Computer grading of lung disease severity in patients with lymphangioleiomyomatosis referred for transplantation

Objectives

Lymphangioleiomyomatosis (LAM) patients with severe lung disease may be considered for lung transplantation. Clinical, physiologic, and quality of life data are usually employed for referral. The aim of this study was to determine whether computed tomographic measurement of lung volume occupied by cysts (cyst score) complemented clinical and physiologic data in supporting referral for transplantation.

Methods

Forty-one patients were studied. Pre-referral clinical data, pulmonary function tests, exercise testing, and high-resolution computed tomography (HRCT) scans were obtained. From HRCT, a computer-aided diagnostic program was employed to calculate cyst scores. These data were compared to those of 41 age-matched LAM patients not referred for lung transplantation.

Results

Cyst score, and % predicted FEV1 and DLCO were respectively, 48.1 ± 9.4%, 36.5 ± 9.1%, and 35.0 ± 10.7%. For the control group, cyst score, FEV1, and DLCO were respectively, 14.8 ± 8.3%, 77.2 ± 20.3%, and 66.7 ± 19.3%. Cyst score values showed a normal distribution. However, the frequency distribution of FEV1 was skewed to the right while the distribution of DLCO was bimodal. Correlations between cyst score and FEV1 and DLCO for the study group were respectively, r = − 0.319 and r = − 0.421.

Conclusions

LAM patients referred for lung transplantation had nearly 50% of lungs occupied by cysts. Correlations between cyst score and FEV1 or DLCO were weak; as shown previously, DLCO was better related to cyst number while FEV1 had a better association with cyst size. Given its normal distribution, cyst score measurements may assist in evaluation of pre-transplant severity of lung disease before referral for transplantation.

Pregnancy in lymphangioleiomyomatosis: clinical and lung function outcomes in two national cohorts

Pregnancy in women with lymphangioleiomyomatosis (LAM) has been associated with increased complications and worsening lung function although objective data to advise patients are not available. We assessed lung function and CT scans before and after pregnancy in 16 women with LAM. During the pregnancy, pneumothorax was frequent and mean forced expiratory volume in 1 s (FEV₁) fell from 77%±19% prepregnancy to 64%±25% predicted and DL_CO from 66±26 to 57±26 (both p<0.01). After pregnancy, rates of FEV₁ decline were high and 10 patients required sirolimus. Women with LAM, especially with moderate or advanced disease should be counselled regarding adverse events and loss of lung function during the pregnancy.

Analysis of the MILES cohort reveals determinants of disease progression and treatment response in lymphangioleiomyomatosis

INTRODUCTION

The Multicenter International Lymphangioleiomyomatosis (LAM) Efficacy of Sirolimus (MILES) trial revealed that sirolimus stabilised lung function in patients with moderately severe LAM. The purpose of this study was to further examine the MILES cohort for the effects of racial, demographic, clinical and physiological patient characteristics on disease progression and treatment response in LAM.

METHODS

MILES subjects were stratified on the basis of menopausal status (pre-menopausal/post-menopausal), race (Asian/Caucasian), bronchodilator responsiveness (present/absent), initial forced expiratory volume in 1 s (FEV₁; 51-70% versus ≤50% predicted) and tuberous sclerosis complex (TSC) association (yes/no). A linear mixed effects model was used to compare slope differences, and nonparametric tests were used to compare medians and proportions between treatment groups in each stratum.

RESULTS

In the MILES placebo group, pre-menopausal patients declined 5-fold faster than post-menopausal patients (mean±se FEV₁ slope -17±3 versus -3±3 mL·month^-1; p=0.003). Upon treatment with sirolimus, both the pre-menopausal (-17±3 versus -1±2 mL·month^-1; p<0.0001) and post-menopausal patients (-3±3 versus 6±3 mL·month^-1; p=0.04) exhibited a beneficial response in mean±se FEV₁ slope compared with the placebo group. Race, LAM subtype, bronchodilator responsiveness or baseline FEV₁ did not impact the rate of disease progression in the placebo group or treatment response in the sirolimus group. Menopausal status and race had differential effects on the adverse event profile of sirolimus. Baseline serum vascular endothelial growth factor (VEGF)-D >600 pg·mL^-1 identified subgroups of patients who were more likely to decline on placebo and respond to treatment with sirolimus.

CONCLUSIONS

In LAM patients, treatment with sirolimus is beneficial regardless of menopausal status, race, bronchodilator responsiveness, baseline FEV₁ or TSC association. Serum VEGF-D and menopausal status can help inform therapeutic decisions.

Use of CT Imaging to Quantify Progression and Response to Treatment in Lymphangioleiomyomatosis

BACKGROUND

In lymphangioleiomyomatosis (LAM), infiltration of the lungs with smooth muscle-like LAM cells results in cystic destruction and decline in lung function, effects stabilized by sirolimus therapy. LAM lung disease is followed, in part, by high-resolution CT scans. To obtain further information from these scans, we quantified changes in lung parenchyma by analyzing image "texture."

METHODS

Twenty-six texture properties were quantified by analyzing the distribution and intensity of pixels with a computer-aided system. Both cross-sectional and longitudinal studies were performed to examine the relationships between texture properties, cyst score (percentage of lung occupied by cysts), FEV₁, and diffusion capacity for carbon monoxide (Dlco), and to determine the effect of sirolimus treatment.

RESULTS

In the cross-sectional study, 18 texture properties showed significant positive correlations with cyst score. Cyst score and 13 of the 18 texture properties showed significant differences in rates of change after sirolimus treatment; 11 also significantly predicted FEV₁ and Dlco.

CONCLUSIONS

Increased cyst score was associated with increased texture degradation near cysts. Sirolimus treatment improved lung texture surrounding cysts and stabilized cyst score. Eleven texture properties were associated with FEV₁, Dlco, cyst score, and response to sirolimus. Texture analysis may be valuable in evaluating LAM severity and treatment response.

Expanding the phenotype of COPA syndrome: a kindred with typical and atypical features

Background

Copa syndrome is a rare autosomal dominant disorder with abnormal intracellular vesicle trafficking. The objective of this work is to expand the knowledge about this disorder by delineating phenotypic features of an unreported COPA family.

Methods and results

A heterozygous missense variant (c.698 G>A, p.Arg233His) in COPA was identified in four members of a three-generation kindred with lung, autoimmune and malignant disease of unknown aetiology. Ages of onset were 56, 26, 16 and 1 year, with earlier age of onset in successive generations. Presenting symptoms were cough and dyspnoea. Findings included small lung cysts, follicular bronchiolitis, interstitial lung disease, neuroendocrine cell hyperplasia, rheumatoid arthritis, avascular necrosis and select abnormal autoimmune serologies. Neither alveolar haemorrhage nor glomerular disease were present. Features not previously associated with Copa syndrome included neuromyelitis optica, pulmonary carcinoid tumour, clear cell renal carcinoma, renal cysts, hepatic cysts, nephrolithiasis, pyelonephritis and meningitis. Longitudinal evaluations demonstrated slow progression of lung disease and extrapulmonary cysts.

Conclusions

Worsening severity with successive generations may be observed in Copa syndrome. Extrapulmonary cysts, malignancies, autoimmune neurological disorders and infections are clinical features that may be associated with Copa syndrome. Further studies are indicated to fully define the phenotypic spectrum of this disorder.

The NHLBI LAM Registry: Prognostic Physiologic and Radiologic Biomarkers Emerge From a 15-Year Prospective Longitudinal Analysis

BACKGROUND

The natural history of lymphangioleiomyomatosis (LAM) is mainly derived from retrospective cohort analyses, and it remains incompletely understood. A National Institutes of Health LAM Registry was established to define the natural history and identify prognostic biomarkers that can help guide management and decision-making in patients with LAM.

METHODS

A linear mixed effects model was used to compute the rate of decline of FEV₁ and to identify variables affecting FEV₁ decline among 217 registry patients who enrolled from 1998 to 2001. Prognostic variables associated with progression to death/lung transplantation were identified by using a Cox proportional hazards model.

RESULTS

Mean annual decline of FEV₁ was 89 ± 53 mL/year and remained remarkably constant regardless of baseline lung function. FEV₁ decline was more rapid in those with greater cyst profusion on CT scanning (P = .02) and in premenopausal subjects (118 mL/year) compared with postmenopausal subjects (74 mL/year) (P = .003). There were 26 deaths and 43 lung transplantations during the evaluation period. The estimated 5-, 10-, 15-, and 20-year transplant-free survival rates were 94%, 85%, 75%, and 64%, respectively. Postmenopausal status (hazard ratio, 0.30; P = .0002) and higher baseline FEV₁ (hazard ratio, 0.97; P = .008) or diffusion capacity of lung for carbon monoxide (hazard ratio, 0.97; P = .001) were independently associated with a lower risk of progression to death or lung transplantation.

CONCLUSIONS

The median transplant-free survival in patients with LAM is > 20 years. Menopausal status, as well as structural and physiologic markers of disease severity, significantly affect the rate of decline of FEV₁ and progression to death or lung transplantation in LAM.

Rates of change in FEV1 and DLCO as potential indicators for mTOR inhibitor therapy in premenopausal lymphangioleiomyomatosis patients

The value of rates of change in forced expiratory volume in 1 s (FEV₁) and diffusing capacity of the lung for carbon monoxide (D_LCO) to predict disease progression, and initiation of mTOR (mechanistic target of rapamycin) inhibitor therapy has not been evaluated.In 84 premenopausal lymphangioleiomyomatosis patients, individual rates of change in FEV₁ and D_LCO and their 95% confidence intervals were used to derive subsequent lowest values of FEV₁ and D_LCO that would prompt initiation of sirolimus therapy. These treatment criteria were compared with a criterion based on FEV₁ or D_LCO ≤70% predicted. In 12 patients undergoing sirolimus therapy both methods for determining the optimal point for initiation of therapy were evaluated.27 and 35 patients who experienced greater than expected rates of change in FEV₁ and D_LCO, respectively, would have been excluded from therapy based on an FEV₁ or D_LCO >70% pred. 25 of the 84 patients were eventually treated, but only when FEV₁ or D_LCO were ≤70% pred. Applying such treatment criteria to 12 patients undergoing sirolimus therapy would have delayed treatment for many years.Premenopausal females in whom FEV₁ or D_LCO are declining at rates above the expected based on their individual rates of decline, should be considered for sirolimus therapy before the FEV₁ or D_LCO falls to ≤70% pred.

Mounier-Kuhn Syndrome Mimicking Lymphangioleiomyomatosis

We present the case of a man with Mounier-Kuhn syndrome (MKS), or tracheobronchomegaly, who was referred to the National Institutes of Health Clinical Research Center because of a potential diagnosis of lymphangioleiomyomatosis (LAM), a rare condition in men. The patient was evaluated using ongoing protocols and provided written informed consent. The case demonstrates the presence of chronic inflammation surrounding the dilated airways and histologic changes of the lung parenchyma with emphysematouslike disruption in areas adjacent to the dilated airways. This finding suggests that damage to the lung parenchyma is an ongoing phenomenon in MKS. Moreover, our analysis of CT images indicates similar abnormalities in areas remote from the dilated airways. Finally, because of increased anatomic dead space, calculation of lung diffusion capacity by the single-breath method yielded abnormally low values that required making a correction for the large anatomic dead space, which can be measured by the single-breath nitrogen washout test.

Lymphangioleiomyomatosis Diagnosis and Management: High-Resolution Chest Computed Tomography, Transbronchial Lung Biopsy, and Pleural Disease Management. An Official American Thoracic Society/Japanese Respiratory Society Clinical Practice Guideline

BACKGROUND

Recommendations regarding key aspects related to the diagnosis and pharmacological treatment of lymphangioleiomyomatosis (LAM) were recently published. We now provide additional recommendations regarding four specific questions related to the diagnosis of LAM and management of pneumothoraces in patients with LAM.

METHODS

Systematic reviews were performed and then discussed by a multidisciplinary panel. For each intervention, the panel considered its confidence in the estimated effects, the balance of desirable (i.e., benefits) and undesirable (i.e., harms and burdens) consequences, patient values and preferences, cost, and feasibility. Evidence-based recommendations were then formulated, written, and graded using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach.

RESULTS

For women who have cystic changes on high-resolution computed tomography of the chest characteristic of LAM, but who have no additional confirmatory features of LAM (i.e., clinical, radiologic, or serologic), the guideline panel made conditional recommendations against making a clinical diagnosis of LAM on the basis of the high-resolution computed tomography findings alone and for considering transbronchial lung biopsy as a diagnostic tool. The guideline panel also made conditional recommendations for offering pleurodesis after an initial pneumothorax rather than postponing the procedure until the first recurrence and against pleurodesis being used as a reason to exclude patients from lung transplantation.

CONCLUSIONS

Evidence-based recommendations for the diagnosis and treatment of patients with LAM are provided. Frequent reassessment and updating will be needed.

Official American Thoracic Society/Japanese Respiratory Society Clinical Practice Guidelines: Lymphangioleiomyomatosis Diagnosis and Management

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a rare cystic lung disease that primarily affects women. The purpose of these guidelines is to provide recommendations for the diagnosis and treatment of LAM.

METHODS

Systematic reviews were performed to summarize evidence pertinent to our questions. The evidence was summarized and discussed by a multidisciplinary panel. Evidence-based recommendations were then formulated, written, and graded using the Grading of Recommendations, Assessment, Development, and Evaluation approach.

RESULTS

After considering the panel's confidence in the estimated effects, the balance of desirable (i.e., benefits) and undesirable (i.e., harms and burdens) consequences of treatment, patient values and preferences, cost, and feasibility, recommendations were formulated for or against specific interventions. These included recommendations for sirolimus treatment and vascular endothelial growth factor D testing and recommendations against doxycycline and hormonal therapy.

CONCLUSIONS

Evidence-based recommendations for the diagnosis and treatment of patients with LAM are provided. Frequent reassessment and updating will be needed.

Long-Term Effect of Sirolimus on Serum Vascular Endothelial Growth Factor D Levels in Patients With Lymphangioleiomyomatosis

BACKGROUND

Sirolimus reduces serum levels of vascular endothelial growth factor D (VEGF-D); the size of chylous effusions, lymphangioleiomyomas, and angiomyolipomas; and stabilizes lung function in patients with lymphangioleiomyomatosis (LAM).

METHODS

To determine whether reductions in VEGF-D levels are sustained over time, as well as parallel changes in lung function and lymphatic disease, we evaluated 25 patients with LAM and measured VEGF-D levels, lung function, and extent of lymphatic disease before and during sirolimus therapy.

RESULTS

Treatment with sirolimus stabilized FEV₁ and diffusion capacity for carbon monoxide (Dlco) over a period of 4.5 ± 1.6 years, caused resolution of lymphatic disease, and reduced the size of angiomyolipomas and VEGF-D levels (3,720 ± 3,020 pg/mL to 945 ± 591 pg/mL; P < .0001). Yearly changes in FEV₁ % predicted and Dlco % predicted were reduced from -7.4% ± 1.4% to -0.3% ± 0.5% (P < .001) and -6.4% ± 0.9% to -0.4% ± 0.5% (P < .001), respectively. Lower VEGF-D levels correlated with sirolimus therapy (P < .001), but no significant relationship was observed between reduction in VEGF-D levels and FEV₁ and Dlco during sirolimus therapy. The magnitude of VEGF-D decline was not related to the effect on lung function. Patients with lymphatic disease had higher serum VEGF-D levels, a greater reduction in VEGF-D levels, and better long-term sustained improvement in lung function during sirolimus therapy than did those without lymphatic disease.

CONCLUSIONS

Sirolimus therapy stabilizes lung function over many years of therapy while producing a sustained reduction in VEGF-D levels in patients with elevated levels preceding therapy. An association was not demonstrated between the magnitude of VEGF-D decline and the beneficial effect of sirolimus on lung function. Persistent improvement in lung function was observed in patients with lymphatic disease.

Serum VEGF-D a concentration as a biomarker of lymphangioleiomyomatosis severity and treatment response: a prospective analysis of the Multicenter International Lymphangioleiomyomatosis Efficacy of Sirolimus (MILES) trial

BACKGROUND

VEGF-D is a lymphangiogenic growth factor that has a key role in tumour metastasis. Serum VEGF-D concentrations are increased in most patients with lymphangioleiomyomatosis, a rare neoplasm associated with mTOR-activating tuberous sclerosis gene mutations, lymphadenopathy, metastatic spread, and pulmonary cyst formation. We used data from the Multicenter International Lymphangioleiomyomatosis Efficacy of Sirolimus (MILES) trial to assess the usefulness of serum VEGF-D concentration as a marker of severity and therapeutic response to sirolimus in patients with lymphangioleiomyomatosis.

METHODS

In the MILES trial, patients with lymphangioleiomyomatosis who had forced expiratory volume in 1 second (FEV1) of 70% or less of predicted were randomly assigned (1:1) to 12 months masked treatment with sirolimus or placebo. Serum VEGF-D concentrations were measured at baseline, 6 months, and 12 months. We used a linear regression model to assess associations of baseline VEGF-D concentrations with markers of disease severity, and a linear mixed effects model to assess the associations of VEGF-D concentrations with between-group differences in clinical, physiological, and patient-reported outcomes.

FINDINGS

We included 42 patients from the placebo group and 45 from the sirolimus group in our analysis. Baseline VEGF-D concentrations in individual patients varied from 0·34 ng/mL to 16·7 ng/mL. Baseline VEGF-D concentrations were higher in patients who needed supplemental oxygen than in those who did not need supplemental oxygen (1·7 ng/mL [IQR 0·99–3·36] vs 0·84 ng/mL [0·52–1·39]; p<0·0001) and in those who had a bronchodilator response than in those who did not (2·01 ng/mL [0·99–2·86] vs 1·00 ng/mL [0·61–2·15]; 0·0273). Median serum VEGF-D concentrations were similar at baseline in the sirolimus and placebo groups, and fell from baseline at 6 and 12 months in the sirolimus group but remained roughly stable in the placebo group. Each one-unit increase in baseline log(VEGF-D) was associated with a between-group difference in baseline-to-12-month FEV1 change of 134 mL (p=0·0007). In the sirolimus group, improvement in baseline-to-12-month FEV1 occurred in 15 of 23 (65%) VEGF-D responders (ie, those in whom baseline-to-12-month VEGF-D concentrations decreased by more than they did in any patients in the placebo group) and four of 15 (27%) VEGF-D non-responders (p=0·0448).

INTERPRETATION

Serum VEGF-D is a biologically plausible and useful biomarker in lymphangioleiomyomatosis that correlates with disease severity and treatment response. Measurement of serum VEGF-D concentrations could inform the risk–benefit analysis of sirolimus therapy in patients with lymphangioleiomyomatosis and reduce the numbers of patients needed for clinical trials.

FUNDING

National Institutes of Health, US Department of Defense.

Incidence of Pneumothorax in Patients With Lymphangioleiomyomatosis Undergoing Pulmonary Function and Exercise Testing

Because pneumothorax is frequent in lymphangioleiomyomatosis, patients have expressed concerns regarding the risk of pneumothorax associated with pulmonary function or exercise testing. Indeed, pneumothorax has been reported in patients with lung disease after both of these tests. The aim of this study was to determine the incidence of pneumothorax in patients with lymphangioleiomyomatosis during admissions to the National Institutes of Health Clinical Research Center between 1995 and 2015. Medical records were reviewed to identify patients who had a pneumothorax during their stay at the National Institutes of Health. A total of 691 patients underwent 4,523 pulmonary function tests and 1,900 exercise tests. Three patients developed pneumothorax after pulmonary function tests and/or exercise tests. The incidence of pneumothorax associated with lung function testing was 0.14 to 0.29 of 100 patients or 0.02 to 0.04 of 100 tests. The incidence of pneumothorax in patients undergoing exercise testing was 0.14 to 0.28 of 100 patients or 0.05 to 0.10 of 100 tests. The risk of pneumothorax associated with pulmonary function or exercise testing in patients with lymphangioleiomyomatosis is low.

Benign Metastasizing Leiomyoma

Benign metastasizing leiomyoma (BML) is a rare and poorly characterized disease affecting primarily premenopausal women. Asymptomatic patients are often diagnosed incidentally by radiographs or other lung-imaging procedures performed for other indications, and the diagnosis is eventually confirmed by biopsy. Patients with BML are usually treated pharmacologically with antiestrogen therapies or surgically with oophorectomy or hysterectomy. Antiestrogen therapy is typically efficacious and, in general, most patients have a favorable prognosis. Asymptomatic patients with a confirmed diagnosis of BML, may be followed conservatively without treatment.

EPIDEMIOLOGY, PATHOGENESIS and DIAGNOSIS of LYMPHANGIOLEIOMYOMATOSIS

INTRODUCTION

Lymphangioleiomyomatosis (LAM) is a disease of women characterized by cystic lung destruction, lymphatic involvement, and renal angiomyolipomas.

AREAS COVERED

LAM is caused by proliferation of abnormal smooth muscle-like LAM cells containing mutations and perhaps epigenetic modifications of the TSC1 or TSC2 genes, which encode, respectively, hamartin and tuberin, two proteins controlling the mechanistic target of rapamycin (mTOR) signaling pathway. LAM occurs sporadically or in association with tuberous sclerosis complex. LAM may present with dyspnea, recurrent pneumothorax or chylothorax. Pulmonary function tests show reduced flow rates and lung diffusion capacity. Exercise testing may reveal hypoxemia and ventilatory limitation. The severity and progression of disease may be assessed by computer tomography, and pulmonary function and exercise testing. mTOR inhibitors, (e.g., sirolimus) are effective in stabilizing lung function, and reducing the size of chylous effusions, lymphangioleiomyomas, and angiomyolipomas.

EXPERT OPINION

Different clinical phenotypes including variable rates of disease progression and variable responses to therapy are seen in LAM patients. No one test is available that predicts the course of disease at the time of diagnosis. Further research regarding the molecular biology of LAM clinical phenotypes is warranted. Recent advances in the characterization of the pathogenesis of LAM are leading to the development of new therapies.

Effect of fasting on the size of lymphangioleiomyomas in patients with lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomas occur in 38% of patients with sporadic lymphangioleiomyomatosis (LAM) and may cause pain and increased abdominal girth, mimicking the presence of a malignancy. Lymphatic involvement in LAM is closely associated with elevated serum levels of vascular endothelium growth factor-D (VEGF-D). Because lymphangioleiomyomas undergo diurnal variation in volume, we hypothesized that daytime ingestion of food, by increasing chyle formation and lymphatic flow, is the cause of an increase in lymphangioleiomyoma volume.

METHODS

Subjects had abdominopelvic sonograms and blood drawn for measurement of serum VEGF-D levels under nonfasting (day 1) and fasting (day 2) conditions. The size of the lymphangioleiomyomas was determined by a radiologist who was blinded to the subjects' status. The Wilcoxon signed rank test was used to determine whether the nonfasting tumor size was different from the fasting tumor size.

RESULTS

Thirty-five women were studied (aged 45.2 ± 8.5 years; FEV1, 82% ± 25%; diffusing capacity of the lung for carbon monoxide, 64% ± 25% predicted). Images suitable for volume measurements were obtained in 30 subjects. Fasting decreased the tumor size by 20.7 ± 39.3 cm3 (24% ± 40%, P < .001). Fasting VEGF-D levels (10,650 ± 900 pg/mL) were not significantly different from nonfasting values (12,100 ± 800 pg/mL, P = .56).

CONCLUSIONS

Lymphangioleiomyoma volume decreased during the fasting state. Conversely, a combination of food intake and decreased chyle flow through lymphatics partially obstructed by LAM cells may account for increases in lymphangioleiomyoma size. Imaging studies performed under fasting conditions may help in determining whether an abdominal tumor is a result of LAM or malignancy.

Clinical features, epidemiology, and therapy of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a multisystem disease of women, characterized by proliferation of abnormal smooth muscle-like LAM cells, leading to the formation of lung cysts, fluid-filled cystic structures in the axial lymphatics (eg, lymphangioleiomyomas), and renal angiomyolipomas. LAM is caused by mutations of the TSC1 or TSC2 genes, which encode, respectively, hamartin and tuberin, two proteins with a major role in control of the mammalian target of rapamycin (mTOR) signaling pathway. LAM occurs sporadically or in association with tuberous sclerosis complex, an autosomal-dominant syndrome characterized by widespread hamartomatous lesions. LAM may present with progressive dyspnea, recurrent pneumothorax, or chylothorax. Pulmonary function tests show reduced flow rates (forced expiratory volume in the first second) and diffusion capacity. Exercise testing may reveal gas exchange abnormalities, ventilatory limitation, and hypoxemia. The severity and progression of disease may be assessed by lung histology scores, quantification of computed tomography, pulmonary function testing, 6-minute walk tests, cardiopulmonary exercise testing, and measurement of serum vascular endothelial growth factor D levels. Sirolimus and everolimus, two mTOR inhibitors, are effective in stabilizing lung function and reducing the size of chylous effusions, lymphangioleiomyo-mas, and angiomyolipomas. However, inhibition of mTOR complex 1 increases autophagy, possibly enhancing LAM cell survival. Inhibition of autophagy with hydroxychloroquine, in combination with sirolimus, has been proposed as a possible treatment for LAM. Deficiency of tuberin results in increased RhoA GTPase activity and cell survival, an effect that is mediated through mTOR complex 2 signaling. Because sirolimus and everolimus only affect the activity of mTOR complex 1, therapies targeting RhoA GTPases with simvastatin, which inhibits Rho GTPases and promotes apoptosis, are being investigated. As in the case of cancer, LAM may be best treated with multiple drugs targeting signaling pathways considered important in the pathogenesis of disease.

Retrospective review of combined sirolimus and simvastatin therapy in lymphangioleiomyomatosis

BACKGROUND

Combined simvastatin and sirolimus therapy reduces tuberous sclerosis complex 2-null lesions and alveolar destruction in a mouse model of lymphangioleiomyomatosis (LAM), suggesting that therapy with both drugs may benefit patients with LAM.

METHODS

To determine whether simvastatin changed the prevalence of adverse events or altered the therapeutic effects of sirolimus, we recorded adverse events and changes in lung function in patients with LAM treated with simvastatin plus sirolimus (n = 14), sirolimus alone (n = 44), or simvastatin alone (n = 20).

RESULTS

Sirolimus-related adverse events in the simvastatin plus sirolimus and sirolimus-only groups were 64% and 66% for stomatitis, 50% and 52% for diarrhea, 50% and 45% for peripheral edema, 36% and 61% for acne, 36% and 30% for hypertension, 29% and 27% for proteinuria, 29% and 27% for leukopenia, and 21% and 27% for hypercholesterolemia. The frequency of simvastatin-related adverse events in the simvastatin-only and simvastatin plus sirolimus groups were 60% and 50% for arthralgias and 35% and 36% for myopathy. Before simvastatin plus sirolimus therapy, FEV1 and diffusing capacity of the lung for carbon monoxide (Dlco) yearly rates of change were, respectively, -1.4 ± 0.2 and -1.8 ± 0.2% predicted. After simvastatin plus sirolimus therapy, these rates changed to +1.2 ± 0.5 (P = .635) and +0.3 ± 0.4% predicted (P = .412), respectively. In 44 patients treated with sirolimus alone, FEV1 and Dlco rates of change were -1.7 ± 0.1 and -2.2 ± 0.1% predicted before treatment and +1.7 ± 0.3 and +0.7 ± 0.3% predicted after treatment (P < .001).

CONCLUSIONS

Therapy with sirolimus and simvastatin does not increase the prevalence of drug adverse events or alter the therapeutic effects of sirolimus.

Sustained effects of sirolimus on lung function and cystic lung lesions in lymphangioleiomyomatosis

RATIONALE

Sirolimus therapy stabilizes lung function and reduces the size of chylous effusions and lymphangioleiomyomas in patients with lymphangioleiomyomatosis.

OBJECTIVES

To determine whether sirolimus has beneficial effects on lung function, cystic areas, and adjacent lung parenchyma; whether these effects are sustained; and whether sirolimus is well tolerated by patients.

METHODS

Lung function decline over time, lung volume occupied by cysts (cyst score), and lung tissue texture in the vicinity of the cysts were quantified with a computer-aided diagnosis system in 38 patients. Then we compared cyst scores from the last study on sirolimus with studies done on sirolimus therapy. In 12 patients, we evaluated rates of change in lung function and cyst scores off and on sirolimus.

MEASUREMENTS AND MAIN RESULTS

Sirolimus reduced yearly declines in FEV1 (-2.3 ± 0.1 vs. 1.0 ± 0.3% predicted; P < 0.001) and diffusing capacity of carbon monoxide (-2.6 ± 0.1 vs. 0.9 ± 0.2% predicted; P < 0.001). Cyst scores 1.2 ± 0.8 years (30.5 ± 11.9%) and 2.5 ± 2 years (29.7 ± 12.1%) after initiating sirolimus were not significantly different from pretreatment values (28.4 ± 12.5%). In 12 patients followed for 5 years, a significant reduction in rates of yearly decline in FEV1 (-1.4 ± 0.2 vs. 0.3 ± 0.4% predicted; P = 0.025) was observed. Analyses of 104 computed tomography scans showed a nonsignificant (P = 0.23) reduction in yearly rates of change of cyst scores (1.8 ± 0.2 vs. 0.3 ± 0.3%; P = 0.23) and lung texture features. Despite adverse events, most patients were able to continue sirolimus therapy.

CONCLUSIONS

Sirolimus therapy slowed down lung function decline and increase in cystic lesions. Most patients were able to tolerate sirolimus therapy.

Severity and outcome of cystic lung disease in women with tuberous sclerosis complex

What are the clinical features, severity, and rate of progression of lung disease in women with tuberous sclerosis and lymphangioleiomyomatosis (LAM) and how do they differ from patients with sporadic LAM? Data from 94 tuberous sclerosis/LAM and 460 sporadic LAM women were compared. 40 tuberous sclerosis/LAM and 40 sporadic LAM patients were age- and lung function-matched, and changes in volume occupied by cysts (cyst score) and pulmonary function occurring over 6.5 years were evaluated. Tuberous sclerosis/LAM patients had better lung function than sporadic LAM patients, but no difference was observed from sporadic LAM patients in yearly rates of change in forced expiratory volume in 1 s (-1.9±2.7 versus -1.9±1.9% predicted; p=0.302), diffusing capacity of the lung for CO (-2.1±2.8 versus -1.9±2.7% predicted; p=0.282) or cyst scores (+1.0±1.3 versus +1.4±1.7%, p=0.213). However, the proportion of patients with abnormal lung function and higher rates of FEV1 decline was greater in sporadic LAM. Some young tuberous sclerosis/LAM patients (mean age 25.7±3 years) progressed rapidly from minimal to severe lung disease. Tuberous sclerosis/LAM patients may experience abrupt declines in lung function. Consequently, women with tuberous sclerosis found to have lung cysts should undergo periodic functional and radiological testing to follow disease progression and determine need for therapy.

Management of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM), a multisystem disease affecting almost exclusively women, is characterized by cystic lung destruction and presents with dyspnea, recurrent pneumothoraxes, chylous effusions, lymphangioleiomyomas, and angiomyolipomas. It is caused by the proliferation of a cancer-like LAM cell that possesses a mutation in either the tuberous sclerosis complex (TSC)1 or TSC2 genes. This article reviews current therapies and new potential treatments that are currently undergoing investigation. The major development in the treatment of LAM is the discovery of two mammalian target of rapamycin (mTOR) inhibitors, sirolimus and everolimus, as effective drugs. However, inhibition of mTOR increases autophagy, which may lead to enhanced LAM cell survival. Use of autophagy inhibitors, for example, hydroxychloroquine, in combination with sirolimus is now the subject of an ongoing drug trial (SAIL trial). Another consequence of mTOR inhibition by sirolimus is an increase in Rho activity, resulting in reduced programmed cell death. From these data, the concept evolved that a combination of sirolimus with disruption of Rho activity with statins (e.g. simvastatin) may increase TSC-null cell death and reduce LAM cell survival. A combined trial of sirolimus with simvastatin is under investigation (SOS trial). Since LAM occurs primarily in women and TSC-null cell survival and tumor growth is promoted by estrogens, the inhibition of aromatase to block estrogen synthesis is currently undergoing study (TRAIL trial). Other targets, for example, estrogen receptors, mitogen-activated protein kinase inhibitors, vascular endothelial growth factor-D signaling pathway, and Src kinase, are also being studied in experimental model systems. As in the case of cancer, combination therapy may become the treatment of choice for LAM.

Optimizing treatments for lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM), a multisystem disease predominantly affecting premenopausal women, is associated with cystic lung destruction and lymphatic and kidney tumors. LAM results from the proliferation of a neoplastic cell that has mutations in the tuberous sclerosis complex 1 or 2 genes, leading to activation of a critical regulatory protein, mammalian target of rapamycin. In this report, we discuss the molecular mechanisms regulating LAM cell growth and report the results of therapeutic trials employing new targeted agents. At present, inhibitors of mammalian target of rapamycin such as sirolimus appear to be the most promising therapeutic agents, although drug toxicity and development of resistance are potential problems. As the pathogenesis of LAM is being further recognized, other therapeutic agents such as matrix metalloproteinase inhibitors, statins, interferon, VEGF inhibitors, chloroquine analogs and cyclin-dependent kinase inhibitors, along with sirolimus or a combination of several of these agents, may offer the best hope for effective therapy.

Bronchoscopic diagnosis of Langerhans cell histiocytosis and lymphangioleiomyomatosis

Limited data are available regarding the role of bronchoalveolar lavage (BAL) and transbronchial lung biopsy (TBB) as diagnostic tools in pulmonary Langerhans' Cell Histiocytosis (LCH) and lymphangioleiomyomatosis (LAM). The aim of this study was to review our experience regarding the value of these two techniques in the diagnosis of these cystic lung diseases. Records of 452 patients with the presumptive diagnosis of interstitial lung disease were reviewed; 67 had a clinical-radiological diagnosis of either LCH (n = 27) or LAM (n = 40). Of 16 patients with LCH who underwent BAL, four specimens (25%) contained cells which had positive immunoreactivity for CD1a. Of three patients with negative BAL fluid who had TBB, only one had a positive tissue diagnosis. Ten LCH patients were diagnosed by surgical lung biopsy of which five had negative BAL fluid. The remaining 12 patients were diagnosed by clinical and radiologic features. Standard examination of BAL fluid was of no diagnostic value in LAM. TBB was performed in seven patients and was diagnostic in six, not resulting in complications. All 13 patients who underwent surgical lung biopsies had a positive histopathologic diagnosis The remaining 21 patients were diagnosed by clinical and radiologic features. We suggest that BAL may assist in the diagnosis of LCH whereas TBB may be useful in the diagnosis of LAM, thus avoiding the need for surgical biopsy.

Changes in lung function and chylous effusions in patients with lymphangioleiomyomatosis treated with sirolimus

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a disorder that affects women and is characterized by cystic lung destruction, chylous effusions, lymphangioleiomyomas, and angiomyolipomas. It is caused by proliferation of abnormal smooth muscle-like cells. Sirolimus is a mammalian target of rapamycin inhibitor that has been reported to decrease the size of neoplastic growths in animal models of tuberous sclerosis complex and to reduce the size of angiomyolipomas and stabilize lung function in humans.

OBJECTIVE

To assess whether sirolimus therapy is associated with improvement in lung function and a decrease in the size of chylous effusions and lymphangioleiomyomas in patients with LAM.

DESIGN

Observational study.

SETTING

The National Institutes of Health Clinical Center.

PATIENTS

19 patients with rapidly progressing LAM or chylous effusions.

INTERVENTION

Treatment with sirolimus.

MEASUREMENTS

Lung function and the size of chylous effusions and lymphangioleiomyomas before and during sirolimus therapy.

RESULTS

Over a mean of 2.5 years before beginning sirolimus therapy, the mean (±SE) FEV1 decreased by 2.8%±0.8% predicted and diffusing capacity of the lung for carbon monoxide (Dlco) decreased by 4.8%±0.9% predicted per year. In contrast, over a mean of 2.6 years of sirolimus therapy, the mean (±SE) FEV1 increased by 1.8%±0.5% predicted and Dlco increased by 0.8%±0.5% predicted per year (P<0.001). After beginning sirolimus therapy, 12 patients with chylous effusions and 11 patients with lymphangioleiomyomas experienced almost complete resolution of these conditions. In 2 of the 12 patients, sirolimus therapy enabled discontinuation of pleural fluid drainage.

LIMITATIONS

This was an observational study. The resolution of effusions may have affected improvements in lung function.

CONCLUSION

Sirolimus therapy is associated with improvement or stabilization of lung function and reduction in the size of chylous effusions and lymphangioleiomyomas in patients with LAM.

PRIMARY FUNDING SOURCE

Intramural Research Program, National Heart, Lung, and Blood Institute, National Institutes of Health.

Efficacy and safety of sirolimus in lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a progressive, cystic lung disease in women; it is associated with inappropriate activation of mammalian target of rapamycin (mTOR) signaling, which regulates cellular growth and lymphangiogenesis. Sirolimus (also called rapamycin) inhibits mTOR and has shown promise in phase 1-2 trials involving patients with LAM.

METHODS

We conducted a two-stage trial of sirolimus involving 89 patients with LAM who had moderate lung impairment--a 12-month randomized, double-blind comparison of sirolimus with placebo, followed by a 12-month observation period. The primary end point was the difference between the groups in the rate of change (slope) in forced expiratory volume in 1 second (FEV(1)).

RESULTS

During the treatment period, the FEV(1) slope was -12±2 ml per month in the placebo group (43 patients) and 1±2 ml per month in the sirolimus group (46 patients) (P<0.001). The absolute between-group difference in the mean change in FEV(1) during the treatment period was 153 ml, or approximately 11% of the mean FEV(1) at enrollment. As compared with the placebo group, the sirolimus group had improvement from baseline to 12 months in measures of forced vital capacity, functional residual capacity, serum vascular endothelial growth factor D (VEGF-D), and quality of life and functional performance. There was no significant between-group difference in this interval in the change in 6-minute walk distance or diffusing capacity of the lung for carbon monoxide. After discontinuation of sirolimus, the decline in lung function resumed in the sirolimus group and paralleled that in the placebo group. Adverse events were more common with sirolimus, but the frequency of serious adverse events did not differ significantly between the groups.

CONCLUSIONS

In patients with LAM, sirolimus stabilized lung function, reduced serum VEGF-D levels, and was associated with a reduction in symptoms and improvement in quality of life. Therapy with sirolimus may be useful in selected patients with LAM. (Funded by the National Institutes of Health and others; MILES ClinicalTrials.gov number, NCT00414648.).

Erythropoietin-driven proliferation of cells with mutations in the tumor suppressor gene TSC2

Lymphangioleiomyomatosis (LAM) is characterized by cystic lung destruction, resulting from proliferation of smooth-muscle-like cells, which have mutations in the tumor suppressor genes TSC1 or TSC2. Among 277 LAM patients, severe disease was associated with hypoxia and elevated red blood cell indexes that accompanied reduced pulmonary function. Because high red cell indexes could result from hypoxemia-induced erythropoietin (EPO) production, and EPO is a smooth muscle cell mitogen, we investigated effects of EPO in human cells with genetic loss of tuberin function, and we found that EPO increased proliferation of human TSC2-/-, but not of TSC2+/-, cells. A discrete population of cells grown from explanted lungs was characterized by the presence of EPO receptor and loss of heterozygosity for TSC2, consistent with EPO involvement. In LAM cells from lung nodules, EPO was localized to the extracellular matrix, supporting evidence for activation of an EPO-driven signaling pathway. Although the high red cell mass of LAM patients could be related to advanced disease, we propose that EPO, synthesized in response to episodic hypoxia, may increase disease progression by enhancing the proliferation of LAM cells.

The natural history of lymphangioleiomyomatosis: markers of severity, rate of progression and prognosis

Lymphangioleiomyomatosis (LAM) is a multisystem disease of women, characterized by proliferation of abnormal smooth muscle-like cells (LAM cells) that can metastasize, leading to the formation of lung cysts, fluid-filled cystic structures in the axial lymphatics (e.g., lymphangioleiomyomas), and angiomyolipomas, benign tumors usually involving the kidneys, comprising LAM cells and adipocytes, intermixed with incompletely developed vascular structures. LAM occurs sporadically or in association with tuberous sclerosis complex, an autosomal dominant syndrome characterized by hamartoma-like tumor growths. LAM may present with progressive dyspnea, recurrent pneumothorax, chylothorax, or abdominal hemorrhage. Computed tomography scans show thin-walled cysts scattered throughout the lungs, abdominal angiomyolipomas, and lymphangioleiomyomas. Pulmonary function tests show reduced flow rates (FEV(1)) and diffusion capacity (DL(CO)). Exercise testing may reveal gas exchange abnormalities, ventilatory limitation, and hypoxemia, which can occur with near-normal lung function. Methods used to grade the severity of disease are the LAM histology score, semiquantitative and quantitative computer tomography, pulmonary function testing, and cardiopulmonary exercise testing. Currently, progression of disease is best assessed by serial measurements of FEV(1), DL(CO), and exercise performance. New quantitative radiographic techniques that may offer advantages over physiologic testing are now available. Several potential biomarkers, such as LAM cells in peripheral blood, urine, and chyle and chemokines, vascular endothelial growth factors, and matrix metalloproteinases, may be useful as diagnostic tools or markers of organ involvement, disease severity, and progression.

Therapeutic options for lymphangioleiomyomatosis (LAM): where we are and where we are going

Lymphangioleiomyomatosis (LAM), a multisystem disease affecting predominantly premenopausal and middle-aged women, causes progressive respiratory failure due to cystic lung destruction and is associated with lymphatic and kidney tumors. In the past, the treatment of LAM comprised exclusively anti-estrogen and related hormonal therapies. These treatments, however, have not been proven effective. In this article, we discuss new findings regarding the molecular mechanisms involved in the regulation of LAM cell growth, which may offer opportunities to develop effective and targeted therapeutic agents.

Reversible airflow obstruction in lymphangioleiomyomatosis

BACKGROUND

We previously reported that approximately one-fourth of patients with lymphangioleiomyomatosis (LAM) may respond to therapy with bronchodilators. However, the validity of those observations has been questioned. The aims of the present study were to determine the prevalence of reversible airflow obstruction in patients with LAM and to identify associated clinical and physiologic parameters.

METHODS

First, the clinical and physiologic characteristics of 235 patients were analyzed to determine the frequency of the response to albuterol during a total of 2,307 visits. Second, we prospectively evaluated the response to albuterol (2.5 mg) and ipratropium (500 mug) in 130 patients, and correlated their responses with their clinical and physiologic characteristics.

RESULTS

In the retrospective study, 51% of the patients responded at least once to bronchodilators; of these, 12% responded >/= 50% of the time. A higher frequency of positive bronchodilator responses was associated with greater rates of decline in FEV(1) and diffusing capacity of the lung for carbon monoxide (Dlco). In the prospective study, 39 patients (30%) responded to bronchodilators, including 12 to ipratropium, 9 to albuterol, and 18 to both. The prevalence of asthma and smoking in the 39 responders was not different from that seen in the 91 nonresponders. Patients who responded to ipratropium, albuterol, or both had significantly (p < 0.02) lower FEV(1) and Dlco, and a greater rate of FEV(1) decline (p = 0.044) and Dlco decline (p = 0.039) than patients who did not respond to these bronchodilators. After adjusting for FEV(1)/FVC ratio, Dlco decline also was greater in responders than in nonresponders (p = 0.009).

CONCLUSIONS

Patients with LAM may have partially reversible airflow obstruction. A positive response to bronchodilators is associated with an accelerated rate of decline in pulmonary function.

Pneumothorax after air travel in lymphangioleiomyomatosis, idiopathic pulmonary fibrosis, and sarcoidosis

BACKGROUND

The prevalence of pneumothorax associated with travel in patients with interstitial lung diseases is unknown. In patients with lymphangioleiomyomatosis (LAM), in whom pneumothorax is common, patients are often concerned about the occurrence of a life-threatening event during air travel. The aim of this study was to determine the prevalence of pneumothorax associated with air travel in patients with LAM, idiopathic pulmonary fibrosis (IPF), and sarcoidosis.

METHODS

Records and imaging studies of 449 patients traveling to the National Institutes of Health were reviewed.

RESULTS

A total of 449 patients traveled 1,232 times; 299 by airplane (816 trips) and 150 by land (416 trips). Sixteen of 281 LAM patients arrived at their destination with a pneumothorax. In 5 patients, the diagnosis was made by chest roentgenogram, and in 11 patients by CT scans only. Of the 16 patients, 14 traveled by airplane and 2 by land. Seven of the 16 patients, 1 of whom traveled by train, had a new pneumothorax; 9 patients had chronic pneumothoraces. A new pneumothorax was more likely in patients with large cysts and more severe disease. The frequency of a new pneumothorax for LAM patients who traveled by airplane was 2.9% (1.1 per 100 flights) and by ground transportation, 1.3% (0.5 per 100 trips). No IPF (n = 76) or sarcoidosis (n = 92) patients presented with a pneumothorax.

CONCLUSIONS

In interstitial lung diseases with a high prevalence of spontaneous pneumothorax, there is a relatively low risk of pneumothorax following air travel. In LAM, the presence of a pneumothorax associated with air travel may be related to the high incidence of pneumothorax and not to travel itself.

Effect of a gonadotrophin-releasing hormone analogue on lung function in lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis (LAM), a multisystem disease occurring primarily in women, is characterized by cystic lung destruction, and kidney and lymphatic tumors, caused by the proliferation of abnormal-appearing cells (ie, LAM cells) with a smooth muscle cell phenotype that express melanoma antigens and are capable of metastasizing. Estrogen receptors are present in LAM cells, and this finding, along with reports of disease progression during pregnancy or following exogenous estrogen administration, suggest the involvement of estrogens in the pathogenesis of LAM. Consequently, antiestrogen therapies have been employed in treatment. The goal of this prospective study was to evaluate the efficacy of triptorelin, a gonadotrophin-releasing hormone analogue, in 11 premenopausal women with LAM.

METHODS

Patients were evaluated at baseline and every 3 to 6 months thereafter, for a total of 36 months. Hormonal assays, pulmonary function tests, 6-min walk tests, high-resolution CT scans of the chest, and bone mineral density studies were performed.

RESULTS

Gonadal suppression was achieved in all patients. Overall, a significant decline in lung function was observed; two patients underwent lung transplantation 1 year after study enrollment, and another patient was lost to follow-up. Treatment with triptorelin was associated with a decline in bone mineral density.

CONCLUSIONS

Triptorelin appears not to prevent a decline in lung function in patients with LAM. Its use, however, may be associated with the loss of bone mineral density.

Pulmonary artery pressure in lymphangioleiomyomatosis: an echocardiographic study

BACKGROUND

Exercise-induced hypoxemia is frequent in patients with lymphangioleiomyomatosis (LAM) and could be associated with pulmonary hypertension. The aims of this study were to determine the prevalence of pulmonary hypertension in patients with LAM, to identify physiologic parameters associated with its occurrence, and to evaluate the effect of oxygen on response to exercise.

METHODS

Studies were performed in 120 patients. Complete data, including exercise echocardiography, pulmonary function testing, and standard cardiopulmonary exercise testing, were obtained in 95 patients.

RESULTS

Resting pulmonary artery pressure (PAP) was 26+/-0.7 mm Hg (mean+/-SEM). Eight patients had pulmonary hypertension (43+/-3 mm Hg), and two patients had right ventricular dilatation. Ninety-five patients exercised (room air, n=64; oxygen, n=31) to a power of 58+/-2 W (49% of predicted) and an estimated peak oxygen uptake of 938+/-30 mL/min (56% of predicted). Sixty-one patients had a decline in arterial oxygen saturation (SaO2)>3%, and 56 patients had an elevation in PAP>40 mm Hg. Peak exercise PAP was negatively correlated with exercise Sao2 (p=0.0005). Multivariate analysis showed that exercise SaO2 was the best predictor of exercise PAP (p=0.012).

CONCLUSIONS

Although resting pulmonary hypertension is rare in patients with LAM, a rise in PAP at low exercise levels occurs frequently, in part related to exercise-induced hypoxemia. Optimization of oxygen administration during activities of daily living should be undertaken in patients with LAM to prevent hypoxemia and exercise-induced pulmonary hypertension.

Lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a rare disease that is characterized by proliferation of abnormal smooth muscle-like cells (LAM cells), which leads to the formation of lung cysts, fluid-filled cystic structures in the axial lymphatics, and abdominal tumors. It primarily affects women.

METHODS

The authors present a review of large series, registries, and protocols to highlight the prevalence, pathology, clinical features, diagnosis, and treatment options for patients with LAM.

RESULTS

LAM commonly presents with progressive breathlessness or with recurrent pneumothorax, chylothorax, or sudden abdominal hemorrhage. Computed tomography (CT) scans show numerous thin-walled cysts throughout the lungs, abdominal angiomyolipomas, and lymphangioleiomyomas. Pulmonary function tests show decreased forced expiratory volume in 1 second (FEV1) and diffusion capacity for carbon monoxide (DLCO). Exercise testing shows gas-exchange abnormalities, ventilatory limitation, and hypoxemia that may occur with near-normal lung function.

CONCLUSIONS

No effective treatment currently exists for this progressive disorder. However, recent progress in cancer and smooth muscle cell biology and a better understanding of the factors regulating angiogenesis and lymphangiogenesis may provide a foundation for the development of new therapeutic strategies.

N-terminal pro-brain natriuretic peptide levels and risk of death in sickle cell disease

CONTEXT

Thirty percent of patients with sickle cell disease (SCD) develop pulmonary hypertension, a major risk factor for death in this population. A validated blood biomarker of pulmonary hypertension in SCD could provide important prognostic and diagnostic information and allow the exploration of the prevalence of pulmonary hypertension in participants in the 1996 Multicenter Study of Hydroxyurea in Sickle Cell Anemia (MSH) Patients' Follow-up Study. Levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) provide such information in patients with idiopathic pulmonary arterial hypertension.

OBJECTIVE

To determine the relationship between NT-proBNP levels and severity of pulmonary hypertension and prospective mortality in patients with SCD.

DESIGN, SETTING, AND PARTICIPANTS

NT-proBNP levels were measured in 230 participants in the National Institutes of Health (NIH) Sickle Cell Disease-Pulmonary Hypertension Screening Study (enrollment between February 2001 and March 2005) and in 121 samples from patients enrolled starting in 1996 in the MSH Patients' Follow-up Study. A threshold level predictive of high pulmonary artery pressure and mortality was identified in the NIH Sickle Cell Disease-Pulmonary Hypertension Screening Study and used to define an a priori analytical plan to determine the prevalence and associated mortality of pulmonary hypertension in the MSH follow-up study.

MAIN OUTCOME MEASURES

Severity of pulmonary hypertension and risk of all-cause mortality.

RESULTS

NT-proBNP levels were higher in patients with sickle cell pulmonary hypertension and correlated directly with tricuspid regurgitant jet velocity in the NIH cohort (R = 0.50, P<.001). An NT-proBNP level of 160 pg/mL or greater had a 78% positive predictive value for the diagnosis of pulmonary hypertension and was an independent predictor of mortality (21 deaths at 31 months' median follow-up; risk ratio, 5.1; 95% confidence interval, 2.1-12.5; P<.001; 19.5% absolute increase in risk of death). In the MSH cohort, 30% of patients had an NT-proBNP level of 160 pg/mL or greater. An NT-proBNP level of 160 pg/mL or greater in the MSH cohort was independently associated with mortality by Cox proportional hazards regression analysis (24 deaths at 47 months' median follow-up; risk ratio, 2.87; 95% confidence interval, 1.2-6.6; P = .02; 11.9% absolute increase in risk of death).

CONCLUSIONS

Pulmonary hypertension, as indicated by an NT-proBNP level of 160 pg/mL or greater, was very common in patients in the NIH study and in the MSH cohort. The MSH analysis suggests that rates of vaso-occlusive pain episodes in these patients were unrelated to risk of death; this risk was largely determined by occult hemolytic anemia-associated pulmonary hypertension.

Clinical and molecular insights into lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare disease of women that is characterized by a proliferation of abnormal smooth muscle-like cells (LAM cells), which leads to cystic lung lesions, lymphatic abnormalities, and abdominal tumors (e.g., angiomyolipomas). LAM occurs sporadically or in association with tuberous sclerosis complex, an autosomal dominant syndrome characterized by hamartoma-like tumor growths. The tumor suppressor genes TSC1 and TSC2 have been implicated in the etiology of LAM, as mutations and loss of heterozygosity (LOH) in TSC2 have been detected in LAM cells. TSC1 encodes hamartin, with a postulated role in actin cytoskeleton reorganization. TSC2 encodes tuberin, a protein with roles in cell growth and proliferation, transcriptional activation, and endocytosis. LAM cells, as defined by TSC2 LOH, have been detected in blood and body fluids, and can metastasize. LAM presents insidiously with progressive breathlessness, or dramatically with recurrent pneumothorax, chylothorax, or sudden abdominal hemorrhage. CT scans show numerous thin-walled cysts throughout the lungs, abdominal angiomyolipomas, and lymphangioleiomyomas. Pulmonary function tests show reduced flow rates (FEV1) and diffusion capacity (DL(CO)). Twenty per cent of patients have positive bronchodilator responses. Exercise testing shows gas-exchange abnormalities, ventilatory limitation, and hypoxemia that may occur with near-normal lung function. Progression of disease is best assessed by measurements of DL(CO) and FEV1. In the proper clinical setting, LAM may be diagnosed by a thoraco-abdominal CT scan. Tissue biopsy with special stains (HMB-45) should be reserved for cases with atypical presentations. There is no effective treatment for LAM, but on-going therapeutic trials with rapamycin appear promising.

Decline in lung function in patients with lymphangioleiomyomatosis treated with or without progesterone

STUDY OBJECTIVE

Lymphangioleiomyomatosis (LAM), a disease affecting women and causing cystic lung lesions, and, in some instances, leading to respiratory failure and death, appears to be exacerbated by estrogens. Hence, hormonal therapy with progesterone is frequently employed; however, efficacy has not been demonstrated. Our aim was to determine whether progesterone administration slowed the decline in lung function in LAM.

DESIGN

Retrospective study.

SETTING

National Institutes of Health, Bethesda, MD.

DESIGN AND SUBJECTS

The study population comprised 348 patients with LAM participating in a longitudinal research protocol. Declines in diffusion capacity of the lung for carbon monoxide (Dlco) and FEV(1) were measured in 275 patients observed for approximately 4 years. The declines in Dlco and FEV(1) of patients treated with progesterone, po (n = 67) or IM (n = 72), were compared with those of untreated patients (n = 136).

MEASUREMENTS AND RESULTS

Overall yearly rates of decline in Dlco and FEV(1) were 2.4 +/- 0.4% predicted (0.69 +/- 0.07 mL/min/mm Hg) and 1.7 +/- 0.4% predicted (75 +/- 9 mL), respectively (mean +/- SEM). The most significant predictors of functional decline were initial lung function and age. After adjusting for initial FEV(1), age, and duration of disease, patients treated with IM progesterone tended to have lower rates of decline in FEV(1) than patients treated po (1.9 +/- 0.6% predicted vs 3.2 +/- 0.8% predicted, respectively; p = 0.081). However, there was no significant difference in rates of decline in FEV(1) between patients treated with IM progesterone and untreated patients (1.9 +/- 0.6% predicted vs 0.8 +/- 0.5% predicted, respectively; p = 0.520), and patients treated with po progesterone and untreated patients (3.2 +/- 0.8% predicted vs 0.8 +/- 0.5% predicted, respectively; p = 0.064). After adjusting for initial Dlco, rates of decline in Dlco were significantly higher in patients treated with po progesterone (3.6 +/- 0.7% predicted, p = 0.002) and IM progesterone (2.8 +/- 0.5% predicted, p = 0.022) than in untreated patients (1.6 +/- 0.6% predicted).

CONCLUSIONS

Within the limitations of a retrospective study, our data suggest that progesterone therapy does not slow the decline in lung function in LAM.

Maximal oxygen uptake and severity of disease in lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM), a disease that occurs primarily in women, is characterized by cystic lung lesions causing respiratory failure, which may require lung transplantation. Lung diffusion (DLCO) and/or FEV1 are decreased, but frequently not in parallel with each other. Because cardiopulmonary exercise testing (CPET) provides information that is not obtainable from resting cardiopulmonary tests, we performed CPET in 217 LAM patients and correlated exercise data with clinical markers of severity, computed tomography scans, lung function, and histology. VO2max was decreased in 162 patients, of whom 28 did not reach anaerobic threshold; 29 had low oxygen uptake at anaerobic threshold, and 54 developed hypoxemia. Hypoxemia occurred even in patients with near normal DLCO and FEV1. VO2max decreased with an increasing score of histologic LAM severity and was correlated with computed tomography scans, the use of oxygen, and resting PaO2. DLCO and FEV1, however, were the only significant predictors of VO2max. We conclude that CPET uncovers the presence of exercise-induced hypoxemia and assists in grading the severity of disease and determining supplemental oxygen requirements in patients with LAM.

Serotonin 1A receptor agonists reverse respiratory abnormalities in spinal cord-injured rats

Contusion spinal cord injury (SCI) at T8 produces respiratory abnormalities in conscious rats breathing room air and challenged with CO2. In seeking ways to improve respiration after SCI, we tested drugs that stimulate serotonin 1A (5-HT1A) receptors, based on our previous findings that these agents can counteract respiratory depression produced by morphine overdose. Respiratory function was measured with a head-out plethysmograph system in conscious rats. T8 SCI rats (n = 5) showed decreased tidal volume (Vt; 0.90 +/- 0.02-0.66 +/- 0.03 ml; p < 0.05) and increased respiratory rate (f;91 +/- 3.7-132 +/- 5.7 breaths/min; p < 0.05) with room air ventilation at 24 hr after injury. They also exhibited a diminished response to the respiratory stimulating effect of 7% CO2; minute ventilation increased to 250 +/- 17 ml/min before, but only to 162 +/- 15 ml/min at 24 hr after SCI (p < 0.05). Respiratory deficits during room air ventilation were also observed at 7 d after injury (n = 3). Treatment with the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylmino)tetralin (8-OH-DPAT; 250 microg/kg, i.p.) at 24 hr (n = 5) or 7 d (n = 3) after injury normalized Vt, f, and the respiratory response to 7% CO2. Identical results were obtained with another 5-HT1A receptor agonist, buspirone (1.5 mg/kg, i.p.; n = 3). In contrast, intraperitoneal saline vehicle administration (n = 5) showed no beneficial effects on SCI-impaired respiration. Finally, pretreatment with a specific antagonist of 5-HT1A receptors, 4-iodo-N-[2-[4-(methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl-benzamide (3 mg/kg, i.p.; n = 3) given 20 min before 8-OH-DPAT, prevented 8-OH-DPAT from restoring respiration to normal. Our results demonstrate that drugs that stimulate 5-HT1A receptors counteract respiratory abnormalities in conscious rats after SCI.

Reversible airflow obstruction, proliferation of abnormal smooth muscle cells, and impairment of gas exchange as predictors of outcome in lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a rare disease, occurring in women, characterized by cystic degeneration of the lungs, abdominal tumors, and proliferation of abnormal smooth muscle cells. Lung function abnormalities consist of impairment of the diffusion capacity (DL(CO)) and airflow obstruction. The objective of this study was to correlate the functional impairment with histologic measures of disease severity to identify predictors of disease outcome. Lung function of 143 patients and lung biopsies of 74 of these patients were reviewed for evidence of airway disease and scoring of disease severity. A positive response to bronchodilators was associated with more severe airflow obstruction, a predominantly solid pattern of LAM lesions in the lung biopsy, and greater rate of decline in expiratory flow. Airway inflammation, present in 61% of the lung specimens, was not associated with reversible airway obstruction and did not correlate with the severity of airflow obstruction. DL(CO) correlated best with the LAM histologic score (LHS), a demonstrated predictor of outcome. We conclude that reversible airway obstruction is found in LAM patients with accelerated loss of lung function and a predominantly solid pattern of LAM lesions. Impairment of DL(CO) correlates with LHS, a predictor of survival and time to lung transplantation.

Reversal of morphine-induced apnea in the anesthetized rat by drugs that activate 5-hydroxytryptamine(1A) receptors

The purpose of our study was to test the hypothesis that 5-hydroxytryptamine (5-HT)(1A) receptor agonists counteract morphine-induced respiratory depression. Studies were conducted in anesthetized rats, and respiratory activity was monitored with diaphragm electromyography. Morphine was administered i.v. in doses that produce apnea. Once apnea was established, i.v. administration of the 5-HT(1A) receptor agonist drug 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) at 10 or 100 microgram/kg restored normal breathing in each animal (n = 24). This antagonistic effect of 8-OH-DPAT on morphine-induced respiratory depression was observed in both spontaneously breathing and artificially ventilated animals. Results obtained with 8-OH-DPAT were mimicked by buspirone (50 microgram/kg i.v.), another 5-HT(1A) receptor agonist drug. Pretreatment with 4-(2'-methoxyphenyl)-1-[2'[N-(2'-pyridinyl]-p-iodo-benzamido]ethyl]pi perazine, an antagonist of 5-HT(1A) receptors, prevented 8-OH-DPAT from counteracting morphine-induced apnea. These results indicate that activation of central nervous system 5-HT(1A) receptors is an effective way of reversing morphine-induced respiratory depression. Most important, this is the third model of disturbed respiratory function in which drugs that stimulate 5-HT(1A) receptors have been shown to restore breathing to near-normal levels.

Basic fibroblast growth factor increases long-term survival of spinal motor neurons and improves respiratory function after experimental spinal cord injury

Acute focal injection of basic fibroblast growth factor (FGF2) protects ventral horn (VH) neurons from death after experimental contusive spinal cord injury (SCI) at T8. Because these neurons innervate respiratory muscles, we hypothesized that respiratory deficits resulting from SCI would be attenuated by FGF2 treatment. To test this hypothesis we used a head-out plethysmograph system to evaluate respiratory parameters in conscious rats before and at 24 hr and 7, 28, and 35 d after SCI. Two groups of rats (n = 8 per group) received either FGF2 (3 microg) beginning 5 min after injury or vehicle (VEH) solution alone. We found significantly increased respiratory rate and decreased tidal volume at 24 hr and 7 d after SCI in the VEH-treated group. Ventilatory response to breathing 5 or 7% CO(2) was also significantly reduced. Recovery took place over time. Respiration remained normal in the FGF2-treated group. At 35 d after injury, histological analyses were used to compare long-term neuron survival. FGF2 treatment doubled the survival of VH neurons adjacent to the injury site. Because the number of surviving VH neurons rostral to the injury epicenter was significantly correlated to the ventilatory response to CO(2), it is likely that the absence of respiratory deficits in FGF2-treated rats was caused by its neuroprotective effect. Our results demonstrate that FGF2 treatment prevents the respiratory deficits produced by thoracic SCI. Because FGF2 also reduced the loss of preganglionic sympathetic motoneurons after injury, this neurotrophic factor may have broad therapeutic potential for SCI.