Alpha-1 Antitrypsin Gene Variants in Patients without Severe Deficiency Diagnosed with Pulmonary Emphysema on Chest CT.

Introduction: Although pulmonary involvement due to alpha-1 antitrypsin (AAT) deficiency has been widely described, most studies focus on the genotypes causing severe deficiency (<60 mg/dL). Objective: The aim of this study was to analyze the prevalence of the different AAT gene variants that do not cause severe deficiency in patients with pulmonary emphysema diagnosed by thoracic computed tomography (CT). Furthermore, we assessed the risk associated with a non-severe decrease in AAT values in the pathogenesis of emphysema. Methods: Case-control study design that included patients who had a CT scan available of the entire thorax. In total, 176 patients with emphysema (cases) and 100 control subjects without emphysema were analyzed. Results: The prevalence of variants was higher among cases (25.6%; 45/176) than controls (22%; 22/100), although the difference was not statistically significant (P=0.504) when analyzed globally. In the control group, all the variants detected were MS. Excluding this variant, statistically significant differences were observed in the remaining variants (MZ, SS and SZ). Only 18% of the controls (all MS) presented values below our limit of normality, and all had values very close to the reference value (90 mg/dL). In contrast, 76% of patients with the other variants presented pathological levels. In a logistic regression model, both smoking and a non-severe reduction in AAT (60 to 90 mg/dL) increased the probability of emphysema. Conclusion: Our study confirms an association between certain variants in the alpha-1 antitrypsin gene that do not cause severe deficiency and the presence of pulmonary emphysema. This association with variants that are associated with reductions in serum AAT values is statistically significant and independent of smoking habit.

Non-invasive testing for liver pathology in alpha-1 antitrypsin deficiency.

BACKGROUND: Many patients with alpha-1 antitrypsin deficiency (A1ATD) receive care in respiratory clinics without access to specialist hepatology expertise. Liver disease can develop asymptomatically, and non-invasive markers of fibrosis may help identify patients who require definitive assessment with liver biopsy. We evaluated the utility of non-invasive markers of liver fibrosis in A1ATD to guide testing in settings without ready access to hepatology expertise. METHODS: Patients attending the London A1ATD service undergo assessment using blood tests to calculate the 'APRI' and 'FIB-4' score, liver ultrasound and Fibroscan. Liver biopsy is offered to patients who have abnormal liver function tests with abnormal liver ultrasound and/or liver stiffness >6 kPa on Fibroscan. Liver biopsies were assessed for the presence of A1AT, steatosis, fibrosis and inflammation. RESULTS: 75 patients with A1ATD had results for analysis, 56% were female, age 16-82 years. 75% of patients had Fibroscan <6 kPa, 19% had Fibroscan 6-7.9 kPa and 6%>8 kPa. There was a significant correlation between FIB-4 and Fibroscan (r=0.244, p=0.035). Fibroscan >6 kPa corresponded to a FIB-4 score of >1.26. However, FIB-4 >1.26 had poor sensitivity (47%), specificity (32%) and positive-predictive value (PPV; 36%) to identify Fibroscan >6 kPa. The negative-predictive value (NPV) was stronger at 81%. APRI data were similar. Twelve patients underwent liver biopsy, with 11 reports available for analysis. Six had FIB-4 scores<1.26 and five had Fibroscan of <6 kPa. A1AT was present in 64% of biopsies, steatosis in 82%, mild fibrosis in 36%, moderate fibrosis in 9% and severe fibrosis in 9%. CONCLUSION: A combination of liver ultrasound and non-invasive fibrosis tests can help identify patients with A1ATD liver injury. However, APRI and FIB-4 scores alone had poor sensitivity and specificity to justify use as an independent tool for liver pathology in A1ATD.

A Highly Phenotyped Open Access Repository of Alpha-1 Antitrypsin Deficiency Pluripotent Stem Cells.

Individuals with the genetic disorder alpha-1 antitrypsin deficiency (AATD) are at risk of developing lung and liver disease. Patient induced pluripotent stem cells (iPSCs) have been found to model features of AATD pathogenesis but only a handful of AATD patient iPSC lines have been published. To capture the significant phenotypic diversity of the patient population, we describe here the establishment and characterization of a curated repository of AATD iPSCs with associated disease-relevant clinical data. To highlight the utility of the repository, we selected a subset of iPSC lines for functional characterization. Selected lines were differentiated to generate both hepatic and lung cell lineages and analyzed by RNA sequencing. In addition, two iPSC lines were targeted using CRISPR/Cas9 editing to accomplish scarless repair. Repository iPSCs are available to investigators for studies of disease pathogenesis and therapeutic discovery.

Regional lung densities in alpha-1 antitrypsin deficiency compared to predicted values.

BACKGROUND: We developed a method to calculate a standard score for lung tissue mass derived from CT scan images from a control group without respiratory disease. We applied the method to images from subjects with emphysema associated with alpha-1 antitrypsin deficiency (AATD) and used it to study regional patterns of differential tissue mass. METHODS: We explored different covariates in 76 controls. Standardization was applied to facilitate comparability between different CT scanners and a standard Z-score (Standard Mass Score, SMS) was developed, representing lung tissue loss compared to normal lung mass. This normative data was defined for the entire lungs and for delineated apical, central and basal regions. The agreement with DLCO%pred was explored in a data set of 180 patients with emphysema who participated in a trial of alpha-1-antitrypsin augmentation treatment (RAPID). RESULTS: Large differences between emphysematous and normal tissue of more than 10 standard deviations were found. There was reasonable agreement between SMS and DLCO%pred for the global densitometry (κ = 0.252, p < 0.001), varying from κ = 0.138 to κ = 0.219 and 0.264 (p < 0.001), in the apical, central and basal region, respectively. SMS and DLCO%pred correlated consistently across apical, central and basal regions. The SMS distribution over the different lung regions showed a distinct pattern suggesting that emphysema due to severe AATD develops from basal to central and ultimately apical regions. CONCLUSIONS: Standardization and normalization of lung densitometry is feasible and the adoption of the developed principles helps to characterize the distribution of emphysema, required for clinical decision making.

Double lung transplantation in an HIV-positive patient with Mycobacterium kansasii infection.

Good outcomes with kidney and liver transplantation in HIV-positive patients have led clinicians to recommend lung transplantation in HIV-positive patients based on extrapolated data. Pre-transplant mycobacterial infection is associated with an increased risk of developing new infection or aggravating existing infection, though it does not contraindicate transplantation in non-HIV-infected patients. However, no data exists regarding the outcome of HIV-positive patients with pre-transplant mycobacterial infection. We report a case of double lung transplantation in a 50-year-old HIV-positive patient with alpha-1 antitrypsin deficiency. Prior to transplantation, Mycobacterium kansasii was isolated in one sputum culture and the patient was considered merely colonized as no clinical evidence of pulmonary or disseminated disease was present. The patient successfully underwent a double lung transplantation. Nontuberculous mycobacterial infection was diagnosed histologically on examination of native lungs. Surveillance and watchful waiting were chosen over treatment of the infection. HIV remained under control post-transplantation with no AIDS-defining illnesses throughout the follow-up. A minimal acute rejection that responded to increased corticosteroids was reported. At 12 months post-transplant, a bronchiolitis obliterans syndrome was diagnosed after a drop in FEV1. No evidence of isolation nor recurrence of nontuberculous mycobacteria was reported post-transplantation. At 15 months post-transplant, the patient remained stable with an FEV1 of 30%. The presence of pre-transplant nontuberculous mycobacterial infection did not translate into recurrence of nontuberculous mycobacterial infection post-transplant. Whether it contributed to bronchiolitis obliterans syndrome remains unknown.

Lung function and CT lung densitometry in 37- to 39-year-old individuals with alpha-1-antitrypsin deficiency.

BACKGROUND: Alpha-1-antitrypsin (AAT) deficiency is a hereditary disorder that predisposes to emphysema. A cohort of severe (PiZZ) and moderate (PiSZ) AAT-deficient newborn infants was identified by the Swedish national neonatal AAT screening program in 1972-1974 and has been followed-up since birth. Our aim was to study whether the cohort has signs of emphysema in pulmonary function tests (PFTs) and computed tomography (CT) densitometry at 38 years of age in comparison with an age-matched control group, randomly selected from the population registry. METHODS: Forty-one PiZZ, 18 PiSZ, and 61 control subjects (PiMM) underwent complete PFTs, measurement of resistance and reactance in the respiratory system by impulse oscillometry (IOS)/forced oscillation technique (FOT), and CT densitometry. The results were related to self-reported smoking habits. RESULTS: The total lung capacity (TLC) % of the predicted value was significantly higher in the PiZZ ever-smokers than in the PiZZ never-smokers (P<0.05), PiSZ never-smokers (P=0.01) and the PiMM never-smokers (P=0.01). The residual volume (RV) % of the predicted value was significantly higher in the PiZZ ever-smokers compared to the PiMM never-smokers (P<0.01). The PiZZ ever-smokers had a significantly lower carbon monoxide transfer coefficient (Kco) than the PiSZ never-smokers (P<0.01) and PiMM never-smokers (P<0.01). Respiratory system resistance at 5 Hz (P<0.01), at 20 Hz (P<0.01), and the area of low reactance (Alx; P<0.05) were significantly lower and respiratory system reactance at 5 Hz (P<0.05) was significantly higher in PiZZ subjects compared to the PiMM subjects. No statistically significant differences in the CT densitometry parameters were found between the Pi subgroups. CONCLUSION: The physiological parameters in the PiZZ ever-smokers showed evidence of hyperinflation and emphysema before the age of 40 years.

Similarities in the Computed Tomography Appearance in α1-Antitrypsin Deficiency and Smoking-Related Chronic Obstructive Pulmonary Disease in a Smoking Collective.

BACKGROUND: Emphysematous destruction of lung parenchyma visible in computed tomography (CT) can be attributed to chronic obstructive pulmonary disease (COPD) or to α1-antitrypsin deficiency (AATD). OBJECTIVES: We evaluated if visual semiquantitative phenotyping of CT data helps identifying individuals with AATD in a group of smokers with severe emphysema and airflow limitation. METHOD: n = 14 patients with AATD and n = 15 with COPD and a minimum of 10 pack years underwent CT, clinical assessment, and full-body plethysmography. The extent and type of emphysema as well as large and small airway changes were rated semiquantitatively for each lobe using a standardized previously published scoring system. Lastly, a final diagnosis for each patient was proposed. RESULTS: AATD had a significantly lower mean emphysema score than COPD, with 8.9 ± 3.4 versus 11.9 ± 3.2 (p < 0.001), respectively. Within both groups, there was significantly more emphysema in the lower lobes (p < 0.05-0.001). The COPD group showed an upper- and middle-lobe predominance of emphysema distribution when compared to the AATD group (p < 0.001). Centrilobular (CLE) and panlobular (PLE) emphysema patterns showed a uniform distribution within both groups, with a CLE predominance in the upper lung and a PLE predominance in the lower lung regions. AATD and COPD both showed significantly more airway changes in lower lobes compared to upper lobes (p = 0.05-0.001), without significant differences between both groups. CONCLUSION: The typical emphysema distribution patterns seen on CT traditionally assigned to AATD and COPD were of little use in discriminating both entities. Also, airway changes could not contribute to a more precise differentiation. We conclude that a concise standardized phenotyping-driven approach to chest CT in emphysema is not sufficient to identify patients with AATD in a cohort of smokers with advanced emphysema.

The Role of Computed Tomography for the Evaluation of Lung Disease in Alpha-1 Antitrypsin Deficiency.

Alpha-1 antitrypsin deficiency (AATD) is characterized by low serum levels of or dysfunctional alpha-1 proteinase inhibitor. In the lung parenchyma, this results in a loss of protection against the activity of serine proteases, particularly neutrophil elastase. The resultant imbalance in protease and antiprotease activity leads to an increased risk for the development of early-onset emphysema and COPD. As in traditional smoke-related COPD, the assessment of the severity and disease progression of lung disease in AATD is conventionally based on lung function; however, pulmonary function tests are unable to discriminate between emphysema and airways disease, the two hallmark pathologic features of COPD. CT imaging has been used as a tool to further characterize lung structure and evaluate therapeutic interventions in AATD-related COPD. Moreover, recent advances in quantitative CT have significantly improved our assessment of the lung architecture, which has provided investigators and clinicians with a more detailed evaluation of the extent and severity of emphysema and airways disease in AATD. In addition, serial CT imaging measures are becoming increasingly important, as they provide a tool to monitor emphysema progression. This review describes the principles of CT technology and the role of CT imaging in assessing pulmonary disease progression in AATD, including the effect of therapeutic interventions.

Pulmonary MRI morphometry modeling of airspace enlargement in chronic obstructive pulmonary disease and alpha-1 antitrypsin deficiency.

PURPOSE: We generated lung morphometry measurements using single-breath diffusion-weighted MRI and three different acinar duct models in healthy participants and patients with emphysema stemming from chronic obstructive lung disease (COPD) and alpha-1 antitrypsin deficiency (AATD). METHODS: Single-breath-inhaled 3 He MRI with five diffusion sensitizations (b-value = 0, 1.6, 3.2, 4.8, and 6.4 s/cm2 ) was used, and signal intensities were fit using a cylindrical and single-compartment acinar-duct model to estimate MRI-derived mean linear intercept (Lm ) and surface-to-volume ratio (S/V). A stretched exponential model was also developed to estimate the mean airway length and Lm . RESULTS: We evaluated 42 participants, including 15 elderly never-smokers (69 ± 5 years), 12 ex-smokers without COPD (67 ± 11 years), 9 COPD ex-smokers (80 ± 6 years), and 6 AATD patients (59 ± 6 years). In the never- and ex-smokers, the diffusing capacity of the lung for carbon monoxide (DLCO ) and computed tomography relative area of less than -950 Hounsfield units (RA950 ) were normal, but these were abnormal in the COPD and AATD patients, which is reflective of emphysema. Although cylindrical and stretched-exponential-model estimates of Lm and S/V were not significantly different, the single-compartment-model estimates were significantly different (P < 0.05) for the never- and ex-smoker subgroups. All models estimated significantly worse Lm and S/V in the AATD and COPD subgroups compared with the never- and ex-smokers without emphysema. CONCLUSIONS: Differences in airspace enlargement may be estimated using Lm and S/V, generated using MRI and a stretched-exponential or cylindrical model of the acinar ducts. Magn Reson Med 79:439-448, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Smoking-Related Interstitial Fibrosis: Evidence of Radiologic Regression with Advancing Age and Smoking Cessation.

More data are needed regarding the radiology, co-morbidities and natural history of smoking-related interstitial fibrosis (SRIF), a common pathological finding, mainly described heretofore in association with lung cancer, where respiratory bronchiolitis (RB) usually co-exists. We prospectively acquired high resolution CT scan data (edge-enhancing lung reconstructions) to detect any radiologic interstitial lung abnormality (ILA) in individuals who ultimately underwent surgical lobectomy for lung cancer (n = 20), for radiologic/pathologic correlation. We also re-examined other smoking-related benign histologic cases: chronic obstructive pulmonary disease (COPD lung explants, n = 20), alpha 1-antitrypsin deficiency (A1AT, explanted lungs n = 20), combined pulmonary fibrosis and emphysema (CPFE, n = 8) and idiopathic pulmonary fibrosis (IPF, n = 10). Finally, we pooled our data with all peer-reviewed published data describing histologic SRIF of known ILA status. SRIF was observed in 40% of cancer lobectomies, mean (±SD) age 65.8 ± 8.7 years, none of whom had ILA. SRIF was observed in other smoking-related benign diseases (COPD 35%, A1AT 20%, CPFE 25%, and IPF 10%). 71.4% of benign SRIF cases had no RB (nearly all ex-smokers) versus 0% of cancer-associated SRIF cases (P = 1.7 × 10-3). Pooled data showed that those SRIF subjects without ILA were 15.05 years older than those with ILA (95% confidence interval 8.99 to 21.11, P = 2.5 × 10-5) and more likely to be former smokers (P = 7.2 × 10-3). SRIF is frequently found without lung cancer, and mostly without RB in former smokers. SRIF is less likely to have ILA in older subjects and with smoking cessation, which could represent RB+/-SRIF regression.

Quantitative disease progression model of α-1 proteinase inhibitor therapy on computed tomography lung density in patients with α-1 antitrypsin deficiency.

AIMS: Early-onset emphysema attributed to α-1 antitrypsin deficiency (AATD) is frequently overlooked and undertreated. RAPID-RCT/RAPID-OLE, the largest clinical trials of purified human α-1 proteinase inhibitor (A1 -PI; 60 mg kg-1  week-1 ) therapy completed to date, demonstrated for the first time that A1 -PI is clinically effective in slowing lung tissue loss in AATD. A posthoc pharmacometric analysis was undertaken to further explore dose, exposure and response. METHODS: A disease progression model was constructed, utilizing observed A1 -PI exposure and lung density decline rates (measured by computed tomography) from RAPID-RCT/RAPID-OLE, to predict effects of population variability and higher doses on A1 -PI exposure and clinical response. Dose-exposure and exposure-response relationships were characterized using nonlinear and linear mixed effects models, respectively. The dose-exposure model predicts summary exposures and not individual concentration kinetics; covariates included baseline serum A1 -PI, forced expiratory volume in 1 s and body weight. The exposure-response model relates A1 -PI exposure to lung density decline rate at varying exposure levels. RESULTS: A dose of 60 mg kg-1  week-1 achieved trough serum levels >11 µmol l-1 (putative 'protective threshold') in ≥98% patients. Dose-exposure-response simulations revealed increasing separation between A1 -PI and placebo in the proportions of patients achieving higher reductions in lung density decline rate; improvements in decline rates ≥0.5 g l-1  year-1 occurred more often in patients receiving A1 -PI: 63 vs. 12%. CONCLUSION: Weight-based A1 -PI dosing reliably raises serum levels above the 11 µmol l-1 threshold. However, our exposure-response simulations question whether this is the maximal, clinically effective threshold for A1 -PI therapy in AATD. The model suggested higher doses of A1 -PI would yield greater clinical effects.

An ECLIPSE View of Alpha-1 Antitrypsin Deficiency.

Chronic obstructive pulmonary disease (COPD) is a multicomponent condition that is estimated to become the third leading cause of death in 2020. The ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) study, funded by GlaxoSmithKline, is an observational study designed to define outcomes that can be used as endpoints in clinical trials in individuals with COPD. It allowed us to describe the heterogeneity of COPD, the stability of the exacerbation phenotype, and the factors associated with a progressive decline in lung function and the progression of emphysema on computed tomography scans. The cohort was also used to define genetic factors and biomarkers associated with COPD and disease progression. This review considers how the results from ECLIPSE can inform our understanding of the lung disease associated with alpha-1 antitrypsin deficiency.

Randomized, Placebo-Controlled Trials in Alpha-1 Antitrypsin Deficiency.

Alpha-1 antitrypsin deficiency (AATD) is a condition caused by the inheritance of two mutated SERPINA1 gene alleles. Individuals with AATD are at increased risk of injury to the liver and lungs. The pulmonary manifestations include precocious onset of pulmonary emphysema and bronchiectasis. For nearly three decades, treatment has been available to individuals with emphysema caused by AATD, but this therapy-augmentation of plasma and tissue alpha-1 antitrypsin levels by intravenous administration of human plasma-derived protein-was approved by regulatory authorities based on its biochemical efficacy. This therapy appears to slow the progression of emphysema in patients with AATD. The medical, patient, and regulatory communities have sought assurance that this expensive therapy provides measurable clinical benefit. Documenting such benefit has been difficult because of the slow progression of the underlying lung disease in AATD, the rarity of this genetic condition, and the lack of direct quantitative measurements of emphysema progression. Over the past decade, quantitative computed tomography (CT) densitometry of the lungs has been found to correlate with severity and progression of emphysema. The recent publication of a well-powered, masked, placebo-controlled study using CT densitometry to evaluate the effectiveness of augmentation therapy at slowing the progression of emphysema has provided some assurance of the clinical efficacy of this therapy.

The Association Between α1-Antitrypsin and Coronary Artery Ectasia.

Coronary artery ectasia (CAE) is associated with coronary artery disease (CAD). The underlying pathophysiology of CAE is not fully understood. α1-antitrypsin (A1AT) plays a role in the tissue protease system, and AAT-1 deficiency (A1ATD) has been shown to be related to CAD. We compared A1AT serum levels in patients with and without CAE to determine the association between A1AT levels and the extent of ectasia using the Markis score. We included 50 patients (38 males) with isolated CAE and 46 patients (28 males) with normal coronary arteries after coronary angiography. The levels of A1AT were measured by nephelometry. The median A1AT levels were lower in patients with isolated CAE than in the control group (1.27 ng/mL [range: 1.07-1.37 ng/mL] vs 1.43 ng/mL [range: 1.27-1.59 ng/mL]; P < .001). According to the Markis classification, the extent of CAE was not correlated with A1AT levels ( P = .41). Our results demonstrate an inverse relationship between serum A1AT levels and CAE. α1-antitrypsin is fundamental for the stability and integrity of the arterial wall. Lack of elastase inhibition in cases of A1ATD may contribute to ectasia formation by facilitating proteolysis and weakening the arterial wall.

Lung density associates with survival in alpha 1 antitrypsin deficient patients.

INTRODUCTION: CT density correlates with quality of life (QOL) scores and impaired upper zone lung density associates with higher mortality in alpha one antitrypsin deficiency (A1ATD). We hypothesised that decline in CT densitometry would relate to survival or deterioration in QOL in A1ATD. METHODS: All augmentation naïve PiZZ patients in the UK A1ATD registry with ≥ two successive quantitative CT scans were selected. Patients were divided into groups based on CT density decline and the relationship to survival and change in QOL compared by univariate analyses and multivariate Cox regression. Analyses were performed for whole lung, upper zone and lower zone density separately. Exploratory analyses of FEV1 subgroups were conducted. RESULTS: 110 patients were identified; 77 had whole lung and lung zone density recorded on two CT scans, 33 patients had upper zone data only on four scans. Decline in lower zone density associated with survival, even after adjustment for baseline lung density (p = 0.048), however upper zone density and whole lung density decline did not. This difference appeared to be driven by those with FEV1 >30% predicted. CONCLUSION: Rate of change in lung densitometry could predict survival in A1ATD.

Echocardiographic evaluation in subjects with α1-Antitrypsin deficiency.

BACKGROUND: α1-Antitrypsin (AAT) deficiency (AATD) is a genetic condition associated with early-onset panacinar emphysema and, less often, vascular disease. Recently, abnormal elastic properties of ascending aortic wall were described in ZZ genotype AATD subjects who incidentally showed an increased left ventricular mass. MATERIALS AND METHODS: To evaluate biventricular dimensions, valvular apparatus, systolic and diastolic function, 33 AATD subjects with ZZ genotype and 33 healthy subjects matched for age and sex underwent a complete echocardiographic assessment. RESULTS: Compared to controls, AATD subjects showed increased left ventricular mass (160 ± 59 g vs. 121 ± 70 g, P < 0.001), a higher incidence of left and right ventricular diastolic dysfunction (30% vs. 16%, P < 0.001 and 45% vs. 20%, P < 0.001, respectively) and mitral valve prolapse (35% vs. 6%, P < 0.001). In contrast, there was no difference between the two groups in diameters and systolic function of both ventricles and in the ejection fraction of left ventricle. The functions of aortic and tricuspidal valves were also similar. CONCLUSIONS: In the presence of greater left ventricular mass, a significantly higher incidence of left and right ventricular diastolic dysfunction and mitral valve prolapse occurs in AATD subjects (ZZ genotype). These findings strongly suggest an abnormal remodelling process in cardiac tissue in AATD.

Intravenous augmentation treatment and lung density in severe α1 antitrypsin deficiency (RAPID): a randomised, double-blind, placebo-controlled trial.

BACKGROUND: The efficacy of α1 proteinase inhibitor (A1PI) augmentation treatment for α1 antitrypsin deficiency has not been substantiated by a randomised, placebo-controlled trial. CT-measured lung density is a more sensitive measure of disease progression in α1 antitrypsin deficiency emphysema than spirometry is, so we aimed to assess the efficacy of augmentation treatment with this measure. METHODS: The RAPID study was a multicentre, double-blind, randomised, parallel-group, placebo-controlled trial of A1PI treatment in patients with α1 antitrypsin deficiency. We recruited eligible non-smokers (aged 18-65 years) in 28 international study centres in 13 countries if they had severe α1 antitrypsin deficiency (serum concentration <11 µM) with a forced expiratory volume in 1 s of 35-70% (predicted). We excluded patients if they had undergone, or were on the waiting list to undergo, lung transplantation, lobectomy, or lung volume-reduction surgery, or had selective IgA deficiency. We randomly assigned patients (1:1; done by Accovion) using a computerised pseudorandom number generator (block size of four) with centre stratification to receive A1PI intravenously 60 mg/kg per week or placebo for 24 months. All patients and study investigators (including those assessing outcomes) were unaware of treatment allocation throughout the study. Primary endpoints were CT lung density at total lung capacity (TLC) and functional residual capacity (FRC) combined, and the two separately, at 0, 3, 12, 21, and 24 months, analysed by modified intention to treat (patients needed at least one evaluable lung density measurement). This study is registered with ClinicalTrials.gov, number NCT00261833. A 2-year open-label extension study was also completed (NCT00670007). FINDINGS: Between March 1, 2006, and Nov 3, 2010, we randomly allocated 93 (52%) patients A1PI and 87 (48%) placebo, analysing 92 in the A1PI group and 85 in the placebo group. The annual rate of lung density loss at TLC and FRC combined did not differ between groups (A1PI -1·50 g/L per year [SE 0·22]; placebo -2·12 g/L per year [0·24]; difference 0·62 g/L per year [95% CI -0·02 to 1·26], p=0·06). However, the annual rate of lung density loss at TLC alone was significantly less in patients in the A1PI group (-1·45 g/L per year [SE 0·23]) than in the placebo group (-2·19 g/L per year [0·25]; difference 0·74 g/L per year [95% CI 0·06-1·42], p=0·03), but was not at FRC alone (A1PI -1·54 g/L per year [0·24]; placebo -2·02 g/L per year [0·26]; difference 0·48 g/L per year [-0·22 to 1·18], p=0·18). Treatment-emergent adverse events were similar between groups, with 1298 occurring in 92 (99%) patients in the A1PI group and 1068 occuring in 86 (99%) in the placebo group. 71 severe treatment-emergent adverse events occurred in 25 (27%) patients in the A1PI group and 58 occurred in 27 (31%) in the placebo group. One treatment-emergent adverse event leading to withdrawal from the study occurred in one patient (1%) in the A1PI group and ten occurred in four (5%) in the placebo group. One death occurred in the A1PI group (respiratory failure) and three occurred in the placebo group (sepsis, pneumonia, and metastatic breast cancer). INTERPRETATION: Measurement of lung density with CT at TLC alone provides evidence that purified A1PI augmentation slows progression of emphysema, a finding that could not be substantiated by lung density measurement at FRC alone or by the two measurements combined. These findings should prompt consideration of augmentation treatment to preserve lung parenchyma in individuals with emphysema secondary to severe α1 antitrypsin deficiency. FUNDING: CSL Behring.