小潮气量常规机械通气对发育肺生长因子和炎症因子表达的影响

目的：探讨小潮气量常规机械通气对发育肺生长因子（GFs）和炎症因子表达的影响。方法：分别将早产猪（85％孕龄）、足月新生猪及幼猪（4~5周龄）随机分为机械通气组（MV组）和自主呼吸对照组（NMV组）。调节呼吸机参数，使呼出气潮气量维持在6～8 mL/kg，机械通气6 h（早产猪）或24 h（新生猪、幼猪）后检测肺组织GFs（PDGF-B，IGF-I，KGF，HGF，VEGF，TGF-β1）及炎症因子（IL-1β，IL-6，IL-8，TNF-α）mRNA表达，免疫组化方法观察GFs蛋白表达与分布。多组间比较用单因素方差分析或Kruskal-Wallis检验，两组间比较用t检验或Mann-Whitney U检验。结果：①在早产组，MV组PDGF-B，IL-1β，IL-6，IL-8 mRNA水平较NMV组增高（5.11±0.10 vs 4.88±0.01, 4.95±0.27 vs 4.08±0.37, 4.76±0.27 vs 4.00±0.28, 5.31±0.57 vs 4.15±0.46; P<0.01或0.05），IGF-I mRNA水平降低（3.54±0.13 vs 3.80±0.11; P<0.01）；②在足月新生组及幼年组，MV组GFs及炎症因子mRNA水平较NMV组差异均无显著性。结论： 生后早期机械通气干扰了早产肺GFs的表达，并诱发促炎因子表达，促进了肺损伤的发生；但对足月和幼年肺GFs和炎症因子表达无明显影响。

Effects of conventional mechanical ventilation with low tidal volume on the expression of growth factors and inflammatory mediators in developing porcine lungs

OBJECTIVE: To study the effects of conventional mechanical ventilation (CMV) with low tidal volume on developmental porcine lungs by examining the expression of growth factors and inflammatory mediators. METHODS: Twelve preterm piglets born at 99 days of gestational age, 12 term neonatal piglets and 11 young piglets (4-5-weeks old) were randomly placed on CMV or were not ventilated (control group). The ventilator settings were adjusted to provide a tidal volume of 6-8 mL/kg in order to maintain a normal blood-gas value. After 6 hrs (preterm piglets) or 24 hrs (neonatal and young piglets) of mechanical ventilation, the mRNA expression of growth factors PDGF-B, IGF-I, KGF, HGF, VEGF and TGF-beta1 and proinflammatory cytokines IL-1beta, IL-6, IL-8 and TNF-alpha in the lung tissue was measured using RT-PCR. Growth factor protein expression was measured with immunohistochemistry. RESULTS: In preterm piglets, the CMV group had increased mRNA expression of PDGF-B (5.11+/-0.10 vs 4.88+/-0.01), IL-1beta (4.95+/-0.27 vs 4.08+/-0.37), IL-6 (4.76+/-0.27 vs 4.00+/-0.28) and IL-8 (5.31+/-0.57 vs 4.15+/-0.46), but decreased IGF-I mRNA expression (3.54+/-0.13 vs 3.80+/-0.11) compared with those in the control group (P<0.05 or 0.01). In term neonatal piglets and young piglets, there were no significant differences in the mRNA expression of growth factors and proinflammatory cytokines between the CMV and control groups. CONCLUSIONS: CMV caused inflammatory injury in immature lungs by increasing the expression of proinflammatory cytokines and PDGF-B and decreasing IGF-I expression. However, CMV had no effects on pulmonary expression of growth factors and inflammatory mediators in term neonatal piglets and young piglets.