Muehlethaler Vincent, Kunig Anette M, Seedorf Gregory, Balasubramaniam Vivek, Abman Steven H
Pediatric Heart Lung Center, Dept. of Pediatrics, Univ. of Colorado School of Medicine and The Children's Hospital, Mail Stop 8317, PO Box 6511, Aurora, CO 80045' USA.
Am J Physiol Lung Cell Mol Physiol. 2008 Jan;294(1):L110-20. doi: 10.1152/ajplung.00407.2007. Epub 2007 Nov 9.
We hypothesized that abnormal fetal lung growth in experimental congenital diaphragmatic hernia after maternal nitrofen exposure alters lung structure due to impaired VEGF signaling, which can be reversed with VEGF or nitric oxide (NO) treatment. Timed-pregnant Sprague-Dawley rats were treated with nitrofen on embryonic day 9 (E9), and fetal lungs were harvested for explant culture on E15. Explants were maintained in 3% O2 for 3 days and were treated with NO gas or recombinant human VEGF protein for 3 days. To determine the effects of VEGF inhibition on lung structure, normal fetal lung explants were treated with SU-5416, a VEGF receptor inhibitor, with or without exogenous NO or VEGF. We found that nitrofen treatment impaired lung structure, as evidenced by decreased branching at day 0, but lung structure was not different from controls after 3 days in culture. Nitrofen reduced lung VEGF but not endothelial NO synthase protein level. Treatment with NO enhanced lung growth in control and nitrofen-exposed lungs; however, the response to NO in the nitrofen-treated lungs was reduced when compared with controls. VEGF treatment did not cause a further increase in lung complexity after nitrofen exposure. SU-5416 treatment altered lung structure, which improved with NO but not VEGF treatment. Both nitrofen and SU-5416 treatment increased apoptosis in the mesenchyme of fetal lung explants. We conclude that nitrofen exposure increased apoptosis, decreased lung growth and reduced VEGF expression, and that exogenous NO but not VEGF treatment enhances lung growth. Disruption of lung architecture after VEGF receptor blockade was similar to nitrofen-induced changes but was more responsive to NO.
我们推测，母体接触硝苯呋海因后实验性先天性膈疝中异常的胎儿肺生长会因VEGF信号受损而改变肺结构，而VEGF或一氧化氮（NO）治疗可使其逆转。将定时受孕的Sprague-Dawley大鼠在胚胎第9天（E9）用硝苯呋海因处理，在E15收获胎儿肺进行外植体培养。外植体在3%氧气中培养3天，并用NO气体或重组人VEGF蛋白处理3天。为了确定VEGF抑制对肺结构的影响，正常胎儿肺外植体用VEGF受体抑制剂SU-5416处理，同时或不同时给予外源性NO或VEGF。我们发现，硝苯呋海因处理会损害肺结构，在第0天可见分支减少，但培养3天后肺结构与对照组无差异。硝苯呋海因降低了肺VEGF水平，但不影响内皮型NO合酶蛋白水平。用NO处理可促进对照组和接触硝苯呋海因的肺的生长；然而，与对照组相比，硝苯呋海因处理的肺对NO的反应减弱。硝苯呋海因暴露后，VEGF处理并未使肺的复杂性进一步增加。SU-5416处理改变了肺结构，用NO处理可改善，但用VEGF处理则无改善。硝苯呋海因和SU-5416处理均增加了胎儿肺外植体间充质中的细胞凋亡。我们得出结论，接触硝苯呋海因会增加细胞凋亡、减少肺生长并降低VEGF表达，外源性NO而非VEGF治疗可促进肺生长。VEGF受体阻断后肺结构的破坏与硝苯呋海因诱导的变化相似，但对NO更敏感。
