House Dust Mite Allergy and Associated Allergen-Specific Immunotherapy in Allergic Asthma

There is an increasing trend in the global prevalence, morbidity, and economic burden associated with asthma in recent decades [1]. The Global Strategy for Asthma Management and Prevention Report [2] defined asthma as a chronic inflammatory disorder of the airways in which many cells and cellular elements are involved. Both host factors (primarily genetic) and environmental factors (primarily allergen exposure) are considered to contribute to the development and expression of asthma [3]. Pharmacologic treatment to achieve and maintain asthma control is the main treatment for the management of most asthmatic patients today. However, some measures that identify risk factors and further reduce exposure to these risk factors are also crucial to improve asthma control and reduce medication use. Recent research revealed that asthma is more likely a heterogenous disease in view of clinical manifestations or pathophysiologic mechanisms, and asthma phenotypes or endotypes are evolving to classify subgroups of asthmatic patients [4,5]. The biologically-targeted treatment could benefit specific groups of asthmatic patients on the basis of asthmatic classifications and understanding of pathophysiological mechanisms. Allergic asthma, one important subtype of asthma endotypes, is characterized by a hypersensitivity to airborne allergen and Th2 cell-mediated airway inflammation [4]. The house dust mite (HDM) is considered an important airborne allergen associated with asthma attack in the domestic environment [2]. Further, although allergen-specific immunotherapy (ASIT) has been developed to treat patients with allergic disease for many decades, the role of ASIT in allergic asthma has not been clearly identified. The aim of this review is thus to discuss the risk factor of HDM allergy on allergic asthma, potential strategy of HDM-specific immunotherapy and underlying mechanism, and both experimental and clinical studies of HDM-specific immunotherapy for allergic asthma. Data source and study selections