Effect Of IL-6/TNF-α On Acute Lung Injury Induced By Acute Kidney Injury Of Ischemic-reperfusion Injury Model In Mice

ObjectiveTo investigate the role of IL-6(interleukin-6) and TNF-α(tumor necrosis factor-α)on acute lung injury induced by acute kidney injury, and clarify the part mechanismof the acute kidney injury causing the acute lung injury.Methods1. A total of76male mice (C57BL/6J) were used. Mice were randomly distributedin three groups: control group (C), sham group (S) and ischemia-reperfusiongroup (IR), and the S group and the IR group based reperfusion time were dividedinto nine sub-groups respectively:0h,3h,6h,12h,24h,48h,72h,5d and7d,eventually forming in total of19groups. Using occlusion of bilateral renal pediclefor30min, a mouse model of ischemia-reperfusion induced renal injury wasestablished. In addition, keeping free bilateral renal pedicle instead of clampingrenal pedicle, sham-operated model was created. Moreover, the levels of serumcreatinine (Scr) and blood urea nitrogen (BUN) were determined by automaticbiochemical analyzer; pathological damage degree in renal and lung tissue wereanalyzed by scoring method.2. A total of36male mice (C57BL/6J) were used. Mice were randomly distributedin three groups: control group (C), sham group (S) and ischemia-reperfusiongroup (IR), and the S group and the IR group based reperfusion time were dividedinto four sub-groups respectively:6h,24h,48h and5d, eventually forming in totalof9groups. Then, immunohistochemical technique was taken to identify theprotein expression levels of IL-6and TNF-αin the lung tissue. RT-PCR methodwas taken to detect the mRNA expression levels of IL-6and TNF-αin lung tissue. Results1. The levels of Scr and BUN in each groups(1) No significant difference was found in sub-groups of the C group and the Sgroup of the levels of Scr and BUN (P>0.05).(2) The Scr and BUN levels began to rise in mice of IR group when reperfusionof3h; with the time of reperfusion, the Scr and BUN levels were gradually increased,and the Scr and BUN levels are at peak when reperfusion of24h;the Scr and BUNlevels were gradually decreased when more time of reperfusion, but IR group wassignificantly higher (P <0.05)than the C group and S group when reperfusion of7d.2. Pathological damage score of the renal in mice of each group(1) No significantly differences were observed in sub-groups of C group and Sgroup(P>0.05).(2)In IR0h group, slightly pathological renal damage was observed. As thereperfusion time going, renal injury was gradually increased, and renal injury was themost serious in IR24h group. The renal injury was gradually induced in IR48h group.The renal injury degree of IR7d group was remaining higher than C group and Sgroup(p<0.05).3. Pathological damage score of the lung in mice of each group(1) No significantly differences were observed in sub-groups of C group and Sgroup(P>0.05).(2)In IR6h group, slightly pathological lung damage was observed. As thereperfusion time going, lung injury was gradually increased, and the lung injury wasat the peak in IR48h group. The lung injury was gradually induced in IR72h group.The lung injury degree of IR7d group was returned to baseline levels.4. Protein expression levels of IL-6and TNF-αin the lung tissue(1) Protein expression levels of IL-6in the lung tissue: the expression of IL-6was located in the cytoplasm of the lung cell. No significant differences of IL-6expression were observed in sub-groups of C group and S group (P>0.05).In IR6hgroup, obviously increase was detected, and as the reperfusion time going, IL-6expression level was gradually increased, and was at the peak in the IR48h group,returned to baseline level in IR5d group.(2) Protein expression levels of TNF-α in the lung tissue: No significantdifferences of TNF-αexpression were observed in sub-groups of C group and S group (P>0.05).The TNF-αexpression level began to increase in IR6h group. With thereperfusion time going, TNF-αexpression level was gradually increased, and in theIR48h group was at the peak, and in IR5d group returned to baseline level.5. mRNA expression levels of IL-6and TNF-αin the lung tissue(1) mRNA expression levels of IL-6in the lung tissue: No significant differencesof IL-6mRNA expression were observed in sub-groups of C group and S group (P>0.05).In IR6h group, the IL-6mRNA expression was markedly increased, and was atthe peak in the IR48h group, returned to baseline level in IR5d group.(2) mRNA expression levels of TNF-αin the lung tissue: No significantdifferences of TNF-αmRNA expression were observed in sub-groups of C group andS group (P>0.05).In IR6h group, the IL-6mRNA expression was significantlyincreased, and was at the peak in the IR48h group, returned to baseline level in IR5dgroup.Conclusions1. In the mice model of ischemia-reperfusion renal injury, the acute lung injury andacute renal injury are closely related in time and space. This model is one of theperfect animal model for research of acute kidney injury induced lung injury.2. In the mice model of ischemia-reperfusion renal injury, the expression of IL-6andTNF-α are closely related to the degree of the lung injury, suggesting that IL-6andTNF-α is the evil factor for acute lung injury in mice model of ischemia-reperfusionrenal injury.