Medication and supplement pharmacokinetic changes following bariatric surgery: A systematic review and meta-analysis.

OBJECTIVES: To evaluate the impact of bariatric surgery on the pharmacokinetic (PK) parameters of orally administered medications and supplements. METHODS: Systematic searches of bibliographic databases were conducted to identify studies. Pooled effect estimates from different surgical procedures were calculated using a random-effects model. RESULTS: Quantitative data were synthesized from 58 studies including a total of 1985 participants. Whilst 40 medications and 6 supplements were evaluated across these studies, heterogeneity and missing information reduced the scope of the meta-analysis to the following medications and supplements: atorvastatin, paracetamol, omeprazole, midazolam, vitamin D, calcium, zinc, and iron supplements. There were no significant differences in PK parameters post-surgery for the drugs atorvastatin and omeprazole, and supplements calcium, ferritin, and zinc supplements. Paracetamol showed reduced clearance (mean difference [MD] = -15.56 L/hr, p = 0.0002, I2 = 67%), increased maximal concentration (MD = 6.90 µg/ml, p = 0.006, I2 = 92%) and increased terminal elimination half-life (MD = 0.49 hr, p < 0.0001, I2 = 3%) post-surgery. The remaining 36 medications and 2 supplements were included in a systematic review. Overall, 18 of the 53 drugs and supplements showed post-operative changes in PK parameters. CONCLUSION: This study demonstrates heterogeneity in practice and could not reach conclusive findings for most PK parameters. Prospective studies are needed to inform best practice and enhance patient healthcare and safety following bariatric surgery.

Resistance training and cardiometabolic risk in women with metabolically healthy and unhealthy obesity.

Despite some reported benefits, there is a low quality of evidence for resistance training (RT) improving metabolic health of individuals with overweight or obesity. We evaluated the impact of RT on body composition, cardiorespiratory fitness (CRF) and physical performance, lipid-lipoprotein profile, inflammation, and glucose-insulin homeostasis in 51 postmenopausal women vs. 29 controls matched for age, obesity, and physical activity. Exercised women were further subdivided for comparison of RT effects into those presenting metabolically healthy obesity (MHO) and those with metabolically unhealthy obesity (MUHO) classified according to Karelis and Rabasa-Lhoret or an approach based on adipose tissue secretory dysfunction using the plasma adiponectin(A)/leptin (L) ratio. Participants followed a 4-month weekly RT program targeting major muscle groups (3x10 repetitions at 80% 1-RM). Percent fat marginally decreased and lean body mass increased (0.01

Plasma adiponectin/leptin ratio associates with subcutaneous abdominal and omental adipose tissue characteristics in women.

BACKGROUND: A better understanding of adipose tissue (AT) dysfunction, which includes morphological and functional changes such as adipocyte hypertrophy as well as impaired adipogenesis, lipid storage/mobilization, endocrine and inflammatory responses, is needed in the context of obesity. One dimension of AT dysfunction, secretory adiposopathy, often assessed as a low plasma adiponectin (A)/leptin (L) ratio, is commonly observed in obesity. The aim of this study was to examine markers of AT development and metabolism in 67 women of varying age and adiposity (age: 40-62 years; body mass index, BMI: 17-41 kg/m2) according to levels of adiponectinemia, leptinemia or the plasma A/L ratio. METHODS: Body composition, regional AT distribution and circulating adipokines were determined. Lipolysis was measured from glycerol release in subcutaneous abdominal (SCABD) and omental (OME) adipocytes under basal, isoproterenol-, forskolin (FSK)- and dibutyryl-cyclic AMP (DcAMP)-stimulated conditions. Adipogenesis (C/EBP-α/ß/δ, PPAR-γ2 and SREBP-1c) and lipid metabolism (ß2-ARs, HSL, FABP4, LPL and GLUT4) gene expression (RT-qPCR) was assessed in both fat depots. Participants in the upper versus lower tertile of adiponectin, leptin or the A/L ratio were compared. RESULTS: Basal lipolysis was similar between groups. Women with a low plasma A/L ratio were characterized by higher adiposity and larger SCABD and OME adipocytes (p<0.01) compared to those with a high ratio. In OME adipocytes, women in the low adiponectinemia tertile showed higher isoproterenol-stimulated lipolysis (0.01

PARP1-PKM2 Axis Mediates Right Ventricular Failure Associated With Pulmonary Arterial Hypertension.

The authors show that increased poly(adenosine diphosphate-ribose) polymerase 1 (PARP1) and pyruvate kinase muscle isozyme 2 (PKM2) expression is a common feature of a decompensated right ventricle in patients with pulmonary arterial hypertension and animal models. The authors find in vitro that overactivated PARP1 promotes cardiomyocyte dysfunction by favoring PKM2 expression and nuclear function, glycolytic gene expression, activation of nuclear factor κB-dependent proinflammatory factors. Pharmacologic and genetic inhibition of PARP1 or enforced tetramerization of PKM2 attenuates maladaptive remodeling improving right ventricular (RV) function in multiple rodent models. Taken together, these data implicate the PARP1/PKM2 axis as a critical driver of maladaptive RV remodeling and a new promising target to directly sustain RV function in patients with pulmonary arterial hypertension.

Contribution of markers of adiposopathy and adipose cell size in predicting insulin resistance in women of varying age and adiposity.

Adipose tissue (AT) dysfunctions, such as adipocyte hypertrophy, macrophage infiltration and secretory adiposopathy (low plasma adiponectin/leptin, A/L, ratio), associate with metabolic disorders. However, no study has compared the relative contribution of these markers to cardiometabolic risk in women of varying age and adiposity. Body composition, regional AT distribution, lipid-lipoprotein profile, glucose homeostasis and plasma A and L levels were determined in 67 women (age: 40-62 years; BMI: 17-41 kg/m2). Expression of macrophage infiltration marker CD68 and adipocyte size were measured from subcutaneous abdominal (SCABD) and omental (OME) fat. AT dysfunction markers correlated with most lipid-lipoprotein levels. The A/L ratio was negatively associated with fasting insulinemia and HOMA-IR, while SCABD or OME adipocyte size and SCABD CD68 expression were positively related to these variables. Combination of tertiles of largest adipocyte size and lowest A/L ratio showed the highest HOMA-IR. Multiple regression analyses including these markers and TAG levels revealed that the A/L ratio was the only predictor of fasting insulinemia and HOMA-IR. The contribution of the A/L ratio was superseded by adipose cell size in the model where the latter replaced TAGs. Finally, leptinemia was a better predictor of IR than adipocyte size and the A/L ratio in our participants sample.

Noncanonical HIPPO/MST Signaling via BUB3 and FOXO Drives Pulmonary Vascular Cell Growth and Survival.

RATIONALE: The MSTs (mammalian Ste20-like kinases) 1/2 are members of the HIPPO pathway that act as growth suppressors in adult proliferative diseases. Pulmonary arterial hypertension (PAH) manifests by increased proliferation and survival of pulmonary vascular cells in small PAs, pulmonary vascular remodeling, and the rise of pulmonary arterial pressure. The role of MST1/2 in PAH is currently unknown. OBJECTIVE: To investigate the roles and mechanisms of the action of MST1 and MST2 in PAH. METHODS AND RESULTS: Using early-passage pulmonary vascular cells from PAH and nondiseased lungs and mice with smooth muscle-specific tamoxifen-inducible Mst1/2 knockdown, we found that, in contrast to canonical antiproliferative/proapoptotic roles, MST1/2 act as proproliferative/prosurvival molecules in human PAH pulmonary arterial vascular smooth muscle cells and pulmonary arterial adventitial fibroblasts and support established pulmonary vascular remodeling and pulmonary hypertension in mice with SU5416/hypoxia-induced pulmonary hypertension. By using unbiased proteomic analysis, gain- and loss-of function approaches, and pharmacological inhibition of MST1/2 kinase activity by XMU-MP-1, we next evaluated mechanisms of regulation and function of MST1/2 in PAH pulmonary vascular cells. We found that, in PAH pulmonary arterial adventitial fibroblasts, the proproliferative function of MST1/2 is caused by IL-6-dependent MST1/2 overexpression, which induces PSMC6-dependent downregulation of forkhead homeobox type O 3 and hyperproliferation. In PAH pulmonary arterial vascular smooth muscle cells, MST1/2 acted via forming a disease-specific interaction with BUB3 and supported ECM (extracellular matrix)- and USP10-dependent BUB3 accumulation, upregulation of Akt-mTORC1, cell proliferation, and survival. Supporting our in vitro observations, smooth muscle-specific Mst1/2 knockdown halted upregulation of Akt-mTORC1 in small muscular PAs of mice with SU5416/hypoxia-induced pulmonary hypertension. CONCLUSIONS: Together, this study describes a novel proproliferative/prosurvival role of MST1/2 in PAH pulmonary vasculature, provides a novel mechanistic link from MST1/2 via BUB3 and forkhead homeobox type O to the abnormal proliferation and survival of pulmonary arterial vascular smooth muscle cells and pulmonary arterial adventitial fibroblasts, remodeling and pulmonary hypertension, and suggests new target pathways for therapeutic intervention.

Potential for inhibition of checkpoint kinases 1/2 in pulmonary fibrosis and secondary pulmonary hypertension.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease characterised by exuberant tissue remodelling and associated with high unmet medical needs. Outcomes are even worse when IPF results in secondary pulmonary hypertension (PH). Importantly, exaggerated resistance to cell death, excessive proliferation and enhanced synthetic capacity are key endophenotypes of both fibroblasts and pulmonary artery smooth muscle cells, suggesting shared molecular pathways. Under persistent injury, sustained activation of the DNA damage response (DDR) is integral to the preservation of cells survival and their capacity to proliferate. Checkpoint kinases 1 and 2 (CHK1/2) are key components of the DDR. The objective of this study was to assess the role of CHK1/2 in the development and progression of IPF and IPF+PH. METHODS AND RESULTS: Increased expression of DNA damage markers and CHK1/2 were observed in lungs, remodelled pulmonary arteries and isolated fibroblasts from IPF patients and animal models. Blockade of CHK1/2 expression or activity-induced DNA damage overload and reverted the apoptosis-resistant and fibroproliferative phenotype of disease cells. Moreover, inhibition of CHK1/2 was sufficient to interfere with transforming growth factor beta 1-mediated fibroblast activation. Importantly, pharmacological inhibition of CHK1/2 using LY2606368 attenuated fibrosis and pulmonary vascular remodelling leading to improvement in respiratory mechanics and haemodynamic parameters in two animal models mimicking IPF and IPF+PH. CONCLUSION: This study identifies CHK1/2 as key regulators of lung fibrosis and provides a proof of principle for CHK1/2 inhibition as a potential novel therapeutic option for IPF and IPF+PH.

Implication of EZH2 in the Pro-Proliferative and Apoptosis-Resistant Phenotype of Pulmonary Artery Smooth Muscle Cells in PAH: A Transcriptomic and Proteomic Approach.

Pulmonary arterial hypertension (PAH) is a progressive disorder characterized by a sustained elevation of pulmonary artery (PA) pressure, right ventricular failure, and premature death. Enhanced proliferation and resistance to apoptosis (as seen in cancer cells) of PA smooth muscle cells (PASMCs) is a major pathological hallmark contributing to pulmonary vascular remodeling in PAH, for which current therapies have only limited effects. Emerging evidence points toward a critical role for Enhancer of Zeste Homolog 2 (EZH2) in cancer cell proliferation and survival. However, its role in PAH remains largely unknown. The aim of this study was to determine whether EZH2 represents a new factor critically involved in the abnormal phenotype of PAH-PASMCs. We found that EZH2 is overexpressed in human lung tissues and isolated PASMCs from PAH patients compared to controls as well as in two animal models mimicking the disease. Through loss- and gain-of-function approaches, we showed that EZH2 promotes PAH-PASMC proliferation and survival. By combining quantitative transcriptomic and proteomic approaches in PAH-PASMCs subjected or not to EZH2 knockdown, we found that inhibition of EZH2 downregulates many factors involved in cell-cycle progression, including E2F targets, and contributes to maintain energy production. Notably, we found that EZH2 promotes expression of several nuclear-encoded components of the mitochondrial translation machinery and tricarboxylic acid cycle genes. Overall, this study provides evidence that, by overexpressing EZH2, PAH-PASMCs remove the physiological breaks that normally restrain their proliferation and susceptibility to apoptosis and suggests that EZH2 or downstream factors may serve as therapeutic targets to combat pulmonary vascular remodeling.

Preclinical Investigation of Trifluoperazine as a Novel Therapeutic Agent for the Treatment of Pulmonary Arterial Hypertension.

Trifluoperazine (TFP), an antipsychotic drug approved by the Food and Drug Administration, has been show to exhibit anti-cancer effects. Pulmonary arterial hypertension (PAH) is a devastating disease characterized by a progressive obliteration of small pulmonary arteries (PAs) due to exaggerated proliferation and resistance to apoptosis of PA smooth muscle cells (PASMCs). However, the therapeutic potential of TFP for correcting the cancer-like phenotype of PAH-PASMCs and improving PAH in animal models remains unknown. PASMCs isolated from PAH patients were exposed to different concentrations of TFP before assessments of cell proliferation and apoptosis. The in vivo therapeutic potential of TFP was tested in two preclinical models with established PAH, namely the monocrotaline and sugen/hypoxia-induced rat models. Assessments of hemodynamics by right heart catheterization and histopathology were conducted. TFP showed strong anti-survival and anti-proliferative effects on cultured PAH-PASMCs. Exposure to TFP was associated with downregulation of AKT activity and nuclear translocation of forkhead box protein O3 (FOXO3). In both preclinical models, TFP significantly lowered the right ventricular systolic pressure and total pulmonary resistance and improved cardiac function. Consistently, TFP reduced the medial wall thickness of distal PAs. Overall, our data indicate that TFP could have beneficial effects in PAH and support the view that seeking new uses for old drugs may represent a fruitful approach.

17ß-Estradiol and estrogen receptor α protect right ventricular function in pulmonary hypertension via BMPR2 and apelin.

Women with pulmonary arterial hypertension (PAH) exhibit better right ventricular (RV) function and survival than men; however, the underlying mechanisms are unknown. We hypothesized that 17ß-estradiol (E2), through estrogen receptor α (ER-α), attenuates PAH-induced RV failure (RVF) by upregulating the procontractile and prosurvival peptide apelin via a BMPR2-dependent mechanism. We found that ER-α and apelin expression were decreased in RV homogenates from patients with RVF and from rats with maladaptive (but not adaptive) RV remodeling. RV cardiomyocyte apelin abundance increased in vivo or in vitro after treatment with E2 or ER-α agonist. Studies employing ER-α-null or ER-ß-null mice, ER-α loss-of-function mutant rats, or siRNA demonstrated that ER-α is necessary for E2 to upregulate RV apelin. E2 and ER-α increased BMPR2 in pulmonary hypertension RVs and in isolated RV cardiomyocytes, associated with ER-α binding to the Bmpr2 promoter. BMPR2 is required for E2-mediated increases in apelin abundance, and both BMPR2 and apelin are necessary for E2 to exert RV-protective effects. E2 or ER-α agonist rescued monocrotaline pulmonary hypertension and restored RV apelin and BMPR2. We identified what we believe to be a novel cardioprotective E2/ER-α/BMPR2/apelin axis in the RV. Harnessing this axis may lead to novel RV-targeted therapies for PAH patients of either sex.

Oxidized DNA Precursors Cleanup by NUDT1 Contributes to Vascular Remodeling in Pulmonary Arterial Hypertension.

Rationale: Pulmonary arterial hypertension (PAH) is a life-threatening condition characterized by abnormally elevated pulmonary pressures and right ventricular failure. Excessive proliferation and resistance to apoptosis of pulmonary artery smooth muscle cells (PASMCs) is one of the most important drivers of vascular remodeling in PAH, for which available treatments have limited effectiveness.Objectives: To gain insights into the mechanisms leading to the development of the disease and identify new actionable targets.Methods: Protein expression profiling was conducted by two-dimensional liquid chromatography coupled to tandem mass spectrometry in isolated PASMCs from controls and patients with PAH. Multiple molecular, biochemical, and pharmacologic approaches were used to decipher the role of NUDT1 (nudrix hyrolase 1) in PAH.Measurements and Main Results: Increased expression of the detoxifying DNA enzyme NUDT1 was detected in cells and tissues from patients with PAH and animal models. In vitro, molecular or pharmacological inhibition of NUDT1 in PAH-PASMCs induced accumulation of oxidized nucleotides in the DNA, irresolvable DNA damage (comet assay), disruption of cellular bioenergetics (Seahorse), and cell death (terminal deoxynucleotidyl transferase dUTP nick end labeling assay). In two animal models with established PAH (i.e., monocrotaline and Sugen/hypoxia-treated rats), pharmacological inhibition of NUDT1 using (S)-Crizotinib significantly decreased pulmonary vascular remodeling and improved hemodynamics and cardiac function.Conclusions: Our results indicate that, by overexpressing NUDT1, PAH-PASMCs hijack persistent oxidative stress in preventing incorporation of oxidized nucleotides into DNA, thus allowing the cell to escape apoptosis and proliferate. Given that NUDT1 inhibitors are under clinical investigation for cancer, they may represent a new therapeutic option for PAH.

Identification of Long Noncoding RNA H19 as a New Biomarker and Therapeutic Target in Right Ventricular Failure in Pulmonary Arterial Hypertension.

BACKGROUND: Right ventricular (RV) function is the major determinant for both functional capacity and survival in patients with pulmonary arterial hypertension (PAH). Despite the recognized clinical importance of preserving RV function, the subcellular mechanisms that govern the transition from a compensated to a decompensated state remain poorly understood and as a consequence there are no clinically established treatments for RV failure and a paucity of clinically useful biomarkers. Accumulating evidence indicates that long noncoding RNAs are powerful regulators of cardiac development and disease. Nonetheless, their implication in adverse RV remodeling in PAH is unknown. METHODS: Expression of the long noncoding RNA H19 was assessed by quantitative PCR in plasma and RV from patients categorized as control RV, compensated RV or decompensated RV based on clinical history and cardiac index. The impact of H19 suppression using GapmeR was explored in 2 rat models mimicking RV failure, namely the monocrotaline and pulmonary artery banding. Echocardiographic, hemodynamic, histological, and biochemical analyses were conducted. In vitro gain- and loss-of-function experiments were performed in rat cardiomyocytes. RESULTS: We demonstrated that H19 is upregulated in decompensated RV from PAH patients and correlates with RV hypertrophy and fibrosis. Similar findings were observed in monocrotaline and pulmonary artery banding rats. We found that silencing H19 limits pathological RV hypertrophy, fibrosis and capillary rarefaction, thus preserving RV function in monocrotaline and pulmonary artery banding rats without affecting pulmonary vascular remodeling. This cardioprotective effect was accompanied by E2F transcription factor 1-mediated upregulation of enhancer of zeste homolog 2. In vitro, knockdown of H19 suppressed cardiomyocyte hypertrophy induced by phenylephrine, while its overexpression has the opposite effect. Finally, we demonstrated that circulating H19 levels in plasma discriminate PAH patients from controls, correlate with RV function and predict long-term survival in 2 independent idiopathic PAH cohorts. Moreover, H19 levels delineate subgroups of patients with differentiated prognosis when combined with the NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels or the risk score proposed by both REVEAL (Registry to Evaluate Early and Long-Term PAH Disease Management) and the 2015 European Pulmonary Hypertension Guidelines. CONCLUSIONS: Our findings identify H19 as a new therapeutic target to impede the development of maladaptive RV remodeling and a promising biomarker of PAH severity and prognosis.

PIM1 (Moloney Murine Leukemia Provirus Integration Site) Inhibition Decreases the Nonhomologous End-Joining DNA Damage Repair Signaling Pathway in Pulmonary Hypertension.

OBJECTIVE: Pulmonary arterial hypertension (PAH) is a fatal disease characterized by the narrowing of pulmonary arteries (PAs). It is now established that this phenotype is associated with enhanced PA smooth muscle cells (PASMCs) proliferation and suppressed apoptosis. This phenotype is sustained in part by the activation of several DNA repair pathways allowing PASMCs to survive despite the unfavorable environmental conditions. PIM1 (Moloney murine leukemia provirus integration site) is an oncoprotein upregulated in PAH and involved in many prosurvival pathways, including DNA repair. The objective of this study was to demonstrate the implication of PIM1 in the DNA damage response and the beneficial effect of its inhibition by pharmacological inhibitors in human PAH-PASMCs and in rat PAH models. Approach and Results: We found in vitro that PIM1 inhibition by either SGI-1776, TP-3654, siRNA (silencer RNA) decreased the phosphorylation of its newly identified direct target KU70 (lupus Ku autoantigen protein p70) resulting in the inhibition of double-strand break repair (Comet Assay) by the nonhomologous end-joining as well as reduction of PAH-PASMCs proliferation (Ki67-positive cells) and resistance to apoptosis (Annexin V positive cells) of PAH-PASMCs. In vivo, SGI-1776 and TP-3654 given 3× a week, improved significantly pulmonary hemodynamics (right heart catheterization) and vascular remodeling (Elastica van Gieson) in monocrotaline and Fawn-Hooded rat models of PAH. CONCLUSIONS: We demonstrated that PIM1 phosphorylates KU70 and initiates DNA repair signaling in PAH-PASMCs and that PIM1 inhibitors represent a therapeutic option for patients with PAH.

Metabolic Syndrome Exacerbates Pulmonary Hypertension due to Left Heart Disease.

RATIONALE: Pulmonary hypertension (PH) due to left heart disease (LHD), or group 2 PH, is the most prevalent form of PH worldwide. PH due to LHD is often associated with metabolic syndrome (MetS). In 12% to 13% of cases, patients with PH due to LHD display vascular remodeling of pulmonary arteries (PAs) associated with poor prognosis. Unfortunately, the underlying mechanisms remain unknown; PH-targeted therapies for this group are nonexistent, and the development of a new preclinical model is crucial. Among the numerous pathways dysregulated in MetS, inflammation plays also a critical role in both PH and vascular remodeling. OBJECTIVE: We hypothesized that MetS and inflammation may trigger the development of vascular remodeling in group 2 PH. METHODS AND RESULTS: Using supracoronary aortic banding, we induced diastolic dysfunction in rats. Then we induced MetS by a combination of high-fat diet and olanzapine treatment. We used metformin treatment and anti-IL-6 (interleukin-6) antibodies to inhibit the IL-6 pathway. Compared with sham conditions, only supracoronary aortic banding+MetS rats developed precapillary PH, as measured by both echocardiography and right/left heart catheterization. PH in supracoronary aortic banding+MetS was associated with macrophage accumulation and increased IL-6 production in lung. PH was also associated with STAT3 (signal transducer and activator of transcription 3) activation and increased proliferation of PA smooth muscle cells, which contributes to remodeling of distal PA. We reported macrophage accumulation, increased IL-6 levels, and STAT3 activation in the lung of group 2 PH patients. In vitro, IL-6 activates STAT3 and induces human PA smooth muscle cell proliferation. Metformin treatment decreased inflammation, IL-6 levels, STAT3 activation, and human PA smooth muscle cell proliferation. In vivo, in the supracoronary aortic banding+MetS animals, reducing IL-6, either by anti-IL-6 antibody or metformin treatment, reversed pulmonary vascular remodeling and improve PH due to LHD. CONCLUSIONS: We developed a new preclinical model of group 2 PH by combining MetS with LHD. We showed that MetS exacerbates group 2 PH. We provided evidence for the importance of the IL-6-STAT3 pathway in our experimental model of group 2 PH and human patients.

Inhibition of CHK 1 (Checkpoint Kinase 1) Elicits Therapeutic Effects in Pulmonary Arterial Hypertension.

OBJECTIVE: Pulmonary arterial hypertension (PAH) is a debilitating disease associated with progressive vascular remodeling of distal pulmonary arteries leading to elevation of pulmonary artery pressure, right ventricular hypertrophy, and death. Although presenting high levels of DNA damage that normally jeopardize their viability, pulmonary artery smooth muscle cells (PASMCs) from patients with PAH exhibit a cancer-like proproliferative and apoptosis-resistant phenotype accounting for vascular lumen obliteration. In cancer cells, overexpression of the serine/threonine-protein kinase CHK1 (checkpoint kinase 1) is exploited to counteract the excess of DNA damage insults they are exposed to. This study aimed to determine whether PAH-PASMCs have developed an orchestrated response mediated by CHK1 to overcome DNA damage, allowing cell survival and proliferation. Approach and Results: We demonstrated that CHK1 expression is markedly increased in isolated PASMCs and distal PAs from patients with PAH compared with controls, as well as in multiple complementary animal models recapitulating the disease, including monocrotaline rats and the simian immunodeficiency virus-infected macaques. Using a pharmacological and molecular loss of function approach, we showed that CHK1 promotes PAH-PASMCs proliferation and resistance to apoptosis. In addition, we found that inhibition of CHK1 induces downregulation of the DNA repair protein RAD 51 and severe DNA damage. In vivo, we provided evidence that pharmacological inhibition of CHK1 significantly reduces vascular remodeling and improves hemodynamic parameters in 2 experimental rat models of PAH. CONCLUSIONS: Our results show that CHK1 exerts a proproliferative function in PAH-PASMCs by mitigating DNA damage and suggest that CHK1 inhibition may, therefore, represent an attractive therapeutic option for patients with PAH.

Multicenter Preclinical Validation of BET Inhibition for the Treatment of Pulmonary Arterial Hypertension.

Rationale: Pulmonary arterial hypertension (PAH) is a degenerative arteriopathy that leads to right ventricular (RV) failure. BRD4 (bromodomain-containing protein 4), a member of the BET (bromodomain and extra-terminal motif) family, has been identified as a critical epigenetic driver for cardiovascular diseases.Objectives: To explore the therapeutic potential in PAH of RVX208, a clinically available BET inhibitor.Methods: Microvascular endothelial cells, smooth muscle cells isolated from distal pulmonary arteries of patients with PAH, rats with Sugen5416 + hypoxia- or monocrotaline + shunt-induced PAH, and rats with RV pressure overload induced by pulmonary artery banding were treated with RVX208 in three independent laboratories.Measurements and Main Results: BRD4 is upregulated in the remodeled pulmonary vasculature of patients with PAH, where it regulates FoxM1 and PLK1, proteins implicated in the DNA damage response. RVX208 normalized the hyperproliferative, apoptosis-resistant, and inflammatory phenotype of microvascular endothelial cells and smooth muscle cells isolated from patients with PAH. Oral treatment with RVX208 reversed vascular remodeling and improved pulmonary hemodynamics in two independent trials in Sugen5416 + hypoxia-PAH and in monocrotaline + shunt-PAH. RVX208 could be combined safely with contemporary PAH standard of care. RVX208 treatment also supported the pressure-loaded RV in pulmonary artery banding rats.Conclusions: RVX208, a clinically available BET inhibitor, modulates proproliferative, prosurvival, and proinflammatory pathways, potentially through interactions with FoxM1 and PLK1. This reversed the PAH phenotype in isolated PAH microvascular endothelial cells and smooth muscle cells in vitro, and in diverse PAH rat models. RVX208 also supported the pressure-loaded RV in vivo. Together, these data support the establishment of a clinical trial with RVX208 in patients with PAH.

Mitochondrial HSP90 Accumulation Promotes Vascular Remodeling in Pulmonary Arterial Hypertension.

RATIONALE: Pulmonary arterial hypertension (PAH) is a vascular remodeling disease with a poor prognosis and limited therapeutic options. Although the mechanisms contributing to vascular remodeling in PAH are still unclear, several features, including hyperproliferation and resistance to apoptosis of pulmonary artery smooth muscle cells (PASMCs), have led to the emergence of the cancer-like concept. The molecular chaperone HSP90 (heat shock protein 90) is directly associated with malignant growth and proliferation under stress conditions. In addition to being highly expressed in the cytosol, HSP90 exists in a subcellular pool compartmentalized in the mitochondria (mtHSP90) of tumor cells, but not in normal cells, where it promotes cell survival. OBJECTIVES: We hypothesized that mtHSP90 in PAH-PASMCs represents a protective mechanism against stress, promoting their proliferation and resistance to apoptosis. METHODS: Expression and localization of HSP90 were analyzed by Western blot, immunofluorescence, and immunogold electron microscopy. In vitro, effects of mtHSP90 inhibition on mitochondrial DNA integrity, bioenergetics, cell proliferation and resistance to apoptosis were assessed. In vivo, the therapeutic potential of Gamitrinib, a mitochondria-targeted HSP90 inhibitor, was tested in fawn-hooded and monocrotaline rats. MEASUREMENTS AND MAIN RESULTS: We demonstrated that, in response to stress, HSP90 preferentially accumulates in PAH-PASMC mitochondria (dual immunostaining, immunoblot, and immunogold electron microscopy) to ensure cell survival by preserving mitochondrial DNA integrity and bioenergetic functions. Whereas cytosolic HSP90 inhibition displays a lack of absolute specificity for PAH-PASMCs, Gamitrinib decreased mitochondrial DNA content and repair capacity and bioenergetic functions, thus repressing PAH-PASMC proliferation (Ki67 labeling) and resistance to apoptosis (Annexin V assay) without affecting control cells. In vivo, Gamitrinib improves PAH in two experimental rat models (monocrotaline and fawn-hooded rat). CONCLUSIONS: Our data show for the first time that accumulation of mtHSP90 is a feature of PAH-PASMCs and a key regulator of mitochondrial homeostasis contributing to vascular remodeling in PAH.

Dual ETA/ETB blockade with macitentan improves both vascular remodeling and angiogenesis in pulmonary arterial hypertension.

Dysregulated metabolism and rarefaction of the capillary network play a critical role in pulmonary arterial hypertension (PAH) etiology. They are associated with a decrease in perfusion of the lungs, skeletal muscles, and right ventricle (RV). Previous studies suggested that endothelin-1 (ET-1) modulates both metabolism and angiogenesis. We hypothesized that dual ETA/ETB receptors blockade improves PAH by improving cell metabolism and promoting angiogenesis. Five weeks after disease induction, Sugen/hypoxic rats presented severe PAH with pulmonary artery (PA) remodeling, RV hypertrophy and capillary rarefaction in the lungs, RV, and skeletal muscles (microCT angiogram, lectin perfusion, CD31 staining). Two-week treatment with dual ETA/ETB receptors antagonist macitentan (30 mg/kg/d) significantly improved pulmonary hemodynamics, PA vascular remodeling, and RV function and hypertrophy compared to vehicle-treated animals (all P = 0.05). Moreover, macitentan markedly increased lung, RV and quadriceps perfusion, and microvascular density (all P = 0.05). In vitro, these effects were associated with increases in oxidative phosphorylation (oxPhox) and markedly reduced cell proliferation of PAH-PA smooth muscle cells (PASMCs) treated with macitentan without affecting apoptosis. While macitentan did not affect oxPhox, proliferation, and apoptosis of PAH-PA endothelial cells (PAECs), it significantly improved their angiogenic capacity (tube formation assay). Exposure of control PASMC and PAEC to ET-1 fully mimicked the PAH cells phenotype, thus confirming that ET-1 is implicated in both metabolism and angiogenesis abnormalities in PAH. Dual ETA/ETB receptor blockade improved the metabolic changes involved in PAH-PASMCs' proliferation and the angiogenic capacity of PAH-PAEC leading to an increased capillary density in lungs, RV, and skeletal muscles.

Implication of Inflammation and Epigenetic Readers in Coronary Artery Remodeling in Patients With Pulmonary Arterial Hypertension.

OBJECTIVE: Pulmonary arterial hypertension (PAH) is a vascular disease not restricted to the lungs. Many signaling pathways described in PAH are also of importance in other vascular remodeling diseases, such as coronary artery disease (CAD). Intriguingly, CAD is 4× more prevalent in PAH compared with the global population, suggesting a link between these 2 diseases. Both PAH and CAD are associated with sustained inflammation and smooth muscle cell proliferation/apoptosis imbalance and we demonstrated in PAH that this phenotype is, in part, because of the miR-223/DNA damage/Poly[ADP-ribose] polymerase 1/miR-204 axis activation and subsequent bromodomain protein 4 (BRD4) overexpression. Interestingly, BRD4 is also a trigger for calcification and remodeling processes, both of which are important in CAD. Thus, we hypothesize that BRD4 activation in PAH influences the development of CAD. APPROACH AND RESULTS: PAH was associated with significant remodeling of the coronary arteries in both human and experimental models of the disease. As observed in PAH distal pulmonary arteries, coronary arteries of patients with PAH also exhibited increased DNA damage, inflammation, and BRD4 overexpression. In vitro, using human coronary artery smooth muscle cells from PAH, CAD and non-PAH-non-CAD patients, we showed that both PAH and CAD smooth muscle cells exhibited increased proliferation and suppressed apoptosis in a BRD4-dependent manner. In vivo, improvement of PAH by BRD4 inhibitor was associated with a reduction in coronary remodeling and interleukin-6 expression. CONCLUSIONS: Overall, this study demonstrates that increased BRD4 expression in coronary arteries of patient with PAH contributes to vascular remodeling and comorbidity development.