By Gary Fitzgerald
Asthma was once considered a single, though complex, disease. Now it’s recognized as a spectrum of diseases. Genetic and environmental factors play a role in airway inflammation and hyper-reactivity. This leads to common asthma symptoms: coughing, wheezing and shortness of breath.
Severe asthma is one form of the disease. It’s estimated that 5-10 percent of people with asthma have severe asthma.
Severe asthma is the diagnosis when…
- symptoms are not well-controlled by high-dose inhaled controller medications
- the patient experiences two or more asthma flares in a 12-month span requiring oral corticosteroids
Recent medical breakthroughs involving severe asthma are transforming how its diagnosed and treated. Airway inflammation is a particular focus.
What is Type 2 inflammation in asthma?
As many as 50-70 percent of asthma patients have a form of asthma characterized by Type 2 inflammation. Type 2 inflammation is a type of systemic allergic response that can result in increased asthma exacerbations and decreased lung function.
Cytokines, which are proteins that signal the body’s cells and begin an immune response, are major contributors to Type 2 inflammation.
Common asthma biomarkers are also present in Type 2 inflammation. These include:
- eosinophils (white blood cells involved in airway inflammation)
- Immunoglobulin E (IgE, the chemical associated with allergies)
- fractional exhaled nitric oxide (FeNO, chemicals in the breath produced by cells in an inflammatory response)
When there are too many eosinophils in the blood, there is an increased risk of severe asthma flares. Learn more about eosinophilic asthma at eosasthma.org.
Genetics also appear to play a role in Type 2. Studies show that if one or both parents have Type 2 inflammation related to asthma, their child is four times more likely to have asthma or an allergic disease.
What severe asthma treatments are available?
In recent years, scientists developed medications called biologics to target the cells and pathways that link inflammation to asthma. Biologics are often called “precision medicine” because they are for particular types of a disease.Some biologics target eosinophils and IgE while others target cytokines, such as interleukin-4 (IL-4), IL-5 and IL-13.
If you have asthma that is persistent and difficult to control despite medication, talk with your doctor about Type 2 inflammation. You may want to ask whether stepping up medications is right for you.
Patients with allergic asthma may want to consider allergen immunotherapy. Allergen immunotherapy can reduce the underlying trigger of asthma and decrease the severity of symptoms over time.
Other conditions that involve Type 2 inflammation include: