Asthma features in severe alpha1-antitrypsin deficiency: experience of the National Heart, Lung, and Blood Institute Registry

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.

Development of a risk score to increase detection of severe alpha-1 antitrypsin deficiency

Background

Alpha-1 antitrypsin deficiency (AATD) is an under-recognised genetic cause of chronic obstructive lung disease, and many fewer cases than estimated have been identified. Can a reported respiratory and hepatic disease history from a large AATD testing database be used to stratify a person's risk of severe AATD?

Methods

We analysed data extracted from the AATD National Detection Program. Demographics and medical history were evaluated to predict AATD PI*ZZ genotype. Logistic regression and integer programming models identified predictors and obtained risk scores. These were internally validated on a subset of the data.

Results

Out of 301 343 subjects, 1529 (0.5%) had PI*ZZ genotype. Predictors of severe AATD were asthma, bronchitis, emphysema, allergies, bronchiectasis, family history of AATD, cirrhosis, hepatitis and history of abnormal liver function tests. The derived model establishes a subject's risk of severe AATD, and scores ≥0 had an estimated risk of 0.41%, sensitivity 84.62% and specificity 24.32%. A model simulating guideline recommendations had an estimated risk of 0.51% with a sensitivity of 37.98% and specificity 46.60%. By recommending screening for scores ≥0, we estimate that more subjects would be screened (75.7% versus 53.4%) and detected (84.6% versus 58.2%) compared to a guideline-simulated model.

Conclusion

This medical history risk model is a useful predictive tool to detect subjects at greater risk of having severe AATD and improves sensitivity of detection. Scores <0 are at lower risk and may need not be screened; testing is recommended for scores ≥0 and consistent with current guidelines.

Alpha-1 Antitrypsin Deficiency Liver Disease

Liver disease in homozygous ZZ alpha-1 antitrypsin (AAT) deficiency occurs due to the accumulation of large quantities of AAT mutant Z protein polymers in the liver. The mutant Z protein folds improperly during biogenesis and is retained within the hepatocytes rather than appropriately secreted. These intracellular polymers trigger an injury cascade, which leads to liver injury. However, the clinical liver disease is highly variable and not all patients with this same homozygous ZZ genotype develop liver disease. Evidence suggests that genetic determinants of intracellular protein processing, among other unidentified genetic and environmental factors, likely play a role in liver disease susceptibility. Advancements made in development of new treatment strategies using siRNA technology, and other novel approaches, are promising, and multiple human liver disease trials are underway.

[Alpha 1-antitrypsin deficiency]

INTRODUCTION

Pulmonary emphysema and liver disease are the clinical expressions of alpha 1-antitrypsin deficiency, an autosomal recessive genetic disease.

STATE OF THE ART

Alpha 1-antitrypsin deficiency is usually associated with the homozygous Z variant of the SERPINA1 gene. Its clinical expression always consists in a substantial reduction of alpha 1-antitrypsin serum concentration and its variants are analyzed by isoelectric focalization or molecular techniques. Assessed by CO transfer alteration and CT scan, risk of pulmonary emphysema is increased by tobacco consumption. Assessed by transient elastography and liver ultrasound, risk of liver disease is increased by alcohol consumption or obesity. Treatment of COPD-associated alpha 1-antitrypsin deficiency does not differ from that of other forms of COPD. In patients presenting with severe deficiency, augmentation therapy with plasma-derived alpha 1-antitrypsin reduces the progression of emphysema, as shown in terms of CT-based lung density metrics. Patients with alpha 1-antitrypsin deficiency with a ZZ genotype should refrain from alcohol or tobacco consumption, and watch their weight; so should their close relatives.

PERSPECTIVES

Modulation of alpha 1-antitrypsin liver production offers an interesting new therapeutic perspective.

CONCLUSION

Homozygous (Z) variants of the SERPINA1 gene confer an increased risk of pulmonary emphysema and liver disease, particularly among smokers, drinkers and obese persons.

Alpha-1 Asthma Overlap Syndrome: a Clinical Overview

PURPOSE OF REVIEW

Alpha-1 antitrypsin deficiency (AATD) is one of the most common genetic diseases that is associated with severe complications and yet remains underdiagnosed. The pulmonary symptoms of both AATD and asthma include cough, excessive sputum production, dyspnea, and wheezing. These symptoms overlap significantly leading to difficulty distinguishing between these two conditions and suspicion that there may be an overlap syndrome. We aim to discuss the pathophysiology, clinical manifestations, and treatment of both alpha-1 antitrypsin and asthma and how they may overlap.

RECENT FINDINGS

Recent literature suggests that there is an association between asthma and AATD. This association has been hypothesized to be secondary to an imbalance of elastase and anti-elastase leading to a pro-inflammatory state in patients with AATD. This review serves to overview the pathophysiology, clinical manifestations, and treatment of alpha-1 antitrypsin, asthma, and the increasingly recognized intersection of the two, AATD-asthma overlap syndrome.

Alpha1-antitrypsin deficiency and asthma

α1-antitrypsin deficiency (AATD) is a genetically inherited autosomal-codominant disease with a variable clinical spectrum of lung-related diseases. Pulmonary involvement of α1-antitrypsin deficiency may also include emphysema with variable functional and radiological abnormalities, asthma, and bronchiectasis. Asthma and AATD are mutually exclusive disease entities, but the commonality of neutrophil inflammation across the diseases might suggest common underlying mechanisms of effect. The diseases share many clinical and functional features: patients with AATD commonly first present with asthma-like symptoms; functional alterations may be common to both, such as bronchial hyperresponsiveness or fixed obstruction after bronchial remodeling.  It has been recognized that allergy and asthma often coexist with AATD, but the relationship between allergy, asthma and AATD is not clear. Distinguishing AATD from asthma based on presentation and clinical evaluation is not possible. The clinician must assess each of the elements in the context of the whole patient, any patient with difficult-to-manage asthma should be screened for AATD. From the clinician’s point of view, improving diagnosis in this population is fundamental to optimize clinical management. Genetic studies will probably be needed in the future to unequivocally establish the causal link between AATD and asthma.

[MDR tuberculosis, Alpha-1-anti-trypsin Deficiency, Cough in a Geriatric Nurse]

Multidrug-resistant tuberculosis (MDR-TB) is of low proportion in comparison to the total number of TB patients, however, due to the necessity of a complex medication with potentially severe and life threatening adverse reactions, long term sequelae, and unfavorable outcome special attention is essential. We report the case of a 30-year-old geriatric nurse with a history of chronic cough and hereditary alpha-1-anti-trypsin deficiency (AATD), who suffered from MDR-TB and experienced a number of severe adverse reactions.

Alpha1-antitrypsin deficiency and asthma

PURPOSE OF REVIEW

The aim of the article is to highlight the association between α1-antitrypsin deficiency (AATD) and asthma.

RECENT FINDINGS

AATD is one of the most common and underrecognized autosomal disorders associated with an increased risk of developing liver and lung diseases. An association between α1-antitrypsin and asthma has been suggested, especially with severe forms of this disease. Many studies have shown an increased prevalence of asthma in the α1-antitrypsin-deficient population overtime (4-38%). The biological mechanism underlying these two conditions and able to bind them has not yet been well investigated. As α1-antitrypsin is the main inhibitor of the serine proteinase and it is an important anti-inflammatory protein with pronounced immunomodulatory activities, it can be hypothesized that the link between AATD and asthma might be represented by the elastase/antielastase imbalance and the proinflammatory effect that occurs because of the reduction of this protein.

SUMMARY

There is a strong need for further researches to better understand the molecular mechanisms binding AATD and asthma. It is also recommendable to screen for AATD, late-onset asthma patients, and/or those with not fully reversible airways obstruction.

Vitamin D (1,25(OH)2D3) induces α-1-antitrypsin synthesis by CD4+ T cells, which is required for 1,25(OH)2D3-driven IL-10

Studies to identify novel immune-regulatory functions of active vitamin D (1,25(OH)2D3) in human CD4+ T cells revealed that 1,25(OH)2D3 potently induced expression of the gene SERPINA1, encoding the anti-protease α-1-antitrypsin. We confirmed α-1-antitrypsin protein expression by 1,25(OH)2D3-treated CD4+ T cells, but not in CD8+ T cells or monocytes. α-1-Antitrypsin promotes anti-inflammatory IL-10 synthesis in other immune cell populations. We therefore investigated its immune-regulatory effects in CD4+ T cells. Plasma-derived α-1-antitrypsin drove IL-10 synthesis by CD4+ T cells, which was not dependent on anti-protease activity, but appeared to require a serum-binding factor, since this could not be achieved with recombinant protein. α-1-Antitrypsin is reported to bind complement components, which regulate T cell function. A role for this interaction was therefore probed. Plasma-derived, but not recombinant α-1-antitrypsin contained C3a. Surface Plasmon Resonance and Microscale Thermophoresis demonstrated α-1-antitrypsin binding to C3a. Addition of C3a to CD4+ T cells cultured with recombinant α-1-antitrypsin restored induction of IL-10, whereas neutralisation of C3a abrogated IL-10 induced by plasma-derived α-1-antitrypsin. To interrogate an endogenous role for the α-1-antitrypsin-C3a axis in 1,25(OH)2D3-driven CD4+ T cell IL-10 synthesis, we treated cells from healthy or α-1-antitrypsin-deficient individuals (which transcribe SERPINA1 but do not secrete protein) with 1,25(OH)2D3. A significant correlation was identified between SERPINA1 and IL10 gene expression in healthy donor CD4+ T cells, which was absent in cells from α-1-antitrypsin-deficient individuals. Therefore, α-1-antitrypsin is required for 1,25(OH)2D3-induced IL-10 expression in CD4+ T cells, interacting with C3a to drive IL-10 expression.

Alpha-1-Antitrypsin Deficiency Liver Disease

In homozygous ZZ alpha-1-antitrypsin (AAT) deficiency, the liver synthesizes large quantities of AAT mutant Z, which folds improperly during biogenesis and is retained within the hepatocytes and directed into intracellular proteolysis pathways. These intracellular polymers trigger an injury cascade, which can lead to liver injury. This is highly variable and not all patients develop liver disease. Although not fully described, there is likely a strong influence of genetic and environmental modifiers of the injury cascade and of the fibrotic response. With improved understanding of liver injury mechanisms, new strategies for treatment are now being explored.

Alpha-1 Antitrypsin Deficiency: Phenotypes and Quality of Life

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

Challenges and Prospects for Alpha-1 Antitrypsin Deficiency Gene Therapy

Alpha-1 antitrypsin (AAT) is a protease inhibitor belonging to the serpin family. A number of identified mutations in the SERPINA1 gene encoding this protein result in alpha-1 antitrypsin deficiency (AATD). A decrease in AAT serum concentration or reduced biological activity causes considerable risk of chronic respiratory and liver disorders. As a monogenic disease, AATD appears to be an attractive target for gene therapy, particularly for patients with pulmonary dysfunction, where augmentation of functional AAT levels in plasma might slow down respiratory disease development. The short AAT coding sequence and its activity in the extracellular matrix would enable an increase in systemic serum AAT production by cellular secretion. In vitro and in vivo experimental AAT gene transfer with gamma-retroviral, lentiviral, adenoviral, and adeno-associated viral (AAV) vectors has resulted in enhanced AAT serum levels and a promising safety profile. Human clinical trials using intramuscular viral transfer with AAV1 and AAV2 vectors of the AAT gene demonstrated its safety, but did not achieve a protective level of AAT >11 μM in serum. This review provides an in-depth critical analysis of current progress in AATD gene therapy based on viral gene transfer. The factors affecting transgene expression levels, such as site of administration, dose and type of vector, and activity of the immune system, are discussed further as crucial variables for optimizing the clinical effectiveness of gene therapy in AATD subjects.

The Relationship of the Fibrinogen Cleavage Biomarker Aα-Val360 With Disease Severity and Activity in α1-Antitrypsin Deficiency

BACKGROUND

New markers of COPD and emphysema disease activity are urgently required since current measures of disease severity do not reflect the total disease burden nor predict disease progression. A recently described in vivo marker of neutrophil elastase activity (Aα-Val360) may be an effective marker of COPD and emphysema disease activity, and the current study explores its use in patients with α1-antitrypsin deficiency (AATD) across the disease severity spectrum with particular interest in whether it can be used as an early predictor of the need for intervention.

METHODS

Cross-sectional and longitudinal relationships between Aα-Val360 and full lung-function tests, CT scan densitometry, and other biomarkers were explored in this study of a registry of untreated patients with PiZZ AATD.

RESULTS

The Aα-Val360 related cross-sectionally to physiologic, radiologic, and symptomatic markers of disease severity though not disease progression. Similar cross-sectional relationships were observed in subjects with mild physiologic abnormalities; however, in this subgroup, baseline Aα-Val360 concentration did relate to subsequent disease progression.

CONCLUSIONS

In cross-sectional studies, Aα-Val360 reflects disease severity in AATD and may be a useful marker of disease activity in patients with early disease in whom therapeutic intervention may be indicated.

Alpha-1 antitrypsin and liver disease: mechanisms of injury and novel interventions

α-1-Antitrypsin (α1AT) is a serum glycoprotein synthesized in the liver. The majority of patients with α1AT deficiency liver disease are homozygous for the Z mutant of α1AT (called ZZ or 'PIZZ'). This mutant gene directs the synthesis of an abnormal protein which folds improperly during biogenesis. Most of these mutant Z protein molecules undergo proteolysis; however, some of the mutant protein accumulates in hepatocytes. Hepatocytes with the largest mutant protein burdens undergo apoptosis, causing compensatory hepatic proliferation. Cycles of hepatocyte injury, cell death and compensatory proliferation results in liver disease ranging from mild asymptomatic enzyme elevations to hepatic fibrosis, cirrhosis and hepatocellular carcinoma. There is a high variability in clinical disease presentation suggesting that environmental and genetic modifiers are important. Management of α1AT liver disease is based on standard supportive care and liver transplant. However, increased understanding of the cellular mechanisms of liver injury has led to new clinical trials.

Advances in alpha-1-antitrypsin deficiency liver disease

Alpha-1-antitrypsin (a1AT) deficiency is a common, but under-diagnosed, genetic disease. In the classical form, patients are homozygous for the Z mutant of the a1AT gene (called ZZ or PIZZ), which occurs in 1 in 2,000-3,500 births. The mutant Z gene directs the synthesis of large quantities of the mutant Z protein in the liver, which folds abnormally during biogenesis and accumulates intracellularly, rather than being efficiently secreted. The accumulation mutant Z protein within hepatocytes causes liver injury, cirrhosis, and hepatocellular carcinoma via a cascade of chronic hepatocellular apoptosis, regeneration, and end organ injury. There is no specific treatment for a1AT-associated liver disease, other than standard supportive care and transplantation. There is high variability in the clinical manifestations among ZZ homozygous patients, suggesting a strong influence of genetic and environmental modifiers. New insights into the biological mechanisms of intracellular injury have led to new, rational therapeutic approaches.

Appropriateness of newborn screening for α1-antitrypsin deficiency

OBJECTIVE

The Alpha-1 Foundation convened a workshop to consider the appropriateness of newborn screening for α-1-antitrypsin (AAT) deficiency.

METHODS

A review of natural history and technical data was conducted.

RESULTS

Homozygous ZZ AAT deficiency is a common genetic disease occurring in 1 in 2000 to 3500 births; however, it is underrecognized and most patients are undiagnosed. AAT deficiency can cause chronic liver disease, cirrhosis, and liver failure in children and adults, and lung disease in adults. The clinical course is highly variable. Some neonates present with cholestatic hepatitis and some children require liver transplantation, but many patients remain well into adulthood. Some adults develop emphysema. There is no treatment for AAT liver disease, other than supportive care and liver transplant. There are no data on the effect of early diagnosis on liver disease. Avoidance of smoking is of proven benefit to reduce future lung disease, as is protein replacement therapy. Justifying newborn screening with the aim of reducing smoking and reducing adult lung disease-years in the future would be a significant paradigm shift for the screening field. Recent passage of the Genetic Information Nondiscrimination Act (GINA) and the Affordable Care Act may have a major effect on reducing the psychosocial and financial risks of newborn screening because many asymptomatic children would be identified. Data on the risk-benefit ratio of screening in the new legal climate are lacking.

CONCLUSIONS

Workshop participants recommended a series of pilot studies focused on generating new data on the risks and benefits of newborn screening.

Distinguishing alpha1-antitrypsin deficiency from asthma

OBJECTIVE

To explore the relations that exist between α1-antitrypsin deficiency (AATD) and asthma and to evaluate practices for screening patients with asthma for this genetically determined condition in the context of current guidelines.

DATA SOURCES

English-language articles were selected from a PubMed search using combinations of the following search terms: alpha1-antitrypsin, screening, and asthma.

STUDY SELECTIONS

Studies to be included in this review were based on the authors' expert opinions.

RESULTS

Asthma and AATD are 2 distinct conditions yet they can coexist. Although AATD has a variable symptomatology and some patients may be asymptomatic, many can present with symptoms that are similar to those of asthma, such as dyspnea, wheezing, cough, and mucus production, which can cause confusion at diagnosis. A simple genetic test exists for AATD, which is a single-gene disorder, and the American Thoracic Society and European Respiratory Society guidelines recommend the screening of patients with asthma who exhibit chronic airflow obstruction. Patients with AATD are seen by internal medicine, family medicine, allergy, and pulmonary clinicians, yet there is a generalized lack of awareness of testing among all specialties. This leads to a delayed diagnosis for patients with AATD, typically by 8.3 years.

CONCLUSION

A greater awareness of AATD among clinicians who regularly manage patients with asthma symptoms could increase diagnosis rates, thus optimizing interventions and management strategies to improve patient outcomes.

Nonhuman targets in allergic lung conditions

Existing therapies for allergic asthma are far from perfect: the global prevalence of disease increases despite them and they are poorly effective in dealing with the exacerbations that account for hospitalization and asthma deaths. Commercially, there are pressures on these existing medicines too--a growing threat from generics and reluctance by payers to reimburse for increasingly marginal improvements in medicines with precedented mechanisms. Experience shows that attempts to devise selective small-molecule interventions directed at the myriad of downstream effector pathways has not been a fertile ground for the development of effective new medicines. An alternative strategy, exploiting breakthroughs in understanding the molecular basis of allergenicity and the key role of innate immune mechanisms in asthma, is to direct new approaches to the disease triggers themselves: allergens. This raises interesting possibilities for anti-Lipinski drug design (extracellular nonhuman targets, inhaled delivery) and creates unprecedented pharmacological opportunities in the therapeutic area.

Relationship between frequency, length, and treatment outcome of exacerbations to baseline lung function and lung density in alpha-1 antitrypsin-deficient COPD

Background

Diary cards are useful for analyzing exacerbations in chronic obstructive pulmonary disease (COPD), although factors influencing the length and frequency of each episode are poorly understood. This study investigated factors that influence the features of exacerbations in patients with alpha-1 antitrypsin (AAT) deficiency (PiZ phenotype) and COPD.

Methods

Daily diary cards were collected over 2 years. Patients had emphysema visualized and quantified by computed tomography scan, and had at least one documented exacerbation in the previous year.

Results

The patients (n = 23) had a mean age of 52.5 years, forced expiratory volume in one second (FEV₁) of 1.2 L (38.4% predicted), corrected gas transfer (KCO) of 0.90 mmol/min/kPa/L (59.7% predicted), and 15th percentile lung density of 44.55 g/L. Two hundred and sixty-three exacerbations (164 treated) were identified. The frequency of treated exacerbations correlated negatively with KCO% predicted (r = −0.432; P = 0.022). Exacerbation length (determined for 17 of the patients for whom diary card data through the episode were available) correlated negatively with baseline 15th percentile lung density (r = −0.361; P = 0.003), and increased the longer treatment was delayed (r = 0.503; P < 0.001). Treatment delay was shorter with higher day 1 symptom score, lower baseline FEV₁, FEV₁/forced vital capacity, and lower 15th percentile lung density (r = −0.368, 0.272, 0.461, and 0.786; P = 0.004, 0.036, <0.001, and <0.001, respectively). Time to resolution of exacerbation after treatment initiation was not affected by treatment delay, but correlated negatively with KCO% predicted (r = −0.647; P = 0.007).

Conclusion

In alpha-1 antitrypsin deficiency, the frequency and length of resolution of exacerbation were related to baseline gas transfer. Treatment delay adversely affected exacerbation length, and lung density was the best independent predictor of delay in starting treatment.

Alpha-1 antitrypsin: a potent anti-inflammatory and potential novel therapeutic agent

Alpha-1 antitrypsin (AAT) has long been thought of as an important anti-protease in the lung where it is known to decrease the destructive effects of major proteases such as neutrophil elastase. In recent years, the perception of this protein in this simple one dimensional capacity as an anti-protease has evolved and it is now recognised that AAT has significant anti-inflammatory properties affecting a wide range of inflammatory cells, leading to its potential therapeutic use in a number of important diseases. This present review aims to discuss the described anti-inflammatory actions of AAT in modulating key immune cell functions, delineate known signalling pathways and specifically to identify the models of disease in which AAT has been shown to be effective as a therapy.

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

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

Asthma and COPD in alpha-1 antitrypsin deficiency. Evidence for the Dutch hypothesis

This review summarizes the current information on the relationship between severe alpha-1 antitrypsin deficiency (AATD), asthma and COPD. AATD is a genetic predisposition to the development of early COPD in susceptible individuals and reduction in known factors that enhance lung function loss is the paramount aim of management. Asthma is one controllable condition that leads to the accelerated decline in lung function. Current literature indicates that asthma signs and symptoms are common in those AATD with or without COPD and that bronchodilator response is a risk factor for FEV(1) decline. Furthermore AATD itself predisposes to airway hyper responsiveness, an essential ingredient for reversible airflow obstruction. In the absence of well-characterized markers to distinguish COPD from asthma, clinical diagnosis leads to a delay in the recognition that asthma symptoms such as wheezing can be an early manifestation of COPD in AATD. In addition failure to appreciate asthma overlap in AATD may lead to inadequate suppression of airway inflammation leading to the development of airflow obstruction. The implications of this are discussed as are potential approaches and recommendations for treatment.

Accelerated spirometric decline in New York City firefighters with α₁-antitrypsin deficiency

BACKGROUND

On September 11, 2001, the World Trade Center (WTC) collapse caused massive air pollution, producing variable amounts of lung function reduction in the New York City Fire Department (FDNY) rescue workforce. α₁-Antitrypsin (AAT) deficiency is a risk factor for obstructive airway disease.

METHODS

This prospective, longitudinal cohort study of the first 4 years post-September 11, 2001, investigated the influence of AAT deficiency on adjusted longitudinal spirometric change (FEV₁) in 90 FDNY rescue workers with WTC exposure. Workers with protease inhibitor (Pi) Z heterozygosity were considered moderately AAT deficient. PiS homozygosity or PiS heterozygosity without concomitant PiZ heterozygosity was considered mild deficiency, and PiM homozygosity was considered normal. Alternately, workers had low AAT levels if serum AAT was ≤ 20 μmol/L.

RESULTS

In addition to normal aging-related decline (37 mL/y), significant FEV(1) decline accelerations developed with increasing AAT deficiency severity (110 mL/y for moderate and 32 mL/y for mild) or with low AAT serum levels (49 mL/y). Spirometric rates pre-September 11, 2001, did not show accelerations with AAT deficiency. Among workers with low AAT levels, cough persisted in a significant number of participants at 4 years post-September 11, 2001.

CONCLUSIONS

FDNY rescue workers with AAT deficiency had significant spirometric decline accelerations and persistent airway symptoms during the first 4 years after WTC exposure, representing a novel gene-by-environment interaction. Clinically meaningful decline acceleration occurred even with the mild serum AAT level reductions associated with PiS heterozygosity (without concomitant PiZ heterozygosity).

Ethnic differences in alpha-1 antitrypsin deficiency in the United States of America

Background: Our earlier publications have demonstrated that alpha-1 antitrypsin (AAT) deficiency is not a rare disorder in the United States with at least 33,728 PI*ZZ homozygote individuals at risk.

Method: Using data on the prevalences of the two most common deficiency alleles PI*S and PI*Z in the five major individual ethnic subgroups in the United States, the numbers of heterozygotes for PI*MS and PI*MZ, and compound heterozygotes/homozygotes for PI*SS, PI*SZ and PI*ZZ have been determined for each ethnic subgroup.

Results: When the data for the prevalence of AAT deficiency in individual cohorts are displayed as a function of ethnic subgroup, striking differences are found in the numbers in each of the five phenotypic classes of PI*S and PI*Z. This type of analysis has demonstrated striking differences in the risk for AAT deficiency in each of these five ethnic subgroups. This analysis as a function of ethnic subgroup also has demonstrated that there are higher numbers of each of the five PI*S and PI*Z deficiency classes, namely PI*MS, PI*SS, PI*MZ, PI*SZ and PI*ZZ.

Conclusions: This analysis has demonstrated that the highest risk for AAT deficiency is found in Whites, followed by Hispanics and Blacks with the lowest prevalence among Mexican Americans and no risk among Asians. The numbers for those at risk for AAT deficiency in the United States are well documented and in the present analysis there are, for example, a total of 48,904 PI*ZZ homozygotes at risk. The critical question for our healthcare professionals is ‘When will the medical community acknowledge that AAT deficiency is a prevalent and well-documented human genetic disorder and develop appropriate mechanisms for early diagnosis, medical follow-up and treatment both in the United States and worldwide?’

Alpha-1-antitrypsin augmentation therapy in deficient individuals enrolled in the Alpha-1 Foundation DNA and Tissue Bank

Introduction:

Intravenous augmentation therapy with purified intravenous alpha-1 antitrypsin replaces the deficient protein and is the only currently approved treatment for alpha-1 antitrypsin deficiency (AATD) related lung disease. While augmentation therapy has been available for more than 20 years, there are a limited number of studies evaluating the effect of augmentation on lung function.

Material and methods:

We examined the decline in forced expiratory volume in one second (FEV₁) in patients enrolled in the Alpha-1 Foundation DNA and Tissue Bank in relation to the use or not of alpha-1 antitrypsin augmentation therapy. For the purpose of our analysis we included 164 patients with AATD and PI ZZ genotype.

Results:

Mean age of the patients was 60 years, 52% were females, 94% were white and 78% ex-smokers. The mean FEV₁ at baseline was 1.7 L and the mean FEV₁ % of predicted was 51.3%. The mean follow-up time was 41.7 months. A total of 124 (76%) patients received augmentation therapy (augmented group) while 40 patients (24%) did not received it (non-augmented group). When adjusted by age at baseline, sex, smoking status, baseline FEV₁ % of predicted, the mean overall change in FEV₁ was 47.6 mL/year, favoring the augmented group (ΔFEV₁ 10.6 ± 21.4 mL/year) in comparison with the non-augmented group (ΔFEV₁ −36.96 ± 12.1 mL/year) (P = 0.05). Beneficial ΔFEV₁ were observed in ex-smokers and the group with initial FEV₁ % of predicted of <50%. No differences were observed in mortality.

Conclusions:

In conclusion, augmentation therapy improves lung function in subjects with AATD when adjusted by age, gender, smoking status and baseline FEV₁ % of predicted. The beneficial effects were noted in ex-smoker subjects with FEV₁ below 50% of predicted.

Development of predictive models for airflow obstruction in alpha-1-antitrypsin deficiency

Alpha-1-antitrypsin deficiency is a genetic condition associated with severe, early-onset chronic obstructive pulmonary disease (COPD). However, there is significant variability in lung function impairment among persons with the protease inhibitor ZZ genotype. Early identification of persons at highest risk of developing lung disease could be beneficial in guiding monitoring and treatment decisions. Using a multicenter, family-based study sample (2002-2005) of 372 persons with the protease inhibitor ZZ genotype, the authors developed prediction models for forced expiratory volume in 1 second (FEV(1)) and the presence of severe COPD using demographic, clinical, and genetic variables. Half of the data sample was used for model development, and the other half was used for model validation. In the training sample, variables found to be predictive of both FEV(1) and severe COPD were age, sex, pack-years of smoking, bronchodilator responsiveness, chronic bronchitis symptoms, and index case status. In the validation sample, the predictive model for FEV(1) explained 50% of the variance in FEV(1), and the model for severe COPD exhibited excellent discrimination (c statistic = 0.88).

Screening for Alpha 1 antitrypsin deficiency in Tunisian subjects with obstructive lung disease: a feasibility report

Background

AATD is one of the most common inherited disorders in the World. However, it is generally accepted that AATD in North African populations is not a risk factor for lung and/or liver disease, based on a number of small studies. We therefore planned a screening study for detection of AATD in patients with OLD in a cohort of patients from Kairouan in central Tunisia. Methods: One hundred twenty patients with OLD (asthma, emphysema, COPD) were enrolled in the screening programme. Laboratory diagnosis for AATD was performed according to current diagnostic standards.

Results

We found that 6/120 OLD patients carried an AAT deficient allele, 1 PI*MZ, 1 PI*MPlowel, 3 PI*MMmalton, 1 PI*MMwurzburg.

Conclusion

this pilot study demonstrated that alleles related to deficiency of AAT are not absent in the Tunisian population, and that rare AATD variants prevailed over commonest PI*Z variant. These results would support a larger scale screening for AATD in Tunisia.

Clinical characteristics of subjects with symptoms of alpha1-antitrypsin deficiency older than 60 years

BACKGROUND

The clinical characteristics of elderly subjects with alpha(1)-antitrypsin deficiency (AATD)-associated COPD have not been described.

METHODS

The clinical, demographic, health-related quality of life (HRQoL) characteristics and 1-year exacerbation rates of 275 subjects with AATD and COPD receiving augmentation therapy aged > 59 years (mean [+/- SD] age, 66.3 +/- 5.7 years) were compared to those of 354 subjects aged 50 to 59 years (mean age, 54.3 +/- 2.8 years) and 293 subjects < 50 years (mean age, 43.9 +/- 3.8 years).

RESULTS

Older subjects received diagnoses later in life (mean age at diagnosis, 55.0 +/- 8.5 years) and had a longer diagnostic delay (mean age at diagnosis, 12.9 +/- 14.3 years) than subjects in the other two age groups. Although the proportion of lifetime nonsmokers was higher in the older group, the majority (64%) had significant tobacco exposure but with a longer interval of tobacco abstinence. The mean FEV(1) values (n = 641) were similar between the three age groups, suggesting a slower disease progression in the oldest group. Subjects in the older group were less symptomatic, had less concomitant asthma, and had significantly better scores in most domains of two HRQoL instruments. During follow-up, older subjects had fewer acute exacerbations.

CONCLUSIONS

Subjects with AATD-associated COPD who reach an older age exhibit a more indolent clinical course than younger affected individuals, possibly related in part to differences in tobacco exposure. This finding supports current guidelines that recommend screening of all patients with COPD for AATD, regardless of their age and prior smoking history.

Pollen proteolytic enzymes degrade tight junctions

BACKGROUND AND OBJECTIVE

Asthma and allergic rhinitis are significant, increasing causes of morbidity worldwide. Pollen, a major cause of seasonal rhinitis/conjunctivitis, carries proteolytic enzymes on its surface. We showed previously that peptidase allergens from house dust mites compromise epithelial barrier function by degrading the extracellular domains of the tight junction proteins, occludin and claudin, thus facilitating allergen delivery across epithelial layers. In this study, we aimed to determine whether peptidases from allergenic pollens should similarly be considered to have a role in disrupting tight junctions.

METHODS

Diffusates from stored pollen of Giant Ragweed, White Birch and Kentucky Blue Grass, and fresh pollen from Easter Lily were applied to confluent monolayers of Madin-Darby canine kidney (MDCK) and Calu-3 cells in serum-free medium. Immunofluorescence was performed for the tight junction proteins, occludin, claudin-1 and ZO-1. The effect of pollen diffusate on occludin was studied by Western blotting, and enzymatic activity in the diffusates was demonstrated by zymography. The ability of protease inhibitors to block the action of the diffusate on tight junctions was investigated.

RESULTS

Diffusates from all four allergenic pollens caused loss of immunofluorescence labelling for tight junction proteins on MDCK and Calu-3 cells. The effect was blocked by inhibitors of serine and cysteine proteases. Degradation of occludin was demonstrated by Western blotting and zymography indicated that diffusates contain proteolytic activity.

CONCLUSIONS

Pollen peptidases directly or indirectly disrupt epithelial tight junctions, and this activity should be considered as a possible mechanism for facilitating allergen delivery across epithelia.

Alpha one antitrypsin deficiency: from gene to treatment

Alpha1-antitrypsin deficiency is a genetic disorder which contributes to the development of chronic obstructive pulmonary disease, bronchiectasis, liver cirrhosis and panniculitis. The discovery of alpha1-antitrypsin and its function as an antiprotease led to the protease-antiprotease hypothesis, which goes some way to explaining the pathogenesis of emphysema. This article will review the clinical features of alpha1-antitrypsin deficiency, the genetic mutations known to cause it, and how they do so at a molecular level. Specific treatments for the disorder based on this knowledge will be reviewed, including alpha1-antitrypsin replacement, gene therapy and possible future therapies, such as those based on stem cells.

IL10 polymorphisms are associated with airflow obstruction in severe alpha1-antitrypsin deficiency

Severe alpha(1)-antitrypsin (AAT) deficiency is a proven genetic risk factor for chronic obstructive pulmonary disease (COPD), especially in individuals who smoke. There is marked variability in the development of lung disease in individuals homozygous (PI ZZ) for this autosomal recessive condition, suggesting that modifier genes could be important. We hypothesized that genetic determinants of obstructive lung disease may be modifiers of airflow obstruction in individuals with severe AAT deficiency. To identify modifier genes, we performed family-based association analyses for 10 genes previously associated with asthma and/or COPD, including IL10, TNF, GSTP1, NOS1, NOS3, SERPINA3, SERPINE2, SFTPB, TGFB1, and EPHX1. All analyses were performed in a cohort of 378 PI ZZ individuals from 167 families. Quantitative spirometric phenotypes included forced expiratory volume in one second (FEV(1)) and the ratio of FEV(1)/forced vital capacity (FVC). A qualitative phenotype of moderate-to-severe COPD was defined for individuals with FEV(1) </= 50 percent predicted. Six of 11 single-nucleotide polymorphisms (SNPs) in IL10 (P = 0.0005-0.05) and 3 of 5 SNPs in TNF (P = 0.01-0.05) were associated with FEV(1) and/or FEV(1)/FVC. IL10 SNPs also demonstrated association with the qualitative COPD phenotype. When phenotypes of individuals with a physician's diagnosis of asthma were excluded, IL10 SNPs remained significantly associated, suggesting that the association with airflow obstruction was independent of an association with asthma. Haplotype analysis of IL10 SNPs suggested the strongest association with IL10 promoter SNPs. IL10 is likely an important modifier gene for the development of COPD in individuals with severe AAT deficiency.

Determinants of airflow obstruction in severe alpha-1-antitrypsin deficiency

BACKGROUND

Severe alpha(1)-antitrypsin (AAT) deficiency is an autosomal recessive genetic condition associated with an increased but variable risk for chronic obstructive pulmonary disease (COPD). A study was undertaken to assess the impact of chronic bronchitis, pneumonia, asthma and sex on the development of COPD in individuals with severe AAT deficiency.

METHODS

The AAT Genetic Modifier Study is a multicentre family-based cohort study designed to study the genetic and epidemiological determinants of COPD in AAT deficiency. 378 individuals (age range 33-80 years), confirmed to be homozygous for the SERPINA1 Z mutation, were included in the analyses. The primary outcomes of interest were a quantitative outcome, forced expiratory volume in 1 s (FEV(1)) percentage predicted, and a qualitative outcome, severe airflow obstruction (FEV(1) <50% predicted).

RESULTS

In multivariate analysis of the overall cohort, cigarette smoking, sex, asthma, chronic bronchitis and pneumonia were risk factors for reduced FEV(1 )percentage predicted and severe airflow obstruction (p<0.01). Index cases had lower FEV(1) values, higher smoking histories and more reports of adult asthma, pneumonia and asthma before age 16 than non-index cases (p<0.01). Men had lower pre- and post-bronchodilator FEV(1) percentage predicted than women (p<0.0001); the lowest FEV(1) values were observed in men reporting a history of childhood asthma (26.9%). This trend for more severe obstruction in men remained when index and non-index groups were examined separately, with men representing the majority of non-index individuals with airflow obstruction (71%). Chronic bronchitis (OR 3.8, CI 1.8 to 12.0) and a physician's report of asthma (OR 4.2, CI 1.4 to 13.1) were predictors of severe airflow obstruction in multivariate analysis of non-index men but not women.

CONCLUSION

In individuals with severe AAT deficiency, sex, asthma, chronic bronchitis and pneumonia are risk factors for severe COPD, in addition to cigarette smoking. These results suggest that, in subjects severely deficient in AAT, men, individuals with symptoms of chronic bronchitis and/or a past diagnosis of asthma or pneumonia may benefit from closer monitoring and potentially earlier treatment.

Deficient alpha-1-antitrypsin phenotypes and persistent airflow limitation in severe asthma

BACKGROUND

Persistent airflow limitation is common among patients with severe asthma, but its pathogenesis has not been fully clarified. Severe alpha-1-antitrypsin (AAT) deficiency is a risk factor of chronic airflow limitation and emphysema, and partially deficient phenotypes have been associated with an accelerated decline in lung function. We hypothesized that partial deficiency of AAT (non-PiM AAT phenotype) is a risk factor of persistent airflow limitation in asthma.

METHODS

In 122 patients with severe asthma (86 females; age (median (range)): 44.0 yr (18-75)) postbronchodilator FEV1 and FEV1/VC were measured and the AAT phenotype was determined. Persistent airflow limitation was defined as postbronchodilator FEV1 or FEV1/VC < 75% pred. with TLC > 75% pred.

RESULTS

Six patients (4.9%) had a non-PiM phenotype (1 MF, 3 MS, 1 MZ and 1 SZ). Of the 58 patients with persistent airflow limitation only 1 patient (1.7%) had a non-PiM phenotype vs. 7.8% among the patients without persistent airflow limitation (P = 0.21). Postbronchodilator FEV1/VC (% pred.) was higher in the non-PiM patients than in the PiM patients (P = 0.02), the other lung function parameters were not different. Linear regression analysis showed no association between AAT phenotype and FEV1% predicted (P = 0.26).

CONCLUSIONS

AAT heterozygoty does not seem to be an important risk factor of persistent airflow limitation in patients with asthma. Although confirmation by longitudinal follow-up studies with larger sample sizes is needed, these results suggest that routine assessment of the AAT phenotype is not indicated in asthmatic patients even if they exhibit fixed airflow limitation.

Asthma and allergy in alpha-1 antitrypsin deficiency

This study was designed to determine the prevalence of asthma and atopy, in a large group of subjects with alpha-1 antitrypsin deficiency (AATD) participating in the Alpha-1 Foundation Research Registry. A survey was mailed to all Registry participants (N=2418) and results were collated by AATD phenotype. Participants with PiZZ deficiency were compared to PiMZ and other phenotypes by nonparametric statistics. Responses were collected from 757 participants (31%). Overall 44.6% (N=338) reported MD diagnosed asthma. Wheezing was reported in 76% with respiratory infections, activity and exposure to dusts, fumes, and allergens as common triggers. Across the three groups reported asthma with a history of allergies was reported from 20% to 25%. Wheezing symptoms were significantly less common in the PiMZ group compared with other groups. Of those reporting asthma, 83% of the PiZZ group (n=192) also reported another chronic obstructive pulmonary disease (COPD) diagnosis compared to 48% of the PiMZ group (n=24). Asthma as the only reported diagnosis was three times more prevalent in the PiMZ group compared with the PiZZ group. Although asthma diagnosis is imprecise in the presence of COPD, the high prevalence of wheezing to allergen and irritant exposures with symptoms of atopy suggests that asthma is common in AATD but usually associated with COPD. Those with AATD who are susceptible to asthma require allergy evaluation and aggressive anti-inflammatory strategies as part of their management.

Trends in the diagnosis of symptomatic patients with alpha1-antitrypsin deficiency between 1968 and 2003

BACKGROUND

Alpha1-antitrypsin deficiency (AATD) is usually underrecognized, with only 5% of cases being diagnosed in the estimated 100,000 affected individuals in the United States. To support current guidelines recommending AATD testing of all individuals with COPD, we analyzed the diagnostic experience of a large cohort of symptomatic patients with AATD.

METHODS

A total of 1,020 members of AlphaNet, a not-for-profit health management company devoted to patients with AATD, provided information regarding their AATD diagnostic experience as part of a larger survey-based outcome study.

RESULTS

The average age at diagnosis was 45.5 +/- 9.5 years, and the average interval between the onset of symptoms and diagnosis was 8.3 +/- 6.9 years (+/- SD); 30.8% were diagnosed in patients > 50 years old. Two thirds of the diagnoses were made by the first or second physician, and 20% by the fourth or more physicians. From 1968 to 2003, there was a steady increase in age at diagnosis (p < 0.05), the number of physicians required for diagnosis (p > 0.05), and years with symptoms before diagnosis (p > 0.05), while the proportion of cases diagnosed by the first or second physician decreased (p < 0.001). Individuals with a diagnosis at < 35 years of age saw fewer physicians than other age groups (p < 0.05), and show a tendency toward a shorter diagnostic interval over time (p > 0.05). Diagnoses were made in men earlier than in women (p < 0.05), and the proportion of individuals in whom AATD was detected because of asthma or COPD has increased (p < 0.05).

CONCLUSION

There has not been a significant improvement in earlier disease diagnosis between 1968 and 2003. There has been improved AATD detection in older individuals. The diagnostic delay is still significant, and efforts should be directed to increase early AATD detection by health-care providers and patients.

Overlap of asthma and chronic obstructive pulmonary disease

PURPOSE OF REVIEW

Asthma and chronic obstructive pulmonary disease (COPD) are both defined by the presence of airflow obstruction, but they present distinguishing differences in terms of both risk factors and clinical phenotypes. Yet it is quite common in the clinical setting to observe patients with asthma showing COPD-like phenotypes, and vice versa, making it a priority to search for optimal prevention, treatment, and management strategies for these cases of coexisting lung obstructive diseases.

RECENT FINDINGS

Recent studies have provided further evidence of strong epidemiologic and clinical links between asthma and COPD. Adult subjects with active asthma are as much as 12 times more likely to acquire COPD over time than subjects with no active asthma. Signs identifying patients with asthma predisposed to developing COPD may already be present at the early stages of the disease, a finding with potential implications for prevention of COPD. In addition to spirometry and other pulmonary function tests (such as measurements of residual volume and diffusing capacity of the lung for carbon monoxide), recent evidence suggests that the assessment of type and degree of airway remodeling and the evaluation of inflammatory markers might prove useful in the future to characterize phenotypically patients with coexisting asthma and COPD.

SUMMARY

The nature of the association between asthma and COPD remains unclear and open to discussion. Further research is required to develop effective management algorithms for patients with multiple obstructive lung diseases, determine to what extent early treatment and optimal management of asthma may protect against progression into COPD, and identify genetic markers of individual susceptibility to specific lung disease phenotypes and pharmacologic treatments.

The proportional Venn diagram of obstructive lung disease in the Italian general population

STUDY OBJECTIVES

The Venn diagram of obstructive lung disease (OLD) has been recently quantified. We aimed to quantify the proportion of the general population with OLD, and the intersections of physician-diagnosed asthma, chronic bronchitis (CB), and emphysema in two Italian general population samples, in relationship to airflow obstruction (AO) determined through spirometry.

DESIGN AND PARTICIPANTS

We analyzed data from two prospective studies (4,353 patients) carried out in the rural area of Po River delta from 1988 to 1991 and in the urban area of Pisa from 1991 to 1993.

RESULTS

Prevalence rates of asthma, CB, and emphysema were 5.3%, 1.5%, and 1.2% in the Po delta, and 6.5%, 2.5%, and 3.6% in Pisa. A double Venn diagram, which was used to quantify the distribution of CB, emphysema, and asthma in relation to the presence/absence of AO, identified 15 categories. Isolated AO was the most frequent category (Po delta, 11.0%; Pisa, 6.7%), followed by asthma only without AO (Po delta, 3.3%; Pisa, 4.3%). The combination of the three OLD conditions was the only category that always showed higher prevalence rates for those with AO (Po delta, 0.20%; Pisa, 0.16%) than for those without AO (Po delta, 0.04%; Pisa, 0.05%). Of those with either OLD or AO, there were 61.4% in Po delta and 38.2% in Pisa with isolated AO, 24.8% and 41.9%, respectively, with an OLD without AO, and 13.8% and 19.9%, respectively, with simultaneous OLD and AO. For both genders, the frequency of isolated asthma decreased with age, while that of isolated AO, CB-emphysema, and the combination of asthma and CB-emphysema increased.

CONCLUSION

About 18% of the Italian general population samples either reported the presence of OLD or showed spirometric signs of AO. We confirmed that the Venn diagram of OLD can be quantified in the general population by extending the mutually exclusive disease categories (including a concomitant diagnosis of asthma, CB, or emphysema) to 15.

Alpha1-Antitrypsin as a Risk for Infant and Adult Respiratory Outcomes in a National Birth Cohort

Reduced alpha1-antitrypsin (AAT) encoded by the gene SERPINA1 is a potential risk for pulmonary disease. We investigated SERPINA1 polymorphism as a risk for infant and adult pulmonary morbidity, and adult respiratory function and its change between 43 and 53 yr. We used data on a British national representative sample (n = 5,362) studied since birth in 1946 to age 53 yr (when n = 3,035), when DNA was first obtained. SERPINA1 Z and, to a lesser extent, S carriers had an increased risk of infant lower respiratory infection compared with those who were neither S nor Z carriers (Z carriers: odds ratio = 2.32, 95% confidence interval = 1.37-3.92; S but not Z carriers odds ratio = 1.58, 95% confidence interval = 1.10-2.28) after adjustment for environmental, socioeconomic, and developmental factors, and breast-feeding. There was no difference in the adult outcomes at 53 yr according to genotype, nor was there any association of genotype with change in forced expiratory volume at 1 s between 43 and 53 yr. Lower alpha1-antitrypsin, as indicated by carrier status for the Z and S alleles, was a risk for infant lower respiratory infection, but not for adult respiratory outcomes.

Constitutive protease-activated receptor-2-mediated migration of MDA MB-231 breast cancer cells requires both beta-arrestin-1 and -2

Protease-activated receptor-2 (PAR-2) is activated by trypsin-like serine proteases and can promote cell migration through an ERK1/2-dependent pathway, involving formation of a scaffolding complex at the leading edge of the cell. Previous studies also showed that expression of a dominant negative fragment of beta-arrestin-1 reduces PAR-2-stimulated internalization, ERK1/2 activation, and cell migration; however, this reagent may block association of many proteins, including beta-arrestin-2 with clathrin-coated pits. Here we investigate the role of PAR-2 in the constitutive migration of a metastatic breast cancer cell line, MDA MB-231, and use small interfering RNA to determine the contribution of each beta-arrestin to this process. We demonstrate that a trypsin-like protease secreted from MDA MB-231 cells can promote cell migration through autocrine activation of PAR-2 and this correlates with constitutive localization of PAR-2, beta-arrestin-2, and activated ERK1/2 to pseudopodia. Addition of MEK-1 inhibitors, trypsin inhibitors, a scrambled PAR-2 peptide, and silencing of beta-arrestins with small interfering RNA also reduce base-line migration of MDA MB-231 cells. In contrast, a less metastatic PAR-2 expressing breast cancer cell line does not exhibit constitutive migration, pseudopodia formation, or trypsin secretion; in these cells PAR-2 is more uniformly distributed around the cell periphery. These data demonstrate a requirement for both beta-arrestins in PAR-2-mediated motility and suggest that autocrine activation of PAR-2 by secreted proteases may contribute to the migration of metastatic tumor cells through beta-arrestin-dependent ERK1/2 activation.