AT2R基因在体转染抑制大鼠颈动脉新生内膜增生

目的: 探讨AngⅡ 2型受体（AT2R）基因在体转染对大鼠颈动脉球囊损伤后新生内膜增生的抑制作用。方法:大鼠颈动脉球囊损伤后，局部转染AT2R重组腺病毒载体（pAdCMV/AT2R）或空病毒载体（pAd-GFP），于术后7、14和21 d用RT-PCR、免疫组织化学及HE染色方法，进行AT2R、AngⅡ 1型受体(AT1R)、PCNA在颈动脉壁中表达的变化及定量组织形态学分析；免疫荧光双标染色和激光共聚焦技术检测血管中AT2R与PCNA表达的关系。结果: pAdCMV/AT2R转染后，大鼠颈动脉AT2R的表达水平显著高于未转染组和pAd-GFP组(P<0.01)，21 d时仍维持较强表达。在14 d时pAdCMV/AT2R组PCNA阳性表达率显著低于未转染组和pAd-GFP组［(27.29±5.81)% vs ( 72.25±4.47)%、(68.43±9.12)%，P<0.01］，在AT2R表达阳性的部位PCNA表达阴性。在21 d时，pAdCMV/AT2R组的内膜面积与中膜面积比显著低于未转染组和pAd-GFP组(0.78±0.06 vs 1.44±0.22、1.36±0.21, P<0.01)，pAd-GFP组和未转染组间无显著差异（P>0.05）；各组颈动脉AT1R表达水平无显著差异(P>0.05)。结论: AT2R基因在体转染可抑制球囊损伤后大鼠颈动脉平滑肌细胞增殖和新生内膜增生，AT2R基因转染后表达并发挥其生物学作用时，AT1R和AT2R之间不存在表达量上此起彼伏的关系，可能是建立在信号转导基础上的功能调节关系。

AT2R gene transfer to rat carotid arteries inhibits neointimal hyperplasia after balloon angioplasty

AIM: To study the effects of angiotensin Ⅱ type 2 receptor (AT2R) gene transfer on neointimal hyperplasia in rat carotid arteries after balloon angioplasty. METHODS:AT2R gene was transfected into rat carotid arteries with pAdCMV/AT2R after the establishment of rat carotid balloon injury restenosis model. The arteries were harvested at 7 days, 14 days and 21 days after gene transfer. The expression of AT2R, AT1R, PCNA in arteries and morphology analysis were evaluated by RT-PCR, immunohistochemistry and HE staining. The expressions of AT2R and PCNA were measured by double immunofluorescence staining and confocal microscope. RESULTS:pAdCMV/AT2R delivered into injured rat carotid arteries significantly up-regulated the levels of AT2R mRNA and protein in neointima from day 7 to day 21, but the levels of AT1R was not significantly different (P>0.05). pAdCMV/AT2R transfection significantly decreased the expression of PCNA in neointima at day 14 ［(27.29±5.81)% vs ( 72.25±4.47)%, (68.43±9.12)%，P<0.01］. At day 21, compared with no transfection group and pAd-GFP transfection group, pAdCMV/AT2R transfection reduced I/M (intimal/medial area) ratio significantly (0.78±0.06 vs 1.44±0.22, 1.36±0.21， respectively, P<0.01). No significant difference between pAd-GFP group and no transfection group was observed. CONCLUSION: Gene transfer of AT2R from lumen may effectively inhibit VSMC proliferation and neointimal hyperplasia in the rat carotid arteries after balloon angioplasty. The cross-talk between AT1R and AT2R may operate via signaling pathway, but not via counteraction of receptor expression.