The interstitium, which is lung tissue that surrounds and supports the airways and blood vessels within the lungs, is highly susceptible to environmental substances as well as viral and bacterial attacks. Interstitial lung diseases result from scarring of the interstitium, causing irreversible lung damage and a compromised respiratory system. Some disorders, such as cystic fibrosis and sarcoidosis, affect not only lung tissue but also many other body systems, including the liver, spleen, pancreas and nervous system.
Cystic Fibrosis
Cystic fibrosis causes mucus-secreting cells throughout the body to produce abnormally thick and sticky secretions. In a person's lungs, the thick mucus plugs up small airways, setting the stage for chronic infection and inflammation. Usually the cilia -- the fine hairs that line the airways -- sweep mucus secretions back up the airways to the trachea and carry away any bacteria or debris in the lungs. In people with cystic fibrosis, the secretions are so thick that the cilia cannot move them. The normal defense mechanisms in the lungs cannot clear away bacteria, and infections develop easily, permanently scarring the lungs.
Sarcoidosis
According to the American Lung Association, sarcoidosis may affect all parts of the body, but it affects the lungs and lymph glands in 90 percent of all people with the disease. People most often experience mild early symptoms affecting the lungs, but the disease may develop rapidly. Generalized symptoms of fatigue, loss of appetite and fever accompany respiratory symptoms. Other people gradually develop respiratory symptoms and usually do not experience fever and fatigue.
Hypersensitivity Pneumonitis
This disorder develops in individuals who have an unusually high sensitivity to a particular substance. Repeated exposure can cause weight loss, weakness, emphysema and lung fibrosis or scarring. According to the University of Maryland Medical Center, farm grains have proven to cause these hyper-responsive reactions. Fungal spores released from moldy hay often cause this disorder. Malt workers' lung is another hypersensitivity disorder, caused by fungal contaminants contained in barley. Certain chemicals may also cause hypersensitivity pneumonitis.
