Can Autoimmune Diseases Cause Lung Scarring or ILD?

Yes, rheumatoid arthritis and other autoimmune diseases can cause lung problems, including lung scarring. In autoimmune conditions, your immune system mistakenly attacks your body’s own healthy tissues. Just as it can attack your joints or skin, it can also affect your lungs ^[1]. When this immune system attack leads to inflammation or scarring in the lungs, doctors refer to it as Connective Tissue Disease-Associated Interstitial Lung Disease (CTD-ILD).

Learning that your rheumatoid arthritis (RA) or autoimmune disease could affect your lungs can be frightening. However, having an autoimmune condition does not guarantee you will develop severe lung disease, and early assessment can help guide your care.

How Do Autoimmune Diseases Affect the Lungs?

The term interstitial refers to the supporting tissue and space around the delicate air sacs in your lungs. When your immune system targets this area, it triggers persistent inflammation ^[2].

This condition can involve two main processes:

• Inflammation: Active swelling and immune cell activity in the lungs. With proper treatment, this inflammation can sometimes improve.
• Fibrosis (Scarring): If chronic inflammation injures the air sacs, your body may produce excess collagen to repair it, leading to thick, stiff scar tissue ^[3]. This scarring is permanent and makes it harder for your lungs to expand and transfer oxygen into your bloodstream.

It is important to know that CTD-ILD is not just another word for permanent scarring; the disease can be mainly inflammatory, mainly fibrotic, or a mix of both. Your lung condition could remain stable, improve with treatment, or progress, depending on your specific disease and other individual factors ^[4].

Which Autoimmune Conditions Are Linked to ILD?

Several autoimmune diseases can cause CTD-ILD, but they interact with the lungs differently:

• Rheumatoid Arthritis (RA): It is common for RA to affect the lungs, sometimes even before joint symptoms appear ^[5]. While between 20% and 60% of people with RA may have subtle lung abnormalities on a scan, not all of these become clinically significant or progress to severe scarring ^[6]. When significant scarring does occur, it often follows a pattern called Usual Interstitial Pneumonia (UIP) ^[6]. Factors that increase your risk include smoking, older age, poorly controlled joint disease, and having high levels of certain RA antibodies ^[7].
• Scleroderma (Systemic Sclerosis): This condition frequently involves the lungs ^[1]. Interstitial lung disease affects roughly 47% of people with scleroderma and is driven by a mix of immune system activity and blood vessel damage ^[8][9]. The most common pattern of lung involvement in scleroderma is Nonspecific Interstitial Pneumonia (NSIP) ^[10].
• Lupus (Systemic Lupus Erythematosus): Lupus tends to cause active inflammation—such as pleuritis (inflammation of the lining around the lungs), pleural effusion (fluid around the lungs), or pneumonitis (inflamed lung tissue)—rather than severe chronic scarring ^[11]. Only a small percentage of people with lupus develop fibrotic lung disease compared to those with scleroderma ^[9].
• Other Conditions: Sjögren’s disease, mixed connective-tissue disease, and inflammatory muscle diseases (myositis) can also cause CTD-ILD ^[1].

Note: Autoimmune diseases can also cause other lung issues besides ILD, such as airway disease, medication-related lung injury, or pulmonary hypertension.

What Symptoms Should I Watch For?

Early on, you might not have any symptoms. As the condition develops, you may notice:

• Shortness of breath, especially during exercise or exertion
• A persistent, dry cough
• Unexplained fatigue or a reduced ability to exercise

When to seek immediate care: Contact a doctor urgently if you experience sudden or rapidly worsening breathlessness, severe chest pain, coughing up blood, blue lips, or fainting.

How is CTD-ILD Evaluated and Monitored?

If your doctor suspects lung involvement, or to monitor an existing diagnosis, they may use several tests:

• Pulmonary Function Tests (PFTs): Breathing tests that measure how much air your lungs can hold and how well they transfer oxygen (a measurement called DLCO) ^[12].
• High-Resolution CT (HRCT) Scan: A detailed chest X-ray that creates cross-sectional images of your lungs to look for inflammation or scarring ^[13].

Your care team will determine your testing schedule based on your symptoms, risk factors, and whether your condition is stable or changing.

How is CTD-ILD Treated?

Treatment is highly individualized. It depends on your specific autoimmune disease, the pattern of lung involvement on your CT scan, the severity of your symptoms, and whether your lung function is declining. Never start, stop, or change your RA or autoimmune medications without speaking to your doctor, as this requires careful coordination.

• Observation: If your ILD is mild, stable, and not causing symptoms, your doctor might recommend regular monitoring without adding new lung medications.
• Immunosuppressants: If active inflammation is driving your lung disease, your doctor might prescribe medications that quiet the immune system, such as mycophenolate or rituximab ^[14]. These may help stabilize your lung function, but they require careful monitoring for side effects, including an increased risk of infection ^[15].
• Antifibrotic Medications: If your lung scarring continues to worsen (a condition called progressive pulmonary fibrosis), your doctor might prescribe an antifibrotic drug like nintedanib ^[16]. These medications do not reverse existing scars, but they can help slow down the decline in lung function ^[17]. They can be used alone or sometimes in combination with immunosuppressants, and require monitoring for side effects like diarrhea or liver issues ^[18].
• Supportive Care and Lifestyle:
  • Smoking Cessation: Quitting smoking and avoiding inhaled dust or fumes are critical steps to protect your lungs ^[7].
  • Pulmonary Rehabilitation: Structured exercise and education programs that help improve your breathing and exercise tolerance ^[19].
  • Vaccinations: Staying up-to-date on vaccines (like influenza and pneumonia) helps prevent respiratory infections ^[20].
  • Supplemental Oxygen: If testing shows your blood oxygen levels are low, your doctor may prescribe oxygen therapy ^[21].
  • Managing Acid Reflux: If you experience acid reflux, treating it can help prevent stomach acid from reaching your lungs and worsening your condition ^[21].

Because everyone’s condition is different, your care should ideally involve a collaborative, multidisciplinary team, including a rheumatologist (to manage the autoimmune disease) and a pulmonologist (to manage the lung disease) ^[17].