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Nutritional Immunology

Increased Glucose Availability Activates Chicken Thymocyte Metabolism and Survival¹

Department of Animal and Avian Sciences, University of Maryland College Park, MD 20742

^* To whom correspondence should be addressed. E-mail: bdhumphr{at}calpoly.edu.

Glucose metabolism in mammalian thymocytes is coupled to their development and selection in the thymus. In chickens, thymocytes develop in a low glucose concentration in ovo and a high glucose concentration posthatch. To determine the effect of glucose concentration on thymocyte glucose metabolism, embryonic thymic lobes were cultured in media containing varying glucose concentrations and thymocytes were isolated for analysis. Glucose transporter-1 (Glut-1) and Glut-3 mRNA abundance was at least 2-fold higher in thymocytes incubated with 10 and 20 mmol/L glucose than in those incubated with 0 mmol/L glucose (P < 0.05) and glucose uptake was greatest in thymocytes incubated with 20 mmol/L glucose (P < 0.05). Thymocytes incubated with 0 and 20 mmol/L glucose had 185% greater hexokinase activity than in those incubated with 10 mmol/L glucose (P < 0.05). Consequently, thymocyte glucose utilization was dependent upon glucose availability. Increased glucose utilization resulted in a higher mitochondrial membrane potential in thymocytes incubated with 15 mmol/L glucose than in those incubated with 5 mmol/L glucose (P < 0.05), indicating enhanced thymocyte energy status in response to high glucose concentrations. Additionally, thymocyte viability was lower in thymocytes incubated with 5 mmol/L glucose than in those incubated with 10 and 15 mmol/L glucose (P < 0.05) and rates of thymocyte apoptosis were higher in thymocytes incubated with 5 mmol/L glucose than in those incubated with 15 mmol/L glucose (P < 0.05). Glucose availability induced metabolic changes in thymocytes that altered their energy status and survival. Consequently, these data indicate that glucose availability may influence the development of naïve T cells in the chicken thymus.