliferation and significantly inhibited apoptosis and senescence of DRG cells following injury induced by CMS.

Conclusions

An in vitro model of DRG cell injury induced by CMS, showed that RSC96 Schwann cell-derived exosomes had a protective effect. The effects of Schwann cell-derived exosomes on peripheral nerve injury, including in stress urinary incontinence, require future in vivo studies.

Mechanical stretch aggravates aortic dissection by regulating MAPK pathway and the expression of MMP-9 and inflammation factors

This study aimed to explore whether mechanical stretch aggravated aortic dissection through regulating MAPK pathway, MMP-9, and inflammation factors. We first established aortic dissection model rats. Mechanical stretch (3 g) was exerted on vascular ring of aortic dissection which was also treated by inhibitors of MAPK pathway (SB203580, SP600125, and U0126). HE and Masson staining showed that aortic dissection severity with 3 g tension was worse than that without tension (0 g); after the treatments of diverse inhibitors, the fracture and breakage of the elastic fibers decreased. The expression of MMP-9, TNF-α, IL-1β) p38/p-p38, JNK1/p-JNK1, and ERK1/2/p-ERK1/2 were determined by immunohistochemical analysis, RT-PCR, and western blot. No matter whether tension was exerted or inhibitors were added, there was no change in the expression of p38, JNK1, and ERK1/2. However, compared to the 0 g group, the expression of MMP-9, TNF-α, IL-1β, p-p38, p-JNK1, and p-ERK1/2 was significantly upregulated in the 3 g group (P < 0.05). In both 0 g and 3 g groups, the expression of MMP-9, TNF-α, IL-1β, p-p38, p-JNK1, and p-ERK1/2 was remarkably downregulated after inhibitors treatment (P < 0.05). In conclusion, mechanical stretch aggravated aortic dissection by regulating the MAPK pathway and the consequent expression of MMP-9 and inflammation factors.

Role of Mitochondrial Reactive Oxygen Species in the Activation of Cellular Signals, Molecules, and Function

Mitochondria are a major source of intracellular energy and reactive oxygen species in cells, but are also increasingly being recognized as a controller of cell death. Here, we review evidence of signal transduction control by mitochondrial superoxide generation via the nuclear factor-κB (NF-κB) and GATA signaling pathways. We have also reviewed the effects of ROS on the activation of MMP and HIF. There is significant evidence to support the hypothesis that mitochondrial superoxide can initiate signaling pathways following transport into the cytosol. In this study, we provide evidence of TATA signal transductions by mitochondrial superoxide. Oxidative phosphorylation via the electron transfer chain, glycolysis, and generation of superoxide from mitochondria could be important factors in regulating signal transduction, cellular homeostasis, and cell death.

Mechanism of Mechanical Trauma-Induced Extracellular Matrix Remodeling of Fibroblasts in Association with Nrf2/ARE Signaling Suppression Mediating TGF-β1/Smad3 Signaling Inhibition

Stress urinary incontinence (SUI) is a common hygienic problem affecting the quality of women's life worldwide. In this research, we revealed the involvement and regulation of extracellular matrix (ECM) remodeling, oxidative damage, and TGF-β1 signaling in the pathological mechanisms of mechanical trauma-induced SUI. We found that excessive mechanical strain significantly increased apoptosis rate, decreased cell viability and ECM production, and broke the balance of MMPs/TIMPs compared with the nonstrain control (NC) group. The expression levels of TGFβ1, p-Smad3, Nrf2, GPx1, and CAT were downregulated, the production of ROS, 8-OHdG, 4-HNE, and MDA was increased, and the nuclear translocation of Smad2/3 was suppressed after 5333 μstrain's treatment. Both mTGF-β1 pretreatment and Nrf2 overexpression could reverse mechanical injury-induced TGFβ1/Smad3 signaling inhibition and ECM remodeling, whereas mTGF-β1 had no effect on Nrf2 expression. Nrf2 overexpression significantly alleviated mechanical injury-induced ROS accumulation and oxidative damage; in contrast, Nrf2 silencing exhibited opposite effects. Besides, vaginal distention- (VD-) induced in vivo SUI model was used to confirm the in vitro results; Nrf2 knockout aggravates mechanical trauma-induced LPP reduction, ECM remodeling, oxidative damage, and TGF-β1/Smad3 suppression in mice. Therefore, we deduce that mechanical injury-induced ECM remodeling might be associated with Nrf2/ARE signaling suppression mediating TGF-β1/Smad3 signaling inhibition. This might reflect a new molecular target for SUI researches.

Mechanical Strain Induced Expression of Matrix Metalloproteinase-9 via Stretch-Activated Channels in Rat Abdominal Aortic Dissection

Background

The aim of the study was to investigate the expression of matrix metalloproteinase-9 (MMP-9) in rat abdominal aortic dissection (AD) induced by mechanical strain, so as to offer a better understanding of the possible mechanisms of AD.

Material/Methods

Experimental AD in rats was achieved by the injection of porcine pancreatic elastase. At days 0, 1, 3, 5, 7, 14, 21, and 30 after the establishment of AD model, serum MMP-9 levels were measured by enzyme-linked immunosorbent assay (ELISA). Four groups of vascular rings were stretched in vitro with a mechanical strength of 0 g, 1 g, 3 g, or 5 g for 30 min. Another four groups were pretreated with GdCl₃, streptomycin, SN50, and SN50M, followed by stretching with 3 g for 30 min. The messenger RNA and the protein of MMP-9 were analyzed by real-time RT-PCR and Western blotting, and NF-κB p65 was detected by ELISA.

Results

After the establishment of rat abdominal AD model, the serum MMP-9 levels of AD groups increased significantly. The results showed increased expression of MMP-9 in rat AD vessels stretched with mechanical strength of 1 g, 3 g, and 5 g, but this effect was mostly blocked by Gd Cl₃ and streptomycin. The NF-κB activity in aortic rings was activated by stretching with a mechanical strength of 3 g and was blocked by SN50, but not by SN50M.

Conclusions

The expression of MMP-9 in serum was increased significantly after rat abdominal AD formation. Mechanical strain induced MMP-9 expression in AD vessels, which was mediated through the activation of the stretch-activated channel-induced NF-κB pathway.

Genome-wide DNA methylation pattern in visceral adipose tissue differentiates insulin-resistant from insulin-sensitive obese subjects

Elucidating the potential mechanisms involved in the detrimental effect of excess body weight on insulin action is an important priority in counteracting obesity-associated diseases. The present study aimed to disentangle the epigenetic basis of insulin resistance by performing a genome-wide epigenetic analysis in visceral adipose tissue (VAT) from morbidly obese patients depending on the insulin sensitivity evaluated by the clamp technique. The global human methylome screening performed in VAT from 7 insulin-resistant (IR) and 5 insulin-sensitive (IS) morbidly obese patients (discovery cohort) analyzed using the Infinium HumanMethylation450 BeadChip array identified 982 CpG sites able to perfectly separate the IR and IS samples. The identified sites represented 538 unique genes, 10% of which were diabetes-associated genes. The current work identified novel IR-related genes epigenetically regulated in VAT, such as COL9A1, COL11A2, CD44, MUC4, ADAM2, IGF2BP1, GATA4, TET1, ZNF714, ADCY9, TBX5, and HDACM. The gene with the largest methylation fold-change and mapped by 5 differentially methylated CpG sites located in island/shore and promoter region was ZNF714. This gene presented lower methylation levels in IR than in IS patients in association with increased transcription levels, as further reflected in a validation cohort (n = 24; 11 IR and 13 IS). This study reveals, for the first time, a potential epigenetic regulation involved in the dysregulation of VAT that could predispose patients to insulin resistance and future type 2 diabetes in morbid obesity, providing a potential therapeutic target and biomarkers for counteracting this process.

Calcineurin/NFAT Activation-Dependence of Leptin Synthesis and Vascular Growth in Response to Mechanical Stretch

Background and Aims: Hypertension and obesity are important risk factors of cardiovascular disease. They are both associated with high leptin levels and have been shown to promote vascular hypertrophy, through the RhoA/ROCK and ERK1/2 phosphorylation. Calcineurin/NFAT activation also induces vascular hypertrophy by upregulating various genes. This study aimed to decipher whether a crosstalk exists between the RhoA/ROCK pathway, Ca²⁺/calcineurin/NFAT pathway, and ERK1/2 phosphorylation in the process of mechanical stretch-induced vascular smooth muscle cell (VSMC) hypertrophy and leptin synthesis.

Methods and Results: Rat portal vein (RPV) organ culture was used to investigate the effect of mechanical stretch and exogenous leptin (3.1 nM) on VSMC hypertrophy and leptin synthesis. Results showed that stretching the RPV significantly upregulated leptin secretion, mRNA, and protein expression, which were inhibited by the calcium channel blocker nifedipine (10 μM), the selective calcineurin inhibitor FK506 (1 nM), and the ERK1/2 inhibitor PD98059 (1 μM). The transcription inhibitor actinomycin D (0.1 μM) and the translation inhibitor cycloheximide (1 mM) significantly decreased stretch-induced leptin protein expression. Mechanical stretch or leptin caused an increase in wet weight changes and protein synthesis, considered as hypertrophic markers, while they were inhibited by FK506 (0.1 nM; 1 nM). In addition, stretch or exogenous leptin significantly increased calcineurin activity and MCIP1 expression whereas leptin induced NFAT nuclear translocation in VSMCs. Moreover, in response to stretch or exogenous leptin, the Rho inhibitor C3 exoenzyme (30 ng/mL), the ROCK inhibitor Y-27632 (10 μM), and the actin depolymerization agents Latrunculin B (50 nM) and cytochalasin D (1 μM) reduced calcineurin activation and NFAT nuclear translocation. ERK1/2 phosphorylation was inhibited by FK506 and C3.

Conclusions: Mechanical stretch-induced VSMC hypertrophy and leptin synthesis and secretion are mediated by Ca²⁺/calcineurin/NFAT activation. RhoA/ROCK and ERK1/2 activation are critical for mechanical stretch-induced calcineurin activation.

Adiponectin Attenuates Angiotensin II-Induced Vascular Smooth Muscle Cell Remodeling through Nitric Oxide and the RhoA/ROCK Pathway

INTRODUCTION

Adiponectin (APN), an adipocytokine, exerts protective effects on cardiac remodeling, while angiotensin II (Ang II) induces hypertension and vascular remodeling. The potential protective role of APN on the vasculature during hypertension has not been fully elucidated yet. Here, we evaluate the molecular mechanisms of the protective role of APN in the physiological response of the vascular wall to Ang II.

METHODS AND RESULTS

Rat aortic tissues were used to investigate the effect of APN on Ang II-induced vascular remodeling and hypertrophy. We investigated whether nitric oxide (NO), the RhoA/ROCK pathway, actin cytoskeleton remodeling, and reactive oxygen species (ROS) mediate the anti-hypertrophic effect of APN. Ang II-induced protein synthesis was attenuated by pre-treatment with APN, NO donor S-nitroso-N-acetylpenicillamine (SNAP), or cGMP. The hypertrophic response to Ang II was associated with a significant increase in RhoA activation and vascular force production, which were prevented by APN and SNAP. NO was also associated with inhibition of Ang II-induced phosphorylation of cofilin. In addition, immunohistochemistry revealed that 24 h Ang II treatment increased the F- to G-actin ratio, an effect that was inhibited by SNAP. Ang II-induced ROS formation and upregulation of p22(phox) mRNA expression were inhibited by APN and NO. Both compounds failed to inhibit Nox1 and p47(phox) expression.

CONCLUSION

Our results suggest that the anti-hypertrophic effects of APN are due, in part, to NO-dependent inhibition of the RhoA/ROCK pathway and ROS formation.