Diagnosing α1-antitrypsin deficiency: how to improve the current algorithm

Detection of Alpha-1 Antitrypsin Levels in Chronic Obstructive Pulmonary Disease in Respiratory Clinics in Spain: Results of the EPOCONSUL 2021 Audit

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is an underdiagnosed condition despite being one of the most common inherited disorders in adults that is associated with an increased risk of developing chronic obstructive pulmonary disease (COPD). The aim was to evaluate the frequency of performing AAT levels and associated factors in COPD patients in an audit conducted in 2021-2022, as well as to compare with a previous audit conducted in 2014-2015.

METHODS

EPOCONSUL 2021 is a cross-sectional audit that evaluated the outpatient care provided to COPD patients in respiratory clinics in Spain based on available data from medical registries.

RESULTS

4225 patients with a diagnosis of COPD from 45 centers were audited in 2021. A total of 1670 (39.5%) patients underwent AAT determination. Being treated at a specialized COPD outpatient clinic (OR 1.88, p = 0.007), age ≤ 55 years old (OR 1.84, p = 0.007) and a FEV1 < 50% (OR 1.86, p < 0.001) were associated with a higher likelihood of being tested for AAT, while Charlson index ≥ 3 (OR 0.63, p < 0.001) and genotyping of AATD availability (OR 0.42, p < 0.001) showed a statistically significant negative association. The analysis of cases included in respiratory units that participated in both audits showed an increase in the proportion of cases with AAT serum level testing available (adjusted OR 2.81, p < 0.001). The percentage of individuals with serum AAT levels < 60 mg/dL (a severe AATD) was 4%.

CONCLUSIONS

Our analysis identifies significant improvements in adherence to the recommendation to test AAT levels in COPD patients, performed in 4 out of 10 patients, being more likely at younger ages and with higher COPD severity, and with a detection of severe AATD of 4% among those tested, suggesting that clinicians still perform AAT testing in COPD patients selectively. Therefore, efforts are still needed to optimize AATD screening and establish new early detection strategies to reduce morbidity and mortality in these patients.

[Results of the Implementation of a Case-Finding Program for Alpha-1 Antitrypsin Deficiency in COPD Patients]

Objectives

Currently, the identification of new cases of alpha-1 antitrypsin deficiency (AATD) continues to be one of the great challenges facing the disease. The present study aims to perform an analysis of the results of the implementation of a systematic case detection program of AATD for patients with chronic obstructive pulmonary disease.

Material and methods

Cross-sectional observational study in which the results of AAT screening until December 2022 were analyzed. The cases studied were divided into three periods: (1) no systematic case detection until 2013; (2) systematic case detection of S and Z alleles for cases with AAT < 90 mg/dL until 2018, and (3) systematic case detection of 14 mutations for cases with AAT < 120 mg/dL since 2018.

Results

A total of 471 cases were studied, of which 306 (65.0%) were carriers of some mutation related to HAD. The number of detected cases of all mutations with their percentage against those studied in each period was respectively: 6 (100%), 48 (88.8%) and 253 (61.5%). If we limit to severe mutations (AAT < 57.2 mg/dL), the distribution by periods was respectively: 3 (50.0), 10 (18.5%) and 17 (4.1%).

Conclusions

The present study describes the changes in the detection of patients carrying DAAT-related alleles with three different case identification policies. The data support the use of systematic case detection system in the COPD patient population.

Alpha-1 antitrypsin deficiency: current therapy and emerging targets

INTRODUCTION

Alpha1 antitrypsin deficiency (AATD), a common hereditary disorder affecting mainly lungs, liver and skin has been the focus of some of the most exciting therapeutic approaches in medicine in the past 5 years. In this review, we discuss the therapies presently available for the different manifestations of AATD and new therapies in the pipeline.

AREAS COVERED

We review therapeutic options for the individual lung, liver and skin manifestations of AATD along with approaches which aim to treat all three. Along with this renewed interest in treating AATD come challenges. How is AAT best delivered to the lung? What is the desired level of AAT in the circulation and lungs which therapeutics should aim to provide? Will treating the liver disease increase the potential for lung disease? Are there treatments to target the underlying genetic defect with the potential to prevent all aspects of AATDrelated disease?

EXPERT OPINION

With a relatively small population able to participate in clinical studies, increased awareness and diagnosis of AATD is urgently needed. Better, more sensitive clinical parameters will assist in the generation of acceptable and robust evidence of therapeutic effect for current and emerging treatments.

Dark-field chest x-ray imaging: first experience in patients with alpha1-antitrypsin deficiency

Background

Spirometry and conventional chest x-ray have limitations in investigating early emphysema, while computed tomography, the reference imaging method in this context, is not part of routine patient care due to its higher radiation dose. In this work, we investigated a novel low-dose imaging modality, dark-field chest x-ray, for the evaluation of emphysema in patients with alpha1-antitrypsin deficiency.

Methods

By exploiting wave properties of x-rays for contrast formation, dark-field chest x-ray visualises the structural integrity of the alveoli, represented by a high signal over the lungs in the dark-field image. We investigated four patients with alpha1-antitrypsin deficiency with a novel dark-field x-ray prototype and simultaneous conventional chest x-ray. The extent of pulmonary function impairment was assessed by pulmonary function measurement and regional emphysema distribution was compared with CT in one patient.

Results

We show that dark-field chest x-ray visualises the extent of pulmonary emphysema displaying severity and regional differences. Areas with low dark-field signal correlate with emphysematous changes detected by computed tomography using a threshold of -950 Hounsfield units. The airway parameters obtained by whole-body plethysmography and single breath diffusing capacity of the lungs for carbon monoxide demonstrated typical changes of advanced emphysema.

Conclusions

Dark-field chest x-ray directly visualised the severity and regional distribution of pulmonary emphysema compared to conventional chest x-ray in patients with alpha1-antitrypsin deficiency. Due to the ultra-low radiation dose in comparison to computed tomography, dark-field chest x-ray could be beneficial for long-term follow-up in these patients.

An Italian expert consensus on the management of alpha1-antitrypsin deficiency: a comprehensive set of algorithms

BACKGROUND

Alpha1-antitrypin deficiency (AATD) is a genetic-based risk condition, mainly affecting the lungs and liver. Despite its wide distribution, it is largely underdiagnosed, thus being considered a rare disease, and is consequently managed in ad hoc reference centers. Unfortunately, an easy-to-use algorithm for managing such a complex disease is still lacking.

METHODS

An expert consensus meeting was conducted among experts in the management of AATD to build a comprehensive algorithm, including diagnosis, monitoring, AAT therapy, rehabilitation and lung transplantation, and liver disease, that could serve as a guide for physicians and treating centers. A panel of AATD specialists evaluated the results of their work.

RESULTS

Diagnosis is the most delicate phase, and awareness about this condition should be raised among GPs. A set of recommendations has been written about the most suitable follow-up visits. Augmentation therapy with AAT may be useful to reduce the progression of emphysema and lung function decline in selected patients. Exercise capacity may be improved by pulmonary rehabilitation and, in selected cases, by lung volume reduction or lung transplantation. Support therapies are needed for those who develop liver disease, and, in selected cases, liver transplantation may be considered. Patients should be carefully educated about their lifestyle, including smoking cessation, body weight control, and reduced alcohol intake.

CONCLUSIONS

The proposed algorithm obtained the endorsement of the Italian Society of Pneumology (SIP). However, further studies and additional clinical data are required to confirm the validity of these recommendations.

Alternative poly-adenylation modulates α1-antitrypsin expression in chronic obstructive pulmonary disease

α1-anti-trypsin (A1AT), encoded by SERPINA1, is a neutrophil elastase inhibitor that controls the inflammatory response in the lung. Severe A1AT deficiency increases risk for Chronic Obstructive Pulmonary Disease (COPD), however, the role of A1AT in COPD in non-deficient individuals is not well known. We identify a 2.1-fold increase (p = 2.5x10-6) in the use of a distal poly-adenylation site in primary lung tissue RNA-seq in 82 COPD cases when compared to 64 controls and replicate this in an independent study of 376 COPD and 267 controls. This alternative polyadenylation event involves two sites, a proximal and distal site, 61 and 1683 nucleotides downstream of the A1AT stop codon. To characterize this event, we measured the distal ratio in human primary tissue short read RNA-seq data and corroborated our results with long read RNA-seq data. Integrating these results with 3' end RNA-seq and nanoluciferase reporter assay experiments we show that use of the distal site yields mRNA transcripts with over 50-fold decreased translation efficiency and A1AT expression. We identified seven RNA binding proteins using enhanced CrossLinking and ImmunoPrecipitation precipitation (eCLIP) with one or more binding sites in the SERPINA1 3' UTR. We combined these data with measurements of the distal ratio in shRNA knockdown experiments, nuclear and cytoplasmic fractionation, and chemical RNA structure probing. We identify Quaking Homolog (QKI) as a modulator of SERPINA1 mRNA translation and confirm the role of QKI in SERPINA1 translation with luciferase reporter assays. Analysis of single-cell RNA-seq showed differences in the distribution of the SERPINA1 distal ratio among hepatocytes, macrophages, αβ-Tcells and plasma cells in the liver. Alveolar Type 1,2, dendritic cells and macrophages also vary in their distal ratio in the lung. Our work reveals a complex post-transcriptional mechanism that regulates alternative polyadenylation and A1AT expression in COPD.

Living with the enemy: from protein-misfolding pathologies we know, to those we want to know

Conformational diseases are caused by the aggregation of misfolded proteins. The risk for such pathologies develops years before clinical symptoms appear, and is higher in people with alpha-1 antitrypsin (AAT) polymorphisms. Thousands of people with alpha-1 antitrypsin deficiency (AATD) are underdiagnosed. Enemy-aggregating proteins may reside in these underdiagnosed AATD patients for many years before a pathology for AATD fully develops. In this perspective review, we hypothesize that the AAT protein could exert a new and previously unconsidered biological effect as an endogenous metal ion chelator that plays a significant role in essential metal ion homeostasis. In this respect, AAT polymorphism may cause an imbalance of metal ions, which could be correlated with the aggregation of amylin, tau, amyloid beta, and alpha synuclein proteins in type 2 diabetes mellitus (T2DM), Alzheimer's and Parkinson's diseases, respectively.

Comparison of different algorithms in laboratory diagnosis of alpha1-antitrypsin deficiency

OBJECTIVES

Alpha1-antitrypsin deficiency (AATD) is an inherited condition that predisposes individuals to an increased risk of developing lung and liver disease. Even though AATD is one of the most widespread inherited diseases in Caucasian populations, only a minority of affected individuals has been detected. Whereas methods have been validated for AATD testing, there is no universally-established algorithm for the detection and diagnosis of the disorder. In order to compare different methods for diagnosing AATD, we carried out a systematic review of the literature on AATD diagnostic algorithms.

METHODS

Complete biochemical and molecular analyses of 5,352 samples processed in our laboratory were retrospectively studied using each of the selected algorithms.

RESULTS

When applying the diagnostic algorithms to the same samples, the frequency of False Negatives varied from 1.94 to 12.9%, the frequency of True Negatives was 62.91% for each algorithm and the frequency of True Positives ranged from 24.19 to 35.15%. We, therefore, highlighted some differences among Negative Predictive Values, ranging from 0.83 to 0.97. Accordingly, the sensitivity of each algorithm ranged between 0.61 and 0.95. We also postulated 1.108 g/L as optimal AAT cut-off value, in absence of inflammatory status, which points to the possible presence of genetic AATD.

CONCLUSIONS

The choice of the diagnostic algorithm has a significant impact on the correct diagnosis of AATD, which is essential for appropriate treatment and medical care. The fairly large number of possible false negative diagnoses revealed by the present paper should also warn clinicians of negative results in patients with clinically-suspected AATD.

Alpha-1 antitrypsin governs alcohol-related liver disease in mice and humans

OBJECTIVE

Alcohol-related liver disease (ALD) is a global healthcare problem with limited treatment options. Alpha-1 antitrypsin (AAT, encoded by SERPINA1) shows potent anti-inflammatory activities in many preclinical and clinical trials. In our study, we aimed to explore the role of AAT in ALD.

DESIGN

An unselected cohort of 512 patients with cirrhosis was clinically characterised. Survival, clinical and biochemical parameters including AAT serum concentration were compared between patients with ALD and other aetiologies of liver disease. The role of AAT was evaluated in experimental ALD models.

RESULTS

Cirrhotic ALD patients with AAT serum concentrations less than 120 mg/dL had a significantly higher risk for death/liver transplantation as compared with patients with AAT serum concentrations higher than 120 mg/dL. Multivariate Cox regression analysis showed that low AAT serum concentration was a NaMELD-independent predictor of survival/transplantation. Ethanol-fed wild-type (wt) mice displayed a significant decline in hepatic AAT compared with pair-fed mice. Therefore, hAAT-Tg mice were ethanol-fed, and these mice displayed protection from liver injury associated with decreased steatosis, hepatic neutrophil infiltration and abated expression of proinflammatory cytokines. To test the therapeutic capability of AAT, ethanol-fed wt mice were treated with human AAT. Administration of AAT ameliorated hepatic injury, neutrophil infiltration and steatosis.

CONCLUSION

Cirrhotic ALD patients with AAT concentrations less than 120 mg/dL displayed an increased risk for death/liver transplantation. Both hAAT-Tg mice and AAT-treated wt animals showed protection from ethanol-induced liver injury. AAT could reflect a treatment option for human ALD, especially for alcoholic hepatitis.

Trends in Diagnosis of Alpha-1 Antitrypsin Deficiency Between 2015 and 2019 in a Reference Laboratory

Background

Alpha-1 antitrypsin deficiency (AATD) remains largely underdiagnosed despite recommendations of healthcare institutions and programmes designed to increase awareness. The objective was to analyse the trends in AATD diagnosis during the last 5 years in a Spanish AATD reference laboratory.

Methods

This was a retrospective revision of all alpha-1 antitrypsin (AAT) determinations undertaken in our laboratory from 2015 to 2019. We analysed the number of AAT determinations performed and described the characteristics of the individuals tested, as well as the medical specialties and the reasons for requesting AAT determination.

Results

A total of 3507 determinations were performed, of which 5.5% corresponded to children. A significant increase in the number of AAT determinations was observed from 349 in 2015 to 872 in 2019. Among the samples, 57.6% carried an intermediate AATD (50-119 mg/dL) and 2.4% severe deficiency (<50 mg/dL). The most frequent phenotype in severe AATD individuals was PI*ZZ (78.5%), and aminotransferase levels were above normal in around 43% of children and 30% of adults. Respiratory specialists requested the highest number of AAT determinations (31.5%) followed by digestive diseases and internal medicine (27.5%) and primary care physicians (19.7%). The main reason for AAT determination in severe AATD adults was chronic obstructive pulmonary disease (41.7%), but reasons for requesting AAT determination were not reported in up to 41.7% of adults and 58.3% of children.

Conclusion

There is an increase in the frequency of AATD testing despite the rate of AAT determination remaining low. Awareness about AAT is probably increasing, but the reason for testing is not always clear.

Alpha-1 Antitrypsin Deficiency: a Rare Disease?

PURPOSE OF REVIEW

Commonly categorized as a rare disease, alpha-1 antitrypsin deficiency (AATD) is neither rare, when compared to many other genetic disorders, nor an actual disease, but rather a predisposition toward a wide variety of diseases. It is one of the most common genetic disorders which can lead to a spectrum of clinical manifestations, ranging from no symptoms to progressively debilitating systemic disease, most commonly affecting the lung and liver. It is therefore imperative for clinicians to recognize and be familiar with the spectrum of presentations, methods of diagnosis, and clinical management of AATD. It is also imperative for scientists to recognize the potential for progress in the management of this disorder.

RECENT FINDINGS

This review focuses on the current state of knowledge of AATD, including the wide range of presentations, diagnosis, and clinical management. In addition to the clinical implications of severe AATD, we discuss the relevance of heterozygous state with mild or moderate AATD in the development of both lung and liver disease. While our understanding of the multiple roles of alpha-1 antitrypsin (AAT) is on the rise, with appreciation of its immunomodulatory, anti-infective, and anti-inflammatory properties, this knowledge has yet to impact our ability to predict outcomes. We discuss nuances of augmentation therapy and review novel therapeutic approaches currently under investigation. With the expanding knowledge about the complexities of AAT function and its clinical relevance, and with the increasing ability to diagnose early and intervene on AATD, it should be our goal to change the perception of AATD as a correctable inherited disorder rather than a fatal disease.

Diagnosis and treatment of lung disease associated with alpha one-antitrypsin deficiency: A position statement from the Thoracic Society of Australia and New Zealand

AATD is a common inherited disorder associated with an increased risk of developing pulmonary emphysema and liver disease. Many people with AATD-associated pulmonary emphysema remain undiagnosed and therefore without access to care and counselling specific to the disease. AAT augmentation therapy is available and consists of i.v. infusions of exogenous AAT protein harvested from pooled blood products. Its clinical efficacy has been the subject of some debate and the use of AAT augmentation therapy was recently permitted by regulators in Australia and New Zealand, although treatment is not presently subsidized by the government in either country. The purpose of this position statement is to review the evidence for diagnosis and treatment of AATD-related lung disease with reference to the Australian and New Zealand population. The clinical efficacy and adverse events of AAT augmentation therapy were evaluated by a systematic review, and the GRADE process was employed to move from evidence to recommendation. Other sections address the wide range of issues to be considered in the care of the individual with AATD-related lung disease: when and how to test for AATD, changing diagnostic techniques, monitoring of progression, disease in heterozygous AATD and pharmacological and non-pharmacological therapy including surgical options for severe disease. Consideration is also given to broader issues in AATD that respiratory healthcare staff may encounter: genetic counselling, patient support groups, monitoring for liver disease and the need to establish national registries for people with AATD in Australia and New Zealand.

Anti-cytokines as a Strategy in Alpha-1 Antitrypsin Deficiency

For many years, the lung disease associated with alpha-1 antitrypsin (AAT) deficiency (AATD) was perceived as being secondary to an imbalance between this serine protease inhibitor and the target protease, neutrophil elastase (NE). More recently, a greater understanding of the pathways leading to lung inflammation has shed light on new potential attributes and presented AATD as an inflammatory condition in which proteases and neutrophils still play a major role, but in which pro-inflammatory cytokines, either induced by the actions of NE or by other pro-inflammatory processes normally modulated by AAT, are involved. In this review, we will look at the various cytokines centrally involved in AATD lung disease, and how a greater understanding of their contribution may help development of targeted therapies.

Diagnosing Alpha-1-Antitrypsin Deficiency Using A PCR/Luminescence-Based Technology

Purpose

Alpha-1-antitrypsin deficiency (AATD) is a rare hereditary condition resulting from the mutations in the SERPINA1 (serine protease inhibitor) gene and is characterized by low circulating levels of the alpha-1 antitrypsin (AAT) protein. The traditional algorithm for laboratory testing of AATD involves the analysis of AAT concentrations (nephelometry), phenotyping (isoelectric focusing, IEF), and genotyping (polymerase chain reaction, PCR); in selected cases, full sequencing of the SERPINA1 gene can be undertaken. New technologies arise that may make diagnosis easier and faster.

Methods

We developed and evaluated a new diagnostic algorithm based on Luminex xMAP (multi-analyte profiling) technology using Progenika A1AT Genotyping Test. In an initial learning phase, 1979 samples from individuals suspected of having AATD were examined by both, a traditional and a "new" algorithm. In a second phase, 1133 samples were analyzed with the Luminex xMAP only.

Results

By introducing a Luminex xMAP based algorithm, we were able to simultaneously identify 14 mutations in SERPINA1 gene (instead of two- S and Z-by using our old algorithm). Although the quantity of IEF assays remained unchanged, the nephelometric measurements and sequencing were reduced by 79% and 63.4%, respectively.

Conclusion

The new method is convenient, fast and user-friendly. The application of the Luminex xMAP technology can simplify and shorten the diagnostic workup of patients with suspected AATD.

Portuguese consensus document for the management of alpha-1-antitrypsin deficiency

Alpha-1-antitrypsin deficiency (AATD) is a genetic autosomal codominant disorder caused by mutations in SERPINA1 gene. It is one of the most prevalent genetic disorders, although it remains underdiagnosed. Whereas at international level there are several areas of consensus on this disorder, in Portugal, inter-hospital heterogeneity in clinical practice and resources available have been adding difficulties in reaching a diagnosis and in making therapeutic decisions in this group of patients. This raised a need to draft a document expressing a national consensus for AATD. To this end, a group of experts in this field was created within the Portuguese Pulmonology Society - Study group on AATD, in order to elaborate the current manuscript. The authors reviewed the existing literature and provide here general guidance and extensive recommendations for the diagnosis and management of AATD that can be adopted by Portuguese clinicians from different areas of Medicine. This article is part of a supplement entitled "Portuguese consensus document for the management of alpha-1-antitrypsin deficiency" which is sponsored by Sociedade Portuguesa de Pneumologia.

Alpha 1-antitrypsin deficiency in patients with chronic obstructive pulmonary disease patients: is systematic screening necessary?

OBJECTIVE

Alpha-1-antitrypsin deficiency is a relatively prevalent, but under-diagnosed, genetic disease. The objective of this study was to assess whether the systematic screening for alpha-1-antitrypsin deficiency in all patients with chronic obstructive pulmonary disease from a tertiary service has an impact on the number of patients being diagnosed with this condition.

RESULTS

Chronic obstructive pulmonary disease patients were screened for alpha-1-antitrypsin deficiency using immunonephelometry. The presence of a mutation was confirmed by molecular study of the SERPINA1 gene or by genetic sequencing, as needed. A total of 551 patients with chronic obstructive pulmonary disease were analyzed. Among these, 40 (7.2%) had some genetic mutation, while 11 (2%) had a Pi*ZZ genotype, resulting in severe respiratory illness. The systematic evaluation of chronic obstructive pulmonary disease patients revealed that screening is an effective method to diagnose alpha-1-antitrypsin deficiency. Early diagnosis may facilitate smoking cessation and initiation of treatment to maintain lung function.

Advances in managing COPD related to α1 -antitrypsin deficiency: An under-recognized genetic disorder

α1 -Antitrypsin deficiency (AATD) predisposes individuals to chronic obstructive pulmonary disease (COPD) and liver disease. Despite being commonly described as rare, AATD is under-recognized, with less than 10% of cases identified. The following is a comprehensive review of AATD, primarily for physicians who treat COPD or asthma, covering the genetics, epidemiology, clinical presentation, screening and diagnosis, and treatments of AATD. For patients presenting with liver and/or lung disease, screening and diagnostic tests are the only methods to determine whether the disease is related to AATD. Screening guidelines have been established by organizations such as the World Health Organization, European Respiratory Society, and American Thoracic Society. High-risk groups, including individuals with COPD, nonresponsive asthma, bronchiectasis of unknown etiology, or unexplained liver disease, should be tested for AATD. Current treatment options include augmentation therapy with purified AAT for patients with deficient AAT levels and significant lung disease. Recent trial data suggest that lung tissue is preserved by augmentation therapy, and different dosing schedules are currently being investigated. Effective management of AATD and related diseases also includes aggressive avoidance of smoking and biomass burning, vaccinations, antibiotics, exercise, good diet, COPD medications, and serial assessment.

Alpha-1 Antitrypsin Substitution for Extrapulmonary Conditions in Alpha-1 Antitrypsin Deficient Patients

Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder which most commonly manifests as pulmonary emphysema. Accordingly, alpha-1 antitrypsin (AAT) augmentation therapy aims to reduce the progression of emphysema, as achieved by life-long weekly slow-drip infusions of plasma-derived affinity-purified human AAT. However, not all AATD patients will receive this therapy, due to either lack of medical coverage or low patient compliance. To circumvent these limitations, attempts are being made to develop lung-directed therapies, including inhaled AAT and locally-delivered AAT gene therapy. Lung transplantation is also an ultimate therapy option. Although less common, AATD patients also present with disease manifestations that extend beyond the lung, including vasculitis, diabetes and panniculitis, and appear to experience longer and more frequent hospitalization times and more frequent pneumonia bouts. In the past decade, new mechanism-based clinical indications for AAT therapy have surfaced, depicting a safe, anti-inflammatory, immunomodulatory and tissue-protective agent. Introduced to non-AATD individuals, AAT appears to provide relief from steroid-refractory graft-versus-host disease, from bacterial infections in cystic fibrosis and from autoimmune diabetes; preclinical studies show benefit also in multiple sclerosis, ulcerative colitis, rheumatoid arthritis, acute myocardial infarction and stroke, as well as ischemia-reperfusion injury and aberrant wound healing processes. While the current augmentation therapy is targeted towards treatment of emphysema, it is suggested that AATD patients may benefit from AAT augmentation therapy geared towards extrapulmonary pathologies as well. Thus, development of mechanism-based, context-specific AAT augmentation therapy protocols is encouraged. In the current review, we will discuss extrapulmonary manifestations of AATD and the potential of AAT augmentation therapy for these conditions.

Alpha-1 antitrypsin deficiency: outstanding questions and future directions

Background

Alpha-1 antitrypsin deficiency (AATD) is a rare hereditary condition that leads to decreased circulating alpha-1 antitrypsin (AAT) levels, significantly increasing the risk of serious lung and/or liver disease in children and adults, in which some aspects remain unresolved.

Methods

In this review, we summarise and update current knowledge on alpha-1 antitrypsin deficiency in order to identify and discuss areas of controversy and formulate questions that need further research.

Results

1) AATD is a highly underdiagnosed condition. Over 120,000 European individuals are estimated to have severe AATD and more than 90% of them are underdiagnosed.

Conclusions

2) Several clinical and etiological aspects of the disease are yet to be resolved. New strategies for early detection and biomarkers for patient outcome prediction are needed to reduce morbidity and mortality in these patients; 3) Augmentation therapy is the only specific approved therapy that has shown clinical efficacy in delaying the progression of emphysema. Regrettably, some countries reject registration and reimbursement for this treatment because of the lack of larger randomised, placebo-controlled trials. 4) Alternative strategies are currently being investigated, including the use of gene therapy or induced pluripotent stem cells, and non-augmentation strategies to prevent AAT polymerisation inside hepatocytes.

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.

COPD in individuals with the PiMZ alpha-1 antitrypsin genotype

Since the discovery of severe alpha-1 antitrypsin deficiency as a genetic risk factor for emphysema, there has been ongoing debate over whether individuals with intermediate deficiency with one protease inhibitor Z allele (PiMZ, or MZ) are at some risk for emphysema. This is important, because MZ individuals comprise 2-5% of the general population. In this review we summarise the evidence about the risks of the MZ population to develop emphysema or asthma. We discuss the different study designs that have tried to answer this question. The risk of emphysema is more pronounced in case-control than in population-based studies, perhaps due to inadequate power. Carefully designed family studies show an increased risk of emphysema in MZ smokers. This is supported by the rapid decline in lung function of MZ individuals when compared to the general population after massive environmental exposures. The risk of asthma in MZ subjects is less studied, and more literature is needed before firm conclusions can be made. Augmentation therapy in MZ individuals is not supported by any objective studies. MZ smokers are at increased risk for emphysema that is more pronounced when other environmental challenges are present.

Brief Report: Genetic Variation of the α1 -Antitrypsin Gene Is Associated With Increased Autoantibody Production in Rheumatoid Arthritis

OBJECTIVE

To examine the prevalence of α₁ -antitrypsin deficiency (AATD) in rheumatoid arthritis (RA), and to determine whether AATD is associated with higher levels of rheumatoid factor (RF), antinuclear antibodies (ANAs), and anti-citrullinated peptide autoantibodies (ACPAs).

METHODS

RF, ANAs, and ACPAs were measured by standard immunoturbidimetry, immunofluorescence assay, and enzyme-linked immunosorbent assay, respectively. Characterization of AAT phenotypes was performed by isoelectric focusing and immunofixation. The chi-square test with Yates' correction and the Mann-Whitney U test were used to assess the prevalence of alleles associated with AATD in RA and to compare mean antibody titers, respectively.

RESULTS

Of 246 patients with RA, 24 who were heterozygous for AATD were identified, with no statistically significant difference in the prevalence of AATD between RA patients and the general population (P = 0.39). A positive association between heterozygosity for AATD and the production of ACPAs was observed (P < 0.0001), with increased ACPA titers recorded in the AATD RA cohort compared with the general population (P = 0.01).

CONCLUSION

AAT heterozygous status in RA is strongly associated with positive ACPAs and may define a distinct subset of patients with increased disease severity.

The Allergist's Role in Detection of Severe Alpha-1 Antitrypsin Deficiency

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) frequently presents as difficult to manage asthma or asthma with fixed obstruction and is well documented as being underdiagnosed in the population.

OBJECTIVE

This study aimed to better describe allergists'/immunologists' involvement in the care of patients with AATD and whether they currently contribute to the underdiagnosis by lack of screening for the condition.

METHODS

Using the Research Electronic Data Capture tool, we submitted a questionnaire to 500 patients with severe AATD (ZZ, SZ, ZNull, and FZ) through the Alpha-1 Foundation Research Registry to collect information about patient diagnosis and treatment patterns. Approximately 45% completed the questionnaire, leading to a final enrollment of 226 participants.

RESULTS

Seventy-eight participants (34%) had seen an allergist, but only 11 (5%) were diagnosed with AATD by their allergist. Likewise, allergists prescribed alpha-1 augmentation therapy to only 5 (8%) of the 59 patients on augmentation therapy. Nearly 46% (n = 104) of all participants were diagnosed with either asthma (28%) or allergic disease (18%) before receiving a diagnosis of AATD. Eighteen patients had been treated with immunotherapy before their diagnosis of AATD, with 94% of these participants receiving treatment for 3 years or longer.

CONCLUSIONS

Our data suggest that specialists in Allergy and Immunology should consider and screen for AATD in patients with asthma in whom spirometry does not return to normal. Furthermore, we propose allergists/immunologists are well suited to screen and treat patients with AATD.

Genotyping diagnosis of alpha-1 antitrypsin deficiency in Saudi adults with liver cirrhosis

The acute phase protein alpha-1 antitrypsin (AAT) is mainly produced in liver cells. AAT deficiency affects the lungs and liver. We conducted a case-control study to define a valuable method for the proper diagnosis of alpha-1 antitrypsin deficiency (AATD), as well as the association of liver cirrhosis with AATD in Saudi adults.Blood samples from 300 liver cirrhosis patients and 400 controls were analyzed according to serum AAT concentration, phenotyping, and genotyping. Nephelometry was used for AAT quantification, isoelectric focusing electrophoresis was used for phenotyping detection, and real-time PCR was used for genotyping to determine the Z and S deficiency alleles.This study highlights the accuracy of using genotyping in addition to AAT quantification, since this technique has proven to be successful in the diagnosis of AATD for 100% of our cases. A significant deviation in AAT genotypes frequencies from the Hardy-Weinberg equilibrium in the adult cirrhosis group occurred due to a higher observed frequency than expected for the Pi ZZ homozygous genotype.Pi ZZ in adults may be considered as the risk factor for liver cirrhosis. However, we could not establish this relationship for heterozygous AATD genotypes (such as Pi MZ and Pi SZ).

Panniculitis: A summary

The diagnosis of panniculitis is felt to be a confusing topic by some pathologists. This summarical article presents inflammatory diseases of the subcutis in a systematic fashion, based on whether they are centered on fibrovascular septa or the adipose lobules, and whether morphologic vasculitis is present or not. Septocentric, non-vasculitis disorders include erythema nodosum, panniculitis that follows the use of "biological" therapeutic agents, lipodermatosclerosis, post-irradiation panniculitis, morphea profunda, and necrobiosis lipodica profunda. Polyarteritis nodosa and Behçet's disease are the conditions that are based in the subcutaneous septa with vasculitis. Predominantly-lobular panniculitides with no vasculitis include pancreatogenic panniculitis, the panniculitis of alpha-1-antitrypsin deficiency, panniculitis associated with lupus erythematosus and dermatomyositis, subcutaneous Sweet syndrome, eosinophilic panniculitis, factitial panniculitis, cold panniculitis, panniculitis following injections of corticosteroids, lipomembranous (ischemic) panniculitis; sclerema neonatorum and subcutaneous fat necrosis of the newborn, and Rosai-Dorfman disease of the subcutis. Erythema induratum and infectious panniculitis are vasculitic and lobulocentric conditions. This article reviews the histological features of these diseases.

Recent advances in understanding and treating COPD related to α1-antitrypsin deficiency

INTRODUCTION

Alpha-1-antitrypsin deficiency (AATD) is an orphan disease that predisposes individuals to COPD and liver disease. The following is a comprehensive review of AATD from epidemiology to treatment for physicians who treat COPD or asthma. Areas covered: In this comprehensive review of alpha-1-antitrypsin deficiency, we describe the historical perspective, genetics, epidemiology, clinical presentation and symptoms, screening and diagnosis, and treatments of the condition. Expert commentary: The two most important directions for advancing the understanding of AATD involve improving detection of the condition, especially in asymptomatic patients, and advancing knowledge of treatments directed specifically at AATD-related conditions. With regard to treatment for AATD-related conditions, research must continue to explore the implications and importance of augmentation therapy as well as consider new implementations that may prove more successful taking into consideration not only factors of pulmonary function and liver health, but also product availability and financial viability.

Quantitative analysis of protease recognition by inhibitors in plasma using microscale thermophoresis

High abundance proteins like protease inhibitors of plasma display a multitude of interactions in natural environments. Quantitative analysis of such interactions in vivo is essential to study diseases, but have not been forthcoming, as most methods cannot be directly applied in a complex biological environment. Here, we report a quantitative microscale thermophoresis assay capable of deciphering functional deviations from in vitro inhibition data by combining concentration and affinity measurements. We obtained stable measurement signals for the substrate-like interaction of the disease relevant inhibitor α-1-antitrypsin (AAT) Z-variant with catalytically inactive elastase. The signal differentiates between healthy and sick AAT-deficient individuals suggesting that affinity between AAT and elastase is strongly modulated by so-far overlooked additional binding partners from the plasma.

A Library of Rare α1-Antitrypsin (AAT) Variant Phenotypes to Aid in the Diagnosis of AAT Deficiency

OBJECTIVES

α1-Antitrypsin (AAT) deficiency is a hereditary disorder due to defective production of the serine protease inhibitor, AAT, which can cause lung and liver diseases. Severity of disease depends particularly on the phenotypic representation of AAT variants in the patient.

METHODS

In this study, we present determination of seven common and nine rare variant phenotypes of AAT using pediatric samples collected in Texas Children's Hospital to address the knowledge gap in the identification of rare variants. We tested 16 different AAT variants that had been stored in a -80 °C freezer over the years to add to the reference library of AAT variants. The gold-standard isoelectric focusing electrophoresis method was used for analysis and interpretation of AAT variants. Each variant was inspected visually by comparing multiple bands, unique to phenotypic identity, with a previously identified pattern.

RESULTS

Seven common M, S, and Z variants were identified as M1M1, M2M2, M1M2, MS, SS, SZ, and ZZ. Nine rare variants were identified as FM, FS, FZ, PM, XM, YM, IM, TS, and EP. These were interpreted independently and in a blinded manner by an experienced technologist and two clinical chemists from two different institutions.

CONCLUSIONS

Our results add to the reference library to identify the rare variant phenotypes of AAT protein. This report will guide clinical laboratories for proper assessment of rare variants and in turn contribute to accurate diagnosis and management of AAT deficiency.

α1-Antitrypsin deficiency

α1-Antitrypsin deficiency (A1ATD) is an inherited disorder caused by mutations in SERPINA1, leading to liver and lung disease. It is not a rare disorder but frequently goes underdiagnosed or misdiagnosed as asthma, chronic obstructive pulmonary disease (COPD) or cryptogenic liver disease. The most frequent disease-associated mutations include the S allele and the Z allele of SERPINA1, which lead to the accumulation of misfolded α1-antitrypsin in hepatocytes, endoplasmic reticulum stress, low circulating levels of α1-antitrypsin and liver disease. Currently, there is no cure for severe liver disease and the only management option is liver transplantation when liver failure is life-threatening. A1ATD-associated lung disease predominately occurs in adults and is caused principally by inadequate protease inhibition. Treatment of A1ATD-associated lung disease includes standard therapies that are also used for the treatment of COPD, in addition to the use of augmentation therapy (that is, infusions of human plasma-derived, purified α1-antitrypsin). New therapies that target the misfolded α1-antitrypsin or attempt to correct the underlying genetic mutation are currently under development.