Pulmonary veno-occlusive disease (PVOD) is a rare and devastating cause of pulmonary hypertension that is characterized histologically by widespread fibrous intimal proliferation of septal veins and preseptal venules and is frequently associated with pulmonary capillary dilatation and proliferation(1,2). PVOD is categorized into a separate pulmonary arterial hypertension-related group in the current classification of pulmonary hypertension(3). PVOD presents either sporadically or as familial cases with a seemingly recessive mode of transmission(4). Using whole-exome sequencing, we detected recessive mutations in EIF2AK4 (also called GCN2) that cosegregated with PVOD in all 13 families studied. We also found biallelic EIF2AK4 mutations in 5 of 20 histologically confirmed sporadic cases of PVOD. All mutations, either in a homozygous or compound-heterozygous state, disrupted the function of the gene. These findings point to EIF2AK4 as the major gene that is linked to PVOD development and contribute toward an understanding of the complex genetic architecture of pulmonary hypertension.
MircoRNAs (miRNAs) are small non-coding RNAs that govern the gene expression and, play significant role in the pathogenesis of heart failure. The detection of miRNAs in circulation of pulmonary hypertensive (PH) human subjects remains elusive. In the current study, we determined the pattern of miRNAs of mild-to-severe human PH subjects and, compared them with the control subjects by miRNA array. Blood was obtained using fluoroscopic and waveform guided catheterization from the distal (pulmonary artery) port of the catheter. A total 40 human subjects were included in the study and, the degree of PH was determined by mean pulmonary arterial pressure. Among several miRNAs in the array, we validated 14 miRNAs and, the data were consistent with the array profile. We identified several novel downregulated miRNAs (miR-451, miR-1246) and upregulated miRNAs (miR-23b, miR-130a and miR-191) in the circulation of PH subjects. Our study showed novel set of miRNAs which are dysregulated in PH and, are directly proportional to the degree of PH. These miRNAs may be considered as potential biomarker for early detection of PH.
Chronic obstructive pulmonary disease (COPD) is one of the most common causes of death worldwide. We report in an emphysema model of mice chronically exposed to tobacco smoke that pulmonary vascular dysfunction, vascular remodeling, and pulmonary hypertension (PH) precede development of alveolar destruction. We provide evidence for a causative role of inducible nitric oxide synthase (iNOS) and peroxynitrite in this context. Mice lacking were protected against emphysema and PH. Treatment of wild-type mice with the iNOS inhibitor N -(1-iminoethyl)-L-lysine (L-NIL) prevented structural and functional alterations of both the lung vasculature and alveoli and also reversed established disease. In chimeric mice lacking in bone marrow (BM)-derived cells, PH was dependent on from BM-derived cells, whereas emphysema development was dependent on from non-BM-derived cells. Similar regulatory and structural alterations as seen in mouse lungs were found in lung tissue from humans with end-stage COPD. ► ( ) loss protects mice from smoke-induced emphysema ► Pulmonary hypertension is dependent on iNOS activity in bone marrow-derived cells ► Emphysema is dependent on iNOS activity in non-BM-derived cells ► The iNOS inhibitor L-N6-(1-iminoethyl)-lysine improves established emphysema in mice Smoking-related damage can be reversed by inhibition of iNOS.
Pulmonary hypertension (PH) is characterized by increased proliferation and apoptosis resistance of pulmonary artery smooth muscle cells (PASMCs). Forkhead box O (FoxO) transcription factors are key regulators of cellular proliferation. Here we show that in pulmonary vessels and PASMCs of human and experimental PH lungs, FoxO1 expression is downregulated and FoxO1 is inactivated via phosphorylation and nuclear exclusion. These findings could be reproduced using ex vivo exposure of PASMCs to growth factors and inflammatory cytokines. Pharmacological inhibition and genetic ablation of FoxO1 in smooth muscle cells reproduced PH features in vitro and in vivo. Either pharmacological reconstitution of FoxO1 activity using intravenous or inhaled paclitaxel, or reconstitution of the transcriptional activity of FoxO1 by gene therapy, restored the physiologically quiescent PASMC phenotype in vitro, linked to changes in cell cycle control and bone morphogenic protein receptor type 2 (BMPR2) signaling, and reversed vascular remodeling and right-heart hypertrophy in vivo. Thus, PASMC FoxO1 is a critical integrator of multiple signaling pathways driving PH, and reconstitution of FoxO1 activity offers a potential therapeutic option for PH.
Pulmonary hypertension is one of the problems that can be encountered before liver transplantation. It is not expected in cases with no additional disease in postoperative period. Herein, we report on a 43-year-old woman who developed idiopathic pulmonary hypertension in the early postoperative period. Further investigation both pathologically and clinically is needed in patients undergoing living donor liver transplantation that may help to solve the problems such as pulmonary arterial hypertension before it occurs and manage complex hemodynamic changes successfully in the future.
Pulmonary hypertension (PH) is a heterogeneous disorder associated with a poor prognosis. Thus, the development of novel treatment strategies is of great interest. The enzyme arginase (Arg) is emerging as important player in PH development. The aim of the current study was to determine the expression of ArgI and ArgII as well as the effects of Arg inhibition in a rat model of PH. PH was induced in 35 Sprague-Dawley rats by monocrotaline (MCT, 60 mg/kg as single-dose). There were three experimental groups: sham-treated controls (control group, n = 11), MCT-induced PH (MCT group, n = 11) and MCT-induced PH treated with the Arg inhibitor Nω-hydroxy-nor-l-arginine (nor-NOHA; MCT/NorNoha group, n = 13). ArgI and ArgII expression was determined by immunohistochemistry and Western blot. Right ventricular systolic pressure (RVPsys) was measured and lung tissue remodeling was determined. Induction of PH resulted in an increase in RVPsys (81 ± 16 mmHg) compared to the control group (41 ± 15 mmHg, p = 0.002) accompanied by a significant elevation of histological sum-score (8.2 ± 2.4 in the MCT compared to 1.6 ± 1.6 in the control group, p < 0.001). Both, ArgI and ArgII were relevantly expressed in lung tissue and there was a significant increase in the MCT compared to the control group (p < 0.01). Arg inhibition resulted in a significant reduction of RVPsys to 52 ± 19 mmHg (p = 0.006) and histological sum-score to 5.8 ± 1.4 compared to the MCT group (p = 0.022). PH leads to increased expression of Arg. Arg inhibition leads to reduction of RVPsys and diminished lung tissue remodeling and therefore represents a potential treatment strategy in PH.
Pulmonary hypertension (PH) is a deadly vascular disease with enigmatic molecular origins. We found that vascular extracellular matrix (ECM) remodeling and stiffening are early and pervasive processes that promote PH. In multiple pulmonary vascular cell types, such ECM stiffening induced the microRNA-130/301 family via activation of the co-transcription factors YAP and TAZ. MicroRNA-130/301 controlled a PPARγ-APOE-LRP8 axis, promoting collagen deposition and LOX-dependent remodeling and further upregulating YAP/TAZ via a mechanoactive feedback loop. In turn, ECM remodeling controlled pulmonary vascular cell crosstalk via such mechanotransduction, modulation of secreted vasoactive effectors, and regulation of associated microRNA pathways. In vivo, pharmacologic inhibition of microRNA-130/301, APOE, or LOX activity ameliorated ECM remodeling and PH. Thus, ECM remodeling, as controlled by the YAP/TAZ-miR-130/301 feedback circuit, is an early PH trigger and offers combinatorial therapeutic targets for this devastating disease. Bertero et al. establish vascular matrix remodeling as an early, pervasive driver of pulmonary hypertension (PH) controlled by mechanoactive feedback from YAP/TAZ-microRNA-130/301 in multiple cell types. Inhibition of this circuit ameliorated matrix remodeling and PH, thus introducing promising cooperative therapies to treat this disease.
Forkhead box M1 (FoxM1) is a transcription factor that promotes cell proliferation by regulating a broad spectrum of genes that participate in cell cycle regulation, such as Cyclin B, CDC25B, and Aurora B Kinase. We have shown that hypoxia, a well-known stimulus for pulmonary hypertension (PH), induces FoxM1 in pulmonary artery smooth muscle cells (PASMC) in a HIF-dependent pathway, resulting in PASMC proliferation, while the suppression of FoxM1 prevents hypoxia-induced PASMC proliferation. However, the implications of FoxM1 in the development of PH remain less known. We determined FoxM1 levels in the lung samples of idiopathic PAH (pulmonary arterial hypertension) (IPAH) patients and hypoxia-induced PH mice. We generated constitutive and inducible smooth muscle cell (SMC)-specific FoxM1 knockdown or knockout mice as well as FoxM1 transgenic mice which overexpress FoxM1, and exposed them to hypoxia (10% O , 90% N ) or normoxia (Room air, 21% oxygen) for four weeks, and measured PH indices. We also isolated mouse PASMC (mPASMC) and mouse embryonic fibroblasts MEF) from these mice to examine the cell proliferation and expression levels of SMC contractile proteins. We showed that in hypertensive human lungs or mouse lungs, FoxM1 levels were elevated. Constitutive knockout of FoxM1 in mouse SMC caused early lethality, whereas constitutive knockdown of FoxM1 in mouse SMC prevented hypoxia-induced PH and PASMC proliferation. Inducible knockout of FoxM1 in SMC reversed hypoxia-induced pulmonary artery wall remodeling in existing PH. Overexpression of FoxM1 enhanced hypoxia-induced pulmonary artery wall remodeling and right ventricular hypertrophy in mice. Alteration of FoxM1 status did not affect hypoxia-induced hypoxia-inducible factor (HIF) activity in mice. Knockout of FoxM1 decreased PASMC proliferation and induced expression of SMC contractile proteins and TGF-β/Smad3 signaling. Our studies provide clear evidence that altered FoxM1 expression in PASMC contributes to PH and uncover a correlation between Smad3-dependent signaling in FoxM1-mediated proliferation and de-differentiation of PASMC.
Pulmonary hypertension is a fatal disease, however reliable prognostic tools are lacking. Heart rhythm complexity analysis is derived from non-linear heart rate variability (HRV) analysis and has shown excellent performance in predicting clinical outcomes in several cardiovascular diseases. However, heart rhythm complexity has not previously been studied in pulmonary hypertension patients. We prospectively analyzed 57 patients with pulmonary hypertension (31 with pulmonary arterial hypertension and 26 with chronic thromboembolic pulmonary hypertension) and compared them to 57 age- and sex-matched control subjects. Heart rhythm complexity including detrended fluctuation analysis (DFA) and multiscale entropy (MSE) and linear HRV parameters were analyzed. The patients with pulmonary hypertension had significantly lower mean RR, SDRR, pNN(20), VLF, LF, LF/HF ratio, DFA alpha 1, MSE slope 5, scale 5, area 1-5 and area 6-20 compared to the controls. Receiver operating characteristic curve analysis showed that heart rhythm complexity parameters were better than traditional HRV parameters to predict pulmonary hypertension. Among all parameters, scale 5 had the greatest power to differentiate the pulmonary hypertension patients from controls (AUC: 0.845, P < 0.001). Furthermore, adding heart rhythm complexity parameters significantly improved the discriminatory power of the traditional HRV parameters in both net reclassification improvement and integrated discrimination improvement models. In conclusion, the patients with pulmonary hypertension had worse heart rhythm complexity. MSE parameters, especially scale 5, had excellent single discriminatory power to predict whether or not patients had pulmonary hypertension.