Therapeutic response to asthma medications: genotype predictors

Pharmacogenomics of beta2-agonist: key focus on signaling pathways

Asthma is one of the most common respiratory diseases, where inhalation and exhalation are obstructed due to narrowing of the airways by broncho-constriction or by inflammation. Among all the available anti-asthma therapies, beta2-agonists are the most effective bronchodilators available, and give rapid relief of asthma symptoms. Evidence suggests that the degree of beta2-agonist response varies greatly between patients and genetic factors have a major role in it. Despite several studies on the beta2-agonist pharmacogenetics, significant gaps in knowledge still remain and need to be resolved before the pharmacotyping of beta2-agonist responsiveness comes to clinical practice. As we know, beta2-agonists show their influence by targeting beta2-adrenergic receptors, leading to the activation of beta2-adrenergic receptors and its downstream cascade. Signaling through beta2-adrenergic receptors mediates numerous airway functions by regulating broncho-constriction and dilation pathways. Therefore, it is an important prerequisite to understand these pathways, which will assist in defining the variability in therapeutic responses for beta2-agonists. Owing to the complexity of the action of a beta2-agonist and its therapeutic response, a broader genomics approach will help in optimizing therapy for the individual patient. This might be achieved by considering and focusing on receptor/s at which the drug binds directly, signal transduction cascades or downstream proteins and proteins involved in the relaxation and constriction of the airway smooth muscle. Considering that a drug response may involve a large number of proteins, it seems unlikely that a single polymorphism or haplotype in a single gene would explain a high degree of drug response variability in a consistent fashion. Thus, it shows that a polygenic approach will be more appropriate. In order to follow this, the mode of action of the beta2-agonist and its downstream signaling cascade should essentially be assessed to resolve the beta2-agonist enigma.

Genetic aspects of the etiology and treatment of asthma

This article provides a clinical review of the genetic aspects of the etiology and treatment of asthma for pediatric practitioners who are experienced in asthma diagnosis and management but lack expertise in genetics and immunology. Asthma is caused by the interaction of genetic susceptibility with environmental factors. The asthmatic response is characterized by elevated production of IgE, cytokines, and chemokines; mucus hypersecretion; airway obstruction; eosinophilia; and enhanced airway hyperreactivity to spasmogens. The genes most clearly associated with asthma include disintegrin and metalloprotease ADAM-33, dipeptidyl peptidase 10, PHD finger protein 11, and the prostanoid DP1 receptor. Within a few years, practitioners may apply sophisticated knowledge of cell and molecular biology to expand pharmacotherapeutic approaches and to personalize diagnosis and management.