Effects of total parenteral nutrition on immune function and inflammatory response in young rats

Objectives To investigate the effects of total parenteral nutrition (TPN) on immune function and systemic inflammation in young rats. Methods Eighteen young male SD rats aged 6 to 8 weeks were randomly divided into 3 groups: normal group, control group and TPN group, with 6 rats in each group. The rats in the normal group were not catheterized, and those in the control group were treated with normal saline after right jugular vein catheterization. The rats in the control group and normal group were fed standard food and water, and those in the TPN group were treated with TPN after right jugular vein catheterization, fasting and water abdication. All the young rats were sacrificed in 14 d later. The blood routine of peripheral blood was detected by automatic flow cytometry. The expression of HLA-DR in spleen cells, the proportion of Treg cells in peripheral blood, the ability of endotoxin-induced monocytes to produce TNF-α, apoptosis of lymphocytes (CD4+, CD8+ T cells) and the ability of IFN-γ production after stimulation by phytohemagglutinin (PHA) were detected by flow cytometry. The levels of IL-1β, TNF-α, IL-10 and IL-4 in peripheral blood plasma were determined by ELISA. Results Compared with normal group and control group, the number of venous blood lymphocytes was decreased (P < 0.05), the HLA-DR expression level in spleen cells was reduced (P < 0.05), the proportion of Treg cells in peripheral blood was significantly higher in the TPN group (8.54±1.20) than that in the normal group (3.02±1.49) and the control group (3.00±0.75) (P < 0.05). The proportion of TNF-α induced by endotoxin was significantly lower in the TPN group (8.73±3.11) than the normal group (39.07±16.17) and control group (43.23±18.40). The percentage of IFN-γ produced by CD4+T lymphocytes stimulated by PHA was significantly lower in the TPN group (0.65±0.46) than the normal group (2.94±1.62) and the control group (2.97±1.39), and the difference was statistically significant (P < 0.05). The TPN group had increased apoptosis of lymphocytes (CD4+ CD8+ T cells) at late stage (P < 0.05), increased IL-1β and TNF-α levels (P < 0.05) while decreased IL-10 and IL-4 levels (P < 0.05). Conclusion TPN sustained for 2 weeks can lead to congenital and acquired immune impairment and increase of pro-inflammatory factors in young mice. Early initiation of enteral nutrition is of great significance to reduce immune injury and systemic inflammation