15-LO/15-HETE mediated vascular adventitia fibrosis via p38 MAPK-dependent TGF-β

Chromone-based small molecules for multistep shutdown of arachidonate pathway: Simultaneous inhibition of COX-2, 15-LOX and mPGES-1 enzymes

As a new approach to the management of inflammatory disorders, a series of chromone-based derivatives containing a (carbamate)hydrazone moiety was designed and synthesized. The compounds were assessed for their ability to inhibit COX-1/2, 15-LOX, and mPGES-1, as a combination that should effectively impede the arachidonate pathway. Results revealed that the benzylcarbazates (2a-c) demonstrated two-digit nanomolar COX-2 inhibitory activities with reasonable selectivity indices. They also showed appreciable 15-LOX inhibition, in comparison to quercetin. Further testing of these compounds for mPGES-1 inhibition displayed promising activities. Intriguingly, compounds 2a-c were capable of suppressing edema in the formalin-induced rat paw edema assay. They exhibited an acceptable gastrointestinal safety profile regarding ulcerogenic liabilities in gross and histopathological examinations. Additionally, upon treatment with the test compounds, the expression of the anti-inflammatory cytokine IL-10 was elevated, whereas that of TNF-α, iNOS, IL-1β, and COX-2 were downregulated in LPS-challenged RAW264.7 macrophages. Docking experiments into the three enzymes showed interesting binding profiles and affinities, further substantiating their biological activities. Their in silico physicochemical and pharmacokinetic parameters were advantageous.

Pathophysiological Involvement of Mast Cells and the Lipid Mediators in Pulmonary Vascular Remodeling

Mast cells are responsible for IgE-dependent allergic responses, but they also produce various bioactive mediators and contribute to the pathogenesis of various cardiovascular diseases, including pulmonary hypertension (PH). The importance of lipid mediators in the pathogenesis of PH has become evident in recent years, as exemplified by prostaglandin I2, the most central therapeutic target in pulmonary arterial hypertension. New bioactive lipids other than eicosanoids have also been identified that are associated with the pathogenesis of PH. However, it remains largely unknown how mast cell-derived lipid mediators are involved in pulmonary vascular remodeling. Recently, it has been demonstrated that mast cells produce epoxidized n-3 fatty acid (n-3 epoxides) in a degranulation-independent manner, and that n-3 epoxides produced by mast cells regulate the abnormal activation of pulmonary fibroblasts and suppress the progression of pulmonary vascular remodeling. This review summarizes the role of mast cells and bioactive lipids in the pathogenesis of PH. In addition, we introduce the pathophysiological role and therapeutic potential of n-3 epoxides, a mast cell-derived novel lipid mediator, in the pulmonary vascular remodeling in PH. Further knowledge of mast cells and lipid mediators is expected to lead to the development of innovative therapies targeting pulmonary vascular remodeling.

Circ-Ntrk2 acts as a miR-296-5p sponge to activate the TGF-β1/p38 MAPK pathway and promote pulmonary hypertension and vascular remodelling

BACKGROUND

Circular RNAs (circRNAs), a novel class of non-coding RNAs, play an important regulatory role in pulmonary arterial hypertension (PAH); however, the specific mechanism is rarely studied. In this study, we aimed to discover functional circRNAs and investigate their effects and mechanisms in hypoxia-induced pulmonary vascular remodelling, a core pathological change in PAH.

METHODS

RNA sequencing was used to illustrate the expression profile of circRNAs in hypoxic PAH. Bioinformatics, Sanger sequencing, and quantitative real-time PCR were used to identify the ring-forming characteristics of RNA and analyse its expression. Then, we established a hypoxia-induced PAH mouse model to evaluate circRNA function in PAH by echocardiography and hemodynamic measurements. Moreover, microRNA target gene database screening, fluorescence in situ hybridisation, luciferase reporter gene detection, and western blotting were used to explore the mechanism of circRNAs.

RESULTS

RNA sequencing identified 432 differentially expressed circRNAs in mouse hypoxic lung tissues. Our results indicated that circ-Ntrk2 is a stable cytoplasmic circRNA derived from Ntrk2 mRNA and frequently upregulated in hypoxic lung tissue. We further found that circ-Ntrk2 sponges miR-296-5p and miR-296-5p can bind to the 3'-untranslated region of transforming growth factor-β1 (TGF-β1) mRNA, thereby attenuating TGF-β1 translation. Through gene knockout or exogenous expression, we demonstrated that circ-Ntrk2 could promote PAH and vascular remodelling. Moreover, we verified that miR-296-5p overexpression alleviated pulmonary vascular remodelling and improved PAH through the TGF-β1/p38 MAPK pathway.

CONCLUSIONS

We identified a new circRNA (circ-Ntrk2) and explored its function and mechanism in PAH, thereby establishing potential targets for the diagnosis and treatment of PAH. Furthermore, our study contributes to the understanding of circRNA in relation to PAH.

Neferine ameliorates hypertensive vascular remodeling modulating multiple signaling pathways in spontaneously hypertensive rats

BACKGROUND

Neferine exhibits therapeutic effects on anti-hypertension. However, the effect of neferine on hypertensive vascular remodeling remains unexplored. Therefore, the current study was to investigate the effect of neferine on hypertensive vascular remodeling and its underlying mechanisms.

METHODS

Total 30 male spontaneously hypertensive rats (SHRs) were divided randomly into five groups, including SHR, Neferine-L (2.5 mg/kg/day), Neferine-M (5 mg/kg/day), Neferine-H (10 mg/kg/day), and Valsartan (10 mg/kg/day) groups (n = 6 for each group). Wistar Kyoto (WKY) rats were set as control group (n = 6). Noninvasive blood pressure system, ultrasound, hematoxylin and eosin staining, masson trichrome staining were used to detect the blood pressure, pulse wave velocity (PWV), pathological changes and collagen content in abdominal aortas of SHRs. RNA-sequencing and immunohistochemistry(IHC) analyses were used to identify and verify the differentially expressed transcripts and activation of associated signaling pathways in SHRs.

RESULTS

Various concentrations of neferine or valsartan treatment substantially reduced the elevation of blood pressure, PWV, and abdominal aortic thickening of SHRs. RNA-sequencing and KEGG analyses recognized 441 differentially expressed transcripts and several enriched pathways (including PI3K/AKT and TGF-β/Smad2/3 signaling pathways) after neferine treatment. Masson trichromatic staining and IHC analysis demonstrated that neferine treatment decreased the collagen content and down-regulated the protein expression of PCNA, collagen I & III, and fibronectin, as well as p-PI3K, p-AKT, TGF-β1 and p-Smad2/3 in abdominal aortic tissues of SHRs.

CONCLUSION

Neferine treatment exhibits therapeutic effects on anti-hypertension and reduces vascular remodeling, as well as suppresses the abnormal activation of multiple signaling pathways, including PI3K/AKT and TGF-β1/Smad2/3 pathways.

Effect of inflammation on cytochrome P450-mediated arachidonic acid metabolism and the consequences on cardiac hypertrophy

The incidence of heart failure (HF) is generally preceded by cardiac hypertrophy (CH), which is the enlargement of cardiac myocytes in response to stress. During CH, the metabolism of arachidonic acid (AA), which is present in the cell membrane phospholipids, is modulated. Metabolism of AA gives rise to hydroxyeicosatetraenoic acids (HETEs) and epoxyeicosatrienoic acids (EETs) via cytochrome P450 (CYP) ω-hydroxylases and CYP epoxygenases, respectively. A plethora of studies demonstrated the involvement of CYP-mediated AA metabolites in the pathogenesis of CH. Also, inflammation is known to be a characteristic hallmark of CH. In this review, our aim is to highlight the impact of inflammation on CYP-derived AA metabolites and CH. Inflammation is shown to modulate the expression of various CYP ω-hydroxylases and CYP epoxygenases and their respective metabolites in the heart. In general, HETEs such as 20-HETE and mid-chain HETEs are pro-inflammatory, while EETs are characterized by their anti-inflammatory and cardioprotective properties. Several mechanisms are implicated in inflammation-induced CH, including the modulation of NF-κB and MAPK. This review demonstrated the inflammatory modulation of cardiac CYPs and their metabolites in the context of CH and the anti-inflammatory strategies that can be employed in the treatment of CH and HF.

Cysteine and glycine rich protein 2 exacerbates vascular fibrosis in pulmonary hypertension through the nuclear translocation of yes-associated protein and transcriptional coactivator with PDZ-binding motif

Pulmonary hypertension (PH) is a serious cardiovascular disease with a poor prognosis and high mortality. The pathogenesis of PH is complex, and the main pathological changes in PH are abnormal hypertrophy and vessel stiffness. Cysteine and glycine rich protein 2 (Csrp2), a member of the LIM-only family plays a key role in the response to vascular injury. However, its roles in vascular fibrosis and PH have not been clarified. Therefore, this study aimed to investigate whether Csrp2 can promote vascular fibrosis and to further explore the possible mechanisms. Csrp2 expression was increased in both the pulmonary vasculature of rats with PH and hypoxic pulmonary vascular smooth muscle cells (PASMCs). Hypoxia activated TGF-β1 and its downstream effector, SP1. Additionally, hypoxia activated the ROCK pathway and inhibited KLF4 expression. Silencing SP1 and overexpressing KLF4 reversed the hypoxia-induced increase in Csrp2 expression. Csrp2 knockdown decreased the expression of extracellular matrix (ECM) proteins and inhibited the nuclear translocation and expression of YAP/TAZ in hypoxic PASMCs. These results indicate that hypoxia induces Csrp2 expression through the TGF-β1/SP1 and ROCK/KLF4 pathways. Elevated Csrp2 promoted the nuclear translocation and expression of YAP/TAZ, leading to vascular fibrosis and the development of PH.

Supplementation with Tex261 provides a possible preventive treatment for hypoxic pulmonary artery hypertension

Objectives: Pulmonary artery hypertension (PAH) is a serious disease for which there is no effective treatment. Its pathogenesis is complex and has not yet been clarified. Tex261 is a protein-coding gene whose functional enrichment nodes include the transporter activity of COP II. However, the role of Tex261 in PAH remains unknown. Methods: Sugen5416/Hypoxic PAH models were established, and pulmonary arteries (PAs) were isolated for proteomic sequencing. The binding sites between Hif-1α and Tex261 were verified by dual-luciferase reporter gene assay. Cell proliferation was detected by MTS and EdU assays. For determination of the preventive and therapeutic effects of Tex261, intratracheal instillation of adeno-associated virus (AVV6) with Tex261 vectors was performed. Results: Tex261 was screened according to the proteomic sequencing data. Hif-1α inhibited Tex261 promoter activity under hypoxia. Decreased Tex261 expression promoted PASMC proliferation. Tex261 regulated Sec23 via the Ndrg1-mediated Akt pathway. Tex261 overexpression improved the pressure and vessel remodeling of PAs induced by Sugen5416/hypoxia. Conclusion: Hypoxia suppressed Tex261 expression through Hif-1α activation. The decreased Tex261 could promote Ndrg1 and depress Akt activity and then inhibit Sec23 activity, which leads to cell proliferation and vessel remodeling. Elevated Tex261 has some preventive and therapeutic effects on rats with PAH.

An Overview of Circulating Pulmonary Arterial Hypertension Biomarkers

Pulmonary arterial hypertension (PAH), also known as Group 1 Pulmonary Hypertension (PH), is a PH subset characterized by pulmonary vascular remodeling and pulmonary arterial obstruction. PAH has an estimated incidence of 15-50 people per million in the United States and Europe, and is associated with high mortality and morbidity, with patients' survival time after diagnosis being only 2.8 years. According to current guidelines, right heart catheterization is the gold standard for diagnostic and prognostic evaluation of PAH patients. However, this technique is highly invasive, so it is not used in routine clinical practice or patient follow-up. Thereby, it is essential to find new non-invasive strategies for evaluating disease progression. Biomarkers can be an effective solution for determining PAH patient prognosis and response to therapy, and aiding in diagnostic efforts, so long as their detection is non-invasive, easy, and objective. This review aims to clarify and describe some of the potential new candidates as circulating biomarkers of PAH.

Challenging inflammatory process at molecular, cellular and in vivo levels via some new pyrazolyl thiazolones

The work reported herein describes the synthesis of a new series of anti-inflammatory pyrazolyl thiazolones. In addition to COX-2/15-LOX inhibition, these hybrids exerted their anti-inflammatory actions through novel mechanisms. The most active compounds possessed COX-2 inhibitory activities comparable to celecoxib (IC₅₀ values of 0.09-0.14 µM) with significant 15-LOX inhibitory activities (IC₅₀s 1.96 to 3.52 µM). Upon investigation of their in vivo anti-inflammatory activities and ulcerogenic profiles, these compounds showed activity patterns equivalent or more superior to diclofenac and/or celecoxib. Intriguingly, the most active compounds were more effective than diclofenac in suppressing monocyte-to-macrophage differentiation and inflammatory cytokine production by activated macrophages, as well as their ability to induce macrophage apoptosis. The latter finding potentially adds a new dimension to the previously reported anti-inflammatory mechanisms of similar compounds. These compounds were effectively docked into COX-2 and 15-LOX active sites. Also, in silico predictions confirmed the appropriateness of these compounds as drug-like candidates.

The lncRNA PAHRF functions as a competing endogenous RNA to regulate MST1 expression by sponging miR-23a-3p in pulmonary arterial hypertension

BACKGROUND

Emerging evidence has shown that long non-coding RNA (lncRNA) plays important roles in the development of pulmonary arterial hypertension (PAH). However, some new lncRNAs in patients with PAH are still lacking research. Herein, we examined the expression and role of lncRNA (pulmonary arterial hypertension related factor, PAHRF) in PAH.

METHODS

LncRNA PAHRF expression and localization were analyzed by realtime PCR and fluorescence in situ hybridization. Proliferation and apoptosis were detected by MTT, CCK-8, EDU staining, JC-1 assay, flow cytometry and western blotting. Luciferase activity assay was used to identify PAHRF/ miR-23a-3p/serine/threonine kinase 4 (STK4/MST1) interaction.

RESULTS

LncRNA PAHRF was down-regulated in both the PAs of PAH patients and hypoxic human pulmonary artery smooth muscle cells (PASMCs). The overexpression of PAHRF inhibited the proliferation and promoted the apoptosis of PASMCs. Similarly, we also found PAHRF overexpression decreased the proliferation under hypoxia condition. Knockdown of PAHRF exerted the opposite effects. Luciferase activity assay proved molecular binding between PAHRF and hsa-miR-23a-3p. Moreover, MST1 was confirmed to be the putative target gene and regulated by PAHRF/miR-23a-3p. In addition, we explored the molecular mechanism regulating the expression of miR-23a-3p, and found that lncRNA PAHRF acted as an endogenous sponge for miR-23a-3p, and silencing lncRNA PAHRF could up-regulate the expression of miR-23a-3p. On the contrary, PAHRF-overexpressing plasmid inhibited the expression of miR-23a-3p in hypoxia.

CONCLUSIONS

Our present study reveals a novel PAH regulating model that is composed of PAHRF, miR-23a-3p, and MST1. The aim of this study is probably going to provide a new explanation and give a further understanding of the occurrence of vascular remodeling in PAH from the perspective competing endogenous RNA hypothesis.

Hypoxia-induced retinal pigment epithelium cell-derived bFGF promotes the migration and angiogenesis of HUVECs through regulating TGF-β1/smad2/3 pathway

Hypoxia promotes the secretion of basic fibroblast growth factor (bFGF) in retinal pigment epithelium (RPE), which plays an important part in retinopathy of prematurity (ROP). This study preliminarily explored the effect of hypoxia-induced RPE-derived bFGF on the biological functions of human umbilical vein endothelial cells (HUVECs). After cell culture in hypoxia conditions, the cell viability, apoptosis, and the expressions of bFGF and vascular endothelial growth factor A (VEGFA) in human RPEs were detected by 3-(4, 5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), flow cytometry, western blot, RT-qPCR, or ELISA. The HUVECs were transfected with siRNA for bFGF (sibFGF) or transforming growth factor-β1 (TGF-β1) (siTGF-β1) and grown in the supernatant RPE under normoxia conditions or hypoxia conditions to further determine the cell viability, migration, angiogenesis, and the expressions of TGF-β1, p-smad2/3, and smad2/3 in the cells by performing MTT, transwell, tube formation, Western blot, or RT-qPCR. Hypoxia culture decreased the cell viability and promoted the apoptosis as well as the expressions of bFGF and VEGFA in RPEs. In both normoxia and hypoxia conditions, RPE-derived bFGF increased the cell viability, migration, angiogenesis, and the expressions of TGF-β1 and p-smad2/3 in the HUVECs, with hypoxia-induced RPE-derived bFGF showing a stronger effect than bFGF induced by normoxia. However, sibFGF reversed the effects caused by RPE-derived bFGF. Moreover, siTGF-β1 decreased the high cell viability, migration and angiogenesis of HUVECs, and downregulated the expressions of TGF-β1 and phosphorylated (p)-smad2/3 upregulated by hypoxia-induced RPE-derived bFGF. Hypoxia-induced RPE-derived bFGF could promote the migration and angiogenesis of HUVECs through regulating TGF-β1/smad2/3 pathway.

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

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

Oral 15-Hydroxyeicosatetraenoic Acid Induces Pulmonary Hypertension in Mice by Triggering T Cell-Dependent Endothelial Cell Apoptosis

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by increased mean pulmonary arterial pressure. Elevated plasma and lung concentrations of oxidized lipids, including 15-hydroxyeicosatetraenoic acid (15-HETE), have been demonstrated in patients with PAH and animal models. We previously demonstrated that feeding mice with 15-HETE is sufficient to induce pulmonary hypertension, but the mechanisms remain unknown. RNA sequencing data from the mouse lungs on 15-HETE diet revealed significant activation of pathways involved in both antigen processing and presentation and T cell-mediated cytotoxicity. Analysis of human microarray from patients with PAH also identified activation of identical pathways compared with controls. We show that in both 15-HETE-fed mice and patients with PAH, expression of the immunoproteasome subunit 5 is significantly increased, which was concomitant with an increase in the number of CD8/CD69 (cluster of differentiation 8 / cluster of differentiation 69) double-positive cells, as well as pulmonary arterial endothelial cell apoptosis in mice. Human pulmonary arterial endothelial cells cultured with 15-HETE were more prone to apoptosis when exposed to CD8 cells. Cultured intestinal epithelial cells secreted more oxidized lipids in response to 15-HETE, which is consistent with accumulation of circulating oxidized lipids in 15-HETE-fed mice. Administration of an apoA-I (apolipoprotein A-I) mimetic peptide, Tg6F (transgenic 6F), which is known to prevent accumulation of circulating oxidized lipids, not only inhibited pulmonary arterial endothelial cell apoptosis but also prevented and rescued 15-HETE-induced pulmonary hypertension in mice. In conclusion, our results suggest that (1) 15-HETE diet induces pulmonary hypertension by a mechanism that involves oxidized lipid-mediated T cell-dependent pulmonary arterial endothelial cell apoptosis and (2) Tg6F administration may be a novel therapy for treating PAH.

Resveratrol attenuates angiotensin II-induced cellular hypertrophy through the inhibition of CYP1B1 and the cardiotoxic mid-chain HETE metabolites

Several reports demonstrated the direct contribution of cytochrome P450 1B1 (CYP1B1) enzyme and its associated cardiotoxic mid-chain, hydroxyeicosatetraenoic acid (HETEs) metabolites in the development of cardiac hypertrophy. Resveratrol is commercially available polyphenol that exerts beneficial effects in wide array of cardiovascular diseases including cardiac hypertrophy, myocardial infarction and heart failure. Nevertheless, the underlying mechanisms responsible for these effects are not fully elucidated. Since resveratrol is a well-known CYP1B1 inhibitor, the purpose of this study is to test whether resveratrol attenuates angiotensin II (Ang II)-induced cellular hypertrophy through inhibition of CYP1B1/mid-chain HETEs mechanism. RL-14 and H9c2 cells were treated with vehicle or 10 μM Ang II in the absence and presence of 2, 10 or 50 μM resveratrol for 24 h. Thereafter, the level of mid-chain HETEs was determined using liquid chromatography–mass spectrometry (LC/MS). Hypertrophic markers and CYP1B1 gene expression and protein levels were measured using real-time PCR and Western blot analysis, respectively. Our results demonstrated that resveratrol, at concentrations of 10 and 50 μM, was able to attenuate Ang-II-induced cellular hypertrophy as evidenced by substantial inhibition of hypertrophic markers, β-myosin heavy chain (MHC)/α-MHC and atrial natriuretic peptide. Ang II significantly induced the protein expression of CYP1B1 and increased the metabolite formation rate of its associated mid-chain HETEs. Interestingly, the protective effect of resveratrol was associated with a significant decrease of CYP1B1 protein expression and mid-chain HETEs. Our results provided the first evidence that resveratrol protects against Ang II-induced cellular hypertrophy, at least in part, through CYP1B1/mid-chain HETEs-dependent mechanism.

Quantification of uncertainty in a new network model of pulmonary arterial adventitial fibroblast pro-fibrotic signalling

Here, we present a novel network model of the pulmonary arterial adventitial fibroblast (PAAF) that represents seven signalling pathways, confirmed to be important in pulmonary arterial fibrosis, as 92 reactions and 64 state variables. Without optimizing parameters, the model correctly predicted 80% of 39 results of input-output and inhibition experiments reported in 20 independent papers not used to formulate the original network. Parameter uncertainty quantification (UQ) showed that this measure of model accuracy is robust to changes in input weights and half-maximal activation levels (EC50), but is more affected by uncertainty in the Hill coefficient (n), which governs the biochemical cooperativity or steepness of the sigmoidal activation function of each state variable. Epistemic uncertainty in model structure, due to the reliance of some network components and interactions on experiments using non-PAAF cell types, suggested that this source of uncertainty had a smaller impact on model accuracy than the alternative of reducing the network to only those interactions reported in PAAFs. UQ highlighted model parameters that can be optimized to improve prediction accuracy and network modules where there is the greatest need for new experiments. This article is part of the theme issue 'Uncertainty quantification in cardiac and cardiovascular modelling and simulation'.

Pulmonary Arterial Stiffness: An Early and Pervasive Driver of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a historically neglected and highly morbid vascular disease that leads to right heart failure and, in some cases, death. The molecular origins of this disease have been poorly defined, and as such, current pulmonary vasodilator therapies do not cure or reverse this disease. Although extracellular matrix (ECM) remodeling and pulmonary arterial stiffening have long been associated with end-stage PAH, recent studies have reported that such vascular stiffening can occur early in pathogenesis. Furthermore, there is emerging evidence that ECM stiffening may represent a key first step in pathogenic reprogramming and molecular crosstalk among endothelial, smooth muscle, and fibroblast cells in the remodeled pulmonary vessel. Such processes represent the convergence of activation of a number of specific mechanoactivated signaling pathways, microRNAs, and metabolic pathways in pulmonary vasculature. In this review, we summarize the contemporary understanding of vascular stiffening as a driver of PAH, its mechanisms, potential therapeutic targets and clinical perspectives. Of note, early intervention targeting arterial stiffness may break the vicious cycle of PAH progression, leading to outcome improvement which has not been demonstrated by current vasodilator therapy.

Inhibition of Arachidonate 12/15-Lipoxygenase Improves α-Galactosidase Efficacy in iPSC-Derived Cardiomyocytes from Fabry Patients

(1) Background: A high incidence of intervening sequence (IVS)4+919 G>A mutation with later-onset cardiac phenotype have been reported in a majority of Taiwan Fabry cohorts. Some evidence indicated that conventional biomarkers failed to predict the long-term progression and therapeutic outcome; (2) Methods: In this study, we constructed an induced pluripotent stem cell (iPSC)-based platform from Fabry cardiomyopathy (FC) patients carrying IVS4+919 G>A mutation to screen for potential targets that may help the conventional treatment; (3) Results: The FC-patient-derived iPSC-differentiated cardiomyocytes (FC-iPSC-CMs) carried an expected IVS4+919 G>A genetic mutation and recapitulated several FC characteristics, including low α-galactosidase A enzyme activity and cellular hypertrophy. The proteomic analysis revealed that arachidonate 12/15-lipoxygenase (Alox12/15) was the most highly upregulated marker in FC-iPSC-CMs, and the metabolites of Alox12/15, 12(S)- and 15(S)-hydroxyeicosatetraenoic acid (HETE), were also elevated in the culture media. Late administration of Alox12/15 pharmacological inhibitor LOXBlock-1 combined with α-galactosidase, but not α-galactosidase alone, effectively reduced cardiomyocyte hypertrophy, the secretion of 12(S)- and 15(S)-HETE and the upregulation of fibrotic markers at the late phase of FC; (4) Conclusions: Our study demonstrates that cardiac Alox12/15 and circulating 12(S)-HETE/15(S)-HETE are involved in the pathogenesis of FC with IVS4+919 G>A mutation.

Post‑translational modification of CREB‑1 decreases collagen I expression by inhibiting the TGF‑β1 signaling pathway in rat hepatic stellate cells

Liver fibrosis is a reversible wound‑healing response to liver damage. Following liver injury, activated hepatic stellate cells (HSCs) cause excessive deposition of collagen and other components of the extracellular matrix, which may eventually impair liver function. Transforming growth factor‑β1 (TGF‑β1) is critical for the development of liver fibrosis, and acts by activating HSCs, stimulating matrix deposition and inducing other profibrotic responses. Certain studies have demonstrated that the transcription factor, cyclic adenosine monophosphate (cAMP)‑response element binding protein‑1 (CREB‑1) is important in the inhibition of fibrosis; however, the underlying mechanism remains to be elucidated. The present study hypothesized that CREB‑1 inhibits fibrosis via blocking the TGF‑β1 signaling pathway in HSCs. Treatment with the cAMP‑elevating agent, forskolin stimulated CREB‑1 phosphorylation and transcription activation in HSCs. In addition, treatment with the histone deacetylase inhibitor, trichostatin A extended CREB‑1 phosphorylation. The present study used a pRSV‑CREB‑1 expression vector to upregulate CREB‑1 gene expression. The results indicated that activated CREB‑1 reduced TGF‑β1‑stimulated expression of collagen I, activated Smad2/3 and upregulated expression of Smad7. In addition, activated CREB‑1 attenuated the activation of extracellular signal‑regulated kinase 1/2 induced by TGF‑β1, expression of Ras homolog gene family, member A (RhoA) and Rho‑associated coiled‑coil containing protein kinase 1. Thus, post‑translational modification of CREB‑1 inhibited the profibrotic effects of TGF‑β1 in HSCs via Smad‑dependent and ‑independent signaling pathways.

Elk-1-mediated 15-lipoxygenase expression is required for hypoxia-induced pulmonary vascular adventitial fibroblast dynamics

AIM

15-Lipoxygenase (15-LO) is an important factor in the pathogenesis of pulmonary artery hypertension (PAH). However, the role of 15-LO in the adventitia of the pulmonary arterial wall is unclear. The aim of this study was to explore the role of 15-LO in the modulation of pulmonary adventitial fibroblast (PAF) dynamics.

METHODS

Rats were exposed to normoxic or hypoxic (fraction of inspired O₂  = 0.12) treatments for 7 days. PAF proliferation and cell cycle alterations were measured by MTT assay, cell immunofluorescence, flow cytometry and Western blot analysis. The 15-LO promoter was analysed by luciferase reporter and ChIP assays.

RESULTS

Our results showed that hypoxia induced 15-LO expression in PAFs both in vivo and in vitro. In addition, hypoxia stimulated JNK phosphorylation in PAFs. Blocking 15-LO or JNK suppressed 15-LO-induced PAF proliferation and cell cycle alterations. The inhibition of p27^kipl by gene silencing attenuated 15-LO-induced PAF proliferation and cell cycle alterations. Furthermore, JNK inhibition or Elk-1 knockdown suppressed hypoxia-induced 15-LO expression in PAFs. Luciferase reporter and ChIP assays revealed that the 15-LO promoter contains Elk-1-binding sites and also that Elk-1 increased the hypoxia-induced activity of the 15-LO promoter.

CONCLUSION

These results suggest that hypoxia promotes changes in the cellular dynamics of PAFs by inducing 15-LO expression, which leads to vascular adventitial remodelling. The modulation of p27^kipl expression by 15-LO enhances PAF proliferation and cell cycle alterations. Furthermore, the JNK-dependent increase in Elk-1 signalling is required for hypoxia-induced 15-LO expression in PAFs.

Galectin-3 contributes to vascular fibrosis in monocrotaline-induced pulmonary arterial hypertension rat model

Galectin-3 (Gal-3) plays a critical role in vascular inflammation and fibrosis. The role of TGF-β1 in mediating pulmonary vascular fibrosis is well documented; thus, we suspected that Gal-3 could be an important factor in TGF-β1-induced fibrosis in pulmonary adventitial fibroblasts (PAFs). We treated rats with monocrotaline (MCT) and cultured PAFs with TGF-β1 to stimulate fibrosis. We found that MCT injection induced vessel thickening and extracellular matrix deposition in vivo. TGF-β1 stimulated the production of collagen and fibronectin (Fn) protein in vitro. TGF-β1 promoted the expression of Gal-3 and its translocation, while silencing Gal-3 reduced Col-1a deposition. Blockage of STAT3 decreased the expression of Gal-3 induced by TGF-β1. Gal-3 increased Col-1a accumulation and downregulated matrix metallopeptidase 9 (MMP-9) expression in PAFs, but it did not affect Fn expression. These findings demonstrate that Gal-3 is required for TGF-β1-stimulated vascular fibrosis via a STAT3 signaling cascade and that MMP-9 is also involved in TGF-β1/Gal-3-induced vascular fibrosis.

Role of oxidized lipids in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a multifactorial disease characterized by interplay of many cellular, molecular, and genetic events that lead to excessive proliferation of pulmonary cells, including smooth muscle and endothelial cells; inflammation; and extracellular matrix remodeling. Abnormal vascular changes and structural remodeling associated with PAH culminate in vasoconstriction and obstruction of pulmonary arteries, contributing to increased pulmonary vascular resistance, pulmonary hypertension, and right ventricular failure. The complex molecular mechanisms involved in the pathobiology of PAH are the limiting factors in the development of potential therapeutic interventions for PAH. Over the years, our group and others have demonstrated the critical implication of lipids in the pathogenesis of PAH. This review specifically focuses on the current understanding of the role of oxidized lipids, lipid metabolism, peroxidation, and oxidative stress in the progression of PAH. This review also discusses the relevance of apolipoprotein A-I mimetic peptides and microRNA-193, which are known to regulate the levels of oxidized lipids, as potential therapeutics in PAH.

Lentil consumption reduces resistance artery remodeling and restores arterial compliance in the spontaneously hypertensive rats

We previously established that lentils were able to significantly attenuate the development of hypertension in spontaneously hypertensive rats (SHRs), but the mechanism was not investigated. The current study was therefore designed to examine the effect of lentils on arterial function in relation to arterial stiffness, lipid biochemistry and activation of select aortic proteins. Seventeen-week-old male SHRs were randomly assigned to groups (n=10/group) fed (a) 30% w/w green lentils, (b) 30% red lentils, (c) 30% mixed lentils (red and green) or (d) no lentils for 8 weeks. Normotensive Wistar Kyoto (WKY) groups (n=10/group) received either the mixed lentil or no lentil diet. Blood pressure, pulse wave velocity and serum lipids were measured at baseline and 8 weeks, while pressure myography, arterial morphology and aortic proteins were measured after termination. There were no dietary-related changes in pulse wave velocity or blood pressure for any SHR or WKY group. Low-density lipoprotein cholesterol and high-density lipoprotein cholesterol were significantly lower in only SHR red lentil and WKY mixed lentil groups compared to their controls. The lentil diets reduced the media:lumen ratio of SHRs relative to control-fed SHRs but had no effect on WKYs. Both red and green lentils reduced arterial stiffness of SHRs but not WKYs. SHR lentil groups showed lower aortic p38 mitogen-activated protein kinase (p38MAPK) phosphorylation, thus implying that p38MAPK activation is suppressed with lentil feeding. Lentil-based diets suppress pathological vascular remodeling in SHRs, while green lentils maintain the vascular function of SHRs similar to normotensive WKYs despite the presence of high blood pressure.

Protease-activated receptor 1 and 2 contribute to angiotensin II-induced activation of adventitial fibroblasts from rat aorta

Adventitial fibroblasts (AFs) can be activated by angiotensin II (Ang II) and exert pro-fibrotic and pro-inflammatory effects in vascular remodeling. Protease-activated receptor (PAR) 1 and 2 play a significant role in fibrogenic and inflammatory diseases. The present study hypothesized that PAR1 and PAR2 are involved in Ang II-induced AF activation and contribute to adventitial remodeling. We found that direct activation of PAR1 and PAR2 with PAR1-AP and PAR2-AP led to AF activation, including proliferation and differentiation of AFs, extracellular matrix synthesis, as well as production of pro-fibrotic cytokine TGF-β and pro-inflammatory cytokines IL-6 and MCP-1. Furthermore, PAR1 and PAR2 mediated Ang II-induced AF activation, since both PAR1 and PAR2 antagonists inhibited Ang II-induced proliferation, migration, differentiation, extracellular matrix synthesis and production of pro-fibrotic and pro-inflammatory cytokines in AFs. Finally, mechanistic study showed that Ang II, via Ang II type I receptor (AT1R), upregulated both PAR1 and PAR2 expression, and transactivated PAR1 and PAR2, as denoted by internalization of both proteins. In conclusion, our results suggest that PAR1 and PAR2 play a critical role in Ang II-induced AF activation, and this may contribute to adventitia-related pathological changes.

TGF-β1/FGF-2 signaling mediates the 15-HETE-induced differentiation of adventitial fibroblasts into myofibroblasts

Background

Pulmonary adventitial fibroblasts (PAFs) are activated under stress stimuli leading to their differentiation into myofibroblasts, which is involved in vessel remodeling. 15-HETE is known as an important factor in vessel remodeling under hypoxia; however, the role of 15-HETE in PAF phenotypic alteration is not clear.

Results

The effect of 15-HETE on PAF phenotypic alterations was investigated in the present study. PAFs were treated with 15-HETE (0.5 μM) for 24 h, and the myofibroblast marker α-smooth muscle actin (α-SMA) was analyzed. The 15-HETE induced α-SMA expression and cell morphology. 15-HETE upregulated FGF-2 levels in PAFs, and knockdown FGF-2 by siRNAs blocked the enhanced α-SMA expression induced by 15-HETE. p38 kinase was activated, and blocked depressed 15-HETE-induced FGF-2 expression. The downstream of p38 pathway, Egr-1 activation, was also raised by 15-HETE treatment, and silenced Egr-1 suppressed the 15-HETE-induced upregulation of FGF-2. TGF-β1 was upregulated with FGF-2 treatment, and α-SMA expression induced by FGF-2 was inhibited after the cell was transferred with TGF-β1 siRNA. Meanwhile, FGF-2 increased α-SMA expression and improved proliferation, which was associated with p27^kip1 and cyclin E variation.

Conclusions

The above results suggest that p38/Egr-1 pathway-mediated FGF-2 is involved in 15-HETE-induced differentiation of PAFs into myofibroblasts and cell proliferation.

The role of mid-chain hydroxyeicosatetraenoic acids in the pathogenesis of hypertension and cardiac hypertrophy

The incidence, prevalence, and hospitalization rates associated with cardiovascular diseases (CVDs) are projected to increase substantially in the world. Understanding of the biological and pathophysiological mechanisms of survival can help the researchers to develop new management modalities. Numerous experimental studies have demonstrated that mid-chain HETEs are strongly involved in the pathogenesis of the CVDs. Mid-chain HETEs are biologically active eicosanoids that result from the metabolism of arachidonic acid (AA) by both lipoxygenase and CYP1B1 (lipoxygenase-like reaction). Therefore, identifying the localizations and expressions of the lipoxygenase and CYP1B1 and their associated AA metabolites in the cardiovascular system is of major importance in understanding their pathological roles. Generally, the expression of these enzymes is shown to be induced during several CVDs, including hypertension and cardiac hypertrophy. The induction of these enzymes is associated with the generation of mid-chain HETEs and subsequently causation of cardiovascular events. Of interest, inhibiting the formation of mid-chain HETEs has been reported to confer a protection against different cardiac hypertrophy and hypertension models such as angiotensin II, Goldblatt, spontaneously hypertensive rat and deoxycorticosterone acetate (DOCA)-salt-induced models. Although the exact mechanisms of mid-chain HETEs-mediated cardiovascular dysfunction are not fully understood, the present review proposes several mechanisms which include activating G-protein-coupled receptor, protein kinase C, mitogen-activated protein kinases, and nuclear factor kappa B. This review provides a clear understanding of the role of mid-chain HETEs in the pathogenesis of cardiovascular diseases and their importance as novel targets in the treatment for hypertension and cardiac hypertrophy.

STAT3-mediated MMP-2 expression is required for 15-HETE-induced vascular adventitial fibroblast migration

OBJECTIVE

Vascular adventitial fibroblasts (VAFs) migration was involved in neointima formation, and increased 15-HETE levels contributed to vascular remodeling. However, how 15-HETE-induced VAF migration was not clear.

METHODS AND RESULTS

15-HETE-stimulated VAF phenotypic changes and migration as measured by the wound healing assay required STAT3 phosphorylation. JNK1 and CREB inhibition blocked 15-HETE-induced STAT3 activation and VAF changes. 15-HETE-induced MMP-2 expression and secretion were analyzed by Western blot and ELISA, respectively. MMP-2 knockdown blocked VAF migration and phenotypic alterations. JNK1, STAT3 and CREB blockade suppressed 15-HETE-induced MMP-2 expression in VAFs. MMP-2 promoter activity was assessed by chromatin immunoprecipitation using anti-STAT3 antibodies, which demonstrated that STAT3 was essential for 15-HETE-induced MMP-2 expression. Rats that suffered from hypoxia injury with or without treatment were examined. Pulmonary artery remodeling was obviously observed, and even the media was broken. MMP-2-positive staining was observed in the adventitia and intima. MMP-2 Serum secretion was enhanced as detected by ELISA, and MMP-2 and α-SMA protein expressions were increased after inducing hypoxia in the rats, which was restored in rats that had been administrated with NDGA.

CONCLUSION

These results reveal that STAT3-mediated MMP-2 expression is required for 15-HETE induced-VAF migration.

Effects of baicalin on collagen Ι and collagen ΙΙΙ expression in pulmonary arteries of rats with hypoxic pulmonary hypertension

The synthesis and accumulation of collagen play an important role in the formation and progression of hypoxic pulmonary hypertension. Baicalin has been reported to prevent bleomycin-induced pulmonary fibrosis. However, the role of baicalin in the treatment of pulmonary hypertension remains unknown. A disintegrin and metalloprotease with thrombospondin type-1 motif (ADAMTS-1) is a secreted enzyme that acts on a wide variety of extracellular matrix (ECM) substrates associated with vascular diseases. In this study, we aimed to investigate the effects of baicalin on the synthesis of collagen I in rats with pulmonary hypertension induced by hypoxia and the changes in ADAMTS-1 expression. A total of 24 Sprague Dawley rats were randomly assigned to 3 groups as follows: the control group (C), the hypoxia group (H) and the hypoxia + baicalin group (B). The rats in groups H and B were kept in a normobaric hypoxic chamber for 4 weeks, and the rats in group C were exposed to room air. We measured the hemodynamic indexes, including mean pulmonary artery pressure (mPAP), mean systemic (carotid) artery pressure (mSAP), and then calculated the mass ratio of right ventricle to left ventricle plus septum [RV/(LV + S)] to reflect the extent of right ventricular hypertrophy. We measured the mRNA and protein expression levels of type I collagen, type III collagen and ADAMTS-1 by hybridization in situ, and immunohistochemistry and western blot analysis, respectively. The results revealed that treatment with baicalin significantly reduced pulmonary artery pressure and attenuated the remodeling of the pulmonary artery under hypoxic conditions by increasing the expression of ADAMTS-1, so that the synthesis of type I collagen and its mRNA expression were inhibited. In conclusion, baicalin effectively inhibits the synthesis of collagen I in pulmonary arteries and this is associated with an increase in the expression of ADAMTS-1. Thus, treatment with baicalin may be an effective method for lowering pulmonary artery pressure and preventing pulmonary artery remodeling.

Valsartan improves portal hypertensive gastropathy in rats possibly via TGF-β1/Smad signaling pathway

AIM: To investigate the efficacy and mechanisms of action of valsartan on portal hypertensive gastropathy in rats with gastric mucosa lesions.

METHODS: Forty-eight SD rats were randomly divided into a sham-operated group, a portal hypertension gastropathy group, a valsartan prevention group, a normal dose valsartan group and a high dose valsartan group. Portal hypertensive gastropathy was induced by the partial portal vein ligation method. Gastric mucosa TGF-beta1 expression and microvessel density (MVD) were detected by immunohistochemical staining method. Gastric mucosa Smad2 and Smad7 protein expression was detected by Western blot. Plasma levels of rennin activity (PRA), angiotensin II (Ang II), alanine aminotransferase (ALT), and albumin (ALB) were determined by ELISA.

RESULTS: Compared with the model group, gastric mucosa TGF-β1 (11.58 ± 2.27, 13.29 ± 2.82, 13.15 ± 3.36 vs 24.25 ± 3.48, all P <0.05) and Smad2 (0.86 ± 0.59, 0.82±0.36, 0.83 ± 0.49 vs 1.60 ± 0.77, P < 0.05) protein expression was significantly decreased in the valsartan prevention group, normal dose valsartan group and high dose valsartan group. Smad7 protein expression in the valsartan prevention group, normal dose valsartan group and high dose valsartan group was significantly higher than that in the model group (1.59 ± 0.72, 1.65 ± 0.80, 1.69 ± 0.85 vs 0.58 ± 0.35, all P < 0.05). Plasma PRA (16.49 ng/mL ± 2.77 ng/mL, 15.92 ng/mL ± 4.30 ng/mL, 16.72 ng/mL ± 5.48 ng/mL vs 11.49 ng/mL ± 2.12 ng/mL, all P <0.05) and Ang II (1664.44 pg/mL ± 285.47 pg/mL, 1686.82 pg/mL ± 499.16 pg/mL, 1734.07 pg/mL ± 326.66 pg/mL vs 1110.38 pg/mL ± 193.85 pg/mL, all P <0.01) were also significantly higher in the valsartan prevention group, normal dose valsartan group and high dose valsartan group than in the model group.

CONCLUSION: Valsartan can improve portal hypertensive gastropathy probably by down-regulating TGF-β1 and Smad2 expression and up-regulating Smad7 expression.