DIFFERENTIAL EXPRESSION OF INTESTINAL AND SPLENIC CYTOKINES AFTER PARENTERAL-NUTRITION

Objective: To determine the effect of parenteral nutrition (PN) on the expression of message for inflammatory cytokines in the spleen and di fferent segments of the intestine. Design: Randomized controlled trial . Interventions: All rats underwent central venous cannulation and wer e randomized to two groups. Group 1 (n = 6) received saline solution i nfusion and chow ad libitum; group 2 (n = 5) received lipid-free PN wi th no oral feeding. After 7 days, the animals were killed and the sple ens and segments of small and large intestine were removed. Main Outco me Measures: The expression of message for tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and IL-1 in the spleen and intesti ne was determined using a semiquantitative reverse transcription polym erase reaction. Splenic macrophages were isolated and cultured for 24 hours with and without lipopolysaccharide. Production of TNF-alpha and IL-6 was determined by bioassay followed by enzyme-linked immunosorbe nt assay. Results: After 7 days of infusion, messenger RNA (mRNA) expr ession for TNF-alpha, IL-1, and IL-6 was increased in the jejunum (P < .05), and TNF-alpha mRNA and IL-6 mRNA expression was decreased in th e spleen (P < .01) of PN-fed animals when compared with saline/chow co ntrols. In addition, TNF-alpha mRNA expression was increased in the ce cum (P < .05), IL-1 mRNA expression was increased in the ileum (P < .0 5), and IL-6 mRNA expression was increased in the cecum (P < .05) and Peyer's patches (P < .007) in the PN-fed animals. Production of TNF-a and IL-6 by splenic macrophages was decreased following PN infusion in both lipopolysaccharide-treated and untreated cultures (P < .05). Con clusions: Infusion of lipid-free PN induces a differential mRNA expres sion for inflammatory cytokines in the spleen and intestine with an ov erall up-regulation of the expression of inflammatory cytokines in the intestine and a down-regulation in the spleen. These data provide evi dence that the regulatory mechanisms for cytokine production are diffe rent in the intestine and the spleen. Further study is needed to elabo rate the mechanism of this differential expression following lipid-fre e PN infusion.