Changes and significance of IL-6 in lung tissue of elderly rats model of multiple organ dysfunction syndrome

Objective To study the change and significance of interleukin-6(IL-6) in lung tissue of elderly rats model of multiple organ dysfunction syndrome(MODS).Methods MODS models in the elderly(20 months old) and in the young rats(3 months old) were established by injection of oleic acid(OA) at the dose of 0.25 ml/kg and lipopolysaccharide(LPS) at dose of 3.5mg/kg into SD rats(4 h interval).They were randomly divided into four groups respectively: control group and three model groups(n=10 for each group).The changes of pathomorphology and function in the lung,heart,liver and kidney were observed.The IL-6 contents in plasma and in the lung,heart,liver,and kidney were determined by enzyme linked immunosorbent assay(ELISA).Semi-quantitative RT-PCR was used to measure mRNA expression of IL-6 mRNA in lung,heart,liver and kidney tissues.Results After OA and LPS injection,the lung impairment appeared firstly and PaO2 decreased to minimum at 2 h.Biochemical indexes of functional lesion of the heart,liver and kidney increased to the peak level at 6h.Organs injured more seriously in elderly group than young group at the same time points.The expression of IL-6 mRNA and the concentration of IL-6 in different tissues increased significantly 2 h after LPS injection.Among them,lung tissue was most evidently increased.The expression of IL-6 mRNA in different tissues was higher in elderly group than in young group at the same time points.Conclusion IL-6 level and its mRNA expression evidently rise at early time in lung tissues of elderly rats after OA and LPS injection,which may explain the reasons that the lung injured firstly and more seriously in elderly rats with MODS.