Simvastatin rescues rats from fatal pulmonary hypertension by inducing apoptosis of neointimal smooth muscle cells

Simvastatin restores pulmonary endothelial function in the setting of pulmonary over-circulation

Statin therapy is a cornerstone in the treatment of systemic vascular diseases. However, statins have failed to translate as therapeutics for pulmonary vascular disease. Early pulmonary vascular disease in the setting of congenital heart disease (CHD) is characterized by endothelial dysfunction, which precedes the more advanced stages of vascular remodeling. These features make CHD an ideal cohort in which to re-evaluate the potential pulmonary vascular benefits of statins, with a focus on endothelial biology. However, it is critical that the full gamut of the pleiotropic effects of statins in the endothelium are uncovered. The purpose of this investigation was to evaluate the therapeutic potential of simvastatin for children with CHD and pulmonary over-circulation, and examine mechanisms of simvastatin action on the endothelium. Our data demonstrate that daily simvastatin treatment preserves endothelial function in our shunt lamb model of pulmonary over-circulation. Further, using pulmonary arterial endothelial cells (PAECs) isolated from Shunt and control lambs, we identified a new mechanism of statin action mediated by increased expression of the endogenous Akt1 inhibitor, C-terminal modifying protein (CTMP). Increases in CTMP were able to decrease the Akt1-mediated mitochondrial redistribution of endothelial nitric oxide synthase (eNOS) which correlated with increased enzymatic coupling, identified by increases in NO generation and decreases in NOS-derived superoxide. Together our data identify a new mechanism by which simvastatin enhances NO signaling in the pulmonary endothelium and identify CTMP as a potential therapeutic target to prevent the endothelial dysfunction that occurs in children born with CHD resulting in pulmonary over-circulation.

Simvastatin and dehydroepiandrosterone sulfate effects against hypoxic pulmonary hypertension are not additive

Pulmonary hypertension is a group of disorders characterized by elevated mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance. To test our hypothesis that combining two drugs useful in experimental pulmonary hypertension, statins and dehydroepiandrosterone sulfate (DHEA S), is more effective than either agent alone, we induced pulmonary hypertension in adult male rats by exposing them to hypoxia (10%O2) for 3 weeks. We treated them with simvastatin (60 mg/l) and DHEA S (100 mg/l) in drinking water, either alone or in combination. Both simvastatin and DHEA S reduced mPAP (froma mean±s.d. of 34.4±4.4 to 27.6±5.9 and 26.7±4.8 mmHg, respectively), yet their combination was not more effective (26.7±7.9 mmHg). Differences in the degree of oxidative stress (indicated by malondialdehydeplasma concentration),the rate of superoxide production (electron paramagnetic resonance), or blood nitric oxide levels (chemiluminescence) did not explain the lack of additivity of the effect of DHEA S and simvastatin on pulmonary hypertension. We propose that the main mechanism of both drugs on pulmonary hypertension could be their inhibitory effect on 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, which could explain their lack of additivity.

Mechanisms of pulmonary vascular dysfunction in pulmonary hypertension and implications for novel therapies

Pulmonary hypertension (PH) is a serious disease characterized by various degrees of pulmonary vasoconstriction and progressive fibroproliferative remodeling and inflammation of the pulmonary arterioles that lead to increased pulmonary vascular resistance, right ventricular hypertrophy, and failure. Pulmonary vascular tone is regulated by a balance between vasoconstrictor and vasodilator mediators, and a shift in this balance to vasoconstriction is an important component of PH pathology, Therefore, the mainstay of current pharmacological therapies centers on pulmonary vasodilation methodologies that either enhance vasodilator mechanisms such as the NO-cGMP and prostacyclin-cAMP pathways and/or inhibit vasoconstrictor mechanisms such as the endothelin-1, cytosolic Ca2+, and Rho-kinase pathways. However, in addition to the increased vascular tone, many patients have a "fixed" component in their disease that involves altered biology of various cells in the pulmonary vascular wall, excessive pulmonary artery remodeling, and perivascular fibrosis and inflammation. Pulmonary arterial smooth muscle cell (PASMC) phenotypic switch from a contractile to a synthetic and proliferative phenotype is an important factor in pulmonary artery remodeling. Although current vasodilator therapies also have some antiproliferative effects on PASMCs, they are not universally successful in halting PH progression and increasing survival. Mild acidification and other novel approaches that aim to reverse the resident pulmonary vascular pathology and structural remodeling and restore a contractile PASMC phenotype could ameliorate vascular remodeling and enhance the responsiveness of PH to vasodilator therapies.

Reversal of pulmonary arterial hypertension and neointimal formation by kinin B1 receptor blockade

Background

This study examined whether BI113823, a novel selective kinin B1 receptor antagonist can reverse established pulmonary arterial hypertension (PAH), prevent right heart failure and death, which is critical for clinical translation.

Methods

Left pneumonectomized male Wistar rats were injected with monocrotaline to induce PAH. Three weeks later, when PAH was well established, the rats received daily treatment of BI113823 or vehicle for 3 weeks.

Results

Treatment with BI113823 from day 21 to day 42 after monocrotaline injection reversed established PAH as shown by normalized values of mean pulmonary arterial pressure (mPAP). BI113823 therapy reversed pulmonary vascular remodeling, pulmonary arterial neointimal formation, and heart and lung fibrosis, reduced right ventricular pressure, right heart hypertrophy, improved cardiac output, and prevented right heart failure and death. Treatment with BI113823 reduced TNF-α and IL-1β, and macrophages recruitment in bronchoalveolar lavage, reduced CD-68 positive macrophages and expression of proliferating cell nuclear antigen (PCNA) in the perivascular areas, and reduced expression of iNOS, B1 receptors, matrix metalloproteinase (MMP)-2 and MMP-9 proteins, and the phosphorylation of ERK1/2 and AKT in lung. Treatment with BI113823 reduced mRNA expression of ANP, BNP, βMHC, CGTF, collange-I and IV in right heart, compared to vehicle treated controls. In human monocytes cultures, BI113823 reduced LPS-induced TNF-α production, MMP-2 and MMP-9 expression, and reduced TNF-α-induced monocyte migration.

Conclusions

We conclude that BI113823 reverses preexisting severe experimental pulmonary hypertension via inhibition of macrophage infiltration, cytokine production, as well as down regulation of matrix metalloproteinase proteins.

Emerging antenatal therapies for congenital diaphragmatic hernia-induced pulmonary hypertension in preclinical models

Congenital diaphragmatic hernia (CDH)-related deaths are the largest contributor to in-hospital neonatal deaths in children with congenital malformations. Morbidity and mortality in CDH are directly related to the development of pulmonary hypertension (PH). Current treatment consists of supportive measures. To date, no pharmacotherapy has been shown to effectively reverse the hallmark finding of pulmonary vascular remodeling that is associated with pulmonary hypertension in CDH (CDH-PH). As such, there is a great need for novel therapies to effectively manage CDH-PH. Our review aims to evaluate emerging therapies, and specifically focuses on those that are still under investigation and not approved for clinical use by the Food and Drug Administration. Therapies were categorized into antenatal pharmacotherapies or antenatal regenerative therapies and assessed on their method of administration, safety profile, the effect on pulmonary vascular pathophysiology, and overall efficacy. In general, emerging antenatal pharmaceutical and regenerative treatments primarily aim to alleviate pulmonary vascular remodeling by restoring normal function and levels of key regulatory factors involved in pulmonary vascular development and/or in promoting angiogenesis. Overall, while these emerging therapies show great promise for the management of CDH-PH, most require further assessment of safety and efficacy in preclinical models before translation into the clinical setting. IMPACT: Emerging antenatal therapies for congenital diaphragmatic hernia-induced pulmonary hypertension (CDH-PH) show promise to effectively mitigate vascular remodeling in preclinical models. Further investigation is needed in preclinical and human studies to evaluate safety and efficacy prior to translation into the clinical arena. This review offers a comprehensive and up-to-date summary of emerging therapies currently under investigation in experimental animal models. There is no cure for CDH-PH. This review explores emerging therapeutic options for the treatment of CDH-PH and evaluates their impact on key molecular pathways and clinical markers of disease to determine efficacy in the preclinical stage.

Dietary Geranylgeranyl Pyrophosphate Counteracts the Benefits of Statin Therapy in Experimental Pulmonary Hypertension

BACKGROUND

The mevalonate pathway generates endogenous cholesterol and intermediates including geranylgeranyl pyrophosphate (GGPP). By reducing GGPP production, statins exert pleiotropic or cholesterol-independent effects. The potential regulation of GGPP homeostasis through dietary intake and the interaction with concomitant statin therapy is unknown.

METHODS

We developed a sensitive high-pressure liquid chromatography technique to quantify dietary GGPP and conducted proteomics, qualitative real-time polymerase chain reaction screening, and Western blot to determine signaling cascades, gene expression, protein-protein interaction, and protein membrane trafficking in wild-type and transgenic rats.

RESULTS

GGPP contents were highly variable depending on food source that differentially regulated blood GGPP levels in rats. Diets containing intermediate and high GGPP reduced or abolished the effects of statins in rats with hypoxia- and monocrotaline-induced pulmonary hypertension: this was rescuable by methyl-allylthiosulfinate and methyl-allylthiosulfinate-rich garlic extracts. In human pulmonary artery smooth muscle cells treated with statins, hypoxia activated RhoA in an extracellular GGPP-dependent manner. Hypoxia-induced ROCK2 (Rho associated coiled-coil containing protein kinase 2)/Rab10 (Ras-related protein rab-10) signaling was prevented by statin and recovered by exogenous GGPP. The hypoxia-activated RhoA/ROCK2 pathway in rat and human pulmonary artery smooth muscle cells upregulated the expression of Ca²⁺-sensing receptor (CaSR) and HIMF (hypoxia-induced mitogenic factor), a mechanism attenuated by statin treatment and regained with exogenous GGPP. Rab10 knockdown almost abrogated hypoxia-promoted CaSR membrane trafficking, a process diminished by statin and resumed by exogenous GGPP. Hypoxia-induced pulmonary hypertension was reduced in rats with CaSR mutated at the binding motif of HIMF and the interaction between dietary GGPP and statin efficiency was abolished. In humans fed a high GGPP diet, blood GGPP levels were increased. This abolished statin-lowering effects on plasma GGPP, and also on hypoxia-enhanced RhoA activity of blood monocytes that was rescued by garlic extracts.

CONCLUSIONS

There is important dietary regulation of GGPP levels that interferes with the effects of statin therapy in experimental pulmonary hypertension. These observations rely on a key and central role of RhoA-ROCK2 cascade activation and Rab10-faciliated CaSR membrane trafficking with subsequent overexpression and binding of HIMF to CaSR. These findings warrant clinical investigation for the treatment of pulmonary hypertension and perhaps other diseases by combining statin with garlic-derived methyl-allylthiosulfinate or garlic extracts and thus circumventing dietary GGPP variations.

Angiotensin-Converting Enzyme 2 Activator Ameliorates Severe Pulmonary Hypertension in a Rat Model of Left Pneumonectomy Combined With VEGF Inhibition

Background: Pulmonary arterial hypertension (PAH) is a life-threatening and deteriorating disease with no promising therapy available currently due to its diversity and complexity. An imbalance between vasoconstriction and vasodilation has been proposed as the mechanism of PAH. Angiotensin-converting enzyme 2 (ACE2), which catalyzes the hydrolysis of the vasoconstrictor angiotensin (Ang) II into the vasodilator Ang-(1-7), has been shown to be an important regulator of blood pressure and cardiovascular diseases. Herein we hypothesized diminazene aceturate (DIZE), an ACE2 activator, could ameliorate the development of PAH and pulmonary vascular remodeling.

Methods: A murine model of PAH was established using left pneumonectomy (PNx) on day 0 followed by injection of a single dose of the VEGF receptor-2 inhibitor SU5416 (25 mg/kg) subcutaneously on day 1. All hemodynamic and biochemical measurements were done at the end of the study on day 42. Animals were divided into 4 groups (n = 6–8/group): (1) sham-operated group, (2) vehicle-treatment group (SuPNx₄₂), (3) early treatment group (SuPNx₄₂/DIZE₁₋₄₂) with DIZE at 15 mg/kg/day, subcutaneously from day 1 to day 42, and (4) late treatment group (SuPNx₄₂/DIZE₂₉₋₄₂) with DIZE from days 29–42.

Results: In both the early and late treatment groups, DIZE significantly attenuated the mean pulmonary artery pressure, pulmonary arteriolar remodeling, and right ventricle brain natriuretic peptide (BNP), as well as reversed the overexpression of ACE while up-regulating the expression of Ang-(1-7) when compared with the vehicle-treatment group. In addition, the early treatment group also significantly decreased plasma BNP and increased the expression of eNOS.

Conclusions: ACE2 activator has therapeutic potentials for preventing and attenuating the development of PAH in an animal model of left pneumonectomy combined with VEGF inhibition. Activation of ACE2 may thus be a useful therapeutic strategy for the treatment of human PAH.

Advanced therapeutic inhalation aerosols of a Nrf2 activator and RhoA/Rho kinase (ROCK) inhibitor for targeted pulmonary drug delivery in pulmonary hypertension: design, characterization, aerosolization, in vitro 2D/3D human lung cell cultures, and in vivo efficacy

Inhalable nanostructured microparticles of simvastatin, a Nrf2 activator and RhoA/Rho kinase (ROCK) inhibitor, were rationally designed for targeted pulmonary delivery as dry powder inhalers (DPIs) for the treatment of pulmonary hypertension (PH). Advanced particle engineering design technology was employed to develop inhalable dry powders using different dilute feed concentrations and spray drying pump rates. Several analytical techniques were used comprehensively to characterize the physicochemical properties of the resulting powders. Scanning electron microscopy (SEM) was used to visualize particle morphology (shape), surface structure, size, and size distribution. Karl Fischer titration (KFT) was employed to quantify the residual water content in the powders. X-ray powder diffraction (XRPD) was used to determine crystallinity. Hot-stage microscopy (HSM) under cross-polarizing lens was used to observe the presence or absence of birefringence characteristic of crystallinity. Differential scanning calorimetry (DSC) was employed to quantify thermotropic phase behavior. Attenuated total reflectance (ATR)-Fourier-transform infrared (FTIR) spectroscopy and Raman spectroscopy were used to determine the molecular fingerprint of simvastatin powders before and after particle engineering design. In vitro aerosol dispersion performance was performed with three different Food and Drug Administration (FDA)-approved human DPI devices. Cell viability and transepithelial electrical resistance (TEER) were demonstrated using different in vitro human pulmonary cell two and three-dimensional models at the air-liquid interface, and in vivo safety in healthy rats by inhalation. Efficacy was demonstrated in the in vivo lamb model of PH. Four different inhalable powders of simvastatin were successfully produced. They possessed nanostructured surfaces and were in the inhalable size range. Simvastatin retained its crystallinity following particle engineering design. The more dilute feed concentration spray dried at the lower pump rate produced the smallest particles. All powders successfully aerosolized with all three DPI human devices. Inhaled simvastatin as an aerosol restored the endothelial function in the shunt lamb model of PH, as demonstrated by the reduction of pulmonary vascular resistance (PVR) in response to the endothelium-dependent vasodilator acetylcholine.The reviews of this paper are available via the supplemental material section.

Combination of Dichloroacetate and Atorvastatin Regulates Excessive Proliferation and Oxidative Stress in Pulmonary Arterial Hypertension Development via p38 Signaling

Pulmonary arterial hypertension (PAH) is a lethal disease generally characterized by pulmonary artery remodeling. Mitochondrial metabolic disorders have been implicated as a critical regulator of excessively proliferative- and apoptosis-resistant phenotypes in pulmonary artery smooth muscle cells (PASMCs). Dichloroacetate (DCA) is an emerging drug that targets aerobic glycolysis in tumor cells. Atorvastatin (ATO) is widely used for hyperlipemia in various cardiovascular diseases. Considering that DCA and ATO regulate glucose and lipid metabolism, respectively, we hypothesized that the combination of DCA and ATO could be a potential treatment for PAH. A notable decrease in the right ventricular systolic pressure accompanied by reduced right heart hypertrophy was observed in the DCA/ATO combination treatment group compared with the monocrotaline treatment group. The DCA/ATO combination treatment alleviated vascular remodeling, thereby suppressing excessive PASMC proliferation and macrophage infiltration. In vitro, both DCA and ATO alone reduced PASMC viability by upregulating oxidative stress and lowering mitochondrial membrane potential. Surprisingly, when combined, DCA/ATO was able to decrease the levels of reactive oxygen species and cell apoptosis without compromising PASMC proliferation. Furthermore, suppression of the p38 pathway through the specific inhibitor SB203580 attenuated cell death and oxidative stress at a level consistent with that of DCA/ATO combination treatment. These observations suggested a complementary effect of DCA and ATO on rescuing PASMCs from a PAH phenotype through p38 activation via the regulation of mitochondrial-related cell death and oxidative stress. DCA in combination with ATO may represent a novel therapeutic strategy for PAH treatment.

Pulmonary arterial hypertension specific therapy: The old and the new

Pulmonary arterial hypertension (PAH) is a vascular disorder associated with high morbidity and mortality rate and is characterized by pulmonary vascular remodeling and increased pulmonary vascular resistance, ultimately resulting in right ventricular failure and death. Over the past few decades, significant advances in the understanding of the epidemiology, pathogenesis, and pathophysiology of pulmonary arterial hypertension have occured. This has led to the development of disease specific treatment including prostanoids, endothelin receptor antagonists, phosphodiesterase inhibitors, and soluble guanylate cyclase stimulators. These therapies significantly improve exercise capacity, quality of life, pulmonary hemodynamics, but none of the current treatments are actually curative and long-term prognosis remains poor. Thus, there is a clear need to develop new therapies. Several potential pharmacologic agents for the treatment of pulmonary arterial hypertension are under clinical development and some promising results with these treatments have been reported. These agents include tyrosine protein kinase inhibitors, rho-kinase inhibitors, synthetically produced vasoactive intestinal peptide, antagonists of the 5-HT2 receptors, and others. This article will review several of these promising new therapies and will discuss the current evidence regarding their potential benefit in pulmonary arterial hypertension.

Statin treatment prevents the development of pulmonary arterial hypertension in a nonhuman primate model of HIV-associated PAH

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by pulmonary vascular remodeling, elevated pulmonary arterial pressure, and right heart failure. Human immunodeficiency virus (HIV)-infected individuals have a higher incidence of PAH than the non-HIV infected population and evidence suggests a role for systemic and pulmonary inflammation in the pathogenesis of HIV-associated PAH. Due to their pleiotropic effects, including immune-modulatory and anti-inflammatory effects, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have been considered for the treatment of PAH, with conflicting results. The effects of statins on HIV-associated PAH have not been specifically evaluated. We have developed a non-human primate (NHP) model of HIV-associated PAH that closely mimics HIV-PAH using simian immunodeficiency virus (SIV)-infected rhesus macaques (Macaca mulatta). We determined that treatment of healthy macaques with atorvastatin prior to and throughout SIV infection prevented the development of SIV-associated PAH. Additionally, SIV-infected macaques that initiated atorvastatin treatment during the early chronic disease stage had reduced incidence of PAH compared to untreated animals. Statin treatment reduced inflammatory mediators TGF-β, MIP-1α, and TNF-α and the numbers of CD14^dimCD16⁺ non-classical monocytes, and CD14⁺CCR7⁻CD163⁻CD206⁺ alveolar macrophages previously shown to be associated with SIV-PAH. These results support the concept that statins reduce inflammatory processes that contribute to PAH and may provide a safe and effective prophylactic strategy for the prevention of PAH in HIV-infected individuals.

Benefits of statins in chronic obstructive pulmonary disease patients with pulmonary hypertension: A meta-analysis

PURPOSE

This meta-analysis was performed to evaluate the efficacy of statins in chronic obstructive pulmonary disease (COPD) patients with pulmonary hypertension (PH).

METHODS

A systematic search was made of MEDLINE, Cochrane, ISI Web of Science and SCOPUS databases. Randomized clinical trials on treatment of COPD-PH with the statins, compared with placebo, were reviewed. Studies were pooled to weighted mean differences (WMD), with 95% confidence interval (CI).

RESULTS

Five trials (enrolling 270 participants) met the inclusion criteria. Compared with placebo, the statins presented significant effects on systolic pulmonary artery pressure (WMD -4.52 mmHg; 95% CI -6.32 to -2.72 mmHg) and 6-min walk distance (6MWD) (WMD 32.46 m; 95% CI 13.63-51.29 m).

CONCLUSIONS

Statins therapy significantly improves PH and 6MWD in COPD patients with PH.

Current Treatment Strategies and Nanoparticle-Mediated Drug Delivery Systems for Pulmonary Arterial Hypertension

There are three critical pathways for the pathogenesis and progression of pulmonary arterial hypertension (PAH): the prostacyclin (prostaglandin I₂) (PGI₂), nitric oxide (NO), and endothelin pathways. The current approved drugs targeting these three pathways, including prostacyclin (PGI₂), phosphodiesterase type-5 (PDE5) inhibitors, and endothelin receptor antagonists (ERAs), have been shown to be effective, however, PAH remains a severe clinical condition and the long-term survival of patients with PAH is still suboptimal. The full therapeutic abilities of available drugs are reduced by medication, patient non-compliance, and side effects. Nanoparticles are expected to address these problems by providing a novel drug delivery approach for the treatment of PAH. Drug-loaded nanoparticles for local delivery can optimize the efficacy and minimize the adverse effects of drugs. Prostacyclin (PGI₂) analogue, PDE5 inhibitors, ERA, pitavastatin, imatinib, rapamycin, fasudil, and oligonucleotides-loaded nanoparticles have been reported to be effective in animal PAH models and in vitro studies. However, the efficacy and safety of nanoparticle mediated-drug delivery systems for PAH treatment in humans are unknown and further clinical studies are required to clarify these points.

Oxidative Stress and Its Implications in the Right Ventricular Remodeling Secondary to Pulmonary Hypertension

Pulmonary hypertension (PH) is a pulmonary vascular disease characterized by increased pulmonary artery pressures. Long standing pulmonary arterial pressure overload leads to right ventricular (RV) hypertrophy, RV failure, and death. RV failure is a major determinant of survival in PH. Oxidative stress has been associated with the development of RV failure secondary to PH. Here we summarize the structural and functional changes in the RV in response to sustained pulmonary arterial pressure overload. Furthermore, we review the pre-clinical and clinical studies highlighting the association of oxidative stress with pulmonary vasculature and RV remodeling in chronic PH. Targeting oxidative stress promises to be an effective therapeutic strategy for the treatment of RV failure.

The expression of survivin in irreversible pulmonary arterial hypertension rats and its value in evaluating the reversibility of pulmonary arterial hypertension secondary to congenital heart disease

The reversibility of pulmonary arterial hypertension (PAH) determines the operability of congenital heart disease (CHD) complicating with PAH, but it lacks a method for evaluating the reversibility. The current study aims to investigate the serum survivin level in irreversible PAH rats and to explore its potential as a biomarker for evaluating the reversibility of PAH in CHD patients. Irreversible PAH rats were characterized by prominent obstructive lesions resulting from the intimal formation, which was associated with decreased apoptosis and increased survivin expression, while reversible PAH rats were featured by medial hypertrophy resulting in mild occlusion, with increased apoptosis and unchanged survivin expression. In addition, the serum survivin was significantly increased in irreversible PAH rats when compared to both reversible PAH and control rats, and a positive correlation of serum survivin with survivin expression in the lung was confirmed. Third, the preoperative serum survivin was significantly higher in patients with irreversible CHD-PAH than in these with reversible CHD-PAH, and significant correlations between the serum survivin and BNP, preoperative pulmonary vascular resistance index, and postoperative mean pulmonary arterial pressure were also identified. In conclusion, the increased survivin level is a feature of irreversible PAH and the serum survivin represents a candidate biomarker reflecting the operability of CHD-PAH patients.

Simvastatin causes pulmonary artery relaxation by blocking smooth muscle ROCK and calcium channels: Evidence for an endothelium-independent mechanism

Simvastatin reduces pulmonary arterial pressure and right ventricular hypertrophy in animal models of pulmonary arterial hypertension (PAH) and is thought to restore endothelial dysfunction. In vivo effects of drugs are complicated by several factors and little is known of the direct effects of statins on pulmonary arteries. This study investigated the direct effects of simvastatin on pulmonary arteries isolated from rats with or without monocrotaline-induced PAH. Simvastatin suppressed contractions evoked by the thromboxane A2 receptor agonist U46619 (30 nM), the α₁–adrenergic agonist phenylephrine (5 μM) and KCl (50 mM) by ~50% in healthy and diseased arteries, but did not reduce contraction evoked by sarco/endoplasmic reticulum ATPase blockers. It relaxed hypertensive arteries in the absence of stimulation. Removing the endothelium or inhibiting eNOS did not prevent the inhibition by simvastatin. Inhibiting RhoA/rho kinase (ROCK) with Y27632 (10 μM) suppressed contractions to U46619 and phenylephrine by ~80% and prevented their inhibition by simvastatin. Y27632 reduced KCl-induced contraction by ~30%, but did not prevent simvastatin inhibition. Simvastatin suppressed Ca²⁺ entry into smooth muscle cells, as detected by Mn²⁺ quench of fura-2 fluorescence. The calcium antagonist, nifedipine (1 μM), almost abolished K⁺-induced contraction with less effect against U46619 and phenylephrine. We conclude that simvastatin relaxes pulmonary arteries by acting on smooth muscle to interfere with signalling through G-protein coupled receptors and voltage-dependent Ca²⁺ entry. Its actions likely include inhibition of ROCK-dependent Ca²⁺ sensitisation and voltage-gated Ca²⁺ channels. These are likely to contribute to the beneficial effects of simvastatin in animal models of PAH.

Silibinin efficacy in a rat model of pulmonary arterial hypertension using monocrotaline and chronic hypoxia

Background

C-X-C chemokine receptor type 4 (CXCR4) may be involved in the development of pulmonary arterial hypertension (PAH). CXCR4 inhibitor AMD3100 was described to have a positive effect on the prevention of pulmonary arterial muscularization in PAH models. Silibinin is a traditional medicine that has an antagonistic effect on CXCR4. We investigated the effect of silibinin using rat models of PAH.

Methods

PAH was induced by a single subcutaneous injection of monocrotaline. The rats were maintained in a chronic hypoxic condition (10% O₂) with or without silibinin. To evaluate the efficacy of silibinin on PAH, right ventricular systolic pressure (RVSP), Fulton index (weight ratio of right ventricle to the left ventricle and septum), percent medial wall thickness (% MT), and vascular occlusion score (VOS) were measured and calculated. Immunohistochemical analysis was performed targeting CXCR4 and c-Kit. Reverse transcription-quantitative polymerase chain reaction was performed for the stem cell markers CXCR4, stromal cell derived factor-1 (SDF-1), c-Kit, and stem cell factor (SCF), and the inflammatory markers monocyte chemoattractant protein 1 (MCP1), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNFα). Statistical analyses were performed using t-test and one-way analysis of variance with Bonferroni’s post hoc test.

Results

Silibinin treatment for 1 week reduced RVSP and Fulton index. Treatment for 2 weeks reduced RVSP, Fulton index, % MT, and VOS, as well as downregulating the expression of CXCR4, SDF-1, and TNFα in pulmonary arteries. In contrast, treatment for 3 weeks failed to ameliorate PAH. The time-course study demonstrated that RVSP, Fulton index, % MT, and VOS gradually increased over time, with a decrease in the expression of CXCR4 and TNFα occurring after 2 weeks of PAH development. After 3 weeks, SDF-1, c-Kit, and SCF began to decrease and, after 5 weeks, MCP1 and IL-6 gradually accumulated.

Conclusions

The CXCR4 inhibitor silibinin can ameliorate PAH, possibly through the suppression of the CXCR4/SDF-1 axis, until the point where PAH becomes a severe and irreversible condition. Silibinin results in reduced pulmonary arterial pressure and delays pulmonary arteriolar occlusion and pulmonary vascular remodeling.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1041-y) contains supplementary material, which is available to authorized users.

NH4Cl treatment prevents doxorubicin-induced myocardial dysfunction in vivo

AIMS

Improvements in cancer treatment have significantly extended the lifespan of patients. However, due to the adverse effects of cancer treatment, cancer survivors are at increased risk of cardiovascular complications. Doxorubicin is a widely used spectrum antitumor drug, but the life-threatening side-effect of cardiotoxicity limits its clinical application. Ammonium chloride (NH₄Cl), as a heteropolar compound with pH value regulation, can cause intracellular alkalization and metabolic acidosis thus effecting enzymatic activity and influencing the process of biological system. The underlying effect of NH₄CL in DOX-induced cardiomyocyte apoptosis and hypertrophy in mice has never been reported before.

MAIN METHODS

This study we used DOX to induce cardiac remodeling and dysfunction in mice. Myocardial histology was performed using HE staining. Myocardial cell size was measured by wheat germ agglutinin (WGA) staining. Echocardiographic evaluation of cardiac function, qPCR detection of the mRNA expression of cardiac hypertrophy and inflammation markers. Apoptosis was detected by TUNEL method. Transmission electron microscopy (TEM) was used to detect autophagy.

KEY FINDINGS

We found that NH₄CL effectively improved DOX-induced cardiomyocyte apoptosis and cardiac dysfunction in mice. Our results showed that NH₄CL significantly improved DOX-induced contractile dysfunction, inflammation, apoptosis and autophagy in mice.

SIGNIFICANCE

Our results indicate that NH₄CL is effective in improving DOX-induced cardiac dysfunction and remodeling. It may therefore be a therapeutic entry point to limit doxorubicin-mediated adverse cardiac reactions.

Angiotensin-converting enzyme 2 activation suppresses pulmonary vascular remodeling by inducing apoptosis through the Hippo signaling pathway in rats with pulmonary arterial hypertension

Objective: To investigate the effects of angiotensin-converting enzyme 2 (ACE2) activation on pulmonary arterial cell apoptosis during pulmonary vascular remodeling associated with pulmonary arterial hypertension (PAH) and to elucidate potential mechanisms related to Hippo signaling. Methods: PAH model was developed by injecting monocrotaline combined with left pneumonectomy using Sprague-Dawley rat. Then, resorcinolnaphthalein (Res; ACE2 activator), MLN-4760 (ACE2 inhibitor), A-779 (Mas inhibitor), and 4-((5,10-dimethyl-6-oxo-6,10-dihydro-5H-pyrimido[5,4-b]thieno[3,2-e][1,4]diazepin-2-yl)amino) benzenesulfonamide (XMU-MP-1; MST1/2 inhibitor) were administered via continuous subcutaneous or intraperitoneal injection for 3 weeks. Animals were randomly divided into six groups: control, PAH, PAH+Res, PAH+Res+MLN-4760, PAH+Res+A-779, and PAH+Res+XMU-MP-1. On 21 day, hemodynamics and pathologic lesions were evaluated. Apoptosis and apoptosis-associated proteins were detected by TUNEL and western blotting. ACE2 activity and Hippo pathway components including large tumor suppressor 1 (LATS1), Yes-associated protein (Yap), and phosphorylated Yap (p-Yap) were investigated by fluorogenic peptide assays and western blotting. Results: In the PAH models, the mean pulmonary arterial pressure, right ventricular hypertrophy index, pulmonary vascular remodeling, anti-apoptotic protein Bcl-2 and Yap were all increased but the pulmonary arterial cell apoptosis, pro-apoptotic proteins caspase-3 and Bax were lower. ACE2 activation significantly ameliorated pulmonary arterial remodeling, this action was related to increased apoptosis and up-regulation of LATS1 and p-Yap. These protective effects were mitigated by the co-administration of A779 or MLN-4760. Moreover, inhibiting the Hippo/LATS1/Yap pathway with XMU-MP-1 blocked apoptosis in pulmonary vascular cells induced by ACE2 activation during the prevention of PAH. Conclusions: Our findings suggest that ACE2 activation attenuates pulmonary vascular remodeling by inducing pulmonary arterial cell apoptosis via Hippo/Yap signaling during the development of PAH.

Arctigenin prevents monocrotaline-induced pulmonary arterial hypertension in rats

The hallmark features of the development of pulmonary arterial hypertension (PAH) include the proliferation of pulmonary vascular smooth muscle cells, oxidative stress, inflammation, and pulmonary artery remodeling. Arctigenin is a bioactive component of Arctium lappa that exerts anti-inflammatory and antiproliferative effects in several diseases; however, its effects on pulmonary arteries are still unclear. This study aimed to investigate the efficacy of arctigenin to prevent PAH. Rats injected with monocrotaline (MCT) progressively developed PAH. Arctigenin treatment (50 mg per kg per day, intra-peritoneally) ameliorated right ventricular systolic pressure and pulmonary arterial remodeling, decreased the expression of inflammatory cytokines, and limited the proliferation of pulmonary vascular smooth muscle cells in lungs. Mechanistically, arctigenin effectively inhibited the MCT-induced elevation of NLRP3, caspase-1, and interleukin 1-beta expression in the lungs. These results indicate that arctigenin ameliorates MCT-induced PAH, at least in part, through exerting its anti-inflammatory, antioxidant, and antiproliferative effects, which inhibit the NLRP3 inflammasome signal pathway in rats.

Arctigenin ameliorates monocrotaline-induced pulmonary arterial hypertension, at least in part, through exerting its anti-inflammatory, antioxidant, and antiproliferative effects, which inhibit the NLRP3 inflammasome signal pathway in rats.

Nanoparticle-Mediated Targeting of Pitavastatin to Small Pulmonary Arteries and Leukocytes by Intravenous Administration Attenuates the Progression of Monocrotaline-Induced Established Pulmonary Arterial Hypertension in Rats

Statins are known to improve pulmonary arterial hypertension (PAH) by their anti-inflammatory and anti-proliferative effects in animal models. However, recent clinical studies have reported that clinically approved statin doses failed to improve clinical outcomes in patients with PAH. We therefore hypothesized that nanoparticle (NP) -mediated targeting of pitavastatin could attenuate the progression of established PAH.We induced PAH by subcutaneously injecting monocrotaline (MCT) in Sprague-Dawley rats. On day 14 after the MCT injection, animals that displayed established PAH on echocardiography were included. On day 17, they were randomly assigned to the following 5 groups: daily intravenous administration of (1) vehicle, (2) fluorescein-isothiocyanate-NP, (3) pitavastatin, (4) pitavastatin-NP, or (5) oral sildenafil. Intravenous NP was selectively delivered to small pulmonary arteries and circulating CD11b-positive leukocytes. On day 21, pitavastatin-NP attenuated the progression of PAH at lower doses than pitavastatin alone. This was associated with the inhibition of monocyte-mediated inflammation, proliferation, and remodeling of the pulmonary arteries. Interestingly, sildenafil attenuated the development of PAH, but had no effects on inflammation or remodeling of the pulmonary arteries. In separate experiments, only treatment with pitavastatin-NP reduced the mortality rate at day 35.NP-mediated targeting of pitavastatin to small pulmonary arteries and leukocytes attenuated the progression of established MCT-induced PAH and improved survival. Therapeutically, pitavastatin-NP was associated with anti-inflammatory and anti-proliferative effects on small pulmonary arteries, which was completely distinct from the vasodilatory effect of sildenafil. Pitavastatin-NP can be a novel therapeutic modality for PAH.

Effects of Simvastatin on Fetal Cardiac Impairment in the Diaphragmatic Experimental Hernia Model

BACKGROUND

Statins and sildenafil have been shown to exert beneficial effects in cardiac injury. We hypothesized that antenatal maternal administration of simvastatin and/or sildenafil might also promote benefits in cardiac remodeling of congenital diaphragmatic hernia (CDH). Therefore, we performed micro-CT image analysis and histology of the heart after antennal treatment in experimental nitrofen-induced CDH.

METHODS

At 9.5 days post conception (dpc), pregnant rats were exposed to nitrofen. At 16 and 20 dpc fetuses were treated with simvastatin and/or sildenafil. At 21 dpc postmortem micro-CT and autopsy were performed.

RESULTS

All nitrofen-treated fetuses had a lower birth weight compared to controls; in the simvastatin-treated group, a significant improvement in CDH was noted. Impairment of the lung and liver was also noted in CDH. Compared to controls, CDH rats showed lower ventricular mass, with greater left ventricular thickness; simvastatin decreased the ventricular mass and improved wall thickness. CDH rats exhibited myocardial hypotrophy, severe vascular depression in the left ventricle, and intense interstitial edema compared to controls and nitrofen-exposed animals without CDH. In CDH, the cardiac morphology appeared deformed with left ventricular wall verticalization. Simvastatin improved cardiac myocyte appearance and heart morphology.

CONCLUSION

The potential to treat CDH with antenatal simvastatin may improve the management of this malformation.

Identifying Involvement of H19-miR-675-3p-IGF1R and H19-miR-200a-PDCD4 in Treating Pulmonary Hypertension with Melatonin

Non-coding RNAs play an important role in the pathogenesis of pulmonary arterial hypertension (PAH). The aim of this study was to characterize the therapeutic role of melatonin as well as the underlying molecular mechanism (its effects on the expression of H19 and its downstream signaling pathways) in the treatment of PAH. Real-time PCR and western blot analysis were performed to evaluate the expression of H19, miR-200a, miR-675, insulin-like growth factor-1 receptor (IGF1R), and programmed cell death 4 (PDCD4). The value of systolic pulmonary artery pressure (SPAP) and the ratio of medial thickening in the monocrotaline (MCT) group were increased, whereas the melatonin treatment could decrease these values to some extent. The weights of RV (right ventricle), LV (left ventricle) + IVS (interventricular septal), and RV/(LV + IVS) in the MCT group were much higher than those in the MCT + melatonin and control groups. In addition, the expression of H19, miR-675, IGF1R mRNA, and IGF1R protein in the MCT group was the highest, whereas their expression in the control group was the lowest. The expression of miR-200, PDCD4 mRNA, and PDCD4 protein in the MCT group was the lowest, whereas their expression in the control group was the highest. Furthermore, H19 directly suppressed the expression of miR-200a, whereas miR-675-3p and miR-200a directly inhibited the expression of IGF1R and PDCD4, respectively. Finally, melatonin treatment inhibited cell proliferation; upregulated the expression of H19, miR-675-3p, and PDCD4; and downregulated the expression of miR-200a and IGF1R. This study demonstrated the role of H19-miR-675-3p-IGF1R- and H19-miR-200a-PDCD4-signaling pathways in the melatonin treatment of PAH.

Cerivastatin Nanoliposome as a Potential Disease Modifying Approach for the Treatment of Pulmonary Arterial Hypertension

In this study we investigated nanoliposome as an approach to tailoring the pharmacology of cerivastatin as a disease-modifying drug for pulmonary arterial hypertension (PAH). Cerivastatin encapsulated liposomes with an average diameter of 98 ± 27 nm were generated by a thin film and freeze-thaw process. The nanoliposomes demonstrated sustained drug-release kinetics in vitro and inhibited proliferation of pulmonary artery (PA) smooth muscle cells with significantly less cellular cytotoxicity as compared with free cerivastatin. When delivered by inhalation to a rat model of monocrotaline-induced PAH, cerivastatin significantly reduced PA pressure from 55.13 ± 9.82 to 35.56 ± 6.59 mm Hg (P < 0.001) and diminished PA wall thickening. Echocardiography showed that cerivastatin significantly reduced right ventricle thickening (monocrotaline: 0.34 ± 0.02 cm vs. cerivastatin: 0.26 ± 0.02 cm; P < 0.001) and increased PA acceleration time (monocrotaline: 13.98 ± 1.14 milliseconds vs. cerivastatin: 21.07 ± 2.80 milliseconds; P < 0.001). Nanoliposomal cerivastatin was equally effective or slightly better than cerivastatin in reducing PA pressure (monocrotaline: 67.06 ± 13.64 mm Hg; cerivastatin: 46.31 ± 7.64 mm Hg vs. liposomal cerivastatin: 37.32 ± 9.50 mm Hg) and improving parameters of right ventricular function as measured by increasing PA acceleration time (monocrotaline: 24.68 ± 3.92 milliseconds; cerivastatin: 32.59 ± 6.10 milliseconds vs. liposomal cerivastatin: 34.96 ± 7.51 milliseconds). More importantly, the rate and magnitude of toxic cerivastatin metabolite lactone generation from the intratracheally administered nanoliposomes was significantly lower as compared with intravenously administered free cerivastatin. These studies show that nanoliposome encapsulation improved in vitro and in vivo pharmacologic and safety profile of cerivastatin and may represent a safer approach as a disease-modifying therapy for PAH.

High expression of CXCR4 and stem cell markers in a monocrotaline and chronic hypoxia-induced rat model of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a severe and fatal clinical syndrome. C-X-C chemokine receptor type 4 (CXCR4) is known to serve a key role in recruiting mesenchymal stem cells (MSCs) from the bone marrow. In the present study, a rat model of PAH induced by 5 weeks of chronic hypoxia and treatment with a single injection of monocrotaline (60 mg/kg) was used to investigate the involvement of CXCR4 in PAH. Successful establishment of the PAH model was confirmed by significant differences between the PAH and control groups in right ventricular systolic pressure, Fulton index, wall thickness, vascular occlusion score determined by immunohistochemical staining and the expression of inflammatory markers measured by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The expression of CXCR4 and other stem cell markers were compared in the PAH and control groups. RT-qPCR showed that the expression of CXCR4, SCF, c-Kit, and CD29, which are expressed in MSCs, was significantly higher in the PAH group. Immunohistochemical staining also showed that the numbers of CXCR4-, c-Kit- and CD90-positive cells were significantly higher in the PAH group. These results suggest that CXCR4 is involved in the pathogenesis of PAH and that stem cells may serve an important role in pulmonary vascular remodeling.

Protection against monocrotaline-induced pulmonary arterial hypertension and caveolin-1 downregulation by fluvastatin in rats

Statins are Hydroxymethylglutaryl-coenzyme A reductase inhibitors, which are typically used to lower blood cholesterol. Additional beneficial effects, including improvement to pulmonary arterial hypertension (PAH), have also been confirmed. However, the mechanisms underlying this improvement have not yet been clarified. The present study was conducted to determine if fluvastatin was protective against experimental PAH development and to investigate the potential effects of fluvastatin on caveolin‑1 (cav‑1) expression. Rats were randomized to either receive a single subcutaneous injection of monocrotaline (MCT; 60 mg/kg; MCT group) or a single subcutaneous injection of MCT (60 mg/kg) followed by an oral gavage of fluvastatin (10 mg/kg) once daily until day 42 (M + F group). Rats in the MCT group received an equivalent volume of saline following the MCT injection. Six additional rats were given an equivalent volume of saline throughout as a control measure. PAH associated variables and cav‑1 protein expression were measured in each group at various times during the experimental period. Hemodynamic and morphometric analysis revealed that M + F rats developed moderate, delayed PAH. Cav‑1 western blot analysis demonstrated that cav‑1 expression was not significantly different in fluvastatin treated rats; however, MCT injured rats given saline had markedly reduced cav‑1 expression. It was concluded that fluvastatin may protect against PAH development and ameliorate MCT induced inhibition of cav‑1 expression in rats.

Are statins beneficial for the treatment of pulmonary hypertension?

Pulmonary hypertension (PH) is a condition characterized by vasoconstriction and vascular remodeling with a poor prognosis. The current medical treatments available are supportive care therapy and pulmonary vascular-targeted therapy. Targeted treatments for PH include prostacyclin analogs, endothelin receptor antagonists, and phosphodiesterase type 5 inhibitors; however, these treatments cannot reverse pulmonary vascular remodeling. Recently, many novel treatment options involving drugs such as statins have been emerging. In this review, we attempt to summarize the current knowledge of the role of statins in PH treatment and their potential clinical effects. Many basic researches have proved that statins can be helpful for the treatment of PH both in vitro and in experimental models. The main mechanisms underlying the effects of statins are restoration of endothelial function, attenuation of pulmonary vascular remodeling, regulation of gene expression, regulation of intracellular signaling processes involved in PH, anti-inflammatory responses, and synergy with other targeted drugs. Nevertheless, clinical researches, especially randomized controlled trials for PH are rare. The current clinical researches show contrasting results on the clinical effects of statins in patients with PH. Carefully designed randomized, controlled trials are needed to test the safety and efficacy of statins for PH treatment.

Statins may be beneficial for patients with pulmonary hypertension secondary to lung diseases

BACKGROUND

Previous animal studies and clinical trials report inconsistent findings regarding the role of statins in pulmonary hypertension (PH). Systematic reviews have shown no use of statins on pulmonary arterial hypertension (PAH). This is the first meta-analysis of randomized controlled trials (RCTs) determining the clinical impacts of statin therapy on patients with PH secondary to lung diseases.

METHODS

Electronic databases and manual bibliographical searches were conducted. Eligible studies included RCTs of at least 3 months that evaluated statin therapy as compared with control in adult patients with PH due to pulmonary diseases. Statistical analyses were performed to calculate mean difference, relative risks (RRs), and 95% confidence intervals (CIs) using random-effect model.

RESULTS

A total of 6 RCTs were identified and included in this study. Five trials reported the effects of statins in patients with both chronic obstructive pulmonary disease (COPD) and PH, and the remaining 1 was based on PH due to pneumoconiosis. We found that statin therapy was associated with increased 6-minute walk distance and reduced pulmonary artery systolic pressure. There was no observed difference in the incidence of death, drug withdrawal, and adverse event between statin and control group.

CONCLUSIONS

Our findings suggest that statins might be safe and beneficial for patients with PH due to chronic lung diseases. However, larger RCTs with more patients and longer observational duration are needed.

Pulmonary hypertension due to left heart disease causes intrapulmonary venous arterialization in rats

OBJECTIVE

A rat model of left atrial stenosis-associated pulmonary hypertension due to left heart diseases was prepared to elucidate its mechanism.

METHODS

Five-week-old Sprague-Dawley rats were randomly divided into 2 groups: left atrial stenosis and sham-operated control. Echocardiography was performed 2, 4, 6, and 10 weeks after surgery, and cardiac catheterization and organ excision were subsequently performed at 10 weeks after surgery.

RESULTS

Left ventricular inflow velocity, measured by echocardiography, significantly increased in the left atrial stenosis group compared with that in the sham-operated control group (2.2 m/s, interquartile range [IQR], 1.9-2.2 and 1.1 m/s, IQR, 1.1-1.2, P < .01), and the right ventricular pressure-to-left ventricular systolic pressure ratio significantly increased in the left atrial stenosis group compared with the sham-operated control group (0.52, IQR, 0.54-0.60 and 0.22, IQR, 0.15-0.27, P < .01). The right ventricular weight divided by body weight was significantly greater in the left atrial stenosis group than in the sham-operated control group (0.54 mg/g, IQR, 0.50-0.59 and 0.39 mg/g, IQR, 0.38-0.43, P < .01). Histologic examination revealed medial hypertrophy of the pulmonary vein was thickened by 1.6 times in the left atrial stenosis group compared with the sham-operated control group. DNA microarray analysis and real-time polymerase chain reaction revealed that transforming growth factor-β mRNA was significantly elevated in the left atrial stenosis group. The protein levels of transforming growth factor-β and endothelin-1 were increased in the lung of the left atrial stenosis group by Western blot analyses.

CONCLUSIONS

We successfully established a novel, feasible rat model of pulmonary hypertension due to left heart diseases by generating left atrial stenosis. Although pulmonary hypertension was moderate, the pulmonary hypertension due to left heart diseases model rats demonstrated characteristic intrapulmonary venous arterialization and should be used to further investigate the mechanism of pulmonary hypertension due to left heart diseases.

Reoxygenation Reverses Hypoxic Pulmonary Arterial Remodeling by Inducing Smooth Muscle Cell Apoptosis via Reactive Oxygen Species-Mediated Mitochondrial Dysfunction

Background

Pulmonary arterial remodeling, a main characteristic of hypoxic pulmonary hypertension, can gradually reverse once oxygen has been restored. Previous studies documented that apoptosis increased markedly during the reversal of remodeled pulmonary arteries, but the types of cells and mechanisms related to the apoptosis have remained elusive. This study aimed to determine whether pulmonary artery smooth muscle cell (PASMC)‐specific apoptosis was involved in the reoxygenation‐induced reversal of hypoxic pulmonary arterial remodeling and elucidate the underlying mechanism.

Methods and Results

Hypoxic pulmonary hypertension was induced in adult male Sprague‐Dawley rats (n=6/group) by chronic hypobaric hypoxia. and the hypoxic pulmonary hypertension rats were then transferred to a normoxia condition. During reoxygenation, hypoxia‐induced pulmonary arterial remodeling gradually reversed. The reversal of remodeled pulmonary arteries was associated with increased H₂O₂ and with changes in lung expression of cleaved caspase3/PARP, Bax, and Bcl‐2, consistent with increased apoptosis. The PASMC apoptosis, in particular, increased remarkably during this reversal. In vitro, reoxygenation induced the apoptosis of cultured rat primary PASMCs accompanied by increased mitochondrial reactive oxygen species, mitochondrial dysfunction, and the release of cytochrome C from mitochondria to cytoplasm. Clearance of reactive oxygen species alleviated mitochondrial dysfunction as well as the release of cytochrome C and, finally, decreased PASMC apoptosis.

Conclusions

Reoxygenation‐induced apoptosis of PASMCs is implicated in the reversal of hypoxic pulmonary arterial remodeling, which may be attributed to the mitochondrial reactive oxygen species–mediated mitochondrial dysfunction.

Statins ameliorate pulmonary hypertension secondary to left ventricular dysfunction through the Rho-kinase pathway and NADPH oxidase

BACKGROUND

Pulmonary hypertension (PH) is a devastating disorder, for which no therapy is curative. It has been reported that pulmonary vascular remodeling, associated with increasing mean pulmonary arterial pressure and upregulated expression of endothelial nitric oxide synthase (eNOS), endothelin-1 (ET-1), RhoA/RhoH-kinase results in the development of PH. Oxidative stress and the RhoA/Rho-kinase pathway are also thought to be involved in the pathophysiology of PH. Statins are 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (HMG-CoA reductase inhibitors) with pleiotropic effects and are potential agents for the treatment of PH. In this study, we investigated the beneficial effects of simvastatin on the development of PH secondary to left ventricular dysfunction.

METHODS

A PH secondary to left ventricular dysfunction model was established in 6-week-old aortic-banded rats. The pulmonary expression of Rho kinase, ET-1, eNOS, p-eNOS, nitrite/nitrate (NOx), cGMP, p47^Phox , and p67^Phox were investigated in the early-treatment group, to which was administered simvastatin (30 mg/kg/day) from days 1 to 42 or the late-treatment group, to which was administered simvastatin (30 mg/kg/day) from days 29 to 42.

RESULTS

Simvastatin attenuated the mean pulmonary artery pressure, pulmonary arteriolar remodeling, plasma brain natriuretic peptide, ET-1, reactive oxygen species, and the NADPH oxidase 2 regulatory subunits, p47^Phox and p67^Phox , and upregulated pulmonary p-eNOS, NOx, and cGMP in both the early- and late-treated groups.

CONCLUSIONS

Inhibiting HMG-CoA reductase may have therapeutic potential for preventing and attenuating the development of PH in left ventricular dysfunction through the Rho-kinase pathway and NADPH oxidase. A translational study in humans is needed to substantiate these findings. Pediatr Pulmonol. 2017;52:443-457. © 2016 Wiley Periodicals, Inc.

The Effects of Statins on Pulmonary Artery Pressure in Patients with Chronic Obstructive Pulmonary Disease: A Randomized Controlled Trial

OBJECTIVE

Pulmonary hypertension is a serious complication in patients suffering from chronic obstructive pulmonary disease (COPD). The aim of this study is to investigate the effects of atorvastatin in reducing pulmonary arterial pressure in COPD patients.

METHODS

This double-blind, randomized trial was conducted on 42 known cases of COPD with systolic pulmonary arterial pressure of more than 25 mmHg. The patients were randomly assigned into two groups, 21 patients with atorvastatin treatment (40 mg/daily for 6 months) and 21 patients without receiving atorvastatin. All the patients participated voluntarily and provided written informed consent. The trial was registered in the Iranian Registry of Clinical Trials. Pulmonary pressure was also anticipated by Doppler echocardiography with peak pressure gradient of tricuspid regurgitation. Both groups were tested with echocardiography to measure systolic pulmonary pressure at baseline and posttreatment. Statistical analysis includes Chi-square, Student's t-test, and Wilcoxon test. P < 0.05 was considered statistically significant.

FINDINGS

The mean age was 65.8 ± 11.5 years for atorvastatin group and 63.7 ± 7.6 years for control group (P = 0.45). Baseline and posttreatment mean systolic pulmonary artery pressure (PAP) levels in the atorvastatin group were 48.9 ± 3.3 and 38.4 ± 1.9 mmHg, respectively (P = 0.007). In the control group, mean systolic PAP levels at baseline and 6 months later were 45.6 ± 3.1 and 38.9 ± 2.4 mmHg, respectively (P = 0.073). The patients treated with atorvastatin showed significant decrease in total cholesterol (P = 0.001) and low-density lipoprotein cholesterol (P = 0.008).

CONCLUSION

A 40 mg dose of atorvastatin daily for 6 months may have beneficial effects in reducing PAP in patients with COPD. Further studies are necessary to find long-term effects of statins in COPD patients.

Outcome of rheumatoid arthritis following adjunct statin therapy

Objective:

Rheumatoid arthritis (RA) is characterized by symmetric peripheral polyarthritis, inflammatory synovitis, and articular destruction. Statins, 3-hydroxy-3-methylglutaryl coenzyme A-reductase inhibitors, mediate significant vascular risk reduction in patients with coronary artery disease by promoting reduction in plasma levels of low-density-lipoprotein cholesterol. Extensive in vitro data, experimental studies and more recently few clinical trials have strongly suggested statins to possess an important role in RA mainly mediated by their anti-inflammatory and immunomodulatory properties. The objective of this study was to evaluate the effect of adjunct statin therapy in comparison to standard disease modifying antirheumatic drugs (DMARD) therapy in patients with RA.

Materials and Methods:

In this observational study, diagnosed RA patients of age group between 40 and 60 years were selected as per the inclusion criteria from the rheumatology outdoor. From the selected patients, we identified two separate groups of patients. Group 1 included 30 patients of RA currently under DMARD therapy with adjunct statin medication. Group 2 included 30 patients of RA currently under DMARD therapy. Patients were followed up over 6 months. Standard parameters such as disease activity score (DAS28), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were recorded for comparing the outcome of RA in both groups.

Results:

Out of a total of 60 patients who took part in the study, significant beneficial role of adjunct statin medication was found in this study when prescribed along with conventional DMARDs in active RA patients. The mean DAS28, considered by far as the most important index of clinical disease activity in RA, was found to be significantly lower (P < 0.05) in the adjunct statin-treated group (group 1) than that of the conventional DMARD treated group (group 2) after 6 months of continuous therapy. Other two important biochemical markers of RA disease activity, that is, ESR and CRP were also found to be significantly lower (P < 0.05) in RA patients who were on adjunct statin medication (group 1) than in group 2 comprising RA patients only under conventional DMARDs therapy without statin medication.

Conclusion:

The results suggest an adjunct and potentially beneficial role of statin therapy in active cases of RA, producing significant clinical and biochemical improvement.

Efficacy and Safety of Statins for Pulmonary Hypertension: A Meta-Analysis of Randomised Controlled Trials

BACKGROUND

Pulmonary hypertension (PH) is a serious disease, and treatment is a continuing challenge. Some in vitro and in vivo studies identified that statins were effective for PH. However, results of some randomised controlled trials (RCTs) have been controversial. The objective of our study was to clarify whether statins are effective and safe for pulmonary hypertension.

METHODS

We systematically searched for eligible RCTs from PubMed, EMBASE, Web of Science, and the Cochrane Library during January 2016. Two reviewers independently extracted data. Standard mean differences (SMDs) and weighted mean differences (WMDs) with 95% confidence intervals (CIs) were estimated for continuous data (exercise capacity cardiac, pulmonary arterial pressure (PAP), cardiac index, and low-density lipoprotein (LDL)). Risk ratios (RRs) were estimated for dichotomous data (adverse events and clinical deterioration).

RESULTS

A total of 496 patients from six RCTs were included. Low-density lipoprotein in the statin group decreased significantly compared with the placebo group (WMD = -22.79; 95% CI: -34.33 ∼ -11.24). However, we did not find a statistically significant effect on exercise capacity (SMD = 0.18; 95% CI: -0.34 - 0.71), PAP (WMD = -3.01; 95% CI: -8.68 - 2.65), or CI (WMD = -0.04; 95% CI: -0.15 - 0.23). Additionally, there was no difference between statins and placebo with respect to hepatic injury (RR: 1.12; 95% CI: 0.43 - 2.92), myalgia (RR: 0.81; 95% CI: 0.32 - 2.03), or clinical deterioration (RR: 0.98; 95% CI: 0.58 - 1.67).

CONCLUSIONS

Statin treatment appears to be safe but may have no effect on PH.

A systematic review and meta-analysis of trials using statins in pulmonary arterial hypertension

Statins improve pulmonary vascular remodeling and right ventricular hypertrophy in animal models of pulmonary arterial hypertension (PAH). However, clinical trials assessing the efficacy of statins in patients with PAH have reported mixed results. In this systematic review and meta-analysis, we assess the efficacy of statins in patients with PAH. We included randomized controlled clinical trials (RCTs) that evaluated the efficacy of statins in patients with PAH. Primary outcomes were mortality and change in 6-minute walk distance (6MWD). Data are presented as odds ratio (OR) and weighted mean difference (WMD), with 95% confidence intervals (CIs), for binary and continuous variables, respectively. We included 4 RCTs of high quality. The mean age of participants was 42 ± 13 years, and 70% were women. The statins used were simvastatin at 40-80 mg in two trials, atorvastatin 10 mg in one trial, and rosuvastatin 10 mg in the other. In the pooled-data analysis, there was no statistically significant improvement in mortality (OR: 0.75 [95% CI: 0.32-1.74]), 6MWD (WMD: -9.27 [95% CI: -27.73 to 9.20]), or cardiac index (WMD: 0.11 [95% CI: -0.04 to 0.27]) with statin therapy when compared to placebo. There was no difference in adverse events leading to withdrawal of therapy between statin and placebo groups. These data suggest that statins are not beneficial in the treatment of PAH. There is a need for large, well-conducted clinical trials assessing the effects of statins in patients with PAH. Future trials should include homogeneous patient populations and should be long-term, event-driven trials with combined morbidity and mortality end points.

Rosuvastatin intensifies the beneficial effects of rho-kinase inhibitor in reversal of monocrotaline-induced pulmonary hypertension

INTRODUCTION

It remains controversial whether statins have a beneficial effect on pulmonary arterial hypertension (PAH). This study is intended to evaluate whether statin, co-administered with Rho-kinase inhibitor, could enhance its efficacy. Although Rho-kinase inhibitors, including fasudil, have been reported to improve pulmonary hypertension in experimental and clinical studies, the combination of these agents has not been tested in the treatment of pulmonary hypertension (PH).

MATERIAL AND METHODS

The effects of such a regimen on hemodynamics, right ventricle hypertrophy, and Rho-associated protein kinase (ROCK) activity in experimental monocrotaline (MCT)-induced pulmonary hypertension were examined. Fourteen days after monocrotaline injection (60 mg/kg), male rats were treated orally for another 14 days with fasudil (15 mg/kg per day), or with a combination of fasudil + rosuvastatin (10 mg/kg per day).

RESULTS

The drug combination reversed the MCT-induced increase in right ventricle pressure (RVP) and reduced right ventricular hypertrophy (RV/LV + S ratio) more than Rho kinase inhibitor alone. The simultaneous administration of fasudil and rosuvastatin caused a further decrease of RhoA kinase activity in isolated lung tissues as compared to fasudil alone.

CONCLUSIONS

The results indicate that rosuvastatin intensifies the beneficial effects of Rho-kinase inhibitor on the Rho/Rho-kinase pathway and such a combination may represent an option for the treatment of pulmonary arterial hypertension.

Efficacy of Statin Therapy in Pulmonary Arterial Hypertension: A Systematic Review and Meta-Analysis

Since the evidence regarding statin therapy in PAH has not been conclusive, we assessed the impact of statin therapy in PAH through a systematic review and meta-analysis of available studies. We searched selected databases up to August 1, 2015 to identify the studies investigating the effect of statin administration on PAH. Meta-analysis was performed using either a fixed-effects or random-effect model according to I(2) statistic. Meta-analysis of 8 studies with 665 patients did not suggest any significant improvement in 6-min walking distance (6MWD) by statin therapy (weighed mean difference [WMD]: -6.08 m, 95% confidence interval [CI]: -25.66, 13.50, p = 0.543; Q = 8.41, I(2) = 28.64%). Likewise, none of the other indices including pulmonary arterial pressure (WMD: -0.97 mmHg, 95%CI: -4.39, 2.44, p = 0.577; Q = 14.64, I(2) = 79.51%), right atrial pressure (WMD: 1.01 mmHg, 95%CI: -0.93, 2.96, p = 0.307; Q = 44.88, I(2) = 95.54%), cardiac index (WMD: 0.05 L/min/m(2), 95%CI: -0.05, 0.15, p = 0.323; Q = 3.82, I(2) = 21.42%), and pulmonary vascular resistance (WMD: -1.42 dyn*s/cm(5), 95%CI: -72.11, 69.27, p = 0.969; Q = 0.69, I(2) = 0%) was significantly altered by statin therapy. In conclusion, the results of the meta-analysis did not show a statistically significant effect of statin therapy in the improvement of 6MWD, pulmonary arterial pressure, right atrial pressure, cardiac index and pulmonary vascular resistance.

Differential effect of mild and severe pulmonary embolism on the rat lung transcriptome

BACKGROUND

Pulmonary thromboembolism (PTE) is a common diagnosis and a leading cause of cardiovascular morbidity and mortality. A growing literature has associated PE with systemic inflammation, and global hyper-coagulability, which contribute to lung remodeling and clot recurrence. The source and mechanism of inflammation remains unstudied. In humans, inhibition of cholesterol synthesis with statins decreases biomarkers of inflammation. We test the differential effect of pulmonary vascular occlusion during mild and severe pulmonary embolism on the lung transcriptome.

METHODS

Experimental PE was induced in adult male rats by injection of 25 micron polystyrene microspheres into the jugular vein. The effect of Mild PE, (2-h right ventricular systolic pressure [RVSP] normal, 18-h RVSP 44 mmHg) and Severe PE (2-h RVSP > 50 mmHg; 18-h RVSP 44 mmHg) on lungs was assessed by measuring transcriptome-wide changes in gene expression by DNA microarrays.

RESULTS

Severe PE was associated with a large change in lung gene expression and in the expression of KEGG pathways and other gene functional annotation groups. Mild PE was also associated with a large number of significant changes in gene expression and in the expression of KEGG pathways and gene functional annotation groups, even after only 2 h of PE. Up-regulated pathways included increased adipocytokine, chemokine and cytokine signaling as well as cholesterol synthesis.

CONCLUSIONS

Mild PE without acute pulmonary hypertension (PH) increased lung gene expression of inflammatory pathways, including increased cholesterol synthesis. These data indicate that even mild persistent pulmonary vascular occlusion is capable of inciting an inflammatory response from the lung. These data imply the detrimental effect of unresolved pulmonary obstruction from PE.

Could simvastatin be considered as a potential therapy for chronic lung diseases? A debate on the pros and cons

INTRODUCTION

Simvastatin (SV) is a drug from the statin class, currently used orally as an anti-cholesterolemic drug. It inhibits the 3-hydroxy-3-methyl-glutaryl-Coenzyme A (HMG-CoA) reductase to reduce cholesterol synthesis. Recently, it has been found that SV also has several other protective pharmacological actions unrelated to its anti-cholesterol effects that might be beneficial in the treatment of chronic airway diseases.

AREAS COVERED

This review summarizes the evidence relating to SV as a potential anti-inflammatory, anti-oxidant and muco-inhibitory agent, administered both orally and via pulmonary inhalation, and discusses its pro and cons. Evidence could potentially be used to support the delivery of SV as inhaled formulation for the treatment of chronic respiratory diseases.

EXPERT OPINION

The use of SV as anti-inflammatory, anti-oxidant and muco-inhibitory agent for drug delivery to the lung is promising. Inhaled SV formulations could allow the delivery profile to be customized and optimized to take advantage of the rapid onset of action, low systemic side effect and improved physico-chemical stability. This treatment could potentially to be used clinically for the localized treatment of lung diseases where inflammation and oxidative stress production is present.

Reconciling paradigms of abnormal pulmonary blood flow and quasi-malignant cellular alterations in pulmonary arterial hypertension

In pulmonary arterial hypertension (PAH) structural and functional abnormalities of the small lung vessels interact and lead to a progressive increase in pulmonary vascular resistance and right heart failure. A current pathobiological concept characterizes PAH as a 'quasi-malignant' disease focusing on cancer-like alterations in endothelial cells (EC) and the importance of their acquired apoptosis-resistant, hyper-proliferative phenotype in the process of vascular remodeling. While changes in pulmonary blood flow (PBF) have been long-since recognized and linked to the development of PAH, little is known about a possible relationship between an altered PBF and the quasi-malignant cell phenotype in the pulmonary vascular wall. This review summarizes recognized and hypothetical effects of an abnormal PBF on the pulmonary vascular bed and links these to quasi-malignant changes found in the pulmonary endothelium. Here we describe that abnormal PBF does not only trigger a pulmonary vascular cell growth program, but may also maintain the cancer-like phenotype of the endothelium. Consequently, normalization of PBF and EC response to abnormal PBF may represent a treatment strategy in patients with established PAH.

Therapeutic efficacy of valproic acid in a combined monocrotaline and chronic hypoxia rat model of severe pulmonary hypertension

BACKGROUND

Pulmonary hypertension (PH) is a serious disease with poor prognosis. Reports show that cells in remodeled pulmonary arteries of PH patients have similar characteristics to cancer cells, such as exuberant inflammation, increased proliferation, and decreased apoptosis. An ideal strategy for developing PH therapies is to directly target pulmonary vascular remodeling. High levels of histone deacetylase (HDAC) expression and activity are found in certain cancers, and research has shown the potential of HDAC inhibitors in repressing tumor growth via anti-inflammatory and anti-proliferative effects. To date, little is known about the effectiveness of HDAC inhibitors against pulmonary vascular remodeling in severe PH.

OBJECTIVE

To investigate whether class I HDAC inhibitors suppress or reverse the development of severe PH in rats.

METHODS

Male Sprague-Dawley rats were injected with a single, subcutaneous dose of monocrotaline (60 mg/kg), and were exposed to chronic hypoxia to induce severe PH. Valproic acid, a class I HDAC inhibitor, was administered to rats daily via gastric gavage (300 mg/kg) in a PH prevention study (during the first 3 weeks) or a PH reversal study (from 3 to 5 weeks). At the end of experiment, hemodynamic indices were measured, ventricular hypertrophy indices were calculated and vascular remodeling phenotypes were analyzed.

RESULTS

After 3 weeks exposure to a combined stimulation of monocrotaline and chronic hypoxia, rats exhibited a reduced body weight, elevated right ventricular systolic pressure, an increased Fulton index, right ventricle weight ratio, medial wall thickness and muscularized peripheral pulmonary arteries. These parameters for PH evaluation were exacerbated from 3 to 5 weeks. Daily administration of valproic acid therapy prevented and partially reversed the development of severe PH in rats, and decreased inflammation and proliferation in remodeled pulmonary arteries.

CONCLUSION

These data show that class I HDAC inhibitors may be effective for treating severe PH.

Prevention of pulmonary hypoplasia and pulmonary vascular remodeling by antenatal simvastatin treatment in nitrofen-induced congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) has a high mortality rate mainly due to lung hypoplasia and persistent pulmonary hypertension of the newborn (PPHN). Simvastatin has been shown to prevent the development of pulmonary hypertension (PH) in experimental models of PH. We, therefore, hypothesized that antenatal simvastatin would attenuate PPHN in nitrofen-induced CDH in rats. The efficacy of antenatal simvastatin was compared with antenatal sildenafil, which has already been shown to improve pathological features of PPHN in nitrofen-induced CDH. On embryonic day (E) 9.5, nitrofen or vehicle was administered to pregnant Sprague-Dawley rats. On E11, nitrofen-treated rats were randomly assigned to antenatal simvastatin (20 mg·kg(-1)·day(-1) orally), antenatal sildenafil (100 mg·kg(-1)·day(-1) orally), or placebo administration from E11 to E21. On E21, fetuses were delivered by cesarean section, killed, and checked for left-sided CDH. Lung tissue was then harvested for further pathobiological evaluation. In nitrofen-induced CDH, simvastatin failed to reduce the incidence of nitrofen-induced CDH in the offspring and to increase the body weight, but improved the lung-to-body weight ratio and lung parenchyma structure. Antenatal simvastatin restored the pulmonary vessel density and external diameter, and reduced the pulmonary arteriolar remodeling compared with nitrofen-induced CDH. This was associated with decreased lung expression of endothelin precursor, endothelin type A and B receptors, endothelial and inducible nitric oxide synthase, together with restored lung activation of apoptotic processes mainly in the epithelium. Antenatal simvastatin presented similar effects as antenatal therapy with sildenafil on nitrofen-induced CDH. Antenatal simvastatin improves pathological features of lung hypoplasia and PPHN in experimental nitrofen-induced CDH.

Targeted delivery of genes to endothelial cells and cell- and gene-based therapy in pulmonary vascular diseases

Pulmonary arterial hypertension (PAH) is a devastating disease that, despite significant advances in medical therapies over the last several decades, continues to have an extremely poor prognosis. Gene therapy is a method to deliver therapeutic genes to replace defective or mutant genes or supplement existing cellular processes to modify disease. Over the last few decades, several viral and nonviral methods of gene therapy have been developed for preclinical PAH studies with varying degrees of efficacy. However, these gene delivery methods face challenges of immunogenicity, low transduction rates, and nonspecific targeting which have limited their translation to clinical studies. More recently, the emergence of regenerative approaches using stem and progenitor cells such as endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) have offered a new approach to gene therapy. Cell-based gene therapy is an approach that augments the therapeutic potential of EPCs and MSCs and may deliver on the promise of reversal of established PAH. These new regenerative approaches have shown tremendous potential in preclinical studies; however, large, rigorously designed clinical studies will be necessary to evaluate clinical efficacy and safety.