Implications of a Change of Paradigm in Alpha1 Antitrypsin Deficiency Augmentation Therapy: From Biochemical to Clinical Efficacy

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.

Nine controversial questions about augmentation therapy for alpha-1 antitrypsin deficiency: a viewpoint

Augmentation therapy with intravenous alpha-1 antitrypsin is the only specific treatment for alpha-1 antitrypsin deficiency (AATD)-associated emphysema. This treatment has been available and remained basically unchanged for more than 35 years, but many questions persist regarding its indications, regimen of administration and efficacy. Because AATD is a rare disease, it has not been possible to conduct randomised, placebo-controlled trials that are adequately powered for the usual outcomes analysed in non-AATD-related COPD, such as lung function decline, exacerbations, symptoms or quality of life. New outcomes such as lung densitometry measured by computed tomography are more sensitive for identifying emphysema progression but are not widely accepted by regulatory agencies. In addition, clinical manifestations, severity and the natural history of lung disease associated with AATD are very heterogeneous, which means that individual prediction of prognosis is challenging. Therefore, the indication for augmentation is sometimes a dilemma between initiating treatment in individuals who may not develop significant lung disease or in whom disease will not progress and delaying it in patients who will otherwise rapidly and irreversibly progress.Other areas of debate are the possible indication for augmentation in patients with severe AATD and respiratory diseases other than emphysema, such as bronchiectasis or asthma, and the use of therapy after lung transplant in AATD patients. All these uncertainties imply that the indication for treatment must be personalised in expert reference centres after in-depth discussion of the pros and cons of augmentation with the patient.

[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.

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.

Clinical manifestations of a new alpha‐1 antitrypsin genetic variant: Q0parma

Alpha‐1 antitrypsin deficiency is an autosomal, codominant disorder caused by mutations of the SERPINA1 gene. Several mutations of SERPINA1 have been described associated with the development of pulmonary emphysema and/or chronic liver disease and cirrhosis. Here, we report a very rare PI*Q0parma variant identified for the first time in an Italian family originally from the city of Parma in Northern Italy

Methodologies for the Determination of Blood Alpha1 Antitrypsin Levels: A Systematic Review

Background: The study of hematic concentrations of alpha1 antitrypsin (AAT) is currently one step in the diagnosis of AAT deficiency. To try to clarify the relevance of the laboratory techniques, we carried out a systematic review of the literature. Methods: Studies evaluating the quantification of AAT in peripheral blood were searched in PubMed in July 2021. The selection criteria included (1) any type of study design that included a quantification of AAT in peripheral blood; (2) studies written in English or Spanish; (3) studies evaluating human beings; and (4) studies involving adults. Results: Out of 207 studies, the most frequently used techniques were nephelometry (43.9%), followed by ELISA (19.8%) and turbidimetry (13.5%). Altogether, 182 (87.9%) cases expressed their results in units of gram, while 16 (7.7%) articles expressed them in units of mole. Only 2.9% articles referred to the standard used, 43.5% articles indicated the commercial kit used, and 36.2% indicated the analyzer used. Conclusions: The technical aspects of these determinations are not always reported in the literature. Journals should be attentive to these technical requirements and ensure that they are included in the works in which AAT is determined in order to ensure a correct interpretation of the study findings.

Mechanisms, Pathophysiology and Currently Proposed Treatments of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is one of the leading global causes of morbidity and mortality. A hallmark of COPD is progressive airflow obstruction primarily caused by cigarette smoke (CS). CS exposure causes an imbalance favoring pro- over antioxidants (oxidative stress), leading to transcription factor activation and increased expression of inflammatory mediators and proteases. Different cell types, including macrophages, epithelial cells, neutrophils, and T lymphocytes, contribute to COPD pathophysiology. Alteration in cell functions results in the generation of an oxidative and inflammatory microenvironment, which contributes to disease progression. Current treatments include inhaled corticosteroids and bronchodilator therapy. However, these therapies do not effectively halt disease progression. Due to the complexity of its pathophysiology, and the risk of exacerbating symptoms with existing therapies, other specific and effective treatment options are required. Therapies directly or indirectly targeting the oxidative imbalance may be promising alternatives. This review briefly discusses COPD pathophysiology, and provides an update on the development and clinical testing of novel COPD treatments.

Therapeutic benefits of recombinant alpha1-antitrypsin IgG1 Fc-fusion protein in experimental emphysema

BACKGROUND

Alpha-1 antitrypsin (AAT) is a major serine protease inhibitor. AAT deficiency (AATD) is a genetic disorder characterized by early-onset severe emphysema. In well-selected AATD patients, therapy with plasma-derived AAT (pAAT), "augmentation therapy", provides modest clinical improvement but is perceived as cumbersome with weekly intravenous infusions. Using mouse models of emphysema, we compared the effects of a recombinant AAT-IgG1 Fc-fusion protein (AAT-Fc), which is expected to have a longer half-life following infusion, to those of pAAT.

METHODS

In an elastase model of emphysema, mice received a single intratracheal instillation of porcine pancreatic elastase (PPE) or human leucocyte elastase (hLE). AAT-Fc, pAAT, or vehicle was administered intraperitoneally 1 day prior to or 3 weeks following elastase instillation. Lung function and histology assessments were performed at 7 and 32 days after elastase instillation. In a cigarette smoke (CS) model of emphysema, mice were exposed to CS daily, 5 days a week, for 6 months and AAT-Fc, pAAT, or vehicle were administered every 10 days during the last 3 months of CS exposure. Assessments were performed 3 days after the last CS exposure. Immune responses to lung elastin peptide (EP) and the effects of AAT-Fc or pAAT treatment on dendritic cell (DC) function were determined ex vivo.

RESULTS

Both elastase instillation and CS exposure triggered emphysema-like alveolar enlargement, increased lung compliance, and increased markers of inflammation compared to controls. Administration of AAT-Fc either prior to or following elastase instillation or during CS exposure provided greater protection than pAAT against alveolar enlargement, lung dysfunction, and airway inflammation. When challenged ex vivo with EP, spleen mononuclear cells from elastase-exposed mice exhibited dose-dependent production of IFNγ and IL-17, suggesting immune reactivity. In co-culture experiments with splenic CD4+ T cells isolated from elastase-exposed mice, AAT-Fc treatment prior to EP-priming of bone marrow-derived dendritic cells inhibited the production of IFNγ and IL-17.

CONCLUSIONS

Compared to pAAT, AAT-Fc more effectively prevented or attenuated elastase- and CS-induced models of emphysema. These effects were associated with immunomodulatory effects on DC activity. AAT-Fc may provide a therapeutic option to individuals with AATD- and CS-induced emphysema.

Alpha-1 antitrypsin deficiency and recombinant protein sources with focus on plant sources: Updates, challenges and perspectives

Alpha-1 antitrypsin deficiency (A1ATD) is an autosomal recessive disease characterized by low plasma levels of A1AT, a serine protease inhibitor representing the most abundant circulating antiprotease normally present at plasma levels of 1-2 g/L. The dominant clinical manifestations include predispositions to early onset emphysema due to protease/antiprotease imbalance in distal lung parenchyma and liver disease largely due to unsecreted polymerized accumulations of misfolded mutant A1AT within the endoplasmic reticulum of hepatocytes. Since 1987, the only FDA licensed specific therapy for the emphysema component has been infusions of A1AT purified from pooled human plasma at the 2020 cost of up to US $200,000/year with the risk of intermittent shortages. In the past three decades various, potentially less expensive, recombinant forms of human A1AT have reached early stages of development, one of which is just reaching the stage of human clinical trials. The focus of this review is to update strategies for the treatment of the pulmonary component of A1ATD with some focus on perspectives for therapeutic production and regulatory approval of a recombinant product from plants. We review other competitive technologies for treating the lung disease manifestations of A1ATD, highlight strategies for the generation of data potentially helpful for securing FDA Investigational New Drug (IND) approval and present challenges in the selection of clinical trial strategies required for FDA licensing of a New Drug Approval (NDA) for this disease.