Lung Disease

Breathing is usually an unconscious act. In humans and other higher animals, cellular respiration is dependent on a complex system that involves many steps between the outside air and the internal environment of the cell. Defects or disease can occur at any step along this pathway, making the number of lung diseases substantial.

While it can affect children as well, lung disease is a major cause of disability in middle age and early retirement. Some forms of lung disease include asthma, chronic bronchitis, emphysema, cystic fibrosis, cancer, acute infectious pneumonia and infant respiratory distress syndrome, the most common cause of death in babies less than a month old. Asthma alone afflicts over 1.5 million Canadians and 8 million Americans, while chronic bronchitis and emphysema cripple more than 10 million North Americans. In Canada, more than twelve thousand people under the age of 18 are hospitalized annually due to severe asthma. Many health disorders related to environmental factors, such as exposure to bacteria, cigarette smoke and industrial pollutants, are lung diseases as well.

The cause of emphysema, a painful and debilitating disease, is still unknown; and research into its origins and prevention continues today, using animal models. Victims of this disease have lungs full of holes where tissue has been destroyed by an enzyme called neutrophil elastase. Studies of emphysema in rabbits and horses (the only species besides humans to develop emphysema spontaneously) are revealing the natural stages of development of this disease and hold the promise of methods to prevent it. Researchers are also exploring the possibility of gene therapy for emphysema patients.

Continued research is needed to find improved asthma therapies and perhaps a cure. Dogs and monkeys in particular are helping researchers to devise new ways of controlling asthma, as well as to determine why certain chemicals provoke asthma attacks. Researchers have identified two genes in mice that may play important roles in causing asthma.

Over the years, a great deal of research has focused on the mechanical properties of the lung. With the complexity of lung function and the vast number of diseases of the lung, biomedical research has come a long way in advancing medical knowledge about this essential body organ. With the continued use of animals and adjunct methodologies such as cell culture and computer modeling, further progress is expected to see bold new therapies and perhaps even cures for lung disease.