Is breathing difficulty a sign of "dirty" lungs?

Have you ever considered the delicate metabolism going on in your lungs behind your daily smooth breathing?

But there's a condition called Pulmonary Alveolar Proteinosis (PAP) that acts like a layer of "dirt" on the alveoli, impairing the lung's ventilation function. From shortness of breath after activity to breathlessness even at rest, it quietly affects your breathing.

◆ What are the causes of Pulmonary Alveolar Proteinosis?

Under normal circumstances, an active substance exists on the inner surface of the alveoli. Its primary function is to reduce alveolar surface tension, maintaining the normal structure and function of the alveoli. It is a key substance for the normal functioning of the respiratory system.

This active substance is continuously produced by lung tissue and cleared by certain cells, maintaining a constant state of equilibrium. When this clearance is impaired, this active substance accumulates within the alveolar cavity, a condition known as PAP. Alveolar macrophages are primarily responsible for the clearance of surfactant, so any factor that causes macrophage dysfunction can trigger PAP.

Currently, there are three main mechanisms believed to cause PAP:

1. The body produces anti-GM-CSF antibodies. These antibodies interfere with the normal function of alveolar macrophages, preventing them from properly clearing surfactant. This is the most common mechanism.
2. Genetic factors. Some people are born with abnormalities in genes related to surfactant clearance, leading to congenital defects in alveolar macrophage function and the disease.
3. Other diseases. For example, blood disorders can indirectly lead to impaired alveolar macrophage function, which in turn causes surfactant to accumulate in the alveoli, triggering PAP.

◆ What are the symptoms of pulmonary alveolar proteinosis?

The primary symptom of PAP is dyspnea, which is related to the inability to properly clear surfactant and its accumulation in the alveoli. These accumulated substances impede gas exchange within the alveoli, leading to hypoxia, which worsens as the disease progresses.

In the early, milder stages of the disease, patients typically only experience discomfort during strenuous activity, such as chest tightness, shortness of breath, and a feeling of "running out of breath." In the later, more severe stages, even at rest, patients experience significant dyspnea due to hypoxemia. The degree of dyspnea corresponds to the severity of the disease.

◆ How is pulmonary alveolar proteinosis treated?

The prognosis of PAP varies: only a small percentage of patients resolve spontaneously, while the majority experience progressive disease progression over time.

If left untreated, patients can experience worsening dyspnea and hypoxia, leading to respiratory failure and even death.

Therefore, once a diagnosis is confirmed, and especially if follow-up reveals progression, aggressive treatment is necessary.

• Treatment plans should be tailored to the cause.

01. Hereditary PAP:

Caused by a genetic abnormality, the primary treatment is bronchoalveolar lavage. Symptoms can be alleviated by regularly instilling large amounts of normal saline into the lungs to remove deposited surfactant. However, surfactant can accumulate again, necessitating repeated lavages.

02. Secondary PAP:

Caused by factors such as blood disorders and occupational dust exposure. Treatment focuses on eliminating the triggering factor and treating the underlying condition. Some patients may experience improvement after the triggering factor is eliminated or the underlying condition is controlled.

03. Primary PAP (caused by the body's production of anti-GM-CSF antibodies):

Bronchoalveolar lavage (whole lung lavage) is the preferred treatment. GM-CSF is a cytokine that maintains alveolar macrophage function. Inhaled GM-CSF supplementation can partially offset the effects of antibodies and restore alveolar macrophage function, achieving therapeutic goals.

Alternatively, plasma exchange or high-dose immunosuppressants may be considered for severely ill patients, but these methods are less commonly used.

Advances in medicine always provide greater protection for health. We hope everyone can avoid breathing problems, enjoy every breath, and maintain a healthy state.