Understanding Alpha-1 Antitrypsin and its Function

Alpha-1 antitrypsin (AAT), also known as α-1 protease inhibitor, is a protein produced mainly by the liver. Its primary role is to protect the body's tissues, particularly the lungs, from being damaged by powerful enzymes released by inflammatory cells, such as neutrophil elastase.

Neutrophil elastase is an enzyme that helps break down damaged tissue and bacteria. However, if left unchecked, it can also destroy healthy lung tissue. AAT acts like a shield, inhibiting the activity of neutrophil elastase and preventing this damage.

Alpha-1 Antitrypsin Deficiency and Emphysema

A deficiency in alpha-1 antitrypsin is a genetic disorder. People with this condition have lower than normal levels of functional AAT in their blood and lungs. This lack of protection means that neutrophil elastase is free to attack and damage the delicate tissues of the lungs over time.

The progressive destruction of lung tissue, particularly the air sacs (alveoli), leads to a lung disease called emphysema. Emphysema makes it difficult to breathe because the damaged air sacs cannot efficiently exchange oxygen and carbon dioxide. It is a major component of Chronic Obstructive Pulmonary Disease (COPD).

Treating Emphysema with Alpha-1 Antitrypsin

For individuals diagnosed with severe alpha-1 antitrypsin deficiency and related emphysema, one treatment option is augmentation therapy. This involves administering purified human alpha-1 antitrypsin protein intravenously. The goal is to increase the levels of functional AAT in the lungs and blood, thereby providing the necessary protection against neutrophil elastase and slowing down the progression of lung damage (emphysema).

This treatment does not repair the damage already done to the lungs, but it can help to preserve the remaining lung function and improve the patient's quality of life. It is a form of protein replacement therapy specific to the underlying deficiency causing the emphysema.

Why Other Options Are Not Treated by Alpha-1 Antitrypsin

Let's look at why the other conditions listed are not treated using alpha-1 antitrypsin:

• Phenylketonuria (PKU): This is a metabolic disorder caused by a deficiency in the enzyme phenylalanine hydroxylase. Treatment involves a special diet low in phenylalanine and sometimes enzyme replacement therapy specifically for phenylalanine hydroxylase, or gene therapy. Alpha-1 antitrypsin is not involved in its treatment.
• Haemophilia A: This is a bleeding disorder caused by a deficiency in clotting Factor VIII. Treatment involves replacing the missing clotting factor VIII, either on demand to stop bleeding or prophylactically to prevent bleeding episodes. Alpha-1 antitrypsin is not used to treat haemophilia A.
• Hepatitis B: This is a viral infection of the liver. Treatment involves antiviral medications that target the Hepatitis B virus. Alpha-1 antitrypsin is not an antiviral agent and is not used to treat Hepatitis B infection.

Based on the function of alpha-1 antitrypsin and the causes of these diseases, it is clear that alpha-1 antitrypsin protein is used specifically to treat emphysema caused by alpha-1 antitrypsin deficiency.

Revision Table: Alpha-1 Antitrypsin and Emphysema

Additional Information on Alpha-1 Antitrypsin Treatment

Alpha-1 antitrypsin deficiency is a significant genetic risk factor for developing emphysema, even in non-smokers. Smoking significantly worsens lung damage in individuals with AAT deficiency because cigarette smoke attracts more inflammatory cells to the lungs, leading to increased release of neutrophil elastase.

Diagnosis of AAT deficiency typically involves a blood test to measure the level of AAT protein. Genetic testing can also identify the specific mutations responsible for the deficiency. Augmentation therapy is a lifelong treatment, usually administered weekly.

While AAT augmentation therapy is primarily used for lung disease (emphysema) associated with AAT deficiency, severe AAT deficiency can also lead to liver disease in some individuals, although augmentation therapy is not used for the liver manifestations.