When Asthma Is Not Just Asthma: Type 2 Inflammation
By Gary Fitzgerald
Asthma was once considered a single, though complex, disease. Now it’s recognized as a spectrum of diseases, with genetic and environmental factors playing a role in airway inflammation and hyperreactivity that causes 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 – which is diagnosed when symptoms are not well controlled by high-dose inhaled controller medications or when two or more asthma flares in a 12-month span require oral corticosteroids.
Recent medical breakthroughs involving severe asthma are transforming how its treated. Airway inflammation is a particular focus.
As many as 50-70 percent of asthma patients have a form of asthma characterized by Type 2 inflammation – a type of systemic allergic response that can result in increased asthma exacerbations and decreased lung function. Research has discovered that cytokines, which are secreted proteins that signal the body’s cells and begin an immune response, are major contributors to the progression of Type 2 inflammation.
In addition, common asthma biomarkers – eosinophils (white blood cells involved in airway inflammation), Immunoglobulin E (IgE, the chemical associated with allergies) and fractional exhaled nitric oxide (FeNO, chemicals in the breath produced by cells in an inflammatory response) – are present.
In recent years, scientists have developed medications – called biologics – that target the cells and pathways that link inflammation to asthma. Some target eosinophils and IgE while others target cytokines, specifically interleukin-4 (IL-4), IL-5 and IL-13. It’s often called precision medicine because it’s developed for particular types of the disease.
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.
In addition to asthma, 80 percent of atopic dermatitis patients and 50 percent of patients diagnosed with nasal polyps also have Type 2 inflammation.
Other conditions believed to be impacted by Type 2 are chronic rhinosinusitis, aspirin-exacerbated respiratory disease (AERD), gastroesophageal reflux disease (GERD) and sleep apnea.
If you have asthma that is persistent and difficult to control with medication, talk with your doctor about Type 2 inflammation and whether stepping up medications is right for you.
Patients with allergic asthma may want to consider allergen immunotherapy, which can reduce the underlying trigger of asthma and decrease the severity of symptoms over time.