This week in class, we talked about how infectious diseases are important not only due to the fact that they cause disease, but also because they worsen the symptoms of existing health conditions. Asthma is a prime example of a disease affected by viruses because symptoms of it worsen with respiratory infections, the majority of which are caused by rhinoviruses. After seeing this recently published research article, I thought it connected really well to Dr. Siegel’s statement during the Tuesday lecture that many exacerbations of diseases and subsequent deaths are due to secondary effects of infections. The study titled "Rhinovirus-induced IL-25 in asthma exacerbation drives type 2 immunity and allergic pulmonary inflammation,” published by researchers in the Imperial College of London, found the process with which Rhinoviruses are responsible for worsening of asthma symptoms and contributing to asthma attacks.
What did they find? They found that Rhinovirus infected individuals with asthma had cells with increased expression of IL25, a small molecule that plays an active role in asthma pathogenesis and triggers a chain of events that leads to an asthma attack. What effects do high levels of IL-25 expression in cells have on individuals? They cause increased T and non-T type 2 cellular responses. An important response is increased type 2 cytokine production, which amplifies the pathogenesis of asthma.
Why are these findings important? Besides demonstrating how Rhinoviruses play a major role in the worsening of asthma symptoms, they introduce a new possibility of treatment. Since IL-25 is expressed highly in cells of individuals with asthma and rhinoviruses, blocking IL-25 can result in amelioration of symptoms by suppressing inflammation. This research gives validation to therapies of asthma that block IL-25 and/or inhibit T and non-T type 2 cellular responses.