Pathologic regression of primary pulmonary hypertension in left native lung following right single-lung transplantation

Endothelial cell senescence exacerbates pulmonary hypertension by inducing juxtacrine Notch signaling in smooth muscle cells

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by a progressive increase in pulmonary artery pressure caused by pathological pulmonary artery remodeling. Here, we demonstrate that endothelial cell (EC) senescence plays a negative role in pulmonary hypertension via juxtacrine interaction with smooth muscle cells (SMCs). By using EC-specific progeroid mice, we discovered that EC progeria deteriorated vascular remodeling in the lungs, and exacerbated pulmonary hypertension in mice. Mechanistically, senescent ECs overexpressed Notch ligands, which resulted in increased Notch signaling and activated proliferation and migration capacities in neighboring SMCs. Pharmacological inhibition of Notch signaling reduced the effects of senescent ECs on SMCs functions in vitro, and improved the worsened pulmonary hypertension in EC-specific progeroid mice in vivo. Our findings show that EC senescence is a critical disease-modifying factor in PAH and that EC-mediated Notch signaling is a pharmacotherapeutic target for the treatment of PAH, particularly in the elderly.

Pulmonary artery pressure-directed therapies in pulmonary arterial hypertension?

Pulmonary arterial hypertension is a rare dyspnea-fatigue syndrome defined by an increase in mean pulmonary artery pressure above 20 mmHg combined with an increase in pulmonary vascular resistance higher than 2 Wood units. The condition is of poor prognosis and still incurable in spite of progress achieved in recent decades. The approach is currently optimized by multi-drug combinations titrated on serial risk assessments using recently validated scores. In this issue of Vascular Pharmacology argument is made based on retrospective registry data from three reference centers in favor of initial multi-drug therapies including a parenteral prostanoid dosed to decrease mPAP to normal. This objective was achieved in only a minority of patients, but improved outcome was demonstrated when mPAP can be brought to below 35 mmHg. This data suggest that pulmonary artery pressure-directed multi-drug therapies in PAH may reverse right heart remodeling and limit progression, or even reverse pulmonary vascular disease. However, further studies are needed to validate mPAP as a primary endpoint in PAH drug trials. In the meantime, aggressive initial prescription of parenteral prostanoids combined with one or two oral drugs targeting the pulmonary circulation under careful clinical, imaging and hemodynamic follow-up may be the best therapeutic strategy.

Aggressive Afterload Lowering to Improve the Right Ventricle: A New Target for Medical Therapy in Pulmonary Arterial Hypertension?

Despite numerous therapeutic advances in pulmonary arterial hypertension, patients continue to suffer high morbidity and mortality, particularly considering a median age of 50 years. This article explores whether early, robust reduction of right ventricular afterload would facilitate substantial improvement in right ventricular function and thus whether afterload reduction should be a treatment goal for pulmonary arterial hypertension. The earliest clinical studies of prostanoid treatment in pulmonary arterial hypertension demonstrated an important link between lowering mean pulmonary arterial pressure (or pulmonary vascular resistance) and improved survival. Subsequent studies of oral monotherapy or sequential combination therapy demonstrated smaller reductions in mean pulmonary arterial pressure and pulmonary vascular resistance. More recently, retrospective reports of initial aggressive prostanoid treatment or initial combination oral and parenteral therapy have shown marked afterload reduction along with significant improvements in right ventricular function. Some data suggest that reaching threshold levels for pressure or resistance (components of right ventricular afterload) may be key to interrupting the self-perpetuating injury of pulmonary vascular disease in pulmonary arterial hypertension and could translate into improved long-term clinical outcomes. Based on these clues, the authors postulate that improved clinical outcomes might be achieved by targeting significant afterload reduction with initial oral combination therapy and early parenteral prostanoids.

Distinct types of plexiform lesions identified by synchrotron-based phase-contrast micro-CT

In pulmonary arterial hypertension, plexiform lesions are associated with severe arterial obstruction and right ventricular failure. Exploring their structure and position is crucial for understanding the interplay between hemodynamics and vascular remodeling. The aim of this research was to use synchrotron-based phase-contrast micro-CT to study the three-dimensional structure of plexiform lesions. Archived paraffin-embedded tissue samples from 14 patients with pulmonary arterial hypertension (13 idiopathic, 1 with known BMPR2-mutation) were imaged. Clinical data showed high-median PVR (12.5 WU) and mPAP (68 mmHg). Vascular lesions with more than 1 lumen were defined as plexiform. Prior radiopaque dye injection in some samples facilitated 3-D rendering. Four distinct types of plexiform lesions were identified: 1) localized within or derived from monopodial branches (supernumerary arteries), often with a connection to the vasa vasorum; 2) localized between pulmonary arteries and larger airways as a tortuous transformation of intrapulmonary bronchopulmonary anastomoses; 3) as spherical structures at unexpected abrupt ends of distal pulmonary arteries; and 4) as occluded pulmonary arteries with recanalization. By appearance and localization, types 1-2 potentially relieve pressure via the bronchial circulation, as pulmonary arteries in these patients were almost invariably occluded distally. In addition, types 1-3 were often surrounded by dilated thin-walled vessels, often connected to pulmonary veins, peribronchial vessels, or the vasa vasorum. Collaterals, bypassing completely occluded pulmonary arteries, were also observed to originate within plexiform lesions. In conclusion, synchrotron-based imaging revealed significant plexiform lesion heterogeneity, resulting in a novel classification. The four types likely have different effects on hemodynamics and disease progression.

Hypoxia-induced pulmonary hypertension-Utilizing experiments of nature

An increase in pulmonary artery pressure is a common observation in adult mammals exposed to global alveolar hypoxia. It is considered a maladaptive response that places an increased workload on the right ventricle. The mechanisms initiating and maintaining the elevated pressure are of considerable interest in understanding pulmonary vascular homeostasis. There is an expectation that identifying the key molecules in the integrated vascular response to hypoxia will inform potential drug targets. One strategy is to take advantage of experiments of nature, specifically, to understand the genetic basis for the inter-individual variation in the pulmonary vascular response to acute and chronic hypoxia. To date, detailed phenotyping of highlanders has focused on haematocrit and oxygen saturation rather than cardiovascular phenotypes. This review explores what we can learn from those studies with respect to the pulmonary circulation. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.1/issuetoc.

A pro-con debate: current controversies in PAH pathogenesis at the American Thoracic Society International Conference in 2017

The following review summarizes the pro-con debate about current controversies regarding the pathogenesis of pulmonary arterial hypertension (PAH) that took place at the American Thoracic Society Conference in May 2017. Leaders in the field of PAH research discussed the importance of the immune system, the role of hemodynamic stress and endothelial apoptosis, as well as bone morphogenetic protein receptor-2 signaling in PAH pathogenesis. Whereas this summary does not intend to resolve obvious conflicts in opinion, we hope that the presented arguments entice further discussions and draw a new generation of enthusiastic researchers into this vibrant field of science to bridge existing gaps for a better understanding and therapy of this fatal disease.

How does pulmonary endarterectomy cure CTEPH: A clue to cure PAH?

Chronic thromboembolic pulmonary hypertension (CTEPH) is a hot topic in the field of pulmonary hypertension, because many CTEPH patients are now curable by surgical pulmonary endarterectomy and more recently possibly by pulmonary balloon angioplasty. However, there are still uncertainties regarding the pathogenesis of CTEPH, specifically how and where the small vessel arteriopathy that is indistinguishable from that in pulmonary arterial hypertension (plexogenic arteriopathy) develops, and how pulmonary endarterectomy improves hemodynamics and possibly cures CTEPH. Based on our recent experimental finding that hemodynamic stress is fundamental for the development of plexogenic arteriopathy, we discuss the uncertainties of CTEPH and potential implication of the effectiveness of pulmonary endarterectomy for reversing plexogenic arteriopathy and possibly providing a novel approach to cure pulmonary arterial hypertension.

Persistence of complex vascular lesions despite prolonged prostacyclin therapy of pulmonary arterial hypertension

AIMS

Continuous infusion of prostacyclin analogues improves survival in advanced pulmonary arterial hypertension. In addition to its vasodilatory effects, prostacyclin has the potential to decrease inflammation, thrombosis, and smooth muscle proliferation. The aim of this retrospective study was to determine whether pathological data support the ability of prostanoids to prevent progression of vascular disease.

METHODS AND RESULTS

Twenty-two autopsied patients with World Health Organization category 1 pulmonary arterial hypertension (primarily idiopathic and connective tissue disease-associated) were divided into those who received long-term prostacyclin (n = 12, PG-long, mean treatment 3.9 years) and those who received 0-1 month of prostacyclin (n = 10, PG-short). Surprisingly, PG-long patients had larger plexiform lesions (P < 0.05), with no decrease in medial and intimal thicknesses as compared with PG-short patients. Plexiform lesion size and density increased with increasing treatment time. Also, PG-long patients had fewer platelet thrombi and more frequent acute diffuse alveolar haemorrhage. Quantification of macrophages and T cells revealed no differences in inflammatory infiltrates.

CONCLUSION

Although long-term prostacyclin therapy may have an antithrombotic effect in addition to its vasodilatory actions, it was not associated with the prevention of advanced vascular lesions. The mechanism by which prostacyclin analogues improve survival in pulmonary arterial hypertension remains uncertain.

Persistence of complex vascular lesions despite prolonged prostacyclin therapy of pulmonary arterial hypertension

AIMS

Continuous infusion of prostacyclin analogues improves survival in advanced pulmonary arterial hypertension. In addition to its vasodilatory effects, prostacyclin has the potential to decrease inflammation, thrombosis, and smooth muscle proliferation. The aim of this retrospective study was to determine whether pathological data support the ability of prostanoids to prevent progression of vascular disease.

METHODS AND RESULTS

Twenty-two autopsied patients with World Health Organization category 1 pulmonary arterial hypertension (primarily idiopathic and connective tissue disease-associated) were divided into those who received long-term prostacyclin (n = 12, PG-long, mean treatment 3.9 years) and those who received 0-1 month of prostacyclin (n = 10, PG-short). Surprisingly, PG-long patients had larger plexiform lesions (P < 0.05), with no decrease in medial and intimal thicknesses as compared with PG-short patients. Plexiform lesion size and density increased with increasing treatment time. Also, PG-long patients had fewer platelet thrombi and more frequent acute diffuse alveolar haemorrhage. Quantification of macrophages and T cells revealed no differences in inflammatory infiltrates.

CONCLUSION

Although long-term prostacyclin therapy may have an antithrombotic effect in addition to its vasodilatory actions, it was not associated with the prevention of advanced vascular lesions. The mechanism by which prostacyclin analogues improve survival in pulmonary arterial hypertension remains uncertain.

Haemodynamic unloading reverses occlusive vascular lesions in severe pulmonary hypertension

AIMS

An important pathogenic mechanism in the development of idiopathic pulmonary arterial hypertension is hypothesized to be a cancer-like cellular proliferation independent of haemodynamics. However, because the vascular lesions are inseparably coupled with haemodynamic stress, the fate of the lesions is unknown when haemodynamic stress is eliminated.

METHODS AND RESULTS

We applied left pulmonary artery banding to a rat model with advanced pulmonary hypertension to investigate the effects of decreased haemodynamic stress on occlusive vascular lesions. Rats were given an injection of the VEGF blocker Sugen5416 and exposed to 3 weeks of hypoxia plus an additional 7 weeks of normoxia (total 10 weeks) (SU/Hx/Nx rats). The banding surgery to reduce haemodynamic stress to the left lung was done at 1 week prior to (preventive) or 5 weeks after (reversal) the SU5416 injection. All SU/Hx/Nx-exposed rats developed severe pulmonary hypertension and right ventricular hypertrophy. Histological analyses showed that the non-banded right lungs developed occlusive lesions including plexiform lesions with marked perivascular cell accumulation. In contrast, banding the left pulmonary artery not only prevented the development of but also reversed the established occlusive lesions as well as perivascular inflammation in the left lungs.

CONCLUSION

Our results indicate that haemodynamic stress is prerequisite to the development and progression of occlusive neointimal lesions in this rat model of severe pulmonary hypertension. We conclude that perivascular inflammation and occlusive neointimal arteriopathy are driven by haemodynamic stress.

Reconciling paradigms of abnormal pulmonary blood flow and quasi-malignant cellular alterations in pulmonary arterial hypertension

In pulmonary arterial hypertension (PAH) structural and functional abnormalities of the small lung vessels interact and lead to a progressive increase in pulmonary vascular resistance and right heart failure. A current pathobiological concept characterizes PAH as a 'quasi-malignant' disease focusing on cancer-like alterations in endothelial cells (EC) and the importance of their acquired apoptosis-resistant, hyper-proliferative phenotype in the process of vascular remodeling. While changes in pulmonary blood flow (PBF) have been long-since recognized and linked to the development of PAH, little is known about a possible relationship between an altered PBF and the quasi-malignant cell phenotype in the pulmonary vascular wall. This review summarizes recognized and hypothetical effects of an abnormal PBF on the pulmonary vascular bed and links these to quasi-malignant changes found in the pulmonary endothelium. Here we describe that abnormal PBF does not only trigger a pulmonary vascular cell growth program, but may also maintain the cancer-like phenotype of the endothelium. Consequently, normalization of PBF and EC response to abnormal PBF may represent a treatment strategy in patients with established PAH.

Reverse remodeling of pulmonary arteries by high-dose prostaglandin I2 therapy: A case report

Idiopathic pulmonary arterial hypertension (IPAH) is characterized by pulmonary vascular remodeling. We have reported that high-dose prostaglandin I₂ (PGI₂) therapy markedly improved hemodynamics in IPAH patients and that PGI₂ induced apoptosis of pulmonary artery smooth muscle cells obtained from IPAH patients. PGI₂ is thought to have reverse remodeling effects, although it has not been histologically confirmed. In a case series, we examined the reverse pulmonary vascular remodeling effects of PGI₂ in lung tissues obtained from an IPAH patient treated with high-dose PGI₂ and an IPAH patient not treated with PGI₂. Apoptotic cells were detected in small pulmonary arteries of the IPAH patient treated with high-dose PGI₂ but not in those from the IPAH patient not treated with PGI₂. Media of peripheral pulmonary arteries were thick in the IPAH patient not treated with PGI₂. On the other hand, media of peripheral pulmonary arteries were thin in the IPAH patient treated with high-dose PGI₂. The single case report suggested that high-dose PGI₂ therapy has the potential for reverse pulmonary vascular remodeling by induction of apoptosis and reduction of medial hypertrophy. Accumulation of cases is needed for the application to generalized effect of high-dose PGI₂. <Learning objective: Reverse pulmonary vascular remodeling would provide further improvement in patients with IPAH. High-dose PGI₂ therapy has the potential for reverse pulmonary vascular remodeling in patients with IPAH.>.

Initial and programmed combination therapy with oral drugs for severe idiopathic pulmonary arterial hypertension

A 49-year-old woman suffering from rapidly progressing right-sided heart failure assessed as World Health Organization functional class (WHO-FC) IV is described. After treatment with oxygen and diuretics, she was in WHO-FC III on admission to our hospital, as confirmed by her poor exercise tolerance in cardiopulmonary exercise testing. Upon detailed examination, she was diagnosed as having idiopathic pulmonary arterial hypertension (IPAH). Right heart catheterization (RHC) revealed severe pulmonary hypertension (mPAP = 65 mmHg) with a markedly decreased cardiac index (CI = 1.0 L/minute/m(2)), and an acute vasoreactivity test with nitric oxide inhalation did not show any response. Due to her severe condition, we decided to attempt oral combination therapy consisting of bosentan, tadalafil, and beraprost, prescribed in the same order and titrated up to their maximum respective doses, instead of intravenous (IV) epoprostenol therapy. Her clinical symptoms improved day by day, and the hemodynamic parameters recovered to nearly normal ranges about 6 months after initiation of the combination therapy. Initial/programmed oral combination therapy for severe IPAH patients is not yet fully established, and there is less evidence concerning its efficacy than IV epoprostenol therapy. However, it has tremendous advantages for PAH patients when they respond well. It is very important to further identify what types of PAH patients will respond to this oral combination therapy and should be treated with it as the first-line therapy.

Long-term effects of epoprostenol on the pulmonary vasculature in idiopathic pulmonary arterial hypertension

The current treatment of pulmonary arterial hypertension (PAH) uses vasodilator drugs. Although they improve symptoms associated with PAH, their chronic effects on the pulmonary vasculature and the right ventricle (RV) in humans remain unknown. We report the autopsy findings from a patient with idiopathic PAH treated with epoprostenol successfully for 18 years. The patient died of colon cancer. The pulmonary vasculature surprisingly showed extensive changes of a proliferative vasculopathy. Immunohistochemical studies confirmed ongoing cellular proliferation. Studies of the RV demonstrated concentric hypertrophy with seemingly preserved contractility. The myocardium shifted to glycolytic metabolism. Although the long-term use of epoprostenol contributed to the patient's increased survival, it did not prevent progression of the underlying vascular disease. Remarkably, the RV was able to sustain a normal cardiac output in the face of advanced vascular pathology. The mechanisms by which the RV adapts to chronic PAH need further study.

Prednisolone inhibits PDGF-induced nuclear translocation of NF-kappaB in human pulmonary artery smooth muscle cells

Pulmonary vascular remodeling, a major cause for the elevated pulmonary vascular resistance in patients with pulmonary arterial hypertension (PAH), is partially due to increased proliferation of pulmonary arterial smooth muscle cells (PASMC) in the media, resulting in vascular wall thickening. Platelet-derived growth factor (PDGF) is a potent mitogen that may be involved in the progression of PAH. Blockade of PDGF receptors has been demonstrated to have therapeutic potential for patients with severe pulmonary hypertension. Prednisolone is an immunosuppressant shown to have anti-inflammatory and antiproliferative effects on PASMC. This study was designed to investigate whether PDGF and prednisolone affect human PASMC proliferation by regulating the nuclear translocation of NF-kappaB (a transcription factor composed of 2 subunits, p50 and p65). Treatment of human PASMC with PDGF (10 ng/ml) significantly increased nuclear translocation of p50 and p65 subunits. Inhibition of NF-kappaB activation or nuclear translocation of p50/p65 significantly attenuated PDGF-induced PASMC proliferation (determined by [(3)H]thymidine incorporation). In the presence of prednisolone (200 microM), the PDGF-induced nuclear translocation of p50 and p65 subunits was markedly inhibited (P < 0.05 vs. the cells treated with PDGF alone). These results indicate that PDGF-induced nuclear translocation of NF-kappaB may play an important role in stimulating PASMC proliferation (and/or enhancing PASMC survival), whereas prednisolone may exert anti-inflammatory and antiproliferative effects on PASMC by inhibiting NF-kappaB nuclear translocation.

The Current Treatment of Pulmonary Arterial Hypertension

In the past decade, three classes of medications have been approved for the treatment of pulmonary arterial hypertension. A review of the clinical trial data for the prostanoids, endothelin antagonists, and phosphodiesterase-5 inhibitors has shown that all agents have similar efficacy on the 6-min walk distance over 12 to 16 weeks, which was the primary end point in the randomized clinical trials. However, little is known about their long-term efficacy or about how these drugs affect the underlying disease, if at all. Successful therapy is currently defined as an improvement in exercise tolerance over a 4-month period. Future trials need to better characterize how therapies affect the pulmonary vasculature pathologically, biologically, and hemodynamically, and whether survival is actually improved.

Reversal of idiopathic pulmonary arterial hypertension and allograft pneumonectomy after single lung transplantation

Prior to the advent of effective medical therapies, the only treatment option for patients with idiopathic pulmonary arterial hypertension (IPAH) was lung transplantation. We present the case of a woman who underwent single-lung transplantation for the treatment of IPAH > 10 years ago in whom chronic rejection developed. Despite complete obliteration of the allograft, it was noted that her PA pressure levels had almost normalized. Therefore, an allograft pneumonectomy was performed. To our knowledge, this is the first reported case of the regression of pulmonary vascular disease following lung transplantation with subsequent successful removal of the allograft.

Prednisolone inhibits proliferation of cultured pulmonary artery smooth muscle cells of patients with idiopathic pulmonary arterial hypertension

BACKGROUND

Idiopathic pulmonary arterial hypertension (IPAH) is associated with proliferation of smooth muscle cells (SMCs) in small pulmonary arteries. There is no therapy that specifically inhibits SMC proliferation. Recent studies reported that prednisolone (PSL) inhibits the postangioplasty proliferation of SMCs in atherosclerotic arteries. In this study, we tested the hypothesis that PSL has antiproliferative effects on pulmonary artery SMCs of patients with IPAH.

METHODS AND RESULTS

Pulmonary artery SMCs were harvested from the pulmonary arteries of 6 patients with IPAH who underwent lung transplantation. Control SMCs were obtained from 5 patients with bronchogenic carcinoma who underwent lung lobectomy. After incubation in the presence of platelet-derived growth factor (PDGF), PSL was added at different concentrations and cell proliferation was assessed by 3H-thymidine incorporation. PSL (2x10(-4) and 2x10(-3) mol/L) significantly inhibited PDGF-stimulated proliferation (P<0.05) of SMCs from patients with IPAH but did not affect cell viability of SMCs, as confirmed by trypan blue staining. In cell cycle analysis using a microscope-based multiparameter laser scanning cytometer, PSL inhibited the progression of SMCs from G(0)/G1 to the S phase. This inhibition was associated with increased p27 expression level. PSL (2x10(-4) mol/L) also inhibited PDGF-induced SMC migration.

CONCLUSIONS

Our results indicate that PSL has an antiproliferative effect on cultured SMCs of pulmonary arteries from patients with IPAH and suggest that PSL may be potentially useful therapeutically in patients with IPAH.

Transplantation of Endothelial Progenitor Cells into the Lung to Alleviate Pulmonary Hypertension in Dogs

Primary pulmonary hypertension (PPH) is still a refractory disease, and patients deteriorate despite any treatment. We hypothesized that neovascularization in the lung could increase the volume of the vascular bed in the pulmonary circulation and thus reduce the development of pulmonary hypertension (PH). Endothelial progenitor cells (EPCs) might be a potential cell source for neovascularization. We examined the effects of EPC transplantation into the lungs of dogs with dehydromonocrotaline-induced PH. The lung parenchyma of PH model dogs was injected with ex vivo-expanded, autologous EPCs originated from peripheral blood (experiments, n=4) or culture medium (control, n=3), using a bronchoscope. EPC transplantation gave significant improvements in mean pulmonary artery pressure, cardiac output, and pulmonary vascular resistance. Histological evaluation revealed both improvement in the medial thickness of the small pulmonary artery and neovascularization of the lung tissue. These results indicate that EPC transplantation into the lung is effective at preventing the progression of dehydromonocrotaline-induced PH in dogs, and suggest a new therapeutic option for PPH.

Twenty-year experience of lung transplantation at a single center: influence of recipient diagnosis on long-term survival

OBJECTIVES

The objective of this study was to examine the long-term patient outcomes of lung transplantation in a single center.

METHODS

Between 1983 and 2003, 521 lung transplants were performed in 501 patients. Major indications were cystic fibrosis (n = 124), chronic obstructive pulmonary disease (n = 88), alpha-1 antitrypsin deficiency (n = 63), pulmonary fibrosis (n = 97), primary pulmonary hypertension (n = 35), Eisenmenger syndrome (n = 21), and miscellaneous end-stage lung diseases (n = 93).

RESULTS

The 5-, 10-, and 15-year survivals for all recipients were 55.1% (95% confidence interval: +/-5%), 35.3% (+/-6%), and 26.5% (+/-11%), respectively. The most common causes of death were sepsis and bronchiolitis obliterans syndrome. Despite an increased postoperative mortality rate, patients with primary pulmonary hypertension achieved the best long-term survival (10-year survival: 59%). Recipients with cystic fibrosis without Burkholderia cepacia infection achieved significantly better long-term survival (10-year survival: 52%) than those with Burkholderia cepacia infection (10-year survival: 15%). The 10-year survival was also significantly better in recipients with chronic obstructive pulmonary disease (43%) than in recipients with alpha-1 antitrypsin deficiency (23%). Although the incidence of bronchiolitis obliterans syndrome was similar between recipients with chronic obstructive pulmonary disease (39%) and alpha-1 antitrypsin deficiency (46%), recipients with alpha-1 antitrypsin deficiency died of sepsis more frequently than recipients with chronic obstructive pulmonary disease (27% vs 6%, respectively; P =.0003).

CONCLUSIONS

Although bronchiolitis obliterans syndrome and sepsis still limit the durability of the benefit, lung transplantation returns many patients with end-stage lung disease to active and productive lives. Differences in the complications and long-term survival show the important contribution of the recipient diagnosis to the success of lung transplantation.