Change in pharmacological effect of endothelin receptor antagonists in rats with pulmonary hypertension: Role of ETB-receptor expression levels

Background and purposeThe endothelin (ET) system is activated in pulmonary arterial hypertension (PAH). The therapeutic value of pharmacological blockade of ET receptors has been demonstrated in various animal models and led to the current approval and continued development of these drugs for the therapy of human PAH. However, we currently incompletely comprehend what local modifications of this system occur as a consequence of PAH, particularly in small resistance arteries, and how this could affect the pharmacological response to ET receptor antagonists with various selectivities for the receptor subtypes. Therefore, the purposes of this study were to evaluate potential modifications of the pharmacology of the ET system in rat pulmonary resistance arteries from monocrotaline (MCT)-induced pulmonary arterial hypertension.Experimental approachET-1 levels were quantified by ELISA. PreproET-1, ET_A and ET_B receptor mRNA expressions were quantified in pulmonary resistance arteries using Q-PCR, while protein expression was evaluated by Western blots. Reactivity to ET-1 of isolated pulmonary resistance arteries was measured in the presence of ET_A (A-147627), ET_B (A-192621) and dual ET_A/B (bosentan) receptor antagonists.Key resultsIn rats with PAH, plasma ET-1 increased (p < 0.001) while pulmonary levels were reduced (p < 0.05). In PAH arteries, preproET-1 (p < 0.05) and ET_B receptor (p < 0.001) gene expressions were reduced, as were ET_B receptor protein levels (p < 0.05). ET-1 induced similar vasoconstrictions in both groups. In arteries from sham animals, neither bosentan nor the ET_A or the ET_B receptor antagonists modified the response. In arteries from PAH rats, however, bosentan and the ET_A receptor antagonist potently reduced the maximal contraction, while bosentan also reduced sensitivity (p < 0.01).Conclusions and implicationsThe effectiveness of both selective ET_A and dual ET_A/B receptor antagonists is markedly increased in PAH. Down-regulation of pulmonary resistance arteries ET_B receptor may contribute to this finding.     

Pulmonary Hemodynamic Response to Acute Combination and Monotherapy With Sildenafil and Brain Natriuretic Peptide in Rats With Monocrotaline-Induced Pulmonary Hypertension

BackgroundThe lungs of patients with pulmonary arterial hypertension (PAH) exhibit decreased bioavailability of nitric oxide and downstream signaling through cyclic guanosine monophosphate (cGMP). Therapies that enhance cGMP-mediated vasodilation have shown efficacy in treating PAH. We tested the hypothesis that combination therapy with sildenafil, a cGMP phosphodiesterase type 5 inhibitor, and brain natriuretic peptide (BNP), a receptor-mediated guanosine cyclase stimulator, synergistically attenuates monocrotaline-induced PAH in rats compared with either monotherapy.MethodsAdult male Sprague-aDawley rats were subcutaneously injected with monocrotaline (n = 41, 50 mg/kg). After approximately 4 weeks, the rats were infused intravenously with vehicle solution, sildenafil (42 and 85 μg/kg/min), or BNP (50 and 100 ng/kg/min), alone and in varied combination. The primary endpoint was the relative change in right ventricular systolic pressure (RVSP) and mean arterial systemic pressure (MAP). Secondary endpoints included heart rate and dP/dt.ResultsVehicle infusions did not alter hemodynamic variables. Sildenafil₈₅ (85 μg/kg/min) alone decreased RVSP (? 16.6 ± 5.6%) and decreased MAP (? 4.0 ± 4.7%). BNP₅₀ (50 ng/kg/min) and BNP₁₀₀ (100 ng/kg/min) decreased RVSP (? 23.3 ± 5.7% and ? 27.1 ± 2.9%, respectively) and MAP (? 6.4 ± 5.8% and ? 14.3 ± 4.1%, respectively). Combination therapy with sildenafil₄₂ and BNP₅₀ decreased RVSP (? 20.7 ± 5.6%) and showed a lessened systemic effect (MAP = ? 11.6 ± 5.9%). Combination therapy with sildenafil₈₅ and BNP₁₀₀ decreased RVSP (? 27.6 ± 3.2%, P = NS) and showed increased systemic effect (MAP = ? 20.7 ± 3.1%, P < 0.05) in comparison with sildenafil₈₅.ConclusionsThis study suggests that intravenous administration of both sildenafil and BNP monotherapy produces significant improvement in RVSP, making them potentially viable options for the treatment of PAH, whereas combination therapy produces no additional improvement in pulmonary hemodynamics.     

Utility of right ventricular Tei-index for assessing disease severity and determining response to treatment in patients with pulmonary arterial hypertension

BackgroundWe sought to evaluate the potential utility of echocardiography-derived morphological and functional right ventricular (RV) variables for assessing disease severity of pulmonary arterial hypertension (PAH) and determining the changes in the patient's hemodynamics in the clinical course.Methods and resultsThis study consisted of 24 normal controls (the control group) and 24 patients with PAH at rest or with exercise (the PAH group) who underwent echocardiography, right heart catheterization, plasma brain natriuretic peptide (BNP) measurement, and six-minute walk distance (6MWD) test. The PAH group had poorer RV echocardiographic variables than the control group. RV Tei-index was more strongly correlated with 6MWD, BNP, cardiac index, mean pulmonary arterial pressure, and pulmonary vascular resistance (PVR) than other RV echocardiography-derived variables including RV end-diastolic areas, RV fractional area change, and tricuspid annular plane systolic excursion. In 16 of the 24 patients who successfully underwent repeated examination during follow up (13.3 ± 4.9 months; range, 5–24 months), PVR decreased from 486 ± 380 dyne s cm⁻⁵ to 346 ± 252 dyne s cm⁻⁵, and RV Tei-index decreased from 0.55 ± 0.30 to 0.42 ± 0.17, and the changes in RV Tei-index were correlated with the concomitant changes in PVR during the clinical course of PAH (r = 0.706, p = 0.002). Tricuspid annular plane systolic excursion and RV fractional area change did not change during the follow up.ConclusionsQuantitative echocardiography revealed that the measurement of RV Tei-index is of great clinical utility for predicting disease severity of PAH and determining the changes in the patient's hemodynamics in the clinical course.     

Disproportionate pulmonary arterial hypertension and lung respiratory diseases: distinctive clinical, hemodynamic and prognosis of patients versus primary pulmonary arterial hypertension

ObjectivesTo characterize and compare patients with disproportionate PH versus patients with primary pulmonary arterial hypertension (PAH).MethodsAll patients referred to our cardiology unit for echocardiography from November 2006 to May 2008 and who have been followed by our pneumologist were screened for severe PH (i.e mean arterial pulmonary pressure > 35–40 mmHg at rest). Patients were excluded if a factor that could influence pulmonary hemodynamics was present. We investigated these patients by pulmonary function tests, echocardiography and right heart catheterisation.ResultsWe reported 16 cases of severe PH in stable patients (n = 8, chronic obstructive pulmonary disease-emphysema) and 13 patients with PAH. Our findings suggest that the patients with disproportionate PH had right heart dysfunction similar to that observed in PAH. But their outcomes were more severe. It seemed that specific vasodilatator therapy was not efficient.     

Mitochondrial complex II participates in normoxic and hypoxic regulation of α-keto acids in the murine heart

α-Keto acids (α-KAs) are not just metabolic intermediates but are also powerful modulators of different cellular pathways. Here, we tested the hypothesis that α-KA concentrations are regulated by complex II (succinate dehydrogenase = SDH), which represents an intersection between the mitochondrial respiratory chain for which an important function in cardiopulmonary oxygen sensing has been demonstrated, and the Krebs cycle, a central element of α-KA metabolism. SDH subunit D heterozygous (SDHD^+/−) and wild-type (WT) mice were housed at normoxia or hypoxia (10% O₂) for 4 days or 3 weeks, and right ventricular pressure, right ventricle/(left ventricle + septum) ratio, cardiomyocyte ultrastructure, pulmonary vascular remodelling, ventricular complex II subunit expression, SDH activity and α-KA concentrations were analysed. In both strains, hypoxia induced increases in right ventricular pressure and enhanced muscularization of distal pulmonary arteries. Right ventricular hypertrophy was less severe in SDHD^+/− mice although the cardiomyocyte ultrastructure and mitochondrial morphometric parameters were unchanged. Protein amounts of SDHA, SDHB and SDHC, and SDH activity were distinctly reduced in SDHD^+/− mice. In normoxic SDHD^+/− mice, α-ketoisocaproate concentration was lowered to 50% as compared to WT animals. Right/left ventricular concentration differences and the hypoxia-induced decline in individual α-KAs were less pronounced in SDHD^+/− animals indicating that mitochondrial complex II participates in the adjustment of cardiac α-KA concentrations both under normoxic and hypoxic conditions. These characteristics are not related to the hemodynamic consequences of hypoxia-induced pulmonary vascular remodelling, since its extent and right ventricular pressure were not affected in SDHD^+/− mice albeit right ventricular hypertrophy was attenuated.     

Functional improvement in a patient with cirrhosis and portopulmonary hypertension treated by sildenafil for 2 years

Portopulmonary hypertension (PPH) represents an uncommon form of pulmonary arterial hypertension (PAH) associated with portal hypertension and cirrhosis. PPH is a severe disease with a poor short-term prognosis, with a possibility of liver transplantation only for patients with mild to moderate PAH. Patients with PAH could be candidates for specific vasodilator-based treatment, the choice of which being guided by their toxicity profile. We report here the case of a 46-year-old woman with a cirrhosis (Child-Pugh C) complicated by a severe PPH (mean pulmonary arterial pressure: 49 mmHg, pulmonary vascular resistance: 688 dynes, right ventricular dysfunction), with NYHA class III dyspnea and an altered 6-min walk distance (6MWD). Treatment with sildenafil (20 mg t.i.d) was started. In the first 6 months, a functional improvement was indicated by dyspnea assessed as class II, an increased distance at the 6MWD (375 m vs. 250 m without oxygen desaturation), and a normalization of right ventricular function. After one year of therapy, the benefits were maintained (6MWD: 465 m) and transthoracic echocardiography showed a normalization of pulmonary arterial pressures. Sildenafil treatment was well tolerated. At two years, haemodynamic values measured by right heart catheterization were similar to the pre-treatment values, while clinical and functional parameters remained improved. At our knowledge, this is the first case delineating the long-term functional benefit of sildenafil monotherapy, making this drug a therapeutic option in patients with PPH and cirrhosis, the usefulness of which in the waiting period for liver transplantation needs to be evaluated.     

Evaluation of left ventricular diastolic function using tissue Doppler echocardiography and conventional doppler echocardiography in patients with subclinical hypothyroidism aged <60 years: A meta-analysis

Studies have suggested that subclinical hypothyroidism (SCH) may have detrimental effects on left ventricular (LV) diastolic function. Whether SCH is a risk factor for LV diastolic dysfunction is controversial. Databases (MEDLINE, PubMed, EMBASE) were searched for cross-sectional studies evaluating LV diastolic function in SCH patients aged <60 years using tissue Doppler echocardiography (TDE) and conventional two-dimensional Doppler echocardiography (2D-DECG) published in the past 12 years. The weighted mean difference (WMD) and 95% confidence interval (CI) were calculated using fixed or random-effects models. We summarized the results of 14 cross-sectional studies with 675 participants. SCH patients had a significantly lower LV mitral annular E_a peak velocity (WMD = ?1.71 cm/s; 95%CI: ?3.02 to ?0.40; p < 0.05), E_a/A_a ratio (WMD = ?0.22; 95%CI: ?0.40 to ?0.05; p < 0.05), and significantly higher mitral annular A_a peak velocity (WMD = 0.47 cm/s; 95%CI: 0.10–0.85; p < 0.05) than euthyroid subjects using TDE. Subgroup analyses showed that statistical significance existed only in E_a and E_a/A_a parameters when data from “women ≥ 90%” were used, and in the A_a parameter when data from “women < 90%” were used. No matter which subgroup of females was used, there were significant differences in LV peak transmitral A velocity (WMD = 7.64 cm/s; 95%CI: 4.55–10.73; p < 0.05), and E/A ratio (WMD = ?0.22; 95%CI: ?0.31 to ?0.21; p < 0.05) but no significant difference in peak transmitral E velocity (p > 0.05) between SCH patients and euthyroid controls using 2D-DECG. Therefore, for those aged <60 years, SCH patients had significantly worse parameters of LV diastolic function than euthyroid controls.     

Tiotropium bromide exerts anti-inflammatory activity in a cigarette smoke mouse model of COPD

Tiotropium bromide is a long acting muscarinic antagonist (LAMA), marketed under the brand name Spiriva^®, for the treatment of chronic obstructive pulmonary disease (COPD). Besides its proven direct bronchodilatory activity, recent clinical studies demonstrated that tiotropium is able to reduce the exacerbation rate and impact the clinical course of COPD. One significant pathological feature believed to be causative for the progressive nature of COPD is chronic pulmonary inflammation. The aim of the present study was to investigate the anti-inflammatory activity of tiotropium on cigarette smoke-induced pulmonary inflammation in mice. C57Bl/6 mice were exposed to cigarette smoke (CS) for four days with increasing exposure time for up to 6 h per day to elicit pulmonary inflammation and mediator release. One hour before smoke exposure, animals were treated with tiotropium by inhalation (0.01–0.3 mg/mL) for 5 min; 18 h after the last CS exposure a bronchoalveolar lavage was performed. Tiotropium concentration-dependently inhibited pulmonary neutrophilic inflammation with an IC₅₀ of 0.058 mg/mL and a maximum inhibition of 60% at 0.3 mg/mL. Furthermore, the CS-induced pulmonary release of leukotriene B₄, interleukin-6, keratinocyte-derived chemokine, monocyte chemotactic protein-1, macrophage inflammatory protein-1alpha and ?2, and tumor necrosis factor alpha was dose-dependently reduced. The bronchodilatory activity of tiotropium against acetycholine-induced bronchoconstriction was found to be in the same dose range as the anti-inflammatory activity with an IC₅₀ of 0.045 mg/mL and a maximum bronchodilation of 90% at 0.3 mg/mL. Our data suggest that the beneficial effects of tiotropium on the course of COPD shown in patients may be associated with an anti-inflammatory activity.     

Bosentan for patients with chronic thromboembolic pulmonary hypertension

BackgroundChronic thromboembolic pulmonary hypertension (CTEPH) is a progressive disease leading to worsening functional status and reduced survival for those patients who cannot undergo pulmonary endarterectomy (PEA). Pharmacotherapy with novel drugs for pulmonary hypertension may be useful in treating patients who are poor candidates for surgery, but there are still few clinical data on medical therapy for CTEPH.The aim of this prospective open-label, multicenter, study is to compare the efficacy of 1-year bosentan treatment to standard drugs in nonoperated patients with CTEPH.Patients and methodsThirty-four nonoperated patients with CTEPH were enrolled. Functional assessment included 6 minute walk test (6MWT), Borg index, WHO classification, arterial blood gases and echocardiography systolic pulmonary artery pressure (sPAP). Seventeen patients received bosentan (62.5 mg bid for 4 weeks and then 125 mg bid); 17 patients were treated with standard therapy alone.ResultsAt admission sPAP was 76.18 +/? 5.96 mmHg in bosentan group and 71.48 +/? 3.71 mmHg in controls, p_aO₂ 64.68 +/? 2.25 mmHg in bosentan group, and 59.52 +/? 2.05 mmHg in controls, 6MWT 297.53 +/? 34.25 mt in bosentan group, and 268.47 +/? 36.54 mt in controls. After 12 months there were significant differences between the groups in the 6MWT (+ 57.24 +/? 22.21 m vs ? 73.13 +/? 21.23 m, p < 0.001), dyspnoea index (Borg score 4.29 +/? 0.49 vs 7.06 +/? 0.32, p < 0.001) and oxygenation (p_aO₂ 65.93 +/? 3.76 mmHg vs 48.48 +/? 1.31 mmHg, p < 0.001). The sPAP was stable after 12 months of bosentan (76.18 +/? 5.96 mmHg vs 71.00 +/? 5.41 mmHg, p = 0.221) in contrast to controls (71.48 +/? 3.71 mmHg vs 80.44 +/? 4.70 mmHg, p = 0.029).ConclusionThe data of this open-label study in nonoperated CTEPH patients suggest an improvement in functional outcomes adding Bosentan to diuretics and oral anticoagulants. No improvement was observed using only standard drugs after 1-year.     

Beneficial effects of ursodeoxycholic acid via inhibition of airway remodelling,apoptosis of airway epithelial cells,and Th2 immune response in murine model of chronic asthma

Background and aimsIn previous studies, anti-inflammatory, anti-apoptotic and immunomodulatory effects of ursodeoxycholic acid (UDCA) on liver diseases have been shown. In this study, we aimed to investigate the effects of UDCA on airway remodelling, epithelial apoptosis, and T Helper (Th)-2 derived cytokine levels in a murine model of chronic asthma.MethodsTwenty-seven BALB/c mice were divided into five groups; PBS-Control, OVA-Placebo, OVA-50 mg/kg UDCA, OVA-150 mg/kg UDCA, OVA-Dexamethasone. Mice in groups OVA-50 mg/kg UDCA, OVA-150 mg/kg UDCA, OVA-Dexamethasone received the UDCA (50 mg/kg), UDCA (150 mg/kg), and dexamethasone, respectively. Epithelium thickness, sub-epithelial smooth muscle thickness, number of mast and goblet cells of samples isolated from the lung were measured. Immunohistochemical scorings of the lung tissue for matrix metalloproteinase-9 (MMP-9), vascular endothelial growth factor (VEG-F), transforming growth factor-beta (TGF-β), terminal deoxynucleotidyl transferase-mediated dUTP nick endlabeling (TUNEL) and cysteine-dependent aspartate-specific proteases (caspase)-3 were determined. IL-4, IL-5, IL-13, Nitric oxide, ovalbumin-specific immunoglobulin (Ig) E levels were quantified.ResultsThe dose of 150 mg/kg UDCA treatment led to lower epithelial thickness, sub-epithelial smooth muscle thickness, goblet and mast cell numbers compared to placebo. Except for MMP-9 and TUNEL all immunohistochemical scores were similar in both UDCA treated groups and the placebo. All cytokine levels were significantly lower in group IV compared to the placebo.ConclusionsThese findings suggested that the dose of 150 mg/kg UDCA improved all histopathological changes of airway remodelling and its beneficial effects might be related to modulating Th-2 derived cytokines and the inhibition of apoptosis of airway epithelial cells.     

Left Ventricular Mass is Preserved in Patients with Idiopathic Pulmonary Arterial Hypertension and Eisenmenger's Syndrome

BackgroundLeft ventricular (LV) atrophic remodelling was described for chronic thromboembolic pulmonary hypertension (PH) but not in other forms of PH. We aimed to assess LV morphometric changes in idiopathic pulmonary arterial hypertension (IPAH) and Eisenmenger's syndrome(ES).MethodsFifteen patients with IPAH, 15 patients with ES and 15 healthy volunteers were included. Magnetic resonance was used to measure masses of LV, interventricular septum (IVS), LV free wall (LVFW), and LV end diastolic volume (LVEDV) indexed for body surface area.ResultsBetween patients with IPAH, ES and controls no differences in LVmass_index (54.4[45.2-63.3] vs 58.7[41.5-106.1] vs 52.8[46.5-59.3], p = 0.50), IVSmass_index (21.6[18.2-21.9)] vs 27.4[18.0-32.9] vs 20.7[18.2-23.2], p = 0.18), and LVFWmass_index ([32.4[27.1-40.0] vs 36.7[30.9-62.1] vs 32.5[26.9-36.1], p = 0.29) were found. LVEDV_index was lower in IPAH patients than in controls and in ES patients (54.9[46.9-58.5] vs 75.2[62.4-88.9] vs 73.5[62.1-77.5], p < 0.001). In IPAH LVEDV but not LV mass correlated with pulmonary vascular resistance (r = -0.56, p = 0.03) and cardiac output (r = 0.59, p = 0.02).ConclusionsLV mass is not reduced in patients with IPAH and with ES and is not affected by haemodynamic severity of PH. LVEDV is reduced in IPAH patients in proportion to reduced pulmonary flow but preserved in patients with ES, where reduced pulmonary flow to LV is compensated by right-to left shunt.     

Impairment of Autonomic Nervous System Activity in Patients With Pulmonary Arterial Hypertension: A Case Control Study

BackgroundChronotropic response to exercise (CR) and heart rate recovery (HRR) immediately after exercise are indirect indices of sympathetic and parasympathetic activity, respectively. The aim of this study was to evaluate CR and HRR in patients with pulmonary arterial hypertension (PAH) in relation to disease severity.Methods and ResultsTen PAH patients (6 females/4 males, mean age: 48 ± 12 years) and 10 control subjects matched for age, gender, and body mass index (6 females/4 males, mean age: 46 ± 6 years) performed a ramp incremental symptom-limited cardiopulmonary exercise test on a cycle ergometer. Main measurements included heart rate at rest (HR), CR = [(peak HR-resting HR/220-age-resting HR) × 100, %], HRR₁ = HR difference from peak exercise to 1 minute after, ventilatory efficiency during exercise (VE/VCO₂ slope), peak oxygen uptake (VO₂p), and the first-degree slope of VO₂ for the first minute of the recovery period (VO₂/t-slope). PAH patients had a significantly decreased CR (58 ± 31 vs 92 ± 13, %, P < .001) and HRR₁ (10 ± 5 vs 29 ± 6, beats/min, P < .001) as well as VO₂p (11.9 ± 3.5 vs 26.9 ± 6.6, mL·kg·min) and VO₂/t-slope (0.2 ± 0.1 vs. 0.9 ± 0.2, mL·kg·min²) compared with controls. CR and HRR₁ correlated well with VO₂p (r = 0.7; P < .001 and r = 0.85; P < .001, respectively) and VO₂/t-slope (r = 0.66; P < .001 and r = 0.85; P < .001, respectively) and had a significant inverse correlation with VE/VCO₂ slope (r = –0.47; P < .01 and r = –0.77; P < .001, respectively).ConclusionsPAH patients present a significant impairment of CR and HRR₁ in relation to disease severity, indicating profound autonomic nervous system abnormalities.     

Une cause rare d’hypertension artérielle pulmonaire : l’amylose thoracique

Isolated thoracic involvement in amyloidosis is a rare and serious condition. Its association with pulmonary arterial hypertension (PAH) usually weakens the prognosis. We report the case of a 40-year-old man with a smoking history, hospitalized for chest pain, abdominal pain and acute respiratory distress. The cardiac ultrasound revealed a circumferential pericardial effusion as well as a pulmonary artery systolic pressure (PAPS) at 80 mmHg. Chest imaging (computed tomography scan and magnetic resonance imaging) showed a tissue process developed in the pericardial sheath (60 × 45 mm) sheathing the ascending aorta and infiltrating the trunk of the pulmonary artery and its right branch. Anatomopathological and immunohistochemical study of the process revealed AL amyloidosis. Note that the patient had no signs of extrathoracic amyloidosis. Blood and urine electrophoresis and immunoelectrophoresis as well as bone marrow mylogram and biopsy were normal. The patient was put on oral anticoagulant as he presented with PAH. A therapeutic protocol with thalidomide and dexamethasone has been initiated. The course of the disease was marked by total regression of the clinical signs, a marked decrease in the amyloid process on imaging and a normalization of the PAPS; our follow-up being three years.     

Intermedin modulates hypoxic pulmonary vascular remodeling by inhibiting pulmonary artery smooth muscle cell proliferation

BackgroundHypoxic pulmonary arterial hypertension (PAH) is a disabling disease with limited treatment options. Hypoxic pulmonary vascular remodeling is a major cause of hypoxic PAH. Pharmacological agents that can inhibit the remodeling process may have great therapeutic value.ObjectiveTo examine the effect of intermedin (IMD), a new calcitonin gene-related peptide family of peptide, on hypoxic pulmonary vascular remodeling.MethodsRats were exposed to normoxia or hypoxia (∼10% O₂), or exposed to hypoxia and treated with IMD, administered by an implanted mini-osmotic pump (6.5 μg/rat/day), for 4 weeks. The effects of IMD infusion on the development of hypoxic PAH and right ventricle (RV) hypertrophy, on pulmonary vascular remodeling, on pulmonary artery smooth muscle cell (PASMC) proliferation and apoptosis, and on the activations of l-arginine nitric oxide (NO) pathway and endoplasmic reticulum stress apoptotic pathway were examined.ResultsRats exposed to hypoxia developed PAH and RV hypertrophy. IMD treatment alleviated PAH and prevented RV hypertrophy. IMD inhibited hypoxic pulmonary vascular remodeling as indicated by reduced wall thickness and increased lumen diameter of pulmonary arterioles, and decreased muscularization of distal pulmonary vasculature in hypoxia-exposed rats. IMD treatment inhibited PASMC proliferation and promoted PASMC apoptosis. IMD treatment increased tissue level of constitutive NO synthase activity and tissue NO content in lungs, and enhanced l-arginine uptake into pulmonary vascular tissues. IMD treatment increased cellular levels of glucose-regulated protein (GRP) 78 and GRP94, two major markers of endoplasmic reticulum (ER) stress, and increased caspase-12 expression, the ER stress-specific caspase, in lungs and cultured PASMCs.ConclusionsThese results demonstrate that IMD treatment attenuates hypoxic pulmonary vascular remodeling, and thereby hypoxic PAH mainly by inhibiting PASMC proliferation. Promotion of PASMC apoptosis may also contribute to the inhibitory effect of IMD. Activations l-arginine–NO pathway and of ER stress-specific apoptosis pathway could be the mechanisms mediating the anti-proliferative and pro-apoptotic effects of IMD.     

Diverse contribution of bone marrow-derived late-outgrowth endothelial progenitor cells to vascular repair under pulmonary arterial hypertension and arterial neointimal formation

AimsIt is still controversial whether bone marrow (BM)-derived endothelial progenitor cells (EPCs) can contribute to vascular repair and prevent the progression of vascular diseases. We aimed to characterize BM-derived EPC subpopulations and to evaluate their therapeutic efficacies to repair injured vascular endothelium of systemic and pulmonary arteries.Methods and resultsBM mononuclear cells of Fisher-344 rats were cultured under endothelial cell-conditions. Early EPCs appeared on days 3–6. Late-outgrowth and very late-outgrowth EPCs (LOCs and VLOCs) were defined as cells forming cobblestone colonies on days 9–14 and 17–21, respectively. Among EPC subpopulations, LOCs showed the highest angiogenic capability with enhanced proliferation potential and secretion of proangiogenic proteins. To investigate the therapeutic effects of these EPCs, Fisher-344 rats underwent wire-mediated endovascular injury in femoral artery (FA) and were concurrently injected intraperitoneally with 60 mg/kg monocrotaline (MCT). Injured rats were then treated with six injections of one of three EPCs (1 × 10⁶ per time). After 4 weeks, transplanted LOCs, but not early EPCs or VLOCs, significantly attenuated neointimal lesion formation in injured FAs. Some of CD31⁺ LOCs directly replaced the injured FA endothelium (replacement ratio: 11.7 ± 7.0%). In contrast, any EPC treatment could neither replace MCT-injured endothelium of pulmonary arterioles nor prevent the progression of pulmonary arterial hypertension (PAH). LOCs modified protectively the expression profile of angiogenic and inflammatory genes in injured FAs, but not in MCT-injured lungs.ConclusionBM-derived LOCs can contribute to vascular repair of injured systemic artery; however, even they cannot rescue injured pulmonary vasculature under MCT-induced PAH.     

Hépatopathies et maladies vasculaires pulmonaires

About 70% patients waiting for liver transplantation have a dyspnea. Two pulmonary vascular disorders can be associated with portal hypertension or chronic liver diseases: portopulmonary hypertension (PoPH) related to pulmonary small arteries remodeling and obstruction and hepatopulmonary syndrome (HPS) characterized by pulmonary capillaries dilatations and proliferations. PoPH is defined by the combination of pulmonary arterial hypertension (PAH) (mean pulmonary artery pressure [PAP] ≥ 25 mmHg, with normal pulmonary artery wedge pressure ≤ 15 mmHg and pulmonary vascular resistance [PVR] > 3 Wood units [WU]) and portal hypertension. HPS is a triad of intrapulmonary vascular dilatations, hypoxemia (increased alveolar-arterial oxygen gradient) and liver disease or isolated portal hypertension. The pathophysiology of both syndromes is complex and poorly understood. PoPH and HPS have a negative impact on functional and vital prognosis in patients with portal hypertension. Liver transplantation is the established treatment standard in HPS. PoPH treatment is improved over the years with the use of specific PAH treatment despite the lack of randomized assay in this indication. Liver transplantation could be considered in PoPH leading to stabilization, improvement or recovery in selected patients (mean PAP < 35 mmHg without severe right ventricular dysfunction and PVR < 4 WU).     

Low-molecular-weight heparin inhibits hypoxic pulmonary hypertension and vascular remodeling in guinea pigs

RATIONALE: We have shown previously that antiproliferative unfractionated heparins block hypoxia-induced pulmonary arterial hypertension (PAH) and vascular remodeling, and hypothesized that low-molecular-weight heparins (LMWHs) would too. OBJECTIVES: To determine the potential role and mechanisms of dalteparin and enoxaparin (two LMWHs) in inhibiting hypoxic PAH and vascular remodeling. METHODS: Male Hartley guinea pigs were exposed for 10 days to normobaric 10% oxygen with dalteparin (5 mg/kg), enoxaparin (5 mg/kg), or with an equivalent volume of normal saline solution. Normoxic control animals (n = 5) received room air for 10 days. Bovine pulmonary artery smooth-muscle cells (PASMCs) were grown in 10% fetal bovine serum without heparin, with dalteparin (1 microg/mL) or with enoxaparin (1 microg/mL). MEASUREMENTS: Pulmonary arterial pressure (PAP), cardiac index, right ventricular heart weight divided by left ventricular plus septum weight (RV/LV+S), hematocrit, percentage of wall thickness of intraacinar vessels (%WT-IA), percentage of wall thickness of terminal bronchiole vessels (%WT-TA), and the percentage of thick-walled vessels (%Thick) were determined. In PASMCs, expression of p27 and cell growth were compared because in mice whole heparin depends on p27 for its antiproliferative action. MAIN RESULTS: In hypoxic animals, hematocrit, PAP, total pulmonary vascular resistance index, RV/LV+S, %WT-IA, %WT-TA, and %Thick all rose significantly vs normoxic control animals (p < 0.05); cardiac index was unchanged. Dalteparin but not enoxaparin significantly reduced PAP, total pulmonary vascular resistance index, and RV/LV + S (p < 0.05 vs hypoxia alone); inhibited PASMC growth; and upregulated p27 expression. Enoxaparin moderately reduced vascular remodeling, which did not translate into less pulmonary hypertension. CONCLUSIONS: Not all LMWHs are the same. Dalteparin was more effective than enoxaparin in inhibiting pulmonary hypertension and vascular remodeling in hypoxic guinea pigs.     

Effects of olopatadine hydrochloride on the release of thromboxane B2 and histamine from nasal mucosa after antigen–antibody reaction in guinea pigs

BackgroundVarious mediators, such as thromboxane (TX) A₂, peptide leukotrienes (P-LT) and histamine, are involved in allergic nasal obstruction. The aim of the present study was to investigate the mechanism whereby olopatadine hydrochloride, a novel anti-allergic drug, ameliorated the allergic nasal obstruction.MethodsThe levels of TXB₂, P-LT and histamine in nasal lavage fluid (NLF) were measured after intranasal antigen challenge in sensitized guinea pigs.ResultsHistamine and TXB₂ levels in the NLF increased eight- and threefold, respectively, 10 min after antigen challenge, whereas the P-LT level was under the detection limit. Oral administration of olopatadine at 0.1, 1 and 3 mg/kg significantly inhibited the increases in TXB₂ and histamine levels. At 3 mg/kg, olopatadine also ameliorated the nasal obstruction caused 10 min after antigen challenge, as determined by acoustic rhinometry.ConclusionsThese results suggest that the amelioration by olopatadine of the allergic nasal obstruction involves the inhibition of the release of TXA₂ and histamine.     

Left ventricular end-diastolic pressure affects measurement of fractional flow reserve

BackgroundFractional flow reserve (FFR), the hyperemic ratio of distal (P_d) to proximal (P_a) coronary pressure, is used to identify the need for coronary revascularization. Changes in left ventricular end-diastolic pressure (LVEDP) might affect measurements of FFR.Methods and MaterialsLVEDP was recorded simultaneously with P_d and P_a during conventional FFR measurement as well as during additional infusion of nitroprusside. The relationship between LVEDP, P_a, and FFR was assessed using linear mixed models.ResultsProspectively collected data for 528 cardiac cycles from 20 coronary arteries in 17 patients were analyzed. Baseline median P_a, P_d, FFR, and LVEDP were 73 mmHg, 49 mmHg, 0.69, and 18 mmHg, respectively. FFR < 0.80 was present in 14 arteries (70%). With nitroprusside median P_a, P_d, FFR, and LVEDP were 61 mmHg, 42 mmHg, 0.68, and 12 mmHg, respectively. In a multivariable model for the entire population LVEDP was positively associated with FFR such that FFR increased by 0.008 for every 1-mmHg increase in LVEDP (beta = 0.008; P < 0.001), an association that was greater in obstructed arteries with FFR < 0.80 (beta = 0.01; P < 0.001). P_a did not directly affect FFR in the multivariable model, but an interaction between LVEDP and P_a determined that LVEDP’s effect on FFR is greater at lower P_a.ConclusionsLVEDP was positively associated with FFR. The association was greater in obstructive disease (FFR < 0.80) and at lower P_a. These findings have implications for the use of FFR to guide revascularization in patients with heart failure.Summary for Annotated Table of ContentsThe impact of left ventricular diastolic pressure on measurement of fractional flow reserve (FFR) is not well described. We present a hemodynamic study of the issue, concluding that increasing left ventricular diastolic pressure can increase measurements of FFR, particularly in patients with FFR < 0.80 and lower blood pressure.     

Blockade of neutrophil responses in aspiration pneumonia via ELR-CXC chemokine antagonism does not predispose to airway bacterial outgrowth

Pneumonia associated with aspiration of bacterial-laden gastric contents is characterized by Glu-Leu-Arg (ELR)-CXC chemokine (e.g., CXC2L1, CXCL8) expression leading to local neutrophil sequestration. This neutrophil response is designed to be protective, but overly aggressive responses can be pathogenic in themselves. Herein we assessed whether blocking neutrophil responses in a guinea pig model of aspiration pneumonia would foster airway bacterial growth. Guinea pigs (n = 5) were challenged intranasally with saline, acidified saline or acidified gastric contents (35 mg/kg body weight, pH 2.0) and treated subcutaneously with 250 μg/kg of the human ELR-CXC chemokine antagonist CXCL8_(3–72)K11R/G31P (G31P) or saline. After 20 h the animals' airway inflammatory responses and bacterial burdens were assessed. A loss of vascular integrity was apparent in the lungs of the saline-treated aspiration pneumonia animals (12.07+/?1.3% of the pleural surfaces exhibited hemorrhagic consolidation, 4.6 × 10⁶ RBC/ml bronchoalveolar lavage fluid [BALF]), as was a pulmonary neutrophilia. The BAL fluids contained gram-negative and -positive bacteria (total load, 6.3+/?3.2 × 10⁷ CFU/ml BALF) that are associated with nosocomial infections in humans. The G31P-treatments attenuated the pulmonary vascular complications (2.27+/?0.5% pleural surface hemorrhagic consolidation, 0.46 × 10⁶ RBC/ml BALF), and reduced the pulmonary neutrophilia by ≥86%. The G31P-treatments did not lead to significant changes in the airway bacterial loads (total load, 3.46+/?1.8 × 10⁷ CFU/ml BALF). This data indicates that attenuation of the pulmonary neutrophil response in aspiration pneumonia reduces pathology very significantly but does not reduce the efficiency of pulmonary bacterial clearance.