Eosinophil-mediated inflammatory pathway

The eosinophil-mediated inflammatory pathway is a biological process central to the development of Type 2 (T2) inflammatory conditions, including severe asthma, eosinophilic esophagitis, and hypereosinophilic syndrome (HES) (NIH, 2024; JCI, 2024). This pathway involves the coordinated action of cytokines, chemokines, and adhesion molecules that regulate the maturation, recruitment, and activation of eosinophils (NIH, 2024). Key drivers include interleukin-5 (IL-5), which is essential for eosinophil differentiation and survival, and chemokines like eotaxins that signal through the CCR3 receptor to direct cell migration (NIH, 2024; JCI, 2024). Once recruited to tissues, eosinophils undergo degranulation, releasing cytotoxic proteins such as major basic protein (MBP) and eosinophil cationic protein (ECP) that cause local tissue damage (NIH, 2024). Therapeutic strategies targeting this pathway include monoclonal antibodies that neutralize IL-5 (e.g., mepolizumab) or block the IL-5 receptor (e.g., benralizumab) to deplete eosinophil populations (JCI, 2024). Other approaches target upstream signaling via IL-4/IL-13 or TSLP, or induce eosinophil apoptosis through Siglec-8 agonism (NIH, 2024). Clinical management of these therapies often relies on biomarkers like blood eosinophil counts and fractional exhaled nitric oxide (FeNO) to identify responsive patient populations (ERS, 2012). While effective, long-term suppression of this pathway may pose risks such as reduced host defense against helminthic parasites (NIH, 2024).

Other names

Eosinophilic inflammationEosinophilic airway inflammationType 2 eosinophilic inflammationEosinophil activation pathway

The mechanism of action for drugs targeting this pathway involves the neutralization of key Type 2 cytokines (IL-5, IL-4, IL-13) or their receptors (IL-5Rα, IL-4Rα) to inhibit eosinophil maturation, recruitment, and survival (NIH, 2024; JCI, 2024). Some agents, such as benralizumab, utilize antibody-dependent cell-mediated cytotoxicity (ADCC) to directly deplete eosinophils, while others like leralimab act as Siglec-8 agonists to induce eosinophil apoptosis (NIH, 2024). Upstream inhibition of TSLP also reduces the activation of the entire eosinophilic cascade (JCI, 2024).