Combined Exercise and Diet Induce Airway Hyperreactivity While Reducing Liver Steatosis in Mice with Diet-Induced Obesity

Background: Obesity is a multi-organ system disease, which is associated with, e.g., a higher prevalence of non-alcoholic fatty liver disease (NAFLD) and asthma. Little is known regarding the effect of obesity-related parameters (including liver integrity) and the respiratory phenotype after a combination of physical activity and diet. Methods: Thirty-two C57BL/6 mice were, after 27 weeks of a high fat diet (HFD), randomly assigned to two dietary interventions for three weeks: a HFD or a normal chow diet (NCD). In both dietary groups, half of the animals were subjected to a sub-maximal exercise protocol. Lung function, lung inflammation, liver histology, and metabolic profile were determined. Results: Mice with obesity did not show airway hyperreactivity after methacholine provocation. Sub-maximal exercise with diet (NCD/E) induced a significant reduction in forced expiratory volume in 0.1 s after methacholine provocation. NCD/E had significantly more neutrophils and inflammation (IFN-γ, TNF-α, IL-4, and IL-17F) in bronchoalveolar lavage compared to non-exercising mice on a HFD (HFD/NE). However, more epithelial injury (serum surfactant protein D and IL-33) was seen in HFD/NE. Additionally, hepatic steatosis and fibrosis were reduced by combined diet and sub-maximal exercise. Conclusions: Combining sub-maximal exercise with diet induced airway hyperreactivity and pulmonary inflammation, while body weight, hepatic steatosis, and fibrosis improved.