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 ìfibrosis.î 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: http://www.nhlbi.nih.gov/health/health-topics/topics/ipf/
or http://www.ipfnet.org
This article was published in the Winter 2008 issue of the
ALA Lung Health Magazine. |