外源性EGF促进吸入性损伤大鼠肺泡Ⅱ型细胞增殖和肺水转运

Exogenous epidermal growth factor stimulates proliferation of alveolar type Ⅱ cells and promotes transepithelium liquid transport in rats with smoke inhalation injury

目的:研究表皮细胞生长因子(epidermal growth factor,EGF)对吸入性损伤大鼠的肺泡Ⅱ型细胞(alveolar typeⅡcell,ATⅡ)增殖和肺水转运功能的影响。方法:清洁级雄性 SD 大鼠160只,160～180g。随机分为四组:Ⅰ组:正常对照(n=10);Ⅱ组:单纯 EGF 给药;Ⅲ组:单纯吸入性损伤;Ⅳ组:吸入性损伤+EGF 治疗。Ⅱ、Ⅲ、Ⅳ组各分为24、48、72、120、168h 五个亚组(n=10)。Ⅲ组和Ⅳ组的大鼠先造成烟雾吸入性损伤。Ⅱ组和Ⅳ组(伤后立即)用特殊针头经气管喷入 EGF(100μg/kg)。每组中6只大鼠用于检测肺泡液体清除率(alveolarliquid clearance,ALC),4只用于病理形态学观察和尿嘧啶脱氧核苷(bromodeoxyuridine,BrdU)免疫组化检查。结果:烟雾吸入性损伤可以导致各级支气管管壁水肿,肺泡壁破坏,肺泡腔内液体聚积,肺泡隔水肿。外源性EGF 显著增加新增殖 ATⅡ数量。正常大鼠 ALC 为(22.07±3.67)%。气管滴入 EGF 后48、72和120h 的 ALC显著升高,分别为[(43.37±11.04)%,(P<0.01);(41.75±7.02)%,(P<0.01);(35.86±4.09)%,(P<0.05)],168h 后恢复正常水平。吸入性损伤后 ALC 在第24h 下降36.7%,其他时间点 ALC 也有不同程度减少。EGF 治疗可以使吸入性损伤大鼠的 ALC 在48h 后即可恢复到正常水平[(25.25±3.66)%]。结论:外源性 EGF经气管喷入,能有效刺激 ATⅡ的增殖,提高肺泡液体转运能力,有助于修复吸入性损伤大鼠的肺泡组织,减轻或消除肺水肿。

Objective:To investigate the effects of intratracheal administration of epidermal growth factor (EGF) on alveolar type Ⅱ cells (ATⅡ) in rats with inhalation injury.Methods:160 Spraue-Dawley rats weighting 160- 180g were randomly divided into four groups:group Ⅰ normal controls (n=10);group Ⅱ(n=50):intratracheal EGF administration;group Ⅲ(n=50),smoke inhalation;and group Ⅳ(n=50):smoke inhalation + intratra- cheal EGF admininstration.The animals in group Ⅱ,Ⅲ and Ⅳ were sacrificed at 24,48,72,120 and 168h after smoke inhalation injury to evaluate the proliferation of ATⅡ and changes in transepithelial transportation of liq- uid.EGF (100μg/kg)was instilled into the tracheas with a special needle in the rats of group Ⅱ and group Ⅳ. Alveolar liquid clearance (ALC) was measured with a ^(125)Ⅰ-albumin method.Anti-BrdU immunohistochemsitry staining was employed to evaluate the proliferation of ATⅡ cells.Results:ALC in group I was measured to be (22.07±3.67)%.After instillation of EGF,it was significantly increased to (43.37±11.04)% at 48h (P<0. 01),(41.75±7.02)% at 72h (P<0.01),and (35.86±4.09)% at 120h (P<0.05),respectively,and recovered to baseline level at 168h.Smoke inhalation resulted in a decrease by 36.7% in ALC level at the initial 24h,and continued to be lowered at the rest intervals.Intratracheal administration of EGF significantly increased ALC and returned it to (25.25±3.66)%,which tended to return to the baseline level at 48h after EGF instillation.Mor- phological studies showed that there were more proliferated AT Ⅱ cells in group Ⅳ than Ⅲ.Conclusion:It was demonstrated that intratracheal instillation of EGF could stimulate the proliferation of AT Ⅱ cells,and promote the transepithelial liquit transportation in rats following inhalation injury.The results provided reliable evidence that EGF have potential beneficial effect in the treatment of inhalation injury or acute lung injury.