Arginine‐Supplemented Diet Decreases Expression of Inflammatory Cytokines and Improves Survival in Burned Rats

Background: We examined whether the expression of inflammatory cytokines in organs was influenced by the enteral diet supplemented with arginine in burned rats. Methods: Male Wistar rats weighing about 200 g underwent catheter jejunostomy and received scald burns covering 30% of the whole‐body surface area. Animals were divided into two groups: a control group (no supplemental arginine, n = 12) and an arginine group (supplemental arginine: 7.7 g/L, n = 10), which continuously received total enteral nutrition for 7 days (250 kcal/kg/d, 1.72 gN/kg/d). The following were measured after the experiment: (1) messenger RNA (mRNA) expression of tumor necrosis factor‐alpha (TNF‐α), interferon‐gamma (IFN‐γ), interleukin‐1beta (IL‐1β), and IL‐6 in the spleen, thymus, lung, and liver by a semiquantitative reverse transcription‐polymerase chain reaction method, (2) inflammatory cytokines in the plasma and supernatant of cultured splenic lymphocytes by enzyme‐linked immunosorbant assay, (3) nitric oxide (NO) product, NO2 −/NO3 −, in the plasma and supernatant of cultured splenic lymphocytes by the Griess method, and (4) survival rate by the Kaplan‐Meier method. Results: The mRNA expression of TNF‐α was significantly decreased in the spleen and lung (p <.01, p <.05), IFN‐γ in the lung (p <.05), IL‐1β in the spleen (p <.05), and IL‐6 in the thymus and liver (p <.05, p <.05) in the arginine group when compared with the control group. The production of TNF‐α by splenic lymphocytes was suppressed in the arginine group in both concanavalin A (Con A)‐treated and ‐untreated cultures (p <.01, p <.05). The production of IFN‐γ by splenic lymphocytes treated with Con A was suppressed in the arginine group (p <.05). The NO product in the supernatant without Con A was increased in the arginine group (p <.05). The mortality rate of the arginine group (0%) was lower than that in the control group (33.3%) on day 7 after the burn injury (p <.05). Conclusions: The data suggest that dietary arginine supplementation decreases the mRNA expression of inflammatory cytokines in organs and improves the survival rate after thermal injury. (Journal of Parenteral and Enteral Nutrition 24:89–96, 2000)