Eating disorders: a role for dipeptidyl peptidase IV in nutritional control

Dipeptidyl peptidase IV (DPP IV), a serine protease with broad tissue distribution and known activity in serum, has been postulated to modulate nutrition control by modification or inactivation of peptide hormones operating in the enteroinsular axis. We hypothesized that changes of DPP IV activity in serum are related to the nutrition status of patients with eating disorders. Serum DPP IV activity was measured in 52 patients (28 with anorexia nervosa and 24 with bulimia nervosa) in four consecutive weekly analyses. Simultaneously, the number of CD26 (DPP IV)-positive peripheral blood lymphocytes was counted. The same analyses were carried out in 28 healthy female volunteers. In week 1 and throughout the observation period, DPP IV activity in the sera of patients with anorexia nervosa and, to a lesser extent, those with bulimia nervosa was elevated in comparison to that of healthy controls (week 1: means = 92.8 U/L for anorexia-nervosa patients and 89.3 U/L for bulimia-nervosa patients versus 74.7 U/L for healthy control subjects, P = 0.014; weeks 1-4: 91.8 U/L for anorexia-nervosa patients and 86.2 U/L for bulimia-nervosa patients versus 77.6 U/L for healthy controls, P < 0.001). We assume that the increase in DPP IV serum activity will increase the turnover of distinct peptide hormones with known effects on nutrition control and susceptibility to degradation by DPP IV. The potential impact of an increase in DPP IV activity in serum on satiety and nutrition control contributes to previously reported implications for immune function.