“Asthma is a chronic disease without a cure,” said Reynold Panettieri, MD, the Robert L. Mayock and David A. Cooper Professor of Medicine in the Pulmonary, Allergy and Critical Care division and chief of the Asthma Section in Penn’s Perelman School of Medicine. But new fungal research from him and his colleagues are giving scientists more information about the causes of asthma and possible new treatments.
Most of us know one of the more than 250 million people living with the disease, which is characterized by a chest tightness, cough and wheeze that can be intermittent or severe and can leave patients with constant difficulty breathing.
Normal lungs receive air from the trachea or windpipe into the bronchi, the main braches that lead to a network of tubular structures that divide and spread air throughout the lungs. The bronchi end in the alveoli, where the oxygen is absorbed into the blood and carbon dioxide picked up and exhaled, an essential waste product of the body’s metabolization of oxygen.
In 60 percent of asthma sufferers, the smooth muscle that lines bronchi becomes inflamed as a result of the presence of allergens, like pollen or pet dander, that gather and aggravate the airways causing them to narrow and impinging on a person’s ability to take deep breaths and blow out air. Forty percent of cases are not allergy sensitive; however, structural cells in the airways play an important role in evoking asthma.
Panettieri and colleagues at Penn and the National Institute of Allergy and Infectious Diseases recently discovered that an allergen from a common fungus can trigger the airway sensitivity characteristic of asthma.
The fungus, Aspergillus fumigatus, was found to incite an increased response in the smooth muscle of the airway, as well as the many cells that band together to help the bronchi function normally. They found that one strain of A. fumigatus, specifically, sets off a chain of events that leads to the tightening of the airway and increased production of mucus.
These results were observed in both humans and mice and detected at the highest levels in the smooth muscle of people with asthma, particularly those who reported a known sensitivity to A. fumigatus. In contrast, muscle tissue from healthy volunteers had little presence of the allergen.
The standard treatment for asthma has been to remove the person from the allergen causing the reaction, which is not always possible in situations where the allergen is in the air or surrounding atmosphere. Clinicians can also treat the disease with an inhaled steroid to block the inflammation.
But, Panettieri says, “this is a breakthrough in the treatment of chronic asthma, as the presence of this allergen in the airway smooth muscle or mucus could serve as a marker for fungal-associated asthma and lead to the development of new drugs that block the action of it, resulting in new treatments for asthma sufferers.