IL-12对小鼠哮喘模型Th亚群和气道炎症的影响

Effects of interleukin-12 on T helper cell subsets and airway inflammation in murine models of asthma

目的观察腹腔注射IL-12对哮喘小鼠Th亚群的调节和气道炎症的影响,并寻找更有效的干预阶段。方法将36只BALB/c小鼠分为4组,每组9只,分别为哮喘组、IL-12干预A组、IL-12干预B组及正常对照组。采用卵白蛋白(OVA)腹腔注射致敏加雾化吸入激发的方法制成哮喘模型,正常对照组小鼠同时以等量的生理盐水腹腔注射加雾化吸入。干预A组在致敏和激发阶段均给予IL-12腹腔注射进行干预,干预B组仅在激发阶段给予IL-12腹腔注射进行干预。最后1次激发结束后24h处死所有小鼠,取左肺作病理切片(HE染色),右肺提取总RNA并逆转录成cDNA后,应用半定量RT-PCR法检测肺组织内IFN-γ基因mRNA的转录表达情况,实时定量PCR法检测肺组织内IL-4基因mRNA的转录表达情况。结果与正常对照组相比,哮喘组小鼠肺组织内IFN-γmRNA表达显著减少(P<0.05),IL-4mRNA表达显著增多(P<0.05);与哮喘组相比,IL-12干预A、B组小鼠肺组织内IFN-γmRNA表达均显著增多(P均<0.05),IL-4mRNA表达均显著减少(P均<0.05)。干预A组与干预B组相比,IL-4mRNA的表达水平差异有统计学意义(P<0.05),而IFN-γmRNA表达水平差异无统计学意义(P>0.05)。结论IL-12能有效纠正哮喘小鼠失衡的Th亚群及控制气道炎症;致敏、激发阶段同时干预与仅激发阶段的干预均能有效的抑制Th2型免疫反应和气道炎症改变,前者能更有效的降低IL-4mRNA的表达水平。

Objectives To investigate the effects of interleukin-12（IL-12）on the T helper cell subsets and airway inflammation in murine model of asthma and to evaluate a more effective stage of intervention. Methods Thirty-six BALB/c mice were randomly divided into 4 groups（nine in each）：asthma group, IL-12 treated group A,IL-12 treated group B,and normal control group. The murine model of asthma was established by intraperitoneal injection（sensitization） and nebulization of ovalbumin（OVA）（challenge）. Mice in normal control group were treated with normal saline（0.9% NS）instead of OVA. IL-12 treated group A mice were treated with intraperitoneal injection of IL-12 at both stages of sensitization and challenge. IL-12 treated group B mice received intraperitoneal IL-12 at challenge stage. All mice were sacrificed 24 hours after the last challenge. Tissues of the left lungs were collected for pathological assessment（H＆E）and tissues of the right lungs were collected for extraction of total RNA. The mRNA expression level of cytokines（IFN-γ and IL-4）were measured by semi-quantitative reverse-transcription polymerase chain reaction（RT-PCR）and real-time PCR technique,respectively. Results The level of IFN-γ mRNA was significantly lower（P 〈 0.05）and the level of IL-4 mRNA was significantly higher（P 〈 0.05）in the asthma group,when compared with the normal control group. The levels of IFN-γ were significantly higher（both P 〈 0.05）,while levels of IL-4 were lower（both P 〈 0.05）in IL-12 treated groups A and B,when compared with the asthma group. There was significant difference in the level of IL-4 mRNA between IL-12 treated group A and group B（P 〈 0.05）,but not the level of IFN-γ mRNA（P 〉 0.05）. Conclusions This study suggested that intraperitoneal injection of IL-12 might effectively reverse the imbalance of Th cell subsets in murine model of asthma and inhibit the antigen-induced airway inflammation. Intervention either at stages of sensitization and challenge or only at the challenge stage produced similar effects. However intervention at both stages would markedly reduce the level of IL-4 mRNA.