CCL13 and asthma: Airway epithelial cells can be activated by cytokines (IL-1β, IFN-γ,TNF-α, etc.)or PAMPS (Pathogen-related molecular patterns) via the TLRs-NF-κb pathway and releases CCL13, which recruits eosinophils and promotes the polarization of M2 macrophages to mediate the progression of asthma (2, 24, 25).