【摘要】 目的探讨空肠弯曲菌(CJ)脂多糖(LPS)中唾液酸(SA)基团参与CJ诱发周围神经病关键性抗原成分的重要地位,为CJLPS与神经节苷脂间的分子模拟推论确立免疫病理学证据。方法构建唾液酸合成酶基因1(neuB1)失活、LPS外核寡糖缺乏SA基团的GBS相关CJO:19变异株。分别以野生株和变异株LPS全身免疫豚鼠,ELISA法检测免疫血清中抗CJLPS和抗神经节苷脂GM1IgG抗体,取坐骨神经作病理学检查。再将免疫血清行坐骨神经外膜下注射并作病理学检查。结果(1)PenO:19CJ变异株的neuB1失活、LPS中SA基团缺失;(2)野生株LPS和变异株LPS全身免疫后,豚鼠均产生高滴度抗LPS特异性IgG;(3)全身免疫后第21、35天,野生株LPS免疫血清中检测到抗GM1IgG抗体,而变异株LPS免疫血清中却测不到该抗体;(4)野生株LPS组中有17.3%的坐骨神经原纤维发生以轴索变性为主(占65.0%)的免疫性损伤,与变异株LPS组比较差异有统计学意义(χ2=125,P<0.01)。而变异株LPS组病变率仅2.4%,与对照组比较差异没有统计学意义(P>0.05);(5)野生株LPS免疫血清神经外膜下注射后,67.8%的豚鼠坐骨神经原纤维发生以轴索变性为主(占68.0%)的病变,而变异株LPS免疫血清注射后仅3.2%的神经原纤维发生病变,差异具有统计学意义(P<0.01)。结论外核寡糖缺乏SA基团的GBS相关CJO:19变异株LPS不再能使实验动物血清中产生高滴度的抗GM1抗体,同时丧失对周围神经的免疫致病力,表明含SA基团的LPS寡糖侧链,是CJ诱发周围神经病的GM1样关键性抗原,从免疫病理学角度证实有关CJ诱发GBS的分子模拟推论。更多还原

【Abstract】 Objective To explore the important role of the terminal residues containing sialic acid (SA) in Campylobacter jejuni (CJ) lipopolysaccharide(LPS) as the critical antigen to induce nerve damage, and also to identify immunopathological evidence for the hypothesis of molecular mimicry and cross-immunity between CJ LPS and gangliosides.Methods A mutant of Pen O:19 CJ with neuB1 gene inactivated and LPS outer core terminal residues losing SA was to be constructed.PCR and RT-PCR were used to confirm the mutant.Capability of CJ LPS binding to cholera toxin B subunit (CTB) was tested.Guinea pigs were systematically immunized with LPS of the wild and the mutant strains, respectively.Titers of anti-LPS and anti-ganglioside GM1 IgG antibodies in sera of immunized guinea pigs were detected by ELISA.Pathological study for sciatic nerves of both Guinea pigs either immunized systematically or perineural injection with their immunized serum was finished. Results (1)The mutant of CJ O:19 strain with inactivated neuB1 gene was successfully constructed and lost transcriptional activity of neuB1 gene in the mutant strain was confirmed by PCR and RT-PCR.SA was well demonstrated by both acidic ninhydrin reaction and periodate-resorcinol reaction in the LPS of wild strain but not in the mutant LPS; (2)Compared with the titers before immunization, the titers of anti-GM1 IgG antibody increased in sera of guinea pigs immunized with LPS of the wild strain.However there were no detectable anti-GM1 IgG antibody in sera of the animals immunized with mutant LPS and PBS.(3)The incidence of pathological fibers of sciatic nerves in wild CJ LPS group (17.3%)was significantly higher than the mutant CJ LPS group(χ 2=125,P<0.01); the difference between the mutant CJ LPS group and control group was not statistically significant(χ 2=1.633,P>0.05).(4)After perineural injection with immunized serum, the incidence of pathological fibers of sciatic nerves in wild strain group (67.8%)was also significantly higher than the incidence of mutant group(P<0.01). Conclusion A mutant of CJ O:19 strain neuB1 gene inactivated and SA component of terminal structure of LPS lost was successfully constructed.And it no longer expressed SA component which is the normal terminal structure of LPS in wild strain.The capability of the wild strain to induce increased titers of anti-GM1 antibody and immune-mediated nerve damage was simultaneously lost for the mutant strain.It could be a strong immunopathologic evidence to identify the molecular mimicry hypothesis between CJ LPS and ganglioside epitope in nerve on the pathogenesis of CJ related GBS.The terminal residues containing SA should be as the basic GM1-like structure in CJ LPS.更多还原