Autoimmune lung disease: Early recognition and treatment helps

A man who was diagnosed with rheumatoid arthritis (RA) five years ago sees his rheumatologist for a follow-up visit. Fortunately, his arthritis is well controlled through medication. He can walk and do all his daily activities without pain. But over the past six months, he’s been feeling short of breath when climbing stairs. He has an annoying dry cough, too. COVID-19? That’s ruled out quickly. But a CT scan of his chest reveals early fibrosis (scarring) of the lungs, most likely related to rheumatoid arthritis. “I can finally walk normally, and now I can’t breathe when I walk!” says the frustrated patient, whose next step is a full evaluation by a pulmonologist.

What is autoimmune lung disease?

This man’s experience offers one example of an uncommon but potentially life-altering complication associated with rheumatic or autoimmune diseases, including:

• rheumatic arthritis, an inflammatory disease that primarily affects the joints
• systemic sclerosis (scleroderma), a fibrosing disorder that typically affects the skin
• dermatomyositis, which results in inflammation in muscles and skin
• systemic lupus erythematosus (SLE or lupus), an inflammatory condition that can affect many parts of the body, including joints, kidneys, and skin.

There are various terms for this complication: autoimmune lung disease, interstitial lung disease, and interstitial fibrosis. Characterized by lung inflammation and/or scarring, it is one of many potential complications affecting different organs in people who have an underlying autoimmune or rheumatic disease.

What is autoimmunity?

Our immune system normally wards off infection and guards against cancer. The term autoimmunity implies that a person’s own immune system sometimes sees its own body tissue as foreign. When this happens, the body generates an immune response against itself. Most people with rheumatoid arthritis experience its effects on joints. But about 10% will also develop symptomatic lung disease like the patient described above.

Why is it important to identify autoimmune lung disease as early as possible?

Studies have shown that this complication is one of the leading causes of illness and death among people with autoimmune diseases. Early disease that is more inflammatory in nature often responds to anti-inflammatory therapies (corticosteroids, for example). But people with mostly fibrotic disease may be more difficult to treat and have poorer outcomes, including disability or a need for oxygen — and in some cases even a lung transplant. However, how quickly or slowly this complication progresses varies. Some people find it progresses more quickly, whereas others may have little or no progression. For that reason, careful surveillance by a pulmonologist who can monitor lung function during regular check-ups is essential.

What triggers this complication and who is most at risk?

While definitive studies have not been done, population studies have identified risk profiles (see here and here). Being male, having a history of cigarette smoking, or having certain antibodies and genetic markers raises risk for autoimmune lung disease. Environmental factors, occupational exposure, and air pollutants also may play a role in developing autoimmunity that affects the lungs (see here and here). Other potential causes include medications that may cause lung injury, or an esophageal dysfunction leading to silent aspiration into the lungs, a common finding in many autoimmune diseases.

Are there treatments for autoimmune lung disease?

Yes, although effectiveness varies. When inflammatory disease is caught early before extensive scarring develops, anti-inflammatory agents, such as corticosteroids, often help. Additionally, catching and treating inflammation early usually leads to a better prognosis.

Recently, the FDA approved pirfenidone (Esbriet) and nintedanib (Ofev) to treat a different fibrotic lung disease called idiopathic pulmonary fibrosis (IPF). Nintedanib is now approved for use in patients with autoimmune lung disease. Both agents can slow, but do not appear to reverse, the presence of fibrosis in the lung. Longer-term studies investigating whether these treatments offer better quality of life and meaningful benefits in terms of illness and death are needed.

If I have a rheumatic or autoimmune disease, what can I do to stay as healthy as possible?

The most important first step is to eliminate any known risks that may cause or exacerbate lung disease. Work with your doctor to stop smoking, if necessary. Ask if you can eliminate any occupational exposures or medications that may contribute to or worsen lung disease. Since early detection of lung inflammation is a goal, rheumatologists often screen people for lung disease at the time of their diagnosis if they are deemed at higher risk, using CT scanning and pulmonary function testing. Increasingly, careful surveillance over time is becoming a normal practice among rheumatologists.

If you do develop signs or symptoms that suggest autoimmune lung disease, such as dry cough and shortness of breath, talk to your doctor. The next step may be a referral to a pulmonologist, or to a multidisciplinary center comprised of pulmonologists, rheumatologists, pathologists, and radiologists, who work as a team to diagnose this complication and develop a treatment plan to reverse or slow the progress of lung disease.