p38 MAPK contributes to angiotensin II-induced COX-2 expression in aortic fibroblasts from normotensive and hypertensive rats. J Hypertens. 2009;27:142-154. [PMID: 19145780 DOI: 10.1097/HJH.0b013e328317a730]

Acute COVID-19 and LongCOVID syndrome - molecular implications for therapeutic strategies - review

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been recognized not only for its acute effects but also for its ability to cause LongCOVID Syndrome (LCS), a condition characterized by persistent symptoms affecting multiple organ systems. This review examines the molecular and immunological mechanisms underlying LCS, with a particular focus on autophagy inhibition, chronic inflammation, oxidative, nitrosative and calcium stress, viral persistence and autoimmunology. Potential pathophysiological mechanisms involved in LCS include (1) autoimmune activation, (2) latent viral persistence, where SARS-CoV-2 continues to influence host metabolism, (3) reactivation of latent pathogens such as Epstein-Barr virus (EBV) or cytomegalovirus (CMV), exacerbating immune and metabolic dysregulation, and (4) possible persistent metabolic and inflammatory dysregulation, where the body fails to restore post-infection homeostasis. The manipulation of cellular pathways by SARS-CoV-2 proteins is a critical aspect of the virus' ability to evade immune clearance and establish long-term dysfunction. Viral proteins such as NSP13, ORF3a and ORF8 have been shown to disrupt autophagy, thereby impairing viral clearance and promoting immune evasion. In addition, mitochondrial dysfunction, dysregulated calcium signaling, oxidative stress, chronic HIF-1α activation and Nrf2 inhibition create a self-sustaining inflammatory feedback loop that contributes to tissue damage and persistent symptoms. Therefore understanding the molecular basis of LCS is critical for the development of effective therapeutic strategies. Targeting autophagy and Nrf2 activation, glycolysis inhibition, and restoration calcium homeostasis may provide novel strategies to mitigate the long-term consequences of SARS-CoV-2 infection. Future research should focus on personalized therapeutic interventions based on the dominant molecular perturbations in individual patients.

Understanding chronic inflammation: couplings between cytokines, ROS, NO, Cai 2+, HIF-1α, Nrf2 and autophagy

Chronic inflammation is an important component of many diseases, including autoimmune diseases, intracellular infections, dysbiosis and degenerative diseases. An important element of this state is the mainly positive feedback between inflammatory cytokines, reactive oxygen species (ROS), nitric oxide (NO), increased intracellular calcium, hypoxia-inducible factor 1-alpha (HIF-1α) stabilisation and mitochondrial oxidative stress, which, under normal conditions, enhance the response against pathogens. Autophagy and the nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated antioxidant response are mainly negatively coupled with the above-mentioned elements to maintain the defence response at a level appropriate to the severity of the infection. The current review is the first attempt to build a multidimensional model of cellular self-regulation of chronic inflammation. It describes the feedbacks involved in the inflammatory response and explains the possible pathways by which inflammation becomes chronic. The multiplicity of positive feedbacks suggests that symptomatic treatment of chronic inflammation should focus on inhibiting multiple positive feedbacks to effectively suppress all dysregulated elements including inflammation, oxidative stress, calcium stress, mito-stress and other metabolic disturbances.

Carbon dioxide and MAPK signalling: towards therapy for inflammation

Inflammation, although necessary to fight infections, becomes a threat when it exceeds the capability of the immune system to control it. In addition, inflammation is a cause and/or symptom of many different disorders, including metabolic, neurodegenerative, autoimmune and cardiovascular diseases. Comorbidities and advanced age are typical predictors of more severe cases of seasonal viral infection, with COVID-19 a clear example. The primary importance of mitogen-activated protein kinases (MAPKs) in the course of COVID-19 is evident in the mechanisms by which cells are infected with SARS-CoV-2; the cytokine storm that profoundly worsens a patient's condition; the pathogenesis of diseases, such as diabetes, obesity, and hypertension, that contribute to a worsened prognosis; and post-COVID-19 complications, such as brain fog and thrombosis. An increasing number of reports have revealed that MAPKs are regulated by carbon dioxide (CO2); hence, we reviewed the literature to identify associations between CO2 and MAPKs and possible therapeutic benefits resulting from the elevation of CO2 levels. CO2 regulates key processes leading to and resulting from inflammation, and the therapeutic effects of CO2 (or bicarbonate, HCO3-) have been documented in all of the abovementioned comorbidities and complications of COVID-19 in which MAPKs play roles. The overlapping MAPK and CO2 signalling pathways in the contexts of allergy, apoptosis and cell survival, pulmonary oedema (alveolar fluid resorption), and mechanical ventilation-induced responses in lungs and related to mitochondria are also discussed. Video Abstract.

Cyclooxygenase-2 is a critical determinant of angiotensin II-induced vascular remodeling and stiffness in resistance arteries of ouabain-treated rats

OBJECTIVE

To investigate the role of angiotensin II/AT 1 receptor signaling and/or cyclooxygenase-2 (COX-2) activation on vascular remodeling and stiffening of the mesenteric resistance arteries (MRA) of ouabain-treated rats.

METHODS

Ouabain-treated (OUA, 30 μg kg/day for 5 weeks) and vehicle (VEH)-treated Wistar rats were co-treated with losartan (LOS, AT 1 R antagonist), nimesulide (NIM, COX-2 inhibitor) or hydralazine hydrochloride plus hydrochlorothiazide. MRA structure and mechanics were assessed with pressure myography and histology. Picrosirius red staining was used to determine the total collagen content. Western blotting was used to detect the expression of collagen I/III, MMP-2, Src, NFκB, Bax, Bcl-2 and COX-2. Reactive oxygen species (ROS) and plasma angiotensin II levels were measured by fluorescence and ELISA, respectively.

RESULTS

Blockade of AT 1 R or inhibition of COX-2 prevented ouabain-induced blood pressure elevation. Plasma angiotensin II level was higher in OUA than in VEH. LOS, but not hydralazine hydrochloride with hydrochlorothiazide, prevented inward hypotrophic remodeling, increased collagen deposition and stiffness, and oxidative stress in OUA MRA. LOS prevented the reduction in the total number of nuclei in the media layer and the Bcl-2 expression induced by OUA in MRA. The higher pSrc/Src ratio, NFκB/IκB ratio, and COX-2 expression in OUA MRA were also prevented by LOS. Likewise, COX-2 inhibition prevented vascular remodeling, mechanical changes, oxidative stress and inflammation in OUA MRA.

CONCLUSION

The results suggest that, regardless of hemodynamic adjustments, the angiotensin II/AT 1 R/pSrc/ROS/NFκB/COX-2 pathway is involved in the development of MRA inward hypotrophic remodeling and stiffness in ouabain-treated rats.

Contribution of RAS, ROS and COX-1-derived prostanoids to the contractile profile of perivascular adipose tissue in cafeteria diet-induced obesity

AIMS

Obesity can lead to the loss of the anticontractile properties of perivascular adipose tissue (PVAT). Given that cafeteria (CAF) diet reflects the variety of highly calorie and easily accessible foods in Western societies, contributing to obesity and metabolic disorders, we sought to investigate the impact of CAF diet on PVAT vasoactive profile and the involvement of renin-angiotensin system, oxidative stress, and cyclooxygenase pathway.

MAIN METHODS

Male Balb/c mice received standard or CAF diet for 4 weeks. Oral glucose tolerance and insulin sensitivity tests were performed, and fasting serum glucose, cholesterol and triglyceride parameters were determined. Vascular reactivity, fluorescence and immunofluorescence analyzes were carried out in intact thoracic aorta in the presence or absence of PVAT.

KEY FINDINGS

CAF diet was effective in inducing obesity and metabolic disorders, as demonstrated by increased body weight gain and adiposity index, hyperlipidemia, hyperglycemia, glucose intolerance and insulin insensitivity. Importantly, CAF diet led to a significant decrease in aortic contractility which was restored in the presence of PVAT, exhibiting therefore a contractile profile. The contractile effect of PVAT was associated with the activation of AT₁ receptor, reactive oxygen species, cyclooxygenase-1, thromboxane A₂ and prostaglandin E₂ receptors.

SIGNIFICANCE

These findings suggest that the contractile profile of PVAT involving the renin-angiotensin system activation, reactive oxygen species and cyclooxygenase-1 metabolites may be a protective compensatory adaptive response during early stage of CAF diet-induced obesity as an attempt to restore the impaired vascular contraction observed in the absence of PVAT, contributing to the maintenance of vascular tone.

Chronic Low-Level Lead Exposure Increases Mesenteric Vascular Reactivity: Role of Cyclooxygenase-2-Derived Prostanoids

Lead (Pb) exposure causes hazardous effects as hypertension and other cardiovascular diseases. We evaluated whether chronic Pb exposure alters the peripheral vascular resistance measuring the vascular reactivity of mesenteric resistance arteries in rats to identify the underlying mechanisms that are associated to the development of Pb-induced hypertension. Mesenteric resistance arteries from lead-treated and untreated Wistar rats (1st dose: 10 μg/100 g; subsequent doses: 0.125 μg/100 g, intramuscular, 30 days) were used. Contractile responses to phenylephrine increased, while acetylcholine and sodium nitroprusside-induced relaxation was not affected by lead treatment. Endothelium removal and inhibition of NO synthase by L-NAME similarly enhanced the response to phenylephrine in untreated and lead-treated rats. The antioxidants apocynin and superoxide dismutase (SOD) did not affect vasoconstriction in either group. The vascular expression of cyclooxygenase-2 (COX-2) protein increased after lead exposure. The respective non-specific or specific COX-2 inhibitors indomethacin and NS398 reduced more strongly the response to phenylephrine in treated rats. Antagonists of EP1 (SC19220), TP (SQ29548), IP (CAY10441) and angiotensin II type 1 (losartan) receptors reduced vasoconstriction only in treated rats. These conclusions present further evidence that lead, even in small concentration, produces cardiovascular hazards being an environmental contaminant that account for lead-induced hypertension.

Non-coding RNAs in aortic dissection: From biomarkers to therapeutic targets

Aortic dissection (AD) is the rupture of the aortic intima, causing the blood in the cavity to enter the middle of the arterial wall. Without urgent and proper treatment, the mortality rate increases to 50% within 48 hours. Most patients present with acute onset of symptoms, including sudden severe pain and complex and variable clinical manifestations, which can be easily misdiagnosed. Despite this, the molecular mechanisms underlying AD are still unknown. Recently, non‐coding RNAs have emerged as novel regulators of gene expression. Previous studies have proven that ncRNAs can regulate several cardiovascular diseases; therefore, their potential as clinical biomarkers and novel therapeutic targets for AD has aroused widespread interest. To date, several studies have reported that microRNAs are crucially involved in AD progression. Additionally, several long non‐coding RNAs and circular RNAs have been found to be differentially expressed in AD samples, suggesting their potential roles in vascular physiology and disease. In this review, we discuss the functions of ncRNAs in AD pathophysiology and highlight their potential as biomarkers and therapeutic targets for AD. Meanwhile, we present the animal models previously used for AD research, as well as the specific methods for constructing mouse or rat AD models.

Tempol prevents isoprenaline-induced takotsubo syndrome via the reactive oxygen species/mitochondrial/anti-apoptosis /p38 MAPK pathway

Takotsubo Syndrome (TS) is a kind of acute cardiac syndrome with a complex pathophysiological mechanism that remains to be elucidated. The relationship between TS and reactive oxygen species has received increasing attention over in recent years. Therefore, the relationship between TS and reactive oxygen species was investigated in vivo and in vitro. Isoprenaline (ISO) was used to induce TS and tempol (quercetin) was selected as a scavenger to eliminate reactive oxygen species in animal experiments, and echocardiography was used to determine the incidence of TS. The H9C2 cells were cultured with different reagents to investigate the detailed mechanism; Reactive oxygen species levels and mitochondrial function were evaluated. Cell apoptosis rate was analyzed by TUNEL staining and the proteins involved in the signaling pathways were examined by Western blotting. It was found that a high dose of tempol almost eliminated TS and protected the cardiac function. Moreover, tempol also decreased the reactive oxygen species levels and reduced lipid droplet deposition in myocardial tissue. In terms of the cultured cells, tempol preconditioning decreased reactive oxygen species production as well as lipid droplet deposition, and protected the mitochondrial function by reducing mitochondrial swelling, thereby maintaining the mitochondrial membrane potential (ΔΨ_m) at a level that was higher than that of controls. Furthermore, tempol could reduce cells apoptosis after ISO treatment and decrease the protein level of p38, which is a member of the MAPK family, which and thus plays an important role in regulating cells apoptosis. This antiapoptotic effect of tempol was similar to that of a control reagent, SB203580, which is a specific inhibitor of phospha-p38 (p-p38). This study demonstrated, for the first time, a sudden increase in reactive oxygen species and effects of the downstream cascades play core roles in the development of TS.

Angiotensin II induces cyclooxygenase 2 expression in rat astrocytes via the angiotensin type 1 receptor

We previously showed that Angiotensin (Ang) II stimulated pro-inflammatory and mitogenic actions in astrocytes suggesting that astrocytes are emerging as key players in neuroinflammation. Evidence suggests that neuroinflammation may contribute to central sympathetic overactivity and elevated blood pressure. Further, cyclooxygenase (Cox)-derived prostanoids were implicated in Ang II-dependent hypertension. Cox2 is one of two Cox isoenzymes that is responsible for the formation of prostanoids from arachidonic acid. Constitutively expressed Cox2 has a protective and homeostatic role in the cardiovascular and renal systems. Inducible Cox2 has been associated with pathogenic stimuli resulting in inflammatory conditions and cancers. In this study, we investigated the effect of Ang II on Cox2 protein and mRNA expression in brainstem and cerebellum astrocytes, and determined whether any differences in Cox2 expression exist in spontaneously hypertensive rat (SHR) astrocytes compared to their normotensive control Wistar rats. We demonstrated that Ang II increased Cox2 protein and mRNA levels relative to untreated controls in a time-dependent manner, in Wistar and SHR brainstem and cerebellum astrocytes. Increases in Cox2 protein expression were evident within 4 h, with subsequent sustained elevation for several hours followed by a decline at 48 h. Ang II-induced Cox2 protein levels were higher in Wistar compared to SHRs in both brainstem and cerebellum astrocytes for the majority of time points examined. The Ang II-induced Cox2 mRNA levels increased within 8 h followed by a rapid decline to almost basal levels at later time points. At the earlier time points, Cox2 mRNA elevation were higher in SHR compared to Wistar rat astrocytes. These Ang II actions were mediated by the Ang type I receptor. Our results corroborate previous reports of Ang II's ability to stimulate neuroinflammatory mediators in astrocytes. Cox2-derived prostaglandins might play a role in brain-renin angiotensin system associated hypertension, and astrocytes could be significant players.

Regulation of YAP by Mammalian Target of Rapamycin Complex 1 in Endothelial Cells Controls Blood Pressure Through COX-2/mPGES-1/PGE2 Cascade

Endothelial cells regulate vascular tone by producing both relaxing and contracting factors to control the local blood flow. Hypertension is a common side effect of mTORC1 (mammalian target of rapamycin complex 1) inhibitors. However, the role of endothelial mTORC1 in hypertension remains elusive. The present study aimed to determine the role of endothelial mTORC1 in Ang II (angiotensin II)-induced hypertension and the underlying mechanism. Endothelial mTORC1 activity was increased by Ang II both in vitro and in vivo. Blood pressure was higher in Tie-2-Cre-mediated regulatory associated protein of mTOR (mammalian target of rapamycin; Raptor) heterozygous-deficient (Tie2Cre-Raptor^KD) mice than control mice both before and after Ang II infusion. Acetylcholine-evoked endothelium-dependent relaxation of mesenteric arteries was impaired in Tie2Cre-Raptor^KD mice. Treatment with indomethacin or a specific COX (cyclooxygenase)-2 inhibitor, NS-398, but not L-NG-nitroarginine methyl ester reduced endothelium-dependent relaxation in Raptor^flox/- mice to a similar extent as in Tie2Cre-Raptor^KD mice. Metabolomic profiling revealed that the plasma content of prostaglandin E₂ was reduced in Tie2Cre-Raptor^KD mice with or without Ang II infusion. In endothelial cells, reduction of the protein level of YAP (yes-associated protein) with siRNA-mediated RPTOR deficiency was autophagy dependent and transcriptionally regulated the expression of COX-2 and mPGES-1 (microsomal prostaglandin E synthase-1). Hence, overexpression of YAP in endothelial cells enhanced the mRNA and protein levels of COX-2 and mPGES-1 and reversed the endothelial dysfunction and hypertension in Tie2Cre-Raptor^KD mice. The present results demonstrate that suppression of mTORC1 activity in endothelial cells reduces prostaglandin E₂ production and causes hypertension by reducing YAP-mediated COX-2/mPGES-1 expression.

Blockade of AT1 receptor restore the migration of vascular smooth muscle cells in high sodium medium

The present study aimed to test the hypothesis that increased sodium concentration affects the migratory phenotype of vascular smooth muscle cells (VSMCs) independently of the haemodynamic factors. Cell migration was evaluated by wound-healing assay under the following conditions: high sodium (HS, 160 mM) and control (CT, 140 mM). Cell viability was assessed by annexin V and propidium iodide labeling. Cyclooxygenase-2 (COX-2) gene expression was analysed by reverse transcription polymerase chain reaction. ERK1/2 phosphorylation was assessed by western blot. Exposure of VSMCs to HS reduced migration, and AT1R blockade prevented this response. HS increased COX-2 gene expression, and COX-2 blockade prevented the reduction in VSMC migration induced by HS. HS also increased ERK1/2 phosphorylation, and ERK1/2 inhibition recovered VSMC migration as well as blocked COX-2 gene expression. The TXA₂ receptor blocker, but not the prostacyclin receptor blocker, prevented the HS-induced VSMCs migration decrease. HS reduces the migration of VSMCs by increasing COX-2 gene expression via AT1R-ERK1/2 phosphorylation. In addition, increased COX-2 by HS seems to modulate the reduction of VSMCs migration by the TXA₂ receptor.

Maternal high-sodium intake affects the offspring' vascular renin-angiotensin system promoting endothelial dysfunction in rats

Perinatal sodium overload induces endothelial dysfunction in adult offspring, but the underlying mechanisms are not fully known. The involvement of tissue renin-angiotensin system on high sodium-programmed endothelial dysfunction was examined. Acetylcholine and angiotensin I and II responses were analyzed in aorta and mesenteric resistance arteries from 24-week-old male offspring of normal-salt (O-NS, 1.3% NaCl) and high-salt (O-HS, 8% NaCl) fed dams. COX-2 expression, O₂^- production and angiotensin converting enzyme (ACE) activity were determined. A separated O-HS was treated with losartan (15 mg kg^-1/day) for eight weeks. Compared to O-NS, O-HS were normotensive. Acetylcholine-induced relaxation was impaired in O-HS arteries, which was improved by tempol, apocynin or indomethacin. The angiotensin I-induced contraction was greater in O-HS arteries, whereas the angiotensin II responses were unchanged. ACE activity, O₂^- production and COX-2 expression were increased in O-HS arteries. In this group, the increased O₂^- production was inhibited by apocynin or losartan. Chronic losartan decreased COX-2 expression and restored the endothelium-dependent vasodilation in O-HS. Our findings reiterate that perinatal sodium overload programs endothelial dysfunction in adult offspring through a blood pressure-independent mechanism. Our results also suggest that vascular angiotensin II is the main mediator of high sodium-programmed endothelial dysfunction, promoting COX-2 expression and oxidative stress.

Cigarette Smoke Increases Endothelial CXCL16-Leukocyte CXCR6 Adhesion In Vitro and In Vivo. Potential Consequences in Chronic Obstructive Pulmonary Disease

Cardiovascular disease (CVD) is a major comorbidity in chronic obstructive pulmonary disease (COPD). Although the mechanism of its development remains largely unknown, it appears to be associated with cigarette consumption and reduced lung function. Therefore, the aim of this study was to investigate the potential link between water-soluble cigarette smoke extract (CSE)-induced endothelial dysfunction and the function of CXCL16/CXCR6 axis on the initial attachment of leukocytes, in addition to its possible impact on COPD-associated systemic inflammation. To do this, we employed several experimental approaches, including RNA silencing and flow cytometry analysis, the dynamic flow chamber technique, and intravital microscopy in the cremasteric arterioles of animals exposed to cigarette smoke (CS). CSE-induced arterial CXCL16 expression, leading to increased platelet–leukocyte and mononuclear cell adhesiveness. CSE-induced CXCL16 expression was dependent on Nox5 expression and subsequent RhoA/p38 MAPK/NF-κB activation. Flow cytometry analysis revealed that COPD patients (n = 35) presented greater numbers of activated circulating platelets (PAC-1⁺ and P-selectin⁺) expressing CXCL16 and CXCR6 as compared with age-matched controls (n = 17), with a higher number of CXCR6⁺-platelets in the smoking COPD group than in ex-smokers. This correlated with enhanced circulating CXCR6⁺-platelet–leukocyte aggregates in COPD patients. The increase in circulating numbers of CXCR6-expressing platelets and mononuclear cells resulted in enhanced platelet–leukocyte and leukocyte adhesiveness to CSE-stimulated arterial endothelium, which was greater than that found in age-matched controls and was partly dependent on endothelial CXCL16 upregulation. Furthermore, CS exposure provoked CXCL16-dependent leukocyte–arteriolar adhesion in cremasteric arterioles, which was significantly reduced in animals with a nonfunctional CXCR6 receptor. In conclusion, we provide the first evidence that increased numbers of CXCR6-expressing circulating platelets and mononuclear leukocytes from patients with COPD might be a marker of systemic inflammation with potential consequences in CVD development. Accordingly, CXCL16/CXCR6 axis blockade might constitute a new therapeutic approach for decreasing the risk of CVD in COPD patients.

Methodological Approach to Use Fresh and Cryopreserved Vessels as Tools to Analyze Pharmacological Modulation of the Angiogenic Growth

The sprouting of new vessels is greatly influenced by the procedure chosen. We sought to optimize the experimental conditions of the angiogenic growth of fresh and cryopreserved vessels cultured in Matrigel with the aim to use this system to analyze the pharmacological modulation of the process. Segments of second-order branches of rat mesenteric resistance arteries, thoracic aorta of rat or mouse, and cryopreserved rat aorta and human femoral arteries were cultured in Matrigel for 7-21 days in different mediums, as well as in the absence of endothelial or adventitia layer. Quantification of the angiogenic growth was performed by either direct measurement of the mean length of the neovessels or by calcein AM staining and determination of fluorescence intensity and area. Fresh and cryopreserved arterial rings incubated in Matrigel exhibited a spontaneous angiogenic response that was strongly accelerated by fetal calf serum. Addition of vascular endothelial growth factor, fibroblast growth factor, endothelial growth factor, or recombinant insulin-like growth factor failed to increase aortic sprouting, unless all were added together. Removal of adventitia, but not the endothelial layer, abrogated the angiogenic response of aortic rings. Determination of the mean neovessel length is an easy and accurate method to quantify the angiogenic growth devoid of confounding factors, such as inclusion of other cellular types surrounding the neovessels. Activity of a α1-adrenoceptor agonist (phenylephrine) and its inhibition by a selective antagonist (prazosin) were analyzed to prove the usefulness of the Matrigel system to evaluate the pharmacological modulation of the angiogenic growth.

Losartan reverses COX-2-dependent vascular dysfunction in offspring of hyperglycaemic rats

AIMS

This study examined whether chronic treatment with losartan, an angiotensin II type 1 receptor (AT₁R) antagonist, might reverse COX-2-mediated vascular dysfunction in mesenteric resistance arteries (MRA) from offspring of hyperglycaemic rats.

MATERIALS AND METHODS

Male 12-month-old offspring of hyperglycaemic (O-DR) and normoglycaemic (O-CR) rats were treated with losartan (15mg·kg·day^-1) during 2months. Third order MRA of untreated and losartan-treated O-DR and O-CR were mounted in wire myograph for isometric tension measurements. COX-2 expression was analyzed by Western blot; TxA₂, PGE₂ and PGF_2α release was measured using commercial kits.

KEY FINDINGS

O-DR showed increased blood pressure, impaired acetylcholine-induced vasodilation and increased noradrenaline-induced vasoconstriction than O-CR. All these parameters were normalized by losartan in O-DR. Pre-incubation of MRA with indomethacin (COX-1/2 inhibitor), NS-398 (COX-2 inhibitor) or tempol (superoxide dismutase mimetic) increased relaxation to acetylcholine and reduced contraction to noradrenaline only in O-DR. COX-2 expression, TxA₂, PGE₂ and PGF_2α release were increased in O-DR. In losartan-treated O-DR, NS-398, indomethacin or tempol failed to produce any effect on acetylcholine or noradrenaline responses. Losartan treatment reduced COX-2 expression, TxA₂, PGE₂ and PGF_2α release in O-DR.

SIGNIFICANCE

The present results reveal that chronic losartan administration in O-DR normalizes endothelial function in MRA by correcting the existing COX-2 overexpression and the imbalance between endothelium-derived relaxing and contracting factors. These findings not only support the beneficial effects of AT₁ receptor antagonist in O-DR, but also suggest the implication of angiotensin II as a putative mediator of hyperglycemia-programmed vascular dysfunction in rats.

Role of COX-2-derived PGE2 on vascular stiffness and function in hypertension

BACKGROUND AND PURPOSE

Prostanoids derived from COX-2 and EP receptors are involved in vascular remodelling in different cardiovascular pathologies. This study evaluates the contribution of COX-2 and EP1 receptors to vascular remodelling and function in hypertension.

EXPERIMENTAL APPROACH

Spontaneously hypertensive rats (SHR) and angiotensin II (AngII)-infused (1.44 mg · kg(-1) · day(-1), 2 weeks) mice were treated with the COX-2 inhibitor celecoxib (25 mg · kg(-1) · day(-1) i.p) or with the EP1 receptor antagonist SC19220 (10 mg · kg(-1) · day(-1) i.p.). COX-2(-/-) mice with or without AngII infusion were also used.

KEY RESULTS

Celecoxib and SC19220 treatment did not modify the altered lumen diameter and wall : lumen ratio in mesenteric resistance arteries from SHR-infused and/or AngII-infused animals. However, both treatments and COX-2 deficiency decreased the augmented vascular stiffness in vessels from hypertensive animals. This was accompanied by diminished vascular collagen deposition, normalization of altered elastin structure and decreased connective tissue growth factor and plasminogen activator inhibitor-1 gene expression. COX-2 deficiency and SC19220 treatment diminished the increased vasoconstrictor responses and endothelial dysfunction induced by AngII infusion. Hypertensive animals showed increased mPGES-1 expression and PGE2 production in vascular tissue, normalized by celecoxib. Celecoxib treatment also decreased AngII-induced macrophage infiltration and TNF-α expression. Macrophage conditioned media (MCM) increased COX-2 and collagen type I expression in vascular smooth muscle cells; the latter was reduced by celecoxib treatment.

CONCLUSIONS AND IMPLICATIONS

COX-2 and EP1 receptors participate in the increased extracellular matrix deposition and vascular stiffness, the impaired vascular function and inflammation in hypertension. Targeting PGE2 receptors might have benefits in hypertension-associated vascular damage.

Valsartan decreases platelet activity and arterial thrombotic events in elderly patients with hypertension

BACKGROUND

Angiotensin type 1 receptor (AT 1 R) antagonists are extensively used for blood pressure control in elderly patients with hypertension. This study aimed to investigate the inhibitory effects of AT 1 R antagonist valsartan on platelet aggregation and the occurrence of cardio-cerebral thrombotic events in elderly patients with hypertension.

METHODS

Two-hundred and ten patients with hypertension and aged > 60 years were randomized to valsartan (n = 140) or amlodipine (n = 70) on admission. The primary endpoint was platelet aggregation rate (PAR) induced by arachidonic acid at discharge, and the secondary endpoint was the rate of thrombotic events including brain infarction and myocardial infarction during follow-up. Human aortic endothelial cells (HAECs) were stimulated by angiotensin II (Ang II, 100 nmol/L) with or without pretreatment of valsartan (100 nmol/L), and relative expression of cyclooxygenase-2 (COX-2) and thromboxane B 2 (TXB 2 ) and both p38 mitogen-activated protein kinase (p38MAPK) and nuclear factor-kB (NF-kB) activities were assessed. Statistical analyses were performed by GraphPad Prism 5.0 software (GraphPad Software, Inc., California, USA).

RESULTS

PAR was lower after treatment with valsartan (11.49 ± 0.69% vs. 18.71 ± 2.47%, P < 0.001), associated with more reduced plasma levels of COX-2 (76.94 ± 7.07 U/L vs. 116.4 ± 15.89 U/L, P < 0.001) and TXB 2 (1667 ± 56.50 pg/ml vs. 2207 ± 180.20 pg/ml) (all P < 0.001). Plasma COX-2 and TXB 2 levels correlated significantly with PAR in overall patients (r = 0.109, P < 0.001). During follow-up (median, 18 months), there was a significantly lower thrombotic event rate in patients treated with valsartan (14.3% vs. 32.8%, P = 0.002). Relative expression of COX-2 and secretion of TXB 2 with concordant phosphorylation of p38MAPK and NF-kB were increased in HAECs when stimulated by Ang II (100 nmol/L) but were significantly decreased by valsartan pretreatment (100 nmol/L).

CONCLUSIONS

AT 1 R antagonist valsartan decreases platelet activity by attenuating COX-2/TXA 2 expression through p38MAPK and NF-kB pathways and reduces the occurrence of cardio-cerebral thrombotic events in elderly patients with hypertension.

Acidic environment activates inflammatory programs in fibroblasts via a cAMP-MAPK pathway

The tissue micromilieu in disorders (inflammation, ischemia, tumor) often shows pronounced metabolic acidosis that may alter signaling and transcriptional activity in resident cells which can be of special importance for omnipresent fibroblasts. In the present study we investigated the impact of metabolic acidosis on rat fibroblasts with special emphasis on their role in inflammation by regulation of TNF-α, MCP-1, COX-2 and iNOS expression and the signaling pathways involved. Extracellular acidosis led to an enhanced expression of TNF-α, COX-2 and iNOS in parallel to an activation of p38 and ERK1/2 kinases that was not observed by sole intracellular acidosis. Accordingly, the protein amounts of TNF-α and COX-2 as well as the production of nitrate and nitrite were elevated. Acidosis-induced expression of COX-2 and iNOS depended on p38 kinase, but not on ERK1/2. In contrast acidosis-induced TNF-α expression was independent of both kinases. Although GPR4, GPR68 and GPR132 are expressed in fibroblasts, the involvement of these potential candidate pH sensors could be ruled out since no acidosis-induced elevation in intracellular cAMP or free calcium content was observed. Furthermore our data show that MAPK activation by an acidic micromilieu depends on Ser/Thr phosphatase activity, but not on the production of reactive oxygen species and is sensitive to cAMP antagonism by Rp-cAMPS. In conclusion, our results show that an acidic microenvironment induces a differential transcriptional program of pathological relevant genes in fibroblasts via the cAMP-phosphatase-MAPK pathway and thereby generates a parainflammatory situation that can result in tissue remodeling.

Valsartan decreases neointimal hyperplasia in balloon-injured rat aortic arteries by upregulating HO-1 and inhibiting angiotensin II type 1 receptor

AIMS

Upregulation of heme oxygenase (HO)-1 plays an important role in vascular protection. Valsartan attenuates neointimal hyperplasia in animal studies. The objective of this study was to examine the role of HO-1 and angiotensin II type 1 (AT1) receptor in the action of valsartan on neointimal hyperplasia in balloon-injured rat aortic arteries.

MAIN METHODS

Thirty-six male Wistar rats were randomly divided into the following three groups with twelve rats in each group: control group, surgery (model) group, and valsartan group. Aortic balloon injury was performed to elicit endothelial denudation with a 2F balloon catheter. On days 14 and 28 after injury, blood was harvested to measure bilirubin levels. Aortic arteries were harvested for morphometry analysis, to determine angiotensin II (Ang II) level, and to analyze mRNA or protein expression.

KEY FINDINGS

Compared with the control group, proliferation and intimal thickening of vascular smooth muscle cells (VSMCs) were obvious in the surgery group rats on days 14 and 28 after injury. Valsartan significantly reduced the proliferation and intimal thickening. Additionally, pretreatment with valsartan significantly reduced Ang II levels, AT1 receptor, and p38 mitogen-activated protein kinase (MAPK) expression. Valsartan increased HO-1 protein and mRNA expression, as well as increased serum bilirubin levels compared with the surgery group.

SIGNIFICANCE

Valsartan treatment decreased neointimal hyperplasia in balloon-injured rats. The mechanism of action might be linked to the upregulation of HO-1, downregulation of AT1 receptor and inhibition of p38MAPK signal pathway.

Pioglitazone reduces angiotensin II-induced COX-2 expression through inhibition of ROS production and ET-1 transcription in vascular cells from spontaneously hypertensive rats

Glitazones have anti-inflammatory properties by interfering with the transcription of proinflammatory genes, such as cyclooxygenase (COX)-2, and with ROS production, which are increased in hypertension. This study analyzed whether pioglitazone modulates COX-2 expression in hypertension by interfering with ROS and endothelin (ET)-1. In vivo, pioglitazone (2.5 mg·kg(-1)·day(-1), 28 days) reduced the greater levels of COX-2, pre-pro-ET-1, and NADPH oxidase (NOX) expression and activity as well as O2 (·-) production found in aortas from spontaneously hypertensive rats (SHRs). ANG II increased COX-2 and pre-pro-ET-1 levels more in cultured vascular smooth muscle cells from hypertensive rats compared with normotensive rats. The ETA receptor antagonist BQ-123 reduced ANG II-induced COX-2 expression in SHR cells. ANG II also increased NOX-1 expression, NOX activity, and superoxide production in SHR cells; the selective NOX-1 inhibitor ML-171 and catalase reduced ANG II-induced COX-2 and ET-1 transcription. ANG II also increased c-Jun transcription and phospho-JNK1/2, phospho-c-Jun, and p65 NF-κB subunit nuclear protein expression. SP-600125 and lactacystin, JNK and NF-κB inhibitors, respectively, reduced ANG II-induced ET-1, COX-2, and NOX-1 levels and NOX activity. Pioglitazone reduced the effects of ANG II on NOX activity, NOX-1, pre-pro-ET-1, COX-2, and c-Jun mRNA levels, JNK activation, and nuclear phospho-c-Jun and p65 expression. In conclusion, ROS production and ET-1 are involved in ANG II-induced COX-2 expression in SHRs, explaining the greater COX-2 expression observed in this strain. Furthermore, pioglitazone inhibits ANG II-induced COX-2 expression likely by interfering with NF-κB and activator protein-1 proinflammatory pathways and downregulating ROS production and ET-1 transcription, thus contributing to the anti-inflammatory properties of glitazones.

Low-dose chronic lead exposure increases systolic arterial pressure and vascular reactivity of rat aortas

Chronic lead exposure induces hypertension affecting endothelial function. We investigated whether low-concentration lead exposure alters blood pressure and vascular reactivity, focusing on the roles of NO, oxidative stress, cyclooxygenase-derived vasoconstrictor prostanoids, and the local angiotensin-renin system. Aortic rings from 3-month-old Wistar rats were treated daily with lead acetate (first dose 4mg/100g, subsequent doses 0.05mg/100g, im) or vehicle for 30 days. Treatment increased lead blood levels (12μg/dl), blood pressure, and aortic ring contractile response to phenylephrine (1nM-100mM). Contractile response after L-NAME administration increased in both groups but was higher after lead treatment. Lead effects on Rmax decreased more after apocynin and superoxide dismutase administration compared to control. Indomethacin reduced phenylephrine response more after lead treatment than in controls. The selective COX-2 inhibitor NS398, thromboxane A2/prostaglandin H2 receptor antagonist SQ 29,548, TXA2 synthase inhibitor furegrelate, EP1 receptor antagonist SC 19220, and ACE inhibitor and AT1 receptor antagonist losartan reduced phenylephrine responses only in vessels from lead-treated rats. Basal and stimulated NO release was reduced and local O2(-) liberation increased in the lead-treated group compared to controls. eNOS, iNOS, and AT1 receptor protein expression increased with lead exposure, but COX-2 protein expression decreased. This is the first demonstration that blood Pb(2+) (12µg/dl) concentrations below the WHO-established values increased systolic blood pressure and vascular phenylephrine reactivity. This effect was associated with reduced NO bioavailability, increased reactive oxygen species production, increased participation of COX-derived contractile prostanoids, and increased renin-angiotensin system activity.

New roles for old pathways? A circuitous relationship between reactive oxygen species and cyclo-oxygenase in hypertension

Elevated production of prostanoids from the constitutive (COX-1) or inducible (COX-2) cyclo-oxygenases has been involved in the alterations in vascular function, structure and mechanical properties observed in cardiovascular diseases, including hypertension. In addition, it is well known that production of ROS (reactive oxygen species) plays an important role in the impaired contractile and vasodilator responses, vascular remodelling and altered vascular mechanics of hypertension. Of particular interest is the cross-talk between NADPH oxidase and mitochondria, the main ROS sources in hypertension, which may represent a vicious feed-forward cycle of ROS production. In recent years, there is experimental evidence showing a relationship between ROS and COX-derived products. Thus ROS can activate COX and the COX/PG (prostaglandin) synthase pathways can induce ROS production through effects on different ROS generating enzymes. Additionally, recent evidence suggests that the COX-ROS axis might constitute a vicious circle of self-perpetuating vasoactive products that have a pathophysiological role in altered vascular contractile and dilator responses and hypertension development. The present review discusses the current knowledge on the role of oxidative stress and COX-derived prostanoids in the vascular alterations observed in hypertension, highlighting new findings indicating that these two pathways act in concert to induce vascular dysfunction.

Reciprocal relationship between reactive oxygen species and cyclooxygenase-2 and vascular dysfunction in hypertension

AIMS

This study evaluates a possible relationship between reactive oxygen species (ROS) and cyclooxygenase (COX)-2-derived products in conductance and resistance arteries from hypertensive animals. Angiotensin II (Ang II)-infused mice or spontaneously hypertensive rats treated with the NAD(P)H Oxidase inhibitor apocynin, the mitochondrion-targeted SOD2 mimetic Mito-TEMPO, the superoxide dismutase analog tempol, or the COX-2 inhibitor Celecoxib were used.

RESULTS

Apocynin, Mito-TEMPO, and Celecoxib treatments prevented Ang II-induced hypertension, the increased vasoconstrictor responses to phenylephrine, and the reduced acetylcholine relaxation. The NOX-2 inhibitor gp91ds-tat, the NOX-1 inhibitor ML171, catalase, and the COX-2 inhibitor NS398 abolished the ex vivo effect of Ang II-enhancing phenylephrine responses. Antioxidant treatments diminished the increased vascular COX-2 expression, prostanoid production, and/or participation of COX-derived contractile prostanoids and thromboxane A(2) receptor (TP) in phenylephrine responses, observed in arteries from hypertensive models. The treatment with the COX-2 inhibitor normalized the increased ROS production (O(2)·(-) and H(2)O(2)), NAD(P)H Oxidase expression (NOX-1, NOX-4, and p22phox) and activity, MnSOD expression, and the participation of ROS in vascular responses in both hypertensive models. Apocynin and Mito-TEMPO also normalized these parameters of oxidative stress. Apocynin, Mito-TEMPO, and Celecoxib improved the diminished nitric oxide (NO) production and the modulation by NO of phenylephrine responses in the Ang II model.

INNOVATION

This study provides mechanistic evidence of circuitous relationship between COX-2 products and ROS in hypertension.

CONCLUSION

The excess of ROS from NAD(P)H Oxidase and/or mitochondria and the increased vascular COX-2/TP receptor axis act in concert to induce vascular dysfunction and hypertension.

Angiotensin II protects primary rat hepatocytes against bile salt-induced apoptosis

Angiotensin II (AT-II) is a pro-fibrotic compound that acts via membrane-bound receptors (AT-1R/AT-2R) and thereby activates hepatic stellate cells (HSCs). AT-II receptor blockers (ARBs) are thus important candidates in the treatment of liver fibrosis. However, multiple case reports suggest that AT-1R blockers may induce hepatocyte injury. Therefore, we investigated the effect of AT-II and its receptor blockers on cytokine-, oxidative stress- and bile salt-induced cell death in hepatocytes. Primary rat hepatocytes were exposed to TNF-α/Actinomycin D, the ROS-generating agent menadione or the bile salts: glycochenodeoxycholic acid (GCDCA) and tauro-lithocholic acid-3 sulfate (TLCS), to induce apoptosis. AT-II (100 nmol/L) was added 10 minutes prior to the cell death-inducing agent. AT-1R antagonists (Sartans) and the AT-2R antagonist PD123319 were used at 1 µmol/L. Apoptosis (caspase-3 activity, acridine orange staining) and necrosis (Sytox green staining) were quantified. Expression of CHOP (marker for ER stress) and AT-II receptor mRNAs were quantified by Q-PCR. AT-II dose-dependently reduced GCDCA-induced apoptosis of hepatocytes (−50%, p<0.05) without inducing necrosis. In addition, AT-II reduced TLCS-induced apoptosis of hepatocytes (−50%, p<0.05). However, AT-II did not suppress TNF/Act-D and menadione-induced apoptosis. Only the AT-1R antagonists abolished the protective effect of AT-II against GCDCA-induced apoptosis. AT-II increased phosphorylation of ERK and a significant reversal of the protective effect of AT-II was observed when signaling kinases, including ERK, were inhibited. Moreover, AT-II prevented the GCDCA-induced expression of CHOP (the marker of the ER-mediated apoptosis).

P38 MAPK signaling pathway: biological functions, roles in the pathogenesis of liver fibrosis and common research methods

The activation and proliferation of hepatic stellate cells (HSC) are the key events in hepatic fibrogenesis. Now the research about the mechanisms of action of HSC-related signal transduction has become a hot topic. This article reviews the biological functions of the p38 MAPK signaling pathway and its roles in the pathogenesis of liver fibrosis and summarizes common research methods for this signaling pathway.

Mechanisms underlying altered extracellular nucleotide-induced contractions in mesenteric arteries from rats in later-stage type 2 diabetes: effect of ANG II type 1 receptor antagonism

Little is known about the vascular contractile responsiveness to, and signaling pathways for, extracellular nucleotides in the chronic stage of type 2 diabetes or whether the ANG II type 1 receptor blocker losartan might alter such responses. We hypothesized that nucleotide-induced arterial contractions are augmented in diabetic Goto-Kakizaki (GK) rats and that treatment with losartan would normalize the contractions. Here, we investigated the vasoconstrictor effects of ATP/UTP in superior mesenteric arteries isolated from GK rats (37-42 wk old) that had or had not received 2 wk of losartan (25 mg·kg(-1)·day(-1)). In arteries from GK rats (vs. those from Wistar rats), 1) ATP- and UTP-induced contractions, which were blocked by the nonselective P2 antagonist suramin, were enhanced, and these enhancements were suppressed by endothelial denudation, by cyclooxygenase (COX) inhibitors, or by a cytosolic phospholipase A(2) (cPLA(2)) inhibitor; 2) both nucleotides induced increased release of PGE(2) and PGF(2α); 3) nucleotide-stimulated cPLA(2) phosphorylations were increased; 4) COX-1 and COX-2 expressions were increased; and 5) neither P2Y2 nor P2Y6 receptor expression differed, but P2Y4 receptor expression was decreased. Mesenteric arteries from GK rats treated with losartan exhibited (vs. untreated GK) 1) reduced nucleotide-induced contractions, 2) suppressed UTP-induced release of PGE(2) and PGF(2α), 3) suppressed UTP-stimulated cPLA(2) phosphorylation, 4) normalized expressions of COX-2 and P2Y4 receptors, and 5) reduced superoxide generation. Our data suggest that the diabetes-related enhancement of ATP-mediated vasoconstriction was due to P2Y receptor-mediated activation of the cPLA(2)/COX pathway and, moreover, that losartan normalizes such contractions by a suppressing action within this pathway.

Angiotensin II differentially modulates cyclooxygenase-2, microsomal prostaglandin E2 synthase-1 and prostaglandin I2 synthase expression in adventitial fibroblasts exposed to inflammatory stimuli

AIMS

To assess whether angiotensin II (Ang II) modulates key enzymes of the cyclooxygenase (COX)-2/prostanoid pathway, including prostaglandin E synthase-1 (mPGES-1) and prostacyclin synthase (PGIS) in rat aortic adventitial fibroblasts in the presence or absence of an inflammatory stimulus [interleukin (IL)-1β].

METHODS AND RESULTS

Fibroblasts stimulated with IL-1β (10 ng/ml, 24 h) and/or Ang II (0.1 μmol/l, 24 h) were used. IL-1β up-regulated COX-2 and mPGES-1 (protein and mRNA) and increased PGI2 and PGE2 release, without altering PGIS protein expression. Ang II did modify neither COX-2 and mPGES-1 expression nor prostanoid levels, but it induced PGIS expression. Interestingly, Ang II further enhanced IL-1β-induced COX-2 expression and PGI2 release and concomitantly reduced IL-1β-induced mPGES-1 expression. The AT1 receptor antagonist losartan prevented the effects of Ang II on IL-1β-induced COX-2 or mPGES-1 expression. IL-1β activated p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK)1/2 pathways, and coincubation with Ang II resulted in a higher and more sustained phosphorylation of both MAPK. Inhibition of either p38 MAPK (SB203580) or ERK1/2 (PD98059) reduced COX-2 and mPGES-1 expression in cells treated with IL-1β or the combination of IL-1β and Ang II. Ang II did not modify COX-2 transcriptional activity but increased COX-2 mRNA stability in IL-1β-treated cells; by contrast, it increased PGIS mRNA levels through a transcriptional mechanism.

CONCLUSION

Ang II differentially modulates key enzymes involved in prostanoid biosynthesis thereby altering the balance between PGI2/PGE2 in vascular cells exposed to inflammatory stimuli.

Angiotensin II downregulates catalase expression and activity in vascular adventitial fibroblasts through an AT1R/ERK1/2-dependent pathway

Angiotensin II (Ang II) plays a profound regulatory effect on NADPH oxidase and the functional features of vascular adventitial fibroblasts, but its role in antioxidant enzyme defense remains unclear. This study investigated the effect of Ang II on expressions and activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in adventitial fibroblasts and the possible mechanism involved. Ang II decreased the expression and activity of CAT in a dose- and time-dependent manner, but not that of SOD and GPx. The effects were abolished by the angiotensin II type 1 receptor (AT1R) blocker losartan and AT1R small-interfering RNA (siRNA). Incubation with polyethylene glycol-CAT prevented the Ang II-induced effects on reactive oxygen species (ROS) generation and myofibroblast differentiation. Moreover, Ang II rapidly induced phosphorylation of ERK1/2, which was reversed by losartan and AT1R siRNA. Pharmacological blockade of ERK1/2 improved Ang II-induced decrease in CAT protein expression. These in vitro results indicate that Ang II induces ERK1/2 activation, contributing to the downregulation of CAT as well as promoting oxidative stress and adventitial fibroblast phenotypic differentiation in an AT1R-mediated manner.

p38 Mitogen-activated protein kinase (MAPK) increases arginase activity and contributes to endothelial dysfunction in corpora cavernosa from angiotensin-II-treated mice

INTRODUCTION

Angiotensin II (AngII) activates p38 mitogen-activated protein kinase (MAPK) and elevates arginase activity in endothelial cells. Upregulation of arginase activity has been implicated in endothelial dysfunction by reducing nitric oxide (NO) bioavailability. However, signaling pathways activated by AngII in the penis are largely unknown.

AIM

We hypothesized that activation of p38 MAPK increases arginase activity and thus impairs penile vascular function in AngII-treated mice.

METHODS

Male C57BL/6 mice were implanted with osmotic minipumps containing saline or AngII (42 µg/kg/h) for 14 days and cotreated with p38 MAPK inhibitor, SB 203580 (5 µg/kg/day), beginning 2 days before minipump implantation. Systolic blood pressure (SBP) was measured. Corpus cavernosum (CC) tissue was used for vascular functional studies and protein expression levels of p38 MAPK, arginase and constitutive NO synthase (NOS), and arginase activity.

MAIN OUTCOME MEASURES

Arginase expression and activity; expression of phospho-p38 MAPK, endothelial NOS (eNOS) and neuronal NOS proteins; endothelium-dependent and nitrergic nerve-mediated relaxations were determined in CC from control and AngII-infused mice.

RESULTS

AngII increased SBP (22%) and increased CC arginase activity and expression (∼twofold), and phosphorylated P38 MAPK levels (30%) over control. Treatment with SB 203580 prevented these effects. Endothelium-dependent NO-mediated relaxation to acetylcholine was significantly reduced by AngII and this effect was prevented by SB 203580 (P < 0.01). AngII (2 weeks) did not alter nitrergic function. However, SB 203580 significantly increased nitrergic relaxation in both control and AngII tissue at lower frequencies. Maximum contractile responses for phenylephrine and electrical field stimulation were increased by AngII (56% and 171%, respectively) and attenuated by SB 203580 treatment. AngII treatment also decreased eNOS phosphorylation at Ser-1177 compared to control. Treatment with SB 203580 prevented all these changes.

CONCLUSION

p38 MAPK inhibition corrects penile arginase activity and protects against erectile dysfunction caused by AngII.

Polyphenol-containing azuki bean (Vigna angularis) seed coats attenuate vascular oxidative stress and inflammation in spontaneously hypertensive rats

We investigated the effects of azuki bean (Vigna angularis) seed coats (ABSC), which contain polyphenols, on the vascular oxidative stress and inflammation associated with hypertension. Spontaneously hypertensive rats (SHR) and control normotensive Wistar-Kyoto (WKY) rats were divided into 2 groups each. One group was fed 0% ABSC; the other, a 1.0% ABSC-containing diet. Tail systolic blood pressure (SBP) was examined throughout ABSC treatment. At 8 weeks, vascular superoxide (O(2)(-)) production was measured by lucigenin-enhanced chemiluminescence. mRNA expressions of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, macrophage chemoattractant protein-1 (MCP-1) and its receptor C-C chemokine receptor 2 (CCR2) in the aorta were analyzed by reverse transcriptase-polymerase chain reaction. Protein expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were determined by western blotting. Polyphenol-containing ABSC suppressed the elevation of SBP throughout the treatment period. The NADPH-stimulated O(2)(-) level decreased significantly in the aorta of ABSC-treated SHR compared with the level of untreated SHR. The p47phox and Nox4 mRNA expression increased significantly in untreated SHR compared with that in WKY rats. Conversely, the level of p47phox mRNA was significantly lower in ABSC-treated SHR than in untreated SHR. The protein abundance of both iNOS and COX-2 was significantly decreased in the aorta of the ABSC-treated SHR compared with this abundance in untreated SHR. The MCP-1 and CCR2 mRNA expressions increased in untreated SHR, and these levels were significantly lower in ABSC-treated SHR. In conclusion, our results suggested that polyphenol-containing ABSC could attenuate vascular oxidative stress and inflammation during the progression of hypertension, and this may lead to an improvement in hypertension.

Gq protein mediates UVB-induced cyclooxygenase-2 expression by stimulating HB-EGF secretion from HaCaT human keratinocytes

Ultraviolet (UV) radiation induces cyclooxygenase-2 expression to produce cellular responses including aging and carcinogenesis in skin. We hypothesised that heterotrimeric G proteins mediate UV-induced COX-2 expression by stimulating secretion of soluble HB-EGF (sHB-EGF). In this study, we aimed to elucidate the role and underlying mechanism of the alpha subunit of Gq protein (Galphaq) in UVB-induced HB-EGF secretion and COX-2 induction. We found that expression of constitutively active Galphaq (GalphaqQL) augmented UVB-induced HB-EGF secretion, which was abolished by knockdown of Galphaq with shRNA in HaCaT human keratinocytes. Galphaq was found to mediate the UVB-induced HB-EGF secretion by sequential activation of phospholipase C (PLC), protein kinase Cdelta (PKCdelta), and matrix metaloprotease-2 (MMP-2). Moreover, GalphaqQL mediated UVB-induced COX-2 expression in an HB-EGF-, EGFR-, and p38-dependent manner. From these results, we concluded that Galphaq mediates UV-induced COX-2 expression through activation of EGFR by HB-EGF, of which ectodomain shedding was stimulated through sequential activation of PLC, PKCdelta and MMP-2 in HaCaT cells.