卡介苗胞壁蛋白增强肺抗铜绿假单胞菌感染防御功能的研究

目的 观察卡介苗胞壁蛋白组分能否提高大鼠肺组织对铜绿假单胞菌的清除率.方法 密度梯度离心和分子筛方法分离卡介苗胞壁蛋白组分.用Northern 杂交和RT-PCR检测卡介苗全菌体及其胞壁蛋白组分对肺上皮SPC-A-1细胞β防御素hBD-1 mRNA表达的刺激作用;腹腔注射卡介苗胞壁蛋白组分48 h后,经气管滴入铜绿假单胞菌或金黄色葡萄球菌,24 h后处死大鼠,取肺组织进行菌落计数.结果 卡介苗胞壁蛋白经分子筛层析后主要得到两大组分,Tricine-SDS-PAGE鉴定组分2相对分子质量约为18×103～30×103.Northern杂交显示热灭活卡介苗能提高肺上皮细胞β防御素hBD-1 mRNA表达,RT-PCR显示胞壁蛋白组分2刺激作用明显强于全菌体.经胞壁蛋白组分2治疗的大鼠肺组织铜绿假单胞菌数低于阴性对照组(P＜0.01),而对金黄色葡萄球菌感染无明显抵抗作用.结论 卡介苗胞壁蛋白组分可提高肺组织对铜绿假单胞菌的清除率,增强肺抗感染防御能力.

BCG Cell Wall Proteins Enhance Clearance of Pseudomonas aeruginosa in Rat Lungs

OBJECTIVE: To test the function of BCG cell wall proteins in enhancing the clearance of Pseudomonas aeruginosa in rat lungs. METHODS: The BCG cells were broken by supersonic technique. The cell wall proteins were isolated by discontinues sucrose density-gradient centrifugation, and fractionated by Sephadex G-150 chromatography. The relative molecular mass of the isolated proteins was analyzed by SDS-PAGE. The hBD-1 gene mRNA expression in the SPC-A-1 cells was identified by Northern blot and RT-PCR. The cell wall component was injected intraperitoneally to the rats. Forty eight hours later, 5 X 10(6) CFU of P. aeruginosa ATCC27853 or Staphylococcus aureus ATCC25923 were inoculated via trachea. The bacteria colony in the supernatant of the homogenated lungs of the rats was counted 24 hours after the inoculation. RESULTS: Two protein components of BCG cell wall were fractionated. The relative molecular mass of component 2 was in the range of 18 X 10(3) -30 X 10(3). The hBD-1 mRNA expression detected by Northern blot was markedly enhanced by the stimulation of heat-inactivated BCG whole cells. The BCG-induced hBD-1 mRNA expression in the SPC-A-1 cells detected by RT-PCR was mainly contributed by fraction 2 of the BCG cell wall proteins. The bacteria decreased significantly in the lungs of the rats with the injection of BCG component 2 (n=8, P<0. 01). CONCLUSION: The fraction (relative molecular mass is 18 X 10(3) -30 X 10(3)) of BCG cell wall proteins improve the defense of rat lungs against P. aeruginosa infection.