To determine the effect of parenteral nutrition (PN) on the expression of message for inflammatory cytokines in the spleen and different segments of the intestine.
Randomized controlled trial.
Eleven adult male Sprague-Dawley rats weighing 250 to 300 g.
All rats underwent central venous cannulation and were randomized to two groups. Group 1 (n=6) received saline solution infusion and chow ad libitum; group 2 (n=5) received lipid-free PN with no oral feeding. After 7 days, the animals were killed and the spleens and segments of small and large intestine were removed.
Main Outcome Measures:
The expression of message for tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and IL-1 in the spleen and intestine was determined using a semiquantitative reverse transcription polymerase reaction. Splenic macrophages were isolated and cultured for 24 hours with and without lipopolysaccharide. Production of TNFα and IL-6 was determined by bioassay followed by enzyme-linked immunosorbent assay.
After 7 days of infusion, messenger RNA (mRNA) expression for TNF-α IL-1 and IL-6 was increased in the jejunum (P<.05), and TNF-α mRNA and IL-6 mRNA expression was decreased in the spleen (P<.01) of PN-fed animals when compared with saline/chow controls. In addition, TNF-α mRNA expression was increased in the cecum (P<.05), IL-1 mRNA expression was increased in the ileum (P<.05), 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-α and IL-6 by splenic macrophages was decreased following PN infusion in both lipopolysaccharide-treated and untreated cultures (P<.05).
Infusion of lipid-free PN induces a differential mRNA expression for inflammatory cytokines in the spleen and intestine with an overall up-regulation of the expression of inflammatory cytokines in the intestine and a down-regulation in the spleen. These data provide evidence that the regulatory mechanisms for cytokine production are different in the intestine and the spleen. Further study is needed to elaborate the mechanism of this differential expression following lipid-free PN infusion.(Arch Surg. 1995;130:1301-1308)