Overview of current therapeutic approaches for pulmonary hypertension

Peripheral Microangiopathy Changes in Pulmonary Arterial Hypertension Related to Systemic Sclerosis: Data From a Multicenter Observational Study

Systemic sclerosis (SSc) is a connective tissue disease characterized by immune-system alterations, fibrosis involving the skin and internal organs and diffuse microangiopathy. Pulmonary arterial hypertension (PAH) is a severe complication of SSc affecting about 10–15% of the patients and it is a leading cause of mortality. Due to the devastating nature of SSc-PAH, there is a clear need to systematically adopt appropriate screening programs. Nail fold videocapillaroscopy (NVC) studies have shown a more severe peripheral microvascular dysfunction in SSc patients with PAH suggesting that abnormalities in peripheral microcirculation may correlate with pulmonary microangiopathy. This is a cross-sectional study involving four tertiary University Rheumatology Units in the Center-North of Italy. Seventy patients, 35 adults with SSc and PAH confirmed by RHC (F/M 34/1; median age 65.2 ± 8.9 SD yrs), and 35 SSc patients without PAH were enrolled (F/M 3471; median age 63.3 ± 10.3 SD yrs). Clinical, laboratoristic and instrumental data were collected and NVC was performed in all patient. Specific NVC parameters were evaluated and a semi-quantitative rating scale was adopted to score these changes. Finally, patients were distributed into the suitable NVC pattern belonging to the scleroderma pattern. Our aim was to compare the peripheral microangiopathy changes in SSc patients with and without PAH, and to investigate the relationship between NVC findings and the main hemodynamic parameters of pulmonary vasculopathy. Patients with SSc-PAH+ showed a significant higher frequency of interstitial lung disease (ILD). No significant differences regarding clinical and laboratoristic parameters were observed. NVC abnormalities, avascular areas were more frequent in SSc patients with PAH, respect to those without (p = 0.03), and capillary density was significantly lower when considering grade 3 (p = 0.02). A higher NVC semiquantitative mean was found in SSc-PAH+ patients and a greater rate of the “late” pattern was detected in SSc-PAH+ subjects in respect to PAH- (57.1% vs. 25.7%) (p = 0.03). A significant correlations between pulmonary pressure values (sPAP by TTE and mPAP by RHC) and the capillary density (Spearman's rho 0.35, p = 0.04 for both). Our findings provide additional evidence to the literature data, confirming that a higher degree of peripheral nailfold microangiopathy is more common in SSc-PAH patients, and further strengthening the concept that NVC changes may run parallel with similar abnormalities inside pulmonary microcirculation.

Treprostinil palmitil inhibits the hemodynamic and histopathological changes in the pulmonary vasculature and heart in an animal model of pulmonary arterial hypertension

Treprostinil palmitil (TP) is a long-acting inhaled pulmonary vasodilator prodrug of treprostinil (TRE). In this study, TP was delivered by inhalation (treprostinil palmitil inhalation suspension, TPIS) in a rat Sugen 5416 (Su)/hypoxia (Hx) model of pulmonary arterial hypertension (PAH) to evaluate its effects on hemodynamics, pulmonary vascular remodeling, and cardiac performance and histopathology. Male Sprague-Dawley rats received Su (20 mg/kg, s.c), three weeks of Hx (10% O2) and 5 or 10 weeks of normoxia (Nx). TPIS was given during the 5-10 week Nx period after the Su/Hx challenge. Su/Hx increased the mean pulmonary arterial blood pressure (mPAP) and right heart size (Fulton index), reduced cardiac output (CO), stroke volume (SV) and heart rate (HR), and increased the thickness and muscularization of the pulmonary arteries along with obliteration of small pulmonary vessels. In both the 8- and 13-week experiments, TPIS at inhaled doses ranging from 39.6 to 134.1 μg/kg, QD, dose-dependently improved pulmonary vascular hemodynamics, reduced the increase in right heart size, enhanced cardiac performance, and attenuated most of the histological changes induced by the Su/Hx challenge. The PDE5 inhibitor sildenafil, administered at an oral dose of 50 mg/kg, BID for 10 weeks, was not as effective as TPIS. These results in Su/Hx challenged rats demonstrate that inhaled TPIS may have superior effects to oral sildenafil. We speculate that the improvement of the pathobiology in this PAH model induced by TPIS involves effects on pulmonary vascular remodeling due to the local effects of TRE in the lungs.

Sexual Health-related Quality of Life in Women with Pulmonary Arterial Hypertension: Compensating for Loss

Rationale: Health-related quality of life (HRQoL) in patients with pulmonary arterial hypertension (PAH) has become increasingly important in disease management as numerous treatment options have improved prognosis and time to clinical worsening. Sexual-HRQoL is poorly understood in patients with PAH, but previous work has shown that patients may face unrecognized challenges, especially related to parenteral prostanoid analogue therapies. Objective: Using qualitative methods, describe challenges and perspectives of sexual-HRQoL among women with PAH. Methods: We conducted 13 semi-structured in-depth interviews at the Pulmonary Hypertension Association's International Pulmonary Hypertension (PH) Conference and Scientific Sessions among female attendees with self-reported World Symposium on PH Group 1 PAH. A coding structure using both deductive and inductive coding was developed to organize and analyze data using applied thematic analysis. Salient themes were identified and presented here using summary and illustrative quotes. Results: Ninety-two percent (12/13) of participants reported a decline in frequency of sex after diagnosis with PAH. A significant portion (62%; 8/13) experienced fear of having sexual intercourse due to cardiopulmonary symptoms. All participants (100%; 13/13) reported compensatory behaviors/strategies during and around sexual intercourse; some participants on subcutaneous prostanoids also reported timing intercourse to coincide with infusion site changes and, as a result, interrupted treatment during this time. Participants reported changing positions during sex to reduce breathlessness, and some reported removing oxygen to avoid interrupting intimacy. Most participants endorsed negative body image related to their medications, external oxygen supplementation, and/or body weight fluctuations (54%; 7/13). Many participants revealed they had never discussed sexual practices with a healthcare professional and desired increased communication and discussion with their providers. Conclusions: Women with PAH face significant burdens and challenges regarding sexual-HRQoL. PAH therapies directly impact sexual-HRQoL. Further targeted qualitative and quantitative studies are needed to better characterize and improve sexual-HRQoL in patients with PAH.

How We Would Treat Our Own Pulmonary Hypertension if We Needed to Undergo Cardiac Surgery

Pulmonary hypertension (PH) is a disease that has many etiologies and is particularly prevalent in patients presenting for cardiac surgery, with which it is linked to poor outcomes. This manuscript is intended to provide a comprehensive review of the impact of PH on the perioperative management of patients who are undergoing cardiac surgery. The diagnosis of PH often involves a combination of noninvasive and invasive testing, whereas preoperative optimization frequently necessitates the use of specific medications that affect anesthetic management of these patients. The authors postulate that a thoughtful, multidisciplinary approach is required to deliver excellent perioperative care. Furthermore, they use an index case to illustrate the implications of managing a patient with pulmonary hypertension who presents for cardiac surgery with cardiopulmonary bypass.

Optimal Tricuspid Regurgitation Velocity to Screen for Pulmonary Hypertension in Tertiary Referral Centers

BACKGROUND

A mean pulmonary artery pressure >20 mmHg now defines pulmonary hypertension. We hypothesize that echocardiographic thresholds need to be adjusted.

RESEARCH QUESTION

Should TRV thresholds to screen for PH be revised given the new hemodynamic definition?

STUDY DESIGN AND METHODS

This multicenter retrospective study included 1,608 patients that underwent both echocardiography and right heart catherization within four weeks. The discovery cohort consisted of 1,081 individuals and the validation cohort included 527. Screening criteria for pulmonary hypertension were derived using receiver operating characteristic analysis and the Youden index assuming equal cost for false positive and negative classification. A lower threshold was calculated using a predefined sensitivity: 95%.

RESULTS

In the discovery cohort, echocardiographic tricuspid regurgitation velocity had a good discrimination for pulmonary hypertension, AUC 88.4 (95% CI, 85.3-91.5). A 3.4 m/s threshold provided a 78% sensitivity, 87% specificity, and 6.13 positive likelihood ratio to detect pulmonary hypertension. 2.7 m/s had a 95% sensitivity and 0.12 negative likelihood ratio to exclude pulmonary hypertension. In the validation cohort, the discovery threshold of 2.7 m/s provided a sensitivity and negative likelihood ratio of 80% and 0.34, respectively. Right cardiac size improved detection of pulmonary hypertension in the lower tricuspid regurgitation velocity groups.

INTERPRETATION

Our data support a lower tricuspid regurgitation velocity around 2.7 m/s for screening pulmonary hypertension with a high sensitivity in tertiary referral centers. Right heart chamber measurements improve the diagnostic yield of echocardiography.

Dual-Functional MN-08 Attenuated Pulmonary Arterial Hypertension Through Vasodilation and Inhibition of Pulmonary Arterial Remodeling

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Inhibition of Mitogen-Activated Protein Kinase (MAPK)-Activated Protein Kinase 2 (MK2) is Protective in Pulmonary Hypertension

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An overview of the biology of a long-acting inhaled treprostinil prodrug

Treprostinil (TRE) is a prostanoid analog pulmonary vasodilator drug marketed with subcutaneous, intravenous (i.v.), oral, and inhaled routes of administration for the treatment of pulmonary arterial hypertension (PAH). Due to its short half-life, TRE requires either continuous infusion or multiple dosing, which exacerbates its side effects. Therefore, a long-acting prostanoid analog that maintains the positive attributes of TRE but has fewer TRE-related side effects could be of clinical benefit. In this report, we describe the discovery, preclinical development, and biology of the TRE ester prodrug, treprostinil palmitil (TP), which is formulated in a lipid nanoparticle (LNP) for administration as a nebulized inhaled suspension (TPIS). In screening assays focused on the conversion of prodrug to TRE, TP (16 carbon alkyl chain) had the slowest rate of conversion compared with short-alkyl chain TRE prodrugs (i.e., 2-8 carbon alkyl chain). Furthermore, TP is a pure prodrug and possesses no inherent binding to G-protein coupled receptors including prostanoid receptors. Pharmacokinetic studies in rats and dogs demonstrated that TPIS maintained relatively high concentrations of TP in the lungs yet had a low maximum plasma concentrations (C_max) of both TP and, more importantly, the active product, TRE. Efficacy studies in rats and dogs demonstrated inhibition of pulmonary vasoconstriction induced by exposure to hypoxic air or i.v.-infused U46619 (thromboxane mimetic) over 24 h with TPIS. Cough was not observed with TPIS at an equivalent dose at which TRE caused cough in guinea pigs and dogs, and there was no evidence of desensitization to the inhibition of pulmonary vasoconstriction in rats with repeat inhaled dosing. TPIS was also more efficacious than i.v.-infused TRE in a sugen/hypoxia rat model of PAH to inhibit pulmonary vascular remodeling, an effect likely driven by local activities of TRE within the lungs. TPIS also demonstrated antifibrotic and anti-inflammatory activity in the lungs in rodent models of pulmonary fibrosis and asthma. In a phase 1 study in healthy human participants, TPIS (referred to as INS1009) had a lower plasma TRE C_max and fewer respiratory-related side effects at equimolar doses compared with inhaled TRE. We have now formulated TP as an aerosol powder for delivery by a dry powder inhaler (referred to as treprostinil palmitil inhalation powder-TPIP), and as an aerosol solution in a fluorohydrocarbon solvent for delivery by a metered dose inhaler. These options may reduce drug administration time and involve less device maintenance compared with delivery by nebulization.

Unrecognized pulmonary arterial hypertension in hospitalized patients

Pulmonary hypertension (PH) is an underdiagnosed and potentially fatal condition. The utility of screening for PH in hospitalized patients undergoing echocardiography is unknown. The goal of this study was to determine the prevalence of undiagnosed pulmonary hypertension (PH) and probable pulmonary arterial hypertension (PAH) in hospitalized patients undergoing echocardiography for any indication. All hospitalized patients undergoing echocardiography were identified and echocardiographs reviewed prospectively for the presence of a tricuspid regurgitant (TR) jet. Electronic medical records (EMR) of patients with a TR jet ≥ 3 m/s were reviewed for identifiable causes of pulmonary hypertension. Patients with no identifiable cause were classified as presumptive World Health Organization (WHO) Group 1 PH (also known as PAH). These PAH patients were compared to other PH patients for baseline demographic characteristics and comorbidities as well as 30-day readmission and mortality. The admitting physicians of patients classified as PH were advised to consider further evaluation including right heart catheterization. We reviewed 4417 consecutive echocardiograms and identified 448 with a TR jet ≥ 3 m/s. Of these 448 patients with PH, 47 were identified as "presumptive PAH" and the other 401 as having PH belonging to WHO Groups 2-5. Presumptive PAH represented 1% of screened echocardiograms and 10.5% of those identified to have an elevated TR jet. Of the patients identified as presumptive PAH, 8 underwent further evaluation including a right heart catheterization, where 5 were confirmed to have PAH. Kaplan-Meier analysis revealed 30-day readmission was higher among those classified as PAH. Our data shows that pulmonary hypertension, as defined by TR jet ≥ 3 m/s, is frequently encountered in hospitalized patients undergoing echocardiography for any reason. A careful review of echocardiogram findings and clinical history suggested 10.5% of those with PH (and 1% of all screened patients) may meet the criteria for PAH. Considering PH is a fatal condition which is frequently missed, a hospital screening program seems feasible.

Current and emerging therapeutic approaches to pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a progressive and fatal lung disease of multifactorial etiology. Most of the available drugs and FDA-approved therapies for treating pulmonary hypertension attempt to overcome the imbalance between vasoactive and vasodilator mediators, and restore the endothelial cell function. Traditional medications for treating PAH include the prostacyclin analogs and receptor agonists, phosphodiesterase 5 inhibitors, endothelin-receptor antagonists, and cGMP activators. While the current FDA-approved drugs showed improvements in quality of life and hemodynamic parameters, they have shown only very limited beneficial effects on survival and disease progression. None of them offers a cure against PAH, and the median survival rate remains less than three years from diagnosis. Extensive research efforts have led to the emergence of innovative therapeutic approaches in the area of PAH. In this review, we provide an overview of the current FDA-approved therapies in PAH and discuss the associated clinical trials and reported-side effects. As recent studies have led to the emergence of innovative therapeutic approaches in the area of PAH, we also focus on the latest promising therapies in preclinical studies such as stem cell-based therapies, gene transfer, and epigenetic therapies.

Remodulin® Pump Failure: An Emergency Medicine Simulation Scenario

Pulmonary hypertension (PH) is a progressive disease that causes high patient mortality. With limited hemodynamic reserve, many PH patients require maintenance IV infusion medications to maintain their activities of daily living. One common delivery method for this targeted therapy is through a Remodulin® (treprostinil) pump. When presenting for emergent evaluation, decompensating PH patients have a broad differential diagnosis including pump failure. PH patients are at a high risk of poor patient outcomes given the difficulty in recognizing PH-specific symptoms and unique aspects of their management. Therefore, learners will benefit from participating in an immersive simulation-based PH patient scenario in a safe learning environment. Here, we present a simulated scenario of a decompensating PH patient on a Remodulin® pump.

Comparison of inhaled nitric oxide with aerosolized prostacyclin or analogues for the postoperative management of pulmonary hypertension: a systematic review and meta-analysis

Background: This study aims to compare the effectiveness of inhaled prostacyclin or its analoguesversus nitric oxide (NO) in treating pulmonary hypertension (PH) after cardiac or pulmonary surgery remains unclear.Methods: PubMed, Cochrane, and Embase databases were searched for literature published prior to December 2019 using the following keywords: inhaled, nitric oxide, prostacyclin, iloprost, treprostinil, epoprostenol, Tyvaso, flolan, and pulmonary hypertension. Randomized controlled trials and multiple-armed prospective studies that evaluated inhaled NO versus prostacyclin (or analogues) in patients for perioperative and/or postoperative PH after either cardiac or pulmonary surgery were included. Retrospective studies, reviews, letters, comments, editorials, and case reports were excluded.Results: Seven studies with a total of 195 patients were included. No difference in the improvement of mean pulmonary arterial pressure (pooled difference in mean change= -0.10, 95% CI: -3.98 to 3.78, p = .959) or pulmonary vascular resistance (pooled standardized difference in mean change= -0.27, 95% CI: -0.60 to 0.05, p = .099) were found between the two treatments. Similarly, no difference was found in other outcomes between the two treatments or subgroup analysis.Conclusions: Inhaled prostacyclin (or analogues) was comparable to inhaled NO in treating PH after cardiac or pulmonary surgery.Key messagesThis study compared the efficacy of inhaled prostacyclin or its analogues versus inhaled NO to treat PH after surgery. The two types of agent exhibited similar efficacy in managing MPAP, PVR, heart rate, and cardiac output was observed.Inhaled prostacyclin may serve as an alternative treatment option for PH after cardiac or pulmonary surgery.

Circulating Plasma Metabolomic Profiles Differentiate Rodent Models of Pulmonary Hypertension and Idiopathic Pulmonary Arterial Hypertension Patients

BACKGROUND

Pulmonary arterial hypertension (PAH) is a severe progressive disease with systemic metabolic dysregulation. Monocrotaline (MCT)-induced and hypoxia-induced pulmonary hypertension (PH) rodent models are the most widely used preclinical models, however, whether or not these preclinical models recapitulate metabolomic profiles of PAH patients remain unclear.

METHODS

In this study, a targeted metabolomics panel of 126 small molecule metabolites was conducted. We applied it to the plasma of the 2 preclinical rodent models of PH and 30 idiopathic pulmonary arterial hypertension (IPAH) patients as well as 30 healthy controls to comparatively assess the metabolomic profiles of PAH patients and rodent models.

RESULTS

Significantly different metabolomics profiling and pathways were shown among the 2 classical rodent models and IPAH patients. Pathway analysis demonstrated that methionine metabolism and urea cycle metabolism were the most significant pathway involved in the pathogenesis of hypoxia-induced PH model and MCT-induced model, respectively, and both of them were also observed in the dysregulated pathways in IPAH patients.

CONCLUSIONS

These 2 models may develop PAH through different metabolomic pathways and each of the 2 classical PH model resembles IPAH patients in certain aspects.

LncRNA H19 promotes the proliferation of pulmonary artery smooth muscle cells through AT1R via sponging let-7b in monocrotaline-induced pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is related to inflammation, and the lncRNA H19 is associated with inflammation. However, whether PDGF-BB-H19-let-7b-AT1R axis contributes to the pathogenesis of PAH has not been thoroughly elucidated to date. This study investigated the role of H19 in PAH and its related mechanism.

METHODS

In the present study, SD rats, C57/BL6 mice and H19-/- mice were injected with monocrotaline (MCT) to establish a PAH model. H19 was detected in the cytokine-stimulated pulmonary arterial smooth muscle cells (PASMCs), serum and lungs of rats/mice. H19 overexpression and knockdown experiments were also conducted. A dual luciferase reporter assay was used to explore whether let-7b is a sponge miRNA of H19, and AT1R is a novel target of let-7b. A CCK-8 assay and flow cytometry were used to analyse cell proliferation.

RESULTS

The results showed that H19 was highly expressed in the serum and lungs of MCT-induced rats/mice, and H19 was upregulated by PDGF-BB in vitro. H19 upregulated AT1R expression via sponging miRNA let-7b following PDGF-BB stimulation. AT1R is a novel target of let-7b. Moreover, the overexpression of H19 and AT1R could facilitate PASMCs proliferation in vitro. H19 knockout protected mice from pulmonary artery remodeling and PAH following MCT treatment.

CONCLUSION

Our study showed that H19 is highly expressed in MCT-induced rodent lungs and upregulated by PDGF-BB. The H19-let-7b-AT1R axis contributed to the pathogenesis of PAH by stimulating PASMCs proliferation. The H19 knockout had a protective role in the development of PAH. H19 may be a potential tar-get for the treatment of PAH.

Ambrisentan: a review of its use in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive disease defined by an elevation in pulmonary arterial pressure that can lead to right heart failure and death. Ambrisentan is a selective endothelin receptor antagonist approved for the treatment of idiopathic, heritable PAH and connective tissue disease-associated PAH. Ambrisentan has been shown to improve exercise capacity and hemodynamics with an acceptable side-effect profile. It has also proven to be safely used in combination with other PAH-specific medications, especially with phosphodiesterase-5 inhibitors. In the recent randomized trial, AMBITION, it was shown that upfront combination therapy of ambrisentan and tadalafil significantly decreased the risk of clinical failure compared with monotherapy. This review describes the drug profile of ambrisentan and its safety and efficacy in the treatment of PAH.

Pulmonary Hypertension and Cancer: Etiology, Diagnosis, and Management

OPINION STATEMENT

Pulmonary hypertension is caused by cancer and its therapeutic agents including chemotherapy, radiotherapy, and even the targeted therapies. Ironically, some of the cancer therapies that cause one type of pulmonary hypertension (PH) could potentially be employed in the treatment of another PH type. Greater awareness on the role of cancer therapeutic agents in causing PH is required. Conversely, since PH is mostly incurable, the potential role of some of these cancer therapeutic agents in the cure of PH should be recognized. In short, the relationship between cancer, cancer therapy, and PH is an interesting one requiring further attention, education, and research.

Expression and analyses of the HIF-1 pathway in the lungs of humans with pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is characterized by endothelial dysfunction and structural remodeling of the pulmonary vasculature, mediated initially by reduced oxygen availability in the lungs. Hypoxia inducible factor (HIF), consisting of the functional subunit, HIF‑1α, and the constitutively expressed HIF‑1β, is involved in the pathological processes associated with hypoxia. In the current study, the sequences of cDNAs and amino acids of HIF were characterized and analyzed using online bioinformatics tools. To further evaluate whether HIF accounts for the occurrence of PAH, the present study determine the expression and phosphorylation levels of HIF and its associated pathways, including extracellular signal‑regulated kinase (Erk)1/2 and phosphoinositide 3‑kinase (PI3K)/Akt, in the lungs of patients with PAH by reverse transcription‑quantitative polymerase chain reaction and western blotting. The mRNA expression levels of PI3K, Erk2, and HIF‑1α in the patients with PAH were significantly higher, compared with those in the control group, by 3.6‑fold (P<0.01), 4.06‑fold and 2.64‑fold (P<0.05), respectively. No significant differences were found in the mRNA and protein levels of Akt between the two groups (P>0.05). The protein levels of phosphorylated (p‑)Akt, Erk1/2, p‑Erk1/2, HIF‑1α and HIF‑1β were significantly increased by 5.89‑, 0.5‑, 0.59‑, 1.46‑ and 0.92‑fold, respectively, in the patients with PAH, compared with those in the controls group (P<0.01 for p‑Akt, Erk1/2; P<0.05 for p‑Erk1/2, HIF‑1α and HIF‑1β). These findings suggested that the mitogen‑activated protein kinase and PI3K/Akt signaling pathways, and HIF‑1 may perform a specific function in the pathogenesis of PAH.

Thymosin Beta 4 protects mice from monocrotaline-induced pulmonary hypertension and right ventricular hypertrophy

Pulmonary hypertension (PH) is a progressive vascular disease of pulmonary arteries that impedes ejection of blood by the right ventricle. As a result there is an increase in pulmonary vascular resistance and pulmonary arterial pressure causing right ventricular hypertrophy (RVH) and RV failure. The pathology of PAH involves vascular cell remodeling including pulmonary arterial endothelial cell (PAEC) dysfunction and pulmonary arterial smooth muscle cell (PASMC) proliferation. Current therapies are limited to reverse the vascular remodeling. Investigating a key molecule is required for development of new therapeutic intervention. Thymosin beta-4 (Tβ4) is a ubiquitous G-actin sequestering protein with diverse biological function and promotes wound healing and modulates inflammatory responses. However, it remains unknown whether Tβ4 has any protective role in PH. The purpose of this study is to evaluate the whether Tβ4 can be used as a vascular-protective agent. In monocrotaline (MCT)-induced PH mouse model, we showed that mice treated with Tβ4 significantly attenuated the systolic pressure and RVH, compared to the MCT treated mice. Our data revealed for the first time that Tβ4 selectively targets Notch3-Col 3A-CTGF gene axis in preventing MCT-induced PH and RVH. Our study may provide pre-clinical evidence for Tβ4 and may consider as vasculo-protective agent for the treatment of PH induced RVH.

The peroxisome proliferator-activated receptor β/δ agonist GW0742 has direct protective effects on right heart hypertrophy

Pulmonary hypertension is a debilitating disease with no cure. We have previously shown that peroxisome proliferator-activated receptor (PPAR) β/δ agonists protect the right heart in hypoxia-driven pulmonary hypertension without affecting vascular remodeling. PPARβ/δ is an important receptor in lipid metabolism, athletic performance, and the sensing of prostacyclin. Treatment of right heart hypertrophy and failure in pulmonary hypertension is an emerging target for future therapy. Here we have investigated the potential of GW0742, a PPARβ agonist, to act directly on the right heart in vivo and what transcriptomic signatures are associated with its actions. Right heart hypertrophy and failure was induced in mice using a pulmonary artery banding (PAB) model. GW0742 was administered throughout the study. Cardiovascular parameters were measured using echocardiography and pressure monitoring. Fibrosis and cellular changes were measured using immunohistochemistry. Transcriptomics were measured using the Illumina MouseRef-8v3 BeadChip array and analyzed using GeneSpring GX (ver. 11.0). PAB resulted in right heart hypertrophy and failure and in increased fibrosis. GW0742 reduced or prevented the effects of PAB on all parameters measured. GW0742 altered a number of genes in the transcriptome, with Angptl4 emerging as the top gene altered (increased) in animals with PAB. In conclusion, the PPARβ/δ agonist GW0742 has direct protective effects on the right heart in vivo. These observations identify PPARβ/δ as a viable therapeutic target to treat pulmonary hypertension that may complement current and future vasodilator drugs.

Upregulated copper transporters in hypoxia-induced pulmonary hypertension

Pulmonary vascular remodeling and increased arterial wall stiffness are two major causes for the elevated pulmonary vascular resistance and pulmonary arterial pressure in patients and animals with pulmonary hypertension. Cellular copper (Cu) plays an important role in angiogenesis and extracellular matrix remodeling; increased Cu in vascular smooth muscle cells has been demonstrated to be associated with atherosclerosis and hypertension in animal experiments. In this study, we show that the Cu-uptake transporter 1, CTR1, and the Cu-efflux pump, ATP7A, were both upregulated in the lung tissues and pulmonary arteries of mice with hypoxia-induced pulmonary hypertension. Hypoxia also significantly increased expression and activity of lysyl oxidase (LOX), a Cu-dependent enzyme that causes crosslinks of collagen and elastin in the extracellular matrix. In vitro experiments show that exposure to hypoxia or treatment with cobalt (CoCl2) also increased protein expression of CTR1, ATP7A, and LOX in pulmonary arterial smooth muscle cells (PASMC). In PASMC exposed to hypoxia or treated with CoCl2, we also confirmed that the Cu transport is increased using 64Cu uptake assays. Furthermore, hypoxia increased both cell migration and proliferation in a Cu-dependent manner. Downregulation of hypoxia-inducible factor 1α (HIF-1α) with siRNA significantly attenuated hypoxia-mediated upregulation of CTR1 mRNA. In summary, the data from this study indicate that increased Cu transportation due to upregulated CTR1 and ATP7A in pulmonary arteries and PASMC contributes to the development of hypoxia-induced pulmonary hypertension. The increased Cu uptake and elevated ATP7A also facilitate the increase in LOX activity and thus the increase in crosslink of extracellular matrix, and eventually leading to the increase in pulmonary arterial stiffness.

Circulating miRNAs as potential marker for pulmonary hypertension

MircoRNAs (miRNAs) are small non-coding RNAs that govern the gene expression and, play significant role in the pathogenesis of heart failure. The detection of miRNAs in circulation of pulmonary hypertensive (PH) human subjects remains elusive. In the current study, we determined the pattern of miRNAs of mild-to-severe human PH subjects and, compared them with the control subjects by miRNA array. Blood was obtained using fluoroscopic and waveform guided catheterization from the distal (pulmonary artery) port of the catheter. A total 40 human subjects were included in the study and, the degree of PH was determined by mean pulmonary arterial pressure. Among several miRNAs in the array, we validated 14 miRNAs and, the data were consistent with the array profile. We identified several novel downregulated miRNAs (miR-451, miR-1246) and upregulated miRNAs (miR-23b, miR-130a and miR-191) in the circulation of PH subjects. Our study showed novel set of miRNAs which are dysregulated in PH and, are directly proportional to the degree of PH. These miRNAs may be considered as potential biomarker for early detection of PH.