CXCL12/CXCR4在高氧致新生大鼠肺损伤中的动态变化及意义

Dynamic changes of CXCL12/CXCR4 in neonatal rats with hyperoxia-induced lung injury and their significance

目的检测趋化因子12(CXCL12)[又名基质细胞衍生因子-1(stromal cell derived factor 1,SDF-1)]及其受体(Cys-X-Cys receptor 4,CXCR4)在高氧致新生大鼠肺损伤中的变化,初步探讨其在新生大鼠高氧肺损伤中的作用及可能机制。方法 SD新生大鼠64只,按随机数字表达法分为空气对照组和高氧组,高氧组吸入氧体积分数≥0.95(95%O2)的高氧建立高氧肺损伤动物模型。高氧刺激3、7、14、21 d后分别取2组新生大鼠行肺组织病理学检查;水解法测肺组织羟脯氨酸含量;实时荧光定量PCR检测肺组织CXCL12和CXCR4 mRNA;Western blot检测肺组织CXCR4蛋白。结果病理学检查显示,高氧组肺组织炎症明显,结构紊乱,高氧暴露时间越长,损伤越明显。肺组织羟脯氨酸的含量在高氧刺激14 d和21 d后[(493.69±127.50)、(582.55±174.78)μg/g]明显高于空气对照组[14 d(327.52±46.97)μg/g(P<0.05),21 d(321.27±60.63)μg/g(P<0.01)]。高氧组CXCL12 mRNA表达在高氧刺激14 d及21 d后[(2.12±1.08)、(2.68±0.87)]均高于相应对照组[0.68±0.22(P<0.05),0.51±0.18(P<0.01)],CXCR4 mRNA表达在高氧刺激7、14、21 d后(0.53±0.23、0.36±1.15、0.31±0.19)均低于相应对照组[(2.80±1.14、2.71±1.26,P<0.05),(2.93±0.14,P<0.01)]。肺组织CXCR4蛋白的表达高氧刺激7、14、21 d后(2.06±0.64、2.84±0.83、1.38±0.34)均高于相应对照组[1.37±0.41(P<0.05),0.81±0.27(P<0.01),0.85±0.23(P<0.05)]。结论 CXCL12/CXCR4可能在高氧肺损伤的炎症反应和纤维化过程中发挥了重要作用。

Objective To study the role of chemotatic factor 12（CXCL12）,also known as stromal cells-derived factor 1（SDF-1）,and its Cys-X-Cys receptor 4（CXCR4） in hyperoxia-induced lung injury and its possible mechanism.Methods Sixty-four Sprague-Dawley neonatal rats were randomly divided into control group and hyperoxia group.An animal model of hyperoxia-induced lung injury was established by inhaling ≥95%O2.After 3,7,14,and 21 days＇ inhaling,the rats were killed and lung tissue samples were taken for pathological examination.Hydroxyproline level in lung tissue samples was measured with the hydrolysis method.Expression of CXCL12,CXCR4 mRNA and CXCR4 protein in lung tissue samples was detected by real-time polymerase chain reaction（RT-PCR） and Western blotting,respectively.Results Pathological examination showed significant inflammation and structural disorder in lung tissue of hyperoxia group.The longer the exposure to hyperoxia was,the severer the injury was.The hydroxyproline level in lung tissue samples was significantly higher in hyperoxia group than in control group after exposure to hyperoxia for 14 and 21 d（493.69±127.50 μg/g and 582.55±174.78μg/g vs 327.52±46.97μg/g and 321.27±60.63 μg/g,P0.05 or P0.01）.The expression level of CXCL12 mRNA was markedly higher in hyperoxia group than in control group after exposure to hyperoxia for 14 and 21 d（2.12±1.08 and 2.68±0.87 vs 0.68±0.22 and 0.51±0.18,P0.01）.However,the expression level of CXCR4 mRNA was significantly lower in hyperoxia group than in control group（0.53±0.23,0.36±0.15 and 0.31±0.19 vs 2.80±1.14,2.71±1.26 and 2.93±0.14,P0.05）after exposure to hyperoxia for 7,14,and 21 d,while the expression level of CXCR4 protein was significantly higher in hyperoxia group than in control group after exposure to hyperoxia for 7,14 and 21 d（2.06±0.64,2.84±0.83 and 1.38±0.34 vs 1.37±0.41,0.81±0.27 and 0.85±0.23,P0.05）.Conclusion CXCL12/CXCR4 may play an important role in inflammatory reaction and fibrosis of hyperoxia-induced lung injury.