Lessons from allergic rhinitis versus asthma pathogenesis and treatment

The clinical overlap of allergic rhinitis and asthma has led to the proposal that the two entities share common pathogenic mechanisms, especially T-cell-dependent, IgE-mediated airway inflammation. The inflammation has been ascribed to an imbalance in the response of T-helper cells, such that T helper type 2 (T(H)2) products predominate over T(H)1 cytokine production in both diseases. This scheme, however, does not fully explain the primary roles of the epithelial barrier or respiratory viruses in the development of acute and chronic pathophysiology of these upper and lower airway diseases. This article reviews the pathogenesis of allergic rhinitis, focusing on the role of the antigen-presenting cell and the consequent downstream events. A new scheme, called the Epi-Vir-All paradigm, is presented that more fully addresses the roles of the airway epithelium, respiratory viruses, and allergy in inflammatory air-way disease.