Introduction to Asthma and Phenotyping

Abstract

Asthma is an inflammatory disorder characterized by airway obstruction, airway hyperresponsiveness, and airway inflammation, all of which are variable among patients and variable in time within any specific patient. Understanding the mechanism that underlies this observed variability, and using that understanding to advance the science of asthma and the care of asthmatic patients, is an essential purpose of developing phenotypes. Clinical phenotypes have been used for decades, but overlap each other, and do not map cleanly to either pathophysiologic mechanism or with therapeutic response. Molecular phenotyping, although as yet only partially developed, offers the promise of dissecting the mechanistic underpinnings of the variability of asthma and of providing predictive therapeutics for the benefit of patients with this common and troubling disease.

Phenotypes in obstructive sleep apnea: A definition, examples and evolution of approaches

“…The aims of phenotyping include improving understanding of disease mechanisms, predicting response to therapy, risk for adverse events and reducing heterogeneity in clinical trials [16]. …”

“…Several of the patient phenotypes in asthma and COPD have been overlapping, not always reproducible, changed over time, and have not consistently pointed to greater mechanistic understanding or treatments [16, 22]. This may be due to disparate populations studied, lack of relevant features used for phenotyping, or a situation in which clinical phenotypes alone may not capture relevant biology.…”

“…Phenotyping strategies can be grouped by features (e.g., clinical vs. molecular) and by experimental approaches (e.g., supervised vs. unsupervised) (Table 1) [16]. Clinical phenotyping focuses on identifying unique patient categories based on measures such as signs, symptoms, demographics, comorbidities, physiological and anatomic measures, or treatment responsiveness.…”

“… See references [16, 26-29] for details on methodology. OSA – obstructive sleep apnea, REM – rapid eye movement. …”

The Complex Type 2 Endotype in Allergy and Asthma: From Laboratory to Bedside

“…At first, phenotypes describing clinical and morphologic characteristics as well as unique responses to treatment have been developed to address the complexities of the disease. Phenotypes may be clinically relevant in terms of presentation, triggers, and treatment response, but do not necessarily relate to or give insights into the underlying pathological mechanism [4]. For most of the allergic diseases, extended heterogeneous disease-related metabolic, inflammatory, immunological, and remodeling pathways have been described, and a reproducible underlying mechanism is defined as a disease endotype [5•, 6•].…”