Alpha-1 Antitrypsin Deficiency and Tobacco Smoking: Exploring Risk Factors and Smoking Cessation in a Registry Population

Sex-Differences in Alpha-1 Antitrypsin Deficiency: Data From the EARCO Registry

BACKGROUND

Sex and gender influence many aspects of chronic obstructive pulmonary disease (COPD). Limited data are available on this topic in alpha-1 antitrypsin deficiency (AATD). We therefore aimed to investigate sex issues in the EARCO registry, a prospective, international, observational cohort study.

METHODS

Baseline data from PiZZ individuals, enrolled in the registry with complete data on sex and smoking history were analysed by group comparisons and binary logistic regression analyses.

RESULTS

1283 patients with AATD, 49.3% women were analysed. Females reported less tobacco consumption (16.8±12.2 vs. 19.6±14.5 PY, p=0.006), occupational exposures towards gases, dusts or asbestos (p<0.005 each) and consumed less alcohol (5.5±7.6 vs. 8.4±10.3u/week, p<0.001). Females reported COPD (41% vs. 57%, p<0.001) and liver disease (11% vs. 20%, p<0.001) less often. However, they had a higher prevalence of bronchiectasis (24% vs. 13%, p<0.001). Despite better lung function (FEV1%pred. 73.6±29.9 vs. 62.7±29.5, p<0.001) females reported a similar symptom burden (CAT 13.4±9.5 vs. 12.5±8.9, p=ns) and exacerbation frequency (at least one in the previous year 30% vs. 26%, p=ns) compared to males. In multivariate analyses, female sex was an independent risk factor for exacerbations in the previous year OR 1.6 p=0.001 in addition to smoking history, COPD, asthma and bronchiectasis and was also identified as risk factors for symptom burden (CAT≥10) OR 1.4 p=0.014 besides age, BMI, COPD and smoking history.

CONCLUSION

Men had higher rates of COPD and liver disease, women were more likely to have bronchiectasis. Women's higher symptom burden and exacerbation frequency suggest they may need tailored treatment approaches.

Cardiovascular disease in Alpha 1 antitrypsin deficiency: an observational study assessing the role of neutrophil proteinase activity and the suitability of validated screening tools

BACKGROUND

Alpha 1 Antitrypsin Deficiency (AATD) is a rare, inherited lung disease which shares features with Chronic Obstructive Pulmonary Disease (COPD) but has a greater burden of proteinase related tissue damage. These proteinases are associated with cardiovascular disease (CVD) in the general population. It is unclear whether patients with AATD have a greater risk of CVD compared to usual COPD, how best to screen for this, and whether neutrophil proteinases are implicated in AATD-associated CVD. This study had three aims. To compare CVD risk in never-augmented AATD patients to non-AATD COPD and healthy controls (HC). To assess relationships between CVD risk and lung physiology. To determine if neutrophil proteinase activity was associated with CVD risk in AATD. Cardiovascular risk was assessed by QRISK2® score and aortic stiffness measurements using carotid-femoral (aortic) pulse wave velocity (aPWV). Medical history, computed tomography scans and post-bronchodilator lung function parameters were reviewed. Systemic proteinase 3 activity was measured. Patients were followed for 4 years, to assess CVD development.

RESULTS

228 patients with AATD, 50 with non-AATD COPD and 51 healthy controls were recruited. In all COPD and HC participants, QRISK2® and aPWV gave concordant results (with both measures either high or in the normal range). This was not the case in AATD. Once aPWV was adjusted for age and smoking history, aPWV was highest and QRISK2® lowest in AATD patients compared to the COPD or HC participants. Higher aPWV was associated with impairments in lung physiology, the presence of emphysema on CT scan and proteinase 3 activity following adjustment for age, smoking status and traditional CVD risk factors (using QRISK2® scores) in AATD. There were no such relationships with QRISK2® in AATD. AATD patients with confirmed CVD at four-year follow up had a higher aPWV but not QRISK2® at baseline assessment.

CONCLUSION

aPWV measured CVD risk is elevated in AATD. This risk is not captured by QRISK2®. There is a relationship between aPWV, lung disease and proteinase-3 activity. Proteinase-driven breakdown of elastin fibres in large arteries and lungs is a putative mechanism and forms a potential therapeutic target for CVD in AATD.

Measuring of Alpha-1 Antitrypsin Concentration by Nephelometry or Turbidimetry

Most clinical laboratories quantify alpha-1 antitrypsin using either nephelometry or turbidimetry techniques because they are commercially available, amenable to automation, and precise. Both methods are based on light scatter. The foundation of both techniques is based on incubation of the specimen with anti-AAT polyclonal antibody solution, a polymer matrix between endogenous AAT and the reagent antibodies forms, leading to production of light-scattering large particles. Although these two terms are sometimes used synonymously, technically speaking they are not.Nephelometry measures the amount of turbidity or cloudiness of a solution by directly quantifying the intensity of the light scattered by insoluble particles in the sample. Therefore, this technique measures the light that passes through the sample, with the detector being placed at an angle from the sample. Turbidimetry is the process of measuring the loss of intensity of the light transmitted linearly through a sample caused by the scattering effect of insoluble particles. The decrease in light transmission is measured compared to a reference, and the absorbed light is quantified.Beyond specific technical differences between both techniques, there are two major differences between the two procedures that may influence the results. First, the concentration of the sample and the resulting intensity of scattered light relative to the intensity of the light source is one major factor. Second, the size of the scattering particles is also a key differentiating factor. This chapter describes the technical requirements, the different protocols, and the clinical applicability of these two techniques in the diagnosis of alpha-1 antitrypsin deficiency.

Testing Alpha-1 Antitrypsin Deficiency in Black Populations

Alpha-1 antitrypsin (AAT) deficiency (AATD) is an under-recognized hereditary disorder and a significant cause of chronic obstructive pulmonary disease (COPD), a disease that contributes to global mortality. AAT is encoded by the SERPINA1 gene, and severe mutation variants of this gene increase the risk of developing COPD. AATD is more frequently screened for in non-Hispanic White populations. However, AATD is also observed in other ethnic groups and very few studies have documented the mutation frequency in these other ethnic populations. Here, we review the current literature on AATD and allele frequency primarily in Black populations and discuss the possible clinical outcomes of low screening rates in a population that experiences poor health outcomes and whether the low frequency of AATD is related to a lack of screening in this population or a truly low frequency of mutations causing AATD. This review also outlines the harmful SERPINA1 variants, the current epidemiology knowledge of AATD, health inequity in Black populations, AATD prevalence in Black populations, the clinical implications of low screening of AATD in this population, and the possible dangers of not diagnosing or treating AATD.

Testing Patterns and Disparities for Alpha-1 Antitrypsin Deficiency

BACKGROUND

Alpha-1 antitrypsin deficiency is an under-recognized genetic cause of chronic lung and liver disease; it remains unclear what the testing frequency and disparities are for alpha-1 antitrypsin deficiency.

METHODS

This is a retrospective cohort study of people with newly diagnosed chronic obstructive pulmonary disease and liver disease identified at the University of Florida between January 1, 2012 and December 31, 2021. We performed incidence and prevalence analysis for alpha-1 antitrypsin (AAT) testing and point-biserial correlation analysis for tobacco use and AAT testing. We evaluated characteristics with AAT testing using adjusted multivariable logistic regression.

RESULTS

Among 75,810 subjects with newly diagnosed chronic obstructive pulmonary disease and liver disease between 2012 and 2021, 4248 (5.6%) were tested for AAT deficiency. All subjects had an AAT level performed, while 1654 (39%) had phenotype testing. Annual incidence of testing increased for subjects with newly diagnosed chronic obstructive pulmonary disease or liver disease from 2.8% and 5.4%, respectively, in 2012 to 4.1% and 11.3%, respectively, in 2021. Adjusted multivariable regression analysis showed factors favoring AAT testing were White race, and concomitant chronic obstructive pulmonary disease and liver disease. Increasing age, non-White race, current tobacco use, and being a male with chronic obstructive pulmonary disease had lower odds of AAT testing.

CONCLUSION

Although slowly improving, testing for AAT deficiency continues to have a low uptake in the clinical setting despite guidelines recommending broader testing. Individuals of White race and those with concomitant chronic obstructive pulmonary disease and liver disease are more likely to be tested, while older subjects, individuals of non-White race, current tobacco use, and men with chronic obstructive pulmonary disease are less favored to be tested.

Diagnosis and augmentation therapy for alpha-1 antitrypsin deficiency: current knowledge and future potential

The underdiagnosis of alpha-1 antitrypsin (AAT) deficiency (AATD) has been recognized for many years, yet little progress has been made in treatment of the disease. In this review, we summarize the AATD disease process as well as its diagnosis and treatment by AAT augmentation therapy. AATD is a rare autosomal disease that primarily affects the lungs and liver. AATD is associated with an increased susceptibility to developing pulmonary emphysema. The specific pharmacological treatment for AATD is intravenous administration of exogenous AAT. Augmentation therapy with AAT increases serum and pulmonary epithelial AAT levels, restores anti-elastase capacity, and decreases inflammatory mediators in the lung. Augmentation therapy reduces the loss of lung density over time, thus slowing progression of the disease. The effects of augmentation therapy on outcomes, such as frequency/duration of flare-ups, quality of life, lung function decline and mortality, are assessed. Wider testing for AATD, potentially through primary care physicians, could result in earlier treatment and better outcomes for individuals with AATD-induced lung respiratory disease.

[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.

Disease progression in patients with PI*ZZ alpha-1 antitrypsin deficiency

BACKGROUND AND OBJECTIVE

Alpha-1 antitrypsin deficiency (AATD) is an uncommon but underdiagnosed cause of cirrhosis and lacks medical treatment options. It is important to recognize risk factors that contribute to disease progression and liver transplantation. We aimed to assess if age, sex, or smoking status was associated with liver or lung disease progression.

METHODS

Forty-three patients with ZZ-AATD cirrhosis were consecutively sampled from an Institutional Review Board-approved registry of 240 patients with AATD of any genotype seen as outpatients in the Cleveland Clinic between 1999 and 2019. To determine the association between risk factors and lung or liver disease progression, linear mixed-effects models with fixed effects for linear time, risk factor, and time-by-risk factor interaction, and the random intercepts for intra-patient correlation were used.

RESULTS

Based on the mixed-effects model analysis, there was a significant association between liver disease progression and smoking history, and no association with age or sex. There was no association between lung disease progression and age, sex, or smoking history. However, smoking history was significantly associated with lower forced expiratory volume values.

CONCLUSION

This study found that in a cohort of patients with PI*ZZ genotype AATD (ZZ-AATD) and cirrhosis, smoking history was associated with liver disease progression, whereas age and sex were not.

Disease burden associated with alpha-1 antitrypsin deficiency: systematic and structured literature reviews

Alpha-1 antitrypsin deficiency (AATD) is a rare genetic disorder characterised by reduced levels of circulating alpha-1 antitrypsin and an increased risk of lung and liver disease. Recent reviews of AATD have focused on diagnosis, epidemiology and clinical management; comprehensive reviews examining disease burden are lacking. Therefore, we conducted literature reviews to investigate the AATD disease burden for patients, caregivers and healthcare systems. Embase, PubMed and Cochrane libraries were searched for AATD publications from database inception to June 2021, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Most published AATD studies were small and short in duration, with variations in populations, designs, measures and outcomes, complicating cross-study comparisons. AATD was associated with significant pulmonary and hepatic morbidity. COPD, emphysema and bronchiectasis were common lung morbidities, where smoking was a key risk factor. Fibrosis and steatosis were the most common liver complications reported in patients with a PiZ allele. Health status analyses suggested a poorer quality of life for AATD patients diagnosed with COPD versus those with non-AATD-associated COPD. The burden for caregivers included loss of personal time due to caring responsibilities, stress and anxiety. AATD was also associated with high direct medical costs and healthcare resource utilisation.

Estimated Prevalence and Number of PiMZ Genotypes of Alpha-1 Antitrypsin in Seventy-Four Countries Worldwide

BACKGROUND

The α-1 antitrypsin (AAT) protease inhibitor PiMZ is a moderately deficient genotype, until recently considered of little or negligible risk. However, a growing number of studies show that MZ carriers have an increased risk of developing lung and liver diseases, if exposed to smoking or other airborne or industrial pollutants, and hepatotoxic substances.

METHODS

We used the epidemiological studies performed to determine the frequencies of PiM and PiZ worldwide, based on the following criteria: 1) samples representative of the general population; 2) AAT phenotyping or genotyping characterized by adequate methods, including isoelectric focusing and polymerase chain reaction; and 3) studies with reliable results assessed with a coefficient of variation calculated from the sample size and 95% confidence intervals, to measure the precision of the results in terms of dispersion of the data around the mean.

RESULTS

The present review reveals an impressive number of MZs of more than 35 million in 74 countries of the world with available data. Seventy-five percent of them are people of Caucasian European heritage, mostly living in Europe, America, Australia and New Zealand. Twenty percent of the remaining MZs live in Asia, with the highest concentrations in the Middle East, Eastern¸ Southern, and South-eastern regions of the Asian continent. The remaining five percent are Africans residing in Western and Eastern Africa.

CONCLUSION

Considering the high rate of smoking, the outdoor and the indoor air pollution from solid fuels used in cooking and heating, and the exposure to industrial dusts and chemicals in many of these countries, these figures are very worrying, and hence the importance of adequately assessing MZ subjects, recommending them rigorous preventive measures based on the adoption of healthy lifestyles, including avoidance of smoking and alcohol.

Alpha-1 Antitrypsin Augmentation Inhibits Proteolysis of Neutrophil Membrane Voltage-Gated Proton Channel-1 in Alpha-1 Deficient Individuals

Background and Objectives: Alpha-1 antitrypsin is a serine protease inhibitor that demonstrates an array of immunomodulatory functions. Individuals with the genetic condition of alpha-1 antitrypsin deficiency (AATD) are at increased risk of early onset emphysematous lung disease. This lung disease is partly driven by neutrophil mediated lung destruction in an environment of low AAT. As peripheral neutrophil hyper-responsiveness in AATD leads to excessive degranulation and increased migration to the airways, we examined the expression of the membrane voltage-gated proton channel-1 (HVCN1), which is integrally linked to neutrophil function. The objectives of this study were to evaluate altered HVCN1 in AATD neutrophils, serine protease-dependent degradation of HVCN1, and to investigate the ability of serum AAT to control HVCN1 expression. Materials and Methods: Circulating neutrophils were purified from AATD patients (n = 20), AATD patients receiving AAT augmentation therapy (n = 3) and healthy controls (n = 20). HVCN1 neutrophil expression was assessed by flow cytometry and Western blot analysis. Neutrophil membrane bound elastase was measured by fluorescence resonance energy transfer. Results: In this study we demonstrated that HVCN1 protein is under-expressed in AATD neutrophils (p = 0.02), suggesting a link between reduced HVCN1 expression and AAT deficiency. We have demonstrated that HVCN1 undergoes significant proteolytic degradation in activated neutrophils (p < 0.0001), primarily due to neutrophil elastase activity (p = 0.0004). In addition, the treatment of AATD individuals with AAT augmentation therapy increased neutrophil plasma membrane HVCN1 expression (p = 0.01). Conclusions: Our results demonstrate reduced levels of HVCN1 in peripheral blood neutrophils that may influence the neutrophil-dominated immune response in the AATD airways and highlights the role of antiprotease treatment and specifically AAT augmentation therapy in protecting neutrophil membrane expression of HVCN1.

Alpha-1 antitrypsin deficiency: clarifying the role of the putative protective threshold

AATD is the only readily identifiable monogenic cause of COPD. To date the only condition-specific treatment for AATD-associated COPD is weekly administration of intravenous purified pooled human AAT (IV-AAT). Uncertainties regarding which AATD genotypes should benefit from IV-AAT persist. IV-AAT is costly and involves weekly administration of a plasma product. Much of the risk stratification has been centred around the long-accepted hypothesis of a "putative protective threshold" of 11 µM (0.57 g·L^-1) in serum. This hypothesis has become central to the paradigm of AATD care, though its derivation and accuracy for defining risk of disease remain unclear.We review the literature and examine the association between the 11 µM threshold and clinical outcomes to provide context and insight into the issues surrounding this topic.We found no data which demonstrates an increased risk of COPD dependent on the 11 µM threshold. Moreover, an abundance of recent clinical data examining this threshold refutes the hypothesis. Conversely, the use of 11 µM as a treatment target in appropriate ZZ individuals is supported by clinical evidence, although more refined dosing regimens are being explored.Continued use of the 11 µM threshold as a determinant of clinical risk is questionable, perpetuates inappropriate AAT-augmentation practices, may drive increased healthcare expenditure and should not be used as an indicator for commencing treatment.Genotype represents a more proven indicator of risk, with ZZ and rare ZZ-equivalent genotypes independently associated with COPD. New and better risk assessment models are needed to provide individuals diagnosed with AATD with reliable risk estimation and optimised treatment goals.