Mechanistic insights from human studies of asthma

Obesity is a risk factor for the development of asthma that worsens severity and control in those with existing asthma. Many intersecting mechanisms may underlie the obesity-asthma relationship: alterations in pulmonary physiology secondary to the mechanical load of truncal fat; environmental exposures; metabolic effects including insulin resistance and dyslipidemia; immunomodulatory and inflammatory effects of obesity including altered adipokine profiles; oxidative stress; the microbiome; and genetic and epigenetic changes within molecules involved in metabolic regulation. These different factors may be variably present in any one individual. In this chapter, we will summarize what is known about the mechanisms causing asthma in obesity, how this might explain different phenotypes, and why it sometimes differs between children and adults.