The Effects of Obesity, Weight Loss, and Weight Gain on Thymic Expression of FGF21

Thymic involution is a key concern in an increasingly obese and an increasingly old population due to its role in the immune system. FGF21 signaling has been identified as one key element in the alterations to the thymic microenvironment that are seen with obesity and age, which both increase thymic involution. Research has been quickly growing on this topic, and this study adds a characterization of weight change to the knowledge of transcriptional regulation of these signaling molecules. Since FGF21 has been identified as a strong protective factor against the degradation and loss of the thymic epithelial layer, it is of particular interest. A mouse model of obesity, weight loss, and weight gain using dietary modulation was used to study this interaction. It was hypothesized that FGF21 would be relatively expressed the most in the obese group, followed by the weight gain group, weight loss, and lean in descending order. It was also hypothesized that the relative expression of -Klotho and FGFR1 would follow this trend similarly. A statistically significant p-value for the difference in relative expression of FGF21 between the experimental groups (p = 0.0190) was found. The difference between groups was not significant for FGFR1 (p = 0.8549) or -Klotho (p = 0.07180). The FGF21 multiple comparisons revealed significant differences between lean versus weight gain (p = 0.0161) and lean versus obese (p = 0.0107). The FGFR1 multiple comparisons showed no significant differences between any of the groups. The -Klotho multiple comparisons reveals a statistically significant difference between the obese and weight loss groups (p = 0.0142). These findings demonstrate a potential role for FGF21 signaling in obesity-induced immune dysfunction.Bachelor of Science in Public Healt