New pharmacotherapy options for pulmonary arterial hypertension

Single-cell microencapsulation improves lung retention of endothelial colony-forming cells after intravascular delivery and unmasks therapeutic benefit in severe pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is triggered by pulmonary vascular endothelial cell apoptosis and microvascular loss. Therefore, therapies that can regenerate lost vasculature may offer therapeutic benefit. Endothelial colony-forming cells (ECFCs) can directly repair damaged blood vessels and may have therapeutic potential for the treatment of PAH. However, poor retention of ECFCs in the lungs following intravenous delivery greatly limits their therapeutic application. Therefore, we studied whether cellular microencapsulation could enhance retention in the lung after systemic delivery and improve therapeutic efficacy of ECFCs in a rat monocrotaline (MCT) PAH model. ECFCs were encapsulated by vortex emulsion using various concentrations of agarose, and initial cell viability was assessed. Encapsulated and free ECFCs were transduced with luciferase and administered to Sprague-Dawley rats 3 days after injection of MCT. In vivo ECFC persistence and bio-distribution was assessed by bioluminescence imaging (BLI). At the end of the study, right ventricular systolic pressure (RVSP) and right ventricular hypertrophy were assessed for therapeutic efficacy. Microgel encapsulation using 3.5% agarose improved cell survival and supported cell migration from capsules. At 15 minutes after delivery, BLI radiance was similar for free and microencapsulated ECFCs. However, only encapsulated cells could be detected by BLI at 4 and 24 hours. Transplantation of microencapsulated ECFCs led to significant improvement in RVSP 3 weeks after delivery compared with nonencapsulated ECFCs. Together, microencapsulation increased retention of ECFCs within the lungs. Furthermore, even a modest increase in ECFC persistence over 24 hours can provide an important therapeutic benefit in the rat MCT model of PAH.

Resveratrol: Mechanistic and therapeutic perspectives in pulmonary arterial hypertension

Resveratrol, trans 3,5,4'-trihydroxystilbene, is a stilbenoid polyphenol with a wide range of properties including antioxidant, neuroprotective, cardioprotective, anti-inflammatory and anticancer activities. It is found in the skins of grape (50-100 μg/mL), red wine, peanuts, bilberries, blueberries and cranberries. The most important effects of resveratrol have been found in cardiovascular disease, with pulmonary arterial hypertension (PAH) being a major severe and progressive component. Many factors are involved in the pathogenesis of PAH, including enzymes, transcription factors, proteins, chemokines, cytokines, hypoxia, oxidative stress and others. Resveratrol treats PAH through its actions on various signaling pathways. These signaling pathways are mainly suppressed SphK1-mediated NF-κB activation, BMP/SMAD signaling pathway, miR-638 and NR4A3/cyclin D1 pathway, SIRT1 pathway, Nrf-2, HIF-1 α expression, MAPK/ERK1 and PI3K/AKT pathways, and RhoA-ROCK signaling pathway. Resveratrol efficiently inhibits the proliferation of pulmonary arterial smooth muscle cells and right ventricular remodeling, which are underlying processes leading to enhanced PAH. While supportive evidence from randomized controlled trials is yet to be available, current in vitro and in vivo studies seem to be convincing and suggest a therapeutic promise for the use of resveratrol in PAH.

Conditioned medium from M2b macrophages modulates the proliferation, migration, and apoptosis of pulmonary artery smooth muscle cells by deregulating the PI3K/Akt/FoxO3a pathway

Background

Immunity and inflammation are considered to be central features of pulmonary artery hypertension (PAH), in which macrophages are one of the main components of inflammatory cell infiltration around the pulmonary artery. M2b macrophages, which are different from M1 and M2 macrophages, are believed to have immunomodulatory activities and produce little fibrosis. The purpose of this study was to explore the effect of M2b macrophages on pulmonary artery smooth muscle cells (PASMCs) derived from monocrotaline-induced PAH rats.

Methods

PASMCs were cultured in serum-free medium, the supernatant of M0 macrophages, or the supernatant of M2b macrophages for 24 hours. Then cell proliferation was assessed by cell counting kit-8 and cell migration ability was detected by wound healing and transwell assays. The apoptosis rate of cells was determined by TUNEL staining and annexin V-PE/7-ADD staining. Western blot was used to detect the expression of Bcl-2 family proteins, cleaved caspase-9 and PI3K/Akt/FoxO3a pathway. LY294002 (a specific inhibitor of PI3K) was used to investigate its effect on PASMCs and its relationship with M2b macrophages.

Results

Conditioned medium from M2b macrophages significantly inhibited the proliferation and migration of PASMCs compared with the control group and M0 macrophage group. Furthermore, conditioned medium from M2b macrophages promote PASMC apoptosis and increased the expression of pro-apoptotic proteins Bax and cleaved caspase-9, inhibited the expression of anti-apoptotic proteins Bcl-2 and Bcl-xl. Finally, conditioned medium from M2b macrophages inhibited the PI3K/Akt/FoxO3a pathway. Inhibition of PI3K/Akt/FoxO3a pathway also significantly inhibit the proliferation, migration, and apoptosis resistance of PASMCs.

Conclusion

Conditioned medium from M2b macrophages can inhibit the proliferation, migration, and apoptosis resistance of PASMCs, which may be at least partially by deregulating the PI3K/Akt/FoxO3a pathway.

Protective effects of resveratrol and SR1001 on hypoxia-induced pulmonary hypertension in rats

Hypoxic pulmonary hypertension (HPH) is a fatal disease with limited therapeutic strategies. Combination therapy is regarded as the standard of care in PH and becoming widely used in clinical practice. However, many PH patients treated with combinations of available clinical drugs still have a poor prognosis. Therefore, identifying innovative therapeutic strategies is essential for PH. This study is designed to examine the effects of combined prevention with resveratrol and SR1001 on HPH in rats. The effects of combined prevention with resveratrol and SR1001 and each mono-prevention on the development of HPH, Th17 cells differentiation, expression of guanine nucleotide exchange factor-H1 (GEF-H1), Ras homolog gene family member A (RhoA) and Phosphorylated myosin phosphatase target subunit (MYPT1) were examined. HPH and RV hypertrophy occurred in rats exposed to hypoxia. Compared with normoxia group, the hypoxia group showed significantly increased ratio of Th17 cells. After treatment with resveratrol, HPH rats showed an obvious reduction of Th17 cells. SR1001 significantly reduced the increased p-MYPY1, RhoA, and GEF-H1 expression in the hypoxic rats. The mono-prevention with resveratrol or SR1001 significantly inhibited the Th17 cells differentiation, p-STAT3, p-MYPY1, RhoA, and GEF-H1 protein expression, which was further inhibited by their combination prevention. The combination of resveratrol and SR1001 has a synergistic interaction, suggesting that combined use of these pharmacological targets may be an alternative to exert further beneficial effects on HPH.

Role of miR-223-3p in pulmonary arterial hypertension via targeting ITGB3 in the ECM pathway

Objectives

To investigate the functions of miR‐223‐3p and ITGB3 in pulmonary arterial hypertension (PAH).

Materials and Methods

Microarray analysis was used to detect differentially expressed genes and microRNAs. In in vitro models, the expressions of miR‐223‐3p and ITGB3 were detected by qRT‐PCR and Western blot. α‐SMA expression and cell proliferation were analysed by immunofluorescence and MTT assay, respectively. In in vivo models, PAH progressions were determined by measuring the levels of mPAP and RVSP. Lung and myocardial tissues were subjected to HE staining and Masson and Sirius red‐saturated carbazotic acid staining to investigate the pathological features.

Results

The microarray analysis revealed that ITGB3 was upregulated, while hsa‐miR‐223‐3p was downregulated in PAH. After the induction of hypoxia, miR‐223‐3p was downregulated and ITGB3 was upregulated in PASMCs. Hypoxia induction promoted cell proliferation and inhibited α‐SMA expression in PASMCs. Both the upregulation of miR‐223‐3p and the downregulation of ITGB3 attenuated the aberrant proliferation induced by hypoxia conditions. After approximately 4 weeks, the mPAP and RVSP levels of rats injected with MCT were decreased by the overexpression of miR‐223‐3p or the silencing of ITGB3. The staining results revealed that both miR‐223‐3p overexpression and ITGB3 knockdown alleviated the pulmonary vascular remodelling and improved the PAH pathological features of rats.

Conclusions

MiR‐223‐3p alleviated the progression of PAH by suppressing the expression of ITGB3, a finding which provides novel targets for clinical treatment.

Diagnosis and management of PNH: Review and recommendations from a Belgian expert panel

Despite its considerable morbidity and mortality, paroxysmal nocturnal haemoglobinuria (PNH) is still underdiagnosed. Patients with PNH can suffer from cardiovascular, gastrointestinal, neurological or haematological symptoms and refer to several specialists. The aim of this paper is to review the diagnosis and the management of PNH patients, with the primary focus on identifying high-risk groups. Additionally, the implementation and prognostic value of the defined high-risk groups will be commented on and the management of PNH patients is discussed from a Belgian perspective. Finally, based on the available data, recommendations are provided. Eculizumab is a potent C5 complement inhibitor and reduces intravascular haemolysis and thrombosis in PNH patients and improves their quality of life. As thrombosis is the main cause of death in PNH patients, identifying high-risk PNH patients in need of therapy is essential. Currently, novel complement inhibitors are in development and the first data seem promising. Another challenge in PNH is to identify new markers to assess the thrombotic risk to achieve a better risk-based prophylactic anti-thrombotic management. Finally, because of the low prevalence of the disease, PNH patients should be included in the prospective PNH registry, which will offer new insights on the natural course of the disease and the impact of treatment of PNH.

Iloprost attenuates hyperoxia-mediated impairment of lung development in newborn mice

Cyclooxygenase-2 (COX-2/PTGS2) mediates hyperoxia-induced impairment of lung development in newborn animals and is increased in the lungs of human infants with bronchopulmonary dysplasia (BPD). COX-2 catalyzes the production of cytoprotective prostaglandins, such as prostacyclin (PGI2), as well as proinflammatory mediators, such as thromboxane A2. Our objective was to determine whether iloprost, a synthetic analog of PGI2, would attenuate hyperoxia effects in the newborn mouse lung. To test this hypothesis, newborn C57BL/6 mice along with their dams were exposed to normoxia (21% O2) or hyperoxia (85% O2) from 4 to 14 days of age in combination with daily intraperitoneal injections of either iloprost 200 µg·kg-1·day-1, nimesulide (selective COX-2 antagonist) 100 mg·kg-1·day-1, or vehicle. Alveolar development was estimated by radial alveolar counts and mean linear intercepts. Lung function was determined on a flexiVent, and multiple cytokines and myeloperoxidase (MPO) were quantitated in lung homogenates. Lung vascular and microvascular morphometry was performed, and right ventricle/left ventricle ratios were determined. We determined that iloprost (but not nimesulide) administration attenuated hyperoxia-induced inhibition of alveolar development and microvascular density in newborn mice. Iloprost and nimesulide both attenuated hyperoxia-induced, increased lung resistance but did not improve lung compliance that was reduced by hyperoxia. Iloprost and nimesulide reduced hyperoxia-induced increases in MPO and some cytokines (IL-1β and TNF-α) but not others (IL-6 and KC/Gro). There were no changes in pulmonary arterial wall thickness or right ventricle/left ventricle ratios. We conclude that iloprost improves lung development and reduces lung inflammation in a newborn mouse model of BPD.

Inflammatory Macrophage Expansion in Pulmonary Hypertension Depends upon Mobilization of Blood-Borne Monocytes

Pulmonary inflammation, which is characterized by the presence of perivascular macrophages, has been proposed as a key pathogenic driver of pulmonary hypertension (PH), a vascular disease with increasing global significance. However, the mechanisms of expansion of lung macrophages and the role of blood-borne monocytes in PH are poorly understood. Using multicolor flow cytometric analysis of blood in mouse and rat models of PH and patients with PH, an increase in blood monocytes was observed. In parallel, lung tissue displayed increased chemokine transcript expression, including those responsible for monocyte recruitment, such as Ccl2 and Cx₃cl1, accompanied by an expansion of interstitial lung macrophages. These data indicate that blood monocytes are recruited to lung perivascular spaces and differentiate into inflammatory macrophages. Correspondingly, parabiosis between congenically different hypoxic mice demonstrated that most interstitial macrophages originated from blood monocytes. To define the actions of these cells in PH in vivo, we reduced blood monocyte numbers via genetic deficiency of cx₃cr1 or ccr2 in chronically hypoxic male mice and by pharmacologic inhibition of Cx₃cl1 in monocrotaline-exposed rats. Both models exhibited decreased inflammatory blood monocytes, as well as interstitial macrophages, leading to a substantial decrease in arteriolar remodeling but with a less robust hemodynamic effect. This study defines a direct mechanism by which interstitial macrophages expand in PH. It also demonstrates a pathway for pulmonary vascular remodeling in PH that depends upon interstitial macrophage-dependent inflammation yet is dissociated, at least in part, from hemodynamic consequences, thus offering guidance on future anti-inflammatory therapeutic strategies in this disease.

Global Proteomics Deciphered Novel-Function of Osthole Against Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a progressive cardiovascular-disease with high mortality lacking high-efficiency drug. Our efforts attempted to delineate therapeutic action of osthole produced by Angelica Pubescens Maxim, which has the capacity to treat PAH by exploiting an iTRAQ-based proteomic method. Excitingly, osthole was observed to significantly restore 98 of 315 differential proteins significantly modified by PAH progression. They were primarily annotated into 24 signaling pathways. Four mostly affected proteins (RPL15, Cathepsin S, Histone H3.3 and HMGB1) were experimentially validated which belonged to ribosome pathway, oxidative phosphorylation pathway, systemic lupus erythematosus pathway, complement and coagulation cascades pathway, whose modifications and modulations mostly accounted for therapeutic capacity of this compound against PAH. Altogether, our findings demonstrated that global proteomics is a promising systems-biology approach for deciphering therapeutic actions and associated mechanisms of natural products derived from traditional Chinese medicine. Importantly, osthole is supposed to be a candidate compound for new drug development to treat PAH.

Origin and production of inflammatory perivascular macrophages in pulmonary hypertension

Myeloid cells, including monocytes and macrophages participate in steady state immune homeostasis and help mount the adaptive immune response during infection. The function and production of these cells in sterile inflammation, such as pulmonary hypertension (PH), is understudied. Emerging data indicate that pulmonary inflammation mediated by lung perivascular macrophages is a key pathogenic driver of pulmonary remodeling leading to increased right ventricular systolic pressure (RVSP). However, the origin of these macrophages in pulmonary inflammation is unknown. Inflammatory monocytes, the precursors of pathogenic macrophages, are derived from hematopoietic stem and progenitor cells (HSPC) in the bone marrow and spleen during acute and chronic inflammation. Understanding the role of these organs in monocytopoiesis, and the mechanisms of HSPC proliferation and differentiation in PH are important to discover therapeutic targets curbing inflammation. This review will summarize the current limited knowledge of the origin of lung macrophage subsets and over-production of inflammatory monocytes in PH.

BMP type II receptor as a therapeutic target in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic disease characterized by a progressive elevation in mean pulmonary arterial pressure. This occurs due to abnormal remodeling of small peripheral lung vasculature resulting in progressive occlusion of the artery lumen that eventually causes right heart failure and death. The most common cause of PAH is inactivating mutations in the gene encoding a bone morphogenetic protein type II receptor (BMPRII). Current therapeutic options for PAH are limited and focused mainly on reversal of pulmonary vasoconstriction and proliferation of vascular cells. Although these treatments can relieve disease symptoms, PAH remains a progressive lethal disease. Emerging data suggest that restoration of BMPRII signaling in PAH is a promising alternative that could prevent and reverse pulmonary vascular remodeling. Here we will focus on recent advances in rescuing BMPRII expression, function or signaling to prevent and reverse pulmonary vascular remodeling in PAH and its feasibility for clinical translation. Furthermore, we summarize the role of described miRNAs that directly target the BMPR2 gene in blood vessels. We discuss the therapeutic potential and the limitations of promising new approaches to restore BMPRII signaling in PAH patients. Different mutations in BMPR2 and environmental/genetic factors make PAH a heterogeneous disease and it is thus likely that the best approach will be patient-tailored therapies.

Discerning functional hierarchies of microRNAs in pulmonary hypertension

Pulmonary hypertension (PH) is a multifaceted vascular disease where development and severity are determined by both genetic and environmental factors. Over the past decade, there has been an acceleration of the discovery of molecular effectors that mediate PH pathogenesis, including large numbers of microRNA molecules that are expressed in pulmonary vascular cell types and exert system-wide regulatory functions in all aspects of vascular health and disease. Due to the inherent pleiotropy, overlap, and redundancy of these molecules, it has been challenging to define their integrated effects on overall disease manifestation. In this review, we summarize our current understanding of the roles of microRNAs in PH with an emphasis on potential methods to discern the hierarchical motifs governing their multifunctional and interconnected activities. Deciphering this higher order of regulatory structure will be crucial for overcoming the challenges of developing these molecules as biomarkers or therapeutic targets, in isolation or combination.

Survival in Idiopathic Pulmonary Fibrosis: Perspectives from Pulmonary Arterial Hypertension

Maher has received grants, consulting fees, and speaker fees from GlaxoSmithKline and UCB and grants from Novartis. He has also received consulting fees and speaker fees from AstraZeneca, Bayer, Biogen Idec, Boehringer Ingelheim, Cipla, Lanthio, InterMune International AG (a wholly owned Roche subsidiary since 2014), F. Hoffmann-La Roche, Sanofi-Aventis, and Takeda. Maher is supported by a National Institute for Health Research Clinician Scientist Fellowship (NIHR Ref: CS:-2013-13-017). Dejonckheere is an employee of F. Hoffmann-La Roche. Nathan has received consulting fees from Roche-Genentech and Boehringer Ingelheim. He is also on the speakers bureau for Roche-Genentech and Boehringer Ingelheim and has received research funding from both companies. All authors contributed equally to study concept and design, data collection and analysis, and manuscript preparation.

Bone marrow-derived mesenchymal stem cells modified with IGFBP-3 inhibit the proliferation of pulmonary artery smooth muscle cells

Pulmonary arterial hypertension (PAH) is a common clinical cardiovascular disease, leading to the excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) and endothelial cells, and is associated with a high mortality rate. Recently, stem- and progenitor cell-mediated gene therapies have provided a novel approach for the treatment of PAH. However, the function of human bone marrow-derived mesenchymal stem cells (hBM‑MSCs) modified with the insulin-like growth factor binding protein-3 (IGFBP-3) gene in the regulation of PAH is not yet fully understood. In this study, we explored the biological role of IGFBP‑3-modified hBM‑MSCs in the proliferation of human PASMCs (hPASMCs), and also investigated the potential underlying molecular mechanisms. Our results revealed that IGFBP-3-modified hBM‑MSCs inhibited the proliferation of angiotensin II-stimulated hPASMCs following co-culture on cell culture inserts. In addition, total DNA synthesis and the protein levels of hPASMCs in co-culture were decreased. Moreover, the IGFBP‑3-modified hBM‑MSCs promoted apoptosis and downregulated the expression of B-cell lymphoma-2 (Bcl-2), but increased the expression of Bcl-2 associated X protein (Bax) in hPASMCs. Furthermore, the IGFBP‑3-modified hBM‑MSCs significantly induced a phenotypic change in the hPASMCs from the synthetic to the contractile phenotype in co-culture. Importantly, the levels of several related proteins in the hPASMCs, including phosphorylated (p-)insulin receptor substrate-1 (p-IRS-1), phosphoinositide 3-kinase (p-PI3K), serine/threonine-protein kinase (p-Akt), mitogen-activated protein kinase (p-p38), p-Jun N-terminal kinase (p-JNK) and extracellular signal-regulated kinase (p-ERK), were markedly decreased by the IGFBP-3-modified hBM‑MSCs following co-culture. Taken together, our findings suggest that IGFBP-3-modified hBM‑MSCs inhibit the proliferation and promote the apoptosis of hPASMCs, and promote the swithc to a contractile phenotype in more effectively than wild-type hBM‑MSCs, possibly through the activation of the PI3K/Akt and Ras-mitogen-activated protein kinase (MAPK) signaling pathways. The findings of our study suggest that IGFBP‑3‑modified hBM‑MSCs may be a promising therapeutic strategy for the treatment of PAH.

[The cancer paradigm in pulmonary arterial hypertension: towards anti-remodeling therapies targeting metabolic dysfunction?]

Pulmonary arterial hypertension (PAH) is a rare, complex and multifactorial disease in which pulmonary vascular remodeling plays a major role ending in right heart failure and death. Current specific therapies of PAH that mainly target the vasoconstriction/vasodilatation imbalance are not curative. Bi-pulmonary transplantation remains the only option in patients resistant to current therapies. It is thus crucial to identify novel vascular anti-remodeling therapeutic targets. This remodeling displays several properties of cancer cells, especially overproliferation and apoptosis resistance of pulmonary vascular cells, hallmarks of cancer related to the metabolic shift known as the "Warburg effect". The latter is characterized by a shift of ATP production, from oxidative phosphorylation to low rate aerobic glycolysis. In compensation, the cancer cells exhibit exacerbated glutaminolysis thus resulting in glutamine addiction, necessary to their overproliferation. Glutamine intake results in glutamate production, a molecule at the crossroads of energy metabolism and cancer cell communication, thus contributing to cell proliferation. Accordingly, therapeutic strategies targeting glutamate production, its release into the extracellular space and its membrane receptors have been suggested to treat different types of cancers, not only in the central nervous system but also in the periphery. We propose that similar strategies targeting glutamatergic signaling may be considered in PAH, especially as they could affect not only the vascular remodeling but also the right heart hypertrophy known to involve the glutaminolysis pathway. Ongoing studies aim to characterize the involvement of the glutamate pathway and its receptors in vascular remodeling, and the therapeutic potential of specific molecules targeting this pathway.