外源性硫化氢对大鼠内毒素性肺损伤的影响及机制研究

Effect of exogenous hydrogen sulfide on polymorphonuclear neutrophil accumulation in acute lung injury rat induced by lipopolysaccharides and its mechanism

目的：应用H2S供体硫氢化钠（NaHS）,观察外源性H2S对中性粒细胞（PMN）在脂多糖（LPS）刺激大鼠肺内聚集的影响及其机制。方法：采用尾静脉注射致Sprague-Dawley（SD）大鼠内毒素急性肺损伤（ALI）模型,将大鼠随机分为4组（n=8～12）。对照组：由尾静脉注射无菌生理盐水（0.5ml/kg）;LPS组：由尾静脉注射LPS（1mg/kg）;LPS＋NaHS组：注射LPS前10min腹腔注射NaHS（28μmol/kg）;NaHS组：腹腔注射NaHS（28μmol/kg）。6h后光镜下观察各组大鼠肺组织学变化并计数肺泡间隔中PMN数目（number/HP）;脱氧核苷酸末端转移酶介导的原位末端标记技术（TUNEL）测定支气管肺泡灌洗液（BALF）中PMN凋亡百分率及应用Western blot检测肺组织细胞间黏附分子（ICAM）-1和核转录因子（NF）-κB表达的变化。结果：注射LPS后动物肺组织出现出血、水肿及PMN聚集等病理征象。LPS组大鼠肺组织中PMN数目较对照组显著增加,PMN凋亡百分率下降,ICAM-1、NF-κB表达显著增高;应用NaHS后每高倍镜PMN数目显著减少,PMN凋亡百分率明显增高,ICAM-1、NF-κB表达显著降低,肺组织损伤减轻。单独应用NaHS组大鼠上述各项指标与对照组大鼠相比无显著差异。结论：NaHS可减少PMN在肺内聚集,其机制与其抑制NF-κB通路,从而下调ICAM-1表达、促进PMN凋亡有关。

Objective：To study the effects of sodium hydrosulfide （NaHS）, hydrogen sulfide （H2S） donor, on LPS-induced polymorphonuclear neutrophil （PMN） accumulation and its mechanism. Methods： The animal model of acute lung injury （ALI） caused by intravenous injection of lipopolysaccharides （LPS）. Adult male Spraguce-Dawley （SD） rats were randomly divided into four groups（n=8～12 per group）： Control group （0.5 ml/kg normal saline i.v.）, LPS-treated group （1 mg/kg, i.v.）, LPS plus NaHS（1 mg/kg i.v. and 28 μmol/kg i.p., respectively） and NaHS group （28 μmol/kg i.p.）. Animals were sacrificed at 6 h after agent administration. Morphological changes of lung tissues were observed and polymorphonuclear neutrophil （PMN） number in alveolar septum was tested. The apoptosis of PMN in the bronchoalveolar lavage fluid （BALF） was examined with in situ TdT-mediated dUTP end labeling（TUNEL）. Intercellular adhesion factor-1 （ICAM-1） and nuclear factor-κB（NF-κB） expressions in the lung tissue were analyzed by Western Blot. Results： The results showed that bleeding, edema, PMN accumulation and other pathological signs in the lung tissue emerged after LPS injection. Compared to control rats, the LPS-treated rats had increased PMN number, decreased PMN apoptotic percentages, and increased expressions of ICAM-1 and NF-κB. Administration of NaHS into LPS-treated rats reduced the PMN number and expressions of ICAM-1 and NF-κB but increased PMN apoptotic percentages. In addition, NaHS alleviated the degree of ALI. There were no significant differences of the above indicators between NaHS-treated rats and control rats. Conclusion： NaHS can reduce the PMN accumulation in the lung, and its mechanism is related to down-regulation expression of ICAM-1 and promotion of PMN apoptosis induced by inhibition of NF-κB pathway.