This article describes research showing that most if not all asthma is autoimmune in origin with natural killer cells the intrinsic cause.
Asthma is a chronic disease that affects the airways of the lungs. The airways are the vessels such as bronchioles and alveoli that carry air in and out of the lungs. In asthma, the inner walls of these airways become inflamed or swollen. Consequently the vessels become narrower and airflow is restricted.
Symptoms of Asthma
Symptoms of asthma include wheezing, coughing, chest tightness, and difficulty breathing, especially at night and in the early morning. Symptoms vary in severity and they vary over time, with heightened episodes of symptoms called asthma attacks. Untreated, asthma attacks can be fatal.
The Autoimmune Connection
For many years it's been known that asthma has several different causes including allergies, environmental triggers such as wood smoke and cigarette smoke, aspirin sensitivity, damage from respiratory infections, and autoimmunity.
Autoimmune or atopic asthmas has traditionally been associated with rheumatic symptoms, cold sensitivity, and Raynaud’s phenomena whereas aspirin-induced asthma may be associated with nasal polyps. Asthma has also been known to be commonly associated with rheumatoid arthritis, Crohn's disease and other autoimmune conditions.
However, according to current research all incidences of asthma are autoimmune in origin.
According to this theory, allergies and other environmental triggers induce asthma in people who are genetically predisposed. At one time, it was thought that helper T cells contributed to autoimmune asthma. New studies suggest that the true culprits are natural killer cells that have gone awry.
Harvard researchers Dale Umetsu and Omid Akbari discovered that lymphocytes known as natural killer (NK) cells are responsible for the process that leads to asthma. In the normal immune response to pollen and other environmental agents our immune system launches a series of events to protect. In asthma, these immune system cells misidentify harmless pollens, dust and dander, initiating an exaggerated reaction in which natural killer cells destroy attack the airway vessels. The consequences include breathlessness, wheezing, tissue damage, and, in the worst cases, death.
Natural Killer Cells in Autoimmune Diseases
Recent studies show that NK cells contribute to a number of autoimmune conditions including autoimmune infertility, Crohn’s disease, and rheumatoid arthritis, and other conditions that often accompany asthma. Current research is underway to determine how NK cells travel from the bloodstream and lodge in tissue during the immune response.
How this Finding Affects Treatment
From this viewpoint, it’s understandable why many patients with asthma fail to respond to corticosteroid therapy. Corticosteroids have little effect on natural killer cells. With further research into the role of NK cells in asthma, newer and more effective treatments can be identified.
Resources:
What is Asthma? National Heart, Blood and Lung Institute, Department of Health and Human Services, May 2006, accessed July 10, 2007.
William Cromie, Researchers Uncover Cause of Asthma, Harvard News Office, March 2006.
