Estrogens and development of pulmonary hypertension: interaction of estradiol metabolism and pulmonary vascular disease

The effects of 17 alpha-estradiol to inhibit inflammation in vitro

Background

17 Alpha-estradiol (17 α-E2) is a natural, non-feminizing stereoisomer of 17 beta-estradiol (17 β-E2). Whereas much is known about the physiological effects of 17 β-E2, much less is known about 17 α-E2. For example, 17 β-E2 exerts anti-inflammatory effects in neurons and adipocytes through binding and activation of estrogen receptor alpha (ERα); however, if 17 α-E2 has similar effects on inflammation is currently unknown.

Methods

To begin to address this, we analyzed the ability of 17 α-E2 and 17 β-E2 to suppress lipopolysaccharide (LPS)-induced inflammation in vitro using embryonic fibroblast cells (MEF) from wild type and total body ERα (ERKO) male and female mice. Additionally, we further probed if there were sex differences with respect to the effects of E2s using primary pre-adipocyte cells from C57BL/6J male and female mice. Also, we probed mechanistically the effects of E2s in fully differentiated 3T3-L1 cells.

Results

Both E2s decreased LPS-induced markers of inflammation Tnf-α and Il-6, and increased the anti-inflammatory markers Il-4 and IL-6 receptor (Il-6ra) in MEF cells. To begin to understand the mechanisms by which both E2’s mediate their anti-inflammatory effects, we probed the role of ERα using two methods. First, we used MEF cells from ERKO mice and found reductions in ERα diminished the ability of 17 α-E2 to suppress Tnf-α in female but not in male cells, demonstrating a sexual dimorphism in regard to the role of ERα to mediate 17 α-E2’s effects. Second, we selectively reduced the expression of ERα in 3T3-L1 cells using siRNA and found reductions in ERα diminished the ability of both E2s to suppress Tnf-α and Il-6 expression. Lastly, to determine the mechanisms by which E2s reduce inflammation, we explored the role of NFκB-p65 and found both E2s decreased NFκB-p65 expression.

Conclusions

In conclusion, we demonstrate for the first time that 17 α-E2, as well as 17 β-E2, suppresses inflammation through their effects on ERα and NFκB-p65.

Electronic supplementary material

The online version of this article (10.1186/s13293-017-0151-9) contains supplementary material, which is available to authorized users.

Anastrozole in Pulmonary Arterial Hypertension. A Randomized, Double-Blind, Placebo-controlled Trial

RATIONALE

The aromatase inhibitor anastrozole blocks the conversion of androgens to estrogen and blunts pulmonary hypertension in animals, but its efficacy in treating patients with pulmonary arterial hypertension (PAH) is unknown.

OBJECTIVES

We aimed to determine the safety and efficacy of anastrozole in PAH.

METHODS

We performed a randomized, double-blind, placebo-controlled trial of anastrozole in patients with PAH who received background therapy at two centers.

MEASUREMENTS AND MAIN RESULTS

A total of 18 patients with PAH were randomized to anastrozole 1 mg or matching placebo in a 2:1 ratio. The two co-primary outcomes were percent change from baseline in 17β-estradiol levels (E2) and tricuspid annular plane systolic excursion (TAPSE) at 3 months. Anastrozole significantly reduced E2 levels compared with placebo (percent change: -40%; interquartile range [IQR], -61 to -26% vs. -4%; IQR, -14 to +4%; P = 0.003), but there was no difference in TAPSE. Anastrozole significantly increased the 6-minute-walk distance (median change = +26 m) compared with placebo (median change = -12 m) (median percent change: anastrozole group, 8%; IQR, 2 to 17% vs. placebo -2%; IQR, -7 to +1%; P = 0.042). Anastrozole had no effect on circulating biomarkers, functional class, or health-related quality of life. There was no difference in adverse events.

CONCLUSIONS

Anastrozole significantly reduced E2 levels in patients with PAH but had no effect on TAPSE. Anastrozole was safe, well tolerated, and improved 6-minute-walk distance in this small "proof-of-principle" study. Larger and longer phase II clinical trials of anastrozole may be warranted in patients with PAH. Clinical trial registered with www.clinicaltrials.gov (NCT 1545336).

Higher Estradiol and Lower Dehydroepiandrosterone-Sulfate Levels Are Associated with Pulmonary Arterial Hypertension in Men

RATIONALE

Recent studies have focused on the role of female sex and estradiol (E2) in pulmonary arterial hypertension (PAH), but it is not known whether sex hormones are risk factors for PAH in men.

OBJECTIVES

We performed a case-control study to determine whether hormone levels (E2, dehydroepiandrosterone-sulfate [DHEA-S], and testosterone) are associated with PAH in men.

METHODS

Plasma sex hormone levels in men with idiopathic, heritable, or connective tissue disease-associated PAH were compared with those from age- and body mass index-matched men without clinical cardiovascular disease.

MEASUREMENTS AND MAIN RESULTS

There were 23 cases with PAH (70% had idiopathic PAH, 65% were functional class III/IV) and 67 control subjects. Higher E2 and E2/testosterone levels were associated with the risk of PAH (odds ratio per 1 ln[E2:testosterone], 6.0; 95% confidence interval, 2.2-16.4; P = 0.001), whereas higher levels of DHEA-S were associated with a reduced risk (odds ratio per 1 ln[DHEA-S], 0.1; 95% confidence interval, 0.0-0.3; P = 0.001). E2 and DHEA-S levels were strong predictors of case status (C statistic for both, 0.82) but testosterone was not (C statistic, 0.53). Higher levels of E2 were associated with shorter 6-minute-walk distances (P = 0.03), whereas higher levels of DHEA-S were associated with lower right atrial pressure (P = 0.02) and pulmonary vascular resistance (P = 0.01) in men with PAH.

CONCLUSIONS

Higher levels of E2 and lower levels of DHEA-S were associated with PAH in men. Sex-based differences in sex hormone processing and signaling may contribute to unique phenotypes in pulmonary vascular disease.

2-Methoxyestradiol protects against IgG immune complex-induced acute lung injury by blocking NF-κB and CCAAT/enhancer-binding protein β activities

Increasing evidences indicate that 2-Methoxyestradiol (2ME2) plays an essential role in protecting against inflammatory responses. However, its effect on IgG immune complex (IC)-induced acute lung injury (ALI) remains enigmatic. In the study, by using i.p. administration of 2ME2, we evaluated its influence on IgG IC-induced pulmonary injury in mice. We found that during IgG IC-induced ALI, mice treated by 2ME2 displayed a substantial decrease in vascular permeability and neutrophil influx (represented by myeloperoxidase activity) when compared with their counterparts receiving vehicle treatment. Furthermore, 2ME2 treatment significantly decreased pro-inflammatory mediator production and inflammatory cell, especially neutrophil accumulation in bronchoalveolar lavage fluids (BALFs) upon IgG IC stimulation. In vitro, IgG IC-triggered inflammatory mediator production was markedly down-regulated by 2ME2 in macrophages. Moreover, we verified that the activation of the transcription factors, NF-κB and CCAAT/enhancer-binding protein (C/EBP) β, were inhibited by 2ME2 in IgG IC-challenged macrophages. We demonstrated that alleviation of NF-κB-dependent transcription might be associated with reduced phosphorylation of NF-κB p65, and reduction of C/EBP activation was directly linked to its expression. In addition, we discovered that IgG IC-stimulated phosphorylation of both p38 MAPK and ERK1/2 was alleviated by 2ME2. These data indicated a novel strategy for blockade of IgG IC-induced inflammatory activities.

Influence of gender on right ventricle adaptation to endurance exercise: an ultrasound two-dimensional speckle-tracking stress study

BACKGROUND

Characteristic right ventricle (RV) remodelling is related to endurance exercise in male athletes (MAs), but data in female athletes (FAs) are scarce. Our aim was to evaluate sex-related influence on exercise-induced RV remodelling and on RV performance during exercise.

METHODS

Forty endurance athletes (>10 training hours/week, 50% female) and 40 age-matched controls (<3 h moderate exercise/week, 50% female) were included. Echocardiography was performed at rest and at maximum cycle-ergometer effort. Both ventricles were analysed by standard and speckle-tracking echocardiography.

RESULTS

Endurance training induced similar structural and functional cardiac remodelling in MAs and FAs, characterized by bi-ventricular dilatation [~34%, left ventricle (LV); 29%, RV] and normal bi-ventricular function. However, males had larger RV size (p < 0.01), compared to females: RV end-diastolic area (cm²/m²): 15.6 ± 2.2 vs 11.6 ± 1.7 in athletes; 12.2 ± 2.7 vs 8.6 ± 1.6 in controls, respectively, and lower bi-ventricular deformation (RV global longitudinal strain (GLS) (%): -24.0 ± 3.6 vs -29.2 ± 3.1 in athletes; -24.9 ± 2.5 vs -30.0 ± 1.9 in controls, and LVGLS: -17.5 ± 1.4 vs -21.9 ± 1.9 in athletes; -18.7 ± 1.2 vs -22.5 ± 1.5 in controls, respectively, p < 0.01). During exercise, the increase in LV function was positively correlated (p < 0.01) with increased cardiac output (∆%LV ejection fraction, r = +0.46 and ∆%LVGLS, r = +0.36). Improvement in RV performance was blunted at high workloads, especially in MAs.

CONCLUSION

Long-term endurance training induced similar bi-ventricular remodelling in MAs and FAs. Independently of training load, males had larger RV size and lower bi-ventricular deformation. Improvement in RV performance during exercise was blunted at high workloads, especially in MAs. The potential mechanisms underlying these findings warrant further investigation.

Sex and strain-based inflammatory response to repeated tobacco smoke exposure in spontaneously hypertensive and Wistar Kyoto rats

CONTEXT

Approximately four million people die every year from chronic obstructive pulmonary disease (COPD), with more than 80% of the cases attributed to smoking.

OBJECT

The purpose of this study was to examine the rat strain and sex-related differences and the extended tobacco smoke exposure to induce lung injury and inflammation with the goal of finding a suitable rodent model to study COPD.

METHODS

Male and female spontaneously hypertensive (SH) and male Wistar Kyoto (WKY) rats were exposed to filtered air (FA) or to tobacco smoke (TS: 90 mg/m3 particulate concentration) for 6 h/day, three days/week for 4 or 12 weeks.

RESULTS

Male SH rats demonstrated an enhanced, persistent inflammatory response compared to female SH and male WKY rats with extended TS exposure. Following four weeks of TS exposure, male SH rats had significantly increased total leukocytes and macrophage numbers, levels of TNF-alpha and elevated lactate dehydrogenase activity in bronchoalveolar lavage fluid compared with female SH, male WKY rats and corresponding controls. After 12 weeks of TS exposure, male SH rats continued to show significant increase in inflammatory cells and TNF-alpha, as well as IL-6 mRNA lung expression. In addition, the alveolar airspace of male SH rats exposed to TS was significantly enlarged compared to their FA controls, female SH and WKY rats.

CONCLUSION

The male SH rat demonstrates greater cellular, inflammatory and structural changes highly reminiscent of COPD compared to female SH and male WKY rats, suggesting that the male SH rat is an optimal rodent model to study COPD.

Resveratrol alleviate hypoxic pulmonary hypertension via anti-inflammation and anti-oxidant pathways in rats

Resveratrol, a plant-derived polyphenolic compound and a phytoestrogen, was shown to possess multiple protective effects including anti-inflammatory response and anti-oxidative stress. Hypoxic pulmonary hypertension (HPH) is a progressive disease characterized by sustained vascular resistance and marked pulmonary vascular remodeling. The exact mechanisms of HPH are still unclear, but inflammatory response and oxidative stress was demonstrated to participate in the progression of HPH. The present study was designed to investigate the effects of resveratrol on HPH development. Sprague-Dawley rats were challenged by hypoxia exposure for 28 days to mimic hypoxic pulmonary hypertension along with treating resveratrol (40 mg/kg/day). Hemodynamic and pulmonary pathomorphology data were then obtained, and the anti-proliferation effect of resveratrol was determined by in vitro assays. The anti-inflammation and anti-oxidative effects of resveratrol were investigated in vivo and in vitro. The present study showed that resveratrol treatment alleviated right ventricular systolic pressure and pulmonary arterial remodeling induced by hypoxia. In vitro experiments showed that resveratrol notably inhibited proliferation of pulmonary arterial smooth muscle cells in an ER-independent manner. Data showed that resveratrol administration inhibited HIF-1 α expression in vivo and in vitro, suppressed inflammatory cells infiltration around the pulmonary arteries, and decreased ROS production induced by hypoxia in PAMSCs. The inflammatory cytokines' mRNA levels of tumor necrosis factor α, interleukin 6, and interleukin 1β were all suppressed by resveratrol treatment. The in vitro assays showed that resveratrol inhibited the expression of HIF-1 α via suppressing the MAPK/ERK1 and PI3K/AKT pathways. The antioxidant axis of Nuclear factor erythroid-2 related factor 2/ Thioredoxin 1 (Nrf-2/Trx-1) was up-regulated both in lung tissues and in cultured PASMCs. In general, the current study demonstrated that resveratrol may prevent pulmonary hypertension through its anti-proliferation, anti-inflammation and antioxidant effects. Hence, the present data may offer novel targets and promising pharmacological perspective for treating hypoxic pulmonary hypertension.

Novel signaling pathways in pulmonary arterial hypertension (2015 Grover Conference Series)

The proliferative endothelial and smooth muscle cell phenotype, inflammation, and pulmonary vascular remodeling are prominent features of pulmonary arterial hypertension (PAH). Mutations in bone morphogenetic protein type 2 receptor (BMPR2) have been identified as the most common genetic cause of PAH and females with BMPR2 mutations are 2.5 times as likely to develop heritable forms of PAH than males. Higher levels of estrogen have also been observed in males with PAH, implicating sex hormones in PAH pathogenesis. Recently, the estrogen metabolite 16α-OHE1 (hydroxyestrone) was implicated in the regulation of miR29, a microRNA involved in modulating energy metabolism. In females, decreased miR96 enhances serotonin's effect by upregulating the 5-hydroxytryptamine 1B (5HT1B) receptor. Because PAH is characterized as a quasi-malignant disease, likely due to BMPR2 loss of function, altered signaling pathways that sustain this cancer-like phenotype are being explored. Extracellular signal-regulated kinases 1 and 2 and p38 mitogen-activated protein kinases (MAPKs) play a critical role in proliferation and cell motility, and dysregulated MAPK signaling is observed in various experimental models of PAH. Wnt signaling pathways preserve pulmonary vascular homeostasis, and dysregulation of this pathway could contribute to limited vascular regeneration in response to injury. In this review, we take a closer look at sex, sex hormones, and the interplay between sex hormones and microRNA regulation. We also focus on MAPK and Wnt signaling pathways in the emergence of a proproliferative, antiapoptotic endothelial phenotype, which then orchestrates an angioproliferative process of vascular remodeling, with the hope of developing novel therapies that could reverse the phenotype.

Nicotinamide Adenine Dinucleotide Phosphate Oxidase-Mediated Redox Signaling and Vascular Remodeling by 16α-Hydroxyestrone in Human Pulmonary Artery Cells: Implications in Pulmonary Arterial Hypertension

Estrogen and oxidative stress have been implicated in pulmonary arterial hypertension (PAH). Mechanisms linking these systems are elusive. We hypothesized that estrogen metabolite, 16α-hydroxyestrone (16αOHE1), stimulates nicotinamide adenine dinucleotide phosphate oxidase (Nox)-induced reactive oxygen species (ROS) generation and proliferative responses in human pulmonary artery smooth muscle cells (hPASMCs) and that in PAH aberrant growth signaling promotes vascular remodeling. The pathophysiological significance of estrogen-Nox-dependent processes was studied in female Nox1(-/-) and Nox4(-/-) mice with PAH. PASMCs from control subjects (control hPASMCs) and PAH patients (PAH-hPASMCs) were exposed to estrogen and 16αOHE1 in the presence/absence of inhibitors of Nox, cytochrome P450 1B1, and estrogen receptors. Estrogen, through estrogen receptor-α, increased Nox-derived ROS and redox-sensitive growth in hPASMCs, with greater effects in PAH-hPASMCs versus control hPASMCs. Estrogen effects were inhibited by cytochrome P450 1B1 blockade. 16αOHE1 stimulated transient ROS production in hPASMCs, with sustained responses in PAH-hPASMCs. Basal expression of Nox1/Nox4 was potentiated in PAH-hPASMCs. In hPASMCs, 16αOHE1 increased Nox1 expression, stimulated irreversible oxidation of protein tyrosine phosphatases, decreased nuclear factor erythroid-related factor 2 activity and expression of nuclear factor erythroid-related factor 2-regulated antioxidant genes, and promoted proliferation. This was further amplified in PAH-hPASMCs. Nox1(-/-) but not Nox4(-/-) mice were protected against PAH and vascular remodeling. Our findings demonstrate that in PAH-hPASMCs, 16αOHE1 stimulates redox-sensitive cell growth primarily through Nox1. Supporting this, in vivo studies exhibited protection against pulmonary hypertension and remodeling in Nox1(-/-) mice. This study provides new insights through Nox1/ROS and nuclear factor erythroid-related factor 2 whereby 16αOHE1 influences hPASMC function, which when upregulated may contribute to vascular injury in PAH, particularly important in women.

Metformin Reverses Development of Pulmonary Hypertension via Aromatase Inhibition

Females are more susceptible to pulmonary arterial hypertension than males, although the reasons remain unclear. The hypoglycemic drug, metformin, is reported to have multiple actions, including the inhibition of aromatase and stimulation of AMP-activated protein kinase. Inhibition of aromatase using anastrazole is protective in experimental pulmonary hypertension but whether metformin attenuates pulmonary hypertension through this mechanism remains unknown. We investigated whether metformin affected aromatase activity and if it could reduce the development of pulmonary hypertension in the sugen 5416/hypoxic rat model. We also investigated its influence on proliferation in human pulmonary arterial smooth muscle cells. Metformin reversed right ventricular systolic pressure, right ventricular hypertrophy, and decreased pulmonary vascular remodeling in the rat. Furthermore, metformin increased rat lung AMP-activated protein kinase signaling, decreased lung and circulating estrogen levels, levels of aromatase, the estrogen metabolizing enzyme; cytochrome P450 1B1 and its transcription factor; the aryl hydrocarbon receptor. In human pulmonary arterial smooth muscle cells, metformin decreased proliferation and decreased estrogen synthesis by decreasing aromatase activity through the PII promoter site of Cyp19a1 . Thus, we report for the first time that metformin can reverse pulmonary hypertension through inhibition of aromatase and estrogen synthesis in a manner likely to be mediated by AMP-activated protein kinase.

Sex and menopause differences in response to tadalafil: 6-minute walk distance and time to clinical worsening

Pulmonary arterial hypertension (PAH) is a female-predominant disease, but there are little data on treatment response by sex and menopausal status. In this retrospective analysis of the Pulmonary Arterial Hypertension and Response to Tadalafil (PHIRST) randomized clinical trial, we assessed treatment response between the sexes by examining change in 6-minute walk distance (6MWD) and time to clinical worsening (TCW). We examined the effect of menopausal status on the same treatment measures. 6MWD was recorded before and after 16 weeks of treatment with tadalafil or placebo in the PHIRST study cohort of 340 subjects (264 females, 76 males). A univariate analysis was used to assess the effect of sex on change in 6MWD and TCW. Multivariate linear regression and Cox proportional hazards models were built for 6MWD and TCW, respectively. Women were subdivided by age as a surrogate for menopausal status. The linear trend test and the log-rank test were performed on change in 6MWD and TCW by age. For tadalafil-treated patients, a significant difference in change in 6MWD by sex (mean: 48.6 m for males vs. 34.7 m for females; P = 0.01) was found, but it was not significant in multivariate analysis (P = 0.08). There was a trend toward a female age-dependent effect in change in 6MWD; the premenopausal group showed the greatest improvement. A significant sex- or age-dependent effect on TCW was not present. In conclusion, this retrospective analysis of the PHIRST trial suggests that men and premenopausal women may experience greater functional improvement when treated with tadalafil than older women, but there was no consistent sex or menopausal effect on TCW.

Sex Differences in Immunology: More Severe Development of Experimental Pulmonary Hypertension in Male Rats Exposed to Vascular Endothelial Growth Factor Receptor Blockade

Background. The epidemiology of pulmonary hypertension (PH) is characterized by a female preponderance, whereas males share higher severity of the disease. Objective. To compare the severity of experimental PH between male and female athymic rats. Methods. PH was induced in 11 male and 11 female athymic rats (resp., SU_M and SU_F groups) using an inhibitor of VEGF-receptors I and II, semaxanib (40 mg/kg). After 28 days, right ventricular (RV) remodeling, systolic function, and hemodynamics were measured using echocardiography and a pressure-volume admittance catheter. Morphometric analyses of lung vasculature and RV myocardium were performed. Results. Four weeks after semaxanib injection, RV end-systolic pressure was higher in SU_M than in SU_F. Males developed marked RV enlargement and systolic dysfunction compared to females. Impairment of RV-PA coupling efficiency was observed only in SU_M. The smooth muscle cells of the pulmonary arteries switched from a contractile state to a dedifferentiated state only in males. Conclusions. Female athymic rats were protected against the development of severe PH. RV-PA coupling was preserved in females through limitation of pulmonary artery muscularization. Control of smooth muscle cells plasticity may be a promising therapeutic approach to reverse established vascular remodeling in PH patients.

Statement on pregnancy in pulmonary hypertension from the Pulmonary Vascular Research Institute

Pregnancy outcomes in patients with pulmonary hypertension remain poor despite advanced therapies. Although consensus guidelines recommend against pregnancy in pulmonary hypertension, it may nonetheless occasionally occur. This guideline document sought to discuss the state of knowledge of pregnancy effects on pulmonary vascular disease and to define usual practice in avoidance of pregnancy and pregnancy management. This guideline is based on systematic review of peer-reviewed, published literature identified with MEDLINE. The strength of the literature was graded, and when it was inadequate to support high-level recommendations, consensus-based recommendations were formed according to prespecified criteria. There was no literature that met standards for high-level recommendations for pregnancy management in pulmonary hypertension. We drafted 38 consensus-based recommendations on pregnancy avoidance and management. Further, we identified the current state of knowledge on the effects of sex hormones during pregnancy on the pulmonary vasculature and right heart and suggested areas for future study. There is currently limited evidence-based knowledge about both the basic molecular effects of sex hormones and pregnancy on the pulmonary vasculature and the best practices in contraception and pregnancy management in pulmonary hypertension. We have drafted 38 consensus-based recommendations to guide clinicians in these challenging topics, but further research is needed in this area to define best practices and improve patient outcomes.

The sexual dimorphism associated with pulmonary hypertension corresponds to a fibrotic phenotype

Although female predominance in the development of all types of pulmonary hypertension (PH) is well established, many clinical studies have confirmed that females have better prognosis and higher survival rate than males. There is no clear explanation of why sex influences the pathogenesis and progression of PH. Using a rat angioproliferative model of PH, which closely resembles the primary pathological changes observed in humans, we evaluated the role of sex in the development and progression of PH. Female rats had a more pronounced increase in medial thickness in the small pulmonary arteries. However, the infiltration of small pulmonary arteries by inflammatory cells was found only in male rats, and this corresponded to increased myeloperoxidase activity and abundant adventitial and medial fibrosis that were not present in female rats. Although the level of right ventricle (RV) peak systolic pressure was similar in both groups, the survival rate in male rats was significantly lower. Moreover, male rats presented with a more pronounced increase in RV thickness that correlated with diffuse RV fibrosis and significantly impaired right cardiac function. The reduction in fibrosis in female rats correlated with increased expression of caveolin-1 and reduced endothelial nitric oxide synthase-derived superoxide. We conclude that, in the pathogenesis of PH, female sex is associated with greater remodeling of the pulmonary arteries but greater survival. Conversely, in males, the development of pulmonary and cardiac fibrosis leads to early and severe RV failure, and this may be an important reason for the lower survival rate among males.

Disruption of the cytochrome P-450 1B1 gene exacerbates renal dysfunction and damage associated with angiotensin II-induced hypertension in female mice

Recently, we demonstrated in female mice that protection against ANG II-induced hypertension and associated cardiovascular changes depend on cytochrome P-450 (CYP)1B1. The present study was conducted to determine if Cyp1b1 gene disruption ameliorates renal dysfunction and organ damage associated with ANG II-induced hypertension in female mice. ANG II (700 ng·kg(-1)·min(-1)) infused by miniosmotic pumps for 2 wk in female Cyp1b1(+/+) mice did not alter water consumption, urine output, Na(+) excretion, osmolality, or protein excretion. However, in Cyp1b1(-/-) mice, ANG II infusion significantly increased (P < 0.05) water intake (5.50 ± 0.42 ml/24 h with vehicle vs. 8.80 ± 0.60 ml/24 h with ANG II), urine output (1.44 ± 0.37 ml/24 h with vehicle vs. 4.30 ± 0.37 ml/24 h with ANG II), and urinary Na(+) excretion (0.031 ± 0.016 mmol/24 h with vehicle vs. 0.099 ± 0.010 mmol/24 h with ANG II), decreased osmolality (2,630 ± 79 mosM/kg with vehicle vs. 1,280 ± 205 mosM/kg with ANG II), and caused proteinuria (2.60 ± 0.30 mg/24 h with vehicle vs. 6.96 ± 0.55 mg/24 h with ANG II). Infusion of ANG II caused renal fibrosis, as indicated by an accumulation of renal interstitial α-smooth muscle actin, collagen, and transforming growth factor-β in Cyp1b1(-/-) but not Cyp1b1(+/+) mice. ANG II also increased renal production of ROS and urinary excretion of thiobarburic acid-reactive substances and reduced the activity of antioxidants and urinary excretion of nitrite/nitrate and the 17β-estradiol metabolite 2-methoxyestradiol in Cyp1b1(-/-) but not Cyp1b1(+/+) mice. These data suggest that Cyp1b1 plays a critical role in female mice in protecting against renal dysfunction and end-organ damage associated with ANG II-induced hypertension, in preventing oxidative stress, and in increasing activity of antioxidant systems, most likely via generation of 2-methoxyestradiol from 17β-estradiol.

The association between CYP1A1 genetic polymorphisms and coronary artery disease in the Uygur and Han of China

Background

The cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1) gene is expressed in the vascular endothelium, which metabolizes arachidonic acid into 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs). 20-HETE mediates cardiovascular homeostasis and growth response in vascular smooth muscle cells (VSMCs) as well as the anti-platelet effect. EETs are potent endogenous vasodilators and inhibitors of vascular inflammation. This study assessed the association between human CYP1A1 gene polymorphisms and coronary artery disease (CAD) in the Uygur and Han in China.

Methods

Two independent case–control studies that recruited Han (389 patients with CAD and 411 controls) and Uygur participants (293 patients with CAD and 408 controls) analyzed the relationship between CYP1A1 single nucleotide polymorphisms (SNPs: rs4886605, rs12441817, rs4646422 and rs1048943) and CAD. All patients with CAD and controls were genotyped for the four SNPs of CYP1A1 using TaqMan SNP genotyping assays.

Results

In the Uygur group, the distribution of the dominant model(CC vs CT + TT) of rs4886605 for the total sample and the males was significantly different between CAD patients and control participants (P = 0.001 and P = 0.012, respectively), The difference remained significant after a multivariate adjustment (P = 0.018, P = 0.015, respectively). The rs12441817 was also associated with CAD in a dominant model for all participants (P = 0.003) and men (P = 0.012), and the difference remained significant after a multivariate adjustment (P = 0.016, P = 0.002, respectively). However, we did not observe differences in the Uygur females and Han group with regard to the allele frequency or genotypic distribution of rs4886605 and rs12441817 between patients with CAD and control participants. Patients with CAD did not significantly differ from the control participants with regard to the distributions of rs4646422 and rs1048943 genotypes, the dominant model, the recessive model, or allele frequency in the Han and Uygur groups.

Conclusion

Both rs4886605 and rs12441817 SNPs of the CYP1A1 gene are associated with CAD in the Uygur population of China.

Progress in solving the sex hormone paradox in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a devastating and progressive disease with marked morbidity and mortality. Even though being female represents one of the most powerful risk factors for PAH, multiple questions about the underlying mechanisms remain, and two "estrogen paradoxes" in PAH exist. First, it is puzzling why estrogens have been found to be protective in various animal models of PAH, whereas PAH registries uniformly demonstrate a female susceptibility to the disease. Second, despite the pronounced tendency for the disease to develop in women, female PAH patients exhibit better survival than men. Recent mechanistic studies in classical and in novel animal models of PAH, as well as recent studies in PAH patients, have significantly advanced the field. In particular, it is now accepted that estrogen metabolism and receptor signaling, as well as estrogen interactions with key pathways in PAH development, appear to be potent disease modifiers. A better understanding of these interactions may lead to novel PAH therapies. It is the purpose of this review to 1) review sex hormone synthesis, metabolism, and receptor physiology; 2) assess the context in which sex hormones affect PAH pathogenesis; 3) provide a potential explanation for the observed estrogen paradoxes and gender differences in PAH; and 4) identify knowledge gaps and future research opportunities. Because the majority of published studies investigated 17β-estradiol and/or its metabolites, this review will primarily focus on pulmonary vascular and right ventricular effects of estrogens. Data for other sex hormones will be discussed very briefly.

Clinical aspects of portopulmonary hypertension

Portopulmonary hypertension (PoPH) is an often neglected form of pulmonary hypertension where pulmonary hypertension occurs in the presence of portal hypertension. PoPH is important to diagnose and treat as it may improve the patient's quality of life and improve the outcome after liver transplantation. In this review, we discuss the clinical aspects of PoPH including its pathophysiology, diagnosis, treatment, and prognosis.

The effects of gender difference on monocrotaline-induced pulmonary hypertension in rats

The present study aimed to compare the effect of gender difference on hemodynamic consequences in the development of monocrotaline (MCT)-induced pulmonary hypertension in rat. The effect of antioxidant enzyme systems on the development of pulmonary hypertension mediated by the phytotoxin MCT and the effect of gender on these antioxidant systems were also investigated. For this purpose, the right ventricular pressures (RVPs) and right ventricular/heart weight (HW) ratios were compared between groups and the glutathione (GSH) level and superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) activities were determined in lung and liver tissue samples of rats. RVP and right ventricular/HW ratios significantly increased in the MCT group compared to the control group. In the MCT group, RVP was significantly higher in males than females. MCT-induced pulmonary hypertension resulted in decreased GSH level, decreased GST and SOD activities and increased CAT activity in lung and liver tissues of both male and female rats. In addition, the lung and liver GSH level and GST and SOD levels were higher in female control rats compared to male control rats. The results of the present study, that antioxidant enzyme activities were different between the groups, highlight the possible role of oxidative stress in the pathogenesis of MCT-induced pulmonary hypertension in rats. Moreover, the lower antioxidant defense capacity of male rats than female rats may be considered as a cause of more aggressive course of MCT-induced pulmonary hypertension in males compared to females.

Interaction between bone morphogenetic protein receptor type 2 and estrogenic compounds in pulmonary arterial hypertension

Abstract The majority of heritable pulmonary arterial hypertension (HPAH) cases are associated with mutations in bone morphogenetic protein receptor type 2 (BMPR2). BMPR2 mutation carries about a 20% lifetime risk of PAH development, but penetrance is approximately three times higher in females. Previous studies have shown a correlation between estrogen metabolism and penetrance, with increased levels of the estrogen metabolite 16α-hydroxyestrone (16αOHE) and reduced levels of the metabolite 2-methoxyestrogen (2ME) associated with increased risk of disease. The goal of this study was to determine whether 16αOHE increased and 2ME decreased penetrance of disease in Bmpr2 mutant mice and, if so, by what mechanism. We found that 16αOHE∶2ME ratio was high in male human HPAH patients. Bmpr2 mutant male mice receiving chronic 16αOHE had doubled disease penetrance, associated with reduced cardiac output. 2ME did not have a significant protective effect, either alone or in combination with 16αOHE. In control mice but not in Bmpr2 mutant mice, 16αOHE suppressed bone morphogenetic protein signaling, probably directly through suppression of Bmpr2 protein. Bmpr2 mutant pulmonary microvascular endothelial cells were insensitive to estrogen signaling through canonical pathways, associated with aberrant intracellular localization of estrogen receptor α. In both control and Bmpr2 mutant mice, 16αOHE was associated with suppression of cytokine expression but with increased alternate markers of injury, including alterations in genes related to thrombotic function, angiogenesis, planar polarity, and metabolism. These data support a causal relationship between increased 16αOHE and increased PAH penetrance, with the likely molecular mechanisms including suppression of BMPR2, alterations in estrogen receptor translocation, and induction of vascular injury and insulin resistance-related pathways.

Mass spectrometry evidence for formation of estrogen-homocysteine conjugates: estrogens can regulate homocysteine levels

Homocysteine (HCys), a sulfur-containing amino acid, is formed during the metabolism of methionine. An imbalance between the rate of production and the use of HCys during methionine metabolism can result in an increase in the plasma and urinary levels of HCys. HCys has been shown to be toxic to vascular endothelial cells through several pathways. Many earlier clinical studies have revealed an association between plasma HCys and cardiovascular and other diseases. In contrast, estrogens are suggested to lower the risk of cardiovascular disease. Several studies indicate that estrogen metabolites could be responsible for cardiovascular protection. It has been demonstrated that electrophilic estrogen quinones, E1(E2)-2,3-Q and E1(E2)-3,4-Q, can alkylate DNA as well as form conjugates with glutathione. I hypothesize that estrogen quinones generated in situ by oxidative enzymes, metal ions, or molecular oxygen can interact with HCys to form conjugates. This in turn could lower the levels of toxic HCys as well as quenching the reactive estrogen quinones, resulting in cardiovascular protective effects. To test the feasibility of a protective estrogen-HCys pathway, estrogen quinones were treated with HCys. Tandem mass spectrometry analysis of the assay mixture shows the formation of estrogen-HCys conjugates. Furthermore, incubation of catechol estrogens with myeloperoxidase (MPO) in the presence of HCys resulted in the formation of respective estrogen-HCys conjugates. The identities of estrogen-HCys conjugates in MPO assay extracts were confirmed by comparing them to pure synthesized estrogen-HCys standards. I propose that through conjugation estrogens could chemically regulate HCys levels; moreover these conjugates could be used as potential biomarkers in determining health.

2-methoxyestradiol binding of GPR30 down-regulates angiotensin AT(1) receptor

Controlling angiotensin AT1 receptor function has been shown to be protective for many pathophysiological disorders. Although estrogen metabolite, 2-methoxyestradiol (2ME2) can down-regulate angiotensin AT1 receptor expression independently of nuclear receptors, no specific cellular targets have been identified. This study was focused on identification and validation of a cellular target responsible for 2ME2-mediated angiotensin AT1 receptor down-regulation in a continuously passaged rat liver epithelial cell line. Cell membranes were isolated and used to determine 2ME2 specific binding. Cell membranes exposed to [(3)H]2ME2 showed specific saturable binding, which was found to be pertussis toxin (PTx) sensitive. Under similar conditions, G-protein coupled receptor 30 (GPR30) agonist (G1) and antagonist (G15) inhibited 2ME2 specific binding. In these cells GPR30 was found localized to endoplasmic reticulum (ER) membranes. In intact cells, G1 down-regulated angiotensin AT1 receptor expression and this effect was reversed by G15. Furthermore, 2ME2 mediated activation of epidermal growth factor receptor (EGFR) followed by ERK1/2 phosphorylation, an essential signaling step in angiotensin AT1 receptor down-regulation, was abrogated by G15, suggesting that this signal is GPR30 dependent. Additionally, EGF was found to independently down-regulate angiotensin AT1 receptor in an ERK1/2-dependent manner. In summary, our results demonstrate for the first time that 2ME2 down-regulation of angiotensin AT1 receptor is dependent on ER membrane-associated GRP30. Moreover, this effect is facilitated by GPR30 dependent transactivation of EGFR and ERK1/2 phosphorylation. This study provides further understanding of the physiological significance of 2ME2 and its role in modulating angiotensin AT1 receptor expression.

[Pulmonary arterial hypertension: a flavor of autoimmunity]

It is admitted that autoimmunity results from a combination of risks such as genetic background, environmental triggers, and stochastic events. Pulmonary arterial hypertension (PAH) shares with the so-called prototypic autoimmune diseases, genetic risk factors, female predominance and sex hormone influence, association with other chronic inflammatory and autoimmune diseases, defects in regulatory T cells function, and presence of autoantibodies. Case reports have been published indicating the beneficial effect of some immunosuppressive and anti-inflammatory therapies in PAH, supporting the potential role of immune mechanisms in the pathophysiology of the disease. In this review, we discuss the current knowledge on autoimmune mechanisms operating in PAH, especially mounting a local autoimmune response inside the pulmonary tissue, namely pulmonary lymphoid neogenesis. A better understanding of the role of autoimmunity in pulmonary vascular remodelling may help develop targeted immunomodulatory strategies in PAH.

PSYCHOPHYSIOLOGICAL CHARACTERISTICS OF WOMEN IN DEPENDENCE ON THE OVARIOHORMONAL CYCLE PHASE AND PROGESTERONE ACTIVITY (PART 1)

With the aim to identify the effects of menstrual cycle phase on the cognitive and psycho-emotional characteristics in 78 women aged 18–27 years were studied in a within-subject design Half the subjects began during their follicular phase and half began during their luteal phase (LP). The level of psycho-emotional tension was lowest, but cognitive performance efficiency is a highest in LP that is associated with the highest saliva progesterone level.

A pilot study of the effect of spironolactone therapy on exercise capacity and endothelial dysfunction in pulmonary arterial hypertension: study protocol for a randomized controlled trial

BACKGROUND

Pulmonary arterial hypertension is a rare disorder associated with poor survival. Endothelial dysfunction plays a central role in the pathogenesis and progression of pulmonary arterial hypertension. Inflammation appears to drive this dysfunctional endothelial phenotype, propagating cycles of injury and repair in genetically susceptible patients with idiopathic and disease-associated pulmonary arterial hypertension. Therapy targeting pulmonary vascular inflammation to interrupt cycles of injury and repair and thereby delay or prevent right ventricular failure and death has not been tested. Spironolactone, a mineralocorticoid and androgen receptor antagonist, has been shown to improve endothelial function and reduce inflammation. Current management of patients with pulmonary arterial hypertension and symptoms of right heart failure includes use of mineralocorticoid receptor antagonists for their diuretic and natriuretic effects. We hypothesize that initiating spironolactone therapy at an earlier stage of disease in patients with pulmonary arterial hypertension could provide additional benefits through anti-inflammatory effects and improvements in pulmonary vascular function.

METHODS/DESIGN

Seventy patients with pulmonary arterial hypertension without clinical evidence of right ventricular failure will be enrolled in a randomized, double-blinded, placebo-controlled trial to investigate the effect of early treatment with spironolactone on exercise capacity, clinical worsening and vascular inflammation in vivo. Our primary endpoint is change in placebo-corrected 6-minute walk distance at 24 weeks and the incidence of clinical worsening in the spironolactone group compared to placebo. At a two-sided alpha level of 0.05, we will have at least 84% power to detect an effect size (group mean difference divided by standard deviation) of 0.9 for the difference in the change of 6-minute walk distance from baseline between the two groups. Secondary endpoints include the effect of spironolactone on the change in placebo-corrected maximal oxygen consumption; plasma markers of vascular inflammation and peripheral blood mononuclear cell gene expression profiles; sympathetic nervous system activation, renin-angiotensin-aldosterone system activation and sex hormone metabolism; and right ventricular structure and function using echocardiography and novel high-resolution magnetic resonance imaging-based techniques. Safety and tolerability of spironolactone will be assessed with periodic monitoring for hyperkalemia and renal insufficiency as well as the incidence of drug discontinuation for untoward effects.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01712620.

Gender, sex hormones and pulmonary hypertension

Most subtypes of pulmonary arterial hypertension (PAH) are characterized by a greater susceptibility to disease among females, although females with PAH appear to live longer after diagnosis. While this "estrogen paradoxȍ of enhanced female survival despite increased female susceptibility remains a mystery, recent progress has begun to shed light upon the interplay of sex hormones, the pathogenesis of pulmonary hypertension, and the right ventricular response to stress. For example, emerging data in humans and experimental models suggest that estrogens or differential sex hormone metabolism may modify disease risk among susceptible subjects, and that estrogens may interact with additional local factors such as serotonin to enhance the potentially damaging chronic effects of estrogens on the pulmonary vasculature. Regardless, it remains unclear why not all estrogenic compounds behave equally, nor why estrogens appear to be protective in certain settings but detrimental in others. The contribution of androgens and other compounds, such as dehydroepiandrosterone, to pathogenesis and possibly treatment must be considered as well. In this review, we will discuss the recent understandings on how estrogens, estrogen metabolism, dehydroepiandrosterone, and additional susceptibility factors may all contribute to the pathogenesis or potentially to the treatment of pulmonary hypertension, by evaluating current human, cell-based, and experimental model data.

Factors associated with elevated pulmonary arterial pressure levels on the echocardiographic assessment in patients with prior pulmonary embolism

BACKGROUND

Factors associated with the detection of raised systolic pulmonary artery pressure (sPAP) levels in patients with a prior episode of pulmonary embolism (PE) are not well known.

METHODS

We used the RIETE Registry database to identify factors associated with the finding of sPAP levels ≥50 mm Hg on trans-thoracic echocardiography, in 557 patients with a prior episode of acute, symptomatic PE.

RESULTS

Sixty-two patients (11.1%; 95% CI: 8.72-14.1) had sPAP levels ≥50 mm Hg. These patients were more likely women, older, and more likely had chronic lung disease, heart failure, renal insufficiency or leg varicosities than those with PAP levels <50mm Hg. During the index PE event, they more likely had recent immobility, and more likely presented with hypoxemia, increased sPAP levels, atrial fibrillation, or right bundle branch block. On multivariate analysis, women aged ≥70 years (hazard ratio [HR]: 2.0; 95% CI: 1.0-3.7), chronic heart or chronic lung disease (HR: 2.4; 95% CI: 1.3-4.4), atrial fibrillation at PE presentation (HR: 2.8; 95% CI: 1.3-6.1) or varicose veins (HR: 1.8; 95% CI: 1.0-3.3) were all associated with an increased risk to have raised sPAP levels. Chronic heart disease, varicose veins, and atrial fibrillation were independent predictors in women, while chronic heart disease, atrial fibrillation, a right bundle branch block or an S1Q3T3 pattern on the electrocardiogram were independent predictors in men.

CONCLUSIONS

Women aged ≥70 years more likely had raised sPAP levels than men after a PE episode. Additional variables influencing this risk seem to differ according to gender.

The genetics of pulmonary arterial hypertension in the post-BMPR2 era

Pulmonary arterial hypertension (PAH) is a rapidly progressive and fatal disease for which there is an ever-expanding body of genetic and related pathophysiological information on disease pathogenesis. The most common single culprit gene known is BMPR2, and animal models of the disease in several forms exist. There is a wealth of genetic data regarding modifiers of disease expression, penetrance, and severity. Despite the rapid accumulation of data in the last decade, a complete picture of the molecular pathogenesis of PAH leading to novel therapies is lacking. In this review, we attempt to summarize the current understanding of PAH from the genetic perspective. The most recent PAH demographics are discussed. Heritable PAH in the post-BMPR2 era is examined in detail as the most robust model of PAH genetics in both animal models and human pedigrees. Important downstream molecular pathways and modifiers of disease expression are reviewed in light of what is known about PAH pathogenesis. Current and emerging therapies are examined in light of genetic data. The role of genetic testing in PAH in the post-BMPR2 era is discussed. Finally, directions for future investigations that ideally will fulfill the promise of novel therapeutic or preventive strategies are discussed.

Sex differences and sex steroids in lung health and disease

Sex differences in the biology of different organ systems and the influence of sex hormones in modulating health and disease are increasingly relevant in clinical and research areas. Although work has focused on sex differences and sex hormones in cardiovascular, musculoskeletal, and neuronal systems, there is now increasing clinical evidence for sex differences in incidence, morbidity, and mortality of lung diseases including allergic diseases (such as asthma), chronic obstructive pulmonary disease, pulmonary fibrosis, lung cancer, as well as pulmonary hypertension. Whether such differences are inherent and/or whether sex steroids play a role in modulating these differences is currently under investigation. The purpose of this review is to define sex differences in lung structure/function under normal and specific disease states, with exploration of whether and how sex hormone signaling mechanisms may explain these clinical observations. Focusing on adult age groups, the review addresses the following: 1) inherent sex differences in lung anatomy and physiology; 2) the importance of certain time points in life such as puberty, pregnancy, menopause, and aging; 3) expression and signaling of sex steroid receptors under normal vs. disease states; 4) potential interplay between different sex steroids; 5) the question of whether sex steroids are beneficial or detrimental to the lung; and 6) the potential use of sex steroid signaling as biomarkers and therapeutic avenues in lung diseases. The importance of focusing on sex differences and sex steroids in the lung lies in the increasing incidence of lung diseases in women and the need to address lung diseases across the life span.

Hypoxia stimulates the production of the angiogenesis inhibitor 2-methoxyestradiol by swine granulosa cells

We previously demonstrated the presence of 2-methoxyestradiol (2-ME) in swine follicular fluid. Present study was aimed first of all to investigate if swine granulosa cell produce 2-ME; in addition, we tried to assess a potential effect of hypoxia in modulating 2-ME output. Finally, we explored the effect of 2-ME in an angiogenesis bioassay set up in our lab. Our data show that cultured granulosa cells are able to produce 2-ME; interestingly, the secretion of the hormone appeared to be stimulated by hypoxia. Angiogenesis bioassay points out that 2-ME displays an inhibitory effect on neovascularisation. Therefore our data suggest that 2-ME could be a local effector in determining the fine tuning responsible for follicle angiogenesis. These data deserve special attention since the ovary is a valuable experimental model in angiogenesis research.

Design and validation of an endothelial progenitor cell capture chip and its application in patients with pulmonary arterial hypertension

The number of circulating endothelial progenitor cells (EPCs) inversely correlates with cardiovascular risk and clinical outcome, and thus has been proposed as a valuable biomarker for risk assessment, disease progression, and response to therapy. However, current strategies for isolation of these rare cells are limited to complex, laborious approaches. The goal of this study was the design and validation of a disposable microfluidic platform capable of selectively capturing and enumerating EPCs directly from human whole blood in healthy and diseased subjects, eliminating sample preprocessing. We then applied the "EPC capture chip" clinically and determined EPC numbers in blood from patients with pulmonary arterial hypertension (PAH). Blood was collected in tubes and injected into polymeric microfluidic chips containing microcolumns pre-coated with anti-CD34 antibody. Captured cells were immunofluorescently stained for the expression of stem and endothelial antigens, identified and counted. The EPC capture chip was validated with conventional flow cytometry counts (r = 0.83). The inter- and intra-day reliability of the microfluidic devices was confirmed at different time points in triplicates over 1-5 months. In a cohort of 43 patients with three forms of PAH (idiopathic/heritable, drug-induced, and connective tissue disease), EPC numbers are ≈50% lower in PAH subjects vs. matched controls and inversely related to two potential disease modifiers: body mass index and postmenopausal status. The EPC capture chip (5 × 30 × 0.05 mm(3)) requires only 200 μL of human blood and has the strong potential to serve as a rapid bedside test for the screening and monitoring of patients with PAH and other proliferative cardiovascular, pulmonary, malignant, and neurodegenerative diseases.

Beta-estradiol attenuates hypoxic pulmonary hypertension by stabilizing the expression of p27kip1 in rats

BACKGROUND

Pulmonary vascular structure remodeling (PVSR) is a hallmark of pulmonary hypertension. P27(kip1), one of critical cyclin-dependent kinase inhibitors, has been shown to mediate anti-proliferation effects on various vascular cells. Beta-estradiol (β-E2) has numerous biological protective effects including attenuation of hypoxic pulmonary hypertension (HPH). In the present study, we employed β-E2 to investigate the roles of p27(kip1) and its closely-related kinase (Skp-2) in the progression of PVSR and HPH.

METHODS

Sprague-Dawley rats treated with or without β-E2 were challenged by intermittent chronic hypoxia exposure for 4 weeks to establish hypoxic pulmonary hypertension models, which resemble moderate severity of hypoxia-induced PH in humans. Subsequently, hemodynamic and pulmonary pathomorphology data were gathered. Additionally, pulmonary artery smooth muscle cells (PASMCs) were cultured to determine the anti-proliferation effect of β-E2 under hypoxia exposure. Western blotting or reverse transcriptional polymerase chain reaction (RT-PCR) were adopted to test p27(kip1), Skp-2 and Akt-P changes in rat lung tissue and cultured PASMCs.

RESULTS

Chronic hypoxia significantly increased right ventricular systolic pressures (RVSP), weight of right ventricle/left ventricle plus septum (RV/LV+S) ratio, medial width of pulmonary arterioles, accompanied with decreased expression of p27(kip1) in rats. Whereas, β-E2 treatment repressed the elevation of RVSP, RV/LV+S, attenuated the PVSR of pulmonary arterioles induced by chronic hypoxia, and stabilized the expression of p27(kip1). Study also showed that β-E2 application suppressed the proliferation of PASMCs and elevated the expression of p27(kip1) under hypoxia exposure. In addition, experiments both in vivo and in vitro consistently indicated an escalation of Skp-2 and phosphorylated Akt under hypoxia condition. Besides, all these changes were alleviated in the presence of β-E2.

CONCLUSIONS

Our results suggest that β-E2 can effectively attenuate PVSR and HPH. The underlying mechanism may partially be through the increased p27(kip1) by inhibiting Skp-2 through Akt signal pathway. Therefore, targeting up-regulation of p27(kip1) or down-regulation of Skp-2 might provide new strategies for treatment of HPH.

Evidence of dysfunction of endothelial progenitors in pulmonary arterial hypertension

RATIONALE

Severe pulmonary arterial hypertension (PAH) is characterized by the formation of plexiform lesions and concentric intimal fibrosis in small pulmonary arteries. The origin of cells contributing to these vascular lesions is uncertain. Endogenous endothelial progenitor cells are potential contributors to this process.

OBJECTIVES

To determine whether progenitors are involved in the pathobiology of PAH.

METHODS

We performed immunohistochemistry to determine the expression of progenitor cell markers (CD133 and c-Kit) and the major homing signal pathway stromal cell-derived factor-1 and its chemokine receptor (CXCR4) in lung tissue from patients with idiopathic PAH, familial PAH, and PAH associated with congenital heart disease. Two separate flow cytometric methods were employed to determine peripheral blood circulating numbers of angiogenic progenitors. Late-outgrowth progenitor cells were expanded ex vivo from the peripheral blood of patients with mutations in the gene encoding bone morphogenetic protein receptor type II (BMPRII), and functional assays of migration, proliferation, and angiogenesis were undertaken. measurements and main results: There was a striking up-regulation of progenitor cell markers in remodeled arteries from all patients with PAH, specifically in plexiform lesions. These lesions also displayed increased stromal cell-derived factor-1 expression. Circulating angiogenic progenitor numbers in patients with PAH were increased compared with control subjects and functional studies of late-outgrowth progenitor cells from patients with PAH with BMPRII mutations revealed a hyperproliferative phenotype with impaired ability to form vascular networks.

CONCLUSIONS

These findings provide evidence of the involvement of progenitor cells in the vascular remodeling associated with PAH. Dysfunction of circulating progenitors in PAH may contribute to this process.