Circadian Rhythm Affects the Dynamics of S-IgA Mucosal Secretion

Abstract

Today, many people prefer the simplicity of eating at fast-food restaurants. The prevalence of overweight and obesity thus seems likely to continue to rise in coming decades, and recent evidence has demonstrated that obesity is associated with cancer, infectious diseases, and metabolic syndrome. We hypothesized that obesity induces mechanical changes in the digestive and circulatory organs, which may in turn disrupt homeostasis. This study investigated systemic and local impacts of diet-induced obesity on the immune system, including the mucosal tissues. Mice were administered a high-fat diet (HFD) or normal diet (ND) for 3 weeks, after which plasma and fecal extracts were collected at 6-h intervals. A significant reduction in plasma immunoglobulin (Ig)G and increase in fecal secretory (S-) S-IgA concentrations were observed in HFD-fed mice. In addition, corticosterone levels were significantly higher in the plasma of mice fed HFD when compared with those fed ND, indicating that daily intake of high-fat foods causes physiological stress. Taken together, these results suggest that regular consumption of high-fat foods may negatively impact both systemic and mucosal immune responses.