Inflammation in Asthma: Mechanistic Insights and the Role of Biologics in Therapeutic Frontiers

Abstract

Asthma is a chronic and multifaceted respiratory condition that affects over 300 million individuals across the globe. It is characterized by persistent inflammation of the airways, which leads to episodes of wheezing, breathlessness, chest tightness, and coughing. The most prevalent form of asthma is classified as Type 2 or T2-high asthma. In this variant, the immune response is heavily driven by eosinophils, mast cells, and T-helper 2 (Th2) cells. These components release a cascade of cytokines, including interleukin-4 (IL-4), interleukin-5 (IL-5), and interleukin-13 (IL-13). This release promotes several processes: the production of immunoglobulin E (IgE), which is integral to allergic responses; the recruitment of eosinophils-white blood cells that contribute to inflammation and tissue damage. Conversely, non-Type 2 or T2-low asthma is typically associated with a different inflammatory profile characterized by neutrophilic inflammation. This type of asthma is driven by T-helper 1 (Th1) and T-helper 17 (Th17) immune responses, which are often present in older adults, smokers, and those suffering from more severe manifestations of the disease. Among asthmatic patients, approximately 80-85% of cases are classified as T2-high asthma, while only 15-20% are T2-low asthma. Treatment of asthma focuses heavily on controlling inflammation. Inhaled corticosteroids remain the cornerstone therapy for managing T2-high asthma. For more severe or treatment-resistant cases, biologic therapies targeting specific inflammatory pathways, such as anti-IgE (omalizumab), anti-IL-5 (mepolizumab, benralizumab), and anti-IL-4/IL-13 (dupilumab), have shown great promise. For T2-low asthma, macrolide antibiotics like azithromycin and other novel therapies are being explored. This article reviews the safety, efficacy, and indications of the currently approved biologics and discusses potential novel biologics for asthma.

Keywords: asthma; biological therapy; biologics; monoclonal antibody; type 1 inflammation; type 2 inflammation.

Figure 1

A schematic of asthma endotypes, associated inflammation, and their treatments.