alpha-1-antitrypsin deficiency

Alpha-1-Antitrypsin Deficiency

Mark Brantly, M.D.Professor & Chief

Division of Pulmonary, Critical Care & Sleep MedicineUniversity of Florida College of Medicine

Objectives

1. Learn about the clinical and molecular features of Alpha-1-Antitrypsin deficiency

2. Learn who should be screened for Alpha-1-Antitrypsin deficiency

3. Learn about current and new therapies for Alpha 1-Antitrypsin Deficient Individuals

Alpha-1-Antitrypsin Deficiency

• AAT level 5.75 M PI*Z (>95%)• PI*Z Glu to Lys at 342• Clinical Presentation

– Asthma– Bronchiectasis– Pneumonia– COPD– Cirrhosis

• Rapid decline in lung function• Premature disability and death• Smokers die 20 years before

non-smokers• Passive Smoking is especially

risk for Deficient Children

51 y/o AAT Deficient Individual Chest CT Coronal View

1-Antitrypsin

• 52 kDa glycoprotein• Acute phase reactant “anti-

inflammatory”• Secreted in large amount

from hepatocytes, but also express in many other tissues

• At least 100 different alleles• 34 alleles associated with

deficiency or dysfunction• Mutations may affect the

amount secreted and/or its function

• The frequency of the Z allele suggest a selective advantage

Met 358

Our Genetic LegacyVariation is the Spice of Life

• “Insanity is hereditary-you get it from your kids”, MBrantly, father to 14, 16 and 28 year old children

• Alleles are the result of genetic variation on the same gene

• Not all alleles are associated with increased risk of disease

• Genetic Load: 5-15 “lethal” genes• Genes are not absolutely

predictive for the development of disease

• Risk (lung disease) MM=1, MZ~1.5-3, SZ~4-8, ZZ~18

Active SiteZ MutationGlu to Lys 342

1-Antitrypsin Deficiency

• AAT level 5.75 M PI*Z (>95%)• Common genetic disease, 75-100,000

homozygous individuals in USA (1:2500-4000)

• Frequency of S and Z alleles in Turkey is unknown

• COPD and Liver disease• Rapid decline in lung function often

associated with lung infections• Asthma is common presenting feature• Carriers are at increased risk for COPD• Most common inherited risk factor for

COPD (~10% are MZ, SZ or ZZ)• Early diagnosis and preventive care

translate into health benefits

5000

~95,000

The Problem

WHO-ATS-ERS-ACCP Recommendations

• All individuals with COPD should be tested once with PI/genotyping plus an AAT level

• All individuals with asthma and a non-reversible component

• Family members of individuals with Alpha-1-antitrypsin deficiency

• Individuals with “cryptogenic” cirrhosis

1-Antitrypsin-Neutrophil Elastase Docking

1-antitrypsin

Neutrophilelastase

Met358

Asn46

Asn83

Asn247

Asp46

Asn144

Asn95

His46

Ser195

Protease-Antiprotease Balance

Normal AAT Deficiency

Neutrophil Elastase Burden

Anti-Neutrophil Elastase Protection

Neutrophil Elastase Burden

AAT

AAT

• Lung damage is the result of both a burden of neutrophils and its toxic products and a lack of sufficient AAT in the lower lung.

Anti-Neutrophil Elastase Protection

Lung Injury in AAT Deficient Individuals

Oxidants

Proteases

-Defensins

Effectsof

Injury

Propagation

andMaintenancePro-Inflammatory Cells (PMN, Mast Cells, Lymphocytes &AM)

InitiationSmoking

Infections

Polymers of Z AAT

Cellular Response to UPR

Pro-Inflammatory Molecules (LTB4 & IL8)

Recruitment-Expansion-ActivationFibrosis

AATAirwayAlveolus

1-Antitrypsin is More than an Antiprotease

• 52 kDa glycoprotein• Acute phase reactant “anti-

inflammatory”• Secreted in large amount from

hepatocytes, but also expressed in macrophages & bronchial epithelium

• Broad spectrum anti-protease• Inhibits -defensin cytotoxicity

and pro-inflammatory properties• Anti-oxidant with 9 methionines

Met 358

AAT Gene

SERPIN Cluster

AAT Gene Coding Region

AAT Normal Alleles

AAT Null Variants

Active Site

Active Site

AAT Deficiency Alleles

AAT Z Protein

Active Site

Z MutationGlu to Lys 342

Active Site

The Spectrum of Lung Disease AAT Deficiency

• Normal Lung Function with CT Evidence of Emphysema

• Emphysema• Bronchiectasis• Rapid decline in lung function often

associated with lung infections• Asthma is common presenting

feature• Accelerated Rate of Decline in Lung

Function– FEV1 35-80% -ROD 83.5ml/year– Increase ROD in BDR+

Individuals• Evidence that Lung Inflammation

Begins Early

Airways Disease and EmphysemaIn AAT Deficiency

• Deficient individuals frequently have CT scan evidence of bronchiectasis

• Greater the 65% of AAT NHLBI Registry subjects have a positive BDR

• In animal models airway hyper-reactivity is reduced by AAT

• Anecdotal evidence from patients on augmentation therapy

• Large fraction of deficient individuals present as asthmatics

Adults

Age of onset; 25-45 years

Pulmonary

Dyspnea Emphysema

Chronic Bronchitis Episodic Bronchitis

Pneumonia Asthma

Hepatic Cirrhosis

Hepatosplenomegaly

Gastrointestinal Bleeding Ascites

Hepatoma

Children

Age of onset; 2 months-8 years

Hepatic

Neonatal Cholestatic Jaundice

Failure to Thrive Lethargy/Irritability

Hepatosplenomegaly Vomiting Diarrhea Cirrhosis

Gastrointestinal Bleeding Ascites

Pulmonary

Asthma Dyspnea

Other

Clinical Features of AAT Deficiency by Age Group

Reduction in Life Span

• Only 52% of 1AT Deficient Individuals with pulmonary

symptoms are alive at age 50• Only 16% of 1AT Deficient

individuals with pulmonary symptoms are alive at age 62• Most common causes of death

– Emphysema– Infection– Sepsis – Liver Disease

Brantly, et al Am Rev Respir Dis. 138(2): 327-36, 1988

Laboratory Methods for the Detection of AAT Deficient Individuals

• AAT Genotyping (typically S and Z alleles) RFLP or Taqman

• AAT PI typing (Phenotype) isoelectic Focusing

• AAT level-Nephelometry• High Resolution DNA Melt• Sample types: include,

plasma, serum, dried blood spot and buccal swabs

• Future-monoclonal AB, Amptamers, “office test” kits

• AAT Deficiency Diagnosis in a LABORTORY Diagnosis

1-Antitrypsin Typing (PI Typing)

Relationship Between PI Type and Serum Level

QO

10

20

50

40

30

MS MZMM SZ ZZ

Ser

um

1-A

ntitr

ypsi

n Le

vel (

M)

1-Antitrypsin PI Type

Ser

um

1-A

ntitr

ypsi

n Le

vel (

mg

dl)260

156

52

104

208Normal Range

Typical Pedigree

Treatment of Lung Disease

1AT Deficiency

Neutrophil Elastase Burden

Anti-neutrophil Elastase Protection

AAT

Reduce the burden of neutrophil products

Augment the lung AAT concentration

Prevention of Lung Destruction

• Smoking cessation*, avoidance of smoke, and dust

• Pneumococcal and influenza vaccination• Aggressive antibiotic therapy• Treatment of airway disease with inhaled

steriods and bronchodilators• *Children with AAT Deficiency are at great

Risk of Lung Destruction when their parent Smoke

Therapies of AAT Deficiency

• Intravenous Augmentation Therapy– Pooled Human AAT(60mg/kg)

• >$100,000/year no controlled studies but is FDA approved

• Potential of viral and prion transmission

• Therapies in Development– Aerosolized AAT

• rAAT- nebulized• Pooled Human-dry powder (like insulin) • hAAT nebulized

Specific Therapies of AAT Deficiency (continued)

• Therapies in Development– Gene Therapy

• Muscle delivery of AAV1/2- AAT trials began in UF

– Many new therapies on the horizon

Dry Powder Aerosolize AAT

Replace weekly IV dosing with daily pulmonary dosing– reduced drug requirements– increased patient convenience

A1PI

Powder Particles1 - 2 m

Powder Production(Spray drying)

Pulmonary Delivery System(Pneumatic reusable)

Powder Packaging(Unit dose blisters)

~ 6 mg A1PI / blister

First

• It’s a Inherited Disorder--- Counseling and Family Screening

AOF-UF Detection Lab Testing Algorithm

Identification of GenotypeZZ, SZ, SS, MS* & MZ*

DBS AAT Level

Positive for S or Z allelesNegative for S or Z alleles(98% are MM)

Individual with Obstruction

Stop or PI typefrom

plasma or serum Plasma Sample Second Confirmation by PI

Typing

*MS & MZ with low AAT Levels are likely Null or Rare Low Level AAT Alleles and Plasma Sample is requested for PI typing &SNP scan by High Resolution DNA Melt.

DBS Genotyping

for S & Z Alleles

WHO-ATS-ERS Recommendations

• All individuals with COPD should be tested once with PI/genotyping plus an 1-antitrypsin level

• All individuals with asthma and a non-reversible component

• Family members of individuals with 1-antitrypsin deficiency

• Individuals with “cryptogenic” cirrhosis

Summary: COPD Management

Diagnose

Reduce risk

Smoking cessation

Reduce symptoms

Reduce complications

PharmacotherapyPulmonary rehabilitation

ImmunizeTreat exacerbationsConsider oxygen

SpirometryAAT Testing!!!

Education

Education

Education

Education