Of note, this review highlights that complex functional changes in airways coexist with the complex inflammatory processes, and the potential synergistic use of C3a and C5a inhibition may subdue airway inflammation and prevent subepithelial fibrosis by blocking the intrapulmonary activation of C3a and C5a, is a potential clinical approach for treating patients with asthma. The gene discussed is C5; the disease is asthma.