Satoshi Akagi

Pro-apoptotic effects of imatinib on PDGF-stimulated pulmonary artery smooth muscle cells from patients with idiopathic pulmonary arterial hypertension☆

BACKGROUND Remodeling of the pulmonary artery by an inappropriate increase of pulmonary artery smooth muscle cells (PASMCs) is problematic in the treatment of idiopathic pulmonary arterial hypertension (IPAH). Effective treatment that achieves reverse remodeling is required. The aim of this study was to assess the pro-apoptotic effects of imatinib, a platelet-derived growth factor (PDGF)-receptor tyrosine kinase inhibitor, on PASMCs obtained from patients with IPAH. METHODS PASMCs were obtained from 8 patients with IPAH undergoing lung transplantation. Cellular proliferation was assessed by (3)H-thymidine incorporation. Pro-apoptotic effects of imatinib were examined using TUNEL and caspase-3,7 assays and using transmission electron microscopy. RESULTS Treatment with imatinib (0.1 to 10 μg/mL) significantly inhibited PDGF-BB (10 ng/mL)-induced proliferation of PASMCs from IPAH patients. Imatinib (1 μg/mL) did not induce apoptosis in quiescent IPAH-PASMCs, but it had a pro-apoptotic effect on IPAH-PASMCs stimulated with PDGF-BB. Imatinib did not induce apoptosis in normal control PASMCs with or without PDGF-BB stimulation. PDGF-BB induced phosphorylation of Akt at 15 min, and Akt phosphorylation was inhibited by imatinib in IPAH-PASMCs. Akt-I-1/2 (1 μmol/L), an Akt inhibitor, in the presence of PDGF-BB significantly increased apoptotic cells compared with the control condition. Thus, Akt-I-1/2 could mimic the effects of imatinib on PASMCs. CONCLUSION Imatinib has anti-proliferative and pro-apoptotic effects on IPAH-PASMCs stimulated with PDGF. The inhibitory effect of imatinib on Akt phosphorylation induced by PDGF plays an important role in the pro-apoptotic effect.

Intravenous administration of nicorandil immediately before percutaneous coronary intervention can prevent slow coronary flow phenomenon

AIMS To determine the effect of intravenous administration of nicorandil on slow coronary flow (SCF) phenomenon in patients undergoing percutaneous coronary intervention (PCI). METHODS AND RESULTS In a preliminary study, 6 mg of nicorandil showed optimal efficacy for vasodilatation without causing significant haemodynamic instability. In the main study, a total of 408 patients were randomly assigned to receive intravenous administration of 6 mg of nicorandil immediately before PCI. The number of patients in the nicorandil group was 206 [acute coronary syndrome (ACS): 47, non-ACS: 159] and that in the control group was 202 (ACS: 61, non-ACS: 141). Nicorandil significantly decreased the incidence of post-procedural SCF phenomenon in both the ACS and non-ACS groups. The rate of target vessel revascularization (TVR) was significantly lower in the nicorandil group than in the control group in ACS patients. CONCLUSION Our simple procedure prevented SCF phenomenon not only in patients with ACS but also in patients with non-ACS without any adverse effect. Additionally our procedure reduced the rate of TVR in patients with ACS.

Inhibitory Effects of Simvastatin on Platelet-derived Growth Factor Signaling in Pulmonary Artery Smooth Muscle Cells From Patients With Idiopathic Pulmonary Arterial Hypertension

Idiopathic pulmonary arterial hypertension (IPAH) is a progressive disease characterized by inappropriate increase of pulmonary artery smooth muscle cells (PASMCs) leading to occlusion of pulmonary arterioles. Inhibition of platelet-derived growth factor (PDGF) signaling is starting to garner attention as a targeted therapy for IPAH. We assessed the inhibitory effects of simvastatin, a 3-hydroxy-3-methylglutanyl coenzyme A reductase inhibitor, on PDGF-induced proliferation and migration of PASMCs obtained from 6 patients with IPAH who underwent lung transplantation. PDGF stimulation caused a significantly higher growth rate of PASMCs from patients with IPAH than that of normal control PASMCs as assessed by 3H-thymidine incorporation. Simvastatin (0.1 μmol/L) significantly inhibited PDGF-induced cell proliferation of PASMCs from patients with IPAH but did not inhibit proliferation of normal control cells at the same concentration. Western blot analysis revealed that simvastatin significantly increased the expression of cell cycle inhibitor p27. PDGF significantly increased the migration distance of IPAH-PASMCs compared with that of normal PASMCs, and simvastatin (1 μmol/L) significantly inhibited PDGF-induced migration. Immunofluorescence staining revealed that simvastatin (1 μmol/L) inhibited translocation of Rho A from the cytoplasm to membrane and disorganized actin fibers in PASMCs from patients with IPAH. In conclusion, simvastatin had inhibitory effects on inappropriate PDGF signaling in PASMCs from patients with IPAH.

Three-Dimensional Structure of Pulmonary Capillary Vessels in Patients With Pulmonary Hypertension

Pulmonary arterial hypertension, pulmonary veno-occlusive disease, and pulmonary capillary hemangiomatosis are included in the same group (group 1) of clinical classification of pulmonary hypertension.1 Histological changes in the small pulmonary arteries (ie, intimal fibrosis and medial hypertrophy) are similar in these 3 diseases, and clinical presentations of the 3 diseases are often indistinguishable.1 However, it is estimated that the hemodynamics of capillary vessels are quite different in each disease. The hemodynamics of capillary vessels (ie, capillary occlusion) play an important role in cardiovascular diseases.2 Thus, clarification of the differences in the hemodynamics is essential to understand the pathophysiology of these 3 diseases. We obtained lung segments from patients with pulmonary hypertension who underwent living-donor lung transplantation and from patients with …

epoprostenol sodium for treatment of pulmonary arterial hypertension

The release of endogenous prostacyclin (PGI2) is depressed in patients with pulmonary arterial hypertension (PAH). PGI2 replacement therapy by epoprostenol infusion is one of the best treatments available for PAH. Here, we provide an overview of the current clinical data for epoprostenol. Epoprostenol treatment improves symptoms, exercise capacity, and hemodynamics, and is the only treatment that has been shown to reduce mortality in patients with idiopathic PAH (IPAH) in randomized clinical trials. We have reported that high-dose epoprostenol therapy (>40 ng/kg/min) also results in marked hemodynamic improvement in some patients with IPAH. High-dose epoprostenol has a pro-apoptotic effect on PAH-PASMCs via the IP receptor and upregulation of Fas ligand (FasL) in vitro. However, long-term intravenous administration of epoprostenol is sometimes associated with catheter-related infections and leads to considerable inconvenience for the patient. In the future, the development of new routes of administration or the development of powerful PGI2 analogs, IP-receptor agonists, and gene and cell-based therapy enhancing PGI2 production with new routes of administration is required.

Different sizes of centrilobular ground-glass opacities in chest high-resolution computed tomography of patients with pulmonary veno-occlusive disease and patients with pulmonary capillary hemangiomatosis

BACKGROUND Centrilobular ground-glass opacity (GGO) is one of the characteristic findings in chest high-resolution computed tomography (HRCT) of patients with pulmonary veno-occlusive disease (PVOD) and patients with pulmonary capillary hemangiomatosis (PCH). However, clinical differential diagnosis of these two diseases is difficult and has not been established. In order to clarify their differences, we compared the sizes of GGOs in chest HRCT and the sizes of capillary assemblies in pulmonary vascular casts between patients diagnosed pathologically with PVOD and PCH. METHODS We evaluated chest HRCT images for four patients with idiopathic pulmonary arterial hypertension (IPAH), three patients with PVOD and three patients with PCH, and we evaluated pulmonary vascular casts of lung tissues obtained from those patients at lung transplantation or autopsy. RESULTS Centrilobular GGOs in chest HRCT were observed in patients with PVOD and patients with PCH but not in patients with IPAH. We measured the longest diameter of the GGOs. The size of centrilobular GGOs was significantly larger in patients with PCH than in patients with PVOD (5.60±1.43 mm versus 2.51±0.79 mm, P<.01). We succeeded in visualization of the 3-dimensional structures of pulmonary capillary vessels obtained from the same patients with PVOD and PCH undergoing lung transplantation or autopsy and measured the diameters of capillary assemblies. The longest diameter of capillary assemblies was also significantly larger in patients with PCH than in patients with PVOD (5.44±1.71 mm versus 3.07±1.07 mm, P<.01). CONCLUSION Measurement of the sizes of centrilobular GGOs in HRCT is a simple and useful method for clinical differential diagnosis of PVOD and PCH.

Prostaglandin I2 induces apoptosis via upregulation of Fas ligand in pulmonary artery smooth muscle cells from patients with idiopathic pulmonary arterial hypertension.

BACKGROUND Pulmonary vascular remodeling with idiopathic pulmonary arterial hypertension (IPAH) is associated with impaired apoptosis of pulmonary artery smooth muscle cells (PASMCs). We have reported that high-dose prostaglandin I2 (PGI2) therapy markedly improved hemodynamics in IPAH patients. The therapy is thought to reverse vascular remodeling, though the mechanism is unclear. The aim of this study is to assess proapoptotic effects of PGI2 on PASMCs obtained from IPAH patients. METHODS We investigated proapoptotic effects of PGI2 in PAH-PASMCs by TUNEL assays, caspase-3,-7 assays and transmission electron microscopy. We examined the expression of Fas ligand (FasL), an apoptosis-inducing member of the TNF cytokine family, in PAH-PASMCs. We measured the serum FasL levels in IPAH patients treated with PGI2. RESULTS TUNEL-positive, caspase-3, 7-active cells and fragmentation of the nucleus were detected in PAH-PASMCs treated with PGI2. The percentage of apoptotic cells induced by PGI2 at a high concentration was higher than that induced by PGI2 at a low concentration. PCR-array analysis revealed that PGI2 upregulated the FasL gene in PAH-PASMCs, and we measured the FasL expression by quantitative RT-PCR and Western blotting. PGI2 significantly increased the mRNA level of FasL by 3.98 fold and the protein level of FasL by 1.70 fold. An IP receptor antagonist inhibited the induction of apoptosis, elevation of cyclic AMP and upregulation of FasL by PGI2. Serum FasL level had a significant positive correlation with PGI2 dose in IPAH patients treated with PGI2. CONCLUSIONS PGI2 has proapoptotic effects on PAH-PASMCs via the IP receptor and upregulation of FasL.

Delivery of Imatinib-Incorporated Nanoparticles into Lungs Suppresses the Development of Monocrotaline-Induced Pulmonary Arterial Hypertension

Platelet-derived growth factor (PDGF) is implicated in the pathogenesis of pulmonary arterial hypertension (PAH). Imatinib, a PDGF-receptor tyrosine kinase inhibitor, improved hemodynamics, but serious side effects and drug discontinuation are common when treating PAH. A drug delivery system using nanoparticles (NPs) enables the reduction of side effects while maintaining the effects of the drug. We examined the efficacy of imatinib-incorporated NPs (Ima-NPs) in a rat model and in human PAH-pulmonary arterial smooth muscle cells (PASMCs). Rats received a single intratracheal administration of PBS, FITC-NPs, or Ima-NPs immediately after monocrotaline injection. Three weeks after monocrotaline injection, intratracheal administration of Ima-NPs suppressed the development of pulmonary hypertension, small pulmonary artery remodeling, and right ventricular hypertrophy in the rat model of monocrotaline-induced PAH. We also examined the effects of imatinib and Ima-NPs on PDGF-induced proliferation of human PAH-PASMCs by (3)H-thymidine incorporation. Imatinib and Ima-NPs significantly inhibited proliferation after 24 hours of treatment. Ima-NPs significantly inhibited proliferation compared with imatinib at 24 hours after removal of these drugs. Delivery of Ima-NPs into lungs suppressed the development of MCT-induced PAH by sustained antiproliferative effects on PAS-MCs.

Intratracheal Administration of Prostacyclin Analogue-incorporated Nanoparticles Ameliorates the Development of Monocrotaline and Sugen-Hypoxia-induced Pulmonary Arterial Hypertension.

Abstract: Nanoparticles (NPs) have been used as novel drug delivery systems. Drug-incorporated NPs for local delivery might optimize the efficacy and minimize the side effects of drugs. Intravenous prostacyclin improves long-term survival in patients with pulmonary arterial hypertension (PAH), but it causes serious side effects such as catheter-related infections. We investigated the efficacy and safety of intratracheal administration of a prostacyclin analogue, beraprost (BPS), incorporated NPs in Sugen-hypoxia-normoxia and monocrotaline rat models of PAH and in human PAH pulmonary arterial smooth muscle cells (PASMCs). After a single administration, BPS NPs significantly decreased right ventricular pressure, right ventricular hypertrophy, and pulmonary artery muscularization in the 2 rat models. BPS NPs significantly improved the survival rate in the monocrotaline rat model. No infiltration of inflammatory cells, hemorrhage, or fibrosis was found in the liver, kidney, spleen, and heart after the administration of BPS NPs. No liver or kidney dysfunction was found in the blood examinations. BPS and BPS NPs significantly inhibited the proliferation of human PAH PASMCs after 24 hours of treatment. BPS NPs significantly continued to inhibit the proliferation of human PAH PASMCs at 24 hours after the removal of BPS NPs. BPS NPs significantly induced apoptosis in PAH PASMCs compared to that in non-PAH PASMCs. Intratracheal administration of BPS NPs ameliorates pulmonary hypertension in PAH rat models by a sustained antiproliferative effect and a proapoptotic effect on PAH PASMCs.

Reverse Right Ventricular Remodeling After Lung Transplantation in Patients With Pulmonary Arterial Hypertension Under Combination Therapy of Targeted Medical Drugs

BACKGROUND Patients with pulmonary arterial hypertension (PAH) are currently treated with combination therapy of PAH-targeted drugs. Reverse right ventricular (RV) remodeling after lung transplantation (LTx) in patients with end-stage PAH despite combination therapy of PAH-targeted drugs has not been fully elucidated.Methods and Results:A total of 136 patients, including 32 with PAH, underwent LTx from 1998 to 2014. We enrolled 12 consecutive patients with PAH treated with combination therapy of PAH-targeted drugs who underwent LTx and retrospectively analyzed the temporal and serial changes in hemodynamics and echocardiography before LTx and at 3 and 12 months after LTx. Before LTx, the RV was markedly dilated with substantially reduced RV fractional area change (RVFAC). At 3 months after LTx, pulmonary artery pressure, pulmonary vascular resistance and RV stroke work index were significantly decreased, while left ventricular stroke work index was increased. RV size assessed by echocardiography also significantly decreased and RVFAC improved. At 12 months after LTx, RVFAC was further increased and RV wall thickness was decreased significantly. CONCLUSIONS Although severe RV dysfunction and dilation were observed in patients with end-stage PAH despite combination therapy of PAH-targeted drugs, RV function and morphology were improved after reduction of RV pressure load by LTx.