血红素氧合酶-1抗氧化、抑制细胞凋亡作用已得到证实,阻断其作用,损伤加重[2~4]。HO-1作为体内重要的抗氧化酶,在LPS注入后表达增加、活性增强[7,8]。HO-1还可诱导自身表达,在再灌注损伤中起保护作用[9]。HO-1的ALI保护作用与本身及其降解血红素代谢产物(胆绿素、Fe2+和CO)有关。HO能降解催化产生自由基和脂质过氧化的血红素,直接参与清除自由基,抑制前炎症介质产生,增加抗炎介质的表达,保护细胞避免凋亡[2~4,7~9]。HO-1代谢产物胆绿素和其还原产物胆红素是强有力的抗氧化剂,胆绿素保护细胞脂质膜的过氧化,胆红素清除自由基,保护不饱和脂肪酸的过氧化,二者还能抑制炎症细胞的趋化、粘附,抑制由自由基和炎症介质诱导的细胞凋亡。HO-1源性Fe2+和HO-1本身能促进铁蛋白合成,减轻细胞内因高铁催化的脂质过氧化和Fenton反应[7],细胞内铁浓度降低,凋亡减少。CO作为HO-1最重要的代谢产物,能阻止炎症细胞肺内浸润、抑制其活化及与细胞粘附,加快凋亡,终止炎症反应的扩大[10]。CO清除氧自由基,减轻自由基造成的损害,增强拮抗自由基诱导的凋亡;此外,CO还调控凋亡相关基因,保护细胞避免凋亡。 HO-1活性可通过检测血中COHb水平了解[8],本实验中,LPS注入后,HO-1表达增加,COHb升高,提示HO-1活性增强,在预先注入ZnPP后,HO-1表达下降,活性亦降低。 总之,脂多糖诱导大鼠肺组织HO-1表达上调及细胞凋亡增加参与了ALI的发病,表达上调的HO-1有助于抑制细胞凋亡,减轻肺损伤。 参考文献 1. Bosma K,Fanelli V,Ranieri M. Acute respiratory distress syndrome;update on the latest developments in basic and clinical research. Intensive Care Medicine,2005,18;137-145. 2. Choi A M K,Alam J. Heme oxygenase-1;function,regulation,and implication of novel stress-inducible protein in oxidant-induced lung injury. Am J Respir Cell Mol Biol,1996,15;9-19. 3. Petrache I,Otterbein LE,Alam J,et al. Heme oxygenase-1 inhibits TNF-a-induced apoptosis in cultured fibroblasts. Am J Physiol,2000,278;L312-L319. 4. Lang D,Reuter S,Buzescu T,et al. Heme-induced heme oxygenase (HO-1) in human monocytes inhibits apoptosis despite caspase-3 up-regulation. International Immunology,2004,17;155-165. 5. Smith K M,Mrozek J D,Simonton S C,et al. Prolonged partial liquid ventilation using conventional and high-frequency ventilatory techniques;Gas exchange and lung pathology in an animal model of respiratory distress syndrome. Crit Care Med,1997,25;1888-1897. 6. Vogt B A,Alam J,Croatt A J,et al. Acquired resistance to acute oxidative stress;Possible role of heme oxygenase and ferritin. Lab Invest,1995,72;474-483. 7. Vreman H J,Stevenson D K. Detection of heme oxygenase activity by measurement of carbon monoxide;Current protocols in toxicology. New York;Wiley Sons,1999,9;10-10. 8. Yoshida T,Maulik N,Ho YS,et al. H(mox-1) constitutes an adaptive response to effect antioxidant cardioprotection;A study with transgenic mice heterozygous for targeted disruption of the heme oxygenase-1 gene. Circulation,2001,103;1695-1671. 9. Miynanaki H,Yamada H,Ohta M,et al. The effects of inhaled carbon monoxide on lung injury in rats caused by lipopolysaccharide. Masui,2003,52;363-369. 10. Brouard S,Otterbein LE,Anrather J,et al. Carbon monoxide generated by heme oxygenase 1 suppresses endothelial cell apoptosis. J Exp Med,2000,192;1015-1025. 11. Zhang X,Shan P,Alam J,et al. Carbon monoxide modulates Fas/Fas ligand,caspases,and Bcl-2 family proteins via the p38 mitogen activated protein kinase pathway during ischemia-reperfusion lung injury. J Biol Chem,2003,278;22061-22070. |