Effects of obesity on asthma: immunometabolic links

Asthma is a widespread chronic inflammatory disease, which has a highly heterogeneous etiopathogenesis, with predominance of either T-helper cell type 2 (Th2; type 2) or non-Th2 (non-type 2) mechanisms. Together with cardiovascular or autoimmune diseases, obesity, and others, asthma belongs to so called noncommunicable diseases, a group of disorders with immunometabolic links as underlying mechanisms. So far, obesity and asthma have been considered mostly independently, but there are clear signs of relevant interactions. First, obese patients are at increased risk of asthma or asthma-like symptoms. Second, asthma accompanied by obesity is more severe and more difficult to treat. A specific phenotype called obesity-associated asthma has been also described, which is late-onset, rather severe, non-type 2-driven disease, present mostly in women. In addition, obesity can coincide with asthma also in children, and, although obesity generally skews the Th1/Th2 balance towards Th1, it can also accompany type 2-driven asthma. However, those combinations represent less precisely defined disease entities. Despite a substantial increase in our knowledge on the mechanisms mediating the effects of obesity on the development of asthma in several recent years, still much needs to be done, especially on the molecular level.