Primary pulmonary hypertension

The soluble guanylate cyclase stimulator, 1-nitro-2-phenylethane, reverses monocrotaline-induced pulmonary arterial hypertension in rats

AIMS

We examined the effects of treatment with 1-nitro-2-phenylethane (NP), a novel soluble guanylate cyclase stimulator, on monocrotaline (MCT)-induced PAH in rats.

MAIN METHODS

At day 0, male adult rats were injected with a single subcutaneous (s.c.) dose of monocrotaline (60 mg/kg). Control (CNT) rats received an equal volume of monocrotaline's vehicle only (s.c.). Four weeks later, MCT-treated rats were treated orally for 14 days with NP (50 mg/kg/day) (MCT-NP group) or its vehicle (Tween 2%) (MCT-V group). At the end of the treatment period and before invasive hemodynamic study, rats of all experimental groups were examined by echocardiography.

KEY FINDINGS

With respect to CNT rats, MCT-V rats showed significant; (1) increases in pulmonary artery (PA) diameter, RV free wall thickness and end-diastolic RV area, and increase of Fulton index; (2) decreases in maximum pulmonary flow velocity, PA acceleration time (PAAT), PAAT/time of ejection ratio, and velocity-time integral; (3) increases in estimated mean pulmonary arterial pressure; (4) reduction of maximal relaxation to acetylcholine in aortic rings, and (5) increases in wall thickness of pulmonary arterioles. All these measured parameters were significantly reduced or even abolished by oral treatment with NP.

SIGNIFICANCE

NP reversed endothelial dysfunction and pulmonary vascular remodeling, which in turn reduced ventricular hypertrophy. NP reduced pulmonary artery stiffness, normalized the pulmonary artery diameter and alleviated RV enlargement. Thus, NP may represent a new therapeutic or a complementary approach to treatment of PAH.

Soluble guanylate cyclase stimulator, trans-4-methoxy-β-nitrostyrene, has a beneficial effect in monocrotaline-induced pulmonary arterial hypertension in rats

The soluble guanylate cyclase (sGC)/GMPc pathway plays an important role in controlling pulmonary arterial hypertension (PAH). We investigated whether the novel sGC stimulator trans-4-methoxy-β-nitrostyrene (T4MN), ameliorates monocrotaline (MCT)-induced PAH. At Day 0, rats were injected with MCT (60 mg/kg, s. c.). Control (CNT) rats received an equal volume of monocrotaline vehicle only (s.c.). Four weeks later, MCT-treated rats were orally treated for 14 days with T4MN (75 mg/kg/day) (MCT-T4MN group) or its vehicle (MCT-V group), and with sildenafil (SIL; 50 mg/kg) (MCT-SIL group). Compared to the CNT group, MCT treatment induced a significant increase in both the Fulton index and RV systolic pressure but significantly reduced the maximum relaxation induced by acetylcholine. Indeed, MCT treatment increased the wall thickness of small and larger pulmonary arterioles. Oral treatment with T4MN and SIL reduced the Fulton index and RV systolic pressure compared to the MCT-V group. Maximum relaxation induced by acetylcholine was significantly enhanced in MCT-SIL group. Both T4MN and SIL significantly reduced the enhanced wall thickness of small and larger pulmonary arterioles. Treatment with T4MN has a beneficial effect on PAH by reducing RV systolic pressure and consequently right ventricular hypertrophy, and by reducing pulmonary artery remodeling. T4MN may represent a new therapeutic or complementary approach for the treatment of PAH.

Pulmonary Arterial Hypertension in Hispanics

Pulmonary hypertension (PH) is a medical condition characterized by elevated pressures in the pulmonary vessels. Pulmonary arterial hypertension (PAH), or pre-capillary PH, is a subgroup of the broader PH definition. PAH is rare compared to other groups of PH; its prevalence is about 15 cases per million in the adult population. Several disease processes may lead to PAH; however, the most common cause of PAH is idiopathic. Until recently, treatment for PAH was very limited and prognosis was dismal. Limitations in management remain present today but more treatment options are available for patients suffering from this condition. 

Most of the information available regarding PAH comes from registries in the United States and Europe. Limited information about epidemiology, treatment options, and response to the treatment is available for other ethnic groups such as Hispanics. In the world of medicine, we have learned from other more common medical conditions that components, such as genetics, environment, and culture may affect how diseases manifest and how they respond to treatment. It is important to be aware of how different ethnic groups exposed to different environmental conditions respond to different treatment modalities. The aim of this paper is to review the limited data available regarding PAH in Hispanics. This paper will review the information regarding the etiology, diagnosis, and treatment modalities available in South American and Central American countries. This paper will also review the data available for Hispanics diagnosed with PAH living in the United States. The goal is to highlight the difference in how PAH manifests in Hispanics compared to other ethnic groups. We aim to emphasize the importance of the lack of data available for this group and how it may be affecting the way we are treating Hispanics with PAH. 

A Correlative Study of Spirometric Parameters and Markers of Right Ventricular Dysfunction in Pediatric Patients with Pulmonary Arterial Hypertension

Background: Alteration in lung function is present in children with pulmonary arterial hypertension (PAH). We aimed to study the pulmonary function indices obtained by spirometry in pediatric patients with PAH, and to correlate them with B-type natriuretic peptide (BNP) and echocardiographic parameters.

Methods: Thirty-one children with PAH were enrolled in this study, of those 26 patients (83.87%) associated shunt defect and 5 patients (16.12%) were diagnosed with idiopathic PAH. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, peak expiratory flow rate (PEFR), forced expiratory flow at 25–75% of the pulmonary volume (FEF 25–75) were evaluated by spirometry and correlated with BNP and echocardiographic parameters that reflect right ventricle function.

Results: Restrictive pattern of pulmonary function was present in 51.6% (n = 16) of all PAH children. There were significant correlations between BNP with FVC (p = 0.001), FEV1 (p = 0.001), and FEV1/FVC (p = 0.001). Serum BNP level was significantly increased in the group of patients without shunt. Of those echocardiographic parameters that reflect right ventricle function, we found that TAPSE significantly correlated with PEFR (r = −0.47, p <0.01), and with FEF 25–75 (r = −0.39, p <0.01).

Conclusions: Deterioration of the pulmonary function indices are correlated with BNP and echocardiographic parameters, markers of RV dysfunction. Being easy and reliable tests, pulmonary functions can be introduced among the follow-up tools in children with PAH.

An exploratory panel of biomarkers for risk prediction in pulmonary hypertension: emerging role of CT-proET-1

BACKGROUND

Pulmonary arterial hypertension (PAH) is a rare, deadly condition. Although risk stratification is extremely important for assessment of prognosis and to guide therapy, there is lack of evidence concerning the role of novel biomarkers. In a pivotal study, we sought to comparatively investigate the predictive power of several new biomarkers in PAH.

METHODS

Patients with prevalent PAH were enrolled in the study protocol, which included clinical, functional and echocardiographic assessment. Blood samples were collected at baseline for determination of NT-proBNP, CT-proET-1, MR-proANP, MR-proADM, copeptin and troponin I. Patients were clinically followed-up up to 12 months for first occurrence of hospital admission due to PAH-related clinical worsening, heart/lung transplantation or all-cause mortality.

RESULTS

Among the 28 included patients the pre-specified end-point occurred in 8 (29% event rate). There were higher baseline levels of CT-proET-1, copeptin, MR-proANP, NT-proBNP and troponin I in patients who reached the composite end-point. They also had larger right atria. In multivariate Cox regression, CT-proET-1 was the only biomarker associated with increased hazard of reaching the primary composite end-point (hazard ratio per tertile increase = 10.1; 95% CI 2.0 to 50.6).

CONCLUSIONS

CT-proET-1 provided prognostic information independent of other biomarkers. Importantly, we have provided the first evidence that CT-proET-1 may be superior to commonly used biomarkers.

Physiological characterization of a mouse model of cachexia in colorectal liver metastases

Loss of skeletal muscle mass and function (cachexia) is severe in patients with colorectal liver metastases because of the large increase in resting energy expenditure but remains understudied because of a lack of suitable preclinical models. Our aim was to characterize a novel preclinical model of cachexia in colorectal liver metastases. We tested the hypothesis that mice with colorectal liver metastases would exhibit cachexia, as evidenced by a reduction in liver-free body mass, muscle mass, and physiological impairment. Twelve-week-old male CBA mice received an intrasplenic injection of Ringer solution (sham) or murine colorectal cancer cells (MoCR) to induce colorectal liver metastases. At end-point (20-29 days), the livers of MoCR mice were infiltrated completely with metastases, and MoCR mice had reduced liver-free body mass, muscle mass, and epididymal fat mass compared with sham controls (P < 0.03). MoCR mice exhibited impaired rotarod performance and grip strength (P < 0.03). Histochemical analyses of tibialis anterior muscles from MoCR mice revealed muscle fiber atrophy and reduced oxidative enzyme activity (P < 0.001). Adipose tissue remodeling was evident in MoCR mice, with reduced adipocyte diameter and greater infiltration of nonadipocyte tissue (P < 0.05). These findings reveal the MoCR mouse model exhibits significant cachexia and is a suitable preclinical model of cachexia in colorectal liver metastases. This model should be used for identifying effective treatments for cachexia to improve quality of life and reduce mortality in patients with colorectal liver metastases.

Pulmonary hypertension in parenchymal lung disease

Idiopathic pulmonary arterial hypertension (IPAH) has been extensively investigated, although it represents a less common form of the pulmonary hypertension (PH) family, as shown by international registries. Interestingly, in types of PH that are encountered in parenchymal lung diseases such as interstitial lung diseases (ILDs), chronic obstructive pulmonary disease (COPD), and many other diffuse parenchymal lung diseases, some of which are very common, the available data is limited. In this paper, we try to browse in the latest available data regarding the occurrence, pathogenesis, and treatment of PH in chronic parenchymal lung diseases.

Correlation of a scintigraphic pulmonary perfusion index with hemodynamic parameters in patients with pulmonary arterial hypertension

PURPOSE

To determine whether the perfusion index (PI) can be used as a noninvasive measure to diagnose and predict the severity of disease in patients with pulmonary arterial hypertension (PAH).

MATERIALS AND METHODS

Twenty-two patients were included in this retrospective investigation: 9 controls and 13 patients with PAH. Controls had no evidence of PAH [mean pulmonary arterial pressure (MPAP) ≤25 mm Hg and pulmonary capillary wedge pressure ≤18 mm Hg]. The study patients had PAH (MPAP ≥25 mm Hg and pulmonary capillary wedge pressure ≤18 mm Hg) and no diagnosis of pulmonary embolism. Due to the retrospective nature of the study, the PI was calculated from the posterior perfusion image of a ventilation perfusion scan. The PI was computed as the sum of differences versus control for the 9 deciles above background. Receiver operating characteristic curve analysis was used to compare PI with other parameters for predicting PAH.

RESULTS

Linear correlations of PI were found to be significant with the following parameters: pulmonary vascular resistance (r=0.81, P=0.00009), total pulmonary vascular resistance (MPAP/cardiac output) (r=0.80, P=0.00013), pulmonary artery systolic pressure (r=0.73, P=0.00018), MPAP (r=0.72, P=0.00022), pulmonary diastolic pressure (r=0.53, P=0.01), and right atrial pressure (r=0.50, P=0.03). Using logistic regression, the PI was significant in separating patients with PAH from controls (χ²=5.6, P=0.02).

CONCLUSION

The data suggest that PI can be used for the noninvasive diagnosis and measurement of severity of PAH.

Recent trends in pulmonary arterial hypertension

Pulmonary hypertension is a serious and unrelenting pulmonary vascular disorder that affects the functional quality of patients and significantly decreases their life span. If diagnosed early, with the number of new therapeutic options that are available, a better quality of life can be provided for a protracted length of time. It is likely that the available treatment will change the natural course of the disease and perhaps prolong survival. As symptoms are often subtle in the early stages of the disease it is imperative that physicians are aware of the manifestations of this condition. A thorough investigation of patients suspected of this condition is essential so that appropriate treatment can be initiated promptly. The routine workup of a patient suspected to have pulmonary hypertension could easily be carried out in any well-equipped peripheral hospital in many affluent and advanced countries. However, it must be mentioned that in some less advanced countries the necessary work up can only be done in major teaching hospitals. Both pulmonologists and cardiologists should be aware of the pathophysiology of pulmonary arterial hypertension, the workup and the treatment options that are available. Patients with refractory pulmonary hypertension should be referred to these research centers for enrolment into any ongoing drug trials as well as for evaluation for heart-lung, single lung, or double lung transplantation. This paper is primarily aimed at pulmonologists and cardiologists taking care of these patients. Unless indicated otherwise this paper mainly deals with WHO group 1 pulmonary hypertension which is designated pulmonary arterial hypertension. Extensive review of the literature spanning the last 30 years was made through Medline using titles such as primary pulmonary hypertension, pulmonary arterial hypertension, secondary pulmonary hypertension, and pulmonary vascular diseases.

Gene therapy techniques for the delivery of endothelial nitric oxide synthase to the lung for pulmonary hypertension

Pulmonary hypertension (PH) is a serious, often fatal disease characterized by remodeling of the pulmonary vascular bed, increased pulmonary arterial pressure, and right heart failure. The increased vascular resistance in the pulmonary circulation is due to structural changes and increased vasoconstrictor tone. Although current therapies have prolonged survival, the long-term outcome is not favorable. Nitric oxide (NO) is synthesized by endothelial nitric oxide synthase (eNOS) and is important in regulating vascular resistance and in vascular remodeling in the lung. NO deficiency due to endothelial dysfunction plays an important role in the pathogenesis of PH. Therefore, local eNOS gene delivery to the lung is a promising approach for the treatment of PH. Adenoviral-mediated in vivo gene therapy and adult stem cell-based ex vivo gene therapy are two attractive current gene therapies for the treatment of cardiovascular and pulmonary diseases. In this chapter we describe the use of two gene transfer techniques, i.e., adenoviral gene transfer of eNOS and eNOS gene-modified rat marrow stromal cells, for eNOS gene delivery to the lung of laboratory animals for the treatment of PH.

New concepts in the invasive and non invasive evaluation of remodelling of the right ventricle and pulmonary vasculature in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare fatal disease defined as a sustained elevation of pulmonary arterial pressure to more than 25 mmHg at rest, with a mean pulmonary-capillary wedge pressure and left ventricular enddiastolic pressure of less than 15 mmHg at rest. Histopathology of PAH is founded on structural modifications on the vascular wall of small pulmonary arteries characterized by thickening of all its layers. These changes, named as vascular remodelling, include vascular proliferation, fibrosis, and vessel obstruction. In clinical practice the diagnosis of PAH relies on measurements of pulmonary vascular pressure and cardiac output, and calculation of pulmonary vascular resistances. Direct evaluation of pulmonary vascular structure is not routinely performed in pulmonary hypertension since current imaging techniques are limited and since little is known about the relationship between structural changes and functional characteristics of the pulmonary vasculature. Intravascular ultrasound studies in patients with pulmonary hypertension have shown a thicker middle layer, increased wall-thickness ratio and diminished pulsatility than in control patients. Optical Coherence Tomography, a new high resolution imaging modality that has proven its superiority over intravascular ultrasound (IVUS) for the detection and characterization of coronary atherosclerotic plaque composition, may potentially be a useful technique for the in vivo study of the pulmonary arterial wall. In addition current progress in Echo Doppler technique will quantify right ventricular function with parameters independent of loading conditions and not requiring volumetric approximations of the complex geometry of the right ventricle. This would allow the in vivo study of right ventricular and pulmonary artery remodelling in PAH.

Ambrisentan for the Treatment of Pulmonary Arterial Hypertension

Objective:

To review the pharmacology, pharmacokinetics, efficacy, and safety of ambrisentan, a selective endothelin type A (ETA) receptor antagonist, for the treatment of pulmonary arterial hypertension (PAH).

Data Sources:

Articles were identified through a search of the MEDLINE (1950–November 2007) database for English-language articles containing the key words ambrisentan, pulmonary arterial hypertension, pulmonary hypertension, endothelin antagonist, and endothelin type A receptor. References from publications identified in this search were reviewed for relevant information. Unpublished data received from the manufacturer were also included in this review.

Study Selection and Data Extraction:

All articles identified from the data search were reviewed for relevant information. Applicable information was included in this review.

Data Synthesis:

Ambrisentan is the first oral nonsulfonamide ETA receptor antagonist approved by the FDA for use in patients with PAH who have World Health Organization class II or III symptoms. To date, the use of ambrisentan in the treatment of PAH has been evaluated by only 1 published Phase 2 clinical trial and 3 unpublished Phase 3 clinical trials. Ambrisentan therapy during clinical trials resulted in a significant improvement in exercise capacity and hemodynamic parameters. Metabolism occurs by hepatic glucuronidation, with elimination primarily through nonrenal pathways. A half-life of 15 hours allows for once-daily dosing. The most common adverse effect reported during clinical trials was peripheral edema. Hepatotoxicity occurred very infrequently, with affected patients requiring only a dose reduction to resolve an episode of elevated aminotransferases.

Conclusions:

Ambrisentan appears to be a promising treatment option for patients affected by PAH, given its improved drug–drug interaction and hepatotoxicity profile compared with other endothelin antagonists. Future studies are needed to determine the role of ambrisentan in the treatment of PAH and the selection of optimal endothelin antagonism.

Pathogenic mechanisms of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a complex disease that causes significant morbidity and mortality and is clinically characterized by an increase in pulmonary vascular resistance. The histopathology is marked by vascular proliferation/fibrosis, remodeling, and vessel obstruction. Development of PAH involves the complex interaction of multiple vascular effectors at all anatomic levels of the arterial wall. Subsequent vasoconstriction, thrombosis, and inflammation ensue, leading to vessel wall remodeling and cellular hyperproliferation as the hallmarks of severe disease. These processes are influenced by genetic predisposition as well as diverse endogenous and exogenous stimuli. Recent studies have provided a glimpse at certain molecular pathways that contribute to pathogenesis; these have led to the identification of attractive targets for therapeutic intervention. We will review our current understanding of the mechanistic underpinnings of the genetic and exogenous/acquired triggers of PAH. The resulting imbalance of vascular effectors provoking pathogenic vascular changes will also be discussed, with an emphasis on common and overarching regulatory pathways that may relate to the primary triggers of disease. The current conceptual framework should allow for future studies to refine our understanding of the molecular pathogenesis of PAH and improve the therapeutic regimen for this disease.

Idiopathic pulmonary arterial hypertension misdiagnosed as asthma

Idiopathic pulmonary arterial hypertension (IPAH) is a rare disorder that is progressive and often leads to right heart failure if left untreated. Because of the vague nature of symptoms at presentation, IPAH may take several months to diagnose. The most common presenting complaint in patients with IPAH is dyspnea with exertion, which is also commonly seen with asthma. This report describes an adult female with refractory exertional dyspnea who was diagnosed with asthma 2 years earlier but was ultimately diagnosed with IPAH. Exclusion of other etiologies is a necessity for refractory dyspnea in the setting of asthma.

Bone morphogenetic protein type 2 receptor gene therapy attenuates hypoxic pulmonary hypertension

Idiopathic pulmonary arterial hypertension (PAH) is characterized by proliferation of pulmonary vascular endothelial and smooth muscle cells causing increased vascular resistance and right heart failure. Mutations in the bone morphogenetic protein receptor type 2 (BMPR2) are believed to cause the familial form of the disease. Reduced expression of BMPR2 is also noted in secondary PAH. Recent advances in the therapy of PAH have improved quality of life and survival, but many patients continue to do poorly. The possibility of treating PAH via improving BMPR2 signaling is thus a rational consideration. Such an approach could be synergistic with or additive to current treatments. We developed adenoviral vectors containing the BMPR2 gene. Transfection of cells in vitro resulted in upregulation of SMAD signaling and reduced cell proliferation. Targeted delivery of vector to the pulmonary vascular endothelium of rats substantially reduced the pulmonary hypertensive response to chronic hypoxia, as reflected by reductions in pulmonary artery and right ventricular pressures, right ventricular hypertrophy, and muscularization of distal pulmonary arterioles. These data provide further evidence for a role for BMPR2 in PAH and provide a rationale for the development of therapies aimed at improving BMPR2 signaling.

Long-term outcome and effects of oral bosentan therapy in Taiwanese patients with advanced idiopathic pulmonary arterial hypertension

STUDY DESIGN

We report on the long-term outcome and effects of bosentan treatment in Taiwanese patients with advanced (functional class III or IV) idiopathic pulmonary arterial hypertension (IPAH).

MATERIALS AND METHODS

IPAH patients on stable bosentan therapy for more than 12 months and regularly monitored were eligible for this prospective uncontrolled study. Patients were evaluated for several clinical parameters, both measured at the time of initiation of bosentan therapy and after 12 months on therapy: New York Heart Association functional class (NYHA FC), change in 6-min walk distance (6MWD), right ventricle ejection fraction (RVEF), cardiothoracic ratio (CTR), and pulmonary functional status.

RESULTS

Twelve of 15 patients met eligibility requirements and were enrolled. Their mean age was 37.6+/-12.9 years and 92% were female. Six (50%) patients were in NYHA FC IV and the others were in NYHA FC III at baseline. Three (25%) patients were chronic hepatitis C virus (HCV) carriers, with normal liver function. After 12 months of bosentan treatment, 6-MWD, RVEF, and pulmonary function all increased significantly. CTR and NYHA FC both decreased significantly. Oral bosentan was well tolerated and there was no episode of liver dysfunction that required adjustment of the bosentan dosage or discontinuance of therapy.

CONCLUSION

Long-term treatment with oral bosentan appears to have beneficial effects on functional status, exercise capacity, right heart function, and pulmonary function in Taiwanese patients with advanced IPAH, regardless of whether or not they presented with chronic HCV infection.

Inhibition of vascular smooth muscle cell proliferation in vitro by genetically engineered marrow stromal cells secreting calcitonin gene-related peptide

Calcitonin gene-related peptide (CGRP) has a beneficial effect in pulmonary hypertension and is a target for cardiovascular gene therapy. Marrow stromal cells (MSCs), also known as mesenchymal stem cells, hold promise for use in adult stem cell-based ex vivo gene therapy. To test the hypothesis that genetically engineered MSCs secreting CGRP can inhibit vascular smooth muscle cell proliferation, rat MSCs were isolated, ex vivo expanded, and transduced with adenovirus containing CGRP. Immunocytochemical analysis demonstrated that wild type rat MSCs express markers specific for stem cells, endothelial cells, and smooth muscle cells including Thy-1, c-Kit, von Willebrand Factor and alpha-smooth muscle actin. Immunocytochemistry confirmed the expression of CGRP by the transduced rat MSCs. The transduced rat MSCs released 10.3+/-1.3 pmol CGRP/1 x 10(6) cells/48 h (mean+/-S.E.M., n=3) into culture medium at MOI 300 and the CGRP-containing culture supernatant from the transduced cells inhibited the proliferation of rat pulmonary artery smooth muscle cells (PASMCs) and rat aortic smooth muscle cells (ASMCs) in culture. Co-culture of the transduced rat MSCs with rat PASMCs or rat ASMCs also inhibited smooth muscle cell proliferation. These findings suggest that this novel adult stem cell-based CGRP gene therapy has potential for the treatment of cardiovascular diseases including pulmonary hypertension.

Mutations of TGFbeta signaling molecules in human disease

The transforming growth factor beta (TGFbeta) signaling pathway regulates several biological processes including cellular proliferation, differentiation, apoptosis, migration, and extracellular matrix deposition. Ligand and receptor family members signal through two main Smad signaling branches, TGFbeta/activin to Smad2/3 (Sma and MAD-related proteins) and bone morphogenetic protein (BMP) to Smad1/5. At the molecular level, TGFbeta acts by modifying cytoskeletal organization and ultimately regulating expression of specific target genes. Germline disruption of TGFbeta signaling leads to several types of hereditary congenital malformation or dysfunction of the skeletal, muscular and/or cardiovascular systems, and to cancer predisposition syndromes. In this review, the molecular etiology of TGFbeta-associated disorders is examined, together with a discussion of clinical overlap between syndromes and possible biological explanations underlying the variable penetrance and expressivity of clinical characteristics. Increasing our understanding of the molecular etiology underlying genotype-phenotype correlations will ultimately provide a molecular-based approach that should result in better prognostic tools, smart therapeutics and individualized disease management, not only for these rare syndromes, but for more generalized disorders of the cardiovascular and musculoskeletal systems and cancer. The clinical consequence of TGFbeta signaling mutations appears to depend on environmental factors and on the basal levels of ongoing signaling transduction networks specific to each individual. In this respect, genetic background might be a central factor in determining disease outcome and treatment strategy for TGFbeta-associated diseases.

Pulmonary arterial hypertension

Pulmonary arterial hypertension is a disease of the small pulmonary arteries characterized by vascular narrowing and increased pulmonary vascular resistance, which eventually leads to right ventricular failure. Vasoconstriction, vascular proliferation, remodeling of the pulmonary vessels, and thrombosis are all contributing factors to the increased vascular resistance seen in this disease. Pulmonary arterial hypertension develops as a sporadic disease (idiopathic), as an inherited disorder (familial), or in association with certain conditions (collagen vascular diseases, portal hypertension, human immunodeficiency virus infection, congenital systemic-to-pulmonary shunts, ingestion of drugs or dietary products, or persistent fetal circulation). The pathogenesis of pulmonary arterial hypertension is a complicated, multifactorial process. It seems doubtful that any one factor alone is sufficient to activate the necessary pathways leading to the development of this disease. Rather, clinically apparent pulmonary arterial hypertension most likely develops after a second insult occurs in an individual who is already susceptible owing to genetic factors, environmental exposures, or acquired disorders. Currently, there is no cure for pulmonary arterial hypertension but several novel therapeutic options are now available that can improve symptoms and increase survival.

In situ central pulmonary artery thrombosis in primary pulmonary hypertension

A rare case of extensive in situ central pulmonary artery thrombosis in primary pulmonary hypertension (PPH) is presented. The differentiation from chronic thromboembolic pulmonary arterial hypertension (CTEPH) is of paramount importance because of different therapeutic strategies. In this case, the presence of mural thrombus in the central pulmonary arteries on computed tomography made the distinction difficult. However, the possibility of in situ thrombosis was suggested on the basis of absence of other findings of CTEPH (abrupt narrowing/truncation of segmental arteries, variation in size of segmental vessels, arterial webs, mosaic attenuation, pulmonary infarcts, and dilated bronchial arteries), and this was confirmed on final pathology.

Increased susceptibility to pulmonary hypertension in heterozygous BMPR2-mutant mice

BACKGROUND

Bone morphogenetic protein receptor-2 (BMPR2)-heterozygous, mutant (BMPR2(+/-)) mice have a genetic trait similar to that of certain patients with idiopathic pulmonary arterial hypertension (IPAH). To understand the role of BMPR2 in the development of IPAH, we examined the phenotype of BMPR2(+/-) mice and their response to inflammatory stress.

METHODS AND RESULTS

BMPR2(+/-) mice were found to have the same life span, right ventricular systolic pressure (RVSP), and lung histology as those of wild-type mice under unstressed conditions. However, when treated with recombinant adenovirus expressing 5-lipoxygenase (Ad5LO), BMPR2(+/-) mice exhibited significantly higher RVSP than wild-type mice. The increase of RVSP occurred in the first 2 weeks after Ad5LO delivery. Modest but significant muscularization of distal pulmonary arterioles appeared in BMPR2(+/-) mice 4 weeks after Ad5LO treatment. Measurement of urinary metabolites of vasoactive molecules showed that cysteinyl leukotrienes, prostacyclin metabolites, and PGE2 were all increased to a similar degree in both BMPR2(+/-) and wild-type mice during 5LO transgene expression, whereas urinary endothelin-1 remained undetectable. Urinary thromboxane A2 metabolites, in contrast, were significantly higher in BMPR2(+/-) than in wild-type mice and paralleled the increase in RVSP. Platelet activation markers, serotonin, and soluble P-selectin showed a trend toward higher concentrations in BMPR2(+/-) than wild-type mice. Cell culture studies found that BMP treatment reduced interleukin-1beta-stimulated thromboxane A2 production in the pulmonary epithelial cell line A549.

CONCLUSIONS

BMPR2(+/-) mice do not develop pulmonary hypertension spontaneously; however, under inflammatory stress, they are more susceptible to an increase in RVSP, thromboxane A2 production, and vascular remodeling than wild-type mice.

Pulmonary hypertension in men with thyrotoxicosis

Thyrotoxicosis has a myriad of respiratory symptoms including dyspnea. Pulmonary hypertension may contribute to the respiratory symptoms of thyrotoxicosis, but is often unrecognized. We describe 3 male patients with thyrotoxicosis and associated pulmonary hypertension. Case reports of an additional 15 patients are also reviewed. In patients with thyrotoxicosis and pulmonary hypertension, treatment of thyrotoxicosis alone is associated with improvement in pulmonary hypertension. Previous reports have consisted of mostly female patients, but we report 3 men. When all cases are considered, the typical patient is female (10/14 = 71%), middle-aged (48 years), with mean pulmonary artery systolic pressures improving from 56 to 32 mm Hg with treatment. Autoantibodies were detected in 10/14 (71%) patients. The response to treatment (medical or surgical) of thyrotoxicosis supports the hypothesis that hyperthyroidism is either a cause of pulmonary hypertension, or a factor that may unmask pulmonary hypertension. Recognition is important since treatment and response are very different compared to other patients with pulmonary hypertension. This association may not be readily considered in men, since most reports have been of women.

Systemic collateral supply in patients with chronic thromboembolic and primary pulmonary hypertension: assessment with multi-detector row helical CT angiography

PURPOSE

To compare retrospectively the frequency of systemic collateral supply in patients who have chronic thromboembolic pulmonary hypertension with the frequency of systemic collateral supply in patients who have primary pulmonary hypertension by using multi-detector row helical computed tomographic (CT) angiography.

MATERIALS AND METHODS

For this review, neither institutional board approval nor informed consent was required. Thirty-six consecutive patients, including 22 patients (four men, 18 women; mean age, 46.0 years) with chronic thromboembolic pulmonary hypertension (group 1) and 14 patients (five men, nine women; mean age, 63.0 years) with primary pulmonary hypertension (group 2), underwent multisection spiral CT angiography of the pulmonary and systemic circulations with a four- (n = 17) or 16- (n = 19) detector row scanner. CT angiograms were assessed for the presence of abnormal bronchial and/or nonbronchial systemic arteries, CT features of pulmonary hypertension, and right ventricular dysfunction. Vascular and parenchymal signs of chronic pulmonary embolism were specifically analyzed on CT angiograms of group 1 patients. Comparative analyses were performed by using the chi(2) or the Fisher exact test for categoric data. An unpaired bilateral Wilcoxon rank sum test was used for continuous data. A chi(2) goodness-of-fit test was used to compare observed proportions with equal proportions.

RESULTS

The degree of pulmonary hypertension was comparable in groups 1 and 2. Abnormally enlarged systemic arteries were identified in 16 (73%) of 22 patients from group 1 and in two (14%) of 14 patients from group 2 (P = .002). The systemic collateral supply in group 1 comprised enlargement of both bronchial and nonbronchial systemic arteries in nine (56%) of the 16 patients; the remaining seven patients had an exclusive enlargement of bronchial systemic arteries (n = 6, 38%) or nonbronchial (n = 1, 6%) systemic arteries. A total of 31 enlarged nonbronchial systemic arteries were depicted, including 13 inferior phrenic arteries, 10 intercostal arteries, seven internal mammary arteries, and one lateral thoracic artery. The mean +/- standard deviation of abnormal nonbronchial systemic arteries per patient was 1.4 +/- 1.9. No relationship was found between the mean number of abnormally enlarged nonbronchial systemic arteries and the CT angiographic features of chronic pulmonary embolism.

CONCLUSION

These results demonstrate the higher frequency of abnormally enlarged bronchial and nonbronchial systemic arteries in patients who have chronic thromboembolic pulmonary hypertension compared with patients who have primary pulmonary hypertension; this finding could help distinguish these two entities on CT angiograms.

Caractéristiques cliniques, hémodynamiques et génétiques de l’hypertension artérielle pulmonaire familiale

INTRODUCTION

Pulmonary arterial hypertension (PAH) is defined by a raised pressure in the pulmonary arterial circulation associated with small vessel narrowing due to proliferation of the endothelium and vascular smooth muscle. Idiopathic PAH should be distinguished from PAH associated with a causal disease. One familial type (familial PAH), gathered from one family, has recently been linked to a mutation of the BMPR 2 (bone morphogenetic protein receptor 2) gene. It seems important to compare the idiopathic form of PAH with these familial forms to confirm that the same diagnostic and therapeutic principles can be applied to familial PAH.

MATERIAL AND METHODS

The demographic, clinical, haemodynamic and prognostic data from 34 cases of familial PAH were compared with those of 451 cases of idiopathic PAH. The genetic characteristics of the familial forms were also defined.

RESULTS

Familial PAH presented at a younger age than idiopathic PH (31 +/- 15 vs. 45 +/- 18 years p=0.002) without any other demographic difference (sex-ratio 2.09/1 et 1.42/1 p=NS). There was no difference in exercises tolerance (6 minute walking test 341 +/- 98 and 289 +/- 135 metres p=NS), in haemodynamic parameters (mean PAP 65 +/- 12 and 62 +/- 15 mmHg, p=NS), or in prognosis, with the exception of an absence of a vasodilator response in the familial group to nitric oxide challenge. We found the BMPR 2 gene mutation to be quantitatively and qualitatively comparable to previously published data.

CONCLUSION

The only difference between these two forms of this illness were of a younger age at presentation and an absent vasodilator response in the familial PAH group. We do not propose that familial PAH should be treated any differently from the idiopathic form. Genetic counselling will need to be developed in line with the progress being made in the understanding of this condition.

Antiproliferative effects of calcitonin gene-related peptide in aortic and pulmonary artery smooth muscle cells

Pulmonary hypertension is characterized by vascular remodeling involving smooth muscle cell proliferation and migration. Calcitonin gene-related peptide (CGRP) and nitric oxide (NO) are potent vasodilators, and the inhibition of aortic smooth muscle cell (ASMC) proliferation by NO has been documented, but less is known about the effects of CGRP. The mechanism by which overexpression of CGRP inhibits proliferation in pulmonary artery smooth muscle cells (PASMC) and ASMC following in vitro transfection by the gene coding for prepro-CGRP was investigated. Increased expression of p53 is known to stimulate p21, which inhibits G(1) cyclin/cdk complexes, thereby inhibiting cell proliferation. We hypothesize that p53 and p21 are involved in the growth inhibitory effect of CGRP. In this study, CGRP was shown to inhibit ASMC and PASMC proliferation. In PASMC transfected with CGRP and exposed to a PKA inhibitor (PKAi), cell proliferation was restored. p53 and p21 expression increased in CGRP-treated cells but decreased in cells treated with CGRP and PKAi. PASMC treated with CGRP and a PKG inhibitor (PKGi) recovered from inhibition of proliferation induced by CGRP. ASMC treated with CGRP and then PKAi or PKGi recovered only when exposed to the PKAi and not PKGi. Although CGRP is thought to act through a cAMP-dependent pathway, cGMP involvement in the response to CGRP has been reported. It is concluded that p53 plays a role in CGRP-induced inhibition of cell proliferation and cAMP/PKA appears to mediate this effect in ASMC and PASMC, whereas cGMP appears to be involved in PASMC proliferation.

Pulmonary hypertension as a result of drug therapy

Pulmonary hypertension, as a result of adverse drug reactions, must be considered as a rare occurrence. With good medicinal chemistry and screening of compounds before entry into man, it should be almost totally avoidable. Life and medicine are a continuing challenge as our exploration of the regions of unknown biology throw up new targets and new mechanisms and may catch us again as the anorectic (anorectic) drug caught our predecessors.

Epoprostenol in Pregnant Patients with Secondary Pulmonary Hypertension

Women who present with pulmonary hypertension during gestation have traditionally been persuaded to terminate their pregnancy. Historically, the mortality associated with this group is very high. Certain patients with a secondary cause of pulmonary hypertension are believed to share similar pathophysiology with primary pulmonary hypertension patients. Recently, new treatments have become available that have slowed disease progression. We present the successful treatment of two patients who presented during late gestation with moderate pulmonary hypertension. Both patients were managed with intravenous vasodilators and anticoagulants without complication. Each patient successfully delivered a healthy child via spontaneous vaginal delivery. The review of the historical management of similar patients including new insights into the etiology of pulmonary arterial hypertension is also included. It highlights the complexity involved in managing such patients and the requirement of a multidisiplinary team approach.

Growth factor signaling in lung morphogenetic centers: automaticity, stereotypy and symmetry

Lung morphogenesis is stereotypic, both for lobation and for the first several generations of airways, implying mechanistic control by a well conserved, genetically hardwired developmental program. This program is not only directed by transcriptional factors and peptide growth factor signaling, but also co-opts and is modulated by physical forces. Peptide growth factors signal within repeating epithelial-mesenchymal temporospatial patterns that constitute morphogenetic centers, automatically directing millions of repetitive events during both stereotypic branching and nonstereotypic branching as well as alveolar surface expansion phases of lung development. Transduction of peptide growth factor signaling within these centers is finely regulated at multiple levels. These may include ligand expression, proteolytic activation of latent ligand, ligand bioavailability, ligand binding proteins and receptor affinity and presentation, receptor complex assembly and kinase activation, phosphorylation and activation of adapter and messenger protein complexes as well as downstream events and cross-talk both inside and outside the nucleus. Herein we review the critical Sonic Hedgehog, Fibroblast Growth Factor, Bone Morphogenetic Protein, Vascular Endothelial Growth Factor and Transforming Growth Factorbeta signaling pathways and propose how they may be functionally coordinated within compound, highly regulated morphogenetic gradients that drive first stereotypic and then non-stereotypic, automatically repetitive, symmetrical as well as asymmetrical branching events in the lung.

Effect of continuous subcutaneous treprostinil therapy on the pharmacodynamics and pharmacokinetics of warfarin

Treprostinil sodium was recently approved in the United States for continuous subcutaneous infusion in the treatment of pulmonary arterial hypertension (PAH). Anticoagulation with warfarin is recommended in PAH therapy. Given the likelihood for treprostinil and warfarin coadministration, a single-blind, controlled, crossover study was conducted to evaluate the effect of treprostinil infusion on the pharmacodynamics and pharmacokinetics of a single dose of warfarin. Area under the effect-time curve (AUEC(0-1)) and maximum effect over the entire sampling phase (E(max)) for warfarin INR were 219.58 and 2.071 with treprostinil and 218.93 and 2.041 with vehicle, respectively. Mean time to attain the peak concentration of R-enantiomer of warfarin (T(max)), half-life, and elimination rate constant (k(el)) were 1.9 hours, 51.688 hours, and 0.0137 per hour, respectively, in the presence of treprostinil and 1.5 hours, 52.579 hours, and 0.0137 per hour, respectively, in the presence of vehicle (control). Results were similar for the S-enantiomer. The 90% confidence intervals for warfarin INR and warfarin R- and S-enantiomer pharmacokinetic parameter (C(max) and AUC( infinity )) ratios were within 0.80-1.25, which was established as the no-effect criterion for treprostinil coadministration. No serious or severe adverse events, anticoagulation-related events, or clinically significant physical or laboratory findings were reported. These findings suggest that a clinically important interaction between treprostinil and warfarin during therapy is unlikely.

Small-vessel diseases of the lung: CT-pathologic correlates

Diseases that primarily affect the small vessels of the lung are difficult to diagnose. Many conditions are characterized by involvement of small pulmonary vessels, and pathologically they can be conveniently divided into occluding and inflammatory types. The former, typified by chronic pulmonary thromboembolism and primary pulmonary hypertension, are relatively cryptic in terms of imaging. In contrast, inflammatory vasculitides, which often cause pulmonary hemorrhage and infarction, result in florid but nonspecific radiographic abnormalities. The spectrum of thin-section computed tomographic abnormalities encountered in the inflammatory vasculitides is wide: For example, in Wegener granulomatosis the pattern ranges from cavitating nodules to lobar consolidation to ground-glass opacity. This review highlights some of the less obvious imaging manifestations of occlusive and inflammatory diseases of the small pulmonary vessels.

Inhaled diazeniumdiolates (NONOates) as selective pulmonary vasodilators

Selective pulmonary vasodilators cause vasodilatation limited to the pulmonary vasculature, within well-ventilated lung regions. Selective pulmonary vasodilators ideally cause only a minimal effect on the systemic circulation and improve ventilation/perfusion matching. NONOates are a novel group of chemical compounds that spontaneously and continuously release nitric oxide under physiological conditions, over periods of up to 24 h. Inhaled NONOates retain the benefits of gaseous nitric oxide without many of its therapeutic disadvantages. This review focuses on the therapeutic potential of inhaled NONOates in pulmonary hypertension, other lung conditions associated with right ventricular dysfunction and in asthma. The potential toxicity of NONOates is also discussed.

[Clinico-hemodynamic study and treatment of 44 patients with primary pulmonary hypertension]

BACKGROUND

Primary pulmonary hypertension is a poorly understood disease with a difficult treatment.

PATIENTS AND METHOD

Retrospective study of a series of 44 patients suffering from pulmonary hypertension who were studied in our center between 1992 and 2000.

RESULTS

At diagnosis, 6 (13%) patients were classified as having NYHA functional class I, 11 (25%) had class II, 25 (57%) had class III, and 2 had class IV. Mean pulmonary artery systolic pressure by echo-doppler was 92 (range: 43-154) mmHg. Basal right catheterization showed a mean (SD) pulmonary artery pressure of 58 (18) mmHg, total basal pulmonary resistances of 1679 (1,071) din/cm2 and cardiac index of 2.2 (1) 1/minute/m2. Five patients improved with anticoagulation and calcium channel blockers therapy. Since 1998, 11 patients had been treated with continuous endovenous epoprostenol, yet only 3 (27%) had significant clinical improvement. Survival at 5 years after diagnosis was 56%. At the end of study, 7 (70%) out of 10 patients who underwent pulmonary transplantation were alive (mean: 34, range: 3-62 months).

CONCLUSIONS

Pulmonary hypertension is a disease with a poor prognosis. However, treatment with prostaglandins and pulmonary transplantation may lead to encouraging results.