Phenotypic Differences in Alpha 1 Antitrypsin-Deficient Sibling Pairs May Relate to Genetic Variation

Antitrypsin deficiency: still more to learn about the lung after 60 years

The past 60 years have seen multiple publications related to lung disease in α1-antitrypsin deficiency largely reflecting the pathophysiology, biochemical effect and outcomes of augmentation therapy. However, the complexity of disease phenotype and the impact of the natural history presents problems of patient management, study design and hence interpretation of outcome. Although many national and some international registries exist, the lack of consistent in-depth assessment and importantly, the impact of augmentation therapy likely influences our perception of the true natural history. Development of new therapeutic strategies, and even assessment of the role and efficacy of augmentation, remain a challenge as powering such studies for conventional COPD outcomes is impractical due to relative rarity of the genetic condition and the presence of clinical phenotypic variation. The current review approaches these issues, discusses the nature and complexity of assessing patient variability, and provides guidance on further studies required to address them.

Research priorities in α1-antitrypsin deficiency: results of a patients' and healthcare providers' international survey from the EARCO Clinical Research Collaboration

α₁-antitrypsin deficiency (AATD) is a rare and under-recognised genetic condition. Owing to its low prevalence, international initiatives are key for conducting high-quality research in the field.

From July 2018 to December 2019, the European Alpha-1 Research Collaboration (EARCO) developed and conducted two surveys, one for healthcare providers and one for patients and caregivers, aiming to identify research priorities and barriers in access to treatment for AATD.

A survey on 164 research questions was electronically sent to 230 AATD experts in Europe, and 94 completed surveys from 24 countries were received. The top research areas identified by healthcare providers were causes of variable progression and poor outcomes, improvement in diagnosis, initiation and optimal dosing of augmentation therapy and effectiveness of self-management interventions. During the same period, 438 surveys were completed by patients and caregivers from 26 countries. The top research areas identified were improving knowledge about AATD, in particular among general practitioners, access to AATD specialised centres and access to reliable, easy to understand information about living with AATD. Regarding barriers to treatment, participants from countries where augmentation therapy was reimbursed prioritised improving knowledge in AATD, while respondents in non-reimbursed countries regarded access to AATD augmentation therapy and to specialised centres as the most relevant.

The main research and management priorities identified by healthcare providers and patients included understanding the natural history of AATD, improving information to physicians, improving access to specialised reference centres, personalising treatment and having equal opportunities for access to existing therapies.

Surveys for patients and healthcare providers on research priorities in AATD, developed by the @EuroRespSoc CRC EARCO, show that international collaboration and engagement with patients are key development strategies needed for improvementhttps://bit.ly/2ItIzaW

Clinical manifestations in patients with PI*MMMalton genotypes. A matter still unsolved in alpha-1 antitrypsin deficiency

We report the genetic variants associated with alpha-1 antitrypsin deficiency (AATD) in 117 patients admitted to our outpatient clinic and characterized by a serum concentration of AAT lower than 113 mg/dL. We focused on the M-like heterozygous variant of the SERPINA1 gene called PI*MMMalton, and describe three patients with this variant. While the role of homozygous AATD in liver and pulmonary disease is well established, the association between heterozygous AATD and chronic liver and pulmonary disease is still under investigation. The PI*MMMalton genotype was found in 5.8% of patients with a pathological genotype of AATD and in 14.3% of the subjects when considering only those with intermediate AATD. There were no liver or renal abnormalities in patients with the PI*MMMalton genotype. The PI*MMMalton patients included here showed a normal liver function, and none had renal function abnormalities or abdominal aortic aneurysm. Only a prevalence of lung disease was detected.

Alpha-1 Antitrypsin Deficiency: Phenotypes and Quality of Life

Alpha-1 antitrypsin deficiency (AATD) is a recognized genetic cause of rapidly progressive loss of lung function conventionally assessed by the decline in FEV1. However, there is less information concerning other physiological measures and the impact on quality of life. Data derived predominantly from the UK national registry show that AATD presents with various physiological phenotypes with differing clinical impact and progression. In general, the decline in quality of life is surprisingly slow despite rapid loss of lung function, which may reflect the benefits of centralized services for patients with AATD. Use of the new GOLD classification identifies patient characteristics that relate to mortality and disparate symptomatology despite similar spirometric impairment.

European Respiratory Society statement: diagnosis and treatment of pulmonary disease in α1-antitrypsin deficiency

α1-antitrypsin deficiency (AATD) is the most common hereditary disorder in adults. It is associated with an increased risk of developing pulmonary emphysema and liver disease. The pulmonary emphysema in AATD is strongly linked to smoking, but even a proportion of never-smokers develop progressive lung disease. A large proportion of individuals affected remain undiagnosed and therefore without access to appropriate care and treatment.

The most recent international statement on AATD was published by the American Thoracic Society and the European Respiratory Society in 2003. Since then there has been a continuous development of novel, more accurate and less expensive genetic diagnostic methods. Furthermore, new outcome parameters have been developed and validated for use in clinical trials and a new series of observational and randomised clinical trials have provided more evidence concerning the efficacy and safety of augmentation therapy, the only specific treatment available for the pulmonary disease associated with AATD.

As AATD is a rare disease, it is crucial to organise national and international registries and collect information prospectively about the natural history of the disease. Management of AATD patients must be supervised by national or regional expert centres and inequalities in access to therapies across Europe should be addressed.

Maximal mid-expiratory flow detects early lung disease in α1-antitrypsin deficiency

Pathological studies suggest that loss of small airways precedes airflow obstruction and emphysema in chronic obstructive pulmonary disease (COPD). Not all α₁-antitrypsin deficiency (AATD) patients develop COPD, and measures of small airways function might be able to detect those at risk.Maximal mid-expiratory flow (MMEF), forced expiratory volume in 1 s (FEV₁), ratio of FEV₁/forced vital capacity (FVC), health status, presence of emphysema (computed tomography (CT) densitometry) and subsequent decline in FEV₁ were assessed in 196 AATD patients.FEV₁/FVC, FEV₁ % predicted and lung densitometry related to MMEF % pred (r²=0.778, p<0.0001; r²=0.787, p<0.0001; r²=0.594, p<0.0001, respectively) in a curvilinear fashion. Patients could be divided into those with normal FEV₁/FVC and MMEF (group 1), normal FEV₁/FVC and reduced MMEF (group 2) and those with spirometrically defined COPD (group 3). Patients in group 2 had worse health status than group 1 (median total St George's Respiratory Questionnaire (SGRQ) 23.15 (interquartile range (IQR) 7.09-39.63) versus 9.67 (IQR 1.83-22.35); p=0.006) and had a greater subsequent decline in FEV₁ (median change in FEV₁ -1.09% pred per year (IQR -1.91-0.04% pred per year) versus -0.04% pred per year (IQR -0.67-0.03% pred per year); p=0.007).A reduction in MMEF is an early feature of lung disease in AATD and is associated with impaired health status and a faster decline in FEV₁.

Rationale and Design of the Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis Study. Alpha-1 Protocol

Severe deficiency of alpha-1 antitrypsin has a highly variable clinical presentation. The Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis α1 Study is a prospective, multicenter, cross-sectional study of adults older than age 35 years with PiZZ or PiMZ alpha-1 antitrypsin genotypes. It is designed to better understand if microbial factors influence this heterogeneity. Clinical symptoms, pulmonary function testing, computed chest tomography, exercise capacity, and bronchoalveolar lavage (BAL) will be used to define chronic obstructive pulmonary disease (COPD) phenotypes that can be studied with an integrated systems biology approach that includes plasma proteomics; mouth, BAL, and stool microbiome and virome analysis; and blood microRNA and blood mononuclear cell RNA and DNA profiling. We will rely on global genome, transcriptome, proteome, and metabolome datasets. Matched cohorts of PiZZ participants on or off alpha-1 antitrypsin augmentation therapy, PiMZ participants not on augmentation therapy, and control participants from the Subpopulations and Intermediate Outcome Measures in COPD Study who match on FEV1 and age will be compared. In the primary analysis, we will determine if the PiZZ individuals on augmentation therapy have a difference in lower respiratory tract microbes identified compared with matched PiZZ individuals who are not on augmentation therapy. By characterizing the microbiome in alpha-1 antitrypsin deficiency (AATD), we hope to define new phenotypes of COPD that explain some of the diversity of clinical presentations. As a unique genetic cause of COPD, AATD may inform typical COPD pathogenesis, and better understanding of it may illuminate the complex interplay between environment and genetics. Although the biologic approaches are hypothesis generating, the results may lead to development of novel biomarkers, better understanding of COPD phenotypes, and development of novel diagnostic and therapeutic trials in AATD and COPD. Clinical trial registered with www.clinicaltrials.gov (NCT01832220).

Antitrypsin Deficiency Assessment and Programme for Treatment (ADAPT): The United Kingdom Registry

The study of rare diseases is compromised by its rarity. The establishment of national and international registries can overcome many of the problems and be used for many monogenetic conditions with relatively consistent outcomes and thus lead to a consistency of clinical management by centres of excellence. However, in Alpha-1 antitrypsin deficiency (AATD), the outcome is highly variable in terms of the organ(s) most affected and the diversity of disease penetration and progression. This creates the added difficulty of understanding the disease sufficiently to monitor and advise the patients to the standard required and importantly design and deliver clinical trials that address the many facets of the disease. The development of research registries and centres of excellence provides the necessary expertise and data to further the understanding and management of diseases like AATD though with significant cost implications. The ADAPT programme was established in 1996 with extensive core funding to enable patients to be seen from all regions of the United Kingdom as an addition to the National Health Service without appointment time constraints and with the purpose of collecting extensive state of the art demographics. The model has proven to be highly productive providing new insights especially into the lung disease, generating and delivering on clinical trials and importantly establishing active patient groups and participation.

Vitamin D-binding protein gene polymorphisms and chronic obstructive pulmonary disease susceptibility: A meta-analysis

The vitamin D-binding protein (VDBP) genetic polymorphisms have been associated with chronic obstructive pulmonary disease (COPD). A number of studies have been conducted to investigate the combined effects of the VDBP gene (GC) rs7041 and rs4588 polymorphisms on the COPD risk. However, the results obtained are inconclusive. The present meta-analysis aimed to investigate whether GC polymorphisms may be a potential risk factor for COPD. The Web of Science, PubMed, Google Scholar, Embase, Cochrane Library, China National Knowledge Infrastructure and Wanfang Database were searched from inception until June 1, 2014. The meta-analysis was performed using the STATA 12.0 software. Twelve case-control studies, including 2,937 subjects, met the inclusion criteria. Overall, a significantly increased risk was detected in populations of GC*1F homozygotes, whereas no associations between other GC polymorphisms and COPD risk were detected. According to ethnicity, the results demonstrated that the GC*1F homozygotes may be a risk factor for COPD and the GC*2 homozygotes may be a protective factor against COPD in the Asian population. However, similar associations were not observed among the Caucasian population. In conclusion, the current meta-analysis indicates that the GC*1F homozygotes may be a risk factor for COPD and the GC*2 homozygotes may be a protective factors against COPD in the Asian population.

α-1-Antitrypsin deficiency: clinical variability, assessment, and treatment

The recognition of α-1-antitrypsin deficiency, its function, and its role in predisposition to the development of severe emphysema was a watershed in our understanding of the pathophysiology of the condition. This led to the concept and development of intravenous replacement therapy used worldwide to protect against lung damage induced by neutrophil elastase. Nevertheless, much remained unknown about the deficiency and its impact, although in recent years the genetic and clinical variations in manifestation have provided new insights into assessing impact, efficacy of therapy, and development of new therapeutic strategies, including gene therapy, and outcome measures, such as biomarkers and computed tomography. The current article reviews this progress over the preceding 50 years.

Augmentation therapy for alpha-1 antitrypsin deficiency: towards a personalised approach

Background

Intravenous augmentation therapy is the only specific treatment available for emphysema associated with alpha-1 antitrypsin deficiency. Despite large observational studies and limited interventional studies there remains controversy about the efficacy of this treatment due to the impracticality of conducting adequately powered studies to evaluate the rate of decline in lung function, due to the low prevalence and the slow progression of the disease. However, measurement of lung density by computed tomography is a more specific and sensitive marker of the evolution of emphysema and two small placebo-controlled clinical trials have provided evidence supporting a reduction in the rate of decline in lung density with augmentation therapy.

The problem

Where augmentation therapy has become available there has been little consideration of a structured approach to therapy which is often introduced on the basis of functional impairment at diagnosis. Data from registries have shown a great variability in the evolution of lung disease according to patient acquisition and the presence of recognised risk factors. Avoidance of risk factors may, in many cases, stabilise the disease. Since augmentation therapy itself will at best preserve the presenting level of lung damage yet require intravenous administration for life with associated costs, identification of patients at risk of continued rapid or long term progression is essential to select those for whom this treatment can be most appropriate and hence generally more cost-effective. This represents a major reconsideration of the current practice in order to develop a consistent approach to management world wide.

Purpose of this review

The current review assesses the evidence for efficacy of augmentation therapy and considers how the combination of age, physiological impairment, exacerbation history and rate of decline in spirometry and other measures of emphysema may be used to improve therapeutic decision making, until a reliable predictive biomarker of the evolution of lung impairment can be identified. In addition, individual pharmacokinetic studies may permit the selection of the best regimen of administration for those who need it.

Summary

The rarity and variable characteristics of the disease imply the need for an individualised approach to therapy in specialised centres with sufficient experience to apply a systematic approach to monitoring and management.

Association of IREB2 and CHRNA3 polymorphisms with airflow obstruction in severe alpha-1 antitrypsin deficiency

Background

The development of COPD in subjects with alpha-1 antitrypsin (AAT) deficiency is likely to be influenced by modifier genes. Genome-wide association studies and integrative genomics approaches in COPD have demonstrated significant associations with SNPs in the chromosome 15q region that includes CHRNA3 (cholinergic nicotine receptor alpha3) and IREB2 (iron regulatory binding protein 2).

We investigated whether SNPs in the chromosome 15q region would be modifiers for lung function and COPD in AAT deficiency.

Methods

The current analysis included 378 PIZZ subjects in the AAT Genetic Modifiers Study and a replication cohort of 458 subjects from the UK AAT Deficiency National Registry. Nine SNPs in LOC123688, CHRNA3 and IREB2 were selected for genotyping. FEV₁ percent of predicted and FEV₁/FVC ratio were analyzed as quantitative phenotypes. Family-based association analysis was performed in the AAT Genetic Modifiers Study. In the replication set, general linear models were used for quantitative phenotypes and logistic regression models were used for the presence/absence of emphysema or COPD.

Results

Three SNPs (rs2568494 in IREB2, rs8034191 in LOC123688, and rs1051730 in CHRNA3) were associated with pre-bronchodilator FEV₁ percent of predicted in the AAT Genetic Modifiers Study. Two SNPs (rs2568494 and rs1051730) were associated with the post-bronchodilator FEV₁ percent of predicted and pre-bronchodilator FEV₁/FVC ratio; SNP-by-gender interactions were observed. In the UK National Registry dataset, rs2568494 was significantly associated with emphysema in the male subgroup; significant SNP-by-smoking interactions were observed.

Conclusions

IREB2 and CHRNA3 are potential genetic modifiers of COPD phenotypes in individuals with severe AAT deficiency and may be sex-specific in their impact.

The role of proteases, endoplasmic reticulum stress and SERPINA1 heterozygosity in lung disease and α-1 anti-trypsin deficiency

The serine proteinase inhibitor α-1 anti-trypsin (AAT) provides an antiprotease protective screen throughout the body. Mutations in the AAT gene (SERPINA1) that lead to deficiency in AAT are associated with chronic obstructive pulmonary diseases. The Z mutation encodes a misfolded variant of AAT that is not secreted effectively and accumulates intracellularly in the endoplasmic reticulum of hepatocytes and other AAT-producing cells. Until recently, it was thought that loss of antiprotease function was the major cause of ZAAT-related lung disease. However, the contribution of gain-of-function effects is now being recognized. Here we describe how both loss- and gain-of-function effects can contribute to ZAAT-related lung disease. In addition, we explore how SERPINA1 heterozygosity could contribute to smoking-induced chronic obstructive pulmonary diseases and consider the consequences.

Alpha1-antitrypsin deficiency: a clinical-genetic overview

Severe α1-antitrypsin deficiency (AATD) is an inherited disorder, leading to development of emphysema in smokers at a relatively young age with disability in their forties or fifties. The emphysema results from excessive elastin degradation by neutrophil elastase as a result of the severe deficiency of its major inhibitor α1-antitrypsin (AAT). The AAT expression is determined by the SERPINA1 gene which expresses codominant alleles. The three most common alleles are the normal M, the S with plasma levels of 60% of normal, and the severely deficient Z with levels of about 15% of normal. Homozygosity for the Z mutant allele is associated with retention of abnormal AAT in the liver, which may lead to neonatal hepatitis, liver disease in children, and liver disease in adults. Regular intravenous infusions of purified human AAT (AAT augmentation therapy) have been used to partially correct the biochemical defect and protect the lung against further injury. Two randomized controlled trials showed a trend of slower progression of emphysema by chest computerized tomography. Integrated analysis of these two studies indicated significantly slower progression of emphysema. AAT is quantified by immunologic measurement of AAT in serum, the phenotype characterized by isoelectric focusing, the common genotypes by targeted DNA analysis, and by sequencing the coding region of the gene when the AAT abnormality remains undefined. AATD is often unrecognized, and diagnosis delayed. Testing for AATD is recommended in patients with chronic irreversible airflow obstruction, especially in those with early onset of disease or positive family history. Testing is also recommended for immediate family members of those with AATD, asthmatics with persistent airflow obstruction, and infants and older subjects with unexplained liver disease. There are over 100 different AAT gene variants; most are rare and only some are associated with clinical disease.

A systematic review of the role of vitamin insufficiencies and supplementation in COPD

BACKGROUND

Pulmonary inflammation, oxidants-antioxidants imbalance, as well as innate and adaptive immunity have been proposed as playing a key role in the development of COPD. The role of vitamins, as assessed either by food frequency questionnaires or measured in serum levels, have been reported to improve pulmonary function, reduce exacerbations and improve symptoms. Vitamin supplements have therefore been proposed to be a potentially useful additive to COPD therapy.

METHODS

A systematic literature review was performed on the association of vitamins and COPD. The role of vitamin supplements in COPD was then evaluated.

CONCLUSIONS

The results of this review showed that various vitamins (vitamin C, D, E, A, beta and alpha carotene) are associated with improvement in features of COPD such as symptoms, exacerbations and pulmonary function. High vitamin intake would probably reduce the annual decline of FEV1. There were no studies that showed benefit from vitamin supplementation in improved symptoms, decreased hospitalization or pulmonary function.

Diagnostic delay and clinical modifiers in alpha-1 antitrypsin deficiency

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is one of the most prevalent inherited diseases in Whites, but identification of affected patients and establishment of the diagnosis is still unsatisfactory. This study assessed the latencies and numbers of physicians involved in identifying AATD patients, and the importance of smoking, vaccination status, and specific augmentation therapy on the course of the disease.

METHOD

Patients from Germany and Austria underwent a single written interview with 28 items. Five hundred and ninety-six patients were addressed and 44.9% replied.

RESULTS

The age at symptom onset was 39.1±10.1 years, and the diagnosis was established at the age of 45.1±10.9 years. From the 6-year delay in establishing the diagnosis, 1.4±1.7 (range 0.5-10.5) years were due to patients' reluctance to seek medical attention. There were 3.2±2.4 (range 1-13) physicians involved in establishing the diagnosis. Smoking was associated with an earlier onset of respiratory symptoms and lower exercise capacity. Vaccination against pneumococci and/or influenza, and augmentation therapy resulted in significantly fewer exacerbations and fewer emergency room visits. Airway infections and passive smoking during childhood were not found to influence the onset of respiratory symptoms.

CONCLUSIONS

In conclusion, there is still a large delay between symptom onset and AATD diagnosis. Smoking history, vaccination status, and augmentation therapy have an important impact on the course of the disease.