Surgery for patients with Alpha 1 Antitrypsin Deficiency: A review

Expert Perspectives on the Management of Alpha 1-Antitrypsin Deficiency

Alpha 1-antitrypsin deficiency is an inherited autosomal codominant disorder, which predisposes patients to lung and/or liver disease. Even though it is considered rare, it is one of the most frequent genetic disorders worldwide, albeit remaining underdiagnosed. Several organizations and societies, including the Portuguese Society of Pulmonology have been elaborating guidelines and recommendations for the diagnosis and management of alpha 1-antitrypsin deficiency. Nevertheless, some important matters are yet to be included in those, mainly due to lack of robust scientific evidence, and continue to represent a point of discussion. This article reviews some important scientific publications and expresses the perspectives of a group of Portuguese experts regarding the management of alpha 1-antitrypsin deficiency, namely in terms of the pre and neonatal diagnosis, the impact of the COVID-19 pandemic, the validity of replacement therapy in lung transplant-receiving, and finally, alternative strategies of alpha 1-antitrypsin deficiency treatment to improve the patients' quality of life.

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.

Lung and liver transplantation in patients with alpha-1 antitrypsin deficiency

Alpha-1 antitrypsin (AAT) augmentation is effective in slowing the progression of emphysema due to AAT deficiency (AATD) but cannot prevent eventual progression to end-stage lung disease and complete respiratory failure, which is the leading cause of death for individuals with severe AATD. When patients develop end-stage lung disease, lung transplantation is the only treatment option available, and this can improve lung physiology and patient health status. The available data suggest that survival rates for lung transplantation are significantly higher for patients with AATD-related chronic obstructive pulmonary disease (COPD) compared with non-AATD-related COPD, but, conversely, there is a higher risk of common post-lung transplant complications in patients with AATD versus non-AATD COPD. Nevertheless, lung transplantation (single and bilateral) is favorable for patients with AATD. After respiratory failure, the second leading cause of death in patients with AATD is liver disease, for example, cirrhosis and hepatocellular carcinoma, caused by the accumulation of mutant forms of AAT retained within the liver. As with lung disease, the only treatment option for end-stage liver disease is liver transplantation. Survival rates for patients with AATD undergoing liver transplantation are also favorable, and patients, particularly pediatric patients, have benefitted from advancements in peri-/post-surgical care. As the majority of AAT is produced by the liver, the AAT phenotype of the recipient becomes that of the donor, meaning that AAT serum levels should be normalized (if the donor is AAT-replete), halting further lung and liver disease progression. However, post-liver transplant respiratory function may continue to decline in line with normal age-related lung function decline. In the most severe cases, where patients have simultaneous end-stage lung and liver disease, combined lung and liver transplantation is a treatment option with favorable outcomes. However, there is very little information available on this procedure in patients with AATD.

Imaging in alpha-1 antitrypsin deficiency: a window into the disease

Imaging modalities such as plain chest radiograph and computed tomography (CT) are important tools in the assessment of patients with chronic obstructive pulmonary disease (COPD) of any etiology. These methods facilitate differential diagnoses and the assessment of individual lung pathologies, such as the presence of emphysema, bullae, or fibrosis. However, as emphysema is the core pathological consequence in the lungs of patients with alpha-1 antitrypsin deficiency (AATD), and because AATD is associated with the development of other lung pathologies such as bronchiectasis, there is a greater need for patients with AATD than those with non-AATD-related COPD to undergo more detailed assessment using CT. In the field of AATD, CT provides essential information regarding the presence, distribution, and morphology of emphysema. In addition, it offers the option to quantify the extent of emphysema. These data have implications for treatment decisions such as initiation of alpha-1 antitrypsin (AAT) therapy, or suitability for surgical or endoscopic interventions for reducing lung volume. Furthermore, CT has provided vital insight regarding the natural history of emphysema progression in AATD, and CT densitometry has underpinned research into the efficacy of AAT therapy. Moving forward, hyperpolarized xenon gas (129Xe) lung magnetic resonance imaging (MRI) is emerging as a promising complement to CT by adding comprehensive measures of regional lung function. It also avoids the main disadvantage of CT: the associated radiation. This chapter provides an overview of technological aspects of imaging in AATD, as well as its role in the management of patients and clinical research. In addition, perspectives on the future potential role of lung MRI in AATD are outlined.

Recurrence of emphysema post-lung transplantation in a patient with alpha 1 antitrypsin deficiency (AATD)

The genetic disorder alpha 1 antitrypsin deficiency (AATD) results in reduced levels of alpha 1 antitrypsin (AAT) in the lung and an imbalance between AAT anti-protease activity and the activity of proteases that degrade elastin and connective tissues. This imbalance commonly leads to the excessive proteolysis of structural tissue of the alveoli, causing chronic obstructive pulmonary disease (COPD)/emphysema. While patients with AATD are encouraged to make lifestyle changes, including stopping smoking, and can be treated with alpha 1 antitrypsin therapy (AAT therapy) to slow progression of COPD/emphysema, damage to the lungs is irreparable, and therefore, lung transplantation is required in severe cases. However, following lung transplant, the genetic cause of AATD-related COPD/emphysema remains, and patients may continue to be at risk of redeveloping COPD/emphysema.

Recurrence of COPD/emphysema was observed in a patient with AATD 2 years after initial successful lung transplantation and cessation of AAT therapy who recommenced smoking after no signs of disease at the 1-year assessment. This case demonstrates that smoking cessation is critical in patients with AATD, even after lung transplant, and it highlights that patients with AATD may benefit from AAT therapy post-lung transplant.

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Patients with AATD can redevelop emphysema following lung transplantation.

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Abstinence from smoking remains crucial in all patients with AATD.

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AAT therapy may be required in patients who redevelop emphysema post-lung transplant.

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.

α1-Antitrypsin deficiency and chronic respiratory disorders

α₁-antitrypsin deficiency (AATD) is a hereditary disorder associated with a risk of developing liver disease and pulmonary emphysema, and other chronic respiratory disorders (mainly asthma and bronchiectasis); Z variant is the commonest deficient variant of AAT. Determining AAT concentration in serum or plasma and identifying allelic variants by phenotyping or genotyping are fundamental in the diagnosis of AATD. Initial evaluation and annual follow-up measurement of lung function, including post-bronchodilator forced expiratory volume in 1 s and gas transfer inform on disease progression. Lung densitometry is the most sensitive measure of emphysema progression, but must not be use in the follow-up of patients in routine clinical practice. The exogenous administration of purified human serum-derived AAT is the only approved specific treatment for AATD in PiZZ. AAT augmentation therapy is not recommended in PiSZ, PiMZ or current smokers of any protein phenotype, or in patients with hepatic disease. Lung volume reduction and endoscopic bronchial valve placement are useful in selected patients, whereas the survival benefit of lung transplant is unclear. There are several new lines of research in AATD to improve the diagnosis and evaluation of the response to therapy and to develop genetic and regenerative therapies and other treatments.