HuR mediates the synergistic effects of angiotensin II and IL-1β on vascular COX-2 expression and cell migration

Long Noncoding RNA HAFML Promotes Migration and Invasion of Rheumatoid Fibroblast-like Synoviocytes

The aggressive phenotype exhibited by fibroblast-like synoviocytes (FLSs) is critical for the progression of joint destruction in rheumatoid arthritis (RA). Long noncoding RNAs (lncRNAs) have crucial roles in the pathogenesis of diverse disorders; however, few have been identified that might be able to control the joint damage in RA. In this study, we identified an lncRNA, ENST00000509194, which was expressed at abnormally high levels in FLSs and synovial tissues from patients with RA. ENST00000509194 positively modulates the migration and invasion of FLSs by interacting with human Ag R (HuR, also called ELAVL1), an RNA-binding protein that mainly stabilizes mRNAs. ENST00000509194 binds directly to HuR in the cytoplasm to form a complex that promotes the expression of the endocytic adaptor protein APPL2 by stabilizing APPL2 mRNA. Knockdown of HuR or APPL2 impaired the migration and invasion of RA FLSs. Given its close association with HuR and FLS migration, we named ENST00000509194 as HAFML (HuR-associated fibroblast migratory lncRNA). Our findings suggest that an increase in synovial HAFML might contribute to FLS-mediated rheumatoid synovial aggression and joint destruction, and that the lncRNA HAFML might be a potential therapeutic target for dysregulated fibroblasts in a wide range of diseases.

CBS-H2S axis preserves the intestinal barrier function by inhibiting COX-2 through sulfhydrating human antigen R in colitis

INTRODUCTION

Lipopolysaccharide (LPS) causes lesions of the epithelial barrier, which allows translocation of pathogens from the intestinal lumen to the host's circulation. Hydrogen sulfide (H₂S) regulates multiple physiological and pathological processes in colonic epithelial tissue, and CBS-H₂S axis involved in multiple gastrointestinal disorder. However, the mechanism underlying the effect of the CBS-H₂S axis on the intestinal and systemic inflammation in colitis remains to be illustrated.

OBJECTIVES

To investigate the effect of CBS-H₂S axis on the intestinal and systematic inflammation related injuries in LPS induced colitis and the underlying mechanisms.

METHODS

Wild type and CBS^-/+ mice were used to evaluate the effect of endogenous and exogenous H₂S on LPS-induced colitis in vivo. Cytokine quantitative antibody array, western blot and real-time PCR were applied to detect the key cytokines in the mechanism of action. Biotin switch of S-sulfhydration, CRISPR/Cas9 mediated knockout, immunofluorescence and ActD chase assay were used in the in vitro experiment to further clarify the molecular mechanisms.

RESULTS

H₂S significantly alleviated the symptoms of LPS-induced colitis in vivo and attenuated the increase of COX-2 expression. The sulfhydrated HuR increased when CBS express normally or GYY4137 was administered. While after knocking kown CBS, the expression of COX-2 in mice colon increased significantly, and the sulfhydration level of HuR decreased. The results in vitro illustrated that HuR can increase the stability of COX-2 mRNA, and the decrease of COX-2 were due to increased sulfhydration of HuR rather than the reduction of total HuR levels.

CONCLUSION

These results indicated that CBS-H₂S axis played an important role in protecting intestinal barrier function in colitis. CBS-H₂S axis increases the sulfhydration level of HuR, by which reduces the binding of HuR with COX-2 mRNA and inhibited the expression of COX-2.

Long Non-Coding RNA MEG8 Suppresses Hypoxia-Induced Excessive Proliferation, Migration and Inflammation of Vascular Smooth Muscle Cells by Regulation of the miR-195-5p/RECK Axis

It has been recognized that rebalancing the abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) helps relieve vascular injury. Presently, we aim to investigate whether long non-coding RNA (lncRNA) maternally expressed 8 (MEG8) plays a role in affecting the excessive proliferation and migration of VSMCs following hypoxia stimulation. A percutaneous transluminal angioplasty balloon dilatation catheter was adopted to establish vascular intimal injury, the levels of MEG8 and miR-195-5p in the carotid artery were tested by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Hypoxia was used to stimulate VSMCs, then the cell counting kit-8 (CCK-8) assay, Transnwell assay, and wound healing assay were conducted to evaluate the proliferation, and migration of VSMCs. The protein levels of RECK (reversion inducing cysteine rich protein with kazal motifs), MMP (matrix metalloproteinase) 3/9/13, COX2 (cytochrome c oxidase subunit II), macrophage inflammatory protein (MIP)-1beta, VCAM-1 (vascular cell adhesion molecule 1), ICAM-1 (intercellular adhesion molecule 1), and HIF-1α (hypoxia inducible factor 1 subunit alpha) were determined by western blot or cellular immunofluorescence. As the data showed, MEG8 was down-regulated in the carotid artery after balloon injury in rats and hypoxia-treated VSMCs, and miR-195-5p was overexpressed. Forced MEG8 overexpression or inhibiting miR-195-5p attenuated hypoxia-promoted cell proliferation and migration of VSMCs. In addition, miR-195-5p up-regulation reversed MEG8-mediated effects. Hypoxia hindered the RECK expression while boosted MMP3/9/13 levels, and the effect was markedly reversed with MEG8 up-regulation or miR-195-5p down-regulation. Mechanistically, MEG8 functioned as a competitive endogenous (ceRNA) by sponging miR-195-5p which targeted RECK. Moreover, the HIF-1α inhibitor PX478 prevented hypoxia-induced proliferation, and migration of VSMCs, upregulated MEG8, and restrained miR-195-5p expression. Overall, lncRNA MEG8 participated in hypoxia-induced excessive proliferation, inflammation and migration of VSMCs through the miR-195-5p/RECK axis.

Therapeutic Potential of Phosphodiesterase Inhibitors for Endothelial Dysfunction- Related Diseases

Cardiovascular diseases (CVD) are considered a major health problem worldwide, being the main cause of mortality in developing and developed countries. Endothelial dysfunction, characterized by a decline in nitric oxide production and/or bioavailability, increased oxidative stress, decreased prostacyclin levels, and a reduction of endothelium-derived hyperpolarizing factor is considered an important prognostic indicator of various CVD. Changes in cyclic nucleotides production and/ or signalling, such as guanosine 3', 5'-monophosphate (cGMP) and adenosine 3', 5'-monophosphate (cAMP), also accompany many vascular disorders that course with altered endothelial function. Phosphodiesterases (PDE) are metallophosphohydrolases that catalyse cAMP and cGMP hydrolysis, thereby terminating the cyclic nucleotide-dependent signalling. The development of drugs that selectively block the activity of specific PDE families remains of great interest to the research, clinical and pharmaceutical industries. In the present review, we will discuss the effects of PDE inhibitors on CVD related to altered endothelial function, such as atherosclerosis, diabetes mellitus, arterial hypertension, stroke, aging and cirrhosis. Multiple evidences suggest that PDEs inhibition represents an attractive medical approach for the treatment of endothelial dysfunction-related diseases. Selective PDE inhibitors, especially PDE3 and PDE5 inhibitors are proposed to increase vascular NO levels by increasing antioxidant status or endothelial nitric oxide synthase expression and activation and to improve the morphological architecture of the endothelial surface. Thereby, selective PDE inhibitors can improve the endothelial function in various CVD, increasing the evidence that these drugs are potential treatment strategies for vascular dysfunction and reinforcing their potential role as an adjuvant in the pharmacotherapy of CVD.

Metformin regulates inflammation and fibrosis in diabetic kidney disease through TNC/TLR4/NF-κB/miR-155-5p inflammatory loop

BACKGROUND

Type 2 diabetes mellitus (T2DM) is significantly increasing worldwide, and the incidence of its complications is also on the rise. One of the main complications of T2DM is diabetic kidney disease (DKD). The glomerular filtration rate (GFR) and urinary albumin creatinine ratio (UACR) increase in the early stage. As the disease progresses, UACR continue to rise and GFR begins to decline until end-stage renal disease appears. At the same time, DKD will also increase the incidence and mortality of cardiovascular and cerebrovascular diseases. At present, the pathogenesis of DKD is not very clear. Therefore, exploration of the pathogenesis of DKD to find a treatment approach, so as to delay the development of DKD, is essential to improve the prognosis of DKD.

AIM

To detect the expression of tenascin-C (TNC) in the serum of T2DM patients, observe the content of TNC in the glomerulus of DKD rats, and detect the expression of TNC on inflammatory and fibrotic factors in rat mesangial cells (RMCs) cultured under high glucose condition, in order to explore the specific molecular mechanism of TNC in DKD and bring a new direction for the treatment of DKD.

METHODS

The expression level of TNC in the serum of diabetic patients was detected by enzyme-linked immunosorbent assay (ELISA), the protein expression level of TNC in the glomerular area of DKD rats was detected by immunohistochemistry, and the expression level of TNC in the rat serum was detected by ELISA. Rat glomerular mesangial cells were cultured. Following high glucose stimulation, the expression levels of related proteins and mRNA were detected by Western blot and polymerase chain reaction, respectively.

RESULTS

ELISA results revealed an increase in the serum TNC level in patients with T2DM. Increasing UACR and hypertension significantly increased the expression of TNC (P < 0.05). TNC expression was positively correlated with glycosylated haemoglobin (HbA1c) level, body mass index, systolic blood pressure, and UACR (P < 0.05). Immunohistochemical staining showed that TNC expression in the glomeruli of rats with streptozotocin-induced diabetes was significantly increased compared with normal controls (P < 0.05). Compared with normal rats, serum level of TNC in diabetic rats was significantly increased (P < 0.05), which was positively correlated with urea nitrogen and urinary creatinine (P < 0.05). The levels of TNC, Toll-like receptor-4 (TLR4), phosphorylated nuclear factor-κB p65 protein (Ser536) (p-NF-κB p65), and miR-155-5p were increased in RMCs treated with high glucose (P < 0.05). The level of TNC protein peaked 24 h after high glucose stimulation (P < 0.05). After TNC knockdown, the levels of TLR4, p-NF-κB p65, miR-155-5p, connective tissue growth factor (CTGF), and fibronectin (FN) were decreased, revealing that TNC regulated miR-155-5p expression through the TLR4/NF-κB p65 pathway, thereby regulating inflammation (NF-κB p65) and fibrosis (CTGF and FN) in individuals with DKD. In addition, metformin treatment may relive the processes of inflammation and fibrosis in individuals with DKD by reducing the levels of the TNC, p-NF-κB p65, CTGF, and FN proteins.

CONCLUSION

TNC can promote the occurrence and development of DKD. Interfering with the TNC/TLR4/NF-κB p65/miR-155-5p pathway may become a new target for DKD treatment.

Valsartan solid lipid nanoparticles integrated hydrogel: A challenging repurposed use in the treatment of diabetic foot ulcer, in-vitro/in-vivo experimental study

The article presents an experimental study on the possible repurposed use of valsartan (Val), in the local treatment of uncontrolled diabetic foot ulcer. Solid lipid nanoparticles (SLN), loaded with Val were prepared by applying 3² full factorial design using modified high shear homogenization method. The lipid phase composed of Precirol® ATO 5 (P ATO 5) and/or Gelucire 50/13 (G 50/13) in different ratios and a nonionic emulsifier, Pluronic 188 (P188), was used in different percentages. Optimized formulation was further integrated in hydroxyl propyl methyl cellulose (HPMC) gel for the ease of administration. In-vitro and in-vivo characterizations were investigated. The prepared nanoparticles showed small particle size, high entrapment efficiency and sustained drug release. Microbiologically, Val-SLN showed a prominent decrease in the biofilm mass formation for both gram-positive and gram-negative bacteria, as well as a comparable minimum inhibitory concentration level to levofloxacin alone. Diabetes was induced in 32 neonatal Sprague-Dawley rats. At 8 weeks of age, rats with blood sugar level >160 were subjected to surgically induced ulcer. Treatment with Val-SLN for 12 days revealed enhanced healing characteristics through cyclooxygenase-2 (COX-2), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), nitric oxide (NO), transforming growth factor-beta (TGF-β), matrix metalloproteinase (MMPs) and vascular endothelial growth factor (VEGF) pathways. Histological examination revealed re-epithelization in Val-SLN treated ulcer, as well as decrease in collagen using trichrome histomorphometric analysis.

Supraphysiological Levels of Testosterone Induce Vascular Dysfunction via Activation of the NLRP3 Inflammasome

Background: Both supraphysiological and subphysiological testosterone levels are associated with increased cardiovascular risk. Testosterone consumption at supraphysiological doses has been linked to increased blood pressure, left ventricular hypertrophy, vascular dysfunction, and increased levels of inflammatory markers. Activation of the NLRP3 inflammasome contributes to the production of proinflammatory cytokines, leading to cardiovascular dysfunction. We hypothesized that supraphysiological levels of testosterone, via generation of mitochondrial reactive oxygen species (mROS), activates the NLRP3 inflammasome and promotes vascular dysfunction. Methods: Male, 12 week-old C57Bl/6J (WT) and NLRP3 knockout (NLRP3-/-) mice were used. Mice were treated with testosterone propionate [TP (10 mg/kg) in vivo] or vehicle for 30 days. In addition, vessels were incubated with testosterone [Testo (10-6 M, 2 h) in vitro]. Testosterone levels, blood pressure, vascular function (thoracic aortic rings), pro-caspase-1/caspase-1 and interleukin-1β (IL-1β) expression, and generation of reactive oxygen species were determined. Results: Testosterone increased contractile responses and reduced endothelium-dependent vasodilation, both in vivo and in vitro. These effects were not observed in arteries from NLRP3-/- mice. Aortas of TP-treated WT mice (in vivo), as well as aortas from WT mice incubated with testo (in vitro), exhibited increased mROS levels and increased caspase-1 and IL-1β expression. These effects were not observed in arteries from NLRP3-/- mice. Flutamide [Flu, 10-5 M, androgen receptor (AR) antagonist], carbonyl cyanide m-chlorophenyl hydrazone (CCCP, 10-6 M, mitochondrial uncoupler) and MCC950 (MCC950, 10-6 M, a NLRP3 receptor inhibitor) prevented testosterone-induced mROS generation. Conclusion: Supraphysiological levels of testosterone induce vascular dysfunction via mROS generation and NLRP3 inflammasome activation. These events may contribute to increased cardiovascular risk.

Circular RNA 0001073 Attenuates Malignant Biological Behaviours in Breast Cancer Cell and Is Delivered by Nanoparticles to Inhibit Mice Tumour Growth

Background

Circular RNAs (circRNAs) are a special class of noncoding RNAs that are involved in gene regulation and compete with mRNA for miRNA binding sites. The roles of circRNAs in cancer, especially breast cancer (BC), are poorly understood.

Materials and Methods

The expression levels of circRNA 0001073 (circ-1073) in BC cells (BCCs) and tissues and peritumoural tissues were detected by real-time quantitative reverse transcription-polymerase chain reaction. Kaplan–Meier analysis and receiver operating characteristic curves were used to evaluate relapse-free survival (RFS) and the diagnostic value of circ-1073 for BC, respectively. The biological functions of circ-1073 were determined by cell counting kit-8 assays, colony formation assays, flow cytometry, wound-healing assays, transwell assays, and xenograft model studies. RNA immunoprecipitation assays were conducted to identify the connection between circ-1073 and human antigen R (HuR).

Results

Low circ-1073 expression was discovered in BCCs and BC tissues compared with normal mammary epithelial cells and peritumoural tissues, respectively. Circ-1073 downregulation was significantly associated with an unfavourable prognosis, including a shorter RFS, in BC patients. Circ-1073 is a valuable diagnostic biomarker for BC. Circ-1073 overexpression significantly inhibited BCC proliferation and induced apoptosis by increasing Cleaved Caspase-3/9 levels. Moreover, circ-1073 upregulation significantly suppressed cell mobility and epithelial–mesenchymal transition. Notably, xenograft tumour growth was inhibited by the intratumoural injection of nanoparticles containing the circ-1073 plasmid or by circ-1073 overexpression, and this inhibition was accompanied by HuR upregulation.

Conclusion

Circ-1073 functions as a tumour suppressor in BC, suggesting its potential as a novel therapeutic target in BC.

Both HuR and miR-29s regulate expression of CB1 involved in infiltration of bone marrow monocyte/macrophage in chronic liver injury

Bone marrow-derived monocytes/macrophages (BMMs) play a vital role in liver inflammation and fibrogenesis. Cannabinoid receptor 1 (CB1) mediates the recruitment of BMMs into the injured liver. In this study, we revealed the molecular mechanisms under CB1-mediated BMM infiltration. Carbon tetrachloride (CCl₄ ) was employed to induce mouse liver injury. In vivo, human antigen R (HuR) was upregulated in macrophages of injured liver. HuR messenger RNA (mRNA) expression was positively correlated with CB1 and F4/80 mRNA expression. Furthermore, we detected the binding between HuR and CB1 mRNA in CCl₄ -treated livers. In vitro, HuR modulated arachidonyl-2'-chloroethylamide (ACEA, CB1 agonist)-induced BMM migration by regulating CB1 expression. HuR promoted CB1 expression via binding to CB1 mRNA. ACEA promoted the association between HuR and CB1 mRNA via inducing HuR nucleoplasmic transport. In the cytoplasm, HuR competed with the miR-29 family to improve CB1 expression and BMM migration. In conclusion, our results prove that HuR regulates CB1 expression and influences ACEA-induced BMM migration by competing with miR-29 family.

Bradykinin and interleukin-1β synergistically increase the expression of cyclooxygenase-2 through the RNA-binding protein HuR in rat dorsal root ganglion cells

Synergistic expression of cyclooxygenase-2 (COX-2) by interleukin-1β (IL-1β) and bradykinin (BK) in peri-sensory neurons results in the production of prostanoids, which affects sensory neuronal activity and responsiveness and causes hyperalgesia. To evaluate the effects of pro-inflammatory mediators on COX-2 expression, cultured rat dorsal root ganglion (DRG) cells were treated with IL-1β and BK, which caused persistent increased COX-2 expression. Co-treatment increased COX-2 transcriptional activities in an additive manner by a COX-2 promoter luciferase assay. Immunoprecipitated HuR, an RNA-binding protein, in co-treated DRG cells contained more COX-2 mRNA than that of the control. The synergistic effects of IL-1β and BK on COX-2 expression may be a result of RNA stabilization mediated by HuR in peri-sensory neurons. Multiple pro-inflammatory cytokines and mediators are produced during neurogenic inflammation and aberrant control of COX-2 mRNA turnover may be implicated in diseases including chronic inflammation, which results in inflammation-derived hyperalgesia around primary sensory neurons.

FXR1 Is an IL-19-Responsive RNA-Binding Protein that Destabilizes Pro-inflammatory Transcripts in Vascular Smooth Muscle Cells

This work identifies the fragile-X-related protein (FXR1) as a reciprocal regulator of HuR target transcripts in vascular smooth muscle cells (VSMCs). FXR1 was identified as an HuR-interacting protein by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The HuR-FXR1 interaction is abrogated in RNase-treated extracts, indicating that their association is tethered by mRNAs. FXR1 expression is induced in diseased but not normal arteries. siRNA knockdown of FXR1 increases the abundance and stability of inflammatory mRNAs, while overexpression of FXR1 reduces their abundance and stability. Conditioned media from FXR1 siRNA-treated VSMCs enhance activation of naive VSMCs. RNA EMSA and RIP demonstrate that FXR1 interacts with an ARE and an element in the 3' UTR of TNFα. FXR1 expression is increased in VSMCs challenged with the anti-inflammatory cytokine IL-19, and FXR1 is required for IL-19 reduction of HuR. This suggests that FXR1 is an anti-inflammation responsive, HuR counter-regulatory protein that reduces abundance of pro-inflammatory transcripts.

mPGES-1 (Microsomal Prostaglandin E Synthase-1) Mediates Vascular Dysfunction in Hypertension Through Oxidative Stress

mPGES-1 (microsomal prostaglandin E synthase-1), the downstream enzyme responsible for PGE₂ (prostaglandin E₂) synthesis in inflammatory conditions and oxidative stress are increased in vessels from hypertensive animals. We evaluated the role of mPGES-1-derived PGE₂ in the vascular dysfunction and remodeling in hypertension and the possible contribution of oxidative stress. We used human peripheral blood mononuclear cells from asymptomatic patients, arteries from untreated and Ang II (angiotensin II)-infused mPGES-1^-/- and mPGES-1^+/+ mice, and vascular smooth muscle cells exposed to PGE₂ In human cells, we found a positive correlation between mPGES-1 mRNA and carotid intima-media thickness (r=0.637; P<0.001) and with NADPH oxidase-dependent superoxide production (r=0.417; P<0.001). In Ang II-infused mice, mPGES-1 deletion prevented all of the following: (1) the augmented wall:lumen ratio, vascular stiffness, and altered elastin structure; (2) the increased gene expression of profibrotic and proinflammatory markers; (3) the increased vasoconstrictor responses and endothelial dysfunction; (4) the increased NADPH oxidase activity and the diminished mitochondrial membrane potential; and (5) the increased reactive oxygen species generation and reduced NO bioavailability. In vascular smooth muscle cells or aortic segments, PGE₂ increased NADPH oxidase expression and activity and reduced mitochondrial membrane potential, effects that were abolished by antagonists of the PGE₂ receptors (EP), EP1 and EP3, and by JNK (c-Jun N-terminal kinase) and ERK1/2 (extracellular-signal-regulated kinases 1/2) inhibition. Deletion of mPGES-1 augmented vascular production of PGI₂ suggesting rediversion of the accumulated PGH₂ substrate. In conclusion, mPGES-1-derived PGE₂ is involved in vascular remodeling, stiffness, and endothelial dysfunction in hypertension likely through an increase of oxidative stress produced by NADPH oxidase and mitochondria.

Molecular functions and specific roles of circRNAs in the cardiovascular system

As part of the superfamily of long noncoding RNAs, circular RNAs (circRNAs) are emerging as a new type of regulatory molecules that partake in gene expression control. Here, we review the current knowledge about circRNAs in cardiovascular disease. CircRNAs are not only associated with different types of cardiovascular disease, but they have also been identified as intracellular effector molecules for pathophysiological changes in cardiovascular tissues, and as cardiovascular biomarkers. This evidence is put in the context of the current understanding of general circRNA biogenesis and of known interactions of circRNAs with DNA, RNA, and proteins.

Differential Effects of sEH Inhibitors on the Proliferation and Migration of Vascular Smooth Muscle Cells

Epoxyeicosatrienoic acid (EET) is a cardioprotective metabolite of arachidonic acid. It is known that soluble epoxide hydrolase (sEH) is involved in the metabolic degradation of EET. The abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) play important roles in the pathogenesis of atherosclerosis and restenosis. Thus, the present study investigated the effects of the sEH inhibitor 12-(((tricyclo(3.3.1.13,7)dec-1-ylamino)carbonyl)amino)-dodecanoic acid (AUDA) on platelet-derived growth factor (PDGF)-induced proliferation and migration in rat VSMCs. AUDA significantly inhibited PDGF-induced rat VSMC proliferation, which coincided with Pin1 suppression and heme oxygenase-1 (HO-1) upregulation. However, exogenous 8,9-EET, 11,12-EET, and 14,15-EET treatments did not alter Pin1 or HO-1 levels and had little effect on the proliferation of rat VSMCs. On the other hand, AUDA enhanced the PDGF-stimulated cell migration of rat VSMCs. Furthermore, AUDA-induced activation of cyclooxygenase-2 (COX-2) and subsequent thromboxane A2 (TXA₂) production were required for the enhanced migration. Additionally, EETs increased COX-2 expression but inhibited the migration of rat VSMCs. In conclusion, the present study showed that AUDA exerted differential effects on the proliferation and migration of PDGF-stimulated rat VSMCs and that these results may not depend on EET stabilization.

Decreased vasorelaxation induced by iloprost during acute inflammation in human internal mammary artery

Cyclooxygenase-2 (COX-2) induction in human internal mammary arteries (IMA) under inflammatory conditions has been associated with attenuated norepinephrine (NE)-induced vasoconstriction. This effect was associated with increased prostaglandin (PG) E₂ and prostacyclin (PGI₂) releases. The present study was designed to assess the role of these PG and their receptors (EP and IP, respectively) on the vascular reactivity during acute inflammation. Isolated IMA were cultured in the absence (Control conditions) or presence (Inflammatory conditions) of both interleukin-1 beta (IL-1β) and lipopolysaccharide (LPS). The vasorelaxation and the increased content of cyclic adenosine monophosphate (cAMP) induced by iloprost, a PGI₂ analogue, were significantly reduced under inflammatory conditions and restored in preparations cultured with the IP antagonist (CAY10441). Decreased cAMP levels under inflammatory conditions are due to at least increased phosphodiesterase (PDE) 4B expression. On the other hand, PGE₂, thromboxane analogues and EP agonists-induced vasoconstrictions were not affected under inflammatory conditions. No vasorelaxation was observed with PGD₂, PGE₂ or the EP2/4 agonists in pre-contracted IMA. Finally, using RT-qPCR and immunohistochemistry, the COX-2, IP receptor and PGI₂ synthase (PGIS) were detected. A significant increase of COX-2 and moderate increase of IP mRNA expression was observed under inflammatory conditions, whereas PGIS mRNA level was not affected. This study demonstrates that PGI₂/IP receptor signalling and PGI₂-induced relaxation are impaired in human IMA during acute inflammation, whereas the responses induced by other prostanoids are not affected. These results could explain some of the mechanisms of vascular dysfunction reported in inflammatory conditions.

NADPH oxidases and vascular remodeling in cardiovascular diseases

Reactive oxygen species (ROS) are key signaling molecules that regulate vascular function and structure in physiological conditions. A misbalance between the production and detoxification of ROS increases oxidative stress that is involved in the vascular remodeling associated with cardiovascular diseases such as hypertension by affecting inflammation, hypertrophy, migration, growth/apoptosis and extracellular matrix protein turnover. The major and more specific source of ROS in the cardiovascular system is the NADPH oxidase (NOX) family of enzymes composed of seven members (NOX1-5, DUOX 1/2). Vascular cells express several NOXs being NOX-1 and NOX-4 the most abundant NOXs present in vascular smooth muscle cells. This review focuses on specific aspects of NOX-1 and NOX-4 isoforms including information on regulation, function and their role in vascular remodeling. In order to obtain a more integrated view about the role of the different NOX isoforms in different types of vascular remodeling, we discuss the available literature not only on hypertension but also in atherosclerosis, restenosis and aortic dilation.

Augmented oxidative stress and preserved vasoconstriction induced by hydrogen peroxide in coronary arteries in obesity: role of COX-2

BACKGROUND AND PURPOSE

Oxidative stress plays a key role in the vascular and metabolic abnormalities associated with obesity. Herein, we assessed whether obesity can increase coronary vasoconstriction induced by hydrogen peroxide (H₂ O₂ ) and the signalling pathways involving COX-2 and superoxide (O₂^.- ) generation.

EXPERIMENTAL APPROACH

Contractile responses to H₂ O₂ and O₂^.- generation were measured in coronary arteries from genetically obese Zucker rats (OZR) and compared to lean Zucker rats (LZR).

KEY RESULTS

Both basal and H₂ O₂ -stimulated O₂^.- production were enhanced in coronary arteries from OZR, but H₂ O₂ -induced vasoconstriction was unchanged. The selective COX-2 inhibitor NS398 significantly reduced H₂ O₂ -induced contractions in endothelium-denuded arteries from LZR and OZR, but only in endothelium-intact arteries from LZR. PGI₂ (IP) receptor antagonism modestly reduced the vasoconstrictor action of H₂ O₂ while antagonism of the PGE₂ receptor 4 (EP₄ ) enhanced H₂ O₂ contractions in arteries from OZR but not LZR. Basal release of COX-2-derived PGE₂ was higher in coronary arteries from OZR where the selective agonist of EP₄ receptors TCS 2519 evoked potent relaxations. COX-2 was up-regulated after acute exposure to H₂ O₂ in coronary endothelium and vascular smooth muscle (VSM) and inhibition of COX-2 markedly reduced H₂ O₂ -elicited O₂^.- generation in coronary arteries and myocardium. Expression of Nox subunits in VSM and NADPH-stimulated O₂^.- generation was enhanced and contributed to H₂ O₂ vasoconstriction in arteries from obese rats.

CONCLUSION AND IMPLICATIONS

COX-2 contributes to cardiac oxidative stress and to the endothelium-independent O₂^.- -mediated coronary vasoconstriction induced by H₂ O₂ in obesity, which is offset by the release of COX-2-derived endothelial PGE₂ acting on EP₄ vasodilator receptors.

Hu antigen R is required for NOX-1 but not NOX-4 regulation by inflammatory stimuli in vascular smooth muscle cells

OBJECTIVE

NOX-1 and NOX-4 are key enzymes responsible for reactive oxygen species (ROS) generation in vascular smooth muscle cells (VSMC). The RNA-binding protein Hu antigen R (HuR) is implicated in posttranscriptional regulation of gene expression; however, its role regulating NOX is unknown. We investigated transcriptional and posttranscriptional mechanisms underlying angiotensin II (AngII) and IL-1β regulation of NOX-1 and NOX-4 in VSMC and their implications in cell migration.

METHODS

Rat and human VSMC were stimulated with AngII (0.1 μmol/l) and/or IL-1β (10 ng/ml). NOX-1 and NOX-4 mRNA and protein levels, NOX-1 and NOX-4 promoter and 3'UTR activities, NADPH oxidase activity, ROS production, and cell migration were studied.

RESULTS

IL-1β increased NOX-1 expression, NADPH oxidase activity and ROS production, and decreased NOX-4 expression and H2O2 production in VSMC. AngII potentiated the IL-1β-mediated induction of NOX-1 expression, NADPH oxidase activity, ROS production, and cell migration. However, AngII did not influence IL-1β-induced NOX-4 downregulation. AngII + IL-1β interfered with the decay of NOX-1 mRNA and promoted HuR binding to NOX-1 mRNA. Moreover, HuR blockade reduced NOX-1 mRNA stability and AngII + IL-1β-induced NOX-1 mRNA levels. IL-1β decreased NOX-4 expression through a transcriptional mechanism that involved response elements situated in the proximal promoter. AngII and/or IL-1β-induced cell migration were prevented by NOX-1 and HuR blockade and were augmented by NOX-4 overexpression.

CONCLUSION

In VSMC HuR-mediated mRNA stabilization is partially responsible for AngII + IL-1β-dependent NOX-1 expression, whereas transcriptional mechanisms are involved in decreased NOX-4 expression induced by IL-1β. NOX4 and HuR regulation of NOX-1 contributes to VSMC migration, important in vascular inflammation and remodeling.

Dual mechanisms of action of the RNA-binding protein human antigen R explains its regulatory effect on melanoma cell migration

Overexpression of wingless-type MMTV integration site family 5A (WNT5A) plays a significant role in melanoma cancer progression; however, the mechanism(s) involved remains unknown. In breast cancer, the human antigen R (HuR) has been implicated in the regulation of WNT5A expression. Here, we demonstrate that endogenous expression of WNT5A correlates with levels of active HuR in HTB63 and WM852 melanoma cells and that HuR binds to WNT5A messenger RNA in both cell lines. Although the HuR inhibitor MS-444 significantly impaired migration in both melanoma cell lines, it reduced WNT5A expression only in HTB63 cells, as did small interfering RNA knockdown of HuR. Consistent with this finding, MS-444-induced inhibition of HTB63 cell migration was restored by the addition of recombinant WNT5A, whereas MS-444-induced inhibition of WM852 cell migration was restored by the addition of recombinant matrix metalloproteinase-9, another HuR-regulated protein. Clearly, HuR positively regulates melanoma cell migration via at least 2 distinct mechanisms making HuR an attractive therapeutic target for halting melanoma dissemination.

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.