THE EFFECT OF DIETARY-PROTEIN SUPPLEMENTATION ON INSULIN-LIKE GROWTH-FACTORS (IGFS) AND IGF-BINDING PROTEINS IN CHILDREN WITH SHIGELLOSIS

Nutrient deficiency causes growth failure and decreases serum insulin- like growth factor-I (IGF-I) concentrations. Because IGFBPs modulate t he concentrations and availability of IGFs in serum, IGF-binding prote ins (IGFBPs) were measured along with IGF-I and IGF-II before and afte r 21 days of refeeding in 22 undernourished Bangladeshi children (2-4 yr of age) with shigellosis. The effects of a 150 Cal/kg day diet with a normal protein (6%; n = 10) or high protein (15%; n = 12) content w ere studied. The results were compared with those of 25 age-matched he althy American children (controls). Body weight gain was better in pat ients receiving the high protein diet than in those receiving the norm al protein diet. In both groups, initial IGF-I (32 +/- 6 and 24 +/- 7 ng/mL; mean +/- SD) and IGF-II (117 +/- 15, 174 +/- 45 ng/mL) concentr ations were low compared to controls (100 +/- 12 and 542 +/- 29 ng/mL, respectively; P<0.007). After refeeding, IGF-I increased to 160 +/- 2 6 ng/mL on the normal protein diet and to 322 +/- 41 ng/mL on the high protein diet, exceeding values in controls (P < 0.007). IGF-II increa sed mole than 2-fold on each diet (P < 0.007), reaching control values . IGFBP-2 concentrations before refeeding were twice those in controls (750 +/- 200 vs. 317 +/- 33 ng/mL; P < 0.007) and normalized after re feeding in the high protein group (288 +/- 32 ng/mL; P = NS), but rema ined elevated in the normal protein group (526 +/- 77 ng/mL; P < 0.007 ). IGFBP-3 levels before refeeding were low and returned to normal on each diet. IGFBP-3 proteolytic activity in serum was initially increas ed and declined on the high protein diet. In conclusion, protein conte nt in the refeeding diet differentially affects IGFs and IGFBPs in you ng undernourished children with infection. IGF-I and IGFBP-2 seem to b e particularly sensitive to dietary protein alterations. We speculate that an increase in IGF-I concentrations, normalization of IGFBP level s, and a decrease in IGFBP-3 proteolytic activity in serum may all be involved in the improved recovery and catch-up growth observed with th e high protein diet.