Rio Dumitrascu

Publications of Rio Dumitrascu

• Inducible NOS inhibition reverses tobacco-smoke-induced emphysema and pulmonary hypertension in mice.

  Authors: Michael Seimetz, Nirmal Parajuli, Alexandra Pichl, Florian Veit, Grazyna Kwapiszewska, Friederike C Weisel, Katrin Milger, Bakytbek Egemnazarov, Agnieszka Turowska, Beate Fuchs [......] Peter Jaksch, Rio Dumitrascu, Holger Garn, Robert Voswinckel, Sawa Kostin, Werner Seeger, Ralph T Schermuly, Friedrich Grimminger, Hossein A Ghofrani, Norbert Weissmann

  Cell. 10/2011; 147(2):293-305.

  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 vascularChronic 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 iNOS were protected against emphysema and PH. Treatment of wild-type mice with the iNOS inhibitor N(6)-(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 iNOS in bone marrow (BM)-derived cells, PH was dependent on iNOS from BM-derived cells, whereas emphysema development was dependent on iNOS 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.

• The role of dimethylarginine dimethylaminohydrolase in idiopathic pulmonary fibrosis.

  Authors: Soni Savai Pullamsetti, Rajkumar Savai, Rio Dumitrascu, Bhola Kumar Dahal, Jochen Wilhelm, Melanie Konigshoff, Dariusz Zakrzewicz, Hossein Ardeschir Ghofrani, Norbert Weissmann, Oliver Eickelberg, Andreas Guenther, James Leiper, Werner Seeger, Friedrich Grimminger, Ralph Theo Schermuly

  Science translational medicine. 06/2011; 3(87):87ra53.

  Idiopathic pulmonary fibrosis (IPF) is a progressive, dysregulated response to alveolar injury that culminates in compromised lung function from excess extracellular matrix production. AssociatedIdiopathic pulmonary fibrosis (IPF) is a progressive, dysregulated response to alveolar injury that culminates in compromised lung function from excess extracellular matrix production. Associated with high morbidity and mortality, IPF is generally refractory to current pharmacological therapies. We examined fibrotic lungs from mice and from patients with IPF and detected increased expression of dimethylarginine dimethylaminohydrolases (DDAHs)--key enzymes that metabolize asymmetric dimethylarginine (ADMA), which is an endogenous inhibitor of nitric oxide synthase, to form l-citrulline and dimethylamine. DDAHs are up-regulated in primary alveolar epithelial type II cells from these mice and patients where they are colocalized with inducible nitric oxide synthase. In cultured alveolar epithelial type II cells from bleomycin-induced fibrotic mouse lungs, inhibition of DDAH suppressed proliferation and induced apoptosis in an ADMA-dependent manner. In addition, DDAH inhibition reduced collagen production by fibroblasts in an ADMA-independent but transforming growth factor/SMAD-dependent manner. In mice with bleomycin-induced pulmonary fibrosis, the DDAH inhibitor L-291 reduced collagen deposition and normalized lung function. In bleomycin-induced fibrosis, inducible nitric oxide synthase inhibition decreased fibrosis, but an even stronger reduction was observed after inhibition of DDAH. Thus, DDAH inhibition reduces fibroblast-induced collagen deposition in an ADMA-independent manner and reduces abnormal epithelial proliferation in an ADMA-dependent manner, offering a possible therapeutic avenue for attenuation of pulmonary fibrosis.

• Increased expression of 5-hydroxytryptamine2A/B receptors in idiopathic pulmonary fibrosis: a rationale for therapeutic intervention.

  Authors: Melanie Königshoff, Rio Dumitrascu, Sergey Udalov, Oana Veronica Amarie, Rudolf Reiter, Friedrich Grimminger, Werner Seeger, Ralph Theo Schermuly, Oliver Eickelberg

  Thorax. 11/2010; 65(11):949-55.

  Idiopathic pulmonary fibrosis (IPF) has a poor prognosis and limited responsiveness to available treatments. It is characterised by epithelial cell injury, fibroblast activation and proliferation andIdiopathic pulmonary fibrosis (IPF) has a poor prognosis and limited responsiveness to available treatments. It is characterised by epithelial cell injury, fibroblast activation and proliferation and extracellular matrix deposition. Serotonin (5-hydroxytryptamine; 5-HT) induces fibroblast proliferation via the 5-HTR(2A) and 5-HTR(2B) receptors, but its pathophysiological role in IPF remains unclear. A study was undertaken to determine the expression of 5-HT receptors in IPF and experimental lung fibrosis and to investigate the effects of therapeutic inhibition of 5-HTR(2A/B) signalling on lung fibrosis in vivo and in vitro. Quantitative RT-PCR showed that the expression of 5-HTR(1A/B) and 5-HTR(2B) was significantly increased in the lungs of patients with IPF (n=12) and in those with non-specific interstitial pneumonia (NSIP, n=6) compared with transplant donors (n=12). The expression of 5-HTR(2A) was increased specifically in IPF lungs but not in NSIP lungs. While 5-HTR(2A) protein largely localised to fibroblasts, 5-HTR(2B) localised to the epithelium. To assess the effects of 5HTR(2A/B) inhibition on fibrogenesis in vivo, mice were subjected to bleomycin-induced lung fibrosis and treated with the 5-HTR(2A/B) antagonist terguride (or vehicle) in a therapeutic approach (days 14-28 after bleomycin). Terguride-treated mice had significantly improved lung function and histology and decreased collagen content compared with vehicle-treated mice. Functional in vitro studies showed that terguride is a potent inhibitor of transforming growth factor β(1)- or WNT3a-induced collagen production. The studies revealed an increased expression of 5-HTR(2A) specifically in IPF. Blockade of 5-HTR(2A/B) signalling by terguride reversed lung fibrosis and is thus a promising therapeutic approach for IPF.

• Activation of the WNT/β-catenin pathway attenuates experimental emphysema.

  Authors: Nikolaus Kneidinger, Ali Önder Yildirim, Jens Callegari, Shinji Takenaka, Maria Magdalena Stein, Rio Dumitrascu, Alexander Bohla, Ken R Bracke, Rory E Morty, Guy G Brusselle, Ralph Theo Schermuly, Oliver Eickelberg, Melanie Königshoff

  American journal of respiratory and critical care medicine. 10/2010; 183(6):723-33.

  Chronic obstructive pulmonary disease (COPD) is a devastating disease, for which no causal therapy is available. To characterize WNT/β-catenin signaling in COPD in humans and elucidate its potentialChronic obstructive pulmonary disease (COPD) is a devastating disease, for which no causal therapy is available. To characterize WNT/β-catenin signaling in COPD in humans and elucidate its potential role as a preventive and therapeutic target in experimental emphysema in mice. The expression, localization, and activity of WNT/β-catenin signaling was assessed in 12 COPD and 12 transplant donor samples using quantitative reverse transcriptase polymerase chain reaction, immunohistochemistry, and Western blotting. The role of WNT/β-catenin signaling was assessed in elastase- and cigarette smoke-induced emphysema and therapeutic modulation thereof in elastase-induced emphysema in TOPGAL reporter and wild-type mice in vivo. No differences in the mRNA expression profile of the main WNT/β-catenin signaling components were observed comparing COPD and donor lung homogenates. Immunohistochemical analysis revealed reduced numbers of nuclear β-catenin-positive alveolar epithelial cells in COPD. Similarly, WNT/β-catenin signaling was down-regulated in both experimental emphysema models. Preventive and therapeutic, WNT/β-catenin activation by lithium chloride attenuated experimental emphysema, as assessed by decreased airspace enlargement, improved lung function, reduced collagen content, and elevated expression of alveolar epithelial cell markers. Decreased WNT/β-catenin signaling is involved in parenchymal tissue destruction and impaired repair capacity in emphysema. These data indicate a crucial role of WNT/β-catenin signaling in lung repair mechanisms in vivo, and highlight WNT/β-catenin activation as a future therapeutic approach for emphysema.

• Effects of phosphodiesterase 4 inhibition on bleomycin-induced pulmonary fibrosis in mice

  Authors: Sergey Udalov, Rio Dumitrascu, Soni Pullamsetti, Hamza Al-tamari, Norbert Weissmann, Hossein Ghofrani, Andreas Guenther, Robert Voswinckel, Werner Seeger, Friedrich Grimminger, Ralph Schermuly

  BMC Pulmonary Medicine. 01/2010;

  Abstract Background Pulmonary fibrosis (PF) is a group of devastating and largely irreversible diseases. Phosphodiesterase (PDE) 4 is involved in the processes of remodeling and inflammation, whichAbstract Background Pulmonary fibrosis (PF) is a group of devastating and largely irreversible diseases. Phosphodiesterase (PDE) 4 is involved in the processes of remodeling and inflammation, which play key role in tissue fibrosis. The aim of the study was, therefore, to investigate the effect of PDE4 inhibition in experimental model of PF. Methods PF was induced in C57BL/6N mice by instillation of bleomycin. Pharmacological inhibition of PDE4 was achieved by using cilomilast, a selective PDE4 inhibitor. Changes in either lung inflammation or remodeling were evaluated at different stages of experimental PF. Lung inflammation was assessed by bronchoalveolar lavage fluid (BALF) differential cell count and reverse transcription quantitative polymerase chain reaction (RT-qPCR) for inflammatory cytokines. Changes in tissue remodeling were evaluated by pulmonary compliance measurement, quantified pathological examination, measurement of collagen deposition and RT-qPCR for late remodeling markers. Survival in all groups was analyzed as well. Results PDE4 inhibition significantly reduced the total number of alveolar inflammatory cells in BALF of mice with bleomycin-induced PF at early fibrosis stage (days 4 and 7). Number of macrophages and lymphocytes, but not neutrophils, was significantly reduced as well. Treatment decreased lung tumor necrosis factor (TNF)-α mRNA level and increased mRNA level of interleukin (IL)-6 but did not influence IL-1β. At later stage (days 14 and 24) cilomilast improved lung function, which was shown by increase in lung compliance. It also lowered fibrosis degree, as was shown by quantified pathological examination of Hematoxilin-Eosin stained lung sections. Cilomilast had no significant effect on the expression of late remodeling markers such as transforming growth factor (TGF)-β1 and collagen type Ia1 (COL(I)α1). However, it tended to restore the level of lung collagen, assessed by SIRCOL assay and Masson's trichrome staining, and to improve the overall survival. Conclusions Selective PDE4 inhibition suppresses early inflammatory stage and attenuates the late stage of experimental pulmonary fibrosis.

• Effects of phosphodiesterase 4 inhibition on bleomycin-induced pulmonary fibrosis in mice.

  Authors: Sergey Udalov, Rio Dumitrascu, Soni S Pullamsetti, Hamza M Al-tamari, Norbert Weissmann, Hossein A Ghofrani, Andreas Guenther, Robert Voswinckel, Werner Seeger, Friedrich Grimminger, Ralph T Schermuly

  BMC pulmonary medicine. 01/2010; 10:26.

  Pulmonary fibrosis (PF) is a group of devastating and largely irreversible diseases. Phosphodiesterase (PDE) 4 is involved in the processes of remodeling and inflammation, which play key role inPulmonary fibrosis (PF) is a group of devastating and largely irreversible diseases. Phosphodiesterase (PDE) 4 is involved in the processes of remodeling and inflammation, which play key role in tissue fibrosis. The aim of the study was, therefore, to investigate the effect of PDE4 inhibition in experimental model of PF. PF was induced in C57BL/6N mice by instillation of bleomycin. Pharmacological inhibition of PDE4 was achieved by using cilomilast, a selective PDE4 inhibitor. Changes in either lung inflammation or remodeling were evaluated at different stages of experimental PF. Lung inflammation was assessed by bronchoalveolar lavage fluid (BALF) differential cell count and reverse transcription quantitative polymerase chain reaction (RT-qPCR) for inflammatory cytokines. Changes in tissue remodeling were evaluated by pulmonary compliance measurement, quantified pathological examination, measurement of collagen deposition and RT-qPCR for late remodeling markers. Survival in all groups was analyzed as well. PDE4 inhibition significantly reduced the total number of alveolar inflammatory cells in BALF of mice with bleomycin-induced PF at early fibrosis stage (days 4 and 7). Number of macrophages and lymphocytes, but not neutrophils, was significantly reduced as well. Treatment decreased lung tumor necrosis factor (TNF)-alpha mRNA level and increased mRNA level of interleukin (IL)-6 but did not influence IL-1 beta. At later stage (days 14 and 24) cilomilast improved lung function, which was shown by increase in lung compliance. It also lowered fibrosis degree, as was shown by quantified pathological examination of Hematoxilin-Eosin stained lung sections. Cilomilast had no significant effect on the expression of late remodeling markers such as transforming growth factor (TGF)-beta1 and collagen type Ia1 (COL(I)alpha1). However, it tended to restore the level of lung collagen, assessed by SIRCOL assay and Masson's trichrome staining, and to improve the overall survival. Selective PDE4 inhibition suppresses early inflammatory stage and attenuates the late stage of experimental pulmonary fibrosis.

• Role of Epidermal Growth Factor Inhibition in Experimental Pulmonary Hypertension.

  Authors: Bhola Kumar Dahal, Teodora Cornitescu, Aleksandra Tretyn, Soni Savai Pullamsetti, Djuro Kosanovic, Rio Dumitrascu, Hossein Ardeschir Ghofrani, Norbert Weissmann, Robert Voswinckel, Gamal-Andre Banat, Werner Seeger, Friedrich Grimminger, Ralph Theo Schermuly

  American journal of respiratory and critical care medicine. 10/2009;

  RATIONALE: Epidermal growth factor (EGF) and its receptors play a role in cell proliferation and survival and are implicated in the pathobiology of pulmonary arterial hypertension (PAH). ObjectiveRATIONALE: Epidermal growth factor (EGF) and its receptors play a role in cell proliferation and survival and are implicated in the pathobiology of pulmonary arterial hypertension (PAH). Objective and methods: We investigated a) the effects of three clinically approved EGF receptor (EGFR) antagonists in vitro on rat pulmonary arterial smooth muscle cell (PASMC) proliferation and in vivo on experimental pulmonary hypertension (PH) induced by monocrotaline injection in rats and by chronic hypoxia in mice, and b) the expression of EGFR in the lung tissues from experimental and clinical PH. MEASUREMENTS AND MAIN RESULTS: The EGFR inhibitors, gefitinib, erlotinib and lapatinib inhibited the EGF-induced proliferation of PASMCs. In rats with established PH, gefitinib and erlotinib significantly reduced right ventricular systolic pressure (RVSP) and right ventricular hypertrophy (RVH). In addition, the medial wall thickness and muscularization of pulmonary arteries were improved. In contrast, lapatinib did not provide therapeutic benefit. These EGFR antagonists at their highest tolerable dose did not yield significant improvement in RVSP, RVH and pulmonary vascular remodeling in mice with chronic hypoxic PH. Moreover, no significant alteration in the EGFR expression was detected in the lung tissues from patients with idiopathic PAH (IPAH). CONCLUSION: The partial therapeutic efficacy of the EGFR antagonists in animal models of pulmonary hypertension and the absence of significant alteration in EGFR expression in the lungs from IPAH patients suggest that the EGFR do not represent a promising target for the treatment of pulmonary hypertension.

• The soluble guanylate cyclase activator HMR1766 reverses hypoxia-induced experimental pulmonary hypertension in mice.

  Authors: Norbert Weissmann, Sascha Hackemack, Bhola Kumar Dahal, Soni Savai Pullamsetti, Rajkumar Savai, Manish Mittal, Beate Fuchs, Thomas Medebach, Rio Dumitrascu, Martin van Eickels, Hossein Ardeschir Ghofrani, Werner Seeger, Friedrich Grimminger, Ralph Theo Schermuly

  American journal of physiology. Lung cellular and molecular physiology. 08/2009;

  Severe pulmonary hypertension (PH) is a disabling disease with high mortality, characterized by pulmonary vascular remodeling and right heart hypertrophy. In mice with PH induced by chronic hypoxia,Severe pulmonary hypertension (PH) is a disabling disease with high mortality, characterized by pulmonary vascular remodeling and right heart hypertrophy. In mice with PH induced by chronic hypoxia, we examined the acute and chronic effects of the soluble guanylate cyclase (sGC) activator HMR1766 on hemodynamics and pulmonary vascular remodeling. In isolated perfused mouse lungs from control animals, HMR1766 dose-dependently inhibited the pressor response of acute hypoxia. This dose response curve was shifted leftward when investigating the effects of HMR1766 in isolated lungs from chronic hypoxic animals for 21 days at 10% oxygen. Mice exposed for 21 or 35 days to chronic hypoxia developed pulmonary hypertension, right heart hypertrophy and pulmonary vascular remodeling. Treatment with HMR1766 (10mg/kg/day), after full establishment of pulmonary hypertension from day 21 to day 35, significantly reduced pulmonary hypertension, as measured continuously by telemetry. In addition, right ventricular (RV) hypertrophy and structural remodeling of the lung vasculature were reduced. Pharmacological activation of oxidized sGC partially reverses hemodynamic and structural changes in chronic hypoxia-induced experimental PH. Key words: Pulmonary hypertension, soluble guanylate cyclase (sGC), Hypoxia, Vascular remodeling.

• Evaluation of angiogenesis using micro-computed tomography in a xenograft mouse model of lung cancer.

  Authors: Rajkumar Savai, Alexander Claus Langheinrich, Ralph Theo Schermuly, Soni Savai Pullamsetti, Rio Dumitrascu, Horst Traupe, Wigbert Stephan Rau, Werner Seeger, Friedrich Grimminger, Gamal-Andre Banat

  Neoplasia (New York, N.Y.). 01/2009; 11(1):48-56.

  Quantitative evaluation of lung tumor angiogenesis using immunohistochemical techniques has been limited by difficulties in generating reproducible data. To analyze intrapulmonary tumor angiogenesis,Quantitative evaluation of lung tumor angiogenesis using immunohistochemical techniques has been limited by difficulties in generating reproducible data. To analyze intrapulmonary tumor angiogenesis, we used high-resolution micro-computed tomography (micro-CT) of lung tumors of mice inoculated with mouse Lewis lung carcinoma (LLC1) or human adenocarcinoma (A549) cell lines. The lung vasculature was filled with the radiopaque silicone rubber, Microfil, through the jugular vein (in vivo application) or pulmonary artery (ex vivo application). In addition, human adenocarcinoma lung tumor-bearing mice treated site-specifically with humanized monoclonal antibody (bevacizumab) against vascular endothelial growth factor. Quantitative analysis of lung tumor microvessels imaged with micro-CT showed that more vessels (mainly small, <0.02 mm(2)) were filled using the in vivo (5.4%) compared with the ex vivo (2.1%) method. Furthermore, bevacizumab-treated lung tumor-bearing mice showed significantly reduced lung tumor volume and lung tumor angiogenesis compared with untreated mice as assessed by micro-CT. Interestingly, microvascularization of mainly the smaller vessels (<0.02 mm(2)) was reduced after bevacizumab treatment. This observation with micro-CT was nicely correlated with immunohistochemical measurement of microvessels. Therefore, micro-CT is a novel method for investigating lung tumor angiogenesis, and this might be considered as an additional complementary tool for precise quantification of angiogenesis.

• Characterization of a murine model of monocrotaline pyrrole-induced acute lung injury.

  Authors: Rio Dumitrascu, Silke Koebrich, Eva Dony, Norbert Weissmann, Rajkumar Savai, Soni Pullamsetti, Hossein Ghofrani, Arun Samidurai, Horst Traupe, Werner Seeger, Friedrich Grimminger, Ralph Schermuly

  BMC pulmonary medicine. 01/2009; 8(1):25.

  ABSTRACT: Backgroud: New animal models of chronic pulmonary hypertension in mice are needed. The injection of monocrotaline is an established model of pulmonary hypertension in rats. The aim of thisABSTRACT: Backgroud: New animal models of chronic pulmonary hypertension in mice are needed. The injection of monocrotaline is an established model of pulmonary hypertension in rats. The aim of this study was to establish a murine model of pulmonary hypertension by injection of the active metabolite, monocrotaline pyrrole. METHODS: Survival studies, computed tomographic scanning, histology, bronchoalveolar lavage were performed, and arterial blood gases and hemodynamics were measured in animals which received an intravenous injection of different doses of monocrotaline pyrrole. RESULTS: Monocrotaline pyrrole induced pulmonary hypertension in Sprague Dawley rats. When injected into mice, monocrotaline pyrrole induced dose-dependant mortality in C57Bl6/N and BALB/c mice (dose range 6-15 mg/kg bodyweight). At a dose of 10 mg/kg bodyweight, mice developed a typical early-phase acute lung injury, characterized by lung edema, neutrophil influx, hypoxemia and reduced lung compliance. In the late phase, monocrotaline pyrrole injection resulted in limited lung fibrosis and no obvious pulmonary hypertension. CONCLUSIONS: Monocrotaline and monocrotaline pyrrole pneumotoxicity substantially differs between the animal species.

• Effects of cell-penetrating peptides and pegylation on transfection efficiency of polyethylenimine in mouse lungs.

  Authors: Juliane Nguyen, Xiulan Xie, Michael Neu, Rio Dumitrascu, Regina Reul, Johannes Sitterberg, Udo Bakowsky, Ralph Schermuly, Ludger Fink, Thomas Schmehl, Tobias Gessler, Werner Seeger, Thomas Kissel

  The journal of gene medicine. 09/2008;

  BACKGROUND: Cell-penetrating peptides (CPPs) could potentially be used as vectors for intracellular delivery of proteins, peptides and nucleic acids. The present study examined different CPPs, suchBACKGROUND: Cell-penetrating peptides (CPPs) could potentially be used as vectors for intracellular delivery of proteins, peptides and nucleic acids. The present study examined different CPPs, such as TAT-derived and arginine rich sequences, as well as model amphiphilic peptide, with respect to transfection efficiency of pegylated polyethylenimine (PEI) in A549, Calu-3 cells and in mice after intra-tracheal administration. METHODS: The conjugates were prepared by the coupling of CPPs to PEI via a heterobifunctional polyethylene glycol (PEG) linker, resulting in the bioconjugates CPP-PEG-PEI. Structures were successfully confirmed by (1)H-nuclear magnetic resonance and diffusion-ordered spectroscopy. Unmodified PEI 25 kDa was compared with pegylated PEI, and aggregation tendency in cell culture medium, interaction with mucin and stability against heparin was assayed. After evaluating transfection efficiency of the polymers in two different lung cell lines, luciferase reporter gene expression was determined in mouse lungs. RESULTS: All conjugates showed superior transfection efficiency compared to unmodified PEI 25 kDa. The conjugates sizes were generally < 300 nm, thus enabling them to penetrate through the mucus lining of the lung and reach the target cells. Coupling of CPPs to PEG-PEI, however, did not significantly improve transfection efficiency in A549 cells, calu-3 cells and in mouse lungs. CONCLUSIONS: We show that small and stable polyplex size achieved by pegylation is favourable for successful pulmonary gene delivery. Compared to PEI 25 kDa, pegylated PEI and CPP-PEG-PEI displayed enhanced transfection efficiency both in vitro and in vivo. Copyright (c) 2008 John Wiley & Sons, Ltd.

• Dysregulated bone morphogenetic protein signaling in monocrotaline-induced pulmonary arterial hypertension.

  Authors: Rory E Morty, Bozena Nejman, Grazyna Kwapiszewska, Matthias Hecker, Anka Zakrzewicz, Fotini M Kouri, Dorothea M Peters, Rio Dumitrascu, Werner Seeger, Petra Knaus, Ralph T Schermuly, Oliver Eickelberg

  Arteriosclerosis, thrombosis, and vascular biology. 06/2007; 27(5):1072-8.

  BACKGROUND: Mutations in the bmpr2 gene, encoding the type II bone morphogenetic protein (BMP) receptor, have been identified in patients with pulmonary arterial hypertension (PAH), implicating BMPBACKGROUND: Mutations in the bmpr2 gene, encoding the type II bone morphogenetic protein (BMP) receptor, have been identified in patients with pulmonary arterial hypertension (PAH), implicating BMP signaling in PAH. The aim of this study was to assess BMP signaling and its physiological effects in a monocrotaline (MCT) model of PAH. METHODS AND RESULTS: Expression of BMP receptors Ib and II, and Smads 4, 5, 6, and 8, was downregulated in lungs but not kidneys of MCT-treated rats. Smad1 phosphorylation and expression of BMP/Smad target genes id1 and id3 was also reduced, although ERK1/2 and p38(MAPK) phosphorylation remained unaffected. BMP receptor and Smad expression, Smad1 phosphorylation, and induction of the BMP/Smad-responsive element of the id1 promoter were reduced in pulmonary artery smooth muscle cells (PASMCs) from MCT-treated rats. As a consequence of impaired BMP/Smad signaling, PASMCs from MCT-treated rats were resistant to apoptosis induced by BMP-4 and BMP-7, and were also resistant to BMP-4 antagonism of proliferation induced by platelet-derived growth factor. CONCLUSION: BMP signaling and BMP-regulated physiological phenomena are perturbed in MCT-treated rats, lending solid support to the proposed roles for BMP signaling in the pathogenesis of human PAH.

• Phosphodiesterase 1 upregulation in pulmonary arterial hypertension: target for reverse-remodeling therapy.

  Authors: Ralph Theo Schermuly, Soni Savai Pullamsetti, Grazyna Kwapiszewska, Rio Dumitrascu, Xia Tian, Norbert Weissmann, Hossein Ardeschir Ghofrani, Christina Kaulen, Torsten Dunkern, Christian Schudt, Robert Voswinckel, Jiang Zhou, Arun Samidurai, Walter Klepetko, Renate Paddenberg, Wolfgang Kummer, Werner Seeger, Friedrich Grimminger

  Circulation. 06/2007; 115(17):2331-9.

  BACKGROUND: Pulmonary arterial hypertension (PAH) is a life-threatening disease, characterized by vascular smooth muscle cell hyperproliferation. The calcium/calmodulin-dependent phosphodiesterase 1BACKGROUND: Pulmonary arterial hypertension (PAH) is a life-threatening disease, characterized by vascular smooth muscle cell hyperproliferation. The calcium/calmodulin-dependent phosphodiesterase 1 (PDE1) may play a major role in vascular smooth muscle cell proliferation. METHODS AND RESULTS: We investigated the expression of PDE1 in explanted lungs from idiopathic PAH patients and animal models of PAH and undertook therapeutic intervention studies in the animal models. Strong upregulation of PDE1C in pulmonary arterial vessels in the idiopathic PAH lungs compared with healthy donor lungs was noted on the mRNA level by laser-assisted vessel microdissection and on the protein level by immunohistochemistry. In chronically hypoxic mouse lungs and lungs from monocrotaline-injected rats, PDE1A upregulation was detected in the structurally remodeled arterial muscular layer. Long-term infusion of the PDE1 inhibitor 8-methoxymethyl 3-isobutyl-1-methylxanthine in hypoxic mice and monocrotaline-injected rats with fully established pulmonary hypertension reversed the pulmonary artery pressure elevation, structural remodeling of the lung vasculature (nonmuscularized versus partially muscularized versus fully muscularized small pulmonary arteries), and right heart hypertrophy. CONCLUSIONS: Strong upregulation of the PDE1 family in pulmonary artery smooth muscle cells is noted in human idiopathic PAH lungs and lungs from animal models of PAH. Inhibition of PDE1 reverses structural lung vascular remodeling and right heart hypertrophy in 2 animal models. The PDE1 family may thus offer a new target for therapeutic intervention in pulmonary hypertension.

• Classical transient receptor potential channel 6 (TRPC6) is essential for hypoxic pulmonary vasoconstriction and alveolar gas exchange.

  Authors: Norbert Weissmann, Alexander Dietrich, Beate Fuchs, Hermann Kalwa, Mahmut Ay, Rio Dumitrascu, Andrea Olschewski, Ursula Storch, Michael Mederos y Schnitzler, Hossein Ardeschir Ghofrani, Ralph Theo Schermuly, Olaf Pinkenburg, Werner Seeger, Friedrich Grimminger, Thomas Gudermann

  Proceedings of the National Academy of Sciences of the United States of America. 01/2007; 103(50):19093-8.

  Regional alveolar hypoxia causes local vasoconstriction in the lung, shifting blood flow from hypoxic to normoxic areas, thereby maintaining gas exchange. This mechanism is known as hypoxic pulmonaryRegional alveolar hypoxia causes local vasoconstriction in the lung, shifting blood flow from hypoxic to normoxic areas, thereby maintaining gas exchange. This mechanism is known as hypoxic pulmonary vasoconstriction (HPV). Disturbances in HPV can cause life-threatening hypoxemia whereas chronic hypoxia triggers lung vascular remodeling and pulmonary hypertension. The signaling cascade of this vitally important mechanism is still unresolved. Using transient receptor potential channel 6 (TRPC6)-deficient mice, we show that this channel is a key regulator of acute HPV as this regulatory mechanism was absent in TRPC6(-/-) mice whereas the pulmonary vasoconstrictor response to the thromboxane mimetic U46619 was unchanged. Accordingly, induction of regional hypoventilation resulted in severe arterial hypoxemia in TRPC6(-/-) but not in WT mice. This effect was mirrored by a lack of hypoxia-induced cation influx and currents in smooth-muscle cells from precapillary pulmonary arteries (PASMC) of TRPC6(-/-) mice. In both WT and TRPC6(-/-) PASMC hypoxia caused diacylglycerol (DAG) accumulation. DAG seems to exert its action via TRPC6, as DAG kinase inhibition provoked a cation influx only in WT but not in TRPC6(-/-) PASMC. Notably, chronic hypoxia-induced pulmonary hypertension was independent of TRPC6 activity. We conclude that TRPC6 plays a unique and indispensable role in acute hypoxic pulmonary vasoconstriction. Manipulation of TRPC6 function may thus offer a therapeutic strategy for the control of pulmonary hemodynamics and gas exchange.

• Activation of soluble guanylate cyclase reverses experimental pulmonary hypertension and vascular remodeling.

  Authors: Rio Dumitrascu, Norbert Weissmann, Hossein Ardeschir Ghofrani, Eva Dony, Knut Beuerlein, Harald Schmidt, Johannes-Peter Stasch, Mark Jean Gnoth, Werner Seeger, Friedrich Grimminger, Ralph Theo Schermuly

  Circulation. 02/2006; 113(2):286-95.

  BACKGROUND: Severe pulmonary hypertension is a disabling disease with high mortality, characterized by pulmonary vascular remodeling and right heart hypertrophy. Using wild-type and homozygousBACKGROUND: Severe pulmonary hypertension is a disabling disease with high mortality, characterized by pulmonary vascular remodeling and right heart hypertrophy. Using wild-type and homozygous endothelial nitric oxide synthase (NOS3(-/-)) knockout mice with pulmonary hypertension induced by chronic hypoxia and rats with monocrotaline-induced pulmonary hypertension, we examined whether the soluble guanylate cyclase (sGC) stimulator Bay41-2272 or the sGC activator Bay58-2667 could reverse pulmonary vascular remodeling. METHODS AND RESULTS: Both Bay41-2272 and Bay58-2667 dose-dependently inhibited the pressor response of acute hypoxia in the isolated perfused lung system. When wild-type (NOS3(+/+)) or NOS3(-/-) mice were housed under 10% oxygen conditions for 21 or 35 days, both strains developed pulmonary hypertension, right heart hypertrophy, and pulmonary vascular remodeling, demonstrated by an increase in fully muscularized peripheral pulmonary arteries. Treatment of wild-type mice with the activator of sGC, Bay58-2667 (10 mg/kg per day), or the stimulator of sGC, Bay41-2272 (10 mg/kg per day), after full establishment of pulmonary hypertension from day 21 to day 35 significantly reduced pulmonary hypertension, right ventricular hypertrophy, and structural remodeling of the lung vasculature. In contrast, only minor efficacy of chronic sGC activator therapies was noted in NOS3(-/-) mice. In monocrotaline-injected rats with established severe pulmonary hypertension, both compounds significantly reversed hemodynamic and structural changes. CONCLUSIONS: Activation of sGC reverses hemodynamic and structural changes associated with monocrotaline- and chronic hypoxia-induced experimental pulmonary hypertension. This effect is partially dependent on endogenous nitric oxide generated by NOS3.

• Inhaled iloprost reverses vascular remodeling in chronic experimental pulmonary hypertension.

  Authors: Ralph Theo Schermuly, Hüseyin Yilmaz, Hossein Ardeschir Ghofrani, Kathrin Woyda, Soni Pullamsetti, Andreas Schulz, Tobias Gessler, Rio Dumitrascu, Norbert Weissmann, Friedrich Grimminger, Werner Seeger

  American journal of respiratory and critical care medicine. 09/2005; 172(3):358-63.

  RATIONALE: Inhaled iloprost is an effective therapy for pulmonary arterial hypertension (PAH). However, no study to date has addressed the effects of inhaled iloprost on changes to pulmonary vascularRATIONALE: Inhaled iloprost is an effective therapy for pulmonary arterial hypertension (PAH). However, no study to date has addressed the effects of inhaled iloprost on changes to pulmonary vascular structure that occur in PAH. OBJECTIVES: The present study was designed to investigate chronic antiremodeling effects of inhaled iloprost in monocrotaline (MCT)-induced PAH in rats. Methods: Four weeks after a single injection of MCT, after full establishment of PAH, rats were nebulized with iloprost at a dose of 6 microg . kg(-1) . day(-1), or underwent sham nebulization with saline. RESULTS: After 2 weeks of inhalation therapy, right ventricular pressure and pulmonary vascular resistance were reversed in rats treated with iloprost, but not in sham-treated control animals. Systemic arterial pressure was unaffected. In addition, right heart hypertrophy, the degree of pulmonary artery muscularization, and the medial wall thickness of intraacinar pulmonary arteries regressed in response to iloprost. Furthermore, the MCT-induced increase in matrix metalloproteinase-2 and -9 activities and tenascin-C expression was suppressed. CONCLUSIONS: We conclude that the inhalation of iloprost reverses PAH and vascular structural remodeling in MCT-treated rats. This regimen suggests the possibility of an antiremodeling therapy in PAH.

• Activation of soluble guanylate cyclase reverses pulmonary vascular remodeling induced by hypoxia in mice

  Authors: Rio Dumitrascu, Norbert Weissmann, Hossein Ghofrani, Knut Beuerlein, Harald Schmidt, Johannes-Peter Stasch, Markus Gnoth, Werner Seeger, Friedrich Grimminger, Ralph Schermuly

  BMC Pharmacology. 01/2005;

• Inactivation of sestrin 2 induces TGF-beta signaling and partially rescues pulmonary emphysema in a mouse model of COPD.

  Authors: Frank Wempe, Silke De-Zolt, Katri Koli, Thorsten Bangsow, Nirmal Parajuli, Rio Dumitrascu, Anja Sterner-Kock, Norbert Weissmann, Jorma Keski-Oja, Harald von Melchner

  Disease models & mechanisms. 3(3-4):246-53.

  Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. Cigarette smoking has been identified as one of the major risk factors and several predisposingChronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality worldwide. Cigarette smoking has been identified as one of the major risk factors and several predisposing genetic factors have been implicated in the pathogenesis of COPD, including a single nucleotide polymorphism (SNP) in the latent transforming growth factor (TGF)-beta binding protein 4 (Ltbp4)-encoding gene. Consistent with this finding, mice with a null mutation of the short splice variant of Ltbp4 (Ltbp4S) develop pulmonary emphysema that is reminiscent of COPD. Here, we report that the mutational inactivation of the antioxidant protein sestrin 2 (sesn2) partially rescues the emphysema phenotype of Ltbp4S mice and is associated with activation of the TGF-beta and mammalian target of rapamycin (mTOR) signal transduction pathways. The results suggest that sesn2 could be clinically relevant to patients with COPD who might benefit from antagonists of sestrin function.