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目的过氧化物酶体增殖物激活受体γ(peroxisome proliferator-activated receptor gamma,PPARγ)是一类由配体激活的核转录因子,参与调节多种炎症介质的释放,但PPARγ是否参与调节放射性肺炎尚不清楚。本实验研究PPARγ激动剂吡格列酮(pioglitazone,PIO)对放射性肺炎的预防作用,并探讨其机制。方法将BALB/c小鼠80只随机分为正常对照组、单纯照射组、PIO治疗组及照射+PIO治疗组4组,每组20只。X射线全胸单次照射15Gy建立小鼠放射性肺炎模型,PPARγ激动剂PIO 20mg/(kg·d)于照射前1周开始灌服,1次/d,每周称体质量调整1次给药剂量,共8周。分别于照射前、照射后1、4和8周处死小鼠5只,摘取全肺,称湿重,计算肺指数;行肺脏组织学HE染色观察肺组织学变化,ELISA法检测小鼠血清中转化生长因子β1(transforming growth factor beta 1,TGF-β1)、白介素6(interleukin 6,IL-6)和肿瘤坏死因子α(tumor necrosis factor-alpha,TNF-α)在各组小鼠血清中的变化。结果各组小鼠无一例死亡。资料经Kolmogorov-Smirnov检验符合正态分布,方差齐。单纯照射组小鼠肺指数最高,F=35.82,P<0.001;照射组小鼠肺指数显著高于对照组和PIO组,均P<0.001;照射+PIO组小鼠肺指数显著低于单纯照射组,P<0.001。不同时间点各组小鼠肺指数差异无统计学意义,F=1.30,P=0.282。照射后肺组织发生广泛炎症改变,小血管和毛细血管扩张、充血,肺间隔和肺泡腔充斥大量水肿液体,使肺泡间隔增厚,肺泡腔减小。肺泡腔以及增厚的肺间质中充斥大量炎性细胞成分,包括巨噬细胞、中性粒细胞、淋巴细胞和红细胞等,表现为充血、水肿和渗出。PIO组则减轻了照射诱发的肺组织充血、水肿和渗出。单纯照射组小鼠TGF-β1、IL-6及TNF-α水平均高于其他3组,差异均有统计学意义,F值分别为128.80、79.18和135.51,均P<0.001。对照组和PIO组小鼠血清TGF-β1、IL-6及TNF-α水平差异均无统计学意义,P=1.000;照射组小鼠血清TGF-β1、IL-6及TNF-α水平均显著高于对照组和PIO组(均P<0.001),照射+PIO组小鼠血清TGF-β1、IL-6及TNF-α水平均显著低于单纯照射组(均P<0.001)。照射后4周血清TGF-β1(F=20.62,P<0.001)、IL-6(F=8.15,P=0.001)及TNF-α(F=5.96,P=0.005)水平最高,均显著高于照射后1周。但血清TGF-β1与照射后8周相比差异无统计学意义,P=0.460。血清TGF-β1、IL-6及TNF-α水平处理组与照射后时间之间无交互效应。血清中TGF-β1(r=0.486,P=0.021)、IL-6(r=0.525,P<0.001)和TNF-α(r=0.573,P=0.005)水平与肺指数呈显著正相关。结论 PPARγ激动剂PIO能减轻小鼠放射性肺炎,其作用与可能与调节TGF-β1、IL-6和TNF-α的表达水平有关。
Objective Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated nuclear transcription factor involved in regulating the release of a variety of inflammatory mediators. However, whether PPARγ is involved in the regulation of radiation pneumonitis still not clear. This experiment study PPARγ agonist pioglitazone (PIO) on the prevention of radiation pneumonia, and explore the mechanism. Methods Eighty BALB / c mice were randomly divided into normal control group, irradiation group, PIO treatment group and irradiation + PIO treatment group (n = 20). X-ray full-chest irradiation 15Gy mouse model of radiation pneumonitis, PPARγ agonist PIO 20mg / (kg · d) 1 week before irradiation began to be fed, 1 times / d, weekly body mass adjustment once administration Dose for a total of 8 weeks. Five mice were sacrificed at 1, 4 and 8 weeks after irradiation, respectively. Whole lungs were taken out and wet weights were calculated to calculate lung index. Lung histology was observed by HE staining, and the serum levels of mouse serum The expressions of transforming growth factor β1 (TGF-β1), interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF-α) The change. Results None of the mice in each group died. Data by Kolmogorov-Smirnov test consistent with the normal distribution, the variance of homogeneous. The lung index of the mice in the irradiation group was the highest, F = 35.82, P <0.001. The index of the lung of the mice in the irradiation group was significantly higher than that in the control group and the PIO group (P <0.001) Group, P <0.001. There was no significant difference in lung index between groups at different time points, F = 1.30, P = 0.282. A wide range of inflammatory changes occurred in the lung tissue after irradiation, small blood vessels and capillaries dilated, congestion, pulmonary septum and alveolar fluid filled with a large number of edema, alveolar septum thickening, alveolar reduction. Alveolar cavity and thickening of the lung interstitium filled with a large number of inflammatory cell components, including macrophages, neutrophils, lymphocytes and red blood cells, showed congestion, edema and exudation. PIO group reduced radiation-induced lung congestion, edema and exudation. The levels of TGF-β1, IL-6 and TNF-α in the mice in the simple irradiation group were all higher than those in the other three groups, the differences were statistically significant, the F values were 128.80, 79.18 and 135.51 respectively, all P <0.001. The serum levels of TGF-β1, IL-6 and TNF-α in the control group and the PIO group were not significantly different (P = 1.000). The levels of serum TGF-β1, IL-6 and TNF- The levels of serum TGF-β1, IL-6 and TNF-α in the irradiated + PIO group were significantly lower than those in the control group and the PIO group (all P <0.001). The highest level of serum TGF-β1 (F = 20.62, P <0.001), IL-6 (F = 8.15, P = 0.001) and TNF-α 1 week after irradiation. However, there was no significant difference between the serum TGF-β1 and the 8th week after irradiation (P = 0.460). Serum TGF-β1, IL-6 and TNF-α levels of treatment group and no interaction between the time after irradiation. Serum levels of TGF-β1 (r = 0.486, P = 0.021), IL-6 (r = 0.525, P <0.001) and TNF- α (r = 0.573, P = 0.005) were positively correlated with lung index. Conclusion PPARγ agonist PIO can attenuate radiation pneumonitis in mice, which may be related to the regulation of the expression of TGF-β1, IL-6 and TNF-α.