Pulmonary Arterial Hypertension Therapy Research Articles

Hub gene ELK3-mediated reprogramming lipid metabolism regulates phenotypic switching of pulmonary artery smooth muscle cells to develop pulmonary arterial hypertension induced by PM2.5

Fine particulate matter (PM2.5) as an environmental pollutant is related with respiratory and cardiovascular diseases. Pulmonary arterial hypertension (PAH) was characterized by incremental pulmonary artery pressure and pulmonary arterial remodeling, leading to right ventricular hypertrophy, and finally cardiac failure and death. The adverse effects on pulmonary artery and the molecular biological mechanism underlying PM2.5-caused PAH has not been elaborated clearly. In the current study, the ambient PM2.5 exposure mice model along with HPASMCs models were established. Based on bioinformatic methods and machine learning algorithms, the hub genes in PAH were screened and then adverse effects on pulmonary artery and potential mechanism was studied. Our results showed that chronic PM2.5 exposure contributed to increased pulmonary artery pressure, pulmonary arterial remodeling and right ventricular hypertrophy in mice. In vitro, PM2.5 induced phenotypic switching in HPASMCs, which served as the early stage of PAH. In mechanism, we investigated that PM2.5-mediated mitochondrial dysfunction could induce phenotypic switching in HPASMCs, which was possibly through reprogramming lipid metabolism. Next, we used machine learning algorithm to identify ELK3 as potential hub gene for mitochondrial fission. Besides, the effect of DNA methylation on ELK3 was further detected in HPASMCs after PM2.5 exposure. The results provided novel directions for protection of pulmonary vasculature injury, against adverse environmental stimuli. This work also provided a new idea for the prevention of PAH, as well as provided experimental evidence for the targeted therapy of PAH.

Dissecting molecular mechanisms underlying ferroptosis in human umbilical cord mesenchymal stem cells: Role of cystathionine γ-lyase/hydrogen sulfide pathway.

Ferroptosis can induce low retention and engraftment after mesenchymal stem cell (MSC) delivery, which is considered a major challenge to the effectiveness of MSC-based pulmonary arterial hypertension (PAH) therapy. Interestingly, the cystathionine γ-lyase (CSE)/hydrogen sulfide (H2S) pathway may contribute to mediating ferroptosis. However, the influence of the CSE/H2S pathway on ferroptosis in human umbilical cord MSCs (HUCMSCs) remains unclear. To clarify whether the effect of HUCMSCs on vascular remodelling in PAH mice is affected by CSE/H2S pathway-mediated ferroptosis, and to investigate the functions of the CSE/H2S pathway in ferroptosis in HUCMSCs and the underlying mechanisms. Erastin and ferrostatin-1 (Fer-1) were used to induce and inhibit ferroptosis, respectively. HUCMSCs were transfected with a vector to overexpress or inhibit expression of CSE. A PAH mouse model was established using 4-wk-old male BALB/c nude mice under hypoxic conditions, and pulmonary pressure and vascular remodelling were measured. The survival of HUCMSCs after delivery was observed by in vivo bioluminescence imaging. Cell viability, iron accumulation, reactive oxygen species production, cystine uptake, and lipid peroxidation in HUCMSCs were tested. Ferroptosis-related proteins and S-sulfhydrated Kelch-like ECH-associating protein 1 (Keap1) were detected by western blot analysis. In vivo, CSE overexpression improved cell survival after erastin-treated HUCMSC delivery in mice with hypoxia-induced PAH. In vitro, CSE overexpression improved H2S production and ferroptosis-related indexes, such as cell viability, iron level, reactive oxygen species production, cystine uptake, lipid peroxidation, mitochondrial membrane density, and ferroptosis-related protein expression, in erastin-treated HUCMSCs. In contrast, in vivo, CSE inhibition decreased cell survival after Fer-1-treated HUCMSC delivery and aggravated vascular remodelling in PAH mice. In vitro, CSE inhibition decreased H2S levels and restored ferroptosis in Fer-1-treated HUCMSCs. Interestingly, upregulation of the CSE/H2S pathway induced Keap1 S-sulfhydration, which contributed to the inhibition of ferroptosis. Regulation of the CSE/H2S pathway in HUCMSCs contributes to the inhibition of ferroptosis and improves the suppressive effect on vascular remodelling in mice with hypoxia-induced PAH. Moreover, the protective effect of the CSE/H2S pathway against ferroptosis in HUCMSCs is mediated via S-sulfhydrated Keap1/nuclear factor erythroid 2-related factor 2 signalling. The present study may provide a novel therapeutic avenue for improving the protective capacity of transplanted MSCs in PAH.

ERS International Congress 2023: highlights from the Pulmonary Vascular Diseases Assembly.

Pulmonary vascular diseases such as pulmonary embolism and pulmonary hypertension are important and frequently under-recognised conditions. This article provides an overview of key highlights in pulmonary vascular diseases from the European Respiratory Society International Congress 2023. This includes insights into disease modification in pulmonary arterial hypertension and novel therapies such as sotatercept and seralutinib. Exciting developments in our understanding of the mechanisms underpinning pulmonary hypertension associated with interstitial lung disease are also explored. A comprehensive overview of the complex relationship between acute pulmonary embolism and chronic thromboembolic pulmonary hypertension (CTEPH) is provided along with our current understanding of the molecular determinants of CTEPH. The importance of multidisciplinary and holistic care cannot be understated, and this article also addresses advances beyond medication, with a special focus on exercise training and rehabilitation.

Impact of Left Heart Disease Risk Factors on Outcomes in Pulmonary Arterial Hypertension Therapy

BackgroundCurrent guidelines recommend initial monotherapy for pulmonary arterial hypertension (PAH) with ‘cardiopulmonary comorbidities’, despite limited available evidence to guide management. Research QuestionDo left heart disease (LHD) risk factors have an impact on treatment response and influence applicability of risk assessment in a real-world cohort of PAH patients? Study Design and MethodsThe AMBITION trial criteria was used to define the phenotype of PAH patients with risk factors for LHD. Treatment strategy, functional outcome, long term survival and risk discrimination were compared with a reference PAH cohort using the PHSANZ registry. Results487 incident PAH patients diagnosed between 2011-2020 were included. Of these, 103 (21.1%) fulfilled the definition of PAH with LHD risk factors with 384 (78.9%) remaining as reference group. PAH with LHD risk factors were older (66±13 vs. 58±19years, p<0.001), had lower pulmonary vascular resistance (393±266 vs 708±391dynes/sec/cm-5, p=0.031) and worse 6-minute walk distance (286±130 vs. 327±136m, p=0.005) at diagnosis. PAH with LHD risk factors were less likely to receive less initial combination therapy (27% vs. 44%, p=0.02). Changes in 6-minute walk distance at 12-months were similar in both groups, 43±77 in PAH with LHD risk factors and 50±90m in reference group (p=0.5), including when stratified by initial treatment strategy (monotherapy: 40±81 vs. 38±95m p=0.87 and combination therapy: 53±78 vs. 64±106m, p=0.511; PAH with LHD risk factors vs. reference PAH). Functional class improvements were also similar in both groups. REVEAL 2.0 risk score effectively discriminated risk in both populations (C-statistic=0.756 for PAH with LHD risk factors and C-statistic=0.750 for reference PAH). There was no difference in survival between the two groups (log-rank test p=0.29). InterpretationIn a real-word cohort, PAH patients with LHD risk factors were less likely to be exposed to initial combination therapy. Nevertheless, selected PAH patients with LHD risk factors who were treated with initial combination therapy derived similar functional response compared to reference group. Further studies are needed to phenotype PAH patients with cardiopulmonary comorbidities who may benefit from initial combination therapy.

Evaluating the safety and long-term efficacy of triple vasodilator therapy for pulmonary arterial hypertension associated with congenital heart disease

Abstract Background Pulmonary arterial hypertension (PAH) affects 5-10% of congenital heart disease (CHD) patients, but there is limited information on the safety and efficacy of triple combination therapy for PAH-CHD. The aim of this study was to assess the long-term effects of triple therapy (TT) with prostacyclins on PAH-CHD patients. Methods A retrospective, longitudinal, cohort study of patients with PAH-CHD under active follow-up in our center. All patients were receiving baseline dual therapy at maximum doses. Clinical characteristics, including functional class (FC), 6-minute walk test distance (6MWTd), and NT-ProBNP were recorded before initiating TT and during annual follow-ups during 2 years. Results 60 patients were included (median age 41, 31 women 61%). 32 had Eisenmenger syndrome, 9 had coincidental shunts, 18 had postoperative PAH, and 1 had a significant L-R shunt. TT was initiated based on the clinical situation, existence of shunt and ease of administration (epoprostenol 20%, treprostinil 41%, selexipag 32%, iloprost 7%). A significant improvement in the 6MWTd was observed one year after the initiation of TT (p&amp;lt;0.05), which was maintained at two-year follow-up, with an average improvement of 44 metres. An improvement of FC was observed in 79% of patients at one year, maintained at 2 years in 76%. A NT- proBNP levels decreased from the start, and reached significancy two years after the initiation of TT, with an average decrease of 199 ng/l (Figure 1). Twenty patients (33.3%) experienced side effects after drug initiation. Most were mild and well-controlled with symptomatic treatment. Only 3 (5%) had to change the administration route (Figure 2). By subgroups, patients without Eisenmenger and with pre-tricuspid defects had a more marked benefit. Conclusions TT has been shown to be safe and effective in patients with PAH-CHD, improving FC, 6MWTd, and NT-proBNP levels, particularly in pre-tricuspid defects and non-Eisenmenger PAH-CHD.Changes after initiation of TTType of treatment and side-effects

Triple therapy for incident pulmonary arterial hypertension in Finland between 2008 and 2020. A descriptive real-world FINPAH cohort study

Abstract Background Treatment of pulmonary arterial hypertension (PAH) with triple therapy (TriT) including phosphodiesterase type-5 inhibitors (PDE5), endothelin receptor antagonists (ERA), and prostacyclin receptor agonists (PRA) or analogues (PCA) is indicated in severe PAH. There is evidence of benefit also in intermediate-risk patients. Purpose To describe the real-world use of TriT in a contemporary cohort of Finnish PAH patients. Methods Data was collected via chart review by treating clinicians. Pulmonary hypertension (PH) patients were diagnosed between 2008–19 at the five Finnish university hospitals. Patient characteristics and clinical information were combined with mortality data from Statistics Finland. Persistence and survival were estimated using Kaplan-Meier. Results Out of 493 incident PH patients with medication history available, TriT was recorded for 41 (8%), with a median follow-up of 5.86 years (IQR: 4.12-8.72). TriT patients were predominantly women (73%), mean age 55 years (IQR 46–69) at diagnosis. 35 patients (85%) had PAH (37% iPAH, 27% PAH associated with connective tissue disease and 22% other PAH subclasses), and 6 patients (15%) had other PH types, mostly CTEPH. TriT was started at a median of 2.15 years (IQR: 0.65-3.64) after diagnosis. At the initiation of TriT, 7 patients (17%) had NYHA functional class (FC) IV, 21 (51%) had FC III, 8 (20%) had FC II. Median six-minute walking distance (6MWD) was 360 m (IQR 245-435 m, N=33). Median BNP was 328 pg/mL (IQR 190-723, N=10), and median NT-proBNP was 1082 pg/mL (IQR 745-3420, N=31). Fewer than 3 patients (&amp;lt;7%) were at ESC/ERS 2015 high risk. Initial PRA or PCA in TriT was iloprost (n=21, 51%), selexipag (n=12, 29%), or treprostinil (n=8, 20%). Initial ERA in TriT was macitentan (n=20, 49%), bosentan (n=11, 27%), or ambrisentan (n=10, 24%). Initial PDE5 was sildenafil (n=36, 88%) or tadalafil (n=5, 12%). Estimated persistence with TriT was 88% at 1 year and 84% at 5 years. Selexipag and iloprost were discontinued in &amp;lt;3 (&amp;lt;25% of users) and in 12 (57% of users), respectively, and 10 patients (24%) were switched to treprostinil. 6 TriT patients were listed for lung transplant after start of TriT, and 4 received a lung transplant. Six months after start of TriT, 4 patients (10%) had died and 5 (12%) had discontinued TriT. For the patients with 6 months of recorded TriT use (N=31), NT-proBNP changed by median -184 pg/mL (IQR -689 to +165, N=24), and 6MWD changed by median +20 m (IQR -3 to +35, N=22). In 8 patients (30%) FC improved within 6 months of TriT, was stable in 15 patients (56%) and worsened in 4 patients (15%). After 6 months of TriT, no patient was at high risk. Estimated overall survival was 90% (95%-CI 82-100%) at 6 months and 1 year after start of TriT. Estimated 5-year survival was 52% (95%-CI 38-72%). Conclusion(s) The study shows infrequent use but high persistence of TriT in Finnish PAH patients. TriT patients remained generally stable while on TriT.

Abstract 13431: Safety and Efficacy of Pulmonary Artery Denervation Therapy for the Treatment of Pulmonary Artery Hypertension

Background: Despite recent advances in the treatment of pulmonary arterial hypertension (PAH), the survival rate remains poor in severe PAH. Pulmonary artery denervation (PADN) therapy for PAH is gaining popularity, although the safety and efficacy of PADN were not fully evaluated. Therefore, we conducted an updated systematic review and meta-analysis of the safety and efficacy of PADN in the treatment of patients with PAH. Methods: Using PRISMA guidelines, we searched PubMed, Embase, Cochrane, and the Clinical Trials.gov databases from inception till May 2023 for placebo-controlled outcome studies that compared PADN therapy to placebo in patients with moderate-severe PAH. The literature was screened for appropriate randomized clinical trials (RCT) and prospective studies, and data were extracted and analyzed. Comprehensive meta-analysis software (CMA v3, Biostat Inc. Englewood, NJ, USA) was utilized to perform statistical analyses. Results: The metanalysis included 8 studies (7 RCTs and 1 prospective) with 577 patients (PADN group = 270, placebo = 307). PADN treatment was associated with a significant reduction in mean pulmonary artery pressure [weighted mean difference (WMD) = -6.9 mmHg; 95% CI = -9.7, -4.1; P &lt; 0.01; I 2 = 61] and pulmonary vascular resistance [WMD = -3.2 dyne.s.cm -5 ; 95% CI = -5.4, -0.9; P = 0.005; I 2 = 95]. There was a statistically significant improvement in the cardiac output [WMD = 0.3 l/min; 95% CI = 0.07, 0.6; P=0.012; I 2 = 76] and numerical improvement in 6-minute walking distance [WMD = 67.7m; 95% CI = -3.73, 139.2; P = 0.06; I 2 = 95] in the PADN group. There were fewer side effects in the PADN group as compared to the placebo group. Conclusion: This updated metanalysis supports PADN as a safe and efficacious therapy for moderate-severe PAH. Findings are limited by small sample size, medium-quality literature, and large data heterogeneity, necessitating larger RCT with clinical endpoints comparing PADN therapy with optimal medical treatment.

Abstract 17599: Sotatercept for the Treatment of Pulmonary Arterial Hypertension: A Systematic Review and Single-Arm Meta-Analysis

Introduction: Pulmonary arterial hypertension (PAH) is associated with progressive clinical worsening and a 50% 5-year survival rate with current PAH therapies. Sotatercept is a first-in-class fusion protein with promising results in preclinical trials, but clinical evidence on its role in treating PAH remains limited. Hypothesis: Sotatercept may provide clinical benefits for patients with symptomatic PAH. Aims: To assess the efficacy of sotatercept in addition to background PAH therapy in this population. Methods: We searched PubMed, Embase, Cochrane and Clinicaltrials.gov in April 2023 for clinical trials assessing efficacy outcomes of sotatercept in patients with PAH. Using a random-effects model, we performed a single-arm meta-analysis of proportions for binary outcomes and applied generic inverse variance weighting formulas to pool arithmetic means and least squares means for continuous outcomes. Statistical analyses were performed using Review Manager 5.4.1 and R software 4.2.2. Results: We included three clinical trials comprising 254 patients with WHO functional class II or III PAH. At 24 weeks, only 2% of patients on sotatercept experienced symptoms of clinical worsening (95% CI 1 to 5; Fig. 1A). Sotatercept was also associated with a reduction in pulmonary vascular resistance (mean change from baseline -199.92 dyn·sec·cm -5 ; 95% CI -256.83 to -143.0; Fig. 1B), while improving 6-minute walk distance (mean change from baseline 45.86 m; 95% CI 28.54 to 63.18; Fig. 1C). Conclusions: These findings suggest that sotatercept may improve exercise capacity while decelerating clinical worsening and attenuating pulmonary vascular resistance in patients with mild to moderate PAH.

Abstract 14319: Riociguat in Pulmonary Arterial Hypertension: Application of the 4-strata COMPERA 2.0 Risk Assessment Tool in the PATENT Studies

Background: The 2022 ESC/ERS treatment guidelines for pulmonary arterial hypertension (PAH) recommend using a four-strata risk assessment strategy at follow-up. COMPERA 2.0 is a refined four-strata risk assessment tool that subdivides patients at intermediate risk of mortality at 1 year into intermediate-low and intermediate-high risk groups for a more granular approach to risk prediction. Aim: This post-hoc analysis applied COMPERA 2.0 to the PATENT studies of riociguat in patients with PAH. Methods: COMPERA 2.0 was applied to patients who were pretreated with PAH therapy at PATENT-1 entry. Patients with missing data for COMPERA 2.0 variables were excluded. In PATENT-1, risk strata were assessed at baseline and Week 12; and 6-minute walking distance (6MWD) at Week 12 was analyzed by risk strata at baseline. All pretreated patients entering the PATENT-2 open-label extension were included in Kaplan-Meier analyses to assess association of risk strata at PATENT-1 baseline and Week 12 with clinical worsening and survival. Results: At PATENT-1 baseline (riociguat 2.5 mg n=102, placebo n=49), more patients were at intermediate-low risk than intermediate-high risk (Figure 1). At PATENT-1 Week 12, a higher proportion of patients were at low risk with riociguat vs placebo (Figure 1). At PATENT-1 Week 12, the following mean [SD] changes in 6MWD were seen in patients at intermediate-low risk (riociguat 24 m [57 m], placebo 10 m [60 m]) and intermediate-high risk (riociguat 34 m [56 m], placebo –2 m [70 m]) by COMPERA 2.0 at baseline. COMPERA 2.0 assessed at PATENT-1 baseline and Week 12 was able to discriminate between risk strata for clinical worsening and survival in PATENT-2 (n=167, log-rank tests: p≤0.001 for all analyses). Conclusion: This analysis confirmed the risk-reduction benefits of riociguat in patients with PAH and validated the utility of COMPERA 2.0 in the long-term risk assessment of patients from a clinical trial population.

Abstract 14354: The Impact of Riociguat in Pulmonary Arterial Hypertension Patients With Comorbidities Included in Interventional Clinical Trials

Background: The number of pulmonary arterial hypertension (PAH) patients with comorbidities is increasing, however, there are few published data from these patients in PAH therapy clinical trials meaning that evidence-based treatment recommendations have not been made. Aim: This post-hoc analysis of pooled riociguat clinical trial data assessed the impact of riociguat in patients with PAH and comorbidities. Methods: All interventional studies of riociguat in patients with PAH (PATENT-1, PATENT PLUS, RESPITE, MOTION, REPLACE, and the Phase II study) were included in the pooled analysis. The safety of riociguat and placebo was assessed in patients with ≥3 comorbidities vs &lt;3 comorbidities. Safety was assessed by adverse events (AEs) and serious AEs (SAEs). Comorbidities included: age ≥65 years, body mass index ≥30 kg/m 2 , history of essential hypertension, diabetes mellitus, history of significant coronary artery disease, and atrial fibrillation. Results: The 609 patients who received riociguat and 132 patients who received placebo in the main phase clinical trials of riociguat were included in the analysis. Of these, 113 patients (19%) in the riociguat group and 21 patients (16%) in the placebo group had ≥3 comorbidities. In both treatment groups, AE rates were higher in patients with ≥3 comorbidities vs &lt;3 comorbidities (riociguat 93% vs 86%; placebo 95% vs 84%); with most AEs being mild or moderate. Study drug-related AE rates were similar in both treatment groups and in patients with ≥3 comorbidities vs &lt;3 comorbidities (riociguat 54% vs 56%; placebo 52% vs 52%). SAE rates were higher in riociguat-treated patients with ≥3 comorbidities vs &lt;3 comorbidities (25% vs 12%); of these, 4% and 3% were study drug-related, respectively. In patients with ≥3 comorbidities, study drug-related SAE rates were higher in those receiving placebo vs riociguat (10% vs 4%). AE rates leading to study drug discontinuation were higher in patients with ≥3 comorbidities vs &lt;3 comorbidities (riociguat 6% vs 4%; placebo 10% vs 6%), whereas AE rates leading to death were similar in both groups (riociguat 2% vs 1%; placebo 0% vs 4%). Conclusion: These data suggest that riociguat had an acceptable tolerability profile in PAH patients with comorbidities with most AEs being mild or moderate.

Abstract 18691: Asporin Attenuates Pulmonary Arterial Smooth Muscle Cell Proliferation and Regulates Pulmonary Hypertension Development

Introduction: Pulmonary arterial hypertension (PAH) is a devastating pulmonary vascular lung disease characterized by increased pressure in the pulmonary arteries (PA) leading to cardiac right ventricular (RV) hypertrophy, RV failure, and ultimately death. Current PAH therapies merely improve symptoms temporarily and patients often need lung and heart transplantation. There is dire need for new insights into PAH pathophysiology to find novel therapeutic approaches. A key mechanism driving PAH is medial hyperplasia resulting from enhanced pulmonary arterial smooth muscle cell (PASMC) proliferation. Methods: We employed an unbiased bioinformatics approach in online-available microarray expression and single-cell sequencing datasets of dissected PA from PAH patients. In vitro experiments were performed in PASMC isolated from a female donor and PAH patient. Human lung tissue sections were obtained from the Pulmonary Hypertension Breakthrough Initiative Biobank. The Sugen/Hypoxia model was used to induce PH in rats. Results: We discovered that a novel gene, small leucine-rich proteoglycan Asporin (Aspn), is highly and significantly upregulated in PAH compared to donor PA and is most highly expressed in PASMC. We validated higher Aspn mRNA expression in human lungs and PASMC from PAH patients compared to controls, supporting our bioinformatics approach. Moreover, Aspn protein expression is elevated in PASMC in lung tissue sections from PAH patients compared to donors, as well as in PAH patient plasma . Functionally, silencing Aspn in PASMC from PAH patients promoted proliferation, whereas recombinant Aspn exerted opposite effects. To find potential downstream mediators of Aspn, STRING database analysis revealed that Aspn binds to the pro-proliferative mediator TGFβ1. Accordingly, TGFβ1 downstream mediator p-SMAD2/3 is enhanced upon Aspn silencing in PASMC. Intratracheal delivery of Aspn siRNA in rats aggravated Sugen/Hypoxia-induced PH, as assessed by RVSP, echocardiography and vascular remodeling. Conclusions: We hypothesize that elevated Aspn expression in PAH is a compensatory mechanism that inhibits PASMC proliferation, leading to decreased PA vascular remodeling, and that Aspn may be a novel therapeutic target against PAH.

Abstract 12978: Real-World Treatment Patterns in Hispanic and White Patients With Pulmonary Arterial Hypertension (PAH) in the United States

Introduction: ESC/ERS guidelines recommend initial double oral combination therapy (endothelin-receptor antagonist plus phosphodiesterase 5 inhibitor) in low or intermediate risk PAH patients without cardiopulmonary comorbidities. Upfront use of prostacyclin pathway analogue (PPA) is recommended for patients with high risk of 1-year mortality. Few studies have evaluated treatment patterns/adherence in PAH patients across ethnic groups. Aims: To describe demographic/clinical characteristics and treatment patterns in US Hispanic and White PAH patients. Methods: A retrospective, observational, analysis using Optum’s de-identified Clinformatics ® Data Mart database identified patients aged ≥18 years with pulmonary hypertension (PH) diagnosis (excluding chronic thromboembolic PH) and were new users of PAH medications. Index date was the 31 st day after first PAH-specific medication use (1 Jan 2016-30 Jun 2022); the 30-day window between first PAH medication use and index date was used to identify the initial PAH regimen. Patient characteristics and PAH treatment patterns were analyzed descriptively, with standardized mean differences (SMD) between cohorts assessed (SMD &gt;0.1 indicated significant difference). Results: Hispanic patients were younger, with lower income, lower education level, and higher comorbidity burden than White patients (Table). Few patients received initial combination PAH treatment with similar use of combination therapy in the two cohorts (~14% in each). Hispanic patients were less likely to receive a PPA-containing index treatment regimen and had lower index treatment adherence (Table). Conclusions: In Hispanic and White patients, index combination PAH therapy use was low. Hispanic patients were less likely to receive a PPA-containing index treatment and had lower index treatment adherence. Further research and awareness of the influence of ethnicity on treatment management is needed to improve PAH care.

Abstract 18413: Therapeutic Genome Editing of Endothelial FABP4 by Endothelium-Targeted Nanoparticle Delivery of the CRISPR/Cas9 System Inhibits Pulmonary Arterial Hypertension in Mice and Rats

Introduction: Pulmonary arterial hypertension (PAH) is a devastating disease characterized by progressive vasoconstriction and obliterative vascular remodeling. The molecular mechanisms of obliterative pulmonary vascular remodeling remain elusive. Hypothesis: Therapeutic genome editing of endothelial Fabp4 will knockout FABP4 expression selectively in endothelial cells and inhibit PAH in mice and rats. Methods: Employing the newly developed endothelial cell (EC)-targeted nanoparticle delivery technology, plasmid DNA expressing CRISPR/Cas9 controlled by Cdh5 promoter and Fabp4 -specific guide RNAs driven by U6 promoter was administered i.v. to adult SD rats and Egln1 Tie2Cre mice which exhibit severe PAH and obliterative pulmonary vascular remodeling. One week after nanoparticle administration, the rats were injected with a single dose of monocrotaline (MCT) to induce PAH. At 4 weeks post-MCT, right ventricular systolic pressure (RVSP), ratio of right ventricular versus left ventricular plus septum (RV/LV+S) and pulmonary vascular remodeling were determined. Pharmacological FABP4 inhibitor was also employed to treat MCT rats as a comparison. Similarly, the pulmonary hypertensive phenotype in genome-edited Egln1 Tie2Cre mice was also characterized. Results: Nanoparticle delivery of the all-in-one CRISPR rCdh5 plasmid DNA knockout Fabp4 selectively in endothelial cells in adult rats and Egln1 Tie2Cre mice leading to reduced RVSP, RV hypertrophy and pulmonary vascular remodeling in MCT rats and also in Egln1 Tie2Cre mice. Obliterative pulmonary vascular remodeling seen in Egln1 Tie2Cre mice was inhibited and the mortality rate in endothelial Fabp4-deficient Egln1 Tie2Cre mice was reduced. Treatment of FABP4 inhibitor also inhibits PAH in MCT rats. We also observed a marked increase of FABP4 expression in endothelial cells of lung samples of IPAH patients. Overexpression of FABP4 in primary cultures of human lung microvascular endothelial cells resulted in a 70% increase of cell proliferation. Conclusions: These findings demonstrate endothelial FABP4 is a promising target for PAH therapy. EC-targeted nanoparticle delivery of the genome editing system may represent an effective and safer gene therapy approach for PAH treatment.

Light at the ENDothelium-role of Sox17 and Runx1 in endothelial dysfunction and pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a progressive disease that is characterized by an obliterative vasculopathy of the distal pulmonary circulation. Despite significant progress in our understanding of the pathophysiology, currently approved medical therapies for PAH act primarily as pulmonary vasodilators and fail to address the underlying processes that lead to the development and progression of the disease. Endothelial dysregulation in response to stress, injury or physiologic stimuli followed by perivascular infiltration of immune cells plays a prominent role in the pulmonary vascular remodeling of PAH. Over the last few decades, our understanding of endothelial cell dysregulation has evolved and brought to light a number of transcription factors that play important roles in vascular homeostasis and angiogenesis. In this review, we examine two such factors, SOX17 and one of its downstream targets, RUNX1 and the emerging data that implicate their roles in the pathogenesis of PAH. We review their discovery and discuss their function in angiogenesis and lung vascular development including their roles in endothelial to hematopoietic transition (EHT) and their ability to drive progenitor stem cells toward an endothelial or myeloid fate. We also summarize the data from studies that link mutations in Sox17 with an increased risk of developing PAH and studies that implicate Sox17 and Runx1 in the pathogenesis of PAH. Finally, we review the results of recent studies from our lab demonstrating the efficacy of preventing and reversing pulmonary hypertension in animal models of PAH by deleting RUNX1 expression in endothelial or myeloid cells or by the use of RUNX1 inhibitors. By investigating PAH through the lens of SOX17 and RUNX1 we hope to shed light on the role of these transcription factors in vascular homeostasis and endothelial dysregulation, their contribution to pulmonary vascular remodeling in PAH, and their potential as novel therapeutic targets for treating this devastating disease.

Effects of Face-to-Face Nursing Support on Optimal Adherence to Oral Titratable PAH Therapies

Background Therapies currently available to pulmonary arterial hypertension (PAH) patients do not reverse the disease; however, they improve pulmonary hemodynamics, offer symptomatic relief, and lengthen the time to clinical worsening. These therapies do not come without their challenges, which include side effects and compliance with challenging titration regimens. Health care providers, particularly nurses, play a significant role in improving patient medication adherence. In-home nurse visits offer disease state education, set medication expectations, and provide support tools for patients when experiencing adverse events that may lead to therapy discontinuation. The purpose of this study is to determine the impact that in-home, face-to-face nursing visits have on optimal adherence to oral PAH therapies. Methods We identified patients who received an oral PAH drug (riociguat, selexipag, or treprostinil) supported by a nursing program (study group) and patients who received an oral PAH drug (bosentan, ambrisentan, or macitentan) not supported by a nursing program (control group) using CVS Health pharmacy data from January 1, 2018, to June 30, 2019. A logistic regression model examined demographic and medication factors associated with adherence. Results From January 2018 to June 2019, we identified 107 patients in the study group and 213 patients in the control group. After 6 months, patients in the study group reported 0.6 more fill counts (5.1 vs 4.5; P = .002) and an 11% higher medication possession ratio (MPR) than those in the control group (86.4% vs 75.0%; P = .001). After adjusting for patient characteristics, control patients tended to be more likely to drop therapy in the first 6 months after the index fill (hazard ratio = 1.52; P = .064). After 6 months, the study group reported higher rates of therapy persistence than the control group (72.0% vs 60.6%; P &amp;lt; .05). Conclusions Patients receiving oral PAH therapies (riociguat, selexipag, or treprostinil) supported through a visiting nurse program had significantly higher rates of optimal adherence as demonstrated by a statistically significant improvement in the MPR and a higher prescription fill count than a control group. Ultimately, a multidisciplinary approach supporting the patient and providing patient education, proper motivation, and face-to-face nursing may support improved patient outcomes.

Tumor Necrosis Factor-α-Induced Protein-8-like 2 Transfected Adipose-Derived Stem Cells Regulated the Dysfunction of Monocrotaline Pyrrole-Induced Pulmonary Arterial Smooth Muscle Cells and Pulmonary Arterial Endothelial Cells.

Pulmonary arterial hypertension (PAH) is characterized by pulmonary arterial endothelial cell (PAEC) dysfunction and pulmonary arterial smooth muscle cell (PASMC) activation. For decades, the therapies for PAH based on stem cells have been shown to be effective. Meanwhile, tumor necrosis factor-α-induced protein-8-like 2 (TIPE2) promote the viability of human amniotic mesenchymal stem cells. Therefore, we aimed to explore the role of TIPE2 in adipose-derived stem cells (ADSCs) and the function of TIPE2-transfected ADSCs in the regulation of PAH. We first explored the role and underlying molecular mechanism of TIPE2 in viability and migration of ADSCs. Moreover, the ADSCs transfected with TIPE2 were cocultured with monocrotaline pyrrole (MCTP)-stimulated PASMCs or PAECs. The effects and mechanisms of TIPE2-transfected ADSCs on MCTP-induced PASMCs and PAECs were further investigated. The results showed that TIPE2 overexpression promoted viability and migration of ADSCs by activating the TLR4-ERK1/2 pathway. In addition, TIPE2-transfected ADSCs inhibited the abnormal proliferation and the impaired apoptosis of PASMCs via NF-κB signaling and promoted the conversion of PASMCs from synthetic to contractile. Meanwhile, TIPE2-transfected ADSCs reduced the apoptosis, endothelial-to-mesenchymal transition, and migration of PAECs via PI3K/AKT signaling after MCTP treatment. MCTP-induced oxidative stress and inflammation of PAECs were significantly decreased by TIPE2-transfected ADSCs. In rat model, TIPE2-ADSCs administration further decreased the monocrotaline-induced increase in the right ventricular systolic pressure and ratio of right ventricle weight/left ventricle and septa weight (L + S) and right ventricle weight/body weight compared with the ADSCs group. In conclusion, TIPE2-transfected ADSCs dramatically attenuated the PAH via inhibiting the dysfunction of PASMCs and PAECs.

Navigating the Sotatercept landscape: A meta-analysis of clinical outcomes.

Pulmonary arterial hypertension (PAH) is a widespread condition that affects around 1% of the global population, with a higher prevalence among older individuals. The approach to managing PAH has undergone significant changes, requiring extensive treatment strategies. Sotatercept, an FDA-approved medication, has recently attracted attention for its potential role in PAH therapy. However, information on its safety and effectiveness is scarce. In this study, we performed a meta-analysis of existing randomized clinical trials to assess the impact of Sotatercept on PAH patients. Our findings revealed that those treated with Sotatercept showed greater improvement in pulmonary vascular resistance and World Health Organization functional class compared with placebo recipients. The occurrence of adverse events was similar between both groups. Importantly, the Sotatercept group displayed a considerably higher number of cases with an increase in hemoglobin levels. Considering that about 33% of PAH patients experience anemia and both anemia and polycythemia can adversely affect disease prognosis, additional research is necessary to establish the potential advantages and disadvantages of Sotatercept as a treatment choice, specifically regarding its erythropoietic properties.

A Bioinformatic Algorithm based on Pulmonary Endoarterial Biopsy for Targeted Pulmonary Arterial Hypertension Therapy.

Optimal pharmacological therapy for pulmonary arterial hypertension (PAH) remains unclear, as pathophysiological heterogeneity may affect therapeutic outcomes. A ranking methodology based on pulmonary vascular genetic expression analysis could assist in medication selection and potentially lead to improved prognosis. To describe a bioinformatics approach for ranking currently approved pulmonary arterial antihypertensive agents based on gene expression data derived from percutaneous endoarterial biopsies in an animal model of pulmonary hypertension. We created a chronic PAH model in Micro Yucatan female swine by surgical anastomosis of the left pulmonary artery to the descending aorta. A baseline catheterization, angiography and pulmonary endoarterial biopsy were performed. We obtained pulmonary vascular biopsy samples by passing a biopsy catheter through a long 8 French sheath, introduced via the carotid artery, into 2- to 3-mm peripheral pulmonary arteries. Serial procedures were performed on days 7, 21, 60, and 180 after surgical anastomosis. RNA microarray studies were performed on the biopsy samples. Utilizing the medical literature, we developed a list of PAH therapeutic agents, along with a tabulation of genes affected by these agents. The effect on gene expression from pharmacogenomic interactions was used to rank PAH medications at each time point. The ranking process allowed the identification of a theoretical optimum three-medication regimen. We describe a new potential paradigm in the therapy for PAH, which would include endoarterial biopsy, molecular analysis and tailored pharmacological therapy for patients with PAH.

Pulmonary arterial hypertension drugs can partially restore altered angiogenic capacities in bmpr2-silenced human lung microvascular endothelial cells.

Mutations in the bone morphogenetic protein receptor type 2 (bmpr2) gene and signaling pathway impairment are observed in heritable and idiopathic pulmonary arterial hypertension (PAH). In PAH, endothelial dysfunction is currently handled by drugs targeting the endothelin-1 (ET-1), nitric oxide (NO), and prostacyclin (PGI2) pathways. The role of angiogenesis in the disease process and the effect of PAH therapies on dysregulated angiogenesis remain inconclusive. We aim to investigate in vitro whether (i) bmpr2 silencing can impair angiogenic capacity of human lung microvascular endothelial cells (HLMVECs) and (ii) PAH therapies can restore them. The effects of macitentan (ET-1), tadalafil (NO), and selexipag (PGI2), on BMPRII pathway activation, endothelial barrier function, and angiogenesis were investigated in bmpr2-silenced HLMVECs. Stable bmpr2 silencing resulted in impaired migration and tube formation in vitro capacity. Inhibition of ET-1 pathway was able to partially restore tube formation in bmpr2-silenced HLMVECs, whereas none of the therapies was able to restore endothelial barrier function, no deleterious effects were observed. Our findings highlight the potential role of BMPRII signaling pathway in driving pulmonary endothelial cell angiogenesis. In addition, PAH drugs display limited effects on endothelial function when BMPRII is impaired, suggesting that innovative therapeutic strategies targeting BMPRII signaling are needed to better rescue endothelial dysfunction in PAH.

Restoration of Foxp3+ Regulatory T Cells by HDAC-Dependent Epigenetic Modulation Plays a Pivotal Role in Resolving Pulmonary Arterial Hypertension Pathology.

Rationale: Immune dysregulation is a common feature of pulmonary arterial hypertension (PAH). Histone deacetylase (HDAC)-dependent transcriptional reprogramming epigenetically modulates immune homeostasis and is a novel disease-oriented approach in modern times. Objectives: To identify a novel functional link between HDAC and regulatory T cells (Tregs) in PAH, aiming to establish disease-modified biomarkers and therapeutic targets. Methods: Peripheral blood mononuclear cells were isolated from patients with idiopathic PAH (IPAH) and rodent models of pulmonary hypertension (PH): monocrotaline rats, Sugen5416-hypoxia rats, and Treg-depleted mice. HDAC inhibitor vorinostat (suberoylanilide hydroxamic acid, SAHA) was used to examine the immune modulatory effects invivo, ex vivo, and invitro. Measurements and Main Results: Increased HDAC expression was associated with reduced Foxp3+ Tregs and increased PD-1 (programmed cell death-1) signaling in peripheral blood mononuclear cells from patients with IPAH. SAHA differentially modified a cluster of epigenetic-sensitive genes and induced Foxp3+ Treg conversion in IPAH T cells. Rodent models recapitulated these epigenetic aberrations and T-cell dysfunction. SAHA attenuated PH phenotypes and restored FOXP3 transcription and Tregs in PH rats; interestingly, the effects were more profound in female rats. Selective depletion of CD25+ Tregs in Sugen5416-hypoxia mice neutralized the effects of SAHA. Furthermore, SAHA inhibited endothelial cytokine/chemokine release upon stimulation and subsequent immune chemotaxis. Conclusions: Our results indicated HDAC aberration was associated with Foxp3+ Treg deficiency and demonstrated an epigenetic-mediated mechanism underlying immune dysfunction in PAH. Restoration of Foxp3+ Tregs by HDAC inhibitors is a promising approach to resolve pulmonary vascular pathology, highlighting the potential benefit of developing epigenetic therapies for PAH.