Interstitial Lung Disease (ILD)

Interstitial lung disease (ILD) is a group of disorders related to the scarring of the interstitium of the lungs. Interstitium refers to the tissues around air sacs (alveoli) and contains blood and lymphatic capillaries. It is also known as diffuse parenchymal lung disease (DPLD). ILD is thought to result from an exaggerated repair response to lung injuries. An excess of healing occurs, resulting in the fibrosis of the lung interstitium and thus impairment of the function of the capillaries in their exchange of gases that takes place across their walls. Patients are breathless, complain of cough, and tend to lose weight over time. 

Environmental toxins tend to initiate a cascade of healing reactions in genetically susceptible people. ILD comprises a huge group of disorders with multiple causes. Some of them are described below;

Idiopathic: In several cases, no cause has been identified.

Other autoimmune disorders: ILD may occur in people suffering from other autoimmune diseases like scleroderma, rheumatoid arthritis, lupus, and sarcoidosis.

Occupational exposure: People working in industries with harmful chemicals often develop ILD. For instance, people working with coal dust, asbestos, silica, radiation, or bird droppings.  

Genetic ILD: Sometimes, ILD runs in families and is inherited from the parents to the offspring. Examples include neurofibromatosis and Gaucher disease.

Medications: Some medications result in ILD as their adverse effects, such as methotrexate, cyclophosphamide, amiodarone, and Nitrofurantoin.

ILD group of disorders are relatively less common in the USA. According to a survey, it affects 30 people per 100,000 population per year. It is more prevalent in males. 

People having the following factors have shown an increased susceptibility to the illness;

·         Adults are more likely to be affected by ILD than children.

·         People exposed to environmental toxins at their workplaces like mining, construction, and farming, are at increased risk.

·         People having some other autoimmune diseases like Systemic Lupus Erythematosus (SLE), Rheumatoid Arthritis (RA), etc.

·         People who smoke cigarettes.

·         People who had radiation or chemotherapy for cancer treatment.

Some of the symptoms related to the disorder are;

·         Breathlessness

·         Coughing (nonproductive)

·         Tiredness

·         Weight loss

·         Decreased stamina

If you or your loved one feels difficulty breathing and coughing, it is essential to consult your healthcare provider.

History and physical examination: The doctor will take medical history by asking questions related to your symptoms, current, and past medical illnesses, family history, occupational history, etc. he will perform a thorough physical examination with a particular focus on lungs and breathing.

Pulmonary function tests: These tests are used to check for the function of the lungs and include a number of tests, the most common is spirometry. Others include pulse oximetry, six-minute walk test, diffusing capacity, and measurement of lung volumes.

Chest X-ray: It can show abnormal patterns in ILD like nodular or reticular opacities. It can also provide typical evidence that is specific to some diseases like hilar lymphadenopathy in sarcoidosis.

A high-resolution CT Scan: A high-resolution CT scan gives a more clearer and detailed picture and can be very helpful in diagnosis. The honey-combing appearance of the lungs on a CT scan occurs in late-stage ILD.

Arterial blood gases: This test measures the level of oxygen and carbon dioxide in your blood, which determines the function of the lungs.

Blood tests: Some blood tests can be performed to discover other autoimmune disorders, like rheumatoid factor, anti-CCP antibodies, Ds DNA, etc.

Bronchoscopy: It is a procedure in which a flexible thin tube with a camera is inserted in your windpipe to visualize the condition of the lining, foreign body, tumor, etc.

Lung biopsy: A biopsy is a process that removes a sample of aberrant cells from the body. Your surgeon can do a biopsy in a variety of ways, mostly bronchoscopy, which involves passing a lighted catheter down your neck and then into the lungs to check abnormal parts of your lungs. A sample of tissue can be taken to study in the lab during this process. 

Once the fibrosis is done, it is irreversible. The treatment is then directed to slow the progression of the disease and improve the symptoms. The choice of treatment modalities depends on the type and severity of ILD and includes;

Finding and avoiding the causing factor: If the agent causing the fibrosis gets identified, it is important to avoid its exposure. For example, quitting smoking, stopping work in the environment causing ILD, cessation of medicines, etc.

Medications: Medicines are used to reduce inflammation and improve the function of the lungs. They include steroids, mycophenolate, azathioprine, leflunomide, rituximab, and tacrolimus. Some medicines help in exalting progressive fibrosis, e.g., pirfenidone and nintedanib.

Oxygen therapy: Some people may need supplemental oxygen provided by nasal cannulas.

Pulmonary rehabilitation: Some people may be benefitted from breathing exercises and increased physical activity.

Lung transplant: Severe cases may need a lung transplant to survive. 

ILD is a chronic debilitating disease. If not diagnosed and treated early can lead to severe morbidity and mortality. However, with the use of current medicines, the course of the disease can be slowed down.

The natural course of ILD varies among different diseases and individuals with the same diagnosis. Some conditions start slowly but progress consistently, while some begin acutely and may respond well to therapy. 

For some types, like idiopathic, there is nothing that could be done to prevent it. But for some other types, especially the occupational one, measures can be taken to prevent ILD.

·         Quit smoking

·         Try to stay away from second-hand smoke and chemicals

·         Take a healthy balanced diet

·         Perform regular exercises

·         Wear a face mask when going to work in case of jobs requiring chemical exposure.

·         Get vaccinated for influenza and pneumonia vaccines.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on May 23, 2023.

References

Interstitial Lung Disease | American Lung Association

https://www.lung.org/lung-health-diseases/lung-disease-lookup/interstitial-lung-disease

Management of interstitial lung disease (ILD) in myositis syndromes: A practical guide for clinicians - ScienceDirect

https://www.sciencedirect.com/science/article/pii/S1521694222000286