Heterogeneity and the origins of asthma

Abstract

Objective: To examine the roots of asthma across different ages, including atopy, the role of the microbiome and viral infections, and comorbidities and confounders, such as obesity, aspirin-exacerbated respiratory disease, neutrophilic asthma, cigarette smoking, and the possibility of an asthma-chronic obstructive pulmonary disease overlap syndrome.

Data sources: Data were taken from various scientific search engines, including PubMed and Science Direct databases.

Study selections: Articles that reviewed information on the origins of asthma in persons of all ages, including different phenotypes and genotypes of asthma, were used.

Results: Asthma is a common and complex disease whose origins are likely a combination of both genetic predisposition and environmental exposures. Factors such as the microbiome, other atopic disease, viral infections in young children, and other diagnoses, such as obesity or aspirin-exacerbated respiratory disease, are important to consider when creating a treatment plan for patients.

Conclusion: Asthma is a disease that is often diagnosed in childhood but can present at any age. There is debate in the field as to whether asthma is one disease or several different diseases that include airway inflammation as a key finding. There are risk factors for disease in the environment and through comorbidities that likely play significant roles in the origins of asthma, the development of symptoms, and the response to treatment. These factors are even more important as we look toward the future with the goal of personalized medicine.

Figure 1.. Phenotypic origins of asthma in children and adults.

Specific phenotypes of asthma are more often associated with childhood onset of disease, while others are more commonly found in adults. The various phenotypic origins of asthma are depicted as individual circles with potential representative mechanisms (i.e., Virus, Th2 high, AERD, Occupational, Obesity, Neutrophilic, and ACOS). The bottom line indicates the age at which each of these phenotypes are most predominant. See text for details. ACOS = Asthma-COPD Overlap Syndrome; COX = cyclooxygenase 1; IFN = interferon; IL = interleukin; TNF = tumor necrosis factor. T cells are shown as blue circles, B cells are yellow circles, plasmacytoid dendritic cells are pink circles, eosinophils are pink circles with red inclusions, neutrophils are blue circles with polymorphic nuclei, macrophages are orange, adipocytes are dark green, and exposure to cigarette smoke is indicated by a cigarette.