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Pulmonary Fibrosis
Herbert Y. Reynolds, M.D., Dorothy B. Gail, Ph.D., James P. Kiley, Ph.D.

Diffuse Interstitial Lung Diseases (ILD's) comprise a varied group of pulmonary illnesses that result in fibrosis of lung tissue. Characteristic is discrete areas in the air exchange part of the lung being irritated or becoming inflamed, which causes a cellular reaction that heals and contracts down like a scar, termed fibrosis. Idiopathic pulmonary fibrosis (IPF) is the most frequently recognized ILD with a prevalence of about 200,000 cases in the US . Unfortunately, the precise cause of IPF remains unknown.

The lung tissue reaction in IPF causes similar symptoms in affected patients including: shortness of breath, a dry cough, and decreased physical exertion related to low lung function (documented by forced vital capacity, six minute walking distance, and low blood oxygen saturation). The onset of symptoms can be imperceptible at first, slowly incremental, and exist for a couple of years before requiring medical attention. Chest films, CT chest scan, pulmonary function tests, blood studies, and perhaps a lung tissue biopsy will usually give a diagnosis and provide staging of the illness. Treatment options are many, although most are not curative nor produce dramatic improvement.

The Division of Lung Diseases, NHLBI supports a combination of basic science research on experimental models of lung fibrosis and on human lung fibrosis tissue aimed towards discovering mechanisms that cause IPF, and clinical research to assess therapy for patients. Basic research projects are elucidating the fibrosis reaction at several points: Are fibrocytes that circulate in the blood attracted into lung tissue to become fibroblasts, or do fibroblasts already there proliferate? Do fibroblasts change into myofibroblasts that secrete substances like transforming growth factor, which stimulate the tissue reaction? Are cellular mechanisms that should make inflammatory cells die off defective, thus causing the reaction to smolder and cause fibrosis? The search for new drugs that inhibit these reactions could yield future therapeutic agents. A new IPF Clinical Research Network was established in 2005 to assess drug treatments. The first study is evaluating the effectiveness of Sildenafil on patients with late stage IPF who have pulmonary hypertension. A second trial will evaluate commonly prescribed medications for treating IPF, prednisone, azathioprine, and N-acetylcysteine, compared against placebo for patients in an early stage of the disease.

If you believe that you, a family member, or an acquaintance might have IPF, we would suggest that you consult appropriate physicians to obtain the best care and most probable diagnosis; learn and understand all you can about the illness; remain physically active; obtain nutritional advice; watch for depression symptoms; and work with your physicians on a treatment plan.

For more information about IPF see: or

This article was published in the Winter 2008 issue of the ALA Lung Health Magazine.

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