Connexin-43 is a promising target for pulmonary hypertension due to hypoxaemic lung disease.

The mechanisms underlying pulmonary hypertension (PH) are complex and multifactorial, and involve different cell types that are interconnected through gap junctional channels. Although connexin (Cx)-43 is the most abundant gap junction protein in the heart and lungs, and critically governs intercellular signalling communication, its contribution to PH remains unknown. The focus of the present study is thus to evaluate Cx43 as a potential new target in PH.Expressions of Cx37, Cx40 and Cx43 were studied in lung specimens from patients with idiopathic pulmonary arterial hypertension (IPAH) or PH associated with chronic hypoxaemic lung diseases (chronic hypoxia-induced pulmonary hypertension (CH-PH)). Heterozygous Cx43 knockdown CD1 (Cx43+/-) and wild-type littermate (Cx43+/+) mice at 12 weeks of age were randomly divided into two groups, one of which was maintained in room air and the other exposed to hypoxia (10% oxygen) for 3 weeks. We evaluated pulmonary haemodynamics, remodelling processes in cardiac tissues and pulmonary arteries (PAs), lung inflammation and PA vasoreactivity.Cx43 levels were increased in PAs from CH-PH patients and decreased in PAs from IPAH patients; however, no difference in Cx37 or Cx40 levels was noted. Upon hypoxia treatment, the Cx43+/- mice were partially protected against CH-PH when compared to Cx43+/+ mice, with reduced pulmonary arterial muscularisation and inflammatory infiltration. Interestingly, the adaptive changes in cardiac remodelling in Cx43+/- mice were not affected. PA contraction due to endothelin-1 (ET-1) was increased in Cx43+/- mice under normoxic and hypoxic conditions.Taken together, these results indicate that targeting Cx43 may have beneficial therapeutic effects in PH without affecting compensatory cardiac hypertrophy.

Beneficial effect of dehydroepiandrosterone on pulmonary hypertension in a rodent model of pulmonary hypertension in infants.

BACKGROUND: Pulmonary hypertension (PH) is a disease that affects the adult or infant population. Dehydroepiandrosterone (DHEA), a steroid hormone, has been previously shown to prevent and to reverse PH in an adult rat model. We thus investigated its effect in a rat-pup model of chronic hypoxic PH. METHODS: Animals were maintained for 3 wk in a hypobaric chamber to induce PH, with or without concomitant treatment with DHEA (30 mg/kg every alternate day). RESULTS: DHEA significantly reduced mean pulmonary artery pressure (measured by right cardiac catheterization), pulmonary artery remodeling (evaluated by histology), and right-ventricular hypertrophy (measured by echography and by the Fulton index). At the level of the pulmonary artery smooth muscle cell (PASMC), DHEA increased activity and expression of the large-conductance Ca2+-activated potassium channel (BKCa) (assessed by means of the patch clamp technique). DHEA also inhibited both serotonin- and KCl-induced contraction and smooth muscle cell proliferation. CONCLUSION: Collectively, these results indicate that DHEA prevents PH in infant rats and may therefore be clinically relevant for the management of PH in human infants.

Signal transducers and activators of transcription-3/pim1 axis plays a critical role in the pathogenesis of human pulmonary arterial hypertension.

BACKGROUND: Pulmonary artery hypertension (PAH) is a proliferative disorder associated with enhanced pulmonary artery smooth muscle cell proliferation and suppressed apoptosis. The sustainability of this phenotype required the activation of a prosurvival transcription factor like signal transducers and activators of transcription-3 (STAT3) and nuclear factor of activated T cell (NFAT). Because these factors are implicated in several physiological processes, their inhibition in PAH patients could be associated with detrimental effects. Therefore, a better understanding of the mechanism accounting for their expression/activation in PAH pulmonary artery smooth muscle cells is of great therapeutic interest. METHODS AND RESULTS: Using multidisciplinary and translational approaches, we demonstrated that STAT3 activation in both human and experimental models of PAH accounts for the expression of both NFATc2 and the oncoprotein kinase Pim1, which trigger NFATc2 activation. Because Pim1 expression correlates with the severity of PAH in humans and is confined to the PAH pulmonary artery smooth muscle cell, Pim1 was identified as an attractive therapeutic target for PAH. Indeed, specific Pim1 inhibition in vitro decreases pulmonary artery smooth muscle cell proliferation and promotes apoptosis, all of which are sustained by NFATc2 inhibition. In vivo, tissue-specific inhibition of Pim1 by nebulized siRNA reverses monocrotaline-induced PAH in rats, whereas Pim1 knockout mice are resistant to PAH development. CONCLUSION: We demonstrated for the first time that inhibition of the inappropriate activation of STAT3/Pim1 axis is a novel, specific, and attractive therapeutic strategy to reverse PAH.

Dehydroepiandrosterone reverses chronic hypoxia/reoxygenation-induced right ventricular dysfunction in rats.

Dehydroepiandrosterone (DHEA) prevents chronic hypoxia-induced pulmonary hypertension and associated right ventricle dysfunction in rats. In this animal model, reoxygenation following hypoxia reverses pulmonary hypertension but not right ventricle dysfunction. We thus studied the effect of DHEA on the right ventricle after reoxygenation, i.e. after a normoxic recovery phase secondary to chronic hypoxia in rats. Right ventricle function was assessed in vivo by Doppler echocardiography and in vitro by the isolated perfused heart technique in three groups of animals: control, recovery (21 days of hypoxia followed by 21 days of normoxia) and recovery DHEA (30 mg · kg(-1) every 2 days during the recovery phase). Right ventricle tissue was assessed by optical and electron microscopy. DHEA abolished right ventricle diastolic dysfunction, as the echographic E wave remained close to that of controls (mean ± SD 76.5 ± 2.4 and 79.7 ± 1.7 cm · s(-1), respectively), whereas it was diminished to 40.3 ± 3.7 in the recovery group. DHEA also abolished right ventricle systolic dysfunction, as shown by the inhibition of the increase in the slope of the pressure-volume curve in isolated heart. The DHEA effect was related to cardiac myocytes proliferation. In conclusion, DHEA prevents right ventricle dysfunction in this animal model by preventing cardiomyocyte alteration.

Nasal high-frequency percussive ventilation vs nasal continuous positive airway pressure in newborn infants respiratory distress: A cross over clinical trial.

OBJECTIVE: To determine if nasal high-frequency percussive ventilation (nHFPV) to manage neonatal respiratory distress decreases the regional cerebral oxygen saturation (rScO2 ) compared to nasal continous positive airway pressure (nCPAP). STUDY DESIGN: A prospective, randomized, monocentric, open-label, noninferiority crossover trial. Newborns of gestational age (GA) ≥ 33 weeks exhibiting persistent respiratory distress after 10 minutes of life were treated with nHFPV and nCPAP, in succession and in random order. The primary endpoint was the mean rScO2 , as revealed by near-infrared spectroscopy (NIRS). RESULTS: Forty-nine newborns were randomized; the mean GA and birth weight was 36.4 ± 1.9 weeks and 2718 ± 497 g. The mean rScO2 difference during the last 5 minutes of each ventilation mode (nHFPV minus nCPAP) was -0.7 ± 5.4% (95% confidence interval (CI) -2.25; 0.95%). CONCLUSION: In our study on newborns of GA ≥33 weeks treated for respiratory distress, cerebral oxygenation via nHFPV was not inferior to nCPAP.

Toward the integration of global longitudinal strain analysis in the assessment of neonatal aortic coarctation? A preliminary study.

BACKGROUND: Coarctation of the aorta (CoA) is still challenging to diagnose in neonates with patent ductus arteriosus (PDA). Speckle tracking echocardiography allows reliable analysis of myocardial deformation in newborns and seems to provide important insides into regional changes in patients with left ventricular (LV) outflow tract obstruction. AIMS: To assess the interest of LV global longitudinal strain (GLS) measurement for predicting CoA in neonates with PDA and prenatal suspicion. METHODS: Prospective single-center study. Twenty-two newborns with prenatal suspicion of CoA were included. All newborns were evaluated in the first 12 hours of life. To assess the feasibility and the reproducibility of GLS, 14 healthy full-term newborns with PDA (group 3) were screened. CoA was diagnosed when DA closed, according to usual echocardiographic criteria. RESULTS: Six neonates developed CoA after DA closure (group 1) whereas 16 did not (group 2). Mean gestational age and birth weight were not different between the groups. GLS measurements were possible in 100%. Intra- and inter-observer variability of strain measurements was acceptable. GLS values were significantly lower in neonates who developed CoA (P=0.015). To predict CoA, cut-off value of -17.42% gave the best compromise for sensitivity (83%) and specificity (72%). Aortic arch dimensions were modestly correlated with strain values. The presence of a bicuspid aortic valve was not associated with significant lower GLS values. CONCLUSION: LV GLS analysis is a feasible and reproducible echocardiographic technique in newborns with PDA. Newborns who will develop CoA seem to have lower values of GLS than healthy neonates. Further studies are needed to confirm these preliminary results.

Altered vasoreactivity in neonatal rats with pulmonary hypertension associated with bronchopulmonary dysplasia: Implication of both eNOS phosphorylation and calcium signaling.

Bronchopulmonary dysplasia (BPD) consists of an arrest of pulmonary vascular and alveolar growth, with persistent hypoplasia of the pulmonary microvasculature and alveolar simplification. In 25 to 40% of the cases, BPD is complicated by pulmonary hypertension (BPD-PH) that significantly increases the risk of morbidity. In vivo studies suggest that increased pulmonary vascular tone could contribute to late PH in BPD. Nevertheless, an alteration in vasoreactivity as well as the mechanisms involved remain to be confirmed. The purpose of this study was thus to assess changes in pulmonary vascular reactivity in a murine model of BPD-PH. Newborn Wistar rats were exposed to either room air (normoxia) or 90% O2 (hyperoxia) for 14 days. Exposure to hyperoxia induced the well-known features of BPD-PH such as elevated right ventricular systolic pressure, right ventricular hypertrophy, pulmonary vascular remodeling and decreased pulmonary vascular density. Intrapulmonary arteries from hyperoxic pups showed decreased endothelium-dependent relaxation to acetylcholine without any alteration of relaxation to the NO-donor sodium nitroprusside. This functional alteration was associated with a decrease of lung eNOS phosphorylation at the Ser1177 activating site. In pups exposed to hyperoxia, serotonin and phenylephrine induced exacerbated contractile responses of intrapulmonary arteries as well as intracellular calcium response in pulmonary arterial smooth muscle cells (PASMC). Moreover, the amplitude of the store-operated Ca2+ entry (SOCE), induced by store depletion using a SERCA inhibitor, was significantly greater in PASMC from hyperoxic pups. Altogether, hyperoxia-induced BPD-PH alters the pulmonary arterial reactivity, with effects on both endothelial and smooth muscle functions. Reduced activating eNOS phosphorylation and enhanced Ca2+ signaling likely account for alterations of pulmonary arterial reactivity.

Increased relaxation of immature airways to beta2-adrenoceptor agonists is related to attenuated expression of postjunctional smooth muscle muscarinic M2 receptors.

Spontaneous or agonist-induced contraction of airway smooth muscle can be observed very early in fetal life, thus explaining the possible occurrence of bronchospasm in very low birth weight infants within the first days of life. In an attempt to better manage such bronchospasms, the aim of the present study was to investigate the age-specific modifications in airway smooth muscle relaxation to beta2-agonists and muscarinic antagonists using a combination of functional and molecular techniques. In the rat, isometric relaxation to the beta2-agonist salbutamol was examined in tracheae; we also examined muscarinic receptor expression (M2R and M3R mRNA levels) in airway smooth muscle by immunochemistry, Western blotting, and real-time PCR. Compared with adults, salbutamol-induced relaxation was twofold greater in immature rat isolated tracheae preconstricted by carbachol. This effect was associated with a lower expression of M2R in the smooth muscle of immature animals (sixfold and almost twofold as assessed by immunochemistry and Western blotting, respectively). Real-time PCR data indicate that changes in M2R expression according to age occurred at a posttranscriptional level. In adult airways, there was a significantly greater functional efficacy of M2R blockade by methoctramine compared with that shown in immature rats. Because of the limited availability of human neonate lung tissue, only the molecular part of the study was performed, and we observed a qualitatively similar effect, i.e., a lower M2R expression in the neonatal airway smooth muscle, although this was quantitatively smaller. We conclude that beta2-agonist-induced relaxation is enhanced in immature compared with adult airways as a result of greater postjunctional M2R expression in adult airway smooth muscle. This finding may be of importance in the clinical management of bronchoconstriction in neonates.

Role of DHEA in cardiovascular diseases.

Dehydroepiandrosterone (DHEA) is a steroid hormone derived from cholesterol synthesized by the adrenal glands. DHEA and its 3ß-sulphate ester (DHEA-S) are the most abundant circulating steroid hormones. In human, there is a clear age-related decline in serum DHEA and DHEA-S and this has suggested that a relative deficiency in these steroids may be causally related to the development of a series of diseases associated with aging including cardiovascular diseases (CVD). This commentary aims to highlight the action of DHEA in CVD and its beneficial effect in therapy. We thus discuss the possible impact of serum DHEA decline and DHEA supplementation in diseases such as hypertension, coronary artery disease and atherosclerosis. More specifically, we provide evidence for a beneficial action of DHEA in the main disease of the pulmonary circulation: pulmonary hypertension. We also examine the potential cellular mechanism of action of DHEA in terms of receptors (membrane/nuclear) and associated signaling pathways (ion channels, calcium signaling, PI3K/AKT/eNos pathway, cGMP, RhoA/RhoK pathway). We show that DHEA acts as an anti-remodeling and vasorelaxant drug. Since it is a well-tolerated and inexpensive drug, DHEA may prove to be a valuable molecule in CVD but it deserves further studies both at the molecular level and in large clinical trials.

Effect of high-frequency oscillation and percussion versus conventional ventilation in a piglet model of meconium aspiration.

BACKGROUND: Meconium aspiration syndrome (MAS) remains a frequent cause of morbidity and mortality in term newborns. Our objective was to compare two modes of high-frequency ventilation, high-frequency oscillation (HFOV), and high-frequency percussive ventilation (HFPV) with conventional mechanical ventilation (CMV) in a piglet model of MAS. METHODS: Fifteen newborn piglets were anesthetized, paralyzed, and intubated. Following the instillation of a 3 ml/kg solution of meconium diluted to 30%, the piglets were randomized to one of three groups: high-frequency oscillation (HFOV; Sensormedics®), HFPV (Percussionaire®), or CMV (Siemens®). Animals were ventilated for 6 hr to maintain arterial blood gases within a normal range, that is, pH 7.35-7.45, PaO(2) 10-16 kPa, PaCO(2) 4-6.6 kPa. Arterial blood gas measurements, dynCrs and dynRrs, ventilator settings, and vital signs (heart rate, arterial blood pressure, transcutaneous pulse oxygen saturation, and temperature) were collected at 30, 60, 90, 120, 180, 240, 300, and 360 min after meconium instillation. Oxygenation index (OI) ([(fraction of inspired oxygen)(mean airway pressure)(100)]/PaO(2) ), mean airway pressure, dynamic lung function, secretions cleared and histological alterations were studied in all groups. RESULTS: Mean airway pressure and OI were significantly lower in the CV and HFPV groups compared to the HFOV group (P < 0.05). There was no significant difference between groups regarding lung function, amount of secretions and histological alterations. CONCLUSION: In our model of MAS in piglets, whilst effective gas exchange with a lower mean airway pressure was possible with both CMV and HFPV compared with HFOV there was no apparent difference in lung histology or secretions.

Dehydroepiandrosterone (DHEA) improves pulmonary hypertension in chronic obstructive pulmonary disease (COPD): a pilot study.

OBJECTIVES: It was previously shown that dehydroepiandrosterone (DHEA) reverses chronic hypoxia-induced pulmonary hypertension (PH) in rats, but whether DHEA can improve the clinical and hemodynamic status of patients with PH associated to chronic obstructive pulmonary disease (PH-COPD) has not been studied whereas it is a very severe poorly treated disease. PATIENTS AND METHODS: Eight patients with PH-COPD were treated with DHEA (200mg daily orally) for 3 months. The primary end-point was the change in the 6-minute walk test (6-MWT) distance. Secondary end-points included pulmonary hemodynamics, lung function tests and tolerance of treatment. RESULTS: The 6-MWT increased in all cases, from 333m (median [IQR]) (257; 378) to 390m (362; 440) (P<0.05). Mean pulmonary artery pressure decreased from 26mmHg (25; 27) to 21.5mmHg (20; 25) (P<0.05) and pulmonary vascular resistance from 4.2UI (3.5; 4.4) to 2.6UI (2.5; 3.8) (P<0.05). The carbon monoxide diffusing capacity of the lung (DLCO % predicted) increased significantly from 27.4% (20.1; 29.3) to 36.4% (14.6; 39.6) (P<0.05). DHEA treatment did not change respiratory parameters of gas exchange and the 200mg per day of DHEA used was perfectly tolerated with no side effect reported. CONCLUSION: DHEA treatment significantly improves 6-MWT distance, pulmonary hemodynamics and DLCO of patients with PH-COPD, without worsening gas exchange, as do other pharmacological treatments of PH (trial registration NCT00581087).

Nasal high frequency percussive ventilation versus nasal continuous positive airway pressure in transient tachypnea of the newborn: a pilot randomized controlled trial (NCT00556738).

OBJECTIVE: To determine whether nasal high frequency percussive ventilation (NHFPV) would decrease duration of transient tachypnea of the newborn (TTN) compared to nasal continuous positive airway pressure (NCPAP) in newborn infants. METHODS: A prospective, unmasked, randomized, controlled clinical trial was conducted in 46 eligible newborn infants who were hospitalized for TTN in the University Hospital of Bordeaux (France) between 2007 and 2009. Infants born by cesarian section ≥37 GA, ≥2,000 g with diagnosis of TTN and with a transcutaneous saturation <90% at 20 min after birth were eligible. Infants were randomized to either NHFPV or NCPAP. The primary endpoint was a reduction of the duration of TTN. Secondary endpoints were the duration of oxygen therapy and the minimal level required to obtain a saturation between 90% and 96% integrated into an index which included a time factor: [(FiO2 -21)/time of O2 therapy]. RESULTS: In the NHFPV group the duration of TTN was half the time of NCPAP group (105 min ± 20 and 377 min ± 150, respectively; P < 0.0001). There was a significant decrease in duration of oxygen supplementation in the NHFPV group (6.3 min ± 3.3) compared to the NCPAP group (19.1 min ± 8.1; P < 0.001), and a significant decrease in level of oxygen supplementation [(FiO2 -0.21)/time of O2 therapy] in the NHFPV group (0.29 min(-1) ± 0.16) compared to the NCPAP group (0.46 min(-1) ± 0.50; P < 0.001). There was no complication and NHFPV was as well tolerated as NCPAP. CONCLUSION: NHFPV is well tolerated and more effective than NCPAP in treatment of TTN. NHFPV might be a novel and safe tool to manage TTN. Pediatr Pulmonol.

Dehydroepiandrosterone: A new treatment for vascular remodeling diseases including pulmonary arterial hypertension.

This review describes the cellular and molecular mechanism heterogeneity of dehydroepiandrosterone (DHEA) and its putative therapeutic role in vascular remodeling diseases such as pulmonary artery hypertension (PAH). PAH is characterized by enhanced pulmonary artery smooth muscle cell (PASMC) proliferation, constriction and resistance to apoptosis, all of which contribute to increase the pulmonary artery wall thickness, resistance and therefore pressure. The etiology of PAH remains elusive. Nonetheless, the implications of endothelial dysfunction (decreased nitric oxide generation and increased endothelin production etc), PASMC K(+) channel/mitochondrial axis disruption (voltage-gated K(+) channel (Kv1.5) downregulation and mitochondrial membrane potential hyperpolarization) and the activation of survival pathways such as PI3K/Akt are now accepted. Therefore, a drug able to target all of these abnormalities would be of a great therapeutic interest for the treatment of PAH. We and others have demonstrated that DHEA, a clinically available drug with a low adverse effect profile, is able to achieve these effects. In several animal models of vascular remodeling diseases such as PAH, DHEA has been demonstrated to be a good anti-proliferative and pro-apoptotic drug, decreasing vascular remodeling, and a potent vasodilator. A better understanding of the DHEA mechanisms of action may allow the development of new and better therapies to treat vascular remodeling diseases such as pulmonary hypertension.

Chronic hypoxia induces nonreversible right ventricle dysfunction and dysplasia in rats.

The purpose of this study was to evaluate the reversibility of right ventricular (RV) remodelling after pulmonary artery hypertension (PAHT) secondary to 3 wk of hypobaric hypoxia. A group of 10 adult male Wistar rats were studied and were the following: control normoxic (C), after 3 wk of chronic hypoxia (CH), and after 3 wk of exposure to hypoxia followed by 3 wk of normoxia recovery (N-RE). Mean pulmonary artery pressure was 11 +/- 2 mmHg in the C group, 35 +/- 2 mmHg in the CH group, and 14 +/- 3 mmHg in the N-RE group. RV function was assessed by echocardiography. In the CH group, the pulmonary flow measured in Doppler mode depicted a midsystolic notch and a decrease of the pulmonary acceleration time compared with control [17 +/- 1 vs. 34 +/- 1 ms (n = 10), respectively; P < 0.05]. RV thickening measured in M-mode was apparent in the CH group compared with the control group [2.84 +/- 0.40 vs. 1.73 +/- 0.26 mm (n = 10), P < 0.05]. In the N-RE group, the RV wall was significantly thinner compared with the CH group [1.56 +/- 0.08 vs. 1.73 +/- 0.26 mm (n = 10), P < 0.05]. The calculated RV diameter shortness fraction was not different between the CH group and C group (34 +/- 4.2% vs. 36 +/- 2.8%) but decreased in the N-RE group [20 +/- 2.4% (n = 10), P < 0.01]. The E-to-A wave ratio on the tricuspid Doppler inflow was significantly lower in the CH group and N-RE group compared with the C group [0.70 +/- 0.8 and 0.72 +/- 0.1 vs. 0.88 +/- 0.2 (n = 10), respectively; P < 0.05]. In the isolated perfused heart using the Langendorff method, RV compliance was increased in the CH group and decreased in the N-RE group. In the N-RE group, fibrous bands with metaplasia were observed on histological sections of the RV free wall. We conclude that PAHT induces nonreversible RV dysfunction with dysplasia.

Dehydroepiandrosterone (DHEA) prevents and reverses chronic hypoxic pulmonary hypertension.

Pulmonary artery (PA) hypertension was studied in a chronic hypoxic-pulmonary hypertension model (7-21 days) in the rat. Increase in PA pressure (measured by catheterism), cardiac right ventricle hypertrophy (determined by echocardiography), and PA remodeling (evaluated by histology) were almost entirely prevented after oral dehydroepiandrosterone (DHEA) administration (30 mg/kg every alternate day). Furthermore, in hypertensive rats, oral administration, or intravascular injection (into the jugular vein) of DHEA rapidly decreased PA hypertension. In PA smooth muscle cells, DHEA reduced the level of intracellular calcium (measured by microspectrofluorimetry). The effect of DHEA appears to involve a large conductance Ca2+-activated potassium channel (BKCa)-dependent stimulatory mechanism, at both function and expression levels (isometric contraction and Western blot), via a redox-dependent pathway. Voltage-gated potassium (Kv) channels also may be involved because the antagonist 4-amino-pyridine blocked part of the DHEA effect. The possible pathophysiological and therapeutic significance of the results is discussed.