The Butrous Foundation Young Investigator Award
The Butrous Foundation Young Investigator Award recognises early-career researchers working in pulmonary hypertension.
Established by Ghazwan Butrous, one of PVRI’s founders, the award is presented each year at our Annual Congress to a promising young investigator under 35. The winner is selected by the Congress Scientific Organising Committee for the best abstract.
"The Butrous Foundation supports young scientists by fostering scientific creativity and communication skills, inspiring the next generation of researchers"
Ghazwan Butrous, Co-founder of PVRI
Previous award winners
Platelet Activation and Macrophage Recruitment Drive Vascular Dysfunction in a Murine Model of Sickle Cell Pulmonary Hypertension
Pulmonary hypertension (PH) is a severe and life-limiting complication of sickle cell disease (SCD). Chronic hemolysis and hypoxia promote release of cell-free hemoglobin and reactive oxygen species (ROS), generating an oxidizing extracellular milieu that contributes to vascular injury. Platelet activation and immune cell recruitment are increasingly recognized as drivers of SCD-associated PH (SCD-PH), but the mechanisms linking extracellular redox imbalance to platelet dysfunction and inflammation remain poorly defined. Transgenic SCD (Berkeley, Berk-SS) and wild-type (WT) mice were maintained under normoxic or chronic hypoxic conditions. Platelet activation was assessed by flow cytometry for P-selectin and activated integrin αIIbβ3. Platelet–leukocyte aggregates (PLAs) and macrophage phenotypes were evaluated by flow cytometry and lung histopathology. Hemodynamics were determined by right heart catheterization to obtain right ventricular systolic pressure (RVSP), ejection fraction, and pulmonary vascular remodeling indices. Compared to WT controls, Berk-SS platelets exhibited markedly elevated P-selectin, activated αIIbβ3, and increased PLAs. Lung sections from hypoxic Berk-SS mice demonstrated prominent accumulation of CD169⁺ macrophages, absent in WT mice, suggesting redox-driven macrophage recruitment. Proteomic analysis of lung macrophages identified hypoxia-induced dysregulation of platelet-related proteins, including platelet-activating factor acetylhydrolase 2 (PAFAH2) and PECAM1/CD31, implicating altered platelet–macrophage signaling in vascular inflammation. Strikingly, depletion of macrophages with clodronate significantly improved RV contractility, PA–RV coupling, and ejection fraction relative to vehicle controls, supporting a pathogenic role of macrophage–platelet interactions in SCD-PH.
These findings identify platelet activation and macrophage recruitment as key contributors to pulmonary vascular dysfunction in SCD-PH. Ongoing studies aim to define the upstream triggers of these interactions and their potential as therapeutic targets to prevent vascular remodeling in SCD.
Impact of IRG1/Itaconate Axis on Cardiopulmonary Phenotype: Linking Bone Marrow Dynamics to Inter-Organ Communication
Pulmonary hypertension (PH) is a progressive and lethal cardiopulmonary disorder characterized by pulmonary vascular remodeling and right ventricular hypertrophy. Bone marrow (BM)-derived hematopoietic cells, particularly myeloid cells contribute to the process of pulmonary vascular remodeling. Immune-Responsive Gene 1 (IRG1) encodes cis-aconitate decarboxylase enzyme, responsible for producing itaconate in macrophages in inflammatory phase. However, the association of IRG1/itaconate axis with the cardiovascular system and PH progression remains largely unknown. Here, we reveal that Irg1 − /− mice exhibit baseline pulmonary vascular remodeling, cardiac hypertrophy and dysfunction which are exacerbated by hypoxic exposure. Immune profiling revealed the infiltration of macrophages and dendritic cells into the lung and heart of Irg1 − /− mice. Adoptive transfer of BM from Irg1-deficient mice into naïve WT mice derives cardiac hypertrophy, emphasizing the strong contribution of BM to cardiac dysfunction under Irg1 deficiency. We assessed the multipotency of hematopoietic stem progenitor cells (HSPCs), serving as immune cells progenitor in Irg1 − /− mice. These mice exhibited a reduction in long-term (LT) HSCs, alongside a pronounced shift towards lymphoid-primed multipotent progenitors (MPP-Ly). HSPCs from Irg1 − /− mice exhibited differential transcriptomic activation of immunometabolic pathways, with significant enrichment in NLRP3 inflammasome, complement system activation, and purine metabolism pathways, coupled with a dysregulated metabolomic profile. Notably, the immunometabolic modulatory effect of itaconate was investigated in vitro and in vivo, where 4-octyl-itaconate (4-OI) treatment diminishes the proliferation of pulmonary vascular cells from human PH patients. Moreover, administration of 4-OI in a therapeutic approach attenuates monocrotaline-induced PH in rats. In conclusion, our findings indicate that IRG1/itaconate axis deficiency drives cardiopulmonary phenotype by dysregulating HSPC differentiation and mobilization through immunometabolic alterations, ultimately leading to pulmonary vascular remodeling and cardiac hypertrophy. PH phenotype could be mitigated through itaconate administration, highlighting its potential as a therapeutic strategy for PH and related cardiac complications.
Screening patients with schistosomiasis associated hepatosplenic disease for pulmonary hypertension in Ethiopia and Zambia
Schistosomiasis is a major cause of pulmonary arterial hypertension (PAH) worldwide, but the prevalence and risk factors for schistosomiasis-associated PAH (SchPAH) development are not well understood. Schistosomiasis-associated hepatosplenic disease (SchHSD) is thought to be a major risk factor for PAH development. Herein, we describe our plans for prospectively screening SchHSD subjects for clinical evidence of PAH at two major academic medical centers and national referral hospitals in Addis Ababa, Ethiopia and Lusaka, Zambia. The screening study will primarily be conducted by echocardiography, in addition to clinical assessments. Plasma samples will be drawn and banked for subsequent analysis based on preclinical animal model rationale. If successful, this study will demonstrate feasibility of conducting prospective cohort studies of SchPAH screening in schistosomiasis-endemic regions of Africa, and provide initial data on clinic-based disease prevalence and potential mechanistic biomarkers underlying disease pathogenesis.
Long-term effects of pulmonary endarterectomy on right ventricular remodeling in chronic thromboembolic pulmonary hypertension
Surgical removal of thromboembolic material by pulmonary endarterectomy (PEA) leads to improvement of right ventricular (RV) function in the majority of chronic thromboembolic pulmonary hypertension (CTEPH) patients. However, RV mass does not always normalize post-PEA. Whether this is the result of extracellular matrix expansion (diffuse interstitial fibrosis) or cellular hypertrophy is unknown. We prospectively included 25 CTEPH patients treated with PEA (mean pulmonary artery pressure post-PEA 23 ± 9 mmHg). Structured follow-up measurements were performed before and 6- and 18-months post-PEA. To study changes in RV remodeling, extracellular volume fraction (ECV) of the RV free wall (RVFW) by cardiac MRI was measured and was used to divide the myocardium into cellular and matrix volume. With single beat pressure–volume loop analysis, load-independent RV diastolic stiffness (Eed) was assessed. Circulating collagen biomarkers were analyzed with an enzyme-linked immunosorbent assay to determine the contribution of collagen metabolism. Right ventricular mass decreased significantly but did not normalize 6 months post-PEA (from 43 ± 15 to 27 ± 11 g/m2, p < 0.001). The ECV in the RVFW increased post-PEA (from 31 ± 4 to 34 ± 4%, p = 0.013) and was the result of a larger reduction in cellular volume relative to matrix volume (−38% vs. −30%, P-interaction = 0.0013). The Eed significantly improved and normalized after PEA, but Eed corrected for relative wall thickness did not reduce post-PEA. Levels of matrix metalloproteinase 1 [5 (1–11) to 4 (1–9) ng/mL, p = 0.3], tissue inhibitor of metalloproteinases 1 [247 (196–313) to 221 (145–283) ng/mL, p = 0.036] and transforming growth factor-β [9 (5–16) to 6 (3–11) ng/mL, p = 0.07] were elevated at baseline and remained elevated post-PEA. No further improvements were observed between 6 and 18 months after PEA. Although cellular hypertrophy regresses post-PEA, there is a relative increase in extracellular volume, indicating that extracellular matrix regression is not complete in the RV. This was accompanied by elevated levels of collagen biomarkers suggestive of an active collagen turnover.
Epigenome-wide profiling uncovers novel gene regulatory networks in human pulmonary arterial hypertension
Evidence of epigenome-wide alterations that facilitates normal vascular cells to acquire and exhibit pro-proliferative, apoptotic-resistant, pro-inflammatory phenotypes in pulmonary arterial hypertension (PAH) remains unexplored at a genome-wide scale. Our major objectives were to (1) employ multiple next-generation sequencing (NGS) approaches to profile vascular cell-specific epigenomic alterations in human setting, (2) identify gene regulatory signatures, (3) identify transcription factor networks associated with hypertensive phenotypes, (4) evaluate the therapeutic potential of epigenetic intervention. Cell-specific transcriptome profiling revealed differential expression of 2069 genes (two-fold) in ex vivo isolated pulmonary artery adventitial fibroblasts (PAFBs) from idiopathic PAH (IPAH) and human donors, which strongly indicated the existence of genome-scale alterations in transcription regulatory mechanisms of PAH. To map the PAH-associated epigenomic alterations in the chromatin landscape of PAH vascular cells, we employed ChIP-seq to generate genome-wide maps for RNA polymerase II occupancy, histone modifications associated with euchromatin (H3K9/K14ac, H3K4me3, pan-H4Kac), heterochromatin (H3K27me3, H3K9me3) and enhancers (H3K27ac, H3K4me1). Bioinformatic analysis confirmed massive epigenetic alterations in both histone acetylation and methylation pattern in IPAH, which corroborated with aberrant expression and recruitment of histone-modifying enzymes in IPAH. KEGG analysis of epigenetic signatures revealed association with ABC transporters, smooth muscle contraction, cGMP-PKG, renin secretion, NF-κB, TGFβ and cancer-signaling pathways. Integrative analysis also revealed acquisition of pro-hypertensive gene expression signatures in PAH, that includes differential regulation of novel transcription factor networks (SOX, ID, HES, GLI, GATA, REL) that may altogether coordinate the pro-proliferative and pro-inflammatory phenotypes in PAH. Aberrant epigenetic signatures in PAH were reversed by targeting chromatin-modifying enzymes ex vivo and in vivo. In conclusion, integrative analysis of vascular cell-specific epigenomics data confirmed genome-scale alterations in the chromatin landscape and DNA accessibility leading to aberrant transcriptional responses in PAH. This genome-scale study also uncovered novel regulatory factors, signaling networks and potential targets for therapeutic intervention.
Inflammatory biomarker profiles at baseline and one-year follow-up in pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH)
Pulmonary hypertension (PH) is a devastating disease characterized by increased pulmonary arterial pressure, leading to right heart failure and death. Accumulating evidence is showing increased levels of circulating cytokines, associated with poor prognosis, in pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) patients. Currently, it is unknown if these circulating cytokine levels are already elevated at diagnosis, and if different cytokine profiles exist in different PAH subsets. Our aim was to investigate circulating inflammatory biomarkers at diagnosis (treatment-naïve/baseline) and after one-year follow-up in PAH-subsets and CTEPH patients. Plasma samples from 50 PAH patients (16 idiopathic (I)PAH, 24 Connective Tissue Disease (CTD)-PAH, and 10 Congenital Heart Disease (CHD)-PAH), 37 CTEPH patients, and 18 healthy controls (HC) were measured at diagnosis (baseline) and in a subset of patients at one-year follow-up for circulating inflammatory biomarkers (VEGF-A, TGF-β, CXCL-9, CXCL-13, interleukin (IL)-1β, IL-6, IL-8, IL-10) and were related to hemodynamic parameters. Results show that at baseline, plasma IL-6 concentrations were elevated in CTD-PAH, IL-10 was increased in IPAH, and TGF-β was significantly enhanced in IPAH and CHD-PAH patients compared to HC. CXCL-9 was elevated in patients (IPAH, CTD-PAH, and CTEPH) compared to HC, whereas CXCL-13 was higher in CTD-PAH compared to controls and CTEPH patients. No differences were observed for VEGF-A, IL-1b, and IL-8. In our cohort, no significant hemodynamic correlations were found between circulating cytokines and hemodynamic parameters at baseline. After one-year follow-up, the concentrations of IL-8, IL-10, and TGF-β increased significantly in paired samples from CTD-PAH patients. In conclusion, our findings indicate that different inflammatory profiles in PH exist at diagnosis, seemingly independent of WHO subgroup classification within PAH subsets and CTEPH. After one-year of treatment, these inflammatory profiles differentially changed for each PH subgroup. Additional analyses are required to determine the prognostic and clinical implications of these results.
Read all PVRI 2020 Lima abstracts
Interleukin-6 is Independently Associated with Right Ventricular Function in Pulmonary Arterial Hypertension
Objective: To determine if interleukin-6 (IL6) and right ventricular (RV) function are independently associated in pulmonary arterial hypertension (PAH)
Background: Elevated serum levels of IL6 identify PAH patients at increased risk of mortality, but the mechanism underlying this observation remains incompletely defined. Interestingly, preclinical and clinical data have revealed an association between IL6 and cardiac dysfunction, but
the effect of IL6 on RV function, the major determinant of long-term outcomes in PAH, has not been examined.
Methods: We performed a single-center study of 40 patients with PAH from an institutional registry and analyzed how RV function was related to IL6.
Results: IL6 had a negative logarithmic relationship with RV function as determined by echocardiography. There were no significant relationships between IL6 and mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR), and only a weak association with pulmonary arterial compliance (PAC). When the cohort was divided by median IL6 level, patients with higher IL6 had significantly worse RV function on echocardiography, higher right atrial pressures, and reduced cardiac index and stroke volume despite having similar mPAP, PVR, and PAC. Finally, on multivariate analysis, IL6 was associated with RV function even after adjusting for PVR and PAC.
Conclusions: IL6 is independently associated with RV function in PAH, and patients with higher IL6 levels had more severe RV dysfunction. These findings suggest IL6 may contribute to RV dysfunction and thus could explain the poor survival in PAH patients with elevated IL6.
Oxidation of PKGIα in the lung mediates an endogenous adaptation to pulmonary hypertension
Exposure to chronic hypoxia causes pulmonary hypertension (PH), vascular remodelling, right ventricular (RV) hypertrophy and subsequent cardiac failure. Protein kinase G Iα (PKGIα) is susceptible to oxidation, forming a disulfide homodimer associated with kinase targeting involved in vasodilation and diastolic relaxation. Here we investigated the role of pulmonary PKGIα redox state in hypoxic PH. We found that chronic hypoxia caused pulmonary PKGIα oxidation in mice, as determined at 3 or 28 days, compared to normoxia, likely due to upregulation of H2O2-producing enzymes NADPH oxidase 4 (NOX4), extracellular superoxide dismutase (SOD3), and H2S-producing enzyme cystathionine gamma-lyase (CSE) in the lungs. Increased pulmonary PKGIα oxidation, NOX4 and CSE protein expression were observed in lungs from PAH patients. Chronic CSE inhibition potentiated RV pressure and hypertrophy, and attenuated lung PKGIα oxidation, suggesting that the redox state of PKGIα may be mediated by the products of H2S oxidation such as polysulfide species. To dissect the potential role of oxidised PKGIα in hypoxic PH we employed redox-dead Cys42Ser PKGIα knock-in (KI) mice which are resistant to PKGIα oxidation. KI mice exposed to chronic hypoxia for 28 days developed increased pulmonary vascular resistance, potentiated RV hypertrophy and pressure, greater pulmonary myosin light chain phosphorylation, as well as excessive pro-growth signalling in the lungs, vascular muscularisation and enhanced transition of pulmonary endothelial cells to myofibroblasts, compared to wild-type mice. Pulmonary vessels from the KI mice demonstrated impaired vasodilatory responses to H2O2 compared to wild-type. Polysulfide treatment during chronic hypoxia lead to alleviation of RV hypertrophy in the wild-type, but not in the KI mice. We conclude that PKGIα oxidation may serve an important intrinsic adaptive mechanism that offsets increased pulmonary vascular resistance in PH and thus limits progression to heart failure. We suggest that drug-induced PKGIα oxidation might be beneficial in the PH treatment.
Molecular Imaging of the Human Pulmonary Vascular Endothelium in Pulmonary Hypertension: A Phase II Safety and Proof of Principle Trial
The adrenomedullin receptor is densely expressed in the pulmonary vascular endothelium. PulmoBind, an adrenomedullin receptor ligand, was developed for molecular diagnosis of pulmonary vascular disease (PVD). We evaluated the safety of PulmoBind SPECT imaging and its capacity to detect PVD associated with pulmonary hypertension (PH) in a human phase II study. Thirty patients with pulmonary arterial hypertension (PAH; n = 23) or chronic thromboembolic PH (CTEPH; n = 7) in WHO functional class II (n = 26) or III (n = 4) were compared to 15 healthy controls. Lung SPECT was performed after injection of 15 mCi 99mTc-PulmoBind in supine position. Qualitative and semi-quantitative analyses of lung uptake were performed. Reproducibility of repeated testing was evaluated in controls after one month. PulmoBind injection was well tolerated without any serious adverse event. Imaging was markedly abnormal in PH with ∼50% of participants showing moderate to severe heterogeneity of moderate to severe extent. The abnormalities were unevenly distributed between the right and left lungs as well as within each lung. Segmental defects compatible with pulmonary embolism were present in 7/7 patients with CTEPH and in 2/23 patients with PAH. There were no segmental defects in controls. The PulmoBind activity distribution index, a parameter indicative of heterogeneity, was elevated in PH (65% ± 28%) vs. controls (41% ± 13%; P = 0.0003). In the only participant with vasodilator-responsive idiopathic PAH, PulmoBind lung SPECT was completely normal. Repeat testing one month later in healthy controls was well tolerated and showed no significant variability of PulmoBind distribution. In this phase II study, molecular SPECT imaging of the pulmonary vascular endothelium using 99mTc-PulmoBind was safe and reproducible. PulmoBind showed potential to detect both pulmonary embolism and abnormalities indicative of PVD in PAH. Phase III studies with this novel agent are justified.
Supporting early-career researchers
Early-career researchers play an important role in the future of PH research. This award helps recognise their work, raise their profile, and encourage them to continue developing their ideas.
The award is also an example of how donors, foundations, and private supporters can support research through PVRI. By funding an award, grant, or early-career opportunity, you can help researchers gain recognition and continue their work to improve understanding, treatment, and care for people affected by PH.
