Resveratrol inhibits the deleterious effects of diet-induced obesity on thymic function.

Obesity is associated with an increased risk of infectious diseases. It has been shown to have deleterious effects on cell-mediated immunity, including reducing thymocyte numbers and altering responses of thymocytes to pathogens. In the current study, we examined the efficacy of the antiobesity phytochemical resveratrol in preventing the deleterious effects of a high-fat diet on thymic anatomy and function. Compared to C57Bl/6 male mice fed a low-fat diet, mice on a high-fat diet had a significant increase in thymic weight and lipid content, and a disrupted anatomy, including a reduction of the medullary compartment and absence of a corticomedullary junction. There were a decrease in thymic cellularity and mature T-cell output, and a disrupted T-cell maturation, as evidenced by increased double-negative and decreased single- and double-positive thymocytes. Mice that had been fed resveratrol along with a high-fat diet had a dose-dependent reversal in all these parameters. Western blots from thymi showed that obese mice had lower levels of the key stimulators of lipid metabolism, phospho-5' adenosine monophosphate-activated protein kinase and its downstream target, carnitine palmitoyl transferase-1; this was restored to normal levels in resveratrol-fed mice. Resveratrol also reversed an increase in glycerol-3-phosphate acyltransferase-1, the enzyme that catalyzes the first step in triglycerol synthesis. Taken together, these results indicate that resveratrol is a potent inhibitor of the deleterious effects of diet-induced obesity on thymic anatomy and function, and this may hold promise in preventing obesity-related deficits in cell-mediated immunity.