Wall Thickness Of Pulmonary Arteries Research Articles

Cardiopulmonary protective effects of the selective FXR agonist obeticholic acid in the rat model of monocrotaline-induced pulmonary hypertension

Farnesoid X receptor (FXR) activation by obeticholic acid (OCA) has been demonstrated to inhibit inflammation and fibrosis development and even induce fibrosis regression in liver, kidney and intestine in multiple disease models. OCA also inhibits liver fibrosis in nonalcoholic steatohepatitis patients. FXR activation has also been demonstrated to suppress the inflammatory response and to promote lung repair after lung injury.This study investigated the effects of OCA treatment (3, 10 or 30mg/kg, daily for 5days a week, for 7 and/or 28 days) on inflammation, tissue remodeling and fibrosis in the monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) rat model. Treatment with OCA attenuated MCT-induced increased pulmonary arterial wall thickness and right ventricular hypertrophy, by i) blunting pathogenic inflammatory mechanisms (downregulation of interleukin 6, IL-6, and monocyte chemoattractant protein-1, MCP-1) and ii) enhancing protective mechanisms counteracting fibrosis and endothelial/mesenchymal transition. MCT-injected rats also showed a marked decrease of pulmonary artery responsiveness to both endothelium-dependent and independent relaxant stimuli, such as acetylcholine and a nitric oxide donor, sodium nitroprusside. Administration of OCA (30mg/kg) normalized this decreased responsiveness. Accordingly, OCA treatment induced profound beneficial effects on lung histology. In particular, both OCA doses markedly reduced the MCT-induced medial wall thickness increase in small pulmonary arteries. To evaluate the objective functional improvement by OCA treatment of MCT-induced PAH, we performed a treadmill test and measured duration of exercise. MCT significantly reduced, and OCA normalized treadmill endurance. Results with OCA were similar, or even superior, to those obtained with tadalafil, a well-established treatment of PAH.In conclusion, OCA treatment demonstrates cardiopulmonary protective effects, modulating lung vascular remodeling, reducing right ventricular hypertrophy and significantly improving exercise capacity. Thus, OCA can restore the balance between relaxant and contractile pathways in the lung, promoting cardiopulmonary protective actions.

Beneficial effects of aqueous extract of stem bark of Terminalia arjuna (Roxb.), An ayurvedic drug in experimental pulmonary hypertension

Ethnopharmacological relevanceThe stem bark of Terminalia arjuna (Roxb.) is widely used in Ayurveda in various cardiovascular diseases. Many animal and clinical studies have validated its anti-ischemic, antihypertensive, antihypertrophic and antioxidant effects.Pulmonary hypertension (PH) is a fatal disease which causes right ventricular hypertrophy and right heart failure. Pulmonary vascular smooth muscle hypertrophy and increased oxidative stress are major pathological features of PH. As available limited therapeutic options fail to reduce the mortality associated with PH, alternative areas of therapy are worth exploring for potential drugs, which might be beneficial in PH. Aim of the studyThe effect of a standardised aqueous extract of the stem bark of Terminalia arjuna (Roxb.) in preventing monocrotaline (MCT)-induced PH in rat was investigated. Materials and methodsThe study was approved by Institutional Animal Ethics Committe.Male Wistar rats (150–200g) were randomly distributed into five groups; Control, MCT (50mg/kg subcutaneously once), sildenafil (175µg/kg/day three days after MCT for 25 days), and Arjuna extract (TA125 and TA250 mg/kg/day orally after MCT for 25 days). PH was confirmed by right ventricular weight to left ventricular plus septum weight (Fulton index), right ventricular systolic pressure (RVSP), echocardiography, percentage medial wall thickness of pulmonary arteries (%MWT). Oxidative stress in lung was assessed by super oxide dismutase (SOD), catalase, reduced glutathione (GSH) and thiobarbituric acid reactive substance (TBARS). The protein expressions of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX-1) in lung and gene expression of Bcl2 and Bax in heart were analyzed by Western blot and RT PCR respectively. ResultsMCT caused right ventricular hypertrophy (0.58±0.05 vs 0.31±0.05; P<0.001 vs. control) and increase in RVSP (33.5±1.5 vs 22.3±4.7mm of Hg; P<0.001). Both sildenafil and Arjuna prevented hypertrophy and RVSP. Pulmonary artery acceleration time to ejection time ratio in echocardiography was decreased in PH rats (0.49±0.05 vs 0.32±0.06; P<0.001) which was prevented by sildenafil (0.44±0.06; P<0.01) and TA250 (0.45±0.06; P<0.01). % MWT of pulmonary arteries was increased in PH and was prevented by TA250. Increase in TBARS (132.7±18.4 vs 18.8±1.6nmol/mg protein; P<0.001) and decrease in SOD (58.4±14.1 vs 117.4±26.9U/mg protein; P<0.001) and catalase (0.30±0.05 vs 0.75±0.31U/mg protein; P<0.001) were observed in lung tissue of PH rats, which were prevented by sildenafil and both the doses of Arjuna extract. Protein expression of NOX1 was significantly increased in lung and gene expression of Bcl2/Bax ratio was significantly decreased in right ventricle in MCT-induced PH, both were significantly prevented by Arjuna and sildenafil. ConclusionsAqueous extract of Terminalia arjuna prevented MCT-induced pulmonary hypertension which may be attributed to its antioxidant as well as its effects on pulmonary arteriolar wall thickening.

Salvianolic acid A attenuates vascular remodeling in a pulmonary arterial hypertension rat model.

The current therapeutic approaches have a limited effect on the dysregulated pulmonary vascular remodeling, which is characteristic of pulmonary arterial hypertension (PAH). In this study we examined whether salvianolic acid A (SAA) extracted from the traditional Chinese medicine 'Dan Shen' attenuated vascular remodeling in a PAH rat model, and elucidated the underlying mechanisms. PAH was induced in rats by injecting a single dose of monocrotaline (MCT 60 mg/kg, sc). The rats were orally treated with either SAA (0.3, 1, 3 mg·kg(-1)·d(-1)) or a positive control bosentan (30 mg·kg(-1)·d(-1)) for 4 weeks. Echocardiography and hemodynamic measurements were performed on d 28. Then the hearts and lungs were harvested, the organ indices and pulmonary artery wall thickness were calculated, and biochemical and histochemical analysis were conducted. The levels of apoptotic and signaling proteins in the lungs were measured using immunoblotting. Treatment with SAA or bosentan effectively ameliorated MCT-induced pulmonary artery remodeling, pulmonary hemodynamic abnormalities and the subsequent increases of right ventricular systolic pressure (RVSP). Furthermore, the treatments significantly attenuated MCT-induced hypertrophic damage of myocardium, parenchymal injury and collagen deposition in the lungs. Moreover, the treatments attenuated MCT-induced apoptosis and fibrosis in the lungs. The treatments partially restored MCT-induced reductions of bone morphogenetic protein type II receptor (BMPRII) and phosphorylated Smad1/5 in the lungs. SAA ameliorates the pulmonary arterial remodeling in MCT-induced PAH rats most likely via activating the BMPRII-Smad pathway and inhibiting apoptosis. Thus, SAA may have therapeutic potential for the patients at high risk of PAH.

Protective effects of drag-reducing polymers in a rat model of monocrotaline-induced pulmonary hypertension.

Drag-reducing polymers (DRPs) are blood-soluble macromolecules which may increase blood flow and reduce vascular resistance. The purpose of the present study was to observe the effect of DRPs on monocrotaline-induced pulmonary hypertension (PH) in the rat model. A total of 64 male Wistar rats were randomly divided into four groups: GroupI (pulmonary hypertension model+ DRP treatment); GroupII (pulmonary hypertension model + saline treatment); GroupIII (control + DRP treatment); GroupIV (control + saline treatment). After five weeks, comparisons were made of the following indices: survival rate, body weight, blood pressure, right ventricular systolic pressure, right ventricular hypertrophy, wall thickness of pulmonary arteries, the internal diameter of small pulmonary arteries, plasma IL-1β and IL-6. The survival rate after 5 weeks varied significantly across all groups (P=0.013), but the survival rates of Groups I and II were not statistically significantly different. Administration of DRP (intravenous injection twice weekly) attenuated the PH-induced increase in right ventricular systolic pressure and suppressed the increases in right ventricular (RV) weight and the ratio of right ventricular weight to left ventricle plus septum weight (RV/LV + S). DRP treatment also significantly decreased the wall thickness of pulmonary arteries, augmented the internal diameter of small pulmonary arteries, and suppressed increases in the plasma levels of IL-1β and IL-6. DRP treatment with intravenous injection effectively inhibited the development of monocrotaline-induced pulmonary hypertension in the rat model. DRPs may have potential application for the treatment of pulmonary hypertension.

PROGNOSTIC SIGNIFICANCE OF MORPHLOGICAL INVESTIGATION OF PULMONARY TISSUES BIOPSY SAMPLES IN PATIENTS WITH SARCOIDOSIS AND NON-SPECIFIC INTERSTITIAL PNEUMONIA

The number of myofibroblasts, the wall thickness of pulmonary arteries of small caliber, and degree of pulmonary fibrosis by Ashcroft scale were assessed in biopsy samples of pulmonary tissue in patients with sarcoidosis and nonspecific interstitial pneumonia. The data obtained were compared with the efficiency of patient therapy with system glucocorticoids. It was found that resistance to steroid therapy in sarcoidosis patients was determined by increase in the number of myofibroblasts in pulmonary tissue, their appearance within interalveolar septa and wasn’t associated with the expression of pulmonary fibrosis and the level of pulmonary diffusion capacity. Hormonal resistance in non-specific interstitial pneumonia correlated to the thickness of pulmonary arteries of small caliber.

Pioglitazone alleviates cardiac and vascular remodelling and improves survival in monocrotaline induced pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a fatal disease with limited therapeutic options. Pathophysiological changes comprise obliterative vascular remodelling of small pulmonary arteries, elevated mean pulmonary arterial systolic pressure (PASP) due to elevated resistance of pulmonary vasculature, adverse right ventricular remodelling, and heart failure. Recent findings also indicate a role of increased inflammation and insulin resistance underlying the development of PAH. We hypothesized that treatment of this condition with the peroxisome proliferator-activated receptor-γ (PPARγ) activator pioglitazone, known to regulate the expression of different genes addressing insulin resistance, inflammatory changes, and vascular remodelling, could be a beneficial approach. PAH was induced in adult rats by a single subcutaneous injection of monocrotaline (MCT). Pioglitazone was administered for 2weeks starting 3weeks after MCT-injection. At day 35, hemodynamics, organ weights, and -indices were measured. We performed morphological and molecular characterization of the pulmonary vasculature, including analysis of the degree of muscularization, proliferation rates, and medial wall thickness of the small pulmonary arteries. Furthermore, markers of cardiac injury, collagen content, and cardiomyocyte size were analyzed. Survival rates were monitored throughout the experimental period. Pioglitazone treatment improved survival, reduced PASP, muscularization of small pulmonary arteries, and medial wall thickness. Further, MCT-induced right ventricular hypertrophy and fibrosis were attenuated. This was accompanied with reduced cardiac expression of brain natriuretic peptide, as well as decreased cardiomyocyte size. Finally, pulmonary macrophage content and osteopontin gene expression were attenuated. Based on the beneficial impact of pioglitazone, activation of PPARγ might be a promising treatment option in PAH.

TLR4 regulates pulmonary vascular homeostasis and remodeling via redox signaling.

Pulmonary arterial hypertension (PAH) contributes to morbidity and mortality of patients with lung and heart diseases. We demonstrated that hypoxia induced PAH and increased pulmonary arterial wall thickness in wild-type mice. Mice deficient in toll-like receptor 4 (TLR4-/-) spontaneously developed PAH, which was not further enhanced by hypoxia. Echocardiography determined right ventricular hypertrophy and decreased pulmonary arterial acceleration time were associated with the development of PAH in TLR4(-/-) mice. In pulmonary arterial smooth muscle cells (PASMC), hypoxia decreased TLR4 expression and induced reactive oxygen species (ROS) and Nox1/Nox4. Inhibition of NADPH oxidase decreased hypoxia-induced proliferation of wild-type PASMC. PASMC derived from TLR4(-/-) mice exhibited increased ROS and Nox4/Nox1 expression. Our studies demonstrate an important role of TLR4 in maintaining normal pulmonary vasculature and in hypoxia-induced PAH. Inhibition of TLR4, by genetic ablation or hypoxia, increases the expression of Nox1/Nox4 and induces PASMC proliferation and vascular remodeling. These results support a novel function of TLR4 in regulating the development of PAH and reveal a new regulatory axis contributing to TLR4 deficiency-induced vascular hypertrophy and remodeling.

NADPH oxidases-do they play a role in TRPC regulation under hypoxia?

In the lung, acute alveolar hypoxia causes hypoxic pulmonary vasoconstriction (HPV) to maintain ventilation perfusion matching and thus optimal oxygenation of blood. In contrast, global chronic hypoxia triggers a pathological thickening of pulmonary arterial walls, called pulmonary vascular remodelling, leading to persistence of pulmonary hypertension (PH). Moreover, ischaemia or hypoxia can lead to a damage of pulmonary endothelial cells with subsequent oedema formation. Alterations in reactive oxygen species (ROS) have been suggested as a crucial mediator of such responses. Among the various sources of cellular ROS production, NADPH oxidases (NOXs) have been found to contribute to these physiological and pathophysiological signalling processes. NOXs are the only known examples that generate ROS as the primary function of the enzyme system. However, the downstream targets of NOX-derived ROS signalling in hypoxia are still not known. Canonical transient receptor potential (TRPC) channels recently have been recognised as directly or indirectly ROS-activated channels and have been shown to be essential for hypoxia-dependent vascular regulatory processes in the lung. Against this background, we here summarise the current knowledge on NOX-mediated TRPC channel signalling during hypoxia in the pulmonary circulation.

Targeted activation of endothelin-1 exacerbates hypoxia-induced pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a fatal disease that eventually results in right heart failure and death. Current pharmacologic therapies for PAH are limited, and there are no drugs that could completely cure PAH. Enhanced activity of endothelin system has been implicated in PAH severity and endothelin receptor antagonists have been used clinically to treat PAH. However, there is limited experimental evidence on the direct role of enhanced endothelin system activity in PAH. Here, we investigated the correlation between endothelin-1 (ET-1) and PAH using ET-1 transgenic (ETTG) mice. Exposure to chronic hypoxia increased right ventricular pressure and pulmonary arterial wall thickness in ETTG mice compared to those in wild type mice. Of note, ETTG mice exhibited modest but significant increase in right ventricular pressure and vessel wall thickness relative to wild type mice even under normoxic conditions. To induce severe PAH, we administered SU5416, a vascular endothelial growth factor receptor inhibitor, combined with exposure to chronic hypoxia. Treatment with SU5416 modestly aggravated hypoxia-induced pulmonary hypertension, right ventricular hypertrophy, and pulmonary arterial vessel wall thickening in ETTG mice in association with increased interleukin-6 expression in blood vessels. However, there was no sign of obliterative endothelial cell proliferation and plexiform lesion formation in the lungs. These results demonstrated that enhanced endothelin system activity could be a causative factor in the development of PAH and provided rationale for the inhibition of endothelin system to treat PAH.

Antenatal use of bosentan and/or sildenafil attenuates pulmonary features in rats with congenital diaphragmatic hernia.

Lung hypoplasia, pulmonary persistent hypertension of the newborn and its morphological changes are the main features in congenital diaphragmatic hernia (CDH). This study was undertaken to investigate if antenatal use of sildenafil and/or bosentan attenuates vascular remodeling, promotes branching, and improves alveolarization in experimental nitrofeninduced CDH. Nitrofen (100 mg) was gavage-fed to pregnant rats at post conception day (PCD) 9 to induce CDH. The rats were randomized to 5 groups: 1) control; 2) nitrofen; 3) nitrofen+sildenafil 100 mg/kg per day at PCD 16-20; 4) nitrofen+bosentan 30 mg/kg per day, at PCD 16-20, and 5) nitrofen+bosentan+sildenafil, same doses and administration days. After cesarean delivery, the offsprings were sacrificed. The diaphragmatic defect and pulmonary hypoplasia were identified, and the lungs were dissected. Arterial wall thickness, bronchiolar density and alveolarization were assessed. The offsprings with CDH were characterized by severe pulmonary hypoplasia (lung weight-to-body weight ratio: 0.0263 [95% confidence interval (CI) 0.0242-0.0278)] in the nitrofen group versus 0.0385 (95% CI 0.0355-0.0424) in the control group (P=0.0001). Pulmonary arterial wall thickness was decreased to 3.0 (95% CI 2.8-3.7) μm in the nitrofen+sildenafil group versus 5.0 (95% CI 4.1-4.9) μm in the nitrofen group (P=0.02). Terminal bronchioles increased to 13.7 (95% CI 10.7-15.2) μm in the nitrofen+bosentan group in contrast to 8.7 (95% CI 7.2-9.4) μm in the nitrofen group (P=0.002). More significant differences (P=0.0001) were seen in terminal bronchioles in the nitrofen+sildenafil+bosentan group than in the nitrofen group [14.0 (95% CI 12.5-15.4) μm versus 8.5 (95% CI 7.1-9.3) μm]. Pulmonary arterial wall thickness was also decreased in the former group. In this rat model, antenatal treatment with sildenafil attenuates vascular remodeling. Bosentan promotes the development of terminal bronchioles in nitrofen-induced CDH.

Effect of thoracic epidural blockade on hypoxia-induced pulmonary arterial hypertension in rats.

The present study was aimed to investigate the influence of thoracic epidural blockade on hypoxia-induced pulmonary hypertension in rats. Forty eight Wistar rats were randomly divided into 4 equal groups, named normoxia hypoxia hypoxia/ ropivacaine and hypoxia/saline. Animals were placed in a hypoxia chamber and instrumented with epidural catheters at the thoracic level. Rats were injected with saline or ropivacaine. Haemodynamic measurements included pulmonary artery pressure and right ventricular hypertrophy. Degree of pulmonary vascular remodeling was determined by Hematoxylin and Eosin (HE) staining. Serum cyclic GMP (cGMP) and TNF-α were measured using radioimmuno assay. Real-time PCR and western boltting were employed to examine the expression of cAMP responding-element binding protein (CREB). We found that the thoracic epidural blockade significantly decreased chronic hypoxia-induced pulmonary hypertension and vascular remodeling in rats. Ropivacaine-treated rats exhibited significantly lower mean pulmonary artery pressure (mPAP), ratio of right ventricular weight to left ventricular plus septal weight (RV/(LV+S)) and wall thickness of pulmonary artery compared with those of control rats. Hypoxia-induced increase in levels of serum cGMP and TNF-α was reversed by thoracic epidural blockade. Moreover, hypoxia increased expression of CREB at mRNA and protein levels which could be suppressed by thoracic epidural blockade. Thoracic epidural blockade reduced mPAP and serum level of TNF-α and increased cGMP. The treatment reversed upregulated expression of CREB at mRNA and protein production.

Nuclear Factor κB Inhibition Reduces Lung Vascular Lumen Obliteration in Severe Pulmonary Hypertension in Rats

NF-κB and IL-6, a NF-κB downstream mediator, play a central role in the inflammatory response of tissues. We aimed to determine the role of the classical NF-κB pathway in severe pulmonary arterial hypertension (PAH) induced by SU5416 and chronic hypoxia (SuHx) in rats. Tissue samples from patients with idiopathic PAH (iPAH) and control subjects were investigated. SuHx rats were treated from Days 1 to 3, 1 to 21, and 29 to 42 with the NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) and/or from Days 1 to 21 with anti-IL-6 antibody. Nuclear staining for NF-κB, an indicator of the activation of the classical NF-κB pathway, was detected in pulmonary arterial lesions of patients with iPAH and SuHx rats. NF-κB inhibition with PDTC prevented and reduced pulmonary arterial obliteration without reducing muscularization. However, the elevated lung levels of IL-6 were not reduced in PDTC-treated SuHx animals. PDTC treatment prevented or reduced apoptosis of pulmonary artery wall cells and pulmonary arterial obliteration. IL-6 inhibition had only a partial effect on apoptosis and obliteration. Pulmonary arterial media wall thickness was not affected by any of these treatments. Preventive and therapeutic PDTC treatment promoted immune regulation by increasing the number of perivascular CD4(+) T cells, in particular regulatory T cells (early treatment), and by reducing the number of perivascular CD8(+) T lymphocytes and CD45RA(+) B lymphocytes. Therapeutic PDTC treatment further preserved right ventricular function in SuHx animals. Inhibition of NF-κB may represent a therapeutic option for pulmonary arterial obliteration via reduced vessel wall cell apoptosis and improved regulation of the immune system.

Hepatocyte growth factor intervention on rats with pulmonary hypertension and effect of endothelial cell membrane microparticles

To explore the effect of transfection of adenovirus carrying hepatocyte growth factor (HGF) on pulmonary arterial hypertension (PAH) and endothelial cell membrane microparticles (EMP) in a rat model, and the underlying mechanism. Forty healthy male SD rats were randomly divided into four groups, the normal control group (NOR group), monocrotaline (MCT)-induced pulmonary hypertension group (PAH group), HGF treatment of PAH group (HGF group and THGF group) each with 10 rats. NOR group and the PAH Group: intratracheal instillation of 0.2 ml PBS solution; HGF group: intratracheal instillation of 0.2 ml HGF one times; THGF Group: intratracheal instillation of 0.2 ml HGF one times, and then 1 week repeat again. Different interventions after 2 weeks, the rats was measured mean pulmonary arterial pressure, right ventricular hypertrophy index calculation, HE staining index of pulmonary arterial wall thickness, area index, plasma levels of endothelial cell microparticles. HGF intratracheal instillation after 2 weeks, HGF and THGF groups of SD rats mPAP, RVHI, TI, AI decreased significantly compared with PAH group (P < 0.05). PAH group was increased in particulate levels at different time points significantly higher levels of horizontal (P < 0.05). The EMP levels in HGF group which at 7 and 14 days after dosing were significantly decreased compared with PAH.It still higher than the NOR group (P < 0.05). And after administration of 7 days, 14 days, the EMP level of HGF group was significantly lower than before administration (P < 0.05). Thought airway instillation transfected HGF, pulmonary artery pressure can reduce greater degree, but can't achieve complete reversal. It can inhibit the pulmonary artery wall thickening and maintain effective lumen area, delaying the right ventricular hypertrophy by reducing the membrane particles within the lung, thereby promoting endothelial cell repair to achieve the goal of intervention in pulmonary hypertension.

Tanshinone IIA sulfonate upregulated pulmonary artery smooth muscle peroxisome proliferator-activated receptor γ expression in monocrotaline induced pulmonary hypertension rat

To investigate the effect of sodium tanshinone IIA sulfonate (STS) on rat right ventricular systolic pressure (RVSP), mean right ventricular pressure (MRVP), right ventricular hypertrophy index [RV/(LV+S)], pulmonary vascular remodeling, and PPARγ protein expression in pulmonary artery smooth muscle of monocrotaline (MCT) induced rat pulmonary hypertension model. The pulmonary hypertension model was established by subcutaneously injection of MCT, and the rats were treated with or without STS for 21 days. After that, RVSP, mRVP and RV/(LV+S) were measured. Lung histopathological sections were prepared, and the lumen area, the wall thickness and arterial radius of pulmonary arteries were quantified using the Image Pro Plus 6.0 software. PPARγ protein expression in rat pulmonary artery smooth muscle was detected by Western blot. Compared with control group, the RVSP, mRVP were significantly increased in MCT group (P < 0.05), while in the MCT+STS group, it was decreased from (81.2 ± 1.9) and (28.6 ± 2.0) mmHg to (35.4 ± 8.3) and (14.1 ± 5.4) mmHg, respectively (P < 0.05). The RV/(LV+S) of MCT group was (0.57 ± 0.04), markedly higher than those of control group and control+STS group (0.33 ± 0.02) and (0.34 ± 0.02) , respectively, P < 0.05, while in MCT+STS group, the RV/(LV+S) was (0.43 ± 0.02), lower than that of MCT group (P < 0.05) ;The luminal area/total area of MCT group decreased to (27 ± 6)%compared with control rats (56.00 ± 3.00) % (P < 0.05) . The wall thickness/artery radius (WT%) of MCT group increased from (20 ± 4) % (control group) to (40 ± 3) % (P < 0.05) .In MCT+STS treated rats, luminal area/ total area and WT% were (39.0 ± 2.0) %and (31.0 ± 2.0) %, both statistically different from MCT group (P < 0.05) . The level of PPARγ protein in pulmonary artery smooth muscle of MCT group was (48 ± 4) %, lower than control group (100 ± 0) % (P < 0.05) .In the MCT+STS group, PPARγ protein expression was recovered (102 ± 3) %, (P < 0.05) . STS markedly decreased RVSP,MRVP, RV/(LV+S) and pulmonary vascular remodeling in MCT induced pulmonary hypertension rat, and PPARγ might be targeted as a key molecule during STS treatment.

MiR‐17~92 promotes hypoxia‐induced pulmonary hypertension by regulating proliferation and contraction of pulmonary arterial smooth muscle cells (LB779)

Introduction: Recent studies suggest that microRNAs (miRNAs) play important roles in development and pathogenesis of human diseases. We sought to identify novel miRNAs that may be involved in the pathogenesis of pulmonary arterial hypertension (PAH) and to investigate underlying mechanisms.Methods and Results: We performed miRNA qPCR array using pulmonary arterial smooth muscle cells (PASMC) isolated from lungs of normal donor and PAH patients. We found that all of the six members of the miR‐17~92 cluster were down‐regulated in PAH PASMCs. In hypoxia‐induced PAH mouse model and cultured human PASMCs, we found that short term hypoxia induced miR‐17~92 whereas prolonged hypoxia suppressed miR‐17~92. We generated a strain of SMC‐specific miR‐17~92 knockout (sm‐17~92‐/‐) mouse by crossbreeding miR‐17~92 fl/fl mice with sm22α‐Cre mice and subsequent backcrossing. We exposed 8‐10 week old sm‐17~92‐/‐ mice along with their wild type littermates to hypoxia (10% O2) or normoxia for five weeks. We showed that knockout of miR‐17~92 in SMC attenuated hypoxia‐induced increase in measured their right ventricular systolic pressure (RVSP), RV hypertrophy (RV/(LV+S) ratio), and pulmonary arterial wall thickness, suggesting that SMC‐specific miR‐17~92 is essential for the development of PAH. To investigate the underlying mechanism, we over‐expressed the miR‐17~92 cluster in human PASMC by a lenti‐virus encoding this miRNA cluster. Overexpression of mi‐17~92 induced expression levels of SMA, SM22α, Calponin, and PCNA and BrdU incorporation. Human PASMC from idiopathic PAH (IPAH) patients expressed decreased levels of SMA, SM22α, and Calponin, whereas over‐expression of miR‐17~92 restored the expression of SMA, SM22α, and Calponin in PASMCs from IPAH patient.Summary: We provide evidence that miR‐17~92 is dysregulated in hypertensive PASMC and suppression miR‐17~92 in SMC is sufficient to inhibit hypoxia‐induced PAH in vivo. We also show that miR‐17~92 induces PASMC proliferation and expression of contractile proteins. These results suggest that miR‐17~92 may promote PAH by regulating vascular remodeling and that miR‐17~92 may represent a novel therapeutic target for the treatment of PAH. Support: NIH HL110829 and Gilead Sciences Research Scholars Program.Grant Funding Source: Support by NIH HL110829 and Gilead Sciences Research Scholars Program.

P20 VALUE OF SERUM PRO-BRAIN NATURETIC PEPTIDE (pro-BNP) IN DETECTION OF CARDIAC DYSFUNCTION IN CIRRHOTIC CHILDREN

Background and Aims: Cirrhotic cardiomyopathy designates cardiac dysfunction in cirrhotics in absence of other causes of cardiac disease. Pro-Brain natriuretic peptide (pro-BNP) is a cardiac neurohormone released under increased ventricular wall tension. Serum pro-BNP correlates with cardiac disease severity. We aimed to study the changes in serum pro-BNP in cirrhotic children and correlate them with the clinical, echocardiographic and laboratory findings. Methods: We prospectively enrolled 52 biopsy-proven cirrhotic children (27 males) aged 18–180 months (mean 91.9m±49.9) and 53 matched healthy controls. All cases had full physical and laboratory evaluation. Serum pro-BNP was measured using quantitative ELISA (WKEA MED SUPPLIES CORP; New York, NY, USA). Conventional echocardiographic, Doppler and tissue Doppler imaging (TDI) were performed using Siemens Acuson S3000 (Siemens Healthcare Diagnostics, Newark, DE, USA). Results: Serun pro-BNP levels were significantly higher in patients compared to controls (5.25ng/l versus 4ng/l, p value <0.04). Cirrhotic children had significantly increased diameter of left atrium, right ventricle, pulmonary artery and posterior wall thickness (p < 0.01, 0.02, 0.04 and 0.04 respectively). Early and late diastolic myocardial velocities (E/A) of both mitral and tricuspid valves inflow were significantly lower in cirrhotics (p < 0.005 and <0.0008). TDI revealed significantly higher IVRT and lower IVCT of mitral valve inflow (p < 0.008 and <0.03) in cirrhotic children. In cirrhotics, the only echocardiographic parameter that was significantly correlated with the pro-BNP level was the E wave velocity on tricuspid valve (p < 0.004). Conclusions: Cirrhotic children might develop hepatic cardiomyopathy. Pro-BNP is a useful and specific marker of cardiac dysfunction in cirrhotic children.

Telmisartan Protect Broiler Chickens from Pulmonary Arterial Remodeling Induced by Low Ambient Temperature

Objective: Renin-angiotensin system is associated with many vascular diseases. This study aims to explore the protective effect of telmisartan, Angiotensin type 1 receptor blocker, on pulmonary arterial remodeling induced by low ambient temperature in broiler chickens. Methods: Ninety chickens were randomly divided into 3 groups (n=30), including control group, low temperature group and telmisartan group. Chickens in low temperature group and telmisartan group were exposed to low ambient temperature from 14 days of age until 45 days of age; chickens in telmisartan group were gavaged with telmisartan 5 mg/kg once daily for thirty days. The pulmonary arterial systolic pressure was measured with right catheterization method. Wet lung weight index and right ventricular hypertrophy index were evaluated. Small pulmonary artery wall thickness and elastic fibers was determined respectively by H-E staining and Weight staining. Proliferating Cell Nuclear Antigen (PCNA)-positive cells were determined by Immunohistochemical staining. Results: It showed that pulmonary arterial systolic pressure, wet lung weight index and right ventricular hypertrophy index, small pulmonary artery wall thickness, elastic fibers and PCNA expression increased significantly in Low temperature group compared with control group and telmisartan group. Conclusion: Telmisartan can protect broiler chickens from pulmonary arterial remodeling induced by low ambient temperature

Abstract 9814: Nf-?B Inhibition Prevents Vascular Obliteration and Improves Immune Regulation in Severe Pulmonary Arterial Hypertension

Nuclear factor-κB (NF-κB) and interleukin-6 (IL-6), a NF-κB downstream mediator, play a central role in inflammatory response and vascular cell growth. Inflammation and a dysregulated immune response are found in many forms of severe pulmonary arterial hypertension (PAH), but how the NF-κB pathway contributes to PAH development is unclear. The SU5416 and chronic hypoxia (Su/Hx) rat PAH model is, like severe human PAH, characterized by obliterative pulmonary vascular lesions and right ventricular failure. We hypothesized that activation of the classical NF-κB pathway in severe PAH promotes ongoing vascular lesion cell apoptosis and proliferation, as well as dysregulation of the immune system. We aimed to determine the role of NF-κB in severe PAH induced by Su/Hx in rats. PAH was induced by a single injection of SU5416 and exposure to chronic hypoxia. Su/Hx rats were treated from day 1-21 with the NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC) and/or anti-IL-6 antibody. After hemodynamic assessment at day 21, cytokine/chemokine expression, NF-κB activation, lymphocyte accumulation, as well as pulmonary arterial cell apoptosis and proliferation were evaluated by Western blot, Flow cytometry and immunohistochemistry. The classical NF-κB pathway was activated in pulmonary arterial lesions SuHx rats. NF-κB inhibition with PDTC prevented the development of pulmonary arterial obliteration and in part PAH without reducing muscularization. However, the elevated lung levels of IL-6 were not reduced in PDTC-treated SuHx animals. Apoptosis of pulmonary artery wall cells and pulmonary arterial obliteration was prevented by PDTC or by PDTC+IL-6 inhibition and partially by IL-6 inhibition alone. Pulmonary arterial media wall thickness was not affected by any of these treatments. In Su/Hx rats, CD4 + T cells were reduced and perivascular CD8 + T lymphocytes and CD45RA + B lymphocytes were increased. NF-κB inhibition promoted immune regulation by increasing the number of perivascular CD4 + T cells and reducing the number of perivascular CD8 + T lymphocytes and CD45RA + B lymphocytes. Inhibition of NF-κB may represent a therapeutic option for pulmonary arterial obliteration via reduced vessel wall cell apoptosis and improved immune regulation.

Pulmonary Hypertension in Mitral Stenosis: An Optical Coherence Tomography Study

A 65-year old woman with a prior history of surgical mitral comissurotomy 30 years ago presented with a 6-month history of worsening fatigue and exertional dyspnea. On physical examination, she had a mitral stenosis murmur, a loud P2, with an irregular pulse and mild peripheral edema. The electrocardiogram showed atrial fibrillation; the echocardiogram was notable for a fibro-calcified mitral valve, with severe restriction of leaflet mobility and an area of 1.1 cm. Biventricular function was normal. As the valve anatomy was considered suitable for percutaneous intervention, the patient was scheduled a balloon valvuloplasty. The pre-intervention right heart catheterization showed a pulmonary artery pressure of 45/17/29 mmHg. After successful mitral dilatation, optical coherence tomography (LightLab Imaging Inc., Westford, Massachusetts, United States) was performed on a distal segmental branch of the right pulmonary artery (Fig. 1). Optical coherence tomography images showed diffuse thickening of the distal pulmonary arterial wall (Figs. 2 and 3). We registered a pulmonary artery wall thickness between 0.28 mm and 0.31 mm, higher when compared to reports from subjects without pulmonary hypertension (0.16 [0.03] mm for vessels with 2.14 [0.33] mm of diameter). No complications arose during or after the procedure. Optical coherence tomography is a safe and potentially useful tool for characterize, with high resolution, the pulmonary vessels and may contribute to investigate the mechanisms of vascular remodeling in pulmonary hypertension.

The Potential Efficacy of R8-Modified Paclitaxel-Loaded Liposomes on Pulmonary Arterial Hypertension

In this paper, a novel liposomal formulation of paclitaxel modified with octaarginine (R8) was fabricated and the therapeutic efficacy of it on pulmonary arterial hypertension was evaluated. Octaarginine-modified stealth liposomes loaded with PTX (R8-PTX-LIP) were prepared and characterized. Vector cytoxicity and anti-proliferation ability of different formulations on primary cultured VSMCs were determined with MTT assay. The uptake capacity of VSMCs on different formulations were evaluated by flow cytometry, and the influences on cytoskeletons of liposomes were investigated by cytoskeleton staining with rhodamine-phalloidin. The biodistribution of liposomes were imaged by a CCD camera using a near-infrared fluorophore DiD. The therapeutic efficacy of different PTX-formulations of PAH was evaluated by hemodynamic measurement, right ventricular hypertrophic parameters and vessel diameters. The cellular uptake of R8 modified liposomes (R8-LIP) was improved noticeably compared with other groups. All liposomes did not exert cytotoxicity on VSMCs in 24 h. R8-PTX-LIP exhibited the strongest inhibitory effect on the proliferation of VSMCs among all the formulations (p < 0.001). R8-PTX-LIP could reverse the phenotype transformation, and inhibit cell migration. mPAP, (RV/LV+S) and the wall thickness of small distal pulmonary arteries of rats treated with R8-PTX-LIP were significantly lower than those from other groups (p < 0.001). In conclusion, the drug delivery system of R8-modified paclitaxel-loaded liposomes we established showed pronounced inhibitory effect over VSMCs proliferation and cytoskeleton formation in vitro, a stronger pulmonary delivery ability in vivo, and was effective on PAH, showing the potential for pulmonary drug delivery system for PAH treatment.