双歧杆菌对内毒素损伤幼年大鼠肠道血管内皮细胞粘附分子－1的影响

Effect of bifidobacteria on ileum intercellular adhesion molecule-1 expression in young rats with endotoxin-induced intestinal damage

摘要:

目的：双歧杆菌是肠黏膜屏障中生物屏障的主要成分，参与了宿主的消化、营养、代谢、吸收、免疫及抗感染过程，然而其具体的作用机制目前还不清楚。该研究欲探讨双歧杆菌对内毒素损伤幼年大鼠血清和回肠组织的丙二醛（MDA）含量和小肠绒毛间质血管内皮细胞粘附分子-1（ICAM-1）表达的影响。方法：腹腔注射内毒素制造内毒素损伤动物模型（模型组，E组），治疗组（T组）提前7 d给予双歧杆菌灌胃，同时设对照组（C组，腹腔注射生理盐水），于不同时间点处死后检测血清和肠组织中MDA的含量，并用免疫组织化学和逆转录-聚合酶链反应（RT-PCR）方法检测小肠组织ICAM-1蛋白质和核酸水平的变化。结果：E组血清和小肠MDA含量较对照组增加，以6 h增加明显（肠组织：99.88±12.62 nmol/mg prot vs 84.25±12.96 nmol/mg prot，P<0.05；血清：1.67±0.30 nmol/mL vs 1.13±0.20 nmol/mL，P<0.05）；T组MDA含量（6 h：肠组织92.75±9.28 nmol/mg prot；血清1.17±0.23 nmol/mL）较E组下降；E组小肠组织ICAM-1蛋白质和核酸表达增加，分别以6 h和2 h为著，T组改变低于E组（P<0.05）。 结论：内毒素损伤幼鼠血清和小肠MDA含量增加，同时ICAM-1蛋白质和mRNA表达增加，外源性给予双歧杆菌能降低内毒素组MDA和ICAM-1的增加，表明双歧杆菌能通过抑制大鼠体内的MDA含量和ICAM-1的表达而起到一定的肠道保护作用。［中国当代儿科杂志，2007，9（4）：375-378］

Abstract:

OBJECTIVE: To investigate the effects of bifidobacteria on malondialdehyde (MDA) content and intercellular adhesion molecule-1 (ICAM-1) expression in serum and ileum tissues of young rats with endotoxin-induced intestinal damage, and possible protective mechanisms of bifidobacteria on intestines. METHODS: Eigteen-day-old Wistar rats were randomly administered with normal saline (NS), lipopolysaccharide (LPS, 5 mg/kg) or LPS + bifidobacteria. Bifidobacteria (0.5 mL, twice a day) was intragastrically administrated 7 days prior to LPS injection until the end of the experiment. MDA contents in serum and ileum were detected by the TBA method. Expression of ICAM-1 protein and mRNA were evaluated by immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) after 2, 6, 24 and 72 hrs of LPS injection. RESULTS: The serum and ileum MDA contents in the untreated LPS group increased significantly and reached a peak at 6 hrs of LPS injection when compared with the NS control group (ileum: 99.88±12.62 nmol/mg prot vs 84.25±12.96 nmol/mg prot, P<0.05; serum: 1.67±0.30 nmol/mL vs 1.13±0.20 nmol/mL, P<0.05). The MDA contents in ileum (92.75±9.28 nmol/mg prot) and serum (1.17±0.23 nmol/mL) in the bifidobacteria-treated group at 6 hrs of LPS injection were significantly lower than in the LPS group (P <0.05）.The expression of ICAM-1 protein in the untreated LPS group remarkably increased at 6, 12, 24 and 72 hrs of LPS injection when compared with the NS control group (P<0.01). The bifidobacteria-treated group displayed lower ICAM-1 protein levels than the untreated LPS group at 72 hrs of LPS injection (P<0.01). The ICAM-1 mRNA expression in the untreated LPS group significantly increased at 2hrs of LPS injection when compared with the NS control group (P<0.01). The ICAM-1 mRNA expression in the bifidobacteria-treated group began to decrease at 2 hrs of LPS injection and was reduced again at 24 hrs after experiencing increase at 6 and 12 hrs of LPS injection when compared with the untreated LPS group (P<0.01). CONCLUSIONS: The serum and ileum MDA contents and the expression of ICAM-1 protein and mRNA increased in young rats with endotoxin-induced intestinal damage. Bifidobacteria supplementation can decrease MDA contents and inhibit ICAM-1 expressions, thus providing protections for intestines.［Chin J Contemp Pediatr, 2007, 9 (4):375-378］