Cytokine responses in very low birth weight infants receiving glutamine-enriched enteral nutrition

OBJECTIVE: Very low birth weight (VLBW) infants receiving glutamine-enriched enteral nutrition may present with a lower infection rate, which may result from enhanced antimicrobial innate or Th1 cytokine responses. We investigated whether glutamine-enriched enteral nutrition in VLBW infants increased these cytokine responses following in vitro stimulation of whole blood cells.

METHODS: In a double-blind, placebo-controlled, randomized controlled trial, VLBW infants (gestational age <32 weeks and/or birth weight <1500 g) received enteral glutamine supplementation (0.3 g x kg(-1) x day(-1)) or isonitrogenous placebo supplementation (alanine) between days 3 and 30 of life. Cytokine responses following in vitro whole blood cell stimulation with anti-(alpha)CD3/alphaCD28 or lipopolysaccharide were analyzed by cytometric bead array at 3 time points: before the start of the study, at day 7 of life, and at day 14 of life.

RESULTS: Baseline patient and nutritional characteristics were not different between groups. At least 2 blood samples were analyzed in 25 of 52 (48%) and 38 of 50 (76%) infants in the glutamine-supplemented and control groups, respectively. Glutamine-enriched enteral nutrition was not associated with significant alterations in cytokine responses (interferon-gamma, tumor necrosis factor-alpha, interleukin [IL]-2, IL-4, IL-5, and IL-10) of peripheral blood cells upon stimulation with either anti-alphaCD3/alphaCD28 or lipopolysaccharide.

CONCLUSIONS: We hypothesize that glutamine-enriched enteral nutrition decreases the infection rate in VLBW infants by influencing the mucosal and not the systemic immune system.