Whole-body protein metabolism assessed by leucine and glutamine kinetics in adult patients with active celiac disease

Abstract 

To assess the effect of increased renewal of intestinal epithelial cells on leucine and glutamine (Gln) turnover, 4-hour intravenous infusions of l-[1-¹³C]leucine and l-[2-¹⁵N]Gln were administered to five adult patients with active celiac disease in the postabsorptive state. There was a 35% increase in leucine flux (micromoles per kilogram per hour) in patients (117 ± 17) compared with healthy controls (96 ± 11, P < .03). Gln flux was increased by 13% in patients (377 ± 35) versus controls (335 ± 16, P < .04). These results suggest that active celiac disease, characterized by villous atrophy and crypt cell hyperplasia, is associated with a dramatic increase in whole-body protein breakdown as assessed by ¹³C-leucine, which may contribute per se to the protein malnutrition status of the patients. The increase in Gln utilization as assessed by l-[2-¹⁵N]Gln was moderate, but may have been offset due to the villose atrophy and ensuing reduced intestinal epithelial cell mass. The results are consistent with the concept that increased renewal of intestinal epithelial cells represents a sizable fraction of whole-body protein turnover and that Gln is an important fuel for epithelial intestinal cells in vivo.

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